Search Documents

By Ruth F. Brinkley

This report is the 18th of a series of reports originally issued annually, and more recently bienially, to acquaint the public with the work of the Federal Bureau of Mines in explosives technology. Part I reviews briefly the overall activities during fiscal years 1957 and 1958.4/ Part II presents in abstract form the publications prepared by the Bureau that appeared during the period.5/

Jan 1, 1961

By D. E. Wolfson

As a part of its overall program of coal carbonization, the Bureau of Mines is studying the coking properties of coals that may be used for metallurgical purposes. The objectives of this study were given in detail in a previous report The inherent suitability of coal for metallurgical purposes depends primarily on (1) chemical composition, (2) preparation characteristics, and (3) carbonization behavior. The first two factors, Be well as the amount of available reserves, are considered in selecting coals for carbonization tests. The selection of coal beds in Harlan County, Ky., for coking tests was based, in part, on recent studies of coal reserves by Wallace,3/ who estimated the recoverable reserves in beds 28 inches or more thick, in tons, as follows:

Jan 1, 1956

By G. B. Shea

"INTRODUCTION Much of the recent progress in increasing the efficiency of oil-well performance can be attributed to advancements in the art of cleaning wells. Through research and development by operators and service companies during the past decade, significant improvements in the application of engineering and chemical principles to well-cleaning technology have widened greatly the scope of ""clean-out"" methods to the end that greater ultimate recovery of oil will be attained.This report reviews recent improvements and developments on this important problem in California; it describes also the use of various methods and tools for cleaning wells to stimulate or revive their productivity. Developments in preventing and removing mud sheaths in well-completion operations also are described. The report is based on a field survey, supplemented by data from the technical and patent literature and from manufacturers' catalogs, which contain much valuable information.In preparing the material for publication as a Bureau of Mines report, the author has been fully aware of certain limiting conditions that attend the discussion of a subject such as that treated in this report. The following are examples:1. To a considerable extent, well cleaning in California is done with tools rented from service companies, and their representatives and employees are specialists in jobs of this type. They usually have working experience with their own equipment and methods which greatly exceeds that of persons whose interest has been casual or who have had no opportunity to study the subject in detail in actual practice. Many of the tools and methods are covered by letters patent for the protection that may be in developing and successfully applying these mechanical and chemical means of increasing the production of wells. Frequently several years have been required to perfect a given tool or technique, requiring relatively large investments to establish a service that is remunerative to those who have primary interest in a certain development and at the same time attractive enough to the operators of producing properties (because of greater quantities of oil delivered into the flow tanks) to warrant employment of or contractual agreements with a particular service group."

May 1, 1943

By Richard H. Bares

The general or macroclimate of the study sites in western North Dakota is characterized by rapid and sometimes extreme daily and day-to-day temperature fluctuations, rainfall patterns which are erratic in spatial and temporal distribution and intensity, generally low relative humidity, plentiful sunshine, nearly continuous air movement, and a relatively short frost-free period. Of particular relevance to plant growth and productivity is the mosaic of microclimates: these microclimates are affected by landform (convex and concave surfaces); exposure; slope angle, length and aspect; soil color, texture and surface cover (litter), and vegetation cover. The most critical plant growth governing factor in this region is available water. It is determined principally by water input (precipitation) and water loss (evapotranspiration) which is increased by high temperatures, wind, and poor litter and vegetation cover. While spring and fall precipitation is generally gentle and soil-soaking summer rains frequently come in the form of intensive, soil-washing, localized convective thunderstorms of short duration. Due to the convective nature of these storms, summer rainfall is particularly affected by regional topography; southwest slopes and crests often receive more rainfall since these storms usually move in a northeasterly direction. The water loss due to runoff and consequent soil erosion arc major problems resulting from such "cloudbursts". Previous fall precipitation (September - October) when added to current seasonal precipitation (March - August) was found to be significantly correlated (r-.93) with plant production. Winter precipitation (snowfall) is relatively light as the prevailing weather is dominated by dry polar air masses from the north. The nearly continuous wind is responsible for removing snow from open exposures and depositing it in depressions and windbreaks. Although the winter precipitation is not a large component of the total annual precipitation, conservation of that which does occur would contribute to plant production during the following growing season. Generally clear skies over the region facilitate receipt of abundant sunshine at the earth's surface. While good for early season soil warming and plant photosynthesis, this abundant sunshine coupled with long days and nearly continuous wind is responsible for evapotranspiration exceeding precipitation by an average of six inches between June' and September. On a local (micro) scale, the water deficit is most severe on the southern exposures which receive the most direct (most effective) solar radiation and therefore are warmer than other exposures. On a broader scale, it was found that ambient temperature extremes were slightly but significantly greater in the town of Beulah in the Knife River Valley than at the upland test sites, This may have been due to the difference in topography and/or the "urban heat island" effect. It is known that air temperatures in large cities may be 2° to 4°C higher than that of the surrounding countryside. It is also well known that basins, depressions or valleys are sinks for cold air masses and are often subject to frosts not occurring on adjacent upland sites.

Jan 1, 1982

By Joseph Daniels

[Adequate supplies of suitable coal and coke are prime requisites in many industries, particularly those dealing with the utilization of mineral resources, recently interest has been focused on the possibilities of using electricity produced at Bonneville and Grand Coulee, Wash., in many electrochemical and electrometallurgical processes, in which core or some form of carbon is necessary in addition, discussion has been revived on the possibility of making iron and steel by the conventional methods employed in blast and open-hearth furnaces. The subject also is important at this time because of its relationship to industrial preparedness for national defense. A supply of coke from local sources on the Pacific coast is necessary in any program of production for strategic sufficiency of certain materials. An anal trio involving tae establishment of such industries should include detailed data on available supplies of coal, the quality and properties of the coke produced, and the technologic and economic factors involved in manufacture of echo and disposal of byproducts.]

Jan 1, 1941

By Yi-Shen Li

This report has been prepared by Lockheed Missiles & Space Company, Inc. (LMSC), under United States Bureau of Mines Contract No. H0220040 dated 21 June 1972 for the design, development, fabrication, and certification of the One-Hour Self-Rescue Breathing Apparatus (PBA). The PBA is a self-contained, oxygen-generating, CO2-removing closed-loop breathing apparatus that provides a minimum of 1 hour of breathable atmosphere during escape from a mine with a contaminated or oxygen-deficient atmosphere. This Cost-Plus-Fixed-Fee (CPFF) contract has been successfully completed in a three-phase program. The Phase I tasks included the design, development, and fabrication of prototype units developed at LMSC in accordance with the requirement of the Code of Federal Regulations (CFR) Title 30, Chapter 1, Subchapter B, Part 11 (Appendix A), and was submitted to the National Institute for Occupational Safety and Health (NIOSH) for joint NIOSH and Bureau of Mines certification testing.

Jan 1, 1974

By T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

This Technical Memorandum Report is a collection of three working memoranda, prepared during the course of our work for the bureau of Mines and hound together for convenient reference. These working memoranda present preliminary performance estimates, for baseband voice and narrowband through-the-earth electromagnetic communications systems of principal interest to the Bureau, for operational/emergency mine communications. The calculations were prepared to obtain early indications of the feasibility and governing parameters of such communications systems. They are based on limited, but pertinent, coal mine electromagnetic noise data acquired to-date by Bureau of Mines contractors; and of theoretical signal-attenuation characteristics for two transmitter antenna types of present interest to the Bureau. The memoranda examine the cases of baseband voice and narrowband communications for uplink and downlink transmissions, for frequencies up to 3kHz. Downlink transmissions are via a horizontal wire antenna, up-link transmissions via a vertical-axis loop antenna, for typical mine depths of 300, b00, and 1000 feet. Representative coal-mine overburden conductivities of 10-2 mhos/meter (moderate and common) and 10-1 mhos/meter (high) were used; 10-2 for voice and narrowband, 10-1 for narrowband only. Examples of high, moderate, and low; surface and subsurface; harmonic and broadband-impulsive noise conditions were taken from NBS and Westinghouse (WGL) mine noise data, together with examples of high- and low-levels of ELF atmospheric noise taken from M.I.T. Lincoln Laboratory data.

Jan 1, 1972

By P. R. Tisot

Structural response and/or deformation was determined for each of four different grade Green River oil shales (27.0-, 34.5-, 45.5-, and 63.5-gal/ton) as they were heated in an inert atmosphere, under constant compressive stress, from ambient to subretorting temperatures; that is, below those required for rapid pyrolysis of the organic matter. Small cores and small columns of confined fragments comprised the test specimens, which were heated, in a specially designed microunit, at a uniform rate either to 725° or to 825° F under three different stress levels, 80, 200, and 325 psi. Structural response of some cores was observed as they were heated in a stress-free environment. The obtained stress-strain-time-temperature relationships provide information regarding the oil shale's yield temperature, yield stress, rate of compressive strain, loss of mechanical strength, and nature of structural deformation. Effects of structural deformation on induced permeability in small columns of fragments are presented. Results indicate that underground retorting of Green River oil shale may be seriously impaired through loss of induced permeability brought about by structural deformation of rich oil shale under the influence of heat and compressive stress.

Jan 1, 1971

By N. H. Snyder

THE Bureau of Mines has been active in promoting the purchase of coal for Government use under specifications that define the requirements in terms of heating value of the coal, expressed in British thermal units, and the com-position as shown by proximate analyses. To these, when required, are added the fusing temperature of ash, Hardgrove grindability index, and the free-swelling index. Under most of these specification contracts the bidders guarantee the quality of coal, and that guaranteed by the successful bidder becomes the standard of his contract. The deliveries are sampled in accordance with instructions 4 issued by the Bureau; the samples are analyzed in the Bureau's laboratory to determine whether the coal is of the quality guaranteed by the contractor and, if it is not, a price adjustment is made. Analyses of delivered coal and "tipple" samples (samples collected at mine tipples as coal is being loaded into railroad cars or trucks) are valuable data for use in evaluating future bids. Moreover, the continuous sampling of coal as delivered is a check on the practical results obtained in burning the coal.

Jan 1, 1953

By M. J. Ferrante

High-temperature enthalpy and X-ray powder diffraction studies were con-ducted on aluminum sulfide (Al2S3) as part of the Bureau of Mines effort to provide new data for the advancement of mineral technology consistent with environmental preservation and energy conservation. Relative enthalpies were measured with a copper-block calorimeter from 298.15 to 879 K. Tabulated values are listed for heat capacity, entropy, Gibbs energy functions, and relative enthalpies between 298.15 and 900 K. Enthalpies were also given in the form of an equation and combined with published data to calculate standard enthalpies of formation and Gibbs energies of formation for reactions of crystalline aluminum with crystalline, liquid, and gaseous diatomic sulfur. The hexagonal, rhombohedral, and cubic phases of Al2S3 were identified by X-ray powder diffraction studies, and the indexed powder diffraction patterns of these phases are given. The hexagonal phase was stable to about 852 K and was partially converted to the rhombohedral form at 879 K.

Jan 1, 1981

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 Boyd Wise

A jet pump injector was developed and successfully tested, thereby demonstrating the feasibility of a jet injector for introducing coarse coal into an operating slurry face haulage system: In Phase I a variety of injection concepts were evaluated, and the jet pump was identified as best, due to its simplicity, compactness and performance potential. In Phase IIA subscale jet pump injector tests were conducted, and a computer model of a jet pump injector was developed whose performance predictions correlated well with subscale test results. In Phase IIB various system configurations were defined for integrating a jet pump injector into a fully operational underground coarse slurry face haulage system, further highlighting the feasibility and practicality of such a system. In Phase III a full-scale mobile haulage vehicle embodying a jet pump injector and coal sizing equipment was detail designed into a practical vehicle with attractive performance characteristics. More importantly, fully operational full scale jet pump injector -and feeder/breaker subassemblies were tested and proven successful in their ability to down-size coal to 3" in all 3 dimensions and to consistantly provide slurry of 4217 weight concentration at 6.4 TPM throughput under a wide range of operating conditions including zero to maximum feed rate within 5 seconds.

Jan 1, 1985

By M. Clair Smith

This report is one of a series being prepared by the Bureau of Mines on exploration, development, mining methods, and costs at various open-pit mines in the United States. These reports have been prepared in cooperation with various mining companies. A similar program, conducted from 1928 to 1939, was generally conceded to have contributed to improving the efficiency of mining operations. The purpose of these reports is to promote development and conservation of our mineral resources by disseminating technological information on mining methods and practices. This report describes exploration, development, equipment, and mining by open-pit methods of the remainder of an ore body that had been previously worked by underground methods. The Tripp pit of the Consolidated Coppermines Corp. is located at Kimberly, Nev., a small mining company town having an elevation of 7,250 feet, 9 miles by road west of Ely, Nev. (fig. 1). The pit extends over the area formerly mined by underground methods from the Morris and Brooks shafts.

Jan 1, 1962

By Michael J. Beus

This Bureau of Mines report describes a tunnel stress relaxation gage (TSR) developed to measure initial radial displacement around full-sized underground openings. The TSR technique was shown to be a valid concept in previous field verification tests. Sensitivity has been improved by employing a titanium alloy cantilever in the transducer head, which also permits a deeper sensor location. Use of improved fabrication methods such as stainless steel bellows and sputtering techniques and use of an environmental chamber for testing greatly increased overall reliability. A miniature data acquisition system (DAS) was interfaced directly to the transducer for increased versatility and containment entirely within a borehole. The present TSR system is suitable for use around full-size underground excavations, particularly machine-bored openings. Field evaluation of the improved instrumentation verified the design goals.

Jan 1, 1978

By J. Kruttschnitt

This paper, describing the mining operations at Mount Isa Mines, is one of a series covering mining methods and costs being published by the United States Bureau of Mines. The Mount Isa property has been in operation since June 1931; during this period operations have changed from the production and treatment of carbonate ores to the mining, milling, and smelting of sulphide ores. This change involved revision of ore-extraction methods. Stoping methods have been designed to apply to parallel lodes ranging from 10 to over 100 feet in width and dipping at 50° to 60°. The hardness and strength of the ore and enclosing wall rocks, together with the strength and thickness of the country rock between lodes, have permitted the selection of a sublevel stoping method for mining the sulphide ores.

Jan 1, 1937

By Liming Yuan

A study of the ignition of non-fire-resistant hydraulic fluid sprays was conducted by the National Institute for Occupational Safety and Health. Both an open flame and a hot steel surface were used as the external heat sources. With the open flame as the heat source, the minimum oil temperature and minimum spray nozzle pressure that resulted in an ignition were measured. The effects of the distance between the open flame and the nozzle and the nozzle orifice diameter on the ignitability of the hydraulic fluid sprays were examined. With the hot surface as the heat source, the minimum surface ignition temperature was determined. The degree of oil atomization and the relative direction of oil injection with respect to the hot surface are discussed. The ignition of oil sprays from the impingement of oil jets onto a vertical surface was also investigated. Finally, the results are compared with those obtained for fire-resistant hydraulic fluids. Keywords: Ignition; hot surface; open flame; hydraulic fluid

Jan 1, 2006

By Lloyd A. Morley

The primary goal of this research report is to discuss safety considerations involved in the use of lead-acid batteries for traction purposes in underground coal mines. In order to arrive at the objective, the topic of battery safety has been divided into two specific areas. The first deals with the fact that batteries emit hydrogen gas during and after the charge cycle. Hydrogen gas can be the source of dangerous explosions or mine fires. The second major topic deals with the electrical nature of the battery and battery-charging systems, which also provides a source of mine fires as well as electrocution hazards. In addition to the discussion on battery safety, a literature review has been undertaken to acquaint the reader with some basic concepts inherent to the battery usage process. The result of this research is a set of design specifications and procedural recommendations directed at improving the safety factors inherent in any underground battery usage scheme.

Jan 1, 1977

By Edward J. Caldwell

In 1930 the Bureau of Mines published a description3/ f the concentrating process of the Magma Copper Co. as it had been developed to that time and was then employed. The prevent paper revises the description to the end of 1943 and includes a description of the smelting processes. Data from the mild and smelter operations for, 1942 are given in tables 1 to 14, Billing costs are included, but it is not permissible to publish smelter costs.

Jan 1, 1944

By Stephen C. Tadolini, Steve Bessinger, James Pile, Christopher Mark

The San Juan Coal Mine, located near Farmington, New Mexico, supplies the San Juan Generating Station with more than 6 million tons of coal annually. To replace dwindling surface mine production, San Juan installed a longwall in 2002. The roof rock in much of the underground reserve consists of interbedded coals, carbonaceous shales, and mudstones. Roof support consists of fully-grouted roof bolts, both tensioned and non-tensioned, supplemented by modified cable trusses. Short-encapsulation pull tests conducted by San Juan’s geotechnical engineering department showed that some of the immediate roof layers provided variable bolt anchorage. To ensure that the roof bolts were obtaining the necessary anchorage, additional tests were conducted in a variety of locations. The results have been used to determine the optimum support design for different areas of the mine. Another series of tests evaluated the performance of several bolt and hole diameter combinations. The experience at San Juan Mine shows that short-encapsulation pull tests can provide the information necessary to improve ground control in variable roof conditions. It also illustrates how a pro-active geotechnical engineering program can be an essential component of a state of the art underground coal mine.