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A Review of Dust Control Techniques for LongwallsPresenter Joe DefibaughDate 6/11/13
│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Overview
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
A Review of Dust Control Techniques for Longwalls:
❧ Quick overview of current longwall dust control techniques and the limitations of these techniques
❧ Impact of future regulations for dust control in longwall mines
❧ Better ways to control respirable dust levels in the future
❧ New technologies for dust control going forward to improve the productivity of longwall mining
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Longwall System Dust Controls
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Roadway Controls Include:
❧ Attempt to limit travel on intake roadways during production shifts but this is hard to control due to maintenance requirements
❧ Continual application of water to roadways with water truck to keep dust levels low
❧ Dust introduced into the system needs to be as low as possible
❧ http://www.cdc.gov/niosh/mining/UserFiles/workshops/silicaMNM2010/4-Chekan-DustControlUG.pdf
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Beltway Controls Include:
❧ Sprays located on belt heads
❧ Sprays near the booster drive
❧ Scrapers located on the head and tail
❧ Any transition area in which dust is liberated needs to be addressed
❧ http://www.asgco.com/conveyor-products/secondary-conveyor-belt-cleaners/wash-box-belt-cleaning-system/
❧ http://www.asgco.com/conveyor-products/primary-conveyor-belt-cleaners/
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Stageloader Controls Include:
❧ Dust scrubbers used at stageloader to capture excess dust
❧ Sprays located at dust generation areas
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Top and bottom raceway sprays
Pneumatic atomising sprays in dust hood
Crusher Sprays – fed from cooling circuits
Draws from both Crusher and Dust Hood
│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
AFC Controls Include:
❧ Transition area sprays
❧ Use of water cooled motors on the stageloader and excess water is streamed onto conveyor
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Main gate Corner Venturi Sprays
Transmission cooling water used on Crusher water sprays
│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
AFC Controls Include:
❧ Water sprays to wet coal to suppress liberated coal dust
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Cooling water for lubrication and dust suppression exits here
Sprays in Inspection linepan top decks for lubrication and dust suppression
│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Mine Controls Include:
❧ High volume face ventilation– Keep dust along the face and not in walkway
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Shearer Controls Include:
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Drum Controls Include:
❧ Drum-mounted water spraysBit face flushing sprays – prevention by wetting coal
Bit back flushing sprays – frictional ignition & suppression
❧ Conduct bit maintenance every “x” passes dependent upon cutting conditions but a regular maintenance schedule should be established
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Shearer Body Controls Include:
❧ Splitter arm on head gate side onlyBelting to create barrier
❧ Ranging arm sprays
❧ Sloughing plates
❧ “Shearer-Clearer” sprays
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Powered Roof Support Controls Include:
❧ Automated sprays on canopy and undersideOptimum sequence can be developed to reduce dust
❧ Maintenance is key to keeping these sprays effective and operational
❧ Additional sprays available to reduce dust produced in other areas
Gob side spraysSide shield spraysWash down sprays (toes, links)
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Future Regulations Impact
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Future Regulations Impact:
❧ If respirable dust level drops from 2.0 mg/m³ to 1.0 mg/m³ using 1,217 MSHA dust samples taken in 2009 at the tailgate side operator and jack setter locations: Average = 1.15 mg/m³
122 samples > 2.0 mg/m³ or 10.0%195 samples > 1.7 mg/m³ or 16.0%271 samples > 1.5 mg/m³ or 23.3%628 samples > 1.0 mg/m³ or 51.6%
❧ These samples are at the bimonthly sample rate and could worsen if the rule changes to increase the sampling rate
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00.5
11.5
22.5
33.5
44.5
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Better Ways / New Technologies
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Other Opportunities:
Computational Fluid Dynamics (CFD) –to solve fluid flow scenarios
CFD to design optimized dust reduction systems
Full scale models can be expensive, CFD can be utilized to reduce the dust reduction options to be trialed
CFD results need to be verified with field testing
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Location of Cameras & light
Respirable Dust Reduction
❧ The placement of shearer and shield operators is the #1 contributor to dust levels
This has a dramatic effect to reduce respirable dust at the operator location
❧ Automation that can be “trusted” will help these operators stay in the proper location for reduced dust exposure
❧ In the future remote automation (man-less face) will help remove these operators from these hazardous areas
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Conclusion
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Conclusion:
❧ Dust cannot be eliminated only controlled
❧ No one particular control that makes a huge difference to the overall dust reduction effort
❧ Engineering controls work in conjunction to reduce respirable dust exposure at points throughout the system
❧ Maintaining the current controls is key in keeping dust levels in check
❧ CFD as a tool to test and improve current dust management
❧ Remote operation and automation will be the future to meet more stringent regulations
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
References:
❧ ASGCO Manufacturing, Inc.. (2012)ASGCO Complete Conveyor Solutions. Retrieved from http://www.asgco.com/conveyor-products/
❧ Chekan, G. (2011, November)Best Practices for Dust Control in Metal/Nonmetal Underground Mining. Retrieved fromhttp://www.cdc.gov/niosh/mining/UserFiles/workshops/silicaMNM2010/4-Chekan-DustControlUG.pdf
❧ Ren, T. X., & Balusu, R. (2007, June)ACARP Project C14036 Dust Control Technology Development for Longwall Faces - Shearer Scrubber Development. Retrieved from http://www.envirocon.com.au/papers/acarp_report_c14036.pdf
❧ U.S. Department of Labor - MSHA. (2010, October)Regulatory Economic Analysis Materials in Support of Proposed and Final Rules. Retrieved from http://www.msha.gov/rea.HTM
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│11 June 2013 │ Longwall Systems Dust ControlUnderground Mining
Thank You!
Questions & Comments?
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