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This paper will review some of the work conducted in the past at the Dynamic Effects Laboratory to examine the use of stress waves and fracture mechanics in understanding dynamic fracture and fragmentation in blasting applications. Along the way, we will use photoelasticity and high-speed photography to better understand the mechanisms of fracture and fragmentation.CITATION:Fourney, W L, 2015. The role of stress waves and fracture mechanics in fragmentation, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 27–40 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Montaser S. EL Salmawy, Takahide Wakamatsu, Eishi Kusaka

"The effect of ethoxylation of long chain alcohols on the quartz and feldspar flotation behaviors was investigated for surfactants of the octylphenol polyoxyethylene family. The tests were carried out with an average of 7.5 (Triton X 114), 9.5 (Triton X 100), 30 (Triton X305), 40 (Triton X 405) and 70 (TritonX 705) oxyethylene units. Electrokinetic and flotation studies on quartz have shown that at low pH values, quartz could be floated with polyoxyethylene octytlphenols. The possible mode of adsorption of these nonionic surfactants may be suggested to be due to hydrogen bonding between the oxygen of ether and hydrogen in the free hydroxyl groups on quartz surface. It was anticipated that the selectivity between quartz and microcline would decrease as oxyethylenic chain length increases.Electrokinetic methods were used to elucidate the mechanism of surfactants adsorption and to correlate these findings with the optimum flotation conditions. The polymeric surfactants would reduce the negative values of zeta potential of quartz while the reverse is true for feldspar. After treatment of microcline with HCl, its electrokinetic behavior in the presence of Tritons X surfactants became similar to that of quartz.The obtained results would suggest that separation of quartz from feldspar using nonionic surfactants of octylphenoletoxylated alcohols having shorter oxyethylenic chain length at low pH could be achieved"

Jan 1, 2003

By Martha Gross, Amanda Wachenfeld, Brian Keaney, Jean-Michel Charpentier, Frank Perrone

The Hampton Roads Bridge-Tunnel (HRBT) Expansion widens the existing four-lane bridgetunnel corridor to eight lanes through construction of two parallel tunnels, interstate widening, and bridge expansions. As part of the design-build contract, a supplemental geotechnical investigation was completed to support the design. The investigation for the subaqueous tunnel segment consisted of over 48,400 linear feet of drilling and 7,100 laboratory tests. This paper discusses the challenges of planning and executing a large-scale geotechnical investigation for underground works in a marine environment and the use of big data for effectively managing, interpreting, and transmitting data to the design-builder consistently throughout the investigation.

Jun 23, 2024

By D. Milne, P. Germain, G. Sauriol

"The practical determination of optimum stope geometry has, until recently, been an art relying primarily on experience at a given operation. Due to the complex and variable nature of rock masses in situ, stopes are often designed either very conservatively, resulting in excess development, or non-conservative resulting in excessive dilution and, in some cases, in loss of ore reserves.The Geomechanics group of the Mining Technology Division, Centre de Recherche Noranda, uses a combination numerical modelling and empirical design techniques to optimize allowable stope geometries. The above methodology allows the optim ization of stope geometry for varying rockmass classifications within an operation or between different operations. Such techniques require the development of a thorough geotechnical database at each operation and are best used when calibrated to the specific operation through back analysis.This paper discusses the above optimization techniques in light of specific examples from the Noranda Group. The design methods, limitations and results are discussed.INTRODUCTIONMine design has traditionally referred to production planning, general facility layout, (i.e. ore passes, crusher stations, main haulage drifts, etc.) and ventilation design. The dimensioning and sequencing of the stopes and pillars, however, has been almost solely based on trial and error and precedent practice.More recently, numerical stress analysis has received much more attention as part of the design process. It is common now at many operations to look at the effect of proposed stope layouts and sequences on stress redistribution through the surrounding mine workings. Through calibration of actual stope and pillar behaviour in situ, one can then relate the model predictions to support requirements, safety problems, etc."

Jan 1, 1989

By L. M. Oshinowo

The incorporation of advanced analysis tools, such as CFD, into the process plant design process has become possible through advances in commercially available computational fluid dynamics software and faster computers. Multiphase modeling is now typically employed in the design phase of process plant design at Hatch. The multiphase models include Lagrange-Euler and Euler-Euler treatment of the multiple phases. Additionally, mixture models with interface-sharpening algorithms are applied to the prediction of free-surface flows in complex geometry. CFD is applied to applications where traditional design rules are not applicable. The additional rigor of CFD modeling in 2D and 3D allows process engineers to come closer to realizing true virtual plant design. The objective of this paper is to outline the benefits and pitfalls in the application of multiphase modeling for rigorous design. Several application examples in the hydrometallurgical field will be presented.

Jan 1, 2005

By J. Hadjigeorgiou, J. Wesseloo

Mining companies employ a multitude of risk management tools. The effectiveness of these tools for decision-making and communicating risk has not been addressed. This paper investigates the use of verbal probabilistic expressions in communicating geomechanical risk. Analysing survey data obtained from a group of mining geomechanics professionals, it identifies limitations of common probabilistic expressions. The paper concludes by making specific recommendations to avoid the use of certain expressions that may result in increased uncertainty, thus compromising the use of risk management tools.

Jan 30, 2026

By Steven A. Fechner

In 1991 and 1992, the Bureau of Mines completed chromium, platinum-group metals (PGM), and tin investigations, and started indium, manganese, titanium, and vanadium investigations in Alaska. These studies were done as part of the Site Specific Minerals Investigations project. As a result of this work, the Bureau found PGM-bearing composite plutons in the Yentna River area of the Alaska Range, which are chemically similar to composite plutons in other parts of the Alaska Range and to Ural-Alaskan type complexes. Previously unknown chromium and PGM occurrences were found in the western Brooks Range. A compilation report on the Bureau's chromium and PGM investigations in the western Brooks Range was also published. Indium was found in anomalous concentrations at the Lost River tin deposit. Small occurrences of manganese were located, mapped, and sampled in the Wiseman and Chandalar quadrangles, and in the Liberty Falls, Prince William Sound, and Homer areas. Tin occurrences in western Alaska were summarized in three Bureau open file reports. The beaches near Cape Yakataga and Yakutat were evaluated for their titanium potential and a sampling methodology was developed. Vanadium investigations included examining streams in the Wiseman and Eagle areas that contained anomalous vanadium values. In the Eagle area, high vanadium, uranium, and copper values were found in the basal layers of the Road River formation.

Jan 1, 1994

By Shusen Cheng, Kun Yan

A three-dimensional mathematical model of hot blast stove pipe shell has been established and used for analyzing the stress distribution and deformation. The results show that stress concentration happens along the intersection line of hot blast main and the hot blast manifold. There is no plastic deformation on the whole pipe region. The shell near the intersection elongates along the vertical direction and shortens along the horizontal direction, and deforms into an oval. The shell of hot blast main rises up, and inclines upward around the end of hot blast main. The hot blast main moves away from the hot blast and the displacement near the middle region is larger, the main deforms into an arch on horizontal surface. The deformation of shell may form a gap between shell and refractory inside and damage the security and stabilization of hot blast stove piping.

Mar 1, 2017

By Javankhoshdel Yacoub

Piles are often used to reinforce slopes as they increase the available restoring force when calculating the factor of safety against sliding. In this paper, a 3D model of a slope containing multiple modes of failure is reinforced using pile elements. The results of the 3D Limit Equilibrium analysis containing piles are obtained using a newly introduced coupled approach which combines the results of finite element analysis (to obtain the displacement of soil along the pile) with the traditional limit equilibrium iterative formulation. The multiple modes of failure are obtained using the novel Multi-Modal Optimization (MMO) metaheuristic method which adapts the Particle Swarm Optimization (PSO) method to search for multiple local minima in a single slope model.

Oct 1, 2022

By I. Gaballah

Decontamination of synthetic solutions of PbC12 containing 10, 100 and 1000 ppm of lead, using chemically treated barks had been studied. The percentage of !cad cations' removal from solutions depends upon the pH and the initial concentration. About 99 % of the initial lead content can be removed at pH of about 3.5, 5.5 and 6.5 for initial concentrations of 10, 100 and 1000 ppm respectively. The maximum retention capacity of the treated bark is about 83 mg of lead per gram of modified bark. Bark loaded with lead had been analyzed by Infra Red spectroscopy. It seems that lead reacts with hydroxyl groups of the phenolic constituents of the bark. On the other hand, the removal of a lead cation by the bark leads to the release of two H+. This seems to show that the removal of lead could be interpreted as an ion exchange with hydrogen belonging to the hydroxyl groups of the modified bark.

Jan 1, 1994

By W. W. Simpson, W. L. Staker, R. G. Sandberg

The Bureau of Mines investigated selective extraction of Au and Ag from a low-grade Au ore containing Hg. Gold and silver were extracted from the ore in cyanide slurries, and Hg extraction was suppressed with sodium or calcium sulfide. Maximum Au extraction and minimum Hg extraction were obtained using solutions containing 17 kg NaCN/t of solution (0.34 lb NaCN/st). Increasing the cyanide concentration increased Hg extraction without increasing Au extraction. Mercury extraction from the ore was suppressed with 0.5-2.9 kg CaS/kg Hg (0.5-2.9 lb/lb) in the ore. Gold-to-mercury ratios of 100:1 to 400:1 were obtained in the leach solution, and on the activated carbon in a CIP circuit.

Jan 1, 1985

"One of the corporate values mentioned by many companies deals with respect for people. This paper discusses one aspect of this value, namely, the need for clarity of accountabilities and authorities. The job of the manager in achieving this goal is analyzed and the benefits of enhancing the manager-employee conversation outlined. IntroductionCorporate values usually refer to the standards of behaviour that the leaders of the organization expect of all employees, including themselves, in carrying out their duties. Terms such as integrity, respect for the individual, continuous improvement, continuous learning, teamwork, speed, and innovation are quite common. The company-specific values are typically developed by the top executives of the company, and then tested with a broader group of employees. Where the process works, employees have a good understanding of what behaviour is expected of them in doing their work, in making difficult decisions, and in interacting with others.Having spent considerable time in his career investigating and studying the management systems at over 50 of the most successful companies in Canada, the United States, Europe and Japan, the author has had the opportunity to visit organizations such as Hewlett-Packard, 3M, Xerox, Intel, Toyota, NEC, Komatsu, British Airways, and Eastman Chemical. These experiences, together with the work of many other researchers, including the work of Dr. Elliott Jacques, have helped significantly to form the thoughts expressed below.Rather than reviewing the creation of corporate values and their deployment through the organization, these remarks focus on issues over which managers and employees have some control. The value in which managers can have significant impact deals with people and the respect shown them in the workplace. The component of respect to be emphasized is to be clear about expectations or accountabilities for oneself and the people who report to you, and to ensure that personal authority matches those expectations."

Jan 1, 1999

By Ronald P. Wright

ARAMIDS UNDERGROUND COAL MINING

Jan 1, 1993

By Paul M. Tyler

Graphite occurs in many places in the United States, but previous to 1914 the domestic production amounted to only 15 to 20 per cent of the natural graphite consumed in this country. Including artificial, graphite, the proportion was about 25 per cent. During the World War the production of both natural and artificial graphite increased until, in 1918 it, contributed more than one-half of the available supply, and since 1919 the proportion has not fallen below 40 per cent. Except during the war period, however, this apparently increasing independence has not been due to any large increase in production from domestic mines. It simply reflects a larger output of artificial graphite and reduced imports of Ceylon lung and chip, grades which have never been produced in substantial quantity in the United States. DOMESTIC DEPOSITS3 American graphite deposits, though numerous and often large, are characteristically low-grade. They constitute an abundant source of potential supply, but in normal times they have proved relatively costly to work, and even at the same price the various products have never been able wholly to displace certain imported qualities, notably crucible grades from Ceylon and pencil graphite from Mexico.

Jan 1, 1929

By T. Ogasawara, J. P. Barbosa, A. J. Monhemius, F. T. Da Silvia

A thermodynamic analysis of the sulphation of rare-earth phosphates and the water-leaching of rare-earth sulphates was used to guide experimental work on the sulphation and leaching of concentrates from Pitinga. It was concluded that the sulphuric acid digestion of xenotime is technically feasible and could be used industrially to produce yttrium and other rare-earth oxides. Yttrium extractions of more than 90% were obtained by digestion at 503 K for 4 h at an acid:concentrate ratio of 2:1 with particle size -0.053 mm. The apparent activation energy at temperatures less than 473 K, as determined from the Arrhenius plot, was 11.0 kJ/mol, indicating that the reaction is controlled by the diffusion of the reactants or products through the sulphate layer

Jun 19, 1905

By Saulo Brinco Diniz

As ligas de alumínio da série 7XXX são largamente utilizadas no setor aeronáutico devido sua alta razão resistência mecânica / densidade. O que proporciona uma alta resistência mecânica para as ligas da série 7XXX é a adição de elementos de ligas e tratamentos térmicos adequados, como por exemplo o T7351. Este trabalho teve como objetivo, estudar a evolução microestrutural de uma liga de alumínio 7475-T7351 processada por laminação convencional a temperatura ambiente, e posteriormente submetida a tratamentos térmicos de recozimento para recristalização. De acordo com os resultados apresentados, a amostra que foi submetida ao tratamento térmico de recozimento para recristalização a temperatura de 500ºC durante 15 minutos recristalizou, enquanto que a amostra que foi tratada a 350ºC durante 1500 minutos teve coalescimento dos precipitados.

Oct 30, 2017

By Noan Tonini SImonassi

A indústria da construção civil e a que mais absorve mão-de-obra no Brasil, com uma significativa participação no PIB, da ordem de 15%. Em contrapartida e ainda apontada como uma grande geradora de resíduos, que variam em função da matéria-prima utilizada e também da mão-de-obra desqualificada. Dentro desta faixa de mercado, o número de edificações que empregam blocos cerâmicos como elementos de vedação ou estruturais, é bastante expressivo, principalmente pela facilidade de produção destes artefatos no Brasil. Neste trabalho buscou-se avaliar a influência dos blocos cerâmicos, quando utilizados fora de norma, em uma determinada edificação, formada por um prédio residencial multifamiliar que estava sendo construído no município de Itaperuna, RJ e se encontrava nas etapas construtivas de vedação e revestimento, cujas perdas e causas associadas foram identificadas e quantificadas.

Oct 30, 2017

By Suprakash Gupta, Pawan Kumar Yadav, Deepak Kumar, Debasis Jana

Draglines are extensively used in Indian mines. A dragline has more than hundreds of components, and it is complex in design. This study involves the evaluation of the reliability of a draglines system using a Bayesian network (BN) model mapped from a fault tree. Based on the BN inference, the reliability estimation, the diagnosis, and the sensitivity analysis are performed. In this paper, the overall reliability of the dragline is estimated as well as the contribution of the subsystems or components in the overall reliability evaluation is presented. The results showed that the three subsystems of the dragline, namely, the dragging mechanism, electrical auxiliary subsystem, and swing mechanism, have the lowest reliability (82.17%, 87.98%, and 91.30%, respectively) after an hour of operation. The overall reliability at the first hour of machine operation is estimated to be 62.03%. The study may provide a reference for future work related to the dragline machine’s reliability design and maintenance.

Jan 14, 2023

By Jezuele Milanez

No ano de 2016 foi desenvolvido um importante projeto na Gerdau Mineração relativo ao pilar produtividade: a consolidação da Manutenção Compartilhada na Gerência do Beneficiamento Mineral. A Manutenção Compartilhada, ou autônoma, é um programa que capacita os colaboradores a realizar manutenção, pequenas inspeções, além das operações das plantas de beneficiamento, através da criação da carreira de Operador Mantenedor em sua estrutura. Alinhado com o mapa estratégico da unidade, o projeto teve por objetivo consolidar um novo conceito de estrutura de carreira das equipes de Operação e Manutenção nas plantas de beneficiamento. Buscando maior simplicidade, aumento da produtividade e capturando as oportunidades de sinergia entre as equipes de Operação e Manutenção, o projeto reduziu significativamente o custo de pessoal e resultou em maior autonomia e oportunidades de crescimento para as equipes envolvidas.

Oct 30, 2017

By Alcio Heitor Somensari

O artigo apresenta um estudo de como um sistema de automação elétrica integrado deve fornecer uma completa visão do sistema elétrico, permitindo que as equipes de operação e manutenção tomem decisões precisas rapidamente após uma falha elétrica. As indústrias esperam que suas subestações estejam sempre disponíveis e ligadas, evitando paradas indesejadas. Para isso, precisam de soluções que recuperem o fornecimento de energia de forma rápida e segura, a um custo mínimo. Proporcionar um ambiente aprimorado na sala de controle para uma rápida solução de problemas e conectar subestações de locais hostis e distantes reduzem não apenas tempo de manutenção, mas também aumentam a segurança das equipes. A norma IEC 61850 nos permite entregar uma solução para um sistema mais intuitivo com acesso rápido a informações que melhoram a supervisão da planta na sala de controle.

Aug 16, 2017