Search Documents

By Amir Karami, Scott Munro

This paper focuses on remediation of a 3.6 km long water conveyance tunnel that suffered two large falls of ground (FoGs), one of which subsequently progressed to the ground surface, resulting in full collapse of the tunnel. The tunnel is part of a network of water conveyance tunnels and open channels that direct water into two turbines located in an underground powerhouse, originally constructed in the 1970s. At the time of construction, the tunnel was partially supported with shotcrete or rock bolts, with no further ground support added since construction. Two sonar surveys in 019 and 01 identied two adacent large FoGs in the tunnel, approimately 1.2 km from the tunnel outlet. Historical geological and geotechnical information indicated that the FoGs occurred within a 60 m wide fault zone. Remediation plans were developed, which included stabilization of the outlet channel, the portal, the tunnel leading up to the FoG areas (1.2 km length) and the FoG areas. Several remediation options were considered to restore the tunnel, including construction of a diversion tunnel to bypass the FoGs or remediation of the FoG areas with steel ribs and backlling the void above the FoGs to surface.

Jun 23, 2024

By Iann Bouchard

Introduction à l?abrasion et l?érosion Avec le temps, tout solide va éroder et user les métaux les plus durs; de plus, la Corrosion va aussi laisser une couche mince et faible d?oxydation qui sera rayée du substrat. Solutions et guide de sélection Les polymères de Henkel Loctite® peuvent: ? Réduire l?abrasion par glissement ? Protège contre les agents corrosifs ? Prévenir la cavitation ? Augmenter l?efficacité ? Réduire la turbulence ? Résister aux hautes températures?

Feb 1, 2008

By PEILIN LAN, LEONARD HILL, SIMON TIMBILLAH, BERNARD FOSU, CESAR SOSA-BLANCO

The use of sodium hydrosulfide (NaHS) in most of the operations in by-product molybdenum flotation comes with safety concerns and, in some instances, a high reagent cost. Engineered solutions at the various operations where NaHS is used have reduced the possibility ofH2S gas evolution immensely. However, the threat of exposure remains, and this, coupled with the high dosages of NaHS consumed, supports the continued search for alternative depressants. This paper focuses on efforts to study the applicability of disodium carboxymethyl trithiocarbonate (DCMT), an organic depressant, as an alternative to NaHS. Benchscale rougher flotation results for samples from the Sierrita Cu–Mo plant showed the best DCMTperformance at 8 kg/t of DCMT and pH=10.5 with 30 min of shear conditioning and 10 min of flotation conditioning time. The Aminpro plant model simulation confirmed that DCMT with 4–8 kg/t under certain shearing and conditioning times achieved superior or equivalent Mo–Cu separation efficiencies when compared to NaHS.

Apr 19, 2021

By Charles Will Wright

The application of the camera as an adjunct to topographic mapping began practically with its invention, and it has been employed with varying success since that time. With the exception of the camera to be described, the plate-camera has been universally used in this work, thus giving a projection of the area photographed on a flat surface. From such projections or photographs, by the rules of geometry and of perspective, points defining topographic features and seen from at least two camera-stations may be projected upon a ground-plane—the map.' In 1904 I employed the plate-camera for this purpose in Alaska, but found that the labor necessary to plot the maps, even in a general way, was long and tedious. In 1905 a small Eastman panoramic camera was fitted with spirit-levels, a sight-alidade and a transparent scale, introduced inside the camera to register the degree-points in the sky-line of the film-negative ; also, arrows to indicate the horizon-line. This was, on the whole, successful; but the details in the topography were not brought out in the views with sufficient clearness, aid the photographs were too small. These difficulties were overcome by obtaining a larger and more carefully constructed instrument, which was satisfactorily employed in the field during the year 1906. A panoramic view is made up of an integral number of perspective views upon flat surfaces, and logically is the most accurate and direct means to obtain an impression of a field of * Published by permission of the Director of the U. S. Geological Survey. Stanley, H. M. Photographic and Co-ordinate Surveying, Bans., xx., 740 to 766 (1891). Also, Flemer, J. ,4. Phototopographic Methods and Instruments, Report U. 8. Coast and Geodetic Survey, pt. 2, app. 10, pp. 619 to 735 (1897).

Jan 1, 1908

By Marcos Valdéz Córdova

El presente estudio señala el proceso de mineralización en el domo de Yauli a través de una revisión en el comportamiento de dominios estratigráficos, estructurales, intrusivos, metamórficos y distintos minerales de alteración hidrotermal. Asimismo se describe la geología, su estructura, la alteración de los intrusivos, la alteración de los silicatos metamórficos, la alteración de los mármoles y calizas dolimíticas, cuerpos, mantos y las vetas de reemplazamiento.

Nov 20, 1978

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 R. G. Knickerbocker, C. T. Baroch, A. W. HACKWOOD

The difficulties inherent in the production of alumina by the formation of potassium alum and its subsequent thermal dehydration and decomposition have been overcome , to a large extent , in a process developed at the Boulder City Station of the Bureau of Mines . This process is applicable to the reserves of alunite known to occur in several Western States and , possibly , to certain clay and low-grade bauxite deposits known to exist in this country . The operations sequence of the process is shown in the flow sheet (fig . 1) . Only those steps included within the heavy line are considered in this report . Four different procedures for dehydration of alum were investigated ; ( 1 ) Spray drying , ( 2 ) rotary - kiln drying , ( 3 ) dry grinding in a thermal ball mill , and ( 4 ) dehydration in the vertical- column flash dehydrator . Based upon fuel requirements and other practical considerations , the vertical- column dehydrator , or some modification of its operating principle , offers the botter possibility for commercial use .

Feb 1, 1946

By R. Dippenaar

Traditionally, iron ore has been reduced with coke in a blast furnace and the hot-metal product of the blast furnace containing carbon, manganese, silicon, sulphur and phosphorous, was subsequently refined in a steelmaking furnace. During iron making as well as during steelmaking, significant amounts of slag are produced. Two decades ago, more than 13 m tonne of blast furnace slag and 4 m tonne of steelmaking slag per annum were produced in the USA alone. It is, therefore, not surprising that many attempts have been made to re-use iron and steelmaking slags. However, these slags are not merely metallurgical waste products but, on the contrary, their compositions and physical properties are judiciously designed to optimize the operations in the respective metallurgical reactors. The variation in composition and properties of blast furnaces lags are largely determined by the gangue in the ore and ash in the coke and much progress has been made in the re-use of such slag. With respect to steelmaking slag, emphasis has in recent years been placed on hot-metal treatment before refining and ladle treatment after decarburization. The bulk removal of silicon, phosphorous and sulphur from the hot-metal product of the blast furnace by specially designed slags prior to refining in a basic oxygen furnace, has reduced tap-to-tap time, lowered cost and produced steel of much higher quality. The use of synthetic slags in ladle refining techniques subsequent to decarburization in the basic oxygen furnace has resulted in reduced hydrogen and nitrogen contents and reduced solute impurities. Moreover, inclusion shape and composition control, again by the use of specially designed slags has led to the achievement of much improved mechanical properties of the steel. In these revised process routes, slag of different compositions are produced in the variety of unit processes and hence the re-use of steelmaking slags has become much more complex. Clearly, a thorough understanding of the design and use of these different slags is a pre-requisite to the development of re-use strategies. Japanese steelmakers have spearheaded attempts to reduce slag volumes in the individual unit processes and to strive towards ‘slagless steelmaking’ by recycling slags internally. Steelmaking slag volumes have been reduced on commercial scale from about 140 kg/tonne steel to 60kg/tonne steel. Moreover, model predictions have shown that, in principle, all slag can be recycled and the phosphorous extracted to produce fertilizer. This development is of particular significance since the supply of low-phosphorous iron ores is diminishing at an ever increasing rate. Keywords: slag, environment, iron, steel,

Jan 1, 2004

By Alan B. Wagner

The River Tower is a proposed 27-story condominium building in the heart of downtown Milwaukee, Wisconsin (USA). The tower will be over 100 m tall, and will have a ground area measuring 15 m by 40 m. The structure will be constructed of cast-in-place reinforced concrete. Certain transfer girders and stabilizing diagonals will be constructed of post-tensioned concrete. Vertical loads will be transmitted through an arrangement of columns, bearing walls, and elevator and stair cores. A mat foundation will be used to connect and integrate these load-carrying elements. The site's geologic profile includes 8.4 m of compressible estuarine (organic) deposits. To control settlement, the mat will be pile-supported. These deposits are underlain by moderate-strength inorganic deposits that extend to bedrock at 32 m.

Jan 1, 2002

By Bráulio Salumão de Oliveira

A participação do petróleo e gás natural na matriz energética mundial aumenta gradativamente a cada ano. Em estimativas para as próximas duas décadas, tais fontes continuarão a figurar entre as principais na participação em suprir a demanda por energia mundial. Para que seja tecnicamente e economicamente viável a exploração destes recursos, são necessários utilizar produtos e processos inovadores que, por sua vez, exigem evolução da pesquisa e desenvolvimento de novos materiais e processos. Este estudo objetivou analisar o desenvolvimento tecnológico de ligas ferrosas para os produtos tubulares utilizados nesse mercado, através da elaboração de indicadores a partir de documentos de patentes indexados na base Derwent Innovations Index entre 1995 e 2014. Foram elaborados indicadores de evolução temporal, de identificação dos elementos de liga, das tecnologias em processamento dos produtos e das propriedades requeridas além de comparativos entre principais desenvolvedores e seus mercados de interesse. O número de documentos de patentes sobre o tema aumentou significativamente durante o período estudado. Foram notados países com destaque no número de depósitos de patentes, porém com pouca expressão de pedidos fora de seu território. Os principais titulares são empresas japonesas embora a China tenha apresentado a maior tendência de crescimento de depósitos no tema.

Aug 16, 2017

By Rodrigo Sales

Os principais objetivos de um projeto de Integração e Otimização de Processos (PIO – Process Integration and Optimisation) é de auxiliar no desenvolvimento de uma estratégia integrada de desmonte e cominuição que minimize o custo total por tonelada processada nas etapas de lavra e cominuição das operações, minimize o consumo de energia e maximize a taxa de processamento, produção de metais e lucro da empresa. O projeto consiste na revisão de práticas operacionais, auditoria e amostragem, benchmarking, modelagem e simulações das operações de perfuração e desmonte e cominuição. Isto permite uma análise holística das operações para identificar oportunidades de melhorias e desenvolver estratégias integradas e otimizadas de operação da mina-à-planta. O projeto incluiu o sistema exclusivo da Metso, SmartTag™, para rastrear o minério dos furos de desmonte na mina até a planta concentradora com o objetivo de correlacionar os tipos de minério e de desmonte com os resultados de desempenho da planta. O sistema de modelamento geometalúrgico automatizado chamado GeoMetso™ utiliza a tecnologia de rastreamento de minério SmartTag™ para coletar continuamente dados de desempenho da planta e atualizar automaticamente os modelos preditivos e o modelo de blocos em tempo real. Este sistema é a base para a implementação, validação e melhoria contínua das estratégias integradas e otimizadas de operação, além de auxiliar na reconciliação da mina-à-planta e planejamento de lavra.

Aug 17, 2017

Peculiarities of Quartz Distribution in Zinc Flotation Products and their Influence to Mineral Processing

Sep 13, 2010

By Mike Amick

As virgin coal reserves dwindle, more and more mines are being opened in areas with previous mining. As addressed in this conference before, there are solutions available for designing mines extracting coal from reserves with known underground workings above or below the target seam. Often times, however, mining begins with limited knowledge of the underground workings. Even with careful planning, the proposed design has limited success because the ?facts? as presented during planning turn out not to be as accurate as one would like. At National Coal?s Mine #14, mining the Walnut Mountain seam, after driving the main entries in some 34 crosscuts, it was found during routine mine examinations that the pillars had separated from the roof in a few areas of the mains. Immediate roof conditions proved to be sound but questions arose concerning the stability of the main roof and floor. Core tests were done to better determine the rock strengths and characteristics. The paper presents the ideology used to tackle the effects of mining over old works in an operating coal mine. This paper discusses the analysis of the symptoms observed and the steps taken to ensure that this pillar separation was caused by the underlying old workings and that the separation was expected and controllable.

Jan 1, 2009

By Pamela J. Watson

A novel technique has been employed by the U.S. Bureau of Mines to determine the zeta potential of particles for a far-reaching series of material types in a wide variety of baseline waters, both alone and with many different chemical additives. The materials tested ranged from naturally occurring Sioux Quartzite and Tennessee marble to commercially produced magnesium oxide bricks. The waters tested ranged from ultrapure distilled, deionized water to municipal tap water and mine-site water. The chemical solutions tested included inorganic additives, such as aluminum chloride (AICI3) and sodium chloride (NaCl); organic additives, such as dodecyltrimethyl ammonium bromide (DTAB); and nonionic polymers, such as polyethylene oxide (PEO). The results of precise zeta potential determinations have application in a large number of laboratory studies as well as in various mining and processing operations.

Jan 1, 1989

By A. L. Murray, C. A. Allen

"The Industrial Commission of Utah from a study of the accidents (especially the fatalities) occurring in connection with mining in the State was struck by the large number arising from lack of due care on the part of the employee injured or carelessness on the part of some fellow employee. Figures show that approximately 40% of the deaths are due to carelessness as against only ) 10% or 12% that can be laid to faulty conditions in the mines. With a view to reducing the number of these accidents an intensive campaign of education was inaugurated, conducted jointly by the Industrial Commission of Utah and the United States Bureau of Mines.Through the cooperation of the U. S. Bureau of Mines, Mine Rescue Car No. 11 operating in Utah has been utilized as the means of carrying on the campaign. In making the regular training visits to the mining camps of Utah the crew of car 11 was authorized to include with the courses of instruction in Mine Rescue and First Aid, safety and health rallies, foremen's safety meetings, and appeals carried on through the public schools to stimulate an awaking of personal responsibility of miners and their familiar' in safety and health endeavor. The work was placed under the direct charge of Dr. Murray who has had previous experience in similar work and brought to the campaign helpful enthusiasm. He was assisted by Bruce Johnson, fore¬man miner of Car 11, who had been safety engineer for the U. S. Smelting Company, and R. W. Clark, first aid miner of Car 11. The expense of providing posters, literature, pledge cars, buttons, rental of special educational films and incidental expenses of foremens' meetings has been born by the Industrial Commission.Plan of the Campaign.In planning the campaign the main object was to revive as much as possible, among the workers, a spirit of responsibility for safety. Any considerable reduction of preventable accidents can be accomplished only through the workers themselves who are responsible for such accidents, therefore, the more personal the application could be made to all the workers the greater the accruing results would be."

May 1, 1921

By M. A. Elliott, F. W. Brown

"INTRODUCTION During the recent war the Bureau of Mines, at the request of one of the armed services, investigated the hazards that night be encountered 5n handling perchloric acid, particularly if spilled on certain materials. The hazardous nature of perchloric acid when mixed with reducing agents had been known qualitatively, but it was desired to obtain quantitative data on the explosion hazards of such materials. Accordingly, tests were made to determine the sensitivity of mixtures of perchloric acid and oxidizable materials to initiation by heat, impact, sparks, flame, and explosive impulses. This report summarizes the results of those tests.PROPERTIES OF PERCELORIC ACIDAnhydrous perchloric acid is a colorless,hygroscopic, volatile, mobile liquid that fumes in the air. The anhydrous acid is unstable at ordinary temperatures, and therefore the commercial acid is a water solution containing either 60 percent or 70 percent by weight of the anhydrous acid. The commercial acid is widely used in chemical analysis, frequently to oxidize organic material. If proper precautions are not observed, such an oxidixation may become exceedingly rapid and result in an explosion. Several such explosions involving the acid are mentioned in the literature. 4, 5, 6/"

Jan 1, 1948

By Charles R. Keyes

I. INTRODUCTORY. IN the dry regions of the globe many silver-deposits display certain remarkable features which at the same time are so totally unlike anything met with among ore-bodies elsewhere, that they have long presented exceptional difficulties not only to a satisfactory explanation of their origin, but to economical milling. A most striking peculiarity of these ores is the haloid character of many of their bonanzas. To this fact more than to any other may be ascribed most of the unusual uncertainties of mining-operations in desert countries-the marvelous local richness of the ores under certain conditions and the often abrupt transition, to utter poverty; the inadequacy of ordinary prospecting customs and the constant devising of new exploratory methods; the unaccountable losses in smelting and the continual change in treatment-practice. For these anomalies certain climatic conditions seem to be chiefly responsible.

Jul 1, 1911

By N. B. Pundari

Proper selection of large walking draglines, based on sound engineering principles and field experience, has not kept pace with the large capital expenditures needed to buy these stripping machines. The use of large walking draglines for stripping overburden in US surface coal mines grows steadily, but equipment selection continues to pose problems. An improper size, model, make, or spoil reach selected for a particular stripping application results in additional, unnecessary coal production costs. Large walking draglines are being used to dig deeper tar sands at the Syncrude operations near Fort McMurray in Northern Alberta, Canada. This application is compared with typical deep digging operations and dragline use prevalent at typical US strip mines.

Jan 4, 1981

By Clark D. Harrison

This paper compares the ash slagging potential of Illinois No. 6 Seam coal: as raw coal; as commercially cleaned coal processed in a baum-jig plant; and as coal cleaned to a reduced ash specification at the Electric Power Research Institute's Coal Cleaning Test Facility. The comparison is based on: ? ASTM ash fusibility data ? A slagging index ? Gravity fractionation analyses of critical mineral matter compounds ? Comparative pilot combustion tests. The first three grounds of comparison are laboratory data; and the final comparison involves burning approximately 15 tons of each coal at CONOCO's 1.5 MBtu/hr (440 KW) test combustor. The evidence of these .four comparisons indicates that lowering the ash specification of coal before combustion can significantly improve the ash slagging characteristics of Illinois 90. 6 Seam coal.

Jan 1, 1984

Geophysical methods are useful non-invasive means of collecting subsurface information on the environmental impacts of resource developments. Techniques such as seismic refraction, ground probing radar and magnetics are well established tools for environmental studies of waste disposal sites. Repeat resistivity surveys, gravity surveys, and infrared or multispectral remote sensing hold great promise for monitoring environmental changes. Examples from New Zealand include geothermal field monitoring, which may involve the use of geophysics for .detecting changes of surface thermal activity, hydrothermal eruptions, induced earthquakes, contamination or depletion of shallow groundwater, and subsurface fluid recharge. Other examples include resistivity monitoring of contained effluent disposal ponds, tailings dams and landfills. Experience has shown that care is necessary to identify the natural variability of the parameter measured before drawing conclusions regarding an observed change.

Jan 1, 1994