Coal cleaning by counter-current fluidized cascade

CIM Bulletin, Vol. 75, No. 839, 1982

J.M. BEECKMANS and M. GORANSSON, Faculty of Engineering Science, University of Western Ontario, London, Ontario, S.G BUTCHER, Coal Mining Research Centre, University of Alberta Campus, Edmonton, Alberta

The counter-current fluidized cascade is a novel and potentially efficient pneumatic gravity separation device. Data are presented on over 150 runs of cleaning Alberta thermal coals, covering several size ranges. The coarser sizes of coal were processed in admixture with afluidizing medium consisting of 0.5-by 0.1-mm hematite (or magnetite) and limestone particles. The partition curves for coal particles larger than about 3 mm, mixed with fluidizing medium, showed that the sharpness of separation achievable with the cascade approaches that of wet heavy medium processes, whereas with particles in the size range of 3 by 0.6 mm the sharpness of separation was comparable to that of a Baumjig. Useful cleaning was also achieved with particles smaller than 0.6 mm. Throughput rates of up to 11 tonnes per metre width of cascade per hour were achieved, with no indication ofa deterioration in performance.
Keywords: Coal processing, Coal cleaning, Counter-current fluidized cascades, Gravity separation, Alberta coals, Fluidization, Reflux ratios, Partition curves.