Harnessing Earth Abundant Ores and Resources and Uncovering the Underlying Mechanisms for the Selective Recovery of Transition Metals and Rare Earth Elements Coupled with Carbon Mineralization
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The global transition towards low-carbon energy systems has significantly increased the demand for energy-critical metals, including nickel, aluminum, manganese, cerium, and lanthanum. These metals are essential for the manufacturing of batteries, wind turbines, solar panels, and various other clean energy technologies. Concurrently, initiatives aimed at mitigating climate change necessitate the development of innovative carbon capture strategies that are both scalable and permanent. This thesis proposes an integrated approach to simultaneously address these two challenges by establishing sustainable pathways for the recovery of critical metals while sequestering carbon dioxide (CO₂) through mineralization processes.The research begins with an assessment of the dissolution kinetics of eight mafic and ultramafic rock types under geochemical conditions pertinent to in-situ CO₂ mineralization. Utilizing single-pass flow-through experiments, the release rates of cations, including Mg²⁺, Fe²⁺, Ni²⁺, and Al³⁺, were quantified. This data provides a foundational basis for identifying lithologies that are conducive to simultaneous sequestration and metal recovery. Alternative approach to the in-situ carbon mineralization is a ligand-assisted ex-situ direct aqueous carbon mineralization process that employs Twin Sisters Olivine (TSO) as a reactive substrate. This innovative approach enables the concurrent precipitation of magnesite and the recovery of valuable metals under conditions of elevated temperature and CO₂ pressure. A variety of analytical techniques, including X-ray diffraction (XRD), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), are utilized to elucidate the roles of different chelating agents, silica passivation, and the thermal degradation of ligands in influencing carbonation efficiency and leaching behavior. To achieve selective metal separation, this thesis further investigates solid-phase extraction (SPE) utilizing functionalized mesoporous silica for the separation of cerium from lanthanum. The SPE system exhibited high selectivity and reusability. Furthermore, molecular insights into zinc adsorption were acquired through density functional theory (DFT), elucidating significant binding interactions on redox-active functionalized silica. In summary, this study introduces a multidisciplinary framework that integrates geochemistry, materials science, and molecular modeling, with the objective of developing environmentally sustainable strategies that integrate CO₂ sequestration with the recovery and separation of critical metals.