Production of calcium carbonate from steelmaking slag and captured CO2- optimisation of the carbonation process and product quality

摘要

The X2PCC pilot plant produces precipitated calcium carbonate (PCC) from calcium extracted from steel slag and CO2 gas. This work investigates the carbonation process in order to optimise it to produce PCC of the desired morphology and size. A literature review is presented showing the potential effects of different parameters on the morphology, size and quality of the PCC produced. Experiments are conducted varying different parameters and the morphology and size of the PCC are analysed based on this. Supersaturation is seen as key to understanding and controlling the process, so a model is built to show the supersaturation of the system. This involves activity coefficient modelling using the Pitzer model and estimations of the CO2 solubility and solubility product, Ksp. Pure rhombohedral calcite is produced and needle-like aragonite is produced up to a purity of 70%.