SAMPLING SEQUENCE

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Mining Department
Planning to meet the required DPM concentration
levels in underground mines a calibration model
Presented by Kwabena Osei-Boakye Newmomt
Mining Company (Leeville Mine, Carlin, Nevada)
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Outline
Mining Department

• Objectives
• Funding
• Motivation
• Meikle mine
• Methodology
• Instrumentation
• Approach Strategy
• Ambient Air Sampling
• Activity-based Ambient Air Sampling
• Results Discussions
• Conclusions

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Objectives
Mining Department

• To provide u/g mines with a means to quickly
  quantify ambient air DPM concentrations in u/g
• workplaces.
• To develop a DPM planning strategy/tool to aid
  mine
• planning to ensure that miners are not
  over-exposed beyond the legal DPM limits.

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Funding
Mining Department
The Barrick Goldstrike Meikle Mine funded the
study to understand the extent and nature of DPM
issues within its u/g environment strategies
for mitigation to stay in compliance. This
presentation highlights one of the strategies
being used by the mine as a planning tool to
evaluate and manage DPM conditions.
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Motivation
Mining Department
The standard NIOSH 5040 method for compliance
evaluation of DPM has an inherent time lag of
about one week for laboratory processing of
sample results. During which time exposure levels
could potentially exceed the regulated limit (160
TC ug/m3) and miners health could be affected
defeating the prime aim of the Rule.
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Motivation
Mining Department
Therefore, providing the u/g mines with a quicker
means of quantifying DPM conditions in real-time,
will enable them to efficiently and effectively
manage DPM levels to ensure compliance with the
regulated limit and the much needed health and
safety of miners.
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Meikle Mine
Mining Department
Location Near Elko, Nevada Access 2 Intake
Vertical Shafts A Decline Ventilation
2,000,000 cfm (Intake Exhaust)
Inter-connecting Production zones Two mining
methods Long-hole Open Stoping
Drift-and-Fill Production rate 600k oz/yr Two
12-hr shifts/day Appox. 100 miners per
shift Miners carry respirators (P100) while u/g
they can also smoke
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Meikle Mine
Mining Department
Diesel equipment fleet Approx. 160 pieces Hp
ranging 22 (Utility) to 510 (Cat trucks) Total
Mine diesel equipment Hp Approx. 24, 000
hp Total Mine DPM contribution 2.1
kg/operating-hr
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Instrumentation
Mining Department
NIOSH 5040 Unit MSHA standard instrument/method
for compliance determination
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NIOSH 5040 Unit
Mining Department

• Has a time lag ( 1wk) to obtain Lab results to
  determine exposure During this time lag, miners
  could be exposed unacceptable DPM levels
• Reports only TWA values No mini or maxi values
  or trend of events (Graph)
• Quite expensive to personally monitor each miner
• Inconvenient to don/wear U/g safety
• MSHA might sample once a quarter in selected
  areas not quite effective and representative to
  quantify exposure due to operational changes in
  u/g mining (if the health of miners is the
  objective)

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Instrumentation
Mining Department
TSI DustTrak Unit Uses a 90 deg. light
scattering principles of aerosol to measure mass
concentration of the aerosol (mg/m3) in real-time
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DustTrak Output
Mining Department
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DustTrak Unit
Mining Department

• Real-time instantaneous output to quantify DPM
  leading to fast identification of problem areas
• Can be used to quantify baseline DPM in a series
  ventilation system
• Continuous, unattended ambient air sampling
• May require fewer units at vantage locations for
• mine-wide survey
• Can be fed into remote PC systems, and alarm
• levels set to alert miners of potential danger

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Strategy Approach
Mining Department
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Ambient Air Sampling
Mining Department

• Sampling carried out using two 5040 DustTrak
  in a location (picture)
• Results of 87 samples (from 31 locations) sent
  for analysis of Total Carbon (TC), Organic Carbon
  (OC), and Elemental Carbon (EC)

DT
5040
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Ambient Air Sampling
Mining Department
Sampling locations Main equipment access ramps,
workshops, and air courses where Series
ventilation systems are practiced to get baseline
DPM levels before the air is reused.
Ramp
W/shop
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Activity-based Sampling
Mining Department
Mining activity-based samplings were also
conducted. These included Jamming, combined
Loading and Hauling in isolated zones, Hauling
and Shortcreting.
Jammer
Mucker

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Activity-based Sampling Strategy
Mining Department
Thru Ventilation Layout
Midstream
Downstream
Upstream
Fresh Air
Exhaust
Equipment operating zone
Exposure
Mining activity area
Sampling stations
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Activity-based Sampling Strategy
Mining Department
Dead-End Layout
Fresh Air
Equipment operating zone
Fan
Exhaust
Exposure
Mining activity area
Exposure
Sampling stations
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DPM Model - Formulation
Mining Department
Fresh Air Q (cfm), A
DPM Control Box
DPM, Exposure X (ug/m3)
k conversion factor (588,583) Steady state
conditions
Sampling stations
Engine data Emission rate, e (g/hp-hr), Horsepowe
r, Hp
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Results Discussions
Mining Department
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Results Regression Analysis
Mining Department
TC OC EC
TC 1.3 x EC
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Regression Equation
Mining Department

• Higher correlation coeff. (R2 97 N 24)
• For 88 of the results, TC derived from EC were
• less than or equal to the sum of OC and EC
• MSHA uses the lower of the two TCs to determine
• Compliance
• TC based only on EC yields a more accurate
  result,
• since EC is a good indicator and a major part
• (surrogate) of DPM (Noll, et al., 2007). Such TC
  results
• are free from OC interferences.

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Testing of Model Equation
Mining Department
Validation samples taken from another mine
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Final Model
Mining Department
Predictive Model
Can be used for instant estimation and management
of ambient DPM conditions in U/g workplaces.
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Error Analysis
Mining Department

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Conclusions
Mining Department

• The DustTrak real-time aerosol monitor for
  ambient air sampling could be used in place of
  the MSHA compliance instrument for measurement
  DPM (TC). Strong correlation (R2 96) and
  percent error of 23.
• The calibration equation TC5040 0.53DT 10.2
  makes it possible to continuously monitor and
  manage DPM conditions in u/g workplaces.

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Mining Department
Thanks for the Attention
Questions????