Study On Synthesis Of Nanometer Calcium Carbonate

The particle size, particle shape, distribution of particle size and dispersion are the important quality parameters of nano-CaCO3. The nano-CaCO3 product with smaller size, narrow size distribution and better dispersion is of more economic value. The activity of lime and the control of carbonization can obviously influence the quality of nano-CaCO3. It's very important to prepare lime with high activity and improve carbonization process by taking effective measures.Firstly, the lump lime calcining from traditional industrial kiln was used as material to synthesize nano-CaCO3 in this paper. The effects of reaction temperature, orifice diameter of gas distributor, flow rate of gas, concentration of carbon dioxide, concentration of calcium hydroxide, aging time of slaking soriflux, rotating speed of stirring and additives on crystallization of nanometer calcium carbonate were systematically studied in the fitful bubbling carbonization reactor. The optimum conditions of nano-CaCO3 synthesis were obtained. Sphere nano-CaCO3 particles having the mean size of 45~90nm and narrow size distribution were prepared. The carbonization mechanism was analyzed carefully by the change of pH and viscosity in carbonization process of suspension system.Then, the lime with high activity was prepared from calcining small particles of limestone. The influences of calcining temperature, particle size and calcining time on the activity of lime were discussed. It was shown that the activity of lime could be improved to a great extent compared with lump lime calcining from traditional industrial kiln, and the calcining time and temperature could be reduced obviously.Finally, the lime with high activity was used as material to synthesize nano-CaCO3. It was shown that, compared with the product prepared from lump lime calcining from traditional industrial kiln, the nano-CaCO3 particles with smaller size and more narrow size distribution and better dispersivity could be synthesized under the same carbonization conditions. And the carbonization time can be reduced obviously.