Amenability to dry processing of high ash thermal coal using a pneumatic table

High ash thermal coal from India was used to conduct the dry processing of fine coal using a pneumatic table to evolve a techno-economically novel technique. The fine as-received sample having 55.2% ash was subjected to washability studies at variant densities from 1.4 to 2.2 to assess the amenability to separation. The experiments were conducted using a central composite design for assessing the interactive effects of the variable parameters of a pneumatic table on the product yield and ash content. The performance of the pneumatic table was analyzed in terms of clean coal yield, recovery of combustibles, separation efficiency (Esp) and useful heat value of clean coal. The combustibles of clean coal obtained through a single stage operation at 35% and 38.7% ash were 40% and 63% respectively. However, the two stage processing was more effective in reducing the ash content in the clean coal. The rougher concentrate generated at higher ash level was subsequently processed in different conditions at 35% ash level, and 58% combustibles could be recovered. Hence, two stage processing increases the combustibles by 18 units and the useful heat value of clean coal increases from 1190 kcal/kg to 3750 kcal/kg.