Starting from prepared secondary raw materials, i.e. those ready to be fed into a melting furnace and identified in terms of analysis and yield, a charge is built up by assembling complementary raw materials to directly obtain the alloy to be produced.
The role of melting furnaces is to melt the metal, separate the metal from the oxide, title the alloy and metallurgically treat the metal. These operations are carried out at the lowest possible cost, while limiting metal loss through oxidation and entrainment in dross.
As the raw materials are very different, all types of furnaces used in aluminum metallurgy are used. However, special reverberatory furnaces and rotary furnaces play a very important role, and their technologies are constantly being developed. In particular, we are witnessing the increasingly complex construction of large reverberatory furnaces with multiple functions, and the evolution of rotary furnaces towards solutions with lower operating costs.
The use of salt to slag oxides is a typical recycling technique. The necessary metal treatment, to obtain a quality competitive with that of primary metal, is also developed (elimination of gases, impurities, undesirable components).
Shaping of finished products examines the processes in use: ingot casting, continuous casting, ladle casting for road transport, casting of shaped products.
Note :
The complete study of the subject includes the articles :
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Aluminium recovery and recycling. Strategy;
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Aluminium recovery and recycling. Raw materials ;
— [M 2 347] Aluminium recovery and recycling. Smelting and shaping (this article);
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Aluminium recovery and recycling.