Physical Changes of the Material in the Rotary Kiln
Posted Nov 05 2012 1:06am
The sintering process of the raw materials is carried out in the rotary kiln. Since the rotary kiln has certain slope and speed, the raw material moves from the cold end (kiln head) of the kiln to the hot end (kiln end) of the kiln. Under the action of high temperature, the raw materials become the clinker though the several stages, namely, drying, preheat decomposition, sintering and cooling. Compared with the above stages, the rotary kiln along the length of the kiln from the kiln end to the kiln head can be divided into the drying zone, preheat decomposition zone, sintering zone and the cooling zone. According to the physical and chemical changes of the materials that occur in the kiln, the rotary kiln can be divided into three zones from the kiln end. The raw slurry of the drying zone generally contains attached water about 38-40%. The 82 ° C raw slurry is injected into the kiln head by the spray gun. The raw slurry falls down and returns the rotary kiln to mix with the kiln dust. In this mixing process, the raw slurry can evaporate large amount of water and forms the agglomerates to move toward the kiln head. The role of the drying zone is to remove the attached water in the slurry. The temperature of the drying zone of the furnace and the water content are determined by the detail operations. In general cases, the temperature is about 120 ℃ and the water content in the slurry should be less than 10% to 12%. The kiln temperature should decrease from 800 ℃ to 250 ℃. After the kiln dust generated by various zones of the kiln head enters the drying zone, part of the kiln dust collide the slurry injected. They will lose the energy and enter the dough. However, the large amount of water evaporates here, so the kiln gas flow rate is very large. With the slurry atomization, most of the dust (fine clinker surface) is produced and discharge from the kiln. The kiln is collected by the dust collection system and returns the kiln to constitute the cycle of the kiln dust.