Search Documents

By G. W. Jones

In cooperation with the Edison Electric Illuminating Co. of Boston, Mass., and the-Boston Consolidated Gas Co., the Bureau of Mines, United States Department of the Interior, has conducted a survey continuously since 1929 to determine the general hazards of combustible gases and vapors in manholes of the Edison Electric Illuminating Co.

Jan 1, 1942

By James J. Graham

Uravan, Ambrosia Lake, Gas Hills and South Texas are all historic names in US uranium. These mining areas supplied the uranium that brought the United States into the nuclear age during the 1960s, and fueled the birth of nuclear energy for peaceful uses — a promise of nearly limitless, clean energy for the world’s future. That promise still exists today, but it is hard to hear over the rhetoric of environmental activists and politicians. Nuclear power offers dependable electricity with limited environmental impact at stable prices. Nuclear power releases no greenhouse gases or particulate matter into the atmosphere. High level nuclear waste (HLW), although long lived, is readily controlled and compact. In the United States, generating 1 billion kWh of electricity with coal produces 47 kt (52,000 st) of solid waste (ash and sludge), compared to 3.6 t (4 st) of HLW produced by nuclear.

Jan 1, 2002

By Kevin Landey, Eric Gerst

Expanding blast patterns to near the limit of an explosives’ ability to do the necessary amount of work is a common practice to reduce drilling and blasting costs. Choosing less expensive explosives such as ANFO vs. emulsion, bulk product versus packaged product, etc. are also common cost savers. Both practices are only effective as long as the pattern geometries are accurately drilled. However, will pushing the limits on pattern sizes and explosive products produce consistent results at the face, minimize oversize, produce superior fragmentation, and improve crusher throughput? Sometimes, but no amount of explosives can overcome a poorly drilled pattern. Knowing the probable outcome of any changes in drilling and blasting is valuable in achieving success.

Jan 1, 2018

By K. Shoji

Residence time distributions (RTDs) were estimated by water tracing in a number of wet overflow ball mills (diameters 0.38 to 4.65 m) producing dense, coal-water slurries. In open-circuit mills of 0.38 m diameter and various length-diameter (L/D) ratios, the mean residence times of solid were also determined from measured mill holdups. Holdup increased with increased mill feed rate, but the mean residence times of coal and water were still equal to each other. The experimental residence time distributions were fitted to the Mori-Jimbo-Yamazaki semi-infinite, axial mixing model, and the dimensionless mixing coefficient was determined for each of 25 tests in single- and two-compartment mills. This coefficient was found to be independent of the feed rate but linearly proportional to the D/L ratio. The mixing coefficient was smaller for two-compartment mills than for single-compartment mills, showing that there was reduced mixing introduced by the diaphragm separating the compartments. Equations are given to scale residence time distributions for changes in mill diameter and length.

Jan 1, 2008

By G. W. Jones

In a previous report'/ results were given and a method outlined whereby from a knowledge of the composition of the natural gas and of the inflammability limits of the individual constituents composing the natural gas, the limits of inflammability of natural gas and air mixtures could be closely calculated. This method is based on the application of Le Chatelier's law as modified by Coward, Carpenter and Payman,5/ to apply to a mixture of any number of combustible gases. This law must not be used indiscriminately, because many exceptions have been found. For example, when ethylene, acetylene, hydrogen sulphide, or chlorinated hydrocarbons are present the law may not hold. For a discussion of the many exceptions which have been found, reference should be made to a report by Coward and Jones.6/

Jan 1, 1933

By Y. P. Chugh

This is the final report of a study done by IIT Research Institute for the Bureau of Mines to identify the problem areas and technological inadequacies in noncoal (metal, nonmetal, stone, and sand and gravel) mining and processing systems that are the primary causes of death, injury and occupational disease, and to make recommendations to improve safety and health in these operations. The findings and recommendations presented in the report are based on: (1) analyses of MESA injury and employment data for the period 1961-70, MESA fatality reports for underground noncoal mines (1968-72) and lost time accident data for 1970-72 obtained from mining and processing operation: (2) visits to a variety of noncoa1 mines and mills throughout the country to observe the operations and to study the safety organization and practices used in the industry and (3) interviews with industry and government representatives knowledgeable in the field of noncoa1 mining and processing safety and health. The report provides a comprehensive overview of safety and health problems.

Jan 1, 1974

By D Craw

Uplift of the antiformal ranges in Central Otago, New Zealand , has resulted in the progressive evolution of eluvial placer deposits in tectonic sediments on the range flanks and along their margins. The placers are derived from the reworking of fine-grained gold from the auriferous Manuherikia Group fluvial sediments which covered the basement prior to uplift of the ranges. Gold in the tectonic sediments at Matakanui shows a progressive increase in grainsize in successively younger sediments and nuggets in the youngest gravel sequence are up to two orders of magnitude larger than gold grains in the parent alluvial source. Most of the gold in the tectonic sediments is highly irregular in shape, commonly with delicate surface textures which could not have survived fluvial transport and are indicative of authigenic precipitation. Some coarse grains have been rounded by recycling, and further addition of authigenic gold has occurred. Placer gold values result from both physical and chemical enrichment during sedimentary recycling. Continued range uplift and back-thrusting of sediments on to the ranges results in recycling of earlier formed placer sediments. They also result in further enrichment of gold values through the incorporation of additional supplies of the parent alluvial source sediment The host sediments are widespread along the ranges and are not confined to sites of historic mining activity.

Jan 1, 1992

By C. Dixon

This paper is based on the assumption of some knowledge of the National Water Act. It will consider the question of how that Act fits in with: a) existing laws which overlap on the subject matter b) new laws either in draft or in the process of being compiled c) policies which will eventually find their provisions included in new legislation (e.g. minerals policy) d) international practices. The focus will be specifically on the interaction of legislation relating to water use and water pollution in the mining sector as well as the role of the Department of Water Affairs in mining matters. Hence the title of the presentation.

Jan 1, 1999

By Richard Stayner

Suspended seats perform two functions: Reduce effect of occasional large bumps; Reduce more continuous vibration at a lower level. The former needs high damping. The latter needs low damping. For most mobile work machines the inevitable compromise is generally better than a simple cushion seat, because that amplifies vibration at around 4 Hz which is a sensitive frequency for human vertical WBV. Why have standard tests for seat suspensions? • Seat suspensions are non-linear so any measure of performance depends on operating conditions. For comparison these need to be defined. • Seat manufacturers need benchmarks for product development; • Machine makers choose dynamic characteristics appropriate to their products; • Occupational health specialists wish to control operator exposure to Standard tests should be representative, repeatable and reproducible. These requirements are reviewed in relation to the history of seat test standards and the current position. Current position and history The current position is that we have standard tests for seats for agricultural tractors, earthmoving machinery, industrial (fork-lift) trucks. These tests comprise measurement of vibration transmission and of the rate of damping. Current standards developed as the technology developed, starting around 1960: 1. Test on machine driven over standard surface1. 2. Test on shaker reproducing standard surface. 3. Shaker input replaced by representative spectrum2. 4. Human subject replaced by dynamic dummy. (Not yet settled). Are standard tests representative? The development process has gradually moved seat tests further from reality. 4 hr samples of work exposure suggest that seats do not on average provide large reductions of vertical WBV3. For specific magnitudes of vibration they can work well. For low vibration, performance is reduced by friction and for severe vibration by length of travel. Recent work has led to a new test to quantify how a suspension controls over-travel 9.

Jan 6, 2006

By James C. Barker

The U. S. Bureau of Mines made a reconnaissance In the western Crazy Mountains for cobalt and associated metals as part of the Alaska-wide critical and strategic metals program. The area, located about 75 miles north of Fairbanks in central Alaska, is underlain by complexly faulted, predominantly clastic sedimentary rocks bordering the Tintina Fault system. Above background metal concentrations were found to occur in altered fault zones, tectonic breccias, soils, and ground water seeps and precipitates that either cut or are derived from the faulted clastic sedimentary rocks. Up to 0.115 pct cobalt and more than 2.0 pct zinc were detected in soil samples. Spring precipitates contained up to 1.3 pct zinc, 0.037 pct tungsten, and other metals. Some localities lacked cobalt but contained anomalous amounts of copper, lead, zinc, silver, and other metals. No outcropping of primary metallic minerals was located because of Colluvium and vegetation cover and extensive deep leaching. Therefore, whether the metal values encountered are due to primary deposits with economic development potential or are the results of concentration by ground water from low-grade sources is unknown. The presence of cobalt, nickel and zinc, and the identification of minor tin and tungsten indicate that further investigation is warranted.

Jan 1, 1983

By J. Maiti

This study examined the group differences in accident susceptibility among underground coal mine workers accounting for their personal and workplace characteristics. A logistic regression model was used for this purpose. Data were collected from five underground coal mines for a period of four years. The case study results revealed that different age and experience groups of workers bear no significant differences in their accident susceptibility; however, the workplace location and occupation groups show significant differences in their risk of injuries. It is inferred based on the logistic model results that among the three occupation groups, the face workers are more susceptible towards accidents/injuries compared to the haulage and other workers. Key Words: Mine Safety, Accident Susceptibility, Group Differences, and Logistic Regression.

Jan 1, 2001

By Mark Fennel

The present paper describes the operation and application of the QEMSCANTM automated applied mineralogy technology and how it is been utilized for long range planning by characterizing and optimizing the primary sulfide reserve while providing operational support of the ongoing secondary sulfide leaching operation at the Cerro Verde Mining Complex in Arequipa, Perú.

Sep 12, 2005

By K. S. Rao, R. P. Tiwari, V. K. Shrivastava

ABSRACT: In this paper numerical simulation of jointed block mass behaviour obtained in an experimental study has been presented. Singh et al. (2002) conducted extensive tests on the jointed model materials with several joint configurations. The results of this experimental study were used to validate the strength behaviour of numerical block mass model developed using professionally available software. This software basically contains different kinds of material models. From the results of numerical simulation the existence of strength anisotropy was observed. The strength anisotropy so obtained has been compared with the experimental values reported by Singh et al. (2002). The anisotropic curves in both cases are U-shaped with flat base. They show good agreement in sliding mode of failure zone in which inclination ß (= 90° - ?) of joint set-I lie between 20° to 40° for all cases of interlocking. ZUSAMMENFASSUNG: In dieser numerischen Papiersimulation des verbundenen Blockmasse Verhaltens, das in einer experimentellen Studie erhalten wird, ist dargestellt worden. Singh et al. (2002) leiteten umfangreiche Tests auf den verbundenen vorbildlichen Materialien mit einigen gemeinsamen Konfigurationen. Die Resultate dieser experimentellen Studie wurden verwendet, um das Stärke Verhalten des numerischen Blockmasse Modells zu validieren, das mit professionell vorhandener Software entwickelt wurde. Diese Software enthält im Allgemeinen unterschiedliche Arten der materiellen Modelle. Von den Resultaten der numerischen Simulation wurde das Bestehen von Stärke Anisotrophie beobachtet. Die Stärke Anisotrophie also erreicht ist mit den experimentellen Werten verglichen worden, die von Singh et al. (2002) berichtet werden. Die anisotropen Kurven in beiden Fällen sind mit flacher Unterseite u-förmig. Sie zeigen gute Vereinbarung in gleitender Erscheinungsform des Ausfalls Zone, in der Neigung ß (= 90° - ?) von der Verbindung stellenSie Lüge zwischen 20° auf 40° für alle Fälle vom Ineinandergreifen ein. RESUME: Dans cette simulation numérique de papier du comportement joint de la masse de bloc obtenu en étude expérimentale a été présenté. Singh et autres (2002) ont effectué les essais étendus sur les matériaux modèles joints avec plusieurs configurations communes. Les résultats de cette étude expérimentale ont été employés pour valider le comportement de résistance du modèle numérique de la masse de bloc développé en utilisant le logiciel professionnellement disponible. Ce logiciel contient fondamentalement différents genres de modèles matériels. Des résultats de la simulation numérique on a observé l'existence de l'anisotropie de force. L'anisotropie de force ainsi obtenu a été comparée aux valeurs expérimentales rapportées par Singh et autres (2002). Les courbes anisotropes dans les deux cas sont en U avec la base plate. Elles montrent la bonne concordance dans le mode coulissant de la zone d'échec en lequel la inclination ß (= 90° - ?) du joint placez-Je le mensonge entre 20° à 40° pour tous les cas d'enclencher.

Jan 1, 2003

By J. Lehmann, H. Gaye

A brief review of Computational Thermodynamics software concerning the modeling and prediction of reactions involving metals, slags and fluxes is presented. Their application for various steelmaking treatments is discussed. Examples concern phosphorus removal in BOF and EAF, ladle steel desulfurization, and specific treatments for inclusions control in semi-killed or Al-killed carbon and stainless steels.

In North-West Nelson the Riwaka Complex, a linear basic intrusive complex, is exposed for approximately 45 km. Some 500 km south, across the Alpine Fault, a linear zone of similar but less well known basic intrusives that may be correlatives of the Riwaka Complex is exposed discontinuously for about 80 km. The Complex was emplaced at several centres along a major tensional fracture zone that developed in upper Carboniferous to Lower Permian time. This fracture zone probably formed in response to the development of a west dipping subduction zone that gave rise to the Permian volcanic arcs in east Nelson and western Southland. The Riwaka Complex contains three rock suites. The Fractionation Suite, characterized by cyclic mineral layering and small scale cumulus banding is the largest and is divided into the Ultramafic, Hornblende and Plagioclase Series, each of which is subdivided into several units. The Cumulus Gabbros represent a restricted but important suite of unusual composition, while the third suite is the late phase Diorite Suite. Except in the lower units of the Ultramafic Series sulfide mineralisation is widespread. Pyrrhotite is the dominant sulfide with lesser chalcopyrite pentlandite and pyrite. Four significant zones of sulfide accumulation are recognised and discussed in some detail. Evidence suggests that the primary magma from which the Riwaka Complex was derived was sulfur deficient. It is concluded that the sulfur content of the Riwaka Complex was derived from assimilation of sulfur rich wall rocks during intrusive processes.

Jan 1, 1980

By David L. Bickel

The following instructions and descriptions are presented in two parts to assist an individual to make the borehole deformation gage transducer, and to assemble and test the three-component borehole deformation gage. This Bureau 8 of Mines three-component borehole deformation gage (4, 8, 11)2 fits in a 1-1/2-in-diameter borehole that is drilled in rock and then overcored to determine rock stress.

Jan 1, 1978

By S. Schwartz, T. Bilney

"Over recent years a number of techniques have been developed as part of the AMIRA1 P9 project to represent mathematically or measure directly sub-processes occurring in flotation cells. These include the determination of:•,?a machine parameter (bubble surface area flux, Sb);•,?a froth parameter (froth recovery, Rf );•,?entrainment and drainage parameters (???and d); and•,?an ore floatability parameter (Pi).These flotation parameters allow the plant engineer to develop a model of the flotation circuit that can be used as a powerful tool to diagnose the performance of that circuit. The recently developed JKSimFloat V6 flotation simulator uses these parameters to predict the flotation circuit performance that would arise from changes in operating conditions and circuit configuration.This new flotation technology was applied to the Placer Kanowna Belle Gold Mine in Western Australia. A series of plant surveys, cell characterisation measurements and laboratory batch tests were conducted to determine the flotation circuit model parameters to be used within the JKSimFloat V6 simulatorA thorough flotation circuit analysis was then performed at Kanowna Belle using JKSimFloat V6. The recommendations that were provided by this circuit analysis have resulted in large improvements in the flotation performance at Kanowna Belle. These include a 1.3% increase in flotation gold recovery and a substantial decrease in operating costs. The analysis is still ongoing, however, the benefits already obtained from applying this technology have resulted in a US$1.3 million a year improvement to the mine."

Jan 1, 2005

By Loren R. Anderson

Traditionally, an evaluation of the safety of slopes has been based on computing a safety factor against failure. In computing the safety factor, the geometry of the slope, the soil parameters and the pore pressures are treated as deterministic quantities even though they are known to be random variables. A pseudo-three-dimensional probabilistic slope stability model has been developed that treats shear strength as a random variable. The model uses the probability of a slope failure as an assessment of slope reliability. The model can accommodate zoned embankments of soil in which the strength is described by the Mohr-Coulomb strength envelope. Autocorrelation functions are used to describe the spatial correlation of the strength parameters, c and tan ø. Model error can also be included in the analysis. The model has been applied to an existing tailings dam and to several hypothetical examples. These examples are presented to illustrate the influence of the choice of the soil strength variability parameters on the probability of failure. The results show that the critical failure surface based on the minimum safety factor is not necessarily the failure surface that will yield the maximum probability of failure. The analysis of the tailings dam shows that variance reduction can be large and that the model error is the dominant source of uncertainty for the embankment analyzed.

Jan 1, 1982

By Scott Ellenbecker

Soon New York City will have a new train station. A tunnel project is under construction to extend Line 7 to a new station that is located near the Jacob K. Javits Con-vention Center. This is also part of the Hudson Yards redevelopment project that is intended to aid redevelop-ment of the west side of Midtown Manhattan around the Long Island Railroad?s Caemmerer Railyard. The station, or ?cavern? as it?s called by those excavating it, will be the portal for that growth. In the city, public transportation means high-rise residential proper-ties will have better access to the business district, and those outside the area will have greater access to event facilities ? two factors that are critical for development investment.

Jan 3, 2010

By R. L. Lawson

I?ve been asked to appraise the global role of coal and mining, and the best place I can think of to begin is with the World watch Institute, which purports to monitor all things global. Last fall the institute?s magazine, entitled World Watch, in a cover story called for a worldwide campaign to outlaw the use of coal before this century?s end. To my mind the article began the campaign. However, the institute had to admit that no such ban will be possible unless there is special help and heavy intervention?that is, novel policies and punitive taxes. I?ll quote directly from the magazine to underscore the point: ?without them the market will continue to deceive us into thinking coal is cheap, abundant and irreplaceable?.

Jan 1, 2001