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By J. S. Dunning

The Bureau of Mines investigated a series of Fe-Al-Mo alloys strengthened by ZrC (zirconium carbide) precipitates as chromium-free substitutes for stainless steels. Melting and fabrication methods were devised, and the effects of minor additions of columbium (niobium) and cerium on the mechanical properties and oxidation resistance were determined. Zirconium carbides could not be con-trolled reliably to produce fine precipitate dispersions. A more reliable carbide strengthening mechanism is required if the high-temperature strengths of types 304 and 316 stainless steels are to be duplicated. Workability and oxidation resistance of the alloy series were excellent.

Jan 1, 1982

By Bergerm L. B., S. J. Davenport

"INTRODUCTION Oxygen, because of its vital relationship to man's physical well being, is the most important chemical_ element. It may be breathed, however, only in a rather limited range of concentrations and pressures without producing ill effects. An excess of oxygen may be equally as harmful as too little of it. Because of the importance of these effects, the study of the physiological action of oxygen has received attention for many years and by many investigators. Much of the investigative work has been directed toward determining the limits within which oxygen in abnormal concentrations and at abnormal pressures may be breathed with safety in such applica¬tions as deep-sea diving, work in comprossod-air, aviation, the wearing of apparatus designed to permit entrance into irrespirable atmospheres, and in the therapeutic applications of the medical profession.The Bureau of Mines frequently receives requests for information on the effects of breathing essentially pure oxygen, because of the Bureau's association with the use of self-contained oxygen breathing apparatus for entering irrespirable mine atmospheres, and the use of oxygen in conjunction with artificial respiration as a moans of resuscitation. The purpose of this paper is to summarize briefly the effects upon the human body of the inhalation of oxygen in various concentrations and at various pressures and to give reference to other published information that deals in greater detail with the diverse phases of the subject. The literature in this field is voluminous; therefore, a complete bibliography has not boon presented in this paper. No paper on this subject would be complete without reference to the classic pioneering work of Paul Bert (1) 3/ in this field. Articles such as those of Stadia, Riggs, and Haugaard (2), Bean (3), Specht (4), and others cited contain extensive lists of references that will leadthe reader to information in a degree of detail that is not within the scope of this publication."

Jul 1, 1950

By D. S. Burgess

The characteristics of gas-phase detonations were observed in 20 instrumented firings within earthen tunnels, in 100 such detonations in a 24-in-diam by l63-ft-long steel pipe, and in about 200 smaller scale firings. Most of the fuels studied were representative hydrocarbons--acetylene, propane, gasoline, and a roughly equimolar mixture of methylacetylene, propadiene, and propane. In a pipe with two closed ends, the detonable limits were demonstrated to be very nearly the same as reported limits of flammability. The side-on impulses (pressures integrated over 200-msec intervals) were shown to be the same function of concentration regardless of whether deflagration or detonation had occurred. In a pipe with only the initiation end closed, the impulses of all fuel-air systems tended toward the same level when averaged over comparable ranges of fuel concentration; the lower pressures with saturated hydrocarbons were nearly compensated by longer durations of pressure transient. In all fuel-air systems, unexpectedly high impulses were obtained with slightly lean mixtures. In earthen confining structures, the impulse, of the explosion was efficiently converted into momentum of the failing wall. In the configurations studied, an earth velocity of about 20 fps was critical to overcome the soil's resistance to shear. The destructive effect was determined by gas pressure rather than by total energy release. The assignment of a "TNT equivalent" to an explosive gas mixture is discussed in terms of the confinement of the mixture.

Jan 1, 1968

By Franklin B. W. Woodbury

The Bureau of Mines undertook the development and evaluation of a system to provide a simultaneous, on-line determination of both iron and silica in iron ore beneficiation streams as part of a program to improve the efficiency to mineral separation processes, Californium-252 (252-Cf) was the neutron source used in the system for measuring the amounts of silica and iron in bulk slurries by thermal neutron capture-gamma ray spectra analysis. The theory of thermal neutron capture-gamma ray reactions and their potential application to mineral processing stream analysis is discussed. The prototype system and supporting software developed by the Bureau is described. During the initial phase of the work, both simulated and actual pilot plant slurries were investigated using a 60-to 32-µg 252-Cf neutron source. The percent solids of the slurries was ranged from 2 to 40 percent and the silica and iron content ranged from 1.5 to 83 percent and from 10 to 65 percent, respectively. Accuracy of the determination of the components in the solids was dependent upon the percent solids in the slurry.

Jan 1, 1980

By W. E. Webb, R. H. Church, W. G. Hopkins

The development of systems for location of miners who have become entrapped following a mine disaster has been one of the major research goals in the Bureau of Mines. This study details the preliminary development of such a system. Current technologies for locating trapped miners from the surface are either simple direction, finders or time difference pulse systems that have accuracy Limitations. Developing technologies using full vector field measurements at several receiving points are currently being studied. The necessity of measuring field strength with great accuracy can be a drawback in these systems. A system that operates with continuous wave radio signals, whose phase differences can be measured accurately even in weak signal conditions, greatly improves the location accuracy. A microcomputer would be used, in conjunction with the system, to gather and manipulate the data to automatically pinpoint the location of the trapped miner. Comparison of this system with existing technology indicates a favorable accuracy/complexity ratio for the phase difference of arrival technique.

By W. W. Adams

Reports received by the Bureau of Mines, Department of Commerce, from State mine inspectors, for November, 1930, showed that 219 men were killed in the coal mines of the United States during the month, an increase of 25 over the previous month and 33 over November, 1929. On the other hand the production of coal decreased, the output of 43,329,000 tons in November being 8,397,000 tons less than in October and 9,005,000 tone less than in November a year ago. The larger number of fatalities accompanied by a smaller output of coal resulted in a higher death rate4 per million tons in November than in the same month last year or in October, 1930. The November rate was 5.05, as compared with 3.55 for November, 1929 and 3.75 for October, 1930. The increase in the rate for the industry as a whole was chargeable entirely to bituminous mines, as the anthracite mines had fewer fatalities in November than in either of the previous months to which reference has been made. Reports for bituminous mines alone showed that accidents at this class of mines resulted in a death rate of 5.12, based on 195 fatalities and a production of 38,122,000 tons. This rate indicated an increase of 55 per cent over the rate for October, of the same year, and 72 per cent over the rate for November, 1929. The October record was 146 fatalities and 44,150,000 tons, and that for November a year ago was 138 deaths and a production of 46,514,000 tons.

Jan 1, 1930

By Andrew Cecala, John Organiscak, William Heitbrink

Many types of heavy equipment used in the mining and construction industries use enclosed cabs to protect equipment operators from dust and noise exposure. Normally, when the equip- [ ] ment is new, manufacturers' deigned controls are effective at keeping the operator's exposure at acceptable level. However, as equipment becomes older and many components of the enclosure deteriorate, such as gaskets and seals, the effectiveness of the enclosed cab can be greatly reduced. This can cause excessive and dangerous exposures to respirable dust, especially when the ore or overburden contains crystalline silica.

By Gregory M. Molinda

The U.S. underground coal miner faces a continuing hazard from the fall of roof. At the root of many injuries and fatalities are weak or defective roof strata. Throughout mining history, millions of miles of entry have provided exposure of every conceivable geologic roof hazard. This report describes the geologic origin, association, and potential danger from the most common hazards. Discussions of weak rock include drawrock, rider coals, head coal, stackrock, and stream valley effects. Discontinuities, or roof defects, are described including, clay veins, slickensides, joints, and paleochannels. A number of examples from U.S. coalfields are used to document geologic structure and associated hazards. Roof fall analysis is a methodology used by NIOSH for hazard recognition and prevention; its application and benefit to the industry are discussed.

Jan 10, 2003

By Charles L. Kimbell

World political events that occurred subsequent to yearend 1990, but that bear heavily on the global mineral industry, have been of such importance that they cannot be disregaded, and certainly they contribute to any type of "outlook." However, to write of them simply as "forecasts" in an "outlook" section of this study would be to unjustly pretend to status as prophets. Thus, this section covers events that have occurred not as predictions but rather as history. Despite the end of the cold war, the world remained fractionated, at least from the limited perspective of its mineral industry. The fractionation was not so much the result of adversarial politics between countries and groups of countries, although to be sure, such conflicts had not disappeared. Rather, the fractionation was in the widely divergent patterns of performance that resulted from the diverse conditions and problems facing the different countries and country groups.

Jan 1, 1993

By Alexander May

In its role to provide technology to prevent or limit adverse environmental impacts associated with mining or minerals processing, the Bureau of Mines has conducted research at its Tuscaloosa Research Center to asess the environmental impacts of phosphogypsum produced by the Florida phosphate industry. Over the years, stockpiles containing 335 million tons of phosphogypsun have accumulated and the industry continues to generate an additional 33 million tons a year. Samples from approximately 1,000 feet of drill core, obtained from nine stockpiles were characterized using chemical, X-ray diffraction, emission spectrographic, radiological, and physical means. The data developed indicated that phosphogypsum is not a corrosive or toxic hazardous waste as defined by Environmental Protection Agency criteria. Radium concentration averaged 21 picocuries per gram and its content was inversely related to particle sizes. Thirty-nine elements were detected in phosphogypsum; concentrations of these elements did not vary with depth within the stockpiles.

Jan 1, 1982

By Steven J. Schatzel, Gerrit V. R. Goodman, Robert B. Krog, C. Özgen Karacan, Gabriel S. Esterhuizen

Although longwall mining productivity can far exceed that of room-and-pillar mining, the total methane emissions per extracted volume associated with longwall sections are generally higher than those for continuous miner or pillar removal sections. Increased face advance rates, increased productivities, increased panel sizes, and more extensive gate road developments have challenged existing designs for controlling methane on longwalls. Methane control research by the National Institute for Occupational Safety and Health (NIOSH) recently examined a number of practices designed to maintain concentrations in mine air within statutory limits and consistently below the lower explosive limit. These included a reservoir modeling approach to predict methane inflows in gate road entries. The outputs sug­gested that emission rates in the gate roads decreased with the use of shielding boreholes and increased degasification time. Also, mining perpendicular to the face cleats liberated more gas into the mine workings, emissions were almost a linear function of Langmuir pressure and volume, and emissions were inversely related to sorption time constant. Subsequent simulations predicted changes in methane drainage using in-seam boreholes. The results showed that longer degasification times resulted in lower face emission rates. Premining degasification produced more methane than that produced during panel extraction, a fact attributed to the already decreased methane content of the coalbed. This work concluded that longer premining degasification periods would be more advantageous to the operator. The industry trend toward increasing longwall face width can produce increased methane emissions from the face due to a higher volume of cut coal on the face conveyor. Two methods were used to estimate face methane levels on longer faces. In the first method, segmented methane data were extrapolated for greater face widths. The second method estimated emissions contributions from the shearer, face conveyor, panel belt, longwall face, and ribs, and summed these for wider panels. Permeability changes in the gob behind the longwall shields were estimated using a NIOSH-developed numerical model. The results showed that permeability was highest near the edges and corners of the gob.

Jan 3, 2008

By Joseph Cervik, Gerald L. Finfinger

This Bureau of Mines publication reviews underground methane drainage pro- grams being conducted in various coalbeds. Equipment used in drainage programs such as drills, underground pipelines, and methane monitoring systems is described.

Jan 1, 1980

By Noel N. Moebs

Studies by the Bureau of Mines have identified geologic structures in mine roof rock that contribute to many roof falls in Appalachian coal mines. These structures, including paleochannels, scours, pinchouts, slickensides, clay veins, crevasse splays, and joints, can often be identified during, and sometimes before, mine development. Mine projections can be revised to reduce the adverse effects of discontinuitites in roof structure; large roof areas of laminated sandstone or incompetent strata generally can be delineated or inferred from exploratory drill hole data, and the need for supplementary support can be anticipated. Accurate descriptions of roof geology also provide some indication of optimum length and type of roof bolts that should be installed.

Jan 1, 1981

By R. P. Adams

Because of the extreme interest in materials with high melting temperatures and the advantages offered over the powder route for making high-density material, arc-melting and centrifugal-casting methods were investigated for preparing shapes of hafnium carbide with and without excess carbon. Highly satisfactory equipment was constructed and efficient operating procedures were established. Also, methods for preparing consumable electrodes and shrink-tolerant graphite molds were developed. Although crack-free hafnium carbide (6.3 weight-percent carbon) shapes were not made, coherent castings containing 9 to 13.5 weight-percent carbon were produced; the same compositions were shown to be resistant to thermal shock. Selected physical and chemical tests were performed on castings chosen for investigation by chemical and nondestructive inspection techniques. Electrical conductivity and thermal expansion measurements were made. Measurable oxidation of all the compositions studied was observed to start between 500° and 600° C. Attack by nitrogen, however, did not occur until temperatures exceeded 2,000° C. A linear relationship of the logarithm of the diamond pyramid hardness to the temperature was noted. Considerable scatter of the bend-rupture strengths at room temperature and of the tensile strengths up to 2,000° C was found. However, at the latter temperature and above, a definite relationship of strength to temperature was observed and some ductility was noted.

Jan 1, 1968

By Uldis Jansons

This report evaluates the economic Mining feasibility of four selected mineral deposit types that can be anticipated to be found in (d)(2) lands in the western Brooks Range, Alaska. The major assumption made for this study is the availability of a rail system for transporting equipment and concentrates for the base metal mines. Commodity prices used are those in existence in July 1976. Mine models were established based on known deposits and then evaluated. A lead-zinc-silver-barite deposit for which grades were available but ore reserves were assumed would require approximately 25% higher ore grades or higher metal prices to yield a 15% discounted cash-flow rate of return an the investment if mined at a rate of 10,000 tons per day open pit methods. Large copper-zinc mineral deposits could be mined economically at rates either of 5,000 tons per day underground or 10,000 tons per day by open pit methods. A high-grade copper deposit require a copper price of over one dollar ryes pound to yield an economic profit to be mined at 2,000 tons per day by underground methods. A small high-grade gold underground mine would require a gold price of about $295 per ounce to yield a 20% discounted cash-flow rate of return on investment if all new mine equipment were used and if existing labor rates were paid: Enterprising mining groups operating as partnerships might be able to operate this mine profitably at a gold price of about $152 per ounce, perhaps slightly less.

Jan 1, 2012

By Mary S. Esfandiary

This list of organizations that conduct research and development programs on coal has been compiled by the Bureau of Mines with the thought that such a directory may provide a useful guide to worldwide research efforts in the areas designated and may facilitate communication between organizations with similar interests. This list includes government, university, private, and commercial organizations. Many of these groups are conducting comparatively modest but often particularly interesting or specialized investigations. The areas of investigation have been defined in a broad manner--these include analysis and constitution, mining and geology, preparation, combustion, briquetting, high- and low-temperature carbonization, gasification, hydrogenation, Fischer-Tropsch, and health and safety. In some instances such information is not available, but the names of the organizations themselves often indicate immediate arias of interest. Special publications issued by and describing the work of each organization have been cited, when known; almost all of the organizations also publish results of their investigations in the technical press. Several foreign technical and trade publications that include such information and are not published directly by any of the organizations listed are cited in the pages following the list of organizations in each country. This list is not complete. Information that would improve coverage and/or accuracy will be welcomed by the Bureau of Mines.

Jan 1, 1961

By Rudolf E. Greuer, Linneas W. Laage, Xinton Chang

UNIT OF MEASURE ABBREVIATIONS USED IN MFIRE FT foot FT3/MIN cubic foot per minute LBM•MIN2/FT4 pound mass times minutes squared over feet to the fourth FT2/HR square feet per hour BTU/HR*FT*F British thermal unit divided by hours times fimes feet times degree Fahrenheit IN W G inches water gage FT3/MIN cubic feet per minute FT2 square feet FT3 cubic feet LBM, pound mass F Fahrenheit IN W G /CFM2 inches water gage per cubic foot per minute squared PERCENTAGE percent BTU/MIN British thermal unit per minute MFIRE BAT PROGRAM cls echo off echo MFIRE activated mfire0 echo Wait a moment for loading the program if EXIST zheng chg mfirel if EXIST zheng chg mfire2 if EXIST zheng chg mfire1 if EXIST zheng chg erase zheng chg if EXIST hang chg erase hang chg if EXIST yunzhi fan copy yaodong.ion+yunzhi fan yaodong ion if EXIST yunzhi fan erase yunzhi fan if EXIST xintan chg copy yaodong xin+xintan chg yaodong ion if EXIST xintan chg erase xintan chg if EXIST yaodong xin copy yaodong.xin mfire out if EXIST yaodong.xin erase yaodong.xin if EXIST net erase net echo Your output is saved in file MFIRE OUT MFIRE0 FOR PROGRAM CHARACTER•50 A OPEN (10,FILE='NET',STATUS='UNKNOWN',FORM='UNFORMATTED') NETWW=0 WRITE (10) NETWW OPEN (21,FILE='ZHENG CHG',STATUS='UNKNOWN',FORM='UNFORMATTED') A=) ' B=0.0 WRITE (21) A WRITE (21) A,B

Jan 1, 1990

By Spencer P. Howell, J. F. Xrawshaw

"A recent premature explosion in a quarry that resulted in the death of nine men and the injury of several others, was directly traceable to a spark from a steam-shovel working under the face directly in front of the hole being loaded. This accident and similar accidents on record in the Bureau of Mines indicates the necessity for pointing out the dangers in quarries of explosives being ignited by sparks emitted from steam shovels and locomotives, and making recommendations for greater safety.Many premature explosions of which the following are examples, have resulted from sparks, both from steam shovels and passing locomotives. (A) The premature explosion occurred during August, 1920 at a limestone quarry, in a 100-foot drill hole, loaded with 1000 pounds of high-grade nitroglycerin and gelatin dynamites. This hole had been loaded with 500 pounds of 75 per cent strength gelatin dynamite, 300 pounds of 60 per cent straight nitroglycerin dynamite, and 200 pounds of 50 per cent straight nitro¬glycerin dynamite; but no steaming had been placed in the hole. The powderman loading the hole saw the spark enter the hole and was able to run a short distance before the explosion took place, thus escaping serious injury. The explosion of this first hole was transmitted to nearby hole similarly charged. The fall of rocks from these two holes buried the steam shovel and some of the gang of men working around it.(B) In September, 1909, in the Canal Zone, a steam shovel uncovered a misfired charge of dynamite. While the dynamite was being picked up the steam shovel continued working nearby. A spark from the shovel set fire to some loose dynamite spilled on the ground from the troken cartridges. This fire was transmitted to a hole which was being loaded close by and caused a premature explosion. One man was injured."

Nov 1, 1920

By Bill M. Stewart, Phil W. Patton, Curtis C. Clark

Back injuries from handling materials in underground mines continue to be a major safety problem. In spite of the ingenuity of many people and the development of numerous mechanized aids, the number of materials-handling injuries remains second only to the number of roof fall injuries in underground coalmines. Relocation and repositioning of electrical cable, conveyor belt parts, and roof bolt sup-plies in particular are the sources of significant numbers of back injuries. To help reduce such injuries, researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health are examining Mine Safety and Health Administration accident data to determine correlations between materials-handling tasks and the number of back injuries. Also being investigated are new technologies used in underground mines in the United States. Equipment is being developed or modified that would replace the necessity of doing lifting tasks manually. A Coleman manipulator was tested, and modifications were made to make it more suitable for underground mine use. To reduce or eliminate the need to manually clean off materials that commonly plug grizzly openings, a track-guided pincher arm device was developed. Oversized rock can be broken with the pincher arms in the up position, and the arms can be lowered to grab and remove debris. The arm can also be used in a sweeping action to remove cohesive fines that may bridge grizzly openings.

By Paul W. McGann

THE MINERAL INDUSTRIES had a near-record year in 1950, as rising industrial activity in general, greatly accentuated by the outbreak of hostilities in Korea in midyear, called forth increasing supplies of mineral fuels and raw materials. The aggregate value of mineral production was second only to that in 1948, and the aggregate physical volume was exceeded only in 1948 and 1947. Lower coal production accounted for the failure to surpass these earlier years. Growth of production was fairly constant throughout the year, especially for crude petroleum; its physical output for the year as a whole exceeded that of 1949 by 7 percent. According to Federal Reserve Board indexes, other relative gains were 16 percent for coal, 9 percent for fuels in general, and 17 percent for metals. The increase for mining in general was of the order of 10 percent. This was not quite as large as the general increase in industrial production but clearly reflected the total-industrial trend (see fig. 1).

Jan 1, 1953