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By Foster Fraas

In this Bureau of Mines report, use of the photoemission of electrons to produce electric charges for the electrostatic separation of sonic dispersed minerals, which had previously been ground to pass a 43µ-opening sieve, is demonstrated. It appears that many of the oxides, carbonates, sulfides, and arsenides will respond to photoemission. Minerals least responsive are the oxides of silicon, the oxides of aluminum, and minerals that have a high concentration of these oxides. Although several synthetic ore mixtures did not yield to complete separation in a one-stage operation, it is probable that preliminary neutralization of the initial electric charges produced by powder dispersion will provide complete separation. That the separation can be carried out in air and without the use of reagents or heating, which are required in the present practice of electrostatically separating coarse granular feeds, is of special significance.

Jan 1, 1972

By Fred N. Kissell, Maurice Deul, T. D. Moore

Methane emission from two surface gob-degasification boreholes was measured by the Bureau of Mines. The investigation took place during mining of a 3,200-foot longwall panel in the Lower Kittanning coalbed in central Pennsylvania. The first hole was 500 feet from the start of mining, and the second hole was 2,200 feet. The first hole went on natural draft as soon as the longwall face passed it. This caused the methane flow in the return entries to drop 75 pct. In the 6 months required to complete the panel, the two holes emitted 69 MMcf of methane in varying percentages of concentration in air. In 3 years, the holes emitted a total of 150 MMcf of methane.

Jan 1, 1976

By Peter F. Strong, Robert L. Lagace, Alfred G. Exslie

The theoretical study of WF radio communication in coal mines, with particular reference to the rate of loss of signal strength along a tunnel, and from one tunnel to another around a comer is the concern of this paper. Of prime interest are the nature of the propagation mechanism and the prediction of the radio frequency that propagates with the smallest loss. The theoretical results are compared with published measurements. This work was part of an investigation of new ways to reach and extend two-way communications to the key individuals who are highly mobile within the sections and haulageways of coal mines.

Nov 14, 1974

By R. F. Tenney

No detailed information has been published heretofore on the performance of small industrial-type anthracite stokers in building-heating service, apparently because of the difficulty of comparing the performance of one unit with that of another over an entire season's operation. Studies of competitive heating fuels have been similarly handicapped, and attempts to compare fuels are seldom technically sound in this investigation, the performance of a 60-in. Losch4 stoker burning rice-size anthracite in a standard commercial boiler was observed during a 4-month winter-spring season. It was used to heat two buildings at the Bureau of Mines' Anthracite Research Center at Schuylkill Haven, Pa., with the customary type of automatic pressure-range control. Attendance was limited to inspecting, fuel weighing, data recording, and ash removal. Results were computed daily and grouped by weekly periods to minimize daily irregularities. The same stoker-boiler unit had already been tested in a series of American Society of Mechanical Engineers (ASME) test code runs, with the stoker running continuously and with other conditions well stabilized A comparison of results from the code test and the building-heating tests provided information not available in the past for a single stoker unit, assisted in analyzing heat losses not computable in a cyclic operation, and established a basis for evaluating stoker performance in heating service.

Jan 1, 1963

By P. Delogne, L. Deryck, R. Liegeois

So far as the propagation of electromagnetic waves is concerned, an underground tunnel behaves like a pipe or hollowed waveguide. Waves propagate in this tunnel with a low attenuation only if their frequency is higher than a so-called critical frequency which depends on the shape and mostly on the cross -dimensions of the tunnel and which value is in the neighbourhood of several tenths of MHz. However, when a metallic conductor is stretched along the gallery the electromagnetic characteristics of the latter are considerably modified and the effect of the cut-off frequency disappears; this is due to the fact that the gallery equipped with such a conductor works like a coaxial cable where the conductor serves as the outward conductor and the wall of the gallery as the return conductor. This is the principle of the monofilar waveguide cable which has been perfectly studied by Gabillard. Two mean characteristics of the monofilar mode are as follows: first of all, when the cable is suspended in the middle of the cross section of the gallery, the electromagnetic field occupies all the space between the wire and the walls of the gallery. When the wire is close to the wall, the electromagnetic field tends to become concentrated between the wire and the wall, with the consequence that, with the given monofilar mode power, the aerial of a receiver standing somewhere in the tunnel will capture a weaker and weaker signal. Secondly, owing to the fact that the mode of monofilar propagation uses the ground as return conductor, its power of propagation is considerably diminished; the closer the wire is to the wall the higher the attenuation, for only a very small part of the wall is utilized as return conductor. To cover great distances, everything else being equal, two or more conductors must be placed in the gallery. If the distance between two conductors of a cable is much smaller than the distance between one or other of the conductors and the walls; or again if one of the conductors surrounds the others and forms a screening, two sorts of modes appear: on the one

Jan 1, 1973

By Larry Patts, Michael J. Brnich

Approximately 45% of U.S. coal is produced from underground mining. The use of diesel engines to power under- ground mining equipment has steadily increased over the past four decades in an effort to improve mine safety and productivity. Several advantages realized with the use of diesel-powered mining equipment in underground coal mines are listed in Table I. The primary disadvantage of using diesel equipment in underground coal mines is that diesel exhaust emissions can contaminate mine ventilation air. The major constituents of diesel exhaust are gaseous emissions (which include carbon monoxide, carbon dioxide, oxides of nitrogen, sulfur oxides and unburned hydrocarbons) and diesel particulate matter (DPM). The Mine Safety and Health Administration (MSHA) has incorporated threshold limit values for all gaseous components of diesel exhaust into their regulations. These have been established by the American Conference of Governmental Industrial Hygienists.

By M. Howard Berliner

During the spring of 1944, the Bureau of Mines investigated the Crescent mine area near the village of Rewey, Iowa County, Wis., as part of a general investigation of the zinc-producing area of southwestern Wisconsin. The work was done when every effort was being made to increase the production of metals important to the Nation's war program. The Bureau of Mines completed 24 churn-drill holes in an area immediately to the west of a mineralized section which had been mined through shallow workings for lead and zinc more than 40 years earlier.

Jan 1, 1948

By Bernard Porter

The rate of the heterogeneous reaction between high-purity uranium metal and uranium tetrafluoride in molten lithium fluoride was measured. The apparent heat of activation for the reaction is 16.91 kilocalories per mole of UF4. A surface-controlled mechanism is suggested in which UF4 is adsorbed on the uranium metal surface. Additional UF4 reacts with the adsorbed species and the metal site to form an activated complex that decomposes to the product UF3. The reaction is an important source of metal loss in the electrowinning of uranium metal.

Jan 1, 1966

By S. H. Katz

"At the annual meeting of the International Association of Fire Engineers at Kansas City, Mo., in June, 1919, the Bureau of Mines offered to cooperate with municipal fire departments for the purpose of obtaining information regarding composition of the air in burning buildings. (Katz, S. H., Statement made at Convention of International Assoc. of Fire Engineers: Fire and Water Eng., vol. 66, July 16, 1919, pp. 129-30, also Fireman's Herald, vol. 78, July 12, 1919, pp. 48.) The gas-mask laboratory of the Bureau's experiment station at Pittsburgh sent vacuum bottles for taking samples to fire chiefs in twenty-five cities, who had signified their intention to aid in this work. It was hoped to obtain one hundred or more samples, because statistics in quantity are necessary for drawing reliable conclusions concern-in the likelihoods of encountering irrespirable as in burning buildings. This far, eleven samples have been received by the laboratory. Results of analyses and pertinent data regarding these samples are given in the accompanyingEight of the eleven samples contained, no carbon monoxide; seven of the eight were taken above the ground level and one below ground. One sample taken above ground contained 0.03 per cent carbon monoxide, and this quantity is not dangerous to breathe for a limited time. Of the three samples taken below ground, one contained no carbon monoxide; the other two contained 0.10 and, 0.35 per cent, respectively. This indicates that in a burning building, the hazard from carbon monoxide is much greater below the ground level. The cause undoubtedly lies in the poorer ventilation that is usually found in cellars or basements. Abundance of ventilation provides the necessary air for complete combustion, or if incomplete combustion does occur, the carbon monoxide generated by the fire is greatly diluted with fresh air and swept away by the current. It may be noted that the highest proportion of carbon monoxide was found in a cellar where a fire as burning among piled cases. The difficult access of air to the burning parts facilitated the formation and lib ration of carbon monoxide. The smoke here was very light and no difficulty was experienced in breathing. Some of the air containing dense smoke showed little change from normal air by analysis. Thus the density of smoke or the irritation and difficulty it causes in breathing are no indication of the presence of poisonous gas. None of the samples shows important oxygen."

Nov 1, 1920

By David C. Oyler, Winton J. Gale, Jinsheng Chen, Christopher Mark

A collaborative project between RAG Emerald Mine, NIOSH, and SCT Operations was conducted to investigate ground behaviour, reinforcement performance, and stress redistribution in a coal mine entry subjected to a severe horizontal stress concentration. Field measurements indicated that the stresses applied to the study site nearly doubled during longwall mining, resulting in roof deformations extending to a height of 4.8 m (16 ft) above the entry. This paper focuses on the computer simulation that was undertaken to provide more insight into the roof behaviour and rock bolt interaction during mining. The model’s input rock properties were derived from extensive laboratory testing, and the model itself simulated a broad range of failure mechanisms. The effects of different bolt patterns on roadway behaviour were evaluated. Comparison between the model results and the field measurements indicated that that the model effectively simulated the critical elements of the actual roadway’s behaviour. With the confidence gained, the model was used as a baseline for additional simulations that evaluated the expected performance of alternative roof support systems. The study will also provide a benchmark data set for future applications of numerical modelling to U.S. coal underground mining.

By A. L. Murray

"Welfare endeavor in connection with both the metal and the coal mines of Utah has shown gratifying progress during recent years, and in most mining towns of the state, both the operators and their employees deserve much credit for the efforts put forth to better the living, working, educational and recreational conditions. Progress has been and is being made, but there are still a few important towns where purer water and better sewage disposal are pressing needs.In the older metal-mining towns that are incorporated and are independent of the mining properties operating in the vicinity, less opportunity is presented for the companies to exercise efforts looking toward improved welfare conditions than in company towns controlled by the mine operators.However, even in such towns the companies can do much to better welfare conditions, as shown by the progress in Bingham Canyon during the past several years. The Utah Copper Company has spent $800,000 since 1920, in the erection of modern brick cottages, apartment houses and the Germnell Memorial Club. The cottages and apartment houses have every convenience to be found in up-to-date city homes. The Gemmell Memorial Club erected and equipped at a cost of $175,000 was provided by the company for the benefit of the Utah Copper employees living in the canyon and has been made the recreational center for the camp. Another improvement is the $100,000 fireproof hotel built by the United States Mine of the United States Mining, Smelting and Refining; Co. in the Copperfield section of Bingham Canyon. This hotel will accommodate 105 men exclusive of hotel help and has all the conveniences of a city hotel."

Sep 1, 1925

By Ronald S. Conti

Fire is a major concern for those who work in underground mines. A mine fire can occur at anytime and often results in a partial or total evacuation of mine personnel and could result in the loss of lives. Therefore, having a workforce that is well trained to prevent, detect, and fight a fire is important. This paper focuses on responders’ preparedness for fire. Responders in this context are considered the entire workforce and are categorized as first, second, and sustained responders and evacuating miners. Quality training enhances ones awareness of mine fire hazards and promotes self-confidence in combating fires and responding to emergencies. Early warning systems and other escapeway aids such as a through-the-earth signaling and communication system, lasers and strobe lights are also addressed. The technological advancements that have been made can improve the state-of-preparedness for responders to underground emergencies and increase the chances of survival for escaping personnel.

By J. H. Perkins

The Bureau of Mines has conducted desorption work on fine coal particles at near atmospheric pressure. An apparatus Iris been developed that uses a capacitance manometer to measure desorption of methane from coal particles up to, 2 inches in diameter and pressures up to 1,000 psi. This will make it possible to duplicate the desorption process as it occurs in its natural underground environment.

Jan 1, 1969

By Charles L. Kimbell

The final tables of this chapter, tables 25-50, extend and expand the statistical series on production that was started in the 1963 edition of the Area Reports: International Volume of the Minerals Yearbook and that was subsequently updated and expanded in the 1965 and 1967-90 editions. Continuing the practice started in 1989, a column has been included in each of these tables providing a 5-year average for 1987-91, inclusive. This should provide a clearer picture more rapidly of the role of each major producer over the 5-year period. The listing order of major producers, however, continued to be, as in past years, in descending order of rank in the year of review, 1991. This group of tables now includes each of the crude minerals that ranked from? 1st to 19th in 1983 terms of value of their output (as well as four others of lesser rank). These 23 crude mineral commodities accounted for 93 % of the estimated value of world crude mineral production in 1983. In addition, world output of five key downstream products-aluminum, steel, cement, nitrogen in ammonia, and refined oil-is included because of their significance as products.

Jan 1, 1993

By Henry M. Harris

The Bureau of Mines investigated a glass containing approximately 17 percent lithia and 83 percent silica to establish a method of devitrifying cast and rolled shapes. Glass shapes with high strength were made by melting, forming, and rapid cooling of the composition, and the shapes subsequently were converted to a crystalline condition by heat treatment. The best devitrification schedule included rapid cooling of the glass to below 300° C, followed by reheating at a rate of 50° to 400° C per hour, depending on the size of the shape, followed by a of 60 to 70 hours at 500° C and another period of 15 hours at 800° C. attempts to use faster heating rates or slow cooling to accomplish devitrification in deformation of the shapes. The crystalline shapes had flexural strengths that averaged over 33,000 psi, achieved with an annealing time of 60 to 70 hours at 500° C.

Jan 1, 1965

By J. D. Noll

The Mine Safety and Health Administration (MSHA) has promulgated rules to limit the exposure of metal/nonmetal underground miners to diesel particulate matter (DPM). These rules have resulted in many types of control tech­nologies being implemented including diesel particulate filters (DPF). The passive type DPF is the most desirable because it requires little maintenance and it regenerates while the vehicle is operating. One problem with passive DPFs is that many vehicles cannot develop the sustained exhaust temperatures needed to initiate DPF regeneration, and thus it is required that the DPF be catalyzed to decrease the temperature needed for regeneration. In some past studies, such catalyzed filters have been shown to cause an increase in the nitrogen dioxide concentrations in the exhaust, resulting in a potential health hazard. In this study, a lightly catalyzed DPF along with a fuel-born catalyst were employed to help reduce the DPM emissions from a 980F loader used for cleanup in a stone mine. After 30 days of use, the filter continued to regenerate successfully at the exhaust temperatures generated by this loader, substantially reduced DPM concentrations emitted in the exhaust, and did not cause a measurable increase in nitrogen dioxide levels that could be attributed to the device.

Jan 1, 2009

By Greenwald, H. P

The Bureau of Mines has been conducting experiments on the explosibility of coal-dust in the experimental mine for more than 17 years. The results have been published from time to time3, and a forthcoming technical paper4 will summarize the results and discuss them in some detail. The present paper will be limited to a statement of the more important facts that these researches have discovered.

Apr 1, 1929

By C. D. McMaster, John C. Hartley

Three systems that monitor ventilating fans are described . These electronic monitoring systems automatically perform most of the operations required to conform with the provisions of the Federal Mine Safety Code in the event of fan failure or slowdown .

Jan 1, 1964

New Continuous Personal Dust Monitors (CPDM) submitted to NIOSH for approval to sample coal mine dust must accurately measure respirable coal mine dust in mine environments. There are two steps in the process which may be done in any order. The manufacturer is required to submit the results of a comparative underground coal mine dust sampling study, where the candidate CPDM is compared to an approved coal mine dust sampling device (currently the Coal Mine Dust Personal Sampling Unit (CMDPSU)). This testing shall follow the guidelines outlined below and shall demonstrate through weighted regression analysis that the mean coefficient of variation with bias correction is equal to or less than 12.8%. The other step involves laboratory testing to determine the electronic and environmental stability. This testing must be conducted by a private, commercial, academic or other laboratory approved by NIOSH.

Jan 1, 2009

By R. Van A. Mills

This preliminary paper is intended to answer briefly some of the inquiries coning to the Bureau of Mines regarding the so-called "paraffining", of oil wells and methods of preventing and remedying that trouble. The increased difficulties in operation and the losses of production caused by the deposition of gummy and waxy hydrocarbons, commonly called paraffin, in the wells, tubing, other pumping equipment, and in the pores of the productive sands, have long been recognized but the trouble has not been overcome. The nature and causes of the trouble, together with some of the possible methods by which it may be diminished or overcome, are outlined below. Character of the Peraffining Materials. The so-called paraffin that collects in oil wells end in the pores of the oil-producing sands immediately around the wells, is generally made up of amorphous wax or uncracked paraffin, asphalt, or other gummy hydrocarbons mixed with more or lees water, oil, and inorganic silt. Some of the samples of this "paraffin" collected from oil wells in different fields and examined by the Bureau of Mines contain as mach as 20 per cent by weight of water and inorganic silt, whereas other samples are composed entirely of waxy hydrocarbons and oil. The inorganic silt accompanying this "paraffin" is mostly fine sand, clayey materials, common salt and finely disseminated precipitates of calcium and magnesium carbonates. Sulphates of calcium, barium, and strontium are less common constituents of the "paraffin."

Jan 1, 1923