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Control the release of ground-water into active underground coal workings by short-term pumping from dewatering wells sited on fractures. Approach The sudden release of fracture-stored groundwater into underground coal workings often occurs when mine workings are developed beneath fracture valleys, Pumping from fracture trace-sited dewatering wells, prior to development of the underlying workings, can be an efficient means of intercepting fracture-stored groundwater before it is released into the mine. Dewatering operations are discontinued once the underlying mine workings have been fully developed, and the maximum possible reduction in fracture storage has been achieved through pumping. How It Works An aerial photographic technique known as fracture trace analysis is used to site dewatering wells on rock fractures in a valley bottom. Downhole caliper and temperature logs are used to assess the fracture flow potential of each dewatering well drilled.

Jan 1, 1987

Develop a more efficient method of testing the integrity of in-situ leach mining operations. The Problems For economic and environ-mental reasons, in-situ leaching operations must be sure that wells do not leak. Loss of solution in large quantities can be expensive in itself, and if such losses result in pollution the costs can be even higher. Wells are usually tested for leaks by sealing them with packers, pressurizing them and monitoring the pressure drop. However, many commercially-available packers are designed to be used in steel-cased wells rather than the fiberglass-or plastic-cased wells used for in-situ mining. These packers are heavy, cumbersome, expensive, and often leak. In addition, commonly used well-integrity-test systems require lengthy test periods and drill rigs or hoist trucks with rigid pipes must be used to run the packers in and out of the well. The Bureau of Mines has developed a mobile, self-contained leak-testing system that is faster, uses trailer-mounted equipment that can be operated by one person, and features a new inflatable packer.

Jan 1, 1985

By Irving Hartmann

The record of safety in the use of permissible explosives in United States coal mines has been excellent, due in great measure to the persistence with which research has been carried on in the Bureau of Mines, to the development of permissible explosives, and to the cooperation of mine operators and workers in using permissibles in a recommended manner and in the effective though gradual replacement of black powder and other nonpermissibles. The demand for increased rate of coal production, changes in mining conditions and minim methods, and introduction of new mining machinery have resulted in modified or new blasting practices. To keep abreast of these developments the Bureau of Mines conducts investigations under actual mining conditions at the Experimental coal mine near Pittsburgh, Pa. Several years ago an extensive study was complete to determine conditions under which the allowable charge limit for permissible explosives per shot hole might be raised from 1.5 to 3 pounds without undue risk of gas or coal-dust ignitions. As a result of the study, this increase in the charge limit was authorized under certain specified conditions in 1948,5/ greatly facilitating production schedules.

Jan 1, 1954

By J. A. McAllister

In the course of a study of domestic Manganese resources, 2-ton representative samples of ore were taken by Bureau of Mines' engineers from the Payday claim, Weber County, and the Newcomb-claims, Rich County, Utah. The Payday No. 1 deposit is situated 13 miles northeast of Huntsville, Weber County, Utah. The manganese ore is a. replacement deposit in limestone and consists of manganese oxides imbedded 'in clay and also as the cementing agent consolidating small pebbles and pieces of quartz and limestone.

Jan 1, 1949

By E. P. Youngman

At the time of the preparation of the monograph upon the mining legisla- tion of Newfoundland, by the Imperial Institute of London, the existing local statutory law (as distinct from case laws and the applicable English acts) con- sisted of the following legislation: 1. Chapter 129 of the consolidated statutes, entitled "Of Crown Lands, Timber, Mines and Minerals," as amended by the Crown lands act, 1928. 2. Chapters 131 and 132 of the consolidated statutes (acts relating to mines regulation and rewards for discovery of minerals, respectively). 3. Crown lands act, 1918, as amended by the crown lands (amendment) act, 1921. 4. The Labrador Act, 1927. 5. The Crown royalties act, 1927. 6. Crown lands act, 1928, together with rules and regulations issued thereunder.

Oct 1, 1932

By Hugo E. Camargo

In an effort to reduce Noise Induced Hearing Loss (NIHL) in the mining industry, the National Institute for Occupational Safety and Health (NIOSH) is conducting research to develop noise controls for mining equipment whose operators exceed the Permissible Exposure Level (PEL). The process involves three steps: 1) Noise source identification (NSI), 2) development of noise controls, and 3) evaluation of the developed noise controls. For the first and third steps, microphone phased array measurements are typically conducted and data are processed using the conventional beamforming (CB) algorithm. However, due to the size and complexity of the machines, this task is not straight forward. Furthermore, because of the low frequency range of interest, i.e., 200 Hz to 1000 Hz, results obtained using CB may show poor resolution issues which result in inaccuracy in the noise source location. To overcome this resolution issue, two alternative approaches are explored in this paper, namely the CLEAN-SC algorithm and a variarion of an adaptive beamforming algorithm known as Robust Capon Beamformer (RCB). These algorithms were used along with the CB algorithm to process data collected from a horizontal Vibrating Screen (VS) machine used in coal preparation plants. Results with the array in the overhead position showed that despite the use of a large array, i.e., 3.5-meter diameter, the acoustic maps obtained using CB showed "hot spots" that covered various components, i.e., the screen deck, the side walls, the I-beam, the eccentric mechanisms, and the electric motor. Thus, it was not possible to identify which component was the dominant contributor to the sound radiated by the machine. The acoustic maps obtained using the RCB algorithm showed smaller "hot" spots that in general covered only one or two components. Nevertheless, the most dramatic reduction in "hot" spot size was obtained using the CLEAN-SC algorithm. This algorithm yielded acoustic maps with small and well localized "hot" spots that pinpointed dominant noise sources. However, because the CLEAN-SC algorithm yields small and localized "hot" spots, extra care needs to be used when aligning the acoustic maps with the actual pictures of the machine. In conclusion, use of the RCB and the CLEAN-SC algorithms in the low frequency range of interest helped pinpoint dominant noise sources which otherwise would be very hard to identify.

Jan 1, 2009

By B. J. Dalton

The Helium Research Center, Helium Activity, Bureau of Mines, is presently engaged in a critical examination of all of the PVT data on helium that appear in the literature. The long-range objective is the development of a single equation of state for helium that will allow all of the thermodynamic properties to be calculated and will reproduce all of the data within the accuracy with which the data are known. A preliminary objective is to obtain the best values of the second virial coefficients and to develop an equation that will reproduce the best values as a function of temperature. The method of treatment consists in expressing the PV product of a gas, for a given isotherm, in terms of a power series in either the pressure or the density and evaluating the constants by least squares solution. Associated with these functions whose coefficients have been evaluated by least squares, the following errors, or deviations, are of interest; the standard error of a single measurement; the standard error in each coefficient; and the standard error of the resulting function.

Jan 1, 1964

By Martin S. Oudenhoven

This Bureau of Mines report presents the results of a microseismic study conducted in the Climax block cave mine at Climax, Colo. Rock noises created by caving were monitored and their sources located during a 3-month period. A planar array of seven accelerometers, located above the block of ore being caved, detected the rock noise. A computer was used to calculate the location of the microseismic activity, using a traveltime difference method. The accuracy of these locations was estimated to be ±20 feet. An analysis of the data taken during the recording period showed a concentration of microseismic events located in the wall of the cave panel. This concentration of events was found to occur in a "high-silica" geologic forma-tion that cut across the caving panel approximately 200 feet behind the undercut.

Jan 1, 1973

By B. J. Dalton

The Helium Research Center, Helium Activity, Bureau of Mines, is presently engaged in a critical examination of all of the PVT data on helium that appear in the literature. The long-range objective is the development of a single equation of state for helium that will allow all of the thermodynamic properties to be calculated and will reproduce all of the data within the accuracy with which the data arc known. A preliminary objective is to obtain the best val¬ues of the second virial coefficients and to develop an equation that will reproduce the best values as a function of temperature. The method of treatment consists in expressing the PV product of a gas, for a given isotherm, in terms of a power series in either the pressure or the density and evaluating the constants by least squares solution. Associated with these functions whose coefficients have been evaluated by least squares, the following errors, or deviations, are of interest; the standard error of a single measurement; the standard error in each coefficient; and the standard error of the resulting function.

Jan 1, 1964

Develop an improved downhole geophone system with enhanced signal/noise ratio for collecting cross-hole seismic data used in tomographic reconstructions. Background The Bureau of Mines is conducting research in the use of cross-hole seismic tomography for detecting and monitoring leach solution flow during in situ mining. This technique requires the use of a downhole seismic energy source in one borehole and a downhole wall-locking receiver (geophone) in another borehole separated from the first by the region to be investigated. Bureau research personnel chose a commercially available air gun for use as the downhole seismic energy source. Unfortunately, commercially available downhole wall-locking geophones that the Bureau tested were difficult to operate in the field, often unreliable and generally inadequate in terms of their signal/noise ratio. Therefore, research personnel began to experiment with an alternative down-hole geophone design that could be used to collect adequate data in a wide variety of borehole and cross-hole field situations. Approach An attractive alternative geophone design would be one that would incorporate a pneumatically operated wall-locking system. As an integral part of the Bureau's existing field system, a portable, high- pressure/low-volume air compressor would have sufficient capacity to operate the air gun as well as several small high-pressure pneumatic linear actuators. This approach was the simplest and most compatible with the research activities being conducted at the site.

Jan 1, 1991

By C. B. Manula, R. L. Sanford, R. A. Rivell

PART I. FLOW CHARTS

Jan 1, 1974

One of the major unknowns in the use of iron and copper is the quantity of various low level impurities, particularly hydrogen, that may be introduced during the deoxidizing process prior to casting. Introduction of hydrogen results in the embrittlement of components made from these metals. In addition, hydrogen bubbles in castings of copper result in the formation of blisters and swelling of the casting. During the last year, a significant effort has been made at the University of Missouri-Rolla to understand the permeation of hydrogen in galvanized automotive steel components and the hydrogen absorption during the electrodeposition of copper. The galvanized steel components consisted of automotive upholstery clips, seat belt holders and brake clips. Although the process of galvanization protects the steel from corrosion the process invariably causes the steel to pick up enough hydrogen to make it susceptible to brittle fracture.

Jan 1, 1992

By C. C. Merrill

Studies were made to determine the amenability of yttrium to fused-salt electrorefining in a controlled atmosphere. Tests were conducted in a LiCl- YCl3 electrolyte system at 710° C. The major variables studied were the YCl3 content of the electrolyte, from l.7 to 13.4 mol percent, and the initial cathode current density, from 410 to 1,630 amperes per square foot. Vacuum distillation was employed to remove salt from the deposited metal. Metallic impurities, except for lithium, could be reduced to near or below their lower analytical limits, ranging from 10 ppm for Cu to 300 ppm for Ta; reduction of oxygen content, however, was accomplished only in metal produced from electrolytes with 5.4 mol percent YCl3 or less. Initial cathode current density had little effect on the purity of the product.

Jan 1, 1967

Reduce worker exposure to respirable dust without interfering with bag-filling operations. Approach A dust control hood was developed which contains and captures dust close to its source and prevents it from entering the bag-filling operator's work place. How It Works A sheet metal hood is placed around the nozzle of the bag filling machine. The hood is connected through ducts to the plant exhaust ventilation system. Air pulled into the front of the hood and around the sides of the bag picks up dust generated inside the hood, and carries it to the dust collector. The size of the hood can be adapted to fit most fluidized valve-type bag-filling machines. The height of the hood depends on the bulk density of the product and weight of the bags being filled. The 14-inch-width of the hood allows it to be used on multi-nozzle baging machines spaced 16 inches on center. Only 2/3 of the bag is actually within the hood, and this allows easy operator access for placing the bags on the nozzle.

Jan 1, 1978

By A. C. Johnson

This report is one of a series being prepared by the Bureau of Mines on exploration, development, mining methods, and costs at various mines in the United States. It describes operations at the Black Rock mine, Wah Chang Mining Corp., Mono County, Calif. The purpose of these reports is to promote development and conservation of our mineral resources by disseminating technologic information on mining methods, practices, and costs. The Black Rock tungsten mine of the Wah Chang Mining Corp. is 33 miles north of Bishop, Calif., in the Benton Range, Mono County, Calif. The property was acquired in August 1950 and a well-planned program of exploration, development, and exploitation resulted in a good production record with low costs. Operations were halted in July 1957, about 6 months after suspension of the tungsten purchase program by the Federal Government.

Jan 1, 1960

By James A. Morgan

FIELD MEASUREMENTS OF NOISE WERE MADE ON THE PERIPHERY OF ENCLOSURES DESIGNED, MANUFACTURED AND INSTALLED BY INDUSTRIAL ACOUSTICS COMPANY, INC. ON THE SECONDARY TACONITE CRUSHER AT THE JACKSON COUNTY IRON COMPANY PLANT IN BLACK RIVER FALLS, WISCONSIN. NOISE REDUCTION ACHIEVED BY THE ENCLOSURES WAS SUFPICIENT TO PERMIT REDUCTION OF CRUSHER ROOM NOISE TO 90 DBA, PROVIDED THAT OTHER SOURCES ARE APPROPRIATELY TREATED AND ACOUSTICAL ABSORPTION IS PROVIDED IN THE CRUSHER ROOM. SECONDARY CRUSHER NOISE WAS REDUCED 10 TO 15 DBA BY THE ENCLOSURES.

Jan 1, 1980

By G. E. McElroy

"while investigating the presence of heavy strata gases* in certain mines of the East Tintic mining district of Utah, a small, local body of light, very hot gas of high-nitrogen composition was noted in one of the mines. Observations and analyses indicate that this light gas was resulting from very rapid oxidation of finely disseminated pyrite, in lead-silver sulphide ore. The gas was actually mine air which had lost a large proportion of its oxygen content by reaction with the pyrite. This body of gas was hanging in a local high spot about 5 by 5 by 5 feet in size, caused by caving, at the end of a crosscut. Fifty feet from this spot, an air current of 6000 cubic feet per minute was entering the 5 by 7 foot cross-cat from a raise from below.On account of the vapor contained in the gas, the bottom level of the gas could be plainly seen and was practically a horizontal plane, but of slightly wavy appearance, coinciding with the point where an acetylene light was extinguished. This body of gas was visited on three occasions and samples obtained by means of evacaated bulbs and by water displacement. The temperature of the gas was ap¬proximately 175 degrees P. on all three occasions, so that sampling required thick gloves and quick action. Air three feet below the vapor line had a temperature of only 120 degrees F., and a relative humidity of 27 per cent. The stratification of the air and gas mixtures was so sharply defined that the sampler could hold his head a few inches below the vapor level for an appreciable period of time without any noticeable effect other than that due to the high temperature. At one foot below vapor level, it was 135 degrees F., and the relative humidity was 30 per cent. When a candle and an acetylene light were raised into the gas from below, the candle flame was extinguished at a point two inches lower than the acetylene flume, indicating a drop in oxygen content from about 16 per cent to 12 per cent (oxygen content of normal dry air 20.05 per cent) in the distance of two inches."

Sep 1, 1921

By R. V. Ramani, R. A. Jankowski, R. Bhaskar

"The spatial distribution of airborne dusts, deposition of dust in the airway, as well as the effect of airflow velocity and particle density on dust behavior in mine airways were studied in a set of experiments performed in a mine airway under controlled conditions. Considerable deposition of dust near the source was indicated. Pronounced effects due to velocity were observed in ambient dust concentration and deposition along the mine airway, both in the respirable and the total size ranges. Cross-sectional concentration measurements indicate an increase in concentration from the roof to the floor. The average cross-sectional concentration is about 75% of the concentration in the center of the airway.IntroductionA number of studies have been performed since the early 1950s on the behavior of dust in mine air (Bradshaw and Godbert, 1954; Dawes and Slack, 1954; Bradshaw et al., 1954; Hall, 1955-56; Reinhardt, 1971; Ford, 1971; Courtney et al., 1982). While the experimental data available from these studies are indeed useful in understanding dust cloud behavior in a specific situation, no generalized conclusions can be drawn because of the lack of data on parameters such as flow velocity, size distribution of the source dust, and particle density. These change from mine to mine or even within the same mine. The present study is aimed at providing a better understanding of the temporal and spatial behavior of dust particles in underground' mine airways (National Academy of Sciences, 1980). The characteristics studied encompassed airborne concentrations and floor depositions over the entire size range as well as the respirable size range. The experimental results in this paper are intended to complement a mathematical model developed to predict ambient concentration and deposition of airborne dust in mine airways (Bhaskar and Ramani, 1986)."

Aug 31, 1989

By Jacqueline A. McClaskey

The U.S. Bureau of Mines Information and Analysis Directorate collects worldwide data on virtually every commercially important non fuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. The Bureau's data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority for the U.S. Bureau of Mines survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress). This act strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1993

By B. J. Scheiner

Extraction of molybdenum from molybdenite ore by an electrolytic oxidation procedure was investigated by the Bureau o f Mines. Various parameters affecting molybdenum extraction, such as salt concentration, temperature, treatment rate, current density, and particle size, were studied. Molybdenum extraction of 95.2 percent was achieved on a laboratory scale from an ore containing 0.35 percent molybdenite. Corresponding power consumption was 24 kwhr per pound of molybdenum extracted with a base consumption of 4.5 pounds of sodium carbonate. Laboratory and pilot plant experiments are in progress on low-grade molybdenum concentrates containing rhenium and copper. Preliminary results indicate that molybdenum extractions in the 90- to 99-percent range and rhenium extractions of 93 to 99 percent can he obtained without appreciable oxidation of associated copper minerals.

Jan 1, 1972