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By E. A. Metz

Work related pulmonary diseases are in the top TEN causes of occupational disability and death in the United States. Likewise, it also ranks high inmost of the other industrial countries. It is difficult to know the true occurrence of occupational lung disease because of poor documentation. This is especially true when one examines workers’ compensation claims. Most frequently, silica and asbestos are paramount in our discussion of work related pulmonary disease. Little consideration is given to other “dust-related” diseases, irritant reactions, reactive airway responses, and hypersensitivity reactions. The major classification of occupational lung diseases will be discussed. This includes both acute and chronic disease that arises in the work place, especially, the mining industry. It’s more important to make an accurate evaluation and diagnosis for the prevention of disease among other workers.

Jan 1, 2000

By Henrique de Araújo Resende

Em função do aumento constante da produtividade nos laminadores e linhas de processo de usinas siderúrgicas e de alumínio, está cada vez mais evidente a necessidade de aumentar as campanhas de produção dos mandris de bobinadeiras e desbobinadeiras, reduzir as paradas de manutenção das linhas além de minimizar ao máximo os custos com reparo e fabricação. Para isso, é importante conhecer os diversos projetos de mandris utilizados nos últimos anos, os maquinários envolvidos na fabricação e reparo desses equipamentos além de estar atualizado quanto às novas tecnologias que poderão ser aplicadas. Para possibilitar o entendimento descrito acima, este material será divido em 3 partes: Projetos SMS de mandris no Brasil; Condições de fabricação e reparo; Novas tecnologias. A SMS possui 58 mandris em operação hoje no Brasil estratificados entre os seus principais clientes, desde linhas de decapagem e laminação a quente até a saída do produto final após os laminadores a frio na galvanização e linhas de pintura e corte. Com isso, é possível estabelecer uma análise técnica do desempenho de cada equipamento e sobressalente de forma bem estruturada. Esse é o principal objetivo desse trabalho.

Aug 16, 2017

Now more than ever, the United States must have an adequate and dependable supply of minerals to meet its defense and economic needs. A chief mission of the U.S. Department of the Interior Bureau of Mines is to help ensure that the United States meets these needs at acceptable environmental, energy, and economic costs. As it looks toward the 21st century, the Bureau of Mines will focus its attention on the following areas: - upgrading the capabilities of its mineral information and analysis program - expanding mineral land assessment activities - disseminating the practical results of federally funded research activities to the private sector through enhanced technology transfer - addressing the impact of regulations on mineral industries - addressing the needs for mineral-oriented training and research in the Nation's universities - enhancing mine worker health and safety - improving mining and mineral processing productivity through automation, robotics and other innovative technologies - reducing the environmental impact of mining and mineral processing operations - and enhancing the accessibility and conservation of domestic mineral resources.

Jan 1, 1991

By Z. Sun

Magnetic fields have been used for inclusions removal from melt and preparation of materials with gradient compositions. Fundamental in these applications is that the induced magnetic forces on the particles/melt can enhance migration and change the interaction behavior. In the present paper, migration and interaction behavior of electrical-insulating particles in a conductive melt under strong magnetic field are theoretically analyzed. It is found that the migration can be considerably enhanced for micrometer sized particles by applying a strong magnetic field. In addition, two forces are involved in the interaction between two particles: the interparticle magnetic dipole-dipole attractive force due to magnetization and the repulsive force induced by flow of the melt. This theoretical analysis renders a better understanding of recent experimental results. Additionally, a new method by using strong magnetic field can be proposed to control the particle size distribution for the preparation of metal-matrix composites.

Jan 1, 2009

By Elvis Candeias Silva

Introdução: A automatização dos procedimentos de desligamento, religamento e de extração remota de disjuntores de alta tensão consiste em um sistema que utiliza as tecnologias disponíveis na atualidade para trabalhar em prol da saúde e segurança dos trabalhadores. O conhecimento e utilização de Controlador Lógico Programável - CLP, Interfaces Homem Máquina - IHM foram considerados fundamentais para este projeto. Estes recursos alinhados às normas técnicas vigentes, e a adoção de dispositivos de proteções entre outros, possibilitou a elaboração deste projeto. Objetivo: Aumentar a segurança do eletricista ao realizar manobras com disjuntores de alta tensão. Método: Desenvolvido um sistema automatizado para desligamento, religamento, extração e inserção de disjuntores de alta tensão remotamente, utilizando um motor elétrico no painel do disjuntor, substituindo o que antes era feito por um profissional habilitado na área elétrica. Resultado: A implantação deste sistema permite realizar os procedimentos no disjuntor em local seguro, chamado zona livre, distante do raio de ação de qualquer energia proveniente de um arco elétrico. Conclusão: O projeto permitiu a remoção do risco para o eletricista durante a operação do disjuntor, deixando-o livre de qualquer possível contato com a energia proveniente de uma falha no disjuntor.

Aug 7, 2018

By Fernanda Simões Ribeiro Curcio

O desempenho econômico de uma ferrovia é reflexo, principalmente, da qualidade da via onde circulam os trens e da frequência de manutenções necessárias. A manutenção da via permanente tem um custo significativo, principalmente quando se faz necessária a reposição de trilhos. Além disso, uma linha férrea interditada impacta diretamente nas condições de segurança e nos custos operacionais de uma empresa. Conseguir uma via permanente satisfatória é um dos mais complexos assuntos discutidos na literatura ferroviária. Em regiões sob convertedores de aciarias, a manutenção de linhas férreas se torna ainda mais complexa devido a projeção de material incandescente, com temperaturas que chegam a atingir 1.300ºC. Os meios tradicionais de fixação de dormentes com olhais e grampos elásticos não resistem aos efeitos destas temperaturas, comprometendo a fixação dos trilhos, ficando estes susceptíveis a deformações excessivas e, consequentemente, sujeitos a constantes quebras. Como o trilho é o componente mais importante da superestrutura ferroviária, sendo o principal elemento de suporte e guia dos veículos e representando o maior custo dentre os elementos da via, ampliar sua vida útil representa reduções significativas de custo e impactos operacionais.

Aug 16, 2017

By Caroline Olsen

The objective of this study was to achieve Zn activation control in an industrial Cu flotation circuit treating a complex Cu-Pb-Zn-Au-Ag sulphide ore at the LaRonde Division of Agnico-Eagle Mines Limited (Québec, Canada). In order to provide process relevant results, a laboratory testing methodology was developed to duplicate plant operational parameters. The action mechanisms of ZnSO4, TETA (triethylenetetramine) and NaHSO3used as depressants in order to limit ZnS activation were examined. Laboratory flotation tests with and without Cu2+ions (the ions responsible for ZnSactivation)were performed. All depressants showed equal or better flotation performance relative to baseline tests. For example, in the presence of Cu2+, the Zn recovery reduced from 32.2% to 17.5% in the copper rougher concentrate after adding ZnSO4(with a dosage of 50 g/t). TOF-SIMS analyses confirmed the relative decrease in surface Cu in the samples treated with ZnSO4and TETA. For the case with TETA, this indirectlyindicates the formation of a copper TETA complex in solution, thereby reducing available Cu for transfer. The TOF-SIMS and XPS data indicate that the addition of ZnSO4and NaHSO3resulted in an increase in surface metal hydroxides and SO3 on ZnS grains inhibiting both Cu and collector attachment.ZnSO4 was subsequently tested with success in the LaRonde concentrator. The addition of 40 g/t ZnSO4 at the conditioning (or cleaning) stage led to a 2% reduction in Zn content in the Cu and PM concentrate. Recently, improvements towards the control of copper sulfate addition in the downstream Zn flotation circuit resulted in the reduction of Cu2+ in process water. As this ?cleaner? water is recycled for Cu and PM flotation, the addition of ZnSO4 is now used only as required.

Sep 1, 2012

By P. Campbell, E. M. Gardy, L. Hachkowski

Introduction The efficient process control of a uranium mill and its associated mining operation requires a nearly continuous knowledge of the uranium concentration in the ore. Generally, the approach is to use laboratory assays of grab samples from the mill feed belt. In some cases, elaborate and expensive systems have been used to ensure random sampling, but even with these systems, mass-balance discrepancies still exist. There is a requirement for an on-line instrument that can give a prompt, accurate analysis of a large portion of the feed stock. The authors have recently evaluated a laboratory system that achieves these goals using neutron activation and delayed neutron counting. The development of the on-line uranium ore analyzer is a consequence of previous work done at the Whiteshell Nuclear Research Establishment (WNRE) (Campbell et al., 1978 and 1981), and is based on the emission of delayed neutrons after the neutron irradiation of fissionable materials. The mechanism of delayed neutron emission has been described (Keepin, 1965), but briefly is as follows. The fission fragments resulting from irradiation are in an excited state. Certain of these delayed fission products, precursors, decay to a more stable state by the emission of a delayed neutron. The delayed neutrons can be divided into six groups with effective half-lives ranging from 0.2-55 sec. It is important to note that more than 50% of the delayed neutrons are emitted within the first 6 sec after irradiation; this has an influence on the design of the analysis instrument. Measurement Cycle The measurement cycle involves a neutron irradiation, a delay time, and a counting period. The laboratory demonstration model of the ore analyzer comprises a californium-252 neutron source, a source chamber, a pneumatic transfer facility, and a neutron irradiation and counting module (Fig. 1). The ore sample is placed in the irradiation chamber. The neutron source is transferred to the center of the chamber for a 5-sec irradiation while the helium-3 thermal neutron detectors are switched off. As the source returns to the storage chamber, the detectors are switched on and the delayed neutrons counted. The total assay cycle is 16 sec. The current instrument design calls for the ore to be cut from the main belt every 16 sec by a mechanical arm and dropped into the analyzer directly, or via another belt. The cycle starts when there is a sufficient mass of ore in the irradiation chamber to depress a switch and stops when the delayed neutron count is finished. The ore is then dropped through the bottom of the analyzer chamber and returned to the main belt. The counts from each cycle are accumulated and the data reduced to give the desired information. Key for Fig. 1 A-Helium-3 neutron detector B-Wax moderator for neutrons C-Irradiation chamber D-Funnel for receiving ore E-Gate F-Transducers G-Biological shield for neutron source H-Transfer tube for neutron source I-Neutron source J- Microprocessor K-Accumulator for hydraulics L-Control panel M-Electro-hydraulic servo valve to control movement of the source N-Electro-hydraulic proportional valve to control movement of the gate O-Hydraulic power unit Irradiation and Counting Equipment Irradiation of the ore is achieved using a 1 X 10 7 neutron*s-1 californium-252 neutron source. The source is contained in an iron capsule and pneumatically transferred between the irradiation/counting and storage chambers. The irradiation/counting chamber possesses 12, 600-mm (24-in.) long helium-3 thermal neutron detectors embedded in an annulus of wax (Fig. 1). Two sets of six detectors are each interfaced to a preamplifier, amplifier and single-channel pulseheight analyzer system, and the two systems are connected to a scaler. A special timing unit controls the transfer of the source and the on and off switching of the detector assembly, in sequence with the movement of the source. Results and Discussion In the experimental demonstration, using the 107 neutron.s-1 source, a 10% uranium ore was measured to ± 10% (2o total error) in 10 cycles and ±6% (2o) in 100 cycles. Since a larger source was not available, it can be statistically predicted that a 109 neutron-s-1 source could be used to measure a 0.1% ore to ± 10% (20) in 10 cycles. The uranium can occur as discrete nonhomogeneous particles in the ore, and the error caused by such a distribution of particles is ± 4% (2o), as determined by

Jan 1, 1984

By Foluke Salgado de Assis

Este trabalho visa apresentar os resultados obtidos através de ensaios balísticos realizados em sistemas de blindagem multicamada tendo como camada intermediária o compósito de poliéster reforçado com fibras de juta. Seguindo as especificações da norma americana NIJ 0101.06, foram realizados ensaios balisticos utilizando munição de calibre 7,62 x 51 mm, que possui velocidade acima de 800 m/s. A blindagem multicamada utilizada possui como camada frontal uma pastilha hexagonal cerâmica (alumina dopada com 4% de nióbia), segunda camada de compósito de matriz poliéster reforçada com manta de juta e terceira camada uma placa de alumino 5052 H34. A utilização de compósitos poliméricos reforçados com fibras naturais em substituição às fibras de aramida é de grande interesse, pois além de desempenharem a mesma função no sistema de blindagem, possuem um valor de mercado bem menor. Os resultados de profundidade de indentação na plastilina atenderam a norma NIJ 0101.06 e utilizando a técnica de microscopia eletrônica de varredura, verificou-se que o compósito poliéster-juta capturou os fragmentos cerâmicos através do mecanismo de incrustação mecânica.

Oct 30, 2017

By Alaelson Vieira Gomes

Amostras de alumina APC-2011 SG com nióbia, sílica e magnésia foram sinterizadas a 1400 °C/3h, a fim de serem avaliadas suas propriedades balísticas. A adição de nióbia foi de 6% e 8% em peso; sílica foi de 0% e 0,8% em peso; e magnésia no teor de 0% e 0,15% em peso. As amostras sinterizadas foram caracterizadas medindo-se dureza, densificação e velocidade após o impacto.Os ensaios balísticos foram efetuados colando discos cerâmicos em chapas de aço e então submetendo o alvo a impacto usando projetil 7,62 mm de um fuzil com uma distância de tiro de 5m. A energia absorvida pela fragmentação dos discos cerâmicos foi estimada pela velocidade residual.As superfícies de fratura das amostras foram observadas por microscopia eletrônica de varredura. Os resultados foram analisados.Verificou-se que a adição de quantidades elevadas de nióbia à alumina com presença menos significativa de sílica e magnésia pode incrementar a presença de fase vítrea nos contornos de grãos da alumina, com efeito nas propriedades do material para uso em proteção balística.

Oct 30, 2017

By Késsius Bortolan Menezes

O complexo Minas-Rio da Anglo American iniciou suas operações em agosto de 2014. A usina de tratamento produziu, em 2016, cerca de 15,5 milhões de toneladas de concentrado. O minério, explorado em Conceição do Mato Dentro (MG), passa pelas etapas de cominuição, classificação, concentração e separação sólido-líquido antes de ser bombeado por 529 km até São João da Barra (RJ), onde é filtrado, estocado e embarcado para exportação. Durante a fase de projeto, a utilização de equipamentos pilotos com capacidade de centenas de quilos por hora foi de fundamental importância para verificação da viabilidade técnica do tratamento do minério. Contudo, a realização de um teste exigia um esforço muito grande, devido aos grandes volumes de minério necessários. Por isso, com o início das operações, os testes em escala de bancada começaram a ser mais explorados. Além deles, testes em mini planta piloto com capacidade de dezenas de quilos por hora são muito utilizados, pois permitem simular de forma simples diferentes circuitos. O trabalho tem por objetivo mostrar essa evolução histórica na utilização de ferramentas para avaliação do desempenho da flotação, com exemplos de resultados práticos obtidos, e como os mesmos influenciaram a tomada de ações que culminaram em melhorias industriais.

Oct 30, 2017

By Camila Fernandes Rezende, Camila Simon Christ, Vinicios Andreatta, Marcus Vinícius Pimentel Gomes

A integração e cruzamento de dados de diversos sistemas para as unidades técnicas de processo sempre foi uma necessidade e um desafio. Para a unidade técnica da Aciaria, a integração de dados gerados pela Instrumentação, Automação e MES (Manufacturing Execution System) é imprescindível para a análise e otimização do processo. Este processo feito de forma manual era trabalhoso, improdutivo e com grande potencial de erros. Mesmo com o suporte da área de TI (tecnologia da informação) e TA (tecnologia de automação), em alguns casos este processo era inviável devido à complexidade. Com a utilização de uma ferramenta analítica, já utilizada em outros processos produtivos da empresa (Laminação de Tiras a Quente e Qualidade), foi possível prover acesso a diferentes bases de dados, permitindo a integração dessas informações de forma simplificada, ágil e única, todos consumindo os mesmos dados, com as mesmas regras. A automatização deste processo trouxe benefícios como: melhora na qualidade do dado, democratização das informações e tempo para investigação de problemas e otimização de processo, além de menor dependência das equipes de TI e TA.

Oct 1, 2019

By Y. V. Swamy, B. Bhoi, H. S. Ray

Low-grade manganese ores with low Mn/Fe ratios can he enriched through selective carbon reduction of iron oxide to magnetite followed by magnetic separation o f the magnetite. Thermogravimetric analysis (TGA) was used to assess the preferential isothermal reduction of pure M1702 and Fe2O3 using solid carbon. This was followed by reduction of a synthetic analogue of composition comparable to an actual low-grade ore (i.e., Sandur manganese ore, Sandur, India). The carbothermic reduction of the manganese ore converts the hematite and goethite minerals to magnetite (Fe3O4), with the magnetite then going into the magnetic, fraction. The resultant nonmagnetic ,fraction becomes depleted of iron with an enhanced manganese content. These results show that it is possible to reduce the iron from 22% to 5.85%, thus increasing the Mn/Fe ratio from 1.52 to 6.2 with a manganese recovery of about 50%. The recovery was, further improved by grinding the magnetic fraction to -75 µm.

Jan 1, 1999

By N. Kumar Kittusamy

Operators of construction equipment perform various duties at work that expose them to a variety of risk factors that may lead to health problems. A few of the health hazards among operators of construction equipment are: (a) whole-body vibration, (b) awkward postural requirements (including static sitting), (c) dust, (d) noise, (e) temperature extremes, and (f) shift work. It has been suggested that operating engineers (OEs) are exposed to two important risk factors for the development of musculoskeletal disorders: whole-body vibration and non-neutral body postures. Method: This review evaluates selected papers that have studied exposure to whole-body vibration and awkward posture among operators of mobile equipment. There have been only few studies that have specifically examined exposure of these risk factors among operators of construction equipment. Thus other studies from related industry and equipment were reviewed as applicable. Conclusion: In order to better understand whole-body vibration and postural stress among OEs, it is recommended that future studies are needed in evaluating these risk factors among OEs.

Jan 1, 2004

By S. A. Allen

The Eufaula bauxite district of Barbour and Henry Counties in southeast Alabama covers an area approximately 14 miles long, 6 miles wide at the eastern extremity near the Chattahoochee River, and 10 miles wide at the western end near the east fork of the Choctawhatchee River (see figs. 1 and 2). The long axis of this polygon bears a little south of east.

Jan 1, 1949

By D. Bogh

Wound rotor motors are used in difficult mining applications where there is a need to start high inertia, hard starting loads while limiting inrush current They are recognized as robust and simple to control. This paper will cover the performance, specification, and important issues to be considered when applying medium voltage wound rotor motors in mining applications. Medium voltage grinding, crusher, and conveyor applications will be discussed. Specifically covered are motor efficiency, speed range, and rotor control. Crane motors often have wound rotor construction, but their load cycle and ratings are outside the scope of this paper.

Jan 1, 2011

By Satish Kate

Indian limestone mines which are highly mechanized in operation and supply limestone to the cement plants have been quite successful in devising ways and means to optimize blasting parameters, so as to have best fragmentation, powder factor, and cost of excavation. In primary blasting mechanized or manually mixed ammonium nitrate Fuel Oil is quite popular in dry holes, and in case of watery holes conventional packaged slurry/emulsions are being used. In order to avail the low density characteristics of the ANFO, some limestone mines have also used Saw Dust and Rice Husk along with ANFO. A number of field trials have been undertaken to explore the suitability of mixing rice-husk and saw dust with ANFO. Presently, about 10% of rice husk/saw dust is being used only to expand the explosive column. The main technical consideration for the use of saw dust/rice husk, has been to reduce the final density and increase the occupancy of explosive in the blast-hole. This not only lowers the detonation pressure in the blast holes, but also reduces cost of explosive without compromising on the fragmentation quality. Besides, with sleeping of the charge there is no substantial fall in the blast quality.

Jan 1, 2006

By M. L. McAllister, M. Veiga

The mineral industry has seen many significant changes in the past decade. Increasingly, it has responded to unanticipated pressures and demands with a variety of voluntary initiatives. Yet there is still much to do. Mining now takes place in a different context than was the case in the past. Socio-economic, political and environmental considerations must now be integrated into traditional mining systems. This process of integration needs to involve industry, governments, academics, communities and other stakeholders to design a new approach to mining, one that can be fostered through interdisciplinary links and holistic strategies. This paper considers the meaning of sustainability in the context of the Canadian mining industry and explores the need for a broader vision for the mining industry. The role of technology is then analyzed and related to an initiative recently taken by Canadian universities to develop a national network for interdisciplinary research into sustainable mining, CaSM.

Jan 1, 1999

By D. Bernabe

The mine scheduling process defines a mining sequence across the life of the mine and stipulates the amount of ore, waste, and specific blocks to be mined each year so that the highest economic return can be obtained under a number of constraints. There are a number of mine scheduling software packages available. Each claims to be the best scheduler by maximizing Net Present Value (NPV) or by minimizing overall mining costs. These mine scheduling programs follow different procedures and scheduling philosophies based on either mathematical or heuristic principles. There was no study in which the mine production scheduling procedures applied by these packages were discussed and compared. This paper evaluates four open pit mine scheduling programs recently developed and compares them in order to determine if significant differences exist among them. The same input data, which consist of a 3-D block model, an economic set of parameters, and the initial surface topography for a operating copper mine in Southern Peru, was used to test each technique. The following programs were investigated with respect to their ability to optimize the NPV for the case study. 1) M821V1 Scheduler by Mintec; 2) NPV Scheduler by Earthworks; 3) Milawa Scheduler by Whittle Programming; and, 4) Fundamental Tree Scheduling Method (FTSM) developed at the Colorado School of Mines. The results from this case study demonstrate that the scheduling software packages, Mintec, Earthworks, and Whittle obtained similar NPV’s, while FTSM scheduler gave a six percent higher NPV than the other schedulers.

Jan 1, 2002

By Andrew R. Marchbank

The application of biologically assisted methods for metal extraction in the mining industry has a long history, but development of modern techniques has been relatively slow. There is, however, a resurgence of interest in the industry with the recent development of methods to successfully treat base metals concentrates. Two major pilot plant programs for treatment of chalcopyrite concentrates have been initiated in the past year and results from one are beginning to be released. This paper provides an overview of methods that have been applied in the past; from the earliest deliberate applications of the technology, through the copper and uranium heap and dump leach applications, the more highly engineered agitated tank leach gold applications and the developments currently taking place in the industry.

May 1, 2002