HUMAN HEALTH RISK ASSESSMENT FOR ALUMINIUM, ALUMINIUM OXIDE ...
casting of aluminium into ingots. Aluminium is first extracted at 140 250 C with caustic soda from the bauxite, precipitated as aluminium hydroxide after the removal of iron and silicon impurities, and subsequently converted to aluminium oxide in a calcination process. These steps encompass the Bayer process Sleppy, 1992 .