Solid–Liquid Phase Equilibria in the Ternary MgCl₂–NiCl₂–H₂O System at 303–323 K

Abstract

For efficient nickel recovery from laterite nickel ore, an improved understanding of the solubility in ternary MgCl2–NiCl2–H2O systems is required. Herein, the stable phase equilibria in a ternary MgCl2–NiCl2–H2O system at 303, 313, and 323 K were studied using an isothermal dissolution equilibrium method. For this ternary system, the solubility and density were measured at different temperatures. The equilibrium solid phases were identified using X-ray diffraction, combined with the Schreinemakers’ method for wet residues. Based on the solubility data, the phase diagrams of the MgCl2–NiCl2–H2O system at 303, 313, and 323 K were plotted. At all investigated temperatures, the phase diagrams of this ternary system presented an invariant point, two isothermal dissolution curves, and three crystallization regions. Neither double salt nor solid solution was produced. The Mixed Solvent Electrolyte (MSE) model was applied to calculate the solubility for this ternary system. According to the comparison of phase diagram, the calculated data were in good agreement with the experimental values.