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By J. Douglas Causey

In 1987, at the request of the Bureau of Land Management, the U.S. Bureau of Mines studied 11,069-acres of the 12,290-acre Eldorado Wilderness Study Area (NV-050-423) in order to evaluate its identified mineral resources. The study area is located in Clark County, NV, adjacent to and northeast of the town of Nelson. There are inferred subeconomic resources on the Paul (gold, silver), Bel (gold, silver), Big Horn-Inez (silver, copper, lead, zinc) claims, and Montezuma (gold, silver, copper, lead, zinc) patented claim group in the Eldorado study area. Because of lack of exposures, tonnage and grade on these properties could not be determined. No resources were identified for the other five properties examined in the area. The southern two-thirds of the area is in the Eldorado mining district, a base- and precious-metal district which has been intensely explored for over 100 years. Nine claim groups were examined in the study area. Eight claim groups are within the Eldorado district and include the Montezuma (patented -M.S. 3966), Bel, Eldorado, VAR, SINJUN, Paul, Rusty Bit, and Big Horn-Inez. One property, the Flintstone claim group, is north of the Eldorado mining district at the north end of the study area.

Jan 1, 1988

By W. P. Diamond, A. C. Smith, J. A. Organiscak, T. P. Mucho

The U.S. Bureau of Mines conducted a worldwide literature review of bleederless ventilation practices to evaluate their use as a spontaneous combustion control measure in U.S. coal mines. Factors that must be taken into account in the design and use of these systems include seal construction, the use of ventilation control devices, the use of methane-drainage systems in gassy mines, and the ground control plan. Monitoring for the detection of spontaneous combustion and the control of methane when methane-drainage techniques are employed is critical to the successful use of a bleederless ventilation system. This report describes the types of ventilation systems used throughout the world and the spontaneous combustion risks associated with these systems. Methane-drainage systems used in conjunction with bleederless ventilation systems are discussed. Ground control considerations such as pillar design, entry stability, and seal usage are reviewed. Monitoring systems for spontaneous combustion detection, methane-drainage control, and behind seals are examined. Finally, methods for evaluating the spontaneous combustion hazard of a mining operation to determine when the use of a bleederless ventilation system is warranted are reviewed.

Jan 1, 1994

By Brian G. White

Two examples of en echelon mining-induced fractures seen in hard-rock mines provided a basis for inferring that fracture zones and bedding plane separations immediately surrounding mine openings are promoted by oblique shear into the openings. It is hypothesized that initial fractures or separations form at the corners of openings as a result of high stress and physical constraint on the rock's ability to deform elastically toward the opening. These conditions result in a locally preferred direction of shearing. The shearing, in turn, generates tensile stress that initiates a progression of systematically offset fractures approximately parallel to the direction of greatest compressive stress. The fractures or bedding separations create tabular rock layers that amplify shearing displacement through bending and dilation. Such shearing effectively reduces and redistributes the compressive stress, but significant dilation is an inevitable consequence. The combination of dilation and shearing and the progressive development of fracture zones have important implications with respect to ground support. The concept of mining-induced fractures forming as a result of shear is illustrated by two examples from coal mines. First, fractures seen at longwall faces probably result from shear associated with subsidence. The fracture zone that develops approximates or possibly defines the draw angle of subsidence. As the face advances, fractures extend downward along the lower edge of the fracture zone, while upper extensions of the fractures are pressed closed. Fracture zones in entry roofs provide a second practical example. Here, mining-induced fractures typically follow bedding planes. The shear zone model suggests that the first bedding separations develop near the edges of the roof and successive separations progress upward and toward the center. However, if the direction of greatest stress is inclined with respect to the roof, a fracture or bedding separation zone may propagate from one side only and also extend higher. Because coal ahead of the face provides some support against lateral shear deformation, bedding separation is inhibited near the face. Rock bolts installed close to the face ultimately become more strained and bent than bolts installed a few meters from the face, and bolts installed through the more remote part of a separation zone may ultimately experience the greatest tensile and bending strains. This model is supported by field data documenting progressive bolt failures that rapidly propagated downward across the roof during face advance.

By Michael J. Brnich

Since 1991, Pittsburgh Research Center (PRC- formerly part of the Bureau of Mines) researchers have recorded extensive interviews with 30individuals 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. This is the second of two articles which report experts responses to questions about training for future mine emergencies. During the interviews they discussed how training should be conducted, who should be trained, and what topics should be included. This article will cover the third area: Topics that should be included in training for mine emergency response managers.

Jan 1, 1997

By A. G. Smelley

As part of research conducted in its mission to effect pollution abatement, the Bureau of Mines, U. S. Department of the Interior, is developing a dewatering technique that allows for disposal of phosphatic clay wastes, for reuse of water now lost with clays, and for reclamation of mined land. The technique utilizes a high-molecular-weightnonionic polyethylene oxide polymer (PEO) that has the ability to flocculate and dewater phosphatic clay wastes. A synergistic flocculation study was made to determine whether a portion of PEO could be replaced by other reagents. Several groups of reagents were tested: (1) those that increased the zeta potential of the phosphatic clay wastes; (2) those capable of hydrogen bonding; and (3) those which flocculated the phosphatic clay waste. Reduction in PEO consumption occurred only with addition of those reagents able to flocculate the slime. The use of natural guar gums resulted in a lower PEO requirement and also yielded a dewatered product of higher solids content, 43 to 45 percent, versus 33 to 35 percent obtained with PEO alone.

Jan 1, 1980

By W. W. Adams

Lower accident rates were the outstanding feature. of the second annual sand and gravel safety competition conducted in 1930 by the United States Bureau of Mines in cooperation with the National Sand and' Gravel Association. Both the frequency and, severity rates for accidents were greatly reduced as compared with those shown by the first year's contest, that for 1929. Three times as many plants were enrolled, and the number of man-hours of work represented was more than doubled. Seventy-six sand-and-gravel plants, situated in 20 States, participated in the Competition, as compared with 26 plants, located in 13 States, in the year before. The number of man-hours of employment, which indicated the amount of exposure to occupational hazards, was 4,915,592, an increase of more than 100 per cent over the previous year's total of 2,259,572 hours. The frequency of accidents declined from 74.4 per million hours for all plants enrolled in the first year's contest to 42.7 per million man-hours for all plants enrolled in 1930. The accident-severity rate was reduced from 9.7 days of disability per thousand man-hours of exposure in 1929 to 5.9 days of disability per thousand man-hours of exposure in 1930. The actual number of accidents reported for 1930 by 76 plants included four deaths and 206 injuries whereas the 26 plants that were enrolled in 1929 reported three fatalities and 165 injuries. Under the rules of the contest all "lost-time" injuries are reported--that is, all injuries that disable an employee for more than the remainder of the day on which the accident occurred. If the employee is physically able to resume his work on the day following the accident, the injury is not classed as a lost-time injury. The contest covered accidents and man-hours worked by all employees at the plant who were employed by the same company, and included work up to the point of delivery of the material directly to consumer or to independent agency of transportation--in other words, to point of relinquishment of control of the material by the producer.

Jan 1, 1931

By N. Kyriazi, W. Duerr, J. Shubilla, J. G. Kovac, J. Kravitz

A joint effort by the Bureau of Mines and the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, was undertaken to determine how well self-contained self-rescuers, deployed in accordance with Federal Regulations (30 CFK 75.1714), held up in the underground environment. This report presents findings regarding laboratory-tested breathing apparatus from the first year of a 5-yr program as well as other related findings. The SCSR's were tested on human subjects and on a breathing and metabolic simulator. These results indicate that the apparatus, if well-treated, perform as expected except for manufacturing defects or quality control problems, which are identified. However, when the apparatus are carried in and out of the mine every day and stored at the working section, they may suffer abuse that can be extreme. Physical signs of abuse, unless extremely obvious, frequently are not detected by the miners or the mine operators; this poses a danger to a potential user in case of emergency. Recommendations include improved training in inspection procedures.

Jan 1, 1986

By Glenn C. Reed

The Sheep Creek iron deposits, Meagher County, Mont., were investigated by the Bureau of Mines in 1943 and 1944. Work undertaken included exploratory trenching, churn drilling, petrographic studies, and detailed beneficiation tests. It was determined that the Sheep Creek ores occur both as fissure filling and bedding replacements in thin-bedded shale and arenaceous limestones of the Algonkian Belt series. At least five stratigraphic horizons were found to be mineralized. Metallurgical studies indicate that the ores are not amenable to beneficiation by present-day low-cost methods. Details of geology, sampling, and beneficiation tests are presented in this report.

Jan 1, 1949

By R. H. Sprute

This report describes a feasibility study to consolidate coal waste sludge in a 100-acre pond by applying direct current between floating and buried electrodes. The study was conducted by the Bureau of Mines under a cooperative agreement with Washington Irrigation and Development Co., located near Centralia, Wash. Part 1 covers results of laboratory tests at the Bureau's Spokane Research Center and a small-scale field test at the cooperator's coal preparation plant in western Washington. The process is efficient and cost-effective when power is applied at low current density. A proposed system, fully described in part 2, has electrodes covering 21 acres of pond surface radially arranged around a central power platform. Densification of pond contents would require 2 to 3 years of treatment. Total cost of equipment, labor, and material is approximately $500,000.

Jan 1, 1982

By Robert K. Koch

Laboratory-scale studies on defluorination of natural and synthetic fluorspars by pyrohydrolysis at 1,500° C. were made to determine the feasibility of developing a process for producing hydrogen fluoride from siliceous fluorspars. It was found that the reaction (at 1,500° C.) is not promising for process development, even though a silica-free offgas can be generated. The primary difficulty is the low hydrogen fluoride content of the offgases; an HF content of 6 percent was the best achieved. Previous research by the Bureau of Mines has demonstrated that offgases averaging 27 percent hydrogen fluoride can be produced under carefully controlled conditions at 1,280° C. The lower temperature process is a better method for production of HF. However, charges in which the CaF to Si02 mole ratio varied from 0.4 to 2 could be processed with similar results. Also, combined alumina and ferric oxide contents up to 25 mole-percent did not noticeably alter the rate of defluorination. Therefore, virtually any natural siliceous fluorspar would respond in essentially the same manner when exposed to water vapor at 1,500° C.

Jan 1, 1962

By Jr. Smith

To investigate the effects of flow geometry on laminar flames, studies are in progress in this laboratory employing Bunsen-type burners with rectangular cross section. Interpretation of these studies requires a determination of the flow velocity at all points of the rectangular cross section for one dimensional steady laminar flow. In addition, values of the velocity gradient at the boundary for such flows are needed in the interpretation of blow-off and flash-back studies with burners of rectangular cross section. The hydrodynamical problem of steady laminar flow of a viscous fluid in channels of rectangular cross section was solved by Stokes. His results have been quoted by Love21 and by Dryden, Murnaghan, and Bateman,§/ and they have been discussed by Boussines and by Paschoud. It may be noted that the steady laminar flow of a viscous fluid in channels of rectangular cross section constitutes a hydrodynamical analogue for the problem of the torsion of an isotropic prism of rectangular cross section.

Jan 1, 1952

By J. H. Jansky, P. W. Jeran, G. L. Hassett, M. C. Irani

This Bureau of Mines report tabulates methane emissions from U.S. bituminous coal mines with daily emission rates of at least 100,000 cfd according to States, counties, and coalbeds. Most of the methane emitted is from mines in the Appalachian States. Total daily emissionin 1975 was 216.3 MMcfd, compared with 227.0 MMcfd in 1971 and 214.5 MMcfd in 1973. Thirty counties in nine States had daily methane emissions of 1 MMcfd or more, These emitted 93 percent of the total methane. The highest emissions were from Monongalia County, W. Va,, which accounted for 18.9 percent of the total. This was followed by Marion County, W. Va., 9.6 percent; Buchanan County, Va., 8.5 percent; Jefferson County, Ala., 6.1 percent; and Washington County, Pa., 5.9 percent. The Pittsburgh coalbed emitted 45.7 percent of the total methane, followed by the Pocahontas No. 3 coalbed with 12.9 percent. The report lists 196 mines, of which 60 had daily methane emissions of 1 MMcfd or more. Included in this compilation are the identification and thickness of the coalbed, methane emission, coal production and ventilation rates, number of drifts, shafts, and slopes used for ventilation purposes, shaft depth, age of mine, and gas-to-coal ratio.

Jan 1, 1975

By D. J. Parker, D. Harrington, L. H. Harrison

The necessity for protection against the hazards of lightning manifests itself from time to time in the mining industry by reason of loss of life, damage to electrical equipment, fires in surface structures at mines, and accidents in the handling and use of explosives. This paper is intended to assemble, correlate, and present some of the salient. points embodied in the available literature on the subject and at the same time give some factual data concerning instances of such loss of, life and damage to property, with special application to the mining industry The annual loss of life and destruction of property by lightning is considerable; the former may be prevented to a limited extent, though use of common sense as to exposure is required and not always followed; the latter can be prevented to a considerable degree. The manufacturers of electrical equipment,, through improved types of lightning arresters,, have done much toward the protection of electrical equipment, with consequent safeguarding of life and of property. Education based on unfortunate experiences has gone far to discourage the handling of explosives and blasting accessories during thunder storms, especially in open pits and quarries, and to a much smaller extent in underground workings. The lowly lightning rod plays an important role in the protection of certain types of buildings (especially isolated buildings), stacks, monuments, and other structures. LIGHTNING PHENOMENA In 1751, Franklin proved that lightning was simply a visible display of electricity - an extended spark; and until a generation ago little had been added to his exposition, to define the various phases of the phenomenon. Matters pertaining to lightning are discussed in the following references:

By Lowell Stroud

A windowed-cell phase equilibrium apparatus was used to obtain equilibrium vapor- liquid data for a helium-bearing natural gas (Hogback) at temperatures from -100 to -250° F and pressures to 500 psia. Anomalous phase behavior resulting in the formation of two stable liquid phases occurred at tmperatures below -200° F and pressures above 200 psia. A review of the published literature on the occurrence of multiple-liquid phases included in the report indicates that the experimental results with Hogback gas are the first substantiated evidence of a vapor-liquid-liquid equilibria in a helium-containing natural gas.

Jan 1, 1963

Coal miners, especially roof bolter and continuous miner operators, work in a hazardous underground environment where they are often exposed to poor roof conditions. Nearly 500 rock fall injuries are reported each year, and 99% of them are caused by rocks falling from between the roof bolts. These loose rocks that injure miners are usually just a few inches thick, but on average weigh 280 pounds. NIOSH has found that most rock fall injuries can be prevented by installing roof screen during the bolting cycle. Roof screen is a sheet made of steel wires in a grid pattern. When screen is bolted up against the mine roof, it provides far more coverage than any common surface control used in the mines today. Because more mine roof is covered, there is less chance that a rock will fall and injure a miner. The facts about roof screen are shown in the new NIOSH video entitled “Make It Safer With Roof Screen.” Using extensive underground footage, the 7-minute video shows how well screen keeps loose rock from falling in difficult roof conditions. Techniques for installing screen from both outside-controlled and walk-thru roof bolting machines are shown. The video also provides safe handling tips, best practices, and information about machine technology that can greatly improve material handling. Throughout the video, a coal mine safety manager and a shift foreman talk about the tremendous difference that roof screen has made at their mines. An instructional booklet supplements the video with additional information. It presents compelling data from mines that have practically eliminated rock fall injuries with a roof screening program. Other sections of the booklet discuss in greater detail roof screen installation, tips for manual screen handling, a material handling system for roof screen, and use of the personal bolter screen, which can be easily handled by one person. Screen specification and custom ordering are described, including the sizes of screen, grid sizes, reinforcing (indicator) wires, edge cut options, and screen strength. A list of additional sources of information is also provided. Nearly every mine eventually encounters poor roof. Screen is one of the most powerful control techniques available. This new video will help make mine managers aware of screen, and it can help them in developing a roof screen installation program. It also serves as an information source and teaching tool for safety managers and trainers. The video can easily be integrated into new miner training programs or annual refresher training.

Mar 1, 2005

By C. W. Smith

The Bureau of Mines conducted laboratory-scale beneficiation tests on a sample of corundum gneiss from Montana to devise a method for beneficiating corundum for use as a substitute for refractory-grade bauxite. A flotation process utilizing petroleum sulfonate as the collector in an acid circuit was devised. Results showed that two flotation schemes each produced a concentrate exceeding the national stockpile specifications for calcined bauxite. From a feed containing 28 pct corundum concentrates containing up to 92.5 pct alumina (A1203) were produced with a corundum recovery of 78.5 pct.

Jan 1, 1987

By G. L. Neumann

The Andover-Sulphur Hill iron mines in Sussex County, N. J., have a production record extending over 100 years. The last production recorded was about 1880. These mines produced high-grade ore of two types: Bed ore (hematite) and blue ore (magnetite. Some sulfides (lead, zinc, and copper) were found underlying the iron deposits. Data as to size and grade of these sulfide bodies are very sketchy, Toward. J. Hewitt of Elizabeth, N. J., lessee of the Sulphur Hill mines from 194045, prospected for lead, zinc, and copper. .His Only production was several hundred tons of low-grade iron ore, which was crushed and used as heavy aggregate to make concrete blocks for ship ballast. In October and November 1942 made a magnetic survey of this area and bored six-diamond-drill holes with the dual objective of prospecting for sulfides and testing for extensions of the iron-ore deposits indicated by the magnetic survey. In 1944, an iron-mining company examined this property and diamond-drilled seven holes Between December 1949 and March 1950, the Bureau Of Mines in search of sulfide deposits, bored three additional diamond-drill holes. Two of these were on the Sulphur Hill tract and one on the adjoining Tar Hill tract.

Jan 1, 1952

By J. D. Davis

From the chemist's point of view it would be ideal if specifications for coke for any stated purpose could be written on the basis of chemical composition and burning characteristics. Unfortunately this is not possible. In fact, the physical properties of a coke are often of such major importance as to render any specified chemical requirements totally inadequate to show the quality of coke desired. For example, a furnace coke may admirably fill all chemical requirements, such as for low phosphorus, sulphur, moisture, and high fixed carbon, and still be too soft to support the burden of the furnace without excessive crushing. Again, a domestic coke though a good fuel as judged from Chemical analysis, may be of unmarketable size. Thus one can not define the quality of a coke for a specified purpose without taking into account both its chemical and physical characteristics even when this has been done the specification may fail because neither coke user nor producer can accurately define by quantitative tests the qualities most desired. In other words, there is need of accurate test methods for measuring the properties of coke and, what is equally important, for correlating the results with the behavior of the coke in use. Coke quality is determined by the kind of coal used, the coking process, and the type of equipment used in the coking process. Chemical analysis of the coals, together with small-scale coking tests, will give a good indication of their suitability; but, in general, coke must be produced on an industrial scale and tested in the equipment for which it is intended before conclusive information as to its quality is obtained.

Jan 1, 1928

By Donald P. Blasko

The Bureau of Mines investigated two areas of oil and gas seeps in the north-central Gulf of Alaska--Katalla River to Bering River and Cape Yakataga to Yakutat Bay to determine (1) whether previously reported seeps are still active, (2) the characteristics of the seeping hydrocarbons, and (3) the amount of bitumen contained in the drainage leaving the seeps and entering the Gulf of Alaska. Thirteen separate oil seeps, six bitumen deposits, and eight gas seeps were located, sampled, and analyzed. The oils ranged from 35.2° to 14.1° API gravity and had sulfur contents from 0.53 to 1.31 wt-pct. Bitumen samples had API gravities from 2.4° to 14.6° and sulfur contents from 0.28 to 0.88 wt-pct. Gas samples had specific gravities ranging from 0.577 to 0.883 and caloric values from 724 to 1,427 Btu/cu ft. A total of 63 water samples obtained from seep locations and seep drainages were analyzed by atomic absorption spectrophotometry for ionic content and by solvent extraction for hydrocarbon content. Although some of the water at the oil seeps had a bitumen content as high as 246,000 mg/1, the amount of hydrocarbons actually reaching the Gulf of Alaska averaged <0.2 mg/1.

Jan 1, 1976

Provide the technology to remotely reset circuit breakers on continuous mining machines used in extended cuts.

Jan 1, 1994