Research on integrated CO2 absorption-mineralization and regeneration of absorbent process

Abstract

The hot potassium-alkali method provides excellent performance for the absorption of CO2 from flue gas. However, the high energy consumption by absorbent regeneration poses a critical barrier to the widespread industrialization of the hot potassium-alkali method. In this study, an integrated CO2 absorption-mineralization and regeneration of absorbent (IAMR) process was proposed using K2CO3 solution as the absorbent and steel slag as the desorbent at normal temperature and pressure. This method greatly reduced the energy consumption and costs compared with the traditional thermal regeneration method. Under the optimal conditions, i.e. a K2CO3 concentration of 1.0 mol/L, reaction temperature of 60 °C and liquid-solid (K2CO3 solution-steel slag) ratio of 14 mL/g, the carbonation conversion of the steel slag reached 58.63% after 120min, corresponding to a CO2 storage capacity of 212 kg/t steel slag. The reaction process showed that the main component Ca2SiO4 in the steel slag had high solubility activity in K2CO3 solution which significantly enhanced the rate and efficiency of CO2 sequestration. Moreover, the performance stability of K2CO3 solution during CO2 absorption-desorption circulation was discussed. This research is of great significance for the simultaneous treatment of alkaline waste slags (steel slag, fly ash, etc.) and mitigation of greenhouse gases.