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By William J. Campbell

These investigations were undertaken as part of a program to determine the optimum X-ray spectral lines to use for analyzing the wide variety of samples received by the X-ray Laboratory. Theoretical calculations and experimental data derived from these investigations show that longer wavelength spectral lines, > 2A, are very useful for many analytical problems. Because of the low fluorescence yield of the elements of atomic numbers 13-22 and the small depth of penetration of their X-ray spectral lines, these elements were originally considered to be insensitive; however, these studies show that the wide dispersion of their spectral lines, coupled with their weak beta lines, permits the use of wide collimation, thus increasing the line intensity. More importantly, the background due to scattered primary radiation is very low in the long-wavelength region.

Jan 1, 1959

By John B. Gayle

During studies of the various methods for determining and specifying the factors that indicate whether a particular coke is better or worse than other cokes for metallurgical uses, questions arose as to the precision of screen-analysis tests on coke. Although the usual index of precision, the standard deviation of the test result, gives a measure of the precision of these data, the experimental determination of the standard deviation for a particular set of conditions requires tests on a large number of duplicate samples. Because this procedure necessaily involves a great deal of labor, an equation for predicting standard deviations from theoretical considerations has been developed. Results predicted with this equation agree satisfactorily with the experimental values and are applicable to tests on coal, coke, gravel, and other bulk materials.

Jan 1, 1952

By Frederick K. Allgaier

This is the first in a series of progress reports on the longwall subsidence research program at the Bureau of Mines Denver Research Center. As part of this program, the Bureau and the Utah Power and Light Co. are cooperating on a study conducted at the Deer Creek Mine, which is directed toward developing the capability to estimate the surface subsidence resulting from longwall mining in a geologic, topographic, and mining environment common to coalfields in the Western United States. A monitoring network has been established at the Deer Creek Mine to measure subsidence over four adjacent longwall panels. To date, two panels have been mined. Subsidence began as the first panel was mined and continued for 1 year following completion of the panel, during which time the adjacent panel was mined" A maximum of 2.7 feet of subsidence occurred over the two longwall panels mined at a depth of 1,500 feet. Because of the length of time that subsidence continued after mining, the final subsidence profiles and angle of draw have not yet been determined.

Jan 1, 1982

By Otis E. Perkins

This paper is one of a series being prepared for the United States Bureau of Mines to disseminate technical information retarding the methods used in mining nonmetallic minerals. The cost tabulations represent operating expenditures only and not total costs. It is recognized that publication of total costs might in many instances cause embarrassment to individual operators as well as to the industry as a whole. On the other hand, operating costs are essential to the technical discussion and study of the methods employed. The attention of the reader is specifically called to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. This paper deals particularly with methods and costs of dredging, classifying materials, and transportation at the plant of the Ross Island Sand & Gravel Co. of Portland, Ore. ACKNOWLEDGMENTS The author wishes to acknowledge the assistance of Harold Blake, general manager of the company, and of A. V. Kramer, cashier in charge of the plant office.

Jan 1, 1933

By Charles E. Munroe

At the outset of the war the uncontrolled production and possession of explosives obviously became a serious menace to the safety of persons and property and the successful conduct of military opera- tions. Even in the years immediately preceding the entrance of the United States into the Great War explosives were employed in attempts to wreck munitions plants as at Eddystone, Pa., or to inter- rupt transportation and conveyance by demolition of munition-laden cars as at Black Tom Island, N. Y., or by attacks on ships, bridges, and viaducts. Outrages with explosives, such as that which Holt inflicted on the Senate reception room, United States Capitol, were not infrequent, and often caused serious loss of life and injury to persons as well as destruction of property. The regular manufacturers of explosives were keenly alive to this menace and early took such steps as lay within their power to meet it as is shown by the following letter:

Jan 1, 1921

Objective: To identify and evaluate a durable, flexible, and practical stopping to direct ventilation airflows in large-opening metal/nonmetal mines.

May 1, 2006

By J. W. Eckerd, W. S. Sanner, P. L. Woolf, R. E. McKeever

The Bureau of Mines experimental blast furnace was operated successfully with anthracite metallurgical briquets . Tuyère pressures were higher and more erratic than for operations using coke , and furnace " hangs " occurred more frequently . Higher hot - blast temperatures were required to maintain the quality of the metal . By using higher hot blast temperatures , the fuel and production rates and slag volumes were comparable to those obtained for all - coke operation . The anthracite metallurgical briquets exhibited excellent mechanical strength and descended through the shaft of the furnace with little breakage or reduction in size .

Jan 1, 1964

The method of using large-diameter augers to recover coal was introduced to the mining industry about the end of World War II, and production of bituminous coal with augers has increased steadily to an estimated 7 million tons, or approximately 1.4 percent of the total mined in 1956. Although auger mining has proved to be a reliable and economical method of mining coal, a number of unfortunate fatal accidents have been experienced; consequently the need for these recommended safety standards is indicated for this comparatively new method of coal mining. As mining methods and equipment change from time to time and new hazards are introduced, these standards will be revised; therefore, questions or suggestions from the coal-mining industry will be welcomed and carefully considered.

Jan 1, 1958

By L. B. Pankratzt

The heat content above 298.15° K of ferroelectric lithium columbate (LiCbO3) was measured to 1,770° K. The Curie temperature was determined to be 1,450° K, the melting point 1,540° K, and the heat of fusion 16.94 kcal/mole. Heat content and entropy increments have been tabulated for the temperature range from i98.15° to 1,800° K. Heat contents are also given in equation form.

Jan 1, 1966

By S. L. Windes

For a number of years, the Bureau of Mines conducted tests on various types of structures to determine the effect of seismic vibrations emanating from quarry blasting in an effort to determine an index of damage . Associated with these tests , occasional records were made of the characteristics of. the air blast or concussion from the explosions . Although the importance of the air - blast problem was recognized , the equipment was not designed for air -blast measurements , nor was the early research program concerned with the problem . After the ground - vibration tests had been completed , attention was turned to study of the air blast and its effect . The air - blast problem in reference to quarry and mine blasting may be divided conveniently into three phases : (1 ) Determination of the fundamental characteristics of the air blast , such as the pressure - time relationship , speed of propagation, attenuation , and the like ; ( 2) effect of blasting conditions on these air -blast characteristics ; and ( 3) determination of the conditions necessary for damage to structures . The initial step was the development of microphones suitable for recording the anticipated blast pressures. Such microphones were designed and built during 1940 , and described in technical detail for publication ( 2)3/. Briefly, the microphone adopted was a small, plate - diaphragm condenser type . The recording was through special transducer amplifiers with low -frequency response to zero cycles per second and a Duddell - type oscillograph of special design .

Feb 1, 1942

By E. G. Davis

Under a memorandum of agreement with Reynolds Metals Co., Richmond, VA, the Bureau of Mines studied the problem of corundum formation on refractory linings in aluminum recycling furnaces. A laboratory test was developed for evaluating refractories in contact with molten recycled aluminum and identifying the mechanism of corundum formation. A test apparatus was designed and constructed to evaluate the performance of refractory samples. Corundum mechanism formation studies indicated that corundum formed on refractories when there is metal penetration. Once corundum forms, it acts as a wick allowing the molten aluminum to move to the surface where it is oxidized, thus causing further growth of the corundum. Phosphoric acid treatment or a spinel mortar coating prevented corundum formation on the 70-and 90-pct-A1203 refractories.

Jan 1, 1988

By Jean M. Kenney

Frequencies of haulage-related accidents in metal and nonmetal surface mines for the years 1988 through 1990 were investigated and compared with those of non-haulage-related accidents. This study was part of the U.S. Bureau of Mines program to improve mining haulage safety. Data were obtained through the U.S. Bureau of Mines Accident Data Analysis (ADA) program. The chi-square test was used to compare frequencies of haulage-related and non-haulage-related accidents for each of the following variables: degree of injury, age, total number of years of mining experience, and shift time. Significance was determined for degree of injury between haulage-related and non-haulage-related accidents. Age of injured did not vary significantly between haulage-related and non-haulage-related accidents, but total number of years of mining experience was found to be significant. Shift time for the accident proved to vary significantly between haulage-and non-haulage-related accidents. Events causing injury for haulage-related accidents were tabulated, and the most frequent determinants of haulage-related accidents were identified. Accident descriptions for both fatalities and permanent disabilities were studied, and the primary causes of these accidents were identified. These findings suggest that haulage-related jobs are among the most dangerous when considering accidents experienced by all workers in the metal and nonmetal surface mining work force.

Jan 1, 1993

By L. J. Kane

Applications are described of various methods for determining the weight concentration and physical properties of solid and liquid impurities of gases in connection with problems encountered in synthesis-gas production. Of special interest among these methods may be listed: 1. A method developed for determining, the weight concentration of solid and liquid impurities in. hot, crude synthesis gas containing a high concentration of moisture. 2. A method developed for the same purpose but for highly purified synthesis gas or atmospheric air. 3. A method for obtaining a uniform dispersion of dry duet or, a microscope slide for particle-size determination or other purposes.

Jan 1, 1954

By K. A. Fowler, L. W. Higley

The effect of uranium on the transformation kinetics and the hardenability of a low- alloy steel was evaluated . Isothermal transformation curves were developed from metallographic studies , and hardenability was determined by standard Jominy end- quench tests . For the steels investigated , the addition of 0.15 weight- percent uranium was found to produce a significant shift in the isothermal transformation curve and caused a related increase in hardenability . These effects diminished rapidly when the uranium content was increased above 0.2 weight - percent .

Jan 1, 1964

By H. L. Gibbs

A portable radon monitoring instrument capable of making on-the-spot measurements of the radon gas content of uranium mine atmospheres was designed and constructed. The monitor was tested in the laboratory and in operating uranium mines. Good correlation was obtained between the monitor readings and radon measurements made on mine atmosphere samples taken in radon bottles.

Jan 1, 1973

By D. Harrington

In recent years over 100,000 persons have been killed annually in the United. States by accidents; about one-fifth of these have been workers in some of our industries; about one-third have been killed by motor vehicles; about another third have mot death in home accidents, chiefly falls, burns, scalds, explosions, poisons, asphyxiations, suffocations, cuts, scratches, and so forth; and the rest have been killed in public accidents, excluding those caused by vehicles but including accidents on railroads or electric cars, drowning, and deaths by firearms and. other means. Definite statistics on nonfatal accidents are not readily available, but at least 10,000,000 fairly serious accidents probably occur in the United States annually. The latest industrial-accident statistics are obtainable from 1935 National Safety Council publications, in which annual industrial fatalities are divided about as follows (in round numbers): Agriculture, 4,500; trade and service, 4,500; construction, 3,100; transportation and public utilities, 2,900; manufacturing, 2,600; mining, quarrying, petroleum, etc., 1,900.

Jan 1, 1938

By S. L. Ausmus

The work covered in this report is a continuation of an earlier feasibility study by the Federal Bureau of Mines and points out improvements in the skull-melting method for casting reactive metals such as titanium, zirconium, and hafnium. Machined graphite molds with laminated sections can be reused many times. Large tube sections can be produced by spin casting. Graphite powder is the best expendable mold material, but binders for this use must be compounded carefully. The effects of current and furnace atmosphere on the dependent variables of the casting technique are shown. Because of developments in casting technology for titanium which eliminate the basic problems of melting and pouring the metal, opportunities for improvement in the method have increased. The mold material and gate and riser configurations require particular attention. The limits of application of the casting method have yet to be defined. New knowledge in anyone of these areas could result in marked improvements and simplifications in casting methods.

Jan 1, 1960

By Charles D. Litton

This U.S. Bureau of Mines report details the results of a series of large-scale experiments where small coal fires were used to ignite the conveyor belt at air velocities ranging from 0.76 to 6.1 m/s. In the tests, electrical strip heaters imbedded within a pile of coal were used to heat the coal to a point of flaming ignition. The flaming coal subsequently ignited the conveyor belt located approximately 5 to 10 cm above the coal pile. During the tests, temperature, CO, and smoke levels were continuously measured in order to determine both alarm time and level as the fire intensity progressed through the stages of smoldering coal, flaming coal, and flaming coal plus flaming belt. Analysis of the data leads to certain conditions of air velocity and sensor alarm levels that are required for early detection of conveyor belt entry fires. Two nomographs are presented, which define sensor alarm levels and sensor spacings as a function of belt entry cross-sectional area and belt entry air velocity.

Jan 1, 2010

By Danny Hagood

The drilling of horizontal boreholes as a means of degasification in advance of mining has been tried at Jim Walter Resources, Inc., No. 4 Mine. In a joint venture with the U.S. Bureau of Mines, a series of horizontal drainage boreholes have been drilled in the panels of an advancing continuous miner section with impressive results. The combined methane gas production rate has ranged from 205,000 to 680,000 cfd (cubic feet per day} with individual "in-seam" horizontal holes producing up to 332,000 cfd. The methane liberation from the ribs for the entire panel length has decreased from an average of 8.75 cfm (cubic feet per minute) per 100 feet of entry to 4.05 cfm per 100 feet, a 54 per cent reduction. The actual gas concentration as measure at the surface discharge point normally ranges from 85 per cent to 95 per cent methane. As a consequence of the significant reduction in methane liberation rates from the panels of the section, a 50 per cent increase in productivity from the section has been realized.

Jan 1, 1983

By B. J. Scheiner

Extraction of silver from silver mill tailings by an electrolytic oxidation procedure was investigated by the Bureau of Mines. Various parameters affecting silver extraction, such as electrolysis time, particle size, and dissolution of the silver as the tetrachloro or cyanide complex, were studied at 30° C with an electrolyte concentration of 20 weight-percent sodium chloride. Resulting silver extractions ranged from 77 to 90 percent, depending on the tailings being treated. Concomitant extraction of mercury ranged between 90 and 95 percent. Power consumption was 52 to 90 kilowatt-hours per ton for the tailings investigated. Comparative experiments using direct cyanidation resulted in extraction of 46 to 82 percent of the silver and 20 percent of the mercury. Cyanide consumption ranged from 3.3 to 9.4 pounds per ton of tailings, depending on the tailings being treated. Silver and mercury were recovered from leach solutions by precipitation on iron powder, followed by conventional distillation and fire refining steps.

Jan 1, 1972