Mining Program Strategic Plan, 2019-2023 - Strategic Goal 3: Reduce the risk of mine disasters and improve post-disaster survivability of mine workers

Mining Program Strategic Plan

Mining Program Strategic Goals Overview

Strategic Goal 3: Reduce the risk of mine disasters and improve post-disaster survivability of mine workers

Historically, mine disasters such as fires, explosions, inundations, and roof falls have been the driving force behind both enactment of mining laws and regulations and government investment in mining health and safety research. Fatalities have occurred as a direct result of these events but have also occurred when workers were unable to successfully escape, to isolate themselves from toxic atmospheres to await rescue, or when rescuers perished during a rescue attempt. Although mine disasters have become less frequent, the hardship arising from recent mine disasters is still strongly felt by the families of the 12 miners who barricaded themselves at the Sago mine following the 2006 explosion, with 11 suffocating in the toxic atmosphere; the 6 miners and 3 rescuers who died in the Crandall Canyon pillar collapse in 2007; and the 29 miners who perished in the Upper Big Branch explosion in 2010.

Lives can be saved through improved technologies and practices to limit the occurrence of mine disasters. These technologies and practices include more effective applications of rock dust and improved control of float coal dust to limit accumulations of the explosible fuel source; more effective bleeder designs to limit accumulations of methane gas in bleeder entries and to maintain the proper split of ventilation airflow at longwall tailgate corners; improved techniques for identifying incipient stages of a mine fire and the spread of toxic contaminants throughout active workings; and improved identification of conditions and mechanisms that lead to instability of rock masses. Improvements in post-disaster escape strategies and technologies such as mine refuge alternatives, emergency communications, emergency evacuation decision-making, and survivability of critical systems such as mine-wide atmospheric monitoring, communication, and tracking systems could increase the chances of worker survival.

NIOSH disaster prevention research can reduce the human toll of mine disasters by removing or limiting the conditions under which a disaster can occur. Improved strategies and technologies for self-escape and for use by mine rescue personnel will provide the industry with much-needed tools to enhance miner survivability in the event of a disaster. Accordingly, this work addresses accumulations of combustible and explosible materials; detection of hazardous conditions; catastrophic failure of mine pillars, stopes, and critical structures; mine worker self-escape; and post-disaster survival and rescue of mine workers.

Below, in the boxes to support Strategic Goal 3, each intermediate goal is followed a series of activity goals—activities that move the research through the NIOSH research to practice (r2p) continuum—then a table, then an analysis of burden, need, and impact. The table lists the health and safety concerns; describes the research focus areas; identifies the mining sectors or worker populations affected; defines the research type used to address the concerns, and links to key Mining Program research projects that target solutions.

Click on a box representing the intermediate goal to expand or collapse it.

Activity Goal 3.1.1: (Intervention Research) Conduct studies to design, develop, and assess the effectiveness of standardized rock dust testing procedures and protocols.

Activity Goal 3.1.2: (Intervention Research) Conduct studies to develop, assess the effectiveness of, and identify barriers to utilizing anti-caking rock dust.

Activity Goal 3.1.3: (Intervention Research) Conduct studies to develop and assess the effectiveness of float dust controls to reduce the risk of injury associated with coal mine dust explosions.

Activity Goal 3.1.4: (Intervention Research) Conduct studies to develop guidelines for mine development near gas wells and casing design criteria to reduce the likelihood of gas migration into underground mines.

Activity Goal 3.1.5: (Intervention Research) Conduct studies to reduce the risk of explosions caused by emissions of methane gas from gobs.

Health and Safety Concern Research Focus Area Mining Sector/Worker Population Research Type Related Project Research
Injuries and fatalities from explosions Float dust control Underground coal Intervention

Improved float dust controls
(new in 2019)

Injuries and fatalities from explosions Rock dust effectiveness Underground coal Intervention Treated rock dust
Injuries and fatalities from explosions Gas well/longwall coal mine interaction Underground coal Intervention Gas well stability in pillars
Burden

According to MSHA data, since 2009, 29 U.S. mine workers have been killed and 23 injured as a result of fires or explosions in underground workings. Float coal dust, generated during coal mining, serves as fuel that can propagate an explosion flame, and the explosibility of float coal dust is controlled by applying “rock dust”—i.e., ground limestone dust—on all mine surfaces as an inerting agent. However, based on data from MSHA’s Mine Data Retrieval System, the industry received nearly 1,600 violations in 2018 for failure to maintain rock dust levels sufficient to limit float coal dust explosibility. Accumulations of methane gas are also a constant threat to the safety of underground mine workers. According to MSHA data, from 2009 to 2018, roughly 100 methane ignitions occurred during coal mining, generally during longwall mining. Ventilation airflow is the primary means of controlling methane levels, but such controls are challenged by more rapid mine development that liberates greater methane quantities, larger mining areas that create greater exposed coal surfaces, and larger gob areas under the influence of a single ventilation district. Finally, fires in a confined underground mine environment can produce catastrophic consequences. From 2009 to 2018, approximately 830 fires were reported that resulted in one fatality. When the fire source cannot be readily diagnosed or remedied, the mine may be temporarily sealed by a mine operator until diagnostics indicate that the fire is extinguished. Such an action can greatly stress or ruin the local economies, which are dependent upon mine worker wages.

Need

Federal regulations mandate that all underground coal mine surfaces be rock dusted; however, no standard protocol exists for evaluating the inerting performance of rock dust. A previous NIOSH study collected rock dust samples from various mining regions and discovered that nearly half of the samples did not meet minimum particle size requirements; of those that did meet the requirements, some did not inert coal dust. This study calls into question the effectiveness of rock dust products being used in underground coal mines, demonstrating the need for standard test protocols for use by manufacturers. To reduce disaster risk, effective ventilation on longwall mining units is also critical to controlling the large amounts of methane gas liberated during mining. Specifically, research is needed to quantify potential accumulations of methane at the longwall tailgate corner. Guidance on mine monitoring is also needed so that sensors can be properly deployed to maintain the effectiveness and utility of a monitoring system. Sensor deployment strategies must be developed and evaluated using performance-based metrics to ensure early detection of a combustion incident. The NIOSH Mining Program is uniquely qualified to conduct this disaster prevention work due to the high level of expertise of its researchers and the availability and access to the required laboratory apparatuses and in-mine facilities.

Impact

NIOSH Mining Program successes in reducing the risk of disaster are evidenced by the development of the coal dust explosibility meter, recommendations for a new rock dusting standard, software products such as MFIRE, and research on “smart ventilation.”  Continued research in these areas will develop technologies that limit the generation and transport of float dust at the source and throughout mine workings. In addition, standard test protocols developed by NIOSH will be available to industry suppliers to assess rock dust effectiveness for inerting a propagating coal dust explosion. Mine operators will use NIOSH research findings to improve ventilation to minimize accumulations of methane gas at longwall tailgate corners, and NIOSH will develop new strategies that provide earlier detection of such accumulations along the longwall face area, thus reducing the number of face ignitions. Improved NIOSH-developed sensor deployment strategies will be performance-based, permitting early detection of fires and heating in the incipient stages of combustion and, perhaps, forestalling the long-term closure and sealing of the mine.

Top of Page

Activity Goal 3.2.1: (Intervention Research) Conduct studies to develop sensor deployment strategies to detect levels of combustible gases to prevent fires and explosions and ground instabilities.

Activity Goal 3.2.2: (Intervention Research) Conduct studies to develop sensor deployment strategies to detect unstable mine opening conditions for prevention of ground control failures.

Activity Goal 3.2.3: (Intervention Research) Conduct studies to develop and assess the effectiveness of interventions to prevent hot surface ignitions on mining equipment.

Activity Goal 3.2.4: (Intervention Research) Conduct studies to develop and assess the effectiveness of interventions to suppress mining equipment fires.

Activity Goal 3.2.5: (Intervention Research) Conduct studies to characterize factors that influence Li-ion battery ignition pressures within sealed enclosures and to develop design recommendations for explosion-proof or flameproof battery enclosures.

Activity Goal 3.2.6: (Intervention Research) Conduct studies to characterize fire in Li-ion ion battery-powered mining equipment to determine appropriate fire suppression agents/systems and to develop ventilation recommendations for preventing smoke and toxic gas spread in a mine.

Health and Safety Concern Research Focus Area Mining Sector/Worker Population Research Type Related Project Research
Fatalities from mine fires Combustible gas detection Underground mining Intervention

Characterizing mine fires
(ended in 2019)

Fatalities from ground falls and bursts Ground detection conditions Underground coal mining; underground metal (deep and weak rock mines) Intervention

Stone pillar design

Alternative mining methods

Fatal and nonfatal injuries from equipment fires Hot surface ignition mitigation Underground mining Intervention

Equipment fires
(added in 2019)

Fatalities from mine fires; injuries and fatalities from explosions Lithium-ion battery safety Underground mining Intervention Lithium-ion battery hazards
(added in 2019)
Burden

Mine fires and dynamic rock and coal failures continue to be serious hazards threatening the safety of the mining workforce. According to MSHA accident data, approximately 380 coal burst events were reported from 1983 to 2013. Of those, 20 resulted in fatalities, with 33% in longwall mines. From 2009 to 2018, there were 25 bursts reported, with 12% of these resulting in fatalities. The large majority of these events (64%) were in longwall mines. There were two additional fatalities in a single event in 2014 during room-and-pillar (R&P) retreat mining. MSHA mine accident data further indicate that during 2009-2018 there were 830 reported fires, one fatality caused by mine fires, and 238 injuries caused by flame, fire, and smoke. In metal/nonmetal mines, combustible liquids including diesel fuel, engine oil, and hydraulic fluid come into contact with hot engine exhaust components such as exhaust manifolds and turbo chargers. Further, increased use of lithium-ion (Li-ion) battery technologies in mines brings potential failure modes, intensities, and toxicities of large-format Li-ion battery fires that are not well understood. In addition, dynamic rock and coal failures, known as coal “bumps” or “bursts,” pose a significant hazard during full extraction coal mining. According to MSHA accident data, from 2009 to 2013, there were 20 bursts reported, resulting in one fatality. The large majority of these events (75%) were in longwall mines. There were two additional fatalities in a single event in 2014 during room-and-pillar (R&P) retreat mining. The two most recent coal burst fatality events occurred in R&P retreat mining operations with distinct multi-seam interactions evident at the accident sites.

Need

Mine monitoring remains one of the biggest assets to improve detection of and reduce the risk of hazardous conditions, but sensors must be appropriately deployed to ensure the efficacy of the monitoring system and the information it provides. MSHA regulations on sensor deployment are limited and prescriptive in nature. Performance-based deployment strategies are needed for critical underground locations, including battery charging stations and diesel fuel storage areas. In relation to Li-ion batteries, current MSHA battery fire prevention requirements were developed to address lead-acid battery hazards, but do not take into consideration known fire hazards associated with Li-ion batteries. Research is needed to study the failure modes of these batteries, heat release rates of battery fires, gaseous products of combustion, the appropriate fire suppression agents/systems, explosion-proof enclosure design criteria, and overall risk assessment. The continued occurrence of dynamic events with the potential to cause multiple fatalities underscores the need for further understanding of the conditions and mechanisms that lead to those events. Detailed geological characterization of the surrounding rock mass and the determination of the complete stress redistribution experienced during R&P retreat and longwall mining are needed to understand and eliminate these rare but catastrophic events. NIOSH is ideally suited to address these issues due to its breadth of knowledge and experiences in developing sensors and sensor arrays to detect hazardous accumulations of combustible gases. Furthermore, NIOSH has the expertise and industry contacts necessary to understand coal bursts and related phenomena and to develop methodologies for predicting and identifying potentially adverse mining conditions.

Impact

Research on mine monitoring will help to address the industry’s major fire safety issues. The development of sensor deployment strategies will help mine operators install those sensors appropriately to detect a mine fire or a hazardous condition in a timely and effective manner, thus reducing injuries or fatalities from the fire or toxic byproducts. Improved sensor deployment strategies will be performance-based, permitting early detection of fires and heatings in the incipient stages of combustion. Lithium-ion battery safety research will advance fire-related knowledge in this area, improving reactions to fires caused by such batteries. This work will also establish a solid foundation for developing prevention measures and avoidance forecasting to eliminate burst catastrophes.

Top of Page

Activity Goal 3.3.1: (Basic/Etiologic Research and Intervention Research) Conduct studies to determine characteristics associated with and development of mine design guidelines to prevent massive or catastrophic failures of mine structures.

Health and Safety Concern Research Focus Area Mining Sector/Worker Population Research Type Related Project Research
Fatal and nonfatal injuries from ground failure Pillar failure in dipping and multiple-level mining Underground stone mining Basic/Etiologic
Intervention
Stone pillar design
Fatal and nonfatal injuries from ground failure Pillar failure in underground coal mines; failures in rockburst-prone or weak ground conditions Underground coal; underground metal (deep and weak rock mines)

Basic/Etiologic
Intervention

Coal and entry stability
(added in 2019)

Alternative mining methods

Roof support

Burden

Current NIOSH Mining Program research related to this intermediate goal focuses on underground stone mines. Historically, the large majority of limestone mining has been accomplished through surface mining operations. NIOSH reported that 3,334 crushed stone mines were operating in 2019. Of that total, 101 were underground mines. Over the last two decades, the number of surface operations has been decreasing while the number of underground mines is gradually increasing. According to MSHA data, since 2009, fatalities related to ground control in underground stone mines have accounted for 4 of the 55 total fatalities. The reduction in ground fall injury rate in limestone mining has been significantly less than that achieved in coal mining during the past decade, and the injury rate has increased significantly over the past two years. Likewise, the fatality rate in the underground stone sector has increased overall during the past decade, while the underground coal sector fatality rate has declined.

Need

NIOSH developed and made public the first pillar design software program (S-Pillar) for underground stone mining in 2011. This software is designed to meet the pillar design needs of the majority of the underground stone mine industry but does not address several uniquely challenging environments. Stakeholder discussions have indicated that these environments will likely be encountered more often at future mining operations. Further analyses of case histories are necessary to provide detailed assessments of the hazards associated with these insufficiently studied environments. NIOSH is uniquely qualified to undertake this research effort. The organization has had a long history of impactful research in this area, including development of software for analysis of stone pillar stability. Continued efforts will only improve the predictive capabilities of this product.

Impact

A successful stone pillar stability project will establish a solid foundation for the development of revised or supplemental guidelines for underground stone pillar design. Research will likely be performed in underground limestone mines but may be applicable to other hard rock room-and-pillar mines with similar dimensions, depths, mechanical properties, and lithology.

Top of Page

Activity Goal 3.4.1: (Intervention Research and Translation Research) Conduct studies to develop and determine barriers to effective implementation of a standardized mine emergency self-escape system.

Activity Goal 3.4.2: (Translation Research) Conduct studies to determine barriers to effectively incorporating self-escape competency profiles into assessment activities.

Activity Goal 3.4.3: (Intervention Research) Conduct studies to improve the integrity of atmospheric monitoring systems following a disaster.

Activity Goal 3.4.4: (Translation Research) Conduct studies to determine barriers to the effective use of atmospheric monitoring tools.

Activity Goal 3.4.5: (Intervention Research) Conduct studies to improve post-disaster survivability and self-escape capability by interfacing MFIRE 3.0 with real-time mine fire simulations with information generated from atmospheric monitoring data.

Activity Goal 3.4.6: (Intervention Research) Conduct studies to assess the performance of refuge alternatives to improve post-disaster survivability and self-escape capability.

Health and Safety Concern Research Focus Area Mining Sector/Worker Population Research Type Related Project Research
Survivability during self-escape Technologies and standardized practices to improve self-escape Underground mining Intervention
Translation

Situational awareness
(ended in 2019)

Fatal and nonfatal injuries from fire Fire detection Underground mining Intervention

Characterizing mine fires
(ended in 2019)

Fatal and nonfatal injuries Refuge alternatives Underground coal Intervention Refuge alternatives
Emergency management/disaster prevention Leading health and safety indicators Underground mining Intervention
Translation
Health and safety indicators
(added in 2019)
Burden

Mine emergencies have resulted in fatalities even when self-rescue responses and rescue activities were attempted, which raises a number of serious concerns about the preparedness of the U.S. mining industry to respond to mine emergencies. There is evidence that inadequate training of the workforce to effectively identify and respond to the related risks is among the root causes associated with these tragedies. Less than optimal technologies are also at fault. For example, MSHA evaluated accident and fatality data from 1900 through 2006 and estimated that 221 lives could have been saved over the 107-year period if refuge alternatives (RAs) had been available. To continue improvement of refuge alternatives, the MSHA final rule provides guidance for the design and implementation of these structures, including structural integrity of RAs, breathable air supplies, air monitoring, the removal of harmful gases, effective communications, and provisions for lighting, sanitation, food, water, and first aid. While a significant amount of work has been conducted in the development and integration of technologies to fulfill these requirements, validation of the designs and commercially available products must be investigated.

Need

While it is difficult to quantify or predict the economic and human costs associated with mine disasters, the resulting fatalities serve as a reminder of the critical need to balance investments in resources to reduce the likelihood of high-probability but low-severity events with investments focusing on response to infrequent but high-severity events. NIOSH is an industry leader in the development and testing of emergency response systems. As such, the Mining Program can provide the mining industry with critical guidance on future modifications and evaluations of improved systems. Fatalities can be reduced through improved solutions for mine worker self-escape and for survivability of those who fail to escape from an underground mine fire, explosion, or fall of ground. Because of its past research in the areas of self-escape, mine rescue, and post-disaster survivability, the Mining Program is well-positioned to make critical advances in these areas to support mine workers who could be endangered in future events. Success depends on monitoring systems, which accurately provide information of contaminated underground atmospheres after a mine disaster; technologies that provide a safe location for refuge with an atmosphere where trapped miners can wait for rescue; miners who evaluate their situations correctly and take appropriate self-protective actions; and mine rescuers who make decisions so they can safely assist miners during emergency events.

Impact

Building on past successful research and development efforts will improve the survivability and applicability of underground post-disaster monitoring systems. For example, rather than drilling boreholes to enable monitoring of the underground atmosphere, which can take days to complete, research will develop more robust environmental sensors strategically located in underground workings that can collect real-time mine data to monitor and lower the risk of hazardous conditions. Such advances will allow the continued flow of critical atmospheric information to mine rescue teams and to underground mine workers. Additional study by NIOSH in miner competence in the knowledge, skills, abilities, and other attributes (KSAOs) required for self-escape post-disaster will develop new self-escape training protocols. Through the application of evidence-based NIOSH recommendations and incorporation of self-escape performance-based training and assessment criteria, mine safety and health training professionals will have the tools necessary to bring all miners to mastery in the physical tasks required for self-escape. Further investigation of refuge alternatives will enable the mining industry to perform accurate evaluations of RAs and to submit approval applications required by MSHA. Research on the validation of the designs and commercially available RA products will provide life-sustaining solutions to miners who fail to escape and must take refuge to await rescue.

 Top of Page

Page last reviewed: 11/10/2019 Page last updated: 1/6/2020