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By John Rusnak

The Coal Mine Roof Rating (CMRR) is a practical rock mass classification system for use in design of mine openings. Data can be obtained for this purpose from exploration drill cores if simple geotechnical logging and rock mechanics testing is conducted. The CMRR is an excellent method to quantify rock characteristics for engineering purposes. It bridges the gap between geologic description and engineering design. The CMRR was utilized in the design of a 10,000 fl. long coal belt conveyor tunnel connecting an Eastern Associated Coal Corp. mine and preparation plant in Boone County, West Virginia. Data gathering and analysis techniques are discussed involving the calculation of the CMRR and its application in the design of the tunnel, which was driven through a thin coal bed zone. The preliminary findings have correlated well with actual roof and mining conditions encountered during driving the tunnel and it is concluded the CMRR is an effective method to utilize geologic data from exploration core holes for engineering analysis and design.

Jan 1, 1998

By George T. Faust

The petrographer engaged in examining the products resulting from the beneficiation of ores and rock minerals is constantly required to develop new means and methods of assaying microscopically the results of such operations. From time to time investigators have published descriptions of apparatus that have aided in solving problems in processes f physical separation. Thus, in 191.9, Coghill and Bonardi 31 published a paper covering the application of the binocular microscope and camera lucida to the microscopic analysis of pulverized ores. Similar work has been published by Schneiderhohn 4/, Schwartz 5/, and Head and his associates6/, 7/, 8/. The present paper goes further and considers application of the polarizing comparison-microscope to problems directly concerned with mineral dressing where it is desirable to compare analogous products, and in addition it suggests new uses in various related fields. This work was conducted under the cooperative agreements of the Southern Experiment Station of the Federal Bureau of Mines and. the University of Alabama.

Jan 1, 1940

By Thomas Trochalides

Newtown Creek Water Pollution Control Plant in Brooklyn, NY is the largest of 14 Water Pollution Control Plants in New York City. It services over 1 million people with a current processing capacity of 310 million gallons daily. Upgrades to the plant have been underway since 1998. This paper details the foundation elements installed in three separate contracts during 2009: NC-41F, NC-36G, and NC-47G. The elements are Concrete-Filled Pipe Piles, H-Piles, Steel Sheet Piling, Secant Walls, Drilled Caissons, and High Capacity Micropiles. Soils on the site consist of fill over organic silty clay and silty sand. Beneath the organic layers lie lake sand and varved silt and clay, sitting atop glacial till and rock. Due to Federal Mandates, certain plant capacity and secondary treatment requirements had to be met by specific dates. Failure to meet the requirements would have an adverse affect on the NYC areas being serviced. Further complicating the project, the existing plant operations had to be maintained throughout the entire construction phase. To accommodate the constraints of the project, new specialty equipment and several key redesigns were used to maintain construction schedules

Jan 1, 2010

By Merle L. Bowser

The Bureau of Mines has developed a portable recording methanometer that utilizes the Bureau's methane sensor. The methanometer can operate continuously for at least 30 hours on small, sealed, rechargeable lead-acid batteries.

Jan 1, 1969

By George S. Rice

The following paper was presented at an International Conference on Mine Safety Research held at Dortmund, Germany, September 23-28, 1935, inclusive. This conference was attended by representatives of Belgium, France, Germany, Great Britain, and the United States ands by invitation, Czechoslovakia, Poland, Spain, and Russia. The first international conference of representatives of mine-safety, research stations was held the United States Bureau of Mines Pittsburgh Experiment station in 1912 .4/

Jan 1, 1936

Adverse ground behavior events, such as convergence and falls of ground, are some of the most significant challenges and hazards in underground mines. Our goal is to work toward mine-wide, digital, and real-time three-dimensional geotechnical situational awareness and predictive capabilities in complex underground mining operations. This will benefit operators, engineers, and management by enabling them to develop a more proactive approach to ground control. To this end, and inspired by research in the field of remote sensing and autonomous robotics, this paper assesses the potential of mobile light detection and ranging (LiDAR) data acquisition for high-frequency, high-accuracy monitoring tasks in Global Navigation Satellite Systems (GNSS) deprived underground mines. Limitations of current monitoring practices are reviewed. Relevant academic and commercial developments in the fields of indoor mobile mapping systems (MMSs) and simultaneous localization and mapping (SLAM), robust autonomous robotic platforms, and automated remote sensing data processing are highlighted, and their current shortfalls are evaluated. To conclude, the ramifications of this work for the development of future autonomous underground mine monitoring solutions are discussed.

Jul 28, 2020

By William D. Hissem

For those blasthole applications which require the use of holes ranging from 1” to 5.5” in diameter, the use of top hammer drills has been the equipment of choice for several generations of drillers. Pneumatic compressed air and hydraulic compressed oil systems represent the primary technologies which are available to the drilling practitioner. While both employ the same operating principals, the characteristics of performance, cost, and reliability can be markedly different between technologies and manufacturers.

Jan 1, 1998

By Lawrence K. Barker

Crude shale oil produced by underground retorting of Green River Formation oil shale was hydrogasified over a cobalt-molybdate-on-alumina catalyst at operating temperatures ranging from 800° to 1,300° F, pressures of 500, 1,000, and 1,500 psig, and a liquid hourly space velocity of 1.02 volumes of oil per volume of catalyst per hour (Vo/Vc/hr). At a temperature of 1,300° F and pressure of 1,500 psig, 94 weight-percent of the liquid feed was converted to gas containing 72 volume-percent methane. With two reactors in series at a temperature of 1,170° F in reactor 1 and 1,260° F in reactor 2 and a pressure of 1,500 psig, 97 weight-percent of the liquid feed was converted to gas with a methane content of 75 volume-percent. Liquefied petroleum gas (LPG) was hydrogasified at operating temperatures ranging from 500° to 1,400° F at a pressure of 500 psig over a cobalt-molybdate-on-alumina catalyst. Similar experiments were made with an empty tubular reactor. The data indicate that gasification reactions in the presence of a cobalt-molybdate catalyst change from predominantly a catalytic (carbonium ion) reaction to predominantly a thermal (free radical) reaction at temperatures greater than 1,100° F. The data also indicate that a reaction temperature of 1,350° F is necessary at the space velocities used in this investigation to make a synthetic natural gas (methane content of 90 volume-percent) from in situ crude shale oil.

Jan 1, 1975

By R. T. Langland

Using a finite-element computer model, we have conducted an analytical study of roof behavior in a room-and-pillar coal mine. With standard engineering property in formation and a computer code developed for the Bureau of Mines to calculate roof sag, convergence, and roof-bolt load change, we have calculated the stability of roof-support systems and compared the computed data with experimental data collected during a field investigation at three test sites, one in a development area and two in production areas of a coal mine.

Jan 1, 1978

By R. L. Blake

The crystal structure of hematite, a-Fe203, has been refined as part of a continuing study of the behavior of phases in the Fe-O system during reduction and oxidation. Three-dimensional diffraction intensities were collected on two spherical single crystals of hematite with a semiautomated Buerger single-crystal diffractometer. The first crystal refined was a natural Elba hematite with minor impurities. The other, a synthetic crystal, was refined at the request of Mossbauer spectroscopy investigators concerned with impurities in the natural crystal. The structure has been refined with a least-squares program and the final structure for the natural crystal irradiated with CuKa-radiation gave a discrepancy factor (R) of 3.65 percent using 49 unrejected reflections of the 51 measured. For the synthetic crystal, using MoKa-radiation, the discrepancy factor converged to 2.8 percent using 95 unrejected reflections and was 3.3 percent for all 109 reflections. The structure model of Pauling and Hendricks has been confirmed with essentially no change in the iron coordinates and approximately a 5-percent change in the oxygen coordinates. Selected interatomic distances and angles were calculated as were anisotropic temperature factors.

Jan 1, 1970

By Virgil A. Marple

The primary purpose of this contract was to evaluate methods and techniques by which the size distribution acid concentration of mining-related dusts can be measured. One result has been the development of a portable, battery-operated optical particle counter/ multi-channel analyzer system which can he used to determine the size distribution and concentration of mining aerosols. One important aspect of this program has been the development of a calibration technique which relates the output of the optical particle counter to the penetration of the particles through an impactor: This results in a calibration curve in terms of the aerodynamic or Stokes' diameter or the aerosol particles. Using this technique, calibrations were performed on coal, silica, Arizona road dust, potash, and rock dust (corer ore) aerosols. Another task of this program was the calibration and evaluation of the GCA respirible dust monitors (RMD) 101-1 and 301. The results of evaluation showed that the instruments were within the manufacturer's specification of ±25% of the true mass concentration up to about 15 mg/m , if the dust particles were in a size range from about 0.7 to 10 µm aerodynamic diameter. Particles smaller tan about 0.7 µm were not collected by the instrument and particles larger than about 10 µm were lose in the inlet. Other tasks included performing field studies in cooperative research programs with the Bureau of Mines personnel, development of a portable polystyrene latex generator for use in optical particle counter calibrations in the field. The incorporation of impactor classification devices on the inlets of aerosol mass measuring instruments to give mass size distributions, and a study of the density of coal particles as a function of the particle size.

Jan 1, 1977

By J. S. Coats, G. E. Patts, N. Hughes

Conventional sampling methods are known to suffer from the variable loss of fine gold by elutriation. Freeze sampling yields representative and quantitative data that, when combined with information on the sedimentology of gravel-bed rivers, may facilitate the development of improved dispersion models for source detection. It is suggested that freeze sampling may have particular application to the orientation stage of a large gold exploration survey

Jan 1, 1991

By Richard S. Fowkes

Advanced technology, including automation and computerized information systems, is being adopted in mining at an ever-increasing rate to improve safety and productivity and to decrease overall costs. This U.S. Bureau of Mines report focuses on the human factors issues related to advanced technology. Among the significant facts discovered were the following: Experts studying tile design adoption, and implementation of new technology have stated repeatedly that human factors specialists should be involved from the early planning stages, through design and fabrication, and up to and during production, since human factors has been consistently identified as the biggest obstacle to the efficient utilization of new technology. Also, middle management is generally the greatest obstacle to the adoption of advanced technology, this technology can give rise to worker alienation, boredom, stress, job insecurity, and a sense of isolation; training most of the present work force is more cost effective than hiring new workers; workers are willing to accept new technology if they are given a voice in its implementation; the social and the technical systems should be jointly optimized; and with the intro¬duction of advanced technology, the cognitive or mental, rather than the physical, aspects of human-machine interaction must be emphasized.

Jan 1, 1994

This report summarizes the results of several field tests conducted by Collins for the Bureau of Mines under contract S0122076 and contract H0232056. The field projects represent a part of Collins continuing effort on a broad study of coal mine communications. These experiments analyze the propagation characteristics of radio signals in a working coal mine environment. The intent of the program is to provide basic propagation loss characteristics by which we may evaluate various approaches to an integrated mine communications system. The goal of such a system is to satisfy both operational and emergency communications needs in the mine.

Jan 1, 1974

By Eugene T. Sheridan

The Bureau of Mines annually canvasses the peat producers in the United states and publishes economic data on the peat industry, based upon reports submitted by producers. This publication lists all producers that reported commercial production to the Bureau for 1960 and presents data on individual plants. The companies named herein represent virtually all commercial producers, although a few small companies may not have been canvassed as the industry has many small operations that operate intermittently. Output of the various companies listed ranged from a few tons to more than 50,000 tons. Peat is included in the Bureau's annual surveys of the mineral industries because peat is classified as a mineral fuel. Although none is used for fuel in the United States, peat is a potential source of energy and ranks as one of our large mineral resources. The domestic peat industry sells peat, chiefly, for use as a soil amendment for general soil-improvement purposes. During the past decade the industry has expanded rapidly with operations increasing from 45 in 1947-494/ to 115 in 1960. Output during this period has more than tripled, increasing from 131,782 short tons to 470,889 short tons.

Jan 1, 1961

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

To meet the energy requirements, hydroelectric projects are planned and executed in many countries. Though these projects requires a high capital investment, the returns are regular with minimum maintenance after commissioning of the project and are ecofriendly. Bhutan is situated in the eastern Himalayas and covers an area of 38,394km2 (14824.01sq. miles. It is bordered by India in East, South and West and by Tibet in the North. The hydropower potential of the country is estimated at 30,000MW, out of which around 5% has been harnessed.

Jan 1, 2016

By S. J. Lui

Sodium oleate was an effective diaspore collector, whereas chelate collector OL2 showed certain collecting power over diaspore and nonionic surfactant OL3 showed little collecting ability. Then experiments were carried out using sodium oleate as the main collector with the addition of OL2,OL3 to study the influences on diaspore flotation, it could be seen from the experiments that accelerants had a marked influence on the recovery of diaspore, which could be raised by 10%, and the addition sequence also affected the flotation behavior: the best results could be gained when the accelerants were mixed thoroughly before adding and the best ratio of collector OL1 and accelerant OL2, OL3 stood at 30:2:1. Based on the calculation of the ingredients in the sodium oleate solution, sodium oleate reacted with surface of the mineral and formed the acid-soap polymer [HOl?Ol-] when pH was about 9. Zeta potential test showed the accelerant promoted the absorption of collector on the mineral surface, which lowered zeta potential. As could be seen from surface tension experi-ments, the addition of accelerant OL3 lowered the CMC value of OL1 solution, which was equiva-lent to raise the power of the agents. Further Infrared Ray experiments showed the co-absorption of OL1 and OL2 make aluminum oleate on the mineral surface more stable. Up till now, the mixed reagents with sodium oleate as the main collector, combined with other two accelerants had been used in the Zhongzhou concentration plant, which is the first diaspore flotation plant in China.

Jan 1, 2014

By G K. N Subasinghe

Metallurgists operating Knelson Concentrators (KC) often rely on manufacturerÆs recommendations for selecting operating parameters, such as fluidising water flow rate and cycle time. Recent studies have shown that these parameters are not only dependent on the machine parameters but also on the feed characteristics, such as size distribution of the gold and gangue particles and the composition of its constituent minerals. It is known that a particle entering a KC initially traverses a circular path within the bowl. For a particle to maintain a given orbit, the required centripetal force must be supplied by external means. It has been argued that this centripetal force, which is dependent on the mass of the particle, its radial position and the rotational speed of the bowl, is provided by the fluid drag force created by inwardly moving fluidising water and the BagnoldÆs force created by the particle/particle collisions. Depending on the fluidising water flow rate, one of two situations can occur where the porosity of the bed increases or decreases, which influences the amount of material retained within the bowl. The amount of material of a given size and density retained in the bowl is thus dependent on the extent of the centripetal force provided. Based on the above concept, a criterion that can be used to predict the amount of material recovered in the bowl has been derived and validated by experimental data. It may also be construed that this criterion demarcates the transition of the bed from a packed-bed state to a fluidised state. By identifying the transition values for the different constituent mineral particles in the feed, it is possible to estimate the optimal fluidising water flow rate that would maximise gold recovery while minimising gangue recovery. In addition, the kinetics of gangue displacement by incoming heavy mineral particles were also studied using synthetic mineral mixtures. The experimental data suggests that this process follows first order kinetics and that the build-up of heavy mineral reaches a maximum. A model has been proposed to predict the optimal batch cycle time for a KC in terms of the feed characteristics and machine operating parameters.

Jan 1, 2006

Collins Radio Company, through this contract with the Bureau of Mines, has conducted a System Study of Coal Mine Communi¬cations. The program was a three phase program to establish a data base, perform communication system analysis and optimi¬zation, and prepare equipment specifications to be included in this final report. At the start of establishing a data base both a knowledge of mine communication and coal mines in general was obtained. Communication system requirements and constraints were determined along with a survey of current and potential mine communication equipment. An investigation was completed concerning theoretical LF and VLF propagation characteristics, and UHF propagation tests were conducted in a working coal mine. Different mines were contacted and on-site surveys completed with respect to coal mine communication requirements.

Jan 1, 1973