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By A. Lawley S. Schuster

The tensile behavior of copper foils prepared from rolled bulk material has been studied over the thickness range 2 to 53 , and for a range of pain sizes. For foils of comparable grain size, having the cube texture and tested along (100), yield strength increases with decreasing foil thickness t below -26p, with a corresponding decrease in ductility. Deformation occurs in the form of localized slip clusters distributed throughout the gage section. To the extent that the tensile strength (10 to 18 kg mm-) is unaffected by foil thickness, and that the foils possess fair ductility, the stress-strain behavior resembles that of bulk material rather than that of whiskers or evaporated films of comparable dimensions. The dependence of yield strength o on foil thickness t below -26p is of the form: oy = oo + kt-1/2. Possible explanations for the stress increase are considered based on 1) the dependence of active dislocation source length on foil dimensions, 2) the locking of surface sources, or the blocking of mobile sources at the surface due to surface film. It is now well-established that filamentary whiskers of many materials show exceptionally high strength compared with bulk crystals.'-11 As the diameter of the whiskers decreases to -1, the observed fracture strength approaches, and in certain cases exceeds, the calculated shear stress for the nucleation of slip in a perfect crystal.' In general, the stress-strain curve is entirely elastic, with strains at fracture approaching 1 pct. Similarly, thin films12-24 of evaporated or electrodeposi-ted material have been shown to possess tensile strengths three to seven times that of bulk material, with total strains at fracture -1 to 2 pct. In the present study, attention has been directed to the room-temperature tensile behavior of thin foils of copper over the thickness range 2 to 53, prepared from rolled bulk material. Yield stress, ultimate tensile strength, elongation to fracture, and work-hardening behavior are measured as a function of grain size and foil thickness. Structurally such foils are superior to either evaporated or electrodeposited films, and in the recrystallized condition exhibit considerable ductility. Apart from preliminary work by Sumino and Yamamoto25 on the work-hardening behavior of rolled and recrystallized copper foils, no systematic tensile studies have been carried out on material of this form. EXPERIMENTAL PROCEDURE Tensile specimens were prepared from 99.995 pct purity rolled copper foils of thickness 2, 6, 12, 26, and 53, obtained from the Hamilton Watch Co., Lancaster, Pa. Irrespective of specimen shape, it is necessary to use tensile foils with edges free from notches or tears. To this end, any form of cutting operation was excluded, and the tensile foils prepared using a photoengraving process, the details of which are described elsewhere.26 Since tensile data are required under conditions of uni-axial stress, the specimen shape is extremely important. Ideally, the foil should be infinitely long, allowing a gradual taper from the grip area to the gage section; however, from a practical standpoint, long foils are easily damaged during testing. A modified tensile specimen was therefore selected having a parallel gage section 1.25 by 0.20 in. with a tapered shoulder section increasing to 0.5 in. at the grips, and an over-all length between grips of 4 in., Fig. 1. In practically all tests, these foils fractured within the parallel gage section. By approximating the foil contour (Fig. 1) to a hyperbola it is possible to analyze the stress distribution in the tensile foil using two-dimensional elasticity

Jan 1, 1964

By Stephen P. Signer

To improve the understanding of the support interaction mechanics between grouted bolts and coal mine roofs and to help lay the foundations for improved design and evaluation techniques, the 0.8. Bureau of Mines has conducted laboratory, field, and analytical studies of the load transfer mechanics of grouted roof bolts. Mechanisms by which load is transferred from a bolt through the grout to the rock mass are analyzed. Strain gauges were installed on over 70 bolts and tested to observe the rate of load transfer when a force was applied at the bolt head. Laboratory and field tests were conducted to determine bolt-grout- rock interaction behavior in both the elastic and postyield phases. Long-term laboratory tests were run to determine the time-dependent properties of both polyester resin- and-gypsum-grouted bolts. Numerical studies using finite- element techniques were compared to the experimental results. Elastic tests showed that 90 pct of the applied load was transferred within 24 in of bolt length. Long-term tests indicated that creep is more significant in gypsum-grouted bolts than in resin- grouted bolts. Plastic studies showed that yielding of steel will translate down the length of the bolt from 6 to 20 in.

Jan 1, 1988

"The outlook for Eastern Canada is decreasing coal production over the next few years; however, a reappraisal of the long-term requirements and increased prices of coal could lead to a revitalizing of the industry. The market for Western coal is expanding and is expected to exceed 50 million tons per year in the metallurgical and thermal power fields. Western coal reserves are currently estimated at 119 billion tons. Technical developments in Eastern Canada include a shearer and gate-end support system to mechanically cut the stall and brushing at the tail-end of a longwall. In Western Canada, the most modern equipment is used in mining, beneficiating and shipping coal. Results to date on the underground hydraulic experiments exceed expectations. The importance of reclamation is recognized and plans have been made to restore and re-vegetate disturbed areas and mine dumps. In Eastern Canada, experiments were started to determine the feasibility of coal reclamation from mine dumps, including one dump that is on fire. The Mining Research Centre, Mines Branch, continued to conduct research work oriented toward solving Canadian mining problems The Western office of the Centre, opened in 1970, was set up primarily to study problems associated with a resurgent coal industry."

Jan 1, 1971

APPROXIMATELY 26 percent of the total ore production to date from the largest single deposit of copper-bearing material in the world was mined during the war years, 1942 to 1945, at Chile Exporation Company's great open-pit mine at Chuquicamata, Chile. About 18 percent of the total waste removed during the life of the mine was handled in the same period. The total of ore and waste represents approximately 24 percent of the total material that has been excavated from the pit. This is more than was removed in the first fourteen years of operation from 1914 through 1927. The pit at Chuquicamata is 17/8 miles long, 1/2 mile wide, and has a present vertical extent of 817 ft between the top of the highest bench and the lowest bench being worked. However, when

Jan 1, 1948

A vital ingredient in ensuring that metals exploration companies, working in the developing countries of thePacific Rim, support the development of national geologists is making such a learning program cost-effective. There is a wide spectrum of learning needed in the development of these explorationists: the technical and conceptual skills to carry out exploration efficiently, the professional and managerial skills to apply the exploration in the work situation, the personal attributes required to manage their exploration effectively, and a company organisation that allows them to learn and use these skills and attributes.

Jan 1, 1995

By Margaret R. Egan

A study of the combustion emission products of rigid ventilation ducting was completed by the U.S. Bureau of Mines. The ducting was composed of fiberglass-reinforced polyester resin. Four properties of the ducting were evaluated: (1) propensity to ignite, (2) smoke characteristics, (3) gas emissions, and (4) heat release. Particle sizes, obscuration, optical densities, and production constants for gas and smoke were also calculated. These results provide comprehensive data about the emission products, detectability, and relative hazards of fiberglass-reinforced plastic ducting and other mine combustibles under realistic fire conditions.

Jan 1, 1990

Investigation of the Effect of N-Substituents on Performance of Thioureas as Special Collectors for Copper Sulfides by ab Initio Calculations

Sep 13, 2010

By B McCreath

Industrial process water for the Commodore Coal Mine and the adjoining Millmerran Power Station is provided by pumping secondary treated sewage effluent 100 km from the Wetalla Sewage Treatment Plant near Toowoomba. (A separate source is used for potable water.) The effluent is not of sufficient quality for discharge to a watercourse, but it is suitable, with further treatment, for the mine and power station. In designing and constructing the pipeline, special emphasis was placed on preventing accidental spills or planned releases to the environment. The pipeline and associated works can transfer 1000 ML/annum for reuse in the coal mine and power station.

Jan 1, 2003

By George P. Jr Schivley

Looking at the process of drilling rock from the standpoint of the power required, yields an equation that relates Force-on-the-Bit; Torque, to rotate the bit; and bit Angular Speed to the Penetration Rate of the bit; the Area of the hole being drilled and the Specific Fracture Energy of the rock. Specific Fracture Energy and the Compressive Strength of the rock are related.

Jan 1, 1994

By R. C. Bryce

"Selbaie is located northwest of Joutel, in what is known as the fourth east-west volcanic sediment group in northwestern Quebec. The main metals produced are copper and zinc, with important contents of both silver and gold. Production comes from an open pit mine on the A-I zone and from two underground mines on the B zone and the A-2 zone. Each mine gave rise to important capital investment programs for construction and mine development, all of which were managed and staffed with company-hired, non-union personnel. Production from all sources now exceeds 7000 tonnes per day, with a workforce of540 regular employees. Of particular interest technically is the high recovery of B zone reserves underneath 40 m of overburden cover, the low-cost capital development of the A-2 zone, the computerized control of open pit mining, and the successful copper-zinc separation of the A-1 zone ore. Due to the low grades of the mineral deposits, efficiency in all aspects of the production process, is essential to the success of the operation.LocationThe Selbaie Mine is located 82 km northwest of the locality of Joutel in northwestern Quebec (Fig. 1). Access to the mine is by an all-weather road, 32 km of which is paved. A second road access to the site is via La Sarre, 134km to the southwest. Employee access, materials transport and haulage of copper and zinc concentrates take place over both of these roads."

Jan 1, 1990

By W. Rostoker, R. P. Elliott

TWO intermediate phases enter into equilibrium with the primary solid solutions of titanium.' The TiMn2 phase was identified by Wallbaum2 as of the C14 type isomorphous with MgZn2. Contrary to Maykuth, et al.,¹ the phase occuring at about the 50-50 atomic proportion has been shown to derive from a peritectoid reaction.:' A 30 day anneal at 900°C of an alloy containing 52 wt pct Mn developed sufficient of the new phase to give a clear and predominant diffraction pattern. The powder pattern was taken in a 14 cm diameter powder camera using filtered Cu Ka radiation. In all, 75 lines were recognized and measured. Interplanar spacing and observed intensities for the first 26 of these are given in Table I.

Jan 1, 1954

Coal Division Industrial Minerals Division Minerals Beneficiation Division Mining, Geology and Geophysics Division Established as a Society February 26, 1957 OFFICERS AND COMMITTEES J W Woomer, President A B Cummins, President-elect S D Michaelson, Past President C E Lawall, Eastern Regional Vice-President D W Scott, Central Regional Vice-President 3 D Forrester, Western Regional Vice-President R B Ladoo, Treasurer John Cameron Fox, Secretary

Jan 1, 1959

By A. R. T. Denues

[Liquid oxygen explosives are ordinarily made from a carbonaceous absorbent and from liquid oxygen of high purity. These explosives have a limited but definite field of usefulness; their properties have been described in the literature, which includes several publications of the Bureau of Mines, the most recent dealing with fire-retardant treatments.3/ It seems generally conceded that the outstanding hazards in the use of these explosives are their high inflammability and their relative sensitivity to mechanical action. Each of these topics has been studied, and some interesting practical results have been obtained. Treatments have been described that render liquid-oxygen explosives prepared from granular carbonaceous absorbents practically immune to the action of igniting agents representing or exceeding practical hazards in violence.]

Jan 1, 1941

By M. Vallée

"Geological and technical problems are often considered the most important ones affecting new mining projects. Typical problems and likely causes are reviewed based on current Quality Management and Continuous Improvement (QMCI) perspectives, giving particular attention to the work of W.E. Deming. As the “system approach” is an essential part of these policies, its characteristics are described with particular attention given to cultural- behavioural, organizational and systembased constraints described by J. Gharajedaghi. Given that poor communication and interaction among geologists, mineral processors and mining engineers/operators can seriously affect the adequacy of tests, project planning and execution, and mine profitability, these interrelated processes within the mining systems are analyzed and modelled. The impacts on models and simulations of ignoring typical data, information and knowledge uncertainties are addressed. Adapting W.E. Deming’s Fourteen Points, System of Profound Knowledge and insistence on leadership, and the analysis of mining system constraints, will allow the effective QMCI approach required to reduce geological and technical risks. Whenever we achieve this goal, we will be in a better position to overcome environment-, market-, finance- and community-related problems, achieve higher company and industry profitability as well as more sustained development. RÉSUMÉLes problèmes géologiques et techniques sont souvent considérés les plus importants parmi ceux qui affectent les nouveaux projets miniers. Des problèmes typiques et leur causes sont étudiés dans la perspective de gestion de la qualité et d’amélioration continue (GQAC), en relation avec les travaux de W.E. Deming. Comme l’approche système est au centre de ces méthodes, ses caractéristiques sont décrites en donnant une attention particulière aux contraintes de types culturel-comportemental, organisationnel, et systémique décrites par J. Gharajedaghi. Compte-tenu que les lacunes dans les communications et les interactions entre géologues, minéralurgistes, et ingénieurs/opérateurs miniers peuvent affecter sérieusement la validité des essais, de la planification et de l’exécution des projets ainsi que la rentabilité des exploitations, ces processus connexes font l’objet d’analyse et de modélisation. Les impacts sur les modèles et les simulations de l’incertitude des données, informations et connaissances sont soulignés. En adaptant au système minier les Quatorze Obligations et le Système de connaissance approfondie de W.E. Deming ainsi que l’analyse des trois types de contraintes, nous pourrons développer une approche GQAC permettant de réduire les risques géologiques et techniques des projets miniers et des exploitations. Ceci nous pemettra de mieux faire face aux problèmes reliés à l’environnement, aux marchés, au financement et aux conditions sociales, d’améliorer la rentabilité des exploitations minières et de l’industrie, tout en contribuant de façon accrue au développement durable."

Jan 1, 2003

By Holger Cordes

X-ray diffraction has long been used for qualitative and quantitative mineral analysis but Rietveld data analysis is still an under utilized method for mineral exploration and processing applications. In this full-profile approach the structural parameters of each mineral phase, together with experimental parameters, are refined by least-squares methods to minimize the difference between observed and calculated diffraction patterns. The result is a standard-less, quantitative analysis of the mineral abundance in the sample that is more accurate and considerably faster compared to traditional methods. The TOPAS software package combines a user-friendly interface with a unique approach to resolve overlapping peaks. Automated analysis options are also available and significantly reduce analysis time for routine samples. Several examples on a wide range of naturally occurring rock types are shown that illustrate the capabilities and limitations of the method. The examples include several options for the quantification of amorphous constituents like volcanic glasses.

Jan 1, 2006

By Walter E. Heinrichs

The following is a condensed version of an open letter addressed to Bil Gilbert of Sports Illustrated: Your article, "When a Law Fights a Law, Sports Illustrated. April 26, 1971, betrays considerable unfamiliarity with the subjects of ecology, social science, mining law and history. In a magazine as widely circulated as Sports Illustrated, an article of such a slanted nature misleads the general public.

Jan 1, 1971

By J. Temporal

An introduction to the conference material in this issue is given together with the issue contents list, closing remarks by its chairman Dr. J. Temporal, the list of contributors and their companies, and the information that the 26th Sir Julius Wernher memorial lecture had had to be presented by the lecturer's wife, M. Biggart, in his absence due to site problems on the Storebaelt project

Jun 16, 1905

By T. H. Yang, K. K. Lee, Z. Z. Liang, C. A. Tang, L. C. Li, Y. Tsui, L. G. Tham

Abstract: A series of numerical tests of hydraulic fracturing in heterogeneous rocks were performed to investigate the influence of pore pressure magnitude and gradient on initiation and propagation of tensile fractures. The numerical tests were run with a Rock Failure Process Analysis code, F-RFPA2D, incorporated with a Flow-Stress-Damage coupling model (FSD). To investigate the influence of pore pressure magnitude on fracture behaviour, “pinch-off” breaking tests, originally employed by Bridgeman to investigate the effective stress law for tensile fracture in a uniform pore pressure field, were numerically modelled. In another numerical test, a double-notched sample, with fluid pressure in one notch while keeping the other one open to the atmosphere, is numerically extended to investigate how the fluid flow direction or the pore pressure gradient will influence the fracture behaviour. The simulation results show that fracture is strongly influenced by both pore pressure magnitude and pore pressure gradient. Keywords: seepage mechanics; heterogeneous; pore pressure; numerical simulation; failure process ZUSAMMENFASSUNG: Um den Einfluss der Wasserdruckgroesse der Oeffnung und der Porisitaet auf den Bruchentstanden und Verbreiten der Tension von Gebirgen zu beurteilen, wurde viele nummerische Pruefungen auf den hydraulischen Bruch in dem Gebirgen aufgenommen. Diese Pruefungen wurden mittels der Analyse- Software F-RFPA2D und Flow-stress-Damage Coupling model ( FSD) durchgefuehrt. Um den Einfluess der Wasserdruckgroesse der Oeffnung auf den Bruch zu beurteilen, wurden auch Bruchpruefung und nummerische Analogexperimenten gemacht, und dadurch wurde die ganze Phase der Bruchentstanden und Verbreiten wiedergezeigt, und die Ergebnissen ergeben sich, dass die Wasserdruckgroesse der Oeffnung und der Porisitaet sehr viel auf den Bruchentstanden und Verbreiten der Tension von Gebirgen beeinfluessen. Schluesselwoerter: Durchlaessigkeit , ungeleichmaessig, Wasserdruck der Oeffnung, nummerische Analog, Zerstoerungspahse Résumé : Une série de simulations numériques a été ménée pour analyser l’influence de la grandeur de la pression de pore et du gradient sur la naissance et la propagation des fractures de tensions par le biais de la simulation numérique des fractures hydroliques dans des rochers hétérogènes . Le logiciel F-RFPA (Rock Failure Process Analysis code ) intégrant FSD ( Flow-Stress-Damage coupling model ) y a été employé. Les résultats des simultations montrent tout le processus de la naissance et de la propagation des fractures sous la pression de pore. Ces résultats nous ont permis de constater que la grandeur de la pression de pore et le gradient exercent une influence importante sur la naissance des fractures dans les rochers et sur leur mode de propagation . Mots de clé : le mécanisme de transfusion ; l’hétéogénéité ; la pression de pore ; la simultation numérique ; le processus destructif

Jan 1, 2003

By Thomas J. Peters

A mineral survey of the Sill Hill RARE II area (No. 5304), covering 5,200 acres (2,100 ha) of the Cleveland National Forest, San Diego County, California, was conducted by the U.S. Bureau of Mines and the U.S. Geological Survey. This survey was in conformance with the Resource Planning Act (RPA) of 1974, as amended by the National Forest Management Act of 1976, to provide mineral resource information for study area classification. Bureau of Mines personnel made an economic appraisal of mineral deposits by searching pertinent geological and mining publications as well as U.S. Bureau of Land Management, U.S. Forest Service, and U.S. Bureau of Mines files and records. Known mines, prospects, and mineralized localities were examined during 1981, and sampling and mapping were done where warranted. The Geological Survey 'did geologic mapping, geochemical sampling, and geophysical surveys to aid this study.

Jan 1, 1983

Jan 1, 1968