Study On The Decomposition Of The Witherite Under High Temperature

The natural barium carbonate is called witherite commonly. The barium salts and barium compounds extracted from the mineral are used widely in the electron, drilling, chemical industry, building materials, light industry, medicine and metallurgy, and they are important industrial materials. There is vast scale of barium mineral in Chengkou, Chongqing, which is the main mineral there. The storage capacity is very big not in China, but in the world. While, the existing production technology has a lot of faultinesses. So the rate of conversion is too low (the percent of BaO in the clinker aggregate is about 40%), and it has some faultinesses like low efficiency, big cost and high labor hardness. The existing way has baffled the development of the firm. For settling this problem, this paper studyed the decomposition of the witherite mineral under high temperature, and discussed the possibility of roasting the witherite by rotary kiln.By analyzing the question both in theory and experiments, this paper found that if the witherite is roasted directly adding nothing the temperature of the starting to decompounding is about 1200℃, and the temperature of the vast decompounding is about 1400 ℃. But if the temperature is above 1300℃, the witherite will bond , so this way can't be used in practical production. Through a lot of experiments , this paper deemed that if the witherite is roasted under 1350℃ by adding 10 percent of coke powder, and the reducing atmosphere is held at the same time, the result of the experiment will be best. Under this condition, the percent of the BaO in the clinker aggregate is up to 54%, which is above 70% according to the rate of conversion. Through building mathematic model this paper verified the results of the experiments. Otherwise, this paper had designed the rotary kiln and discussed the possibility to roast the witherite by rotary kiln. Several parameters had be determined, the speed of rotation: 0 ~5 r/min; inclination: 1%~5%; the length of the rotary kiln: 5m; the inter diameter: 0.25m and considered the main problem was to control the reducing atmosphere.