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By L. C. IlsLey

Explosives have been fired electrically for several decades. Mountains have been tunneled, deep shafts sunk, extensive coal and metal mine workings excavated and, in times of war, railroads, buildings, bridges, and fortifications have been destroyed by means of electrically fired explosives. Modern engineering depends so much on explosives that their safe and efficient handling and especially their detonation are of prime importance to all those connected with the use of explosive agents. Electric shot-firing is only one method of igniting explosives, but it is rapidly spreading and because of certain inherent safety features should be encouraged. Data collected by the Bureau of Mines indicate that in the United States a large percentage of the blasting in quarries, shafts, and tunnels, and from 15 to 25 per cent of the blasts in mining operations, are set off electrically. The Bureau of Mines is interested in electric shot-firing because of its use in mining, and especially because electric methods, when properly applied, are undoubtedly safer than other methods commonly used.

Jan 1, 1926

By R. A. Beall, S. L. Ausmus

The development of a completely water - free expendable graphite mold material , useful for reactive metal castings , has been detailed . Mixing and curing variables have been evaluated both by physical testing of the material itself and by castings of titanium , zirconium , and hafnium . The blend of powdered graphite , cornstarch , dextrin , cereal binder , linseed oil , and Carbowax -4000 is a successful mix when mulled in a carbon dioxide atmosphere , and properly cured and fired . The primary advantage of this material is its adaptability to standard foundry techniques ; i . e . , core blowing and hand ramming . Temperatures in the curing and firing cycles do not exceed 960 ° C , and no vacuum firing is required .

Jan 1, 1964

By Robert H. Peters

Several significant problems associated with employee turnover among underground miners are described in this Bureau of Mines report. Although a vast amount of research has been conducted on turnover among employees in nonmining industries, there has never been an attempt to empirically investigate the causes of turnover among underground miners. This report presents the results of empirical research on employee turnover in other industries and describes and critiques the research methods that have been used to investigate turnover. Using the findings on employee turnover in other industries and known data about miners and the mining industry, a conceptual model of the factors that cause turnover among miners was generated. This model, which is expected to provide a basis for later empirical studies, is presented. Several recommendations for controlling miner turnover are also presented.

Jan 1, 1986

By G. S. Rice

The Experimental Mine of the United States Bureau of Mines is a unique coal mine that serves as a large-scale testing laboratory. It is used primarily for testing the explosibility of coal-dust and gases but is also the workshop for many other kinds of research work of which the chief object is to increase safety in mining. The mine is situated in Allegheny County, Pa., about 13 miles southwest of Pittsburgh among the high hills of the west bank of the Monongahela River, at the northeastern edge of the gas-coal district of the Pittsburgh coal bed which extends south through the Connellsville coking-coal district into West Virginia. The Pittsburgh bed, of the Upper Carboniferous age, is one of the most extensive continuous coal beds in the United States, if not in the world. Throughout large areas it shows remarkable uniformity of thickness, levelness, and character of coal, which is a coking coal of high-grade bituminous rank. Its thickness in the northern part is 5 to 5 ½ feet and in the central and southern part is 7 to 9 feet.

Jan 1, 1933

By Albert L. Toenges

The development of Alaska depends on the existence of an adequate fuel supply in the Territory. The need to investigate coal deposits was recognized as early as 1911, when the first investigations were conducted in Alaska by engineers of the Bureau of Mines. Conditions existing in the Bering River and Matanuska coal fields, as found by Dr. Robert A. Holmes, former Director of the Bureau of Mines, are described by the Honorable W. L. Fisher, former Secretary of the Interior./ Following Dr. Holmes' investigation, a party of Bureau of Mines engi¬neers headed by R. Y. Williams visited the Bering River field in 1912 in cooperation with the Navy Department. A detailed examination was made of the Bering River field, and 855 tons of coal were mined from three prospects on Trout Creek. This bulk sample was delivered to the Navy for steaming and other tests. A description of the work of the field party and results of tests of the coal by the Navy Department and the Bureau of Mines has been published.

Jan 1, 1949

By John W. Kopp

Stemming is used in blasting operations to help contain explosive gases as long as possible. Stemming can reduce airblast, improve fragmentation, and reduce the chances of hot explosive gases igniting methane and dust explosions in underground mines. Stemming is required in underground coal mines but is generally not used in underground metal and nonmetal mines. Some underground metal and nonmetal mines are classified as gassy and can require special blasting procedures such as the use of stemming to minsure the safety of miners. The types and amounts of stemming material that are desirable in underground metal and nonmetal mine blasting to ensure good or improved fragmentation while containing the hot gases are largely unknown. This Bureau of Mines research examined the effectiveness of differing lengths of stemming by measuring stemming ejection times as related to burden movement. With properly stemmed blasts, stemming is contained until some burden movement has occurred. Test blasts at two surface limestone quarries were evaluated using high-speed photography. For the conditions of these tests, a stemming length of at least 26 charge diameters was found to prevent premature stemming ejection. In tests with stemming lengths of 16 charge diameters, the stemming was effective but there was early venting of hot gases through fractures in the rock. Further testing with other rock types, hole diameters, explosive types, and stemming materials as they affect incendivity is recommended.

Jan 1, 1987

By Neal M. Muir, Robert S. Sanford, Bruce I. Thomas

"INTRODUCTION The presence of the zinc-lead-copper deposits an the north slope of Mount Eielson, Mount McKinley National Park, Alaska, has been known for many years. The deposits were examined by J. C. Reed, a geologist of the United States Geological Survey during the summer of 1931. In the summer of 1943 the authors and Clyde Wahrhaftig, a geologist of the Geological Survey, examined the deposits.ACKNOWLEDGMENTSIn its program of investigation of mineral deposits, the Bureau of Mines has as its primary objective the more effective utilization of our mineral resources to the and that they make the greatest possible contribution to national security and economy. It is the policy of the Bureau to publish the facts developed by each project as soon as practicable after its conclusion. The Mining Branch, Lowell B. Moon, chief, conducts preliminary examinations, performs the actual investigative work, and prepares the final report. The Metallurgical Branch, Oliver C. Ralston, chief, analyzes samples and performs beneficiation tests.Particular acknowledgment is due to Heine Kenworthy, who conducted the beneficiation tests under the supervision of C. Travis Anderson; to Clyde Wahrahaftig of the Geological Survey, who completed the Geologic and topographic maps, to Grant Pearson of the National Park Service; and to O. M. Grant and Mrs. Frank McGarvoy for their assistance during the examination."

Nov 1, 1947

By L. R. Burdick, J. F. Barkley

"The agglomerating index of coal is an index based upon the nature of the coke residue left when the standard volatile-matter determination of the well-known proximate analysis is made. In this determination a small amount of coal is heated in a container to about 950° C. (1,742° F.), at which temperature the volatile matter is driven off, leaving a coke formation. The coke residues for various coals are quite different in physical structure: and, for some time past, work has been done on studies of the nature of these residues in connection with the coking of coal. In 1934 Gilmore, Connell, and Nicolls proposed use of the agglomerating index for indicating the dividing line between noncaking coals and those having weakly caking properties. 4/ Its use was adopted in the standard classification of coals by rank as a requisite physical property index to differentiate semianthracite from low-volatile bituminous coal and also high-volatile ""C"" bituminous from subbituminous ""A"" coal, as shown in table 1, the standard coal classification adopted by the American Society for Testing Materials and the American Standards Association. 5./In studying the agglomerating properties of coals based on the coke residue the Bureau of Mines has adopted the notation given in table 2. Coals that in the volatile-matter determination give a coke residue either in the form of an agglomerate button that will support a 500-gram weight without pulverizing or a button that shows swelling or cell structure are considered to be agglomerating."

Nov 1, 1938

No noticeable international economic recovery occurred during the first half of 1982. Industrial production continued to fall in the United States, Canada and Italy and to hold steady in France. Modest increases in production occurred in Japan, England and Germany, although some decline took place from March to April. The U.S. mining industry has been more severely affected by the world recession than the U.S. economy. This is not immediately obvious when comparing the U.S. mining industrial production index from 1981 to 1982, which decreased 8.5 percent, as compared to a 7.1 percent decline for total domestic industries. However, "mining" industry statistics in the U.S. national economic accounting system include petroleum and natural gas as well as minerals. When metal mining is isolated, the decrease in production from 1981 to 1982 is 19.3 percent. If metal mining production continues to perform at the same rate during the third and fourth quarters of 1982 as during the first half of the year, declines from 1981 levels will be quite severe. Aluminum will have declined 22 percent, copper 18 percent, iron ore 24 percent, lead 3 percent, steel 29 percent, titanium 2 percent and zinc 25 percent.

Jan 1, 1982

By Richard L. Fischer

Constant-volume charges of precipitated PETN (pentaeythrite tetranitrate) at three specific gravities (0.50, 1.00, and 1.50) were used in laboratory tests to examine the effects of changes in explosive properties on free-surface displacement pulses and on crater dimensions. The tests were performed in large blocks of cement-mortar. The values for the detonation velocity, detonation pressure, specific energy, energy density, and energy release rate were calculated from the explosive loading density. Calculated explosive properties were correlated with free-surface displacement pulse measurements, strain energy, and measured crater dimensions. Increases in explosive properties resulted in increased free-surface displacement pulse parameters and crater dimensions. The loading density, detonation velocity, energy density, detonation pressure, and energy release rate were found to be best indicators of explosive performance. Simple acoustic relationships involving impedance ratios were examined and could not be used to predict peak displacement amplitude or strain energy. Data are presented in the customary English units as well as the International System of Units (SI).

Jan 1, 1970

By Robert A. Speirer, Richard G. Burdick

Methods of detecting geologic faults and other linear features by means of processed LANDSAT satellite images have gained prominence during the past several years . There have been numerous programs written to pick these " lineaments , " but they have been almost universally tailored to large computers . This Bureau of Mines report describes a detection method developed for use with a minicomputer . The method comprises a suite of programs that scans an image for all " potential " lineaments . From this partially analyzed data , the final lineaments are picked by another routine . The method was field tested in an area of south- central Wyoming , and results indicated good agreement between computer- picked lineaments and ground features . Most of the known geologic faults in the area were picked by the method . Such features as roads and trails were also picked but were easily distinguished from faults during field inspection . The method is relatively new but promises to be a viable reconnaissance technique for the mining industry in geologic structural analysis .

Jan 1, 1965

By R. Burrell, N .. L. Lapp

"Except for asthma and pulmonary infections, the types of lung disease that have been of immunologic interest the longest are the various mineral pneumoconioses. Because of their chronicity, type of pathology produced, and well-known immunotoxic properties associated with the dusts inciting them, the pneumoconioses have long drawn attention to the possibility that the immune system has not only been modulated but that its effectors have possibly contributed to their pathogenesis. All of the mineral dusts reviewed here have definite immunomodulating properties and act on various cellular and molecular components of the immune system. Further, each has an immunotoxic potential to induce either hypersensitivity (as in the case of beryllium) or other types of immune injury. This article reviews the immunologic aspects of the four major occupational minerals that have an immunologic impact on the lung: asbestos (particularly chrysotile), silica or quartz, beryllium, and coal mine dust.These agents have many things in common, yet each is distinctive. Although the possibility still exists that these mineral particles can adsorb intrinsic tissue antigens or extrinsic organic antigens to their surfaces and initiate immune responses to the adsorbed antigens, only one, beryllium, can act as an antigen itself. Silica is a profound macrophage toxin and thereby exerts many effects on those factors controlled by macrophages. Asbestos has undergone the most immunologic studies resulting in a much dearer picture of how it may contribute to immunopathology. Coal mine dust is the agent about which least is known immunologically, partly because there is no such thing as purified coal mine dust or a standard by which coal mine dust can be defined. Indeed, there are studies that use only the dust from the ground coal itself, whereas other studies use the total dust collected from air samples of a working mine in the belief that other types of dusts (e.g., silica from roof bolt drilling, from sand ground on the rails by cars, and from surface drilling) contribute to the disease (Figs. 1 to 5). This properly is coal mine dust and is poorly characterized. Yet, workers exposed to these dusts share similar reactive characteristics and they may be considered collectively as well as individually."

Mar 1, 1992

By Charles B. Kenaban

The possibility of using ultrasonic energy as a tool to improve the electrolytic deposition of copper and zinc from several electrolytes was investigated by the Federal Bureau of Mines. Sound with frequencies of 20, 26, 38, and 400 kilocycles per second and acoustical intensities of 0.25 to 1.5 watts per square centimeter was employed. Measurements of cell voltage, anode and cathode current efficiencies, and electrode potentials were made at various current densities. Effects of ultrasonics on the quality of the deposit and on anode corrosion also was noted. In the electrolytic recovery of copper from an acid copper sulfate solution at 50° C., adherent, well-consolidated deposits are normally obtained up to a current density of 30 amperes per square foot. As the current density is increased above this value, the deposits normally become progressively more spongy and less adherent. Ultrasonic irradiation resulted in adherent and well-consolidated deposits at current densities up to 300 amperes per square foot. Radiation also produced smaller grain size and preferred orientation of the copper crystals. In addition, radiation caused as much as 3-volt decreases in cell voltages at the higher current densities. These decreases were caused chiefly by depolarization of the anode, although small depolarization effects were also noted at the cathode. Radiation apparently did not greatly affect cathode-current efficiencies, but prevented excessive anode corrosion at the higher current densities and resulted in more uniform corrosion. Ultrasonic radiation at a frequency of 400 kilocycles per second was not as effective as radiation at the lower frequencies. Circulation of the electrolyte at rates up to 5 percent of the cell capacity per minute did not produce results comparable to those effected by ultrasonic radiation. Rapid rotation of the cathode up to 1,800 revolutions per minute gave results approaching those obtained with ultrasonics.

Jan 1, 1961

By R. S. Dean

This report, the third of a series of annual reports of the Metallurgical Division to be released in this form, covers the fiscal year July 1, 1936, to June 30, 1937. The technological work of the division is performed by sections. Thus, an efficient organization is provided to prosecute the various problems under investigation, and a logical system is set up for presenting the material contained in this report.

Jan 1, 1937

By R. S. Dean

The work of the metallurgical fundamentals section during the past year, representing active experimental investigation or thermodynamic study, may be summarized as the following problem subjects: 1. Low-temperature specific-heat investigations. 2. Development of a method of concentrating gases. 3. Thermodynamic properties of metallic carbides and nitrides, 4. Production of pure chromium from chromium chlorides. 5. Thermodynamic properties of the hydrates of calcium, sulphate. While this list is not identical, with officially designated problems, due to overlapping of subjects and to new developments within specified problems, presentation upon the basis of this subdivision will best serve to review the work of the section.

Jan 1, 1937

By W. H. Oppelt

A small, annular-retort gasifier having a nominal capacity of 40 pounds of lignite per hour was designed and constructed at the Lignite Experiment Station, Grand Forks, N. Dak. The purpose of the investigation was to increase the capacity of an annular-retort gasifier by better temperature distribution in the heating chamber (adjacent to the annulus) and by supplemental internal heating with controlled amounts of air. Correct control of air admission should yield crude ammonia-synthesis gas having a (H2+CO)-N2 ratio of 3. Dakota Star stoker-size lignite was used during the exploratory experimental program. The effects of temperature level and distribution in the heating chamber and of addition of air to the reactor were investigated. Hydrogen - carbon monoxide ratios ranged from 1.9 to 2.5, and (H2+C0)-N2 ratios were as low as 2.9. Hourly gas production ranged from 970 to 2,580 cu. ft., or 62.0 to 164 cu. ft. per sq. ft. of heated surface, or 350 to 940 cu. ft. per cu. ft. of reactor volume. Data from the small gasifier could be readily correlated with those previously obtained in the commercial-scale unit under comparable experimental conditions.

Jan 1, 1957

By N. L. Wimmler

"INTRODUCTION The Southern Cross district in Deer Lodge County, Mont., has been chiefly a gold producer. Most of the production has come from gold-bearing hematite-limonite ores. Some of these ores were mined and shipped to smelters for use as flux in smelting copper ores. A magnetite deposit in the Pomeroy property, containing no gold or other economic nonferrous minerals, was mined from 1921 to 1923, the ore being shipped to smelters for flux.The iron-bearing deposits in the Southern Cross area were examined by Bureau of Nines engineers/ on June 28, 1943, and October 14, 1943. As a result, a Bureau exploration project was recommended; it was conducted during 1944. A magnetometer survey was first made of the magnetite-bearing area at and in the vicinity of the Pomeroy property. Exploration by diamond core drilling was then conducted within this area, and in the Southern Cross and Hold Fast properties. The cyanide tailings dump at the Hold Fast mill was sampled by auger drilling.This report presents the data obtained by the Bureau of Mines exploration."

Dec 1, 1946

By Albert L. Toenges

This report is the second of a series describing methods and systems of mechanical mining; where operations are conducted on more than one shift. The first report, Information Circular 7014,4/ describes mining operations at 14 mines and the present paper describes operations at 11 additional mines. The purpose of this study is to analyze the advantages and disadvantages of the various types of equipment and mining systems now used where more than one shift is worked per day. Physical conditions vary in different and in the same mining districts and determine, together with economical considerations, the systems of mining and the types of mechanical loading equipment to be used. The information presented in this paper may be helpful to operators or others who may contemplate installing a mechanical mining system. The equipment used in the mines described comprises conveyors, scrapers, mobile loaders, mobile conveyors, and combination of these types. The description of the mining systems and practices at the mines investigated is detailed only as they relate to and affect mechanization. In computing the operating data in mines that are not totally mechanized, employees not working directly on production have been charged to output from mechanized sections in proportion to the percentage of mechanization. The operating data for comparing various systems are for an average working dry, as the number of men working on idle days varies greatly in different mines.

Jan 1, 1939

By John R. McWilliams

This is one of a series of reports being published by the Bureau of Mines on mining methods and costs at various mines throughout the United States. Including the Holden mine in this series is particularly appropriate at this time. The mine was operated on a low-cost, large-scale production basis to compensate for low-grade ore. Even with the best conditions and the most efficient methods, the margin of profit was small. Under the present situation of rising costs and lowering metal prices, the profit margin vanished. On June 28, 1957, the mine operations ceased; therefore, this report can review the entire life span of the mine.

Jan 1, 1958

By Horace C. Porter

Much has been written of the changes undergone by coal in storage and the deterioration of coal through exposure to the weather. In order to obtain definite information for the benefit of the Government departments and of all who store coal in large quantities, a series of tests was begun in the fall of 1909 under the supervision of J. A. Holmes, then chief technologist of the United States Geological Survey, and was continued by the Bureau of Mines after its establishment in 1910. The tests were confined to determinations of the loss in heating value of the coals and did not include a study of other deterioration; for example, in coking quality or the yield of by-products in coking. The Bureau of Yards and Docks of the Navy Department cooperated in tests of New River (W. Va.) coal, a variety largely used by the Navy. A preliminary report presenting a brief account of the early results of these tests has been published by the Bureau of Mines as Technical Paper 16.a The detailed report is presented in this bulletin, which gives a full account of the tests and the analytical data covering a period of five years' storage. Data of somewhat similar experiments for shorter periods with gas coal from the Pittsburgh bed, with Pocahontas coal on the Isthmus of Panama, and with Sheridan, Wyo., subbituminous coal, which is used for railroad and other purposes in the West, are included.

Jan 1, 1917