Enhanced ultrafine coal dewatering using flocculation filtration processes

Ultrafine coal (-150 mu m) can be effectively cleaned using advanced separa tion techniques such as column flotation, however, dewatering it to below 2 0 percent moisture level using the conventional dewatering techniques is di fficult. A comparative flocculation filtration study was performed for enha ncing dewatering of ultrafine coal using vacuum, hyperbaric, and centrifuga l filters. The cationic and anionic flocculants were added into the slurry individually or in combinations. Vacuum filtration results showed that use of flocculants increased filtrati on rate by several times and/or substantially reduced cake moisture. Combin ed use of anionic and cationic flocculants showed further improvement. Addi tion of flocculants significantly increased filtration rate of hyperbaric f iltration and reduced cake moisture in centrifugal filtration. Anionic floc culant was more effective in enhancing fine coal dewatering than cationic f locculant in vacuum filtration while cationic flocculant was more effective in high shear centrifugal filtration. A new approach on using flocculants in vacuum filtration is proposed for enhanced fine coal dewatering. (C) 200 0 Elsevier Science Ltd. All rights reserved.