Advances in process development of aqueous CO2 mineralisation towards scalability

Aqueous mineralisation is a process that reacts CO2 with aqueous ions to produce solid carbonates that fix CO2 permanently. Over the past decade, the commercial deployment of mineral carbonation processes has been slow, as many processes have been shown to suffer from limited reaction rate and poor energy efficiency. Yet, the potential of further improvement of this route, and its theoretical capacity to address CO2 emissions at the global scale, still drive efforts from many researchers in academia and industry. Aqueous CO2 mineralisation remains an attractive option, requiring milder process parameters than gas-solid mineral carbonation, and offers more opportunities for intensification through chemical additives, catalysts, process integration, use of alternative energy sources, reactor design, among other innovations. Aqueous mineral carbonation processes are categorized into three branches: (1) two-step carbonation process with dissolution stage; (2) direct aqueous carbonation with solid phase as reactant; (3) direct aqueous carbonation of brines. For each category, the progress made in the investigation and optimization of process parameters, source of feedstock, process intensification strategies, and products evaluation for utilisation, were assessed. Coupled with the process development, process simulation and reaction modelling, environmental impact assessment, energetic analysis, and economic evaluation, have also been critically reviewed. The focus was on identifying those processes with less energy and cost intensity and most CO2 avoided, to inform the most promising options for scale-up. This review discusses the feasibility of a portfolio of technologies, and updates the current process development status in bridging the gap between benchscale investigation and industrial-scale implementation.