Multi-analytical interpretative model for the assessment of the mineralogical-chemical properties and environmental impact of historical Zn-Pb slags

Abstract This study presents an integrated multi-analytical model for evaluating the mineralogical and chemical properties, as well as the environmental risk, of historical Zn-Pb slags. The investigated material originates from a 19th-century spoil dump, representing a typical example of legacy metallurgical waste. The proposed model integrates historical data analysis, macroscopic characterization, and combined chemical and mineralogical investigations using XRF, ICP-OES, SEM/EDS, and XRD techniques. The results demonstrate significant heterogeneity in slag composition within a single spoil dump profile. Heavy metals were identified in multiple forms, including dispersion within amorphous phases, association with oxide phases, and incorporation into silicate structures. Weathering processes, particularly glaze devitrification, were found to influence the progressive release of metals, with their mobility strongly controlled by environmental conditions such as pH. The proposed model provides a practical tool for integrated characterization and environmental risk assessment of metallurgical waste. It can support decision-making in waste management, site assessment, and remediation planning, and is adaptable to other types of anthropogenic and natural materials.