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By Doris M. Hyde

In the past, mining has represented between 11% and 12% of the gross domestic product (GDP). In 1982, mining contributed over $150 million to the estimated $1.4 billion GDP.2 Overall economic growth for 1983 was projected at about 2%, primarily as a result of increased tourism. The inflation rate remained at or fell below the 1982 level of almost 4%. The Government continued its efforts to strengthen the industrial base by improving infrastructural systems and the establishment of a free trade zone. Laws against property ownership by foreigners or foreign-owned companies were strengthened, but the prohibition was softened to allow for close family inheritance. Otherwise, Government approval must be obtained to retain property acquired through inheritance, court order, mortgage, or other means. Special consideration was granted to foreign investors seeking to promote industries beneficial to the economy.

Jan 1, 1985

By Edward D. Thimons

Because of the high number of accidental methane gas ignitions in metal and nonmetal mines, the Bureau of Mines searched for a simple guideline that would allow mine personnel to evaluate the methane hazard in a given mine. Air samples were collected by the Bureau in 53 metal and nonmetal mines and analyzed for trace evidence of methane gas. Samples were collected in the returns and at the working faces. Those mines classified as gassy by the Mine Safety and Health Administration had a significantly higher average methane concentration than those classified as nongassy. Of the 9 gassy mines sampled, 7 had methane concentrations above 100 ppm, whereas only 1 of the 44 nongassy mines had a concentration above 100 ppm. The 100-ppm concentration may be used as a simple and convenient guideline for forecasting the methane hazard in a mine, whether or not the mine is classified as gassy. There was no consistent correlation between commodity mined and methane concentration, nor was there a correlation between mine depth and methane concentration. Neither of these factors can be considered a guideline for predicting methane hazards.

Jan 1, 1979

By Jr. Sharkey

The Bureau of Mines investigated gases from flash and laser irradiation of Pittsburgh seam (hvab) coal to determine the action of high temperatures on coal. Temperatures in excess of l,000° C were reached with both types of irradiation. Craters about 300 microns in diameter were produced in the coal with millisecond pulses from the laser unit rated at 1.7 joules' output. Gaseous products from laser and flash irradiations in vacuum contained 21 and 8 percent acetylene, respectively. Diacetylene, vinylacetylene, and other products to molecular weight 130 were indicated in the mass spectrum of the gas from the laser study. Single experiments were also conducted in which the laser energy, particle size of the coal, and atmosphere were varied. The results indicated that the distributions of products obtained from the flash and laser irradiations of coal were different from that produced in high-temperature carbonization.

Jan 1, 1966

By Russell Levens

A strategy for prioritizing mining health and safety research by evaluating the potential for risk reduction through interventions is proposed. Mining has one of the highest incidence rates of injury and disease found in major industries. The main premise of this paper is that often the best opportunities to reduce these rates are not revealed by retrospective analysis of injury and illness data. Instead, a proactive approach is needed that accounts for risks to specific hazards that can be abated by engineering or behavioral interventions. The process proposed here begins with development of prospective interventions. The degree of reduction in risk to be expected from an intervention then is determined from statistics on the mining worker population, the expected degree of success of the intervention, and the expected change in the severity of injuries resulting from the intervention. Three disparate mining health and safety concerns are presented to demonstrate common problems in assessing risks of injury and illness and describe additional data needs. Information on events preceding injuries and illnesses and more detailed demographic data on the mining work force are needed to analyze injury and illness data more precisely. Detailed information on exposure to specific hazards is necessary to evaluate the potential for an intervention to reduce risk of injury or illness.

By G. A. Howes

This is one of a series of circulars dealing with the cost of equipping and developing mining properties in the United States and Canada, prepared and published by the Bureau of Mines in cooperation with various mining and exploration companies. This group of circulars is designed to supplement an earlier series which covered the methods and costs of mining and milling at a large number of producing properties. ACKNOWLEDGMENTS The authors desire to thank Robert A. Bryce, president of Macassa Mines (Ltd.), for permission to use the data presented in this paper, and to acknowledge the cooperation of A. J. Keast, under whose direction as manager the plant was installed and equipped and the shaft was sunk to a depth of approximately 2,000 feet.

Jan 1, 1932

By Robert S. Sanford

This paper deals with truck haulage methods and costs at one of the many open-cut mines that are replacing rail haulage with heavy-duty trucks. At this mine, ore is trucked to a crushing plant, centrally located within one of the open-cuts. The requirements for efficient low-cost truck haulage are: Good trucks designed for heavy loads, adequate truck maintenance, smooth roads, and well-trained truck drivers The weighted average cost of hauling a long ton of ore to the crusher and the waste to the dump was reduced from $0.1993 in 1948 to $0.1114 during the last half of 1949, his corresponds to a cost per ton mile of $0.0864.

Jan 1, 1952

By Hsin Wei Wu

A real-time Diesel Particulate Matter (DPM) monitor has been developed on the basis of the successful National Institute of Occupational Health and Safety (NIOSH) designed Personal Dust Monitor (PDM) unit. The objectives of a recently completed Australian Coal Association Research Program (ACARP) study were to modify the PDM to measure the submicrometre fraction of the aerosol in a real-time monitoring underground instrument. Mine testing focused on use of the monitor in engineering evaluations to determine how conditions can be improved. Studies, including a selection during Longwall (LW) moves as described in this paper, demonstrated how DPM concentrations from vehicles fluctuate under varying ventilation and operational conditions. Correlation between the current SKC DPM measurement system and real-time DPM monitors were conducted and results from six mines show a correlation between elemental carbon (EC) and the new monitor DPM mass ranging from .51 to .81 with R2 >.90. These differences are suspected to be due to variations from mine to mine in aspects such as mine atmospheric contamination, vehicle fleet variations, fuel type, engine maintenance, engine combustion efficiency, engine behaviour or interference from other submicrometre aerosol. Real-time monitoring readily reflects the movement of individual diesel vehicles and allows pin-pointing of high exposure zones such as those encountered where various vehicles work in areas of constrained or difficult ventilation. DPM monitoring approaches that have been available for some time based on shift average monitoring do not readily allow successful engineering evaluation exercises to determine acceptability of pollution levels. Identification of high DPM concentration zones allows efficient modification of mine ventilation, operator positioning and other work practices t o reduce miners? exposures without waiting for laboratory analysis results.

Jan 1, 2010

By Peter F. Steidl

Seven degasification wells have been completed in the Pittsburgh coalbed at the new Emerald mine near Waynesburg, Pa. Funding was provided by the Bureau of Mines to perform stimulation treatments on five of the wells, to show that this is a feasible and economical means of degasifying part of a coalbed. The seven wells ranged in depth from 590 to 910 feet. Stimulation treatments used 25,260 to 42,660 gallons of foam and 7,400 to 12,800 pounds of 20/40-mesh prop sand. Pumping rates were 10.8 to 11.6 bbl/min and treating pressures were from 1,050 to 1,600 psig. On the day following stimulation, gas production ranged from a few hundred cubic feet per day to more than 100,000 cu ft/day.

Jan 1, 1978

By J. E. Tiffany, J. J. McKitterick

"IntroductionThe Bureau of Mines is investigating the fundamental factors in breaking down coal at the face, which govern the production of lump coal in typical mines working, different coal beds. Tiffany and Nelson in 1923-21 conducted tests on methods of blasting and use of different explosives, in a mine working the Pittsburgh bed in Pennsylvania. They determined come of these factors quantitatively, and compared their results with those obtained when the regular mine practice was followed.Results of Previous InvestigationThe tests by Tiffany and Nelson showed that the use of the cartridge of smaller diameter than that used in mine practice, resulted in an increase of 5 per cent in the amount of lump coal passing over a 1-1/4-inch bar screen, with a reduction of 32 per cent by weight in amount of explosive required. On the other hand, they found that on reducing the weight of charge 20 per cent, and using the cartridge of larger diameter, the round would not throw down the coal satisfactorily.Experiments with ""snubbing"" showed a similar improvement in quantity of lump coal, end the coal that was blasted rolled forward into the working place. however, in recent tests at another mine where the coal Lad different physical characteristics, snubbing did not always result in the coal rolling forward, on account of clinging to the ribs, and was not found to be an advantage. Therein the writers of this paper recommend that tests be made before deciding upon the adoption of snubbing in a particular mine."

Aug 1, 1925

By Jeran Paul W., Michael A. Trevits

Subsidence data gathered by the U.S. Bureau of Mines over a series of longwall panels in the Pittsburgh Coalbed were studied to obtain insight as to the role of time in the subsidence process. It was found that subsidence began essentially with undermining and was completed within 1 year. The progress of the subsidence was dependent upon location above the panel. Subsidence in the central area of the subsidence trough, where subsidence is the greatest, was about 90 pct complete by the time the face had progressed a distance equal to one overburden thickness beyond a particular surface point. For a point over the rib of the longwall panel, the subsidence was only about 60 pct complete at this time. Data from three other sites in the northern Appalachian Coal Basin were analyzed to determine if an anomaly or the true characteristics of the subsidence process had been observed. All sites behaved similarly in the central portion of the subsidence trough. However, the subsidence of points over and adjacent to the ribs of the longwall panels was site specific. The fact that movement across the width of the panel was not uniform should be taken into account in assessing damages or the potential for damages resulting from mining-induced subsidence.

Jan 1, 1995

The first metal-mine accident-prevention course was prepared and published in 1942-45 as a series of seven miners' circulars (Nos. 51-57). The scope of the course has been broadened, revised, and brought up to date, and it is being published as a similar series of seven miners' circulars (Nos. 51-57, revised) on accident prevention in metal and nonmetallic mines. These circulars are: Accident Statistics (Miners' Circular 51), dealing with general statistics on accidents and injuries at metal and nonmetallic mines, including causes, costs, and the uses of investigations and reports of all accidents.

Jan 1, 1955

Effective control of respirable dust is one of the most serious problems associated with longwall mining in the United States. This report describes the development and laboratory testing of dust collectors for use on double drum shearers. Systems tested included: ? High Capacity Flooded Bed Scrubber ? Water Powered Extraction Cowls ? Water Powered Extraction Drums ? Water Powered spot Scrubbers. The systems were tested using tracer gas in a full-scale model of a longwall shearer face. This report provides a detailed description of the test facility, test methods, and system test results.

Jan 1, 1982

By Hugo E. Camargo

In an effort to reduce Noise Induced Hearing Loss (NIHL) in the mining industry, the National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop noise controls for mining equipment whose operators exceed the Permissible Exposure Level (PEL). The process involves three steps: 1) Noise source identification (NSI), 2) development of noise controls, and 3) evaluation of the developed noise controls. For the first and third steps, microphone phased array measurements are typically conducted and data are processed using the conventional beamforming (CB) algorithm. However, due to the size and complexity of the machines, this task is not straight forward. Furthermore, because of the low frequency range of interest, i.e., 200 Hz to 1000 Hz, results obtained using CB may show poor resolution issues which result in inaccuracy in the noise source location. To overcome this resolution issue, two alternative approaches are explored in this paper, namely the CLEAN-SC algorithm and a variarion of an adaptive beamforming algorithm known as Robust Capon Beamformer (RCB). These algorithms were used along with the CB algorithm to process data collected from a horizontal Vibrating Screen (VS) machine used in coal preparation plants. Results with the array in the overhead position showed that despite the use of a large array, i.e., 3.5-meter diameter, the acoustic maps obtained using CB showed "hot spots" that covered various components, i.e., the screen deck, the side walls, the I-beam, the eccentric mechanisms, and the electric motor. Thus, it was not possible to identify which component was the dominant contributor to the sound radiated by the machine. The acoustic maps obtained using the RCB algorithm showed smaller "hot" spots that in general covered only one or two components. Nevertheless, the most dramatic reduction in "hot" spot size was obtained using the CLEAN-SC algorithm. This algorithm yielded acoustic maps with small and well localized "hot" spots that pinpointed dominant noise sources. However, because the CLEAN-SC algorithm yields small and localized "hot" spots, extra care needs to be used when aligning the acoustic maps with the actual pictures of the machine. In conclusion, use of the RCB and the CLEAN-SC algorithms in the low frequency range of interest helped pinpoint dominant noise sources which otherwise would be very hard to identify.

Jan 1, 2009

By Suresh K. Bhatt

Although overall worker productivity for U.S. underground coal mines is available, productivity by mining method and seam thickness is not. Mining technology has gone through dramatic changes in the past decade, and the industry has experienced a lack of accurate productivity Figures addressing these changes. This information is of great interest in planning for future mining systems as thick and shallow coal seams currently being mined are depleted and exploitation of thinner, deeper, and better quality seams is considered to partially meet the requirements of the 1990 Clean Air Act Amendments. In a cooperative program, the U.S. Bureau of Mines obtained raw mine level production and related data from U.S. Energy Information Administration for 1989 and 1990 and performed the needed statistical analysis. Base criteria, parameters, and salient results of the mine productivity analysis are presented in this report.

Jan 1, 1994

By M. W. Von Bernewitz, E. H. Denny

The use of oxygen breathing apparatus during rescue and recovery operations at both coal and metal mines has become so commonplace that there is a tendency for the industry not to give such apparetus the full measure of credit that it deserves in any particular disaster , therefore , the data presented herein should give some idea of what has been done in this regard during the past 15 years that is , up to 1910 by the Technologic Branch of the U. S. Geological Survey , and thence ( to the end of 1922) by the U. S. Bureau of Mines .

Feb 1, 1923

By E. M. SEELEY, F. S. LOTT

The total capacity of the natural-gasoline industry to produce light hydrocarbon products increased to 21,322,000 gallons ( 507,670 barrels ) daily on January 1 , 1948 , from 17,928,000 gallons ( 426,860 barrels ) daily on January 1 , 1946. Expansion of the industry in the first two post -war years , 1946 end 1947 , thus averaged 9 percent annually , compared with 6 percent annually in the last two war years , 1944 and 1945 . The number of cycle plants increased only from 37 to 39 in the years 1946 and 1947 , and total capacity of these plants gained 21 percent to 5,857,000 gallons de ily on January 1 , 1948 , represent ing 27.5 percent of the total capacity of the industry , compared with 27.0 percent on January 1 , 1946. All other plants decreased in number in the two-year period from 589 to 510 on January 1 , 1948 , but their total daily capacity increased 18 percent to 15,465,000 gallons . The daily capacity of the average plant in the industry was enlarged from 28,600 gallons on January 1 , 1946 , to 38,800 gallons on January 1 , 1948 , continuing the long -established trend to producing units of greater size and efficiency . The average cycle plant capacity increased from 131,000 gallons daily to 150,200 gallons daily on the same dates as the average capacity of all other natural -gasoline plants increased from 22,200 gallons to 30,300 gallons . Owing to the elimination of small , obsolescent plants in Illinois , Oklahoma , and Pennsylvania , these States experienced the greatest reductions in numbers of plants in 1946 and 1947. In Oklahoma and Texas , several consolidations of two or more plants into a single operating unit were reported . Louisiana and Mississippi were the only States in which the number of plants increased , but daily capacity to produce light products was larger in eleven States on January 1 , 1948, than two years earlier . Added facilities in California and Texas accounted for 41 and 36 percent , respectively, of the national gain in capacity .

Sep 1, 1948

By B. R. Mohal, S. Chander

"A new technique to determine wettability of powders is presented in this paper. In this technique the times for immersion of individual particles from air into liquids, defined as imbibition times, are measured. Through the measurements of imbibition times for a large number of particles, it is possible to determine homogeneity/heterogeneity of a powder sample with regard to its wetting behavior. Quartz particles give a very narrow distribution of imbibition times showing a homogeneous wetting surface whereas coal particles give a broad distribution indicative of the heterogeneous nature of its surface. The imbibition time measurement technique is considered to have certain advantages over other methods to determine wettability of powders in surfactant solutions. In this study we have also compared the imbibition times with the wetting rate mea¬surements obtained by a modified Walker test.INTRODUCTIONSeveral methods are available for determining wetting characteristics of sol¬ids. Each of the methods has been used in the past to obtain very valuable information for comparing wetting behavior of various solids in a given liquid or for comparing the wetting behavior of several liquids for a given solid. Each method measures a somewhat different aspect of wetting and therefore quantitative correlations between techniques have been difficult. A general approach is to use a method in which close similarity between the technique and the application (where results of wetting measurements are to be used) can be maintained. The objective of this investigation was to develop a method which could be used to determine the wetting characteristics of single particles in surfactant solutions. Wetting of individual particles is of importance in cap¬ture of dust particles by sprays of surfactant solutions.METHODS FOR DETERMINING WETTING — A BRIEF REVIEWThe various methods available for measuring wetting characteristics of solids include: contact angle, immersion/sink time, bubble pick-up, induction time, capillary rise, and displacement method measurements. Some of the methods are briefly reviewed in the paragraphs that follow."

Mar 1, 1989

By Laurance L. Oden

The Bureau of Mines is developing nickel catalysts for converting synthesis gas derived from coal to synthetic natural gas. The present report describes the relationship between the composition of aluminum-nickel alloys in the composition range NiAl3 to Ni2Al3 equilibrated at 840° C and the properties of catalysts obtained from them. Methanation activity was determined in the temperature range of 300° to 360° C in a flowing gas stream containing 1 pct CO, 8 pct H2, and the remainder He. One part per million of H2S was added to the gas stream at 400° C to evaluate the susceptibility of catalysts to sulfur poisoning. The total surface area was measured by the adsorption of nitrogen at liquid nitrogen temperature, and the active surface area was measured by the adsorption of hydrogen at room temperature. Total surface area and active surface area were found to increase with increasing proportion of aluminum-saturated Ni2Al3 in the precursor alloy, but methanation activity and resistance to poisoning by H2S were nearly constant. However, the methanation activity of the catalyst prepared from stoichiometric Ni2Al3 was less than half that of the other catalysts.

Jan 1, 1978

By R. B. Corbett

"INTRODUCTION Aluminum and manganese bronzes as a group, may be separated readily from other copper-base alloys by experienced sorters. However, separation of aluminum bronze from manganese bronze is generally a matter of guesswork, so that accurate separation presents a difficult salvage problem.Attempts at separation by the thermoelectric tester. 3/ which had proved successful in solving other sorting problems, showed in this instance that the desired separation was uncertain because of the wide range of composition allowable in each kind of bronze. If only one composition of each kind of bronze were used in industry, separation by the thermoelectric method probably would be simple. However; the variability in composition observed in commercial alloys is so great that the thermoelectric power of the one type frequently overlaps the range of values found for the other. As a result, specimens frequently are classified in the' wrong group.Separation of the two types of bronzes on the basis of measurements of magnetic properties on filings from the various samples also proved unsuccessful because the test results overlapped to such an extent that no clear-cut division could be obtained.Electrode potential measurements were made also on the aluminum and manganese bronzes in the hope of distinguishing between them. A drop of saturated potassium chloride solution was placed on the fresh surface of the metal and the tip of a calomel electrode introduced therein. The voltage generated was measured by connecting the electrode and the bronze part to a research-type potentiometer. Although the voltages generated by the manganese bronze parts were greater than those generated by the aluminum parts, the difference in the closest two sets of readings was not sufficient to warrant a good separation. When a concentrated potassium alum solution was used instead of the potassium chloride solution, a wider divergence of voltage was produced by the various bronzes, but unfortunately readings overlapped in several instances."

Nov 1, 1944

By David E. Van Dillen

This volume is a task-by-task review of work performed in modernizing the BMINES finite element code. Much of the discussion is accomplished by cross reference to the user?s guide, which is Volume I of this two-volume report. The computer program described in this report provides for the static, three-dimensional, linear and nonlinear analysis of structural and geologic systems by the finite element method. The nonlinear material properties currently available in the code include isotropic, anisotropic, variable modulus, plastic, viscoelastic, and viscoplastic. Load application capabilities include gravity loading, surface tractions, and initial stresses. The element library includes rods, beams, plane and axisymmetric quadrilateral elements, three-dimensional brick elements, thick shell elements, and plane, axisymmetric, and three-dimensional joint elements. Special features include the ability to simulate excavation and construction sequences by means of element activity. An automatic mesh generator is included in order to simplify input preparation.

Jan 1, 1981