Control of dust in underground coal mines is critical for mitigating both safety and health hazards.For decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effective...Control of dust in underground coal mines is critical for mitigating both safety and health hazards.For decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effectiveness of various dust control technologies in coal mines.Recent studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains(CACs)to reduce respirable dust in key operator positions.While detailed dust characterization was not a focus of such studies,this is a growing area of interest.Using preserved filter samples from three previous NIOSH studies,the current work aims to explore the effect of two different scrubbers(one wet and one dry)and a roof bolter CAC on respirable dust composition and particle size distribution.For this,the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive X-ray.Results indicate that dust composition was not appreciably affected by either scrubber or the CAC.However,the wet scrubber and CAC appeared to decrease the overall particle size distribution.Such an effect of the dry scrubber was not consistently observed,but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return air.Aside from the insights gained with respect to the three specific dust control case studies revisited here,this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.展开更多
In modern room and pillar coal mines,the coal is produced by continuous miner(CM)machines.The CM is used to mine the coal seam by continuously cutting at a vertical face.Depending on the seam thickness,quality,and geo...In modern room and pillar coal mines,the coal is produced by continuous miner(CM)machines.The CM is used to mine the coal seam by continuously cutting at a vertical face.Depending on the seam thickness,quality,and geotechnical properties,some roof,floor,or interburden rock is often cut along with coal.While CMs can be highly efficient in terms of production rates,they can also generate high concentrations of dust.Dust poses both safety(i.e.,explosibility)and respiratory health hazards.Previous research has generally indicated that CM cutting in rock yields much more respirable dust than cutting in coal.Although in-mine studies that directly evaluate this trend have not been reported,understanding relative dust generation from different geologic strata could have important implications.In many mines,for instance,the rock is the primary source of respirable silica and silicates,which can be especially hazardous.To mitigate dust generated by the CM,mines use a variety of controls including ventilation,on-board scrubber systems,and water sprays.However,the relative effects of controls on dust generated from different strata have also not been widely investigated.In this field study,respirable dust sampling was conducted in the intake and return airways of an active CM during periods when the cutting was targeted either primarily at the coal seam(bottom cut)or primarily at the roof rock(top cut)in a standard entry.Results indicated that CM cutting in rock strata generated somewhat finer particles and respirable dust concentrations that were 2.1-26 times higher than cutting in coal strata,although the coal height being cut was about 2.2-2.9 times greater than the rock height.Additionally,the analysis of dust mineralogy generally showed a mix of both carbonaceous(coal)and mineral particles regardless of the target strata.Furthermore,the study was designed to evaluate the effects of two typical combinations of CM scrubber and ventilation conditions,and increased pressure and volume through the CM water sprays.In general,operation of the scrubber tended to yield lower and somewhat finer respirable dust concentrations,irrespective of the strata the CM was targeting.Increased water spray pressure and volume sometimes appeared to reduce the respirable dust concentration when the CM was targeting the roof rock,but no effect could be discerned when the CM was targeting the coal seam.展开更多
基金CDC/NIOSH for funding this research(75D30119C05529)。
文摘Control of dust in underground coal mines is critical for mitigating both safety and health hazards.For decades,the National Institute of Occupational Safety and Health(NIOSH)has led research to evaluate the effectiveness of various dust control technologies in coal mines.Recent studies have included the evaluation of auxiliary scrubbers to reduce respirable dust downstream of active mining and the use of canopy air curtains(CACs)to reduce respirable dust in key operator positions.While detailed dust characterization was not a focus of such studies,this is a growing area of interest.Using preserved filter samples from three previous NIOSH studies,the current work aims to explore the effect of two different scrubbers(one wet and one dry)and a roof bolter CAC on respirable dust composition and particle size distribution.For this,the preserved filter samples were analyzed by thermogravimetric analysis and/or scanning electron microscopy with energy dispersive X-ray.Results indicate that dust composition was not appreciably affected by either scrubber or the CAC.However,the wet scrubber and CAC appeared to decrease the overall particle size distribution.Such an effect of the dry scrubber was not consistently observed,but this is probably related to the particular sampling location downstream of the scrubber which allowed for significant mixing of the scrubber exhaust and other return air.Aside from the insights gained with respect to the three specific dust control case studies revisited here,this work demonstrates the value of preserved dust samples for follow-up investigation more broadly.
文摘In modern room and pillar coal mines,the coal is produced by continuous miner(CM)machines.The CM is used to mine the coal seam by continuously cutting at a vertical face.Depending on the seam thickness,quality,and geotechnical properties,some roof,floor,or interburden rock is often cut along with coal.While CMs can be highly efficient in terms of production rates,they can also generate high concentrations of dust.Dust poses both safety(i.e.,explosibility)and respiratory health hazards.Previous research has generally indicated that CM cutting in rock yields much more respirable dust than cutting in coal.Although in-mine studies that directly evaluate this trend have not been reported,understanding relative dust generation from different geologic strata could have important implications.In many mines,for instance,the rock is the primary source of respirable silica and silicates,which can be especially hazardous.To mitigate dust generated by the CM,mines use a variety of controls including ventilation,on-board scrubber systems,and water sprays.However,the relative effects of controls on dust generated from different strata have also not been widely investigated.In this field study,respirable dust sampling was conducted in the intake and return airways of an active CM during periods when the cutting was targeted either primarily at the coal seam(bottom cut)or primarily at the roof rock(top cut)in a standard entry.Results indicated that CM cutting in rock strata generated somewhat finer particles and respirable dust concentrations that were 2.1-26 times higher than cutting in coal strata,although the coal height being cut was about 2.2-2.9 times greater than the rock height.Additionally,the analysis of dust mineralogy generally showed a mix of both carbonaceous(coal)and mineral particles regardless of the target strata.Furthermore,the study was designed to evaluate the effects of two typical combinations of CM scrubber and ventilation conditions,and increased pressure and volume through the CM water sprays.In general,operation of the scrubber tended to yield lower and somewhat finer respirable dust concentrations,irrespective of the strata the CM was targeting.Increased water spray pressure and volume sometimes appeared to reduce the respirable dust concentration when the CM was targeting the roof rock,but no effect could be discerned when the CM was targeting the coal seam.
