(173ag) Utilizing Mg-Bearing Minerals for Selective Nickel and Iron Recovery Coupled with Carbonates and Amorphous Silica Production

This study addresses critical mineral scarcity and climate change by developing a sustainable approach for recovering multiple metals from olivine while promoting carbon sequestration. Through a comprehensive leaching process, metal recovery, and reagent recycling, the approach achieves selective recovery of valuable metals (Ni²⁺) and converts Mg²⁺ into carbonates for CO₂ storage. Hydrometallurgical leaching facilitates over 90% metal dissolution and conversion, followed by Fe extraction and pH swing for high-purity products, such as iron hydroxide, amorphous silica, nickel carbonates and Mg-carbonates. It was found that iron removal can minimize metal loss for the nickel extraction and carbonation. Moreover, A techno-economic assessment highlights the economic benefits of this approach to removing iron in the early stage. Selective Ni²⁺ extraction is achieved using Versatic 10 by adjusting the equilibrium pH to 6.5-6.8 after removing impurities (e.g. Fe, Si), followed by stripping with bubbling CO₂. Mg-rich leachate is then used for Mg-carbonate production under ambient conditions. The proposed integrated process yields high-purity value-added products and sequestered CO₂.