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Tham khảo tài liệu 'environmental management part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 7 Management of the Salt Cake Generated at Secondary Aluminium Melting Plants A. Gil and S.A. Korili Department of Applied Chemistry Building Los Acebos Public University of Navarra Campus of Arrosadia E-31006 Pamplona Spain 1. Introduction Aluminium is due to its properties the second most used metal after iron. It is used in a wide number of products and sectors either alone or as an alloy Kammer 1999 . The aluminium production is based on an electrolytic process the Hall-Hérolt process in which metallic aluminium is obtained from the reduction of aluminium oxide. The metal obtained with this process is called primary aluminium. Aluminium oxide is extracted from natural bauxite in the Bayer process. Since the development of the large-scale production of aluminium oxide aluminium production has expanded enormously http www.worldaluminium. org . It is worth mentioning the important growth in aluminium production in China in recent years over 12 964 tones of aluminium were produced in 2009 http www.world-aluminium.org . The recycling of aluminium is very important since the residues of this metal can be reused without any loss of quality. The metal obtained in this way is called secondary aluminium. The aluminium destined for recycling can be divided into two categories preconsumer byproducts from the production of primary aluminium and scrap associated with postconsumer aluminium. By means of melting in some cases with prior processing the byproducts and scrap are transformed into ingots half balls and plates for subsequent commercialization. Comparing primary and secondary aluminium production the secondary process causes less environmental impact than the primary process Drossel et al 2003 . It consumes 17 times less energy it emits 17 times less pollution to the atmosphere it generates between five and nine times less solid wastes and it consumes 35 times less water. For both processes the greatest problems derive from the generation and management of wastes. .
