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Improve the health and safety of underground mine workers by finding ways of keeping them away from unsupported areas of the mine. Background Roof falls have been the leading cause of fatal accidents in the underground coal mining industry. During 1985-89, 92 coal miners were killed by falls of roof and rib, with more than 4,000 miners injured. According to accident investigation reports from the Mine Safety and Health Administration, 47% of the victims of these fatal roof fall accidents were in the area of unsupported roof al the time they were killed. There is an urgent need to find out why miners go under unsupported roof and to devise strategies for preventing this unsafe behavior. Approach To discover what can be done to prevent miners from going under unsupported roof, confidential interviews were conducted with 297 miners who work in the face crews of 6 different coal mines. The interview topics included company policies and actions regarding going under unsupported roof, how foremen react to people who go under unsupported roof, circumstances likely to cause some people to go under unsupported roof and how to prevent these situations, and observations concerning those who go under unsupported root.

Jan 1, 1991

By J. J. Cummins

Green River oil shale previously extracted by benzene was heated at 150°, 200°, 250°, 300°, and 350° C for 0.5 to 360 days to determine the rate at which kerogen degrades to thermal products, the types of thermal products formed, and the effect of prolonged low-temperature heating (preheating) upon subsequent assay yields. Thermal decomposition of kerogen at 150° to 350° C is treated as a first-order reaction. The specific reaction rate for kerogen decomposition increases from 2.2 X 10-4 per day at 150° C to 2.0 X 10-1 per day at 350° C. The calculated kerogen activation energy is 19 kcal. Variations in the rate of formation of individual type components of the pyrolytic products were found. Carbon balances show an increase in the amount of kerogen converted to bitumen and oil (from assay of preheated oil shale) as the temperature of preheating increased from 150° to 350° C. Total product from shale preheated at temperatures of 150° and 200° C gave less than 100 percent of Fischer assay yields while the total products from shale preheated at temperatures of 250° to 350° C gave greater than 100 percent of Fischer assay yields.

Jan 1, 1972

By T. E. Ackman

The Bureau of Mines conducted a study of current trends in methods employed by the coal industry to dispose of acid mine drainage (AMD) treatment sludge. Thirty-three AMD treatment plants, operated by 11 Pennsylvania coal companies, were randomly surveyed. These plants provided data for calculating sludge volumes, as well as information on sludge settling, transportation, and disposal. Onsite visits allowed observation of problems associated with the various methods of sludge disposal: (1) disposal into a deep mine, (2) permanent retention in ponds, (3) disposal at an active coal refuse area, and (4) onsite burial. Method 1 is the most frequently used and the most environmentally sound. It is apparent, based on this representative sampling of AMD treatment plants, that the magnitude of sludge production is such that an aggressive and directed effort in reduction of sludge volume is seriously needed. The areas of major concern are (1) the amount of surface land required for sludge storage and disposal, (2) reclamation of these disturbed surface areas, and (3) effective and efficient means of removing, transporting, and disposing of AMD sludge. In this report, an engineering approach to the practical problems associated with the existing disposal methods is presented, together with recommendations for future research.

Jan 1, 1982

By Robert E. Wood

[The temperature dependency of the low-density thermal conductivity coefficients, ?°T, of nitrogen, 100° to 1,200° K, is correlated with the Keyes' equation, ?T ½ -1 -12/T) WT = aT+ bT 10 The equation ?T,P = ?°T +a[ ]ß represented 509 experimental higher V pressure thermal conductivities in the temperature range 131.2° to 973.15° K for pressures to 500 atmospheres, with a mean absolute deviation of 2.35 percent. This equation was used to compute thermal conductivities of gaseous nitrogen for 47 pressures, 1 to 240 atmospheres, and 110 temperatures, 133° to 740° K, which are common to conditions encountered in Bureau of Mines helium purification processes. Isobaric heat capacities, CP, and viscosities, ?T,P, from previous work were combined with the present thermal conductivities, ?T,P, to compute Prandl1 numbers, C?T P / ?T ,P, of nitrogen. Tabular values of Prandtl num¬bers are presented for 49 pressures, 1 to 240 atmospheres, and 75 temperatures, 133° to 740° K. Estimated uncertainties are ±5 percent in the tabulated thermal conductivities and ±15 percent for the computed Prandtl numbers. However, the uncertainty may rise to ±10 percent for thermal conductivities and to ±30 percent for Prandtl numbers as the critical conditions of nitrogen are approached.]

Jan 1, 1971

A revolutionary development in blasting materials has occurred in the past 5 years. Ammonium nitrate, sensitized by the addition of a few percent of No. (class) 2 diesel fuel or other suitable petroleum product, has been adopted as a low-cost, efficient blasting agent2/ by a wide variety of mining and heavy construction operations. Moreover, ready availability of the component supplies throughout the Nation and ease of their formulation into effective blasting agents have made it possible for the blaster himself to pre-pare the mixes at the site of use. Although these field-mixed products have partly or wholly displaced explosives such as dynamites in some applications, there are other blasting operations where the fuel-sensitized ammonium nitrate agents do not appear to be well adapted. Important safety characteristics are inherent in ammonium nitrate-based blasting agents prepared under competent factory control, or when field mixed under equivalent close control--as long as the hazards they present are clearly understood and respected. This publication attempts to summarize knowledge of those hazards and to incorporate practical ways to cope with them. A series of safety recommendations thus is presented. These recommendations cover the preparation, storage, transportation, and use of field-mixed ammonium nitrate blasting agents.

Jan 1, 1960

By J. W. Walkiewicz

The Bureau of Mines investigated alloys containing mischmetal (MM), cobalt, copper, magnesium, and iron for use in permanent magnets in place of the scarce samarium-cobalt alloys. The magnetic properties of MM-Co, MM-Co-Cu, MM-Co-Cu-Mg, and MM-Co-Cu-Fe-Mg alloys were evaluated. Magnets were fabricated by powder metallurgy consisting of arc-melting the metals, crushing and grinding the resultant alloys, alining and compacting the powder, and sintering the compacts. Magnetic values of MHc = 4.7 kOe, BHc = 4.07 kOe, Br = 6.81 kG, and (BH)max = 10.0 MGOe were obtained with a MM-Co alloy containing 36±0.5 wt-pct MM. By substituting copper and magnesium for part of the cobalt, the values for MHc and BHc were increased to 29.0 kOe and 5.89 kOe, respectively. This intrinsic coercivity value exceeded that of Sm-Co alloy obtained in our laboratory. The addition of iron to MM-Co-Cu-Mg alloys resulted in an increase of Br to 6.90 kG and (BH)max to 10.3 MGOe. Copper and magnesium contents of these alloys were optimized to obtain maximum values of MHc.

Jan 1, 1981

By Khamis Y. Haramy

This Bureau of Mines paper describes the use of the borehole shear tester (BST) In mines. Assembly and procedure sections explain how the equipment is assembled and used properly. Schematics of the BST, limitations, test hole specifications, data recording and calculations are all explained briefly, and an example of the data collecting and calculations is given to assist understanding.

Jan 1, 1981

By S. Ralph Austin

This Bureau of Mines investigation determined the effects of so-called annealing at high temperatures on radon-222 emanation from domestic uranium ores. Concurrently, a method was developed for closely estimating the emanation coefficients of hot samples from measurements of their gamma activity after cooling. Emanation coefficients of 102 samples from 14 domestic areas of past, present, and possible future uranium production were investigated using modifications of the closed-can, gamma-only assay method at and after cooling from 100° to 1,000° C. True annealing probably does not occur below 500° C. In limited investigations at 500° C and above, effects of annealing are masked by the effects of other parameters. Emanation is commonly less at one or more of the steps investigated in the 100° to 500° C range than before heating. This decrease is tentatively attributed to water loss at temperatures dependent upon the minerals present. The average sample emanates least at 300° C; emanation increases with higher temperatures to at least 900° C. Emanation decreases sharply on cooling, but it is partially restored by prolonged exposure to the atmosphere at room temperature. Higher than average emanation of coffinite ores at 500° C and above may be related to destruction of the coffinite crystal structure.

Jan 1, 1979

By L. A. Neumeier

The Bureau of Mines evaluated the properties and anisotropy in properties of rolled Zn-Cu and Zn-0.12 pct Ti-Cu alloys with various copper additions to 1.25 pct. The alloys were rolled cold and at various hot-rolling temperatures to reductions as high as 92 pct after breakdown rolling. The properties are extremely sensitive to various combinations of composition, rolling temperature, and rolling reduction, Zn-Cu alloys can develop good creep resistance, but they are inferior in that respect to Zn-Ti-Cu alloys. For alloys either with or without the titanium addition, cold-rolling results in recrystallization of the matrix and rejection of copper from solution, causing poor hardness, tensile, and creep properties, but high ductility. Peak tensile strengths develop when the alloys are rolled in the range 320° to 400° F, Best creep resistance for Zn-Cu alloys requires higher rolling temperatures when copper content is increased. Creep resistance is best for Zn-Ti-Cu alloys with about 0.75 to 1.0 pct CU rolled near 480° F. Some copper is soluble in the TiZn15 phase, which forms into "stringers" during rolling. The possible contributions to creep behavior of factors such as distribution of second-phase particles, grain size, and preferred orientation are discussed.

Jan 1, 1970

By Sean Gallagher

Study Design. A split-plot experimental design was used to evaluate the influence of posture, trunk angle, and rotational velocity on peak torque output and myoelectric activity during maximal trunk extension maneuvers. Objectives. To determine whether the kneeling posture alters extension torque capabilities in isometric and isokinetic exercises as compared with standing. Also, to ascertain whether recruitment of trunk muscles is modified by such a postural change. Summary of Background Data. Factors such as workplace geometry may force workers to adopt awkward or unusual postures in the performance of manual tasks. An understanding of the limitations placed on strength in unconventional working postures is crucial to the proper design of jobs. Methods. Twenty-one healthy male subjects (mean age = 36 years 7 SD) performed 12 trunk extension exertions in standing and kneeling postures. Isometric tests were performed at 22.5°. 45°, and 67.5° of trunk flexion. isokinetic tests were done at three velocities: 30°/sec, 60°/sec, and 90°/sec. Electromyographic data were collected from eight trunk muscles to assess muscle recruitment under each condition. A prior; orthogonal contrasts were specified for analysis of both torque and electromyographic data. Results. The kneeling posture was associated with a 15% decrease in peak torque output when contrasted with standing; however, no concomitant change in trunk muscle activity was evident. Trunk hyperflexion (isometric tests) and increasing rotational velocity (isokinetic tests) were associated with reduced torque in both postures. Trunk muscle activity was primarily affected by changes in trunk angle and velocity of contraction. Conclusions. A reduced extensor capability exists in the kneeling posture, despite equivalent trunk muscle activity. The similar activation patterns in both postures suggest that the strength deficit does not result from alterations in trunk muscle function. Rather, it may be the consequence of a reduced capability to rotate the pelvis in the kneeling posture, due to a disruption of the biornechanical linkage of the leg structures. [Key words: electromyography, isokinetic, isometric, low back pain, posture. strength1 Spine 1997;22:1864-1872

By Richard Mainiero, James H. Rowland

For many years there have been small scale tests available for evaluating the toxic fumes production by cap-sensitive explosives (DOT Class 1.1), but these could not be used with blasting agents due to the large charge sizes and heavy confinement required for proper detonation. Considering the extensive use of blasting agent in construction and mining, there is a need to determine the quantities of toxic fumes generated by blasting agents. At the International Society of Explosive Engineers Twenty Third Annual Conference on Explosives and Blasting Technique in 1997, the authors reported on a facility for detonating large (4.54 kg), confined blasting agent charges in a controlled volume that had been constructed at the National Institute for Occupational Safety and Health’s Pittsburgh Research Lab’s Experimental Mine. Since 1997, this facility has been used to collect data on toxic fumes produced by the detonation of various ammonium nitrate/fuel oil (ANFO) mixtures and several cap-sensitive explosives. ANFO composition ranging from 1 to 10 percent (pct) fuel oil have been studied. As expected from previous studies, with an increase in fuel oil content the carbon monoxide production increases, while nitric oxide and nitrogen dioxide production decrease. The detonation velocity varies from 3,000 to 4,000 m/sec for the 1to 10 pct range of fuel oil content, suggesting that ANFO mixes with improper fuel oil content may appear to detonate properly, while their fume production differs significantly from optimum. The study also considers such factors as degree of confinement, water contamination, and aluminum content on blasting agent fume production. Results indicate that water contamination of the ANFO has little effect on carbon monoxide production, but causes significant increase in nitric oxide and nitrogen dioxide production. Decreasing confinement from Schedule 80 steel pipe to 0.4-mm thick sheet metal also has little effect on carbon monoxide production, but significantly increases nitric oxide and nitrogen dioxide production. Adding5 and 10 pct aluminum to the ANFO had no clear effect on carbon monoxide, nitric oxide, or nitrogen dioxide production.

By Daniel G. Di Canio

A computer based accident cost indicator model (ACIM) for estimating tangible costs of occupational injuries, illnesses, and fatalities in the U.S. mining industry is described. Studies performed to expand the scope of the ACIM to all mining sectors are presented. Validation of ACIM cost element estimation algorithms with actual costs of mining-related injuries and illnesses are presented. A study of the effect of a fatal accident on production in surface coal and metal/nonmetal mines is presented. The study is based on a sample of 15 fatalities in underground and surface mines. Evidence of significant long- term decline in postfatality production at 6 of 8 underground samples is presented. The average loss is shown to be 1.8% of annual mine production. A study of accident costs in U.S. mining from 1975 through 1981 using the ACIM is presented. The study shows that total annual costs increased from $180,000,000 in 1975 to $379,000,000 in 1981, a 15% annual increase after adjusting for inflation, with mining companies bearing 45% of the total and expected wage losses to mining families accounting for 42%. The study shows total costs of $12,400 per accident and $674,000 per fatal accident for 1981.

Jan 1, 1983

By Charles L. Kimbell

Bulk carriers, freighters, and tankers are the three classes of seagoing vessels engaged in transporting mineral commodities. However, vessels in these classes are not wholly devoted to mineral commodity transport, as seen in tables 16 through 22. Bulk carriers move considerable tonnages of agricultural products as well as crude minerals, their concentrates, mineral fertilizers, and the like. Freighters, owing to their great variety, can be devoted wholly to hauling mineral products or wholly to non mineral goods, as well as carrying mixed mineral commodities and non mineral commodities. They include general cargo ships, full container ships, partial container ships, roll-on/roll-off ships, and barge carriers. Tankers, although largely engaged in moving crude oil and refinery products, also transport liquid chemicals, molasses, wine, liquefied natural gas, and other fluids. Table 16 shows the distribution of the world's merchant fleet by vessel type in terms of the number of vessels, their gross tonnage, and their deadweight tonnage. The increase of nearly 1.5 % in the number of vessels between 1990 and 1991 compared with a 2.7% growth in gross tonnage and a nearly 2.3 % increase in deadweight tonnage points to an increase in the average size of vessels. Of the four categories of vessels reported, all showed increases in number and in deadweight tonnage between 1990 and 1991 except for "other," and on the gross tonnage basis, all groups registered increases. Although physical characteristics of vessels such as size, draft, crew requirements, type of propulsion system, ratio of gross tonnage to cargo tonnage, and fuel costs have undeniable influences on shipping industry performance, problems of and changes in the quantity and types of materials moved also significantly affect the shipping sector of the world economy, and thus have a bearing on the minerals sector of that aggregate. Unfortunately, comprehensive global data reflecting changes in these critical variables are not published.

Jan 1, 1993

By Lloyd A. Morley

Research performed on computer modeling of mine power systems under USBM Grant G0155003 1S described. The work was performed at the Pennsylvania State University from 5 November 1975 through 4 November 1976. Results presented are interim in nature, and future research is planned to integrate the simulations which have been developed. The thrust of this research has been divided into three main areas. 1. Modification of a previously developed model (Mine Power System Simulation or MPSS) to include interactive operation and the use of default (average) load data. 2. Development of a dynamic simulation of interdependent mine power system induction motors. 3. Development of an approach to modeling of motor shaft loading of induction machines for mining operations. During the course of the current year's research, significant results have been achieved in all areas. Construction of an interactive MPSS model has been completed and checked. This simulation was written in APL code and is fully interactive. In addition, default data representing 158 different pieces of mining equipment has been developed for use with the interactive model. Additional work described includes the construction of a dynamic simulation of interdependent continuous miner induction motors and the development of an approach fo: motor shaft load torque computation from experimental data.

Jan 1, 1976

This appendix contains the list of equipment, their corresponding number and their specifications with the quotations from the vendors/ manufacturers who can supply this equipment. The listings are arranged by process plant areas.

Jan 1, 1979

By P. A. Richardson

The current Bureau of Mines active list of permissible explosives includes 76 brands. Eleven are gelatinous and the rest are the granular type. The list of permissible blasting devices comprises five Cardox models.

Jan 1, 1970

The objective of this study was two-fold: 1. To perform a world literature search pertinent to the analysis, selection and design of hoisting systems and their components and to codify the search into a literature compendium. The search resulted in a technical data file of over 1500 hard copy items. The compendium index was also suitable for establishing a comprehensive computer-loaded data base on the subject. 2. To develop a comprehensive system of guidelines to cover salient aspects of analysis, selection and design of electrical, mechanical and structural components of a hoisting system with a view to establish parameters for maximum safety and efficiency of operation, installation and revision of the system. 3. Major mechanical components in the hoist and mechanical drive train are considered. Design and specification criteria based on American standards and practices are developed as they apply to typical mine hoist arrangements.

Jan 1, 1988

By N. Kumar Kittusamy

A field study was conducted to evaluate seat designs on shuttle cars. Eight operators participated in evaluating seat designs on the basis of perceived levels of vehicle jarring/jolting and discomfort. Researchers also measured the levels of vehicle jarring/jolting. Four basic seat designs were compared on low and mid-coal seam shuttle cars during production operations at two underground coal mines. Two seats were currently used on the shuttle cars and another two were NIOSH designs. Objective data were collected using accelerometers with pre-amplifiers and filters connected to a data recorder; whereas subjective data were gathered with a visual analog scale (VAS) and a questionnaire. Results from measured levels of jarring/jolting showed that the NIOSH Seat L2A smoothed out bumps better than any other seats. Using the VAS, mid-seam and low-seam shuttle car operators rated the levels of jarring/jolting and discomfort lower with the NIOSH seat than the other seats. Questionnaire responses indicated that operators rated NIOSH seat designs as more comfortable. This research will provide the industry with better seat designs for isolating jarring/jolting in vehicles. Furthermore, researchers plan to improve the NIOSH seats using information gathered in this study.

Jan 1, 2003

By Steven E. Mischler, Jon C. Volkwein

A diesel particulate matter analyzer capable of direct, real-time measurement of engine exhaust particulate is necessary to effectively institute source control technology currently being used on diesel equipment and to ensure that the control measures are working. To investigate the potential of a differential pressure monitor to measure diesel particulate matter in undiluted exhaust, samples were collected from three different diesel engines-Kubota, Isuzu, and Deutz-running under 12 different RPM and load scenarios. These measurements were compared to elemental carbon concentrations in the sampled exhaust as determined by using the NIOSH 5040 analytical method. Elemental carbon is used as a surrogate measurement for diesel particulate matter. The results of the two data sets were then compared using a linear regression analysis. The coefficient of determination (or R2) was calculated to be 0.98, 0.94, and 0.74 for the Kubota, Deutz, and Isuzu engines, respectively. R2 values of this magnitude indicate that this method can be successful in estimating elemental carbon emissions in the engines tested. In addition, for replicate samples, the coefficient of variation ranged from 7.1% to 10.2% with an average of 8.5%. These data indicate that this method could prove useful to mechanics as they work to maintain engines and DPM control technologies.

By W. R. Byrnes

This project was initiated on October 1, 1980 and will be completed on December 31, 1983. The project was Initially approved and funded by the Office of Surface Mining and subsequently was moved to the jurisdiction of the Bureau of Mines. It was administered through the Indiana Mining and Mineral Resources Research Institute. The research was done to assess reforestation success and ultimate productivity for areas reclaimed under the Surface Mining Control and Reclamation Act of 1977 (P.L. 95-87). The Permanent Regulatory Program for implementation of P.L. 95-87 Includes provisions for revegetation that require seeding of ground cover plants to control erosion until permanent vegetation such as tree species Is established, and restoration of mined land to its original or better productivity. Much of the land to be surface-mined presently supports forest cover and it is anticipated that reconstructed minesoils will exhibit high productive potential for hardwood tree species. Hence, information was needed on compatibility of ground cover and tree seedlings when established concurrently as well as on revegetation success under postmining versus premining conditions.

Jan 1, 1983