Community Research and Development Information Service - CORDIS


This project investigates the factors which affect the nature and extent of size degradation of graded coals in transport systems used for industrial combustion plant. Fines generated by degradation commonly adversely affect combustion efficiency or cause handling difficulties. The proportion of fines generated is therefore used in this study as the main measure of degradation. Investigation of degradation in screw conveyors and elevators shows that even friable anthracite coals can be handled with negligible degradation if the machinery is correctly sized and designed. Specific recommendations are given for the design of screw conveyors. During lean phase pneumatic conveying, breakage is linked to particle kinetic energy; control of conveying velocity is essential, particularly on long straight pipelines. A rubber lined cyclonic reception unit was successfully demonstrated to prevent impact against walls on delivery. A simple laboratory compression test shows that very little breakage is due to compressive stress only. This also provides a means of comparing the susceptibility of coals to breakage during pneumatic conveying. Studies with an annular shear cell suggest that fines would be generated at slippage zones between static and moving coal within flat-bottomed silos discharging to a single point.

Additional information

Authors: BRITISH COAL CORPORATION, British Coal Corporation, Stoke Orchard, Cheltenham, Glos. GL52 4RZ (GB)
Bibliographic Reference: EUR 12361 EN (1989) MF, 77 pp., ECU 4, blow-up copy ECU 7.50
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