Acceleration of Iron-Rich Olivine CO2 Mineral Carbonation and Utilization for Simultaneous Critical Nickel and Cobalt Recovery

Abstract

CO2 mineral carbonation is an important method to sequester carbon dioxide (CO2) in the form of stable mineral carbonates for permanent storage. The slow kinetics of carbonation, especially for iron-rich olivine, is the major challenge for potential application. This work proposes methods to accelerate the mineral carbonation process of different materials in the general mineral grouping of divalent metals–olivine for simultaneous nickel and cobalt recovery. It is found that nickel-olivine is facile for mineral carbonation compared to ferrous and magnesium olivine. Ferrous olivine is the most difficult form of olivine to carbonate as illustrated in both thermodynamics and experimental test results. The increase in iron content in olivine inhibits the CO2 mineral carbonation process by forming an iron-silica-rich passivation interlayer. The use of a reducing gas or reagent can enhance the mineral carbonation of olivine probably through hindering oxidation of Fe(Ⅱ). The addition of sodium nitrilotriacetate (NTA) as a metal complexing agent is much more efficient for the acceleration than usage of a reducing atmosphere. The combination of sodium bicarbonate/CO2 gas supply and NTA can enhance the diffusion of all divalent metal ions from the reacting olivine surface, thereby limiting the formation of the passivation interlayer. Meanwhile, highly selective nickel and cobalt leaching can be simultaneously achieved along with the CO2 mineral carbonation, 94% nickel, and 92% cobalt leaching as well as 47% mineral carbonation versus only 10% iron and 1% magnesium leached in 2 h. This work provides a novel direction to achieve critical metals recovery with accelerated mineral carbonation process.