SYNTHESIS OF PRECIPITATED CALCIUM CARBONATE IN THE FORM OF CALCITE CRYSTALS AS A VALORIZATION OF LIME CARBIDE SLAG WASTE

The presence of high level of calcium oxide (CaO) has been detected in lime carbide (LC) slag waste generated form the acetylene gas industry. There is untapped potential for the valorization of LC-slag waste, where the calcium oxide content can be converted into Precipitated Calcium Carbonate (PCC/CaCO3) which is valuable and can contribute to carbon dioxide sequestration. Calcium carbonate has unique advantages as a carrier, but some critical problems need to be addressed, such as low productivity, disordered structure, and weak adsorption ability. In this study, the desired type of crystal is calcite which has the most stable characteristics from the other types of crystals. Micro-bubble reactor is used as a method of dispersing CO₂ in converting CaO to PCC/CaCO3. This method has the advantage of being able to maintain CO₂ gas bubbles longer in solution so that the reaction time that occurs can also be optimize. The LC-Slag valorization process was carried out by varying the LC-slag concentration between 3-7% w/w and the reaction time between 15-35 minutes. The dispersion of CO₂ gas is fixed at a flow rate of 2.5 L/m. From the yield, it can be seen that the longer the reaction time, the yield of PCC/CaCO3 produced is also greater. At 35 minute reaction time and concentration LC-Slag Waste varied 3, 5, and 7% w/w, the produced yields were 89.44, 95.00, and 93.76%, respectively. This is evidenced by the results of SEM and XRD analysis. In the future, this treatment method is expected to provide more insight and guidance for the valorization of LC-slag waste and CO₂ mineralization in the acetylene gas industry.