Recovery of valuable materials from aluminium salt cakes

Salt cakes, which are nominally waste products derived from aluminium dross melting furnaces, are complex mixtures of some 20 different compounds made up of many different elements. Normally they are regarded as waste products and they are disposed of in toxic waste dumps. However, it is shown here that some components are readily recoverable as high-grade products for recycling or sale and that the residues thus generated can be non-toxic. Recoverable components include metallic aluminium, salt (halite (NaCl) and sylvite (KCl)), alumina-containing compounds, and possibly hydrogen gas.