Ternary phase diagrams of CdSO4–NiSO4–H2O at 40 °C and 80 °C

The separation of cadmium and nickel from sulfate leach liquors of waste Ni–Cd batteries is investigated by using ternary phase diagrams. Experimental studies are carried out to obtain ternary phase diagrams of nickel sulfate, cadmium sulfate and water mixture at 40 °C and 80 °C. The eutectic point is determined to be composed of CdSO4.8/3H2O + NiSO4.6H2O and CdSO4.H2O + NiSO4.6H2O, for 40 °C and 80 °C, respectively, while two univariant curves and two crystallization regions are observed corresponding to CdSO4.8/3H2O and NiSO4.6H2O at 40 °C, CdSO4.H2O and NiSO4.6H2O at 80 °C. Both low (40 °C) and high (80 °C) temperature systems belong to a simple saturated type while no double salts or solid solutions exist.