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By Lars Osen

This investigation was undertaken to contribute to the understanding of underground pull tests by conducting laboratory tests under closely controlled conditions. Steel bolts, instrumented with electrical resistance strain gages, were anchored in an aluminum block, a granite block, and a steel sleeve, and were subjected to pull tests. The bearing plates used were either flat7 dished, or embossed. In pull testing a bolt that is prestressed, there is a range of loading during which bolt load is greater than the jack-applied load, This study showed that preload, the size, shape, and type of bearing plate; and the geometry of the system determine the point at which bolt load and applied load become equal. The effects on bolt load of both a theoretical solution and actual pull tests were analogous and led to similar results.

Jan 1, 1965

By M. J. Dailey

This paper is one of a series being prepared by the United States Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The property of the Silver King Coalition Mines Co. is situated in the western past of the Park City mining district, Utah, about 1 ½ miles southwest of the town of Park City, The elevation at the collar of the main shaft is 8,137 feet above sea-level.

Jan 1, 1930

By Michael J. Sapko, Samuel P. Harteis, Eric S. Weiss

The Pittsburgh Research Laboratory (PRL) of the National Institute for Occupational Safety and Health (NIOSH) recently conducted full-scale explosion experiments; these experiments evaluated the strength characteristics of various seal designs used for safely isolating worked-out areas in underground coal mines. Large-scale explosion tests were conducted within the multiple entry section of PRL’s Lake Lynn Experimental Mine (LLEM) employing the only currently accepted test method endorsed by the Mine Safety and Health Administration (MSHA) for seal design in American mines. These explosion tests are labor-intensive, expensive to conduct, and can interfere with other critical underground safety and health research programs conducted by NIOSH. Therefore, the PRL has developed an alternative seal evaluation method, based on a hydrostatic pressure loading concept, that can facilitate the in-situ testing of seals in an operating mine. Two chambers within LLEM and one within the Safety Research Coal Mine (SRCM) were used for hydrostatic pressure loading various seal designs. The results from tests in these chambers compare favorably with those from the large-scale explosion tests in the multiple entries. Preliminary size-scaling relationships for predicting the strength of standard seal designs as a function of entry size is also presented. In addition to testing seal designs at the required 20 psi static pressure level, the new facilities also allow for the determination of the seal’s ultimate failure pressure. This new approach shows promise as an alternative evaluation method for improving mine sealing technologies which, in turn, will enhance the safety of the underground personnel.

By W. E. Anable

The Bureau of Mines studied the purification of commercially available yttrium by melting it in a 100-kw electron-beam furnace. Button-scale melts were made to determine the ultimate purification that could be attained by melting yttrium at 1,733° to 1,770° C at low pressure (0.05 to 0.1 micron) for 1 to 120 minutes. In addition, numerous melts were made to study the effect of doping yttrium with carbon, 17 selected metallic additions, and 3 compounds. Except for nickel and zirconium, the metallic impurities in yttrium were lowered significantly on extended treatment; silicon was lowered only slightly. The nonmetallic impurities} oxygen, nitrogen, and carbon, were not lowered except on short exposures. In isolated instances, the oxygen content was lowered from 5,860 ppm to about 5,000 ppm. In most instances the carbon con-tent was lowered from 545 to about 220 ppm in 20 minutes and then increased again. It was concluded that yttrium cannot be purified by direct heating or by the doping technique employed.

Jan 1, 1965

By Oliver W. Keener

This paper describing the methods and costs of mining at the Hartley-Grantham mine of the Century Zinc Co. in the Tri-State Lead and Zinc district is one of a series being prepared by the United States Bureau of Mines can mining practices, methods, and costs in the various mining districts of the United States. LOCATION, HISTORY, AND GEOLOGY The Hartley-Grantham Mine is located just outside the city limits of Baxter Springs, Kans., as shown in Figure 1. A plan of the mine is given in Figure 2, and Figure is a cross section through A - A of Figure 2.

Jan 1, 1930

By R. V. Ramani, P. M. T. White, D. Sutton

1.1 General The examination and evaluation of a mineral deposit to determine whether or not it can be profitably exploited entails many factors unrelated to the physical nature and intrinsic worth of that deposit. Nevertheless, geology and geologically related factors have great bearing on the economic potential of the deposit. This is only natural because the deposit owes its existence to these factors. This is even more so in underground mines where the whole system is a geologically enclosed one. Geology plays a major role in at least four phases of a mineral venture. Firstly, it acts as an indicator of the existence of parti¬cular minerals. For example, it is inconceivable that a sedimentary coal deposit would exist in a granitic batholith or stock, or that a sandstone would host primary copper or nickel sulphides. Further, the positional relationship of different rock types may be significant in locating deposits such as replacement zinc and copper sulphides in limestones which have been intruded by igneous rocks. Thus, geology is important in the exploration phase of a mineral deposit. Secondly, once potentially valuable minerals have been discovered, knowledge of geology plays a significant role in determining the dis¬tribution, grade and extent of the mineralization. Controls on mineralization include one or all of those related to structure, rock type, sedimentary features, post-depositional redistribution, etc. Con¬sequently, in order to effectively evaluate a deposit in terms of

Jan 1, 1974

By Richard J. Mainiero, Marcia L. Harris, James H. Rowland

In the past several years, there have been a number of blasting-related carbon monoxide migration incidents. In each case, there have been some common factors that appear to be related to carbon monoxide migration. Geology, heavy confinement of the blast, close proximity to the affected structure, and open pathways into the affected structure are just a few. Prince William County, VA is an area undergoing a boom in suburban development. In the year 2001, more than 4,050 new homes were constructed within the county.1 In the new housing development located in Bristow,VA, trench blasting was utilized to excavate proposed sewage and utility lines. On November 8, 2002, a trench blast was conducted for the installation of utility lines. Later that evening a carbon monoxide detector alarmed in a nearby house. The gas company and fire department sampled for carbon monoxide and measured 100 ppm and more than 200 ppm on the first floor and in the basement respectively. Subsequent efforts to prevent migration of CO into the nearby homes met with mixed results. The only reliable technique for protecting neighbors from CO appears to be the placement of CO monitors in the homes. The events are presented and discussed.

By Gerald J. Joy, Paul J. Middendorf

This study examines the patterns and trends in noise exposure documented in data collected by Mine Safety and Health Administration inspectors at U.S. coal mines from 1987 through 2004. During this period, MSHA issued a new regulation on occupational noise exposure that changed the regulatory requirements and enforcement policies. The data were examined to identify potential impacts from these changes. The overall annual median noise dose declined 67% for surface coal mining and 24% for underground coal mining, and the reduction in each group accelerated after promulgation of the new noise rule. However, not all mining occupations experienced a decrease. The exposure reduction was accompanied by an increase of shift length as represented by dosimeter sample duration. For coal miners exposed above the permissible exposure level, use of hearing protection devices increased from 61% to 89% during this period. Participation of miners exposed at or above the action level in hearing conservation programs rapidly reached 86% following the effective date of the noise rule. Based on inspection data, the occupational noise regulation appears to be having a strong positive impact on hearing conservation by reducing exposures and increasing the use of hearing protection devices and medical surveillance. However the increase in shift duration and resulting reduction in recovery time may mitigate the gains somewhat.

By D. Harrington

An explosive may be defined as a substance (usually a mixture) that has the property of yielding, readily to combustion or oxidation upon application of flame or shock, the combustion or oxidation process being rapid and accompanied by formation of such relatively large quantities of gases that much violence and pressure are produced; these, in turn, react against their surroundings and cause what is termed an explosion. By their very nature their action is destructive and disruptive of adjunct materials; hence, all explosives axe potentially hazardous and every type of explosive, irrespective of its relative safety, should be handled, .stored, and used with utmost care at all times and under all conditions. It should always be remembered that any explosive can be rude safe only in certain of its features and under certain conditions and circumstance. If these facts (and they certainly are facts) are always kept in mind, most of the modern types of explosives can be utilized advantageously in our industrial life and with a considerable degree of safety. That commercial explosives can be handled. safely is borne out in part by the fact that in the past 15 years at least 3,000,000,000 pounds of the commercial explosive dynamite have been transported by railroads in the United State, without injury to any person, insofar as available records indicate.

Jan 1, 1939

By Leonard Greenburg

The analytical procedure necessary when using this new impinger•bubbler eil)paratus is almost identical with that em:r;,loyed with the Palm0r a:pp8.ratua. As sugar is not employei, the new apparatus por.;sesses the advantage over the eug.r tube method in having vsry low control errors, being, therefore, much simple in laboratory manipulation during analysis.

Aug 1, 1922

By Edward L. McHugh, Jami M. Girard

While less than 1% of reported accidents are associated with slope stability problems, slope failures were responsible for about 15% of all U.S. surface mine fatalities between 1995 and 2001. Small rockfalls, which may involve hand-sized rocks weighing only a few kilograms, can cause fatal injuries to workers away from the protection of large machinery. Massive highwall failures containing a million cubic meters of material or more can be fatal even for heavy equipment operators. As part of an ongoing study at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health, several remote-sensing technologies are being evaluated as tools to monitor slopes for hazards and to assess slope stability. Field tests of a hyper spectral imager were conducted to assess its value for improving geologic maps of potentially unstable alteration zones on mine slopes. An interferometric radar device capable of detecting very small displacements on slopes awaits final assembly and field testing. Computerized monitoring methods using images from digital and video cameras are being assessed for application to mine slope surveillance. These and other techniques will eventually provide new tools to augment current methods for monitoring ground control hazards in mines.

By Fred N. Kissell

A self-sealing brattice intended for use during coal mine rescue and recovery operations has been designed and tested by the Bureau of Mines. The major design difference between self-sealing and conventional brattice is that the fabric is cut and sewn BS a hemisphere instead of as a flat sheet. This new type of brattice offers reduced weight, leakage, and installation time. Preliminary testing indicates that the concept is worthwhile, but that further developmental research is required.

Jan 1, 1976

By L. Y. Sadler

The Bureau of Mines conducted a study Lo determine the loss in weight of silica (Si02) volatilization from low-alumina (A1203) refractories used as hot face liner materials in such process equipment as coal gasifiers, synthesis gas transfer lines, and ammonia plant secondary re-formers. Small specimens of 80-and 40-pct-A1203 brick and 95-pct-SiO2 brick were exposed to steam in high-pressure furnaces at pressures of up to 1,000 psig and temperatures up to 1,400° C for periods ranging up to 120 h. Weight losses from the 40-pct-A1203 brick after 40 h of exposure were highest, 2.75 pet at 1,400° C and 1,000 psig. The rate of weight loss had dropped to near zero after 80 h of exposure at all temperatures. No relationship between total silica content of the specimen and weight loss could be established nor did scanning electron microscopic examination of the specimens before and after exposure identify specific regions (e.g., surface) suffering a disproportionate share of the silica loss. It was concluded that minor silica volatilization is likely to occur, if at all, at temperatures of less than 1,000° C and pressures below 1,000 psig, and that low-alumina refractories should be used as dry-ash coal gasifier hot face linings.

Jan 1, 1986

By Murray Jacobson

The respirable dust standard in the Federal Coal Mine Health and Safety Act of 1969 is designed to prevent disability and death from coal workers' pneumoconiosis. Beginning June 30, 1970, the operators of coal mines were required to maintain the average concentration of respirable dust in the active workings at or below 3.0 milligrams of dust per cubic meter of air. The standard is reduced to 2.0 milligrams per cubic meter after Dec. 30, 1972. This paper presents the equipment and procedures used by the coal mine operators in implementing the respirable dust sampling program established by the Secretary of the Interior and the Secretary of Health, Education, and Welfare and shows the effect of the law, during the first year, on the reduction of dust levels in selected mines. The system employed by the Bureau of Mines for analyzing and processing the dust samples is also presented.

Jan 1, 1971

By L. O. Bacon

This Bureau of Mines report summarizes the results of laboratory work in the design of instrumentation for obtaining the dynamic tensile strength of rock at minimum loading. Minimum loading is defined as the lowest tensile loading by pulse reflection to cause fracturing. The instrumentation for obtaining dynamic tensile strengths of rock cores evolved into the use of a compressed-air pellet gun to impact one end of a rock core, suspended by wires, at increasing increments of air pressure. Maximum strain was measured on most or all of the impacts, and the strain at fracture of the core was obtained by extrapolating the pellet velocity-strain curve to the pellet velocity at fracture. Stress at tensile fracture was obtained from the maximum s train, and the dynamic Young's modulus was calculated from the rod velocity by using simple rod theory.

Jan 1, 1962

By E. D. Gordner

U. S. Bureau of Mines

Jan 1, 1923

By J. H. East, D. Harrington

Fires in metal mines have resulted in some of the worst disasters in American mining history insofar as loss of life is concerned. One fire caused the death of 163 miners and individual less spectacular fires have cost the lives of scores of workers. Metal mines are often very deep, and the men working on numerous levels far removed from direct communication with the surface. In many instances they cannot be warned quickly of an emergency or a mine fire by telephone or other usual method of communication, or by messenger, flashing lights, gongs, sirens, or whistles. Telephones are not paricularly effective as a means of warning unless placed at all strategic points and with attendants always on duty; though telephones well placed have a definite value in any well-pla.mied emergency procedure in mines of all kinds. Messengers are slow and men working in remote parts of a mine would not receive a warning quickly enough. Most metal mines are not electrically lighted, except at or adjacent to shaft stations and in principal haulageways, and this limits the effectiveness of flashing lights. Electric gongs and sirens or whistles have been tried as warning signals, but the sound is quickly deadened and does not travel upward into the stopes, especially those of an extensive volume. Shutting off the compressed air is by no means satisfactory as a warning, as not infrequently it is stopped accidently, so that it loses its value as an alarm. The introduction of water into compressed air lines is undesirable as a fire warning and necessitates considerable care, especially in deep mines; pressure-reducing valves must be provided to reduce pressure that otherwise would break connections or split the pipe. A quick, effective method of warning miners underground of the existence of an emergency requiring them to leave the mine immediately, such as a fire on the surface or underground, is provided by the introduction of stenches in the compressed-air lines. This method of warning is by no means experimental, inasmuch as it has been used successfully for many years in

Jul 1, 1943

Develop a new method for coal mint pillar stability evaluation and design based on pillar load measurements. Approach A novel approach to chain pillar stability evaluation and design for longwall coal mining panels has been developed by the Bureau of Mines. The evaluation approach uses an INTEGRITY FACTOR as the criterion for stability. Hydraulic borehole pressure cells developed by the Bureau are used to measure stresses in a pillar for stability evaluation. The results are used to improve the pillar design.

Jan 1, 1989

By Wm. O. Vanderburg

This paper describing the mining practices at the Block P mine of the St. Joseph Lead Co. at Hughesville, Mont., is ore of a series of similar papers being prepared by the Bureau of Mines on mining practices, methods, and costs in the various miner of the United States. ACKNOWLEDGMENTS In the preparation of this paper the writer acknowledges the assistance of R. H. Willcomb, general manager, William Thorson, mine superintendent, and B. P. Bellport, mining engineer, of the Hughesville division of the St. Joseph Lead Co.; and of E. D. Gardner; supervising engineer, U. S. Bureau of Mines, Southwest Experiment Station, Tucson, Ariz.

Jan 1, 1931

By H. P. Rue

For the proper control of gasoline treating plants there is need of a quick test for corrosion. In "sweetening" gasoline that is, in treating it to remove evil smelling mercaptans or to convert them to disulphides or sulphides the sodium plumbite ("doctor") method is generally used. This method involves agitation of the gasoline with "doctor solution's (sodium plumbite made by dissolving litharge in a solution of caustic soda) in the presence of free sulphur3. One of the common mistakes in the technique of this process is the addition of too much free sulphur, which will dissolve in the gasoline and cause it to be corrosive. In the operation of a continuous sweetening; or treating plant, a check on the corrosiveness of they product is imperative at all times. The copper-strip test commonly used in specifications take, so long to perform that the plant may fail to function properly for some time before the operator discovers it. The writer has investigated a rapid corrosion test method involving the use of metallic mercury, recently developed by Messrs. G. T. Granger, refinery superintendent, and A. B. Comstock, chief chemist, of the Barnsdall Refineries, Inc., Okmulgee, Okla. They have used this test successfully for several months in controlling the operation of their continuous treaters any have come to the conclusion that it has several advantages over the copper-strip test. Chief among these is the time caved, as the copper-strip test takes at least one-half hour, while the mercury test can be wade in about five minutes. It is very evident that this is an important item in controlling a continuous treater.

Jan 1, 1928