Properties of electrolyte solutions relevant to high concentration chloride leaching I. Mixed aqueous solutions of hydrochloric acid and magnesium chloride

A computer code based on a Pitzer model has been developed for the comprehensive prediction of the thermodynamic properties of MgCl2–HCl aqueous solutions over a wide range of conditions from 25 to 120 °C and from 0–350 g L− 1 chloride. This code was applied to the calculation of (i) water activities and mean ionic activity coefficients for mixed aqueous solutions of hydrochloric acid and magnesium chloride over a wide range of concentrations and to 100 °C, (ii) solubilities of MgCl2·6H2O in MgCl2–HCl solutions to 80 °C, (iii) partial pressures of HCl(g) and H2O(g) over MgCl2–HCl aqueous solutions at various temperatures and (iv) partial pressures of HCl(g) at the normal boiling point of these mixed electrolyte solutions. The model predictions are in excellent agreement with available experimental data and confirm evidence from the literature that MgCl2(aq) and HCl(aq) mix almost ideally at constant water activity.