Abstract
We previously found that minute linear and cloud-shaped particles of mineral matter in coal were difficult to liberate from organic matter. Thus, quantitative information on the shape of mineral matter in coal is considered to be significant to the development of pulverization-ash removal processes. The present study proposes a new method to obtain quantitative data on the shape and size of mineral matter in coal using a common imaging tool, a photomicroscope, which can be used on-site easily. The mineral distribution in coal could be measured by distinguishing organic matter and mineral matter using luminance distribution curve obtained from gray scale images. As the shape index of mineral matter, the ratio of diameter maximum length to diameter was found to be appropriate. Samples of pulverized coal of different sizes were prepared. The effect of coal particle size, size of mineral particles in coal, and the shape index of minerals on mineral removal efficiency were evaluated by sink-float separation. The present indices were found to play significant role in mineral removal from coal.
