Oxygen solubility in copper bioleaching solutions

Abstract

Oxygen is usually the limiting reagent in bio-leaching processes. For this reason, aeration is a key point to take into account when designing such processes, and the oxygen saturation concentration is an important variable to know. Currently, there is a lack of data or models to accurately predict the concentration at which oxygen saturates under the operational conditions during copper bio-leaching. For this paper, oxygen solubility was measured in solutions containing the main electrolytes present in bio-leaching solutions: sulphuric acid, ferrous sulphate, ferric sulphate, and copper sulphate; measurements were performed throughout the range of concentration that is characteristic to each electrolyte. These solutions were obtained by microbiological oxidation of ferrous sulphate, and were exposed to air, at atmospheric pressure, until oxygen saturation occurred. Measurements were taken using a dissolved-oxygen electrode. From the results, the equation is obtained:Si=S°−12.698⋅10−pH−0.0555⋅Fe2+−0.0290⋅Fe3+−0.0265⋅Cu2+ that predicts oxygen solubility in copper bio-leaching liquors from the simple measurement of pH and Fe2 +, Fe3 +, and Cu2 + concentrations.