Thermodynamic model for acidic Fe(II) sulphate from solubility data

摘要

Acidic ferrous sulphate solutions are generated in a large scale in the hydro- and pyrometallurgical industries. They are also produced in the steel industry and titanium dioxide production. Acid mine drainage has long been a significant environmental problem in the coal and metal sulphide mining. The demand of recycling and reuse of materials has increased significantly especially in EU. Dumping and land filling a neutralised deposit is not an option anymore. Thus, efficient techniques of recycling and reuse of sulphuric acid and/or metal sulphates from the side streams are needed. When developing alternative solutions, a better understanding of the thermodynamic behaviour of the FeSO_4-H_2SO_4-H_2O system is needed. In the present study a thermodynamic model of this system has been developed, in order to yield a thermodynamically consistent set of values for the solubility of iron sulphate in a wide temperature and concentration range. The current model presents the experimental data available with a good accuracy and consistently up to 100 °C, and sulphuric acid concentrations up to 10 mol/kg. The model also predicts well the solubility measurements available in dilute sulphuric acid solutions at 160-220 °C.