Search Documents

By Ralph H. Whaite

To assist the anthracite industry obtain technical data on pneumatic packing, the Federal Bureau of Mines imported a pneumatic packing machine from Germany and installed it in a mine of a cooperating company in the Northern anthracite field of Pennsylvania. This report covers the second in a series of experiments in applying pneumatic packing for controlling strata movement (subsidence) above mine workings in the Pennsylvania anthracite region. The first experiment2/ was begun in January 1950, in a section of the mine where about 50 percent of the original coal remained in the form of pillars; since the company did not plan to mine the pillars in this particular area, pneumatic packing of the chamber voids was done for test purposes only. During this initial test the machine was operated on 204 shifts, and 652,400 cubic feet of breaker refuse material (22,834 tons) was packed into the voids of 16 chambers. The work was completed in December 1951.

Jan 1, 1956

By D. R. Tesarik

To ensure the stability ofa tailings pond embankment, the height of the phreatic surface must be kept at or below a safe level. In this investigation, the Bureau of Mines analyzed various horizontal drain designs for tailings embankments to determine their effects on location of the phreatic surface. This report describes the investigation, and it includes 21 dimensionless graphs that can be used to estimate the drain spacing and length dimensions necessary to ensure the stability of embankments of various configurations. Analyses were based on the use of two computer codes, a three-dimensional finite-element code and a two-dimensional finite-difference code. The computer-generated results were compared with results obtained from a laboratory embankment model, other laboratory test results, and piezomet-ric data from two actual tailings embankments. Nearly the same phreatic surface locations were predicted using either of the computer codes. For one of the actual embankments studied, the predicted phreatic surface location was slightly higher than the measured location; for the other, the predicted location closely followed the actual surface trend. Phreatic surfaces of the laboratory model were slightly higher than the code-gener-ated locations, and the differences grew larger as drain length increased or drain spacing decreased.

Jan 1, 1984

By A. W. Decora

Gas-liquid chromatography has been applied to separating basic nitrogen compounds, such as pyridines and amines. Close-boiling compounds have been separated by exploiting structural and polarity differences, using selective liquid substrates dispersed on specially prepared solid supports. Development of these special supports was necessary in order to obtain symmetric peaks for basic nitrogen compounds; solution of this problem was important in applying gas-liquid chromatography to the analysis of basic nitrogen compounds found in shale oil. Attempts to analyze shale-oil tar bases by conventional gas-liquid chromatographic techniques, using Chromosorb4/ or Celite 545 as the support for a nonpolar liquid substrate, resulted in asymmetric peaks. These asymmetries were caused by adsorption of sample vapors on the solid support. Symmetric peaks were obtained when strongly polar liquid substrates were used on either Chromosorb or Celite. However, a solid support giving symmetric peaks only with strong polar substrates restricts the choice of substrate, and frequently, desired separations cannot be achieved.

Jan 1, 1961

By E. G. Davis

Large-scale ultrafine grinding tests of a coarse kaolin were made using the Bureau of Mines developed attrition grinding process in continuous open-and closed-circuit systems. A 20-inch diameter attrition grinder, designed and constructed at the Tuscaloosa Laboratory, was used. Studies included single- and multiple-stage open-circuit grinding, and also continuous grinding tests in closed-circuit with a 6-inch-diameter solid bowl centrifuge. Clay feed, containing 9.0 percent minus-2-micrometer esd, was used at fates up to 840 pounds per hour. Multistage grinding tests gave better results than single-stage treatment when equivalent clay feed rates were used. Closed-circuit grinding tests yielded ground products containing slightly more minus-2-micrometer-esd clay than the open-circuit grinding when using the same clay feed. Energy consumption was lower in closed-circuit grinding than in batch or open-circuit grinding. A modified two-stage closed-circuit grinding system gave the best grade of product and amount of minus -2-micrometer-esd clay produced per pound of clay feed. The ground product from this test contained 88.5 percent minus-2-micrometer-esd material and electrical energy consumption was 327 kilowatt-hours per ton of minus-2-micrometer-esd material produced.

Jan 1, 1973

By Frederick C. Trutt

A guide to the development and utilization of an interactive mine-power-system fault program (Z-bus by algorithm) is presented. Theoretical foundations, as well as implementation considerations are discussed with respect to the mine-power system. Alternative Kron reduction techniques are presented along with a triangular-storage method for storage conservation. Program capabilities include the analysis of balanced and unbalanced (line-to-line, line-to-ground, and line-to-line-to-ground) fault situations using symmetrical component theory. To account for phase shifting in delta-wye transformers and zero-sequence network constructions, transformer and load configurations are specified by the user. The positive-and zero-sequence connections needed for network conformity are automatically constructed with the required impedances.

Jan 1, 1979

By H. A. Doerner

"During the year which has passed since the last progress report on reduction of zinc by natural gas,3 the laboratory experiments on this investigation have been completed. In this concluding report, the whole subject will be reviewed and additional data presented.Chemical ReactionsIn a thermodynamic study of zinc smelting, Maier 4 discussed the use of methane for reducing zinc oxide, and predicted equilibria at various temperatures for the sore important reactions. The study has been extended to include the following list.Maier predicted that 870°C. would be the critical temperature above which reaction (1) would take precedence over reaction (2) and that reaction (1) at equilibria would be substantially complete at or above 927°C. A subsequent papers described experimental verification of these predictions and gave data on reaction rates under various conditions.It methane is passed through a heated bed of zinc oxide at a low enough rate reactions (1), (3), and (4) reach an equilibrium which can be expressed by reaction (10). The equilibrium concentrations for the products of this reaction in the temperature range 900° to 1100°C. were calculated by applying the thermodynamic constants to the stoichiometric relations. 6 The results of these calculations are listed in table 1 and shown graphically in figures 1, A and B. These data have major importance, and experimental work has shown that they are subtantially correct."

Dec 1, 1934

By Albert L. Toenges

The Grundy coal field is in process of development, and this circular was written to describe the mining methods and practices in use in the mines now being worked in this field. In lieu of man-hour labor data for individual mines a consolidated sheet of mine costs, which includes expenses for labor, material, and power, is given for all mines. The costs are for a working day only, based on average daily production. Because the demand for coal is seasonal, the costs for idle days, which vary at each mine, have not been estimated. Approximate reserves of coal seams have been estimated from data and maps taken from Bulletin XVIII of the Virginia Geological Survey4/.

Jan 1, 1936

By Harry H. Ku

In December 1975, a report entitled "An Evaluation of the Accuracy of the Coal Mine Dust Sampling Program Administered by the Department of Interior" [1] was prepared by the Analytical Chemistry Division of the National Bureau of Standards (NBS), in response to a request by Senator Harrison A. Williams. Chairman, Committee on Labor and Public Welfare. The report attempted to evaluate the adequacy of (1) the personal sampler unit used to measure the coal dust concentration in the mines, (2) the procedures used by the Department of Interior (DOI) to analyze the dust samples obtained from mine operators, and (3) any recent studies made by the Department or private industry concerning the coal dust sampling equipment. Recommendations in the report of NBS included continued research efforts by the appropriate organization to correct the personal sampler deficiencies and to consider the use of area or stationary samplers as a supplement to the personal samplers. Concurrent with the NBS report cited above, the General Accounting Office (GAO) also issued a report in December, 1975 [2], suggesting that improvements are still needed in coal mine dust sampling programs and procedures relating to penalty assessments and collections. Among recommendations made by GAO, the following paragraph specifically called for actions by the agencies involved:

Jan 1, 1979

By L. A. Stinnett

An investigation of hazardous surface openings of abandoned and inactive underground mines in the Black Hills area of South Dakota has revealed: (1) tracing legal ownership of mineral claims via county courthouses is confusing, complex, and oftentimes misleading, (2 ) in general, the selected mine openings in this investigation are to be considered relatively high in risks and hazard potential which poses a threat to the general public, (3) mine closure procedures and designs can generally be categorically implemented depending on the overall situation of the particular mine opening with subsequent unit costs' estimates, (4) few preventive state or federal legal measures exist to date concerning mine closures, and (5) liability damages relating to mine opening accidents usually involve expensive and complex common law cases.

Jan 1, 1979

By L. C. Brichta

The Tri-State zinc-lead catalog, compilation of which was initiated by the Bureau of Mines in August 1949, is designed to provide a continuing record of avail-able drill-hole logs and maps of mine developments in the zinc-lead district in southwestern Missouri, southeastern Kansas, and northeastern Oklahoma. The maps and data thus preserved constitute a reservoir of factual information readily available to individuals and firms interested in planning mineral explorations, to Government agencies for formulating estimates or ore reserves, and to the mining industry in the district for general uses. The areas to be included in the catalog embrace the explored and mined tracts within 760,000 acres of the more active western part of the district. The consensus among local mine operators, geologists, and mining engineers is that over 100,000 boles, costing more than $30,000,000, have been drilled in the district. Records of some of the early drilling and mine developments are destroyed or lost, but the Bureau of Mines has copies of about 47,500 drill-hole logs and is accumulating and recording on microfilm those that are currently available. As of May 1, 1954, the logs of approximately 28,000 drill holes had been microfilmed and are available for inspection at the Bureau of Mines office, Joplin, Mo.

Jan 1, 1955

By W. W. Adams

The first full year of the second World War for the United States presented a picture of the metal-and nonmetal-mining 4 industry which, without proper analysis and explanation, would convey a distorted view of achievements during 1942, especially because employment at gold and silver (lode and placer) mines-the largest group-declined to such an extent that the over-all totals for the country were reduced even though increases were made at mines producing copper, lead-zinc, iron, miscellaneous metals, and non-metals. A complete panorama of the metal-and nonmetal-mining industry, exclusive of coal mining, reveals a decrease in the number of men employed, the man-hours of employment, and the accident-frequency rates. Were the gold and silver (lode and placer) mines to be considered as a separate category; it would be seen that the number of men employed at all the other groups of mines increased appreciably over 1941. These other increases must be considered important, since these mines produced the vital war minerals that made valuable contributions to the military successes of the United States and its Allies during the year. A separate analysis of each of the various groups of mines may be found elsewhere in this bulletin. For the purpose of maintaining continuity in this series of bulletins, however, the discussion in this introduction will be confined to the entire metal-and nonmetal-mining industry (excluding coal mining, for which a separate bulletin, No. 462, has been published).

Jan 1, 1945

By Andrew Allan

[This report describe the first experiment of the Anthracite Research Laboratory, Bureau of Miners, in attempting to reduce underground-mining costs and conserve anthracite as a natural r-source by introducing now minim methods. The work war, dons in cooperation with one of the large anthracite-producing companies. It applies to productive mining, characterized by comparatively low cost, per ton and high production per man, as differentiated from development mining, which is always necessary before the, productive or retreat phase can begin. The system d scribed in this report is believed to be generally applicable to beds pitching 70° to 90° and, under certain conditions, to beds pitching loss than 70°. After development hate been completed, an openings is made, extending the full width of the 9- to 10-foot coal bad and reaching from the haulageway to the vertical limits of the solid coal. Long drill holes (20 to 50 feet) charged with about one stick of permissible explosive riper foot of length are fused to break the coal. Once broken, the coal is loaded onto a shaker conveyor by gravity and thence into mine: cars. The coal is mined retreating in 15- to 20-foot sections that are broken and loaded onto the conveyor through a specially constructed chute. In the Bureau?s experimental work, the height of sections arse ranged from 35 to 60 fact, depending on the geologic extent of the coal bed.]

Jan 1, 1952

By H. Reginald Hardy

This report describes the results of a research project carried out to investigate the feasibility of using transducer arrays, located on surface or in shallow boreholes, above an active coal mine to detect and locate the source of underground microseismic activity which normally occurs during mining. The initial stage of the project involves the design and development of a self-contained mobile microseismic monitoring facility capable of use in remote field locations. Following this a variety of transducers, and transducer field installation techniques were investigated to obtain optimum sensitivity and high signal-to-noise characteristics. Preliminary efforts were also undertaken to develop semi-automated techniques for analysis of microseismic field data. Using the facilities and techniques developed field studies were carried out at a number of surface locations over a central Pennsylvania coal mine operating at depths of the order of 500 feet. In particular studies were con-ducted over a previously mined development area, troubled by extensive problems of roof instability, and over two longwall panels during mining. Although many of the field studies were carried out during the development stage of the project, results in general have been most encouraging. Limited results were obtained over the development area, however excellent microseismic signals, correlating with underground strata instability, were detected over both long-wall areas, proving the general feasibility of surface monitoring techniques. More recent studies, carried out as part of a subsequent project, and utilizing modified geophone installation techniques at a third longwall site, have verified explicitly the feasibility of measuring underground microseismic activity from surface locations. Sections of typical field data are included in this report along with a brief review of the studies carried out at each of the field sites. Detailed analysis of data obtained at the second and third longwall test sites will be presented in a later report.

Jan 1, 1974

By D. C. Dahlin

The U.S. Bureau of Mines investigated the magnetic susceptibility of minerals as a function of mag-netic field strength to determine how it might affect the potential for high-field magnetic separation as an alternative to other separation technologies. Single-mineral concentrates were prepared from specimens from the same deposit to compare magnetic susceptibilities of minerals that occur together and from specimens from different deposits to compare magnetic susceptibilities of like minerals. A vibrating-sample magnetometer with a superconducting magnet capable of producing a magnetic field of 7.16 x 106 Aim (90 kOe) was used to measure the magnetic moment of the samples. The data were then converted to specific magnetic susceptibility data and plotted as a function of magnetic field strength. Cursory studies were also completed on the effects of iron content and oxidation roasts on magnetic susceptibility in high fields. The results showed that magnetic susceptibility is essentially constant in magnetic fields above those needed to saturate ferromagnetic constituents. Although magnetic susceptibility is influenced by iron content and by thermal treatment, the changes are not large enough to influence separations in fields above 1.59 x 106 Aim (20 kOe).

Jan 1, 2010

By Richard A. Walker

This report describes the development and performance of a multi-level, multi-function Calibration Light Source designed for field-calibration of a group of specific photometers. The Calibration Source is capable of providing ±35% accuracy calibrations at all of the following levels: 0. 05 foot-Lamberts, 6 foot-Lamberts, 6 foot-candles and 20 foot-candles. The Source was found to provide constant light output to within 1% over 50 hours of lamp operation and for line voltage variations of ±25%. It is compact and light-weight (11 pounds), and can be easily transported and used by one man in normal office environments (without requiring a darkroom).

Jan 1, 1976

By John T. Neubert

Between 1988 and 1990, the U.S. Bureau of Mines studied the mineral resources of San Juan National Forest to appraise and determine types and locations of deposits that could be mined economically now and in the foreseeable future. The study included a comprehensive field examination and literature search. Substantial amounts of lead, zinc, copper, gold, and silver have been mined from within the Forest in the La Plata, Rico, Silverton, and Dunton areas. At least one buried 200 million ton stockwork molybdenum deposit occurs in the Rico area. Similar size porphyry copper deposits occur at the surface and about 1,700 feet below the surface in the Bedrock Creek area of the La Plata district. Numerous smaller base-and precious-metal and uranium deposits have been prospected and mined throughout the Forest. Coal, oil, and gas have been or are currently being produced in the western and southern parts of the Forest. Carbon dioxide occurs in the western part of the Forest. Strategic elements occurring within the Forest include platinum, palladium, cadmium, gallium, indium, bismuth, and tellurium; however none of these elements is economically recoverable at present. Several geothermal areas are scattered across the eastern two-thirds of the Forest. Industrial minerals within the Forest include sand and gravel, limestone, and decorative stone.

Jan 1, 1992

By Jeffrey Y. Foley

The Bureau of Mines sampled surface exposures of podiform chromite in the Caribou Mountain-Melozitna ultramafic belt in the Kokrines-Hodzana Highlands, central Alaska. Fieldwork began in 1979 as part of an assessment of the mineral potential of lands adjacent to the trans-Alaska pipeline corridor, for the Bureau of Land Management, and continued through 1981 as a Bureau of Mines investigation. The belt comprises six complexes of which the three closest to the pipeline corridor were investigated. Concentrations of chromite disseminated in dunite host rock make up mineralized intervals ranging in thickness from less than an inch to 5 ft and in grade from 3 to 23 pct chromium. The largest occurrence has an exposed strike length of 80 ft. Bulk surface samples were collected from 10 of these exposures, and beneficiation tests on the samples produced concentrates of metallurgical, refractory, and subindustrial grades. Part I--this report--describes the fieldwork; part II--1C 8916--describes the beneficiation work.

Jan 1, 1983

By Cleo G. Rall

The value of brine analyses in the study of petroleum-engineering problems was recognized early in the history of petroleum. The Bureau of Mines before 1928 had indicated in several reports.3/ ways in which analyses might be used. Because of the confusion resulting from attempts to correlate the work of different chemists using greatly varying methods of analysis and systems of computation and expression of results, a paper presenting the methods used by the Bureau of Mines was prepared and published in 1928. This system of determining the characteristic constituents of oil-field waters and of calculating and reporting results has been widely adopted by the petroleum industry. The earliest and most obvious use of water analyses is determination of the source of water infiltrating into petroleum and natural-gas wells. For this purpose it is necessary that an analysis of the connate water of the formation from which the oil is produced be available and that an analysis of the contaminated water be made. By comparing these analyses with those of connate waters from formations higher in the structure, the formation from which the infiltrating water comes may be identified.

Jan 1, 1953

By W. M. McKewan

The U.S. Bureau of Mines has established a wire rope research laboratory to examine the factors that affect the life of wire rope. A 2-in-diameter 6x25 fiber core rope was degraded on a bending fatigue machine. This was the first in a series of tests on rope of this construction and size. Baseline testing at the laboratory was reported in an earlier publication. Tensile and nondestructive tests were performed on samples of the rope to determine the relationship between rope deterioration and rope breaking strength. The tests indicated that as a wire rope nears the end of its useful life, deterioration and the consequent loss of rope strength increase at an accelerated rate.

Jan 1, 2010

By D. Harrington

The number of fatalities from mine explosions for the fiscal year 1945 dropped below that of the year before; continued improvement over the record of the years from 1940 to 1945 is hopeful, but the number of reported explosions has increased rather than diminished, and the number of victims claimed by explosions is often more definitely a factor of chance than forethought. Mine fires and explosions can be eliminated through the methods now well-known to those well-informed in matters pertaining to safety in mining but ignored by many coal-mine operators and employees who follow procedures of the past or their own short cuts, regardless of disasters that may result: Tried and proved safety measures for preventing mine fires and explosions have been recommended to the mining public repeatedly, yet only a relatively small but far-sighted minority have adopted these measures and made them a part of operating practice. That far more explosion disasters did not occur in 1945 is fortunate. In 1945 a coal-mine fire of electrical origin caused heavy loss of life, while several others from the same cause were controlled with but few fatalities; this hazard is now being curbed temporarily to some degree after the bad record of the two preceding years, but a real solution of the problem has not been reached, although cooperating committees trying to produce at least some answer have made progress.

Jan 1, 1946