China Nonferrous Metallurgy

Zinc electrolysis anode slime contains a large amount of manganese. At present, the commonly treatment method in enterprises is to return to the leaching process for reuse, but this method will lead to a high concentration of manganese ions in the system solution, which will affect electrolysis. In this study, the reduction leaching behavior of manganese in zinc electrolytic anode slime in SO₂-H₂O system was investigated by using the reduction characteristics of SO₂, and the effects of process conditions on the leaching rate of manganese and the dissolution rate of potassium and calcium were investigated. The results show that under the conditions of initial acidity of 0g/L, liquid-solid ratio of 4.0, SO₂ dosage of 3.5mol, reaction temperature of 40℃, reaction time of 1.5h and stirring speed of 400r/min, the leaching rate of Mn reaches 99.7%, and the dissolution rates of K and Ca are 89.7% and 28.6%, respectively. The impurities such as K and Ca in the manganese-rich solution can be removed by chemical precipitation method and used to prepare industrial grade manganese sulfate. The main chemical components of the leaching residue are Pb 37.79%, Ag 1480g/t, Sr 12.49% and Si 6.07%, which exist in the forms of PbSO₄, SrSO₄ and SiO₂, respectively. Pb, Ag and Sr in the volatile residue can be reduced to dust by pyrometallurgical process, and then further separated. The method avoids the problem that the concentration of manganese ions in the electrolytic system is too high, and realizes the enrichment of valuable metal elements lead, silver and strontium in the leaching residue. The enrichment factor is about 9, which improves the added value of the leaching residue.