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By Joanne L. Johnston

Researchers at the U.S. Bureau of Mines have developed a new technique for bonding strain gauges to rock bolts. These instrumented bolts are used to determine load at intervals along the length of the bolt so that reliable, consistent measurements for the design of support systems can be obtained. In this Information Circular, this technique is described in detail and should result in improved miner safety in underground mines.

Jan 1, 1993

By Maria I. De Rosa

Table 46 and figure 16 show the number of fires and fire injuries for metal/nonmetal mills by state during 1990-2001. Table 46 also shows the injury risk rates, employees' working hours, and lost workdays. In all, 77 fires occurred in 26 states. Thirty-seven of the fires caused 41 injuries and 1 fatality (including 5 fires and 3 injuries involving contractors). The yearly average was 6.4 fires and 3.4 injuries. Fifty-four fires with 26 injuries and 1 fatality occurred at metal mills; 23 fires with 15 injuries occurred at nonmetal mills. The Ewhr value was 845 x 106 hr (Irr = 0.01), and the LWD value was 6,681. Minnesota had the most fires (16 fires and 5 injuries), followed by Arizona (9 fires and 3 injuries), Wyoming (8 fires and 3 injuries), Nevada (7 fires, 4 injuries, and 1 fatality), and Texas (4 fires and 7 injuries). Of these states, Texas had the highest injury risk rate value (Irr = 0.033). Table 47, partly illustrated in figure 17, shows the number of fires, fire injuries, fire fatalities, risk rates, employees' working hours, and lost workdays by time period. The number of fires increased slightly during the second period, then decreased during the remaining periods. The number of fire injuries show a decrease during most of the periods (an increase is seen during the third period), accompanied by a decline in employees' working hours during most of the periods. The Irr values follow patterns similar to those shown by the injury values. Tables 48-53 show the number of fires by ignition source, method of detection and suppression, equipment involved, location, and burning material by time period. Figure 18 shows the major variables related to fires for 1990-2001. Table 54 shows the number of fire injuries per number of fires causing injuries and total fires by year, ignition source, equipment involved, and location.

Jan 1, 2004

By Robert H. Ridgway

Scrap iron and steel attracted attention during 1937 because of the unprecedented exports and the concomitant agitation in some quarters to prohibit the exportation of this essential raw material except on license by the President. This report does not attempt to analyze the statistics given in the light of the controversy over the limitation of scrap exports, but it is believed that students of this problem will find many essential basic data in the various tables presented herein. This paper presents the results of the third in the series of annual canvasses on the consumption of ferrous scrap and pig iron in the United States. The study was inaugurated in 1935 by the Bureau of Mines in response to requests from trade organizations and others for detailed

Jan 1, 1938

By Harry R. Nicholls

Preliminary tests on presplitting rock in the presence of an in situ static stress field were undertaken to study the influence of a horizontal static stress field on the creation of a vertical presplit fracture plane. These tests indicated that it is easier to fracture the rock parallel to the in situ maximum compressive stress than in other directions. Instrumented shots indicate that the interaction of stress waves generated by the detonating charges is probably responsible for starting tensile fractures between shotholes and that expanding gases may propagate these initial cracks by a wedging action. The hole spacing for presplitting appears to be equal to the half wavelength of the stress wave. However, wider hole spacing appears feasible if the initial fracture is started by closer hole spacing.

Jan 1, 1966

By G. D. Andria

Contract J0275007 was to consist of a thorough two-phase statistical analysis of respirable coal mine dust data from USBM Contracts H0232061, H0232060, H0230029, H0230031, H0210050, and H0242013. Consequently, BCR cataloged and assembled relevant data items from these contracts and formulated procedures suitable for the evaluation. The selected procedure was a Multilinear Regression Analysis which related dust concentrations measured in the mine to other mine parameters. Under the first phase, a thorough analysis of the date from USBM Contract No. H0230029 was completed. Primary results from this analysis are as follows: (1) The five variables that significantly affect dust concentrations in the return behind the brattice are the spray system utilized; the distance from the face to the return brattice; the return airflow; the production rate; and the water consumption rate, in that order. These five variables describe about 85 percent of the total variation in the return dust concentration. (2) Results at the miner and jack-setter locations were somewhat less conclusive due to the fact that only 17 percent of the variation in dust at the miner could be resolved and only 48 percent of the variation at the jack-setter location could be explained. The decision of the sponsor was that these initial results revealed as much information as could be expected; thus, per instructions from the USBM, the second phase (analysis of the other five contracts) was abandoned.

Jan 1, 1978

By Robert H. Ridgway

Scrap iron and steel attracted attention during 1937 because of the unprecedented exports and the concomitant agitation in some quarters to prohibit the exportation of this essential raw material except on license by the President. This report does not attempt to analyze the statistics given in the light of the controversy over the limitation of scrap exports, but it is believed that students of this problem will find many essential basic data in the various tables presented herein. This paper presents the results of the third in the series of annual canvasses on the consumption of ferrous scrap and pig iron in the United States. The study was inaugurated in 1935 by the Bureau of Mines in response to requests from trade organizations and others for detailed

Jan 1, 1938

By L. W. Brandt

The Bureau of Mines, as part of its mission to effect pollution abatement, conducted research to study various means of dewatering Florida phosphatic clay wastes and reclaiming mined lands. The work was done in cooperation with 10 Florida phosphate companies. During this work, a novel technique to effectively dewater phosphatic clay wastes was developed. The solids contained in the clay waste slurry are slowly compressed by moving wire mesh screens through the system. In a typical application, the screens were moved downward, compressing solids ahead of the screens. The rate of movement of the screens is an important variable in the process. It is believed that the moving screens distort the gel structure of the phosphatic clay system and cause the release of water. Samples of 18 clay wastes, including a high-grade attapulgite from beneficiation plants of the Florida phosphate field, were studied using the method. Typical samples were concentrated from initial solids of 4.7 and 11.9 percent to 16.8 and 25.2 percent, respectively, in 3-1/2 days. The high-grade attapulgite sample was dewatered from 2.7 percent solids to 13 percent solids in the same period.

Jan 1, 1980

By H. E. Camargo

In an effort to decrease noise-induced hearing loss (NIHL) in coal preparation plant employees, the National Institute for Occupational Safety and Health (NIOSH) is conduct­ing research to identify and control dominant noise sources in vibrating screen (VS) machines. To this end, acoustic measurements of the noise radiated by a dewatering VS were conducted at the Pittsburgh Research Laboratory (PRL) using microphone phased-array technology. These measurements allowed for the identification of the screen as the dominant source in the 250 Hz 1/3-octave band. The sidewalls are the major contributors in the 315 and 400 Hz bands, whereas the eccentric mechanisms and the electric motor are the dominant sources in the 800 and 1,000 Hz bands, respectively.

Jan 1, 2009

By D. Ng

A facility to evaluate the fire endurance of mine stoppings was constructed by the Bureau of Mines in the multiple entry section of the Bruceton (PA) Experimental Mine. Stoppings up to 6 by 18 ft can be tested in a manner simulating mine conditions. The stopping is subjected to a 70-min liquid fuel tray fire with an energy output of 75,000 Btu/min. The stopping and adjacent areas are instrumented with thermocouples and heat flux gauges. Data acquisition is by an automatic data logger capable of continuously recording over 100 channels of information. Two 8-in-thick concrete block stoppings and a galvanized steel stopping were tested. A crack developed on the fire side surface of the block stoppings where the flames were most intense. However, the temperatures of the unexposed surfaces of the stoppings never exceeded 800 C and the surfaces were undamaged. The steel stopping retained its structural integrity during the test. The temperature of the unexposed steel surface reached 5000 C, but combustible materials located 1 ft from the surface did not ignite. A 3/4-in-thick coating of construction plaster was applied to the fire side of the previously tested uncoated steel stopping. The quantity of heat energy transmitted across this coated metal stopping was reduced approximately 50%. All stoppings prevented the passage of flame and smoke.

Jan 1, 1988

By B. D. Hanson

An interactive computer program has been developed by the Bureau of Mines which enables the user to identify the effect of cutting system changes on relative dust generation for longwall shearer drums. The program simultaneously evaluates machine and coal seam parameters, and those parameters which the user can control. The user can change one or more of these parameters at a time to determine their effect on relative dust generation, cutting forces, and/or cost. The program is written in the BASIC programming language. A complete program listing is included along with user instructions and sample outputs. This program is a more comprehensive version of the relative dustiness index (REDI) program described in Bureau Report of Investigations 8979.

Jan 1, 1988

By Robert Stefanko

The growing demand for energy during the post World War I and World War II periods has prompted underground coal production to increase rapidly. This has been met primarily by mine mechanization, resulting in the development and application of new mining machine types. Correspondingly, the total connected horsepower of each machine as well as the number employed has enlarged rapidly since 1950. (2,3,9,14,16,17) Electrical consumption for each mine has also grown. In the early years of mining electrical applications, only d-c power was utilized underground. Yet, d-c machine limitations were soon realized, and many a-c systems were substituted to permit economic and efficient utilization of a-c distribution and motors. Due to the attractive torque characteristics, ease of distribution and speed control, several traction applications have continued to be powered by d-c motors. The result has been the now prevalent use of mixed a-c/d-c mine power. However, augmented electrical power employment seems to have added to underground coal mining electrical accidents.

Jan 1, 1974

By Paul G. Swanson

This investigation was conducted to identify the principle causes of spoil instability problems in the Eastern Coal Province. The study was also conducted to develop a matrix to predict the strength and groundwater parameters necessary to conduct stability analyses on a proposed reclamation scheme. Suggestive methods to reduce spoil instability potential are also included. Numerous physical property, strength, compressibility, chemical and mineralogical tests were conducted on mine spoil samples obtained from 11 different surface mine sites. Site characteristics that influence the position of the post reclamation groundwater table were identified. Distinct regions within the Eastern Coal Province with high incidences of surface mine slides or high landslide susceptibility were identified. The application of the predictive matrices developed in this study is for surface mine sites mined and reclaimed in general accordance with the Surface Mine Reclamation Control Act of 1977. A review of current mining practices and the relative effect on spoil stability is included.

Jan 1, 1983

By Kevin M. Connor, O&apos

This report documents-the process of literature review, site selection, instrument installation, data acquisition, and preliminary data reduction performed to evaluate the influence of rock mass discontinuities on coal mine subsidence. A system of surface, subsurface and mine level instrumentation was installed at the Armco No. 7 Mine in Montcoal, West Virginia where the overburden varied in thickness from 630 to 1040 feet. Survey monuments, borehole pressure cells, full profile borehole inclinometer-extensometers, mine level extensometers, stressmeters and tape extensometer convergence stations were installed to monitor displacements and stress changes. Final design of the instrumentation system was based on: a) review of available information, b) field mapping and analysis of areal photography, c) drilling, and d) borehole geophysics. The report contains the complete graphed data of stress and displacements accompanying the longwall mining of a 4800 ft long by 480 ft wide coal panel.

Jan 1, 1983

By Robert W. Geehan

"INTRODUCTION The Bureau of Mines, in cooperation with the Federal Geological Survey, explored the Crowell fluorite mine by core drilling in 1945. Claims investigated are in sec. 14, T. 12 S. R. 47 E., M. D. B. & M., in southern rye County, Nev., about 5 miles east of 'Beatty.The twelve holes drilled by the Bureau totaled 3,661 feet. During 1945 the mine operator drove extensive exploration drifts, in part to verify results of the Bureau's work. The drilling program was designed to test for extensions of ore bodies known in the mine.The Crowell mine has shipped Ore to steel plants on the west coast for the past 20 years. During the war this market called for all the fluorite the mine could produce, but previously there were periods when it was difficult to sell ore or concentrates.ACKNOWLEDGMENTSIn its program of exploration of mineral deposits, the Bureau of Nines has as its primary objective the more effective utilization of our mineral resources to the end that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each exploratory project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual exploratory work, and prepares the final report. The Metallurgical Branch, R. G. Knickerbocker, chief, analyzes samples and performs beneficiation tests. Both these branches are under the supervision of Dr. R. S. Dean, assistant director.Special acknowledgment is due to Glenn Allen, district engineer;A. C. Johnson, chief, Reno Division, Mining Branch; S. R Zimmerley, chief, Salt Lake City Division, Metallurgical Branch; W. R. Thurston of the Federal Geological Survey for advice on geological problems; and J. Irving Crowell, Jr., operator of the property, for his cooperation."

Nov 1, 1946

By Joseph Grumer

An instrumented spherical vessel has been used for many years to study laminar combustion waves. Concurrent measurements of flame speed and pressure-rise rates have led to evaluations of burning velocities, the pressure dependence of the burning velocity, and the expansion ratios of the gases passing through the combustion wave. For the most part, these studies have involved flames initially at atmospheric or subatmospheric pressure. The old spherical vessel used by the Bureau of Mines was not designed for use at elevated pressures. Moreover, being made of wrought iron, it was susceptible enough to corrosion to prohibit its use with many combustible mixtures that figure in industrial research. In mid-1956, under sponsorship of the Office of Naval Research, the Bureau undertook the development of a stainless steel spherical vessel capable of withstanding explosions of gaseous mixtures at initial pressures as high as 20 atm. and initial temperatures as high as 250° C. The design called for a double array (cross) of closely spaced small windows for observation of the flame as it traversed the vessel and a piezoelectric transducer to measure concurrently pressure-rise rates. Because no commercial contractor was willing to bid on the construction of such a vessel, it was built at the Bureau's Bruceton machine shop.7

Jan 1, 1961

By W. M. Deaton

The formation of gas hydrates in natural-gas pipe lines depends on temperature and pressure conditions in the lines as well as on the presence of condensed water. The operating pressure in a pipe line may be determined easily and usually is available from the records of operation, but the temperature seldom is known. In cooperation with the American Gas Association, the Bureau of Mines, in its investigation of gas hydrates, conducted a pipe-line-temperature survey and studied underground temperatures at depths at which pipe lines ordinarily are buried and the relationship of these temperatures to prevailing atmospheric conditions. A similar but mere limited study of this type was conducted by engineers of the Bureau of Mines a number of yours ago.4/ A summary of the earlier findings was included in a general report by the Bureau on the flew of natural gas through high-pressure transmission lines.5/ In the present study, data on temperature variations were obtained at several places widely separated geographically. This information should assist pipe-line engineers in designing and operating natural-gas pipe lines.

Jan 1, 1941

By D. A. Lucero, J. E. Brockmann, L. A. Mondy, K. L. Rubow, D. J. Rader

"Department of Mechanical Engineering, University of Minnesota, Minneapolis, MNExperimental and correlated stage responses (the fraction of particles entering an impactor that are collected on a stage) are presented for the Andersen Mark III and Marple personal cascade impactors. The impactors were operated upright and fully assembled so that interstage interference and wall losses could be properly studied. The observed stage responses showed maxima that fell significantly short of unity, meaning that a monodisperse aerosol is never collected exclusuvely on one stage, but is distributed among several stages and internal losses. Correlations for the stage responses are presented so that the experimental results can be used to determine size distributions with available data-inversion algorithms. Simulations with log-normal distributions show significant differences between dpa50 histograms and the more accurate distributions that result by taking the response functions into account.Cascade impactors are widely used for the measurement of aerosol size distributions; their ruggedness and simplicity of operation make them an attractive choice for a variety of environments. In one common application, the aerosol of interest is drawn through the impactor, and the amount deposited on each stage is determined gravimetrically. The primary objective is to extract as much information as possible about the initial size distribution from the resulting set of weights. Unfortunately, the reconstruction of contin-uous size distributions from finite data sets is an ill-posed problem. Not surprisingly, a variety of such reconstruction techniques are presently in use; the success of each method depends on the particular nature of the aerosol sample and the instrument response.Inversion of impactor data by any of these techniques requires that the response functions for each stage be known. The stage response function gives the fraction of particles entering the impactor that deposits on that stage. Values of the response function range from zero to one, and depend on impactor operating conditions (e.g., geometry, flow rate, and gas properties) and particle properties (e.g., diameter, density, and shape factor). As interstage interferences and particle losses will affect each stage's response, experimental determination of stage responses should be made for fully assembled impactors. Unfortunately, impactor stage response functions are rarely reported; rather, single-stage efficiency curves are given that provide an incomplete description of impactor performance.This paper presents experimental stage responses for two fully assembled cascade impactors: the Andersen Mark III and Marple personal impactors (model 298, Andersen Samplers, Inc., Atlanta, Ga.). These calibrations were performed with monodisperse liquid droplets for both impactors and also with monodisperse solid spheres for the Marple personal impactor. The calibration results for the Mark 111 impactor presented here have been previously reported in the response-function format (Rader et al., 1989). The calibration results for the Marple personal impactor, however, were originally presented in the single-stage efficiency for¬mat (Rubow et al., 1987) and have been reanalyzed in this work. Losses within both impactors are considered, and their treat¬ment within data inversion techniques is dis¬cussed. In addition, correlations for each impactor's response functions are presented so that these calibration results can be easily included in data-inversion algorithms. Size distribution inversions using these response correlations are compared with the standard cut-point method for two lognormal test dis¬tributions."

Mar 1, 1992

By J. B. Elizondo

This paper, which describes mining methods and practices at the Piokee mining unit and the Piokee expertmental mining project of The Eagle-Picher Co. in northeast Oklahoma, is one of a series being prepared by the Federal Bureau of Mines on mining methods, practices, and costs in various mining districts of the United States. The Piokee unit, comprising the Piokee, Rowe, Lucky Syndicate, and parts of the Netta White and Otis White leases, is in the SW1/4, W1/2NW1/4SE1/4, and W1/2SW1/4SE1/4 sec. 17, T. 29 N., R. 23 E., Ottawa County, Okla. (figs. 1 and 2), The 200-acre tract is adjacent to the town of Picher and near the heart of the Picher field of the Tri-State zinc-lead mining district.

Jan 1, 1959

The coal reserve base is defined for coalbeds having sufficient thickness for underground mining within a depth range compatible with economic recovery. The reserve data are compiled by the Federal Bureau of Mines by updating and reevaluating previous estimates of the U.S. Geological Survey, State geological surveys, and others. Through the application of computer techniques, the tonnages are compiled by State, county, coalbed, and rank. Coal reserve base is allotted to sulfur categories by a statistical apportionment of data from available Bureau of Mines reports and records. The coal reserve base in those States east of the Mississippi River, minable by underground methods, is estimated to be 169 billion tons in coalbeds greater than 28 inches in thickness to a maximum depth of 1,000 feet. Excluding those coals in reliability categories other than measured and indicated, the underground reserve base includes 162 billion tons of bituminous coal and 7 billion tons of anthracite. Of the total, 27 billion tons contains 1.0 percent or less sulfur. Most of this low-sulfur coal is in the southern Appalachian area. Approximately 16 percent of the underground reserve base is without available analyses. Included in this report is a glossary of terms applicable to a classification system for coal resources and reserves. The purpose of this system is to provide a common yardstick for determining coal resources and reserves.

Jan 1, 1974

By Daniel L. Ng

This Bureau of Mines report describes the results of scanning electron microscopic (SEM) studies of the combustion residues of carbonaceous dust particles resulting from explosions and thermal ignitions in laboratory and full-scale mine tests. The dusts studied varied widely in rank and volatility: Pittsburgh seam bituminous coal (35% volatility), Pocahontas seam bituminous coal (16% volatility), anthracite (7% volatility), graphite, and diamond. The most systematic explosion studies were performed in an 8-L chamber with narrow size distributions of Pittsburgh coal dust with surface mean diameters of 2, 22, and 84 pm. Experiments were conducted mainly in air, with some data obtained in 50% 02. Observations of the bituminous coal explosion residues showed particles with rounded edges, particles with blowholes, and some cenospheres. The lower volatility dust residues showed fewer changes from the original, unburned dust. In addition to the experimental studies, results of SEM observations of residues from a mine explosion disaster are reported. Comparison of such residues with those from the laboratory and experimental mine explosions can help investigators determine the extent of dust participation in the disaster and in identifying the possible ignition sources.

Jan 1, 1983