Calcite precipitation from by-product red gypsum in aqueous carbonation process

Carbon dioxide (CO2) concentration in the atmosphere has been increasing rapidly, and this rapid change has led to promotion of CO2 reduction methods. Of all the available methods, CO2 mineral carbonation provides a leakage free method to produce environmentally benign and stable solid carbonates via a chemical conversion to a thermodynamically lower state. In this research, the precipitation of calcite from by-product red gypsum was evaluated for mineral CO2 sequestration. For this purpose, varied conditions of procedure variables such as reaction temperature, particle size, stirring rate, and liquid to solid ratio were studied. The results showed that applying optimum amount of above-mentioned variables converts the maximum Ca (98.8%) in carbonation process. Moreover, the results confirmed that red gypsum is a considerable potential to form calcium carbonate (CaCO3) during CO2 mineral carbonation process. Furthermore, the low cost and small amount of energy required in the use of by-product red gypsum were considered to be impressive advantages of the CO2 sequestration process. Therefore, the acceptable cost and energy required in mineral carbonation processing of red gypsum confirmed that using this raw material is also applicable method for mineral carbonation processes without any considerable environmental impact.