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A multiple hearth furnace also known as a vertical calciner, is used for continuous preparation and calcining of materials.
The multiple hearth furnaces consist of several circular hearths or kilns superimposed on each other. Material is fed from the top and is moved by the action of rotating "rabble arms", and the revolving mechanical rabbles attached to the arms move over the surface of each hearth to continuously shift the ore. The arms are attached to a rotating central shaft that passes through the center of the roaster. As the material is moved, the ore that is charged at the top hearth gradually moves downward as it passes through windows in the floor of each hearth or through alternate passages around the shaft and the periphery until it finally emerges at the bottom.
The oxidizing gases flow upward, i.e., counter-current to the descending charge. In a well-insulated roaster, external heating is unnecessary except when the charge is highly moist. The hearth at the top of the roaster dries and heats the charge. Ignition and oxidation of the charge occur lower down. [1]
The hearths may be individually heated and the number, temperature, rotation rate, and size of each hearth determine the residence time and conditions for the calcining powder in order to achieve the desired final properties.
The individual hearths are lined with refractory brick, and the rabble arms are typically a force-cooled metal alloy. The entire structure is enclosed in a cylindrical brick-lined steel shell.
Wrought iron is an iron alloy with a very low carbon content in contrast to that of cast iron. It is a semi-fused mass of iron with fibrous slag inclusions, which gives it a "grain" resembling wood that is visible when it is etched or bent to the point of failure. Wrought iron is tough, malleable, ductile, corrosion resistant, and easily welded.
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, sand or rock dust.
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.
Copper extraction refers to the methods used to obtain copper from its ores. The conversion of copper consists of a series of physical and electrochemical processes. Methods have evolved and vary with country depending on the ore source, local environmental regulations, and other factors.
Open-hearth furnaces are one of several kinds of furnace in which excess carbon and other impurities are burnt out of pig iron to produce steel. Since steel is difficult to manufacture owing to its high melting point, normal fuels and furnaces were insufficient and the open-hearth furnace was developed to overcome this difficulty. Compared to Bessemer steel, which it displaced, its main advantages were that it did not expose the steel to excessive nitrogen, was easier to control, and permitted the melting and refining of large amounts of scrap iron and steel.
Calcination refers to heating a solid to high temperatures in absence of air or oxygen, generally for the purpose of removing impurities or volatile substances. However, calcination is also used to mean a thermal treatment process in the absence or limited supply of air or oxygen applied to ores and other solid materials to bring about a thermal decomposition. The root of the word calcination refers to its most prominent use, which is to remove carbon from limestone through combustion to yield calcium oxide (quicklime). This calcination reaction is CaCO3(s) → CaO(s) + CO2(g). Calcium oxide is a crucial ingredient in modern cement, and is also used as a chemical flux in smelting. Industrial calcination generally emits carbon dioxide (CO
2), making it a major contributor to climate change.
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Puddling is a step in the manufacture of high-grade iron in a crucible or furnace. It was invented in Great Britain during the Industrial Revolution. The molten pig iron was stirred in a reverberatory furnace, in an oxidizing environment, resulting in wrought iron. It was one of the most important processes of making the first appreciable volumes of valuable and useful bar iron without the use of charcoal. Eventually, the furnace would be used to make small quantities of specialty steels.
Moira Furnace is a nineteenth-century iron-making blast furnace located in Moira, Leicestershire, on the banks of the Ashby-de-la-Zouch Canal. Built by the Earl of Moira in 1804, the building has been preserved by North West Leicestershire District Council as a museum featuring lime kilns and craft workshops.
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The Fernald Feed Materials Production Center is a Superfund site located within Crosby Township in Hamilton County, Ohio, as well as Ross Township in Butler County, Ohio. It was a uranium processing facility located near the rural town of New Baltimore, about 20 miles (32 km) northwest of Cincinnati, which fabricated uranium fuel cores for the U.S. nuclear weapons production complex from 1951 to 1989. During that time, the plant produced 170,000 metric tons uranium (MTU) of metal products and 35,000 MTU of intermediate compounds, such as uranium trioxide and uranium tetrafluoride.
Mount Isa Mines Limited ("MIM") operates the Mount Isa copper, lead, zinc and silver mines near Mount Isa, Queensland, Australia as part of the Glencore group of companies. For a brief period in 1980, MIM was Australia's largest company. It has pioneered several significant mining industry innovations, including the Isa Process copper refining technology, the Isasmelt smelting technology, and the IsaMill fine grinding technology, and it also commercialized the Jameson Cell column flotation technology.
Zinc smelting is the process of converting zinc concentrates into pure zinc. Zinc smelting has historically been more difficult than the smelting of other metals, e.g. iron, because in contrast, zinc has a low boiling point. At temperatures typically used for smelting metals, zinc is a gas that will escape from a furnace with the flue gas and be lost, unless specific measures are taken to prevent it.
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Mining works on Towers Hill is a heritage-listed group of mining ruins at Towers Hill, Charters Towers, Charters Towers Region, Queensland, Australia. They were built from 1872 to 1940s. They are individually known as Pyrites Works, Rainbow Battery, and Towers Chlorination Works. They were added to the Queensland Heritage Register on 29 April 2003.
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