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By Lloyd A. Morley

A guide to the development and use of an APL computer program for the analysis of load-flow problems is presented. The program is designed to provide an interactive method of load-flow study to improve underground coal mine electrical system design and safety. The theoretical basis for load-flow analysis is discussed, along with per-unit calculations which facilitate computation. Specific input/output, execution and network modification procedures are presented for using the APL program. In addition, typical results are given for examples taken from power system analysis literature.

Jan 1, 1977

By Joseph F. Davies

Along with the humanitarian need for preventing accidents the cost of injuries must be considered. As a means of bringing the facts concerning the prevalence of accidents in mining and their direct cost before the operating officials and others interested in accident prevention in the mining industry, the United. States Bureau of Mines ha as recently made studies and published reports dealing with these subjects in several States 4. This report gives available data on the causes and direct costs of accidents in Virginia coal mines for the 4-year period 1929 to 1932, inclusive. Mounting compensation costs and insurance rates resulting from mine injuries indicate the necessity of measures to decrease the number and severity of accidents. These direct costs, as well as additional losses of an indirect nature, can be eliminated from the cost of production to the extent that accidents are prevented or reduced in severity.

Jan 1, 1934

By D. J. Singleton

Erosion corrosion of 12 alloys in phosphoric acid waste water was studied by the Bureau of Mines. Tests were conducted on oblate spheroids or cylindrical specimens in 12-and 60-cm-diam ball mills by grinding phosphate rock in gypsum pond water with a starting pH of 1.6. For comparison, tests were conducted while grinding phosphate rock in plain water. Static corrosion tests in gypsum pond water also were conducted. For all alloys, the wear by erosion-corrosion (milling with gypsum pond water) was greater than the sum of erosion (milling with water) plus static corrosion. Erosion-corrosion wear was about 1,500 to 3,000 mpy for the alloyed white cast irons, 1,000 to 1,400 mpy for commercial steel ball material and type 316 stainless steel, and 600 to 900 mpy for nickel-base alloys and a high-manganese, nitrided stainless steel. Alloy costs per unit of phosphate rock 'processed favor a low-alloy, high-carbon steel or a high-manganese, nitrided stainless steel.

Jan 1, 1985

By J. W. Town

Studies were made by the Bureau of Mines to determine the influence of textural features on the beneficiation of phosphate minerals (pellets) from selected bed and composite samples representing different rock types of the Western Phosphoria Formation. The particle size of the samples was reduced by attrition grinding to minus 20-, 28-, or 48-mesh depending on ore grade and gangue matrix. Sizing of the ground material showed that the phosphate pellets would concentrate in the plus 200-, 270-, or 325-mesh size fractions sufficiently so that the phosphate content was above the 31.5 :cent P2O5 required for acidulation. The phosphate content of essentially pure phosphate pellets was shown to range from 33 to 39 percent P2O5. Microscopic identification of the particles in each size fraction showed that the phosphate was either in the pellet form and readily liberated or so intimately associated with the gangue matrix that size reduction necessary Co obtain liberation was impractical.

Jan 1, 1967

By M. B. Boyer, C. H. Herty, F. A. Hartgen, G. L. Frear

"DEFINITION OF VISCOSITYViscosity has been defined as the resistance experienced by one portion of a liquid moving over another portion, such as one molecular plane moving over an adjacent plane. A measure of viscosity is the force required to keep one plane in motion at Unit velocity, the other plane being considered stationary. Figure 1 illustrates the general idea that the surface friction between two adjacent areas will be greater the larger the molecules. Therefore it may be assumed that viscosity will be increased by molecular association or agglomeration, and likewise dissociation rill decrease viscosity. According to Maxwell (1)6 the unit of viscosity, the poise, is the tangential force per square centimeter of area of either of two horizontal planes 1 centimeter apart, one of which is fixed while the other moves with unit velocity, the space between being filled with viscous liquid of unit viscosity.The need for a satisfactory apparatus and experimental procedure for the determination of viscosity of high-melting materials at temperatures corresponding to those in pig-iron and steel making has been recognized during the past few decades. The condition of the slag during the smelting and refining periods in the iron- and steel-making processes exerts an important influence on the metal product obtained, this slag condition really meaning the state of viscosity or, vice versa, fluidity, which the slag attains under certain conditions."

Jun 1, 1934

By Charles R. Harrison

The purpose of this study and resulting development of the training program, "Safety--Let's Make It Happen" was to determine the relation of concepts to the development of desired Health and Safety behavior. After extensive pre-contract study, it was hypothesized that improved acceptance and understanding of the Federal Coal Mine Health and Safety Act of 1969 could possibly contribute to the reduction of accidents. Second, in order for an individual to accept and understand the Act, he or she must have a working knowledge of its purposes and application. Third, acceptance and understanding of the Act, necessary to protect the individual from negligence, was imperative. Fourth, an actual operating company could provide the base in which to test these hypotheses in a meaningful manner and develop this type of training program. Six assumptions were agreed upon before embarking on this study and training program development. (1) In the cognitive process, a concept introduction into an individual's personality may result in a behavior quite different than if he or she had been exposed to a different concept.

Jan 1, 1977

By N. E. Hanna

Originally developed for use in coal mines where on-shift blasting with explosives was prohibited, compressed-air blasting has been used for the past 15 years as a substitute for fixed explosives. With the current commercially available compressed-air systems -Airdox and Armstrong -coal is dislodged by a high-pressure discharge of air from a pressurized shell placed in the coal borehole. In the original systems stationary compressors were mounted on the surface or in the underground ventilated areas. These proved so successful that a mobile compressor unit was developed for use at the working face. Because of the possibility that such a unit might operate in a gassy atmosphere, the Bureau of Mines has investigated the hazards associated with operation under conditions where firedamp could accumulate in explosive concentrations. ACKNOWLEDGMENTS Grateful acknowledgment is made of cooperation of C. E. Carter, H. R. Hiller, R. E. Kennedy, H. Kohn, H. D. Metzinger, J. Mahoney, J. Nickovich, G. So Scott and I. Spolan in the experimental work.

Jan 1, 1956

By M. A. Elliott, F. W. Brown

"INTRODUCTION During the recent war the Bureau of Mines, at the request of one of the armed services, investigated the hazards that night be encountered 5n handling perchloric acid, particularly if spilled on certain materials. The hazardous nature of perchloric acid when mixed with reducing agents had been known qualitatively, but it was desired to obtain quantitative data on the explosion hazards of such materials. Accordingly, tests were made to determine the sensitivity of mixtures of perchloric acid and oxidizable materials to initiation by heat, impact, sparks, flame, and explosive impulses. This report summarizes the results of those tests.PROPERTIES OF PERCELORIC ACIDAnhydrous perchloric acid is a colorless,hygroscopic, volatile, mobile liquid that fumes in the air. The anhydrous acid is unstable at ordinary temperatures, and therefore the commercial acid is a water solution containing either 60 percent or 70 percent by weight of the anhydrous acid. The commercial acid is widely used in chemical analysis, frequently to oxidize organic material. If proper precautions are not observed, such an oxidixation may become exceedingly rapid and result in an explosion. Several such explosions involving the acid are mentioned in the literature. 4, 5, 6/"

Jan 1, 1948

By K. J. Maggs

The U.S. Bureau of Mines has investigated the chemical vapor deposition of diamond films on tungsten substrates. The effects of deposition parameters on the adhesion of the films was determined. The films were produced using a hot filament chemical vapor deposition system. Parameters investigated were substrate temperature and methane concentration in the feed gas. Film quality, morphology, and composition were characterized by scanning electron microscopy and Raman spectroscopy. Adhesion testing was performed using an indentation technique, and the results were quantified by relating adhesion to interface fracture toughness. Diamond films with well-faceted crystalline morphology with grain size greater than 1 µm had poor adhesion properties regardless of substrate temperature or methane concentration. Diamond films with smooth morphologies consisting of rounded clusters of small (<0.2 µm) diamond crystallites and amorphous carbon phases displayed much higher adhesion, although the conditions that led to the growth of these films are not understood.

Jan 1, 2010

By John Furness Park

This paper, which describes the mining methods and practices at the Jarbidge mines of the Elkoro Mines Co., is one of a series of papers being issued by the United States Bureau of Mines on mining methods and costs in various districts throughout the United States. LOCATION AND HISTORY The Elkoro Mines Co.&apos;s property is located at Jarbidge in the northeast corner of the State of Nevada (fig. 1). The camp is 9 miles south of the Idaho line; the nearest railroad point is 70 miles to the northeast at Rogerson, Idaho. A road leading to the south and connecting with Deeth, Nev., is passable during the summer months; the heavy snowfall which generally takes place early in the winter usually closes the road until the first of July.

Jan 1, 1931

By Gerhard Braüner

The report gives a review of the methods of predicting mine subsidence; these methods are used particularly in European coalfields. The methods are subdivided into two groups, based on mathematical expressions either for the trough profile or for the influence of infinitesimal extraction elements. The fundamental relationships common to all methods described herein are the principles of superposition and of equivalent extraction areas. The involved parameters are derived from field observations. For calculating horizontal displacements, their relation to the slope of the subsidence profile is applied. The time-dependent development of the subsidence process is characterized by the empirical "time factor." Modifications for the case of inclined strata are considered. A brief review of experimental and theoretical model investigations is given.

Jan 1, 1973

By A. C. Johnson

The T. L. shaft of the Eureka Corp., Ltd., near Adams Hill, Eureka, Nev., was sunk in 1954 and 1955 to permit exploration and development of the lead-zinc-silver ore that had been indicated by drilling. This paper describes the sinking of the 4-compartment, vertical shaft to a depth of 1,127 feet and includes pertinent details of equipment, methods, and costs. A shaft crew of 10 men, supplemented by 13 hoistmen, topmen, carpenter, and shop crewmen, sank and timbered the 1,127 feet of shaft in 630 workdays. Total labor per foot of shaft was 107.95 man-hours. Supplies per foot of shaft included 20 pounds of explosives, 1.61 pounds of drill steel, and 200 board-feet of timber. Power consumption, including that required for pumping, averaged 3,726 kw.-hr. per foot.

Jan 1, 1958

By V. F. Parry

[Approximately 7-1/2 million tons of subbituminous coals are mined annually in Colorado, Wyoming, and Montana, of which 50 percent probably reaches domestic consumers. The moisture of these subbituminous coals is high, averaging about 25 percent when they are mined. The coals are non-caking end stack to a variable degree when exposed to normal atmospheric conditions. They are good domestic fuels, are considered to be smokeless in most furnaces, and have been used for many years in hand-fired domestic furnaces in which the practice is to employ large lutes for efficient combustion.]

Jan 1, 1941

By Ruth F. Brinkley

Principle activities of the Bureau of Mines Explosives Research Laboratory from July 1, 1960 to June 30, 1961 are reviewed briefly in Part 1. Part 1 also includes data obtained in connect ion with several minor investigations which are not sufficient to warrant separate publications. Part 2 gives brief abstracts of publications that appeared during fiscal year 1961; in general, the research reported in these publications antedates this period.

Jan 1, 1963

By Oliver Bowles

In 1943 the Bureau of Mines began a review of trends in consumption and prices of the more important nonmetallic minerals. The first report covering building materials4/ appeared in December of that year. The present paper, which deals with chemical raw materials and fertilizers, is the second of the series. The 34 years from 1910 to 1943, for which statistics are presented herein, comprise periods of uneventful peace, unparalleled prosperity, industrial depression almost to the point of stagnation, and two wars of world proportions.

Jan 1, 1945

By Robert M. Cox

The U. S. Bureau of Mines (USBM) MULSIM/NL modeling technique has been used to analyze anticipated stress distributions for a proposed alternative longwall gate road design for a western Colorado coal mine. The model analyses indicated that the alternative gate road design would reduce stresses in the tailgate entry without increasing stresses in the headgate entry. To test the validity of the alternative gate road design under actual mining conditions, a test section of the alternative system was incorporated into a subsequent set of gate roads developed at the mine. The alternative gate road test section was instrumented with borehole pressure cells, as part of an ongoing USBM research project, to monitor ground pressure changes as longwall mining progressed. During the excavation of the adjacent longwall panels, the behavior of the alternative gate road system was monitored continuously using the USBM computer-assisted Ground Control Management System. During these field tests, the alternative gate road system was first monitored and evaluated as a headgate, and later monitored and evaluated as a tailgate. The results of the field tests confirmed the validity of using the MULSIM/NL modeling technique to evaluate mine designs.

Jan 1, 2010

By J. H. East

"INTRODUCTION .Very little information regarding coal mining in Spain has been published in the American technical press, and few people realize the extent of this industry or the conditions under which coal is mined. The information in this publication was collected in 1945 and consists of personal observations in Spain, statistics, and other data of a, general nature obtained from official sources.Spain produces bituminous coal, lignite and anthracite, but the total tonnage mined is less than the national requirements. Before the war, an appreciable tonnages coal was imported from Great Britain under the Anglo-Spanish treaty, which rebated import duties and effectually prevented competition from any other foreign source. The war stopped the major part of the important of British coal and caused rapid expansion of the domestic sources, but this was not sufficient to supply the industrial demand. Coal that formerly was not acceptable to industry because of quality is now mined and marketed. The Government, allocates the better-grade bituininous coal to the various industries in accordance with the national importance of the work in which they are engaged; for example, the railroads are allotted 100 percent of their requirements, but cement companies can obtain only 25 percent.The Government offered to inducements to increase the production of coal of any class, but the larger part of the increased tonnage obtained was in inferior grades; as a result, the lignite production was taxed, while a bonus was paid for bituminous-coal production in excess of the 1942 tonnage.The anthracite and bituminous-coal areas were severely damaged during the Civil War and many experienced miners migrated to the lignite mines in eastern Spain. This has resulted in an acute shortage, particularly the Province of Oviedo where the most important bituminous-coal deposits are located."

Jan 1, 1947

By A. C. Johnson, McHenry Mosier

The Bureau of Mines has adapted its activities to needs of national defense and to conditions brought about by the war program . Its work is now oriented solely to war problems . After studying about 1,600 deposits of war minerals , exploration projects have been undertaken on 96 of the most promising , of which 56 have proved successful . These have indicated that 56 million tons of ore of commercial or near -commercial grade can be utilized to meet war requirements . Included in this amount are 1 million tons of tungsten ore ; 4 million tons of chromite ore, 10 million tons of manganese ore , 2 million tons of antimony ore , 1 million tons of mercury cre , and 28 million tons of iron ore . Work done in connection with exploration projects included 172,000 feet of surface trenching , 210,000 feet of drilling , and 21,000 feet of shaft sinking . Nearly 100,000 samples were taken, on which 500,000 analyses were made . Extensive metallurgical tests were made on ore from many of these deposits , both in the laboratory and in pilot plants , in connection with research to develop metallurgical processes for their treatment .

Jan 1, 1943

By A. H. Warner, G. A. Morrison

"INTRODUCTION The brown-iron ores of the Western Highland Rim of Tennessee extend north and south across the State for 115 miles. Many prospects of iron ore are known in this area.The district is credited with an output of 8 million tons of washed ore prior to 1930. Records on past shipments of ore indicates that the grade was probably 45 to 50 percent iron, 0,7 to 1.25 percent phosphorus, and 10 to 21 percent insoluble.As part of a survey of the iron resources of the Appalachian area, the Bureau of Manes began exploration .of the Churchwell and Robinette properties April 16, 1945, and continued until July 25, 1945, during which time 122 feet of test pits were sunk and 667 feet of churn drilling was completedPROPERTY AND ACCESSThe Churchweil property and that part of the Robinette tract north of U. S. Highway 64 are reported to be owned by the heirs of William Millsaps.The Churchwell property is northeast of Waynesboro, the county seat of Wayne County (fig. 1), and is east of Forty-Eight Creek, between Duggar Branch on the north and Little Forty-Eight Creek on the south.The property is reached from Waynesboro by traveling U. S. Highway 64 east 8 miles to Forty-Eight Creek, thence north on a secondary road 2 miles, to where Little Forty-Eight Creek joins it, thence by an old logging road up the hill half a mile to the property.The Robinett tract lies 1 mile southeast of the Churchwell and is reached by traveling east from Waynesboro on U. S. Highway 64 and a distance of 6.7 miles, and then turning left on an old logging road and following the ridge 2 miles to the prospect."

Oct 1, 1946

By David A. Benjamin

The USBM (U.S. Bureau of Mines) studied mines, prospects, and mineralized sites in the Roberts WSA (Wilderness Study Area) in 1984. The 15,090-acre WSA, located 35 miles northwest of Eureka, NV, is underlain by alluvial deposits of Quaternary age, extrusive and intrusive volcanic rocks of Oligocene through Miocene age, and metasedimentary rocks of Cambrian through Permian age. The Roberts Mountain Thrust fault cuts through the WSA, dividing the metasedimentary rocks into upper and lower plate rock units. One mine, the Kelley, which produced 397 tons of lead-zinc ore prior to 1940, and two prospects are within the WSA; no resources were identified. Exploration for precious metal deposits is presently being conducted in and adjacent to the WSA on large claim blocks. The study area contains six sites in and near these claim blocks that have anomalous gold and silver. Detailed exploration is needed to delineate resources. High purity silica rocks are present in the WSA. Barite, phosphate, oil shale, and vanadium occurrences just outside the WSA may extend into it, but no such occurrences were observed during the USBM study.

Jan 1, 1986