Recovery of Indium and Germanium from Residues of Zinc Plants

Two optional process concepts for recovering indium and germanium from the zinc process residues are presented: i) RIGAT process where two-lead bearing alloys from Imperial Smelting Process are treated, and ii) Jarogain process where side-streams (e.g. jarosite and gothite) from RLE (Roasting-Leaching-Electrowinning) are processed. A techno-economic assessment was performed for both processes. Additionally, a literature review of the indium, germanium and tin markets was conducted, with the main purpose to provide a background for the metals which market prices the profitability of an investment in the process relies on. The proposed concepts were simulated to provide mass and energy balances for the processes. The mass distribution of elements obtained from pilot-scale experiments performed by the research institutes IMN and VTT, was used as input data in the process simulation. Using the mass balances obtained from the simulation, the main equipment required for the processes were dimensioned. The capital cost, the operational costs and the revenue for the process were estimated and using these, the net present value of the investment was calculated for a period of 20 years. A sensitivity analysis was conducted by varying the estimation of metal prices and selected costs and studying its impact on the net present value. Both of the proposed processes are interesting options for recovering indium and germanium from the secondary sources.