SME Spring 2022 Seminar Series Program
This program includes the dates, times, and abstracts of NIOSH presentations accepted at the 2022 SME Annual Conference and Expo.
Ground Control - April 19, 2022
12:45 p.m. - Zoom seminar session begins
1:00 p.m. - Opening remarks by J. Eric Shereda, PE, CONSOL Energy and Chair, Pittsburgh Section
1:05 p.m. - Utilization of Statistical Analysis to Identify Influential Slope Parameters Associated with Rockfall at Open Pit Mines; presented by Joe Bourgeois, Spokane Mining Research Division, email: qso2@cdc.gov
Abstract: The application of statistical analysis software programs has proven useful for investigation of rockfall runout distance along a designed slope. Rockfall modeling programs are continually being upgraded with more sophisticated analysis tools, such as the use of the rigid body versus lump mass models. Engineers at mine sites utilizing the software may have varied experience related to these models, their associated input parameters, and how to interpret the generated results. To address this concern, researchers at the Spokane Mining Research Division of NIOSH investigated the influence of slope height, slope angle, slope material, and rock size for both rigid body and lump mass models in a 2-D statistical analysis program. Based on a literature search and industry input, specific ranges common to that of an open pit mining environment were chosen for each of the input parameters to determine 90% rock runout distance as well as their sensitivity to change. Data collected from this numerical analysis and simulation will be compared to empirical rockfall data gathered through the duration of the Highwall Safety project conducted by NIOSH from 2022–2026.
1:25 p.m. - Changes in Elasticity and Ductility of Cemented Paste Backfill due to Variations in Binder Content; presented by Tyler Emery, Spokane Mining Research Division, email: qdn0@cdc.gov
Abstract: The Spokane Mining Research Division (SMRD) of NIOSH has partnered with a narrow vein, hard rock underground mine to research the effects of the binder content on the elasticity and post-peak ductility of cemented hydraulic backfill (CHB). This is part of a larger study to enhance the long-term integrity of ground support in underground mines. As mining advances deeper and stresses increase, CHB mix designs will benefit if they can be modified to handle higher levels of strain which are induced by an increased stope closure, typically affected by a reduction in stope width and increased mining depth, or through dynamic loading resulting from a local seismic event. This portion of the research examined the impact of reductions in binder and their impact on Young’s modulus, peak strength, and post-peak ductility.
1:45 p.m. - Assessment of Floor Heaves Associated with Bumps in a Longwall Mine Using the Discrete Element Method; presented by Bo Hyun Kim, Spokane Mining Research Division, email: bkim2@cdc.gov
Abstract: The floor-heave and no floor-heave phenomenon at a western U.S. coal mine was not clearly demonstrated in the numerical model using conventional shear-dominant failure criteria. Kim and Larson (2019) demonstrated the floor-heave and no floor-heave phenomenon using a user-defined model of the s-shaped brittle failure criterion in conjunction with a spalling process in FLAC3D. The results of the FLAC3D modeling agreed with the observations of the relative amounts of heave from each gate road system. However, the FLAC3D model adopted many assumptions and simplifications that were not very realistic from a physical or mechanical perspective. The anisotropy was considered by using the ubiquitous joint (UBI) constitutive model which can represent only one set of cleats. The bedding planes in the coal seam were ignored but implicitly considered by reducing material properties in the model. The stress-induced cracking was mimicked by simultaneously installing a UBI while the mining-induced stresses were calculated in the model. To overcome the assumptions and simplifications of the FLAC3D model, 3DEC modeling in conjunction with the Discrete Fracture Networks (DFNs) technique was performed to better understand the true behavior of floor heave associated with underground mining in an anisotropic stress field. The effect of stress rotation in the mining-induced stress field was considered by using a different geometry of rock blocks system in the coal seam. The heterogeneity of the engineering properties were also considered by using Monte Carlo simulations. Consequently, the 3DEC models using the DFNs technique resulted in modeling calculations of floor heave agreed with observations of the relative amounts of heave from each gate road system.
2:05 p.m. - Effects of Foam Additive on the Ductility of Cemented Paste Backfill; presented by David Sweet, Spokane Mining Research Division, email: myo2@cdc.gov
Abstract: For traditional underhand cut-and-fill mining operations, it can be challenging to design a suitable cemented paste backfill (CPB) mix that can meet the necessary strength requirements and yet maintain its ductility. In deep underground metal mines, the CPB must achieve a high enough strength to be competent under high stress conditions while also remaining ductile enough to withstand high strain from squeezing ground as underhand mining continues under backfilled stopes. To eliminate ground falls that result in injuries and fatalities, researchers from the Spokane Mining Research Division (SMRD) of NIOSH have partnered with Aerix Industries, a producer of concrete additives, to study the effects of foaming agents on the strength and ductility of CPB. This laboratory study examines the impact of various amounts of foam additive on the strength and ductility of CPB mix designs, using binder and tailings provided by Hecla Limited from the Lucky Friday Mine.
2:25 p.m. - Closing remarks
2:30 p.m. - Close of Zoom session - Next webinar: April 21, 2022
Ventilation 1 - April 21, 2022
12:45 p.m. - Zoom seminar session begins
1:00 p.m. - Opening remarks by J. Eric Shereda, PE, CONSOL Energy and Chair, Pittsburgh Section
1:05 p.m. - A Novel Methodology to Locate an Abnormal Airflow in Underground Mine Ventilation Networks; presented by Davood Bahrami, Pittsburgh Mining Research Division, email: dbahrami@cdc.gov
Abstract: Mine ventilation is one of the most important aspects of mining operations in underground mines. It is critical to maintain and deliver required fresh air to the active areas to reduce the risk of overexposure to hazardous contaminants or explosive atmospheres. An unexpected or unknown event such as roof collapse, unexpected mine door closure/opening, a fire/explosion, or fan malfunction could adversely alter the airflow distribution within the mine ventilation network that could lead to a hazardous underground environment. Knowing the occurrence and location of such an incident is of critical importance. In this study, the authors developed a novel methodology to assist mine operators in quickly identifying the location of any abnormal airflow change within the network using the airflow changes at monitored airways. The concept is based on a direct derivative method developed by the authors. This paper provides the details of the developed method as well as numerical verification examples. The application of this method can benefit mine operators and safety personnel in making better decisions during a mine emergency response operation to mitigate hazardous conditions arising from an unexpected airflow disturbance.
1:25 p.m. - A Direct Derivative Method to Calculate Resistance Sensitivity for Mine Ventilation Networks; presented by Lihong Zhou, Pittsburgh Mining Research Division, email: itn2@cdc.gov
Abstract: A reliable and stable ventilation system is essential to the safe operation of underground mines. The stability of a mine ventilation system becomes extremely critical while responding to a fire incident since an unstable ventilation system will pose a risk of airflow reversal. The reversed airflow could bring the fire contaminants such as toxic gases and smoke unexpectedly to working areas. In the past few years, there has been a growing interest in the study of ventilation network stability using the concept of resistance sensitivity, which is described as an indicator of how the airflow in an airway is reacting to a resistance change of other airways. Several methods of calculating the resistance sensitivity in a mine ventilation network have been carried out by re-searchers and scholars around the world. However, the proposed methods heavily rely on a vast amount of mine ventilation simulations, which are very time and computer-power consuming, especially for a large-scale mine ventilation network. In this paper, a direct derivative method calculating the resistance sensitivities with a single mine ventilation simulation has been developed and implemented into a mine fire simulation software, MFIRE. The results from the direct derivative method were verified against the results from a traditional method. The direct derivative method has been proved to be reliable and accurate.
1:45 p.m. - Rockmass Permeability Induced by Longwall Mining Under Deep Cover: Potential Gas Inflow from a Sheared Gas Well, presented by Zoheir Khademian, Pittsburgh Mining Research Division, email: opv9@cdc.gov
Abstract: The stability of shale gas wells drilled through current and future coal reserves can be compromised by ground deformations due to nearby longwall mining. Depending on the longwall-induced rockmass permeability, the high-pressure explosive gas from the damaged well may reach mine workings and overwhelm the mine ventilation systems. This study uses geomechanical models to estimate the rockmass permeability induced by mining. A two-panel longwall model of a deep, 341-m-cover mining site in southwestern Pennsylvania is constructed in 3DEC to explicitly model the rockmass by a Discrete Fracture Network (DFN) technique. Stress-induced fracture apertures and permeabilities are calculated across the model and are validated against permeability measurements. A Fracture Flow Code (FFC) is developed to use these results to predict potential inflow to the mine should a gas well breach occur. One hundred DFN realizations are simulated, and the results show that for a gas pressure of 2.4 MPa, the average of the predicted inflow rates to this deep-cover mine is 0.006 m3/s, significantly lower than the average inflow of 0.22 m3/s for a shallow-cover mine (145 m deep) studied in the previous work (Khademian, et al. 2021). The result can help assess the potential hazards of a shale gas well breach for mine safety and evaluate the ventilation requirements to mitigate the risk.
2:05 p.m. - A Network Model Analysis of an Unconventional Gas Well Breach Above an Underground Coal Mine, presented by Heather Dougherty, Pittsburgh Mining Research Division, email: hdougherty@cdc.gov
Abstract: Gas wells have often intersected mining resources, but unconventional shale well drilling has more recently challenged mines to balance the risk of interaction due to higher pressures and larger quantities of gas. Full extraction mining, such as the longwall method, induces ground movement that may influence the casings if wells are drilled within the mining area. The possibility of a casing shear would lead to the risk of unplanned gas migration into the mine. This has the potential to quickly overcome the ventilation system and reach the explosive range which, if ignited, can have catastrophic consequences on the health and safety of underground workers. The utilization of network software to model mine ventilation is a common practice in the mining industry and can assist with a well breach scenario. This work focuses on a well breach in between two longwall panels after second panel mining with gas entering primarily through the gobs of the adjacent longwall panels. Applying the network software Ventsim, a gob zone and ventilation network were created to better understand the distribution of gas within the mine and the limitations and effectiveness of a ventilation system. The model shows both a transient flow simulation and steady state concentrations throughout the mine ventilation system. Using a standard Pittsburgh coal seam longwall ventilation scheme, we find that the system can dilute a significant inflow of up to 700 cfm of methane.
2:25 p.m. - Closing remarks
2:30 p.m. - Close of Zoom session - Next webinar: April 26, 2022
Ventilation 2 - April 26, 2022
12:45 p.m. - Zoom seminar session begins
1:00 p.m. - Opening remarks by J. Eric Shereda, PE, CONSOL Energy and Chair, Pittsburgh Section
1:05 p.m. - A Laboratory Investigation of Underside Shield Sprays with a Shearer Clearer Water Spray System to Improve Dust Control on Longwall Faces; presented by Scott Klima, Pittsburgh Mining Research Division, email: sklima@cdc.gov
Abstract: Previous testing was performed by researchers at NIOSH to improve longwall dust control using underside shield sprays with a longwall directional spray system. This testing provided encouraging results toward respirable dust exposure reductions for longwall personnel, achieving as high as 99% dust reduction at some sampling locations along the longwall personnel walkway. Additional laboratory testing was con-ducted to test these underside shield sprays in conjunction with a shearer-clearer spray system located on the longwall shearer body. The purpose of this testing was to determine if the underside shield sprays interacted positively or negatively with the shearer-clearer sprays. Results from this testing indicate that while the shearer-clearer system influences where the respirable dust particles are directed, underside shield sprays can still lower respirable dust exposure for longwall personnel.
1:25 p.m. - Lithium Ion Battery Thermal Runaway in a Methane-Air Environment; presented by Naseem Rayyan, Pittsburgh Mining Research Division, email: nbo1@cdc.gov
Abstract: As lithium-ion batteries (LIBs) become more prevalent in the mining industry, new hazards of battery fire and explosion are emerging. Efforts must be taken to ensure that workers are safe from these new hazards, such as batteries undergoing thermal runaway in underground areas that may have explosive methane-air mixtures. Researchers at NIOSH investigated overpressures generated within a sealed battery enclosure filled with an explosive methane-air mixture and a single cell lithium-ion battery driven into thermal runaway using an accelerating rate calorimeter (ARC). For both iron phosphate (LFP) and nickel manganese cobalt (NMC) lithium-ion cells, the explosion overpressures remained un-changed with varying percentages of methane concentration in the atmosphere surrounding the cell. It’s likely that the gases released from the battery undergoing thermal runaway caused an inert atmosphere within the sealed canister. The results from this study will help mining equipment manufacturers develop proper measures to keep miners safe while working with lithium-ion batteries in underground gassy mines.
1:45 p.m. - Hot Surface Ignition of Liquid Fuels Under Ventilation; presented by Wei Tang, Pittsburgh Mining Research Division, email: ope0@cdc.gov
Abstract: Mine equipment fires remain as one of the most concerning safety issues in the mining industry, and most equipment fires were caused by hot surface ignitions. Detailed experimental investigations were conducted at the NIOSH Pittsburgh Mining Research Division on hot surface ignition of liquid fuels under ventilation in a mining environment. Three types of metal surface materials (stainless steel, cast iron, carbon steel), three types of liquids (diesel fuel, hydraulic fluid, engine oil), four air ventilation speeds (0, 0.5, 1.5, 3 m/s) were used to study the hot surface ignition probability under these conditions. Visual observation and thermocouples attached on the metal surface were used to indicate the hot surface ignition from the measured temperatures. Results show that the type of metal has a noticeable effect on the hot surface ignition, while ventilation speed has a mixed influence on ignition. Different types of liquid fuels also show different ranges of ignition temperatures. Results from this work can be used to help understand equipment mine fires and develop mitigation strategies.
2:05 p.m. - Evaluation of Parameters Influencing Potential Gas Flow to the Mine in the Event of a Nearby Shale Gas Well Casing Breach; presented by Kayode Ajayi, Pittsburgh Mining Research Division, email: ony2@cdc.gov
Abstract: The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine creating safe-ty concerns. To provide recommendations for developing guidelines that ensure a safe co-existence of longwall mining and unconventional shale gas production, this study evaluates the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach using a discrete fracture network (DFN) model. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations are within values validated with field measurements. The results show that a decrease in fracture aperture (potentially due to longwall-induced stress in the likely vicinity of the breach location) reduces the potential gas flow to the mine by a significantly higher proportion. A 50% decrease in the aperture of the fracture that directly transports the gas from the casing breach location reduces the gas flow to the mine by over 70%. Similarly, changes in the fracture water saturation level significantly affect the gas flow. In all cases, the potential gas flow to the mine is higher if the casing breach occurs at an increased gas well pressure. These findings provide critical information regarding the impact of each of the parameters associated with gas flow in the event of a shale gas casing breach near a longwall mine and could help towards the development of guidelines to ensure a safe coexistence of both industries.
2:25 p.m. - Closing remarks
2:30 p.m. - Close of Zoom session - Next webinar: April 28, 2022
Safety 1 - April 28, 2022
12:45 p.m. - Zoom seminar session begins
1:00 p.m. - Opening remarks by J. Eric Shereda, PE, CONSOL Energy and Chair, Pittsburgh Section
1:05 p.m. - Haul Truck Safety: NIOSH Research Update; presented by Jon Hrica, Pittsburgh Mining Research Division, email: jhrica@cdc.gov
Abstract: Each year, haul truck accidents account for a large portion of mining injuries and fatalities. To better understand why these accidents continue to occur, researchers from NIOSH utilized a cognitive task analysis methodology to identify the user requirements of surface haul truck operators and assess differences in perceptions between operators, managers, health and safety professionals, trainers, and maintenance personnel. Additionally, researchers used the critical decision method to focus on better understanding the cognitive demands, decision-making, and problem solving during nonroutine incidents. The preliminary results of this study identify and explore themes within the broad categories of hazards, skills & expertise, and training and provide detailed accounts of nonroutine incidents such as near-misses, loss of control, and collisions. These accounts reveal insights into operator decision making and event progressions that can then be used to build more realistic training scenarios and address hidden hazards and root causes of these incidents. These results, along with potential solutions offered by study participants, can inform future research and help identify creative interventions that can be used by mine operators to address haul truck safety issues.
1:25 p.m. - Back to Basics: An Overview of Methods and Parameters to Evaluate Detection Performance and Validation of Collision Warning and Avoidance System in Surface Mining; presented by Joseph Bickson, email: jbickson@cdc.gov
Abstract: Between 2005 and 2021, a NIOSH internal review showed that haul trucks were involved in 54 incidents at surface mines in the United States. Haul truck collision warning and avoidance systems (CXS) can assist in preventing accidents at surface mines. CXS use technologies to detect people or objects and alarm to alert haul truck operators. Robust testing can help ensure that they detect objects without excessive false positive alarms. Testing and validation would increase confidence in and encourage implementation of a CXS. Researchers from NIOSH reviewed documents related to the evaluation and validation of CXS with two objectives: (1) to identify methods and parameters used to evaluate detection performance and (2) to identify gaps in CXS test methods and in detection performance. Stakeholders can use the findings from this research to guide implementation of CXS to improve safety at surface mines.
1:45 p.m. - Analysis of U.S. Surface Mining Haul Truck and Mobile Equipment Accidents; presented by John Homer, Pittsburgh Mining Research Division, email: jhomer@cdc.gov
Abstract: Powered haulage and haul truck-related fatal accidents are among the most frequent at surface mines. Industry organizations developed guidance on accident scenarios to address haul truck and mobile equipment collision-related accidents. However, there is a need to investigate accident data to prioritize these scenarios and identify factors relevant to developing validation methods for collision warning/avoidance technologies and determining their capabilities and limitations. Standards and effective validation methods are necessary for improving system efficacy within mining operations and promoting industry adoption. To address these needs, researchers from NIOSH investigated available powered-haulage and machinery-related fatal accident reports documented by the Mine Safety and Health Administration (MSHA). Their objective was to gain a perspective for informing the development of test protocols and validation methods through determining the most prevalent accident scenarios and related factors. Our findings afford insight for addressing the most prevalent haul truck scenarios and relevant factors within U.S. surface mining environments.
2:05 p.m. - Comparison of Thermal Runaway Pressures within Sealed Enclosures for Nickel Manganese Cobalt and Iron Phosphate Cathode Lithium Ion Cells; presented by Thomas Dubaniewicz, Pittsburgh Mining Research Division, email: tcd5@cdc.gov
Abstract: Mining vehicle manufacturers are developing lithium-ion (Li-ion) battery electric vehicles as an alternative to diesel-powered vehicles. In gassy underground mines, explosion-proof (XP) enclosures are commonly used to enclose electrical ignition sources to prevent propagation of an internal methane-air explosion to a surrounding explosive atmosphere. Li-ion batteries can create pressurized explosions within sealed enclosures due to thermal runaway (TR). NIOSH researchers measured TR pressures of nickel manganese cobalt (NMC) cathode type 18650 Li-ion cells, model MH1, as a function of free space within sealed enclosures and observed an inverse power relation-ship. TR pressure-rise rates, gas quantities, and temperatures were also measured. A confined NMC cell with 92.5 mL of free space produced 232 bar of pressure, far exceeding minimum pressure containment specifications for conventional XP enclosures. Approximately 287 times the cell volume of free space would be needed to reduce the TR pressure of these cells to 8.62 barg (125 psig) per U.S. Code of Federal Regulations, Title 30, Part 18. The NMC cell TR pressures were significantly higher than those measured previously for iron phosphate cathode Li-ion cells under comparable confinement conditions.
2:25 p.m. - Closing remarks
2:30 p.m. - Close of Zoom session - Next webinar: May 3, 2022
Dust - May 3, 2022
12:45 p.m. - Zoom seminar session begins
1:00 p.m. - Opening remarks by J. Eric Shereda, PE, CONSOL Energy and Chair, Pittsburgh Section
1:05 p.m. - Laboratory Investigation of Respirable Coal Dust Deposition and Suppression Process in a Confined Chamber; presented by Hua Jiang, Pittsburgh Mining Research Division, email: qla6@cdc.gov
Abstract: Respirable coal dust has been long recognized as a leading cause of multiple lung diseases. Efforts aimed at reducing dust concentration in underground coal mines have been made in the last few decades. However, increases in coal workers’ pneumoconiosis incidence rates over the last 20 years among U.S. miners are concerning. Dust deposition and water spray suppression are two types of dust removal mechanisms in underground mining activities. In this study, laboratory tests were conducted to investigate the respirable dust decay characteristics during deposition and suppression processes in a confined dust chamber. The dust concentration and size distribution were monitored continuously throughout each 60-minute test. A number-basis particle size distribution was used for analysis to capture the changes of smaller size fractions within the investigated dust sample. This study found that around 62.1% of respirable dust particles were deposited at the end of the deposition test. In addition, the final deposition rate for very fine particles can be less than 20%. The results from the suppression test indicate that larger particles were removed quickly; however, sub-micron particles remain suspended through the 60-minute water spray, and particles under 0.5 µm can be considered irremovable dust under single-spray operation conditions. This study also observed the resuspension of a significant amount of sub-micron particles by the water spray. The results of this study provide basic information for improving dust control strategies and can be utilized to improve the water spray performance for reducing airborne dust levels.
1:25 p.m. - Statistical Analysis of Diesel Particulate Matter and Silica for Underground Stone Mines; presented by Marcia Harris, email: ztv5@cdc.gov
Abstract: Large-opening stone mine ventilation is characterized by high ventilation quantities with low resistances. Stone operation ventilation systems differ with large variations in numbers of entries, depths of operations, slopes of deposit, use of benching, and use of natural ventilation. Past research suggested these mines face three primary ventilation challenges: moving adequate volumes of ventilation air, controlling and directing the airflow, and planning ventilation systems that work well with production requirements.
1:45 p.m. - Respirable Crystalline Silica Exposures Among United States Metal and Non-Metal Mines, 2000-2019; presented by Shilpi Misra, email: smisra@cdc.gov
Abstract: In United States metal and non-metal (MNM) mines, respirable crystalline silica (RCS) exposures are prevalent and a leading indicator of respiratory disease. 55,265 full-shift personal air samples from a public dataset maintained by MSHA were analyzed over the years 2000-2019. Descriptive statistics for RCS, percent silica, and dust concentration in respirable dust samples were examined by explanatory variables. The overall geometric mean (GM) for RCS exposures was 28.9 μg/m3 (GSD: 2.5) and the 95th percentile was 149 μg/m3. Personal exposures varied significantly by, sector, year, state, occupation, location, and commodity (P<0.001). Overall, the percentages of RCS exposures above the MSHA Permissible Exposure Limit (100 μg/m3) and NIOSH Recommended Exposure Limit (50 μg/m3) were 11% and 27%, respectively. Forty of 53 occupations with >50 samples each, had a NIOSH REL exceedance fraction of >20% (range: 20 to 57% exceedance). GM concentrations in 2018 (45.9 μg/m3) and 2019 (52.9 μg/m3) were significantly higher than the GM for all years prior (28.2 μg/m3). The prevalence of high exposures to RCS among MNM miners continues and may be increasing in certain settings and occupations.
2:05 p.m. - Wavelength Selective Portable Device for Quantifying Organic and Elemental Carbon in Diesel Particulate Matter; presented by David Parks, Spokane Mining Research Division, email: nij4@cdc.gov
Abstract: Underground workers in large-opening stone mines may be exposed to respirable crystalline silica (RCS) and diesel particulate matter (DPM) at levels above the regulatory limits set by the Code of Federal Regulations. These workers may be unknowingly subjected to conditions which contribute to respiratory diseases. This paper comprehensively examines the MSHA collected data to determine the extent to which RCS and DPM may be an issue in underground stone mines. Out of 522 sampled mines, there were 108 resulting RCS violations during 2000 – 2020. DPM was more prevalent than RCS in these mines with 382 citations when 929 mines were sampled during 2000 – 2020. DPM is usually the defining parameter for design of mine ventilation systems in large-opening underground stone mines. With this knowledge, focused attention can be directed to these mines so that appropriate prevention and mitigation techniques can be utilized to prevent stone miners’ exposure to RCS and DPM and subsequent respiratory diseases.
2:25 p.m. - Closing remarks
2:30 p.m. - Close of Zoom session - Next webinar: May 5, 2022
Safety 2 - May 5, 2022
12:45 p.m. - Zoom seminar session begins
1:00 p.m. - Opening remarks by J. Eric Shereda, PE, CONSOL Energy and Chair, Pittsburgh Section
1:05 p.m. - Findings from a Systematic Review of Fatigue Interventions: What's (Not) Being Tested in Mining and Other Industrial Environments; presented by Zoe Dugdale, Spokane Mining Research Division, email: nxl4@cdc.gov
Abstract: Fatigue and sleep deficiency remain key occupational health and safety concerns in many industries and subsectors, including in mining. Work schedules in the mining industry are often nonstandard, tasks can be physically and mentally demanding, and environments are some-times hot, poorly lit, and loud. These are all fatigue risk factors and can lead to cognitive impairment and subsequent safety critical events. The purpose of this systematic review was to identify fatigue interventions that have been tested on industrial shiftworkers and explore their effects and the factors that may influence their application in a mine. The protocol for this review adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Relevant studies published between 1980-2020 were identified by carrying out structured, systematic searches in electronic journal databases, consulting external subject matter experts, and manually reviewing the reference lists of a sample of studies. Articles were screened against pre-established inclusion criteria and appraised for methodological strength. Key characteristics such as occupational setting and job task, shift schedule, intervention type, outcome measures, and study findings and limitations were then extracted. Due to considerable heterogeneity in methods, participants, interventions, and findings, a narrative synthesis approach was taken. Two intervention types--lighting and training--were identified out of several frequently documented in other industries and sectors (e.g., planned naps, rest breaks, strategic caffeine use). Critically, no fatigue interventions were tested in mining. Our review provides strong evidence for bright light interventions at improving subjective sleep quality and reducing sleepiness in industrial shiftworkers. How-ever, there is insufficient evidence to posit the benefits of blue-light blocking glasses and sleep hygiene and alertness management trainings. Notable factors influencing the effectiveness of the lighting interventions included when and how often the interventions were administered and their duration. The training interventions were primarily affected by choices in design and delivery, and the relevance of information to workers. To improve effectiveness, interventions should be customized as much as possible for specific workers and with consideration for contextual factors within the workplace environment.
1:25 p.m. - Hand and Finger Injuries in the U.S. Mining Industry, 2011-2017; presented by John Heberger, Pittsburgh Mining Research Division, email: jvg4@cdc.gov
Abstract: Injuries associated with hands and fingers are highly prevalent in mining and identifying factors associated with these injuries are critical in developing prevention efforts. This study identifies nonfatal injury incidence rates, nature of injury, work activities, glove usage, and sources of hand and finger injuries in the U.S. mining industry, as reported to the Mine Safety and Health Administration (MSHA) from 2011-2017. Hand and finger injuries occur at a rate of 6.53 per 1,000 full-time employees, which is nearly double the rate of the next highest affected body part, the back. Most of the hand and finger injuries were classified as cuts/lacerations/punctures (53%) followed by bone fractures/chips (26%). Materials handling and maintenance/repair were common activities at the time of the incident with miscellaneous metals (pipe, wire, guarding) and hand tools as the primary sources of hand and finger injury. Although the information on glove use was limited, leather gloves were most often worn when an injury occurred. When worn, gloves were found to contribute to 20% of the injuries, indicating their potential to protect the hands, but also potentially put the hands at risk. Further research is necessary to determine performance requirements for gloves used in mining operations, specifically those offering cut and puncture resistance.
1:45 p.m. - Electromagnetic Emission Measurement of the Shielded Metal Arc Welding (SMAW) Process; presented by Lincan Yan, Pittsburgh Mining Research Division, email: jjy9@cdc.gov
Abstract: Electromagnetic emissions from electrical devices may interfere with electronic safety systems or other devices in the mining environment. This electromagnetic interference (EMI) may cause unwanted changes in the performance of the affected devices and may cause safety issues for miners. To minimize the risk of EMI, the National Institute for Occupational Safety and Health (NIOSH) has conducted research quantifying the electromagnetic emission of several equipment which might be used in mining environment. Previous researches have shown that welding arcs can give off ultraviolet (UV) radiation, visible light, and infrared (IR) radiation that can cause health problem on skin and eyes. In this study, the electromagnetic emissions of the shielded metal arc welding (SMAW) process was monitored and measured. Several factors including operating mode (AC, DC+, DC-), current setting (low, med, high, max), and electrode type were investigated to compare their effect on emission level. The test shows that the emission level from the welding process can be affected those factors. The test data also shows that among those factors, the operating mode has more influence on emission level than current setting and electrode type do. The information in this paper can be useful for the mining industry to better understand the emission in microwave and radio wave range from a SMAW welder.
2:05 p.m. - Optimization of Auxiliary Fan Placement for Large-Opening Underground Stone Mines; presented by Vasu Gangrade, Pittsburgh Research Mining Division, email: vgangrade@cdc.gov
Abstract: Large-opening stone mines often rely on natural ventilation and a network of auxiliary fans to produce adequate ventilation conditions in the mine instead of main mine fans, which are commonly utilized in coal mines. Large air volumes in underground stone mines, poor ventilation practices, and low operating budgets for mine ventilation potentially leave mine workers at risk to dust, silica, and diesel particulate matter (DPM) emissions exposure. To help improve mine ventilation practices, the optimal auxiliary fan location for maximum airflow production from a ventilated intersection was determined using a combination of field measurements and computational fluid dynamics (CFD) modelling. Airflow quantity and fan data were collected at a partner mine to be applied as CFD model input parameters and comparison data for model validation. A six-foot diameter auxiliary propeller fan was introduced into the validated CFD model at three locations around an intersection with established ventilation flow perpendicular to the fan direction. Placing the fan on the opposite side of the intersection from the target active face area, produced the highest ventilation flow rates at the downstream locations tested and produced the lowest amount of air re-circulation. The findings summarized in this paper show how an optimized auxiliary fan placement may increase the net effective ventilation flow rate by 70,000 cfm and reduce recirculation by 26%, maximizing the potential output of large-opening stone mine ventilation systems and decreasing mine workers’ exposure to airborne contaminants.
2:25 p.m. - Closing remarks
2:30 p.m. - Close of Zoom session, end of series