A comparison of a directional spray system and a flooded-bed scrubber for controlling respirable dust exposures and face gas concentrations

摘要

A continuous mining machine was operated with either a directional spray system (sprayfan) or a flooded-bed dust scrubber. A series of laboratory tests examined the impacts of water pressure and curtain setback distance on respirable dust concentrations and tracer gas levels. Face ventilation was provided by an exhaust curtain. Several combinations of external and underboom sprays also were evaluated with the scrubber. Dust concentrations were measured at locations representing the mining machine operator and in the return airway, while tracer gas levels were measured around the cutting head. When testing with the sprayfan-equipped mining machine, changes in water pressure and setback distance significantly affected miner operator dust levels. Return dust levels varied only slightly. With the dust scrubber, changes in curtain setback impacted miner operator dust concentrations. Use of an external spray manifold significantly increased both operator and return dust levels, apparently by pushing dust beyond reach of the scrubber inlets. Tracer gas levels around the cutting head were affected by changes in sprayfan water pressure. Variations in curtain setback distance affected gas levels on the off-curtain side of the cutting head. With use of the dust scrubber, cutting head gas levels were affected mostly by changes in water pressure, setback distance, and use of the external and underboom sprays. The scrubber was more effective than the sprayfan for controlling respirable dust levels. The sprayfan effectively controlled gas on the off-curtain side of the cutting head, although the scrubber plus the external sprays also provided good control of gas levels in this area. This same spray configuration also adequately controlled gas on the curtain side of the cutting head.