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By Allen McComas, Frank Chase, Phyllip Worley

Longwall mining has gained the reputation as being the safest extraction method in underground coal mines. However, one of the most difficult tasks associated with longwall mining is moving the face once a panel is completed. Based on Mine Safety and Health Administration (MSHA) fatality reports since 1996, longwall face recovery operations have claimed the lives of 5 U.S. miners and have resulted in numerous injuries. Recovery operations can be hazardous because they involve moving large pieces of equipment in very confined spaces. They are also conducted in highly stressed ground conditions due to front abutment loads generated by panel extraction. Shield removal is the most hazardous operation during face recovery because miners are constantly exposed to the unpredictable gob edge. To protect the miners, one or more walking shields, cribbing and/or other supplemental roof and standing supports are typically employed as breaker line supports as each shield is removed. At the Harris No. 1 Mine in southern WV, mobile roof supports (MRS’s) have been used in lieu of traditional walking shields on 17 face moves since 1997. MRS’s are shield-like support units mounted on crawler tracks and are commonly used during room-and-pillar retreat mining operations. For longwall recovery, the two biggest advantages that MRS’s have over traditional walking shields are that they are remotely controlled and are highly maneuverable. MRS’s have contributed to safer shield recovery and shorter move times at the Harris No. 1 Mine. This paper will address both the safety and the operational issues associated with MRS usage during shield recovery. It will also discuss new developments, including the use of the inherently safer battery powered MRS’s, which have been recently certified by the Mine Safety and Health Administration.

By Jerry Bennett

This report describes the results of a survey of current blast area guarding procedures at surface and underground metal/nonmetal mines. It features five case histories (two surface and three underground mines) of blast guarding methods considered to represent the best systems in use in the U.S. Mining Industry. Elements of an effective blast guarding system are presented along with recommendations for improvements in current blast guarding practices. Industrial and military surveillance and detection technology was reviewed to determine if parallel technology exists for immediate application to blasting site security. While it is concluded that immediate transfer of industrial security technology will be limited, a number of recommendations are advanced for new research to adapt some of that technology for application to the mining environment. Two research areas considered to offer the most potential for improved blast guarding are presented. They are, computerized personnel tracking and blast area intrusion detection using infrared, microwave or E-field type detection systems.

Jan 1, 1981

By Susanne Hering, Brent Kirby, Charles D. Litton, Tracy Allen, Kirk R. Smith, Rufus Edwards

In developing countries, high levels of particle pollution from the use of coal and biomass fuels for household cooking and heating are a major cause of ill health and premature mortality. The cost and complexity of existing monitoring equipment, combined with the need to sample many locations, make routine quantification of household particle pollution levels difficult. Recent advances in technology, however, have enabled the development of a small, portable, data-logging particle monitor modified from commercial smoke alarm technology that can meet the needs of surveys in the developing world at reasonable cost. Laboratory comparisons of a prototype particle monitor developed at the University of California at Berkeley (UCB) with gravimetric filters, a tapered element oscillating microbalance, and a TSI DustTrak to quantify the UCB particle monitor response as a function of both concentration and particle size and to examine sensor response in relation to changes in temperature, relative humidity, and elevation are presented here. UCB particle monitors showed good linearity in response to different concentrations of laboratory-generated oleic acid aerosols with a coarse (mass median diameter, 2.1 µm) and fine (mass median diameter, 0.27-0.42 µm) size distributions (average r2 = 0.997 ± 0.005). The photoelectric and ionization chamber showed a wide range of responses based on particle size and, thus, require calibration with the aerosol of interest. The ionization chamber was five times more sensitive to fine rather than coarse particles, whereas the photoelectric chamber was five times more sensitive to coarse than fine. The ratio of the response between the two sensors has the potential for mass calibration of individual data points based on estimated parameters of the size distribution. The results demonstrate the significant potential of this monitor, which will facilitate the evaluation of interventions (improved fuels, stoves, and ventilation) on indoor air pollution levels and research on the impacts of indoor particle levels on health in developing countries.

By Robert B. Fulton

Summary of data and estimates for 52 fluorspar properties in the following 13 foreign countries: Mexico Thailand China (PRC) Morocco Tunisia Italy Spain South Africa France United Kingdom Kenya Namibia Federal Republic of Germany Data includes deposit type, resource tonnage and grades, mining and beneficiation methods, annual production, fluorspar products and by-products, manpower requirements, capital and operating cost estimates. For operating properties, engineering and cost data have been developed for present and anticipated levels of production. Hypothetical operations have been assumed for undeveloped deposits.

Jan 1, 1984

By William J. Campbell

This report describes a Bureau of Mines study undertaken to determine the applications and limitations of solution techniques as a general method of fluorescent X-ray spectrographic analysis. Systematic errors due to variations in particle size, surface preparation, and sample inhomogeneity are eliminated by the use of solutions. The range of applicability of fluorescent X-ray spectrography is increased in two ways: (1) Samples in the form of wire, filings, turnings, etc., can be analyzed as solutions, and (2) samples submitted as solutions can be analyzed as received 0 The lower limit of detectability varies from 0.14 gram per liter for sulfur, atomic number 16, to 0.0015 gram per liter for strontium, atomic number 38. Most elements have limits of detectability between 0.02 and 0.002 gram per liter.

Jan 1, 1959

By Joseph T. Singewald

The term "titaniferous magnetite" is used to designate those magnetic ores of iron that carry more than 2 or 3 per cent of titanium. Large and easily workable deposits of these ores occur in different parts of the world, and have attracted attention for many years. Under present furnace practice, however, the smelting of these ores is both difficult and expensive, and for that reason they are not accepted by furnaces, so that the deposits are practically worthless. The problem of finding a feasible method of utilizing these ores has naturally been attractive, and numerous attempts have been made to solve it. Experiments to that end embrace two lines of investigation. The one that has been the more frequently tried is the elimination of the titanium from the ores, so as to make possible their smelting in the usual way. The other is the devising of a method of smelting by which titaniferous ores may be reduced as economically as are non-titaniferous ores. The former method involves a physical process, the latter a chemical process.

Jan 1, 1913

Provide an unobstructive means of measuring small changes in distance from roof to floor or from rib to rib of a mine opening and the rate of closure in order to help operators of under-ground mines detect hazardous ground conditions. Approach A small ultrasonic measurement system was developed to detect g round movement and define closure rates. How the System Works The system contains two parts: a transducer and a readout device. The small ultrasonic transducer, similar to an audio speaker diaphram, is plucked with an ultrasonic frequency every six seconds. This frequency wave is sent through the air and reflected back to the transducer off any surface at which the transducer is pointed. The amount of time needed by the ultrasonic wave to make this round trip is accurately measured using a precise oscillator / timer and is converted into a measure of distance. The accurate 6-second time interval is used to convert any subsequent changes in the reading to a rate of change in feet per minute. Two readings are then displayed alternately on the readout instrument.

Jan 1, 1984

By Alan A. Campoli

The U.S. Bureau of Mines conducted research to characterize longwall gob loading under bump-prone geologic conditions. Bureau-designed stress meters were installed in the floor rock beneath two longwall panels and coal pillars in the gate road between them. Gob and gate road pillar stress was monitored continuously by a state-of-the-art data acquisition system. The timing of the final destruction of the abutment pillar's load-bearing core was optimal, since the pillar is located between two gob areas and no longer of significant importance for ground control. Maximum stress was observed immediately in front of the longwall face, and this pressure quickly dropped as the face moved past the instruments. The center of the longwall panels regained significant overburden load, while the instruments located less than 100 ft from the edge of the panel showed little or no increase in pressure due to gob reloading.

Jan 1, 2010

By Ben E. Lindsly

The recovery or partial recovery of the oil remaining in oil sands after the usual methods of production have become unprofitable is perhaps the greatest problem in the petroleum industry today. The amount of this oil remaining in the sand is variously estimated by those familiar with the subject to be 25 to 90 per cent of the original content.2 Lewis3 states, "The estimate of 80 to 90 per cent of the oil left underground does not seem incredible."

Jan 1, 1926

By Elbridge W. Gresseth

Rock deformational structures in a deep mine were analyzed by petrofabric techniques to learn (1) the relative magnitude and direction of the principal stresses involved in tectonic deformations prior to mining, (2) the preferred orientation of rock planar discontinuities which define rock anistropy prior to mining, and (3) the relationship of mining-induced rock failure to inherent rock stresses and inherent rock anisotropy. Rock fabric elements used for petrofabric analysis consisted of bedding planes, faults, joints, fractures, foliation, sericite plane (001), quartz axis [0001], quartz deformation lamellae, and microfractures. Structures and structural symmetries from different areas within the mine and from different scales of observation were compared to learn the nature of rock anisotropy and the orientation of the principal stresses defined by rock deformations. Analysis of such fabric as regional and macroscopic faults, b-c joints, quartz [0001], sericite (001), and microfractures, indicate that during the epochs of tectonic deformation, the maximum and minimum principal stresses were horizontally oriented and acted along northwest and northeast axes, respectively. This condition of regional stress appears to have continued during folding and the associated period of faulting. The most recent tectonic deformation represents a rotation of the minimum principal stresses into a vertical position, as shown by the development of a tensile joint system, quartz deformation lamellae, and microfractures. Good interscale correlation and statistical homogeneity of tectonic fabric indicate a stress field homogeneity in this area during tectonic deformation. Rock physical anisotropy is genetically associated with tectonic fabric and consists of preferentially oriented planar discontinuities intersecting along a nearly vertical axis. The mining-induced deformations were correlated with the inherent rock anisotropy which either directly controls or greatly affects their development. This phase of rock deformation shows a greater degree of stress field heterogeneity than was the case with tectonic deformations This is explained as a result of nonconfinement afforded by underground openings and the increase in ground stresses due to mining activity"

Jan 1, 1968

By Nick Barton

When the Q-system was launched in 1974, the name referred to rock mass classification, with focus on tunnel and cavern support selection. Besides empirical design of support, the Q-value, or its normalized value Qc, has been found to correlate with seismic P-wave velocity, with deformation modulus, and with deformation. The Q-system provides temporary or permanent support for road, rail, and mine roadway tunnels and for caverns for various uses. It also gives relative cost and time for tunnel construction for a complete range of rock qualities. There are also indications that Q has captured important elements of the cohesive and frictional strength of rock masses, with Qc resembling the product of rock mass cohesion and rock mass friction coefficient.

Jan 5, 2007

This Bureau of Mines report contains the proceedings of a symposium cosponsored by the Bureau of Mines and the University of North Dakota concerning utilization and technology of Western coals and lignites. The symposium, the sixth in a series, comprised 12 papers.

Jan 1, 1972

By F. D. DeVaney

Metallurgists and coal-washing engineers have used heavy liquids for years in studying the characteristics of ores and coal. By such means true separations can be made between the various specific-gravity increments in the materials examined. To use of heavy liquids has permitted determination of the possible grades of tailings and concentrates by specific-gravity methods on any particular size, and therefore the size to which the ore must be crushed to free the valuable material. The simplicity of float-and-sink separation and the high degree of efficiency attained in the laboratory are factors that commend the method for commercial concentrations.

Jan 1, 1940

By Edward L. McHugh, Louis J. Denes, Jami M. Girard

A prototype portable hyperspectral imager that operates in the visible and near-infrared ranges of the electromagnetic spectrum was field tested at an open-pit mine. The tests were sponsored by the Spokane Research Laboratory, National Institute for Occupational Safety and Health, as part of an investigation of remote sensing technologies for use in detecting and monitoring conditions in surface mines that could lead to catastrophic slope failure. The spectro-polarimetric imager, built at the Carnegie Mellon Research Institute, employs an acousto-optical tunable filter (AOTF) to control wavelength, a phase retarder to measure polarization signatures, and a digital camera and computer to capture data. The spectral range of the instrument is 450 to 1000 nm at 10-nm intervals. High-resolution hyperspectral images of highwalls, outcrops, hand samples, and drill core were collected in the field. Spectra from the images closely matched those of specific minerals present and were used to classify the images. The field tests were designed to examine the feasibility of using spectral imaging to assist in compiling objective geologic maps of mine highwalls and other hazardous slopes. Results illustrate the capability of the method to discriminate materials within the image, validating the concept of simplified spectral imaging. A contributing factor in many slope failures is the presence and distribution of mechanically incompetent, clay-rich altered rock in slope faces. Spectral features of clays and other minerals are more distinctive in the short-wave and mid-infrared part of the spectrum; the capabilities of the instrument need to be extended into this range to apply the AOTF-based technology to common geologic materials. A field-portable hyperspectral imager could find broad application in remotely identifying diverse materials from solids and coatings to gases.

By F. D. DeVaney

Metallurgists and coal-washing engineers have used heavy liquids for years in studying the characteristics of ores and coal. By such means true separations can be made between the various specific-gravity increments in the materials examined. To use of heavy liquids has permitted determination of the possible grades of tailings and concentrates by specific-gravity methods on any particular size, and therefore the size to which the ore must be crushed to free the valuable material. The simplicity of float-and-sink separation and the high degree of efficiency attained in the laboratory are factors that commend the method for commercial concentrations.

Jan 1, 1940

This Bureau of Mines publication consists of an overview of the mine waste management research currently being conducted by the Bureau. The following papers, given at a Technology Transfer Workshop, emphasize the increasing importance of research related to the safety and environmental considerations of mine waste disposal In recent years. Current work related to legislation passed in the last 10 years and their subsequent standards includes the development of adequate monitoring systems, development of stability and seepage prediction and control techniques, control of runoff water, and control of leaching solutions. Selected topics are included here that cover coal mine waste disposal, embankment slope stability monitoring, flow failures of mine tailings impoundments, and controlled burnout of abandoned coal mine fires. The projects described provide a current documentation of problems being addressed.

Jan 1, 1981

By Bill York-Feirn

The Colorado Mine Safety & Training Program (MSTP), in late 2005, completed and began distributing two new training tools; one geared to underground coal mine foremen and the other to surface aggregate employees. Through strong partnerships with MSHA, Colorado Coal Mine Board of Examiners, Colorado Mining Association and the Colorado Rock Products Association, the MSTP continues to create innovative and interactive training tools for not only Colorado, but for the national mining community. "Although we shoot and produce these materials in Colorado, it's important to us to make sure they are useful nationally," said Bill York-Feirn, MS TP Manager. The interactive DVD program "Underground Mine Foreman Certification Study Guide (Coal)," was completed in October 2005. It won the 2005 Grand Prize at the MSHA National Training Materials Competition in Beaver, West Virginia. [ ] This program is fully based upon the requirements of Title 30 Code of Federal Regulations (30 CFR) Parts 48, 50, 70 and 75 for underground coal mine foremen. It contains eight modules plus immediate access to relevant laws in the appendix. Topics covered include: Federal Law, Practical Math Skills, Mine Gases, Ventilation Maps, and scenarios addressing a variety of practical mining concerns. The DVD is designed for self-¬paced study and practice.

Jan 1, 2006

By J. F. McIlwain

The Bureau of Mines has investigated fumes generated by selected welding electrodes used in mines in order to help determine their relative health hazard potential. Fumes were generated and collected in an enclosed chamber for subsequent generation rate and chemical constituent determination. Shielded metal arc electrodes from the following groups were tested: AWS types E308-16 and E310-16 stainless steel, ECoCr-A Co-Cr hardfacing alloy, ENiCr Ni, an Mn-Cr buildup alloy, E7018 carbon steel, and EII018-M low-alloy steel. Flux-cored wire electrodes of this last group also were tested. Fume generation rates and the chemical composition of the fumes were measured. From these data, exposure in-dices were determined, which give a relative measure of the health hazard potential of using the electrodes. The effect of welding onto build-up alloy layers on the fume composition also was examined for five of the higher alloy groups.

Jan 1, 1987

By J. E. Chilton, T. Mal

Methane monitoring at the mine face is essential to assure a safe work environment in underground coal mines. Machine-mounted methane monitors must be used to continuously monitor methane levels during mining. Monitors used on mining machines must be approved by MSHA and properly maintained to provide protection for workers (30 CFR 75.342). To provide protection the instrument must give accurate readings of current methane levels. Accuracy is maintained by calibrating the instrument with a standard gas at least once every 31 days. Instrument “response time” determines how quickly measurements will change to reflect current concentrations. At present there are no criteria for measuring the response time for a ma-chine-mounted methane monitor while underground. This study examined a procedure for measuring the response time of a machine-mounted methane monitor. Response times were measured using methanometers obtained from three different manufacturers. The effects of the measurement technique and methanometer sensor head design on response time measurements are investigated. Techniques for reducing variation in response time measurements are discussed.

By Donald E. Redmon

Industrial engineering departments perform staff duties and are most effective when sincerely supported by management. In accordance with the needs and desires of the mining companies involved, various industrial engineering functions have been adopted widely at western metal mines during the period 1950-60. Newly organized departments usually conduct method and equipment studies, work-measurement programs, and establish and maintain production standards. Supervisor-training programs and courses are effective in showing the relationship between supervisory responsibility and the purpose for which industrial engineering is practiced. Industrial engineering staffs of western metal mines are composed predominantly of personnel from within the companies. Experienced industrial engineers, not necessarily experienced in mining, frequently are hired by a company to help establish the department. Management consultants frequently are called upon to advise management and instruct department personnel in industrial engineering practices. Some departments have developed satisfactory industrial engineering programs without benefit of formal industrial engineering training or advice.

Jan 1, 1962