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To minimize the equipment operator?s respirable dust exposure in enclosed cabs of mobile equipment by install-ing cab filtration and pressurization systems and by keep-ing doors and windows closed. Background Enclosed cabs are used on mobile equipment to protect operators from health and safety hazards. The primary health concern is overexposure to respirable dust. Examples of such equipment in mining include drills, dozers, haul trucks, and other equipment. When equipment is new, the operator?s dust exposure is normally at acceptable levels. As the equipment ages and gaskets and seals deteriorate, the air quality inside an enclosed cab can reach a point where it is no longer at acceptable levels for the equipment operators. In an effort to improve the air quality in enclosed cabs of older mining equipment, NIOSH has been performing research to retrofit cabs with new filtration and pressurization systems. Over the past few years, this research has shown that retrofit systems can substantially improve the cab?s air quality back to safe and acceptable levels. How-ever, this is only possible when a positive cab pressure is achieved and maintained. Thus, when a cab door or window is opened, the cab pressure drops to zero and the cab filtration and pressurization system is rendered ineffective. During a recent field study, the magnitude of this impact was noted when a drill operator repeatedly opened the cab door throughout the course of the drill cycle. Upon closer examination, it was determined that the cab door was being opened to manually guide the next drill steel into place each time an additional section of steel was needed to drill deeper holes.

Sep 1, 2008

In 2006, a total of 280 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA).1 Metal mines were the smallest mining commodity sector, comprising 1.9% of all mining operations. ? Gold mines comprised 46.8% (n=131) of all metal mining operations. Other common types of metal mines were copper ore (n=34; 12.1%), and iron ore (n=33; 11.8%). Nevada had the largest number of metal mines (n=53; 18.9%), followed by Alaska (n=31; 11.1%).

Sep 1, 2008

In 2005, a total of 7,111 sand and gravel mining operations reported employment to the Mine Safety and Health Administration (MSHA). ? Sand and gravel mines were the largest mining sector, comprising 48.5% of all mining operations. ? Sand and gravel mines were found throughout all 50 states and Puerto Rico.

Sep 1, 2008

By Sean Gallagher

This report was written in an effort to provide better control measures for low back pain (LBP) and low back disability in the mining industry. There are numerous factors associated with development of LBP, many of which can be effectively controlled while some cannot. Better job design is promoted as the best method of reducing cases of LBP and can also reduce the disability (i.e., lost time from work) associated with LBP when it happens. The report draws attention to what is currently known about LBP, what the causes are thought to be, and discusses recent back injury trends in the mining industry. Research describing unique physical demands in mining, such as the capabilities and limitations of working in awkward postures, is also presented. Methods that can be used to prevent initial LBP episodes are provided, including facilities design and layout for materials and supplies, use of mechanical-assist devices, improved design of lifting tasks, and better seat design. Methods of reducing the disability associated with LBP (including workplace design, proactive return-to-work efforts, communication, and management commitment) are also discussed. The report concludes that control of LBP and disability in mining requires a comprehensive approach to limit the repetitive loading that can occur on the low back due to manual materials-handling tasks and exposure to whole-body vibration (WBV). Specific recommendations include the following: ? Successful LBP prevention efforts require a proactive program that has strong management commitment and incorporates employee involvement. ? More efficient supply handling systems and use of mechanical-assist devices can greatly reduce exposure to hazardous lifting tasks. ? Lifting tasks should be designed to minimize low back stress. Tools to evaluate and redesign lifting tasks are presented. ? Improved seat design can reduce exposure to WBV and improve posture, leading to reduced LBP risk. ? The disability associated with LBP can be reduced. Getting the worker back on the job as quickly as possible is in the interest of everyone involved.

Sep 1, 2008

In 2005, a total of 263 metal mining operations reported employment to the Mine Safety and Health Administration (MSHA). Metal mines were the smallest mining commodity sector, comprising 1.8% of all mining operations. ? Gold mines comprised 46.0% (n=121) of all metal mining operations. Other common types of metal mines were iron ore (n=32; 12.2%), copper ore (n=31; 11.8%), and lead and/or zinc ore (n=16; 6.1%). ? Nevada had the largest number of metal mines (n=52; 19.8%), followed by Alaska (n=27; 10.3%).

Sep 1, 2008

To develop effective noise controls for continuous min-ing machines (CMMs) to reduce worker noise exposure. Background Noise-induced hearing loss (NIHL) is an occupational illness caused by chronic exposure to excessive sound levels. For underground coal mine workers, NIHL continues to be a serious health issue. Analysis of hearing loss data suggests that by retirement age, 70%?90% of U.S. coal mine workers will have a hearing impairment. Operated in the confined spaces of underground mines, large industrial mining equipment often produces sound levels that can be harmful to workers. Of all equipment used in underground coal mining operations, CMMs account for the most noise overexposures. To reduce the occurrence of noise over-exposures, engineering noise controls must be developed for the CMM.

Sep 1, 2008

By R. Karl Zipf

This report presents nearly all structural data available from explosion tests of 20-psi mine ventilation seals and concrete-block ventilation stoppings that were conducted by the National Institute for Occupational Safety and Health during 1997?2008. Although the seals tested were designed to meet the former federal 20-psi pressure design standard, the structural information contained herein on these seal tests will facilitate the analysis and design of coal mine seals that meet the new explosion pressure design criteria of 50 and 120 psi as set forth in the Mine Safety and Health Administration (MSHA)?s final rule on ?Sealing of Abandoned Areas.? The seal testing data are organized into six broad categories of seal structures based on the materials used and the construction method for those 20-psi seals: 1. Concretelike materials with steel reinforcement and reinforcement bar anchorage to rock 2. Pumpable cementitious materials of varying compressive strengths with no steel reinforcement and no hitching 3. Articulated structures such as solid-concrete-block seals and ventilation stoppings made of solid and hollow-core concrete blocks 4. Polymer and aggregate materials without hitching 5. Wood-crib-block seals with or without hitching 6. Articulated structures such as lightweight blocks with or without hitching This summary contains data on 52 different structures in the above categories?44 seals and 8 ventilation stoppings. The structural data sets include the applied loading on the tested seal represented by a pressure-time curve and, when available, the measured seal response represented by a displacement-time curve. The structural data sets enable the calibration and verification of numerical models of seal behavior at the 20-psi level, which may then facilitate future structural analyses of seal designs for the new 50- and 120-psi explosion pressure design criteria.

Aug 1, 2008

Objective: To provide a safe, practical, cost-effective method for measuring coal rib thickness during highwall mining.

Jul 1, 2008

Objective: To enable mine operators and mine inspectors to make quick and accurate measurements of the explosible nature of coal and rock dust mixtures.

Jul 1, 2008

By Susan M. Moore

Many challenges are faced by workers in lower-seam (42 inches or less) mines. The lower-seam heights confine mine workers to their knees as they perform their daily tasks such as installing roof bolts, delivering supplies, repairing belt, or cutting coal. Miners working in these lower seams often consider kneepads to be their only line of defense against knee injuries. However, healthy knees do not start and stop with kneepads. Other interventions such as changing postures, proper hygiene, and work station design may also be used to reduce mine workers? risks for developing knee injuries. Incorporating these and many other interventions into a mine worker?s ?way of life? is an important step to ensuring a long, healthy career and retirement. Keeping knees healthy is also a key aspect to reducing costs in low-seam mines as the industry battles rising health care costs, and training/recruitment of replacement workers is time-consuming and costly. Educating the workforce about the possible interventions to reduce knee injury risk is a primary objective for the National Institute for Occupational Safety and Health?s (NIOSH) Pittsburgh Research Laboratory (PRL). Therefore, NIOSH researchers, along with industry and academia, developed a training package to educate the mining community about some possible interventions beyond kneepads that may be used to help decrease knee injury rates. Increased awareness and simple changes are the first steps to reducing knee injuries.

May 1, 2008

Background: Frictional ignitions continue to be a problem facing the U.S. underground coal mining industry. Many methane igni-tions are associated with the impact of mining machine cutter bits on quartzitic material (e.g., sandstone) during the coal-cutting process. Most ignitions result in small methane-air fireballs often only a few feet in size and limited to the cutter head location. However, under certain conditions, frictional ignitions can lead to larger methane explosions and/or fires with the potential for causing serious injury or death to the mining machine operator and other nearby miners. The requirements for a frictional ignition are a flammable volume of methane-air and an ignition source. This source is usually the hot streak caused by the frictional impact of the mining bit on hard rock, and the frequency of occurrence increases with increased bit wear. Another possible ignition source is the fric-tional impact of rock on rock during a roof fall.

Mar 1, 2008

On September 4, 2007, Mine Safety and Health Administration, in alliance with the International Union of Operating Engineers and the International Association of Bridge, Structural, Ornamental, and Reinforcing Iron Workers, presented the first annual Mine Construction Maintenance and Repair?s Safety Contractor of the Year Award to Artisan Contracting, Inc., of Cape Girardeau, MO. Eligible contractors located throughout the United States were nominated. Artisan Contracting was nominated by Illinois Cement Company located in LaSalle, IL. Illinois Cement Company is a Division of Eagle Materials Inc., located in Dallas, Texas. Mr. Larry Frankum President of Artisan Contracting Inc., stated, ?While it is gratifying to receive a wonderful award such as this, we must not forget how fragile a good safety record is. We must constantly remain diligent in pursuit of maintaining safe work sites.?

Feb 1, 2008

The National Personal Protective Technology Laboratory (NPPTL) of the National Institute for Occupational Safety and Health (NIOSH) has undertaken a collaborative study with the Mine Safety and Health Administration (MSHA) to determine how well self-contained self-rescuers (SCSRs), deployed in accordance with Federal regulations (30 CFR 75.1714), withstand the underground coal mining environment with regard to both physical damage and aging. Apparatus tested included the CSE SR-100, the Draeger OXY-K Plus, the MSA Life-Saver 60, and the Ocenco EBA 6.5 and M-20. This report presents findings regarding laboratory-tested SCSRs in the tenth phase of testing, from July 2004 to March 2006. The SCSRs were tested on a breathing and metabolic simulator and on a human subject walking on a treadmill. The tests performed in this study are not the tests used for certification (Title 42 of the Code of Federal Regulations, Part 84). The tests performed in this study continue until the apparatus are empty to enable comparison of new versus deployed apparatus. The method for obtaining deployed SCSRs for this evaluation was not a random selection from the deployed population of SCSRs. We sought older apparatus with visible environmental impact rather than newer apparatus, and we attempted to sample a wide range of deployment modes. Although the results of these tests are useful for observing performance of the tested SCSRs, they are not representative of all deployed SCSRs. This report is the last of 10 report phases begun in 1982. Previous reports describe phases 1 through 9 [Kyriazi et al. 1986; Kyriazi and Shubilla 1992, 1994, 1996, 2000, 2002, 2004, 2006] A new evaluation protocol, with revised sampling strategies, test methods, and reporting procedures, is currently being designed to enhance the applicability of the results. The results of these studies suggest that the large majority of SCSRs that pass their inspection criteria can be relied upon to provide a safe level of life support for mine escape purposes. However, the storage and handling in the mining environment seems to have caused performance degradation in some of the apparatus. In this phase, phase 10, we found some CSE SR-100s (93 tested) that exhibited high CO2 levels, stuck-together breathing hoses, starter-O2 failure, breathing hose punctures and tears, high breathing pressures, and loose particulates in the breathing hose. The loose particulates caused coughing in human-subject tests. One MSA Life-Saver 60 (20 tested) in this phase had a stuck-open relief valve. One Ocenco EBA 6.5 (50 tested) had an unattached O2 supply hose. An unexplained phenomenon occurred with two Ocenco M-20s (20 tested): low O2 flow rates preventing their successful use. Almost all of the failures noted involved units that failed their inspection criteria.

Jan 6, 2008

By Mark Colwell, Christopher Mark

This paper summarises the results of a research project whose goal was to provide the Australian coal industry with a rib support design methodology and software tool that could be utilised by suitably qualified colliery staff. The project was primarily funded by Australian Coal Association Research Program (ACARP) and further supported by several Australian longwall operations. The outcome of the project is a design methodology and software tool called, Analysis and Design of Rib Support (ADRS). ADRS is an empirical technique, which recognises that several geotechnical and design factors affect ribline performance and in addition that operational and safety issues essentially dictate the level of performance required. Therefore, the design recommendations associated with ADRS are specific to the Australian coal industry; however the procedure(s) for data collection and analysis could be applied to other countries' 'underground coal industries. Case history data were compiled from 34 longwall and two bord and pillar operations resulting in 204 case histories with each case history data set being defined by approximately 130 individual data fields. In addition monitoring (incorporating stress cells and extensometers) was undertaken at 10 collieries to assess and quantify the effectiveness of different rib support patterns and hardware on rib performance. The monitoring sites allowed for an improved understanding of the mechanisms of rib failure and degradation in terms of its interaction with the installed support and at the various stages of the mining cycle. The design methodology deals with both mains development and gateroad development specific to Australian longwall mines. This paper focuses on longwall gateroads subjected to abutment loading and in particular the travel road which becomes the tailgate of the subsequent panel. The statistical analyses associated with these cases suggested that the level of rib support should be based primarily on the development height and the pillar stress level. The ADRS software guides users through the design process, allowing them to develop rib support plans based on sound science and a broad base of in-mine experience To the best of the authors’ knowledge ADRS is the first systematic rib support design technique to be developed for any country’s underground coal industry. The development and use of empirical models in mining have substantially contributed to improving safety and productivity. ADRS further demonstrates that empirical techniques are particularly relevant and beneficial in dealing with the complexities of geotechnical design associated with underground coal mining.

Jan 6, 2008

By James P. Ulery

Explosions in U.S. coal mines have caused death and injury to miners and destruction of workings since the first reported explosion in 1810. These explosions are caused when buildups of explosive gas and/or dust in the mine are ignited by the presence of a flame or spark. Methane gas is inherently generated and held by adsorption in coal and is normally liberated during mining. Because this gas is explosive in the range of 5%–15% by volume, fresh air is constantly supplied to the working face to prevent the methane/air mixture from reaching this explosive range. The required amount of ventilation air is based on estimates of gas release under normal conditions. Occasionally, unanticipated and unusually high emissions are encountered, which, despite normal ventilation controls, result in an explosive mixture that a spark from a cutting bit or electrical equipment can easily ignite. Investigations have shown that such emissions are often associated with anomalous geologic features or conditions. Although most operators are aware that certain geologic features may adversely affect productivity, few are aware of their potential as a gas emission hazard. This report presents a historical framework detailing the impact of geologic features on excess gas emissions and resultant mine explosions. It also provides operators with specific information on recognizing and alleviating potential hazards from methane emissions related to these geologic features.2

Jan 4, 2008

By Robert F. Randolph, Dana C. Reinke, Richard L. Unger

Purpose The NIOSH Hearing Loss Simulator is a software training and communication tool for promoting hearing loss prevention. It allows a user or trainer to demonstrate the effects of noise exposure on hearing without experiencing an actual noise-induced hearing loss. Estimates of the effects of different levels of noise exposure are based on the American National Standard Determination of Occupational Noise Exposure and Estimation of Noise-Induced Hearing Impairment, otherwise known as ANSI S3.44. This standard specifies the predicted hearing loss for noise-exposed populations of individuals based on risk factors that include gender, age, sound levels (in A-weighted decibels or dBA), and years of exposure. Algorithms specified in the standard were derived from empirical studies of populations that had no exposure to loud noise and other populations that had experienced various levels and durations of noise exposure. This manual explains the major objectives that can be addressed with the simulator and training scenarios that can be applied to real-life, real-worker scenarios. The majority of this guide explains the simulator's functions in detail. Simulator users are encouraged to read this manual while learning how to run the software. [ ] Training Objectives The main objective of the Hearing Loss Simulator is to increase motivation for taking effective hearing prevention action by demonstrating simulated noise-induced hearing losses. [The Simulator can also help teach the following facts about hearing loss. Hearing loss is affected by noise levels. Hearing loss worsens as the noise exposure duration increases. Hearing loss can become permanent. Hearing loss makes it harder to hear what others say. Most hearing loss is not caused by age. Speech is made up of both low and high pitch sounds. Hearing loss due to noise makes it harder to hear high pitch sounds. Hearing loss due to noise has less of an effect on hearing low pitch sounds.]

Jan 3, 2008

By Steven J. Schatzel, Gerrit V. R. Goodman, Robert B. Krog, C. Özgen Karacan, Gabriel S. Esterhuizen

Although longwall mining productivity can far exceed that of room-and-pillar mining, the total methane emissions per extracted volume associated with longwall sections are generally higher than those for continuous miner or pillar removal sections. Increased face advance rates, increased productivities, increased panel sizes, and more extensive gate road developments have challenged existing designs for controlling methane on longwalls. Methane control research by the National Institute for Occupational Safety and Health (NIOSH) recently examined a number of practices designed to maintain concentrations in mine air within statutory limits and consistently below the lower explosive limit. These included a reservoir modeling approach to predict methane inflows in gate road entries. The outputs sug­gested that emission rates in the gate roads decreased with the use of shielding boreholes and increased degasification time. Also, mining perpendicular to the face cleats liberated more gas into the mine workings, emissions were almost a linear function of Langmuir pressure and volume, and emissions were inversely related to sorption time constant. Subsequent simulations predicted changes in methane drainage using in-seam boreholes. The results showed that longer degasification times resulted in lower face emission rates. Premining degasification produced more methane than that produced during panel extraction, a fact attributed to the already decreased methane content of the coalbed. This work concluded that longer premining degasification periods would be more advantageous to the operator. The industry trend toward increasing longwall face width can produce increased methane emissions from the face due to a higher volume of cut coal on the face conveyor. Two methods were used to estimate face methane levels on longer faces. In the first method, segmented methane data were extrapolated for greater face widths. The second method estimated emissions contributions from the shearer, face conveyor, panel belt, longwall face, and ribs, and summed these for wider panels. Permeability changes in the gob behind the longwall shields were estimated using a NIOSH-developed numerical model. The results showed that permeability was highest near the edges and corners of the gob.

Jan 3, 2008

By Erica E. Hall, Robert H. Peters, Charles Vaught, Jon C. Volkwein

Coal workers’ pneumoconiosis is the leading cause of death due to occupational illness among U.S. coal miners. This disease is caused by miners’ exposure to excessive levels of respirable coal mine dust. A personal dust monitor (PDM) has recently been developed to provide near real-time feedback to miners regarding the level of respirable coal dust in the air they breathe. The main objective of this report is to document coal miners’ reactions to this device and how they make use of the information it provides. It summarizes a field study by the National Institute for Occupational Safety and Health that documented the opinions of 30 miners at 4 underground coal mines concerning the use of PDMs.

Jan 2, 2008

By S. M. Moore

Technological advances in underground coal mining have reduced fatalities but may not have reduced worker exposure to cumulative injury risk factors. The objective of this study was to evaluate the prevalence of cumulative injuries before and after the implementation of technological advances in underground coal mining and to make a general cost estimate for these injuries. A previously published algorithm was utilized to identify cumulative injuries within the Mine Safety Health Administration (MSHA) database for two data sets: 1983-1984 and 2003-2004. For both, the following were determined: the number and percentage of cumulative injuries, the average days lost, the average age at the time of injury, the average years of experience and the general cost estimate by body part. The percentage of cumulative injuries remained largely unchanged (37 percent in the 1983-1984 period and 33 percent in the 2003-2004 period). The average number of lost days due to cumulative injuries increased (36±55 days and 62±82 days, respectively), which may have been due to the increased worker age (seven years older in the 2003-2004 period), increased length of employment (seven years longer in the 2003-2004 period) or other factors such as changes in medical practices. Cumulative injuries to the back decreased by 10 percent, while cumulative injuries to the knee increased by 8 percent. The reduction in back injuries may be due to the implementation of assist devices, while the increase in knee injuries may be related to kneeling/crawling in low-seam mines. Cumulative injuries were found to remain a major financial burden on the industry. Recently, National Institute for Occupational Safety and Health (NIOSH) developed tools to assist mining companies with incorporating an ergonomics process into their existing health and safety programs. The participating companies have reported tremendous success. Therefore, it is recommended that ergonomics processes be implemented as a means to systematically identify and address the root causes to cumulative injuries and ultimately reduce costs.

Jan 1, 2008

By J. A. Organiscak

Enclosed cabs are a primary means of reducing the silica dust exposure of equipment operators at surface mines. The National Institute for Occupational Safety and Health (NIOSH) has investigated various factor effects on enclosed cab air filtration system performance. Factors experimen­tally investigated were intake filter efficiency, intake air leakage, intake filter loading (filter flow resistance), recirculation filter use and wind velocity effects on cab penetra­tion (inside to outside cab concentration ratio). Adding an intake pressurizer fan to the filtration system was also investigated. Results indicate that the intake filter efficiency and recirculation filter were the two most influential factors on cab penetration .Use of a recirculation filter significantly reduced cab penetration over the intake air filter by itself due to the multiplicable filtration of the cab interior air. Cab penetration was also affected to a lesser extent by intake filter loading and air leakage. Adding an intake pressurizer fan notably increased intake airflow and cab pressure while providing only minor changes to cab penetration.

Jan 1, 2008