Development of technology for separating low grade coals from raw coals byfluidized bed of dry heavy medium

A raw coal consists of two components, light coals containing combustibles and heavy coals containing ashes. The heavy coals raise transportation expe nses of the raw coals, and the costs of ash disposal after combustion. Sulf ur contents in the heavy coals become a cause of SOx generation. In this st udy, a process of separating the heavy coals from the raw coals by a fluidi zed bed of dry heavy medium is developed. The principle of separation using specific gravity, that is, an object whose density is smaller than the app arent density of the fluidized bed floats and a heavier one settles, and re moving mechanisms of float-coals and sink-coals are employed for the proces s. Density distributions and ash contents of Datong, Taiheiyo and Yanzhou raw coals are measured. As a result of separating the heavy coals from these ra w coals by a process with calcium carbonate for the dry heavy medium, Newto ns' efficiency and combustible recovery become up to 90%, and ash recovery becomes 50 similar to 80%. The effectiveness of the process and the possibi lity of practical utilization are proven by good results.