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By Raymond L. Carpenter

In connection with its continuing studies of the characteristics of alloys and alloying elements, the Bureau of Mines investigated the crystal structure of fused boron. This report describes how the structure of fused boron was found to be rhombohedral by the powder method for crystal-structure determinations by X-ray diffraction. The determinations of the crystal structure of boron reported in the literature were made on crystals prepared by various methods such as electrolysis, thermal decomposition of a boride, or by hydrogen reduction of boron tribromide. Table 1 summarizes the data found in the literature on the crystal structure of boron. The information shows the following: (1) Three structures have been reported for boron, (2) boron prepared by different processes--or even by varied conditions of a process--produces crystals of different structure, and (3) no information is given on the crystal structure of fused boron.

Jan 1, 1960

Design a high-production coal mining machine with inherent low dust generation and low frictional ignition potential. Approach Constant depth linear cutting (CDLC) provides a longterm solution to excessive dust generation from shearers and continuous mining machines through new design of the rotary drum culling system. Problems with rotary drum systems, which must be eliminated to control the dust generation at the source, include the effect of a con¬stantly varying depth of cut using fixed bit spacing, secondary fragmentation of already broken coal and, frictional heating of bits and entrainment of dust by fanning action due to high drum rotational speed, Each bit on a rotary drum enters the coal face at zero depth of cut, goes to some maximum depth at the horizontal centerline during sump, and exits at zero depth.

Jan 1, 1989

By J. Torma-Krajewski, M. Lehman

In 2005, NIOSH and Badger Mining Corporation entered a partnership to implement ergonomic interventions, including a systematic process, to address exposures to risk factors that may result in musculoskeletal disorders or other types of injuries/illnesses. As a result of this partnership, an ergonomics process was integrated with the existing safety and health program to promote an on-going application of ergonomic principles, and over 40 task-specific interventions were implemented during the first year of the process. This paper presents details of the process integration, and several examples of task-specific interventions that reduced exposures to risk factors.

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 Peter L. Swanson

NIOSH has developed an automated PC-based seismic monitoring system for use in mine ground control studies. The distribution and coordination of data acquisition and processing functions across a local area network (LAN) is a central feature of the system. Design requirements include (1) the use of lowcost, off-the-shelf, data acquisition and computer hardware, (2) the capability of automatically merging waveform data sets from different types of monitoring systems, (3) delivery of raw and processed data underground and on the surface, as well as to remote sites, and (4) automated data collection and processing over long periods of time without the need for human intervention. Current mine-wide installations utilize multiple, autonomous seismic networks located both underground and on the surface and provide 20 to 40 stations within a radius of several kilometers. Event locations, magnitude estimates, and other processed data are distributed for display and analysis on network nodes both underground and in the offices of mine engineers and managers. This paper describes the system's hardware and software components, examples of installations in hard-rock and coal mines, and a few observations from western U.S. longwall coal mines.

By Pablo Velasco

Ecuador had limited mineral output, al-though the Government attempted to stimulate metallic mineral exploration and also evaluated a gypsum and a phosphate deposit. A pilot plant to exploit gold deposits was established, and there was extensive gold exploration activity in southern Ecuador. Domestic output of iron and steel declined sharply. Among all minerals, petroleum output was the dominant factor with both exports and production increasing significantly over that of 1988. Crude oil exports contributed 63% of total export earnings and about 70% of the central Government's revenue.

Jan 1, 1986

By Michael J. Brnich

Since 1991, Pittsburgh Research Center (PRC- formerly part of the Bureau of Mines) researchers have recorded extensive interviews with 30 individuals who are experts in the area of mine emergency response. These individuals, who have an average of 35 years of mining experience and 29 years of mine emergency response experience, related stories and observations from events that they experienced during their combined 850 plus years in mine emergency response. The purpose of this effort was to gather information that could be passed onto both today?s and tomorrow?s mine emergency responders to train and guide them in handling future events.

Jan 1, 1997

By Margaret R. Egan

In an underground mine fire, a toxic mixture of combustion product gases and particulate matter is transported by the ventilating system endangering everyone downstream. To determine the magnitude of the problem that these toxic combustion products pose, the U.S. Bureau of Mines is investigating the combustion products of typical materials found in underground mines. The total toxicity of the combustion products depends upon the evolving gas species and particulate matter, the amount of material involved, and the ventilation rate. In a simulated mine environment, the products from smoldering poly- vinyl chloride (PVC) brattice and conveyor belting were analyzed for gas concentrations and smoke characteristics. The primary toxic gases are hydrogen chloride (HC1) and carbon monoxide (CO). Smoldering conveyor belts are more detectable than smoldering PVC brattice cloths. These results, combined with previous analyses, are used to estimate relative toxicities, product levels, and detect-ability of smoldering mine combustibles.

Jan 1, 1992

By Nicholas T. Zilka

One mineral deposit in the Golden Trout Wilderness has potential. The currently producing Pine Tree Mine on the Little Kern River has an estimated 120,000 tons (109,000 t) each of indicated and inferred reserves averaging 0.77 percent tungsten trioxide. No apparent potential exists for base or precious metal or other mineral deposits. INTRODUCTION The Golden Trout Wilderness, established by Congress in 1978 under Public Law 95-237, encompasses 240,000 acres (97,000 ha) of conifer-forested, rolling, upland plateau at the headwaters of the Kern River in Inyo and Sequoia National Forests (fig. 1). Abundant streams locally contain Golden Trout, namesake of the area. Major roads serve the area to the west and east of the Wilderness; access is poor to the north and south.

Jan 1, 1982

By George S. Rice, L. C. IlsLey

"A remarkable explosion of fire-damp caused by a discharge of lightning at the new shaft at the Sitalpur coal mine, has been reported by the Chief Inspector of Mines of India, who gave the following details:""The explosion occurred during a thunderstorm, and the evidence showed that a flash of lightning had, to all appearances, passed down the shaft caus¬ing disruptive discharges at certain points between the guides and the winding rope, rending the latter at two places situated respectively .228 .feet and 278 feet from the surface, The distance between the winding rope and the side of the shaft was 5 feet 4 inches, indicating a spark gap ;of this width, and an intensity of discharge which could not fail to ignite the explosive mixture of gas and air known to be present in the shaft.""The Compressed Air Magazine, January 1920 issue, which contained the above extract also goes on to state;""In 1915, M, Ferey described in a paper read before the Societe de l'Industrie Minerale phenomena of a similar character to the above. In a pit liable to sudden outbursts of gas, for the sake of safety, shot firing was carried out from the surface. During a storm, in the year 1905, shots went off in two places after the detonators had been connected to the conductors) we read in the Colliery Guardian, London. These shots were situated respectively 1,400 and 1,410 metres from the firing station, Realizing the possible danger from this cause, the precaution was taken to cut the conductors at the bottom of the shaft and to connect there just before firing, Even under these conditions a shot went off spontaneously, -.owing, it is believed, to lightning."""

Feb 1, 1920

By E. J. Babcock

The existence of vast deposits of lignite in the West Central and Western States is well known, although the extent and importance of the deposits have not been appreciated, nor has there been an adequate economic utilization of the deposits. The work of the Bureau of Mines, the United States Geological Survey, and the State geological surveys is disclosing an increasingly large area, underlaid with this kind of coal. Among the States having the largest workable deposits may be mentioned North Dakota, Montana, Wyoming, Colorado, and Texas, and in several other Western States lignite occurs in smaller areas. In North Dakota alone it is estimated that the deposits cover approximately 32,000 square miles, many of them being 10 to 15 feet thick and capable of producing in all several hundred billions of tons of lignite. When one stops to consider what these figures mean as to the immensity of these deposits in the West, it is not strange that people are seeking to ascertain better means for deriving larger benefits from the proper utilization of those great deposits. Consequently, any proposed methods of utilization that are promising are well worthy of careful consideration.

Jan 1, 1915

By W. Blake, J. Whyatt

Sixty years of rockbursting in the Coeur d’Alene district has taught painful lessons and led to a number of practical advances in controlling rockburst hazards. This paper summarizes those lessons, concentrating on practical measures that have been successfully adopted to reduce hazards. These lessons are explained in the context of district mining history and current understanding of rockburst phenomena. Overall, the paper provides the practicing mine engineer with an appreciation of rockburst hazards and an overview of practical measures that can be used to control these hazards in the context of Coeur d’Alene district experience.

By L. A. Johnson

This Bureau of Mines report presents the analysis of three cores from the Asphalt Wash area of the P.R. Spring tar sand deposit of northeastern Utah. Two tar sand zones are indicated in the Asphalt Wash Area. Total net thickness of the tar sand ranges from 23 to 39 ft, with occurrences between 56 and 263 ft in depth. The sand has average porosity of 24.7 pct of bulk volume, average permeability before and after extraction of 87.5 and 596 md, respectively, and average oil saturation of 58.1 pct of pore volume. Oil gravity averages 10.9° API.

Jan 1, 1975

By David Hoadley, Kenneth R. Maser, Ashok B. Boghani, James E. Billar, D. Randolph Berry, Mackenzie Burnett, Robert H. Trent

C 6 Automatic Elevator Control Systems An automatic elevator control system, consisting of position sensing devices and a control unit, can be used to control an emergency mine hoist. While automatic elevator control systems are assembled from standard components, they are typically custom designed to suit a given customer's application. Various manufacturers contacted indicated that the price range, less installation, for a simple two-stop control system begins at approximately $2500 and can increase depending upon the type of components used, shaft depth, the type of mechanical drive used, and the maximum operating speed A partial list of elevator control manufacturers follows. They should be contacted for further details. Marshall Elevator Company Pittsburgh, P A 412 -431 -1340 Armor Elevator Company, Inc. Louisville, KY 502-361 -7181

Jan 1, 1976

This report was prepared by Jacob Tolsma and Arnold N. Johnson of the Uniroya 1 Research Center, Wayne, New Jersey. The valuable assistance and suggestions of the project officers, Mr. Ronald D. Hill, Dr. David R. Maneval and Mr. John J. Buscavage is gratefully acknowledged. The authors are grateful to the following Uniroyal personnel: Mr. Daniel Shichman, manager of Engineering Research, and Dr. Emmanuel G. Kontos, manager of the Polymer Physics Research for their direction, encouragement and suggestions regarding the experimental work, and Mr. Mark Olson for the design of the hollow auger soil sampler. We also wish to gratefully acknowledge the efforts and contributions of ideas proposed by our consultants, Dr. Frank T. Caruccio, assistant professor of geology at State University College, New Paltz, New York, and Dr. Pa Ho Hsu, associate professor of soil chemistry, Rutgers University , New Brunswick, New Jersey.

Jan 1, 1972

By Andrew Cecala

During a recent National Institute for Occupational Safety and Health field evaluation of a newly designed filtration and pressurization system for an enclosed cab of a surface drill, it was determined that the drill operator's respirable-dust exposure was significantly increased during time periods when the cab door was opened to manually guide another section of drill steel into place to achieve additional cutting depth. Although no dust cloud was visible when the door was opened to perform this task, the drill operator's exposure was documented (over a three-day test period) to be nine times higher than when the cab door was closed. Even at this higher respirable-dust concentration, the drill operator's exposure remained well below the permissible exposure limit governed by the federal dust standard; however, an alternative method is being investigated to guide the drill steel in place in order to eliminate this increased exposure. .

Jan 1, 2008

By David Ingram

The results from the sound level measurements, the dosimeter recordings and the time-activity studies on four different air-rotary rigs indicate a wide variation of operator noise exposure during hole development. These variations appear to be dependent on the cab design and the operator?s drilling behavior. Studies have documented that exposure to high sound levels for long periods of time can cause hearing loss. The results of this study help identify the loudest parts of the drilling cycle. Sound level measurements on the four rigs show that all the rigs generate sound levels that are 90 A-weighted decibels (dB(A)) and above within 6 feet around the rigs during drilling. It is easy to conclude that some type of noise protection, such as a cab, is needed to protect the operator from overexposure to noise for an eight-hour shift of uninterrupted drilling. However, even when rigs are outfitted with cabs, operators observed in this study are being exposed to sound levels above 90 dB(A) during some activities required to complete a drilling cycle. An evaluation and comparison of the four dosimeter recordings and time-activity studies during one drilling cycle may explain why variations in operator exposure occur. Table 1 summarizes the time-weighted average (TWA) and accumulated dose percentages for each of the four operators during the time needed to complete one typical hole cycle.

Jan 1, 2008

To develop a business case that promotes adoption of noise controls by reducing barriers to industry acceptance and enhancing drivers that foster their implementation. Background Over 75% of the U.S. mining workforce is exposed to hazardous noise, putting them at risk of noise-induced hearing loss (NIHL). Consequently, coal miners suffer high rates of hearing impairment that increase to 70%-90% by retirement age. To address the noise problem for coal miners, researchers from the National Institute for Occupational Safety and Health (NIOSH) first determined that the continuous mining machine (CMM) ranked first among machines associated with reported coal noise overexposures. Further studies found that most CMM noise is generated by three component systems on the machine: dust collection, cutting, and conveying. Of these systems, the on-board chain conveyor was found to be a dominant noise source. Noise generated by the conveying system was addressed through the development of a urethane-coated flight bar chain. The coated chain, shown in Figure 1, has demonstrated an 8-hour time-weighted average (TWA) reduction of operator exposure by 3 dB(A). It has since been accepted by the Mine Safety and Health Administration (MSHA) as a "technologically achievable" noise control for CMM operators who are exposed to noise that exceeds the MSHA permissible exposure level. Having demonstrated the noise reduction performance of the coated chain, NIOSH has assembled information into a business case that can be used by operations considering adopting the chain at their worksite.

Dec 1, 2009

By Staff

The papers contained herein summarize results of various recent Bureau of Mines investigations in the area of mine power distribution systems. They are based on information from Bureau personnel, contractors and grantees, and Mining Enforcement and Safety Administration. Conclusions drawn from a series of parameter measurements on mine power systems, taken over a 3-year span, are presented. Personnel and equipment hazards due to faults on isolated, solidly grounded, and resistance grounded three-phase systems are discussed. Two papers cover dc applications of circuit breakers, including a novel protection scheme for trolley lines. The methods of suppressing induced arcing currents and voltages in a-c machines are evaluated. An evaluation program for ground monitors is described. Acceptance test procedures and the importance of various paparameters for trailing cable splice are covered. A number of techniques for locating faults in trailing cables are described.

Jan 1, 1975

Reduce the noise radiated by the auger miner cutting head (typically 105 dBA at the face) by 10 dBA without compromising the durability or productivity of the tool. Approach Research was conducted by the Bureau of Mines to identify the noise sources of auger miners with emphasis on the cutting head and coal cutting process. The overall noise level generated by the coal cutting process was found to depend greatly upon the structural characteristics of the auger cutting head. Based on this information, a quieter cutting head was

Jan 1, 1982