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By E. D. Gardener, Byron O. Pichard

"Methane, frequently called fire damp or marsh gas, is very well known to coal miners but to thy average gold miner it means nothing, as it is not associated generally with the rock formations in which gold is found.We have recently been conducting a study of mine air in typical gold mines on the Pacific Coast, and out of five California mines in which the air was sampled, three showed methane. Each of these three mines, referred to below as mines A, B, and C, have had accumulations great enough to be ignited. An authentic report from another California, gold mine, which has not yet been sampled, states that recently the superintendent was seriously burned by the ignition of a pocket of gas. This mine is later mentioned as mine D.Mine A is an old mine which had been abandoned for several years and permitted to fill with water. It has been unwaterad recently, and is now being developed at greater depths. During the unwatering, gas bubbles formed on the water and upon being ignited burned freely. It is reported that two men were seriously burned from accidentally igniting the gas. Samples of the bubbles on analysis showed high percentages of methane. Since the mine has been unwatered, no trouble has been experienced through gas being ignited. However, out of a total of six air samples which we took recently in scattered working places, all showed small amounts of methane, the methane content being 0.06, 0.04, 0.05, 0.04, 0.04 and 0.07 per cent, respectively. When these samples were taken methane was not suspected, but its general presence in the mine air indicates that it is being given off constantly."

Dec 1, 1921

Design and test a high-production coal mining machine that generates less respirable dust. Background Current coal cutting systems generate excessive amounts of airborne respirable dust and fines during the mining process. Dust control technologies, including dust dilution by ventilation and suppression by water sprays, are not always able to reduce dust levels sufficiently. The U.S. Bureau of Mines (USBM) has designed a cutting system that reduces respirable dust generated by the cutting action of the drum. This cutting system, based on geometric principles developed in the 1500's, makes use of a constant depth, linear cut to remove coal at deeper cut depths and at lower rotary speeds than a conventional rotary drum. A comparison of the linear and rotary cut paths is shown in figure 1. Approach A full-scale prototype of the linear cutting concept was valuated under laboratory conditions to determine its performance relative to standard rotary drums. Results of these evaluations show production of fewer fines, or more uniform product size, a significant reduction in the amount of airborne dust, and reduced torque and power requirements (figure 2). On the basis of these results, a contract effort was undertaken by McCracken and Associates of Bristol, TN, to design a linear cutting head for underground testing.

Jan 1, 1995

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

Table

Jan 1, 1977

Aid mine workers in detecting hazardous roof conditions in underground mines by developing a method of roof sounding which supplements or replaces the traditional roof sounding technique where the miner relies on experience to determine whether or not the rock is sound. Approach The Bureau of Mines developed an electronic roof sounding de-vice that acoustically determines the integrity of mine roof rock by "listening" to the variation in frequency vibrations within the rock. How It Works n previous research, the Bureau of Mines found that loose rock in a mine, when impacted, vibrates at a much lower frequency and for a lower time period than does a solid slab. By quantifying the enhancement of low frequency vibrations in loose rock over solid rock, a repeatable, objective measure of the rock's soundness can be obtained. This approach was used in developing the rock stability tester.

Jan 1, 1986

By Thomas L. McVay

The Bureau of Mines made laboratory batch and small-scale continuous flotation tests of a sample of pegmatite rock from a deposit of the Lithium Corporation of America, Inc., near Kings Mountain, N.C., to determine the feasibility of producing commercial-grade spodumene concentrates. Various reagents and flotation procedures were tested to determine the optimum conditions for floating the spodumene and retarding the gangue minerals. The best results were obtained when sodium fluoride and lignin sulfonate were used as the pulp conditioner and oleic acid was used as the spodumene collector. The continuous flotation tests indicated that commercial-grade. spodumene concentrates analyzing 6.4 pct. Li2O could be produced with recovery of 77 pct. of the lithia in the ore.

Jan 1, 1962

By Lewis V. Wade

Barrett EA, Kowalski KM [1995]. Effective hazard recognition training using a latent-image, three-dimensional slide simulation exercise. Pittsburgh, PA: U.S. Department of the Interior, Bureau of Mines, RI 9527. NTIS stock number: PB95-170379. Beus MJ, Orr TJ [1995]. Computer modeling and analysis of the Greens Creek mine, Admiralty Island, AK. Spokane, WA: U.S. Department of the Interior, Bureau of Mines, RI 9530.NTIS stock number: PB95-176418. [ ]

By C. M. Mason

Mechanical mining produces large quantities of very fine coal dust called float dust. The associated increase in hazard requires a reexamination of the Bureau of Mines method of evaluating the incendivity of explosives in coal dust-gas-air mixtures. A technique recently developed by Bureau of Mines laboratories for evaluating the incendivity of explosives in coal dust-air mixtures was applied, with modifications, to coal dust-air-natural gas mixtures. A series of permissible explosives were evaluated by this modified technique. Results indicate that the modified technique could be the basis of a more discriminatory procedure than that presently in use.

Jan 1, 1968

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

5. General Escapeway Requirements 5.1 Escape Routes Present escapeway regulations state "Every mine shall have two separate properly maintained escapeways to the surface which are so positioned that damage to one shall not lessen the effectiveness of the other, or a method of refuge shall be provided when only one opening to the surface is possible." "Escape routes shall be a. Inspected at regular intervals and maintained in safe, travellable condition, b. Marked with conspicuous and easily read direction signs that clearly indicate the ways of escape." "Application. "Regular" intervals means at intervals no greater than monthly where conditions are stable and oftener where conditions may change." "Designated escapeways inclined more than 30* from the horizontal shall be equipped with stairways, ladders, cleated walkways, or emergency hoisting facilities." As can be noted in present and proposed regulations there must be two separate properly maintained escapeways. In most operations, the escapeways will consist of one route that is the normal travelway used in day to day operations. The second route is usually a return airway through old work areas. Based on this generally accepted practice, we will designate the two types as primary and secondary.

Jan 1, 1976

Develop a cost-effective, flexible method for extinguishing underground coal mine Fires that can be readily used in fire conditions encountered in both abandoned mines and coal outcrops. In addition to the abatement of an underground coal fire, a secondary objective was to prevent subsidence by filling the voids with a material having sufficient compressive strength to minimize subsidence. Approach The Colorado School of Mines Research Institute was awarded a research contract to determine the viability of using Foaming Mud Cement for abating underground coal mine fires and preventing subsidence. The program consisted of a laboratory and pilot scale investigation and process development. An extensive, controlled test program was conducted simulating floor, rib, roof and rubble fire conditions. Field demonstrations were conducted after the pilot scale research was completed. How It Works Traditional techniques have targeted the control of burning by eliminating the air, fuel source or heat. This has been accomplished by trenching, quenching, mothering or combinations of these three methods. These techniques were not always successful, particularly in the case of fires in abandoned mines.

Jan 1, 1991

By Ronald D. Hill, Elmore C. Grim

The goal of blasting is to get maximum fragmentation of the consolidated material in the overburden with optimum drilling and blasting cost. The amount of fragmentation required is determined by the stripping unit to be used In overburden removal. Many coal seams must also be broken by blasting; this is conducted before coal removal. There are environmental factors as well as due regard for public safety, health, and welfare that must be considered in choosing the blasting plan. The blasting plan should be made during preplanning and is based on data from the overburden cores. Analysis of the data will help In determining the kind of drilling equipment and bit types that will be needed for overburden preparation.

Jan 1, 1974

By R. V. Ramani, R. Stefanko, G. W. Luxbacher

1 11 THIS IS A DIGITAL COMPUTER SIMULATION OF THE VENTILATION SYSTEM OF A MINE LOCATED IN WASHINGTON COUNTY, PENNSYLVANIA. THE VENTILATION SURVEY ON WHICH THIS SIMULATION IS BASED WAS RUN FROM OCT. 27-30 AND ON NOV. 2, 1976 IN THE ACTIVE PORTION OF THE MINE INBY COMBS SHAFT AND THE INACTIVE PORTION AFCUND AND INBY DONAHOO SHAFT. FOLLOW-UP SURVEYS WERE THEN RUN ON FEB. 18 AND FROM MARCH 7-11, 1977 TO INCLUDE THE MAIN HAULAGE SYSTEM OUTBY THE ACTIVE AREAS OF THE MINE. ALL SURVEY DATA WAS NORMALIZED TO A STANDARD DENSITY OF 0.075 POUNDS/CU.FT. PRIOR TO THE CALCULATION OF INPUT PARAMETERS FOR THIS SIMULATION.

Jan 1, 1977

Reduce injury to people or damage to equipment when a scheduled production blast is detonated. Approach The essential elements of an effective blast area security system were identified through case studies of five mining operations where the blast area guarding practices were considered to be superior to those generally found in the industry. These elements were used in making recommendations for improved blast area safeguarding practices. Background The blast area security system is a means by which the mine operator prevents injury to people or damage to equipment when blasting is performed. Analysis of blasting accidents showed that most blasting accidents occur during scheduled blasting and are due to inadequate blast-site security. Factors contributing to the system's breakdown are failure to clear the blast zone, inadequate guarding. and failure of personnel to follow instructions, retreat to a safe location, and/or take adequate cover. Mine personnel, visitors and even trespassers can inadvertently wander into a blasting zone unless proper procedures exist to ensure that all personnel are cleared from the blast zone and kept safely away until after blasting IS completed. Statistics show that the blaster is the miner most frequently injured In these accidents.

Jan 1, 1986

By D. Harrington

Recently the attention of the U. S. Bureau of Mines has in a number of instances been called to the firing of shots of permissible explosives in coal mines with delay-action detonators. In one bituminous coal mine they were used to bring down the coal for conveyor loading; in another in blasting pillars, which were not undercut; in another in one of the two charges separated by stemming in deep drill holes where the coal was undercut and sheared and mechanically loaded; in another in shooting top coal; and in another in the shooting of coal faces electrically from the surface. Some of these mines were rated as gassy by the State Mining Department in the State concerned. In most instances the charging of holes was done while the working shift was in the mine, and in some the shots were blasted while the working shift was in the mine. In all of these cases the shots were dependent - that is, the efficacy of the succeeding shots was dependent - upon the firing of the preceding shot or shots. The first shot, or possibly two or three shots, was usually fired with a no-delay electric detonator or an instantaneous electric detonator.

Jan 1, 1929

By Earl C. Lane

This is the second of a series of reports on a survey of petroleum products manufactured on the Pacific Coast from California crude oils. California crudes differ in many characteristics from the petroleum produced in other parts of the United States, and the claim has been made that some of the present federal Specifications for petroleum products tend to discriminate against California products. The purposes of the present survey are to determine what particular specification requirements California petroleum products characteristically fail to meet, how widely the products deviate from these requirements, and if possible to show whether the fault lies with the specifications or the products, or along what 'lines investigation to determine the question should proceed. The first report* of the series gave the physical and chemical properties of gasoline and mineral spirits made from California crudes. The present report deals with lubricating oils. Sixty-one samples of lubricating stocks and finished commercial products were generously donated by four of the large refining companies of California. Fifteen samples of automobile lubricating oils, made in California from California crudes, were purchased in the open market. Nine samples of lubricating oils mode from Gulf Coast crude were contributed for comparison by a company in Texas. The refining companies have continued the helpful and cordial cooperation shown by them in connection with the earlier work of the survey.

Jan 1, 1923

Minimize failures or inefficiency in the operation of in situ mining wells. Approach The proper design, construction and development of wells are important to any in situ leaching operation. To permit cost-effective production from an underground ore body by leaching it in place, many wells are normally installed. Construction and maintenance costs increase with the number of wells, and poor construction and maintenance procedures result in production losses and negative environmental impacts, To minimize these losses and impacts, the Bureau of Mines conducted an investigation to determine the optimum in situ well construction and operating procedures for the minerals industry. Factors considered during the investigation included drilling equipment and procedures; types of well casing and grouting; completion methods, e.g, screening or perforation; and system maintenance. The data collected were used to prepare a manual that offers guidelines

Jan 1, 1984

By C. B. Manula, R. L. Sanford, R. A. Rivell

The need for a large capacity, high speed computer is more apparent in the revised model than in the original one. Core storage requirements for data and model logic have at least tripled. This dictates the use of one of the large modern machines such as the IBM 360-370 series or the Univac 1108 and 1110, which handle the model without the need for extensive program overlay. Computer time is expensive on these machines, however, and comprehensive analysis has gone into optimizing computer execution time consistent with model information flow sensitivity. For example, revised locomotive tramming routines have been developed which will significantly cut execution time compared to the previous version. Transceiver Applications The computer coding for the model has been developed to enable program execution and testing using a remote terminal on a time sharing system. In fact, nearly all of the coding, debugging, testing and modifications have been performed from a terminal during develop¬ment. The gaming options described in the Model Input Section of this report have been designed so that they are easily changed by the user from any remote site. One restriction on remote applications which could arise, however, is where highly detailed output options are specified, resulting in a large amount of output records which could be handled more efficiently on a high speed printer.

Jan 1, 1974

1. The Federal Mine Safety and Health Act of 1977 defines an independent contractor as "any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine." Contractors that perform specific types of work (e.g., shaft and slope sinking, material handling within mine property, drilling and blasting) are required to report the number of employees who perform work at coal mines and at metal and nonmetal mines.

May 1, 2003

By Launa Mallett, Charles Vaught, Michael J. Brnich, R. Lincoln Derick

After thoroughly covering the health and safety training subjects required under Title 30, Part 48, of the Code of Federal Regulations (CFR), mine operators often find themselves with little or no time left in the class schedule for other important topics. This paper discusses a technique developed in partnership with RAG Twenty mile Coal Co., Oak Creek, CO, for incorporating employee participation at all levels in fire prevention and safe equipment operation training outside of traditional classrooms. The process involves development of training modules consisting of short, 5- to 7-minute videotapes coupled with toolbox talks that ground the content of the videos within the context of a miner’s workplace.

Jan 1, 2002

By Ralph B. Adair

The Bureau of Mines conducted laboratory batch and small-scale continuous tests on samples of silt from the Nolichucky Reservoir near Greeneville, Tenn., to develop a process for the recovery of commercial-grade muscovite concentrates. Using a combination of Humphreys spirals for preconcentration followed by cationic flotation, 94.5 percent of the muscovite was recovered in a product containing 96.5 percent muscovite.

Jan 1, 1971

By Lloyd A. Morley, Alan M. Christman

General A review of the literature has revealed important areas which should be investigated during the field work. Of the utmost importance is the safety of mine personnel. Should a phase-to-ground fault occur on a shovel or other piece of equipment, current may return to the substation through the machine's contact surface with the mine floor, thereby raising the frame above ground potential and posing a shock hazard to anyone who touches the equipment. If the frame-to-earth resistance is very low, then no dangerous potentials will be developed, and a basis for elimination of the ground conductors from trailing cables could be postulated. However, should the contact resistance be high, then lethal voltages could be present on the machine frame. In this instance, low-resistance ground conductors in the trailing cable would be a necessity. Therefore, field tests should include measurements of the earth resistance of electrically operated portable or mobile mining equipment such as shovels, draglines, and drills. When the electrical distribution system is subject to lightning discharges, the grounding grid must safely carry to earth and dissipate enormous current surges. It is essential that the grounding grid have a low value of earth resistance, because any potential developed across the grounding grid as a result of current flow will appear on the frames of all machinery connected to the grid. Thus, an earth resistance

Jan 1, 1976