Acid bioleaching of solid waste materials from copper, steel and recycling industries

The aim of this work was to evaluate the feasibility of bioleaching for the solubilisation of metals from solid waste streams and by-products of copper, steel and recycling industries. The leaching experiments were carried out in shake flasks in mineral salts media inoculated with iron and sulphur oxidising acidophiles at 25 °C. The experiments tested the effects of the inoculum, pH, supplemental ferrous iron and sulphur, sodium chloride, and the type of waste material. Solubilisation of metals was mainly achieved through acid attack due to the formation of sulphuric acid by sulphur oxidising bacteria. Addition of ferrous iron and chloride ions did not enhance metal solubilisation.