Processing Zinc Hydrometallurgy, Purification Of The Residue - Cobalt And Nickel Slag Test

A systematic process of treating with Co-Ni residue from zinc hydrometallurgy has been developed. It based on the thermodynamic analyses of E-pH equilibrium diagrams and experiments. The process consists of the following major unit operations:(1) Leaching: Sulfuric acid was used as leaching agent. The optimum technology condition was: L/S ratio of 2.5:1, 80℃,80 min, sulfuric acid dosage of 1.4 times theoretic dosage. On this condition, the leaching rate of metals were: Zn>98%, Cd>99%,Co>99%,Ni>98.(2) Purification of cadmium: Zinc dust was used as reducing agent. The optimum technology condition was: the first stage, 50℃, 40 min, zinc dust dosage of 0.8 times theoretic dosage, the second stage, 45 ℃ , 40 min, zinc dust dosage of 0.6 times theoretic dosage. On this condition, the replacing rate of metals were: Cd>99%, Co<10%.Ni<15%.(3) Purification of cobalt: Na₂S₂O₈ was used as oxidant. the optimum technology condition was: 80℃ , 2h, Na₂S₂O₈ dosage of 8 times theoretic dosage, pH=5.0⁵.2. On this condition, cobalt content was 18.037% and nickel content was 0.093% in purification residue.(4) Purification of nickle: Zinc dust was used as reducing agent, Sb₂O₃ and CuSO₄ were used as activated agents. The optimum technology condition was: 80℃, 3h, Sb₂O₃50mg/L,CuSO₄50mg/l, zinc dust dosage of 40 times theoretic dosage, pH=4.0. On this condition, nickel content of residue was 4.916% .