Systematic Approach to Determination of Maximum Achievable Capture Capacity via Leaching and Carbonation Processes for Alkaline Steelmaking Wastes in a Rotating Packed Bed

Accelerated carbonation of basic oxygen furnace slag (BOFS) coupled with cold-rolling wastewater (CRW) was performed in a rotating packed bed (RPB) as a promising process for both CO<sub>2</sub> fixation and wastewater treatment. The maximum achievable capture capacity (MACC) via leaching and carbonation processes for BOFS in an RPB was systematically determined throughout this study. The leaching behavior of various metal ions from the BOFS into the CRW was investigated by a kinetic model. In addition, quantitative X-ray diffraction (QXRD) using the Rietveld method was carried out to determine the process chemistry of carbonation of BOFS with CRW in an RPB. According to the QXRD results, the major mineral phases reacting with CO<sub>2</sub> in BOFS were Ca­(OH)<sub>2</sub>, Ca<sub>2</sub>(HSiO<sub>4</sub>)­(OH), CaSiO<sub>3</sub>, and Ca<sub>2</sub>Fe<sub>1.04</sub>Al<sub>0.986</sub>O<sub>5</sub>. Meanwhile, the carbonation product was identified as calcite according to the observations of SEM, XEDS, and mappings. Furthermore, the MACC of the lab-scale RPB process was determined by balancing the carbonation conversion and energy consumption. In that case, the overall energy consumption, including grinding, pumping, stirring, and rotating processes, was estimated to be 707 kWh/t-CO<sub>2</sub>. It was thus concluded that CO<sub>2</sub> capture by accelerated carbonation of BOFS could be effectively and efficiently performed by coutilizing with CRW in an RPB.