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By J. M. Boxall

The electrolytic zinc plant at the Bartlesville division of Z.C.A. originally used lead anodes containing only 0.25% silver because only H.G. zinc and alloy was to be produced. In 1984, a small addition of strontium carbonate was made to control the surf ace morphology of the cathodes which reduced short circuits and increased current efficiency. Later a drastic reduction in colloid addition further reduced short circuits. Increased strontium additions allowed the production of some S.H.G. zinc. Increasing the silver content of the anodes reduced the lead in cathodes only slightly. More important, the anode scale that was not removed during anode cleaning, entered the electrolyte and contaminated the cathodes with lead. A piping system has been installed to purge the contaminated electrolyte directly back to the leaching section. This has allowed the plant to produce S.H.G. zinc consistently.

Jan 1, 1990

By A Geldenhuis, M Hagger, J Maree

Disposal of mine water is a worldwide problem occurring in the coal and gold as well in the metal ore mining areas. Since southern Africa is a (semi) arid region, mining effluents should be treated to qualities such that they can be used for agricultural purposes or that they can be discharged in river system. Studies have shown that partly treated acid mine water can be used for irrigation. A copper mine in Botswana plans to use 5 M/d of treated mine effluent for the irrigation of agricultural product. The results of this study showed that when applying the biological sulfate removal technology the produced sulfide precipitated the metals in the mine effluent, such as nickel, Zn and Mn, to metal sulfide (MeS).

Jan 1, 2003

By J P. Bolduc, P. E. Pelletier

Preceded by brief general considerations such as the development of the mining industry in. the Province of Quebec, the choice of plant location, the types of problems studied etc., the paper gives a complete description of this new research and treatment center for metallic, non-metallic and asbestos ores. Facilities for carrying out operations in the three sections of the plant -the sampling section, the ore treatment section and the asbestos section -are fully discussed as well as laboratory facilities for (a) the preliminary testing of ores prior to pilot plant treatment and (b) the grading and testing of asbestos fibre. AT THE beginning of the century, the annual value of the mineral production of the Province of Quebec stood at the $2,500,000 level. Twenty-five years later, it was just under $24,000,000. In 1950, half a century later, it was slightly in excess of $200,000,000. But in 1959, in the span of only nine years, it

Jan 1, 1962

By P. G. Semple

For the last four years, the Kilborn Group of Companies (Kilborn) has been involved in several major projects in the CIS. These projects include the Kumtor Project, the Kubaka Gold Project, the Kazgold Project, the Aginskoe Project and the Jerooy Project. These projects are all in various stages of detailed engineering and construction. In this paper, Kilborn will discuss our experience in the CIS and share some insight into project development in this geographic region.

Jan 1, 1996

By AIME AIME

THE annual meeting of the A.I.M.E. was fittingly closed with a joint meeting of the Metropolitan sections of the four National societies on Feb. 18, at which this subject was adequately discussed by leading engineers before an audience that completely filled the Engineering Auditorium. The large amount of publicity that has been given the Diesel electric loco- motive, and the often garbled reports of its performance and possibilities that have been circulated, makes it particularly fitting that the facts should be given the profession as determined by those who have aided in developing and operating this latest form of prime- mover in railroad operation. C. A. Stein, general manager of the Central R. R. of New Jersey, opened the meeting with a discussion of the problem of electrification, and the relation of the short haul, switching, and terminal service to heavy electrification. Referring directly to the problem of the Central R. R. of New Jersey, some subtitution for the steam locomotive is necessary within the city limits of New York because of local ordinances against the smoke nuisance. While the improvement in the design of the steam locomotive has been marked-the efiiency today is over fifty times that of the locomotive of 100 years ago-it has now probably reached the point of maximum perfection. If anything, it is open to the criticism of having Coo many appliances to get out of

Jan 1, 1926

By Balladares V. Eduardo

Most of the arsenic contained in copper concentrates is removed in the gas phase during the smelting and converting processes and, according to recent environmental regulations, it is required to fix it in a solid stable form. In this regards, ferric arsenate has been reported as thermal and aqueous stable compound. Therefore, various alternatives for treating gas containing arsenic were considered in this work. From data obtained at laboratory scale on fixation of arsenic using iron oxide, a new process to treat copper concentrates containing arsenic was evaluated. The effect of temperature, oxygen potential and the sample porosity on the fixation of arsenic contained in a gaseous stream was studied, and the iron oxide converted into ferric arsenate was up to 10%. The obtained results suggest a new alternative for gas treatment with an interesting and attractive technical development. The arsenic was retained as ferric arsenate with thermal and aqueous stability, and it allows a safe disposal keeping the environmental restrictions. The kinetics parameters are used to scale up laboratory results to higher processing rates.

Jan 1, 2005

By T. Wulleman, M. Ansriou

Integrity testing is a primary quality control check on a product that is for the most part not accessible to visual examination. Their cost can be expensive when using direct methods of inspection (like coring a pile) or more economical when using indirect methods (e.g. acoustic testing). All indirect methods operate by “inference” which means that they do not directly measure the defect of integrity. Indirect methods measure the variation of physical values (temperature, impedance, speed, ect.) correlated to the integrity of the pile allowing the detection of integrity defects, although these methods do not allow for the characterization of the defect. 1. INTRODUCTION Cast-in-place piles are particularly prone to integrity defects. The reasons for this are multiple, including lack of high quality of contractor workmanship, experience and supervision necessary in construction, variable soil and groundwater conditions on site, etc. Furthermore, visual inspection of the finalized pile is usually impossible. Therefore, special care has to be taken both during the execution process and during the subsequent quality control campaign to detect any defects of executed piles. Today, a lot of methods do exist to assess pile integrity. It is thus essential to understand the mechanism governing those devices to both make an engineering choice of the pile integrity testing method and to interpret correctly the provided results. 2. QUALITY IN PILE FOUNDATIONS 2.1 Pile anomalies A pile having an anomaly is a pile which has a different behavior from what is normally expected. The presence of a pile anomaly does not necessarily imply that a pile cannot be used for its intended purpose (Gordon & Chapman 2004). An anomaly can be considered as a defect, or a “performance” depending on the ability of the pile to fulfil the following three criteria (3C): C1 - Meet the Service Limit State (SLS) requirement and support the proposed working load without settling more than admissible by the superstructure ; C2 - Meet the Ultimate Limit State (ULS) requirement and carry a specified load with an adequate factor of safety against failure ; C3 - Remain durable throughout the design life of the structure such that the pile is not affected by time dependent activities (chemical attack, corrosion of steel reinforcement, ect.), which would jeopardize its ability to maintain its compliance with the first two criteria.

Jan 1, 2019

By Peter Cali, Wesley Schmutzler

"The Deep Mixing Method (DMM) was employed to raise and support the LPV (Lake Pontchartrain and Vicinity) -111 Levee in New Orleans. Even using innovative technologies, the tight schedule to achieve the 100 year elevation by June 1, 2011 was a daunting endeavor. The size and scope of DMM proposed for LPV-111 was on a scale never attempted outside of Japan. Over 1.65 million cubic yards of DMM was installed. LPV-111 is adjacent to the Bayou Sauvage Wildlife Refuge, which is the largest urban National Wildlife refuge in the United States. By utilizing DMM to control settlement and improve stability of the taller levee, side slopes were steepened from the conventional 1V:4H to 1V:2.85H, thus avoiding encroachment into the Bayou Sauvage and reducing the amount of clay needed for the completed levee. The COE utilized Early Contractor Involvement (ECI) for this contract. The ECI process allowed for input from the DMM contractor, TREVIICOS South, in order to optimize equipment resources and material requirements. This paper gives an overview of the extensive DMM requirements for LPV-111 and explains the benefits of the ECI process.IntroductionDuring hurricane Katrina the levee that constitutes LPV-111 was overtopped and breached in several locations. The United States Army Corps of Engineers (USACE) was presented with the task of increasing the level of the flood protection around New Orleans after Hurricane Katrina to the 100- Year hydraulic grade - the level of protection that provides risk reduction from a storm surge that has a 1% chance of being equaled or exceeded in any given year - and the firm project completion deadline was June 2011.LPV-111 is located in East New Orleans and a large portion of the levee is adjacent to the Bayou Sauvage National Wildlife Refuge. The levee could not encroach on this area. This provided a limited footprint for the levee and made construction of conventional levee difficult, if not impossible. The total length of the project was 5.3 miles. Included in the project was the rehabilitation of one main pumping station and one smaller pump station for water management within the refuge. Short sections of “T” wall were used at the tie in at the Lake Borgne Surge Barrier, the main pump station and the CSX Railroad crossing"

Jan 1, 2017

By R. E. Cuthbertson

AN early appreciation by the management that Climax ore presented a challenging problem of economic concentration was responsible for the establishment, in June 1926, of an ore-testing department at the experimental plant of the Colorado School of Mines at Golden, some ninety miles from Climax. An engineering office was later organized in the same community for the design of all ore-treatment units erected at Climax during the period of rapid growth. Work of the ore-testing and design staffs was effectively co-ordinated under a common head. The primary reason for having the ore-testing and plant design departments in Golden, was to place these activities under the able supervision of A. J. Weinig, consultant for the Climax Molybdenum Co., and director of the experimental plant. A secondary consideration was the availability of excellent facilities for research in ore dressing in a highly favorable environment. Concentration of molybdenite by flotation from an ore of simple mineral composition does not appear, superficially, to present a serious problem in ore dressing but experience belies this apparent simplicity. The molybdenite content of average Climax ore is low and it is finely

Jan 1, 1946

By JOHN LANE DYNAN

HE Tonopah Extension property consisted originally of three claims, with an area of 38 acres. In 1902 a shaft, now known as No. 1, was started near the eastern end of the property, close to the Tonopah Mining Co.'s boundary line, in the. andesite cap rock' which covers the ore-bearing formations in the western end of the Tonopah district. A short distance below the 60-ft. level, the orebodies pinched out, although the veins continued. This shaft has not been used since 1916. Before 1910, the production was small, coming mostly from small shoots of high-grade shipping ore. In that : year, the, company started its 30-stamp mill and cyanide plant; the mill was later enlarged to 50 stamps, with a corresponding increase in the cyanide-plant capacity, which brought the capacity of the mill up to 350 .tons per day. The total production of the mine to Oct. 1, 1920, is 871,177 tons of ore, from which was recovered 15,267,216 oz. of silver and 156,241 oz. of gold.' This makes an average recovery per ton of 17.5 oz. silver and 0.179 oz. gold. The average price received for silver since' the beginning of operations is 65.87 c. per oz., and the average value recovered from the ore-'is $15.25. The area of the property has been gradually increased by purchases and consolidations of adjoining ground until it is now 647 acres. A new shaft, known as No. 2, was started in 1912, 1600 ft. west .of No. 1, and in the following year a crosscut on the 750-ft. level of this shaft resulted in the discovery of the. Murray Vein system, from which the greatest prosperity of the mine has come. This vein, with its related veins,

Jan 1, 1921

By T. B. Counselman

WHEN one thinks of Minnesota iron ore, one thinks of big open pits, where high- grade ore is simply scooped up with a power shovel, loaded into cars, and hauled away for shipment to the blast furnace. On the western end of the Mesabi range, however, are large tonnages of iron ore which contain too much silica to be used directly in the blast furnace, and these ores must first be concentrated to a purer form. The Mesabi range is about 100 miles long and a maximum of 3 miles wide. The iron formation, which in its unaltered form is called taconite: consists of a banded iron- bearing chert. Where the high-grade ore bodies occur, these have resulted from folding and cracking with sub- sequent leaching out of the silica, leaving the iron oxide behind. The big open pits and the underground mines are situated in these concentrations.

Jan 1, 1941

By Andrew Thallisson de Souza

Os aços inoxidáveis ABNT da série 300 são ligas austeníticas Fe-C(< 0,08%) - Cr(18 a 20%) - Ni(8 a 10%) são muito aplicados, pois apresentam alta estampabilidade, alta soldabilidade, boa resistência à corrosão uniforme em vários meios corrosivos, no entanto, sofrem corrosão localizada (pites, corrosão sob tensão, fresta e corrosão intergranular). Os aços inoxidáveis da família UNS S32304, têm 23%Cr e 4%Ni. Por terem teor de carbono inferior a 300ppm (0,03% em massa) são resistentes à corrosão intergranular, sofrem pites e corrosão sob tensão (CST). Devido ao alto teor de cromo, o aço UNS 32304 apresenta boa resistência à corrosão uniforme, sendo que na corrosão por pites o mesmo apresenta um comportamento melhor que os aços ABNT 304 (sem Mo) e ABNT 316 (com Mo), de acordo com o Número Equivalente de Resistência ao Pite (PREN). O PREN dos aços UNS 322304 é 26, e para os aços ABNT 304 e 316 são 18 e 25, respectivamente. Este trabalho caracterizou os diferentes aços inoxidáveis química, metalográfica e eletroquimicamente em meios contendo íons cloretos. A partir de ensaios de caracterização eletroquímica, por polarização potenciodinâmica, verificou-se que o aço ABNT 304 apresentou potencial de pite inferior aos aços ABNT 316 e o UNS 32304, em soluções aquosas contendo 3,5% (massa) de NaCl. Verificou-se que estes aços sofreram CST empregando-se ensaios de deformação (corpo de prova em U) e carga constante (corpo de prova de tração liso) nos eletrodos em soluções aquosas contendo 42% (massa) de MgCl2 na temperatura de aproximadamente 143°C. Salienta-se que o comportamento em CST do aço ABNT 304 foi inferior aos demais. As amostras ensaiadas foram caracterizadas fratograficamente (macro e microfratograficamente - empregando-se microscopia eletrônica de varredura). Os corpos de prova que sofreram CST apresentaram facetas de clivagem e “marcas de rios”, características da fratura frágil.

Aug 17, 2017

By Moacir Kuwahara

Nesta pesquisa, foi desenvolvido um material compósito com matriz poliéster, reforçadas com fibras de bambu e de sisal. As fibras de bambu foram extraídas do próprio campus da UFPA e as fibras de sisal obtidas no comércio de Belém. As fibras foram submetidas ao equipamento moinho granulador, com a finalidade de otimizar o corte das fibras, visto que, pelo processo manual gasta-se um certo tempo para obter uma quantidade necessária, para fabricação dos compósitos. E os comprimentos obtidos variaram entre 5 a 15 mm. Os compósitos foram produzidos utilizando-se o menor nível possível de processamento tecnológico nas etapas de fabricação. Foram fabricados 8 (oito) corpos de prova para fração mássica definida com a seguinte proporção 3,90%; a fabricação foi realizada por moldagem manual, usando resina poliéster insaturada com a proporção de agente de cura/resina de 0,33%. As fibras de sisal e bambu foram submetidas a ensaio de tração, determinação da massa especifica e avaliação microestrutural, por microscopia eletrônica de varredura (MEV).

Aug 16, 2017

By Fábio de Oliveira Braga

Um sistema de blindagem multicamada consiste de uma camada frontal de cerâmica, uma camada intermediária de fibras sintéticas ou de material compósito, e uma camada posterior de um metal dúctil. Recentemente, há o interesse em substituir as fibras sintéticas por fibras naturais, por suas propriedades adequadas, menor custo e peso. O objetivo deste trabalho é avaliar o desempenho de compósitos de matriz poliéster reforçados por fibras naturais de Curauá em blindagens multicamada. Placas com 0, 10, 20 e 30% vol. de fibras integraram a blindagem que sofreu impacto balístico com munição 7.62 mm, e o dano foi avaliado pela indentação característica em plastilina e por uma análise microscópica das superfícies de fratura. Foi mostrado que a blindagem resiste ao impacto balístico, atendendo à norma NIJ-0101.04 para o nível de proteção III. Além disso, as fibras de Curauá são responsáveis por manter a coesão do compósito após o impacto balístico, e o compósito por dissipar parte da energia do projétil por mecanismos como delaminação, trincamento da matriz, fratura e descolamento das fibras.

Aug 16, 2017

By Bruno Augusto Batista Ribeiro, Felipe Terra Elias, Wagner Moulin Silva

In the pyrometallurgical production of copper from its sulfides, converting in the Peirce Smith (P-S) Converter is still the most widespread method to obtain white metal and blister copper from the matte. Despite the fact of being a century-old process, it is still possible to achieve improvements in the process, by the use of modern tools, one of the most valuable being numerical calculation and computer-aided simulation. The present study presents three cases in which the angle for the gas injection and the number of working tuyeres are changed during the slag blow phase of the converting process. It was noticed that a decrease of the number of tuyeres, followed by an increase in the injection gas velocity, results in improved reaction volume and less stress to the refractory lining. However, an increase in the amount of copper lost to the slag as oxide is likely to occur.

Jan 1, 2014

By Michael Frawley, Deana Ruud, Jessica Turner

Technology is allowing for new ways to mitigate risk associated with subsurface exploration and unanticipated subsurface conditions during construction. Unanticipated subsurface conditions have the potential to force delays and cost overruns on even the best-managed and well-executed projects. For more than a century, geotechnical professionals have documented the location and conditions encountered in hundreds of thousands of subsurface borings. Utilizing processes for compiling and managing data, owners can streamline site selection and receive access to a conceptual geotechnical model before field exploration takes place. Digitizing historical subsurface information allows for creation of an interactive, web-based platform combining publicly available information and culminating with the opinion of a local, experienced geotechnical engineer. This connectivity aids in the reduction of risks associated with unknown conditions on prospective project sites. Through this conceptual project study, we demonstrate how a project owner would be able to use a comprehensive desktop study to review the expected conditions prior to making a purchasing decision. Following the purchase, the expected conditions would be confirmed through traditional methods, confirming potentially problematic site conditions and the associated risks. INTRODUCTION Preliminary project planning is often based on assumptions made by the design team with regards to site suitability. After due diligence, site development is traditionally initiated by the owner or the owner’s representative when engaging a geotechnical engineer to perform a thorough subsurface exploration at a site. The data generated by the geotechnical engineer’s analysis of the site is required to design foundations, pavements and earth retaining structures and move the project from concept into design. This necessary, subsurface exploration can be time consuming, intrusive, and require significant resources, often when resources during construction seasons when resources are most limited. By leveraging historical data generated from previous subsurface exploration, a more thorough analysis of project risk can be developed prior to mobilizing a drill rig. Ultimately, preliminary budgets and designs are more accurate and geotechnical field exploration is more strategic. The geotechnical engineer’s role transforms from raw exploration and analysis to confirmation of anticipated conditions.

Jan 1, 2019

By Saulo Morais de Andrade

Aços de alta resistência mecânica têm sido aplicados largamente no setor automotivo para redução do peso veicular e aumento da segurança. O aço de alta resistência e baixa liga (ARBL) é um dos exemplos de materiais utilizados em peças estruturais e de reforço dos automóveis. Nesse trabalho foi avaliado o efeito das temperaturas de bobinamento e encharque nas propriedades mecânicas do aço ARBL laminado a frio microligado ao nióbio, com limite de escoamento mínimo de 410 MPa, produzido em escala industrial. De uma forma geral, foram observados queda nos limites de escoamento e resistência, e aumento do alongamento total do aço com a elevação das temperaturas avaliadas. Foi observado que a temperatura de encharque apresentou uma maior influência, ocasionando uma maior queda na resistência mecânica. Como não foram verificadas alterações significativas no tamanho de grão ferrítico, as variações nos valores de propriedades mecânicas podem ser atribuídas ao coalescimento de precipitados.

Aug 16, 2017

By Livia Mara Candido

As reservas de minério de ferro, apresentam tendências de menores teores de Fe, tornando maior a necessidade da redução da fração granulométrica inferior a 150µm, o que torna o processo viável tecnicamente por meio concentração. O método mais comum utilizado é a concentração através da flotação. Flotação é uma técnica de separação baseada na afinidade das espécies minerais com as moléculas de água. Na flotação reversa de minério de ferro, utilizam-se agentes que reforçam o caráter hidrofílico das partículas de Ferro, chamados de depressores. O mais comumente utilizado é o amido de milho em forma de solução, gelatinizado com a adição de soda cáustica. Dentro desse contexto e afim de aumentar o poder de gelatinização do depressor, foram realizados através do planejamento fatorial estatístico, ensaios de flotação em bancada, com diferentes concentrações iniciais e finais de amido de milho presente na solução e ainda a relação de amido/soda para avaliar o impacto sobre a recuperação metalúrgica da flotação, concluindo-se que recuperação metálica foram fortemente influenciados pela concentração inicial da solução de amido.

Oct 30, 2017

By Luis Acainas Caballero, Karl Hoen, Stephan Krämer, Christoph Klein

The situation of the steel industry is still challenging. Worldwide overcapacities have an impact on profitability. More than ever, the point at SMS group is to provide the steel industry with flexible and profitable technologies and systems over the whole process chain. One example for that is the thin slab casting and rolling technology and, in particular the CSP® technology (Compact Strip Production), being well established for hot coil production. From its introduction in 1989, CSP® technology has been continuously further developed. Today, on a CSP® plant, the full range of high-quality steel grades can be produced with tightest geometrical and metallurgical tolerances under optimal economic conditions. With the introduction of semi-endless rolling and, as a further step, the endless rolling process, the product range for thin and ultra-thin products has been further enlarged, allowing for the production of hot rolled coils with a thickness of 0.8 mm for low carbon steel grades. Also high-strength steel grades may be produced with gauges below the minimum product thickness that can be achieved in a conventional-type hot rolling mill. Another step in the further development of CSP® technology is digitalization. In December 2016, the CSP® plant of Big River Steel (BRS), located in Arkansas, USA was put into operation. It is the first learning steel mill in the world. The CSP® plant of BRS comes with innovative technologies, providing impressive operational results right from the beginning.

Oct 1, 2019

By Willy Ank de Morais

Para se determinar as propriedades mecânicas de uma junta soldada torna-se necessário conhecer as propriedades mecânicas do metal de adição decorrente de um processo de soldagem. O objetivo desse trabalho foi verificar as propriedades mecânicas de uma solda MAG elaborando e qualificando um procedimento de soldagem. Para isso foi utilizado quatro ensaios mecânicos: tração, macrográfia, micrografia e dureza. Foi estipulado o limite de escoamento, de ruptura, o alongamento e a estricção; macrográfico, determinou-se, a olho nu, a zona fundida, a zona de ligação, a zona termicamente afetada e o metal de base; micrográfico, tração, definiu-se os componentes microestruturais da solda e do metal de base; dureza e foi estabelecida a tenacidade da solda e do metal de base.

Aug 16, 2017