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By Lok M. Sharma

"Construction of a new bridge in a seismically sensitive area requires careful assessment of earthquake impact on the serviceability of the facility. Not only is the superstructure vulnerable, the foundations play a key role in the bridge’s survivability. A new bridge in eastern part of the state of Missouri in the U.S.A. is located in a seismically active area and hence subject to additional thrust on the foundations and superstructure and potential damage due to liquefaction. An eleven span bridge with foundation soils varying from shallow bedrock to over 30 m (100 feet) overburden soils were considered for the bridge support piers. Two of the bridge support bents located within the flood plain area through over 30m (100 feet) of alluvial deposits were considered most affected by an earthquake event due to the additional thrust and lateral ground spreading. This paper describes the determination of site specific seismic hazard, numerical modelling of the foundation system, and methodology of dynamic analyses, effects of lateral spreading and liquefaction potential on bridge support bents. From numerical modelling using FLAC, the increase in thrust on piers and deformations were computed to predict the behavior of the foundations.INTRODUCTIONA newly constructed bridge on route US 40 crosses the Missouri River west of St. Louis, Missouri and upstream of Mississippi River in mid-west USA. The west abutment area has near surface bedrock while the east abutment area has overburden deposits over 30m (100 feet) thick, mostly river sediments comprising of silts, lean clays and sands overlying bedrock. Softer layers of silts and sands in the east river bank area are assessed to be liquefiable during a high magnitude earthquake event. St Louis area has a potential for a high magnitude earthquake due to the New Madrid Fault some 160km (100 miles) south. The bridge foundations were designed as drilled piers, 2 m (8 feet) in diameter and socketed into the bedrock. Bents No. 10 and 11, located in the lower flood plain area of the river, are considered to be most affected by a seismic event.In order to perform dynamic analyses of the foundations, earthquake ground motion time history was developed for the specific site using a Probabilistic Seismic Hazard Analysis (PSHA) and selecting and scaling of a recorded time history. Relying on the U.S. Geological Survey (USGS) Earthquake Hazard Program for the PSHA and AASHTO Guide Specifications for LRFD Seismic Bridge Design, spectral acceleration values for the site were developed. The spectral acceleration values were for a 7 percent probability of exceedance in 75 years (1000 year return). Numerical modelling using FLAC computer program was performed. This paper presents the seismic design parameters, methodology used in the dynamic analyses, static and dynamic analyses, impact and mitigation of liquefaction on Bents 10 and 11 and the abutment fills, and effect of lateral spreading on the foundations in the lower flood plain area of the bridge. From the numerical modelling, increase in thrusts on pier foundations and estimated deformation were computed."

Jan 1, 2017

By Roy S. Nutter

The automation of coal mining must occur in a manner that is economically beneficial to the industry and that enhances the safety of the underground and surface workplaces. The work at WVU over the last five years in applying expert systems and neural network controlled autonomous robotics provides the mining industry with tools that when properly applied should clearly lead to mine-wide management and operational improvements and should also contribute to a higher awareness of safety issues by all work crews. This work includes the development of MMSS (Mine Management Support System) and the detailed development of autonomous robotics utilizing neural networks for mining systems.

Jan 1, 1993

By Bruno Deves Flores

O presente trabalho tem como objetivo investigar a influência da adição de carvão vegetal e do seu tamanho de partícula na reatividade do coque. Para isso, um carvão vegetal de eucalipto foi adicionado a um carvão médio volátil americano em três teores (3%, 5% e 8%) e em duas faixas granulométricas distintas (abaixo de 1 mm e entre 3 mm e 4 mm). O carvão individual e as misturas de carvão/carvão vegetal foram carbonizados em um forno de escala laboratorial (1 kg). A reatividade dos coques produzidos e do coque de referência foi avaliada e comparada usando análise termogravimétrica. Também foram realizadas análises morfológicas através de microscópio óptico e eletrônico, usando amostras antes e após os ensaios termogravimétricos. Baseado nos resultados, a influência da introdução de carvão vegetal na reatividade do coque foi analisada e discutida neste trabalho.

Aug 1, 2018

By M. J. Sapko

A moderately scaled apparatus was developed by the Bureau of Mines to determine the fire resistance characteristics of mine conveyor belts and similar type materials. The design of the apparatus was based upon data obtained in full-scale fire tests and features a radiant panel to preheat the belt and a methane-oxygen ribbon burner to ignite the sample under ventilating condi¬tions in a rectangular duct. The test method overcomes the limitations of existing laboratory-scale methods and provides a measure of both ignitability and flammability in quantitative terms. Flame propagation depended upon such variables as air velocity, ignitor heat flux, and belt width and height in the test chamber. Data are presented for nine belt materials and fire resistance ratings are proposed in terms of the flame spread rate, heat release rate, and the critical ignitor heat flux. The ratings discriminate between the fire hazard posed by different fire-resistant belts and tend to be in reasonable agreement with those obtained in full-scale fire tests.

Jan 1, 1981

By R. Patrick

As a unique South African organisation, CSIR: Division of Mining Technology (Miningtek) strives to support the mining industry by improving health, safety and productivity through developing, adapting and transferring technology. Considerable effort is currently directed towards the development of potential non-explosive mining methods with the potential to allow continuous mining in narrow reef conditions. Besides improving productivity, continuous mining results in concentrated mining which has a significant impact on reducing infrastructural costs. Impact Ripping and Water Pulse Rock Breaking have been tried on gold mines, whereas Activation, Mini-Disc? cutting and the Plasma Holemaker are currently being tested on platinum mines. The organisation?s many years of experience in novel rockbreaking, together with its world-wide collaborator network, has placed it in a unique position to assist the mining industry and manufacturers in developing and/or adapting existing technologies for application underground. Currently a range of technologies are being investigated, which have reached different stages of maturity. The main technologies under investigation are; - Impact ripper system - Water pulse rock breaking - Activated undercutting rollers - Mini disc cutters - Electric rock breaking

Oct 1, 2001

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.

By Jesse R. Jacobson

A large casino complex in Cherokee, North Carolina recently underwent a $633 million expansion that involved substantial foundation challenges. The site is located in a valley on the southern edge of the Great Smoky Mountains National Park, where subsurface conditions typically consist of varying thicknesses of fill overlying alluvium, residuum, partially weathered rock and rock. The fill and alluvium contain cobbles and boulders as large as several feet in diameter. The residuum and partially weathered rock are very thick in some areas, and the depth at which consistently high quality rock is encountered is highly variable. To reduce the foundation costs for the expansion, continuous flight auger (CFA) piles were proposed in lieu of micropiles. CFA piles are not generally used in this geologic environment and concerns regarding their selection included: (1) an uncertainty that CFA piles could be successfully constructed given the difficult conditions and (2) a lack of regional data regarding unit resistance values and load transfer characteristics. To address these concerns, a design-phase test program was undertaken to evaluate pile constructability, develop an understanding of the load transfer behavior, and establish the required pile lengths. The program included soil test borings, shear wave velocity measurements, timed auger probes, instrumented pile load tests and observation of exhumed piles. It was demonstrated that CFA piles could be advanced through the fill, cobble/boulder-laden alluvium, residuum and into the partially weathered rock, albeit with some limitations. Under axial loading, the pile response was very stiff and relatively high unit resistance values were measured. Pile instrumentation allowed for the evaluation and use of design pile lengths shorter than that tested, and the overall reduction in pile lengths yielded a 40 percent reduction in foundation cost. In general, CFA piles were determined to be a suitable, economical foundation alternative.

Jan 1, 2011

By J. L. Morning

During recent years, the Bureau of Mines has conducted an extensive investigation of the materials for making iron and steel. This work includes iron ore concentration, agglomeration, direct reduction of iron ores and concentrates, the production of pure manganese, chromium, and cobalt by electrolytic processes, the production of ferroalloys from low-grade domestic ores, and the development of special alloys to utilize these products. As a part of this general program, a Congressional appropriation allowed the con¬struction of an electric-furnace, semicommercial, ingot-producing plant at Shasta Dam near Redding, Calif. The primary objectives of the pilot plant were to determine the costs and operating problems involved in the production of steel and ferrous alloys in which sponge iron was used as melting stock, and to determine the physical properties of the materials produced. The pilot-plant equipment and the results of sponge iron-melting tests in the basic lined, electric arc furnace have been reported in previous publications.3/4/

Jan 1, 1953

By Vincent Roy

Numerous on going activities at the Daniel-Johnson Dam : ? Surveillance / monitoring ; ? Structural investigations & evaluation ; ? Injection work ; ? Crack mapping ; ? Instrumentation management (drawings & inventory) ; ? Drainage system state ; ? Foundation evaluation

Aug 1, 2013

By L. Villa, O. Suarez, D. Arias, L. G. Corretge

The deposit comprises two vertical, lenticular bodies emplaced in the allochthonous block of a Variscan thrust. Epigenetic mineralisation occurs as replacement of carbonated volcaniclastic rocks of Cambro-Ordovician age. The dominant sulphide minerals are sphalerite and galena with minor chalcopyrite; the main non-metallic mineral is quartz and there is hydrothermal silicification, chloritisation and sericitisation. Sulphur isotope values for sphalerite and galena are heavy and reflect the fundamental relationship between delta-34S in ZnS and in PbS, suggesting isotopic equilibrium. Four sphalerite-galena pairs yield temperatures between 163 and 218 degrees C, in good agreement with the 187-207 degrees C estimated by the Ga/Ge-sphalerite geothermometer. The ore sulphide was leached by the hydrothermal solution from diagenetic pyrite in the host rocks and disseminated sphalerite and galena in Cambrian carbonates

Jun 19, 1905

By Alvaro Ordoñez

El presente texto describe el nuevo método para la obtención de cobre por lixiviación de minerales mixtos de cobre en medio básico, donde la disolución de minerales mixtos de cobre se realiza a través de un medio lixiviante compuesto de hipoclorito (lejía) y amoniaco en un medio básico. En ese sentido, se busca extraer cobre, a presión y temperatura normales por lixiviación con cloro acuoso - amoniaco, a partir de minerales oxidados y mixtos, así como recuperar el cobre contenido en el PLS mediante electrodeposición directa, obviando la etapa intermedia de extracción por solventes, para obtener como producto final cobre catódico.

Sep 12, 2011

By R. Van A. Mills

Rapid deterioration and destruction of metal equipment in oil and gas fields cause waste of resources and financial losses that must be lessened or eliminated if operations in many important fields are to continue profitable. The magnitude of this destruction is proved by the huge consumption of iron and steel pipe, tubing, casing, pump valves, and sucker rods to replace worn-out equipment, and by the amount of such equipment that is left in wells or junked. (See PI. I, A and B, and PI. II, A and B, and Fig. 14, p. 61.) This destruction of equipment constitu~es in itself a serious waste, but contingent production troubles, such as underground leakage of oil through defective tubing and pumps, and the consequent loss of oil and gas because of damage to pay sands by infiltrating water and silt, frequent and costly repairs with necessary suspension of production, and the ultimate injury to or loss of valuable wells, often cancel all operating profits. Many of these troubles result from rapid destruction of metal equipment by corrosive waters. The strata penetrated by the wells usually contain saline waters. Certain types of these waters, with their associated gases, are intensely corrosive; they attack well casing or tubing so vigorously as to riddle it with holes, rendering it useless in a few years or even a few months or weeks after it is installed. Pump plungers, working barrels, balls and seats of valves, and screen pipe, as well as lead lines and other surface equipment, are ruined with equal rapidity. The development and application of practical methods to retard or prevent this corrosion are among the most urgent problems of the oil and gas industry. Although much progress has been made in preventing the corrosion of metals, the need for reducing the damage from corrosion in oil and gas fields is still imperative. This is especially true of underground corrosion in the wells, because underground conditions favor corrosion and are difficult to study; hence they have not been thoroughly understood. In efforts to stop ~amage to oil and gas field equipment by corrosion, numerous methods have been proposed or tried with varying success. Some of these methods are cheap and effective. However, it is surprising that in many important fields the damage by corrosion is accepted as necessary or unavoidable, although cheap and effective methods that have been developed and successfully tried elsewhere might greatly reduce the trouble or eliminate it. This bulletin describes common causes and effects of oil and gas field corrosion and outlines methods of abating the damage. In order to accomplish this purpose best, the writer has avoided taking sides in controversies between the advocates of different metals for oil-field use; instead he describes the methods of combating corrosion in the various fields and suggests experiments that may yield valuable results. Throughout the paper he has freely used information from published reports of other investigators.

Jan 1, 1925

By Edward H. Jr. Boyle, Paul R. Thomas

Introduction It is estimated that nearly 40% of all the gold ever mined in free world countries has been produced by South African operations. There is concern that this immense productive capacity will soon decline. Such a decline could reduce world gold supply and lessen the ability of market economy countries (MEC) to exert the major influence upon the world gold market. This paper addresses three general issues concerning South African gold production: • How much gold remains to be recovered from the demonstrated resources of the 44 evaluated South African mines; • How long can production at current levels continue; and • What will be its cost. Table 1 provides production data on the world's 10 largest producers for the years 1971, 1981, and 1983. As shown, South African gold production declined significantly from 1971 through 1981. As of 1981, annual South African gold production had dropped by more than 311 t (10 million oz) in 10 years. Despite this, its mines still produced 656 t (21 million oz) that year, about half the world total. From 1981 through 1983, this trend was reversed. Annual South African gold production increased by more than 21.8 t (700,000 oz). The trend reversal was also evident in the US, Canada, and Australia. This illustrates the general, inverse relationship between gold price and gold production. In South Africa especially, as gold prices increased substantially during the 1970s, the average grade of ore mined (pay limit) was lowered as new, lower grade areas and materials were exploited. Gold production declined in volume. But gold revenues increased, and the lives of the operations were extended. The 1981-83 period was one of declining (US dollar-based, average annual) gold prices that resulted in increasing South African production as average ore grades were raised. South Africa currently accounts for 50% of world production (Fig. 1). Figure 2 illustrates South Africa's contribution to total MEC production in 1971 and 1983. Although South Africa's relative share of production has declined, it still represents the single most important source of new gold supply. In 1983, it supplied more than 65% of total MEC production. South Africa currently produces more than twice as much gold as the Soviet Union (ranked second in world production), and 11 times more gold than the US (ranked fourth in world production). Barring major discoveries, South African gold production is expected to peak in 1987 and begin to decline again throughout the 1990s. The rate of decline is ex-

Jan 11, 1984

By P. W. Godbehere

"INTRODUCTIONMagnetic mill linings have been developed from an invention by Mr. Bertil Brandt, the originator of the Skega rubber lining. The OREBED magnetic mill lining is a concept in which rubber covered strontium ferrite permanent magnets are arranged on the inside wall of a mill shell so that they attract magnetically susceptible material be it ore, media or tramp, to form a protective layer over the magnets and to serve as an operating surface with indefinite life.Noranda Mines Ltd. through its associate Norcast Division of Noranda Metal Industries formed a joint venture with the inventors to market magnetic mill linings in North America. For the past twelve months trials have been undertaken in conjunction with Orebed Inc. to test and develop these linings for grinding mill applications at the Horne Concentrator. Two independent milling circuits are currently being operated, one treating a siliceous gold ore and the other a copper slag.This paper presents the results of the magnetic lining test programme to date."

Jan 1, 1983

By Sanford J. Douglas

This publication describes a study by the Federal Bureau of Mines of devices and methods used for testing and splicing 4,160-volt and 440-volt cables and for providing ground-fault protection for 440-volt circuits, as developed and used by the electrical staff of the Tecumseh coal mine, an open-pit operation at Boonville, Ind. The testing and ground-fault devices described should find ready application in other open-pit mines, and, with suitable modifications for voltages involved, in underground mining. The devices and testing methods are based on sound engineering principles and are time-tested and economically feasible, Four devices are used: A high-voltage tester, and a low-voltage high- current tester, both for testing 4,160-volt cables; a tester for 440-volt cables; and, electronic ground-fault protective device for 440-volt cable circuits. All the cable testers and the grounding device were designed and built at the mine from standard parts. They are inexpensive, dependable, and job tested, An attempt has been made here to describe them in enough detail so that interested persons can assemble duplicate units.

Jan 1, 1960

By Bengt H. Fellenius

THIS PAPER deals with the analysis of results from axial testing of vertical single piles, i.e. the most common field test per-formed. Despite the numerous tests which have been carried out and the many Papers which have reported on such tests and the analysis thereof, the understanding of pile test loading in current engineering practice leaves much to be de-sired. The reason for this is that the engineers have concerned themselves with mainly only one question: "Does the pile have a certain least capacity?", finding little of practical value in analysing the actual capacity and the pile-soil interaction. This Paper aims to show that engineering value can be gained from elaborating on a pile test ? during the actual testing in the Held, as well as in the analysis of the results. The first portion of the notes make use of an earlier Paper by the author (Fellenius. 1975). However, additional views and recent literature have been incorporated.

Jan 1, 1988

In referring to two subjects of interest to the Members of this Australasian Institute of Mining Engineers, I would at the outset desire to express our gratification that to-day we are able to welcome as now united with ourselves, those members who until recently constituted the New Zealand Institute. It is hoped that the amalgamation so amicably arranged may be productive of the best results to all concerned, incorporated as this combination has been at the moment of the fulfilment of that greater political union, the Australian Commonwealth.Since last Annual Meeting held in Brisbane, we have come under the same roof as the Chamber of Mines of Victoria, and we entertain the hope that as that Chamber and this Institute possess so many interests in common in the encouragement and advancement of mining and metallurgical progress in these colonies, that much mutual benefit will ensue. There are many directions in which each body can assist the other, and I trust that a friendly co-operation will be maintained.It is gratifying to feel that in all the colonies a distinct movement is being made to increase the facilities for education in Mining and Metallurgy but if I may refer to our colony of Victoria in particular, we have to express the profound regret that in the means of education in the higher branches, we occupy an inferior position, and it is quite certain that we will continue to do so unless the Government is prepared to subordinate provincial considerations to the weightier.

Jan 1, 1901

By Rose L. Ballard

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Included also are the tables that show the principal nonfuel mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of volume I and in the State chapters of volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is ordinarily termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1983

By C. R. Summers, J. N. Murphy

In response to the Coal Mine Health and Safety Act of 1969, mandatory noise standards have been developed that specify time-noise limits of mine personnel exposure. Most affected by elevated noise levels is the pneumatic roof bolter operator, both in terms of levels near or in excess of 115 dbA and in terms of length of exposure. Therefore, the principal emphasis of this Bureau of Mines report is on pneumatic drill noise control. It is not the intent of this report to suggest any drill redesign; instead, methods are suggested to reduce the noise level by complementing existing machines. An integral muffler system and a separate muffler system were tested in an attempt to lower pneurnaric drill noise levels. Pneumatic drills, when new, operate at about 115 dbA when drilling in sandstone. Using the drill muffler systems, it was possible to decrease the noise level of a 115 -dbA s rope drill to approximately 100 dbA.

Jan 1, 1974

By Haigh J. E

An accurate measure of the earth's magnetic field can be made in a few seconds with the portable proton precession magnetometer. Such an instrument increases the applicability of the long successful method of magnetic prospecting for minerals. As an example of the usefulness of the proton magnetometer, a survey over volcanic rocks near Apsley (Tas.) was made.INTRODUCTIONA completely portable magnetometer whose operation is based on the free precession of polarized protons in the earth's magnetic field, is now available on the market at a price competitive with magnetometers based on the classical physical principles. The ease, accuracy, rapidity, and reliability with which measurements of the earth's total magnetic field can be made with the proton precession magnetometer, led to the try-out of the instrument in an actual field problem so as to evaluate fully the capabilities of the instrument. Such evaluation is important, because the history of magnetic prospecting has shown that whenever significantly improved instrumentation has been introduced, prospecting costs have been substantially cut and many areas in which the prospecting costs were formerly considered excessive in relation to probable returns, have become economic mineral prospects. The proton precession magnetometer offers the possibility of opening up new areas for successful magnetic prospecting.AN OUTLINE OF THE HISTORY OF MAGNETIC PROSPECTINGWhile an outline of the history of magnetic prospecting is not directly connected with the evaluation of a proton pre...

Jan 1, 1963