| Nickeliferous laterite pressure leachates are multicomponent metal sulfate solutions containing excess free H2SO4 in amounts dependent on the ore and consequently on the solution composition. These solutions are encountered in the Pressure Acid Leach Process for nickel and cobalt recovery from lateritic ore deposits. Typically the metals which have the greatest influence on the leach solution acidity are iron, aluminum, and magnesium. These also have a significant impact on scale formation on the internal surfaces of the autoclave. Solubility data have been extensively used to identify the chemistry and thermodynamics of aqueous solutions. However, very limited data exist for metal solubilities in sulfuric acid media at the temperatures of relevance to laterite pressure leach solutions. In this work, the solubilities of iron, aluminum, magnesium and nickel in 10--70 g/L free sulfuric acid in the temperature range of 230° to 270°C were measured. With the aid of the OLI software, new thermodynamic data were estimated that permit the calculation of the activity of hydrogen ions. |
