Efficient Recovery of Combustibles From Coking Coal Fines

The processing of three Indian coking coal fines with feed ash values of 25.12% (S1), 22.97% (S2), and 30.38% (S3) was studied. Substantial improvement in the overall recovery of combustible could be obtained by splitting sample S1, exhibiting good washability but poor release behavior, into a coarser and a finer fraction and treating them by gravity and Jameson cell flotation, respectively. Sample S2 had over 70% of the material below 100 µm and had excellent release characteristics. The Jameson cell flotation indeed resulted in very high recovery of combustibles at the desired target ash values and split processing was not required for this sample. The floatability and washability characteristics of sample S3 indicated that gravity-based methods might improve combustible recovery in terms of theoretical yield at the desired product ash values. A combination of spiral concentration of the coarser fraction and froth flotation of the finer fraction using a Jameson cell showed some improvement in the combustible recovery of this sample. It was established in this study that if the floatability is poor or moderate, then split processing improves coal cleaning performance. Flotation alone may be recommended only when samples exhibit excellent floatability.