| Magnesium chloride is difficult to remove from hydrometallurgical nickel laterite processes economically. However, magnesium precipitation as MgSO4•H2O from a concentrated chloride solution with simultaneous regeneration of HCl offers advantages over conventional pyrohydrolysis. In this work, OLI System's Mixed Solvent Electrolyte model was updated and used to predict the solubility of MgSO4•H 2O in mixed sulphate-chloride solutions. Predictions reproduced experimental trends at temperatures between 65 and 105°C, HCl concentrations up to 2.3 mol·kg-1, FeCl3 concentrations of 1.0 mol·kg-1, and MgCl2 concentrations up to 4.8 mol·kg-1. Model results matched experimental results with an average absolute relative deviation of 10.8% and an average absolute deviation of +/- 0.09 mol·kg-1. The validated model was used to determine magnesium sulphate hydrate phase stability regions and MgSO4•H2O solubility in various chloride solutions. Model results can be used to optimize the Anglo Research Nickel Process flowsheet with respect to acid consumption and magnesium impurity control. |
