Extraction of magnesium from four Finnish magnesium silicate rocks for CO2 mineralisation-part 2: Aqueous solution extraction

Extraction of magnesium from minerals serpentinite, amphibolite and diopside for mineral carbonation in Finland are compared. In part two of this study, extraction in an aqueous solution reactor is the main focus, using solvents such as ammonium bisulphate (ABS), ammonium sulphate (AS) and hydrochloric acid. The advantage of using a mixture of ABS and AS as solvent is analysed. A process suggested containing an aqueous solution extraction reactor is compared to a mineral carbonation process with a thermal solid/solid extraction step. Extracted elements, mainly magnesium, are measured with atomic absorption spectroscopy (AAS). The two serpentines tested in the study showed sufficient reactivities required for an efficient carbonation process, while the two other minerals' reactivities were insufficient. The best extraction results obtained for the two serpentines give a binding capacity of CO2 that is 292 and 260 kg CO2/ton rock. Reactivity with a minimal amount of water, and recirculating and regenerating solvent salts is analysed.