Study On Preparating Different Crystal Shape Of Calcium Carbonate By The Method Of Liquid Reaction

CaCO3 is applied widely to various industries as one of important inorganic materials. As present, some domestic or oversea scholars pay their more attation to the study of carbonization reaction between gas and liquid. In this process, CaCO3 is preparated by entering CO2 into the Ca(OH)2 latex, which is regarded as calcium source. A great deal of limestones and coals are consumed in this process. With the cause of limit and non-regeneration of mineral resources, a new technologic route is selected, that is by-product CaCl2 in producing NaCO3 and NH4HCO3 are selected resonablely as basic materials in this paper, and CaCO3 is preparated by the method of liquid reaction. The study has not only theoretical value but also apparent benefit for protecting environment and applicate extensively outlook.The crystal process of CaCO, is comprised of two phases, that is nucleation and crystal growth of CaCO3. It will be the key of preparating superfine and different crystal CaCO3 how to control effectively the process about mentioned. Therefore, we have selected water-solubility macromeclecule polmer as additive, with its characteristic of absorbed at the interface between solid and liquid, it can be absorbed on the freshly formed surface of CaCO3 crystal, which can influence the crystal process of CaCO3. At the same time, the relative rate of growth of every behaviour surface of CaCO3 crystal can be changed, and the aim of adjusting crystal shape of CaCO3 is achieved while the types of additive is altered.In the study of influence of water-solubility macromeclecule polmer on the crystal process of CaCO3, the factors such as the concentration of additive, the temperature of reaction, the concentration of original solution, the stirring rate and so on, which can effect the crystal of CaCO3, have been discussed in this paper. Seen from the results of experiment, it has double effects that rstrian the nucleation and crystal growth of CaCO3 when additive is joined into the reactive solutions. Thus, the fall of concentration of calcium ion in solution becomes slower than the solution's without additive, seen from the further analysis of experimental results , the crystal growth of CaCO, is retarded basicly in the view of kinetics by the additive entered into the solution during the whole crystal process in spite that additive has effection on the nucleation of CaCO3. Therefore, we had studied the kinetic mechanism of growth of CaCO, crystal and calculated its kinetic contant and reactiveseries under bank conditions and additive's in this paper. We have found that kinetic contant of crystal growth is changed by the additive, but reactive series not. The results of experiment has confirmed our presumption of additive effect on the crystal process of CaCO3.At present, there is a lack of literatures for preparating CaCO3 by the method of liquid reaction.The particle size of CaCO3 is big, and crystal shape is simple when CaCO3 is preparated by the method of liquid reaction. With the characteristic of water-solubility macromeclecule polmer absorbed at the interface between solid and liquid, the particle size of CaCO3 can be restrained effectively and the crystal shape of CaCO3 may also be control-ed, and spherical and plate CaCO3 have been preparated in this paper. So conditions are be created for producing different crystal shape CaCO3 in industry by this method.