The Iron Precipitate from Primary Zinc Production: A Potential Future Source for Indium and Silver

Indium as a so-called hitchhiker metal is extracted almost entirely in course of the primary zinc production. Thus, a strong dependence on the output of the corresponding base metal is given. Taking the annual growth rate of approximately 3% in zinc production and the one of indium, respectively, around 15% into account, it is obvious that a shortage in indium is faced. Because of the relative new application area of indium in high-tech products, a great potential of dumped metal is present in the residues of the past production. Therefore, the present paper describes the characterization and the possible treatment of such an iron precipitation residue, including the thermodynamic background for a pyrometallurgical extraction of indium and silver.