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