Comprehensive physicochemical characterization and property-process matrix for valorizing copper extraction wastes: Enabling technology selection and screening-level resource classification

Abstract

A comprehensive characterization of copper extraction wastes, namely, tailings, electrostatic precipitator (ESP) dust, and slag, was conducted to establish a baseline for selecting efficient metal recovery flowsheets at a screening level. Analytical techniques, including ICP-OES, XRD, and SEM-EDS, revealed distinct properties for each waste stream from a single plant of global relevance. ESP dust was identified as a critical metal-rich stream with high concentrations of copper (17.3%) and cobalt (360 mg/kg), but also poses a significant environmental hazard because cadmium leaching exceeds regulatory limits (2.12 mg/L). Its fine particle size and soluble copper minerals make it ideally suited for hydrometallurgical processing, provided that integrated hazardous-element removal is included. Conversely, slag's refractory fayalite matrix and entrapped copper phases suggest alternative routes, such as pyrometallurgical re-smelting or vitrification. Tailings, with their acidic pH and low-grade, poorly liberated metals, indicate potential for bioleaching. This study provides a screening-level property-process matrix that links material characteristics to hypothesized recovery pathways, however, full classification would require quantitative studies including life-cycle assessment (E-axis), pilot-scale validation (F-axis), and statistically robust volume estimation (G-axis). The findings provide a scientifically justified framework for converting complex metallurgical wastes into valuable secondary resources while highlighting the need for further dynamic testing.