Separation and recovery of Ni from copper electrolyte by crystallization of nickel ammonium sulfate double salt
(1. School of Metallurgy and Environment, Central South University, Changsha 410083, China;
2. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
2. School of Minerals Processing and Bioengineering, Central South University, Changsha 410083, China)
Abstract: The separation and recovery of Ni from the copper electrolyte by crystallization of nickel ammonium sulfate double salt were studied. It is found that the solubility of copper sulfate at the same temperature is less than that of nickel sulfate, while the solubility of copper ammonium sulfate is greater than that of nickel ammonium sulfate. So, by adding (NH4)2SO4, the Ni can be selectively crystallized from the copper electrolyte. By adding (NH4)2SO4 at the molar ratio of (NH4)2SO4/NiSO4 ≤0.8, and crystallizing at -15 °C for 10 h, the Ni in the copper electrolyte can be crystallized in the form of Ni(NH4)2(SO4)2×6H2O. The qualified product of NiSO4×6H2O can be obtained by pyrolyzing the crystals, dissolving the pyrolysis product in water, and then concentrating the dissolved solution for crystallization. The method of double salt crystallization is a clean, environmentally-friendly, cost-effective and efficient method for separating and recovering nickel from copper electrolyte.
Key words: copper electrolyte; nickel; crystallization; nickel ammonium sulfate