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By C. Daniel Kealy

Finite-element,, mathematical models that solve LaPlace's and Richard's equations numerically were used to locate the phreatic surface within tailings pond embankments and to define the subsurface flow of water from the pond. Both must be known to design structurally and environmentally safe tailings dams. The permeability distribution within and beneath the embankment, the fluid potential values upgradient and downgradient from the embankment, and the geometry and elevation of an approximately impermeable layer at some depth beneath the embankment were used as computer inputs in analyzing over a dozen finite-element models of tailings dams varying structurally from simple to complex. Results predicted with the finite-element model were confirmed with measurements in a laboratory model of a tailings pond and in the field. Of particular importance to the design of safe slopes, all data indicated that the phreatic surface within a tailings dam is concave upward, a configuration opposite that in most earth dams. The close correlation between predicted and experimental values confirmed the practicability of using the finite-element technique to design safe tailings dams.

Jan 1, 1971

By Jeffrey A. Shibe

A prototype Fire Safety Evaluation System has been developed and is ready to be evaluated by a Peer Consulting Panel and for performing field tests. The system can be used to determine combinations of widely accepted fire safety equipment and under-ground coal mine features that provide a level of safety equivalent to those required by the Code of Federal Regulations-Title 30 for underground coal mines. In this evaluation, equivalent safety performance is gauged in terms of overall level of safety provided rather than by a component by component comparison.

Jan 1, 1987

By Valois R. Shea-Albin

Ground control problems are an important factor affecting safety, production, and efficiency in underground coal mines. A major portion of ground control problems encountered in underground coal mines can be attributed to geologic features in the strata surrounding the extracted coal seam. The U.S. Bureau of Mines has compiled information from numerous sources on the geological features that contribute to ground control problems in underground coal mines. The compilation includes (1) sedimentary features such as paleochannels, crevasse splays, clastic dikes, mold-and-cast structures, concretions, and lithologic factors, and (2) structural features such as folds, fractures, joints, cleat, and faults. The compiled information will aid in identifying the features, predicting their occurrence in advance of mining, and controlling or minimizing roof failure when these features are encountered in an underground coal mine.

Jan 1, 1993

By R. S. Dean

In general, the Division conducts investigations relating to the treatment of ores and metallurgical products from the condition to which they are mined to the refined metal. At the object of conserving natural resources and eliminating waste by furnishing information on current methods of metallurgical practice making fig fundamental studies of metallurgical processes and developing new processes and alloys to the point of demonstrating their or value. Office of the Chief Engineer The functions of the technical units of the Office of the Chief Engineer are indicates

Jan 1, 1941

By Earl C. Redman

The Juneau Gold Belt, centered on Juneau and approximately 120 miles long by 10 miles wide, stretches from Berners Bay on the north to Windham Bay on the south (fig. D-l). Access within the Juneau Gold Belt is provided by the Glacier, Thane, and North Douglas Highways. The Glacier Highway extends northwest from Juneau for approximately 40 miles to Echo Cove, and the other two roads end 5.5 miles southeast and 12.6 miles west from Juneau, respectively. None of these roads connect with other highway systems and access to other areas is restricted to airplanes, the State ferry system, and commercial barge lines. BUREAU ACTIVITIES The majority of lode gold produced in Alaska came from the Juneau Gold Belt portion of the Juneau Mining District. To evaluate the economic potential of the Gold Belt, the Bureau located 173 mines and prospects within the area. A total of 263 ad its and shafts were found and 56,650 feet of underground workings were mapped. The Bureau collected and analyzed 1,557 samples during the study. In addition, considerable detailed geologic map-ping was done in the vicinity of the mines and prospects from which ore control models were developed.

Jan 1, 2012

By John C. Machisak

THIS CHAPTER of the Minerals Yearbook (Volume III) contains overall injury experience for coal mines, both anthracite and bituminous, coke plants, petroleum and natural gas, peat, and asphalt and related bitumens (native); metal mines, their metallurgical plants, including ore-dressing plants and primary nonferrous reduction plants and refineries; nonmetal mines; nonmetal mills; sand and gravel operations; slag (iron blast-furnace) plaints; and stone quarries and their related pants. Volume I of the yearbook contains a chapter showing injury experience and employment data treated separately by metal mines, nonmetal mines, quarries and their related plants, metallurgical plants (ore-dressing plants and primary nonferrous reduction plants and refineries are shown separately), nonmetal mills, sand and gravel plants, and iron blast-furnace slag plants. Volume II contains injury and employment experience in the fuel industries (coal, coke, petroleum and natural gas, asphalt and related bitumens (native), and peat. Injury and employment data are submitted voluntarily for the mineral operations through an industry canvass made by the Bureau of Mines, except for the coal industry, whose reports are mandatory. Information published in this chapter is the result of this canvass. Figures presented in this chapter for 1961 are preliminary except for anthracite, peat, coke, petroleum and natural gas, asphalt and related bitumens, and slag. These preliminary data, with the exception of bituminous coal, are a summation of reports received by May 31, 1962, from the operators showing their injury and employment experience. Estimations of injury and employment experience are not included in these preliminary data.

Jan 1, 1962

By Thomas O. Glover

Cameroon continued to enjoy sustained economic growth that began with its independence in 1960. Growth in the gross domestic product (GDP) averaged 2.8% per year during the 1960's and the first half of the 1970's. Starting in 1976 and for the succeeding 10 years, the GDP accelerated rapidly owing to the coming on-stream of Cameroon's small but domestically significant offshore oil industry. In 1985, the GDP grew by 7.8%, but in 1986, it was only up 5.5%. The country's sustained economic growth in dollar terms of gross national product (GNP) per capita reached $1,075 in 1986. The ranking in GNP per capita by the International Monetary Fund put Cameroon in the middle-income category for developing countries. The sustained economic growth rate up to 1986 was due to the injection of income from oil into the economy, but crude oil price reductions in 1986 brought a slowdown. In 1986, crude oil production grew to 200,000 barrels per day, an increase of 8.2% from that of 1985. Most of the oil came from the Société Nationale Elf Aquitaine (SNEA) wells in the multifield Rio del Rey complex. Additional output came from the Moudi Field operated by Compagnie Française des Pétroles S.A. Proven oil reserves in Cameroon were 540 million barrels. At 1986 production rates, and in the absence of further discoveries, Cameroon will have exhausted its recoverable oil reserves by the year 1995. Owing to worldwide crude price reductions, the country's oil income fell 60% between 1985 and 1986, from $1.82 billion2 to $0.72 billion. Cameroon's refinery operator commenced operating the Sonara refinery in 1981 at Point Limboh. Sonara's capacity of 43,000 barrels per day was small by most standards. In 1986, natural gas reserves, estimated at 100 billion cubic meters, were not produced commercially because there were no domestic users. Proposals for a multibillion-dollar liquefied natural gas plant at Kribi had been submitted; however, work on the plant had not commenced.

Jan 1, 1988

By Patrick J. Cain

The fatigue-failure characteristics under high-frequency (10 KHz) cyclic loading were determined for a marble, granite, and quartzite. The rock speci-mens were cyclicly loaded (using a high-power piezoelectric sonic transducer) at a constant strain amplitude generated by forming a longitudinal standing stress (strain) wave in the cylindrical test specimen. The number of load cycles required to fail each rock type at a given strain amplitude was deter-mined. The fatigue fractures were tensile in nature and the fracture load amplitudes were as low as 30 pct of the static tensile strength. Also the internal heating of the rock caused by the material damping (internal friction) was measured. The damping and internal heat generation in the specimens was analyzed to show that nearly all of the power input can be accounted for as a change in enthalpy in the specimen. Using these results the thermal strain in the rock was calculated to evaluate its contribution to fatigue failure. The thermal strain was found to range up to 30 pct of the dynamic strain amplitude depending on the load amplitude and the number of load cycles. The specific energy required for failure was determined and possible applications of the high-frequency fatigue fragmentation process are discussed.

Jan 1, 1975

As part of the United States Department of the Interior, Bureau of Mines Health and Safety Research Program, Walter C. McCrone Associates, Incorporated has examined 71 samples of airborne mine dusts using the techniques of x-ray diffraction, electron microprobe analysis and light microscopy. This report details the procedures which were used in this work and documents the results which were obtained.

Jan 1, 2011

The Bureau of Mines has sponsored a comprehensive research program to enhance the safe, effective, and efficient use of blasting technology by the mining industry. Recent research results of the surface mine blasting program were presented at a seminar on April 25, 1987, in Chicago, IL. Many of the topics discussed at the seminar are presented in this proceedings. The new research described in these papers includes computer monitoring of rock motion, the influence of blast delay times on rock fragmentation, blasting effects on Appalachian water wells, blast vibration measurement near structures, and the reduction of accidents through improved blasting safety.

Jan 1, 1987

By Frank E. Cash, Max S. Petersen

The use of safe equipment, safeguards, and safe practices in the mining and allied industries should reduce injuries and improve accident experience. The object of this report is to give to the mining industry, especially metal mining, a graphic pictorial description of some of the safeguards, equipment, and practices used and followed in the iron-ore mines of the Lake Superior district. Some of the subject material has been in use or has been established for many years, and some is relatively new. Some of the equipment was purchased commercially, and some was designed by the company employees and constructed in the mine shops. The photographs were taken by the personnel of the Health and Safety Division of the United States Bureau of Mines, primarily for use in the Metal-Mine Accident-Prevention Course of the Bureau of Mines. In general, they are arranged under the following headings or subjects: 1. Accident statistics. 2. Support of ground. 3. Hoisting and haulage. 4. Explosives. 5. Fires, gases, and ventilation.

Oct 1, 1948

By J. S. Miller

The Bureau of Mines conducted surface tests to determine the feasibility of using liquid explosives for underground rock fracturing. The effects of configuration, confinement, length, critical layer thickness, and fracture-propping sand on detonation and explosive propagation velocity of desensitized nitroglycerin were studied, using polymethyl methacrylate and glass-plate reservoirs through lengths from 3 to 12 ft, with explosive-layer thicknesses from 0.1875 to 0.0312 in and in aluminum tubes 8 ft long with diameters from 2.000 to 0.125 in. Interval and continuous detonation velocity data were obtained. Under the test conditions detonation velocity was dependent upon explosive confinement and fracture-propping sand. The detonation velocity of a confined nitroglycerin explosion in aluminum tubes can be reduced by as much as 85 percent, when the tube contains fracture-propping sand. The shape of the reservoir, whether triangular or rectangular, has little effect on the detonation velocity or explosive propagation. The critical or minimum explosive-layer thickness between glass plates, capable of supporting propagation, was 0.0312 in. The presence of a fracture-propping sand in the sheetlike layers increased the critical explosive layer thickness to 0.0625 in. In nitroglycerin-filled and nitroglycerin-sand filled tubes, the minimum tube diameters successfully tested were 0.125 in and 0.375 in, respectively.

Jan 1, 1969

By Raja V. Ramani

The potential usefulnuss of reclaimed surface-mined land has received much attention in recent times. This attention is partially due to the establishment of federal environmental reclamation standards but concern for achieving better land uses has also been shown by interested members of the mining industry. In an effort to develop a procedure for evaluating postmining land use potentials, specific mines in various regions of the U. S. were studied to determine the extent of current mined-land planning and to discover characteristics that are regional in nature. As part of this investigation, a 430-acre surface mine in Clear-field County, Pennsylvania has been studied. Established site planning principles have been applied to the case study site including formation of a data base, development of alternate land use plans, and evaluation of the economic, environmental, and social impacts of the land use alternatives. Key factors affecting site realization have been identified along with positive suggestions for applying land use planning processes to mined-land planning.

Jan 1, 1983

By Ernest W. Johnson, F. E. Cash

"INTRODUCTION Mine operators have long realized the importance of providing a satisfactory and dependable means of giving prompt warning to underground mine workers at the occurrence of a mine fire or other threatened disaster.Most underground mines of the Lake Superior district are prepared to inject a stench liquid into the compressed-air system quickly to give such warning. The liquid evaporates quickly and gives off an intense and easily recognizable odor even when present in minute quantities in the mine air. Workers in the mines studied have been fairly generally familiarized with the odor and instructed as to evacuation procedure when the warning odor is detected.In some mines provided throughout with electric lighting, including working faces, a prearranged light-flashing signal is given as a warning supplementary to that received from the stench.In a few mines, workers have been instructed to evacuate the mine immediately in the event the compressed-air supply is cut off, regardless of whether mechanical failure may be involved.Information obtained in observing a number of stench-injection tests is compiled and presented in the hope-that it will serve as an incentive to provide means of making stench injections at mines not now so equipped and for making similar tests at other underground mines, so that in case unsatisfactory results are obtained rectifying adjustments or changes may be made in time. It is further hoped that this paper will bring out the real importance of repeating these tests from time to time, at least once a year on each operating shift, so that in the event of an actual emergency, underground employees will receive a prompt warning."

Nov 1, 1945

By R. K. Linn

The New Idria Mining and Chemical Co. owns and operates the New Idria mine in southern San Benito County, Calif. During 1957-59, the New Idria mine was the largest producer of mercury in the United States and its alltime production of over a half-million flasks was exceeded only by one mine. It is one of the oldest and most consistent producers in California. With the exception of 1921-22, the mine has an annual production of mercury dating back to 1854. This paper by the Federal Bureau of Mines describes the exploration, development, mining, and furnacing of mercury ore at the New Idria mine. Figure 1 is a view of the furnace plant of the New Idria mine. The purpose of this report is to promote the development and conservation of our mineral resources by dissemination of technological information on mining and processing procedures, and related practices at operating mines.

Jan 1, 1961

By Eldon C. Pattee

Reconnaisance samples of reported beryllium occurrences in Idaho, Washington, Montana, and Oregon were chemically and spectroscopically tested in a mobile laboratory. The two predominant types of occurrences were green beryl associated with Cretaceous intrusions and disseminated aquamarine associated with Tertiary intrusions. Although the beryllium content of known deposits in the Northwest is too low for economic development at present, total submarginal-grade beryllium resources in pegmatites are estimated to be 570,000 to 1,870,000 tons containing 0.024 to 0.167 BeO. A potential source of 500,000 to 700,000 tons of beryllium-bearing tactite in Idaho and Montana averages 0.033 to 0.080 percent BeO.

Jan 1, 1968

By Edward G. Cunney

Track in underground bituminous coal mines was investigated and technology was taken from other industries in order to obtain information on conditions that impair the safety and efficiency of the track and to develop guidelines and useful information on the construction, inspection and maintenance of mine track. Volume 1 contains information on the investigations, observed track conditions, useful technology from railroads and other industries, derivations of track condition descriptors and limits, conclusions, and recommendations. Volume 2, Guidelines, contains recommended standards and practices for mine track. It includes the relation of track conditions to safe speeds; descriptions and limits for measurable track features, such as gage; descriptions of conditions for track components that are normally not measurable, such as subbase soils; construction requirements and techniques; inspection requirements and methods; and methods for managing and performing track maintenance work. It does not repeat the summary or? derivations. Volume 3, Inspection Handbook, summarizes recommended standards and procedures from Volume II and provides related information for ready reference by inspectors in the mines. As a research product to be used in mines, it does not repeat the summary, derivations or references.

Jan 1, 1977

By LeRoy D. Loy

The disposal of excess overburden from surface mining can be accomplished by use of a reclamation technique entitled head-of-hollow or valley fill. This report attempts to assess current valley fill regulations and practices, identifies inherent benefits and deficiencies, and develops concepts to enhance fill technology.

Jan 1, 1978

By R. S. Dean

The original flotation reagents were certain oils selected for a combination of properties that occurred fortuitously. It was recognized quite early in the study of flotation mechanism that, in order to function, an oil must have an active group-one that differs from the remainder of the molecule in its affinity for water or the mineral particle. Wark4 gives credit for recognition of this elementary chemical principle to the senior author of this report.5 However, it was soon found that simple hydrocarbons could not be used as flotation reagents and that two of the functions, which were combined in the early flotation oils such as pine and eucalyptus, could be obtained in separate compounds and their relative intensity controlled to advantage. These two functions were called collecting and frothing.

Jan 1, 1944

By Richard E. Thill

Elastic wave velocities and moduli were determined by both the pulse and resonance methods in a large number of specimens of St. Cloud Gray Granodiorite and Tennessee marble under the same moisture, temperature, and stress environment. Long cylinders were first tested by the resonance method to obtain longitudinal bar and torsional wave velocity. The cylinders were then sectioned in half and tested by the pulse method to obtain the transient pulse velocity. These velocities were later used to obtain various moduli for comparison. Statistical comparisons between the Young's, shear, and bulk moduli and Poisson's ratios obtained independently by the pulse and resonance methods indicate that the methods do not give equivalent results in nearly isotropic rock. The amount of difference varies for each modulus, with the least difference (less than 5 pct) occurring in the shear modulus and the greatest difference (as high as 34 pct) in the bulk modulus. Moduli determinations in aluminum show much closer agreement between the pulse and resonance methods than in rock. The discrepancy in pulse and resonance results probably is caused by frequency dispersion effects and by differences in error sensitivity in the various formulas used to calculate the moduli.

Jan 1, 1974