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Validation of the Ventgraph Program for use in Metal/Non-Metal Mines

Validation of the Ventgraph Program for use in Metal/Non-Metal Mines. Christopher Pritchard MS P.E. Mining Engineer NIOSH OMSHR Spokane, WA. Summary. Introduction Description of 1972 Sunshine Mine and Fire Event Recreating the ventilation network Modeling network and mine fire

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Validation of the Ventgraph Program for use in Metal/Non-Metal Mines

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  1. Validation of the Ventgraph Program for use in Metal/Non-Metal Mines Christopher Pritchard MS P.E. Mining Engineer NIOSH OMSHR Spokane, WA

  2. Summary • Introduction • Description of 1972 Sunshine Mine and Fire Event • Recreating the ventilation network • Modeling network and mine fire • Model verification • “What If” Scenarios • Summary and Conclusions

  3. Introduction • NIOSH Research Plan - 2008 • Reduce incidents and severity of fires in M/NM Mines • Increase understanding of products of combustion • Improve ventilation and escape planning • Investigate and choose ventilation software • Verify by using actual M/NM mine fire incident

  4. Ventilation Software Requirements • Mine Fire simulation capabilities • Real time • Non-compressible flow • NVP • Graphics • Choice: Ventgraph for Windows

  5. Fire: 1972 Sunshine Mine • Historically significant • Deep • Complicated ventilation system • Compressed air injection • Multiple fans • Drastic changes to ventilation system

  6. Previous Sunshine Work: • 1977 USBM Report: Hall/Ramani/Greuer • Network model only • Semi NVP • No fire • No contaminants • No graphics

  7. Sunshine Ventilation System

  8. 1972 Fire Event • 11:40 am Smoke detected 3700L @ No. 10 Shaft • 12:00 Mine evacuation begun by 3100L route, surface notified, 3700L fire door closed at Jewell Shaft • 12:45 last survivors hoisted to 3100L @10 SH, 1:00 last hoist run. • 1:15 No. 12 SH cover removed

  9. Fire and Evacuation Sequence

  10. Sunshine Pictures Jewell Shaft entrance Workings

  11. Sunshine Pictures Stope 10 Shaft Hoist at 3100 Level

  12. Sunshine Pictures No. 8 Shop area – smoke detected “Blue Room” 3700 Level

  13. Sunshine Pictures 3700 Level 910R fire site Fire Site in raise

  14. Modeling Process • Airway data from 1977 USBM report • Scale airways from JW Andrews Sunshine maps • Temperature data from USBM vent survey – Fall, 1971 • Barometric data from mine elevations

  15. Modeling Development • Initial run – 1.6% accuracy with USBM • Fire location – 910 Raise between 3100 and 3700 level • Bulkhead failure sequence • Problem with 3400 booster fan, redo with fan curve, 3.3% accuracy

  16. Calibrate Model to Fire Events • Key events: • 11:35 am Smoke 3700 level • 12:00 smoke observed at surface • 12:10 smoke leaks into 3100 level

  17. Fire Model Events • Fire sequence model: • 11:05 am wood fire 910R, 65m long, ramp up time 5 minutes to Level 10 • 11:10 fire to 100m, 910R Bulkhead partially failed, 08 Shop door open • 11:15 fire to 200m, 910R BH further failure • 11:20 fire constant, 910R BH wide open

  18. Ventgraph Output Smoke at approximate time of discovery 11:40 am

  19. Ventgraph Output Local Detail of Fire Area – CO Levels at 11:40 am

  20. Verification • Model - good correlation to observed smoke arrival times • CO levels correlate well to escaping miner behavior • Results of model give confidence to analyzing alternatives • Run “What-If” Scenarios

  21. What-If Scenarios • Turn off 3400 Level Booster Fans • Problem with implementation of task • “What-If”: Stop fan 12:35 pm • Clears most 3100 roadway in 15 min • CO still high at 3100L hoist for 80 min • Did not effect lower mine CO levels • Would more 12:45 cage miners survive? • Allow rescuers to reach 3100L hoist more quickly?

  22. What-If Scenarios • Jewell Fire Door Closure Sequence • Supervisors underground made best decision – close 3700L door. • Close 3100L door – evacuating miners perish, lower levels may survive longer • Best option - leave both doors open and shut down 3400L booster fans

  23. What-If Scenarios • Opening No. 12 Shaft cover earlier • Slight improvement in airflow to 4800L: 0.9 – 2.1 m3/s • Essentially no difference to any other area of the mine

  24. What-If Scenarios • Placement of bulkheads • Aid fire fighting • Simulation “short term” accurate • Fire can endanger mine infrastructure • Planning may minimize damage • Sunshine: no combo of booster/doors works • Stopping needed to be installed inby 910R (and fire) to be effective

  25. Summary/Conclusions • Ventgraph validated in Sunshine Scenario • NVP • Multiple fans • Leakage • Recirculation • CO levels • Issues/Problems: • Ventgraph fire “Intensity Levels” • Booster fan flow deviation w/USBM model

  26. Summary/Conclusions • 3400 Level booster fan decision • Contributed to 1977 MSHA ACT • Valuable modeling/training tool • Use before and during event Survivors Tom Wilkinson and Ron Flory

  27. NIOSH - OMSHRSpokane Questions or Comments? CPritchard@cdc.gov 509-354-8021

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