Nano-scale Preparation Of Active Calcium Carbonate

Nanograde calcium carbonate is a kind of functional inorganic filler. It not only can increase the volume of product and decrease the cost, but also has excellent tefnj-or.ce character. In this paper, the preparation technology and surface mod/station are studied systematically.The key reaction, carbonation, and its mechanism of the preparation of nanograde calcium carbonate are studied. The basic character of carbonation reaction is discovered by monitoring the conductivity and pH value during the reaction. Some reasonable explanation and deduction are also given. Through the experiments of suspending gas and adding seed crystal, the explanation and deduction are verified.Based on the single-factor experiments of preparing nanograde calcium carbonate, the optimum technology conditions, which provide some consultation for industry, are found. The temperature of reaction is about 10癈. The volume concentration of CO2 is 30%~40% and the concentration of Ca(OH)2 is around 8%. Meanwhile, the preparations of different crystal form calcium carbonate are also studied in this paper. By adding different additive during carbonating process, cubic, spherical and chain calcium carbonate are prepared. Moreover, ultrasonic technique is used in the experiment. The result shows that the particle size of calcium carbonate can be decreased effectively by using ultrasonic, and the distribution of the particle size is narrow. Through examination, it can be easy found that the particle sizes of the calcium carbonate are less than 100nm and the average of pH value 8.81, the average subside volume 5.11nu/g,the average of the whiteness degree (Wj) 90.88. That means all of the calcium carbonate prepared reach the national standard of high-quality products.In the end, the surface activation of nanograde calcium carbonate is also studied. Several new activators are developed and used in the experiments, and some characters of the activation calcium carbonate are investigated and determined as following: the activation rate 100%, the average value of oil absorption 46.8g/100g, and the whiteness degree (Wj) 93.70. All the activation calcium carbonates prepared fit in with the nationalstandard.