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By W. F. Hughes

The thermodynamics of an electromagnetic field-fluid interaction system is discussed. A review of the thermodynamics of linear media (the permittivity and permeability taken as functions of density and temperature) is presented; then an extension is made to nonlinear media (the permittivity and permeability taken as functions of the fields). Expressions for thermodynamic properties and reversible work are derived and the first law of thermodynamics for magnetohydrodynamic flow is discussed.

Jan 1, 1968

By Fred N. Kissell

Methane-flow and pressure data taken from a mine in the Pocahontas No. 3 coalbed are compared with flow rates from lump coal obtained in laboratory experiments. From this, it is concluded that the main source of gas is the intact coalbed rather than a "crushed zone" near the working face. The permeability and sorption capacity of the intact coalbed are calculated and gas emission rates are theoretically accounted for.

Jan 1, 1972

By Connie S. Musulin

Radon concentrations in shallow uranium mines such as the Bureau of Mines experimental research mine are affected by barometric pressure changes. The radon concentrations show a significant correlation with absolute pressure; but over a period of days, a steady rise or fall in barometric pressure will result in noncorrelation of data. Fan shutdowns also affect radon concentrations, and an equation was derived to determine the time required for the radon concentration to return to normal after a fan shutdown, whether the ventilation is blowing or exhausting.

Jan 1, 1982

By Herbert H. Fields

The Bureau of Mines has been promoting health and safety in mining since its establishment in 1910. One area of research covers methane control in coalbeds; this report describes a multipurpose borehole used for both degasification and the production of commercial-quality gas. The multipurpose borehole was drilled into a barrier pillar, and seven horizontal degasification holes and one pressure point hole were drilled radially out from its perimeter. On January 28, 1974, after 505 days of degasification, a compressor was installed to the exhaust stack of the multipurpose borehole (1), and pipeline--quality gas was introduced into a commercial pipe-line. As of February 4, 1975, over 171 million cubic feet of gas had been purchased by the gas company. The in situ pressure at a depth of 200 feet into the coalbed and the average gas flow and water flow from the degasification holes as they were completed and closed off were 203 psig, 1,200,000 cfd, and 6.8 gpm, respectively. Twenty-four hours after the seven holes were connected through individual pipes to the atmosphere, the total gas and water flows and the in situ pressure dropped, respectively, to 971,000 cfd, 1.3 gpm, and 18 psig. Five hundred days later, the corresponding values were 620,000 cfd, 0.15 gpm, and 10.5 psig. Daily flows have been as high as 800,000 cfd, and as low as 360,000 cfd, during the last 500 days. On February 4, 1975, after 882 days of degasification, 576 million cubic feet of gas had been removed from the Pittsburgh coalbed; apparently a much larger area of virgin coal is being degasified than is defined by the holes. This study indicates that horizontal boreholes drilled into a coalbed from the bottom of any shaft will effectively remove gas from the Pittsburgh coalbed,

Jan 1, 1975

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

Provide the mining industry with an easy-to-use means of accurately predicting surface subsidence caused by longwall mining in the northern Appalachian Coal Basin. Approach The Bureau of Mines developed a subsidence prediction model using the novel approach of a variable subsidence coefficient. This approach had to be used because of the resistant strata types which commonly occur within the relatively thin overburden material typical in northern Appalachia. Such resistant strata precluded the use of the popular European methods that assume homogeneous overburden or overburden behaving as homogeneous from a subsidence point of view. The model is available in a BASIC computer program for use on most personal computers. The user has the options of obtaining individual subsidence calculations or may choose to develop a subsidence profile using an average overburden value. The program output can be generated in graphic or tabular form showing the location of the surface point with respect to the longwall panel edge, overburden depth, and the subsidence value.

Jan 1, 1986

By L. C. IlsLey

The Burrell methane indicator developed by Col. G. A. Burrell in 1915 was modified during 1918 to the " insulated type " Burrell indicator . Though this instrument has been used in mines since its first introduction , it was not formally approved as safe and efficient for use in gaseous mines until March , 1922. The indicator is built by the Mine Safety Appliances Co. , Pittsburgh , Pa . Approval No. 800 has been assigned to this company covering the device in the form approved . The principle of the Burrell indicator is fairly well known . It works on the same principle as the Haldane apparatus - measuring by means of a graduated scale , the contraction resulting from burning the methane content of an air and gas sample . A given aniount of the mine atmosphere to be tested for methane is taken into the indicator . This sample is then thoroughly shaken with the water in the indicator for one minute . The methane in the sample is now burned for two minutes by a heated platinum coil , which is energized by a small storage battery containing two Edison cells connected in series . After the glower or coil has burned for two minutes , it is disconnected from the battery , and the indicator is again shaken for The amount of contraction observed by reading the height the water rises in the U- tube of the indicator , which is calibrated to register the percentage of gas in the sample . The indicator as approved by the Bureau of Mines is equipped with an Edison M- 8 mine- lamp battery , and with a glass and scale graduated from zerɔ tɔ four per cent methane . The approval of a corbination service that is , an attachment for giving illumination from the same battery from which the platinum glower is operated has been withheld pending the development of a battery with larger capacity . - Under laboratory operating conditions , a single glower was capable of making at least 20 determinations if proper precautions were observed with respect to the use of freshly charged batteries . A battery should be allowed to stand off charge several hours before using in an indicator , as the peak voltage of a freshly charged Edison cell is abnormally high and is likely to send enough current through the glower to melt the platinum wire . Fifty-seven satisfactory operations were obtained from a completely charged battery . The point where the voltage of the cell fell below 2.3 volts with the glower attached was taken as the lower limit of successful operation . A voltage less than 2.3 does not permit the lower to burn at a temperature that will completely burn the gas in the air , thus giving a false indication .

Jun 1, 1922

By J. D. Corrick

Research was conducted to develop operating techniques and define some of the limiting parameters for microbially converting hydrous calcium sulfate to hydrogen sulfide. The work was carried out in either glass stoppered flasks or anaerobic fermentors. Using the criteria of pH, temperature, number of bacteria per milliliter of test solution, and hydrogen sulfide produced, it was shown that hydrous calcium sulfate could be microbially converted to hydrogen sulfide at a rate of 7.3 g H2S/1 of fermentor volume per 24 hours. The various parameters defined were pH, temperature, and medium exchange rate. These were shown to be a pH range of 7.2 to 8.8, a temperature range of 30° to 35° C, and a medium exchange rate of 70 percent of the ferment or volume per 24 hours. It was also shown that a daily waste was between 50 and 77 percent as effective as sodium lactate in supporting the production of hydrogen sulfide and that by utilizing a gas to purge the fermentation system, a 1.7-fold increase in hydrogen sulfide was obtained.

Jan 1, 1970

By George S. Koch

In preparing diamond-drill core samples for assay at the Homestake mine, Lead, S. Dak., 5-foot intervals of core are processed through three stages, crushing, grinding, and pulverizing, and portions of the core material are discarded after splitting at each stage of preparation. Then two 1-assay-ton fractions are taken from the pulverized material and assayed. This report investigates alternative methods of sample preparation. The consequences of crushing, grinding, and pulverizing all rather than part of the core are appraised through the statistical analysis of assay results from 118 5-foot intervals of core. Evidently, a substantial improvement in precision at small additional expense is obtained by grinding most or all of the core before splitting. Pulverizing all of the core would be desirable only if doing-so would cost less than assaying five random splits from each interval. Graphs and tables detail appropriate procedures to obtain specified precisions. The experimental design and methods can be applied to similar problems in preparing core and other geological samples.

Jan 1, 1972

By A. W. Henderson

Methods for converting WOCl4 to WCle were investigated in small-scale, laboratory apparatus to devise a method for preparing pure WCls suitable for conversion to tungsten metal. Chlorine, COCI2, and CCI4, alone and in combination with various forms of carbon, were tested as chlorinating agents at various temperatures. More than 95 percent conversion of WOCl4 to WCls was achieved with all reagents at 8000 C in the presence of activated carbon. Only CCl4 maintained its effectiveness in the absence of carbon at 800° C. The effectiveness of carbon was found to be related directly to its surface area.

Jan 1, 1968

By J. Litsenberger, T. E. Marshall, P. R. Coyle, L. J. Prosser, A. T. Iannacchione

For the first time in an underground stone mine, the relationship between roof movement and microseismic emissions was examined in conjunction with two distinct roof fall areas. As roof monitoring increases in acceptance and monitoring technology advances, the goal of providing reliable roof fall detection systems to enhance the safety of underground mine workers moves closer to reality. Instrumental to reaching that goal is the ability to interpret accurately and completely roof movement and microseismic emissions, which can serve as precursors to roof falls. This paper examines the capabilities of convergence and microseismic monitoring systems to better understand roof rock failure mechanics and to anticipate roof falls. An understanding of how these techniques are used and how they interact with each other is critical in developing the most effective ground control strategy for our nation’s mines.

By E. K. Kleespies

The Bureau of Mines determined the kinetics of the reaction of titanium-iron alloys with titanium trichloride dissolved in sodium chloride to provide a basis for understanding the reactions occurring in metallurgical processes involving reduction of the metal halides or alloy refining in fused salts. The rate of the heterogeneous reaction was determined between titanium-iron alloys and titanium trichloride to elucidate the effects of alloy composition on the rate. Measurements were made in an inert atmosphere with a high-temperature thermobalance using high-purity reactants. The rates of the reactions were about 1 x 10-5 g Ti/cm2-sec, and the reaction was phase-boundary controlled. Titanium alloys of the body-centered cubic beta structure reacted faster than those with the hexagonal close-packed alpha structure. The inter-metallic compound, TiFe, reacted very slowly, whereas TiFe2 was inert. Alloys containing above 89 atomic percent iron gained weight by reacting with titanium species in the salt solution and depositing titanium in the alloy. The effect of TiCl3 concentration on the reaction rate was determined from 2 to 12 weight-percent TiC13 and at various alloy compositions. At high iron contents, above 50 atomic percent, the TiC13 concentration effect was small. At lower iron contents, the TiC13 concentration effect was greater for beta-crystalline alloys than for alpha-crystalline alloys. The temperature dependence of the reaction between titanium alloy containing 8.7 atomic percent iron and titanium trichloride was measured over the temperature range 1,062° to 1,220° K, and the energy of activation was 7.7 kilocalories for the reaction.

Jan 1, 1967

By J. J. Bourquin, S. H. Katz

"Three types of respiratory apparatus namely, gas masks, hose masks, and self-contained oxygen-breathing apparatus - are now commonly used for protection from noxious gases, vapors, and smokes or ristes, but no particular type can be selected as best for all conditions. Many factors must be considered in connection with each situation, so that each must be considered as a problem in itself. Following are concise statements for comparing the types:Gas masks are the simplest and easiest to wear, also the least cumber-sore; but they protect only in comparatively low concentrations of noxious gases and should never be used where the air contains less than 16 per cent of oxygen. Special masks give protection from one gas or class of gases, but may give no protection against another gas or class of gases.Hose masks protect in any irrespirable atmosphere, but are somewhat cumbersome, the length of hose limiting the distance a wearer may go from fresh air. They are serviceable also where a supply of pure air moves with the wearer, as where a locomotive engineer in a smoky tunnel is using a hose mask supplied with air from the compressed air line of the locomotive. Hose masks consume no chemicals or materials and so are not limited in the time they may be used.Self-contained oxygen-breathing apparatus protect in any irrespirable atmosphere, but their weight is cumbersome, they can be used only by trained men, and frequent attention must be given them to maintain good working condition. On the other band they are the only safe means for exploring mines and other places filled with irrespirable gases in high concentrations."

Jun 1, 1923

By Richard A. Thomas, Charles D. Litton, Kenneth E. Mura, Harry C. Verakis

Experiments were undertaken to evaluate the flammability of typical noise abatement materials used to line the cab interior of mobile mining equipment. The experiments were conducted using three different experimental configurations: 1. A ventilated tunnel test. 2. A full-size cab test where the interior surfaces were lined with the sample material and then ignited near the floor using a methane-air burner. 3. Standard ASTM E-162 tests using a radiant panel test apparatus. This paper describes the tests and presents the results obtained for 15 to 20 different materials of various chemical compositions and thickness. With one exception, materials that did not exhibit flame spread in the tunnel test also performed well in the full-scale cab test. All materials that had passed only a small-scale flammability test, such as SAE J369, failed dramatically in all three of the above test configurations. With one exception, all materials that performed well in the full-scale cab test had flame spread indices < 25, based upon the ASTM E-162 results. The lone exception had an ASTM E-162 flame spread index of 68. With regard to samples that failed the full-scale cab test, the carbon monoxide levels within the cab reached lethal concentrations in the range of 1.8% to 3.8% within 2 minutes from ignition of the sample—dramatically illustrating the severe fire environment that can result within the cab space.

By Lawrence L. Davis

This chapter includes tables for 1981 that were not available in time for publication of the 1981 Minerals Yearbook, but does not include corresponding tables for 1982. The value of raw nonfuel minerals produced in the United States during 1982 was estimated at about $20 billion, a decrease of $5 billion compared with that of 1981. The decline in value is the first since 1971 and is the largest percentage drop since 1938. Although the domestic mining industry continued to be troubled by difficulties in attracting capital and by import competition from countries with lower overall production costs, the principal cause of the decline was sharply decreased demand brought on by the worldwide economic slowdown. Metal commodities were impacted most severely with only 4 of 21 metals registering production value gains and only 3 of 21 showing production quantity increases. Overall metal production value decreased 37% from that of 1981, a reflection of the domestic slowdown in the automobile and construction industries, which are major metal users, Overall production value of nonmetals decreased 12% compared with that of 1981, with only 14 out of 44 nonmetals showing increases. Nonmetal production quantities increased over 1981 for only 6 of the 44 nonmetals.

Jan 1, 1983

Compare the fire endurance of paneled steel stoppings with that of traditional concrete block Stoppings. Background Permanent stoppings or partitions arc used in mines to separate ventilation airways. The ability of stoppings to retain their structural integrity for a minimum length of time under lire conditions and prevent the spread of flame and toxic combustion products to an adjacent airway is critical. The success of miners in reaching safety during a fire depends largely on the presence of uncontaminated airways. Traditionally, permanent stoppings for coal mines are constructed of concrete blocks. Recently, paneled steel stoppings that satisfy many of the requirements demanded of permanent stoppings, such as incombustibility and strength, have been introduced. Their use also introduced concerns such as the ability of a steel stopping to maintain its ventilation control function when exposed to a fire and the potential that the fire could transmit enough heat through the stopping to ignite combustible materials on the unexposed side. To address these concerns, the Bureau of Mines investigated the fire endurance of galvanized steel and concrete block stoppings.

Jan 1, 1989

By F. J. Smith, W. A. Gallagher, C. A. Herbert

"INTRODUCTION A fire started about 10 a.m., November 10, 1947, at the Kings mine, Princeton Mining Co., Princeton, Ind., about 1,800 feet inby the main shaft bottom on the main west haulage road at a point estimated to be 2 miles from the faces of the main west entries. No lives were lost, as 27 men escaped from the mine after a series of explosions, which necessitated sealing the mine on the surface. This information circular shows"" how adverse conditions might be overcome, when reopening a sealed mine, by expert planning and close cooperation on the part of various organizations. Conditions found in the mine after it was reopened were comparable to the worst that had been anticipated, yet the mine was recovered with comparatively little difficulty and a minimum of risk. The open workings in the mine covered a vast area, but most of the mine resumed production of coal after being sealed for only 37 days.The information contained herein also points to the desirability of adhering as closely as possible to a predetermined schedule of operations."

Feb 1, 1949

To develop and design a bit that will rapidly drill smooth and precise instrumentation holes in soft rock. Approach Use a one-piece bit made by combining a drag bit and a diamond bit. Because a smooth-walled borehole with a precise diameter is needed for borehole pressure cells (BPC) and other borehole instruments, a diamond bit is usually used. However, diamond bit drilling is slow, and the bit will tend to bind when squeezing ground is encountered. On the other hand, the drag bit will cut faster, but the walls of the drill hole will be rough and the diameter will not be as precise. The combination will provide a bit which penetrates as rapidly as a drag bit, but retains the smooth-wall and precise borehole diameter of a diamond bit. How It Works A three-foot-length of EW-size drill rod is centered in a diamond bit by welding it to three equally-positioned spacers at each end of the bit. A drag bit is attached to the EW rod with a standard EW-to-drag bit adapter as shown in the diagram. Three equally-spaced diamond inserts are set to the desired hole size and welded to the diamond bit barrel behind the crown. These inserts increase the smoothness and precision of the hole by cut-ting away any hole closure. Three equally-spaced shims are set approximately 0.020-inch under the overall insert diameter size and welded to the rear of the diamond bit barrel. The combination bit should be used on a diamond drill with either water, mist or air as the coolant.

Jan 1, 1982

The instrumentation specification in the National Academy of Engineering (NAE) report of March, 1970, set forth some rather general guidelines that the seismic surface system should follow. The fact that there was no comparable equipment in existence at that time, and the need to produce a system from presently available equipment, was spelled out in that document. The features that the system should include were listed, and included: • Quick and simple deployment • Portability • Battery-powered operation • All-weather operation • Computational simplicity and speed • High reliability and long shelf-life • Dual service for location and communication • Adaptability to widely varying seismic velocities. topography, and geologic structures • Minimum maintenance • Capability of continuous operation for extended periods, and • Reasonable cost Since that report, there has been a substantial amount of field work addressing the trapped miner detection and location problem carried out by Westinghouse Corporation under contract with the Bureau of Mines. Two complete surface systems have been designed, built, and field tested and substantial documentation has been produced on the mine environment and background noise using these systems. These systems, built from off-the-shelf equipment, have been designed with maximum flexibility in mind in order to explore what con¬figuration a field unit should have.

Jan 1, 1974

Rank the dust knockdown (airborne capture) ability of six different types of water spray nozzles, Approach A fixed quantity of dust is released into a large, closed chamber in a laboratory. Water sprays are turned on inside the chamber and their effectiveness on the dust cloud is evaluated from the rate at which the dust disappears. This method better simulates dust suppression underground than methods tried earlier. The results of the laboratory test were confirmed by conducting tests on a full-scale mod-el continuous miner face where dust levels were measured in the return airway. Results of the Closed Chamber Tests The graph indicates that atomizing nozzles provide the best use of water for dust scrubbing. However, use of these nozzles is limited by their susceptibility to damage and clogging. Hollow-cone nozzles perform almost as well as atomizing nozzles. Test results also indicate that full-cone, venturi-assisted, and flat-fan spray cones are about two-thirds as effective as hollow-cone nozzles. The least effective were venturi nozzles designed for moving air. The most significant advantage of hollow-cone nozzles over other nozzles tested is reduced clogging due to larger orifice size. The hollow-cone nozzle used in the test and depicted by the graph was type BD-3 manufactured by Spraying Systems Co., Wheaton, IL. This nozzle is already used on many continuous miners. Other hollow-cone nozzles of

Jan 1, 1982