Study on leaching behaviour of germanium and iron in zinc oxide dust from lead zinc smelting

Abstract

ABSTRACT Zinc oxide dust from lead zinc smelting is an important raw material for germanium recovery. This article researched the behaviour of germanium and iron in zinc oxide dust leaching in response to the problem of low germanium leaching efficiency. For this purpose, the germanium phase distributions were confirmed, the effects of sulphuric acid concentration, liquid–solid ratio, leaching temperature, and leaching time were determined. According to the findings, germanium exists primarily in the form of soluble germanium oxide and germanates. In addition, the germanium leaching efficiency is most affected by the leaching time, because the leaching iron will be oxidised and create Fe4Ge3O12 precipitation with the leaching germanium if the leaching time is too long, resulting in the decline of germanium leaching efficiency. The leaching efficiency of zinc and germanium can reach 89.05% and 84.32%, respectively, when the sulphuric acid concentration is 150 g/L, the liquid–solid ratio is 5:1, the leaching temperature is 85°C, and the leaching time is 30 min, which is 0.44% and 7.21% higher than that under unoptimised conditions. Furthermore, through sodium sulphite-assisted leaching, the leaching efficiency of germanium is further increased to 89.48%, indicating that reductant-assisted leaching is a direction worthy of study.