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Carbon dioxide utilization for enhanced metal recovery (EMR) during mineralization has been recently developed as part of CCUS (carbon capture, utilization, and storage). This paper describes fundamental studies on integrating CO 2 mineralization and concurrent selective metal extraction from natural olivine. Nearly 90% of nickel and cobalt extraction and mineral carbonation efficiency are achieved in a highly selective, single-step process. Direct aqueous mineral carbonation releases Ni 2+ and Co 2+ into aqueous solution for subsequent recovery, while Mg 2+ and Fe 2+ simultaneously convert to stable mineral carbonates for permanent CO 2 storage. This integrated process can be completed in neutral aqueous solution. Introduction of a metal-complexing ligand during mineral carbonation aids the highly selective extraction of Ni and Co over Fe and Mg. The ligand must have higher stability for Ni-/Co- complex ions compared with the Fe(II)-/Mg- complex ions and divalent metal carbonates. This single-step process with a suitable metal-complexing ligand is robust and utilizes carbonation processes under various kinetic regimes. This fundamental study provides a framework for further development and successful application of direct aqueous mineral carbonation with concurrent EMR. The enhanced metal extraction and CO 2 mineralization process may have implications for the clean energy transition, CO 2 storage and utilization, and development of new critical metal resources.

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This paper has been submitted for publication in the Canadian Metallurgical Quarterly (CMQ) journal. The technology of CO 2 sequestration by mineral carbonation: Current status and future prospects Abstract Mineral carbonation (MC) has been extensively researched all over the world since it was found as a natural exothermic process to permanently and safely sequester CO 2. In order to accelerate the natural process, various methods for carbonation of Mg-/Casilicate minerals and other industrial wastes have been studied. It has been found that the MC efficiency will increase with an increase of CO 2 pressure, retention time, temperature, mass ratio of Mg or Ca to Si in minerals, specific surface area, and the slurry concentration in a specific range, and with the introduction of effective catalysts, for example, 1M NaCl and 0.64M NaHCO 3 or carbonic anhydrase. However, there still is not a successful industrial application because of high economic cost and slow reaction rate. It is not economic to exploit Mg-and Ca-silicate minerals deposits or tailings to sequester CO 2 by MC, due to the cost of grinding and heat pre-treatment and in some cases the whole sequestration process may result in more CO 2 emissions than the amount of CO 2 sequestered due to the requirements of energy inputs. The process however, may be profitable as a whole (with carbon credits). It is suggested to combine MC with recovery of valuable metals from ore deposits in order to reduce the cost for MC by cost sharing for mineral recovery.

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