Ex-situ mineral carbonation process challenges and technology enablers: A review from Australia’s perspective

Abstract

While reacting CO₂ with sub-surface mafic/ultramafic phases potentially captures greenhouse gas emissions, low porosity and very slow kinetics makes this problematic. Mineral processing tailings and mining wastes offer distinct particles with exposed surfaces that enhance reactivity, and Australia’s mining sector has numerous prospective tailings streams. Passive carbonation of such tailings is known, although reactivity is still usually low. This review evaluates the potential of accelerated mineral carbonation (AMC), engineered routes to facilitate mafic/ultramafic tailings carbonation.

The state-of-the-art of AMC technologies are evaluated in terms of operational principles, advantages, process challenges and environmental impacts. After providing a snapshot of Australia’s current mining industry, the best carbonation routes/practices for favorable rock types (e.g. wollastonite, serpentinite, olivine) are reviewed, highlighting their key Australian deposits or operations. Major challenges facing technology scale-up (CO₂ source, particle size and associated environmental risks) are analyzed. Integrating AMC with direct air capture (DAC) provides an adjacent pure, pressurized CO₂ stream to raise the viability of both technologies, while breakthroughs in secondary metal recovery or marketing carbonated end-products can also bolster business models. However, in the absence of supporting regulatory frameworks, major companies have been reluctant to adopt early-stage research, design and development to elevate AMC technologies toward commercialization.