Search Documents

By R. L. F. Kay, T. A. Fletcher, A. J. Boyce, C. M. Rice

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The synorogenic, mafic Ordovician intrusion comprises orthopyroxene-rich xenoliths and mafic-ultramafic cumulates with low-grade pyrrhotite, chalcopyrite and pentlandite mineralisation. Despite abundant textural, mineralogical and O isotope evidence for significant assimilation of country rocks, S isotopes indicate only a modest uptake and suggest that mineralisation is dominated by magmatic sulphur. The preferred explanantion is that the magma was close to S saturation on emplacement. Uptake of elements such as Si and O led to early crystallisation of orthopyroxene, resorption of olivine and early segregation of a sulphide liquid. Post-magmatic interaction with a high-temperature, surface-derived fluid, whose movement may have been controlled by regional shear zones, reset biotite and whole-rock O isotope values but not those of orthopyroxene. This model identifies the presence of olivine-rich rocks and evidence of extensive assimilation as guides to prospectivity

Jun 19, 1905

By Howard E. Parkinson

In 1969, new coal mine health and safety legislation was enacted in the United States. As a result of this legislation, the Department of Interior, Bureau of Mines has carried out communications research aimed at developing whole mine communications for increased safety and efficient operation. The research has advanced and many promising results are now being demonstrated to the mining industry. However, there remains a challenge to further improve wireless communications within the mine workings and through the overburden above the workings. The objectives for future research and development will be discussed, together with the physical and operational constraints that new mine communication systems must face.

Jan 1, 1973

By Leonilson Toffoli Pedrini

A corrosão ocorre devido à deterioração de um material pela ação química ou eletroquímica em meio corrosivo, sujeito ou não a esforços mecânicos, causando modificações indesejáveis, tais como perda de massa, alterações estruturais e variações químicas. O aço inoxidável austenítico AISI 304L é utilizado em grande escala pelas indústrias por apresentar baixo custo e boa resistência à corrosão decorrente da camada de passivação. A passividade dos aços inoxidáveis em eletrólito com íons de cloreto é destruída em pontos ou áreas localizadas. Neste trabalho foi analisado, por meio de ensaios eletroquímicos, a resistência à corrosão do aço AISI 304L. Foi utilizada gaiola catódica em chapa de aço inoxidável 316, com dimensões de 0,8 mm de espessura, 112 mm de diâmetro, furos de diâmetro de 25 mm de altura e 8 mm uniformemente distribuída, com um distância de 9,2 mm entre furos. Os tratamentos térmicos foram realizados a 700, 800 e 900ºC, respectivamente. Os resultados indicam que a resistência à corrosão das amostras tratadas diminuiu, devido a precipitação de nitretos quando são submetidas a processos em altas temperaturas.

Aug 16, 2017

Collins Radio Company, through this contract with the Bureau of Mines, has conducted a System Study of Coal Mine Communi¬cations. The program was a three phase program to establish a data base, perform communication system analysis and optimi¬zation, and prepare equipment specifications to be included in this final report. At the start of establishing a data base both a knowledge of mine communication and coal mines in general was obtained. Communication system requirements and constraints were determined along with a survey of current and potential mine communication equipment. An investigation was completed concerning theoretical LF and VLF propagation characteristics, and UHF propagation tests were conducted in a working coal mine. Different mines were contacted and on-site surveys completed with respect to coal mine communication requirements.

Jan 1, 1973

By Leslie H. Sharp, Martin J. Gavin

"Introduction.Investigations of the oil shales of the State of Colorado were begun February 1, 1920, by the U. S. Bureau of Mines and the State of Colorado, under cooperative agreement entered into by the Bureau and the State, funds for which were provided by the State. The investigations are for the purpose of determining by large-scale Laboratory retorting tests, those conditions which will produce optimum yield of best quality products from Colorado shales. (For an outline of the work and description of the apparatus, see Gavin, Martin J., and Sharp, Leslie H., ""investigations of the Fundamentals of Oil-shale Retorting,"" Reports of Investigations, Bureau of Mines, July, 1920.)In the preliminary work which is usually required when a new material is being dealt with, certain physical and chemical constants of the shales being investigated, and their products, were determined; these data will be of much value not only to the thorough retorting tests now under way at Boulder, but to engineers who will design and construct oil-shale plants. While the figures presented in this report apply only to the shale used in the determinations, strictly speaking, the shale used was selected to represent, as well as possible, an average of the massive type of oil shale encountered in Colorado. The figures, therefore, can probably be applied with little danger of serious error to any massive Colorado oil shale which yields in the neighborhood of a barrel (42 gallons) of oil to the ton.This paper is based on a more complete article now being prepared in which experimental methods are explained in full, and complete experimental data. For the purpose of presenting the data with as delay as possible, it has been decided to anticipate the more complete article with the present report."

Aug 1, 1920

By Robert S. Nichols

Fording Coal Limited's mine in the Rocky Mountains near Elkford, B.C. has produced 21.8 million clean tonnes of metallurgical coal from 1971 to 1980, inclusive. This production has come from several pit areas and required the removal of 149.1 million bank cubic meters of waste rock and overburden by truck-shovel and dragline operations. Waste dumps from 30m to 200m in height have been successfully constructed on natural slopes, generally between 10° and 26°. Design considerations for the dumps include foundation and soil conditions, natural slope angles and containment of weak overburden or rehandle materials. Dump control is maintained by monitoring the crest and the face of an active dump area. Crest movement is measured by extensometers locally termed "Spoil Monitors". When crest movement rates progressively increase above normal, dumping operations are temporarily relocated. Some unstable conditions and mass failures have occurred as the result of natural foundation slopes being in excess of 26°, failure of weak water saturated foundation soils or weak material being placed on the dump.

Jan 1, 1983

By Corate L. Brierley

Low-grade porphyry copper ores containing chalcopyrite as the primary mineral was leached by two strains of acidophilic, thermophilic microbes belonging to the genus Sulfolobus. Leach tests were conducted in glass columns heated to 60-70° C. Pinto Valley and San Manuel ores sized to -1/2 inch + 50 mesh were effectively leached by the thermophilic organisms, but pinto Valley and Cyprus Bagdad ores sized to -2 inch + 1/2 inch resisted leaching. Aeration did not contribute measurably to bacterial copper extraction, since two columns, one inoculated and one sterilized, having a rest/ leach cycle without recurrent aeration exhibited copper extraction patterns similar to those of the aerated columns. Distilled water can be substituted for 9K medium without diminishing copper extraction. Decreasing the pH of the leachate to about 1.8 enhanced the extraction of copper from pinto Valley ore with the thermophilic microbes. Thiobacillus ferrooxidans was found to be relatively ineffective at copper extraction from pinto Valley ore. Of eleven solvent extraction reagents tested, Adogen 364 and Warsol at concentrations of 0.1% and 0.012 were inhibitory to oxygen uptake by the two Sulfolobus strains. Di-2-ethyhexyl phosphoric acid at concentrations of 0.1%, 0.01% and 0.001% were totally inhibitory to the respiration of both organisms.

Jan 1, 1979

By Georgene Renner

With more than 800 booth spaces sold and 540 exhibiting companies displaying their wares, there was something for everyone on the exhibit floor of the 2014 SME Annual Meeting in Salt Lake City, UT Feb. 23-26. The following is a sample of what was offered at the 2014 meeting.

By A. R. T. Denues

"INTRODUCTION The orienting phases of the current investigation of cushioned blasting in the Explosives Division of the Bureau of Mines were indicated in a previous publication (5) 3/. Pertinent literature reviewed therein indicated a highly controversial field. This emphasized the need for experimental studies of many factors that affect the health and safety of miners and the efficiency of mining operations. Results of some orienting tests showed marked effects on practical hazards. Further, they emphasized the necessity and importance of the contemplated investigation. The scope and general plan of these practical inquiries into the safety of cushioned blasting were indicated.This investigation of cushioned blasting relates to the various means employed to reduce the intensity of application of energy from explosive actions in boreholes. It has been suggested (from p. 19 of reference 5) that the divisions of this work would correspond to the salient hazards affected by cushioned blasting. These include the ignition hazard, hazards from poisonous gases, and other practical hazards in the blasting technique. The ignition hazard was resolved into two components of approximately equal weight. These include studies of effects upon (1) the incendivity of blown-out shots and upon (2) the occurrence of such shots. Experimental studies of effects on the incendivity of blown-out shots were first undertaken. Questions of the best procedure for making these evaluations have been adduced, and the interpretation and utilization of the results of gallery testing seemed to require detailed attention; some preliminary general considerations of such testing were therefore necessary."

Jan 1, 1943

During the initial portion of the contract several alternative designs were considered, as set out step by step in the monthly reports. The conclusions reached during this period were - to use on INTERDATA Model 70 as the system minicomputer - to drop the idea of multiplexing and digitizing the inclinometer outputs downhole due to the greater complexity and cost that that alternative would imply - to use a multitasking software monitor to enable synchronization of the several tasks that the system would have to perform simultaneously - to use a common controller for all I/0 devices except those which were available off the shelf from Interdata - to use a sheave counter to meter off equal increments of probe travel, but to supplement this information with the use of an encoder on the winch drum in order to be able to measure total probe travel unambiguously. - to place all I10 device interfaces in a bin connected to the common controller. During this period considerable attention was dedicated to the design of the mechanical components contemplated it the original contract. Of these, only those required for vertical probe was complete at the time that it was decided to forego the mechanical subsystem and concentrate on developing the necessary electronics and software to interface with the probes being developed by the Bureau of Mines.

Jan 1, 2012

By Paul J. Remington

The field data gathered as part of the measurements described in Volumes I and II were re-analyzed in the low frequency regime (.1 Hz to 1 Hz) where motion sickness normally occurs. These data were compared co the international standard ?ISO 2631 Addendum 2: Evaluation of exposure to whole body z-axis vertical vibration in the frequency range 0.1 to 1.0 Hz." For both underground mining machines and surface mining machines the results showed that one would not expect motion sickness to .be a severe problem. New field data were gathered on the vibration reduction performance of various seat designs found on surface coal mining machines. The vibration during normal operation was measured on the seat using the standard seat pad accelerometer package described in the previous two volumes and simultaneously on the floor of the machine at the base of the seat. Preliminary indications are that the so-called high performance seats used for operator vibration reduction do not offer significant improvement over conventional seats.

Jan 1, 1984

By E. H. Griswold, C. E. Beecher

DURING 1931 the petroleum industry has faced the most hazardous periods of its existence, caused by large potentials, overproduction, and demoralized markets. Two state governors actually resorted to the use of the militia in an effort to restore a semi-stabilized condition within the industry, to prevent waste of the states' natural resources, and to restore prices to a level that would yield the states a reasonable tax revenue. These conditions have made it necessary to put into effect most. stringent economies and have produced a spirit of cooperation between companies to an extent that never before existed. The necessity for unified action on such matters as proration and the advantages to be gained by unit operation are being realized by the oil industry as a whole. Fewer wells have been drilled and wildcat operations almost eliminated: development and operation costs have been greatly reduced and more attention is being paid to efficient recovery methods. The net work of oil pipe- lines has grown rapidly especially in the area of East Texas. The construction and operation of natural gas and gasoline pipelines into areas far distant from the source of supply has been one of the outstanding accomplishments. Refining efficiency has continued to increase and the public is being supplied with a better grade of gasoline at a lower price. The unreasonable tax which state politicians have succeeded in placing on gasoline has encouraged tax evasion and unfair competition by un- scrupulous dealers and has misled the public as to the true price of gasoline.

Jan 1, 1932

By Richard I. Miller

Science Applications, Inc. has developed for the U.S. Bureau of Mines a rapid response radon monitor capable of accurately responding within three minutes to changing radon levels of magnitude from 100 to 10,000 pCi/1, typical of the levels in working uranium mines. The instrument weighs 17 pounds, is sized 12" x 10" x 6", and is capable of 8 hours of continuous portable operation with a self-contained, rechargeable battery power source. Residual chamber contamination from a radon level allowed to remain in the chamber for 90 minutes is about 10 percent, decaying about a factor of two in one hour. The instrument sensitivity is a nominal 0.1 cpm/(pCi/1), with a background count rate of less than 1 cpm.

Jan 1, 1979

By Ted H. Eyde

Both private industry and the Interior Department have become alarmed about the enormous amount of Federal land that has been withdrawn from appropriation either under the Mineral Leasing Laws or the Mining Law of 1872. According to a recent article by Gary Benethum and L. Courtland Lee, governmental actions have withdrawn nearly 400 million acres from the operation of the Mining Law of 1872 and over 500 million acres from the Leasing Laws. An addition al 100 million acres for the Mining Law of 1872 and 70 million acres for the Leasing Laws are either encumbered or being managed in such a way as to constitute a defacto withdrawal from mineral development. This means simply that mineral exploration end development under the Mining Law of 1872 is either prevented or discouraged in an area the size of the states of California, Arizona, Washington, Oregon, Nevada, Utah, Idaho, and one half of Colorado combined. Under the Mineral Leasing Laws, exploration and development is either prevented or discouraged in an area equal in size to all the states east the Mississippi River, except Maine.

Jan 1, 1976

By Thomas J. Peters

The U.S. Bureau of Mines and the U.S. Geological Survey are responsible for the evaluation of the mineral resources and potential of further planning areas included in the U.S. Forest Service Roadless Area Review and Evaluation (RARE II) program. The Bureau of Mines primarily evaluates mineral deposits and prospects within the areas. The Geological Survey naps the area's geology and conducts geochemical sampling. Evaluations are in conformance with the Forest and Rangeland Renewable Resources Planning Act of 1974 as amended by the National Forest Management Act of 1976. The Hauser RARE II area, which consists of 7,600 acres (3,100 ha) within the Cleveland National Forest, is in southern San Diego County, California. The area, which forms the north slope of Hauser Canyon, ranges between 1,600 and 3,919 ft (490 m) in elevation. It is sparsely to densely covered with desert shrubs. The area is underlain by granitic rocks of the Peninsular Ranges batholith.

Jan 1, 1983

By L. R. Herrmann

The most fundamental feature of fracture is that it involves separation. Such separation can arise by either separation of molecules, more or less along the line joining their centers (tension), or by d sliding separation roughly perpendicular to that line (shear). Theoretically, a perfect crystal could never be broken by the application of perfectly axial compressive stress (until some sub-molecular actions occur). In tension fields the calculated forces between molecules are extremely high. Consequently, calculations based on the forces known to exist in materials at the molecular and crystalline levels always lead to strengths which are two or three magnitudes higher than the strengths obtained in service or in the laboratory. It has been a major problem, therefore, to explain: (a) How fracture can occur in compressive stress states. (b) Why the observed strength of a material is always much lower than its calculated strength.

Jan 1, 2012

By Randall M. Wheeler

Many of us have used a seismograph to measure peak particle velocity and frequency. But do we really understand why? Also, why do we measure particle velocity instead of displacement and/or acceleration? What is the vector sum? How do these items relate? Where does frequency fit in? This workshop will attempt to answer these and other questions. Some of the answers may surprise you, others may not.

Jan 1, 1997

By R. K. Rath

Adsorption, electrokinetic and flotation studies were carried out. The maximum density of adsorption of guar gum was obtained at pH 7.5 on sphalerite and at pH 11.5 on galena. Flotation recovery of sphalerite was reduced only marginally by the presence of guar gum in the pH range investigated, whereas recovery of galena was reduced to about 20% at pH 12. Differential flotation tests on binary mixtures indicated that 10 ppm of guar gum can depress galena and separate it from sphalerite at around pH 12.1. Co-precipitation tests confirmed the formation of a metal ion-guar gum complex in the bulk solution, suggesting that this is the precursor to adsorption. The adsorption isotherms for both minerals followed Langmuirian behaviour, but adsorption of guar gum on galena was significantly higher than on sphalerite and dissolution tests indicated that the concentration of Pb ions released from galena was an order of magnitude greater than that of Zn ions dissolved from sphalerite

Jun 21, 1905

The Khanong supergene-enriched copper resource, (~23 Mt at 3.0 per cent Cu), is one of several resources recently discovered in the intrusive-centred, sediment-hosted Au-Cu Sepon mineral field located in southern Lao PDR. The unusual style of hypogene mineralisation and unique set of conditions have resulted in the development and preservation of a supergene-enriched profile in this subtropical climate. Hypogene sulphide-rich mineralisation replaced calcareous cataclastite (fault rock) developed in the flat-lying, extensional, Khanong Fault. Spatially, the hypogene mineralisation was immediately out board of the skarn û hornfels Cu-Bi front and in board of sediment hosted Au-(As-Sb) mineralisation in a zoned intrusive-centred hydrothermal system. In situ supergene enrichment of the sulphide protore has resulted in a high-grade chalcocite-clay zone (~10.3 Mt at 4.6 per cent Cu) overlain by leached limonite-clay. A very high-grade in situ to exotic limonite-clay Cu-oxide-mineral zone is locally developed above impermeable dolomite at the base of chalcocite-clay zone. Exotic Cu-Mn-wad mineralisation developed for up to 1 km down the hydraulic gradient from the chalcocite-clay zone. Unique supergene enrichment conditions have resulted in the high-grade Khanong Cu resource in a subtropical weathering environment. The base of the currently active supergene profile coincides with the base of a flat-lying, pyrite-rich fault rock, dipping parallel to the hill slope, maximising Cu enrichment. Meteoric water has been channelled along subvertical faults and narrow horizontal subsurface zones. Low permeability of the fault host rock and footwall rocks has controlled the low volume and slow movement of groundwater required for supergene enrichment. Erosion has been slowed by the resistive ironstone and limonite-clay layer at surface, which assists in preserving the gentle slope over the chalcocite-clay zone.

Jan 1, 1999

By A. D. Hahn

This report describes and gives the results of an examination by the Federal Bureau of Mines of ilmenite-bearing placer sand deposits in the 24-mile long valley of Otter Creek, Kiowa and Tillman Counties, Okla. Drilling and sampling was completed in three periods between October 1956 and September 1957. Mineralogic studies and mineral-dressing tests on recovery of ilmenite and other heavy minerals from composited samples of the sands were made in Bureau of Mines laboratories at Rolla, Mo., in 1957 and early 1958. Otter Creek rises in and drains the southwestern extremity of the Wichita Mountains, which are represented locally by knolls and ridges of gabbro and granite surrounded by plains floored with flat-lying Permian red beds. The valley fill consists of a basal sand-clay component, derived from weathering of the igneous rocks, and an overlying silt-clay alluvium. Ilmenite is present in significant quantity and recoverable grain size only in the basal sand-clay.

Jan 1, 1960