Activation methods for enhancing CO2 mineralization via mine tailings—A critical review

Abstract

Greenhouse gas emissions from fossil fuel combustion exacerbate global warming, necessitating scalable and cost-effective carbon capture and storage (CCS) strategies. Mineral carbonation has emerged as a promising solution, permanently converting carbon dioxide (CO₂) into stable carbonates while simultaneously repurposing mine tailings for sustainable waste management. Ultramafic and mafic mine tailings, which are rich in Mg- and Ca-bearing minerals, provide abundant and reactive feedstocks for CO₂ sequestration. This review examines the chemical, mineralogical, and physical characteristics of selected tailings from nickel, asbestos, diamond, gold, iron, and platinum group metal (PGM) mines to assess their carbonation potential, and also introduces a mineral-specific analysis of mechanical activation effects across these materials. However, inherent mineralogical differences necessitate tailored activation strategies to increase CO₂ reactivity. To address this, four principal activation methods are evaluated: (1) mechanical activation, which increases the surface area and number of defect sites but has limited dissolution effects; (2) chemical activation, which increases ion availability but raises concerns over reagent costs and waste disposal; (3) thermal activation, which dehydroxylates minerals at ∼650°C to increase reactivity but is energy intensive; and (4) engineered activation, which integrates multiple approaches, such as mechanochemical, thermochemical, and external-field-assisted techniques (e.g., microwaves and ultrasound), to achieve synergistic benefits. However, challenges such as energy optimization, large-scale implementation, and sustainable reagent recovery remain, and these are critically assessed through a cross-method analysis of scalability, cost, and environmental trade-offs. This critical review underscores the transformative potential of mine tailings as valuable resources for commercial-scale CO₂ sequestration, bridging climate change mitigation with circular economy principles and advancing sustainable industrial practices.