Pyrometallurgy is a branch of extractive metallurgy. It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals.[1] Pyrometallurgical treatment may produce products able to be sold such as pure metals, or intermediate compounds or alloys, suitable as feed for further processing. Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like iron, copper, zinc, chromium, tin, and manganese.[2]
Pyrometallurgical processes are generally grouped into one or more of the following categories:[3]
calcining,
roasting,
smelting,
refining.
Most pyrometallurgical processes require energy input to sustain the temperature at which the process takes place. The energy is usually provided in the form of combustion or from electrical heat. When sufficient material is present in the feed to sustain the process temperature solely by exothermic reaction (i.e. without the addition of fuel or electrical heat), the process is said to be "autogenous". Processing of some sulfide ores exploit the exothermicity of their combustion
Calcination is thermal decomposition of a material. Examples include decomposition of hydrates such as ferric hydroxide to ferric oxide and water vapor, the decomposition of calcium carbonate to calcium oxide and carbon dioxide as well as iron carbonate to iron oxide:
Roasting consists of thermal gas–solid reactions, which can include oxidation, reduction, chlorination, sulfation, and pyrohydrolysis.
The most common example of roasting is the oxidation of metal sulfide ores. The metal sulfide is heated in the presence of air to a temperature that allows the oxygen in the air to react with the sulfide to form sulfur dioxide gas and solid metal oxide. The solid product from roasting is often called "calcine". In oxidizing roasting, if the temperature and gas conditions are such that the sulfide feed is completely oxidized, the process is known as "dead roasting". Sometimes, as in the case of pre-treating reverberatory or electric smelting furnace feed, the roasting process is performed with less than the required amount of oxygen to fully oxidize the feed. In this case, the process is called "partial roasting" because the sulfur is only partially removed. Finally, if the temperature and gas conditions are controlled such that the sulfides in the feed react to form metal sulfates instead of metal oxides, the process is known as "sulfation roasting". Sometimes, temperature and gas conditions can be maintained such that a mixed sulfide feed (for instance a feed containing both copper sulfide and iron sulfide) reacts such that one metal forms a sulfate and the other forms an oxide, the process is known as "selective roasting" or "selective sulfation".
Carbonate ores are also smelted with charcoal, but sometimes need to be calcined first.[citation needed]
Other materials may need to be added as flux, aiding the melting of the oxide ores and assisting in the formation of a slag, as the flux reacts with impurities, such as silicon compounds.[citation needed]
Smelting usually takes place at a temperature above the melting point of the metal, but processes vary considerably according to the ore involved and other matters.[citation needed]
Refining is the removal of impurities from materials by a thermal process. This covers a wide range of processes, involving different kinds of furnace or other plant.
The term "refining" can also refer to certain electrolytic processes. Accordingly, some kinds of pyrometallurgical refining are referred to as "fire refining".
^Brent Hiskey "Metallurgy, Survey" in Kirk-Othmer Encyclopedia of Chemical Technology, 2000, Wiley-VCH, Weinheim. doi:10.1002/0471238961.1921182208091911.a01.
^Adalbert Lossin "Copper" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a07_471.
^"Pyrometallurgy". Encyclopedia Britannica. Retrieved January 16, 2021.
External links
Hydrometallurgical processing of impurity streams generated during the pyrometallurgy of copper
January 07, 2023
pyrometallurgy, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, 2022, learn. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Pyrometallurgy news newspapers books scholar JSTOR May 2022 Learn how and when to remove this template message Pyrometallurgy is a branch of extractive metallurgy It consists of the thermal treatment of minerals and metallurgical ores and concentrates to bring about physical and chemical transformations in the materials to enable recovery of valuable metals 1 Pyrometallurgical treatment may produce products able to be sold such as pure metals or intermediate compounds or alloys suitable as feed for further processing Examples of elements extracted by pyrometallurgical processes include the oxides of less reactive elements like iron copper zinc chromium tin and manganese 2 Pyrometallurgical processes are generally grouped into one or more of the following categories 3 calcining roasting smelting refining Most pyrometallurgical processes require energy input to sustain the temperature at which the process takes place The energy is usually provided in the form of combustion or from electrical heat When sufficient material is present in the feed to sustain the process temperature solely by exothermic reaction i e without the addition of fuel or electrical heat the process is said to be autogenous Processing of some sulfide ores exploit the exothermicity of their combustion Contents 1 Calcination 2 Roasting 3 Smelting 4 Refining 5 See also 6 References 7 External linksCalcination EditMain article Calcination Calcination is thermal decomposition of a material Examples include decomposition of hydrates such as ferric hydroxide to ferric oxide and water vapor the decomposition of calcium carbonate to calcium oxide and carbon dioxide as well as iron carbonate to iron oxide CaCO3 CaO CO2Calcination processes are carried out in a variety of furnaces including shaft furnaces rotary kilns and fluidized bed reactors Roasting EditMain article Roasting metallurgy Roasting consists of thermal gas solid reactions which can include oxidation reduction chlorination sulfation and pyrohydrolysis The most common example of roasting is the oxidation of metal sulfide ores The metal sulfide is heated in the presence of air to a temperature that allows the oxygen in the air to react with the sulfide to form sulfur dioxide gas and solid metal oxide The solid product from roasting is often called calcine In oxidizing roasting if the temperature and gas conditions are such that the sulfide feed is completely oxidized the process is known as dead roasting Sometimes as in the case of pre treating reverberatory or electric smelting furnace feed the roasting process is performed with less than the required amount of oxygen to fully oxidize the feed In this case the process is called partial roasting because the sulfur is only partially removed Finally if the temperature and gas conditions are controlled such that the sulfides in the feed react to form metal sulfates instead of metal oxides the process is known as sulfation roasting Sometimes temperature and gas conditions can be maintained such that a mixed sulfide feed for instance a feed containing both copper sulfide and iron sulfide reacts such that one metal forms a sulfate and the other forms an oxide the process is known as selective roasting or selective sulfation Smelting EditMain article Smelting Smelting involves thermal reactions in which at least one product is a molten phase Metal oxides can then be smelted by heating with coke or charcoal forms of carbon a reducing agent that liberates the oxygen as carbon dioxide leaving a refined mineral Concern about the production of carbon dioxide is only a recent worry following the identification of the enhanced greenhouse effect Carbonate ores are also smelted with charcoal but sometimes need to be calcined first citation needed Other materials may need to be added as flux aiding the melting of the oxide ores and assisting in the formation of a slag as the flux reacts with impurities such as silicon compounds citation needed Smelting usually takes place at a temperature above the melting point of the metal but processes vary considerably according to the ore involved and other matters citation needed Refining EditMain article Refining metallurgy Refining is the removal of impurities from materials by a thermal process This covers a wide range of processes involving different kinds of furnace or other plant The term refining can also refer to certain electrolytic processes Accordingly some kinds of pyrometallurgical refining are referred to as fire refining See also EditBlast furnace Flash smelting Isasmelt furnace Reverberatory furnaceReferences Edit Brent Hiskey Metallurgy Survey in Kirk Othmer Encyclopedia of Chemical Technology 2000 Wiley VCH Weinheim doi 10 1002 0471238961 1921182208091911 a01 Adalbert Lossin Copper in Ullmann s Encyclopedia of Industrial Chemistry 2005 Wiley VCH Weinheim doi 10 1002 14356007 a07 471 Pyrometallurgy Encyclopedia Britannica Retrieved January 16 2021 External links EditU S Patent 5616168 Hydrometallurgical processing of impurity streams generated during the pyrometallurgy of copper Retrieved from https en wikipedia org w index php title Pyrometallurgy amp oldid 1118573198, wikipedia, wiki, book, books, library,
