Organic ligands and CO2 unlock the potential for energy relevant metals recovery and carbon mineralization from mafic rocks

The need to meet the rising demand for energy relevant metals (e.g., Fe, Mn, Al, Cr, Ni) motivates the development of sustainable chemical pathways to recover these metals from earth abundant and unconventional resources such as mafic rocks. Mafic resources such as olivine gabbro (OG) and picrite basalt (PB) are harnessed for coupled carbon mineralization and metal recovery, and contrasted with ultramafic resources such as serpentinized peridotite (SP). The carbon mineralization extents of Ca, and Mg species in SP, OG, and PB are 71%, 39%, and 11%, respectively, at 185 °C, pCO₂ of 50 bar, and a reaction time of 10 h in a mixture bearing 2 M NaHCO₃ and 0.1 M Na₂H₂EDTA·2H₂O. Higher carbon mineralization extents are directly related to olivine and pyroxene contents. Magnesite is observed as the dominant carbonate phase in OG, while magnesian calcite and dolomite are consistently formed in PB. The presence of metal chelating solvents such as Na₂H₂EDTA·2H₂O is reported to enhance metal dissolution (Fe: ~2692 & 2606 ppm, Al: 2753 & 2670 for OG and PB respectively). These results unlock the possibility of harnessing mafic rocks such as OG and PB as resources for the co-recovery of energy relevant metals coupled with carbon mineralization.