High-efficiency CO2 sequestration through direct aqueous carbonation of carbide slag: determination of carbonation reaction and optimization of operation parameters

Under the dual-carbon target, CO2 mineralization through solid wastes presents a mutually beneficial approach for permanent carbon emission reduction at a low material cost, while also enabling the resource utilization of these wastes. However, despite its potential, a comprehensive understanding about the effect of industrial solid waste properties and operating parameters on the carbonation process, and the mechanism of direct aqueous carbonation is still lacking. A series of experiments were conducted to compare the carbonation performance of fly ash, steel slag, and carbide slag. Subsequently, CO2 mineralization by carbide slag was systematically studied under various operating parameters due to its high CO2 sequestration capacity. Results showed the reactivity of CaO and Ca(OH)2 was higher than that of CaO·SiO2 and 2CaO·SiO2. Carbide slag demonstrated a sequestration capacity of 610.8 g CO2/kg and carbonation efficiency ζCa of 62.04