왕겨재의 분쇄특성에 관한 연구 = Grinding Characteristics of Rice Husk Ash

다국어 초록 (Multilingual Abstract)

This work was conducted to study the operating characteristics of a grinding system designed to obtain fine rice husk ash powder. To find better utilization of the rice husk, a valuable by-product from rice production, once the rice husk was combusted and the thermal energy was recovered from the furnace, the ash was fed and pulverized in the grinding system resulting a fine powder to be used as a supplementary adding material to the portland cement. The rice husk ash grinding system consisted of a high speed centrifugal fan for the preliminary coarse milling and a dry-type stirred ball mill for the subsequent fine grinding. For the coarse milling, the effects of feed rate (60, 180, 360 kg/h) and fan speed (3000, 4500, 6000rpm) on the mean particle size and the specific energy input were studied. Total grinding time (15, 30, 45 min), impeller speed (250, 500, 750 rpm), and mixed ratio (4.8, 7.9, 14.9) were three operating factors examined for the performance of a stirred ball mill used for the fine grinding of ash.
As the fan speed increased, the particle size decreased while the specific energy input increased for coarse milling of rice husk ash. With the stirred ball mill used in this study, the minimum attainable mean diameter of ash powder appeared to be 2μm. During the fine grinding of rice husk ash, the difference in specific surface area of powder showed an increase and the grinding energy efficiency decreased with the increase in total grinding time, impeller speed, and mixed ratio. For the operating conditions employed, the resulting mean diameter of fine ash powder, specific energy input, and grinding energy efficiency were in the range of 1.79~10.18μm,0.256~5.226kwh/kg, and 1.11 ~7.1m2/Wh, respectively. Grinding time of 30miin, impeller speed of 750rpm, and mixed ratio of 4.8 were chosen as the best operating conditions of the stirred ball mill for fine grinding. At these conditions, mean particle diameter of the fine ash, grinding energy efficiency, grinding throughput, and specific energy input were 2.73μm, 3.95m2/Wh, 0.25kg/h, and 1.22kWH/kg, respectively.