Control of morphology, specific surface area and agglomeration of precipitated calcium carbonate crystals through a multiphase carbonation process
In this study, precipitated calcium carbonate (PCC) has been produced using a semi-continuous carbonation process within Ca(OH)2(s)-CO2(g)-H2O system inside a bench-scale reactor. In order to understand the effect of temperature, solid percent of the milk of lime (MOL), CO2 gas injection rate, agitation rate on the conductivity, the specific surface area, microporous surface area (and subsequently agglomeration), and reaction termination time, an experimental procedure was used based on a central composite design (CCD). The conductivity and pH were applied as the parameters controlling the reaction termination time. Using the data obtained from the multiple regression analysis, the effect of the parameters on the above-mentioned responses were obtained. Since the resulting conductivity has a direct relationship with the morphology; therefore the conductivity levels were considered as parameters to determine the morphology. Moreover, the microporous surface area of the PCC considered to determining the agglomeration. In this study, ultra-pure PCC with the high specific surface area and controlled morphology (scalenohedral, cluster scalenohedral, rhombohedral, vaterite or Chain-like agglomerates) were produced, without adding any crystal growth modifier (CGM). The obtained PCC dimensions of 20 nm up to 2 µm, having a specific surface area of 5.99-26.69 m2.g-1, purity of 99.86%, and a controlled morphology.