Recovery of Precious and Base Metals from Copper Mining Byproducts, Tailings, and Gangue Materials: A Comprehensive Review

Copper mining generates substantial quantities of byproducts including converter slags, tailings, and gangue materials containing valuable precious metals (Au, Ag) and base metals (Cu, Ni, Co, Fe). This comprehensive review synthesizes approximately 20 Scopus-indexed research articles examining extraction methodologies for Au, Ag, Cu, Fe, Co, Ni, and Si from metallurgical wastes. Three primary processing categories—pyrometallurgical, hydrometallurgical, and biohydrometallurgical approaches—are critically evaluated. Hydrometallurgical methods utilizing organic acids and citric acid achieve superior copper recovery rates (>99%), while low-temperature pyrometallurgical roasting demonstrates excellent performance for iron and nickel extraction (>96%). Thermodynamic analysis via Pourbaix diagrams reveals optimal oxidation-reduction potentials for spontaneous metal dissolution. Kinetic studies show activation energies ranging from 16.2 to 45.2 kJ/mol, indicating mass-transfer and diffusion-controlled mechanisms. Particle size (<45 μm), temperature (70°C optimal), and leaching agent concentration significantly influence extraction efficiency. This review establishes that integrated sequential processing—combining flotation, bioleaching, and acid leaching—achieves comprehensive metal recovery exceeding 80% for all target metals while minimizing environmental impact.