FG KALEMBWE TSHIHUISA

Industrial copper tailings from the Kingamyambo site constitute a large-tonnage, metal-bearing residue whose inadequate valorization limits resource efficiency and increases environmental liabilities. This study aimed to quantify the effectiveness of citric acid as an alternative lixiviant for recovering copper from Kingamyambo tailings, and to determine operating conditions that maximize leaching yield while minimizing reagent consumption. Laboratory leaching tests were conducted on homogenized tailings using aqueous citric acid solutions at controlled pulp density, temperature, and agitation speed. Systematic variations of acid concentration (0.1–1.0 mol·L⁻¹), leaching time (0.5–8 h), and particle size fractions were performed, and dissolved copper concentrations were measured by volumetric analysis to calculate extraction yields and apparent leaching rates. The process was evaluated in terms of copper recovery, kinetic behavior, and specific acid consumption per kilogram of copper produced. Under optimized conditions, copper recovery increased from less than 20% at low acid concentration to more than 70–80% at 0.5–1.0 mol·L⁻¹ citric acid, while the leaching time required to reach 60% recovery decreased by approximately 40–50% compared with non-optimized tests. Specific citric acid consumption was reduced by about 20–30% by adjusting pulp density and particle size. These findings indicate that citric acid leaching can provide technically viable copper recovery from Kingamyambo tailings with significant improvements in extraction kinetics and reagent efficiency, supporting the potential industrial application of an environmentally benign lixiviant for tailings reprocessing.