Search Documents

By H. H. Schrenk, F. E. Griffith

"The increase in tunneling operations that requires working under pressures greater than that of ordinary atmosphere has raised the question of the use and possible limitations of respiratory protective devices under such unusual conditions. As little, if any, information is available, there is need for a comprehensive study of this subject before specific recommendations can be made. In the absence of such data it seems desirable to make a few preliminary observations regarding the problems associated with wearing respiratory protective devices under increased air pressures.Two distinct problems must be considered--the mechanics of the apparatus used under such conditions and the physiological effects of increased pressures on wearers of respiratory apparatus. This report is confined to the use of oxygen breathing-apparatus and gas masks under pressure.ACKNOWLEDGMENTSThe data presented were obtained at the Queens Midtown Tunnel under construction at the east end of 42d Street, New York City, during a study of compressed-air illness conducted by the Bureau of Mines in cooperation with the United States Public Health. Service and the New York City Tunnel Authority.Grateful acknowledgment for cooperation and the use of facilities is made to Dr. R. R. Sayers and his associates, particularly Dr. J. W. Crosson (who acted as observer during the oxygen breathing apparatus tests), of the Division of Industrial Hyiene, National Institute of Health; to the Port of New York Authority, through Dr. Edward Levy; end to the contractors, through Doctor Emery."

Jan 1, 1940

By Fred D. Wright

A compressor and utility station, which is believed to be one of the largest mobile units of this type ever constructed, was placed in operation at the Bureau of Mines experimental oil-shale mine near Rifle, Colo., during. 1949. This mobile unit mounts two 770-cubic-feet-per-minute air compressors, a 2,500-gallon water tank, and a 200-cubic-foot air receiver. The mobile base of the unit is a 30-ton trailer 30-feet long and 12-feet wide. Prior to the construction of this unit, compressed air was supplied to underground workings through pipe lines connecting with a stationary compressor plant on the surface. The power consumed in supplying compressed air to underground drilling crews was 0.531 kw.-hr. per ton of shale broken. Use of the mobile unit has cut this figure to 0.421 kw.-hr. per ton of shale broken and, more important, has eliminated the cost of installing and maintaining underground air and water lines.

Jan 1, 1950

By Wing G. Agnew

It is thought that a brief description of the unique mining and milling procedure at the Doyle nine may be interesting to those engaged in small-scale operations at old mines or in working new ore body adjacent to old workings. It also shows what can be done with r. small capital outlay in working a zinc-lead mine on a small scale; as the operation herein described was begun 3 years ago with four men and it now employs 17 men. The original idea was to mine out any ore left around the edges of some old stones above the water level and to rob pillars after an old stope became filled with waste and tailings. This has been done, and the procedure is still being followed; at the same time a paying lead is being mined toward an area in which churn-drill holes have shown ore. Also, preparations are now being made to do some pumping.

Jan 1, 1936

By W. P. Yant

Canister-type gas masks have become an essential part of the equipment of many industries not only for use in emergencies, but also in performing normal operations of industrial processes and procedures, particularly where ventilation is not practically or economically feasible. They are also used widely for enhancing safety of operations which previous to the development of gas masks had been performed in harmful atmospheres. Since the inception of industrial gas masks the Bureau of Mines has been actively engaged in endeavoring to increase the efficiency and safety of these devices and this bureau has become a source of advice to manufacturers in producing devices of good quality and to industry in the proper selection and use of these devices. In order to give first-hand information and keep current with the demands and needs of industry it is necessary to perform investigations from time to time. This report deals with tests of certain types of commercial gas-mask canisters for protection against mercury vapor.

Jan 1, 1932

By Alan D. Hartman

The U.S. Bureau of Mines, under a Memorandum of Agreement with the American Society of Mechanical Engineers (ASME), established design criteria for a facility to melt residues from municipal waste combustion. This facility, which is available to potential users on a cost-sharing basis, is also applicable to a variety of inorganic waste materials from smelting or melting operations. The design consists of a mechanical feed handling system, electric arc melting furnace, fume-offgas handling system, and thermal oxidizer for final offgas treatment. Screw conveyors and a bucket elevator deliver up to 2,000 lb/h of minus I-in material to a three-phase electric arc melting furnace. This unique 800-kV?A furnace has a water-cooled shell and roof to minimize interaction of the melt with the refractory lining. The volume of the hearth below the slag taphole is approximately 1.2 st of steel. The furnace is sealed, allowing atmosphere control within the furnace and fume duct by nitrogen or inert gas injection. A jet-pulsed baghouse removes particulate from the offgas and serves as an acid gas scrubber. The clean offgas is heated to 1,800° F for 1 s in a propane-fired thermal oxidizer before being vented to the atmosphere.

Jan 1, 2010

By Alan G. Mayton

A prototype end-cab shuttle car (SC) design has been developed to improve protection and address ergonomic concerns of the SC operator in low coal mines. The new design features an end cab transversely mounted to the SC and equipped with a closed-circuit video system. The end cab was retrofitted to a low-coal SC and evaluated in surface trials at the U.S. Bureau of Mines. During surface trials, test operators evaluated the end-cab SC relative to visibility; cab features-space, seating, controls, and operator position; tramming-inby, outby, and turning corners; and dumping. Trials were conducted using 12 test subjects; 6 were experienced SC operators. Results of the trials were promising. Of the experienced operators, the only operator with low-coal experience gave the new design the highest rating. Four experienced operators rated the end-cab design "better" to "much better" than a standard center-driven, side-cab SC for visibility when tramming, protection from roof and rib hazards, and no change in seat position with direction of travel. This report discusses research to modify a used 21SC JOY SC, retrofit the SC with the Bureau-developed end-cab, and evaluate the retrofitted end-cab SC in surface trials.

Jan 1, 2010

By A. Visnapuu

The U.S. Bureau of Mines investigated the oxidation of American Iron and Steel Institute (AISI) Type 304 stainless steel (SS) during annealing in simulated combustion products from several air-CH4 fuel ratios. Atmospheres representing air-CH4 ratios of 14:1 and 18:1 contained free 02, while atmospheres representing 10:1 air-CH, ratio did not. A Cr203 layer formed on SS samples annealed in atmospheres containing free 0, while a Cr-Fe spinel layer formed in atmospheres with no free 02. The Cr203 layer was adherent and presented a protective barrier to metal diffusion, effectively limiting oxidation of the metal substrate. The Cr-Fe spinel was not protective and allowed the diffusion of Fe through the spinel to the gas-oxide interface where it was oxidized to magnetite, which spalled from the surface. This resulted in thick scale layers on samples annealed in atmospheres containing no free 02, as compared to layers formed on samples annealed in atmospheres containing free 02. These results confirmed and explained industrial operators' observations that thick, smoky (fine spalled magnetite) scales form on SS annealed in low free-02 atmospheres, while thin protective oxide layers form on sheets in atmospheres containing free 02.

Jan 1, 2010

By T. C. Atchison

This report describes a mobile laboratory designed and constructed by the Bureau of Mines in 1950 to meet the needs of an experimental blasting research program. The laboratory has facilities for making; film recordings of 16 simultaneous transient electrical signals over a broad range of amplitude, frequency, and duration. The signals are recorded with specially designed oscilloscopes and high-speed drum cameras. Each of the 16 channels records on a separate strip of 35-millimeter film by using interchangeable input units, transducers having different sensitivities and output impedances can be accommodated. The laboratory can be used to record both steady-state and transient phenomena originating as electrical voltages or capable of being converted to electrical voltages by appropriate transducers. Thus, the laboratory can, be used in studying various types of vibration problems or high-speed phenomena, such as ground and building vibrations, machinery vibrations, airborne vibrations, electrical-circuit switching phenomena, millisecond timing, and seismic phenomena occurring when rock is broken by explosives.

Jan 1, 1956

By Jr. Norman

Thermoelectric properties of depleted uranium selenides and tellurides were investigated from room temperature to 700 C. Several depleted uranium monoselenides and monotellurides were doped with selected cationic and anionic materials to determine the effect of impurity additions on the thermoelectric properties. The undoped uranium selenides and tellurides were semimetallic conductors exhibiting low Seebeck coefficients and electrical resistivities. Partial or complete degeneracy was in evidence, indicating a charge carrier energy distribution similar to that in a metal. Doping increased the Seebeck coefficients of the uranium monoselenides and monotellurides; however, the corresponding change in the power factor in the figure of merit was small because of the increase in electrical resistivity.

Jan 1, 1965

By Martin A. Elliott

"INTRODUCTION During the recent war the Bureau of Mines was requested to obtain in¬formation on the temperature at which ammonium nitrate mixed with certa: contaminants would react rapidly. This information was desired in connection with an investigation of an explosion that had occurred during the evaporation, by air agitation, of volutions containing ammonium nitrate in which compressor oil that might have passed the filters was suspected of being a contaminant.During the course of this work it was found that mixtures of ammonium nitrate and zinc reacted rapidly at comparatively low temperatures: and since zinc could not positively be eliminated as a contaminant in the explosion in question, a series of tests was carried out, not only with mixtures of ammonium nitrate and compressor oil but also ammonium nitrate and zinc with and without oil. A few experiments were made with metals other than zinc.The investigation was not as extensive as might have been desired, owing to limitations -in time. The results are presented at this time in view of their current interest in connection with the Texas City disaster, in which a large quantity of ammonium nitrate detonated in the holds of two ships."

Mar 1, 1948

By E. L. Rawlins

The Bureau of Mines, with the cooperation of the Natural Gas Association of America, has conducted a study of leakage losses from natural-gas transmission lines. This study has shorn that surveys to determine the leakage from transmission lines lead to line repair work that not only aids in the conservation of gas, but can be made to show financial returns of large magnitude.2 In order to conduct the study, it was necessary to develop accurate and reliable methods of determining the actual leakage from pipe lines. METHODS OF TESTING Three methods that were developed and used to determine the leakage losses from high-pressure natural-gas transmission lines are: (1) The "pressure-drop" method, (2) The "metering-in and metering-out" method. (3) The "metering-in" method.

Jan 1, 1926

By J. M. Kuchta

The Bureau of Mines used laminar hot air jets of l/8- to 3/4-inch diam-eter to determine the hot gas ignition temperatures of various combustible vapor-air mixtures. The combustibles were n-hexane, n-octane, n-decane, a hydrocarbon jet fuel (JP-6), and an adipate ester aircraft engine oil (MIL-L- 7808). Minimum ignition temperatures occurred at a fuel to air weight ratio of about 0.5 and were not greatly sensitive to variations of fuel concentra¬tion. Moderate variations of jet velocity also had little influence on these ignition temperatures. However, these temperatures decreased with increase in heat source dimensions (jet diameter). The hot gas ignition temperatures of the combustibles were not necessarily much greater than corresponding autoignition and wire ignition temperatures when the size (,F the heat source and the ignition criterion were the same.

Jan 1, 1966

By W. C. McBee

A family of modified-sulfur cements has been developed by the Bureau of Mines for the preparation of construction materials with improved properties. Various types of sulfur cements were prepared by reacting sulfur with mixtures of dicyclopentadiene (DCPD) and oligomers of cyclopentadiene (CPD). Durable cements were prepared with structural characteristics ranging from rigid to flexible. These cements were used to prepare corrosion-resistant materials for use in a wide variety of industrial applications where resistance to acidic and salt conditions is needed. These materials were prepared as rigid concretes, flexible pavings, spray coatings, and grouts. Production of modified-sulfur cements in a commercial-size plant was demonstrated.

Jan 1, 1981

By H. B. Brunot, L. C. IlsLey

The chief object of the Electrical Section of the United States Bureau of Mines is the study of causes and means of preventing accidents resulting from the use of electricity in mines . A large part of this work for the last 20 years has been the inspection and testing of mining equipment under the provisions of schedules which give the minimum requirements considered essential for the safety of equipment intended for use at or near the working faces of dusty or gassy mines . During the first few years of this work , particular attention was paid to the explosionproof features of the various accessories such as motors , controllers , and other parts . The knowledge of the essentials necessary for safe designs of enclosures has since been augmented by field experience and by data obtained in testing a large number and variety of designs . With our present knowledge it would seem that a disproportionate stress was placed on making the various enclosures explosionproof , but not enough thought was given to the danger from wiring and connections outside of explosionproof enclosures . The list of equipment that has met minimum requirements for safety and has been approved as permissible by the Bureau of Mines includes storage - battery locomotives , power trucks , drills , loading machines , conveyors , cutting machines , room hoists , pumps , concrete mixers , and rock-dusting machines . The wiring on some of the machines is comparatively simple and sometimes , except for the trailing cable , may be entirely within the explosionproof enclosures . In general , there is outside wiring between enclosures , and on the larger machines the wiring may be extensive and complicated . In considering the safety of wiring for mining machinery , attention must be given the severe service and unfavorable surroundings imposed by mining conditions . Some of the matters that require consideration are : ground . The lack of care of the exterior wiring to be expected in the average mine . The lack of adequate periodic inspection of the wiring . The absence of adequate facilities for satisfactory inspection and repairs under- The severe conditions of moisture , dirt , mechanical injury , and low voltage encountered in mining service .

Apr 1, 1931

By T. M. Barczak

This report describes Bureau of Mines research to develop methods to evaluate loading on longwall roof supports to permit better design and more efficient utilization of these structures in compliance with the geological conditions in which they are employed. The resultant vertical and horizontal force acting on the canopy of a shield can be determined, either from a statically determinate solution assuming rigid-body mechanics and elimination of certain unknowns, or from an elastic solu-tion by analysis of the load-displacement relationship of the shield structure. A two-dimensional rigid-body model is presented that determines resultant shield forces by measurement of leg, canopy capsule, and lemniscate link forces. An elastic solution is presented, in the form of an elastic stiffness model with two degrees of freedom, which describes the load-displacement relationship from the stiffness of the shield structure as determined in the Bureau's Mine Roof Simulator (MRS). The ability of both models to determine resultant forces acting on the shield canopy are evaluated from full-scale tests in the MRS. More advanced numerical models are also discussed as part of the Bureau's continuing effort in the evaluation of roof support structures.

Jan 1, 1987

By Alla D. Mah

The energies of combustion of zirconium carbide and hafnium carbide were measured by combustion calorimetry and the heats of combustion and formation. of zirconium carbide and hafnium carbide were derived . The results are-- ZrC AH298.15 ( combustion) = -308.60 ± 0.55 kcal /mole , AH298.15 ( formation) -47.0 ± 0.6 kcal /mole , AH298.15 = HfC (combustion ) = -306.08 ± 0.20 kcal/mole , AH298.15 ( formation) -52.3 ± 0.4 kcal /mole . = INTRODUCTION This report contains the results of calorimetric measurements to obtain the heats of formation of zirconium carbide ( ZrC) and hafnium carbide ( HfC) . The work was conducted as part of a Bureau of Mines program for determining the heats of formation of oxides , carbides , and nitrides by combustion calorimetry . Combustion calorimetry is one of the most precise calorimetric techniques . The chief obstacle to obtaining accurate heat of formation values for carbides , and the chief reason for the variation in the results of different investigators , is the lack of purity of the carbide samples . Corrections for impurities always involve assumptions which lead to uncertainties . In general , a large impurity correction is accompanied by a large uncertainty in the final result .

Jan 1, 1964

By John W. Taber

"INTRODUCTION AND SUMMARYDiscovery of these unusual fluorite deposits was brought to the attention of the Bureau of Mines late in 1951, shortly after the first locations were made. A brief investigation of the deposits by the Bureau revealed seven principal outcrops of fluorite in two areas. The smallest outcrop continuously exposes massive fluorite over an area 25 by 55 feet; the largest outcrop is a similar exposure 180 by 240 feet. The deposits, appear to be sharp-walled, low-angle, tabular ore bodies in granite and are at least 10 feet thick.The Bureau investigation of the deposits included bulldozer strip-trenching, drilling and blasting rock cuts, and channel sampling across three of the largest outcrops. This sampling indicated an average grade of 97.2 percent CaFp and 1.44 percent SiO2.Preliminary metallurgical tests on the ore indicate that it can be concentrated to acid-grade specifications by simple gravity methods. One laboratory test recovered 78.4 percent of the fluorite in a product containing 98.7 percent CaF2, 0.25 percent SiO2, and 0.10 percent Fe2O3."

Oct 1, 1952

By K. R. Becker

The addition of a force gage and a reaction detector to the Bureau of Mines drop-weight impact apparatus made it possible to examine the details of the force exerted on the specimen and make estimates of the time to reaction. With the current setup the force was found to be oscillatory and not reproducble. However, single well-defined pressure pulses can be delivered to the explosive sample by modifying the drop-weight tools. With a modified test arrangement, the time to reaction and the peak force and energy at the time of reaction were determined as a function of drop-weight height for several different explosives. All these parameters were found to decrease as the rate of force application was increased. The same parameters were also found to vary with the thickness of the test sample. The implications of these results are discussed in terms of practical drop-weight testing.

Jan 1, 1972

By Oliver Bowles

The exingencies of a world war have brought home to the American public, especially the people of the. Eastern States, the urgent need for conserving fuel. Transportation problems in the East have created an unprecedented situation wherein fuel-oil supplies are greatly restricted, and the consequent increase in demand for coal further complicates the problem of transporting and storing that commodity. People should awaken to the need for utilizing every possibly means of conserving to fuel, even to the extent of reducing the temperature in their homes.

Jan 1, 1942

By Paul W. Jeran

This Bureau of Mines report has been prepared to provide a means whereby mineworkers without specific geologic training can recognize and record the existence of potentially hazardous geologic features encountered in coal mines. Each geologic feature described in this report has been implicated in roof failure. Through the recording of the observations of mineworkers, based on this report, a geologic map of mine workings and the associated ground control problems can be compiled. From such maps, the trends of changes and features can be determined and projected ahead of mining. The face crew can be alerted to a potential problem and what to look for as the face is advanced.

Jan 1, 1983