China Nonferrous Metallurgy

In China, the zinc hydrometallurgical plants usually reuse the cell zinc anode slime and plate zinc anode slime directly in the leaching system, however, during this process, it is hard to control the Mn²⁺ concentration in zinc electrolyte. In this paper, it is creatively put forward that when the Mn²⁺ concentration in zinc electrolyte is less than 4 g/L and the plate zinc anode slime is proportioned with zinc concentrate, the MnO₂ is reduced under high temperature to low valent Mn by roasting, so as to lower the oxidation efficiency of the anode slime to increase the concentration of Mn²⁺ in the zinc electrolyte. Parameters for operation are follows: mass proportioning ratio of anode slime and zinc concentrate about 1∶100, temperature of fluidized bed 910-950 ℃, hearth temperature 300-330 ℃. When the Mn²⁺ concentration of zinc electrolyte is not less than 4 g/L, the plate zinc anode slime is subject to ball mill grinding and slurrying before being returned to the leaching system with the particle size being controlled around 0.074 mm, the oxidation efficiency can be more than 91%. The reuse modes are taken under different conditions, which can not only achieve the comprehensive recycling of valuable metals, but also be conducive to the timely adjustment of the Mn²⁺ concentration in the zinc electrolyte to lay a solid foundation for the stable running of production.