The key for dust control of coal mine is to clarify the dust concentration distribution and sedimentation in different areas. Both similarity experiment and numerical simulation method have certain restrictions and ar...The key for dust control of coal mine is to clarify the dust concentration distribution and sedimentation in different areas. Both similarity experiment and numerical simulation method have certain restrictions and are quite different from the actual situation on site. In order to study the dust sedimentation regularity of coal mine in large mining height, “filter membrane method” is adopted in this paper, i.e., to dry and weigh the filter membrane before and after sampling, collect the dust of respirable zone on mining face and calculate the dust concentration based on a main airway of 100 m. The result shows that: A large amount of dust will be produced during coal mining, wherein the maximum dust concentration from 6 m upstream to 100 m downstream of coal cutter is 121 mg/m3</sup>, while the minimum dust concentration is 61 mg/m3</sup>;The dust concentration in return airway is reduced with the distance increases, while the dust concentration at the entrance is 91 mg/m3</sup>;A large amount of dust may fall from roof during section advancing and improves the dust concentration of hydraulic support in walking area obviously;The dust granularity of mining face and return airway is 0 - 100 μm, but the amount of respirable dust is higher than 80%, the larger the dust particle size, the higher the dust concentration. Besides, dust in small particle size can be suspended in air flow for longer, but that in large particle size may subside under the action of gravity;To reduce dust exposure, the mining position shall be located in the windward direction of advancing or coal cutter. This research can provide guidance for taking dust prevention measures of working face in large mining height.展开更多
Airborne rock dust poses serious long-term health effects to workers in mining and tunneling underground rock environments.When inhaled,respirable crystalline silica particles commonly found in quartz and other minera...Airborne rock dust poses serious long-term health effects to workers in mining and tunneling underground rock environments.When inhaled,respirable crystalline silica particles commonly found in quartz and other minerals will scar sensitive lung tissue and cause irreversible lung diseases.Characteristics such as concentration,type of mineral,particle size,and particle shape can harm workers to various extents.Therefore,this study characterizes airborne rock dust particles that are released from mechanically cutting rock.Laboratory full scale linear cutting tests on samples of potash rock were performed with radial picks to generate dust and were collected with various instruments,including Dorr-Oliver cyclones.Three stages of pick wear were tested:new,moderately worn,and severely worn.Comparisons between different stages of pick wear to dust concentration,size distribution,and particle shape characteristics are drawn from this preliminary study using analytical methods,field-emission scanning electron microscope image capture techniques,and laser diffraction.Although further testing needs to be conducted to make viable and concrete conclusions,a review of the test results reveals a strong tendency in generated airborne and deposited dust to be linked to the bit tip wear,which was influenced by tip surface area geometry,such as a sharp tip,blunt tip,or undulating sharp tips.The moderately worn pick,or the pick with the bluntest tip,in these experiments released the highest concentration of dust.The moderately worn(bluntest)pick also generated particle shapes with the highest aspect ratio compared to the other two picks.Additionally,in terms of the particle size distributions,all the picks generated airborne particle size mean values between 0.7 and 1.2µm in aerodynamic diameter.As for deposited particle size distributions,all the picks generated particles with the mode of particle aerodynamic diameter sizes at 13µm.In the end,the results of this preliminary study paired with future testing can confirm and eventually provide the basis for optimum bit management and maintenance systems to control airborne dust exposures.展开更多
文摘The key for dust control of coal mine is to clarify the dust concentration distribution and sedimentation in different areas. Both similarity experiment and numerical simulation method have certain restrictions and are quite different from the actual situation on site. In order to study the dust sedimentation regularity of coal mine in large mining height, “filter membrane method” is adopted in this paper, i.e., to dry and weigh the filter membrane before and after sampling, collect the dust of respirable zone on mining face and calculate the dust concentration based on a main airway of 100 m. The result shows that: A large amount of dust will be produced during coal mining, wherein the maximum dust concentration from 6 m upstream to 100 m downstream of coal cutter is 121 mg/m3</sup>, while the minimum dust concentration is 61 mg/m3</sup>;The dust concentration in return airway is reduced with the distance increases, while the dust concentration at the entrance is 91 mg/m3</sup>;A large amount of dust may fall from roof during section advancing and improves the dust concentration of hydraulic support in walking area obviously;The dust granularity of mining face and return airway is 0 - 100 μm, but the amount of respirable dust is higher than 80%, the larger the dust particle size, the higher the dust concentration. Besides, dust in small particle size can be suspended in air flow for longer, but that in large particle size may subside under the action of gravity;To reduce dust exposure, the mining position shall be located in the windward direction of advancing or coal cutter. This research can provide guidance for taking dust prevention measures of working face in large mining height.
文摘Airborne rock dust poses serious long-term health effects to workers in mining and tunneling underground rock environments.When inhaled,respirable crystalline silica particles commonly found in quartz and other minerals will scar sensitive lung tissue and cause irreversible lung diseases.Characteristics such as concentration,type of mineral,particle size,and particle shape can harm workers to various extents.Therefore,this study characterizes airborne rock dust particles that are released from mechanically cutting rock.Laboratory full scale linear cutting tests on samples of potash rock were performed with radial picks to generate dust and were collected with various instruments,including Dorr-Oliver cyclones.Three stages of pick wear were tested:new,moderately worn,and severely worn.Comparisons between different stages of pick wear to dust concentration,size distribution,and particle shape characteristics are drawn from this preliminary study using analytical methods,field-emission scanning electron microscope image capture techniques,and laser diffraction.Although further testing needs to be conducted to make viable and concrete conclusions,a review of the test results reveals a strong tendency in generated airborne and deposited dust to be linked to the bit tip wear,which was influenced by tip surface area geometry,such as a sharp tip,blunt tip,or undulating sharp tips.The moderately worn pick,or the pick with the bluntest tip,in these experiments released the highest concentration of dust.The moderately worn(bluntest)pick also generated particle shapes with the highest aspect ratio compared to the other two picks.Additionally,in terms of the particle size distributions,all the picks generated airborne particle size mean values between 0.7 and 1.2µm in aerodynamic diameter.As for deposited particle size distributions,all the picks generated particles with the mode of particle aerodynamic diameter sizes at 13µm.In the end,the results of this preliminary study paired with future testing can confirm and eventually provide the basis for optimum bit management and maintenance systems to control airborne dust exposures.
