Dewatering ultrafine clean coal in a T. H. filter press

This study demonstrates a low-cost, high-efficiency filter press technology for dewatering minus 150 m column flotation clean coal products from two coal mines. Pilot-scale in-plant demonstration of this technology at these two locations provided stable, trouble-free operation while achieving an excellent dewatering performance at a high throughput. At one location, filter cakes with residual total moisture contents in the 20-22% range were achieved. At the other location 25-27% residual total moisture contents were achieved. At the second location, lower cake moisture content in the range of 21-25% was achieved with the use of appropriate dewatering aids. For difficult to dewater coals with higher clay contents, the innovative use of hot water during the filtration process was found to reduce cake moisture content by two to three percentage points over the baseline conditions. Engineering economic evaluations indicated that a fine coal product can be produced using column flotation and the filter press at a cost of $5.95/t (dry basis) for one mine. With appropriate blending strategies, annual profitability can be shown to increase by $0.9 million ($US) for this 1.8 Mt/year mine. For the second 2.4 Mt/year mine, annual profitability was projected to increase by $2.5 million ($US).