Kinetics model adaptability analysis of CO2 sequestration process utilizing steelmaking slag and cold-rolling wastewater

Abstract

Better adaptive kinetics model for CO2 sequestration utilizing wastes in steelmaking plant has a big significance for establishing green out-circulating network system. This work investigated the effect of temperature, L/S ratio and cold-rolling wastewater concentration on carbonation degree in basic oxygen furnace slag and CRW carbonation process, then their kinetics was discussed by surface coverage model and shrinking core model, respectively, in order to evaluate their adaptability and accuracy. Furthermore, CO2 sequestration intensifying factor was originally proposed for considering the carbonation depth, through comparing diffusion coefficient of CO2 between water carbonation and wastewater carbonation. The results showed that carbonation conversion increased as temperature and CRW concentration increased except for L/S ratio, and the maximum carbonation could reach 41.499 ± 1.240%. Because higher prediction error existed in surface coverage model, the shrinking core model had a better adaptability and accuracy for analyzing carbonation process in autoclave. Meanwhile, the CO2 sequestration intensifying factor was 1.6 times as big as carbonation process in distilled water as a result of DCO2 value. CO2 sequestration reaction in our work was controlled by calcium diffused because of DCO2 (0.700–0.976 × 10−4 cm2 s−1) and DCa (0.935–1.149 × 10−5 cm2 s−1). The results above will be helpful for us to better comprehend the reaction kinetics at micro-scale, when the idea of triple wastes self-circulation system network will be established to industrial application.