Optimizing metal recovery from slag leaching solutions: Advanced ion exchange techniques for sustainable resource extraction

Abstract

Metal recovery through ion exchange (IX) is a promising strategy for resource extraction and environmental conservation. We assessed the efficacy of IX in recovering metal ions from slag leachates sourced from a Chilean copper processing plant. At pH 4.3, selective precipitation removed over 90 % of Fe(III) and Al(III). In batch mode, an iminodiacetic-functionalized resin selectively adsorbed Fe(III) and Al(III) ions, outcompeting other valuable metals. Optimizing pH and matrix composition in column operations boosted nickel recovery to 0.65 eq/L using a bispicolylamine-functionalized resin. A 3.5 % NH4OH solution proved effective for nickel elution, reaching 10 g/L peak concentration. The successful upscaling of the process from a 10 mL to a 100 mL bed volume demonstrates positive insights for industrial application, enabling efficient nickel recovery from larger volumes of water. SEM analysis revealed the physical state on the resin, and metal ion interactions, which verified the interpretations from water analyses, reinforcing the reliability and coherence of the results. Ongoing work aims to extend this method to selective zinc and cobalt recovery. The flow charts developed in this study aid in selecting appropriate IX-based wastewater treatments. This research aims to recover metals from mining-affected water, reduce waste, and promote metal recycling while enhancing environmental conservation efforts.