smelting, in metallurgy, any process of melting or fusion, especially to extract a metal from its ore. Smelting processes vary in detail depending on the nature of the ore and the metal involved, but they are typified in the use of the blast furnace.

Process by which a metal is obtained from its ore, either as the element or as a simple compound, usually by heating beyond the melting point, ordinarily in the presence of reducing agents such as coke or oxidizing agents such as air (see oxidation-reduction). A metal whose ore is an oxygen compound (e.g., iron, zinc, or lead oxide) is heated (reduction smelting) in a blast furnace to a high temperature; the oxide combines with the carbon in the coke, escaping as carbon monoxide or carbon dioxide. Other impurities are removed by adding flux, with which they combine to form slag. If the ore is a sulfide mineral (e.g., copper, nickel, lead, or cobalt), air or oxygen is blasted through (matte smelting) to oxidize the sulfide to sulfur dioxide and any iron to oxide slag, leaving the metal. Seealso metallurgy; mineral processing.

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