Dust Control Training Program for Underground Personnel

Research Team MembersDr. Y. P. Chugh, Harrold Gurley, John Pulliam

Southern Illinois University Carbondale

Illinois Mining Institute August 26, 2015

Project ManagerDr. Joseph Hirschi

Illinois Clean Coal Institute

Training – It Must Be Interesting…..

Dukette and Cornish (2009): • Adults can sustain attention for about 20 minutes. • Short-term response to the stimulus that attracts attention is

only eight seconds.

Conclusion: I only have 8 seconds to get your attention, and if the information being presented takes more than 20 minutes, I’ve lost you.

New Dust Regulations

Effective February 1, 2016 • DOs, ODOs, and Part 90 Miners must be sampled quarterly with a Continuous

Personal Dust Monitor (CPDM) • 15 valid representative samples collected on consecutive normal production shifts

required from each DO and ODO every calendar quarter. ODOs shall be sampled after DOs are completed and, if more than one type of ODO is present on the MMU, each is sampled during separate time periods

• 5 valid representative samples on consecutive work days from each Part 90 miner required each calendar quarter

• District Manager may require additional groups of 15 valid representative samples when information indicates the operator has not followed the approved ventilation plan for an MMU

Effective August 1, 2016 • Respirable coal mine dust standard for underground and surface - 1.5 mg/m3 • For Part 90 Miners and Intake Air - 0.5 mg/m3

MSHA Dust Training Mandates –What miners are required to know?

• MSHA – “Dust Sweep” that began Dec. 7, 2009 placed emphasis on respirable dust control.

• From MSHA – “Respirable Dust Control for Miners and Mine Operators” (Health Hazard Information Sheet 41)

Train miners, at least annually, on: 1) Health hazards of respirable coal mine dust 2) Purpose and importance of effective dust sampling and dust controls 3) Mandatory health standards applicable to their particular operation 4) Health provisions of the Federal Mine Safety and Health Act 5) Dust control portion of the approved ventilation plan 6) Importance of participating in the NIOSH X-ray program

Our Education and Training Approach

• Create curiosity by asking questions and using real-life situations.

• KISMIF “Keep It Simple, Make It Fun”• Develop “Best Practices” based on lab studies validated

by field experience. • Highlight science behind best practices.• Educate mine personnel on best practices and making

them habits. • Include ALL personnel, not just those at the face as dust

in the intake air or from “out-by” sources can be significant and impact the face area.

Dust Characterization

• Roof and floor are easily wetted.• The wettability of coal varies depending on

coal seam and location within the coal seam (i.e., top, middle, or bottom bench)

MaterialPercent (%) wettability

Sample 1 Sample 2 Sample 3Top bench 40 91.2 70

Middle bench 65 81.5 79.6Bottom bench 61 72 83

Roof 88 Floor 95

Wettability Increases with Contact Time and Water Temperature

5 10 15 20 25 3093.00

93.50

94.00

94.50

95.00

95.50

96.00

96.50

97.00

97.50

98.00Wettability as a function of contact time

Contact time (sec)

% W

etta

ble

40 50 60 70 80 90 100 1100

10

20

30

40

50

60

70

80

90

100

Wettability as a function of temperature

Temperature (F)

% W

etta

ble

Dust Sources

• Point of extraction – CM, LW shearer• Roof support systems – bolter, LW shields• Conveyor systems• Intake air

Intake Dust – Higher that expected?!

Intake Dust vs. Intake Air Velocity: Making it go faster does not make

it go away… but it does help

One Culprit in Intake Dust – Rock Dust?

About 25% of rock dust is < 10 micron (i.e, respirable range)

Water Sprays

• Maintain sprays - if its broke… fix it. – Partially blocked sprays create a stream or distorted cone,

which can be worse than no spray at all.

• Sprays must operate at the right pressure – Too much pressure may blow dust away – Too little pressure may not contain the dust.

• Research suggests pressure for hollow cone sprays should not exceed 90-100 psi

Ventilation – why it is important!

KEY PARAMETERS• Volume and velocity of air in LOXC.• Volume and velocity of air entering LC (in LOXC)

and exiting LC (at face) LC – should be close.– LC properly installed – no gaps.

• Length of LC – effects volume.• Scrubber air volume/capacity.– Good balance between

scrubber and LC volumes.

Miner Operator Location – End of Line Curtain (ELC)

1 ft. 5 ft. 3 ft. 6 ft.

Miner Operator Location – End of Line Curtain (ELC)

Difference Between CMO Standing versus Sitting/Kneeling

Line curtain

Higher mg/m3

Lower mg/m3

Effect of Scrubber w/ 7,000 cfm at ELC

Without HU in place, air is pulled by the scrubber toward the face from the gap in the LOXC. It can pick up and recirculate dust as air exits into the return XC/entry.

Scrubber discharge at an angle

Fan OFF

Fan ON

Effect of Scrubber on ELC Air Volume

• Length of LC greatly effects air volume reaching the end of the LC when the scrubber is running.

• Data from more than 200 cuts have been used to compare end of LC air volumes with scrubber off and on. Results:– LC <10 ft = 7.5% increase– LC >10 ft but <40 ft = 18.7% increase– LC >40 ft but <75 ft = 29% increase– LC > 90 ft = 80% increase

• These increases typically cause significant recirculation of dust since some of the additional air enters through gaps at the roof, floor, and overlaps that are inby the LOXC.

How long does it take for the scrubber to pull in all the air contained in a 40 foot cut?

• Scrubber intake = 7500cfm• Volume of air 40 feet from the face =

Entry height = 7 feet X Entry width = 19 feet X 40 feet = 5320 cubic feet of air5320/7500 = 42.5 seconds

Allowing the scrubber to run one minute after loading a car will significantly reduce dust in

the face area.

For Ram Car Operator…The Side They Are Located On When Traveling May Make a Difference

High dust concentrations

Lower dust concentration

Mining a XC Straight Ahead – Curtain vs. No Curtain, Scrubber ON vs. OFF

Scrubber can cause air to recirculate towards the HUO and LC can block air flow directly into return

Effect of Box and Slab Cut on HUO

Topics covered during typicalDust Control Training Program

• Dust parameters during production shift:– Replace worn or broken cutting bits– Scrubber – working properly, clean filter screen and screen

cleaning spray/s operating – Adequate air at end of line curtain and CMO positioned

properly– Clean filters on roof bolter and maintain seals of dust collection

boxes – Empty roof bolter dust boxes at face, not in LOXC– Proper placement of dust pump cyclone on person being

sampled– Keep haulage roads damp

QUESTIONS?