Germanium recovery by co-precipitation of germanium and iron in conventional zinc metallurgy

A considerable fraction of germanium is produced as a by-product in zinc metallurgy. In the conventional roast-leach-electrowin (RLE) process, most of the germanium is incorporated into the neutral leaching residue, which is the main source for germanium recovery. As the largest germanium supplier worldwide, Yunnan Chihong Zinc & Germanium Co., Ltd (Yunnan, China), recover germanium shown in Figure 1. In the process, a great deal of chemical material such as tannic acid is consumed and the germanium concentrate obtained is of very low grade. The reason why a great deal of tannic acid is needed to precipitate germanium is that many types of metal ions can form complexes with it1-3. O.S. Pokrovsky et al. found germanium coprecipitate with iron hydroxide4. Based on this understanding, a modified process was presented, as in Figure 2. In this paper, the variables influencing the germanium precipitation were investigated