Control of Airborne Respirable Dust Hazards: A Training Program for Underground Coal Miners The Penn State Miner Training Program University Park, PA 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 mining2.4 million tons Room and pillar continuous mining178.6 million tons Longwall retreating (shearers)189.0 million tons Other underground methods4.0 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 Mines Continuous 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 Mines Longwall 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 CurrentProjected Shearer cutting power900 kW? Cut width1 m1.13 m Conveyor speed/ power 1.5 m/s 1,800 kW 1.5 m/s 2,700 kW Shield width/ capacity 1.5 m / 900 t 2.0m / >900 t Face voltage/ total power 4,160 V 3,900 kW --- Panel belt width1.4 m--- Main belt width1.8 m--- Production/8 hr. machine shift8,000 t---

Typical Longwall Panel Parameters CurrentProjected Seam height (m) Face width (m) Panel length (m)3,000.05,500.0 No. of entries3 or 42 or 3 % Dev. coal 10 to 15Under 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 Mines Conventional Mining Mining Method Equipment Operation Primary Source Secondary Source Quartz Source Conventional Mining Coal cutter/coal cutting Major Coal driller/coal drilling Major Blasting Major Load & transfer to shuttle car Minor Rock drill/roof bolt drilling MinorMajor Feeder-breaker Negligible Minor Conveyor Negligible

Mining Method Equipment Operation Primary Source Secondary Source Quartz Source Continuous Mining Continuous miner/coal cutting Major Falling of broken material to ground Minor Gathering arm Minor Transfer to shuttle car Minor Rock drill/drilling MinorMajor Feeder-breaker Negligible Minor Conveyor Negligible Sources of Dust in Mines Continuous Mining

Sources of Dust in Mines Longwall Mining Mining Method Equipment Operation Primary Source Secondary Source Quartz Source Longwall Mining Shearer/coal cutting MajorMinor Roof support movement Minor Stage-loader-crusher Conveyor Negligible

Proceed to Section 8 Longwall Dust Control Methods