Search Documents

By Adriano Francisco dos Santos

Dentre as diversas atividades executadas na área de Utilidades de uma empresa, o processo de clarificação e potabilização da água é de suma importância para a manutenção dos processos e das pessoas que ali trabalham. O presente trabalho visa mostrar a preocupação da Área de Energia com os funcionários, colaboradores e comunidade, no que se diz respeito aos riscos a saúde e segurança na utilização do cloro gasoso no processo de clarificação e potabilização da água e as atitudes tomadas para eliminação desse risco, durante o processo de substituição do cloro gasoso pela tecnologia Oxamine®.

Jul 31, 2018

By Lincoln Silva Gomes

Processos metalúrgicos durante soldagem provocam tensões residuais em peças soldadas. Recentemente foi observado um efeito de redistribuição das tensões residuais de soldagem num período de até duas semanas após o termino do processo de soldagem. Existe hipótese nossa que esta redistribuição das tensões está associada a mudança na microestrutura que ocorre no material após do processo de soldagem. Para provar esta hipótese, uma simulação física dos ciclos térmicos do processo de soldagem foi realizada utilizando a simulação física termo-mecânica (GLEEBLE). Através da técnica de microscopia eletrônica de varredura associada a técnica de difração de elétrons retroespalhados (MEV–EBSD) foi observada a variação da misorientação dos grãos e mudanças na microestrutura do material nos primeiros dias após soldagem, acompanhada de redistribuição das tensões residuais.

Aug 17, 2017

By José Maurício dos Santos Pinheiro

As redes de comunicação em cabeamento metálico são a imensa maioria nas plantas industriais. Entretanto, redes ópticas experimentam expansão nos ambientes industriais em substituição ao cabeamento metálico nas redes de automação. Isto se deve principalmente às exigências dos novos sistemas de automação industrial que têm obrigado a busca por soluções tecnologicamente atualizadas e estruturas capazes de disponibilizar a informação de modo mais flexível, barato e eficiente, observando a constante necessidade de adaptação para as tecnologias emergentes. Este estudo tem como objetivo discutir o emprego das redes ópticas passivas no ambiente industrial, discutindo a migração das redes metálicas para uma plataforma de rede óptica, visando maior capacidade de transmissão e gerenciamento simplificado, considerando a significativa redução de custos operacionais, consumo de energia e espaço físico.

Aug 17, 2017

By Andre Luiz Nunis da Silva

Didímio metálico foi obtido no Instituto de Pesquisas Tecnológicas do Estado de São Paulo, a partir do óxido de didímio, o qual foi produzido pela extração por solventes de óxidos de terras raras do concentrado obtido na mina de nióbio da Companhia Brasileira de Metalurgia e Mineração - CBMM. Foram investigadas duas rotas tecnológicas, metalotérmica e redução eletroquímica, ambas ocorrendo em sais fundidos. Foi possível produzir didímio com um mínimo de 99 % de pureza por ambas as rotas, mas a rota metalotérmica demanda uma etapa de processamento adicional para remover impurezas e agentes redutores.

Oct 30, 2017

By N. Parlee, V. C. Kashyap

The solubilities of nitrogen in liquid iron and liquid Fe-Ni, Fe-Mo, Fe-V, and Fe-Mo-V alloys were measured by the Sieverts method. Measurements were made at 1600° to 1800°C on binary alloys up to 20 pet Ni, 10 pet V, 10 pet Mo; and on ternary alloys containing 0 to 3 pet V with 0 to 5 pet Mo. The results on liquid iron confirm that Sieverts' law is obeyed in the range 50 to 750 mm pressure. The measured solubilities and their temperature coefficients are in general agreement with other modern authors. The logarithms of the activity coefficients of nitrogen in the binaries are approximately linear functions of the pet of alloying element. A method suggested by Wagner, Chipman, and others for predicting gas solubilities in complex alloys from solubility data on binaries was applied to the Fe-Mo-V alloys. Reasonably good agreement was obtained between calculated and experimental solubilities. NITROGEN'S solubility in liquid iron has been studied by a number of investigators. It is reasonably well established that the solubility of nitrogen follows Sieverts' law at least up to 1 atm partial pressure and that the solubility increases gradually with temperature. The solubility of nitrogen in Fe-X binary liquid systems has been investigated in only a few cases. Only the systems Fe-Cr,3-5, 7 Fe-V,3 Fe-Mn,3, 5 Fe-Ni,3, 5 Fe-Si,B, H Fe-C, L, H and Fe-P4 appear to have received any study. The only work on liquid Fe-V was done by Brick and Creevy.3 This was limited to 13.5 pet and 26.5 pet V, but no exact temperatures were recorded. No work whatsoever appears to have been done on liquid Fe-Mo alloys and even work on Fe-Ni alloys is rather scant. The work on liquid ternary systems is still more limited, and the only publication available appears to be that of Wentrup and Reif,7 who studied the Fe-Cr-Mn and Fe-Cr-Ni alloys. Rassbach, Saunders, and Harbrecht17 have reported work on the solubility of nitrogen in stainless steel but this was not a systematic study of any particular system. Commercial alloys usually contain several alloying elements. Thus, it often becomes important to be able to predict the nitrogen solubility in systems containing two or more added elements without the necessity of making measurements. Wagner,14 Chipman," Darken and Gurry," and Morris and Buehl 14 have suggested means by which this may be accomplished, and Langenberg14 has recently applied one of these methods to nitrogen solubility in complex liquid alloys. This paper reports the results of nitrogen solubility determinations on Fe-Ni, Fe-Mo, Fe-V, and Fe-Mo-V alloys and compares calculated and experimental solubilities in the ternary alloy. Attempted measurements on Fe-Cr alloys were not successful by the experimental method employed. Experimental Method The general method of solubility measurement was that of Sieverts.' The apparatus and procedure were essentially the same as used by Liang, Bever, and Floe."' The equipment consisted of a small vacuum furnace heated by a 6 kw induction unit, gas measuring apparatus, and a gas purification train. The crucibles used were Norton Alundum with alumina sand around them for insulation. The crucibles were charged with 100 to 200 g of material, about 180 g or nearly filling the crucible being found most satisfactory. Hot volumes were determined with argon and ranged from 95 to 130 cu cm (stp). Temperature measurements were made with a Leeds and Northrup optical pyrometer which was calibrated periodically against the melting point of iron in the same apparatus."-'* Good quality nitrogen, hydrogen, and argon gases were further purified and dried in standard purification trains. The sources of the high purity iron and other alloying elements used were as follows:

Jan 1, 1959

By Antonio Regio Avancini

Nos últimos anos Vitória vem sendo fortemente afetada por chuvas torrenciais em um curto período de tempo. Para garantir a segurança dos trabalhadores e equipamentos como também reestabelecer as condições normais de trabalho num menor intervalo de tempo, foi necessário rever e criar alguns procedimentos com o intuito de mitigar o efeito das chuvas. Os procedimentos são voltados principalmente a melhor manutenção das galerias de escoamento de água, melhorias no sistema de drenagem dos pátios, redução de altura das pilhas de matérias-primas, melhorias nos procedimentos de recuperação das matérias-primas dos pátios.

Aug 16, 2017

By Marcos de Oliveira Fonseca

O crescente volume de dados gerados pelos sistemas computacionais tem estimulado o uso cada vez maior das técnicas de Data Analytics. Tais técnicas suportam a transformação dos dados em informações úteis para tomada de decisão nas diversas áreas de negócio. Na indústria em geral essa situação não é diferente, graças também ao uso cada vez maior de sistemas de automação e informática industrial. Esses sistemas coletam e disponibilizam milhares de dados do processo numa alta taxa de aquisição, o que normalmente representa um altíssimo volume de dados, muitas vezes chamado de Big Data. O presente trabalho mostra como essas técnicas podem ser aplicadas para maior conhecimento do comportamento e melhoria do desempenho de processos industriais, usando uma abordagem prática de inteligência de negócio que explora as características dos sistemas de automação e informação industrial.

Jul 30, 2018

By Sidmar Aparecido Ceresani

O presente estudo tem como objetivo demonstrar a cinética de recristalização e o amolecimento da liga C272000 processada na laminação a frio com uma deformação de 75%. Para determinar o modelo cinético Johnson, Mehl e Kolmogorov (JMAK) foi adotado a temperatura de 450° entre 5min. a 50min. Restaurando totalmente a microestrutura deformada plasticamente sendo progressiva a elevação do tempo e da temperatura. A caracterização microestrutural das amostras foi utilizado microscopia óptica e metalografia. Conclui-se que o modelo JMAK satisfaz a forma de nucleação da recristalização da liga C272000.

Oct 30, 2017

By E. D. Gálvez, L. A. Cisternas, R. Acosta-Flores, F. A. Lucay

Froth flotation processes are carried out in flotation cells that are grouped into banks, and these banks are interconnected, forming a flotation circuit. A literature review shows the existence of papers related to flotation circuit design based on mathematical programming. However, due to the complexity of solving the mathematical model in most of the work, it is considered that a small number of species is present in the feed to the circuit, which differs from practice. In addition, simple bank models are generally used. This paper presents a methodology for designing mineral concentration circuits that overcomes the problems mentioned. It allows the use of more suitable cell or bank models and the inclusion of several species. The methodology is based on two phases. The first phase identifies the set of optimal structures using discrete values of stage recoveries, solving several mixed integer linear programming (MILP) problems. In the second phase, the optimal design for each of the structures obtained in the previous phase is determined using a suitable model for the recovery at each cell or bank, which results in a mixed integer nonlinear programming (MINLP) model. The design of a copper concentration plant with eight species and the design of a zinc concentration plant with three species and five size fractions by species are used to validate the proposed methodology. The structure of the cells in the rougher and cleaner banks deliver structures that are novel.

By Cláudio Antunes de Oliveira

O objetivo deste trabalho é utilizar o vasto banco de dados de informações de processo armazenadas pelo InfoPlus.21, que é um exemplo de sistema PIMS - Plant Information Managment System, para implementar um sensor virtual a partir de um modelo neural visando obter a tendência de resposta da variável consumo específico de uma caldeira. Propõe-se também, extrair diagnósticos do processo através do emprego da Lógica Fuzzy. As etapas de treinamento da rede neural e o desenvolvimento do diagnóstico envolveram simulações no software Matlab. Os resultados obtidos demonstraram-se bastante satisfatórios. Destaca-se a tendência de resposta do sensor virtual que apontou 97% de confiabilidade. Por fim entende-se que as propostas deste trabalho foram alcançadas, principalmente pela implementação inovadora do sensor virtual no InfoPlus.21 por meio da ferramenta SQLPlus, a qual possibilitará novas aplicações no meio industrial.

Jul 30, 2018

Provide a means of recovering precious metal values from finely ground tailing materials. Approach Determine the procedures needed for agglomerating the finely ground material for subsequent heap-leach cyanidation of the precious-metal-bearing tailings. Applying Agglomeration/Heap-Leaching to Fine Tailings Agglomeration technology was developed by the Bureau of Mines to provide cost-effective recovery of precious metal values though better heap leaching of clayey or low-grade ores. While many precious metal producers have adopted this technology to reclaim precious metals from crushed ores and wastes, other operations have experienced problems in using the heap leaching technique effectively on piles of fine tailings. In contrast to the coarser ore and waste material, most tailings piles contain more than 50 percent minus 200 mesh materials with no coarse material. Fine particles and clays present in the pile can impede 8 uniform flow of the leaching solution through the heap, thus preventing efficient and cost-effective precious metals recovery.

Jan 1, 1986

By W. E. Lamont

Flotation studies of phosphate-bearing waste pond materials, low-grade washer products, and raw ores, all from the Tennessee brown phosphate district, showed that these types of materials could be treated without des liming to recover high-grade phosphate concentrates. The investigation showed that fine grinding before flotation was a requisite for increased recovery of the phosphate values and that the optimum pH conditions were in the range of 10.0 to 10.5 when using anionic collectors. Multiple-cleaning of the rougher phosphate concentrate was required to produce high-grade concentrates. Phosphate recoveries ranged from 60 to 82 percent and were inversely related to the grade of concentrate produced.

Jan 1, 1972

By A. L. Mula

Pasaremos revista brevemente a 10s fundamentos de 10s ciclones, considerando un ciclón típico. Los datos gráficos disponibles en la literatura han sido convertidos en ecuaciones matemáticas por conveniencia. Se suministran los procedirnientos preliminares para seleccionar y diseñar tanto los ciclones como las bombas, y se facilita con algún detalle un ejernplo de cálculo para un hipotético circuito de molienda. En general, debe consultarse a 1os proveedores de ciclones y bombas para determinar un disefio definitivo. Algunos suministradores de ciclones emplean normalmente computadores digitales para el diseño definitivo con objeto de asegurar una gran precision.

Jan 1, 1982

By David A. Monaghan, Kenneth R. Maser, Adi R. Gurdar, D. Randolph Berry

5. Development of Initial Probing System 5. 1 Introduction The preliminary evaluation of a variety of potential methods for initial probing showed that the optical system using closed circuit television (CCTV) and the sonar, or acoustic ranging, system were the most promising. The former is capable of pro¬viding a visual display of the mine passages in a clear, non-smoky environment, and the latter is capable of providing a map of the spatial location of the coal surfaces making up the entries, as well as objects, such as cribs, mining machines, etc., in the passages in both smoky and non-smoky environments. The sonar system used in conjunction with the CCTV in a clear environment can greatly assist in resolving the spatial distribution of objects seen on the TV screen. Further, in a smoky environment the interpretation of the sonar information could be facilitated if some visual information were also available. CCTV systems exist but require some modifications to suit this particular application. The Industrial Hazards and Communications Division of the Bureau has an ongoing program for the development of such a CCTV system. Rather than duplicate this effort in developing a CCTV system, it was decided to evaluate the possibility of utilizing their system for initial probing, while continuing with the develop¬ment of a system which would work in any environment, including the presence of dense smoke. The concept of using sonar for the initial probing of mine passages represents the application of new technology requiring development. The results of such a development effort undertaken during the course of this program are described in the following sections.

Jan 1, 1973

By Hoyt Gale

RECENT work on borate deposits near Kramer, in the extreme southeast corner of Kern County, California, is of special interest to those who are making a study of the mode of origin of the borate minerals colemanite and ulexite. A valuable clue to the mode of origin of colemanite in its present known deposits is given in a paper by W. F. Foshag1, of the United States National Museum. Colemanite is found in or near original deposits of ulexite, from which it is supposed to have been derived by a change in the rate of movement or the character of the ground water. Indications that an alteration of this sort had produced colemanite were first recognized by the writer' in specimens collected in the Kramer district in 1920, and sent to W. T. Schaller, at U. S. Geological Survey, for identification. The identity of the two borate minerals in these specimens was not at once determined, but the relations of the minerals as seen in the specimens afforded a manifest clue to the origin of the deposits. Similar specimens were obtained by the writer from deposits in death Valley soon after he had examined the deposits near Kramer. After studying the specimens submitted to him Dr. Schaller wrote as follows: "I have finally positively identified the boron minerals you sent me with your letter of Sept. 27. The `white fibrous mineral like ulexite' is ulexite; the harder nodules' in the clay are colemanite, apparently formed from the ulexite as a result of leaching, with recrystallization in place-a theory that Foshag is working on." The present paper is a report on the facts observed at. the deposits near Kramer, and some general observations on the geological relations noted, which, unfortunately, still form only a very incomplete record.

Jan 2, 1926

By C. Liu, G. Zhu, Y. Liao

"The effect of particle size on the flotation kinetics of a low-rank coal was compared using air bubbles and oily bubbles. Five kinetic models were applied to the data from the tests to derive the relationships between the flotation rate constant, the ultimate recovery, and the particle size fraction. The results show that oily bubble flotation (OBF) resulted in a lower ash content and higher combustible recovery than air bubble flotation (ABF), especially for the -125 ??m size fraction. It was found that the flotation of a low-rank coal in individual size fractions using air bubbles and oily bubbles can be best described by a first-order model with rectangular distribution of tendency to float and the classical first-order model respectively. OBF yielded higher ultimate combustible and ultimate ash recoveries. The flotation rate constants for OBF were higher in all the models except for the fully mixed reactor model. The ultimate recovery values and modified rate constants first increased and then decreased as the size fraction decreased. The trend of the flotation rate constants as a function of the size fraction was similar in all the models except for the fully mixed reactor model. IntroductionFroth flotation is a physical-chemical separation method that is widely used in coal beneficiation for the separation of fine coal particles from associated minerals in water slurries. Since the cumulative recovery of a component in the concentrate is proportional to flotation time, the flotation process can be considered as a time-rate recovery process (Emad, Mohammad, and Bahram, 2010). Therefore, the general mathematical flotation models that incorporate both a recovery and a rate function can describe flotation time recovery profiles.The kinetics of coal flotation, as a measure of coal recovery as a function of time, have been studied in detail by many researchers. Different kinetic models have been proposed and published in the literature. The order and the rate constant are strongly dependent on the flotation conditions, such as the particle size and size distribution, the bubble concentration, the reagent concentrations, and the operating parameters (Zhang et al., 2013). The particle size has been reported to affect the flotation kinetics to a great extent (Yoon, Luttrell, and Asmatulu, 2002; Ntengwe and Witika, 2011). Numerous researchers have studied the aspects of flotation kinetics while paying special attention to particle size (Meftuni and Ibrahim, 1997; Rubinstein and Samygin, 1998; Graeme, 2012). However, the effect of particle size on the flotation kinetics of a low-rank coal has been relatively little discussed."

Jan 1, 2017

Editor?s note: Each year, Mining Engineering features an industrial minerals review. Several people put in a fair amount of time in developing the material for this issue, all the while doing their own jobs. Thank you to the industrial minerals annual review editor, to the Industrial Minerals and Aggregates Division technical committee chair and vice-chairs, and to the authors of the individual commodity profiles. Jim Norman, member SME, of Tetra Tech, is the industrial minerals annual review editor. Rajesh Raitani, member SME, of Cytec Industries Inc., is chair of the Industrial Minerals and Aggregates Division?s Technical Committee. The technical Committee vice chairs include: ? Vishal Gupta, member SME, of FlSmidth, Agricultural Materials. ? Candace Trimble, member SME, of Oil- Dri Corporation of America, and Bradley Van Gosen, of the U.S. Geological Survey, ceramics and refractory materials. ? Stanley Krukowski, member SME, of the Oklahoma Geological Survey, chemical raw materials. ? Russell Winn, member SME, of R.E. James Gravel Co., chemical raw materials. ? Justin Zdunczyk, member SME, of Plum Creek, construction materials. ? Jerry Gauntt, member SME, of Golder Associates, fillers and pigments. ? Michael Cheshire, member SME, of Los Alamos National Laboratory, sorbents, filters and process aids. ? Rajesh Raitani, member SME, of Cytec, Industries Inc., specialty minerals. Their help makes possible this June industrial minerals issue. On behalf of ME readers, the editors thank them.

Jul 1, 2013

By P. F. Kinyoun

MANY interesting new features are embodied in the latest extension to the open-hearth department of the Bethlehem Steel Co., at Lackawanna, N. Y. Automatic control of the important factors in furnace operation-fuel, air, draft, pressure, slag composition, and of the temperature in various regions of the furnace-has been carried out to a remarkable degree; the human factor is minimized, and the chances for mishaps and irregularities in operation are greatly reduced.

Jan 1, 1937

By AIME AIME

THE MILLING PROGRAM on Monday required a morning and afternoon session with a special luncheon of the Milling Committee in the Engineers Club at noon. Grinding and flotation were the main subjects of the papers which drew an attendance of fifty or more at each session. Under the direction of Chairman Arthur F. Taggart in the forenoon, all papers on flotation and general milling were considered, leaving the, after- noon free for crushing and grinding, with Dr. Galen H. Clevenger in the chair. The high spot was the first public presentation of the idea of size reduction of minerals by explosive shattering.

Jan 1, 1932

By G. W. Jones

[A survey of the Ii terature reJ.l....ting to iE;li tion temperatures of acet-ylene-air and acetylene-oxygen mixtures reveals rather '.'fide disagreement in the reported results. In SO!':1e instances the i ition temperatures of acet?-ylene-air mixtures were reported to be lower than those of acetylene-oTjgan mixtlU'es, which is contrary to experience 'tri th other combustibles. ':10 clea.r up some of t!le reported discrepancies, the authorn have icvestigated the igni tion temperatures of acetylene both in air anri oxygen, and their results are presented in this report.]

Jan 1, 1941