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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 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'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 J. E. Chilton

The U.S. Bureau of Mines has developed an intrinsically safe carbon monoxide (CO) monitoring system for mines by coupling a fiber-optic data telemetry (FODT) system with a prototype electro-chemical CO monitor. The CO monitoring system can be used in a coal mine as one component of an early fire warning system. This system may be used in belt haulage entries when the entries are used for supplying ventilation air to working places. The FODT accepts a 0.1-to 1.1-V analog signal from the monitor and converts it to pulses (0 to 5 V) at frequencies from 1.1 to 11 kHz that drive a light-emitting diode (LED). An electrically nonconducting fiber-optic cable carries the LED signal to a remote receiver. The receiver analyzes the incoming light signal and displays the measured CO concentration in parts per million. This report discusses the performance of the FODT system and characteristics of the CO monitor such as response times, linearity, and temperature and pressure effects.

Jan 1, 2010

By B. W. Madsen

Research by the Bureau of Mines has shown that treatment of open pit waste by crushing and sizing followed by flotation of the fines and leaching the coarse fraction results in greater metal recoveries than obtained by leaching only. Tests with a chalcocite-bearing quartz monzonite mine waste sample that had been crushed to minus 6 inches and screened on 1/2 inch yielded copper and silver recoveries of 71 and 22 percent, respectively, by the combined flotation-leaching process, compared with 48 percent of the copper and no silver recovered leaching the run-of-mine material. Copper was more readily leached from the coarse material with the minus 1/2-inch fines removed than from material with the fines included. The improved leaching was attributed to improved permeability and the associated improved circulation of air to the interior of the ore column. Cost estimates showed that the proposed intensive treatment of mine waste will require a greater capital investment and higher annual operating costs than conventional milling and dump leaching process. However, the income from the additional metal production offsets the increase in capital investment and operating costs, resulting in additional profit.

Jan 1, 1975

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 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 Lloyd A. Morley

This annual report details progress under USBM Grant G0155003 during the project period of January 1, 1977 through December 31, 1977. The report contains four principal chapters covering accomplishments in the mine electrical safety research areas of continuous monitoring, battery and battery-charging safety, and computer modeling. Highlights of the work are summarized in the last report chapter.

Jan 1, 1978

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 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 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

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 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 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'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 Harvard Eng

An industrial survey was made for the Missouri Basin Field Committee of the Department of the Interior to determine the type and quantity of water-borne mineral wastes and the water requirements of metal-processing industries in the basin in Kansas and western Missouri. Data are presented on metal-processing plants visited through June 30, 1959. Most of the plants were in the greater Kansas City area. This report is to be supplemented with a similar publication on other industries, including those producing sand and gravel, coal, petroleum, and chemicals. In 1958, 19 million pounds of waste materials was discharged from metal processing industries. Approximately 14 million pounds of this waste was in the form of ferrous sulfate, and 2 million pounds was ferric phosphate. Galvanizing, other hot dipping, and automotive industries contributed the greater part of iron compounds wasted; some of this waste occurred as sludge that was not discharged to water courses but was hauled to refuse dumps, podium was present in nearly all industrial wastes, and the total of more than 900,000 pounds constituted one of the larger material losses. Although small in quantity, electroplating and allied coating wastes contained metals that were expensive when originally purchased.

Jan 1, 1961

By Isaac A. Zlochower, Michael J. Sapko, Ronald S. Conti

The Bureau of Mines has developed a system using a high-speed electropneumatic mechanism for the rapid (grab) sampling of dusts and gases during an explosion. The sampling system consists of an aluminum housing that incorporates two 30-cm3 preevacuated glass vials with rubber septums. Upon actuation, the sampling probe needle is driven through the septum with a pressurized air pulse, filling the tube with gas and dust from the mine explosion. After a predetermined time, the sampling probe needle is retracted by a second high-pressure air pulse to its normal (quiescent) state, allowing the sampling tube to reseal. The onset and the duration of sampling are independently variable and controlled by a time-delay relay package. This technique enables the monitoring of pyrolysis-charring in coal particles and the generation and combustion of the pyrolysis vapors in both large- and small- scale explosions. The following results were obtained from full-scale dust explosion tests at the Bureau of Mines Lake Lynn Laboratory: (1) Gas sampling of the leading edge of the flame front shows the large concentration changes, characteristic of the flame front; (2) gas samples taken entirely in the flame zone consist of pyrolysis and combustion products with very low residual oxygen; and (3) the particles collected in the flame zone show signs of extensive pyrolysis and charring.

Jan 1, 1988