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By John A. Johnson

For the purpose of comparing the amounts of dust produced by various mining operations, samples of atmospheric dust were collected during a complete cycle of drilling, blasting and mucking at or near the face of the Bureau's Mount Weather testing adit while the efficiency of several types of stemming in metal-mine blasting was being investigated. ACKNOWLEDGMENTS All gas samples were analyzed in the laboratory of the Bureau of Mines Gas Section at Pittsburgh, Pa.

Jan 1, 1939

By Wilson Blake

Rock preconditioning in advance of mining was shown to be an effective means of rock-burst control based on the results of a field demonstration carried out on the 7700 level of the Hecla Mining Company's Star mine. Mining through the preconditioned zone was characterized by greatly reduced rates of released seismic energy and no bumping or rock bursting occurred within the preconditioned zone. Mining above the preconditioned zone was characterized by greatly increased rates of released seismic energy and rock bursting, particularly where the vein became very narrow in waste zones. This increased incidence of rock bursting points out the need for stope preconditioning to be carried out on an entire stope block basis. The data obtained from the monitoring of the mining above the preconditioned zone on the 7700 level will be extremely useful in evaluating any future stope block preconditioning experiments on the lower levels or the Star mine.

Jan 1, 1980

By S. L. Huang

The location and shape of potential failure surfaces in soil slopes were directly determined based on the stresses induced in the soil mass and the strength of the soil itself. Stress calculations were carried out by the finite element method with the Drucker-Prager nonlinear material model. The Mohr-Coulomb failure criterion and Mohr's circle stress analysis were then applied to the calculated stresses to determine the characteristics of the failure surface.

Jan 1, 1989

Lime and Marble Limited was founded by the late T J McKee OBE and his family in 1935. The Company had its base in the high grade marble deposits on Takaka Hill, and was also shipping crushed limestone to the Auckland glass works, and supplying burnt lime for industry.

Jan 1, 1998

By E. J. Ripling, M. W. Toaz

Tensile tests were conducted on pure magnesium and on four commercial alloys over a variety of temperatures and strain rates. The high positive slope of the ductility vs testing temperature curves that is found over a short range of testing temperatures for these materaturerials was shown to result from the fact that the microstructure was not stable at these testing temperatures. Pure magnesium did not display a transition temperature, although its sub-room temperature ductility was low. This poor ductility resulted from a grain boundary weakness. The aluminum-bearing commercial magnesium alloys had a higher ductility than the pure magnesium. ness.Thealuminum-bearingcommercialThese alloys did exhibit a transition temperature and grain boundaries that were stronger than the grain material. Both pure magnesium and the commercial alloys began initiating cracks at strains equal to one half of their fracture strain. MAGNESIUM base alloys' enormous potential as structural materials lies in their high strength to weight ratios. At present, the high strength magnesium base alloys such as AZ-80, which will be discussed later, have about as high a tensile strength to specific gravity ratio as the highest strength wrought aluminum alloy, 75s-T6, and, of course, a much higher strength to weight ratio than structural steel. Further, since the magnesium base alloys develop their high strength to weight ratios with moderate strengths and extremely light weights, the ratio of load carrying capacity to the weight of many structures is relatively higher for the magnesium base alloys than their strength to weight ratios would indicate. This results because judicious increases in section size, such as increasing the depth of bending members or adding reinforcing ribs, can frequently increase the weight of a structure linearly while the strength and stiffness increase as the second or third power of the added weight. Strength and rigidity must be designed into lightweight structures by those techniques which establish multiaxial stress states. Consequently, strong, lightweight structures frequently also possess a greater propensity toward brittle failures. In order to insure against these catastrophic failures, an extra premium must be placed on ductility and toughness in light alloys. Current knowledge of the ductility and toughness behaviors—notched behaviors—of magnesium base alloys is limited.* Most of the magnesium base alloys * The state of present knowledge regarding the effect of testing temperature on mechanical properties has recently been summar-ized by Pritchard.' crystallize in the hexagonal system, so that they are expected to exhibit a tough and ductile to brittle transition temperature. Actually, a transition temperature behavior has been reported for commercially pure magnesium in the literature, but the characteristics of this transition temperatureh uggest that it may not be a transition in the usual meaning, but simply the onset of some thermal softening, a performance much like that which face-centered-cubic lead might exhibit slightly below room temperature. If transition temperatures do exist, such important questions as the manner in which they are affected by internal variables such as chemical composition and grain size, or the effect of external variables such as rate of straining or notch severity have never been investigated. The investigation reported upon herein was undertaken in order to define some of the mechanical behaviors of the magnesium base alloys better, to gain a better understanding of the influence of some of the above listed variables, and particularly to understand their effect on ductility and toughness better. Material and Procedure Material-—Pure magnesium and four commercial alloys were used in this investigation. The alloys were selected so that chemically they made up a series with approximately the same minor alloying

Jan 1, 1957

By S. T. Camagu, J. Dutta Majumdar, S. L. Pityana

Laser surface alloying was used to develop copper and molybdenum aluminides by injecting premixed copper and molybdenum powder particles into a laser-generated melt pool on an aluminium substrate. Different laser processing parameters were used to produce the composite thin layers on the substrate material. The microstructure and phase constituents of the composite layer were studied by means of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) techniques. Experimental results show that the matrix structure of the metal matrix composite layer consists of ?-CuAl2and MoAl5. Surface hardness was increased by a factor of 3.

Jan 1, 2015

By Dennis P. Martin, Michael M. Fitz, James E. Friant

Methods for reducing the cyclic nature of drill and blast tunneling operations have been long needed. A miniature blasting system using 10 mm (.375 in.) holes, 0.91 m (36 in.) deep, and blasting only one hole at a time makes it practical for men to work behind a shield, remaining at the face during the entire process. A prototype automated module was developed to drill, load the hole and initiate the detonation without moving from the hole. A unique cost effective gell explosive and a novel, low cost initiation method were developed.

Jan 1, 1989

By Emöke Imre

A point-symmetrical linear coupled consolidation model with displacement boundary condition is suggested for the description of the consolidation around the pile tip after pile penetration. Analytical solution is given. Main features of the solutions are predicted by the analysis of the system of differential equations and, the boundary conditions.

Jan 1, 2002

By B. A. Ridolfi, S. M. Alvarez

The Moon Creek Reclamation Project provides a case study in the development of creative cleanup solutions for an abandoned lead and zinc mine and mill site located in northern Idaho. Innovative design features include construction of a 88,000cubic yard combined waste containment facility on soft in-situ tailings, water-balance cap, limestone gravel drains, a geocell mattress for stability, and a below-grade scour protection berm. The stream, including a wetlands buffer, will be relocated within an existing road alignment and rehabilitated to provide trout habitat. These elements allow for the integration of reclamation and stabilization measures into an effective site design.

Jan 1, 1999

[Determine how subsidence resulting from underground coal mining affects surface structures, and evaluate the usefulness s of the tiltmeter for monitoring foundation movement. Approach The Bureau of Mines is studying foundation response to mine subsidence in order to determine how subsidence-induced ground movements affect foundations in place directly above the mint. These investigations are essential if economic mitigation and repair techniques are to be made. In addition, commercially available tiltmeter are being evaluated (or use as a cost-effective monitoring technique. To study foundation response and to evaluate the tiltmeter system, full-scale model foundations were constructed, instrumented, and monitored for three years. Vertical and horizontal displacements, tilt magnitudes and directions, and observed damages were recorded. Displacements were compared with measured lilt to determine if the tiltmeter was tracking foundation response to subsidence, The Bureau developed a computer software package to aid in the reduction and analysis of the tiltmeter data.]

Jan 1, 1988

By S. Read, G. Cook

The Hoek-Brown failure criterion is often applied to a wider range of rocks than the isotropic rock masses to which it is strictly applicable. This paper evaluates the patterns of defects in rock masses using spherical projection contour plots of samples of randomly-generated orientations and datasets from mapping of New Zealand closely-jointed greywacke rock masses. Two indices from the contour plots - the area within the 1% contour (A1%) and maximum concentration (Cmax) are introduced for distinguishing uniform (isotropic), random or regular defect patterns. The indices provide a potential extension to current guidelines on the use of the Hoek-Brown failure criterion. The paper also outlines kinematic checks to assess the influence of defect clusters on rock mass strength. Das Hoek-Brown Bruchkriterium, das strikte nur fuer isotrope Gefuege gilt, findet oft einen viel weiteren Anwendungsbereich. Diese Arbeit bewertet diverse Dispersionsmuster der Defekte einer Gesteinsmasse. Wir vergleichen in sphaerischer Projektion (1) Beispiele zufaelliger Orientierung von Defekten und (2) Felddaten ueber neuseelaendisache engstaendig geklueftete Grauwacken. Die Projektionen werden durch die Indices A1% (Flaechenanteil des 1%-Bereichs) and Cmax (Hoechstkonzentration) gekennzeichnet, welche isotrope, zufaellige und regulaere Muster unterscheiden und die aktuellen Richtlinien zum Hoek-Brown Kriterium ergaenzen. Wir testen ferner Defektgruppen der Gesteine kinematisch auf ihren Einfluss auf Massenfestigkeit. Le critère de rupture de Hoek-Brown est souvent utilisé sur une variété de roches plus étendue que les masses rocheuses auxquelles il est strictement applicable. Ce travail évalue la distribution des défauts au sein d'une masse rocheuse en utilisant une projection sphérique des contours d'échantillons d'orientations générées aléatoirement et de données de cartographie provenant de greywackes à joints rapprochés de Nouvelle Zélande. Deux indices de cette projection - la zone des contours en dessous de 1 % (A1%) et celle de concentration maximum (Cmax) sont introduites pour distinguer les répartitions uniformes (isotropes), aléatoires ou régulières. Ces indices fournissent une extension potentielle aux règles d'utilisation du critère de rupture de Hoek-Brown. Ce travail utilisent également les contrôles cinématiques pour évaluer l'influence des groupes de défauts sur la résistance de la masse rocheuse.

Jan 1, 2003

By R. G. Garrett, A. J. S. Geddes

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). The 1986 geochemical survey was successful in recognising all the previously known mineral occurrences of significance in Jamaica, in outlining areas not previously believed to have mineral potential and in stimulating fresh appraisals of old occurrences in terms of their potential for new commodities. This has resulted in a very significant increase in mineral exploration activity in Jamaica

Jul 1, 1991

By Len Harris

Webster?s Dictionary describes culture as: ? The totality of socially transmitted behavior patterns, arts, beliefs, institutions and all other products of human work and thought typical of a population or community at a given time. ? A style of social and artistic expression peculiar to a class or society. ? Intellectual and artistic activity. ? The art of developing the social, moral and intellectual facilities through education. The authors have nearly 100 years of combined experience in the mining industry working with and consulting to mining companies and companies engaged in the supply of goods and services to the mining industry worldwide. In this report, they present their experiences and ideas on the importance of cultural aspects in the successful development and implementation of mining ventures. Their suggestions on how to handle culture shock will be of interest to expatriate managers, operators, social workers, and engineering and construction personnel posted to overseas operations, as well as to nationals posted to other parts of their own country.

Jan 1, 2008

By J. C. W. M. de Wit

An excavation, within which a tunnel is sunk as a part of the Centraal Station underground station (platform section) of the Noord/Zuidlijn ('North/South Line'), is to be created beneath the Amsterdam Centraal ('Amsterdam Central') station. The section beneath Amsterdam Centraal Station is characterised by the application of a particular technology in the form of, inter alia, the so-called 'sandwich wall'. This is a composite wall consisting of two rows of Tubex piles with a body of jetgrout columns in-between. This wall acts both as an excavation support wall and also provides vertical bearing. The installation of the wall, including both Tubex piles and jetgrout columns, within these specific conditions (limited height, sensitive historical building), within the design requirements set in terms of construction tolerance and water and soil retention, may be regarded as being a pioneering achievement. The environmental constraints are that the trains should continue to run, the inconvenience to passengers should be kept to a minimum and the historic station should not suffer any damage. Because of the complexity of the working conditions, the project is being overseen by a steering group of experts in the specified construction processes. In order to manage the project risks, jet grouting trials were initially carried out, in order to highlight and control execution problems; the practicability of the design is then tested. Work commenced on the sandwich wall in 2003, when the wooden piles were extracted at the locations where the sandwich wall was to be constructed; in 2004, the steel Tubex piles for the southern wall sections were installed. From May 2005, the construction of the sandwich wall got under way; in addition to the described process supervision, an extensive measuring programme was established, so that the process could be adjusted as necessary and the quality of the finished product determined. This applied to both individual columns and for the end product, the sandwich wall. The measurement results were processed for each column, interpreted and the effect on the work still to be conducted was assessed for each future column. Preventative and corrective measures were, if necessary, taken in order to control or counteract the measured defect. In addition to the process-oriented and qualitative measurements, various independent measurement systems at the station building served as a further control in order to prevent damage to the building.

Jan 1, 2006

By D. Potter

In 1990, Freeport Exploration began regional reconnaissance exploration programs in Irian Jaya, the easternmost province of the republic of Indonesia (Fig. 1). Irian Jaya occupies the western half of the island of New Guinea. Freeport was awarded an initial contract of work that totaled 2.6 million hm2 (6.4 million acres). The company was subsequently awarded additional concessions that added 1 million hm2 (2.5 million acres). The concessions require work commitments and periodic relinquishments. Due to these relinquishments, Freeport’s current land position totals 1.9 million hm2 (4.7 million acres). Freeport began the exploration program to locate additional Grasberg deposits, the largest deposit in the Ertsberg district. But the company recognized that other types of deposits could be present in the largely unexplored area of Irian Jaya.

Jan 1, 1999

By L C. Taylor, H U. Lesiste

This is a preliminary study of the statistical variation of the pressures on a target above a buried explosion. The data were taken at various distances from the charge centerline for three heights of the target above the soil and one charge depth of burial. All tests were conducted in saturated sand. They show that peak pressures and times of peaks are neither repeatable from shot to shot nor rotationally symmetric within a single shot. The peak pressure and time of peak at each location can be represented by cumulative normal distributions. The paper describes the means and standard deviations of these distributions at eight distances from the charge center for each height of target. These are used to determine the change in standard deviation of the distribution with distance from the charge centerline and height of target. The effect of scale on the mean peak pressures and times of peaks and on their standard deviations at a single scaled distance from the centerline of the charge are explored using various charge weights.

Jan 1, 2010

By TvS. von Moltke

Steel is a highly versatile material due to its low cost and good mechanical properties, but typically needs some or other form of corrosion protection due to its tendency to corrode when exposed to atmospheric conditions. In the case of organic coatings, the corrosion protection and functionality of the final product is critically dependent on the adhesion of the coating to the surface of the steel. In this work the effect of contaminants and the nature of the surface layers present on industrial steel products are investigated by means of paint adhesion tests, Auger electron spectroscopy (AES), and X-ray Photoelectron spectroscopy (XPS). It was found that the presence of sodium species on the surface is very detrimental to paint adhesion under wet conditions, while satisfactory adhesion may be obtained even in the presence of silicon and carbon residues. It was also found that the nature of the Fe-O layer, formed under wet conditions is labile and different from that formed in dry air, and that subtle changes in process conditions, such as changing the oxygen content of the quench water, may change the adhesion of paint to the surface of the steel. Lewis acid-base interactions are discussed as a mechanism that may determine the bonding between the steel and polymer coating.

Jan 1, 2003

By Leslie F. Ruppert

The US Geological Survey (USGS) is currently conducting a coal resource assessment of the coalbeds and zones that are projected to provide the bulk of the nation’s resources for the next few decades. The Pittsburgh and Upper Freeport coals are the first two beds in the northern and central Appalachian basin region to undergo fully digital coal assessments. The bed-specific assessments are being carried out in partnership with the state geologic surveys of West Virginia, Ohio, Pennsylvania and Maryland. Comprehensive stratigraphic and geochemical databases have been developed for both of the beds. The extent of the bed with mined areas, structure contour, isopach, and overburden thickness maps for the Pittsburgh coal bed have been released as USGS open-file reports.

Jan 1, 1999

To many Australian Mining Engineers, we take it, the singular features of banket deposits are not as familiarly known as they would wish, possibly because in the majority of instances they are not in touch with the South African milling world, and have had little opportunity of studying the development of the banket beds, either from correspondence or literature. The writer hazards this opinion feelingly, because, when in Australia and before he had visited Africa, the utmost knowledge he was able to obtnin was a mass of conflicting theoretic discussion as to the agencies which formed the banket bed, without any practical hints as to their geological horizon, the rocks with which they are associated, the usual appearance and character of the ore, in fine, without that everyday detailed description which the miner requires when seeking information regarding mineral or metal deposit foreign in character to any that he has yet studied, or as yet had any opportunity of studying in his own country.The writer recognised that many more able men than he have from time to time discussed the features and formation of the banket beds of the land, notwithstanding which and feeling that many of his Australian colleagues have found themselves in a similar position regarding accurate detailed information respecting these African banket deposits as he himself was, he hopes that the present paper on the said deposits, as found on the fields under notice, will prove useful to some and of interest to all.

By R. J. Boyd

SUMMARY The productivity of drill and blast methods of mining in hard rock is limited by the cyclic nature of the operation, and a plateau of performance has been reached, even with the most advanced equipment developments. Higher mine operating costs and lower metal prices have more than ever generated the need for breaking through these productivity barriers. After initial field testing The Robbins Company has designed and manufactured, on a joint venture basis with Mount Isa Mines, Ltd., Australia, a prototype "Mobile Miner" for continuous cutting of hard rock. This paper describes the cutting concept, the initial application of a completed 1,156 m (3792 ft.) long 14% decline, actual performance and delay analysis, developmental modifications, anticipated performances of a fully developed machine, and possible future applications. Sincere appreciation is expressed to the management of Mount Isa Mines, Ltd., for allowing access to the data used in this paper. The views expressed here are those of the author and not necessarily those of Mount Isa Mines, Ltd. INTRODUCTION A paper titled, "Design and Development of a Mobile Mining Machine", was presented by J.P. Kindsvater at the RETC, New York, in 1985. This paper described the evaluation of a test fixture in an andesite quarry near Seattle, followed by design, construction and

Jan 1, 1987