Date of Award
Doctor of Philosophy
A dry method of coal beneficiation achieved by triboelectrification in a fluidized bed and separation in an electrostatic field has been investigated at The University of Western Ontario for a considerable period of time. This study was undertaken to extend this method from batch to continuous operation and to examine the feasibility of improving the separation by multi-stage operation. In analogy with froth flotation using chemical agents to enlarge the differences in hydrophobicity, the feasibility of enlarging the differences in work function of coal components to improve the separation was also investigated.;A new apparatus for electrostatic separation was designed and built for continuous operation and for convenience of chemical surface conditioning. A high volatile bituminous B coal having ash and sulfur contents of 13.3% and 0.21% respectively was used in the separation. The optimized parameters for the separations were experimentally determined. The effect of conditioning agents having different physical and chemical properties on the efficiency of separation was investigated.;Continuous runs of up to 8 hours showed that the method can be used in continuous operation. For single stage separations, the separation index was 6.4. In two-stage operation, the separation index doubled so that with the same coal recovery the ash content in coal rich fraction decreased from 10% to 6.5% while the ash content in ash rich fraction increased from 15% to 20%.;The results from chemical conditioning show that of the agents tested, acetone is the best for separation of ash forming components. On the other hand, for maceral separation, xylene is the best agent. The vitrinite content in the coal rich fraction increased by 2% over the separation obtained with untreated coal.;Long separation runs have demonstrated the promise of continuous operation of this coal beneficiation method. The two-stage separation has brought the method closer to coal cleaning practice since multi-stage processes can be designed to meet specific product targets. Chemical agents do improve electrostatic coal beneficiation and different agents have been shown to have different effects on beneficiation.
Zhou, Gongguo, "Continuous Electrostatic Beneficiation And Surface Conditioning Of Coal" (1986). Digitized Theses. 1567.