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The Hall–Héroult process is the major industrial process for smelting aluminium. It involves dissolving aluminium oxide (alumina) (obtained most often from bauxite , aluminium 's chief ore, through the Bayer process ) in molten cryolite and electrolyzing the molten salt bath, typically in a purpose-built cell.
The process produces a quantity of fluoride waste: perfluorocarbons and hydrogen fluoride as gases, and sodium and aluminium fluorides and unused cryolite as particulates. This can be as small as 0.5 kg per tonne of aluminium in the best plants in 2007, up to 4 kg per tonne of aluminium in older designs in 1974.
The physical structure of a crystalline material is largely determined by the method of cooling and precipitation of the molten metal. During the pouring process, metal in contact with the ingot walls rapidly cools and forms either a columnar structure or possibly a "chill zone" of equiaxed dendrites, depending upon the liquid being cooled and ...
Direct Chill casting is a method for the fabrication of cylindrical or rectangular solid ingots from non-ferrous metals, especially Aluminum, Copper, Magnesium and their alloys. The original ingots are usually further processed by other methods (rolling, forging, etc.). More than half of global aluminum production uses the Direct Chill casting ...
A billet is a length of metal that has a round or square cross-section, with an area less than 36 in 2 (230 cm 2). Billets are created directly via continuous casting or extrusion or indirectly via hot rolling an ingot or bloom. [1] [2] [4] Billets are further processed via profile rolling and drawing. Final products include bar stock and wire. [3]
Vacuum arc remelting (VAR) is a secondary melting process for production of metal ingots with elevated chemical and mechanical homogeneity for highly demanding applications. [1] The VAR process has revolutionized the specialty traditional metallurgical techniques industry, and has made possible tightly controlled materials used in biomedical ...
Smelting is a process of applying heat and a chemical reducing agent to an ore to extract a desired base metal product. [1] It is a form of extractive metallurgy that is used to obtain many metals such as iron , copper , silver , tin , lead and zinc .
This is a list of primary aluminium smelters in the world. Primary production is the process by which alumina is smelted to pure aluminum. [1] Secondary production is the process of recycling aluminum scrap into aluminum that can be used again. [2] Capacity here refers to metric tonnes of output aluminum. The list is incomplete and missing some ...