Thermodynamic model for acidic Ni(II) sulfate from solubility data

• Published in: Calphad 2013-03, Vol.40, p.41-47
• Main Authors: Kobylin, P.M., Sippola, H., Taskinen, P.A.
• Format: Article
• Language: English
• Subjects: CALPHAD method; Computer simulation; Mathematical models; Nickel; Nickel sulfate; Nickel sulfate hydrates; Pitzer model; Reuse; Solubility; Sulfates; Sulfuric acid; Thermodynamic models
• ISSN: 0364-5916
• DOI: 10.1016/j.calphad.2012.10.002

Acidic nickel sulfate solutions are generated in a large scale in the hydro- and pyrometallurgical industries. They are also produced in many industrial processes from nickel refining to surface finishing of metals by electroplating. Acid mine drainage has long been a significant environmental problem in coal and metal mining. 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 NiSO4–H2SO4–H2O system is needed. In this study a thermodynamic model of this system has been developed in order to yield a thermodynamically consistent set of values for the solubility of nickel sulfate in a wide temperature and concentration range. The current model presents the experimental data available with a good accuracy and consistently up to 90°C, and sulfuric acid concentrations up to 10mol/kg. The model also predicts well the solubility measurements available in dilute up to 1.55mol/kg sulfuric acid solutions at 200–250°C. ► We modeled H2O–NiSO4–H2SO4 system using the Pitzer activity coefficient approach. ► Lots of solubility data were compiled from the literature. ► Our model presents experimental data available consistently up to 90°C.