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By D. B. Dow

"In the natural-gas Gasoline industry, the methods used in determining the amount of gasoline in natural gas are many and varied; they include the specific-gravity test, laboratory tests involving absorption, charge in volume of the gas or in the absorption medium, absorption in charcoal with subsequent distillation, compression of the gas which results in the condensation of the gasoline, and the absorption of the gasoline vapors in an absorption oil, from which the gasoline is distilled and measured. Each of these various tests has advantages, and disadvantages. It is however, conceded in the industry that the tests in which the gasoline is obtained and measured as such are the more reliable.This paper deals with certain factors which should be considered in making absorption tests using ""mineral seal oil"" as an absorbent; this method of testing is widely used not only in the field, but in control work in absorption gasoline plants where the gasoline content of the intake and discharge gas is determined daily. In control work it is frequently found that the plant produces more gasoline than the tests show, which gives the plant the appearance of making more gasoline than is actually present in the gas treated, or in other words operating at more than one hundred per cent efficiency. Obviously then, the tests as made in these cases are in error, and in hope of correcting some of these variances, the following factors have been studied at the U. S. Bureau of Mines petroleum station at Bartlesville, Oklahoma."

Aug 1, 1920

By C. Özgen Karacan

Methane emissions from a longwall ventilation system are an important indicator of how much methane a particular mine is producing and how much air should be provided to keep the methane levels under statutory limits. Knowing the amount of ventilation methane emission is also important for environmental considerations and for identifying opportunities to capture and utilize the methane for energy production. Prediction of methane emissions before mining is difficult since it depends on a number of geological, geographical, and operational factors. This study proposes a principle component analysis (PCA) and artificial neural network (ANN)-based approach to predict the ventilation methane emission rates of U.S. longwall mines. Ventilation emission data obtained from 63 longwall mines in 10 states for the years between 1985 and 2005 were combined with corresponding coalbed properties, geographical information, and longwall operation parameters. The compiled database resulted in 17 parameters that potentially impacted emissions. PCA was used to determine those variables that most influenced ventilation emissions and were considered for further predictive modeling using ANN. Different combinations of variables in the data set and network structures were used for network training and testing to achieve minimum mean square errors and high correlations between measurements and predictions. The resultant ANN model using nine main input variables was superior to multilinear and second-order non-linear models for predicting the new data. The ANN model predicted methane emissions with high accuracy. It is concluded that the model can be used as a predictive tool since it includes those factors that influence longwall ventilation emission rates.

As part of the U.S. Bureau of Mines (USBM) program to characterize subsidence this combination of software and hardware has been used to remotely monitor overburden response to longwall mining. Background The principle of time domain reflectometry (TDR) is being used by the USBM to monitor strata displacements induced by mining. This capability has been enhanced by the availability of cable testers with serial communication modules that allow users to get TDR records in digital form. Actual field installations involve coaxial cables that arc hundreds of meters long, and the many records obtained when monitoring such long cables on a daily basis motivated development of software to view interactively and compare waveforms and to analyze signature changes. Time domain reflectometry (TDR) was developed in the 1960's as a method to locate discontinuities in coaxial transmission cables. The concept has been extended to measurement of properties of materials into which probes are embedded, such as water content of soil, and evaluation of coaxial cable dielectric behavior. This technique was adapted by the USBM in 1975 for use in checking the movement of rock during underground mining. Coaxial cables are grouted into a rock mass that is expected to cave, and progressive rock movement causes the cable to deform. Consequently, there is a progressive change in cable electrical properties that produces changes in TDR pulse reflection signatures. TDR technology has been advanced by Northwestern University to the point where it is now possible to distinguish shear deformation from tensile deformation, and to quantify rock mass displacements, by analyzing these changes in TDR signatures.

Jan 1, 1993

By Raja V. Ramani, Robert L. Frantz

"In response to the U.S. Bureau of Mines (USBM) Request for Proposal (RFP) for "" the establishment of a Generic Mineral Technology Center (GTC) in Respirable Dust,"" the Mining and Mineral Resources Research Institutes (MRIs) at The Pennsylvania State University (PSU) and West Virginia University (WVU) in association with participating MRIs at Massachusetts Institute of Technology (MIT), and the University of Minnesota (UMN) have prepared the comprehensive research program described herein. Michigan Technological University (MTU) joined the Center as an affiliate after its inception. This program was developed with recognition of the stated objective of the Federal Mine Safety and Health laws which is to "". . . permit each miner the opportunity to work underground during the period of his entire adult working life without incurring any disability from pneumoconiosis or any other occupation-related disease . . . .""Exposure to respirable contaminants in mine atmospheres has long posed a serious hazard to miners. The control of these hazards, some of which can have sudden and catastrophic consequences and some others, slow and long enduring, has been a major concern for labor, management and the government. This concern has manifested itself in four mechanisms of control -- (1) regulatory control through minimum standard setting by the passage of mine health and safety laws, (2) engineering control through design and operation of mines according to the best recommended practices, (3) interaction of dust and lung control through periodic physical examinations, wearing personal protection devices, etc., and (4) legal and social control through workman's compensation laws for occupation related health deterioration."

Aug 31, 1989

By Thomas V. Falkie, R. Venkataramani

Underground coal winning operations can broadly be classified as conventional, continuous, and longwall mining. In conventional mining, the operations of cutting, drilling, blasting, loading and hauling, and roof support are performed in that sequence in each working face in a work area. The major difference between continuous and conventional mining is that the coal is cut and loaded by a continuous miner in the former, thereby combining the unit operations of cutting, drilling, shooting, and loading into one. Longwall applications have been viewed with great interest in recent years, and although at the end of 1970 there were only 37 longwall installations in the U. S. with combined production of less than 4 percent of underground total, there is no question about the growth potential of longwall in the United States. Increased capacity, versatility, and power characterize continuous miners today. Although continuous miners have outsold conventional gathering-arm type loading machines for some years, the latter, in the new extra-high capacity types, are continuing to find wide use. Whether the mining system is continuous or conventional, the haulage units may include six-wheel articulated shuttle cars, tractor-trailer units, or extensible belt and bridge-conveyor systems, all tending to increase the productivity of the face units. The decision as to which to choose - continuous or conventional mining - is complicated, and both systems are capable of high production rates. Most continuous miners in use today have a revolving pick-mounted drum to cut the coal and a gathering arm loading unit. Functionally, there is little difference between the loading unit in a

Sep 1, 1972

By R. V. Ramani, R. Bhaskar

One of the primary means of .control of health hazards from respirable contaminants in mine atmospheres is through design and operation of mines to meet mine health and safety regulations and recommended practices. A U.S. National Academy of Sciences study concluded that for significant progress in coal mine dust control, research should be directed more toward obtaining fundamental understanding of the origin, transport and characteristics of respirable coal mine dust. Theoretical and experimental studies on transport of dust in mine airways, particularly coordinated efforts to validate theory with practice, are scarce. Some empirical models, developed on the basis of experimental data, are available but these models cannot be applied to new .conditions. The purpose of this paper· is to present the results of theoretical and experimental studies on the transport and deposition of dust in mine airways. This study is a part of an on-going research project in the Generic Mineral Technology Center on Respirable Dust. In the paper, the assumptions of the modeling phase of the project and the development of a convection-diffusion equation for dust transport in mine airways will be outlined. The important aspect of the modeling effort.is the capture of the deposition phenomenon. The experiments performed under controlled conditions in a typical mine airway as well as under normal mine operating conditions will be discussed. The comparison of the model predictions ·with experimental results will be made to identify critical areas of agreements and deviations. The implications of the findings and areas for further research and development will be identified.

Jan 1, 1990

By D. Dolinar, T. P. Mucho

Horizontal stresses are caused by global plate-tectonic forces. During 1995 alone they were largely responsible for the closing of two longwall mines in the United States. This paper presents six case histories from Pennsylvania, West Virginia, Kentucky and Alabama. In each case, a mine encountered roof falls or difficult ground conditions at the headgate caused by horizontal-stress concentrations. The problems are detailed, and the control measures adopted are described. In most cases, nearby longwall panels without stress concentrations were trouble free. The paper also discusses detailed measurements that were made at two adjacent Pennsylvania longwalls. One headgate was oriented to avoid a horizontal-stress concentration, and the other was not. Eliminating the stress concentration dramatically reduced roof support loads and roof deformation. The paper concludes that proper panel orientation and sequence is the key to maintaining headgate ground control. The optimum orientation is not parallel to the maximum horizontal stress, as previously thought, but rather it is 20° in the stress shadow of the gob. Other stress-control techniques, including artificial support, are briefly discussed.

By Russell C. Frith, David C. Oyler, Dolinar Dennis R., Christopher Mark

Unusual circumstances may require that a longwall retreat into or through a previously driven room. The operation can be completed successfully, but there have been a number of spectacular failures. To help determine what factors contribute to such failures, a comprehensive international database of 131 case histories has been compiled. The cases include six failures where major rock falls occurred in front of the shields, and seven even more serious failures involving major overburden weighting. The case studies suggest two types of room failure mechanism. The first is a roof fall type failure caused by loading of the immediate roof at the face as the fender or remnant longwall panel narrows. The second is an overburden weighting type failure caused by the inability of the roof to bridge the recovery room and face area, and affecting rockwell above the immediate roof. The data indicate that the roof fall type of failure is less likely when intensive roof reinforcement (bolts, cables and trusses) is employed together with higher-capacity shields. The overburden weighting failures, in contrast, occurred when the roof was weak and little standing support was used. Weighting failures were not greatly affected by the density of roof reinforcement. In one of the overburden weighting cases, in a Pittsburgh coal bed mine, stress cell, convergence, bolt load and extensometer data have been used to analyze the failure in detail. Key words: coal mining, ground control, longwall, recovery room.

By Michael S. Wieland

The work-principle method was developed for theoretically resolving toxic fumes from non-ideal charge formulations. The whole description of a wanted process refers to macroscopic changes resulting from removing and imposing constraints that work one at a time to chronologically render trajectory terminal (key) states. The trajectory resolution utilizes a thermodynamic quasi-potential or negative work function, and numeric results require some appropriate standard thermodynamic (equilibrium) reaction code TDRC. The underlying method is unable to restrict reactions, tailor the work output or resolve states within the trajectory transitions, so the trajectory terminology is used somewhat figuratively. The work-principle model has the working fluid (reaction material) interacting with a tremendous reservoir (chamber air and walls), while forecasting the work performed upon a mechanical agent. Within the underground test chamber, the widening fume zone undergoes a decline in temperature, a reduction in reaction rates, resulting in out-of- equilibrium circumstances at the Q*-point, representing the measurement state. Rather than coping with the hard issues of non-equilibrium, the toxic fumes are resolved numerically for the Z-point, rendered by a zero-net- interaction energy constraint. Though other techniques require complex equation-of-state EOS for the whole trajectory, the work-principle formulation eludes the issue, requiring an EOS that works just for the terminal-state. Under the circumstances, the Z-state is reconcilable with the ideal-gas domain, and relevant TDRC results yield the restricted state in a numerical way for different charge formulations. The work principle makes it hard to remedy or to tamper with the resulting Z-point fumes: non-macroscopic trajectory readjustment is forsaken, terminal states are results rather than stipulations, and resetting the EOS formula constants would be ineffectual. Though the non-equilibrium portion remains unresolved, it is noteworthy that the work principle rigidly fixes the Z-state, thereby reducing the uncertainty for rendering reaction-rate models characterizing the non-equilibrium Z-Q* transition. Though more refinements are needed, some Z-point fume results are included to illustrate the threshold (minimum) resolving capacity of the work- principle formulation.

By M. K. Larson, B. G. White

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are investigating the causes and mechanisms of roof failure in underground mines. It is expected that a better understanding of these causes and mechanisms will lead to better layout and support designs that will help prevent accidents and fatalities associated with fall of ground. Two numerical experiments were conducted by NIOSH researchers using the Fast Lagrangian Analysis of Continua (FLAC) computer modeling program with a strain-softening continuum to simulate fracture zones. Two models, one of a round hole in a plate and one of a rectangular opening, were constructed and boundary conditions were applied to simulate far-field shear. The Particle Flow Code in Two Dimensions (PFC2D) computer program was used to look at the effects of far-field shear in generating fractures around an underground opening, but these models are preliminary until boundary conditions, strengths, and stiffnesses are matched to the FLAC models. Results showed that shear zones propagated from the opposite corners of openings in directions that appeared to be determined by opening shape and far-field stress. Tensile failures also formed and extended away from these shear zones. The consistent direction of shear deformation with respect to far-field shear provides a plausible explanation for preferred directions of shear as seen in geologic environments.

By John H. Soulé

"INTRODUCTION The property of the Silver Spot Mines Co. is in the Boston Hill area within and adjacent to the southwest corner of Silver City, N. Mex. The area was visited by Bureau of Mines engineers 3/ in 1941 and 1942 during the investigation of possible sources of manganese. The area was visited again in November 1944 4/ to study the possibilities of geophysical exploration of the manganiferous-iron deposits. This geophysical work was performed in 1945 5/, confirmed the existence of known deposits of manganiferous-iron ores, and indicated the probable extent and situation of others.The Silver Spot property was churn-drilled from 1926 to 1929 during exploration for manganiferous-iron ores. The sludges from a number of the holes indicated low-grade lead-zinc mineralization. Lead and zinc minerals also were found on the dumps of some of the old shafts when the property was visited by D. H. Mullen, an engineer of the Bureau of Mines late in 1946. A diamond-drilling project was proposed. It was started in April 1947 with the intention of investigating the best of the known ore indications as shown by the old churn-drill holes and thus gathering new data upon which to base future work. Only one hole was drilled before the project was terminated because of lack of funds and time."

Mar 1, 1948

By P. G. Kovalchik

Overexposure to noise remains a widespread, serious health hazard in the US mining and other industries despite 25 years of regulation. Most categories of illnesses and injuries associated with mining have improved, with the exception of hearing loss. The drilling of rock in a confined work environment contributes to high levels of noise exposure in mining. The National Institute for Occupational Safety and Health (NIOSH) is conducting research to reduce the noise exposures of jackleg drill operators and to prevent additional cases of noise induced hearing loss (NIHL) by developing and evaluating low-cost retrofit noise controls for equipment. This report describes the procedure for the measurement and reporting of noise from portable pneumatic tools such as jackleg drills. The technique used in this research allows for the determination of the source A-weighted sound power levels and the radiation patterns in octave and 1/3 octave bands. Overall sound power level is also determined. This paper also reports the results obtained by using this procedure to evaluate a SECO S215 standard production drill and a CSIR Miningtek prototype rock drill incorporating engineering noise control measures. It was found that by using the manufacture?s recommended operating pressure of 496 kPa (72 psi) that the CSIR prototype?s sound power was 10 dB(A) less then that of the SECO S215.

Jan 1, 2009

By Doug Tesarik

The study of neutrinos?particles infinitesimally smaller than atoms?would be significantly advanced if a deep underground facility were available that would filter out unwanted cosmic radiation. Encouraging progress has been made in satisfying the criteria for such a facility with the selection of the Homestake Mine in Lead, SD, by the National Underground Laboratory Committee as the recommended site for a National Underground Science Laboratory (NUSL). The Homestake Mine is America?s oldest and deepest underground mine, and its well-maintained infrastructure to depths of 2438 m below the surface makes the mine an excellent site for such a laboratory. The investigation reported here is an initial study of the stability of the first of the proposed chambers. A cylindrical room with a dome-shaped roof and floor was analyzed in three dimensions using the finite-difference program FLAC3D. The results were compared to recommended support requirements based on Barton?s Tunneling Quality Index, Q. Based on model results and observations from previous mining studies, large rooms with 50-m roof spans can be constructed and will remain stable at 2141 m below the surface in the Poorman Formation when the rock is reinforced with cable bolts. Construction may be possible at lower levels in the Yates Formation if more extensive laboratory strength tests confirm initial results.

Jan 1, 2002

By By Staff

"This publication summarizes, for potential contractors and all other interested parties, the research, development, and demonstration of in-house and contract projects programmed by the Bureau of Mines for fiscal year 1982(October 1, 1981-September 30, 1982) under its Minerals Health and Safety Technology program. The objective of these projects is to provide an ordered and sequenced series of advance toward the Bureau's overall goal of providing the systems technology required to create a more healthful and safer working environment for the Nation's mining and minerals processing workersINTRODUCTION The Bureau of Mines conducts a balanced, continuing in-house research and development program to accelerate systematic improvements in health and safety conditions in U.S. mines. Part I of this report outlines the Bureau's present in-house effort to all interested parties; in particular, potential contractors can refer to it when submitting USP's (unsolicited proposals), thus avoiding proposing research that duplicates work being performed by the Bureau.It is the policy of the Bureau of Mines to utilize as fully as possible the capabilities of the private sector in minerals research, and to that endPart II of this report outlines the Bureau's current projected contract research needs.The projects presented were planned at the beginning of the fiscal year and are subject to change based on emerging priorities and availability of funds. Contingencies may require that a significant portion of the program be deferred into fiscal year 1983 (FY 83) or beyond. It is important to realize that since this is a summary document, the project descriptions related to a design, fabrications, and demonstration effort do not necessarily imply total package procurement."

Jan 1, 1982

Locating subsurface conductive solutions is important for many applications, including in situ mining and environmental protection. Drilling boreholes for sampling is expensive and can increase contamination by mixing water from different aquifers. Various noninvasive geophysical methods are available, but previous comparisons were hampered by different methods being used at different sites or at different times. The U.S. Bureau of Mines (USBM) compared methods at one site using the same conductive solution to improve the reliability of the comparisons. Locating deep (> 100 m) solutions is most difficult, SO the USBM selected methods applicable for such depths. Objective Improve the ability to locate subsurface conductive solutions by evaluating and comparing applicable geophysical methods. Approach The experiment was performed cooperatively with other agencies to increase the number of methods studied. The USBM, the University of Arizona, Sandia National Laboratories, and Zonge Engineering and Research, Inc., conducted cooperative field tests of six electromagnetic (EM) geophysical methods to compare their effectiveness in detecting salt water brine of conductivity 3.6 S/m collecting at the water table, 157 m subsurface. The brine was injected through two boreholes. The test site was the University's San Xavier experimental mine near Tucson, AZ. Geophysical surveys using surface and surface-borehole, time-domain electromagnetics (TEM); surface controlled-source audiofrequency magnetotellurics (CSAMT); surface magnetic field ellipticity, surface-borehole, frequency-domain electromagnetics (FEM); and crosshole FEM were conducted before and during brine injection. A total of 110,000 I. of brine was injected over one week, but the effective target volume of brine was much smaller because of mixing with ground water and dispersion.

Jan 1, 1994

By Charles L. Kimbell

Annual global steel industry investment is partly mirrored in the data for selected market economy countries that appear in table 13 for 1988-90. No reasonably comprehensive 1991 data were available for inclusion in this study, and the partial reporting available was so incomplete that it was impossible to demonstrate whether the level advanced or declined from the 1990 level of nearly $15.5 billion. Moreover, with the radical changes that are now being effected in the steel industries of the states that were the U.S.S.R. and its CMEA partners, it is most regrettable that comprehensive and comparable data, both current and historic, on investment in this area are not available. Updated information on market economy country petroleum industry capital and exploration expenditures by geographic area has been included in table 14, and it is evident that there was a substantial upturn in investment in 1991. The level of almost $74.5 billion was 14.5 % above the 1990 level and included gains in every topical category and geographic area. The source of information for this table has been changed to the Oil and Gas Journal Database from the previously used Chase-Manhattan Bank study of Capital Investments of the World Petroleum Industry, which has been discontinued. Because of this source change, it has been necessary to modify the structure of the table somewhat, but its total scope of coverage is regarded as basically unchanged. It should be noted that the grand total, as well as some of the detail appearing for 1987, corresponds precisely with those in the previous source.

Jan 1, 1993

By Deno M. Pappas, Christopher Mark, Eric R. Bauer

During 1998-99, groundfall incidents resulted in 27 fatalities and were responsible for over 70% of all deaths in U.S. underground coal mines. To obtain a better understanding of where and why these incidents occurred, a comprehensive analysis of ground fall injuries and fatalities was conducted. The first portion of the study examined various factors associated with roof and rib fall injuries and reportable roof fall noninjuries that occurred during 1995-98. The study found that the room-and-pillar mining method has twice the groundfall incident rate than the longwall method. Mine locations with high groundfall rates seem to correlate to regions where there is a higher concentration of problematic coalbeds. For example, the Illinois Basin has very high groundfall rates, which can be traced back to several key coalbeds-Kentucky No. 13, Herrin/No. 6/Kentucky No. 11, and Springfield No. 5/Kentucky No. 9. High rib fall rates were found in mines located in thick seams. Groundfall rates were found to be 30% to 40% higher during the months of July through September, possibly due to high humidity that may cause the shale mine roof to deteriorate. The second part of the study examined the root causes of failure by reviewing all groundfall fatality reports for 1996-99. Primary and secondary hazard factors were assigned to each groundfall incident. The primaryf actors resulting in these groundfall fatalities were pillar extraction, traveling under unsupported roof, skin failure, construction, longwall faces, intersections, and geologic discontinuities. Defining prominent ground control incident trends and hazards will identify areas where additional study is needed and where innovative solutions need to be developed to reduce these severe occupational hazards.

Jan 10, 2000

By Eric G. Zahl, John P. Dunford, Hamid Maleki

Coal bumps are influenced by geologic conditions, the geometric design of coal mine excavations, and the sequence and rate of extraction. Researchers from private industry and government agencies around the world have studied mechanisms of violent failure and have identified individual factors that contribute to coal bumps. To develop predictive tools for assessing coal bump potential, the authors initiated a comprehensive study using information from 25 case studies undertaken in U.S. mines. Multiple linear regression and numerical modeling analyses of geological and mining conditions were used to identify the most significant factors contributing to stress bumps in coal mines. Twenty-five factors were considered initially, including mechanical properties of strata, stress fields, face and pillar factors of safety, joint spacings, mining methods, and stress gradients. In situ strength was estimated in 12 coal seams where uniaxial compressive strength exceeded 2,000 psi. Allowances were made for favorable local yielding characteristics of mine roof and floor in reducing damage severity. Pillar and face factors of safety were calculated using displacement-discontinuity methods for specific geometries. This work identified the most important variables contributing to coal bumps. These are (1) mechanical properties of strata, including local yield characteristics of a mine roof and floor, (2) gate pillar factors of safety, (3) roof beam thickness, joint spacing, and stiffness characteristics, which influence released energy,(4) stress gradients associated with the approach of mining to areas of higher stress concentrations, and (5) the mining method. By combining the strength of both analytical and statistical methods, new capabilities were developed for predicting coal bump potential and for building confidence intervals on expected damage.

Jan 5, 1999

By Thomas P. Meloy

"The presence of respirable quartz-bearing mineral par-ticles has been well documented in many coal mines, and the Mine Safety and Health Administration regulations address the quartz content of mine dusts. Unfortunately, the correlation between the quantity of respirable quartz-bearing mineral particles and the pathogenicity of the dust is not strong. Work is currently underway by the National Institute for Occupational Safety and Health/U.S. Bureau of Mines and work is being included in the Respirable Dust Center Program by Dr. Seehra to determine the surface availability of quartz in mixed composition mine dusts. However, this paper propose a possible source of surface quartz or a spe¬cial region in the coal that may contribute to the pathogenicity of selected particles in the respirable dust.Assumed in this model is the hypothesis that either the cleat surface is coated with quartz or some cytotoxic sub-stance that in the body is capable of destroying macrophage and thus inducing a fibrotic response (1) that during the frag¬mentation a reasonable proportion of the respirable size coal particles contain some of the original cleat surface and that these particles have the same order of in vivo cytotoxicity as do the quartz particles. It may be that these cleat surfaced respirable size particles are only contributory to the overall pathogenicity of the coal dust, nevertheless, there are enough of these particles to to considered as a potential source of the cytotoxic dust particles.This paper demonstrates that if the cleat surfaces are mineralized with quartz or have a pathogenic coating, then in many mines there will be enough respirable coal dust particles containing some cleat surface to cause a fibrotic reaction. To understand why some of the dust particles contain as part of their surface some of the cleat surface, consider what happens when a beer bottle is broken. While there are a large number of beer bottle fragments, many of the fragments, particularly the larger fragment sizes, will have as a fraction of their surface part of the original beer bottle surface. The model and mathematics of this problem have been worked out by Meloy.(2-4)In the homogeneous IAC model, (2-5) a fragment or par-ticle resulting from comminution is equally likely to occur anywhere in the material being broken. Therefore the probability of a particle of size x having part of the cleat surface in it, p(x), is proportional to x. Thus:"

Mar 1, 1989

Objective: To improve the effectiveness of dust collector capture on surface mine drills.

Oct 1, 2005