Solubility of Pb(II) and Ni(II) in Mixed Sulfate-Chloride Solutions with the Mixed Solvent Electrolyte Model

The existence of Pb(II) in nickel sulfide mineral feedstocks imposes a burden to nickel hydrometallurgy. To devise effective Pb(II) control strategies, the solubility of Pb(II) in mixed sulfate-chloride solutions needs to be known in the nickel industry. In this work, the solubility of Pb(II) and Ni(II) in a Pb-Na-Ni-SO4-Cl-H2O system was modeled with the mixed solvent electrolyte (MSE) model through commercial software OLI systems. The model parameters, including equilibrium constants of solids (PbCl2, PbSO4, NiSO4.nH2O, and NiCl2.nH2O) and MSE ion interaction parameters, were regressed from various types of equilibrium and thermophysical data such as solubility, heat capacity, vapor pressure, and mean activity coefficient. The obtained model parameters are capable of accurately representing experimental data in binary (PbCl2-H2O, PbSO4-H2O, NiSO4-H2O, and NiCl2-H2O) and ternary (PbCl2-HCl/NaCl-H2O, NiSO4-Na2SO4-H2O, and NiCl2-HCl-H2O) systems and give excellent predictions in multicomponent systems (NiCl2-NaCl-H2O, PbSO4 -H2SO4-H2O, and PbSO4-H2SO4-HCl-H2O).