Optimized structural parameters and heat extraction capacity of mixing device for constant pressure CO2 mineralization using alkaline waste

Alkaline waste such as calcium carbide slag is an ideal material for mineralizing CO 2 and promoting atmospheric carbon reduction. In this study, the structural parameters of a mixing device and a thermal extraction method for the high-efficiency mineralization of CO 2 using alkaline waste were optimized. First, the effects of various factors including the length–diameter ratio, blade inclination angle, spacing, and diameter in constant-pressure and continuous-feed systems on the degree of CO 2 mineralization using carbide slag and on the extraction of the reaction heat during the mineralization process were investigated through experiments and numerical simulations. The influence of different configurations of the heat pipe and the internal fluid flow rate on extraction of the reaction heat was explored. The influence of different factors on the mineralization efficiency and heat extraction ability was analyzed based on the orthogonal simulation method. When the length–diameter ratio, blade inclination angle, spacing, and diameter of the mixing device were 3, 15, 6 cm, and 14 cm respectively, and a heat pipe was used, the heat extraction during calcium carbide slag (alkaline waste) mineralization of CO 2 was at a maximum. In addition, the winding configuration of the heat pipe, which is beneficial for extracting more reaction heat, was optimal, and a model of the relationship between the heat pipe outlet water temperature and flow velocity at the outlet of the heat pipe was established. This study provides theoretical guidance for the field application of alkaline waste for high-efficiency mineralization of CO 2 , which can accelerate the realization of peak CO 2 emissions and carbon neutrality.