Effects of vacuum filtration parameters on ultrafine coal dewatering

Coal fines (-0.6 mm) are often cleaned using wet separation processes such as froth flotation. Dewatering of clean coal slurry is essential for marketing the product and reducing the transportation cost. Vacuum filtration is one of the most widely used processes for fine coal dewatering. However, the filter cake often contains more than 20% moisture demanded by the coal industry. The present study was undertaken to better understand ultrafine coal (-0.15 mm) dewatering process using vacuum filtration by evaluating several important but often overlooked process parameters. A continuous filter leaf dewatering system and a small-scale drum filter were employed to investigate effects of cake formation time, cake drying time, flocculant conditioning time, feed size distribution, slurry agitation intensity etc. Results have shown that ultrafine coal dewatering performance evaluated by cake moisture, solids throughput etc., is strongly dependent on these parameters. Enhanced ultrafine coal dewatering can be achieved by optimizing these process variables.