Treatment of Industrial Alkaline Solid Wastes Using Carbon Dioxide

Carbon dioxide capture and storage (CCS) is an effective method of reducing CO₂ emissions into the atmosphere. In this study, improved mineral carbonation is evaluated as a potential for CCS, where CO₂ is sequestered in a permanent stable carbonated form. Raw materials were selected from the UAE industrial residues like steel-making, cement and acetylene production because they have calcium-rich content as calcium oxide and/or calcium silicate, which have the potential to store CO₂ in the form of permanently stable carbonate minerals. The solid particles were pre-treated, then subjected to direct gas–solid carbonation reaction. Gas analyzer was installed at the output stream of the testing unit to measure the concentration of unreacted CO₂ consequently, and calculate CO₂ captured by the difference between the initial and final concentration. The carbonated products were characterized using pH, conductivity, TDS, thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) to determine the overall sequestration capacity and efficiency of these waste materials for CCS. Based on the total calcium content, the calculated sequestration of CO₂ was: 0.27 kg CO₂/kg-ladle furnace (LF) slag, 0.72 kg CO₂/kg cement kiln dust (CKD) and 0.58 kg CO₂/kg carbide lime waste (CLW).