Study on intensive leaching of indium and germanium from complex materials containing indium and germanium in zinc smelting

In order to destroy the mineral structure of the variety of indium germanium compounds, which are difficult to dissolve, and maximize the efficient leaching of indium germanium strategic metals, a two-stage countercurrent enhanced leaching process combining atmospheric pressure leaching and oxygen pressure leaching methods was proposed to realize the destruction of mineral structures such as oxides, sulfides, germanates, ferrites, silicates, and the maximum leaching of valuable components such as indium and germanium. The results show that the leaching of indium and germanium in easily soluble compounds such as oxides and germanates can be destroyed under the atmospheric pressure leaching conditions of 80 ℃, 180 g/L sulfuric acid concentration, 3 h, 4 mL/g liquid-solid ratio and 500 r/min stirring speed. The refractory metal sulfides and germanates in the first stage leaching residue are more, including indium 1 993.3 g/t, germanium 623.5 g/t, copper 23.65%, and indium, germanium and copper are still high. Further, the oxygen pressure leaching method is adopted to realize the deep leaching of indium and germanium in metal sulfide and insoluble germanate. At the conditions of temperature 120 ℃, oxygen partial pressure 0.25 MPa, sulfuric acid concentration 180 g/L, time 3 h, and liquid-solid ratio 6 mL/g, the mass fractions of indium, germanium, zinc, and copper in the primary leaching slag decrease to 74.2 g/t, 574.8 g/t, 6.15%, and 1.76%, respectively, and the slag rate decreased to 3.5%. Through two-stage counter current enhanced leaching, the total leaching rates of indium, germanium, copper and zinc reach 99.41%, 95.11%, 99.98% and 99.11%, respectively, realizing the efficient leaching of indium, germanium and other metals. © 2023 Central South University of Technology. All rights reserved.