Optimization experiment and production practice of leaching process in zinc hydrometallurgy

Neutral leaching of zinc calcine is one of the key steps in the wet zinc smelting process. In this paper, the effects of initial acidity, smelting temperature, leaching time and grain size of calcine on the neutral leaching of zinc calcining were investigated by single factor experiment and orthogonal test. The results show that the optimum process conditions are: initial acidity of 50 g/L, smelting temperature of 65 ℃, reaction time of 60 min, calcining grain size ≤96 μm; all four factors have a significant effect on the total zinc in the leaching residue, and the influence from big to small are as follow: calcining grain size > initial acidity > reaction temperature >Reaction time. Combined with the results, a series of technical transformations were carried out: adding the winnowing ball milling device in the zinc concentrate roasting and discharging system, reducing the particle size of the zinc calcining to ≤120 μm; two 100 m³ stirred reaction tank were added in series behind the neutral leaching double-boiling leaching tank, and reengineered the process at the same time. By Comparing the production practice before and after the transformation, it was found that the total zinc in the leaching residue decreased from 28%~35% to 22%~25%, and the quality of the supernatant was stable.