1.
Blast furnace
–
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron, but also others such as lead or copper. The end products are usually molten metal and slag phases tapped from the bottom, the downward flow of the ore and flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchange and chemical reaction process. In contrast, air furnaces are naturally aspirated, usually by the convection of hot gases in a chimney flue, according to this broad definition, bloomeries for iron, blowing houses for tin, and smelt mills for lead would be classified as blast furnaces. Blast furnaces existed in China from about 1st century AD and in the West from the High Middle Ages and they spread from the region around Namur in Wallonia in the late 15th century, being introduced to England in 1491. The fuel used in these was invariably charcoal, the successful substitution of coke for charcoal is widely attributed to Abraham Darby in 1709. The efficiency of the process was enhanced by the practice of preheating the combustion air. The oldest extant blast furnaces were built during the Han Dynasty of China in the 1st century AD. However, cast iron tools and weapons were widespread in China by the 5th century BC. These early furnaces had clay walls and used phosphorus-containing minerals as a flux, the effectiveness of the Chinese blast furnace was enhanced during this period by the engineer Du Shi, who applied the power of waterwheels to piston-bellows in forging cast iron. He suggests that early blast furnace and cast iron production evolved from furnaces used to melt bronze, certainly, though, iron was essential to military success by the time the State of Qin had unified China. Usage of the blast and cupola furnace remained widespread during the Song and Tang Dynasties and this may have happened as early as the 4th century AD. The Chinese blast furnace remained in use well until the 20th century, the backyard furnaces favoured by Mao Zedong during the Great Leap Forward were of this type. In the regions with strong traditions of metallurgy, the production actually increased during this period. In most places in the other than in China, there is no evidence of the use of the blast furnace. Instead, iron was made by reduction in bloomeries. The bloomery process was invented probably in modern-day Xinjiang or other parts of Western China by Hans or Mongols around 800 BC. Iron finds in China proper are few before bloomeries were supplanted by the blast furnace in the 5th century BC which seems to have developed independently in the southern Chinese cultural sphere, in Europe, the Greeks, Celts, Romans, and Carthaginians all used this process. Several examples have found in France, and materials found in Tunisia suggest they were used there as well as in Antioch during the Hellenistic Period
Blast furnace
–
Former blast furnace in Port of Sagunto, Valencia, Spain.
Blast furnace
–
Blast furnace in
Sestao, Spain. The furnace itself is inside the central girderwork.
Blast furnace
–
Part of the gas cleaning system of a blast furnace in
Monclova, Mexico. This one is about to be de-commissioned and replaced.
Blast furnace
–
The left picture illustrates the fining process to make
wrought iron from pig iron, with the right illustration displaying men working a blast furnace of smelting iron ore producing pig iron, from the
Tiangong Kaiwu encyclopedia, 1637
2.
Tennessee Valley Authority
–
The enterprise was a result of the efforts of Senator George W. Norris of Nebraska. TVA was envisioned not only as a provider, but also as an economic development agency that would use federal experts and electricity to rapidly modernize the regions economy. T. V. A. s service area covers most of Tennessee, portions of Alabama, Mississippi, and Kentucky, and small slices of Georgia, North Carolina and it was the first large regional planning agency of the federal government and remains the largest. Under the leadership of David Lilienthal, T. V. A. became a model for Americas governmental efforts to seek in assisting the modernization of agrarian societies in the developing world, President Franklin Delano Roosevelt signed the Tennessee Valley Authority Act, creating the TVA. During the 1920s and the Great Depression years, Americans began to support the idea of ownership of utilities. The concept of government-owned generation facilities selling to publicly owned distribution utilities was controversial, many believed privately owned power companies were charging too much for power, did not employ fair operating practices, and were subject to abuse by their owners, at the expense of consumers. By forming utility holding companies, the sector controlled 94 percent of generation by 1921. Many private companies in the Tennessee Valley were bought by the federal government, others shut down, unable to compete with the T. V. A. Government regulations were passed to prevent competition with T. V. A. T. V. A. was one of the first federal hydropower agencies, other attempts to create T. V. A. -like regional agencies have failed, such as a proposed Columbia Valley Authority for the Columbia River in the Pacific Northwest. Regional power consumers may benefit from lower-cost electricity supplied from T. V. A. s network of 29 power-producing hydropower facilities, supporters of TVA, though, note that the agencys management of the Tennessee River system without appropriated federal funding saves federal taxpayers millions of dollars annually. Defenders note that TVA is overwhelmingly popular in Tennessee among conservatives and liberals alike, as Barry Goldwater discovered in 1964, the Supreme Court of the United States ruled TVA to be constitutional in Ashwander v. Tennessee Valley Authority,297 U. S.288. The Court noted that regulating commerce among the states regulation of streams. The war powers also authorized the project, the argument before the court was that electricity generation was a by-product of navigation and flood control and therefore could be considered constitutional. In the 1920s a major battle erupted over building a power system in the Tennessee Valley, based on the World War I federal dam at Muscle Shoals. It would generate electricity and produce fertilizer, Senator George Norris of Nebraska blocked a proposal from Henry Ford in 1920 to use the dam to modernize the valley. Norris deeply distrusted privately owned utility companies and he did get Congress to pass the Muscle Shoals Bill, but it was vetoed as socialistic by President Herbert Hoover in 1931. The idea behind the Muscle Shoals Bill in 1933 became a part of the New Deals TVA
Tennessee Valley Authority
–
TVA Towers, TVA's headquarters in downtown Knoxville, overlooking the Tennessee River
Tennessee Valley Authority
–
Logo of the TVA Flag of the TVA
Tennessee Valley Authority
–
TVA
electricity sign at
Franklin D. Roosevelt Presidential Library and Museum in
Hyde Park, New York
Tennessee Valley Authority
–
President
Franklin D. Roosevelt signs the TVA Act
3.
Chemical plant
–
A chemical plant is an industrial process plant that manufactures chemicals, usually on a large scale. The general objective of a plant is to create new material wealth via the chemical or biological transformation. Chemical plants use specialized equipment, units, and technology in the manufacturing process, some would consider an oil refinery or a pharmaceutical or polymer manufacturer to be effectively a chemical plant. Petrochemical plants are located adjacent to an oil refinery to minimize transportation costs for the feedstocks produced by the refinery. Speciality chemical and fine chemical plants are much smaller and not as sensitive to location. Tools have been developed for converting a base project cost from one location to another. Chemical plants use chemical processes, which are detailed industrial-scale methods, the same chemical process can be used at more than one chemical plant, with possibly differently scaled capacities at each plant. Also, a plant at a site may be constructed to utilize more than one chemical process. A chemical plant commonly has usually large vessels or sections called units or lines that are interconnected by piping or other material-moving equipment which can carry streams of material, such material streams can include fluids or sometimes solids or mixtures such as slurries. An overall chemical process is made up of steps called unit operations which occur in the individual units. A raw material going into a process or plant as input to be converted into a product is commonly called a feedstock. In addition to feedstocks for the plant as a whole, a stream of material to be processed in a particular unit can similarly be considered feed for that unit. Output streams from the plant as a whole are final products, however, final products from one plant may be intermediate chemicals used as feedstock in another plant for further processing. For example, some products from an oil refinery may used as feedstock in petrochemical plants, either the feedstock, the product, or both may be individual compounds or mixtures. It is often not worthwhile separating the components in these mixtures completely, specific levels of purity depend on product requirements, chemical processes may be run in continuous or batch operation. In batch operation, production occurs in time-sequential steps in discrete batches, a batch of feedstock is fed into a process or unit, then the chemical process takes place, then the product and any other outputs are removed. Such batch production may be repeated again and again with new batches of feedstock. Batch operation is used in smaller scale plants such as pharmaceutical or specialty chemicals production
Chemical plant
–
BASF Chemical Plant Portsmouth Site in the
West Norfolk area of
Portsmouth, Virginia,
United States. The plant is served by the
Commonwealth Railway.
Chemical plant
–
Distillation unit in
Italy
Chemical plant
–
History
4.
Extractive metallurgy
–
Extractive metallurgy is a branch of metallurgical engineering wherein process and methods of extraction of metals from their natural mineral deposits are studied. Several processes are used for extraction of same metal depending on occurrence, thereafter, the ore is physically separated from any unwanted impurity, depending on the form of occurrence and/or further process involved. Separation processes take advantage of properties of the materials. These physical properties can include density, particle size and shape, electrical and magnetic properties, and surface properties. This concentrate is either processed to remove moisture or else used as is for extraction of the metal or made into shapes and forms that can undergo further processing. Ore bodies often contain more than one valuable metal, tailings of a previous process may be used as a feed in another process to extract a secondary product from the original ore. Additionally, a concentrate may contain more than one valuable metal and that concentrate would then be processed to separate the valuable metals into individual constituents. Hydrometallurgy is concerned with processes involving aqueous solutions to extract metals from ores, the first step in the hydrometallurgical process is leaching, which involves dissolution of the valuable metals into the aqueous solution and /or a suitable solvent. This may include precipitation, distillation, adsorption, and solvent extraction, the final recovery step may involve precipitation, cementation, or an electrometallurgical process. Sometimes, hydrometallurgical processes may be carried out directly on the ore material without any pretreatment steps, more often, the ore must be pretreated by various mineral processing steps, and sometimes by pyrometallurgical processes. Pyrometallurgy involves high temperature processes where chemical reactions take place among gases, solids, solids containing valuable metals are treated to form intermediate compounds for further processing or converted into their elemental or metallic state. Pyrometallurgical processes that involve gases and solids are typified by calcining and roasting operations, processes that produce molten products are collectively referred to as smelting operations. The energy required to sustain the high temperature pyrometallurgical processes may derive from the nature of the chemical reactions taking place. Typically, these reactions are oxidation, e. g. of sulfide to sulfur dioxide, often, however, energy must be added to the process by combustion of fuel or, in the case of some smelting processes, by the direct application of electrical energy. Ellingham Diagrams are a way of analysing the possible reactions. Electrometallurgy involves metallurgical processes that take place in form of electrolytic cell. The most common types of processes are electrowinning and electro-refining. Electrowinning is a process used to recover metals in aqueous solution
Extractive metallurgy
–
Ellingham diagram for high temperature oxidation
5.
Metal
–
A metal is a material that is typically hard, opaque, shiny, and has good electrical and thermal conductivity. Metals are generally malleable—that is, they can be hammered or pressed permanently out of shape without breaking or cracking—as well as fusible and ductile, about 91 of the 118 elements in the periodic table are metals, the others are nonmetals or metalloids. Some elements appear in both metallic and non-metallic forms, astrophysicists use the term metal to collectively describe all elements other than hydrogen and helium, the simplest two, in a star. The star fuses smaller atoms, mostly hydrogen and helium, to larger ones over its lifetime. In that sense, the metallicity of an object is the proportion of its matter made up of all chemical elements. Many elements and compounds that are not normally classified as metals become metallic under high pressures, the atoms of metallic substances are typically arranged in one of three common crystal structures, namely body-centered cubic, face-centered cubic, and hexagonal close-packed. In bcc, each atom is positioned at the center of a cube of eight others, in fcc and hcp, each atom is surrounded by twelve others, but the stacking of the layers differs. Some metals adopt different structures depending on the temperature, atoms of metals readily lose their outer shell electrons, resulting in a free flowing cloud of electrons within their otherwise solid arrangement. This provides the ability of metallic substances to easily transmit heat, while this flow of electrons occurs, the solid characteristic of the metal is produced by electrostatic interactions between each atom and the electron cloud. This type of bond is called a metallic bond, Metals are usually inclined to form cations through electron loss, reacting with oxygen in the air to form oxides over various timescales. Examples,4 Na + O2 →2 Na2O2 Ca + O2 →2 CaO4 Al +3 O2 →2 Al2O3, the transition metals are slower to oxidize because they form a passivating layer of oxide that protects the interior. Others, like palladium, platinum and gold, do not react with the atmosphere at all, some metals form a barrier layer of oxide on their surface which cannot be penetrated by further oxygen molecules and thus retain their shiny appearance and good conductivity for many decades. The oxides of metals are generally basic, as opposed to those of nonmetals, exceptions are largely oxides with very high oxidation states such as CrO3, Mn2O7, and OsO4, which have strictly acidic reactions. Painting, anodizing or plating metals are good ways to prevent their corrosion, however, a more reactive metal in the electrochemical series must be chosen for coating, especially when chipping of the coating is expected. Water and the two form an electrochemical cell, and if the coating is less reactive than the coatee. Metals in general have high conductivity, high thermal conductivity. Typically they are malleable and ductile, deforming under stress without cleaving, in terms of optical properties, metals are shiny and lustrous. Sheets of metal beyond a few micrometres in thickness appear opaque, although most metals have higher densities than most nonmetals, there is wide variation in their densities, lithium being the least dense solid element and osmium the densest
Metal
–
Gallium crystals
Metal
–
Hot metal work from a
blacksmith.
Metal
–
Zinc, a base metal, reacting with an acid
Metal
–
A gold nugget
6.
Ore
–
An ore is a type of rock that contains sufficient minerals with important elements including metals that can be economically extracted from the rock. The ores are extracted from the earth through mining, they are refined to extract the valuable element. The grade or concentration of an ore mineral, or metal, as well as its form of occurrence, will directly affect the costs associated with mining the ore. The cost of extraction must thus be weighed against the value contained in the rock to determine what ore can be processed. Metal ores are generally oxides, sulfides, silicates, or native metals that are not commonly concentrated in the Earths crust, the ores must be processed to extract the metals of interest from the waste rock and from the ore minerals. Ore bodies are formed by a variety of geological processes, the process of ore formation is called ore genesis. An ore deposit is an accumulation of ore and this is distinct from a mineral resource as defined by the mineral resource classification criteria. An ore deposit is one occurrence of a particular ore type, Ore deposits are classified according to various criteria developed via the study of economic geology, or ore genesis. Stratiform arkose-hosted and shale-hosted copper, typified by the Zambian copperbelt and this identifies, early on, whether further investment in estimation and engineering studies is warranted and identifies key risks and areas for further work. This is because the distribution of ores is unequal and dislocated from locations of peak demand. Other, lesser, commodities do not have international clearing houses and benchmark prices and this generally makes determining the price of ores of this nature opaque and difficult. Such metals include lithium, niobium-tantalum, bismuth, antimony and rare earths, most of these commodities are also dominated by one or two major suppliers with >60% of the worlds reserves. The London Metal Exchange aims to add uranium to its list of metals on warrant, the World Bank reports that China was the top importer of ores and metals in 2005 followed by the USA and Japan. Economic geology Mineral resource classification Ore genesis Petrology Froth Flotation Extractive metallurgy DILL, the “chessboard” classification scheme of mineral deposits, Mineralogy and geology from aluminum to zirconium, Earth-Science Reviews, Volume 100, Issue 1-4, June 2010, Pages 1-420
Ore
–
Manganese ore –
psilomelane (size: 6.7 × 5.8 × 5.1 cm)
Ore
–
Iron ore (
Banded iron formation)
Ore
–
Lead ore –
galena and
anglesite (size: 4.8 × 4.0 × 3.0 cm)
Ore
–
Gold ore (size: 7.5 × 6.1 × 4.1 cm)
7.
Silver mining
–
Silver mining is the resource extraction of silver by mining. Silver is found in native form very rarely as nuggets, but more usually combined with sulfur, arsenic, antimony, or chlorine and in ores such as argentite, chlorargyrite. As silver is found in conjunction with these or alloyed with other metals such as gold. Silver mining has been undertaken since early times, as silver is a precious metal often used for coins, its mining has historically often been lucrative. As with other metals such as gold or platinum, newly discovered deposits of silver ore have sparked silver rushes of miners seeking their fortunes. Silver has been known since ancient times, the silver mines at Laurium were very rich and helped provide a currency for the economy of Ancient Athens. It involved mining the ore in underground galleries, washing the ores, elaborate washing tables still exist at the site using rain water held in cisterns and collected during the winter months. Extraction of silver from ore was widespread in Roman Britain as a result of Roman mining very soon after the conquest of the first century AD. From the mid-15th century silver began to be extracted from copper ores in massive quantities using the process creating a boost to the mining. Silver, which was valuable in China, became a global commodity. The rise and fall of its value affected the world market, Silver mining was a driving force in the settlement of western North America, with major booms for silver and associated minerals in the galena ore silver is most commonly found in. Notable silver rushes were in Colorado, Nevada, Cobalt, Ontario, California, the first major silver ore deposits in the United States were discovered at the Comstock Lode in Virginia City, Nevada, in 1859. Silver is commonly extracted from ore by smelting or chemical leaching, ore treatment by mercury amalgamation, such as in the patio process or pan amalgamation was widely used through the 1800s, but is seldom used today. Silver is also produced during the refining of copper and by application of the Parkes process on lead metal obtained from lead ores that contain small amounts of silver. Commercial grade fine silver is at least 99.9 percent pure silver, the principal sources of silver are copper, copper-nickel, gold, lead, and lead-zinc ores obtained from Canada, Mexico, Poland, Peru, Bolivia, Australia and the United States. Mexico was the worlds largest silver producer in 2014, producing 5,000 metric tons,18.7 percent of the 26,800 tonne production of the world. Gold mining Silver as an investment Silver mining in the United States Silver mining in Britain 2007 Global Silver Production and Inventories
Silver mining
–
An underground silver mine in
Baden-Württemberg, Germany
Silver mining
–
Early silver
Athenian coin, 5th century BCE.
British Museum.
Silver mining
–
Silver
Spanish real from the silver of Potosí, Bolivia. The amount of silver mined at Potosí and other locations in the Spanish Empire led to significant inflation in Europe.
Silver mining
–
A nugget of silver
8.
Iron-making
–
Ferrous metallurgy involves processes and alloys based on iron. It began far back in prehistory, the earliest surviving iron artifacts, from the 4th millennium BC in Egypt, were made from meteoritic iron-nickel. It is not known when or where the smelting of iron ores began. The use of iron was known by the 1st millennium BC. During the medieval period, means were found in Europe of producing iron from cast iron using finery forges. For all these processes, charcoal was required as fuel, Steel was first produced in antiquity as an alloy. Its process of production, Wootz steel, was exported before the 4th century BC to ancient China, Africa, archaeological evidence of cast iron appears in 5th century BC China. New methods of producing it by carburizing bars of iron in the process were devised in the 17th century. During the Industrial Revolution, new methods of producing bar iron without charcoal were devised, in the late 1850s, Henry Bessemer invented a new steelmaking process, that involved blowing air through molten pig iron to burn off carbon, and so to produce mild steel. This and other 19th-century and later processes have displaced the use of wrought iron, today, wrought iron is no longer produced on a commercial scale. Iron was extracted from iron–nickel alloys, which comprise about 6% of all meteorites that fall on the Earth and that source can often be identified with certainty because of the unique crystalline features of that material, which are preserved when the metal is worked cold or at low temperature. Those artifacts include, for example, a bead from the 5th millennium BC found in Iran and spear tips and ornaments from Ancient Egypt, meteoric iron has been identified also in a Chinese axe head from the middle of the 2nd millennium BC. These early uses appear to have been ceremonial or ornamental. Meteoritic iron is very rare, and the metal was very expensive. The early Hittites are known to have bartered iron for silver, at a rate of 40 times the irons weight, typically pea-size bits of metal were cold-hammered into disks and fitted to a bone handle. These artifacts were used as trade goods with other Arctic peoples. When the American polar explorer Robert Peary shipped the largest piece of the meteorite to the American Museum of Natural History in New York City in 1897, another example of a late use of meteoritic iron is an adze from around 1000 AD found in Sweden. Media related to Objects made from meteoritic iron at Wikimedia Commons Native iron in the state occurs rarely as small inclusions in certain basalt rocks
Iron-making
–
Willamette Meteorite, the sixth largest in the world, is an
iron-nickel meteorite
Iron-making
–
Bloomery smelting during the
Middle Ages.
Iron-making
–
Iron meteorites consist overwhelmingly of nickel-iron alloys. The metal taken from these meteorites is known as meteoric iron and was one of the earliest sources of usable iron available to humans.
Iron-making
–
The
Iron pillar of Delhi
9.
Copper extraction
–
Copper extraction refers to the methods used to obtaining copper from its ores. The conversion of copper consists of a series of chemical, physical, methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors. As in all mining operations, the ore must usually be beneficiated, the processing techniques depend on the nature of the ore. If the ore is primarily sulfide copper minerals, the ore is crushed and it is then concentrated using mineral flotation. The concentrate is then sold to distant smelters, although some large mines have smelters located nearby. Such colocation of mines and smelters was more typical in the 19th and early 20th centuries, finally, the final refining process is electrolysis. For economic and environmental reasons, many of the byproducts of extraction are reclaimed, sulfur dioxide gas, for example, is captured and turned into sulfuric acid — which can then used in the extraction process or sold for such purposes as fertiliser manufacture. Oxidised copper ores can be treated by hydrometallurgical extraction, the earliest evidence of cold-hammering of native copper comes from the excavation at Çaÿonü Tepesi in eastern Anatolia. Among the various items considered to be votive or amulets there was one that looked like a fishhook, pločnik archaeological site in southeastern Europe contains the oldest securely dated evidence of copper making at high temperature, from 5,000 BCE. The find in June 2010 extends for additional 500 years the record of copper smelting from Rudna Glava. Copper smelting technology gave rise to the Copper Age and then the Bronze Age, in some cases, tailings have been retreated to recover lost value as the technology for recovering copper has improved. The average grade of copper ores in the 21st century is below 0. 6% copper, a key objective in the metallurgical treatment of any ore is the separation of ore minerals from gangue minerals within the rock. These particles are separated to remove gangue, thereafter followed by a process of physical liberation of the ore minerals from the rock. The process of liberation of copper ores depends upon whether they are oxide or sulfide ores, subsequent steps depend on the nature of the ore containing the copper and what will be extracted. For oxide ores, a hydrometallurgical liberation process is normally undertaken, for sulfide ores, both secondary and primary, froth flotation is used to physically separate ore from gangue. For special native copper bearing ore bodies or sections of ore bodies rich in native copper. The modern froth flotation process was invented the early 1900s in Australia by C. V Potter. All primary sulfide ores of copper sulfides, and most concentrates of secondary copper sulfides, are subjected to smelting
Copper extraction
–
The
Chino open-pit copper mine in New Mexico.
Copper extraction
–
Chalcopyrite specimen from Huaron mine,
Peru
Copper extraction
–
Froth flotation cells to concentrate copper and nickel sulfide minerals, Falconbridge, Ontario.
Copper extraction
–
Copper sulfide loaded air bubbles on a
Jameson Cell at the flotation plant of the
Prominent Hill mine in
South Australia
10.
Redox
–
Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
Redox
–
Rusting iron
Redox
–
A
bonfire
Redox
–
Oxides, such as
iron(III) oxide or
rust, which consists of hydrated
iron(III) oxides Fe 2 O 3 · n H 2 O and
iron(III) oxide-hydroxide (FeO(OH), Fe(OH) 3), form when oxygen combines with other elements
Redox
–
Iron rusting in
pyrite cubes
11.
Slag
–
Slag is the glass-like by-product left over after a desired metal has been separated from its raw ore. Slag is usually a mixture of oxides and silicon dioxide. However, slags can contain metal sulfides and elemental metals, in nature, iron, copper, lead, nickel and other metals are found in impure states called ores, often oxidized and mixed in with silicates of other metals. During smelting, when the ore is exposed to high temperatures, Slag is the collection of compounds that are removed. In many smelting processes, oxides are introduced to control the slag chemistry, assisting in the removal of impurities, in this case, the slag is termed synthetic. Ferrous and non-ferrous smelting processes produce different slags, the smelting of copper and lead in non-ferrous smelting, for instance, is designed to remove the iron and silica that often occurs with those ores, and separates them as iron-silicate-based slags. Slag from steel mills in ferrous smelting, on the hand, is designed to minimize iron loss and so mainly contains oxides of calcium, silicon, magnesium. Any sandy component or quartz component of the original ore automatically carries through the process as silicon dioxide. As the slag is channeled out of the furnace, water is poured over it and this rapid cooling, often from a temperature of around 2,600 °F, is the start of the granulating process. This process causes several chemical reactions to take place within the slag, the water carries the slag in its slurry format to a large agitation tank, from where it is pumped along a piping system into a number of gravel based filter beds. The filter beds then retain the slag granules, while the drains away and is returned to the system. During the Bronze Age of the Mediterranean there were a vast number of metallurgical processes in use. A slag by-product of such workings was a colorful, glassy and it was primarily blue or green and was formerly chipped away and melted down to make glassware products and jewelry. It was also ground into powder to add to glazes for use in ceramics, some of the earliest such uses for the by-products of slag have been found in ancient Egypt. Historically, the re-smelting of iron ore slag was common practice, during the early 20th century, iron ore slag was also ground to a powder and used to make agate glass, also known as slag glass. Ground granulated slag is used in concrete in combination with Portland cement as part of a blended cement. Ground granulated slag reacts with water to produce cementitious properties, concrete containing ground granulated slag develops strength over a longer period, leading to reduced permeability and better durability. Since the unit volume of Portland cement is reduced, this concrete is less vulnerable to alkali-silica, the slag can also be used to create fibers used as an insulation material called slag wool
Slag
–
A path through a slag heap in
Clarkdale, Arizona, showing the striations from the rusting corrugated sheets retaining it.
Slag
–
The Manufacture of Iron – Carting Away the Scoriæ (slag), an 1873
wood engraving
Slag
–
Slag run-off from one of the
open hearth furnaces of a steel mill,
Republic Steel, Youngstown, Ohio, November 1941. Slag is drawn off the furnace just before the molten steel is poured into ladles for
ingotting.
Slag
–
Early slag from Denmark, c. 200-500
CE
12.
Carbon
–
Carbon is a chemical element with symbol C and atomic number 6. It is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds, three isotopes occur naturally, 12C and 13C being stable, while 14C is a radioactive isotope, decaying with a half-life of about 5,730 years. Carbon is one of the few elements known since antiquity, Carbon is the 15th most abundant element in the Earths crust, and the fourth most abundant element in the universe by mass after hydrogen, helium, and oxygen. It is the second most abundant element in the body by mass after oxygen. The atoms of carbon can bond together in different ways, termed allotropes of carbon, the best known are graphite, diamond, and amorphous carbon. The physical properties of carbon vary widely with the allotropic form, for example, graphite is opaque and black while diamond is highly transparent. Graphite is soft enough to form a streak on paper, while diamond is the hardest naturally occurring material known, graphite is a good electrical conductor while diamond has a low electrical conductivity. Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials, all carbon allotropes are solids under normal conditions, with graphite being the most thermodynamically stable form. They are chemically resistant and require high temperature to react even with oxygen, the most common oxidation state of carbon in inorganic compounds is +4, while +2 is found in carbon monoxide and transition metal carbonyl complexes. The largest sources of carbon are limestones, dolomites and carbon dioxide, but significant quantities occur in organic deposits of coal, peat, oil. For this reason, carbon has often referred to as the king of the elements. The allotropes of carbon graphite, one of the softest known substances, and diamond. It bonds readily with other small atoms including other carbon atoms, Carbon is known to form almost ten million different compounds, a large majority of all chemical compounds. Carbon also has the highest sublimation point of all elements, although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature. Carbon is the element, with a ground-state electron configuration of 1s22s22p2. Its first four ionisation energies,1086.5,2352.6,4620.5 and 6222.7 kJ/mol, are higher than those of the heavier group 14 elements. Carbons covalent radii are normally taken as 77.2 pm,66.7 pm and 60.3 pm, although these may vary depending on coordination number, in general, covalent radius decreases with lower coordination number and higher bond order. Carbon compounds form the basis of all life on Earth
Carbon
–
Graphite (left) and diamond (right), the two most well-known allotropes of carbon
Carbon
–
Spectral lines of carbon
Carbon
–
A large sample of glassy carbon.
Carbon
–
Graphite ore
13.
Coke (fuel)
–
Coke is a fuel with few impurities and a high carbon content, usually made from coal. It is the carbonaceous material derived from destructive distillation of low-ash. Cokes made from coal are grey, hard, and porous, while coke can be formed naturally, the commonly used form is man-made. The form known as coke, or pet coke, is derived from oil refinery coker units or other cracking processes. Coke is used in preparation of producer gas which is a mixture of carbon monoxide, producer gas is produced by passing air over red-hot coke. Coke is also used to water gas. Historical sources dating to the 4th century describe the production of coke in ancient China, the Chinese first used coke for heating and cooking no later than the ninth century. By the first decades of the century, Chinese ironworkers in the Yellow River valley began to fuel their furnaces with coke. In 1589 a patent was granted to Thomas Proctor and William Peterson for making iron and steel and melting lead with earth-coal, sea-coal, turf, the patent contains a distinct allusion to the preparation of coal by cooking. In 1590 a patent was granted to the Dean of York to purify pit-coal, in 1620 a patent was granted to a company composed of William St. John, Robert Follensbee and other knights, mentioning the use of coke in smelting ores and manufacturing metals. In 1627 a patent was granted to Sir John Hacket and Octavius de Strada for a method of rendering sea-coal and pit-coal as useful as charcoal for burning in houses, without offense by smell or smoke. In 1603 Hugh Plat suggested that coal might be charred in an analogous to the way charcoal is produced from wood. In 1709 Abraham Darby I established a coke-fired blast furnace to produce cast iron, cokes superior crushing strength allowed blast furnaces to become taller and larger. The ensuing availability of iron was one of the factors leading to the Industrial Revolution. Before this time, iron-making used large quantities of charcoal, produced by burning wood, in the late 18th century, brick beehive ovens were developed, which allowed more control over the burning process. In 1768 John Wilkinson built a more practical oven for converting coal into coke, with greater skill in the firing, covering and quenching of the heaps, yields were increased from about 33 per cent to 65 per cent by the middle of the 19th century. The Scottish iron industry expanded rapidly in the second quarter of the 19th century. In 1802 a battery of beehives was set up near Sheffield, by 1870, there were 14,000 beehive ovens in operation on the West Durham coalfields, capable of producing 4.2 million tons of coke
Coke (fuel)
–
Raw coke
Coke (fuel)
–
Illustration of coal mining and coke burning from 1879.
Coke (fuel)
–
Coal coking ovens at Cokedale, west of
Trinidad, Colorado, supplied steel mills in
Pueblo, Colorado.
Coke (fuel)
–
Coke oven at
smokeless fuel plant,
Abercwmboi, South
Wales, 1976
14.
Charcoal
–
Charcoal is a lightweight, black residue, consisting of carbon and any remaining ash, obtained by removing water and other volatile constituents from animal and vegetation substances. Charcoal is usually produced by slow pyrolysis- the heating of wood or other substances in the absence of oxygen, the whole pile is covered with turf or moistened clay. The firing is begun at the bottom of the flue, the success of the operation depends upon the rate of the combustion. The operation is so delicate that it was left to colliers. They often lived alone in small huts in order to tend their wood piles, for example, in the Harz Mountains of Germany, charcoal burners lived in conical huts called Köten which are still much in evidence today. The massive production of charcoal was a cause of deforestation. The increasing scarcity of easily harvested wood was a factor behind the switch to fossil fuel equivalents, mainly coal. Charcoal made at 300 °C is brown, soft and friable, and readily inflames at 380 °C, made at higher temperatures it is hard and brittle, in Finland and Scandinavia, the charcoal was considered the by-product of wood tar production. The best tar came from pine, thus pinewoods were cut down for tar pyrolysis, the residual charcoal was widely used as substitute for metallurgical coke in blast furnaces for smelting. Tar production led to deforestation, it has been estimated all Finnish forests are younger than 300 years. The end of tar production at the end of the 19th century resulted in rapid re-forestation, the charcoal briquette was first invented and patented by Ellsworth B. A. Zwoyer of Pennsylvania in 1897 and was produced by the Zwoyer Fuel Company. The process was popularized by Henry Ford, who used wood. Ford Charcoal went on to become the Kingsford Company, Charcoal has been made by various methods. The traditional method in Britain used a clamp and this is essentially a pile of wooden logs leaning against a chimney. The chimney consists of 4 wooden stakes held up by some rope, the logs are completely covered with soil and straw allowing no air to enter. It must be lit by introducing some burning fuel into the chimney, if the soil covering gets torn by the fire, additional soil is placed on the cracks. Once the burn is complete, the chimney is plugged to prevent air from entering, the true art of this production method is in managing the sufficient generation of heat, and its transfer to wood parts in the process of being carbonised. A strong disadvantage of this method is the huge amount of emissions that are harmful to human health
Charcoal
–
Dry charcoal
Charcoal
–
Charcoal burning
Charcoal
–
Wood pile before covering it with
turf or soil, and firing it (around 1890)
Charcoal
–
An abandoned charcoal kiln near Walker, Arizona, USA.
15.
Oxygen
–
Oxygen is a chemical element with symbol O and atomic number 8. It is a member of the group on the periodic table and is a highly reactive nonmetal. By mass, oxygen is the third-most abundant element in the universe, after hydrogen, at standard temperature and pressure, two atoms of the element bind to form dioxygen, a colorless and odorless diatomic gas with the formula O2. This is an important part of the atmosphere and diatomic oxygen gas constitutes 20. 8% of the Earths atmosphere, additionally, as oxides the element makes up almost half of the Earths crust. Most of the mass of living organisms is oxygen as a component of water, conversely, oxygen is continuously replenished by photosynthesis, which uses the energy of sunlight to produce oxygen from water and carbon dioxide. Oxygen is too reactive to remain a free element in air without being continuously replenished by the photosynthetic action of living organisms. Another form of oxygen, ozone, strongly absorbs ultraviolet UVB radiation, but ozone is a pollutant near the surface where it is a by-product of smog. At low earth orbit altitudes, sufficient atomic oxygen is present to cause corrosion of spacecraft, the name oxygen was coined in 1777 by Antoine Lavoisier, whose experiments with oxygen helped to discredit the then-popular phlogiston theory of combustion and corrosion. One of the first known experiments on the relationship between combustion and air was conducted by the 2nd century BCE Greek writer on mechanics, Philo of Byzantium. In his work Pneumatica, Philo observed that inverting a vessel over a burning candle, Philo incorrectly surmised that parts of the air in the vessel were converted into the classical element fire and thus were able to escape through pores in the glass. Many centuries later Leonardo da Vinci built on Philos work by observing that a portion of air is consumed during combustion and respiration, Oxygen was discovered by the Polish alchemist Sendivogius, who considered it the philosophers stone. In the late 17th century, Robert Boyle proved that air is necessary for combustion, English chemist John Mayow refined this work by showing that fire requires only a part of air that he called spiritus nitroaereus. From this he surmised that nitroaereus is consumed in both respiration and combustion, Mayow observed that antimony increased in weight when heated, and inferred that the nitroaereus must have combined with it. Accounts of these and other experiments and ideas were published in 1668 in his work Tractatus duo in the tract De respiratione. Robert Hooke, Ole Borch, Mikhail Lomonosov, and Pierre Bayen all produced oxygen in experiments in the 17th and the 18th century but none of them recognized it as a chemical element. This may have been in part due to the prevalence of the philosophy of combustion and corrosion called the phlogiston theory, which was then the favored explanation of those processes. Established in 1667 by the German alchemist J. J. Becher, one part, called phlogiston, was given off when the substance containing it was burned, while the dephlogisticated part was thought to be its true form, or calx. The fact that a substance like wood gains overall weight in burning was hidden by the buoyancy of the combustion products
Oxygen
–
Spectral lines of oxygen
Oxygen
Oxygen
–
A trickle of liquid oxygen is deflected by a magnetic field, illustrating its paramagnetic property
Oxygen
–
Oxygen discharge (spectrum) tube. The green color is similar to the color of an
"aurora borealis"
16.
Flux (metallurgy)
–
In metallurgy, a flux is a chemical cleaning agent, flowing agent, or purifying agent. Fluxes may have more than one function at a time and they are used in both extractive metallurgy and metal joining. Some of the earliest known fluxes were carbonate of soda, potash, charcoal, coke, borax, lime, lead sulfide, iron ore was also used as a flux in the smelting of copper. As cleaning agents, fluxes facilitate soldering, brazing, and welding by removing oxidation from the metals to be joined, the slag is a liquid mixture of ash, flux, and other impurities. This reduction of slag viscosity with temperature, increasing the flow of slag in smelting, is the origin of the word flux in metallurgy. Fluxes are also used in foundries for removing impurities from molten nonferrous metals such as aluminium, in high-temperature metal joining processes, the primary purpose of flux is to prevent oxidation of the base and filler materials. Tin-lead solder attaches very well to copper, but poorly to the oxides of copper. Flux is a substance which is inert at room temperature. Additionally, flux allows solder to flow easily on the piece rather than forming beads as it would otherwise. In some applications molten flux also serves as a heat transfer medium, fluxes for soft soldering are typically of organic nature, though inorganic fluxes, usually based on halogenides and/or acids, are also used in non-electronics applications. Fluxes for brazing operate at higher temperatures and are therefore mostly inorganic. Organic fluxes typically consist of four components, Activators - chemicals disrupting/dissolving the metal oxides. Their role is to expose unoxidized, easily wettable metal surface and aid soldering by other means, highly active fluxes contain chemicals that are corrosive at room temperature. The compounds used include metal halides, hydrochloric acid, phosphoric acid, Salts of mineral acids with amines are also used as aggressive activators. Aggressive fluxes typically facilitate corrosion, require careful removal, and are unsuitable for finer work, Activators for fluxes for soldering and brazing aluminium often contain fluorides. Milder activators begin to react with oxides only at elevated temperature, typical compounds used are carboxylic acids and sometimes amino acids. Some milder fluxes also contain halides or organohalides, vehicles - high-temperature tolerant chemicals in the form of non-volatile liquids or solids with suitable melting point, they are generally liquid at soldering temperatures. Solid vehicles tend to be based on natural or modified rosin or natural or synthetic resins, water-soluble organic fluxes tend to contain vehicles based on high-boiling polyols - glycols, diethylene glycol and higher polyglycols, polyglycol-based surfactants and glycerol
Flux (metallurgy)
–
Rosin used as flux for
soldering
Flux (metallurgy)
–
A flux pen used for
electronics rework
Flux (metallurgy)
–
Multicore solder containing flux
Flux (metallurgy)
–
Wire freshly coated with solder, still immersed in molten rosin flux
17.
Limestone
–
Limestone is a sedimentary rock, composed mainly of skeletal fragments of marine organisms such as coral, forams and molluscs. Its major materials are the minerals calcite and aragonite, which are different crystal forms of calcium carbonate, about 10% of sedimentary rocks are limestones. The solubility of limestone in water and weak acid solutions leads to karst landscapes, most cave systems are through limestone bedrock. The first geologist to distinguish limestone from dolomite was Belsazar Hacquet in 1778, like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts and these organisms secrete shells made of aragonite or calcite, and leave these shells behind when they die. Limestone often contains variable amounts of silica in the form of chert or siliceous skeletal fragment, some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i. e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters and this produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular appearance, the primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters. Limestones may also form in lacustrine and evaporite depositional environments, calcite can be dissolved or precipitated by groundwater, depending on several factors, including the water temperature, pH, and dissolved ion concentrations. Calcite exhibits a characteristic called retrograde solubility, in which it becomes less soluble in water as the temperature increases. Impurities will cause limestones to exhibit different colors, especially with weathered surfaces, Limestone may be crystalline, clastic, granular, or massive, depending on the method of formation. Crystals of calcite, quartz, dolomite or barite may line small cavities in the rock, when conditions are right for precipitation, calcite forms mineral coatings that cement the existing rock grains together, or it can fill fractures. Travertine is a banded, compact variety of limestone formed along streams, particularly there are waterfalls. Calcium carbonate is deposited where evaporation of the leaves a solution supersaturated with the chemical constituents of calcite. Tufa, a porous or cellular variety of travertine, is found near waterfalls, coquina is a poorly consolidated limestone composed of pieces of coral or shells. During regional metamorphism that occurs during the building process, limestone recrystallizes into marble
Limestone
–
Limestone outcrop in the
Torcal de Antequera nature reserve of
Málaga, Spain
Limestone
–
Limestone quarry at
Cedar Creek, Virginia, USA
Limestone
–
Cutting the limestone blocks at a quarry in
Gozo,
Malta
Limestone
–
Limestone as building material
18.
Gangue
–
In mining, gangue is the commercially worthless material that surrounds, or is closely mixed with, a wanted mineral in an ore deposit. It is thus distinct from overburden, which is the rock or materials overlying an ore or mineral body that are displaced during mining without being processed. The separation of mineral from gangue is known as mineral processing, mineral dressing and it is a necessary and often significant, aspect of mining. It can be a process, depending on the nature of the minerals involved. The ease with which the ore can be separated also plays an important part, minerals that were once thought of as gangue, and were dumped, may later find a commercial use. When this happens the old dumps are often reworked to extract the wanted mineral, for example, in copper mines in the 19th century the mineral arsenopyrite was dumped until arsenic became popular as an insecticide later in the century. In the 21st century, the use of gangue has been considered from a point of view. For example, in 2002, about 130 million tons of gangue were produced per year from mining in China. This, mixed with the 60 million tons of coal mud also produced, could be used for generation. The estimated cost of projects would be up to 4 billion yuan. Froth flotation Magnetic separation Vanning Extractive Metallurgy Mineral processing An Elementary Outline Of Mechanical Processes, by G. W. Danforth
Gangue
–
Crystals of
cassiterite, a commercially valuable mineral, in a matrix of
quartz, the gangue
19.
Electrolysis
–
In chemistry and manufacturing, electrolysis is a technique that uses a direct electric current to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from naturally occurring sources such as using an electrolytic cell. The voltage that is needed for electrolysis to occur is called the decomposition potential, nevertheless, electrolysis, as a tool to study chemical reactions and obtain pure elements, precedes the coinage of the term and formal description by Faraday. 1785 – Martinus van Marums electrostatic generator was used to reduce tin, zinc,1800 – William Nicholson and Anthony Carlisle, decomposed water into hydrogen and oxygen. 1808 – Potassium, sodium, barium, calcium and magnesium were discovered by Sir Humphry Davy using electrolysis,1821 – Lithium was discovered by the English chemist William Thomas Brande, who obtained it by electrolysis of lithium oxide. 1833 – Michael Faraday develops his two laws of electrolysis, and provides an explanation of his laws. 1875 – Paul Émile Lecoq de Boisbaudran discovered gallium using electrolysis,1886 – Fluorine was discovered by Henri Moissan using electrolysis. The main components required to achieve electrolysis are, An electrolyte, a substance, frequently an ion-conducting polymer that contains free ions, if the ions are not mobile, as in a solid salt then electrolysis cannot occur. A direct current electrical supply, provides the necessary to create or discharge the ions in the electrolyte. Electric current is carried by electrons in the external circuit, two electrodes, electrical conductors that provide the physical interface between the electrolyte and the electrical circuit that provides the energy. Electrodes of metal, graphite and semiconductor material are widely used, choice of suitable electrode depends on chemical reactivity between the electrode and electrolyte and manufacturing cost. The key process of electrolysis is the interchange of atoms and ions by the removal or addition of electrons from the external circuit, the desired products of electrolysis are often in a different physical state from the electrolyte and can be removed by some physical processes. For example, in the electrolysis of brine to produce hydrogen and chlorine and these gaseous products bubble from the electrolyte and are collected. Each electrode attracts ions that are of the opposite charge, positively charged ions move towards the electron-providing cathode. Negatively charged ions move towards the electron-extracting anode, in this process electrons are either absorbed or released. Neutral atoms gain or lose electrons and become charged ions that pass into the electrolyte. The formation of uncharged atoms from ions is called discharging, when an ion gains or loses enough electrons to become uncharged atoms, the newly formed atoms separate from the electrolyte. Positive metal ions like Cu++ deposit onto the cathode in a layer, the terms for this are electroplating, electrowinning, and electrorefining
Electrolysis
–
Illustration of an electrolysis apparatus used in a school laboratory.
20.
Aluminium
–
Aluminium or aluminum is a chemical element in the boron group with symbol Al and atomic number 13. It is a silvery-white, soft, nonmagnetic, ductile metal, Aluminium metal is so chemically reactive that native specimens are rare and limited to extreme reducing environments. Instead, it is combined in over 270 different minerals. The chief ore of aluminium is bauxite, Aluminium is remarkable for the metals low density and its ability to resist corrosion through the phenomenon of passivation. Aluminium and its alloys are vital to the industry and important in transportation and structures, such as building facades. The oxides and sulfates are the most useful compounds of aluminium, despite its prevalence in the environment, no known form of life uses aluminium salts metabolically, but aluminium is well tolerated by plants and animals. Because of these salts abundance, the potential for a role for them is of continuing interest. Aluminium is a soft, durable, lightweight, ductile. It is nonmagnetic and does not easily ignite, a fresh film of aluminium serves as a good reflector of visible light and an excellent reflector of medium and far infrared radiation. The yield strength of aluminium is 7–11 MPa, while aluminium alloys have yield strengths ranging from 200 MPa to 600 MPa. Aluminium has about one-third the density and stiffness of steel and it is easily machined, cast, drawn and extruded. Aluminium atoms are arranged in a cubic structure. Aluminium has an energy of approximately 200 mJ/m2. Aluminium is a thermal and electrical conductor, having 59% the conductivity of copper. Aluminium is capable of superconductivity, with a critical temperature of 1.2 kelvin. Aluminium is the most common material for the fabrication of superconducting qubits, the strongest aluminium alloys are less corrosion resistant due to galvanic reactions with alloyed copper. This corrosion resistance is reduced by aqueous salts, particularly in the presence of dissimilar metals. In highly acidic solutions, aluminium reacts with water to form hydrogen, primarily because it is corroded by dissolved chlorides, such as common sodium chloride, household plumbing is never made from aluminium
Aluminium
–
Aluminium, 13 Al
Aluminium
–
Spectral lines of aluminium
Aluminium
–
"
Red mud " storage facility in
Stade,
Germany. The aluminium industry generates about 70 million tons of this waste annually.
Aluminium
–
Bauxite, a major aluminium ore. The red-brown color is due to the presence of
iron minerals.
21.
Aluminium smelting
–
Aluminium smelting is the process of extracting aluminium from its oxide, alumina, generally by the Hall-Héroult process. Alumina is extracted from the ore bauxite by means of the Bayer process at an alumina refinery, aluminium smelting is the 2nd most important metallurgical industry in India. A large amount of carbon is used in this process. The Hall-Héroult electrolysis process is the major route for primary aluminium. An electrolysis cell is made of a shell with a series of insulating linings of refractory materials. The cell consists of an outer steel shell as a container. Inside the shell, cathode blocks are cemented together by ramming paste, the top lining is in contact with the molten metal and acts as the cathode. The molten electrolyte is maintained at high temperature inside the cell, the prebaked anode is also made of carbon in the form of large sintered blocks suspended in the electrolyte. A single Soderberg electrode or a number of prebaked carbon blocks are used as anode, while the principal formulation, an aluminium smelter consists of a large number of cell in which the electrolysis takes place. A typical smelter contains anywhere from 300 to 720 pots, each of which produces about a ton of aluminium a day, smelting is run as a batch process, with the aluminium metal deposited at the bottom of the pots and periodically siphoned off. Particularly in Australia these smelters are used to control electrical network demand, however power must not be interrupted for more than 4-5 hours, since the pots have to be repaired at significant cost if the liquid metal solidifies. Carbon anodes are thus consumed during electrolysis, resulting in energy consumption. The Boudouard reaction may take place as a side reaction, CO2 + C → 2CO. Formation of CO consumes twice as much carbon as required for CO2 formation, Carbon consumption shows that the primary anode product is CO2. By increasing the current density up to 1 A/cm2, the proportion of CO2 increases, electrolyte, The electrolyte is a molten bath of cryolite and dissolved alumina. Cryolite is a solvent for alumina with low melting point, satisfactory viscosity. Its density is lower than that of liquid aluminium, which allows natural separation of the product from the salt at the bottom of the cell. The cryolite ratio in pure cryolite is 3, with a temperature of 1010 °C
Aluminium smelting
–
Overview of the Point Henry smelter, operated by
Alcoa World Alumina and Chemicals in Australia
22.
Oxide
–
An oxide /ˈɒksaɪd/ is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. Oxide itself is the dianion of oxygen, an O2– atom, Metal oxides thus typically contain an anion of oxygen in the oxidation state of −2. Most of the Earths crust consists of oxides, the result of elements being oxidized by the oxygen in air or in water. Hydrocarbon combustion affords the two principal carbon oxides, carbon monoxide and carbon dioxide, even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a skin of Al2O3 that protects the foil from further corrosion. Individual elements can form multiple oxides, each containing different amounts of the element. Certain elements can form many different oxides, such those of nitrogen, due to its electronegativity, oxygen forms stable chemical bonds with almost all elements to give the corresponding oxides. Noble metals are prized because they resist direct chemical combination with oxygen, two independent pathways for corrosion of elements are hydrolysis and oxidation by oxygen. The combination of water and oxygen is even more corrosive, virtually all elements burn in an atmosphere of oxygen, or an oxygen rich environment. In the presence of water and oxygen, some elements— sodium—react rapidly, even dangerously, in part for this reason, alkali and alkaline earth metals are not found in nature in their metallic, i. e. native, form. Caesium is so reactive with oxygen that it is used as a getter in vacuum tubes, the surface of most metals consists of oxides and hydroxides in the presence of air. A well-known example is aluminium foil, which is coated with a film of aluminium oxide that passivates the metal. The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodising, though solid magnesium and aluminium react slowly with oxygen at STP—they, like most metals, burn in air, generating very high temperatures. Finely grained powders of most metals can be explosive in air. Consequently, they are used in Solid-fuel rockets. In dry oxygen, iron forms iron oxide, but the formation of the hydrated ferric oxides, Fe2O3−x2x. Free oxygen production by photosynthetic bacteria some 3.5 billion years ago precipitated iron out of solution in the oceans as Fe2O3 in the important iron ore hematite. Oxides have a range of different structures, from molecules to polymeric
Oxide
–
Oxides, such as
iron(III) oxide or
rust, which consists of hydrated
iron(III) oxides Fe 2 O 3 · n H 2 O and
iron(III) oxide-hydroxide (FeO(OH), Fe(OH) 3), form when oxygen combines with other elements
Oxide
–
Silicon dioxide (SiO 2) is one of the most common oxides on the surface of earth. Like most oxides, it adopts a polymeric structure.
23.
Sulfide
–
Sulfide is an inorganic anion of sulfur with the chemical formula S2−. It contributes no color to sulfide salts, as it is classified as a strong base, even dilute solutions of salts such as sodium sulfide are corrosive and can attack the skin. Sulfide is the simplest sulfur anion, the systematic names sulfanediide and sulfide, valid IUPAC names, are determined according to the substitutive and additive nomenclatures, respectively. However, the sulfide is also used in compositional IUPAC nomenclature which does not take the nature of bonding involved. Examples of such naming are selenium disulfide and titanium sulfide, which contains no sulfide ions whatsoever, hydrogen sulfide is itself an example of a non-systematic name of this nature. However, it is also a name, and the preferred IUPAC name for sulfane. Sulfide does not exist in appreciable concentrations even in highly alkaline water, the sulfide anion can assimilate a proton by recombination, S2− + H+ → SH− Because of this capture of a proton, sulfide has basic character. In aqueous solution, it has a pKb value of less than 0, in aqueous solution, most sulfide ions are neutralized. S2− + H2O ↽ − ⇀ SH− + OH− Upon treatment with an acid, sulfide converts to hydrogen sulfide. Oxidation of sulfide gives sulfur or sulfate, metal sulfides react with nonmetals including iodine, bromine, and chlorine forming sulfur and metal salts. Such inorganic sulfides typically have low solubility in water. One famous example is the bright yellow species CdS or cadmium yellow, the black tarnish formed on sterling silver is Ag2S. Such species are referred to as salts. In fact, the bonding in transition metal sulfides is highly covalent, which rise to their semiconductor properties. Several have practical applications as pigments, in cells. Aspergillus niger plays a role in the solubilization of heavy metal sulfides, many important metal ores are sulfides. Significant examples include, argentite, cinnabar, galena, molybdenite, pentlandite, realgar, and stibnite, sphalerite, and pyrite, dissolved free sulfides are very aggressive species for the corrosion of many metals such as steel, stainless steel, and copper. Sulfides present in solution are responsible for stress corrosion cracking of steel
Sulfide
–
Sulfide
24.
Carbonate
–
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, a polyatomic ion with the formula of CO2−3. The name may mean an ester of carbonic acid, an organic compound containing the carbonate group C2. In geology and mineralogy, the term carbonate can refer both to carbonate minerals and carbonate rock, and both are dominated by the ion, CO2−3. Carbonate minerals are extremely varied and ubiquitous in chemically precipitated sedimentary rock, sodium carbonate and potassium carbonate have been used since antiquity for cleaning and preservation, as well as for the manufacture of glass. Carbonates are widely used in industry, e. g. in iron smelting, as a raw material for Portland cement and lime manufacture, in the composition of ceramic glazes, the carbonate ion is the simplest oxocarbon anion. It consists of one carbon atom surrounded by three oxygen atoms, in a planar arrangement, with D3h molecular symmetry. It has a mass of 60.01 g/mol and carries a total formal charge of −2. It is the base of the hydrogen carbonate ion, HCO−3. The Lewis structure of the ion has two single bonds to negative oxygen atoms, and one short double bond to a neutral oxygen. This structure is incompatible with the symmetry of the ion. This process is called calcination, after calx, the Latin name of quicklime or calcium oxide, CaO, exceptions include lithium, sodium, potassium and ammonium carbonates, as well as many uranium carbonates. In aqueous solution, carbonate, bicarbonate, carbon dioxide, in strongly basic conditions, the carbonate ion predominates, while in weakly basic conditions, the bicarbonate ion is prevalent. In more acid conditions, aqueous carbon dioxide, CO2, is the main form, thus sodium carbonate is basic, sodium bicarbonate is weakly basic, while carbon dioxide itself is a weak acid. Carbonated water is formed by dissolving CO2 in water under pressure, in living systems an enzyme, carbonic anhydrase, speeds the interconversion of CO2 and carbonic acid. Although the carbonate salts of most metals are insoluble in water, in solution this equilibrium between carbonate, bicarbonate, carbon dioxide and carbonic acid changes consonant to changing temperature and pressure conditions. In the case of ions with insoluble carbonates, e. g. CaCO3. This is an explanation for the buildup of scale inside pipes caused by hard water, in organic chemistry a carbonate can also refer to a functional group within a larger molecule that contains a carbon atom bound to three oxygen atoms, one of which is double bonded. These compounds are known as organocarbonates or carbonate esters, and have the general formula ROCOOR′
Carbonate
–
Carbonate
25.
Reduction (chemistry)
–
Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
Reduction (chemistry)
–
Rusting iron
Reduction (chemistry)
–
Sodium and
fluorine bonding ionically to form
sodium fluoride. Sodium loses its outer
electron to give it a stable
electron configuration, and this electron enters the fluorine atom
exothermically. The oppositely charged ions are then attracted to each other. The sodium is oxidized, and the fluorine is reduced.
Reduction (chemistry)
–
A
bonfire
Reduction (chemistry)
–
Oxides, such as
iron(III) oxide or
rust, which consists of hydrated
iron(III) oxides Fe 2 O 3 · n H 2 O and
iron(III) oxide-hydroxide (FeO(OH), Fe(OH) 3), form when oxygen combines with other elements
26.
Oxidation (chemistry)
–
Redox is a chemical reaction in which the oxidation states of atoms are changed. Any such reaction involves both a process and a complementary oxidation process, two key concepts involved with electron transfer processes. Redox reactions include all chemical reactions in which atoms have their oxidation state changed, in general, the chemical species from which the electron is stripped is said to have been oxidized, while the chemical species to which the electron is added is said to have been reduced. It can be explained in terms, Oxidation is the loss of electrons or an increase in oxidation state by a molecule, atom. Reduction is the gain of electrons or a decrease in state by a molecule, atom. As an example, during the combustion of wood, oxygen from the air is reduced, the reaction can occur relatively slowly, as in the case of rust, or more quickly, as in the case of fire. Redox is a portmanteau of reduction and oxidation, the word oxidation originally implied reaction with oxygen to form an oxide, since dioxygen was historically the first recognized oxidizing agent. Later, the term was expanded to encompass oxygen-like substances that accomplished parallel chemical reactions, ultimately, the meaning was generalized to include all processes involving loss of electrons. The word reduction originally referred to the loss in weight upon heating a metallic ore such as an oxide to extract the metal. In other words, ore was reduced to metal, antoine Lavoisier showed that this loss of weight was due to the loss of oxygen as a gas. Later, scientists realized that the atom gains electrons in this process. The meaning of reduction then became generalized to all processes involving gain of electrons. Even though reduction seems counter-intuitive when speaking of the gain of electrons, it help to think of reduction as the loss of oxygen. Since electrons are charged, it is also helpful to think of this as reduction in electrical charge. The electrochemist John Bockris has used the words electronation and deelectronation to describe reduction and oxidation processes respectively when they occur at electrodes and these words are analogous to protonation and deprotonation, but they have not been widely adopted by chemists. The term hydrogenation could be used instead of reduction, since hydrogen is the agent in a large number of reactions. But, unlike oxidation, which has been generalized beyond its root element, the word redox was first used in 1928. The processes of oxidation and reduction occur simultaneously and cannot happen independently of one another, the oxidation alone and the reduction alone are each called a half-reaction, because two half-reactions always occur together to form a whole reaction
Oxidation (chemistry)
–
Rusting iron
Oxidation (chemistry)
–
Sodium and
fluorine bonding ionically to form
sodium fluoride. Sodium loses its outer
electron to give it a stable
electron configuration, and this electron enters the fluorine atom
exothermically. The oppositely charged ions are then attracted to each other. The sodium is oxidized, and the fluorine is reduced.
Oxidation (chemistry)
–
A
bonfire
Oxidation (chemistry)
–
Oxides, such as
iron(III) oxide or
rust, which consists of hydrated
iron(III) oxides Fe 2 O 3 · n H 2 O and
iron(III) oxide-hydroxide (FeO(OH), Fe(OH) 3), form when oxygen combines with other elements
27.
Malachite
–
Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO32. Individual crystals are rare but do occur as slender to acicular prisms, pseudomorphs after more tabular or blocky azurite crystals also occur. The stones name derives from Greek Μολοχίτης λίθος molochitis lithos, mallow-green stone, from μολόχη molōchē, variant of μαλάχη malāchē, the mineral was given this name due to its resemblance to the leaves of the mallow plant. Archeological evidence indicates that the mineral has been mined and smelted to obtain copper at Timna Valley in Israel for over 3,000 years, since then, malachite has been used as both an ornamental stone and as a gemstone. In ancient Egypt the colour green was associated with death and the power of resurrection as well as new life and they believed that the afterlife contained an eternal paradise which resembled their lives but with no pain or suffering, and referred to this place as the ‘Field of Malachite’. Malachite was used as a pigment in green paints from antiquity until about 1800. The pigment is moderately lightfast, very sensitive to acids, and this natural form of green pigment has been replaced by its synthetic form, verditer, among other synthetic greens. Malachite is also used for decorative purposes, such as in the Malachite Room in the Hermitage, which features a huge malachite vase, and the Malachite Room in Castillo de Chapultepec in Mexico City. The Tazza, a large vase, one of the largest pieces of malachite in North America. Malachite often results from the weathering of copper ores, and is found together with azurite, goethite. Except for its vibrant green color, the properties of malachite are similar to those of azurite, Malachite is more common than azurite and is typically associated with copper deposits around limestones, the source of the carbonate. Large quantities of malachite have been mined in the Urals, Russia, ural malachite is not being mined at present, but G. N Vertushkova reports the possible discovery of new deposits of malachite in the Urals. Virtual tour of the Malachite Room Malachite, Colourlex
Malachite
–
Malachite from the
Democratic Republic of the Congo
Malachite
–
Slice through a double
stalactite, from
Kolwezi, Democratic Republic of the Congo. Size 5.9 × 3.9 × 0.7 cm.
Malachite
–
A polished slab of malachite, from the Democratic Republic of the Congo
Malachite
–
Malachite and
azurite, from
Morenci, Arizona USA. Size 4.4×4.1×2.2 cm.
28.
Copper
–
Copper is a chemical element with symbol Cu and atomic number 29. It is a soft, malleable, and ductile metal with high thermal and electrical conductivity. A freshly exposed surface of copper has a reddish-orange color. Copper is one of the few metals that occur in nature in directly usable metallic form as opposed to needing extraction from an ore and this led to very early human use, from c.8000 BC. Copper used in buildings, usually for roofing, oxidizes to form a green verdigris, Copper is sometimes used in decorative art, both in its elemental metal form and in compounds as pigments. Copper compounds are used as agents, fungicides, and wood preservatives. Copper is essential to all living organisms as a trace dietary mineral because it is a key constituent of the enzyme complex cytochrome c oxidase. In molluscs and crustaceans, copper is a constituent of the blood pigment hemocyanin, replaced by the hemoglobin in fish. In humans, copper is found mainly in the liver, muscle, the adult body contains between 1.4 and 2.1 mg of copper per kilogram of body weight. The filled d-shells in these elements contribute little to interatomic interactions, unlike metals with incomplete d-shells, metallic bonds in copper are lacking a covalent character and are relatively weak. This observation explains the low hardness and high ductility of single crystals of copper, at the macroscopic scale, introduction of extended defects to the crystal lattice, such as grain boundaries, hinders flow of the material under applied stress, thereby increasing its hardness. For this reason, copper is supplied in a fine-grained polycrystalline form. The softness of copper partly explains its high conductivity and high thermal conductivity. The maximum permissible current density of copper in open air is approximately 3. 1×106 A/m2 of cross-sectional area, Copper is one of a few metallic elements with a natural color other than gray or silver. Pure copper is orange-red and acquires a reddish tarnish when exposed to air, as with other metals, if copper is put in contact with another metal, galvanic corrosion will occur. A green layer of verdigris can often be seen on old structures, such as the roofing of many older buildings. Copper tarnishes when exposed to sulfur compounds, with which it reacts to form various copper sulfides. There are 29 isotopes of copper, 63Cu and 65Cu are stable, with 63Cu comprising approximately 69% of naturally occurring copper, both have a spin of 3⁄2
Copper
–
Native copper (~4 cm in size)
Copper
–
A copper disc (99.95% pure) made by
continuous casting;
etched to reveal
crystallites.
Copper
–
Copper just above its melting point keeps its pink luster color when enough light outshines the orange
incandescence color.
Copper
–
Unoxidized copper wire (left) and oxidized copper wire (right).
29.
Water
–
Water is a transparent and nearly colorless chemical substance that is the main constituent of Earths streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen, Water strictly refers to the liquid state of that substance, that prevails at standard ambient temperature and pressure, but it often refers also to its solid state or its gaseous state. It also occurs in nature as snow, glaciers, ice packs and icebergs, clouds, fog, dew, aquifers, Water covers 71% of the Earths surface. It is vital for all forms of life. Only 2. 5% of this water is freshwater, and 98. 8% of that water is in ice and groundwater. Less than 0. 3% of all freshwater is in rivers, lakes, and the atmosphere, a greater quantity of water is found in the earths interior. Water on Earth moves continually through the cycle of evaporation and transpiration, condensation, precipitation. Evaporation and transpiration contribute to the precipitation over land, large amounts of water are also chemically combined or adsorbed in hydrated minerals. Safe drinking water is essential to humans and other even though it provides no calories or organic nutrients. There is a correlation between access to safe water and gross domestic product per capita. However, some observers have estimated that by 2025 more than half of the population will be facing water-based vulnerability. A report, issued in November 2009, suggests that by 2030, in developing regions of the world. Water plays an important role in the world economy, approximately 70% of the freshwater used by humans goes to agriculture. Fishing in salt and fresh water bodies is a source of food for many parts of the world. Much of long-distance trade of commodities and manufactured products is transported by boats through seas, rivers, lakes, large quantities of water, ice, and steam are used for cooling and heating, in industry and homes. Water is an excellent solvent for a variety of chemical substances, as such it is widely used in industrial processes. Water is also central to many sports and other forms of entertainment, such as swimming, pleasure boating, boat racing, surfing, sport fishing, Water is a liquid at the temperatures and pressures that are most adequate for life. Specifically, at atmospheric pressure of 1 bar, water is a liquid between the temperatures of 273.15 K and 373.15 K
Water
–
Water in three states: liquid, solid (
ice), and gas (invisible
water vapor in the air).
Clouds are accumulations of water droplets,
condensed from vapor-saturated air.
Water
–
Impact from a water drop causes an upward "rebound" jet surrounded by circular
capillary waves.
Water
–
Snowflakes by
Wilson Bentley, 1902.
Water
–
Dew drops adhering to a
spider web.
30.
Copper(II) oxide
–
Copper oxide or cupric oxide is the inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or cuprous oxide, as a mineral, it is known as tenorite and paramelaconite. It is a product of copper mining and the precursor to many other copper-containing products and it is produced on a large scale by pyrometallurgy used to extract copper from ores. The ores are treated with a mixture of ammonium carbonate, ammonia, and oxygen to give copper and copper ammine complexes. These complexes are decomposed with steam to give CuO, Copper oxide belongs to the monoclinic crystal system. The copper atom is coordinated by 4 oxygen atoms in a square planar configuration. The work function of bulk CuO is 5. 3eV Copper oxide is a p-type semiconductor, cupric oxide can be used to produce dry cell batteries. As a significant product of copper mining, copper oxide is the point for the production of other copper salts. For example, many wood preservatives are produced from copper oxide, cupric oxide is used as a pigment in ceramics to produce blue, red, and green, and sometimes gray, pink, or black glazes. It is also used as a dietary supplement in animal feed. Due to low bioactivity, negligible copper is absorbed and it is also used when welding with copper alloys. Cupric oxide can be used to dispose of hazardous materials such as cyanide, hydrocarbons, halogenated hydrocarbons and dioxins
Copper(II) oxide
–
Copper(II) oxide
31.
Galena
–
Galena, also called lead glance, is the natural mineral form of lead sulfide. It is the most important ore of lead and an important source of silver, Galena is one of the most abundant and widely distributed sulfide minerals. It crystallizes in the crystal system often showing octahedral forms. It is often associated with the minerals sphalerite, calcite and fluorite, Galena is the main ore of lead, used since ancient times. Because of its low melting point, it was easy to liberate by smelting. In some deposits galena contains about 1–2% silver, a byproduct that far outweighs the main ore in revenue. Galena deposits often contain significant amounts of silver as included silver sulfide mineral phases or as limited solid solution within the galena structure. These argentiferous galenas have long been the most important ore of silver, Galena deposits are found worldwide in various environments. Galena also occurs in North African countries and at Mount Hermon in Northern Israel, in the United States, it occurs most notably in the Mississippi Valley type deposits of the Lead Belt in southeastern Missouri, and in the Driftless Area of Illinois, Iowa and Wisconsin. The economic importance of galena to the history of the Driftless Area was so great that one of the towns in the region was named Galena. Galena also was a mineral of the zinc-lead mines of the tri-state district around Joplin in southwestern Missouri. Galena is also an important ore mineral in the mining regions of Colorado, Idaho, Utah. Of the latter, the Coeur dAlene district of northern Idaho was most prominent, Galena is the official state mineral of the U. S. states of Missouri and Wisconsin, the former mining town of Galena, Kansas takes its name from deposits of this mineral. Derbyshire in the UK was one of the areas where galena was mined. The largest documented crystal of galena is composite cubo-octahedra from the Great Laxey Mine, Isle of Man, Galena belongs to the octahedral sulfide group of minerals that have metal ions in octahedral positions, such as the iron sulfide pyrrhotite and the nickel arsenide niccolite. The galena group is named after its most common member, with other members that include manganese bearing alabandite and niningerite. Divalent lead cations and sulfur anions form a cubic unit cell much like the mineral halite of the halide mineral group. Zinc, cadmium, iron, copper, antimony, arsenic, bismuth, selenium substitutes for sulfur in the structure constituting a solid solution series
Galena
–
Galena close-up
Galena
–
Galena with
baryte and
pyrite from
Cerro de Pasco,
Peru (5.8×4.8×4.4 cm)
Galena
–
Galena with
druzy calcite
Galena
–
Cubic galena with calcite from Jasper County, Missouri, USA (size: 5.1×3.2×2.8 cm)
32.
Lead
–
Lead is a chemical element with atomic number 82 and symbol Pb. When freshly cut, it is bluish-white, it tarnishes to a dull gray upon exposure to air and it is a soft, malleable, and heavy metal with a density exceeding that of most common materials. Lead has the second-highest atomic number of the stable elements. Lead is a relatively unreactive post-transition metal and its weak metallic character is illustrated by its amphoteric nature and tendency to form covalent bonds. Compounds of lead are found in the +2 oxidation state. Exceptions are mostly limited to organolead compounds, like the lighter members of the group, lead exhibits a tendency to bond to itself, it can form chains, rings, and polyhedral structures. Lead is easily extracted from its ores and was known to people in Western Asia. A principal ore of lead, galena, often bears silver, Lead production declined after the fall of Rome and did not reach comparable levels again until the Industrial Revolution. Nowadays, global production of lead is about ten million tonnes annually, Lead has several properties that make it useful, high density, low melting point, ductility, and relative inertness to oxidation. In the late 19th century, lead was recognized as poisonous, Lead is a neurotoxin that accumulates in soft tissues and bones, damaging the nervous system and causing brain disorders and, in mammals, blood disorders. A lead atom has 82 electrons, arranged in a configuration of 4f145d106s26p2. The combined first and second ionization energies—the total energy required to remove the two 6p electrons—is close to that of tin, leads upper neighbor in group 14. This is unusual since ionization energies generally fall going down a group as an elements outer electrons become more distant from the nucleus, the similarity is caused by the lanthanide contraction—the decrease in element radii from lanthanum to lutetium, and the relatively small radii of the elements after hafnium. The contraction is due to shielding of the nucleus by the lanthanide 4f electrons. The combined first four ionization energies of lead exceed those of tin, for this reason lead, unlike tin, mostly forms compounds in which it has an oxidation state of +2, rather than +4. Relativistic effects, which become particularly prominent at the bottom of the periodic table, as a result, the 6s electrons of lead become reluctant to participate in bonding, a phenomenon called the inert pair effect. A related outcome is that the distance between nearest atoms in crystalline lead is unusually long, the lighter group 14 elements form stable or metastable allotropes having the tetrahedrally coordinated and covalently bonded diamond cubic structure. The energy levels of their outer s- and p-orbitals are close enough to allow mixing into four hybrid sp3 orbitals
Lead
–
Lead, 82 Pb
Lead
–
A sample of freshly solidified lead (from molten state)
Lead
–
World lead production peaking in the
Roman period and the rising
Industrial Revolution
Lead
–
Lead
ingots from
Roman Britain on display at the
Wells and Mendip Museum
33.
Lime (material)
–
Lime is a calcium-containing inorganic material in which carbonates, oxides, and hydroxides predominate. In the strict sense of the term, lime is calcium oxide or calcium hydroxide and it is also the name of the natural mineral CaO which occurs as a product of coal seam fires and in altered limestone xenoliths in volcanic ejecta. The word lime originates with its earliest use as building mortar and has the sense of sticking or adhering and these materials are still used in large quantities as building and engineering materials, as chemical feedstocks, and for sugar refining, among other uses. Lime industries and the use of many of the resulting products date from prehistoric times in both the Old World and the New World, Lime is used extensively for wastewater treatment with ferrous sulfate. The rocks and minerals from which these materials are derived, typically limestone or chalk, are composed primarily of calcium carbonate and they may be cut, crushed or pulverized and chemically altered. Lime kilns are the used for lime burning and slaking. When the term is encountered in a context, it usually refers to agricultural lime. Otherwise it most commonly means slaked lime, as the dangerous form is usually described more specifically as quicklime or burnt lime. In the lime industry, limestone is a term for rocks that contain 80% or more of calcium or magnesium carbonates, including marble, chalk, oolite. Further classification is by composition as high calcium, argillaceous, silicious, conglomerate, magnesian, dolomite, uncommon sources of lime include coral, sea shells, calcite, and ankerite. Limestone is extracted from quarries or mines, dry slaking is when quicklime is slaked with just enough water to hydrate the quicklime, but remain as a powder and is referred to as hydrated lime. In wet slaking, enough water, but not too much, is added to hydrate the quicklime to a referred to as lime putty. Because lime has a property with bricks and stones, it is often used as binding material in masonry works. It is also used in whitewashing as wall coat to adhere the whitewash onto the wall, the process by which limestone is converted to quicklime by heating, then to slaked lime by hydration, and naturally reverts to calcium carbonate by carbonation is called the lime cycle. The conditions and compounds present during each step of the cycle have a strong influence of the end product, thus the complex. An example is when slaked lime is mixed into a slurry with sand. When the masonry has been laid, the lime in the mortar slowly begins to react with carbon dioxide to form calcium carbonate according to the reaction. The carbon dioxide that takes part in reaction is principally available in the air or dissolved in rainwater so pure lime mortar will not recarbonate under water or inside a thick masonry wall
Lime (material)
–
Limestone quarry in Brønnøy, Norway
Lime (material)
–
The lime cycle for high-calcium lime.
34.
Gold
–
Gold is a chemical element with symbol Au and atomic number 79. In its purest form, it is a bright, slightly yellow, dense, soft, malleable. Chemically, gold is a metal and a group 11 element. It is one of the least reactive chemical elements and is solid under standard conditions, Gold often occurs in free elemental form, as nuggets or grains, in rocks, in veins, and in alluvial deposits. It occurs in a solid solution series with the element silver and also naturally alloyed with copper. Less commonly, it occurs in minerals as gold compounds, often with tellurium, golds atomic number of 79 makes it one of the higher numbered, naturally occurring elements. It is thought to have produced in supernova nucleosynthesis, from the collision of neutron stars. Because the Earth was molten when it was formed, almost all of the present in the early Earth probably sank into the planetary core. Gold is resistant to most acids, though it does dissolve in aqua regia, a mixture of acid and hydrochloric acid. Gold also dissolves in solutions of cyanide, which are used in mining and electroplating. Gold dissolves in mercury, forming amalgam alloys, but this is not a chemical reaction, as a precious metal, gold has been used for coinage, jewelry, and other arts throughout recorded history. A total of 186,700 tonnes of gold is in existence above ground, the world consumption of new gold produced is about 50% in jewelry, 40% in investments, and 10% in industry. Gold is also used in infrared shielding, colored-glass production, gold leafing, certain gold salts are still used as anti-inflammatories in medicine. As of 2014, the worlds largest gold producer by far was China with 450 tonnes, Gold is cognate with similar words in many Germanic languages, deriving via Proto-Germanic *gulþą from Proto-Indo-European *ǵʰelh₃-. The symbol Au is from the Latin, aurum, the Latin word for gold, the Proto-Indo-European ancestor of aurum was *h₂é-h₂us-o-, meaning glow. This word is derived from the root as *h₂éu̯sōs, the ancestor of the Latin word Aurora. This etymological relationship is presumably behind the frequent claim in scientific publications that aurum meant shining dawn, Gold is the most malleable of all metals, a single gram can be beaten into a sheet of 1 square meter, and an avoirdupois ounce into 300 square feet. Gold leaf can be thin enough to become semi-transparent
Gold
–
Gold, 79 Au
Gold
–
Moche gold necklace depicting feline heads.
Larco Museum Collection. Lima-Peru
Gold
–
Mirror for the future
James Webb Space Telescope coated in gold to reflect infrared light
Gold
–
The
world's largest gold bar has a mass of 250 kg.
Toi museum,
Japan.
35.
Silver
–
Silver is a metallic element with symbol Ag and atomic number 47. The symbol Ag stems from Latin argentum, derived from the Greek ὰργὀς, a soft, white, lustrous transition metal, it exhibits the highest electrical conductivity, thermal conductivity, and reflectivity of any metal. The metal is found in the Earths crust in the pure, free form, as an alloy with gold and other metals. Most silver is produced as a byproduct of copper, gold, lead, Silver is more abundant than gold, but it is much less abundant as a native metal. Its purity is measured on a per mille basis, a 94%-pure alloy is described as 0.940 fine. As one of the seven metals of antiquity, silver has had a role in most human cultures. Silver has long valued as a precious metal. Silver metal is used in many premodern monetary systems in bullion coins, Silver is used in numerous applications other than currency, such as solar panels, water filtration, jewelry, ornaments, high-value tableware and utensils, and as an investment medium. Silver is used industrially in electrical contacts and conductors, in specialized mirrors, window coatings, Silver compounds are used in photographic film and X-rays. Dilute silver nitrate solutions and other compounds are used as disinfectants and microbiocides, added to bandages and wound-dressings, catheters. Silver is similar in its physical and chemical properties to its two neighbours in group 11 of the periodic table, copper and gold. This distinctive electron configuration, with an electron in the highest occupied s subshell over a filled d subshell. Silver is a soft, ductile and malleable transition metal. Silver crystallizes in a cubic lattice with bulk coordination number 12. Unlike metals with incomplete d-shells, metallic bonds in silver are lacking a covalent character and are relatively weak and this observation explains the low hardness and high ductility of single crystals of silver. Silver has a brilliant white metallic luster that can take a polish. Protected silver has greater optical reflectivity than aluminium at all wavelengths longer than ~450 nm, at wavelengths shorter than 450 nm, silvers reflectivity is inferior to that of aluminium and drops to zero near 310 nm. The electrical conductivity of silver is the greatest of all metals, greater even than copper, during World War II in the US,13540 tons of silver were used in electromagnets for enriching uranium, mainly because of the wartime shortage of copper
Silver
–
Electrolytically refined silver
Silver
–
Silver 1000
oz t (~31 kg) bullion bar
Silver
–
Cessna 210 equipped with a silver iodide generator for
cloud seeding
Silver
–
A Canadian 50 cent piece from 1951, with King George the 6th on the obverse and Canada's (now former) coat of arms on the reverse. It is made of 80% silver and 20% copper.
36.
Tin
–
Tin is a chemical element with symbol Sn and atomic number 50. It is a metal in group 14 of the periodic table. It is obtained chiefly from the mineral cassiterite, which contains tin dioxide, Tin shows a chemical similarity to both of its neighbors in group 14, germanium and lead, and has two main oxidation states, +2 and the slightly more stable +4. Tin is the 49th most abundant element and has, with 10 stable isotopes, metallic tin is not easily oxidized in air. The first alloy used on a scale was bronze, made of tin and copper. After 600 BC, pure metallic tin was produced, pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper, antimony, and lead, was used for flatware from the Bronze Age until the 20th century. In modern times, tin is used in alloys, most notably tin/lead soft solders. Another large application for tin is corrosion-resistant tin plating of steel, inorganic tin compounds are rather non-toxic. Because of its low toxicity, tin-plated metal was used for packaging as tin cans. However, overexposure to tin may cause problems with metabolizing essential trace elements such as copper and zinc, Tin is a soft, malleable, ductile and highly crystalline silvery-white metal. When a bar of tin is bent, a sound known as the tin cry can be heard from the twinning of the crystals. Tin melts at the low temperature of about 232 °C, the lowest in group 14, the melting point is further lowered to 177.3 °C for 11 nm particles. β-tin, which is stable at and above room temperature, is malleable, in contrast, α-tin, which is stable below 13.2 °C, is brittle. α-tin has a cubic crystal structure, similar to diamond. α-tin has no properties at all because its atoms form a covalent structure in which electrons cannot move freely. It is a dull-gray powdery material with no common uses other than a few specialized semiconductor applications and these two allotropes, α-tin and β-tin, are more commonly known as gray tin and white tin, respectively. Two more allotropes, γ and σ, exist at temperatures above 161 °C, in cold conditions, β-tin tends to transform spontaneously into α-tin, a phenomenon known as tin pest. Commercial grades of tin resist transformation because of the effect of the small amounts of bismuth, antimony, lead
Tin
–
left: white, beta, β; right: gray, alpha, α
Tin
–
Droplet of solidified molten tin
Tin
–
Ceremonial giant bronze
dirk of the Plougrescant-Ommerschans type, Plougrescant, France, 1500–1300 BC.
Tin
–
Sample of cassiterite, the main
ore of tin.
37.
Iron
–
Iron is a chemical element with symbol Fe and atomic number 26. It is a metal in the first transition series and it is by mass the most common element on Earth, forming much of Earths outer and inner core. It is the fourth most common element in the Earths crust, like the other group 8 elements, ruthenium and osmium, iron exists in a wide range of oxidation states, −2 to +6, although +2 and +3 are the most common. Elemental iron occurs in meteoroids and other low oxygen environments, but is reactive to oxygen, fresh iron surfaces appear lustrous silvery-gray, but oxidize in normal air to give hydrated iron oxides, commonly known as rust. Unlike the metals that form passivating oxide layers, iron oxides occupy more volume than the metal and thus flake off, Iron metal has been used since ancient times, although copper alloys, which have lower melting temperatures, were used even earlier in human history. Pure iron is soft, but is unobtainable by smelting because it is significantly hardened and strengthened by impurities, in particular carbon. A certain proportion of carbon steel, which may be up to 1000 times harder than pure iron. Crude iron metal is produced in blast furnaces, where ore is reduced by coke to pig iron, further refinement with oxygen reduces the carbon content to the correct proportion to make steel. Steels and iron alloys formed with metals are by far the most common industrial metals because they have a great range of desirable properties. Iron chemical compounds have many uses, Iron oxide mixed with aluminium powder can be ignited to create a thermite reaction, used in welding and purifying ores. Iron forms binary compounds with the halogens and the chalcogens, among its organometallic compounds is ferrocene, the first sandwich compound discovered. Iron plays an important role in biology, forming complexes with oxygen in hemoglobin and myoglobin. Iron is also the metal at the site of many important redox enzymes dealing with cellular respiration and oxidation and reduction in plants. A human male of average height has about 4 grams of iron in his body and this iron is distributed throughout the body in hemoglobin, tissues, muscles, bone marrow, blood proteins, enzymes, ferritin, hemosiderin, and transport in plasma. The mechanical properties of iron and its alloys can be evaluated using a variety of tests, including the Brinell test, Rockwell test, the data on iron is so consistent that it is often used to calibrate measurements or to compare tests. An increase in the content will cause a significant increase in the hardness. Maximum hardness of 65 Rc is achieved with a 0. 6% carbon content, because of the softness of iron, it is much easier to work with than its heavier congeners ruthenium and osmium. Because of its significance for planetary cores, the properties of iron at high pressures and temperatures have also been studied extensively
Iron
–
Iron, 26 Fe
Iron
–
Spectral lines of iron
Iron
–
Iron meteorites, similar in composition to the Earth's inner- and outer core
Iron
–
Hydrated
iron(III) chloride, also known as ferric chloride
38.
Mercury (element)
–
Mercury is a chemical element with symbol Hg and atomic number 80. It is commonly known as quicksilver and was formerly named hydrargyrum, Mercury occurs in deposits throughout the world mostly as cinnabar. The red pigment vermilion is obtained by grinding natural cinnabar or synthetic mercuric sulfide, likewise, mechanical pressure gauges and electronic strain gauge sensors have replaced mercury sphygmomanometers. Mercury remains in use in research applications and in amalgam for dental restoration in some locales. It is used in fluorescent lighting, electricity passed through mercury vapor in a fluorescent lamp produces short-wave ultraviolet light which then causes the phosphor in the tube to fluoresce, making visible light. Mercury poisoning can result from exposure to water-soluble forms of mercury, Mercury is a heavy, silvery-white liquid metal. Compared to other metals, it is a conductor of heat. It has a point of −38.83 °C and a boiling point of 356.73 °C. Upon freezing, the volume of mercury decreases by 3. 59%, the coefficient of volume expansion is 181.59 × 10−6 at 0 °C,181.71 × 10−6 at 20 °C and 182.50 × 10−6 at 100 °C. Solid mercury is malleable and ductile and can be cut with a knife, because this configuration strongly resists removal of an electron, mercury behaves similarly to noble gases, which form weak bonds and hence melt at low temperatures. The stability of the 6s shell is due to the presence of a filled 4f shell, an f shell poorly screens the nuclear charge that increases the attractive Coulomb interaction of the 6s shell and the nucleus. Like silver, mercury reacts with hydrogen sulfide. Mercury reacts with solid sulfur flakes, which are used in mercury spill kits to absorb mercury, Mercury dissolves many other metals such as gold and silver to form amalgams. Iron is an exception, and iron flasks have traditionally used to trade mercury. Several other first row transition metals with the exception of manganese, copper, other elements that do not readily form amalgams with mercury include platinum. Sodium amalgam is a reducing agent in organic synthesis, and is also used in high-pressure sodium lamps. Mercury readily combines with aluminium to form a mercury-aluminium amalgam when the two pure metals come into contact, since the amalgam destroys the aluminium oxide layer which protects metallic aluminium from oxidizing in-depth, even small amounts of mercury can seriously corrode aluminium. For this reason, mercury is not allowed aboard an aircraft under most circumstances because of the risk of it forming an amalgam with exposed aluminium parts in the aircraft, Mercury embrittlement is the most common type of liquid metal embrittlement
Mercury (element)
–
Mercury, 80 Hg
Mercury (element)
–
Spectral lines of mercury (UV not seen)
Mercury (element)
–
A
pound coin (density ~7.6 g/cm 3) floats in mercury due to the combination of the
buoyant force and
surface tension.
Mercury (element)
–
Mercury-discharge spectral calibration lamp
39.
Native copper
–
Native copper is an uncombined form of copper which occurs as a natural mineral. Copper is one of the few elements to occur in native form, although it most commonly occurs in oxidized states. Native copper was an important ore of copper in historic times and was used by pre-historic peoples, native copper occurs rarely as isometric cubic and octahedral crystals, but more typically as irregular masses and fracture fillings. It has a reddish, orangish, and/or brownish color on fresh surfaces and its specific gravity is 8.9 and its hardness is 2. 5–3. The mines of the Keweenaw native copper deposits of Upper Michigan were major producers in the 19th and early 20th centuries. The first commercial mines in the Keweenaw Peninsula opened in the 1840s, isle Royale in western Lake Superior was also a site of many tons of native copper. Some of it was extracted by native peoples, but only one of several attempts at mining turned a profit there. Another major native copper deposit is in Coro Coro, Bolivia, the name copper comes from the Greek kyprios, of Cyprus, the location of copper mines since pre-historic times
Native copper
–
Native copper from Ray mine, Arizona (specimen 5.25 x 4 x 1 cm)
40.
Alumina
–
Aluminium oxide or Aluminum oxide is a chemical compound of aluminium and oxygen with the chemical formula Al2O3. It is the most commonly occurring of several aluminium oxides, and it is commonly called alumina, and may also be called aloxide, aloxite, or alundum depending on particular forms or applications. It occurs naturally in its crystalline polymorphic phase α-Al2O3 as the mineral corundum, varieties of form the precious gemstones ruby. Al2O3 is significant in its use to produce metal, as an abrasive owing to its hardness. Corundum is the most common naturally occurring form of aluminium oxide. Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colors to trace impurities, rubies are given their characteristic deep red color and their laser qualities by traces of chromium. Sapphires come in different colors given by various other impurities, such as iron, Al2O3 is an electrical insulator but has a relatively high thermal conductivity for a ceramic material. Aluminium oxide is insoluble in water, in its most commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools. Aluminium oxide is responsible for the resistance of aluminium to weathering. Metallic aluminium is very reactive with oxygen, and a thin passivation layer of aluminium oxide forms on any exposed aluminium surface. This layer protects the metal from further oxidation, the thickness and properties of this oxide layer can be enhanced using a process called anodising. A number of alloys, such as bronzes, exploit this property by including a proportion of aluminium in the alloy to enhance corrosion resistance. Aluminium oxide was taken off the United States Environmental Protection Agencys chemicals lists in 1988, aluminium oxide is on EPAs Toxics Release Inventory list if it is a fibrous form. Al2O3 +6 HF →2 AlF3 +3 H2O Al2O3 +2 NaOH +3 H2O →2 NaAl4 The most common form of aluminium oxide is known as corundum. The oxygen ions form a hexagonal close-packed structure with aluminium ions filling two-thirds of the octahedral interstices. In terms of its crystallography, corundum adopts a trigonal Bravais lattice with a group of R-3c. The primitive cell contains two units of aluminium oxide. Each has a crystal structure and properties
Alumina
Alumina
–
Aluminium oxide
Alumina
–
Corundum from
Brazil, size about 2×3 cm.
41.
Roasting (metallurgy)
–
Roasting is a process of heating of concentrated ore to a high temperature in presence of air. It is a step of the processing of certain ores, more specifically, roasting is a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component. Often before roasting, the ore has already been partially purified, the concentrate is mixed with other materials to facilitate the process. The technology is useful but is also a source of air pollution. Roasting consists of thermal gas–liquid reactions, which can include oxidation, reduction, chlorination, sulfation, in roasting, the ore or ore concentrate is treated with very hot air. This process is applied to sulphide minerals. During roasting, the sulphide is converted to an oxide, and sulphur is released as sulphur dioxide, many sulfide minerals contain other components such as arsenic that are released into the environment. Up until the early 20th century, roasting was started by burning wood on top of ore and this would raise the temperature of the ore to the point where its sulfur content would become its source of fuel, and the roasting process could continue without external fuel sources. Early sulfide roasting was practiced in this manner in open hearth roasters and this process released large amounts of acidic, metallic, and other toxic compounds. For sulfide roasting, the reaction can be given by - MS +1.5 O2 = MO + SO2 Roasting the sulfide ore, till almost complete removal of the sulfur from the ore. Volatilizing roasting, involves careful oxidation at elevated temperatures of the ores, examples of such volatile oxides include As2O3, Sb2O3, ZnO and sulfur oxides. Careful control of the content in the roaster is necessary. Chloridizing roasting transforms certain metal compounds to chlorides, through oxidation or reduction, some metals like uranium, titanium, beryllium and some rare earths are processed in their chloride form. The second reaction involving an ore is facilitated by addition of elemental sulfur. Carbonate ores react in a manner as the oxide ore. Sulfating roasting oxidizes certain sulfide ores to sulfates in a supply of air to enable leaching of the sulfate for further processing. Magnetic roasting involves controlled roasting of the ore to convert it into a form, thus enabling easy separation. For example, controlled reduction of haematite to magnetite, reduction roasting partially reduces an oxide ore before the actual smelting process
Roasting (metallurgy)
–
Roasted gold ore from
Cripple Creek, Colorado. Roasting has driven off the
tellurium from the original
calaverite, leaving behind vesicular blebs of native gold.
42.
Old World
–
The Old World consists of Africa, Europe, and Asia, regarded collectively as the part of the world known to Europeans before contact with the Americas. It is used in the context of, and contrast with and these regions were connected via the Silk Road trade route, and they have a pronounced Iron Age period following the Bronze Age. The concept of the three continents in the Old World, viz. Asia, Africa, and Europe, goes back to classical antiquity and their boundaries as defined by Ptolemy and other geographers of antiquity were drawn along the Nile and Don rivers. This definition remained influential throughout the Middle Ages and the Early Modern period, the Old world has areas of North Africa, Eurasia, parts of Papua New Guinea and Solomon Islands. The mainland of Afro-Eurasia has been referred to as the World Island, the term may have been coined by Sir Halford John Mackinder in The Geographical Pivot of History. The equivalent of the Old World had names in some of its ancient cultures, including Midgard in Germanic cosmology, synoptic table of the principal old world prehistoric cultures Afro-Eurasia
Old World
–
Map of the "Old World" (the
Ptolemy world map in a 15th-century copy)
43.
Prehistory
–
Prehistory means literally before history, from the Latin word for before, præ, and Greek ιστορία. Neighbouring civilisations were the first to follow, most other civilisations reached the end of prehistory during the Iron Age. The period when a culture is written about by others, but has not developed its own writing is known as the protohistory of the culture. By definition, there are no records from human prehistory. Clear techniques for dating were not well-developed until the 19th century and this article is concerned with human prehistory as defined here above. There are separate articles for the history of the Earth. However, for the race as a whole, prehistory ends when recorded history begins with the accounts of the ancient world around the 4th millennium BC. For example, in Egypt it is accepted that prehistory ended around 3200 BC, whereas in New Guinea the end of the prehistoric era is set much more recently. The three-age system is the periodization of prehistory into three consecutive time periods, named for their respective predominant tool-making technologies, Stone Age Bronze Age Iron Age. The notion of prehistory began to surface during the Enlightenment in the work of antiquarians who used the word primitive to describe societies that existed before written records, the first use of the word prehistory in English, however, occurred in the Foreign Quarterly Review in 1836. The main source for prehistory is archaeology, but some scholars are beginning to more use of evidence from the natural and social sciences. This view has been articulated by advocates of deep history, human population geneticists and historical linguists are also providing valuable insight for these questions. Human prehistory differs from history not only in terms of its chronology, restricted to material processes, remains and artifacts rather than written records, prehistory is anonymous. Because of this, reference terms that use, such as Neanderthal or Iron Age are modern labels with definitions sometimes subject to debate. Palaeolithic means Old Stone Age, and begins with the first use of stone tools, the Paleolithic is the earliest period of the Stone Age. The early part of the Palaeolithic is called the Lower Palaeolithic, evidence of control of fire by early humans during the Lower Palaeolithic Era is uncertain and has at best limited scholarly support. The most widely accepted claim is that H. erectus or H. ergaster made fires between 790,000 and 690,000 BP in a site at Bnot Yaakov Bridge, Israel. The use of fire enabled early humans to cook food, provide warmth, Early Homo sapiens originated some 200,000 years ago, ushering in the Middle Palaeolithic
Prehistory
–
Massive stone pillars at
Göbekli Tepe, in southeast Turkey, erected for ritual use by early
Neolithic people 11,000 years ago.
Prehistory
–
A prehistoric man and boy.
Prehistory
–
Dugout canoe
Prehistory
–
Entrance to the Ġgantija phase temple complex of
Hagar Qim,
Malta, 3900 BC.
44.
Stone Age
–
The Stone Age was a broad prehistoric period during which stone was widely used to make implements with an edge, a point, or a percussion surface. The period lasted roughly 3.4 million years, and ended between 8700 BCE and 2000 BCE with the advent of metalworking, bone tools were used during this period as well but are rarely preserved in the archaeological record. The Stone Age is further subdivided by the types of tools in use. According to the age and location of the current evidence, the cradle of the genus is the East African Rift System, especially toward the north in Ethiopia, where it is bordered by grasslands. The closest relative among the living primates, the genus Pan, represents a branch that continued on in the deep forest. The rift served as a conduit for movement into southern Africa and also north down the Nile into North Africa and through the continuation of the rift in the Levant to the vast grasslands of Asia. The oldest indirect evidence found of stone tool use is fossilised animal bones with tool marks, the oldest stone tools were excavated from the site of Lomekwi 3 in West Turkana, northwestern Kenya, and date to 3.3 million years old. Prior to the discovery of these Lomekwian tools, the oldest known stone tools had been found at sites at Gona, Ethiopia, on the sediments of the paleo-Awash River. All the tools come from the Busidama Formation, which lies above a disconformity, or missing layer, the oldest sites containing tools are dated to 2. 6–2.55 mya. One of the most striking circumstances about these sites is that they are from the Late Pliocene, excavators at the locality point out that. the earliest stone tool makers were skilled flintknappers. The possible reasons behind this seeming abrupt transition from the absence of tools to the presence thereof include. The species who made the Pliocene tools remains unknown, fragments of Australopithecus garhi, Australopithecus aethiopicus and Homo, possibly Homo habilis, have been found in sites near the age of the Gona tools. Innovation of the technique of smelting ore ended the Stone Age, the first most significant metal manufactured was bronze, an alloy of copper and tin, each of which was smelted separately. The Chalcolithic by convention is the period of the Bronze Age. The Bronze Age was followed by the Iron Age, the transition out of the Stone Age occurred between 6000 BCE and 2500 BCE for much of humanity living in North Africa and Eurasia. Note the Rudna Glava mine in Serbia, Ötzi the Iceman, a mummy from about 3300 BCE carried with him a copper axe and a flint knife. In regions such as Sub-Saharan Africa, the Stone Age was followed directly by the Iron Age, the Middle East and southeastern Asian regions progressed past Stone Age technology around 6000 BCE. Europe, and the rest of Asia became post–Stone Age societies by about 4000 BCE, the proto-Inca cultures of South America continued at a Stone Age level until around 2000 BCE, when gold, copper and silver made their entrance
Stone Age
–
Obsidian projectile point
Stone Age
–
Modern
Awash River, Ethiopia, descendant of the Palaeo-Awash, source of the sediments in which the oldest Stone Age tools have been found
Stone Age
–
A variety of
stone tools
Stone Age
–
This is a Mode 1, or Oldowan,
stone tool from the western Sahara.
45.
Bronze Age
–
The Bronze Age is a historical period characterized by the use of bronze, proto-writing, and other early features of urban civilization. The Bronze Age is the principal period of the three-age Stone-Bronze-Iron system, as proposed in modern times by Christian Jürgensen Thomsen. An ancient civilization is defined to be in the Bronze Age either by smelting its own copper and alloying with tin, arsenic, or other metals, or by trading for bronze from production areas elsewhere. Copper-tin ores are rare, as reflected in the fact there were no tin bronzes in Western Asia before trading in bronze began in the third millennium BC. Worldwide, the Bronze Age generally followed the Neolithic period, with the Chalcolithic serving as a transition, although the Iron Age generally followed the Bronze Age, in some areas, the Iron Age intruded directly on the Neolithic. Bronze Age cultures differed in their development of the first writing, according to archaeological evidence, cultures in Mesopotamia and Egypt developed the earliest viable writing systems. The overall period is characterized by use of bronze, though the place and time of the introduction. Human-made tin bronze technology requires set production techniques, tin must be mined and smelted separately, then added to molten copper to make bronze alloy. The Bronze Age was a time of use of metals. The dating of the foil has been disputed, the Bronze Age in the ancient Near East began with the rise of Sumer in the 4th millennium BC. Societies in the region laid the foundations for astronomy and mathematics, the usual tripartite division into an Early, Middle and Late Bronze Age is not used. Instead, a division based on art-historical and historical characteristics is more common. The cities of the Ancient Near East housed several tens of thousands of people, ur in the Middle Bronze Age and Babylon in the Late Bronze Age similarly had large populations. The earliest mention of Babylonia appears on a tablet from the reign of Sargon of Akkad in the 23rd century BC, the Amorite dynasty established the city-state of Babylon in the 19th century BC. Over 100 years later, it took over the other city-states. Babylonia adopted the written Semitic Akkadian language for official use, by that time, the Sumerian language was no longer spoken, but was still in religious use. Elam was an ancient civilization located to the east of Mesopotamia, in the Old Elamite period, Elam consisted of kingdoms on the Iranian plateau, centered in Anshan, and from the mid-2nd millennium BC, it was centered in Susa in the Khuzestan lowlands. Its culture played a role in the Gutian Empire and especially during the Achaemenid dynasty that succeeded it
Bronze Age
–
Chalcolithic copper mine in
Timna Valley,
Negev Desert,
Israel.
Bronze Age
–
Diffusion of metallurgy in
Europe and
Asia Minor. The darkest areas are the oldest.
Bronze Age
–
A
Shang Dynasty two-handled bronze gefuding gui (1600–1046 BC).
Bronze Age
–
Spring and Autumn Period pu bronze vessel with interlaced
dragon design (722–481 BC)
46.
Iron Age
–
The Iron Age is an archaeological era, referring to a period of time in the prehistory and protohistory of the Old World when the dominant toolmaking material was iron. It is commonly preceded by the Bronze Age in Europe and Asia with exceptions, meteoric iron has been used by humans since at least 3200 BC. Ancient iron production did not become widespread until the ability to smelt ore, remove impurities. The start of the Iron Age proper is considered by many to fall between around 1200 BC and 600 BC, depending on the region, the earliest known iron artifacts are nine small beads dated to 3200 BC, which were found in burials at Gerzeh, Lower Egypt. They have been identified as meteoric iron shaped by careful hammering, meteoric iron, a characteristic iron–nickel alloy, was used by various ancient peoples thousands of years before the Iron Age. Such iron, being in its metallic state, required no smelting of ores. Smelted iron appears sporadically in the record from the middle Bronze Age. While terrestrial iron is abundant, its high melting point of 1,538 °C placed it out of reach of common use until the end of the second millennium BC. Tins low melting point of 231, similarly, recent archaeological remains of iron working in the Ganges Valley in India have been tentatively dated to 1800 BC. By the Middle Bronze Age, increasing numbers of smelted iron objects appeared in the Middle East, Southeast Asia, African sites are turning up dates as early as 1200 BC. Modern archaeological evidence identifies the start of iron production in around 1200 BC. Between 1200 BC and 1000 BC, diffusion in the understanding of iron metallurgy and use of objects was fast. As evidence, many bronze implements were recycled into weapons during this time, more widespread use of iron led to improved steel-making technology at lower cost. Thus, even when tin became available again, iron was cheaper, stronger, and lighter, and forged iron implements superseded cast bronze tools permanently. Increasingly, the Iron Age in Europe is being seen as a part of the Bronze Age collapse in the ancient Near East, in ancient India, ancient Iran, and ancient Greece. In other regions of Europe, the Iron Age began in the 8th century BC in Central Europe, the Near Eastern Iron Age is divided into two subsections, Iron I and Iron II. Iron I illustrates both continuity and discontinuity with the previous Late Bronze Age, during the Iron Age, the best tools and weapons were made from steel, particularly alloys which were produced with a carbon content between approximately 0. 30% and 1. 2% by weight. Steel weapons and tools were nearly the same weight as those of bronze, however, steel was difficult to produce with the methods available, and alloys that were easier to make, such as wrought iron, were more common in lower-priced goods
Iron Age
–
Archaeological artifact from the work developed in the area of
Citânia de Briteiros
Iron Age
Iron Age
–
Cross or cruzado in Citânia de Breteiros
Iron Age
–
A pedra formosa
47.
Americas
–
The Americas, also collectively called America, encompass the totality of the continents of North America and South America. Together they make up most of the land in Earths western hemisphere, along with their associated islands, they cover 8% of Earths total surface area and 28. 4% of its land area. The topography is dominated by the American Cordillera, a chain of mountains that runs the length of the west coast. The flatter eastern side of the Americas is dominated by river basins, such as the Amazon, St. Lawrence River / Great Lakes basin, Mississippi. Humans first settled the Americas from Asia between 42,000 and 17,000 years ago, a second migration of Na-Dene speakers followed later from Asia. The subsequent migration of the Inuit into the neoarctic around 3500 BCE completed what is regarded as the settlement by the indigenous peoples of the Americas. The first known European settlement in the Americas was by the Norse explorer Leif Ericson, however, the colonization never became permanent and was later abandoned. The voyages of Christopher Columbus from 1492 to 1502 resulted in permanent contact with European powers, diseases introduced from Europe and Africa devastated the indigenous peoples, and the European powers colonized the Americas. Mass emigration from Europe, including numbers of indentured servants. Decolonization of the Americas began with the American Revolution in 1776, the population is over 1 billion, with over 65% of them living in one of the three most populous countries. As of the beginning of the 2010s, the most populous urban agglomerations are Mexico City, New York, Sao Paulo, Los Angeles, Buenos Aires and Rio de Janeiro, all of them megacities. The name America was first recorded in 1507 in the Cosmographiae Introductio, apparently written by Matthias Ringmann and it first applied to both North and South America by Gerardus Mercator in 1538. Amerigen means land of Amerigo and derives from Amerigo and gen, America accorded with the feminine names of Asia, Africa, and Europa. When conceived as a continent, the form is generally the continent of America in the singular. However, without a context, singular America in English commonly refers to the United States of America. In some countries of the world, America is considered a continent encompassing the North America and South America subcontinents, the first inhabitants migrated into the Americas from Asia. Habitation sites are known in Alaska and the Yukon from at least 20,000 years ago, beyond that, the specifics of the Paleo-Indian migration to and throughout the Americas, including the dates and routes traveled, are subject to ongoing research and discussion. Widespread habitation of the Americas occurred during the glacial maximum
Americas
–
CIA political map of the Americas in
Lambert azimuthal equal-area projection
Americas
–
The Americas
Americas
–
Parkin Site, a Mississippian site in Arkansas, circa 1539.
Americas
–
World map of
Waldseemüller (Germany, 1507), which first used the name America (in the lower-left section, over South America)
48.
Inca
–
The Inca Empire, also known as the Incan Empire and the Inka Empire, was the largest empire in pre-Columbian America, and possibly the largest empire in the world in the early 16th century. The administrative, political and military center of the empire was located in Cusco in modern-day Peru, the Inca civilization arose from the highlands of Peru sometime in the early 13th century. Its last stronghold was conquered by the Spanish in 1572, from 1438 to 1533, the Incas incorporated a large portion of western South America, centered on the Andean Mountains, using conquest and peaceful assimilation, among other methods. The Incas considered their king, the Sapa Inca, to be the son of the sun, the Inca Empire was unique in that it lacked many features associated with civilization in the Old world. In the words of one scholar, The Incas lacked the use of wheeled vehicles, the Incan economy has been described as feudal, slave, socialist. The economy functioned largely without money and without markets, instead, exchange of goods and services was based on reciprocity between individuals and among individuals, groups, and Inca rulers. Taxes consisted of an obligation of a person to the Empire. The Inca rulers reciprocated by granting access to land and goods and providing food, the Inca referred to their empire as Tawantinsuyu, the four suyu. The four suyu were, Chinchaysuyu, Antisuyu, Qullasuyu and Kuntisuyu, the name Tawantinsuyu was, therefore, a descriptive term indicating a union of provinces. The Spanish transliterated the name as Tahuatinsuyo or Tahuatinsuyu, the term Inka means ruler or lord in Quechua and was used to refer to the ruling class or the ruling family. The Incas were a small percentage of the total population of the empire, probably numbering only 15,000 to 40,000. The Spanish adopted the term as a term referring to all subjects of the empire rather than simply the ruling class. As such the name Imperio inca referred to the nation that they encountered, the Inca people were a pastoral tribe in the Cusco area around the 12th century. Incan oral history tells a story of three caves. The center cave at Tampu Tuqu was named Qhapaq Tuqu, the other caves were Maras Tuqu and Sutiq Tuqu. Four brothers and four sisters stepped out of the middle cave and they were, Ayar Manco, Ayar Cachi, Ayar Awqa and Ayar Uchu, and Mama Ocllo, Mama Raua, Mama Huaco and Mama Qura. Out of the side caves came the people who were to be the ancestors of all the Inca clans, Ayar Manco carried a magic staff made of the finest gold. Where this staff landed, the people would live and they traveled for a long time
Inca
–
Inca Empire
Inca
–
Banner of the Tawantinsuyu
Inca
–
The first image of the Inca in Europe,
Pedro Cieza de León, Cronica del Peru, 1553
Inca
–
View of
Machu Picchu
49.
Andes
–
The Andes or Andean Mountains are the longest continental mountain range in the world. They are a range of highlands along the western edge of South America. This range is about 7,000 km long, about 200 to 700 km wide, the Andes extend from north to south through seven South American countries, Venezuela, Colombia, Ecuador, Peru, Bolivia, Argentina and Chile. Along their length, the Andes are split into several ranges, the Andes are the location of several high plateaus – some of which host major cities, such as Quito, Bogotá, Arequipa, Medellín, Sucre, Mérida and La Paz. The Altiplano plateau is the worlds second-highest after the Tibetan plateau and these ranges are in turn grouped into three major divisions based on climate, the Tropical Andes, the Dry Andes, and the Wet Andes. The Andes are the worlds highest mountain range outside of Asia, the highest mountain outside Asia, Mount Aconcagua, rises to an elevation of about 6,961 m above sea level. The peak of Chimborazo in the Ecuadorean Andes is farther from the Earths center than any other location on the Earths surface, the worlds highest volcanoes are in the Andes, including Ojos del Salado on the Chile-Argentina border, which rises to 6,893 m. The etymology of the word Andes has been debated, the majority consensus is that it derives from the Quechua word anti, which means east as in Antisuyu, one of the four regions of the Inca Empire. In the northern part of the Andes, the isolated Sierra Nevada de Santa Marta range is considered to be part of the Andes. The term cordillera comes from the Spanish word cordel, meaning rope, the Andes range is about 200 km wide throughout its length, except in the Bolivian flexure where it is about 640 kilometres wide. The Andes are the result of plate tectonics processes, caused by the subduction of oceanic crust beneath the South American plate. The main cause of the rise of the Andes is the compression of the rim of the South American Plate due to the subduction of the Nazca Plate. In the south, the Andes share a boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, from a geographical approach, the Andes are considered to have their western boundaries marked by the appearance of coastal lowlands and a less rugged topography. The Andes Mountains also contain large quantities of iron ore located in mountains within the range. The Andean orogen has a series of bends or oroclines, the Bolivian Orocline is a seaward concave bending in the coast of South America and the Andes Mountains at about 18° S. At this point the orientation of the Andes turns from Northwest in Peru to South in Chile, the Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively. The Bolivian Orocline area overlaps with the area of maximum width of the Altiplano Plateau, the specific point at 18° S where the coastline bends is known as the Arica Elbow
Andes
–
Aerial photo of a portion of the Andes between
Argentina and
Chile
Andes
Andes
–
"
Cono de Arita " in the
Puna de Atacama,
Salta (
Argentina).
Andes
–
Aerial view of Aconcagua.
50.
Anatolia
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Anatolia, in geography known as Asia Minor, Asian Turkey, Anatolian peninsula, or Anatolian plateau, is the westernmost protrusion of Asia, which makes up the majority of modern-day Turkey. The region is bounded by the Black Sea to the north, the Mediterranean Sea to the south, the Sea of Marmara forms a connection between the Black and Aegean Seas through the Bosphorus and Dardanelles straits and separates Anatolia from Thrace on the European mainland. Traditionally, Anatolia is considered to extend in the east to a line between the Gulf of Alexandretta and the Black Sea to the Armenian Highlands, thus, traditionally Anatolia is the territory that comprises approximately the western two-thirds of the Asian part of Turkey. The Turkification of Anatolia began under the Seljuk Empire in the late 11th century, however, various non-Turkic languages continue to be spoken by minorities in Anatolia today, including Kurdish, Assyrian, Armenian, Arabic, Laz, Georgian, and Greek. Traditionally, Anatolia is considered to extend in the east to a line running from the Gulf of Alexandretta to the Black Sea. This traditional geographical definition is used, for example, in the latest edition of Merriam-Websters Geographical Dictionary, under this definition, Anatolia is bounded to the east by the Armenian Highlands, and the Euphrates before that river bends to the southeast to enter Mesopotamia. To the southeast, it is bounded by the ranges that separate it from the Orontes valley in Syria, the first name the Greeks used for the Anatolian peninsula was Ἀσία, presumably after the name of the Assuwa league in western Anatolia. As the name of Asia came to be extended to areas east of the Mediterranean. The name Anatolia derives from the Greek ἀνατολή meaning “the East” or more literally “sunrise”, the precise reference of this term has varied over time, perhaps originally referring to the Aeolian, Ionian and Dorian colonies on the west coast of Asia Minor. In the Byzantine Empire, the Anatolic Theme was a theme covering the western, the modern Turkish form of Anatolia is Anadolu, which again derives from the Greek name Aνατολή. The Russian male name Anatoly and the French Anatole share the same linguistic origin, in English the name of Turkey for ancient Anatolia first appeared c. It is derived from the Medieval Latin Turchia, which was used by the Europeans to define the Seljuk controlled parts of Anatolia after the Battle of Manzikert. Human habitation in Anatolia dates back to the Paleolithic, neolithic Anatolia has been proposed as the homeland of the Indo-European language family, although linguists tend to favour a later origin in the steppes north of the Black Sea. However, it is clear that the Anatolian languages, the oldest branch of Indo-European, have spoken in Anatolia since at least the 19th century BC. The earliest historical records of Anatolia stem from the southeast of the region and are from the Mesopotamian-based Akkadian Empire during the reign of Sargon of Akkad in the 24th century BC, scholars generally believe the earliest indigenous populations of Anatolia were the Hattians and Hurrians. The region was famous for exporting raw materials, and areas of Hattian-, one of the numerous cuneiform records dated circa 20th century BC, found in Anatolia at the Assyrian colony of Kanesh, uses an advanced system of trading computations and credit lines. They were speakers of an Indo-European language, the Hittite language, originating from Nesa, they conquered Hattusa in the 18th century BC, imposing themselves over Hattian- and Hurrian-speaking populations. According to the most widely accepted Kurgan theory on the Proto-Indo-European homeland, however, the Hittites adopted the cuneiform script, invented in Mesopotamia
Anatolia
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The traditional definition of Anatolia within modern Turkey
Anatolia
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The location of
Turkey (within the rectangle) in reference to the
European continent. Anatolia roughly corresponds to the
Asian part of Turkey, except the eastern parts historically known as the
Armenian Highlands
Anatolia
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1907 map of Asia Minor, showing the local ancient kingdoms
Anatolia
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Mural of
aurochs, a
deer, and humans in
Çatalhöyük, which is the largest and best-preserved Neolithic site found to date. It was registered as a
UNESCO World Heritage Site in 2012.
