Date of Award

2026

Document Type

Open Access Dissertation

Degree Name

Doctor of Philosophy in Chemical Engineering (PhD)

Administrative Home Department

Department of Chemical Engineering

Advisor 1

Lei Pan

Committee Member 1

Timothy C. Eisele

Committee Member 2

David R. Shonnard

Committee Member 3

Darby Stacey

Abstract

The global transition toward electrification and renewable energy systems has driven an increase in critical metal demand. Primary sources are becoming increasingly depleted, prompting the need to exploit alternative sources. Critical metal bearing silicates are abundant however, their utilization is limited by slow reaction kinetics, and challenges associated with energy-intensive processing. Carbon-negative metal extraction is a promising pathway that simultaneously enables critical metal recovery and CO2 storage. This dissertation investigates a series of process innovations to enhance mineral carbonation and critical metal extraction from silicate minerals. Initial research explored the use of sodium sulfate (Na2SO4) to accelerate carbonation kinetics by increasing solution polarity relative to conventional sodium chloride (NaCl) systems, thereby facilitating the dissolution and transport of silicic acid formed during reaction. To address the inherent unreactivity of serpentine minerals, arising from strong hydroxyl bonding within their structure, thermal activation under reducing conditions was employed to enhance reactivity. Coupling this activation with chelation using Na2-EDTA enabled greater than 90% extraction of critical metals, including nickel and cobalt. To overcome kinetic limitations imposed by passivation and product layer formation during carbonation, mechanochemical approaches were evaluated. Attrition grinding effectively enhanced both carbonation and metal extraction by continuously exposing fresh reactive surfaces, achieving higher efficiencies than autogenous grinding. However, the autogenous approach demonstrated economic advantages due to its ability to operate at high solid concentrations and eliminate the need for external grinding media, supporting process scalability. The developed methods were further validated using real-world mine tailings, assessing the feasibility of integrating CO2 storage with critical metal recovery in practical systems. Techno-economic analysis (TEA) and life cycle assessment (LCA) revealed that, while the proposed carbon-negative mineralization pathways are promising, further optimization is required to achieve a global warming potential (GWP) below 1 and reduce CO2 storage costs. This work advances the development of integrated, carbon-negative technologies for sustainable critical mineral extraction and provides a pathway toward decarbonizing the mining industry.

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