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By A. W. Diedericks

Rosh Pinah Zinc Corporation (RPZC) identified implementing a Mineral Resource Management (MRM) programme at the mine as a strategic incentive. The purpose of the programme is to optimize the economic value of the RPZC mineral resource, over the total value chain of the mine, taking expected macro economic conditions into consideration as well. With Mineral Resource Management still being a relatively young drive in the mining industry, information on the concept is relatively scarce. RPZC had several successes and problems with implementing such a concept and also still has a way to go before a complete Minerals Resource Management approach is implemented at the mine and entrenched as a working culture. The purpose of this paper is to: ?define a systems approach to implementing a Mineral Resource Management programme at a base metal mine ?indicate the specific MRM approaches taken at RPZC ?indicate the expected advantages of implementing a MRM approach ?measure the actions already taken against the systematic MRM approach, and indicate the advantages already captured ?indicate the way forward taking lessons learned into consideration ?indicate proposals to implement the MRM approach in the macro mining environment in South Africa.

Jan 1, 2003

Reduce the danger to personnel and destruction of equipment caused by fires on surface coal augers. Approach: A reasonably priced reliable system which automatically senses a fire and activates dry chemical extinguishers, has been built and field tested. How It Works: Heat sensors mounted in the engine compartment and hydraulic hose areas detect the fire, usually before the operator does. This causes the system to automatically discharge A-B-C class dry chemical extinguisher through a fixed piping system.

Jan 1, 1976

By Beavis FC, Box JC

The important chemical and fluid flow phenomena in heap, dump and in situ leaching are summarised. Published, quantitative models of these processes are critically reviewed, and their potential applications outlined. Comparison between the independent predictions of one of the models and column leach test data reported by others confirms the potential. Some recent developments by the authors in the fields of fluid flow through unbroken ore and modelling of the more complex chemical systems are briefly Described.

Jan 1, 1981

By Mandeep Singh

The smelting of lead ores has been carried out in southeast Missouri for centuries, and modern smelting practices have generated a variety of waste products. Lead blast furnace slag is one such product, which typically contains 10% zinc, 25% iron and 2% lead. This slag has often been stockpiled on the producing smelter site and accumulations have now reached several million tonnes. It is possible that in the near future these slags will be classified by the federal Environmental Protection Agency as hazardous, and therefore there is considerable interest in possible treatment processes to render the slags non-hazardous by removing the offending metallic elements. To ensure that the overall slag processing costs are kept to a minimum, it is imperative that lead and zinc be recovered in a form suitable for sale or further processing. There are two generic routes for processing blast furnace slags and they involve hydro-metallurgical or pyrometallurgical techniques. With hydrometallurgy, the slags would be leached directly and the metal values recovered from purified leach solution(s) by electrowinning. One problem with processes of this type is that the zinc and lead grades of the slags are low and the iron content is high, and thus the economics of metal production are often not favorable. For pyrometallurgical processing (1), it has been shown that the slags can be fumed to produce an oxide dust containing all the lead and zinc, and representing only a fraction of the weight of the initial slag. The oxide dust may then be processed hydrometallurgical to recover zinc and lead.

Jan 1, 1992

By Rodrigo Galves De Lucca

As tendências do mercado são de utilizar tubos com maior resistência e tenacidade para a temperatura de projeto. Resultados obtidos em testes de laboratório para diferentes ordens de produção e graus, a partir de testes de tração de chapas e tubos, juntamente com a quantificação microestrutural, proporcionam uma oportunidade para melhor compreender e quantificar a influência de cada fase sobre o comportamento das propriedades mecânicas do material. A presença de maiores quantidades de ferrita acicular/ferrita poligonal, em vez de ferrita poligonal/perlita, geram um aumento das propriedades mecânicas durante a formação do tubo, bem como uma forma bem definida do comportamento de tensão-deformação, o que é benéfico em aplicações de strain based design.

Aug 8, 2018

By Cassiele Renata da Silva

O presente trabalho trata-se da modelagem por elementos finitos de materiais compósitos reforçados com fibras de carbono utilizando duas teorias: a Teoria da Deformação Cisalhante de Primeira Ordem (FSDT) e a Teoria da Deformação Cisalhante de Ordem Superior (HSDT), com o objetivo de efetuar um comparativo entre ambas no contexto de sua capacidade de predição do comportamento dinâmico, sendo possível avaliar e ilustrar as características de desempenho de ambas as formulações. Além disso, analisando o parâmetro geométrico da espessura das placas compósitas torna-se possível comprovar a limitação de uma das teorias. Os resultados são apresentados na forma de funções de resposta em frequência (FRF’s) onde é avaliada computacionalmente a presença de ruídos nos resultados.

Oct 30, 2017

By Marcelo Lucas Pereira Machado

Os aços APIpossuem as combinações desejáveis de resistência à tração, ductilidade, tenacidade e soldabilidade. A ArcelorMittal Tubarão iniciou o desenvolvimento de bobinas a quente do grau API 5L X80M–PSL2. O comportamento dos aços está relacionado aos parâmetros de temperatura, deformação, taxa de deformação, taxa de resfriamento e tempo entre passes na laminação a quente. Foi feito um estudo do comportamento termomecânico deste aço através de ensaios de torção a quente isotérmicos e comparados os resultados com os modelos matemáticos microestruturais da literatura ajustados para o aço em questão. Determinau-se a tensão e deformação de pico, tensão e deformação crítica e o amaciamento do material e compados com os modelos utilizados.

Aug 8, 2018

By Willy Ank de Morais

O estaqueamento profundo é necessário para obter fundações firmes e confiáveis, mesmo em solos de baixa resistência. Após completar a soldagem entre dois perfis, através do uso de talas, que compõe uma estaca de uma fundação profunda, essa união é inserida, juntamente com o restante da viga, através de uma máquina de estaqueamento. Neste processo a região da emenda pode sofrer choque térmico devido à umidade presente no solo. Este trabalho visa demonstrar a viabilidade da imediata inserção (‘cravação’) no solo de juntas entre perfis de aço ASTM A572 Grau 50, efetuadas através da operação de soldagem com eletrodo revestido (E 7018), simulada através de uma condição de maior criticidade pelo processo de arame tubular.

Oct 30, 2017

By Marcelo Xavier Gonçalves, Rodrigo Jorge dos Santos Arruda, Sergio da Cunha Motta

Em busca de uma solução para a mitigação dos riscos aos quais os empregados da empresa Sepetiba Tecon S/A ficam expostos, redução dos custos, eliminação do consumo de madeira e da utilização do brometo de metila (substância que agride a camada de ozônio, utilizada no processo de tratamento da madeira para exportação), buscou-se inovar o processo de peação de bobinas com eixo horizontal e vertical até 13 toneladas, dando continuidade ao processo iniciado em 2017. Para isso, foi elaborado o projeto que substituiu toda a madeira utilizada na peação (travamento da carga) por cintas com filamentos de poliéster de alta tenacidade e polipropileno homopolímero, tornando o processo sustentável, seguro e mais eficiente.

Oct 1, 2019

By Alessandra Vieira Guimarães

A superliga de níquel 718 é uma superliga endurecida por precipitação, com alta resistência mecânica sob condições extremas e ambientes agressivos. Encontra aplicações como componentes críticos para indústrias aeroespacial, óleo e gas e nuclear. Seu alto teor de elementos de liga promove a ocorrência de diversas fases com consequente impacto nas propriedades. O presente trabalho foca na comparação por análise de imagens na morfologia, fração volumétrica, tamanho médio e distribuição de partículas de carbonetos (Nb,Ti)C após duas rotas de processamento termomecânico. Sua quantidade, distribuição e morfologia podem ter um papel em processos de degradação como corrosão e fragilização ao hidrogênio. Portanto, é importante saber como se desenvolve sob diferentes rotas de processamento.

Aug 16, 2017

By F. J. Perzak

The Bureau of Mines conducted a flammability study of plastic ventilation ducts. Six rigid 16-in-diam fiberglass-reinforced plastic ducts from five manufacturers were examined using laboratory-scale, large-scale, and full-scale fire tests. The laboratory-scale tests included the American Society for Testing and Materials E162 radiant panel test, the E2863 oxygen index test, and the standardized small-scale flammability test (S3FT) developed by the Mine Safety and Health Administration (MSHA), U.S. Department of Labor, and replicated by the Bureau of Mines. Ten-foot lengths of the same ducts were also subjected to a large-scale vertical fire test, and 20-to 30-ft lengths were tested in a full-scale in-mine fire test at the Bureau's Lake Lynn Laboratory mine. The data from the laboratory-scale radiant panel test and oxygen index test indicated that the ducts were fire-resistant, However, five of the six ducts failed the S3FT and vertical fire tests, and four of the ducts failed the full-scale in-mine tests with flame propagation rates that ranged from 3 to 10 ft/min. The results indicate the need for improved fire-resistant plastic ducts. The good agreement between the S3FT re-sults and the vertical and full-scale tests show that the S3FT provides a good indication of the flammability of fiberglass-reinforced plastic ducting under realistic fire conditions.

Jan 1, 1987

By R. R. Hornor, Harry E. Tufft

The purpose of this bulletin is to point out some of the benefits and economies to be derived by selecting, preparing, storing, preserving, and utilizing mine timber more carefully and to give some specific information on certain preservatives and processes suitable for mine timber.

Jan 1, 1925

To alleviate the hazard to personnel and danger to equipment caused by fires on large, mobile vehicles. The Approach: A system which automatically senses a fire at its early stage of development, warns the driver of the danger, and activates fire extinguishers in the zone of combustion, How It Works: The automatic fire protection system utilizes both thermal and optical sensors to detect the heat or light given off by a fire in the area of concern (Fig. 1). The system warns the driver of the hazard and then automatically extinguishes the fire with pressurized S-C class powder. The system can also be activated manually from the operator's cab or from ground level. Further, the automatic sequencing of the system can be manually overridden by the driver if he determines that the fire sensors have malfunctioned to cause a false alarm.

Jan 1, 1974

"D bed, Ky., coaL, washing characteristics RII 5140coking coal, reserves, estimate RI 5037Pa., coal, washing characteristics RI 4834, 4941D bed mine, Ky., coal, washig characteristics"

Jan 1, 1960

By Brian P. Waagner

Construction law in general and the law of deep foundations in particular continues to develop rapidly, particularly in the areas of risk allocation. Public and private owners are increasingly using contractual disclaimers to shift the risk of differing site conditions to contractors, and courts are increasingly willing to enforce these contractual devices. Perhaps also in an effort to control costs, public and private owners are turning to design-build contracting techniques. While design-build offers many advantages over traditional project delivery systems, it does not answer all of the risk-allocation questions that frequently arise. Even in design-build, problems with unanticipated subsurface conditions and defective design are not easily addressed. Finally, developments in electronic commerce present the potential to transform the construction industry.

Jan 1, 2002

By J. F. Wilson

An experimental investigation has been made of gas-driven slug displacements in a system of high gas saturation to evaluate the process for use in a California reservoir. Fluid compositions, temperature, pressure and core permeability duplicated reservoir conditions as closely as possible. The temperature was above the critical of the slug materials. The slug composition required for 100 per cent oil recovery in the linear flow systems was found to agree with that determined from equilibrium phase studies. A qualitative theory for the slug displacement of two-phase systems is proposed and found to be in general agreement with the observed flow behavior. The theory predicts that the length of the reservoir fluid-slug transition Zone will increase with increased initial gas saturation and decrease with increased oil swelling accompanying the composition change from reservoir oil to the critical composition. The precipitation of small amounts of an asphaltic phase during the formation of the transition zone had no adverse effects on the flow behavior of otherwise miscible systems. INTRODUCTION Despite the large number of recent publications relating to oil recovery by miscible displacement, little information is available concerning the behavior of crude oil-natural gas systems at conditions likely to be encountered in field application. The laboratory data reported here were obtained during an investigation of the possibility of using a gas-driven LPG slug in a partially depleted California reservoir. Seven gas-driven slug displacements employing slugs of different compositions and sizes were made in 26- to 27-ft long sandstone cores. The equilibrium phase behavior of the systems was also determined. The features of primary interest in this study are the following. 1. Data were obtained on the displacement of reservoir fluids at reservoir conditions. 2. A high gas saturation existed in the long cores at the start of the displacements. 3. The temperature of the studies was above the critical of the slug materials. 4. A comparison between the flow behavior and equilibrium phase behavior, as illustrated by a pseudo-ternary phase diagram, is afforded for a system of considerable complexity. THEORY Phase Behavior The use of the pseudo-ternary phase diagram to illustrate the phase behavior in miscible displacements has been discussed by Clark, Schultz and Shearin. Sie-vert, Dew and Conley and Arnold, Stone and Luffel' have presented both phase equilibrium and flow data for true ternary systems. For the true ternary, the application of the theory is straight-forward; for a reservoir system represented as a ternary, the theory undoubtedly gives a qualitatively correct picture. One purpose of this investigation was to see if the pseudo-ternary phase diagram could be used to predict with reasonable accuracy the conditions necessary for miscible displacements with actual reservoir systems. MiscIBLE Displacement of Two-Phase System A large number of papers "I3 have treated the miscible displacement of a single-phase fluid from both an experimental and a theoretical viewpoint. However, the normal field application of the process will be in a partially depleted reservoir. Often the state of the system will be such that the mobility of the gas phase is greater

By Carl R. Christiansen

The primary objectives of this project are (1) the determination of manpower demand in primary lead and zinc production for the years 1985 and 2000, and (2) the estimation of the availability of the required manpower for these years. In order to meet the first of these objectives relationships between employee requirements and metal production in the various states were established, The total primary lead and zinc production from United states mines in 1985 and 2000 has been predicted by the U.S. Bureau of Mines. These forecasts and the 1974 figures are as follows: [1974 1985 2000 Lead metal, tons 669,000 700,000 900,000 Zinc metal, tons 494,000 585,000 995,000] Mining By analysis of ore reserve data and industry characteristics, the authors estimated the portion of the primary production which each state would yield in the future years. As manpower requirements are determined by the tons of ore produced and by worker productivity, these figures were determined for each mining state and district by developing relationships between lead and zinc metal production, ore production, ore to recoverable metal ratios, employee productivity, and number of employees required. The number of new employees required annually to compensate for attrition and production growth is provided, also.

Jan 1, 1975

By Raphael Henrique Morais Reis

Esse artigo apresenta o desenvolvimento de um protótipo computacional para aplicação em estudos de sistemas termodinâmicos metalúrgicos, através de um sistema web, agilizando consultas as propriedades de substâncias e compostos contidos em Carvalho (1977). O projeto teve início analisando três fatores, primeiro, a importância dos softwares termodinâmicos computacionais na otimização da produção industrial, segundo, a falta de um software termodinâmico com desenvolvimento nacional, e terceiro, a restrição ao acesso a software termodinâmicos proprietários, com licenças pagas. Seu desenvolvimento seguiu a estrutura apresentada por Neto (2012), constituindo, banco de dados, software e aplicações, respectivamente. O sistema web supriu as dificuldade de instalação e interação, podendo ser acessado por quaisquer dispositivos (computadores, tablets e smartphone) conectados a internet.

Oct 30, 2017

By Everaldo da Silva

O objetivo deste trabalho foi estudar a fragilidade a quente de dois aços inoxidáveis duplex utilizando-se ensaios de torção. Ensaios de torção isotérmicos e em resfriamento contínuo, ambos com múltiplas deformações, foram realizados em corpos de prova de aços UNS S32304 e S31803. A caracterização microestrutural foi realizada por microscopia óptica e estudos sobre o equilíbrio de fases em temperaturas elevadas foram conduzidos utilizando simulação computacional. Nos ensaios em resfriamento contínuo, foi observada maior ductilidade no aço UNS 31803. Nos ensaios isotérmicos, foi constatada diminuição da ductilidade para os dois aços com a diminuição da temperatura do ensaio nos casos em que a fração volumétrica de austenita permaneceu constante.

Aug 16, 2017

By Claudio L. Schneider

Um flogopitito originário de um garimpo de exploração de esmeralda, na Bahia, está sendo estudado para utilização como fonte de potássio em técnicas de rochagem. Para este fim, é necessário cominuir a rocha até um tamanho apropriado. Estudos de cinética de dessorção e casa de vegetação estão sendo realizados com a finalidade de determinar o tamanho ideal de partícula para aplicações práticas. O custo associado à cominuição da rocha é um fator determinante na viabilidade econômica do uso da rocha como insumo na agricultura. Sendo assim, um programa de caracterização completo foi realizado para determinar rotas de britagem e moagem econômicas para esta rocha. Os resultados são apresentados de forma aplicada, com exemplos de circuitos e demanda energética.

Aug 8, 2018