Thermodynamic Model for Acidic Metal Sulfate from Solubility Data

Acidic metal sulfate solutions are generated in a large scale in the hydro-and pyrometallurgical industries. Acid mine drainage has long been a significant environmental problem in coal and metal mining. Acidic metal sulfate solutions are also produced in steel industry. The demand of recycling and reuse of materials has increased significantly especially in EU. Dumping a neutralized deposit is not an option any more. Thus, several techniques of recycling and reuse of sulfuric acid and/or metal sulfates from the side streams are needed. When developing alternative solutions a better understanding of the thermodynamic behavior of MnSO₄-H₂SO₄-H₂O system is needed. In this study a thermodynamic model of this system is developed using Gibbs energy minimisation, Pitzer model and CALPHAD method to yield thermodynamically consistent set of values for solubility of metal sulfate in a wide temperature and concentration range.