Data & statistics

Frictional Ignitions in Underground Bituminous Coal Operations, 1983-2005 (PDF, 230 KB, 2007)
This paper presents a statistical analysis of frictional ignitions in the U.S. from 1983 to 2005. Various factors were considered, including mining machine type, state, basin, coalbed, coalbed production, mining method, production, productivity, mine type, and total emissions.

Models

Modeling and Prediction of Ventilation Methane Emissions of U.S. Longwall Mines Using Supervised Artificial Neural Networks (PDF, 844 KB, 2008-02)
This study proposes a principle component analysis (PCA) and artificial neural network (ANN)-based approach to predict the ventilation methane emission rates of U.S. longwall mines.

Measurement & analysis

Alternative Methodologies for Evaluating Explosion-resistant Mine Ventilation Seals (PDF, 6213 KB, 2003-10)
Discusses the evaluation of a seal evaluation method, based on a hydrostatic pressure loading concept, for in-situ testing of seals in an operating mine.

Analysis of Seismic Signatures from Gas and Dust Based Explosions at the Lake Lynn Experimental Mine (PDF, 959 KB, 2008)
A seismic monitoring system located at NIOSH's Lake Lynn Experimental Mine has monitored experimental gas and dust based explosions and impact tests. The results suggest a large explosion that's not restricted can generate potentially the same magnitude as a small explosion that is restricted.

The Brookwood Disaster and Electrical Requirements for Hazardous (Classified) Locations (PDF, 373 KB, 2007)
Researchers with NIOSH studied the electrical equipment ignition sources for the Brookwood and other disasters to develop recommendations for preventing similar disasters.

Characterization of Gas Flow in Longwall Gobs: Pittsburgh Coalbed, PA (PDF, 175 KB, 1999)
Investigation of the geologic and mining factors influencing the migration of longwall gob gas with a goal to optimize methane drainage strategies to reduce the volume of gob gas that reaches the underground workplace.

Coal Dust and Methane (PDF, 198 KB, 2008-06)
This article describes the Coal Dust Explosibility Meter (CDEM), a hand-held instrument developed by NIOSH, which uses optical reflectance to measure the explosibility of a rock dust and coal dust mixture, which is now commercially available.

Coal Dust Particle Size Survey of U.S. Mines (PDF, 56 KB, 2006-08)
NIOSH and MSHA conducted a joint survey to determine the range of coal particle sizes found in dust samples collected from intake airways of U.S. coal mines.

Coal Dust Particle Size Survey of US Mines (PDF, 742 KB, 2007-07)
NIOSH and the Mine Safety and Health Administration (MSHA) conducted a joint survey to determine the range of coal particle sizes found in dust samples collected from intake airways of US coal mines. The results indicate that particle sizes of mine coal dust in intake airways are finer than those measured in the 1920s. This finer size coal dust in intake airways would require more incombustible matter to be effectively inerted than the 65% incombustible specified in current regulations.

Determining the Source of Longwall Gob Gas: Lower Kittanning Coalbed, Cambria County, PA (PDF, 1166 KB, 1992)
Four coreholes were drilled (two before and two after mining) at a longwall mine in the Lower Kitanning coalbed to obtain coal and rock samples from overlying strata to determine their gas content at various times in the mining cycle. Test results indicate that 91 pct of the gas removed from the overlying strata came from coalbeds. Further analysis indicated that only 40 pct of the total gas produced from the panel actually came from the strata directly overlying the panel. The remaining volume of gas production probably migrated to the longwall gob from overlying, and perhaps underlying, strata immediately adjacent to the panel and perhaps from greater distances downdip because of the establishment of a long-term pressure gradient.

Detonation Wave Propagation in Underground Mine Entries (PDF, 116 KB, 2005)
This paper reports on a series of explosive detonation experiments conducted in NIOSH's Bruceton and Lake Lynn Experimental Mines to evaluate low-level (<6 psig) detonation wave propagation behavior in single- and multiple-entry configurations.

Effect of Coal Type and Oxyfuel Combustion Parameters on Pulverised Fuel Ignition (PDF, 112 KB, 2007)
This paper describes ignition tests on pulverised coal suspensions using a suite of coals of different rank and from different countries of origin and over a range of oxygen and coal concentrations of interest for oxyfuel combustion.

Experimental Mine and Laboratory Dust Explosion Research at NIOSH (PDF, 590 KB, 2000-05)
Explosion characteristics such as the minimum explosible concentration and the rock dust inerting requirements were measured for various combustible dusts. The explosion resistance characteristics of seals was also evaluated.

Explosion Evaluation of Mine Ventilation Stoppings (PDF, 233 KB, 2006-06)
NIOSH and the Mine Safety and Health Administration (MSHA) conducted joint research to evaluate explosion blast effects on mine ventilation stoppings at the NIOSH Lake Lynn Experimental Mine. The LLEM data showed that a total pressure of 52 kPa (7.6 psi) destroyed the solid-concrete-block stopping, ~36 kPa (~5.2 psi) destroyed the hollow-core concrete-block stopping, and 9 kPa (1.3 psi) destroyed the steel panel stopping.

Explosion Temperatures and Pressures of Metals and Other Elemental Dust Clouds (PDF, 1281 KB, 2007-07)
The Pittsburgh Research Laboratory of NIOSH conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries.

Explosion Temperatures of Metals and Other Elemental Dust Clouds (PDF, 1476 KB, 2006)
NIOSH conducted a study of the explosibility of various metals and other elemental dusts dispersed in air, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating the explosion hazards in the minerals and metals processing industries.

The Modified Direct Method: A Solution for Obtaining Accurate Coal Desorption Measurements (PDF, 166 KB, 2001)
This paper covers the development of NIOSH's modified direct method to measure the gas content of coal samples.

Overview of Dust Explosibility Characteristics (PDF, 583 KB, 2000-05)
Provides information on the explosibility and ignitability properties of dust clouds that can be used to improve safety in industries that generate, process, use, or transport combustible dusts.

Post-Explosion Observation of Experimental Mine and Laboratory Coal Dust Explosions (PDF, 760 KB, 2007-07)
The Pittsburgh Research Laboratory (PRL) of NIOSH and the Mine Safety and Health Administration (MSHA) conducted joint research on dust explosions by studying post-explosion dust samples. All these data will be useful in future forensic investigations of accidental dust explosions in coal mines, or elsewhere.

Post-Explosion Observations of Experimental Mine and Laboratory Coal Dust Explosions (PDF, 1164 KB, 2006)
NIOSH and MSHA conducted joint research on dust explosions by studying post-explosion dust samples. The samples were collected after full-scale explosions at the PRL Lake Lynn Experimental Mine and after laboratory explosions in the PRL 20-L chamber and the Fike 1 -m3 chamber. The dusts studied included both high and low volatile bituminous coals.

Rapid (Grab) Sampling During Full-scale Explosions - Microscopic and Analytical Evaluation (PDF, 3254 KB, 1988)
The Bureau of Mines has developed a system using a high-speed electropneumatic mechanism for the rapid (grab) sampling of dusts and gases during an explosion. The sampling system consists of an aluminum housing that incorporates two 30-cm3 preevacuated glass vials with rubber septums. Upon actuation, the sampling probe needle is driven through the septum with a pressurized air pulse, filling the tube with gas and dust from the mine explosion.

Rapid Sampling of Products During Coal Mine Explosions (PDF, 1576 KB, 1991-02)
This paper describes a U.S. Bureau of Mines investigation of large-scale coal dust explosions in an experimental mine using a high speed electropneumatic mechanism for the rapid grab-sampling of gases and dusts. This technique enables the monitoring of pyrolysis and charring in fuel dust particles, and the collection of gaseous combustion products, in both large and small-scale explosions.

Technical Development of the Coal Dust Explosibility Meter (PDF, 145 KB, 2006)
The NIOSH Pittsburgh Research Laboratory, in collaboration with MSHA Technical Support, has devised a prototype handheld instrument that can provide a direct assessment of the potential explosibility of a coal and rock dust mixture. The Coal Dust Explosibility Meter (CDEM) is not intended to replace the current MSHA laboratory analysis of coal mine dust samples for incombustible content, but rather to serve as a supplemental device for enhancing mine safety through improved rock dusting practices.

Technology News 461 - Coal Dust Explosibility Meter (PDF, 142 KB, 1997-07)
Describes a device to enable mine operators and mine inspectors to make quick and accurate measurements of the explosive nature of coal and rock dust mixtures.

Technology News 465 - Method for Predicting Methane Emissions on Extended Longwall Faces (PDF, 30 KB, 1997-11)
A method is described for allowing operators to predict methane emissions from panels with increased face width.

Technology News 490 - An Inexpensive Device for Monitoring Explosions in Sealed Areas of Underground Mines (PDF, 288 KB, 2001-06)
Description of a passive, inexpensive technique for monitoring explosion overpressures within sealed areas in underground coal mines.

Use of Infrared Sensors for Monitoring Methane in Underground Mines (PDF, 393 KB, 2008)
This paper describes research conducted to compare the performance, including response time and accuracy, of selected instruments using infrared and catalytic sensors.

Case studies

Blasting Injuries in Surface Mining with Emphasis on Flyrock and Blast Area Security (PDF, 380 KB, 2004-01)
This paper describes several fatal injury case studies, analyzes causative factors, and emphasizes preventive measures.

The Borehole Monitoring Experiment: Field Measurements of Reservoir Conditions and Responses in Longwall Panel Overburden During Active Mining (PDF, 459 KB, 2008-06)
This paper describes the results of a NIOSH borehole monitoring experiment (BME) on an active longwall panel.

Engineering controls

Explosion Pressure Design Criteria for New Seals in U.S. Coal Mines (PDF, 2768 KB, 2007-07)
Seals are used in underground coal mines throughout the United States to isolate abandoned mining areas from the active workings. Prior to the Sago Mine disaster in 2006, mining regulations required seals to withstand a 140-kPa (20-psig) explosion pressure (30 CFR4 75.335(a)(2)). However, Program Information Bulletin No. P06-16 issued by MSHA on July 19, 2006, requires seals to withstand a 345-kPa (50-psig) explosion pressure. The recently enacted MINER Act requires MSHA to increase this design standard by the end of 2007. This report provides a sound scientific and engineering justification to recommend a three-tiered explosion pressure design criterion for new seals in coal mines in response to the MINER Act. The recommendations contained herein apply to new seal design and construction in U.S. coal mines.

Explosion Prevention in United States Coal Mines (PDF, 46 KB, 2007)
This paper outlines the legal standards and methods for protecting underground coal mines in the United States from explosions of methane gas and coal dust. New research will also be presented on the inertization of float coal dust in mines through the addition of inert stone dust and on the application of the Coal Dust Explosibility Meter, a handheld device developed by NIOSH to directly measure the explosibility of a coal dust - limestone dust mixture based on optical reflectivity.

Remote Gob Gas Venthole Monitoring and Cellular Telephone-Based Real-Time Data Transmission System (PDF, 844 KB, 2002-10)
Report on the development and field testing of a solar powered, remote gob gas venthole monitoring and cellular telephone-based real-time data transmission system.

Secondary Explosion Hazards During Blasting in Oil Shale and Sulfide Ore Mines (PDF, 2935 KB, 1995)
Laboratory and field testing results are presented for reducing dust and/or gas ignitions associated with blasting operations in oil shale and sulfide ore mining applications.

Technology News 473 - The Explosion Hazard From Hydrogen Gas Generation Inside Sealed Frames (PDF, 69 KB, 1998-06)
Discusses one type of explosion hazard that was discovered lurking inside sealed and filled plow frame sections when NIOSH investigated ignition incidents resulting from drilling into plow frames.

Technology News 489 - Reducing the Danger of Explosions in Sealed Areas (Gobs) in Mines (PDF, 536 KB, 2001-05)
Techniques are identified to reduce the probability of gob gas explosions.

Technology News 530 - Frictional Ignition of Methane-Air in the Presence of Liquid Hydrocarbons (PDF, 194 KB, 2008-03)
This briefly describes testing done to ignite methane-air in the presence of liquid hydrocarbons, and gives recommendations for limiting fricitonal ignition.

Laboratories

Lake Lynn Cannon Gallery
Evaluating the hazards of explosives in a flammable gas and/or combustible dust atmosphere.