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By James Ridenour

The Gearhart Mountain Wilderness and RARE II area 6225 encompass 22,823 acres (9,236 ha) of the Fremont National Forest in southern Oregon (fig. 1). The area was studied under the provisions of the Wilderness Act of 1964 (Public Law 88-577). The U.S. Bureau of Mines determined the mineral potential of known mines, prospects, or mineralized areas, while in a separate effort the U.S. Geological Survey made geological, geochemical, and geophysical studies. MINERALIZED AREAS The study area contains no mining districts or known claims. Nearby occurrences of uranium, base metals, perlite, mercury, and diatomite apparently do not extend into the study area. Reconnaissance pan samples reveal only trace amounts of gold. No anomalous economic minerals were found in heavy mineral fractions of samples from stream beds draining the area.

Jan 1, 1982

By D. Harrington

This circular presents Part III-A of a series reviewing the literature on effects of breathing dusts with special reference to silicosis; it deals with the economic and legal aspects of dust diseases in industry; Part III-B will contain data on the status and cost of compensation for silicosis, Parts I and II of the series have been issued as Information Circulars 6835, 6840, and 6848; Part I defines and classifies dusts, indicates sources of exposure, and describes the physiological effects of breaching dusts; Part II-A discusses the principal dust factors producing pulmonary pathology and methods of determination of dust in air; and Part II-B presents data on the engineering and medical control in the prevention of dust diseases and general recommendations for their control in industry. A summary and general conclusions will complete the series.

Jan 1, 1935

By M. M. Fine

A process for simultaneously reducing and indurating iron are pellets was developed by Bureau of Mines laboratory research and confirmed on a continuous pilot plant basis. Moist iron are concentrate was balled, mixed with solid reductant, and heated at about 1,100° to 1,150° C. On a small scale, a variety of concentrates and fuels were utilized successfully. The pilot rotary kiln tests were limited to natural magnetite, synthetic magnetite, lignite, and anthracite. In both cases, partially reduced pellets with excellent physical properties were regularly produced with average analyses of at least 80 percent total iron and 60 percent or more metallic iron. These and other prereduced pellets were smelted in the Bureau's experimental blast furnace facility, Bruceton, Pa. With prereduced spheres comprising 85 percent of the burden, the coke rate was approximately half that with standard oxide pellets and production of hot metal was increased by 75 percent. Economic appraisal of the cost of making hot metal indicates that reduced pellets could be more profitable than any other iron raw material in both investment capital and daily cost of operation.

Jan 1, 1970

By Wadaw Cybulski

The problem of coal dust explosions: Basic information about the explicability of coal dust: Main parameters of the explosibility of coal dust; Main parameters of the explosibility of coal dust; Limit explosibility of coal dust and its dependence upon the basic parameters: The effect of the initiator of the explosion-on-the explosibility of coal dust: The dependence of the course of an explosion upon the distribution of coal dust in the workings, upon the dimensions of the workings, the length of zones, the direction of the development of explosions and upon the content of firedamp in the air of the workings; Con-sequences of coal dust explosions; The ways of suppressing the danger of coal dust explosions; Stopping the developed coal dust explosions; The explosibility and explosions of lignite dust of xylite structure

Jan 1, 1975

By Thomas M. Barczak, Dennis R. Dolinar, Gabriel S. Esterhuizen

Longwall mines typically use some form of standing support for secondary roof support in longwall tailgate entries. Although there have been several new support products developed for this application, there remains no universal design criteria to optimize the application of these support technologies. The requirement for optimization and proper support selection is to understand the degree of control that the support has on the ground behavior. The ground reaction curve and numerical modeling was used to evaluate the impact of standing support on ground behavior. LaModel was used to evaluate the impact of standing support on main roof and floor behavior and pillar yielding. The conclusion drawn from this study was that standing supports do not have sufficient capacity to control main roof or floor loading or prevent the resulting convergence of the tailgate entry. However, it is imperative that this “uncontrollable convergence” be considered in the support design to prevent premature failure of the support. A FLAC model was used to evaluate the near-seam roof and floor behavior in conjunction with the global vertical and horizontal stresses. The model suggests that standing roof supports can have some impact on the ground behavior as the elastic response of the rock is exceeded and rock structure deteriorates from the stress concentrations that develop around the tailgate opening. During this phase, the capacity and stiffness of the standing support can be critical to the stability of the opening, as eventually the rock mass will be transformed into a partially detached structure whose weight must be supported by the standing support. This work is part of a ground control program of research at the National Institute for Occupational Safety and Health (NIOSH) aimed at improving mine safety by reducing roof fall injuries and fatalities.

By Laurence F. Kelley

This paper is one of a series being prepared by the United States Bureau of Mines on shaft-sinking methods and costs at individual operations in various mining districts of the United States. The methods and costs described herein are those of The Consolidation Coal Co. at one of its operations in the Tug River district, McDowell County, W. Va. ACKNOWLEDGMENT The author is indebted to Frank R. Lyon, vice-president, Thos. G. Fear, general manager of operations, and Chas. Enzian, chief engineer, of The Consolidation Coal Co., for valuable assistance and collaboration in the preparation of this paper. W. A. Cole, manager of the E. J. Longyear Development Co. furnished valuable data on methods and performance averages.

Jan 1, 1932

By Albert L. Toenges, Frank A. Jones

"INTRODUCTION The introduction of mechanized pining in coal mines, which has speeded loading, has emphasized the importance of efficient underground transportation systems. The purpose of this investigation is to study and analyze various systems now in use, and to derive conclusions therefrom. This report may be helpful to operators who are planning new systems of transportation or who are revising present systems to increase their efficiency. This paper is the first of a series on this subject and describes some systems of transportation utilizing rail haulage.ACKNOWLEDGMENTThe information used in preparing this report was obtained through the courtesy and cooperation of the officials of the companies whose mines wore studied. The descriptions of the transportation systems at the mines included herein have been checked for accuracy, and publication of the data has been approved by the executives of the several operating companies."

Jun 1, 1940

By Peter G. Kovalchik, Rudy J. Matetic, Susan B. Bealko, Adam K. Smith

Overexposure to noise remains a widespread and serious health hazard in the U.S. service providing and goods producing industries. Excessive noise can lead to poor verbal communication and reduce the ability to recognize warning signals. These dangerous work conditions can also cause stress and fatigue. Occupational hearing loss is a permanent illness, with no recovery currently possible. Method: National Institute for Occupational Safety and Health (NIOSH) has recognized Noise Induced Hearing Loss (NIHL) as one of the ten leading work related diseases and injuries in the United States, and has emphasized its importance as one of the critical areas expressed in the National Occupational Research Agenda. Results: One of the most serious noise problems in the goods producing industries is the operation of continuous mining machines during underground coal mining. In order to minimize occupational hearing loss, noise hazards are “designed out” early in the design process. NIOSH is leading a national initiative called Prevention through Design (PTD) to promote this concept. This paper describes the quiet by design approach of a noise control that reduced noise exposures of continuous mining machine operators by 3dB(A) using the four functional areas of PTD, namely Practice, Policy, Research, and Education.

By Yagesh N. Bhambhani, Rammohan V. Maikala

Landstrom et al. (1985) suggested the possibility of cortical activation during exposure to WBV, however, it is not known how cerebral physiology (oxygenation and blood volume) responds in healthy women during different vibration frequencies. This study examined the role of backrest support and handgrip work on cerebral oxygenation and blood volume responses, during exposure to seated WBV. Methods Fourteen women (age: 23.9 ± 3.5 years) were randomly exposed to three frequencies of WBV (3, 4.5 and 6 Hz at approximately 0.9gr.m.s in the vertical direction) on a customized vibrating base (Advanced Therapy Products, Inc., USA) in a seated posture on three separate days. On the first day, the subjects completed an aerobic fitness test until volitional exhaustion on an arm cranking ergometer (Cybex, MET 300, USA). Each WBV session lasted 30 min (6 min baseline without WBV, 8 min WBV ‘with’ or ‘without’ backrest support, and 4 min recovery from WBV, 8 min WBV with ‘opposite’ backrest condition, and 4 min recovery following WBV). During 8 min WBV exposure ‘with’ and ‘without’ backrest support, subjects performed maximal voluntary rhythmic handgrip contractions with their right hand for 1 min using a dynamometer. To obtain regional oxygenation and blood volume responses, a NIRS sensor (MicroRunman, NIM, Inc., PA, USA) was placed on the anterior right frontal lobe just below the hair and close to fronto-temporalis region (Maikala et al. 2005). Results Baseline oxygenation and blood volume values were recorded during recovery from each WBV session of ‘with’ and ‘without’ backrest support. The physiological change in oxygenation and blood volume during each frequency (3, 4.5, and 6 Hz) for both backrest (‘with’ and ‘without’ a backrest) and workload (WBV only and WBV combined with rhythmic handgrip contractions) was calculated as the difference between the maximum values identified for each WBV condition of backrest and workload and baseline values (Maikala et al. 2005). Three-way analysis of covariance with repeated measures (frequency, backrest, and workload) with a fully crossed design was used to evaluate the differences in the oxygenation and blood volume responses (measured in optical density [od] units). Peak oxygen uptake during

Jan 6, 2006

By K. K. Kelley

This work is both a revision and an elaboration of Bureau of Mines Bulletin 371, which was published in 1934 and included data available to October 1933. During the intervening years, a large number of new experimental, high-temperature, heat-content data have become available through continuous, systematic efforts of the Pacific Experiment Station of the Bureau of Mines and the Laboratory for Inorganic and Physical Chemistry of the University of Groningen (Netherlands), coupled with various individual investigations at many institutions. In addition, calculations from spectroscopic and molecular constant data have been extended and applied to a wide variety of gaseous substances. This bulletin purposes to collect and correlate all available high-temperature heat-content and specific-heat data for inorganic sub-stances and to formulate tables and algebraic expressions for their representation. It is hoped in this manner to remove some of the tedium of thermodynamic calculations for industrial metallurgical research workers and engineers who often have available only an inadequate library in this field. It is expected also that this bulletin will have value to those teaching courses in metallurgical and chemical thermodynamics.

Jan 1, 1949

Empirical methods involve the scientific interpretation of real-world experience. Many problems in ground control lend themselves to an empirical approach because the mines provide us with plenty of experience with full-scale rock structures. During the past 10 years, powerful design techniques have emerged from statistical analyses of large databases of real-world pillar successes and failures. These include the Analysis of Retreat Mining Pillar Stability (ARMPS), the Analysis of Longwall Pillar Stability (ALPS), the Mark-Bieniawski rectangular pillar strength formula, and guidelines for preventing massive pillar collapses. In the process, our practical understanding of pillar behavior has been greatly enriched.

Jan 5, 1999

By Hillary W. St. Clair

Mining activity began in colonial times with ironmaking operations scattered along the eastern seaboard. Iron furnaces and forges manufactured iron implements from bog iron ores using charcoal from the extensive forests as a fuel. Lead ores were mined in the Mississippi Valley and copper ores in the Lake Superior region. However, the real beginning of the American mining industry did not occur until the 19th century. The history of American mining is organized around three epochal events. The first was the discovery of gold in California in 1848, which marked the beginning of a period of apprenticeship in mining and metallurgical techniques. The second was the discovery of the fabulous Comstock Lode in western Nevada in 1859, which expanded mining throughout the Far West and led to large-scale underground mining and the development of smelting techniques for lead, silver, and copper ores. The third event was the building of a transcontinental rail-road system after the Civil War, which brought about the consolidation of the industry from a large number of independent mines, mills, and smelters into integrated operations run by large corporations. Thus developed the mining industry that today supplies the energy and critical materials for the great-est industrial complex the world has known.

Jan 1, 1977

By J. A. HUFF, V. V. BAKER

This circular is intended to present in brief form the statutory provisions of Pennsylvania regarding mining operations, in force at the end of the 1931 session of the legislature. lo reference is made to general laws which affect mining only incidentally in common with other subjects, such as the workmens compensation law. The statements have been condensed as far as practicable, and provisions not deemed of general interest, such as matters dealing only with administrative details, have been omitted. This circular obviously is not written with such particularity as to be of great value to the legal profession, but it is hoped that it will be beneficial to the mining industry in giving this information in a relatively compact form. At the end of each paragraph the statute from which it is derived is cited to facilitate reference to the text of the law. It is planned to publish additional circulars from time to time dealing with the mining laws of other States. Any criticisms of the form of publica- tion followed herein, or suggestions aimed at the improvement of future circulars, will be welcomed.

Nov 1, 1932

By S. S. M. Chan

The Bureau of Mines has investigated the structural aspects of shafts and support systems using the finite-element technique. In situ field measurements in deep, vein-type metal mines show that rock stresses are often higher in the horizontal direction than the vertical, and unequal in the horizontal plane. These data and laboratory and field-determined physical properties were used as input to analytical studies. Various design and construction parameters were investigated to deter-mine the effect on shaft stability. Rectangular shafts were studied in detail to determine the effects of applied stress ratio, shaft orientation and dimension, influence of interbedded quartzite and argillite, and rock fracturing. Various support systems were analyzed, including concrete lining, timber, and steel sets. Circular configurations were investigated to evaluate yield zones and liner thickness. Elliptical shafts and time effects were briefly evaluated to illustrate shape and time effects and demonstrate the methodology. It is shown that the magnitude, direction, and ratio of applied stress and rock mass anisotropy are keys to determining shaft stability. A realistic conceptual framework was developed with which to examine the rock and support interaction in deep mine shafts. Structural analysis techniques overcome some of the historical difficulties with shaft de-sign by defining the field data requirements and structural sensitivity of various design and construction parameters.

Jan 1, 1985

By John Paul Gries

This Bureau of Mines report reviews the mineral industry of the Black Hills area, including Butte, Custer, Fall River, Lawrence, Meade, and Penning- ton Counties, S. Dak.; and Crook, Niobrara, and Weston Counties, Wyo. It includes discussion of geological occurrence, processing, and potential of 27 commodities that have been produced from the nine-county area. The value of mineral production exceeds $70 million annually. Gold and petroleum account for two-thirds of the total, followed by clays, cement, sand and gravel, and rock. The combined mineral industries annually consume 268 million kilowatts of electrical energy, 933 million Mcf of gas, and 2 million barrels of fuel oil. Water consumption is about 10,000 gallons per minute. About 2,700 persons are employed on a year-round or significant part-time basis.

Jan 1, 1974

In 2005, a total of 739 nonmetal mining operations reported employment to the Mine Safety and Health Administration (MSHA). These mines (e.g., potash, gypsum, salt) comprised 5.0% of all operations. ? Mines producing common clay comprised 26.9% (n=199) of all nonmetal mining operations. ? Nonmetal mining operations were located in all states and territories except Alaska, Delaware, Hawaii, Maine, New Hampshire, Rhode Island, Puerto Rico, and the Virgin Islands.

Jan 1, 2008

In the interest of safety in mining, the Bureau of Mines recommends: 1. That cages or skips used for hoisting or lowering men in vertical and steeply inclined shafts shall be provided with safety catches designed to prevent falling of the cage or skip if the hoisting rope or other connections break; and 2. That cars used. for hoisting or lowering men with ropes in slopes shall be provided with arresting devices, other than ordinary brakes, that come into action if the hoisting rope or other connections break. In presenting this decision, it is recognized that the principal requirements for safety in hoisting operations are the use of hoisting ropes of ample size and strength to provide a factor of safety recognized as adequate by the best en engineering practice; their proper care, protection against undue wear and corrosion, and frequent inspection; and immediate removal of ropes from service when inspection or tests cast doubt upon their further safe serviceability.

Jan 1, 1938

By S. T. Reese

STATISTICS of injuries in the quarrying and related industries in the United States first became available when the Bureau of Mines collected reports from the operating companies for the calendar year 1911. Since then reports have been collected annually. The present bulletin, covering the calendar year 1952, is the 33d publication containing statistical data on injuries at quarries and related plants, and it is the first to be published since 1944. The last publication was Bulletin 458, Quarry Accidents in the United States during the Calendar Year 1942. The unpublished statistics for 1942-51 may be found in the Appendix of this bulletin. The Bureau of Mines is authorized to collect data on injuries at quarries, but there is no Federal law that compels operators to supply such data, and the reports received from operators are voluntary responses to the Bureau's requests for information. Although the figures presented herein may not be complete for the entire industry, every effort has been exerted to make them so, and the figures given are believed to be thoroughly representative of the hazards to which quarry workers are exposed. Moreover, the figures are com¬parable as between States -which is significant in view of the lack of uniformity among the States as regards classes of plants covered by State laws, classes of injuries covered by State reports, and other factors that tend to make it impracticable or impossible to compare the injury experience of one State with that of another or to comprehend the relative importance of the various causes of injuries in the industry as a whole.

Jan 1, 1955

The concept of isokinetic measurement of strength was originally related by Hislop and Perrine.(1)Characteristics of an isokinetic exertion are constant velocity throughout a predetermined range of motion. Strictly speaking, a means of speed control, and not a load in the usual sense, is applied in isokinetic exertions.(1)However, load and resistance are definitely present in this technique. In this case, the load is a result of the energy absorption process performed by the device to keep the exertion speed constant. The device prevents energy from being dissipated through acceleration in isokinetic exercise. The energy is instead converted into a resistive force, which varies in relation to the efficiency of the skeletal muscle. Since the speed of motion is held constant in isokinetic exercise, the resistance experienced during a contraction is equivalent to the force applied throughout the range of motion. For this reason, the technique of isokinetic exercise has sometimes been referred to as accommodating resistance exercise. This type of exercise allows the muscle to contract at its maximum capability a tall points throughout the range of motion. At the extremes of the range of motion of a joint, the muscle has the least mechanical advantage, and the resistance offered by the machine is correspondingly lower. Similarly, as the muscle reaches its optimal mechanical advantage, the resistance of the machine increases proportionally. It must be understood, however, that while isokinetic devices control the speed of the exertion, this does not assure a constant speed of muscle contraction. The speed of isokinetic contractions is constant during individual exertions; however, it is also possible to compare muscular performance over a wide range of isokinetic velocities. Increasing the isokinetic speed of contraction will place increasing demands on Type II muscle fibers (fast twitch and fast oxidative glycolytic). Workplace Assessment It is clear that isometric strength testing cannot substitute for dynamic strength assessment when examining highly dynamic occupational job demands. As most industrial work tasks contain a significant dynamic component, analysis of isokinetic strength capabilities appears to offer some advantage to isometric testing in this regard. However, it must be recognized that isokinetic devices are not entirely realistic compared with free dynamic lifting in which subjects may use rapid acceleration to gain a weight-lifting advantage.

Jan 1, 1998

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