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Catégorie
Procédé industriel
Résumé
Industrial processes are procedures involving chemical, physical, electrical, or mechanical steps to aid in the manufacturing of an item or items, usually carried out on a very large scale. Industrial processes are the key components of heavy industry.
Chemical process
Certain chemical process yield important basic materials for society, e.g., (cement, steel, aluminum, and fertilizer). However, these chemical reactions contribute to climate change by emitting carbon dioxide, a greenhouse gas, through chemical reactions, as well as through the combustion of fossil fuels to generate the high temperatures needed to reach the activation energies of the chemical reactions.
Calcination – Limestone, which is largely composed of fossilized calcium carbonate (CaCO3), breaks down at high temperatures into useable calcium oxide (CaO) and carbon dioxide gas (), which gets released as a by-product. This chemical reaction, called calcination, figures most prominently in creating cement (the paste within concrete). The reaction is also important in providing calcium oxide to act as a chemical flux (removal of impurities) within a blast furnace.
Smelting – Inside a blast furnace, carbon monoxide (CO) is released by combusting coke (a high-carbon derivative of coal) and removes the undesired oxygen (O) within ores. is released as a by-product, carrying away the oxygen and leaving behind the desired pure metal. Most prominently, iron smelting is how steel (largely iron with small amounts of carbon) is created from mined iron ore and coal.
Hall–Héroult process – Aluminum oxide () is smelted with coke (C) in a high-temperature electrolysis reaction, yielding the desired pure aluminum (Al) and a mixture of CO and .
Haber process – Atmospheric nitrogen (N2) is separated, yielding ammonia (NH3), which is used to make all synthetic fertilizer. The Haber process uses a fossil carbon source, generally natural gas, to provide the CO for the water–gas shift reaction, yielding hydrogen (H2) and releasing .
Source officielle
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