Oil Agglomeration of Coal Fines in Continuous Mode of Operation

Coal-oil agglomeration plays a vital role in addressing the ever increasing pollution due to coal utilization apart from minimizing coal-waste generation. Numerous studies were available on coal-oil agglomeration in batch mode; however, the process has been seldom investigated under continuous mode of operation. In the present study, an attempt has been made to examine the coal-oil agglomeration process under continuous mode of operation using high ash power grade coal procured from Jharkhand (India) with Karanja oil as agglomerant. The effectiveness of the process was estimated in terms of organic matter recovery (OMR) and ash rejection (AR). Preliminary experiments were performed under batch mode to optimize the process variables (oil dosage, agitation speed, agglomeration time, and coal particle size). Subsequently, the process was operated in continuous mode under these optimum conditions by varying the reactor residence time. In batch mode, a maximum OMR (78.09%) with significant AR (51.28%) was observed under the following optimized conditions: oil dosage (20% by wt of coal); agitation speed (1,500rpm); agglomeration time (120s); and coal particle size (+75-200 mu m). However, operation under continuous mode resulted in lower OMR (maximum 47.51%) with higher AR (70.38%), which can be attributed to inadequate contact between coal fines and oil.