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By T. C. Green

A two-phase program evaluated commercial proximity warning devices and then served to design and develop an automatic electrostatic field strength measurement device with improved performance. The Phase I program consisted of test and evaluation of three commercial proximity warning devices, all of which operate on the principle of electrostatic field intensity measurement for determining proximity to high voltage power lines. Performance testing of these devices utilized full-scale cranes and power line systems and a scale model facility. The evaluation results were reported in the Phase I report entitled "Evaluation of Proximity Warning Devices" dated 22 February 1980. Under the Phase II program, a microproressor-based data acquisition system was designed and developed to collect and measure field strength at distributed points around the crane boom. This unit (referred to as the Distributed Sensor AC Electrometer) measures the field strength about a crane boom using 17 distributed sensors. Keyboard control is provided for the equipment operator. Measured field strength values are displayed on a line printer and recorded on magnetic tape. Laboratory testing of this unit demonstrated performance characteristics and field strength measurement accuracy within the design goals. A Phase III measurements program is proposed using the AC Electrometer to map the field strength contours about power line configurations.

Jan 1, 1981

By William A. Beck

The Construction Aggregates Corp. operates a plant for processing sand and gravel from two deposits in Ottawa County, Mich. The bulk of the sand is obtained from a sand dune on the shore of Lake Michigan, and the gravel is dug from a glacial-drift deposit farther inland. Mining is done with draglines, and the material, both at the digging site and in the plant, is moved mainly by systems of conveyors. The Ferrysburg plant serves customers along the Great Lakes, which is unusual for a business normally local in character. Annual production exceeds 1-1/2 million tons of sand and gravel as concrete aggregate and 200,000 tons of core sand for foundry use.

Jan 1, 1962

By Charles C. Boley

High-volatile A bituminous coal from the Allen mine, Las Animas County, Colo., blended with char produced from the same coal yielded accept-able metallurgical coke in a 500-lb movable-wall test oven. Nineteen experimental runs were carried out using several concentration levels of two different chars, 5.6 and 19.6 percent volatile matter, produced by entrainment carbonization of the base coal. With the higher-volatile char, an acceptable coke was produced at a 22.5-percent concentration; the lower-volatile char did not produce an acceptable coke at the concentrations investigated.

Jan 1, 1972

By T. Kessler

Spark-source mass spectrometry has been used to determine the amounts of minor and trace elements in coal particles of various sizes, including the respirable range (<5 microns). Fifty-six elements ranging in concentration from 0.1 ppm wt to 5,000 ppm wt have been determined. The investigation of coal and coal ash has shown that the organic material in coal does not interfere with the spark-source determination of the various elements.

Jan 1, 1971

By Irving Hartmann

As part of the continuing effort by the Bureau of Mines to promote mine safety, research work is being conducted at the Experimental coal mine, Bruceton, Pa., on the prevention of coal-mine explosions and on other mine-safety problems. The principal subjects studied during the past 2 years are briefly described in this paper. Although at present these problems are relevant particularly to the mine layout and to high-speed mining practices in numerous American coal mines, it is hoped that the findings will prove interesting and useful also to our European research colleagues. Some of the investigations treated here will be presented in greater detail in forthcoming Bureau of Mines reports. 1. UNDERGROUND STORAGE OF COAL CUTTINGS The seams in mist American bituminous-coal mines are undercut, shear-cut, or top-cut before blasting. The cuttings arc generally loaded out with the balance of the coal. However, in some mines it is not economical to load and remove cuttings from the mine. This applies especially if the cut section of the seam is of appreciably lower grade than the rest of the coal, or if the cut is made partly into an adjacent stratum that is high in incombustible content. In such mines the cuttings are sometimes stored in random heaps in rooms or other areas, along the ribs of mine entries, or in layers on the floor of rooms or entries.

Jan 1, 1956

By M. S. Seehra, R. S. Pandurangi

"The interaction of amorphous silica particles with several hydrogen bonding agents (H2O,, C2H,OH, C,H,NO) was investigated by monitoring the changes in the bulk and surface IR vibrational modes of silica using photoacoustic spectroscopy, It is argued that the intensity of the silanol band at 3747 cm-1 provides (an inverse) quantitative measure of the interaction of surface groups, along with the shift in the broad hydroxyl band, the interaction following the order C,H,NO > C2H2OH > H2O.The use of IR spectroscopy to study the adsorption on solid surfaces is well documented in the literature,"" For example, hydroxylation of a clean silica surface results in the formation of the free silanol group Si-OH, with a sharp IR band near 3747 cm-1. Further hydroxylation produces a broad band near 3500 cm-1, which is believed to result from various hydrogen-bonded silanol bands leading to a multilayered surface structure of few nm.3-6 Earlier studies had indicated a relationship between the surface silanol band and various chemical activities of silica such as cytotoxicity,7-9 catalysis,10-12 and others.13 Recent studies from our group14-in which the intensity of the silanol band and cytotoxicity of silica, heat-treated at various temperatures up to 1095°C, were investigated-have provided a strong correlation between cytotoxicity and intensity of the silanol band.Coating of silica by PVPNO (polyvinyl-2-pyridine N-oxide with the empirical formula C7H8N0), a strong hydrogen bonding agent, is known to reduce the cytotoxicity of silica, presumably by chemically blocking the silanol groups from phospholipids.15 This interaction of the hydrogen bonding agents with the silica can be studied by IR spectroscopy, and Knozinger16 and Rouxlet and Semples17 have used transmission IR spectroscopy to study the effect of various chemicals on the surface IR modes of silica. However, one of the major disadvantages of transmission IR spectroscopy is that the sample preparation (grinding and mixing with KBr and pelletizing) usually distorts the surface modes (see, e.g., Ref. 14) and there is always a doubt about the effect of the sample preparation on the measured properties, In recent years, photoacoustic (PA) spectroscopy has become the technique of choice for studying the IR spectra of samples in their natural state, since no sample preparation is necessary.18,19 Moreover, according to a recent paper,20 the relative intensity of the surface modes in PA spectroscopy of silica particles is much higher than that in transmission FT-IR spectroscopy. Consequently PA spectroscopy is ideal for studying the surface chemistry, In this work, we have used PA spectroscopy to investigate the interaction of three hydrogen bonding agents (C7H8NO, C2H5OH, and H20) with the silica surface by monitoring changes in the surface IR modes, Our results show that the surface IR modes get perturbed to a larger extent than the bulk IR modes in interaction with the hydrogen bonding agents, Moreover, whereas in the earlier studies, the shift of the broad silanol band near 3500 cm-1 was used as a measure of the interaction with hydrogen bonding agents,16,17 here we show that the relative decrease in the intensity of the sharp silanol band near 3747 cm-1 also serves as a quantitative parameter for the relative surface coverage and surface modification, Details of this work are given below,The Cab-O-Sil samples of silica used here were obtained from the Cabot Corporation of Tuscola, IL, In our earlier studies,14,20 we have shown these particles to be amorphous and about 0.05 am in size, For coverage of these particles with H20 and C2H50H, the following procedure was employed. About 5 mg of silica was mixed with 50 mL of the liquid (H2O or C2H5OH) and refluxed for one hour, The remaining liquid was allowed to evap¬orate to dryness and 1 mg of the treated sample was used to collect the PA spectra. In the case of PVPNO, the amount that binds to Cab-O-Sil is taken from the data on quar"

Mar 1, 1992

By Gary J. Cwick

Mineral resources of the Rice Valley Wilderness Study Area (WSA), in the Mojave Desert of southeastern California, were investigated by the U.S. Bureau of Mines and U.S. Geological Survey during 1980. The study consisted of an examination of mines, prospects, and mineralized areas by the Bureau: of Mines and geological, geochemical, and geophysical investigations by the Geological Survey. Little indicated potential for the presence of mineral resources exists in the valley floor segment of the study area. The Big Maria Mountains section of the study area has some potential for mineral resource development. Decorative building stone from both bedded quartzite deposits and weathered limestone surface rubble (driftwood stone) has been produced from the Big Maria Mountains segment of the study area. Total production is unrecorded but probably small. A 700,000 ton (640,000 t) quartzite resource was inferred and 4,500 tons (4,100 t) of driftwood stone within the study area was estimated. A relatively pure limestone deposit inside the study area contains an inferred resource of 14 million tons (13 million t). One prospect suggests a potential for the presence of manganese resources although none were estimated. The likelihood of discovering oil, gas, coal, uranium or geothermal energy is low; potential sources are not known to exist.

Jan 1, 1982

By Terry J. Close

In 1986 and 1987, at the request of the U.S. Bureau of Land Management, U.S. Bureau of Mines personnel studied 7,040 acres of the 7,240-acre Sheep Mountain Wilderness Study Area (OR-006-003) in order to evaluate its identified mineral resources. The area studied is along the divide between the Snake River and Pine Creek about 1.5 mi south of the village of Oxbow in Baker County, OR. No mineral resources or mineral-related activities were identified in the Sheep Mountain study area. The basalt covering most of the study area has no known mineralized sites. However, it contains common agate and opal that is of limited interest to mineral collectors. This basalt (stone) could be used locally as construction material (crushed stone or fill); however, suitable material is wide spread in the region and more accessible to possible markets.

Jan 1, 1987

By Galen G. Waddell

The Deep Creek zinc and lead mine afforded an excellent example of a relatively small underground mine operation that approached the low mining costs of large, highly mechanized mines. An open stope mining method incorporating sublevel benches and vertical long holes was used (fig. 1). Detailed descriptions are given on the exploration program, stope development, stoping procedures, and pillar removal. Pressure grouting was used to check the inflow of water and thus prolong the life of the mine. Statistics on mining costs and on electric power consumption, haulage from mine to mill, and milling costs are included.

Jan 1, 1963

Objective To reduce equipment operator exposure to respirable dust in enclosed cabs by examining the effectiveness of retrofitting air pressurization and filtration systems on existing cabs. Background Many types of heavy equipment are used in mining, construction, and agriculture. Most have enclosed cabs to protect the equipment operator from excessive dust and noise exposure. When the equipment is new, controls are normally implemented into the cab to keep these exposures at acceptable levels. However, as this equipment becomes older, many components of the enclosure deteriorate, such as gaskets and seals. This causes the effectiveness of the enclosed cab to be greatly reduced. Once this occurs, the equipment operator&apos;s dust exposure can increase to hazardous levels. In surface mining operations, elevated exposures to crystalline silica have caused an excessive incidence of silicosis. Approach A cooperative research study with a mining operation and a cab filtration company was conducted to evaluate the effectiveness of retrofitting an older surface drill with two controls to lower the drill operator&apos;s respirable dust exposure. These two controls were: (1) A good air filtering and pressurization system to ensure that clean air was delivered into the enclosed cab. Ideally, the incoming air filter should be 99% efficient in removing particles with an aero- dynamic diameter of 0.3 pm or greater from the airflow. (2) Sufficiently sealing the cab to develop a positive static pres- sure and ensure that dust was not leaking into the cab. This was done by plugging all holes and cracks and maintaining good gaskets and seals. To prevent wind from forcing contaminated air through holes in the cab, the cab&apos;s static pressure must be greater than the wind&apos;s velocity pressure. During the course of this research, it was found that a floor heater fan used in the drill during the winter months greatly increased the operator’s Respirable dust exposure. Problem Identification Four days of background dust levels were measured as a baseline for this research. These baseline measurements were taken in May 2000 when air temperatures ranged from 60° to 70° F. When this was completed, the two controls were implemented. The first control was to install an improved air filtering and pressurization system on the enclosed cab. This was composed of a two-stage prefilter, a blower, then the respirator-medium secondary filter. Since the secondary filter was on the positive side of the fan, all air delivered into the enclosed cab had to pass through this secondary filter. After the filtering system was installed, the cab was pressurized to a static pressure of0.01 inches of water (w.g.), which is still very minimal. The second control was to seal the cab. New door gaskets were installed, and all cracks and holes in the shell of the enclosure were plugged. This increased the cab pressurization to approximately 0.1 inches w.g.

Mar 1, 2001

By John A. Johnson

For the purpose of comparing the amounts of dust produced by various mining operations, samples of atmospheric dust were collected during a complete cycle of drilling, blasting and mucking at or near the face of the Bureau&apos;s Mount Weather testing adit while the efficiency of several types of stemming in metal-mine blasting was being investigated. ACKNOWLEDGMENTS All gas samples were analyzed in the laboratory of the Bureau of Mines Gas Section at Pittsburgh, Pa.

Jan 1, 1939

By W. T. Millar

Magnetite mines in the Sterling tract, Orange County, N. Y., were operated almost continuously from pre-Revolutionary days until 1923. The Red-Back mine, one of several in this tract, was discovered in 1780; operated briefly in 1880; and abandoned, presumably because the iron ore contained considerable sulfur. The mine is in rough, mountainous country, with altitudes ranging from 500 to 1,100 feet. The magnetite deposit occurs in complex metamorphosed pre-Cambrian formation and is thought to be a replacement of limestone by magnetite. A dip-needle survey, completed in 1916, traced magnetic anomalies for a mile along the outcrop. A preliminary examination of the Red-Back mine was made by W. T. Millar, Bureau of Mines engineer, in December 1942. The Bureau of Mines bored seven diamond-drill holes aggregating 2,727.6 feet during the winter of 1943-44. A zone of magnetite mineralization was intersected in each of the holes.

Jan 1, 1949

By Victor Himel

This report documents a systematic approach towards implementing an improved ensemble for the mine rescue team system that will protect against the hazards of mine rescue and recovery and will also afford improved performance through increased comfort and maneuverability, lighter burdens, and improved human engineering designs. In the first part (Task 1) the mine rescue team&apos;s protective needs were defined along with the test methods required to evaluate whether a particular piece of gear met these needs. Task 2 assessed existing gear against performance criteria and standards developed in Task 1. Task 3 consisted of the conceptual design and construction phases of the MRPE program. Special consideration was given to advanced concepts, materials, and equipment.

Jan 1, 1982

By H. William Zeller

The Bureau of Mines performed laboratory research into the effects of a barium-based fuel additive (the "postflame" type) on diesel particulate matter (DPM) emissions. The 5.6-L, six-cylinder test engine is typical of types certifiable for use in underground mines. Test parameters consisted of additive concentration and engine loads, speed, and air intake restriction. DPM emissions, including condensed volatiles, were measured gravimetrically. Also measured were gaseous emissions including carbon monoxide, nitrogen oxides, and hydrocarbons. The fuel additive was effective, reducing DPM up to 75 pct, when used at a concentration of 0.09 wt pct (one-fourth of the concentration recommended by the manufacturer). The additive was most effective at the highest fuel-air ratios, reducing DPM from 400 mg/m3 for untreated fuel to 120 mg/m3. At light loads, 25 pct of full rated, no DPM reductions were measured. Based on these results, the additive is recommended for use in diesel fuel, at a concentration of 0.09 wt pct, to power underground mining equipment as long as certain conditions are met: that a beneficial DPM reduction is verified, that the minimum required quantity of additive is used, and that potential adverse effects such as increased nitrogen oxides are checked.

Jan 1, 1990

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 Earle S. Burnett

This report outlines the experimental procedures for using a Burnett apparatus to obtain compressibility coefficients for multiphase, multicomponent fluid mixtures. The conventional Burnett method is described briefly whereby multiphase compressibility data can be obtained by first determining the compressibility factor, Z, as an isothermal function of pressure alone. Then starting at conditions of temperature and pressure where Z is known, the fluid is cooled at constant volume to some lower temperature at which the resulting pressure is measured, and a corresponding value of Z is obtained from a fundamental relationship between compressibility factors, pressures, and temperatures at constant volume. The isochoric treatment of the fluid, extended to still lower temperatures and along other isochors, eventually results in compressibility determinations for the whole two-phase system thus covered experimentally.

Jan 1, 1963

By J. A. Herdlick

At the request of the War Production Board a preliminary examination of the Big Ben molybdenum prospect near Neihart, Cascade County, Mont., was made by the Bureau of Mines under G. N. Bennett, mining engineer, Bureau of Mines Montana district office, in September 1942. Formal investigation, consisting of sampling, core drilling, and metallurgical testing, was later undertaken and completed in 1943. Field work was directed by Robert D. O&apos;Brien, mining engineer, Montana district office, under the supervision of E. W. Newman, supervising engineer, Montana district office. This report describes the deposit, presents the factual data obtained from the sampling and core-drilling operations, and summarizes the results of the metallurgical studies. The deposit was first located and prospected in 1922 by the present owner, Frank Mansikka of Neihart, Mont. Periodic examinations made by responsible mining interests were culminated in 1938 when the Federal Mining & Smelting Co. optioned and investigated the property. No ores have been produced from the deposit to date.

Jan 1, 1949

By Ricardo Burdisso, Rahul Kadam, Kyle Schwartz, Marty Johnson

Occupational exposure to hand transmitted vibration (HTV) arises from the hand held powered tools extensively used in the mining and construction industry such as rock drills, chipping hammers, chain saws etc. Regular exposure to HTV is the major cause of a range of permanent injuries to human hands and arms which are commonly referred to as hand-arm vibration syndrome (HAVS). In addition to this, the percussive tools generate overall sound power levels in excess of 110dBA in most cases. Such a high sound power level greatly exceeds the maximum permissible exposure limit (PEL) of organizations such as National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA). Long term occupational exposure to this noise has been diagnosed as the main reason for permanent hearing loss in the operators. It is therefore important to develop an understanding of the mechanisms which lead to these high vibration and sound levels and in order to do this a detailed computational model of a pneumatic chipping hammer has been made. This paper presents a nonlinear computational model of a pneumatic chipping hammer. In order to better understand the dynamics of the chipping hammer, the hammer was subdivided into components that are shown in figure 1 (a) (based on a chipping hammer manufactured by Atlas-Copco). The hammer mainly consisted of a center body, a moving piston and a chisel. Compressed air is used to drive the piston inside of a cylinder and on the downward stroke this piston impacts the chisel to create the hammer effect. The machine has one pneumatic valve and this valve regulates the air supply either to the upper chamber or to the lower chamber. The valve changes according to the relative pressures in the two chambers and the supply pressure. There are also twelve different exhaust ports at two positions along the cylinder labeled upper ports and lower ports. As the piston moves the ports can be closed or open (allowing exhaust). Fundamentally, the computational model was made up of two different sub-models, a fluid model and a structural dynamic model as shown in Figure 3 (a) and (b) respectively. The first sub-model takes into consideration the fluid dynamics of the machine since the hammer is driven by compressed air. Equations for the mass flow rate though bleed orifices (assuming an isentropic process) 1 is used to determine the mass flow into and out of the upper and lower chambers. From this the pressures in the two chambers and consequently the forcing on the piston can be calculated. The second sub-model deals with modeling the structural [ ]

Jan 6, 2006

By Frank K. McIntosh

The Hamme tungsten district is in Vance County, N. C., and Mecklenburg County, Va. Principal development has been in Vance County. The district is approximately 8 miles long by 1 mile wide and extends northeast-southwest. Its center is about 3 miles N. 65° W. of Townsville, N. C. The occurrence of tungsten in the district was first reported in 1901, but it was not until the Hamme brothers revived interest in the deposits in 1942 that commercial development began. The Bureau of Mines, as part of the war minerals program, began exploration and development of the district in June 1943 and completed it in December 1943. The Federal Geological Survey cooperated by mapping the topography and geology and logging the drill cores. The program included mapping, trenching, sampling, diamond drilling, and analyses and beneficiation of ore samples, The principal ore mineral is hubnerite, which occurs in quartz veins within the schist and granite. The veins are generally lenticular along the strike and dip. About 50 quartz veins have been noted in the area, but many are barren or slightly mineralized.

Jan 1, 1948

By J. N. Geyer

In coal mining it is essential to maintain the roof over working places and roadways in the safest condition possible. To this end every effort should be made to win the coal with the least injury to the immediate roof strata, as broken strata certainly present a greater hazard than a sound roof. The chief causes of injury to the roof in mining are inherent in the method of development and recovery and the blasting practices followed. The first, which may produce severe stresses in the roof, weakening it over comparatively large areas has been discussed in previous papers3 and will not be treated here. The second cause is local in effect, but with the same general method of blasting being employed throughout a mine having uniform roof conditions, similar effects on the roof may be expected. In the Bureau&apos;s investigation of accidents caused by falls of roof and coal it has been necessary to make a careful study of blasting practices and their effect on the immediate roof. The purpose of this paper is to show the effect of the observed methods of blasting on different types of roof and to point out methods that have been proved to be least harmful to the roof strata. The data used in preparing this paper have been compiled from reports made by Bureau engineers engaged in the study of falls of roof and coal, and embrace mines opened in the Pittsburgh coal in Ohio and Pennsylvania and the Pittsburgh and Sewickley coals in West Virginia.

Jan 1, 1933