control of airborne respirable dust hazards: a training program for underground coal miners the penn...
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Control of Airborne Respirable Dust Hazards:A Training Program for Underground Coal Miners
The Penn State Miner Training Program
University Park, PA 16802
Raja V. Ramani, Ph.D., P.E, C.M.S.P.Mark C. Radomsky, Ph.D. MPA, C.M.S.P.
Joseph P. Flick, M.S., C.M.S.P.March 31, 2003
Penn
State
CENTERS FOR DISEASE CONTROL AND PREVENTION
NATIONAL INSTITUTE FOR OCUPATIONAL SAFETY AND HEALTH
GENERIC MINERAL TECHNOLOGY CENTER ON RESPIRABLE DUST
PENNSYLVANIA BUREAU OF DEEP MINE SAFETY
RESPIRABLE DUST TRAINING PROGRAM
Section 7
UNDERGROUND MINING METHODS
AND
SOURCES OF DUST
Mining Process and Environment
The working environment in underground coal mining is completely enclosed by the geological medium consisting of the coal seam, and the strata above and below the coal seam.
Mining process consists of two kinds of operations:
1. Unit operations
2. Auxiliary operations
Mining Process and Environment
Unit operations are repeated in a cycle to extract coal, and develop the mine and mine the coal seam
Unit Operations – cutting, drilling, blasting, loading, hauling and roof bolting
Unit operations are repeated in the face areas and all unit operations produce dust
Auxiliary operations provide the support services necessary for the unit operations to function effectively.
Auxiliary Operations – ventilation, ground control, drainage, power, main haulage, communications and lighting.
Auxiliary operations can produce dust. Ventilation is a major dust control auxiliary operation.
Mining Process and Environment
Underground Coal Mining Methods
Room and Pillar Methods – common methods Conventional Mining Method
Continuous Mining Method
Longwall Methods – common methods Longwall Retreating Method with Shearers
Longwall Retreating Method with Ploughs
There are two major U.S. underground coal mining methods with several sub-classes:
Coal Production Per Mining Method
U.S. Underground Coal Mine Production Distribution in year 2000 [Total : 374 million tons]
Room and pillar conventional mining 2.4 million tons
Room and pillar continuous mining 178.6 million tons
Longwall retreating (shearers) 189.0 million tons
Other underground methods 4.0 million tons
Projection of a Hypothetical Mine Showing the First Two Years of Development
Distribution of Broken Material by Respirable, Airborne and Large Particle Size
Mining Sequence in 7-Entry Development for a Conventional Mining Section
Sources of Dust in Mines Conventional Mining Section
Kerf Cutting by the Coal Cutter
Drilling of the Blast Holes in the Face
Blasting of the Coal
Loading of Coal to Shuttle Cars
Drilling for Roof Bolt Holes
Feeder Breaker at the Dump Point
Panel Conveyor
Contamination of Intake Airways
Mining Sequence in 5-Entry Development for a Continuous Mining Section
Sources of Dust in MinesContinuous Mining Section
Coal/Rock Cutting by Continuous Miner [CM]
Coal/Rock Falling to the Ground
Gathering and Loading of the Coal by CM
Loading the Coal on to Shuttle Cars
Drilling for Roof Bolting
Feeder Breaker at the Dump Point
Panel Belt Conveyor
Contamination of Intake Air
Dust Sources in a Continuous Miner Section
Typical Longwall Section
Stage loader
Roof supports
Shearer
Conveyor
Gob
Sources of Dust in MinesLongwall Mining Section
Coal/Rock Cutting by Longwall Shearer
Advance of the Shield Supports
Breaking of Coal at Stageloader/Crusher
Panel Belt Conveyor
Contamination of Intake Air
Dust Sources in a Longwall Section
Longwall Equipment Parameters
Current Projected
Shearer cutting power 900 kW ?
Cut width 1 m 1.13 mConveyor speed/power
1.5 m/s1,800 kW
1.5 m/s2,700 kW
Shield width/capacity
1.5 m / 900 t
2.0m />900 t
Face voltage/total power
4,160 V3,900 kW
---
Panel belt width 1.4 m ---
Main belt width 1.8 m ---
Production/8 hr. machine shift 8,000 t ---
Typical Longwall Panel Parameters
Current Projected
Seam height (m) 2.0 ---
Face width (m) 330.0 420.0
Panel length (m) 3,000.0 5,500.0
No. of entries 3 or 4 2 or 3
% Dev. coal 10 to 15 Under 10%
Cut width (m) 0.9 to 1.2 >1.2
Sources of Dusts in Mines
Primary Sources – These are sources in which the dust produced primarily from breaking the coal or rock from the seam or strata. Examples include: continuous miners, longwall shearers, roof bolting machines, and blasting.
Secondary Sources – These are sources in which the dust is produced from secondary breaking arising from loading, transferring and transporting the coal. Examples include loading machines, stageloader/crusher, conveyor, and reentrainment of settled dust.
The above two sources can be further broken down into major, minor and negligible sources on the basis of their contribution to the overall dust load in the mines.
Major sources include continuous miner,
longwall shearer, and roof bolting machines Minor sources include loaders and roof bolters
Negligible sources include conveyors, and reentrainment
Sources of Dusts in Mines
Sources of Dust in MinesConventional Mining
Mining
Method
Equipment
Operation
Primary
Source
Secondary
Source
Quartz
Source
Conventional
Mining
Coal cutter/coal cutting Major Major
Coal driller/coal drilling Major
Blasting Major
Load & transfer to shuttle car
Minor
Rock drill/roof bolt drilling
Minor Major
Feeder-breaker Negligible Negligible Minor
Conveyor Negligible
Mining
Method
Equipment
Operation
Primary
Source
Secondary
Source
Quartz
Source
Continuous
Mining
Continuous miner/coal cutting
Major Major
Falling of broken material to ground
Minor
Gathering arm Minor
Transfer to shuttle car Minor
Rock drill/drilling Minor Major
Feeder-breaker Negligible Negligible Minor
Conveyor Negligible
Sources of Dust in MinesContinuous Mining
Sources of Dust in MinesLongwall Mining
Mining
Method
Equipment
Operation
Primary
Source
Secondary
Source
Quartz
Source
Longwall
Mining
Shearer/coal cutting Major Minor
Roof support movement Minor Minor
Stage-loader-crusher
Conveyor Negligible Negligible
Proceed to Section 8Longwall Dust Control Methods