Extraction drums and air curtains for integrated control of dust and methane on mining machines.
Ford-VH; Brierley-T; Hole-BJ
NIOSH 1990 Sep:46-51
Control technologies for simultaneously controlling dust and methane on mining machines in the United Kingdom (UK) were described. A dust extraction drum was developed for longwall shearers and air curtains for use in ventilated drivage equipment. The extraction drum consisted of 9 to 12 dust capture tubes built into the drum barrel. Dusty air was drawn in from the cutting zone, cleaned by sprays of water released from hollow cone wear resistant nozzles inside the tubes, and blown out at the goaf side, from where it was turned back into the cutting zone along with the water spray and debris by an angle deflector plate fitted to the gear head. A portion of the air flow was fresh air that could be used to dilute methane. Field tests in which the extraction drums were installed on a variety of shearers in underground mining operations have shown dust reductions on the order of 40 to 80%. In a laboratory test using a simulated coal face the air flow diluted the methane to the extent that frictional ignition did not occur until a methane emission rate of 15 liters per second (l/sec) was reached. A methane emission rate of 15l/sec is well above the emission rates of most coal faces in the UK. The air curtain system directed sheets of fast moving air from the top and side of the machine body into areas where air velocities were low and dust tended to back up. The air curtains were produced from 100 millimeter diameter steel tubes into which air was fed at pressures of 0.75 to 2.0 kilopascals. Total air flow ranged from 0.15 to 0.30 cubic meter per second depending on machine type. The air curtain reduced dust exposures to the operator by at least 70% in underground tests. Laboratory tests showed that the air curtains directed air into the roof at velocities well above the 1 meter per second needed for dispersing methane layers.
Coal-mining; Dust-suppression; Coal-dust; Mine-gases; Control-technology; Mining-equipment; Equipment-design; Equipment-reliability; Safety-research; Air-flow;
Control Technology and Personal Protective Equipment; Research Tools and Approaches; Control-technology;
Proceedings of the VIIth International Pneumoconioses Conference