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By Richard D. Miller

The helium resources base of the United States was estimated by the Bureau of Mines to be 1,040 Bcf as of January 1, 1987. These resources are divided into four categories in decreasing degree of assurance of their existence: (1) helium in storage and in proved natural gas reserves, 265 Bcf, (2) helium in probable natural gas resources, estimated at 228 Bcf, (3) helium in possible natural gas resources, estimated to be 320 Bcf, and (4) helium in speculative natural gas resources, 227 Bcf. These helium resources are further divided into depleting and nondepleting, with the helium in storage being in a separate classification. The depleting resources are those associated with natural gasfields that are, or will be, produced for the natural gas they contain. Almost all of the helium in potential (probable, possible, and speculative) natural gas resources is included in this classification. These depleting resources are estimated to contain 951 Bcf of the total helium resource base. Helium resources contained in nondepleting natural gas resources, i.e., those in shut-in, abandoned, or otherwise nonproducing natural gasfields, are estimated to total 53 Bef. There is 36 Bcf of helium in storage in the Federal Government-owned Cliffside Gasfield near Amarillo, TX.

Jan 1, 1988

By R. K. Koch

The vapor pressures of liquid columbium and liquid hafnium were deter-mined by the Langmuir free evaporation method as a part of the Bureau of Mines program on the study of transition metals. An electron-beam furnace with a water-cooled copper crucible was used for melting. Temperature was measured with a two-color ratio pyrometer. Least-squares analyses of the vapor pres-sure data gave the following equations: [Logp (atm) = 5 .429 -31,310 T] for liquid columbium in the range 2,740° - 3,140° K, and [Log p (atm) = 5,690 28 T] for liquid zirconium in the range 2,500° -2,810° K. Third-law evaluations of each data set gave mean heats of sublimation (298.15° K) of 175.1±3.2 kcal/mole and 148.3±1.2 kcal/mole for columbium and hafnium, respectively. Second-law standard heats of sublimation determined from sigma plots and from sigma-prime plots agreed fairly well with the third-law values. The sigma-prime plots gave standard entropies of sublimation of 30.96±0.84 eu and 33.S6±0.44 eu for columbium and hafnium, respectively.

Jan 1, 1968

By Aleksandar D. Bugarski

Three types of uncatalyzed diesel particulate filter (DPF) systems, three types of high-temperature disposable filter elements (DFEs), and one diesel oxidation catalytic converter (DOC) were evaluated in underground mine conditions for their effects on the concentrations and size distributions of diesel aerosols. Those effects were compared with the effects of a standard muffler. The experimental work was conducted directly in an underground environment using a unique diesel laboratory developed in an underground experimental mine. The DPF systems reduced total mass of aerosols in the mine air approximately 10-fold for light-load and 20-fold or more for high-load test conditions. The DFEs offered similar reductions in aerosol mass concentrations. The efficiency of the new DFEs significantly increased with accumulation of operating time and buildup of diesel particulate matter in the porous structure of the filter elements. A single laundering process did not exhibit substantial effects on performance of the filter element. The effectiveness of DPFs and DFEs in removing aerosols by number was strongly influenced by engine operating mode. The concentrations of nucleation mode aerosols in the mine air were found to be substantially higher for both DPFs and DFEs when the engine was operated at high-load modes than at low-load modes. The effects of the DOC on mass and number concentrations of aerosols in mine air were relatively minor when compared to those of the DPF and DFE systems.

Jan 1, 2009

By Frederick C. Trutt

Research performed on arcing faults and their interaction; with electrical insulating materials within coal.-mine power-system enclosures is described. This work was performed at The Pennsylvania State University from 1 December, 1976 through 30. November, 1977. Results presented are interim in nature and future research is planned to integrate the simulations which have been constructed, as well as to apply developed experimental procedures to the evaluation of electrical insulating materials for use in coal-mine enclosures. The thrust of this research has been divided into several primary areas. These include the development of a theoretical procedure for computation of three-phase and line-to-line arcing fault currents as a function of time, formulation of an arc model based upon thermal-arc plasma properties so that arc voltages and energies may be computed, development of a simulation for pressure and temperature rises when an arc interacts with an electrical insulating material within an enclosure, experimental evaluation of electrical insulating materials in terms of their tendency to support an arc as well as their potential contribution to enclosure pressure rises, and integration of the above research areas to form overall procedures for theoretical and experimental evaluation.

Jan 1, 1977

By Van H. Manning

Chemical and physical tests of coals for the use of the Government have been made by the United States Bureau of Mines. These tests form part of a general study of the coals in the United States with respect to the manner in which each coal can be utilized most efficiently. As a result of this study, much information of value to all industries using coal has been compiled. Special investigations by the Bureau of Mines of the fuels used by the Government have, until recently, been for the most part limited to coal. In the course of these investigations the bureau has de- veloped new methods for use in the purchase of coal by the Gov- ernment. The application of these methods permits an intelligent selection of the coal adapted to the requirements of particular heat- ing or power plants, and has already resulted in the saving of large sums of money. In addition, these investigations have led to the compiling of a series of carefully made analyses of samples of coal collected in a predetermined manner in the mines of all the impor- tant coal fields in the United States, and these analyses are being published to enable Government purchasing agents and all users of coal to select the coal best suited to their needs. The purpose of this paper is to describe briefly the general char- acter and commercial quality of some of the coals mined in the United States that reach tidewater shipping ports, and to show in a general way the important characteristics of those coals that by reason of transportation facilities and the situation of the coal fields are most available for export. Coals of excellent physical character and of high heating value are available for export. For this reason and because of the modern facilities at the collieries for properly grading large shipments, American producers can supply coals suitable for any kind of service. The transportation system from the mines to tidewater and the coal- handling equipment for loading boats at the various ports are highly developed, so that producers are able to give excellent service to foreign buyers. Enormous quantities of these coals have been used by railroads, manufacturing, illuminating-gas, and coke plants, and seagoing vessels, and for household purposes. Much of the coal available for export is superior to the coals that have been supplied to foreign users from other sources.

Jan 1, 1916

By Dennis R. Dolinar, Lewis A. Martin

Cable bolt technology used by the U.S. coal industry was developed to a large extent in the 1990s. Today, these cable systems include both cable bolts and cable trusses to provide supplemental and secondary support in gate roads. This cable technology is significantly different than the cable systems in use in either U.S. hard-rock mines or Australian coal mines. Development of this technology was initiated and spurred by research efforts of the U.S. Bureau of Mines, and has continued under the health and safety programs of the National Institute for Occupational Safety and Health (NIOSH). It was also followed up by work of roof support manufacturers to create an essentially new support system. In this paper, the important support characteristics of both cable bolts and cable trusses are discussed. The design of cable systems and the basis for that design for tailgate and headgate situations are reviewed and explained. Case histories are presented on the application of these support systems based on experience gained at a number of in situ test sites.

Jan 10, 2000

By Larry A. Haas

The U.S. Bureau of Mines investigated the use of organic binders as substitutes for bentonite in agglomerating iron ore concentrate. Over 30 organic binders were evaluated at several dosage levels in laboratory tests. The binder groups producing the greatest green pellet strengths were natural gums (guars carboxyl methyl celluloses) and gelled starches. The nongelled and alkalized starches, starch acrylic copolymers) wood-related products, and dairy products were less effective but better than bentonite. The highest wet pellet drop numbers were obtained with binders that had a medium plate water absorption value (>500 and <10)000) in distilled water and a high slurry viscosity (>75 cP) at 6 pet solids. The highest dry compressive strengths were obtained with binders that gave the highest adhesive tensile strength (>4 kg/ cm2) on iron oxide lap-joint substrates. Pellets with 0.1 pct organic binder had lower compressive strengths and reduction disintegration indices than those with 1 pct bentonite, but higher reduction rates. Pellets with carboxyl methyl cellulose and gelled starch had higher softening temperatures than those with bentonite. Overall, the most promising binder is gelled starch. Its price makes it more cost effective than carboxyl methyl cellulose, and its pellets have metallurgical properties superior to those of bentonite pellets.

Jan 1, 1989

By Jeffrey Shawn Peterson

The testing procedures of the U.S. Mine Safety and Health Administration specify that intrinsic safety acceptance tests be conducted using a standard tungsten-cadmium electrode configuration in the break- flash apparatus. However, in realistic mining environments, other materials may be more likely sources of sparking. Information defining the probability of spark ignition between common materials such as aluminum, brass, copper, lead, tin, cold-rolled steel, and stainless steel is of more practical value in determining ignition hazards. The U.S. Bureau of Mines has completed an investigation of the influence of material on the ignition probability using the breakflash apparatus. By comparing ignition currents or ignition voltages corresponding to a probability of one ignition per thousand sparks to those found previously for cadmium, a margin of safety may be estimated for each material. This report presents the results of an investigation into the influence of disk electrode material on the probability of ignition.

Jan 1, 1992

By Kung-Lee Wang

This Bureau of Mines study illustrates the economic significance of the Florida phosphate industry to the State and to the Nation. Environmental considerations related to phosphate industry activity are discussed briefly. Based on forecasts of Florida phosphate production in 1975, and using 1972 dollars, regional and national output value, income, and employment created by the phosphate industry were estimated for 1975. State and Federal government tax revenues generated by the phosphate industry, are also measured. Further, the concentrated impact of the phosphate industry on certain Florida areas and on regional industries is examined. Finally, the phosphate industry&apos;s importance to the U.S. balance of payments, U.S. agricultural production, and the Frasch sulfur industry is considered, in addition to byproduct fluorine, and potential byproduct uranium from fertilizer manufacturing.

Jan 1, 1974

By Jay F. Colinet

Respirable dust exposure has long been known to be a serious health threat to workers in many industries. In coal mining, overexposure to respirable coal mine dust can lead to coal workers? pneumoconiosis (CWP). CWP is a lung disease that can be disabling and fatal in its most severe form. In addition, miners can be exposed to high levels of respirable silica dust, which can cause silicosis, another disabling and/or fatal lung disease. Once contracted, there is no cure for CWP or silicosis. The goal, therefore, is to limit worker exposure to respirable dust to prevent development of these diseases. The passage of the Federal Coal Mine Health and Safety Act of 1969 established respirable dust exposure limits, dust sampling requirements for inspectors and mine operators, a voluntary x-ray surveillance program to identify CWP in underground coal miners, and a benefits program to provide compensation to affected workers and their families. The tremen­dous human and financial costs resulting from CWP and silicosis in the U.S. underground coal mine workforce are shown by the following statistics: ? During 1970?2004, CWP was a direct or contributing cause of 69,377 deaths of U.S. underground coal mine workers. ? During 1980?2005, over $39 billion in CWP benefits were paid to underground coal miners and their families. ? Recent x-ray surveillance data for 2000?2006 show an increase in CWP cases. Nearly 8% of examined underground coal miners with 25 or more years of experience were diagnosed with CWP. ? ?Continuous miner operator? is the most frequently listed occupation on death certificates that record silicosis as the cause of death.

Jan 1, 2010

By W. H. Young, R. L. Anderson

"Physical conditions, such as thickness and character of the coal seam, dip or pitch of the seam, depth of cover, character of roof and overlying strata, mine water, etc., affect the productivity in bituminous-coal mining. Thickness of the coal seam being mined is probably the most important single item that determines whether the output per man per day shall be low or high; however, in strip mining the depth of cover or overburden to be moved is of equal importance.Bituminous coal is mined today from seams of exceedingly variable thickness - less than 2 feet to more than 50 feet; however, a large majority of the mines are producing .coal from seams 3 to 6 feet thick. The average thickness of the coal seams mined in the United States has not changed materially in the past 25 years. The average seam thickness for all bituminous-coal mines was 63 inches in 1920 4/ and 65 inches in 19)45. As thick seams have been exhausted in the older fields, other thick seams, have been opened in the newer fields.Productivity increased from 4 net tons per man per day in 1920 to 5.78 in 1945. This 45 percent increase in productivity resulted from increased mechanization. The percentage of underground production represented by coal cut by machines increased from 61 in 1920 to 91 in 1945 Mechanical loading increased from less than 1 percent of underground production in 1920 to 56 percent in 1945, and strip mining increased from less than 2 percent to 19 percent of the total production during the same period."

Dec 1, 1947

By M. L. Whisman

Radiotracer techniques were developed for stoichiometric studies of photochemical reactions associated with atmospheric smog formation. Stock blends of separate hydrocarbon and oxygenated compounds were prepared and calibrated. 14C-labeled reactants and products in reaction systems involving hydrocarbons and nitrogen oxides at the ppm level were analyzed for qualitative and quantitative data. Precision and accuracy of these methods developed by the Bureau were determined by replication and statistical treatment of data, and these methods are described.

Jan 1, 1969

By Henry E. Perlee

In a Bureau of Mines study two-dimensional mathematical equations were solved that describe the transient thermal response of a rock dust particle in a cloud of similar particles in a gas flame&apos;s preheat zone subject to a radiant field from the approaching flame. The description includes both radiant energy absorbed and emitted by the particle and thermal conduction inside the particle and into the surrounding gas environment moving relative to the particle. Two situations were studied; in one the radiant energy incident on the particle is converted to thermal energy at the particle surface, and in the other the radiant energy is converted to thermal energy uniformly over the volume of the particle. The result of the study showed that for a 10-µm-radius particle, a 200-mg 1-1 loading density, and a flame approach velocity of 30 m sec-1, the particle temperature rise was twice that previously calculated by Singer and Cook based on the model of Essenhigh and Csaba. It was further established that under the conditions examined a rock dust particle temperature never increases more than about 200 K before crossing the flame front.

Jan 1, 1976

By P. T. Brooks

The selective recovery of nickel and cobalt from impure raw materials is being investigated by the Bureau of Mines as part of a program to develop improved procedures for preparation of pure metals. A combination solvent extraction-electrolytic process has been developed in the laboratory that enables preparation of high-quality nickel and cobalt from nickel oxide containing, in percent, 76 nickel, 0.8 cobalt, 0.5 magnesium, 0.2 iron, and lesser quantities of copper, zinc, and other metals. The oxide was smelted, using carbon as reductant, and cast into anodes. These anodes subsequently were dissolved in diaphragm-type electrolytic cells. Nickel and cobalt were deposited separately from appropriate electrolytes, concurrent with dissolution of the impure anodes. Anolyte containing nickel and cobalt in the form of chlorides and sulfates was treated for removal of impurities and separation of nickel and cobalt. First, iron and aluminum were removed as hydroxides by adding nickel hydroxide to raise the pH of the anolyte from 2.3 to 4.5. Next, the pH was adjusted to 2 by adding hydrochloric acid, and the solution was treated by solvent extraction to separate nickel and cobalt.

Jan 1, 1963

By d&apos, Kathleen J. Amico

This summary appears in Minerals Yearbook volumes I and III, which cover mineral production in the United States, its island possessions, the Canal Zone, and the Commonwealth of Puerto Rico, as well as the principal minerals imported into and exported from the United States. The several commodity and area chapters contain further details on production. A summary table comparing world and U.S. mineral production also is included. Mineral production may be measured at any of several stages of extraction and processing. The stage of measurement used in the chapter is normally what is termed "mine output." It usually refers to minerals in the form in which they are first extracted from the ground, but customarily includes for some minerals the product of auxiliary processing operations at or near mines.

Jan 1, 1967

By W. E. Miller, W. P. Yant, G. W. Jones, R. E. Kennedy

"The determinations of the limits of inflamability of diethyl ether and ethylene in air described in this report were made primarily for comparison with similar determination of other compounds in the same apparatus and by the same laboratory technic. The experimental procedure and the results obtained differ somewhat from those of other investigations. The work also included determinations of the limits of inflamability of these combustibles in oxygen The investigation,was conducted at the Pittsburgh Experiment Station of the United States Bureau of Mines in cooperation with Merck & Co., Inc. LIMITS OF IMFLAMIABILITY OF DIETHYL ETHER-AIR MIXTURESThe limits of inflamability if diethyl ether in air were determined for upward propagation of flame in an upright, closed 8-liter, cylindrical iron bomb 10.2 cm in inside diameter and 96.5 cm in length. This bomb been described in a previous publication. 6Two brands of diethyl ether were used, one a C. P. sulphuric ether manufactured by Baker & Adamson, and,the other Merck & Co. product manufactured for anaesthesia and containing about 3.5 percent of ether alcohol."

Jul 1, 1935

By A. C. Smith

The U.S. Bureau of Mines conducted a study to evaluate the effect of underground mining conditions on the activation of automatic sprinkler heads. Sprinklers were exposed to liquid fuel fires in a rectangular tunnel at airflows of 0, 45, 90, 150, and 250 m/min to determine the effect of ventilation and fire size on the time to activation. As the airflows were increased, the time to activate the sprinklers for a given fire size increased. Also, as the fire size increased, the activation time decreased. Temperature profiles of the tunnel showed that the maximum temperature near the roof was shifted downstream as the airflow increased. Experiments to determine the effect of rated activation temperature and response time index (RTI) value on activation time showed that the time to activate increased with increasing activation temperature, and decreased with decreasing RTI value. Exposure to the mine environment showed little effect on the activation times in large-scale experiments, and no significant effect in laboratory experiments. The results showed that airflow can have a significant effect on the activation times of automatic sprinklers. This needs to be considered in the design of effective sprinkler suppression systems for ventilated areas.

Jan 1, 2010

By C. P. Mangelsdorf

When the finely bedded shale frequently encountered over coal seams experiences a separation, the material below the separation must behave like a beam or plate in that it must resist both bending and shear. Be-cause of the weakness in interlaminar shear inherent in such strata, shear deflections that are usually ignored in isotropic beam theory may account for a significant part of the total roof sag. Similarly, when a roof truss is installed in such a roof the upward displacement reducing the sag will have components due to shear as well as bending. Questions asked by mine operators about the installation of roof trusses frequently deal with optimum position, slope, and initial tension of the inclined chords. This Bureau of Mines report examines the effects of those chord parameters on the strain energy of both shear and bending and offers optimum values that will minimize the total strain energy of the immediate roof. Design charts are provided, several design examples are included, and the results are compared with current practice. The effects of in situ stresses are investigated and are shown to be equivalent to an additional load on the beam.

Jan 1, 1988

By A. J. Kraemer

[The Bureau of Minas for a number of years has been studying the properties of crude petroleum from producing fields in the United States and Western Hemisphere and has published a series of reports on these fields, including oil fields of Texas.5]

Jan 1, 1927

By K. L. Williams

The Bureau of Mines tested a prototype tapered-element oscillating microbalance (TEOM) dust monitor for measuring respirable coal mine dust. The monitor uses the inertial behavior of a vibrating element to measure the mass of sampled dust. Tests were performed to determine variability, drift, the effect of humidity, placement of collection filter, and element orientation during analysis, and comparability with gravimetric measurements of respirable coal dust. Variability was about 1.6 µg. Over about 26 h at 46 pct relative humidity, drift was very slightly negative. When the relative humidity was increased to 78 pct, all units showed a total positive change less then 40 µg over about 70h. Filter placement variation on the tapered element resulting from in- consistent sizing of the filter mounting bases caused significant error (up to 0.2 mg). In practice, calibration of the system for each new filter will eliminate that error. Orientation of the element during analysis did not introduce significant error, but care is necessary when mounting the canister that houses the element to avoid damping oscillation of the element. Dust tests were performed in an aerosol chamber using coal dust. Measurements made by the TEOM dust monitor agreed to within 10 pct of simultaneous measurements by gravimetric personal samplers.

Jan 1, 1986