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单词 blast furnace
释义
blast furnace

Chemistry
  • A furnace for smelting iron ores, such as haematite (Fe2O3) or magnetite (Fe3O4), to make pig iron. The furnace is a tall refractory-lined cylindrical structure that is charged at the top with the dressed ore (see beneficiation), coke, and a flux, usually limestone. The conversion of the iron oxides to metallic iron is a reduction process in which carbon monoxide and hydrogen are the reducing agents. The overall reaction can be summarized thus:

    Fe3O4+2CO+2H23Fe+2CO2+2H2O

    The CO is obtained within the furnace by blasting the coke with hot air from a ring of tuyeres about two-thirds of the way down the furnace. The reaction producing the CO is:

    2C+O22CO

    In most blast furnaces hydrocarbons (oil, gas, tar, etc.) are added to the blast to provide a source of hydrogen. In the modern direct-reduction process the CO and H2 may be produced separately so that the reduction process can proceed at a lower temperature. The pig iron produced by a blast furnace contains about 4% carbon and further refining is usually required to produce steel or cast iron.


Chemical Engineering
  • A smelting furnace used for the continuous production of molten iron from iron ore, from which steel is made. It consists of a steel tower lined with refractory brick into the top of which iron ore, coke, and limestone are charged. Compressed hot air is blasted into the bottom. The chemical reaction of the oxygen in the air and the coke produces carbon monoxide. This then reacts with the iron ore to produce carbon dioxide and iron. The carbon dioxide then reacts with more carbon to produce more carbon monoxide. The limestone combines with the coke ash to form liquid slag, which absorbs any sulphur in the iron, collects at the bottom of the tower, and floats on the surface of the molten iron. Both the molten iron and slag are periodically and separately tapped off. The hot gases are used as fuel for heating the incoming air. The cast or pig iron is used to produce steel in the Bessemer process.


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