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By Andrew F. Conn

This report summarizes the results from the first year of an anticipated multiphase program to develop improved coal mining equipment which utilize the CAVIJET? cavitating water jet method. This laboratory parametric study demonstrated the advantages of cavitating jets over non­cavitating jets in cutting coal, by producing comparable slot depths at one-fifth of the operating pressure, at better than one-half of the spe­cific energy. These results suggest that CAVIJET-augmented mining devices can be developed with compact, low-pressure pumps. Thus, CAVIJET should be capable of operating with safer, lighter support equipment, while providing all of the advantages (reduction of dust and sparks, reduced damage to cutters) of conventional hydraulic mining methods.

Jan 1, 1976

By Lawrence G. Houk

Monazite sand is the only commercial source of cerium, other rare-earth metals and thorium. Although used in rather small quantities, it is essential to many industries. The United Unites is entirely dependent upon British India and Brazil for its supplies. Monazite sand or sand imported under the tariff classification for monazite was shipped to the United States in greater quantities, in 1940 than ever before. About 75 percent of our imports was from British India and most of the remainder from Brazil. If need be, Brazilian production can be expanded to supply all of our essential requirements, and the theater of war expands in the Pacific Brazil may supersede India as the principal source. PHYSICAL PROPERTIES The mineral monazite is generally honey yellow or may vary from greenish yellow to clove brown. The grains are small and resinous in luster, and range from subtranslucent to opaque. The specific gravity varies

Jan 1, 1943

By James Westfield

A brief résumé follows of recent activities of the Division of Coal-Mine Inspection that have had a favorable effect on health, safety, and the reduction of injuries at coal mines: 1. The Federal Mine Safety Code for Bituminous Coal and Lignite Mines of the United States was issued originally by the Director of the Bureau of Mines on July 24, 1946, after consulting with management and labor representatives of the coal-mining industry. The code has been used by Federal coal-mine inspectors while inspecting bituminous-coal and lignite mines as a basis for determining the existence of unhealthful and unsafe conditions and practices in these mines. A revised code was issued by the Secretary of the Interior on October 8, 1953, after further consultations with representatives of management and mine workers and was incorporated by reference in the 1952 and subsequent bituminous-coal wage agreements. The agreement of May 29, 1946, between the Secretary of the Interior, acting as Coal Mines Administrator under authority of Executive Order 9728, and the United Mine Workers of America, covering bituminous-coal and lignite mines in Government possession, charged Federal coal-mine inspectors with the responsibility of making periodic investigations of the mines and reporting to the Coal Mines Administrator any violations of the Federal Mine Safety Code. Federal coal-mine inspectors also had temporary authority to close mines found to be imminently dangerous, but such authority (under Executive Order 9728) was removed on June 30, 1947, when Government control of the mines was terminated.

Jan 1, 1958

By Bruce Maxwell

The deformation modulus of coal mine pillars theoretically can be reduced by drilling holes in advance of the mining face. This reduction of modulus along the edge of the pillar has the effect of decreasing the stress concentration in the roof; control of roof caving is thereby predicted. Initial field work indicated that a high horizontal stress field existed at the field test site: Subsequent field work was undertaken to confirm the high horizontal stress field and to attempt to relieve the horizontal stress in the immediate roof. A method of softening pillars in conjunction with normal mining activity was developed. Instruments to measure horizontal roof strain, roof parting, roof tilt at the rib, and changes in vertical and horizontal stress in the roof and in the coal were used. These instruments were installed in both softened and unsoftened entries and in locations to indicate the effect of vertical slots in the roof. Significant stress reduction due to pillar softening was indicated, but the effect of this reduction on roof stability was not established. The vertical roof slots relieved the horizontal stress in the immediate roof very effectively, and observations of roof conditions indicated that the slots definitely improved roof stability.

Jan 1, 1977

By A. C. Johnson, es Hol, E. O. Binyon

"INTRODUCTION AND SUMMARYThe tungsten properties of Lincoln Mines, Inc., and North Tem Flute Mining and Development Co. were first explored by the Bureau of Mines in 1942. Work on the project comprised trenching, sampling, a small amount of road and trail construction, and a small amount of core drilling. From April 13 to December 10, 1944, additional diamond drilling was done by the Bureau of Mines to test the lateral and downward extensions of the various tactite zones along the contact south of the Lincoln mine, including the property of the North Tem Piute Mining & Development Co.Claims leased by the Lincoln Mines, Inc., are in secs. 25 and 36, T. 3 S., R. 56 E.; secs. 30 and 31, T. 3 S., R. 57 E.: and sec. 1, T. 4 S., R 56 E., M. D. B. & M., in the Tem Piute Mining District, near the north end of the Timpahute Range in west central Lincoln County, Nev. D. B. Fegles is president of Lincoln Mines, Inc. and general offices are in the Wesley Temple Building, Minneapolis, Minn.In June 1945, the Atolia Mining Co. leased the property and purchased the mill and mining equipment from Lincoln Mines, Inc. P. R. Bradley is president of the Atolia Mining Co., whose offices are in the Crocker Building, San Francisco, Calif. This company surrendered the lease on the property on September 30, 1948. The property owners are continuing operations and are now engaged in building a 20-ton mill.The claims of the North Tern Flute Mining & Development Cc. are in sec. 1, T. 4 S., R. 56 E., M. D. B. & M. Merle F. Schofield is president of the company and maintains an office at Hike, Nev. These claims were leased by H. P. Laslett, of the Utah Nevada Mining Co., in 1945 and by the Atolia Mining Co. in 1946. The owners are now doing some exploratory work."

Jan 1, 1950

By Sidney A. Suhler

A field operable, breadboard model, borehole radar was developed for the detection of hazardous geological anomalies in and above a coal seam in advance of mining. A four-inch diameter downhole probe was fabricated and tested in several environments. The radar transmitter was also employed in a cross-hole or through transmission mode to determine natural geotechnical and man-made conditions between boreholes. Sensitivity to underground conditions in both modes of operation were indicated.

Jan 1, 1978

By C. F. Jackson

This paper describing the mining practices at a mine in the Southeast Missouri district is one of a series being prepared by the Bureau of Mines on mining practices, methods, and costs in the various mining districts of the United States. The conditions, operating methods, and practice described in the following pages arc those obtaining at a property in the Southeastern Missouri lead belt, St. Francois County, Mo. This property is the eldest in the county and is a consolidation of a number of separate mines originally opened up as individual operations many years ago. Present-day operations have necessarily to be adapted to suit the older levels, stones, and pillars, and also the recovery of ore from worked over areas which was considered too low grade to mine in the earlier days constitutes a different problem than that of development and mining in virgin ground.

Jan 1, 1929

By Arthur V. Petty

The Bureau of Mines has investigated the effect of refractory oxide additions, introduced in soluble form, on the refractory properties of 42-, 58-, and 70-pct-A1203 brick. Brick having porosities ranging from 12 to 16 pct were impregnated with solutions containing chrome, chrome-iron, zirconium, calcium, magnesium, cobalt, nickel, tin, and manganese ions. Additions of some of these ions provided dramatic improvements to such properties as hot modulus of rupture, hot load, and particularly slag resistance. These improvements can be related to reduction of porosity, amorphous grain boundary phases, formation of more refractory bond phases, and reduction of the wettability of Al203-containing refractories by metallurgical slags. Fifty-eight-percent-AI203 brick, impregnated with chrome, showed hot modulus of rupture, hot load, and slag resistance two to five times better than those of untreated 70-pct-AI203 brick. This could result in reducing the Nation's dependence on imported refractory-grade bauxite generally required for high-A1203 brick, as domestic alumina resouces could be used to produce the improved refractories.

Jan 1, 1984

By David C. Byrne

PURPOSE: Evaluate practical technological advances in hearing protective devices for use in different mining environments. RESEARCH SUMMARY: Previous NIOSH research shows that miners develop hearing loss much more quickly than nonoccupationally noise-exposed individuals and that miners experience a greater severity of hearing loss than would be expected for nonoccupational noise-exposed persons of the same age and sex. As described in the National Occupation-al Research Agenda, problems created by occupational hearing loss include(1) reduced quality of life due to social isolation and unrelenting tinnitus,(2) impaired communication with family members, the public, and coworkers, (3) diminished ability to monitor the work environment (i.e., warning signals, equipment sounds, etc.), (4) lost productivity and increased accidents resulting from impaired communication and isolation, and (5) expenses for workers’ compensation and hearing aids. Although eliminating hazardous noise is the long-term solution to the noise problem, miners will likely need to rely on personal hearing protection in certain situations for quite some time. However, it is well known that noise attenuation provided by hearing protectors as they are worn during everyday use is usually quite different (i.e., worse) than when tested under lab conditions. In addition, workers may refuse to wear their hearing protection for any number of reasons. This project was initiated to evaluate practical technological advances in hearing protectors, with an emphasis on optimizing the balance between effectiveness, comfort, over protection, and communication ability. The recently completed auditory research facility is now under-going the accreditation process conducted by the National Institute of Standards and Technology under the National Voluntary Laboratory Accreditation Program. Experiments are planned to investigate the factors that affect a miner’s ability to hear hazard and warning sounds (e.g., roof working, alarm signals, spoken communications, etc.). A service contract has been initiated to record and digitally store samples of typical warning sounds heard in an underground coal mine. This information will be analyzed in the lab to develop recommendations that can be offered to the mining community regarding correct earplug/earmuff usage to maximize there cognition of hazard and warning sounds while adequately protecting the miners’ hearing.

Jan 12, 2001

By Oliver C. Ralston

The Nonmetallic Minerals Division of the Bureau of Mines deals with all mineral substances not intended to be used as ores for extraction of metals, with the exception of the fuels. However, coal washing, the methods of which are highly Similar to the concentrating methods for ores, is in¬cluded In the work of the Nonmetallic Minerals Division to facilitate administration and to avoid duplication of equipment. During the fiscal year most of the work of the division was done at the experiment stations in College Park, Md., Tuscaloosa, Ala., and Seattle, Wash.

Jan 1, 1938

By Oliver C. Ralston

The Nonmetallic Minerals Division of the Bureau of Mines deals with all mineral substances not intended to be used as ores for extraction of metals, with the exception of the fuels. However, coal washing, the methods of which are highly Similar to the concentrating methods for ores, is included In the work of the Nonmetallic Minerals Division to facilitate administration and to avoid duplication of equipment. During the fiscal year most of the work of the division was done at the experiment stations in College Park, Md. Tuscaloosa, Ala., and Seattle, Wash.

Jan 1, 1938

By Douglas W. Fuerstenau

This report presents the results of an investigation of comminution in tumbling mills. Five different topics involved with ball mill and rod mill grinding kinetics were studied and the results analyzed in terms of phenomenological size reduction and transport models. Continuous rod mill grinding was found to be characterized by high Peclet numbers which permit simulation to be carried out by several methods. The dry batch ball mill grinding of mineral mixtures showed that the breakage rates of the components were composition-dependent but time-independent and were normalizable with specific energy. Locked-cycle tests on mineral mixtures showed that a grinding circuit may take a long time to attain steady-state, during which time the composition of the mill holdings, and hence the breakage rates of the components, continuously changed. This study revealed that under plant conditions, grinding circuits can be in transience perpetually. The transport of mineral mixtures through drums was found to exhibit complex size and/or density-dependent segregation. However, the grinding media in a ball mill can eliminate such segregation, thereby simplifying the modeling of the continuous grinding of complex feeds. Wet batch rod mill grinding on single minerals divulged that the normalizability of breakage kinetics is valid for slurries of constant pulp density at different hold-ups but cannot be extended to slurries varying in pulp density.

Jan 1, 1983

By P. L. Swanson

Stability analyses of fractured and faulted rock masses require delineation of the position, extent, and orientation of geologic discontinuities. The size of the smallest active discontinuity that may potentially be resolved using the spatial distribution of microseismic event locations is Limited by the accuracy and precision of the location methods. At a hard-rock mine in the Coeur D'Alene mining district of northern Idaho, two data sets consisting of calibration blast signals from a known source site and origin time and microseismic event signals were recorded using a stope-wide accelerometer array. These seismic signals are used to quantify various sources of error in event location. Five factors influencing source location errors are examined in this U.S. Bureau of Mines study: (1) biases of the numerical source location techniques, (2) receiver array geometries, (3) uncertainties in receiver positions, (4) errors in picking arrival times, and (5) uncertainties in seismic velocity structure, including the effect of mine openings. In addition, synthetic data (accelerometer positions, travel-time picks and wave velocity) are used to determine the effect of known systematic and random errors on source location calculations. It is shown that the commonly accepted association of minimum travel-time residuals with the best location solution does not necessarily hold true when there is a systematic error in seismic velocity. Recommendations are made for increasing the accuracy and precision of locations of microseismic events detected under similar field conditions.

Jan 1, 2010

By Oliver Q. Leone

Electrorefining tests using titanium-nitrogen alloys as anode material showed that no significant quantity of nitrogen was transferred to the cathode deposit. The nitrogen of the anode remained in the scale, and the titanium-nitrogen alloy was anodically insoluble in the electrolyte when the nitrogen content was 11 weight-percent.

Jan 1, 1966

By John Durkin

This report discusses the configuration and system deployment for the postdisaster surface seismic system for detecting and locating trapped miners. It analyzes the results of 15 field tests to define a signal model, background noise levels, and subarray performance. A waveform modeling procedure is described and compared with observed waveforms. The resulting similarity indicates that the major factors affecting the signal amplitude, waveform, and spectral character are understood. A model is presented which gives the sig-nal amplitude as a function of source type, source depth, and horizontal off-set between source and receiver. Using this model a curve is presented which gives the range at which a signal will be detected for different signal and noise levels. Finally, and most important relative to the mission of the system, the ability of the system to detect signals on one or more subarrays is put into a probabilistic framework. For a strong source it is almost certain that a subarray directly over the source will detect the signal. After signal processing, it is highly likely that signals will be detected on sufficient subarrays to locate the trapped miner. Location errors have been found to be less than 100 ft in the majority of cases. Techniques have been used that can reduce the location errors to this level even when soil layer variation between subarrays is severe.

Jan 1, 1981

The object of this program was to extend the capabilities of visual paging systems both in size and function. The system developed uses the mine pager phone line for communication, monitoring, and remote control. A central station, using a minicomputer, transmits signals by phase inversion modulation of a 16,384 Hz carrier to as many as 999 remote units. The remote unit addressed returns An echo to indicate that it is functioning and, in the case of monitor units, to convey the monitor data. Magnetically latched display dis[c]s, which can be seen from both sides when posted, are used for visual paging. Lists of the addresses of posted pages, unanswered pages, and non-echoing units are prepared by the central station computer. The system was designed to be intrinsically safe and should operate for three months on a 12-volt lantern battery.

Jan 1, 1980

By E. J. Lintner

This paper is one of a series being prepared by the United States Bureau of Mines describing cloy reining, crushing, and grinding methods and costs at various operations throughout the United States. These Toners are designed to disseminate technical information regarding methods used. The cost tabulations represent local operating expenditures only and not total production casts. Although the publication of total production cants might not be advisable in sore instances, yet a knowledge of operating costs is essential to the technical discussion end study of the methods employed. The attention of the reader is specifically coiled to this differentiation in order that no misunderstanding of the scope of the cost tabulations shall ensue. The following report deals specifically with the methods employed by the Clay City Fire Co., Uhrichsville, Tuscarawas County, Ohio.

Jan 1, 1936

By Larman J. Heath

Preliminary results of an explosive fracturing-solvent injection heavy oil recovery experiment conducted by the Bureau of Mines at a shallow oil reservoir near Bartlett, Kans., are given. Three wells 35 to 50 feet apart were drilled to a depth of 360 feet, and an open hole interval from 300 to 350 feet in the Bartlesville Sandstone Formation was explosively fractured with 3,000 pounds of pelletized TNT in each well. Laboratory tests were made on cores obtained from these wells to confirm the suitability of using an aromatic-type solvent. Injection of a 74-percent aromatic solvent was begun into one well and continued intermittently for approximately 2 months. Crude oil production amounted to 29.6 bbl, or 11.7 percent of the total oil con¬tained within the three-well interwell zone.

Jan 1, 1972

By Wils L. Cooley

Several aspects of mine safety grounding systems and equipment are studied. Electrolytic corrosion of test ground beds has shown a high incidence of stray current damage, while efforts to build a reliable continuous ground bed monitor continue. Laboratory and field investigations of trailing cable splices have yielded strong evidence that splices can contribute to stray current problems in the mines, but a method is suggested for discovering deteriorating splices before they pose a serious hazard. A prototype device has been constructed to evaluate the electrical resistance of rail bonds underground as a source of stray current. Theoretical modeling of ground electrodes, has advanced considerably, now covering measurements of large cylindrical electrodes, multiple-rod ground beds, rod electrodes in stratified earth, and measurement of connected beds. A prototype instrument design is given for a potential gradient plotter to quickly evaluate voltage gradients near earth electrodes. Additional ground-check monitor testing is reported.

Jan 1, 1977

By W. A. Selvig

"The tests described in this paper were conducted under the sponsorship of Subcommittee VII on Pulverizing Characteristics of Coal, a subcommittee of Committee D-5 on Coal and Coke, American Society for Testing Materials, with a view to evaluating various laboratory procedures for testing grindability of coal in connection with commercial pulverization of coal for use as powdered fuel. The subcommittee, at a meeting in New York City on February 21, 1934, selected for test four methods that had been developed during the past few years for testing grindabilitay of coal and were being used by coal-testing laboratories in the United States and Canada. These methods are:Bureau of Mines method, Cross method, Fuel Research Laboratory method, and Hardgrove method. Subcommittee VII agreed that the grindability tests should be made on five coals selected to cover a wide range of hardness. The Pittsburgh Experiment Station, Bureau of Mines, was asked to direct the investigation and to prepare representative samples of the coals. Laboratories of the fol. lowing institutions and companies agreed to cooperate by making grindability tests: Babcock & Wilcox Co., Foster Wheeler Corporation, Fuel Engineering Co., of New York, Fuel Research Laboratory of the Canada Department of Mines, and Northwest Experiment Station of the Bureau of Mines.ACKNOWLEDGMENTSHelpful suggestions in planning the investigation were made by A. C. Fieldner, chairman, Committee D-5 on Coal and Coke, A.S.T.M., and chief engineer, Experiment Stations Division, U. S. Bureau of Mines, Washington, D. C., and E. B. Ricketts, research engineer, New York Edison Co., New. York City.The coal samples were supplied through the courtesy of floats, Wheeler Corporation, New York City; Philadelphia & Reading Coal & Iron Co., Pottsville, Pa.; Pittsburgh Coal Co., Pittsburgh, Pa.; and Pocahontas Fuel Co., Inc., New York City."

Feb 1, 1936