Potential of Air Dense Medium Fluidized Bed Separation of Mineral Matter for Mercury Rejection from Alberta Sub-Bituminous Coal

In this study, three basic conditions for efficient dry separation of mineral matter from coal by an air dense medium fluidized bed (ADMFB) separator were assessed. The optimal fluidization air velocity for ADMFB separation was found to be insensitive to particle sizes of feed examined. The suitability of using an ADMFB separation to co-reject mercury with mineral matter was demonstrated. A strong linear relationship between mercury content and mineral matter content was confirmed for two of the three actively mined seams of this sub-bituminous coal. Following ADMFB separation, the linear fit of mercury rejection and ash rejection led to a coefficient of determination ranging from 0.98 to 0.86. In one of the coal seams studied, a mercury rejection of 58% and a mineral matter rejection of 60% were achievable at a total combustible recovery of 87% at optimized fluidization air velocity.