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By A. C. Hnatyshyn

INTRODUCTION THOSE concerned with coal mining operations in Alberta have been asked repeatedly the same question, "Why is mechanization in Alberta proceeding so slowly as to lag far behind the mines in the United States?" This question is often asked in such a manner as to indicate that a severe reprimand is overdue to the mining engineers of this Province for their apparent indifference to the problem of improving their mining operations by increased mechanization. To the average person, unacquainted with mining conditions and problems, mechanization appears to be simply a matter of introducing equipment to load coal underground and, once this is done, substantial economies in operating costs will automatically follow. Invariably, those who have followed this simple reasoning have found, to their regret, that such is not the case and that effective mechanization involves something more than the mere process of introducing loading equipment into a mine. To be effective, any programme of mechanization must take into consideration all operations incidental to the mining, transportation, and handling of the coal from the working face to the tipple, and must utilize equipment which can be best adapted to any peculiar condition or circumstance prevailing in the mine concerned. In the use of such equipment, the net and final result should be an improvement in operating costs of sufficient magnitude to at least return to the operator, over a specific period of years or during the expected life of that equipment, all his investment plus a fair return on that investment.

Jan 1, 1951

By Antonio Fabiano de Oliveira

Estudos de laminação com revestimento de cromo e influência nas propriedades foram realizados com o objetivo de aumentar a produtividade dos cilindros. Para tal, foram utilizados cilindros cromados para laminação de chapas de cobre, com amostragem da técnica de réplica epoxy. A compreensão da correlação entre microestrutura e propriedades do material é objeto de grande interesse e, ao mesmo tempo, necessário para aplicação prática na laminação a frio, combinando revestimento e produtividade. O objetivo da pesquisa atual é comparar as propriedades tribológicas do cobre antes e depois da laminação, no cilindro de trabalho e chapa, com e sem revestimento de cromo.

Oct 30, 2017

By Andrew Matyas

"During the summer of 1968, the author was employed in the Research Department of Dominion Foundries and Steel, Limited, Hamilton, Ontario. Over the years, Dofasco has been conducting a program for developing more efficient control of its basic oxygen steelmaking process. The author was thus able to obtain a variety of viewpoints from both research engineers and furnace operators. He also had access to extensive literature dealing with BOF control schemes underway at other major steel producers. This paper describes the present state of developments in BOF steelmaking control.The necessity for efficient BOF control is pointed out. To appreciate the variables to be controlled, a brief outline of process fundamentals is included. Technical aspects of present methods of practical control are examined in detail; the relative merits of dynamic over static control models are emphasized. Finally, it is shown how an effective dymic-optimizing control scheme serves as the basis for closed-loop computer control of the process."

Jan 1, 1970

By Patrícia Freitas Rodrigues, Talita Gama de Sousa, Paulo Inforçatti Netto, Danilo Abílio Correa Gonçalves, Rebeca Vieira de Oliveira, Eduardo Hoisler Sallet, Jorge Vicente Lopes da Silva, Naiara Vieira Le Sénéchal, Rodolfo da Silva Teixeira, Andersan dos Santos Paula

O processo de fusão seletiva a laser (FSL) é comumente utilizado na manufatura aditiva de materiais metálicos, sendo este um processo rápido no qual as peças são formadas camada por camada. Neste processo uma fonte de laser varre o leito de pó e seleciona as regiões a serem fundidas, através da alta intensidade de potência aplicada, de acordo com o projeto digital proposto, para obter peças com boa densidade. Embora a FSL apresente diversas vantagens, em relação aos processos de fabricação convencionais, esta ainda é de alto custo para indústria. A otimização de parâmetros de processamento desta tecnologia para as ligas com memória de forma vem sendo explorada. As ligas NiTi com memória de forma se destacam por apresentarem o efeito memória de forma e a superelasticidade, o que lhe confere várias aplicações práticas. Otimizar, no processo da FSL para essas ligas, o parâmetro densidade de energia do laser, é fundamental para obter as peças com boas propriedades mecânicas e baixa porosidade. Com isso, este trabalho tem como objetivo observar e criticar a influência dos parâmetros de processamento na microestrutura e porosidade dos corpos de prova de ligas de NiTi manufaturados via FSL.

Nov 15, 2019

By Foluke Salgado de Assis

A fibra de juta é uma das fibras com grande potencial para ser aplicada como tecido reforçando compósitos poliméricos Este trabalho avaliou a resistência ao impacto para compósitos de matriz poliéster reforçado tecido de juta. Os corpos de prova foram fabricados com diferentes percentuais de tecido de juta: 0, 10, 20 e 30% em fração volumétrica. O tecido sido de juta foi embebedado com resina poliéster (estado líquido) e curado em temperatura ambiente durante 24 horas. As amostras foram ensaiadas utilizando o pêndulo impacto Izod and a superfície de fratura foi examinada utilizando o microscópio eletrônico de varredura. A resistência ao impacto Izod dos compósitos poliéster-juta cresceu de maneira linear com o aumento da quantidade de tecido de juta. Utilizando 30% de tecido de juta, foi possível obter 83,1 J/m enquanto o poliéster puro (0% de tecido) obteve 21,8 J/m. O bom desempenho do compósito poliéster-juta pode ser associado com a dificuldade de romper o compósito em virtude do tecido de juta, assim como, as trincas produzidas através da interface poliéster/tecido de juta que colaborou com o aumento na absorção de energia durante o ensaio de impacto Izod.

Oct 30, 2017

By Juliovany Drumond

Este trabalho apresenta os resultados da produção do aço bifásico DP980 galvanizado a quente na ArcelorMittal Brasil, com foco no atendimento às propriedades mecânicas e microestruturais. Foram analisadas bobinas produzidas industrialmente de um aço bifásico baixo carbono com e sem adição de boro, e também amostras para simulação de recozimento. A análise foi baseada nas propriedades obtidas no ensaio de tração e também na microestrutura. Foi observado que o aço com adição de boro apresentou propriedades mecânicas mais elevadas que o aço sem a adição deste elemento, e este aumento está diretamente relacionado à maior fração volumétrica de martensita encontrada neste aço. Este fato está ligado à segregação do boro nas interfaces ferrita / austenita durante o recozimento intercrítico, evitando assim a nucleação e crescimento da “nova” ferrita, com um consequente enriquecimento de carbono na austenita. Esta austenita mais enriquecida de carbono gera uma maior quantidade de martensita na microestrutura final. Diante disso, o aço DP980 produzido industrialmente com adição de boro apresentou melhores propriedades mecânicas e microestruturais, sendo compatível com os requisitos demandados atualmente pela indústria automotiva, quando galvanizado a quente nas condições de processo estabelecidas neste estudo.

Jul 30, 2018

By Marcos Meyer

A pelotização é um processo de aglomeração com objetivo de agregar valor aos finos de minérios de ferro (pellet feed). A partir de 2010, a mina de Brucutu situada no Quadrilátero Ferriferro (QF) passa a ser a maior fornecedora de matéria prima para as plantas de Tubarão / Vitória-ES. O estudo avaliou a performance industrial de duas misturas com alta participação de minério de Brucutu, acima do padrão utilizado na usina de pelotização. Os minérios compostos nas misturas foram caracterizados por análise química, física, mineralógica e microestrutural. O desempenho operacional mostrou superior à mistura padrão utilizada para a produção de pelotas para redução direta, permanecendo com os parâmetros de qualidade consoantes com as especificações do produto final. O conhecimento das características geometalúrgicas destas misturas com minério de Brucutu em maior escala foi de suma importância para adequar o processo e custo das principais operações unitárias da planta envolvida (moagem e forno).

Aug 1, 2018

By Pablo Reis Dias

A necessidade da aplicação dos aços de alta dureza é recorrente nas indústrias de mineração, visto que esses equipamentos são submetidos continuamente a esforços mecânicos. Por isso o objetivo deste trabalho é caracterizar uma amostra de aço Hardox 450 HB soldada pela técnica undermatching com a finalidade de se avaliar a sua soldabilidade, dureza e microestrutura, qualificando a sua predisposição para o uso fabril. Realizou-se o ensaio de composição química, o ensaio metalográfico e o de microdureza afim de se comparar com os dados de fabricantes deste aço e avaliando com os parâmetros de soldagem aplicados a sua susceptibilidade à propagação de trincas. Observou-se que a microestrutura revelada é a martensita com conformação de grãos mais refinados entre o metal de base e o metal de adição. Através da análise química percebeu-se que de acordo com o valor do carbono equivalente, este aço possui média soldabilidade.

Oct 30, 2017

"Cash flow modelling during project evaluation is enhanced when probabilistic methods are applied to the inputs. One of the important inputs is the quarterly production profile. Typically, the steady-state production profile provided to project evaluation practitioners is deterministic, with each quarter the same as every other quarter. This is unrealistic as actual production profiles from existing mines exhibit a range or quarter-on-quarter variance. Monte Carlo stochastic simulation of the production profile can be used to provide a range of possible outcomes, but how are these ranges selected? This paper describes the use of quarterly production variance from a large database of mines worldwide as a benchmark to inform the appropriate selection of ranges. The coefficient of variation is used to rank the production from mines, with quartile analysis applied to indicate industry best, median and worst variation. Due diligence of existing mines and evaluation of future production performance can be quantitatively assessed using this approach. Examples of the effect on value are provided.CITATION:Stewart, C A, 2016. Production variance benchmarks and their use in project evaluation and due diligence, in Proceedings Project Evaluation 2016, pp 201–213 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By V. Sastry

Signgareni Collieries Company Ltd. is operating the JK Opencast Project, at Yellandu, with a rated annual capacity of 1.6 Mt of coal with an average stripping ratio of 4.3. This opencast coal project has three working sections, OC-II block, C-Block and D-Block These workings are operating in close proximity to the JR-5 Longwall Shed, 26-Dip Incline, other structures of 26-Dip, and a Township. There were complaints about ground vibrations and fly rock problems caused due to blasting operations, especially in OC-II and D-Blocks. In view of this, studies were taken up to eliminate the problems of ground vibrations and fly rock.

Jan 1, 2001

[Addison, Herbert Big Horn Colleries Co., Colo. Bldg., Denver, Colo. Aleshire, N. C c-o Roberts & Schaefer Co., Wrigley Bldg., Chicago, Ill. Alexander, John Dacona, Colo. Allan, David Lafayette, Colo. Allen, John Ludlow, Colo. Allen, Thomas Box 420, Glenwood Springs, Colo. Alley, Gerald C. F. &I. Co., Pueblo, Colo. Allison, ArchieBox 562, Walsenburg, Colo. Allison, D. S 1331 Roberta St., Salt Lake City, Utah Allison, Park Engineer, Standard Coal Co., Standardville, Utah Allonier, Howard R c-o Lunkenheimer Co., Cincinnati, Ohio Ambler, J. B c-o Ambler & Riter, Kearns Bldg., Salt Lake City, Utah Anderson, A. E 403 Ideal Bldg., Denver, Colo. Andrews, Sam 503 Pike Ave., Canon City, Colo.. Angster, Joe Walsen, Colo. Angus, William B. W. Snodgrass, 1575 Lafayette St., Denver, Colo. Apperson, A. B Tramway Bldg., Denver, Colo. Armstrong, C. D Apperson Vallery Co., Tramway Bldg., Denver, Colo. Arnoldi,, Victor Ideal, Colo. Autrey, J. S Perrenaud Apts., Denver, Colo. Bachman, W. H 1601 Alcott St., Denver, Colo. Bailey, R. E Utah Power & Lt. Co., Kearns Bldg., Salt Lake City, Utah Baird, Elmer A Equitable Bldg., Denver, Colo. Bartlett, G. F 311 Ernest & Cranmer Bldg., Denver, Colo. Baxter, John M 3748 Lafayette St., Denver, Colo. Becker, J. A Box 682, Rock Springs, Wyo. Beebe, John. D 1414 Court Place, Denver, Colo. Bennett, F. C Colorado Fuel & Iron Co., Berwind, Colo. Benson, Geo Cumberland, Wyo. Betcher, B. L Standardville, Utah Beuchat, Charles Pryor, Colo. Bevan,John 1625 North Corona St., Colorado Springs, Colo. Bisch, James L Van Houten, N., M. Boissier, A. H. C Boston Bldg., Denver, Colo. Bottomley, Edward Kleenburn, Wyo. Bowen, James V Union Coal & Coke Co., Colorado Bldg., Denver, Colo. Bowie, Alex R Bowie, Colo. Bowie, John S Bowie, Colo. Bowie, Wallace D Bowie, Colo. Bowns, W. J Castle Gate, Utah Boyer, F. E 631Jackson St., Denver, Colo. Boyle, Chas Sweetwater, Wyo. Brandenburger, L 59 W. Broadway, Salt Lake City, Utah Brennan, W. D Dawson, N. M. Brewster, Burt B Walker Bank Bldg., Salt Lake City, Utah Brockman, A. L Sugarite, N. M. Brooks, Ed 513 Second St., No. 1 Hill, Rock Springs, Wyo. Brown, Geo. A Cumberland, Wyo. Brown, L. E :.1212 Walker Bldg., Salt Lake City, Utah Brown, Mark Y 629 East Main St., Trinidad, Colo. Bubb, H. H Cokedale, Colo. . Bullock, W. H 1052 Gas & Electric Bldg., Denver, Colo. Bunning, P. C Rock Springs, Wyo. Burnite, Thomas B 523 Boston Bldg., Denver, Colo. Butler, T. H Hanna, Wyo.]

Jan 1, 1924

By E. P. Youngman

This paper is one of a series of digests of foreign mining legislation and court decisions that is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines" in various foreign countries. In the preparation of this interpretation of the laws of Norway, use has been made of William R. Orrmins' translations of various acts of the Norwegian Government, which were forwarded from the American consulate at Oslo^ and transmitted to the Bureau of Mines through the courtesy of the State Department. This digest is released subject to amplification and correction, if necessary, by the proper American foreignservice officers.

Nov 1, 1932

By W. D. Bullock

The King-Beaver mine of Asbestos Corporation Limited operates an open pit in the city of Thetford Mines, Quebec. The approximate loca-tion of the open pit is at Latitude 46° 02' North and Longitude 71° 20' West. The general topography is 1020 feet above sea level. Thirty-six percent of the company's scheduled asbestos ore production, for the Thetford Mines area, comes from the King-Beaver pit. The pit operates 24 hours a day, six days a week. Normal production is 10,500 tons of ore per day at a waste to ore ratio of 2 to 1. The remaining ore requirements are mined from the King-Beaver underground mine and the British-Canadian mine.

Jan 1, 1980

By John F. M. Sims

Political issues and a glaring infrastructure deficiency have retarded the emergence of a strong mining component to the Alaskan economy in recent years. Barriers to orderly mineral development are slowly being removed attendant upon changing political circumstances. Infrastructure development, as an investment avenue as well as a responsibility of the State, is receiving much greater attention than in the past. Alaska of course has a rich and varied mining history going back to the 19th Century. This paper, however, focuses on the mining potential, not the mining heritage of the 49th State. The mining industry is emerging from a nadir in the economic cycle - times during which it was buffeted by unsympathetic administrations and confused and confounded by the protracted land status- conflicts prior to enactment; of the Alaska National Interest Lands Conservation Act (ANILCA) and other milestone legislation. Today Alaska's mining industry looks toward a bright and healthy future and, in the process, will become a very important and vital component of the State and national economy.

Jan 1, 1982

By R Cunningham

The E26 Lift 1 North Project took 37 months from the approval on 1st January 2019 to the commencement of production on 1st March 2022. This was five months ahead of the feasibility plan. When compared to the previous E48 Block Cave construction 12 years prior, which was of a similar size and design with ten extraction drives, crusher and conveyors, the E26 Lift 1 North project has been delivered at 29 per cent less capital cost. Key metrics achieved by the project include 12.7 km of development, 240 km of production drilling for drawbells and undercut blasting, 107 drawbells fired ready for production as well as only three Lost Time Injuries compared to 16 during E48 construction. The Lift 1 North Project Team has established a significant point of difference with the delivery being completed by the ‘Owners Team Model’ not Lump Sum or Turn-key. E26 Lift 1 North is now supplying the Northparkes processing plant for the next eight years. This paper discusses major milestones achieved throughout the process, modifications to processes from previous block cave construction at Northparkes as well as novel approaches to work to achieve the successful delivery of the project.

Mar 29, 2023

By J. E. Rehder

IN A DISCUSSION of use of any material of ?construction in the mining industry, two points of view must 'be kept in mind - that of the producer or manufacturer of mining and metallurgical equipment, and that of the maintenance and operating staff of the mining plant. In the first case, the choice of material of construction is up to the manufacturer and the user of the equipment has little direct say in the matter. However, if materials are badly chosen and the equipment does not function properly, wears out rapidly, or costs too much, repeat orders ?will likely go to a different manufacturer, so that, in the end, the consumer or mine operator does have the final voice. In the case of materials for maintenance work and plant operations, however, .the mill personnel have direct control over purchases and it is then that a well-balanced knowledge of materials, their properties, and their costs, can be directly useful. With all materials of construction, the final criterion is unit cost versus service performance, so that the lowest possible total operational cost will be obtained. Sometimes this means using the cheapest material available, sometimes the most expensive, but in any case careful analysis of service performance, replacement cost, and material cost is essential to determining the material that produces lowest total cost.

Jan 1, 1956

By Xiao Yang

Calcium oxide is one of the major fluxing agents used for steel refining. Because unreacted CaO remains in slag in most cases, discharged slag is difficult to be recycled smoothly. With the growth of environmental concerns, improving utilization efficiency of CaO is required to reduce the amount of discharged slag and energy consumption. The authors have reported a resource and energy-saving process by using multi-phase flux for dephosphorization. Reaction behavior of phosphorus in multi-phase CaO–FeOX–SiO2–P2O5 flux system was investigated. Formation mechanism of P2O5-rich phases was clarified at the interface between solid CaO or 2CaO, SiO2 and molten CaO–FeOx–SiO2–P2O5 slag. Phase relationship and thermodynamic properties of 2CaO, SiO2-3CaO, P2O5 solid solution were observed to confirm the condensation of P2O5 in solid phase. Based on these results, reduction of CaO consumption, discharged slag curtailment, and energy-saving effects in the novel refining process by using multi-phase flux were discussed.

By Nava-Vasquez E, Torres-Torres J, Mendez-Nonell J

The ZA-27 zinc base alloy was poured into cylindrical moulds and solidified under different conditions ie normal freezing and unidirectional freezing. In addition a cylindrical ingot with rheocast material was obtained by stopping the stirring action and, at a specific solid fraction, gravity casting it into a graphite mould. It was observed that the material obtained under normal freezing conditions is likely to present both segregation and inverted pipe. In contrast, the unidirectional solidified and the rheocast cylinders showed the absence of inverted pipe. The segregation pattern was quite irregular in the rheocast ingot while such segregation was more uniform in the unidirectional solidified cylinder. By virtue of these observations, the inverted pipe formation may be ascribed to the interdendritic flow, while the irregular segregation pattern in the rheocast ingot may be attributed to an irregular distribution of the liquid and solid fraction along such a cylinder.

Jan 1, 1993

By P Toor

Due to the high energy consumption of milling, it is desirable to improve the efficiency of this process. One alternative to reduce energy and material consumption while optimising production yield in mill operation is through balanced design and selection of liners. Over-design of liners leads to increased life but at a cost to grinding performance, a relationship which to date has not been studied closely. This paper provides a description of this process of liner life cycle optimization and presents initial results from the first of two life cycles being studied for a 32 foot (ft) SAG mill. The use of commercially proven high resolution laser scanning based liner shape information provided by the MillMapper® software correlated with well controlled site surveys at various points in the liner life was used as the basis for comparison. The survey data was modelled in JKSimMet to provide direct comparisons of mill performance. This potentially provides a methodology for the design of liners that maintain a favourable shape for the majority of liner life, yielding desirable production parameters such as lower specific energy consumption and higher throughput, while at the same time maintaining practical liner life cycles.

Aug 8, 2011

By Thais da Silva Rocha

O objetivo deste trabalho é avaliar a reatividade de um metacaulim comercial a partir da análise de sua cristalinidade. Um tratamento térmico é proposto a fim de tornar o material mais amorfo e para isso o metacaulim comercial já calcinado foi submetido a três tempos e temperaturas de queima em forno mufla (700°C em 1h, 600°C em 2h e 500°C em 1h). Após a queima o tratamento térmico que alcançou o melhor resultado foi o de 600°C em 2 horas, apresentando quase que somente picos cristalinos de quartzo nas análises de DRX. Para avaliar a influência do amorfismo na resistência mecânica de argamassas geopoliméricas foram moldados corpos de prova cilíndricos de Ø 50x100 mm com o metacaulim comercial como referência e com os metacaulins calcinados. Todas as argamassas foram feitas com a mesma dosagem e ensaiadas com 24 horas após a moldagem. O aumento de resistência à compressão chegou a 53% com o metacaulim queimado a 600°C, mostrando que assim como acontece com argamassas de cimento Portland a calcinação completa é um fator crucial para o ganho de resistência mecânica em argamassas geopoliméricas.

Oct 30, 2017