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By Dean, R. S.

THE numerous theories of hardening which have been advanced in recent years are all satisfactory in accounting for some of the phenomena observed in hardening metals, but none so far presented account for all of the facts observed. Some years ago one of the authors, R. S. Dean,' presented a theory to account for some of the properties accompanying work hardening. The present paper develops this theory further in the light of recent experimental work and extends it to other forms of hardening. Many of the ideas included have come from the writings and personally communicated thoughts of others. We have attempted to give proper credit in every case, but it is possible that we have not always done so. As an historical basis it is desirable here to review very briefly the hardening theories which have been current. The first comprehensive theory of work-hardening phenomena was due to Sir George Beilby.2 He contributed the idea that with cold work part of the structure of the metal was rendered amorphous and that-it was to this amorphous material that the cold-worked metal owed its difference in properties. According to Beilby's theory this amorphous material was a supercooled liquid and, therefore, had the characteristics of a vitreous material. That such a theory is not capable of explaining the property changes in metals has been repeatedly pointed out. This theory also allowed a slip to take place only once on a given plane, which, as has been pointed out by Jeffries and Archer13 is not consistent with the observed length of an, individual slip and the amount of elongation which can be obtained by wire drawing. The modifications, which have been proposed to this hypothesis to make it coincide with the experimental facts, have to a considerable extent robbed the theory of its clean-cut characteristics. The commonest of these modifications replaces the amorphous phase with an

Jan 1, 1927

By Rafael Masulck Santos

Este trabalho tem o intuito de correlacionar as principais variáveis dos processos de Recozimento em Caixa e Laminação de Encruamento com as características magnéticas de aços Laminados a frio para fins elétricos de grãos não orientados destinados às aplicações “totalmente processadas” e “semi processados”. Foram utilizadas diferentes temperaturas e tempos de encharque, e posteriormente distintos passes de redução no processo de Encruamento. As microestruturas resultantes das variações dos parâmetros de processo foram analisadas e correlacionadas com as características magnéticas obtidas por ensaio Epstein.

Aug 17, 2017

By R. J. Campbell

[The steady increase of aluminum production means a corresponding increase of carbon consumption in the alumina-reduction cells. Improved petroleum techniques constantly reduce the amount of byproduct petroleum-coke production. These, trends threaten the alumina-reduction works with possible shortages of carbon, which must be supplied from some other source. In anticipation of this shortages, an investigation into the possibility of using coal as an alternative source of carbon was begun at the Northwest Experiment Station of the Federal Bureau of Mines. The investigation lit has developed bench-scale methods that produce carbon of higher purity than is required by specifications for anode carbon. Additional work will b required to bring these processes to pilot-plant seals and to prove the suitability of the carbons, produced or aluminum-anode consumption.]

Jan 1, 1956

By R. J. Leary

A small electronic digital computer employing punched cards has been used to facilitate the solution of a variety of problems in Bureau of Mines pyrometallurgical research. In this work the computer has been found to be economical for solving both simple problems that occur repeatedly and those involving complex or iterative calculations. Each of these classes of problems and their respective solutions are described. These small computers can be used effectively by researchers when they work in consultation with a computer specialist. Close team work produces the required solutions in less time, and, oftentimes, in a more useful form. Participation in programming by researchers develops in them a skill for evaluating the suitability of problems for electronic computing.

Jan 1, 1960

By C. Mattich, A. L. Beyzavi

The Waelz Plant at Taiwan Steel Union Co. Ltd. (TSU) was erected within nine months from September 1, 1998 to May 15, 1999. The nominal capacity of the plant is 50,000 tonnes per year of electric are furnace dust (EAFD). The plant, consisting of material handling, a waelz kiln, a waste gas cleaning system, waelz oxide leaching and waste water treatment, was commissioned within three months from July 1, 1999 until October 12, 1999. The specific problem of the plant is the high chlorine content in the EAFD pellets which is up to 6 %. Lurgi Metallurgie GmbH, Frankfurt, Germany was responsible for the engineering erection and commissioning of the plant.

Jan 1, 2000

By AIME AIME

Report of Committee 24, of the International Association for Testing Materials, presented at the Brussels Congress, 1906. Republished for use at the 94th Meeting of the American Institute of Mining Engineers, New York, N. Y., February, 1908. Discussion by letter is requested by the Secretary of the Institute. The Committee appointed for the solution of Problem 24 consisted of the following members Prof. H. M. Howe, New York, N. Y. (Chairman); L. Levy, Paris, France (Vice-Chairman) ; Prof. D. Tschernoff, St. Petersburg, Russia (Vice-Chairman) ; Prof. Albert Sauveur, Cambridge, Mass. (Secretary) ; Van Drunen, Ixelles, Belgium; Lieut.-Col. H. Tusen, Copenhagen, Denmark ; E. P. Martin, Abergavenny, England ; A. Pourcel, Paris, France ; H. Brauer, Dortmund, Germany ; Dr. Prof. H. Wedding, Berlin, Germany; P. Verole, Milan, Italy ; A. Baalsrud, Christiania, Norway ; A. R. v. Dormus, Vienna, Austria ; A. Sailler, Vienna, Austria; Bureau des Forges, St. Petersburg, Russia; Prof. N. Belelub-sky, St. Petersburg, Russia ; N. Jossa, St. Petersburg, Russia ; Maj.-Gen. M. Korobkoff, St. Petersburg, Russia ; S. Smirnoff, St. Petersburg, Russia ;.Ladislaus v. Tetmajer, Budapest, Hungary ; H. H. Campbell, Steelton, Pa. Early in February, 1905, a list of species and varieties of iron and steel, with definitions, drawn by the Chairman and Secretary of Committee 24, was sent to every member of this Committee with a request for comments and suggestions. A special request was sent to the following gentlemen . for the equivalents in their several languages of these species and varieties : A. , Pourcel, Paris, France; Prof. H. Wedding, Berlin, Germany ; J. A. Brinell, Stockholm, Sweden ; Prof. H. I. Hannover, Copenhagen, Denmark; Prof. P. Kley, Delft, Holland; P. Verole, Milan, Italy; Col. Cubillo, Trubia, Spain. This present report, which is based upon our original list and definitions, and upon the replies to these requests, consists of four parts I. A polyglot, which gives the names of the chief classes of iron and steel in English, French, German, Swedish, Danish and Dutch. We .regret that we have failed to get the Italian and Spanish names. II. English definitions of principal classes of iron and steel. III. A glossary of special sizes and shapes of iron and steel. IV. A note on the boundary between steel and cast-iron. I. POLYGLOT, IN ENGLISH, FRENCH, GERMAN, SWEDISH, DANISH AND DUTCH, OF THE CHIEF CLASSES OF IRON AND STEEL, AND OF THE APPARATUS IN WHICH THEY ARE MADE. This list is not intended to be complete, but rather to include only those varieties which are of interest to the Association.

Mar 1, 1908

By W. R. McDonald

The U.S. Bureau of Mines investigated treatment of gold and silver refractory ores and concentrates that respond poorly to conventional cyanidation techniques due to the complex mineralogy of the ore. Three types of ores were investigated: gold locked placer sands, gold locked in sulfides, and gold that is robbed from the pregnant cyanide solutions by minerals in the ore. Ore treatment included grinding, flotation, cyanidation, air oxidation, pressure oxidation, hypochlorite oxidation, roasting, and carbon in leach.

Jan 1, 1991

By D MacKay

The Mt Wright Project is located near the town of Ravenswood in North Queensland and is operated by Carpentaria Gold – a wholly owned subsidiary of Resolute Mining Limited. Underground Development of the current Mt Wright orebody commenced in June 2006 and the first production ore was brought to surface in June 2007. The orebody is a rhyolite pipe containing fine-grained disseminated gold in a granite host rock. Ground conditions tend to be good to excellent throughout development, with some minor deformation experienced when stope-sized excavations are formed. The mine commenced as a sublevel open stoping (SLOS) operation with the intent to utilise development waste to back fill isolated upper level stopes while developing to the bottom of the known orebody. The mine plan intended to commence production with a bottom-up primary/secondary stoping retreat through the main orebody utilising cemented fill. Some challenges were faced during the initial production phase that included:•Ongoing underground diamond drilling and updating of the block model resulted in some issues reconciling the grade control results to the resource model. This was primarily due to the high variability of grade which in turn caused difficulties in accurately identifying areas of low and high-grade.•The cost of establishing and operating a cemented fill plant to achieve the planned extraction sequence of the orebody had increased significantly beyond initial estimations.•Geotechnical conditions such as stress orientations, ground behavior and response to the forming of excavations learned through the mining of the upper level stopes were different to the assumptions made during the initial design.A number of in-house and external reviews of the mining method were completed which has resulted in a revised mining plan. This paper will summarise the challenges faced and the implementation of the mine plan to date.

Mar 21, 2011

By M. Wasel

The Gross Rosebel gold deposits are located in the Guiana Shield of north central Suriname. Initial discovery of surficial gold in 1880 by local artisanal miners preceded small-scale mechanized mining from 1885 to 1939. The first systematic exploration program was carried out by Placer Development from 1974 to 1977. In May 1992 Golden Star Resources optioned the property. Initial shallow reconnaissance diamond drilling of the extensive surface geochemical anomalies intersected sporadic gold mineralization with no apparent continuity between drill sections. Successive deep augering, trenching and systematic grid drilling based on information from surface mapping allowed development of a preliminary geological model. Further drilling of specific structural-lithologic targets and more complete synthesis of geological data from the trenching and deep auger sampling added to the geological model and defined the multiple controls of gold mineralization. Carefully planned infill drilling on a tighter grid spacing resulted in progressive definition of reserves within six discrete gold deposits. In a complex geological setting, the key to success at Gross Rosebel was persistent, systematic exploration, detailed mapping, careful core logging and perceptive geological interpretation. Reserves now stand at 48.6 Mt at 1.6 glt Au, or 2.4 million ounces of gold. The purpose of this paper is to describe the progression of exploration activity that led to the definition of substantial gold reserves and to summarize the geology of the deposits.

Jan 1, 1998

By B. S. Hulvey

Thin support liners are becoming more accepted and being developed with improved properties because the mining industry as a whole has been offering underground safe test trial sites. This is because of the huge potential for such products. Recent developments tend to indicate that the technology is “coming of age” and these are discussed in this paper.

Jan 1, 2003

By F. R. Cattoir

This Bureau of Mines study investigated molten salt electrorefining for beneficiating low-grade, high-carbon ferrochromium products which can be readily produced from domestic chromite concentrates. A second objective was to refine commercial ferrochromium into low-iron chromium products. Electrorefining of both types of ferrochromium in molten CaC12-NaCl-CrC12, CaCl2-MgC12-CrCl2, or KC1-LiCl-CrCl2 electrolytes produced chromium-iron products with virtual elimination of other impurity elements and some lowering of the iron content, Over 90 percent of the chromium present in the feed materials was recovered. The electrodeposited products were upgraded further by magnetic separation techniques into chromium containing less than 5 percent iron. The technical feasibility of preparing a premium chromium product from a low-grade, high-carbon ferrochromium made from domestic chromite was demonstrated. Chromium virtually free of carbon, oxygen, and silicon from high-carbon ferrochromiums was produced. In addition, the amenability of three commercial grades of ferrochromium to electrorefining and magnetic separation for preparing chromium metal containing less than 5 percent iron was determined.

Jan 1, 1969

By William G. Pariseau, Mark K. Larson, Douglas R. Tesarik, Heather E. Lawson

"This contribution describes development and application of a user-friendly finite element program, UT3PC, to address three important problems in underground coal mine design: (1) safety of main entries, (2) barrier pillar size needed for entry protection, and (3) safety of bleeder entries during the advance of an adjacent longwall panel. While the finite element method is by far the most popular engineering design tool of the digital age, widespread use by the mining community has been impeded by the relatively high cost of and the need for lengthy specialized training in numerical methods. Implementation of UT3PC overcomes these impediments in three easy steps: First, a material properties file is prepared for the considered site. Next, mesh generation is automatic through an interactive process. A third and last step is simply execution of the program. Examples using data from several western coal mines illustrate the ease of using the application for analysis of main entries, barrier pillars, and bleeder entry safety.INTRODUCTIONRational design of safe underground entries and crosscuts, barrier pillars, and bleeder entries begins with a site-specific analysis of stress. An analysis of stress identifies the critical regions of high-stress concentration where yielding is likely and additional or more focused ground control measures are needed. This analysis also identifies regions where stress concentration is low, and risk mitigation is less urgent. Displacements induced by mining, including roof sag, floor heave, and pillar squeeze, are also of importance to stability. The popular finite element method is well-suited for such analysis and has been in use for studying coal mine engineering problems since the late 1960s (Dahl, 1969). The method has been taught in undergraduate engineering curricula for many years and offers an alternative to existing design procedures based mostly on rules of thumb, empirical methods based on mine data, and predigital-age concepts of strata mechanics. However, despite the versatility of the finite element method, usage has been limited, mainly because of the cost of the software and the required training in numerical methods.The program UT3PC (Pariseau, 2017) has evolved from early two-dimensional versions in the era of mainframe computers. These early versions were still quite limited using only a few hundred elements that required overnight turnaround times. Recent versions of UT3PC are convenient and efficient desktop programs that use several million elements. With the advent of personal computers in the mid-1980s and subsequent increase in computer speed, expanded memory, and lower costs, applications for mining increased in three-way cooperative projects among industry, the former U.S. Bureau of Mines, and academia. The Spokane Research Center of the U.S. Bureau of Mines, in cooperation with the University of Utah, developed a two-dimensional desktop finite element program, UT2PC, available to the mining community in 1991. This was a short course offered at the 1991 SME Annual Meeting in Denver, CO."

Jan 1, 2017

By John M. Hancock

IN beginning my remarks, may I make it entirely clear that since January 4, 1947, I have not been a member of the United States Delegation to-the United Nations Atomic Energy Commission I am speaking, therefore, in purely a personal capacity. Because of the interest of the engineering profession with reference to uranium, and because of the title assigned me for this talk, I am going to assume that you know what the United States Plan is for the control of atomic energy. At best, in the limited time, I could only summarize, at the risk of giving undue emphasis to the items mentioned, and at the risk of omitting many important parts of what seems so far to be a complete and well-rounded Plan for meeting the problem. I will aim to comment upon those aspects of the Plan that continue as problems and involve apparent, or obvious, misunderstandings and contrary views The control of atomic energy represents not only a problem but a challenge-both faced by- all the peoples of the world It involves a new approach to the problems of the kinds that arise between nations, problems that have not ever been solved even by international treaties in their efforts to outlaw weapons of war. These efforts range from the Kellogg-Briand treaty to outlaw war, and its obvious failure to prevent World War II, to the interdiction by the Pope of the use of the crossbow in the days of the Crusades. All previous plans have been failures-that makes

Jan 1, 1947

By J. Rostami, P. P. Nelson, A. Khetwaln

Tunnel boring machines (TBMs) can be considered as the method of choice for tunneling in many projects due to the high level of efficiency and high potential productivity, safety, and applicability in a variety of subsurface conditions. The muck transportation system in a TBM tunneling operation plays a significant role in the process and impacts the overall performance of the machine. This paper introduces a recently developed method of simulating TBM operation through discrete event simulation (DES), which allows for tracking of the various activities, incurred downtimes in the operations, and overall machine utilization. The study presented here compares two different muck transportation systems, conveyor and rail, under similar geological conditions to quantify the impacts of the choice of muck transportation systems on machine utilization. The results show the applicability and extent of redundancy in the use of the two systems relative to machine capabilities and their sensitivity to geological conditions.

Jun 13, 2021

By Jr. Sillers

This is the third report of investigations dealing with the application of electrolytic manganese to steel-foundry practice and the seventh in a series of reports dealing with tests to establish the technological acceptability of electrolytic manganese in the iron and steel industries. The work was carried out by Metallurgical Division of the Bureau of Mines as part of an extensive program for the development and utilization of domestic ores. The electrolytic manganese used in the tests was produced by the Bureau at its Boulder, City, Nev., pilot plant by the process developed by the Bureau of Mines.

Jan 1, 1949

By P. S. Newall

As part of a much larger research project, factor analysis was employed to help interpret and compare the geochemical signatures produced by two different sample media; a traditional -80# soil fraction, and a coarse float. Both sample types were collected by hand auger from the extension zone of the Redmoor sheeted-vein complex and analyzed -for 19 major and trace elements. The rationale behind the study infers that the geochemical anomalies produced by wallrock alteration around such targets can be better detected in the lithogeochemical rather than the soil environment, sometimes at considerable distance from their source.

Jan 1, 1991

By Edwarde R. May

The Flambeau volcanogenic massive sulfide deposit located in northwestern Wisconsin occurs within the southern lobe of the Canadian Precambrian Shield. The steeply dipping tabular body occurs in a complex pile of cyclic schistose intermediate to felsic fragmental volcanics. No chloritic alteration pipe is recognized but adjacent rocks have undergone magnesia metasomatism and subsequently were metamorphosed to the upper greenschist and lower amphibolite facies. Although modest in size the deposit is of special interest in that it has an extensive and well preserved supergene enrichment blanket. Economic minerals found within a pyritized quartz-sericite schist are chalcocite and bornite overlying primary chalcopyrite.

Jan 1, 1976

By J. J. Ferreira, M. L. Thurston, I. L. Chinn, D. M. Rose

"Concerns about using microdiamonds for resource estimation have been raised by workers because multiple diamond populations exist in many parts of the mantle source region, small diamonds in kimberlite could be exposed to proportionately greater levels of resorption and modification, and euhedral microdiamonds could crystallize immediately prior to kimberlite eruption. This paper addresses these concerns; discusses the geology of the mantle, the principal diamond host rocks, and the impact of mantle processes; compares micro- and macrodiamond properties and features; and outlines steps to identify and mitigate the risk of diamond resorption and its impact on the diamond grade-size relationship.RÉSUMÉ Des travailleurs se sont interrogés sur l’utilisation de microdiamants pour estimer la ressource; en effet, de multiples populations de diamants existent dans plusieurs secteurs de la région source dans le manteau. Des petits diamants dans la kimberlite pourraient être exposés à des niveaux proportionnellement supérieurs de résorption et de modification; de plus, des diamants idiomorphes pourraient cristalliser immédiatement avant l’éruption de la kimberlite. Le présent article traite de ces questions, discute de la géologie du manteau, des principales roches-mères des diamants et de l’impact des processus dans le manteau, compare les propriétés et les caractéristiques des micro- et des macrodiamants et définit les étapes pour identifier et mitiger le risque de résorption des diamants et son impact sur la relation entre la taille et la qualité des diamants."

Jan 1, 2016

By William P. Blacutt

This paper describes the strategy, the struggles, and the obstacles encountered during the last two years in the ongoing process to capitalize Vinto. The effort involves the offering of a vertically integrated business package composed of the tin and antimony smelters along with the two principal tin mines of the country. Capitalization: Bolivia's Innovative Approach for Privatization, the Vinto Case provides a summary of hard-earned lessons. These experiences can be success- fully implemented in other nations committed to transforming their state natural resource sector.

Jan 1, 1998

By H. Cui

Rapid technological development has caused an increase in the demand for rare earths. Ancylite, a strontium rare earth carbonate, is a potentially significant source of rare earths. In this research paper, essential aspects of the magnetic separation and flotation processes for Bear Lodge ore are presented. A flowsheet is proposed based on an optimization of the variables and flotation simulation. The economic feasibility of the proposed processing operation is analyzed.