Process for indium recovery from extremely diluted solutions

R. Vostal, U. Šingliar, M. Bertau, P. Fröhlich

The growing demand for indium as a high-tech metal requires the development of new winning strategies. Keeping this in mind, a novel approach of in-situ bioleaching is to be applied at the Freiberg mine “Reiche Zeche” with the goal of mobilising indium contained in the ore of the mine and its transfer to a bioleaching solution generated by the process of bioleaching. A continuous process for the recovery of indium oxide from such indium solutions of very low concentrations was developed and thoroughly studied. It was possible to obtain indium oxide with a purity of more than 99 % with minimal chemical consumption from a synthetic solution, which contained only 10 mg/dm3 indium and high amounts of iron and zinc impurities (10 g/dm3 each) by combining two solvent extraction circuits with two different reagents coupled with diffusion dialysis and selective precipitation.