Techno-economic analysis for the integration of ex situ CO2 mineralization and mineral mining

The paper reports a techno-economic analysis (TEA) of ex situ carbon dioxide (CO2) mineralization integrated with a refining process for the recovery of valuable materials such as carbonates for construction and critical minerals for renewable energy systems. The TEA compares the costs of two proposed processes for CO2 mineralization and material recovery. One process uses silicate rocks and the other considers deep-subsurface brines. The TEA model takes input on feed quality and process engineering parameters to produce economic outputs including capital and operating expenses as well as revenues from carbonates and metal sales. The results are combined with a harmonized life cycle assessment (LCA) to evaluate the net carbon balance, ultimately yielding a net cost for CO2 storage. The results show that recovering high-purity products suitable for the market requires a series of refining units for both feedstocks. While rock-based processes can produce 4–5 times more critical elements annually compared to brine-based processes, the additional revenue does not offset the increased capital costs associated with the pre-processing of the ultramafic rocks. In conclusion, an integrated process of CO2 mineralization and material recovery utilizing deep-subsurface brine proves more cost-effective than one relying on ultramafic rocks, primarily due to the elimination of upstream grinding and extraction units. This approach also opens opportunities for integration with geothermal energy conversion, which is currently the primary operation producing deep-subsurface brines.