Timedependent Stability Implications for Two Seam Mining OCI

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Old Mines - New Regulations The Re-opening of the
Gordonsville, Elmwood, and Cumberland Mines Under
New DPM Regulations
12th U.S./North American Mine Ventilation
Symposium June 9-11, 2008 Reno, Nevada
USA Presented by Albert Adu-Acheampong Susan
Patton
AGAPITO ASSOCIATES, INC.
Mining Civil Engineers Geologists
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Presentation Outline

• Site Overview and Background
• Previous Work by Agapito Associates, Inc. (AAI)
• Future Mining Plans
• Basis for the Analysis
• Ventilation System Design
• Recommendations
• Startup Issues

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Site Overview
72 km (45 miles) East of Nashville
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Site Overview and Background

• The Gordonsville, Elmwood (GV/E) and Cumberland
  Mines were formerly owned by Pasminco
• The mines were last operated in 2003 and were
  decommissioned
• Currently owned by Strategic Resource Acquisition
  (SRA) and operated by Dynatec.
• The mines utilize a random room-and-pillar mining
  method to extract zinc underground

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Previous Work by AAI

• Pressure/quantity survey in 1996 for Savage Zinc,
  Inc.
• Developed and validated a computer network model
  for the mine

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Layout of the GV/E and Cumberland Complex
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Future MinePlans
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Basis for the Analysis

• 1996 pressure/quantity survey data
• Site Visit
• Information Received from Client
• Equipment selection table with utilization
• Production sequence with mine map
• Power cost
• Ventilation System Constraints
• Fans limited to less than 300 BHP
• Decline on intake air
• Plans to bore two new 3.7m (12 ft) diameter vent
  raises

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Ventilation System Design Quantity Estimation

• DPM
• New DPM exposure limit of 160TC µg/m3
• Equipment approved by MSHA has a nameplate with
  two pieces of information
• (a) Particulate Index (PI)Dilution air required
  to reduce the exhaust total DPM concentration to
  1000 µg/m3 (total carbon content 80)
• (b) gaseous ventilation rate

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Ventilation System Design Quantity Estimation

• DPM
• Sum of PI for the equipment specified for
  GV/E115.89 m3/s (245,550 cfm)
• Sum of PI for the equipment specified for the
  Cumberland Mine11.7 m3/s (23,650 cfm)
• By ratio (800?PI/Exposure Limit) equates to
  total volume of air required of 613.53 m3/s (1.3
  million cfm) and 58.5 m3/s (118,250 cfm)

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Ventilation System Design Analysis and Results

• Based on the quantity required
• Eight scenarios were analyzed for the GV/E Mine
  Complex
• The GV/E Mine Complex required 5 intakes and 7
  exhausts

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Ventilation System Design Analysis and Results

• Based on the quantity required
• Three scenarios were analyzed for the Cumberland
  Mine
• The Cumberland Mine required 2 intakes and 2
  exhausts

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Ventilation System Design Recommendations

• Startup settings
• Continued monitoring
• Practice contaminant monitoring
• Ventilation surveys recommended to correlate
  models

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Mine Ventilation Startup Issues

• Auxiliary system capacity
• Existing raises
• Managing equipment locations to limit exposures
• Rehabilitating shafts and raises
• Dewatering

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Acknowledgements

• The authors would like to thank SRA
• and Dynatec for initiating this project

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Questions ???
Albert Adu-Acheampong 715 Horizon Dr. Ste
340 Grand Junction, CO 81504 Tel 970
254-9392 Email aaadu_at_agapito.com