DPM Dispersion Study Using CFD for Underground MetalNonmetal Mines

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DPM Dispersion Study Using CFD for Underground
Metal/Nonmetal Mines
12th Mine Ventilation Symposium Reno, Nevada USA

• Yi Zheng yzz59_at_mst.edu
• Jerry C. Tien tien_at_mst.edu
• Mining Nuclear Engineering Department
• Missouri University of Science Technology

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OUTLINE

• DPM Regulation for U/G M/NM Mines
• DPM Situation and Control Strategies
• Simulation Method and Assumption
• Main Airflow Simulation
• Single Heading Airflow-Blowing Exhausting
• Results and Discussion
• Summary and Conclusions

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DPM Regulation for U/G M/NM Mines

• Diesel-powered equipments are widely used in U.S.
  U/G M/NM mines for the power, reliability, easy
  to operate and repair, fuel efficiency,
  durability, etc.
• However, it can cause health problems.
• Therefore, beginning May 20, 2008, 160 µg/m3 of
  TC or less is required by MSHA.

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DPM Situation

• 2001 - 2002, MSHA 358 valid samples from 30
  mines
• 488 µg/m3 of TC for metal mines, 372 µg/m3 of
  TC for stone mines
• 2002 - 2003, MSHA 1,194 valid DPM from 183 mines
• 354 µg/m3 of TC for metal mines, 235 µg/m3 for
  stone mines
• 2003 2006, MSHA 1,798 valid samples from all
  mines covered by the regulation
• 64 (1,151) exceeded 160 µg/m3 of TC

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DPM Control Strategies

• MSHA six available DPM control strategies
• Modern low-DPM emission diesel engines
  upgrade ventilation system environmental cabs
  work practices alternative fuels DPM filters.
• Ventilation is a critical one
• 1 gram of DPM can pollute 6,250 m3 of space to
  final limit if without ventilation.

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Simulation Method and Assumption

• Simulation Method Computational Fluid Dynamics
• Program FLUENT
• Assumption
• DPM movement will be entirely dictated by the
  airflow patterns

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Main Airflow Simulation
South section of an underground metal mine
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Main Airflow Simulationwithout Stoppings
Path of small particles without stoppings
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Main Airflow Simulationwith Stoppings
Stoppings to guide the air
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Main Airflow Simulationwith Stoppings
Path of small particles with stoppings
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Main Airflow Simulationwith Stoppings
Three types of working face with ventilation
problems
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Main Airflow Simulationwith Stoppings
Main airflow velocity near the dead end opening
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Single Heading Airflow Simulation
Single heading
Main entry
Layout of a single heading with blower fan and
tubing
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Single Heading Airflow Simulation
Layout of a single heading with exhaust fan and
tubing
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Single Heading Airflow Simulation
CAT 725 articulated truck
CAT 980H wheel loader
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Results and DiscussionBlowing System
Airflow velocity of the main entry and single
heading
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Results and DiscussionBlowing System
Airflow velocity in the face area
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Results and DiscussionBlowing System
Exhaust airflow pattern in the face area
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Results and DiscussionBlowing System
DPM concentration dispersion in the face
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Results and DiscussionExhausting System
Airflow velocity of the main entry and single
heading
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Results and DiscussionExhausting System
Airflow velocity in the face area
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Results and DiscussionExhausting System
Exhaust airflow pattern in the face area
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Results and DiscussionExhausting System
DPM concentration dispersion in the face
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Summary and Conclusions

• 1. CFD method can be used to simulate the
  airflow patterns for the entire mine or for a
  part of it. Areas with poor ventilation can be
  identified and local ventilation control measures
  designed and evaluated.
• 2. Single heading face usually has the worst
  working condition in underground mines. Local
  ventilation facility is needed to improve the
  situation.
• 3. In a single heading face, loader driver is
  working in a higher DPM environment for both
  blowing and exhausting systems. More work need to
  be done to meet the regulation.

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Summary and Conclusions

• 4. DPM is distributed in a much smaller space in
  a blowing face ventilation system than in an
  exhausting face system, which means high air
  velocity is more effective than quantity to
  control DPM.
• 5. In the near future, a validation experiment is
  planed to take out. After that, a single
  measurement in the face (near the exhaust pipe)
  can give the DPM concentration distribution for
  the whole face area.

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Thank You!