Scaling Mineral Carbonation and Critical Mineral Recovery in Mining Waste: Process Engineering, Techno-Economics, and Public Policy

The growing need to secure critical minerals for clean energy technologies, combined with the imperative to mitigate climate change, has created a unique opportunity to integrate mineral recovery and carbon sequestration. This dissertation investigates the potential of mine tailings as a dual-purpose feedstock for both critical mineral extraction and CO2 storage through mineral carbonation. Mine tailings, often a byproduct of industrial activities, present a promising source of magnesium and calcium that can react with CO2 to form stable carbonate minerals, thus permanently storing carbon while recovering valuable resources. This research focuses on optimizing the mineralization of CO2, from four types of legacy tailings: platinum group element tailings, basalt tailings, and two sources of legacy asbestos waste. The tailings were characterized to assess their mineralogical composition and potential for both mineral recovery and carbonation. The study involved a series of thermal and chemical extraction experiments, targeting conditions that maximize the release of magnesium and other critical minerals while enhancing carbonation efficiency. Results indicate that extraction efficiencies varied by tailings type, with KCAC tailings achieving the highest magnesium recovery (80%). The variation in performance across tailings is discussed in terms of mineralogical structure, reactive surface area, and porosity. A techno-economic analysis (TEA) was developed to assess the costs and benefits of integrating critical mineral recovery with CO2 sequestration in industrial applications. The TEA highlighted that while mineral carbonation presents a viable pathway for reducing CO2 emissions, the economic feasibility is sensitive to feedstock characteristics, processing conditions, and market demand for recovered minerals. Key cost drivers identified include reagent consumption, energy requirements, and equipment specifications for handling corrosive substances and high-pressure environments. The policy implications of these findings are also explored, particularly in relation to the U.S. Superfund law (CERCLA) and the Resource Conservation and Recovery Act (RCRA), which govern the management of industrial waste and incentivize CO2 capture and storage (CCS) technologies. Policy recommendations focus on advancing regulatory frameworks to support the utilization of legacy waste streams for critical mineral recovery and carbon sequestration, with the potential to contribute to the goals of the global energy transition and climate mitigation. This dissertation concludes by emphasizing the importance of cross-sector collaboration in advancing the development of carbon mineralization technologies. Future research should focus on scaling up integrated processes, improving material handling, and addressing environmental and economic challenges. By leveraging mine tailings as a resource for both critical minerals and carbon storage, this work contributes to the broader effort to create sustainable, circular economies that address both resource security and climate change.