| 摘要 |
A heavy medium low-specific gravity method for recovering coarse clean coal within a size range of about +28 m and fine clean coal and coal-bearing particles within a size range of -28 x Om from a raw coal feed wherein heavy medium is recovered as a substantially clean product which can be recycled in the heavy medium system. In the method a raw coal feed containing coal, shale and other impurities within a size range of about 3.81 cmx0 is mixed withi a heavy medium to produce a slurry of low specific gravity between about 1.27 and 1.70. The slurry is treated in at least one cyclone to separate an overflow product containing substantially all coal and coal-bearing particles from an underflow product containing all shale and sulfur-bearing rejects. The overflow product is treated on standard equipment to separate coarse coal from fine coal and heavy medium. The coarse coal is recovered as a usable product. The fine coal and heavy medium are separated from each other in a froth-flotation cell wherein fine coal is separated from the heavy medium and is recovered as a usable product. The substantially clean heavy medium is suitable for recycling to the heavy medium low specific gravity system. The cyclone underflow product is also treated on similar equipment to separate the coarse shale from fine coal, coal-bearing particles, fine shale and heavy medium. The coarse shale is wasted. The fine coal, coal-bearing particles, fine shale and heavy medium are separated from each other in a froth-flotation cell. The fine coal and coal-bearing particles are separated from the medium and fine shale and are recovered as a usable product. The substantially clean heavy medium is suitable for recycling to the heavy medium low specific gravity coal recovery system.
|
