The Study On Preparation Of Nanometer Calcium Carbonate Particles By Calcium Carbide Residue In Ultrasound Field

Preparation of acetylene gas power stone, PVC and other products, At the same time emiting large amounts of calcium carbide,which is difficult to dispose of waste. Carbide contains a lot of soda lime and other substances. The carbide is more difficult to deal with industrial waste, if it does not dispose in time, it would pose a serious threat right environment protection, because the main components of carbide of calcium hydroxide, which can be processed into higher value-added of nano calcium carbonate.In this paper, scrap carbide was made into calcium carbonate as raw materials,The study concludes the pretreatment of carbide and the kinetics, the primary study of preparation of nano calcium carbonate under ultrasound field and the carbonation process with different flow rates, different ultrasound power ,different calcium hydroxide and whether the additive product of particle size on reaction rate and the impact of dispersion and crystal. Finally its carbonization reaction characteristics and mechanism of calcium carbonate crystal nucleation was discussed1.Pretreatment process of carbide, the use of nai-Chi STA-449 thermal analytical system of the burning characteristics of carbide, using X-ray diffraction and scanning electron microscopy SEM to study the changes of carbide microstructure and dynamics at high temperature. Mainly by the content of carbide was found more than 80% of the Ca(OH)₂ and a small amount of CaCO₃,α-SiO₂ andα-Fe₂O₃ phase composition, after calcination. The main crystalline phase is CaO. Calcined at 900℃and sintering process, carbide surface by the many swelled class composed of dumbbell-shaped structure of CaO grain after sintering time at high temperatures, And the size of the ordered and uniform, the boundary clear. Shrinking core model with carbide slag in the calcination process simulation. Calculated activation energy of its calcination to prepare for further study of nano calcium carbide to provide a theoretical basis. 2.Carbonation reaction in the process of ultrasound field, using conductivity meter and pH meter traces carbide Ca(OH) 2-H₂O-CO₂ system at the same time, nanometer calcium carbonate reaction crystallization process of tracking and detection of the preparation process Ca(OH)₂ in the concentration and CO₂ mixed gas volume concentration, the additive product particle size, reaction rate, dispersion and crystal form. And using TEM, XRD diffraction patterns by means of particle composition and structure were characterized. The results show that: with Ca(OH)₂ concentration was increased, the product particle size increases, with increasing volume concentration of CO₂, additive to carbon nano calcium carbonate particle size. The product is good dispersion in small particle size, crystal form is more rules, in the preparation of nano calcium carbonate under ultrasound, using conductivity meter.pH meter and other methods, followed the suspension of calcium hydroxide carbonation process ,The results show that carbonation reaction under ultrasound in the basic and non-carbonation reaction characteristics very similar to the ultrasonic field, And the carbonation process has not changed, but significantly it shortened the reaction time, the dissolution rate of carbation increased with the increasing of surface magnitude of gas ,CO₂ concentrationand power of ultrasound,and decreased with the increasing of reaction temperature ,and the reaction kinetics of a preliminary study, The carbonation can be divided into two stages;the constant rate period and the rate-changing one.and the equation cerrelated can express the kinetics of the process properly.3.Ultrasonic Field on the Preparation of nano calcium carbonate carbide nucleation mechanism was discussed and concluded that ultrasound for the nucleation of calcium carbonate has a significant role in promoting, and for the crystal growth is significantly inhibited.