Process mineralogical study on leaching residue of zinc hydrometallurgy

Taking the zinc leaching residue of a factory in Yunnan as the research object, combined with XRF, XRD, SEM, phase analysis and other means, the chemical element composition of the leaching residue, the main existing forms of elements in the mineral, the particle size distribution and other process mineralogy parameters were studied in detail. The results show that most of the particles in the zinc leaching residue are smaller than 1.12 μm. The main valuable metals in the slag include zinc, germanium, lead and silver, with grades of 15.21%, 216.5 g/t, 6.48% and 0.018%, respectively. The main existing forms of zinc are zinc oxide, zinc sulfide and zinc ferrite, while Iron exists mainly in the form of iron oxide and zinc ferrite. Zinc ferrite is stable and insoluble in dilute acid, which is the main reason for the low zinc leaching rate in zinc leaching residue. At the same time, the increase of Fe³⁺ concentration leads to the increase of solution potential, which further inhibits the decomposition of zinc ferrite, so effectively reducing Fe³⁺ is the main method to improve the zinc leaching rate. Germanium in zinc leaching residue exists mainly in GeO₂ and germanate, which are easily to dissolve in acid. Zinc, germanium and silver have high recycling value and can be recycled comprehensively.