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By Carolina Conter Elgert

O impacto de alguns elementos microligantes no tamanho de grão e nas propriedades mecânicas obtidas em diferentes rotas de processamento foi estudado neste trabalho para uma laminação de barras de aços especiais, special bar quality em inglês, SBQ. Esse estudo compreende as etapas iniciais da metodologia para o desenvolvimento de um modelo capaz de prever o comportamento da microestrutura e as propriedades mecânicas obtidas em processos de laminação de barras, que é pouco difundido para aços microligados. Foram testadas duas variações de aços microligados, com diferentes percentuais de Nb e Ti A rota de processamento mostrou um papel fundamental para a obtenção de melhores propriedades mecânicas nos aços testados – um aprimoramento considerável foi observado quando o material foi laminado seguido uma sequência termo-controlada.

Oct 30, 2017

By James Pile

Long, high capacity, highly tensioned, cable bolts (strand bolts), stiff enough to be installed with resin like a solid bolt, yet flexible enough to be used in any lengths, have been widely used in Australian coal mines since the early 1990?s. A brief history and update on recent developments of this technology is provided. The first major US trial of this Australian technology, has recently taken place at BHP Billiton?s San Juan longwall coal mine in New Mexico. Thirty-five foot long, high capacity, highly tensioned, post-grouted cable bolts are being used to provide active secondary support of intersections in areas where operator safety and life of mine considerations are paramount, and standing support cannot be installed for reasons of equipment access. The cable bolts are resin anchored into overlying sandstone channels, tensioned, and post-grouted. The installation procedure and support results for these highly tensioned cable bolts are given.

Jan 1, 2007

By Gleyson Marcos Barbosa

A forma cilíndrica de bobinas a quente semi-acabadas é essencial para permitir normalidade nas operações posteriores de transporte e utilização. Entretanto tal forma, que é conferida pela bobinadeira, pode ser perdida devido um fenômeno chamado “ovalização”. Com este problema as bobinas assumem uma forma oval, o que pode gerar diversos transtornos, tais como comprometer a inserção da bobina nos mandril do processo seguinte, prejudicar o processo de desbobinamento e colocar em risco a segurança das operações de estocagem nos pátios e transporte. Esta contribuição técnica tem como objetivo mostrar as recentes atividades realizadas por uma equipe multifuncional de 3 diferentes unidades do grupo ArcelorMittal em busca de alternativas para controle da ovalização sem gerar efeitos colaterais indesejados no ciclo produtivo.

Jul 30, 2018

By D. Kwietnewski

With all of the unknowns associated with tunnel construction, how does a contractor choose a roadheader? This paper presents a review of several models of roadheaders being used in today?s tunnel projects. The features of different models of roadheaders are presented and compared. Roadheader size and cutter power generally determine which roadheader is best for a particular job. We will also present a model for matching features of the roadheader to the anticipated ground conditions such that the most efficient machine is selected for the project.

Jan 1, 2011

By Wilford S. Wright, Harold E. Heide, Robert L. Thorne, Neal M. Muir, Aner W. Erickson, Bruce I. Thomas

A program of investigation of strategic and critical minerals began in 1940 to examine and develop tungsten occurrences in the western United States and Alaska. During the years in which the nation was at war, this work was given special impetus to stimulate domestic production. This report is a compilation of results of the tungsten investigations in Alaska supplemented by certain data made available by the Territorial Department of Mines and is designed to include in its scope descriptions of all known tungsten occurrences in the Territory. Two areas in Alaska warranted special investigation - one at Gilmore Dome, 16 miles northeast of Fairbanks, and the other in the Hyder District, at the head of Portland Canal. Three tungsten properties - the Stepovich, Colbert, and Yellow Pup - are at Gilmore Dome. The Stepovich property, referred to sometimes as the Cleary Hill tungsten deposit, was worked by the Cleary Hill Mines Co. from April 1942 until May 1944 and was first examined by Robert S. Sanford and Norman Ebbley, Jr., engineers of the Bureau of Mines, in September 1942. The Cleary Hill Mines Co. by that time had explored an 800-foot strike length of the ore zone with 10 bulldozer trenches and was sinking an inclined shaft on ore in the central portion of the explored zone. In January 1943, the senior author, in company with Ebbley and Harry C. Doheny, supervising engineer of R.F.C., examined the property. Preliminary work by the Bureau of Mines began in May 1945, but actual exploration did not commence until late in June and continued until the end of October 1943. The deposit was examined by John B. Mortie, Jr., and William C. Overstreet, of the Federal Geological Survey, in 1942, and this study was continued in 1943 by Frank Byors, who also assisted the Bureau’s engineers on geologic problems. A magnetometer survey of this area was undertaken in 1942 by Henry Joosting and Eskil Anderson, engineers of the Territorial Department of Mines, and was completed with Bureau of Mines assistance in 1943. During 1943 the Bureau completed exploratory projects on the Cleary Hill mine and adjacent Colbert prospect. The field work on the Colbert property was begun early in July 1945 and continued intermittently until the end of October 1943, when it was recessed because of subzero weather. During September 1944, the Bureau of Mines established (by means of a few surface trenches) continuity between the Colbert mineralized zone, high on the dome, and the Yellow Pup vein, the lowest known tungsten mineralization in the area. It is generally recognized that any extensive program to develop the area as a whole logically would be carried out from the lower horizon.

Jun 1, 1948

By Stewart A. Silling, C. Mick Lownds, Dale S. Preece, Ali Bhuiyan

GEM (Geologic Element Motion) is a Distinct Element Method (DEM) for modeling blast-induced heave. It was developed with a very fast computational algorithm that efficiently treats many different element shapes utilizing alternating arcs and lines to create GEM elements. The GEM computational technique has been previously documented so only a summary will be included in this paper. New features of GEM are the ability to define the size of the rounded corner radius as well the length of the sides for quadrilateral and hexahedral elements. Circles can be created from a quadrilateral element with zero length sides and four arcs. An additional new GEM feature is energy partitioning between brisance and heave. This physics-based partitioning is essential for accurate modeling of blast results over a wide range of rock and explosive types. It accurately defines the volumetric, pressure and energy state of the explosive gases in a blasthole following detonation. Rock mechanical properties and explosive characteristics are included in the calculations. Example simulations provide comparison of the GEM predicted heave for two different classes of explosive. A GEM simulation utilizing hexahedral elements is compared with previous modeling incorporating circular elements.

Feb 6, 2023

By Nobuo Takahashi

Effective solvent extraction media have been investigated for purification of rare earths. At first, a quaternary ammonium compound was studied. The counter anions of rare earths and organic dielectric substances were tested to improve separation factors,. And second, crown ethers were selected for extractant. Several diluents of crown-adducts were tested to improve solubility and distribution coefficient as well as the counter anions of rare earths. Especially, in the presence of strong reducing agents, highly selective extraction of europium from other rare earths was observed. The third extactnts were ß -diketones. Presence of organic dielectric substances was very effective to improve separation factors. Though those. three groups of extractants were suitable for mutual separation of light rare earths, alkyl esters of alkyl-phosphonic acids were suitable for mutual separation of heavy rare earths because of their high separation factors. To keep proper pH value was necessary for acidic extractants, so control method of the solution pH was studied with high molecule insoluble amines or salts of those.

Jan 1, 1995

By Tom Short

"Construction blasting covers a very extensive variety of explosive applications. I will discussseveral of these with you and then show slides from my collection, starting in 1956, which will betterillustrate the types of blasting under discussion."

Jan 1, 1991

By D. D. Downing

This paper is a review of material selection considerations concerning protective coatings in the mining industry. The discussion will cover both capital-dollar projects and maintenance requirements. Emphasis will be on industrial finishes for structural steel and process equipment subjected to aggressive atmospheres. The presentation will cover the total needs of a job, emphasizing not only the owner's requirement for a cost-effective system during plant operations, but also taking into consideration the short-term requirements of general contractors, steel fabricators, erection firms and paint contractors.

Jan 1, 1979

By Tibor Zoltai

Asbestos is a generic term for industrially useful fibers recovered from exploitable deposits of the asbestiform varieties of five silicate minerals: chrysotile, anthophyllite, actinolite-tremolite, cummingtonite-grunerite, and riebeckite. Asbestos and asbestiformm fibers of some other minerals are known to be carcinogenic. Minerals crystallized in the asbestiform habit are characterized by unique properties (morphology, strength and flexibility, physical and chemical durability, and defect-free surface structures). The key to the unusual properties, and health effects, of asbestifarm fibers appears to be in their unusual surface structure. In contrast, non-asbestiform crystals of the same minerals, including the five so-called asbestos minerals do not have these properties and are not carcinogenic (1, 2).

Jan 1, 1989

By T. Urbancic, Eric von Lunen, G. Viegas, A. Baig

"The characterization of the failure process of induced fractures by hydraulic stimulation is fundamental to understanding the generation and evolution of the discrete fracture network within the reservoir. A more detailed analysis of the fracture mechanism can be a powerful tool for identifying fluid flow paths and proppant placement within the reservoir. For example, during the rupture process the energy release is partitioned into different physical processes for which the relative ratio is changed by the presence of fluids or rotations in the local stress field with relation to the frictional resistance in the fracture plane. Fractures occurring in the same host rock under the same stress conditions are expected to rupture similarly, independent of their size (self-similarity). Changes in the scaling relationships of fractures are indicative of a change in the failure process, host rock or in-situ stress. Correlation of failure process data with reservoir rock properties and the in-situ stress field will help identify regions within the reservoir with characteristic types of failures. Further correlation with hydrocarbon production data can be used to develop efficient treatment plans and production diagnostic tools.In this study we investigate the failure process of ~27,000 microseismic (M < -1) fractures induced during a hydraulic fracturing shale completion program in NE British Columbia, Canada by estimating static and dynamic source parameters, such as dynamic and static stress drop, radiated energy, seismic efficiency, moment tensor, fracture plane orientation, slip direction and rupture velocity. On average, the microseismic events have low radiated energy, low dynamic stress and low seismic efficiency, consistent with the obtained slow rupture velocities. Events fail in overshoot mode (slip weakening failure model), with fluids lubricating faults and decreasing friction resistance. Events occurring in deeper formations tend to have faster rupture velocities and are more efficient in radiating energy. Variations in rupture velocity tend to correlate with variation in depth, fault azimuth and elapsed time, reflecting a dominance of the local stress field over other factors.Further identification of spatial and temporal distribution of families of events with similar characteristic rupture behaviors, based on either rock formation, depth, source type, fracture plane orientation, stress drop, pad or proppant stage, may be used as a proxy for specific fracture network development and hydrocarbon production. This information may be used to determine reservoir properties, constrain reservoir geo-mechanical models with measured physical parameters, classify dynamic rupture processes for fracture models and improve fracture treatment designs. These will be the focus of future studies."

Jan 1, 2015

By Stephan A. Jefferis, Adrian H. Bath

"This paper draws together some themes on the durability of barrier systems, and particularly cementitious systems. For contaminated land and water retaining structures, durability can be poorly addressed at all stages of a project, from specification, to barrier material selection, barrier design including toe-in and through to performance assessment in operation. Permeability (hydraulic conductivity) is a dynamic property which will vary over time as reaction processes propagate through a barrier. However, laboratory testing, when undertaken, tends to be focused on short term tests with aggressive chemicals so that the effects of longer-term processes such as carbonation and leaching by permeating water are missed. For water retaining structures, carbonation and leaching actually may be the most significant processes affecting barrier performance as the groundwater adjacent to many water bodies can be otherwise rather benign (as regards bentonite and cementitious systems). These and other reaction processes have been modelled in the arena of nuclear waste repositories and procedures are well recognised. However, such procedures have yet to be widely adopted for the assessment of other barrier systems.INTRODUCTIONOver the last few decades there has been an enormous amount of laboratory research on the durability of barrier materials or more specifically papers reporting the results of permeability tests. Unfortunately there is a much smaller literature on scaling test results to barrier dimensions in the field or to required design lives. Although in the geotechnical industry durability research has been largely laboratory based, in the nuclear industry where relevant timescales are multi-millennia rather than decades, research has been heavily underpinned by geochemical modelling. A significant purpose of this paper is to examine the tools that may be used to analyse the results of tests on barrier materials used in geotechnical engineering, for example, for water retaining structures and contaminated land and draw the attention of the construction industry to the potential of the modelling procedures developed for nuclear repository assessments. Modelling can help to identify underlying processes and so augment information from laboratory testing focused on changes of physical properties such as permeability and strength."

Jan 1, 2016

By Nasri Munfah, Steffen Matthei, Vojtech Gall

"Conventional tunneling as defined by ITA WG19 is also known as the New Austrian Tunneling Method (NATM) or Sequential Excavation Method (SEM) was transformed in the US to deal with challenging tunneling conditions as an alternative to the more traditional tunneling methods. It is being used more often in urban areas, under difficult ground and ground water conditions, and with limited cover. Often the tunnel is of a large and non-uniform cross section in soft soils or weak rocks. The intent of using this tunneling method is to minimize impact on traffic and utilities and reduce disruption of everyday life of people and businesses. To meet these challenges, the industry developed technical approaches and implementation techniques and established sophisticated contractual relationships and collaboration in the field among various parties for successful implementation. This paper examines the development of conventional tunneling (NATM/SEM) in the US to deal with these challenges using recent examples such as Russia Wharf in Boston, Northern Boulevard Crossing, in New York, and Chinatown Station in San Francisco. INTRODUCTION / HISTORY Conventional tunneling or NATM/SEM is a concept that is based on the understanding of the behavior of the ground as it reacts to the creation of an underground opening. In its classic form the SEM/NATM attempts to mobilize the self-supporting capability of the ground to an optimum thus achieving economy in ground support. Initially formulated for application in rock tunneling in the early 1960’s, NATM has found application in soft ground in urban tunneling in the late 60’s and has since then enjoyed a broad, international utilization in both rural and urban settings. In the US the NATM/SEM tunneling method has been used successfully to address challenging tunneling conditions in urban areas. A large number of tunnels have been built around the world using a construction approach which was loosely termed NATM. During the years of discussions and the application of NATM a variety of terms have been used for the same construction approach. These terms were primarily aimed at describing the construction approach rather than the region of its reported origin."

Jan 1, 2016

By Carlos Filippe de Sousa Morais

O software desenvolvido tem como objetivo, mapear o real tempo de operação do RH da Companhia Siderúrgica Nacional - CSN, identificando os atrasos antes e durante o tratamento de um aço no equipamento. Para isso foi criada uma tela automática que é aberta ao operador toda vez que é identificado atrasos, seja durante a troca de panela (Disponibilidade) ou durante o tratamento do aço (Processo). É possível visualizar em qualquer período desejado o preenchimento dos atrasos através de um relatório e uma interface gráfica interativa gerada pelo software, e com isso tomar medidas capazes de melhorar a produtividade no RH. Os resultados abordados ao longo deste trabalho mostram que a solução de uma pequena parte destes atrasos pode gerar ganhos de produção significativos para a Companhia Siderúrgica Nacional.

Aug 16, 2017

By K. Saberyan

A technique is described for the solvent extraction of zirconium. In this method, zirconium has been extracted quantitatively from 0.005 M sodium salicylate solution at pH 2.5 - 3 using 0.01 M triphenylphosphine oxide dissolved in toluene as an extractant. Zirconium has also been recovered quantitatively from 0.2 M potassium thiocyanate solution, but extractions in nitric and hydrochloric acids (as media) were negligible. The resulting extracted metal ion has been stripped with sulfuric acid (0.5 M) and determined with inductively coupled plasma atomic emission spectrometry. This method has been applied successfully to achieve 95% recovery of zirconium from zircon concentrate.

Jan 1, 2010

By Wilhelm Borchers

IN all special branches of the chemical and metallurgical industries, in which large electric furnaces became necessary for carrying out new processes or for the improvement of old ones, the development of the electric furnaces took place on much the same lines. The endeavors to make a success of a new idea brought forth many ingenious designs, which, however, almost without exception, furnished the proof that the safest and shortest way to practical success is the utmost simplicity of construction of the necessary apparatus. Our knowledge of the qualities of materials for building electric furnaces and of the constituents of the furnace-charges, especially their electric conductivity and their chemical affinity . towards one another at high temperatures, is still far from being complete, and from this fact we must conclude that the smaller the number of elements in the construction of a furnace, the fewer the number of unreliable factors both in the construction and in the operation of the electric furnace. This conclusion deserves special attention when an electric furnace for making steel has to be chosen from the constantly growing number of inventions, inasmuch as the chief con¬stituent of steel, the element iron, is a substance which in its liquid phase has so great an affinity fir those elements which are to be removed from the charge, that it is very difficult to comply with the following conditions: 1, to beat the refining-slag to the highest point of its chemical activity ; to prevent the iron from entering the slaw, or, where this cannot be done, to make it enter so that it finally appears in the end-product

Jan 1, 1910

By Patrick J. Doig

The contract for the construction of the Inline Pump Station for the Milwaukee Metropolitan Sewerage District involves the sinking of three shafts and the excavation of a pump chamber. The shafts are being sunk to a depth of 104 meters and pass through 52m of sediments before encountering dolomitic bedrock. The pump chamber is constructed in dolomite. The sediments are alluvial, estuarine and lacustrine in origin, with some ice margin deposits. They comprise loosely consolidated fine to coarse grained sand, silts, clays and gravels, and they are heavily saturated with a water content often above 60%. The water table is at a depth of 3m. The dolomite is silurian, generally dense, with some clay-filled vugs and shale partings. Until 1983, underground construction in the Milwaukee area had been limited to depths of 26m in the sediments and 20m in the dolomites. Water control methods had included caissons, compressed air, extensive internal and external dewatering, and grouting. Flows of 20 liters per second were commonplace with as much as 80 liters per second being encountered in the rock. However, in 1984 work was commenced on the deep sections of the Milwaukee sewerage scheme with the letting of three major contracts including the Inline Pump Station. With excavation taking place at greater depths, it become obvious that previous methods of water control would be inappropriate. To protect against major inrushes of high pressure water in the rock, an extensive program of pre-grouting from the surface was specified. Water control in the sediments was left to the discretion of the contractor and in each case freezing was choosen. This paper describes in detail the grouting and freezing procedures.

Jan 1, 1985

By D. F. Strong, P. P. O'Neill

"The Isle aux Morts Prospect is the first polymetallic, sulphide mineralization reported from the Port aux Basques Complex of southwest Newfoundland. Zn-Pb-Cu-Ba-Ag mineralization hosted by quartz-muscovite semipelite, occurs at the contact between a quartz of eldspathic unit and pelitic unit with intercalated amphibolite are minerals comprise sphalerite-galenachalcopyrite, in order of decreasing abundance. The principal gangue minerals are quartz, muscovite, feldspar and barite. Three morphologic types of mineralization are present: massive with more than 50% sulphide, flanked on one or both sides by disseminated and/or banded types. The massive type of mineralization exhibits a :durchbewegung"" fabric of rounded silicate fragments in a sulphide matrix, characteristic of intensely deformed and metamorphosed sulphide bodies. Sulphide minerals have been mobilized and recrystallized and share the same metamorphic and deformational history as the host rocks. Quartz muscovite schist which hosts disseminated mineralization, displays a K2O enrichment and Na2O depletion, that is typical of alteration associated with sulphide bodies in volcano sedimentary sequences. Isotopic ratios of sulphur are comparable to those of volcanogenic massive sulphide deposits.Despite penetrative deformation and metamorphic recrystallization, features of the local geology and the mineralization suggest that the Isle aux Morts Prospect is volcanogenic in origin. IntroductionFollowing the release of a government lake sediment survey (Butler and Davenport, 1980), which indicated anomalous concentrations of metals in southwest Newfoundland, geologists with Utah Mines Ltd. discovered the Isle aux Morts Prospect, a Zn-Pb-Cu-Ba-Ag showing, located approximately 15 km northeast of Port aux Basques (Figs. I and 2). The mineralization occurs in quartz-muscovite schist and is the first significant basemetal discovery in the Port aux Basques Complex."

Jan 1, 1988

By Alan de Sousa

O presente trabalho tem por objetivo revisar o atual plano de lubrificação de um laminador a frio modelo Sendzimir, tendo como foco principal determinar por meios analíticos, a confiabilidade dos processos de relubrificação à graxa de mancais de rolamento. Para a determinação dos parâmetros de relubrificação do restante dos conjuntos, que não são mancais de rolamento, foi realizada a consulta dos catálogos dos fabricantes para a determinação dos intervalos e quantidades, conforme recomendação destes. Para a realização deste trabalho, foi necessária uma extensa revisão bibliográfica, de normas e literaturas referentes a este tema. No final deste, objetiva-se a obtenção de um aumento da confiabilidade dos equipamentos, além de uma redução de custo com mão de obra e lubrificante durante os períodos de relubrificação.

Oct 30, 2017

By E. W. Raabe

The paper discusses the increasing role of specialist grouting techniques to form water seals or cut-offs for deep basement construction. Raabe and Toth discuss the various grouting methods available for sealing applications and then concentrate on the use of Soilcrete Jet Grouting, a system particularly well suited to ground water control. The Soilcrete processes, suitable soil types and quality control methods are fully described, particularly with regard to the formation of cut-off walls and sealing slabs to prevent the progress of ground water or leachates. The authors have included case histories detailing their experience on designing and installing Soilcrete seals for various projects in West Germany. These include an underground rail project in Dortmund and a discharge structure for the Alz Canal at Burghausen.

Jan 1, 1989