ASSESSING METAL RECOVERY OPPORTUNITIES THROUGH BIOLEACHING FROM PAST METALLURGICAL SITES AND WASTE DEPOSITS: UK CASE STUDY

Abstract

Recovery of metals from former industrial areas (also called brownfields) and closed landfill sites, are critical for future sustainable development and reducing the environmental risks they posed. In this study, the feasibility of using bioleaching for resource recovery of raw and secondary raw materials from a former metallurgical site and deposit (PMSD) located in the UK was investigated. Determination of the physicochemical parameters (conductivity, pH, moisture and ash content) that can affect bioleaching performance along with metal content analysis were carried out. Field measurement were also carried out using a portable X-ray fluorescence (pXRF) spectrometer as a rapid measurement tool and compared with the induced coupled mass spectrometry (ICP-MS) results. Fe (469,700 mg/kg), Ca (25,900 mg/kg) and Zn (14,600 mg/kg) were the most dominant elements present in the samples followed by Mn (8,600 mg/kg), Si (3,000 mg/kg) and Pb (2,400 mg/kg). The pXRF results demonstrated minimal variance (<10%) from the ICP-MS results. The preliminary assessment of bioleaching using Acidithiobacillus ferrooxidans at 5% pulp density with 22 g/L energy source and 10% (v/v) inoculum at pH 1.5 showed that 100% of Ti and Cu, 32% of Zn and 24% of Mn was recovered from the sample material, highlighting opportunities for the recovery of such metals through bioleaching processes.