China Nonferrous Metallurgy

Yunxi Wenshan Zinc Indium Smelting Co., Ltd adopted hematite Fe removal combined with SO2 reduction leaching for Zinc hydrometallurgy. Cu recovery had been relatively low in early production. To address the problem, the Company analyzed the behaviors and balance status of Cu in the production system, and found that low Cu leaching rate in SO₂ reduction leaching section was the major cause for the low Cu recovery in the system. By increasing the reaction temperature by 10-15℃, leaching time by 30-45min and initial acidity to 20-30g/L in SO₂ reduction leaching section, Cu leaching rate can be increased by about 11%; in addition, by controlling the volume of SO₂ input at an appropriate level, generally 1.2 times the content of Fe³⁺ in the solution, Cu precipitation caused by excessive SO₂ input can be avoided, and the loss of Cu into the leaching slag can be reduced. With the above measures, the final Cu recovery rate of the system is improved by about 10% up to 93%.