Kinetic study on reactive dissolution of the precipitated calcium carbonate in sulphurous acid solutions

This paper deals with a kinetics of the reactive dissolution of calcium carbonate in solutions of sulphurous acid. Advancing rate process was investigated by means of conversion yield of calcium carbonate versus time with temperature and granule size as variable parameters. All experiments were performed using a standard laboratory installation made up by a batch reactor with stirring, provided with a heating/cooling jacket with thermostated water In order to make a convenient selection of the solid phase, a comparative study was carried out using some natural sources of carbonates, namely: marble, limestone of Pata de Jos, limestone of Sandulesti and dolomitized limestone. The precipitated calcium carbonate from SC AZOMURES SA Tg. Mures has a similar behavior as any milled limestone. The kinetic model based on granule with shrinking core describes well enough the process, but only at its beginning steps. After that, as the solid reactant in solution is converted, diffusion process becomes the rate controlling step, fact proved by data validating the topochimical model. The value of overall constant, estimated by kinetic data processing, points out that the precipitated calcium carbonates are more reactive than any milled limestone, fact that makes it possible to use the raw material as reagent for wet desulfurization of the flue gases. Waste calcium carbonate, reactivity, reactive dissolution, sulphurous acid, kinetic models.