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By Carl Rampacek

The conversion of dilute sulfur dioxide gas into sulfuric acid by autoxidation in mechanical cells of the flotation or gas absorber types was investigated. Bench-scale tests were made with sulfur dioxide-air mixtures to determine the influence of several factors on autoxidation of sulfur dioxide, using iron and manganese salts as catalysts. The laboratory investigation subsequently was extended to pilot plant acid-making tests, using a modified turbomixer gas absorber having a 12-inch-diameter impeller. Sulfur dioxide gas was produced for the tests by roasting pyrite in a fluidized-bed reactor. In the better tests, made with manganese sulfate as the catalyst, the equivalent of 1,000 pounds of anhydrous H2SO4 was produced per 24 hours as a 10-percent solution; power consumption was 0.2 kwhr per pound of equivalent anhydrous acid synthesized. The batch and continuous tests demonstrated the technical feasibility of producing dilute sulfuric acid by autoxidation of sulfur dioxide gas in mechanical cells when converting pyrite roaster or waste smelter gases.

Jan 1, 1963

By Lívia Silvestre Andrade

Uma das rotas mais importantes de produção do Fe-Nb para aplicações siderúrgicas é a aluminotermia. Para que o processo seja eficiente, é necessário projetar adequadamente a escória, para garantir a mínima retenção de metal na escória e reduzir as perdas, assim como determinar a carga da aluminotermia considerando os balanços de massa e de energia. Neste trabalho, os efeitos das adições de CaO e CaF2 sobre as características das escórias do processo são determinados através da termodinâmica computacional. Um balanço de massa e um balanço de entalpia são formulados, de modo a verificar se as quantidades dos diversos materiais adicionados são adequadas e se as temperaturas de fim de processo são razoáveis. Verifica-se que, a partir de uma carga hipotética formulada, há espaço para melhorias importantes balanceando-se corretamente as adições de CaO e CaF2. Além disto, verifica-se a influência do teor de Mg contido como impureza no Al empregado como redutor, observando-se que seu efeito é bem menos significativo do que inicialmente esperado por diversos operadores.

Oct 30, 2017

By M D. Taylor, G Duclaux, K Atkinson, L A. Fisher, A R. Latham, M F. Gazley, S J. de Beer, C M. Tutt

Geological logging by mine and exploration geologists involves the application of a logging code that requires a geologist to make a subjective decision to classify a particular rock unit. This will most likely result in inconsistencies in logging that will be difficult to monitor or assess over time. A potential solution to this problem is to have an objective method to determine the true nature of a given rock unit. This can be achieved using portable X-ray fluorescence technology (pXRF), as large geochemical data sets can be collected rapidly and at low cost. Plutonic Gold Mine (Plutonic), Western Australia, has a growing data set of more than 150 000 pXRF multi-element analyses from core and underground face samples, reconciled to Au fire-assay concentration, and logging codes. This study investigates and statistically validates the consistency with which the logging codes have been applied at Plutonic for the last four years, with respect to both Au distribution and other elements. In doing so, we have developed a schema that allows objective logging to occur once core has been sent for assay and analysed by pXRF. While far from replacing the geologist in the field, this is a complementary method that adds significant value to a data set.CITATION:Gazley, M F, Tutt, C M, Latham, A R, Duclaux, G, Fisher, L A, Taylor, M D, de Beer, S J and Atkinson, K, 2013. Objective geological logging using geochemical multi-element data - Plutonic Gold Mine, Western Australia, in Proceedings World Gold 2013 , pp 455-462 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

The term "timbered stope" is here meant to denote stopes in which timbering is the predominant feature of the mining method. Stopes with stull sets, as in the Hecla mine, are types of timbered stopes; these types are probably the best-known. Timbering stopes by means of square sets is not as common as formerly, as the system is not often necessary, yet there are good examples and large tonnages are being mined by the method. The square set may be utilized in ordinary overhand stopes if the orebody is suitable. At some mines, square sets have been abandoned in favor of top-slicing; and at others, the square set has superseded horizontal cut and backfilling. A drift, either in the wall or orebody, is necessary before opening the sill floor. In wide deposits, there may be a grillage of drifts and crosscuts, and at least one raise to the level above is needed in each stope for ventilation and handling timbers and filling. The square sets are filled with waste rock from the hanging wall, sorted from the ore, from development work, or from the level above. As a rule, little timber is recovered. The examples include the Butte district, Mother Lode of California, Bunker Hill & Sullivan, Hecla, and Morning mines.

Jan 1, 1925

By G. H. Long, D. H. Magnusson

THE DEFINITION of the continental margin, as considered in this paper, is in the broad sense: " ... those provinces of the continents and of the oceans which are associated with the boundary between these two first-order features of the earth" (Heezen et aL, 1959, p. 17). The provinces in the area under con-sideration are: the Continental Shelf, the Continental Slope and the Continental Rise. The Continental Shelf extends from the shoreline to the shelf break, which lies at approximately the 200-meter isobath through-out the region (except north of the Grand Banks, where the break may be defined more properly by the 400-meter isobath). The Continental Slope and Rise occur between the shelf break and the 4,000-meter isobath. (The last figure was somewhat arbitrarily selected for the purpose of this paper.) The Atlantic Continental Margin as thus defined extends along the eastern coast of Canada from the International Boundary in the Gulf of Maine northward to approximately the 60°N latitude off the coast of Labrador. The area of study amounts to at }east 500,000 square miles -an area roughly equivalent to 13 per cent of Canada's total land surface.

Jan 1, 1970

By Mateus Sotelo Menezes

A família de aços avançados de alta resistência – AHSS contempla uma variedade de materiais que são utilizados principalmente na indústria automotiva. Os aços bifásicos incluem-se nesta classe e são assim denominados devido a sua microestrutura composta por ferrita e martensita. Apresentam alta resistência mecânica associada à ductilidade, o que permite a aplicação de grandes esforços em pequenas áreas sem que ocorra fratura. Este trabalho visa verificar, através de caracterização metalográfica, ensaios de tração e anisotropia, as propriedades mecânicas do aço DP600 para trabalho a frio. A curva tensão-deformação de engenharia para este aço foi estabelecida através de ensaios de tração até a ruptura do corpo de prova. Foram obtidos valores médios de 330 MPa para o limite de escoamento, 589 MPa para o limite de resistência à tração e 20% de alongamento. Os índices de anisotropia também foram verificados através de ensaios de tração. Estes resultados foram comparados com valores encontrados na literatura. De um modo geral, as chapas ensaiadas resultaram em uma diferença de valores de aproximadamente 10%, possibilitando sua utilização a frio.

Aug 16, 2017

By C. Bryce

Rhenium is primarily recovered as a by-product from molybdenum roasting circuits. However, rhenium is also present in copper heap leach solutions at very low concentrations and represents a potential new rhenium source. Freeport-McMoRan Copper & Gold has developed a new process using carbon adsorption followed by ion exchange or solvent extraction to concentrate rhenium from less than 1 ppm to 15 g/L. The product is compatible as a feed to an existing rhenium processing plant. A pilot plant operated at Freeport-McMoRan?s Sierrita mine has demonstrated the technical and financial feasibility of this new process.

Feb 23, 2014

By N. Kanari

Kinetics of the carbochlorination of Cr2O3 has been studied with C12+CO gas mixtures between 500 °C to 900 °C using thermogravimetric analysis. The apparent activation energy is about 100 kJ/mol. Mathematical fitting of the experimental data suggests that the shrinking sphere model is the most adequate to describe the carbochlorination mechanism of chromium oxide and that is controlled by the chemical reaction. In the temperature range of 550 "C to 800 OC, the reaction order is about 1.34 and is independent of temperature. Changing the C12+CO content from 15 pct to 100 pct increases the reaction rate and does not affect the reaction mechanism. Similarly, changing the ratio of C12/(Cl2+CO) from 0.125 to 0.857 do not modify the carbochlorination mechanism of Cr203. In these conditions, the reaction rate passes through a maximum when using a chlorinating gas mixture having a Cl2/(C12+CO) ratio of about 0.5.

Jan 1, 1998

The Grants register 1979-1981, edited by Roland Turner. London, MacMillan, 1980. (Available from Geonicla Publications, P.O. Box 31487, Braamfontein 2017 at R31,37; price to libraries R28,33.) Buyer's guide. Pretoria, South African Bureau of Standards, 1980. (Available free of charge from the Director General, SABS, Private Bag X191, Pretoria 0001.) SABS specification on gold alloys. World coal resources, by Bernardo F. Grossling. London, Financial Times, 1980. 160 pp. $D.S.155. Resources policy, a quarterly journal publish d in March, June, September, and December. Annua subscription: £40. Diamond jubilee 1980 The Associated Scientific and Technical Societies was established in 1920 primarily to 'promote the interests of Scientific, Professional and Technical Societies, the advancement of knowledge in Scientific and Technical subjects, and to uphold the professional status of such Societies,' and to 'represent corporately the views of Scientific, Professional and Technical Societies and the members thereof'. In this manner the strength of unity

Jan 1, 1980

By Valerie Kollonitsch

Functional mineral pigments are used in large quantities in paint, paper, plastics, rubber, textiles, agriculture, and several other industries. U.S. consumption in 1969 is estimated at over 5 million tons a year, valued at nearly $150 million, as shown in Table 1. Originally extender pigments were employed only to lower cost. They were thought of merely as adulterants to replace more expensive prime pigments and binders. However, over the years their role has become better understood, and today their main functions are: - Increasing strength, stability, and service life. - Improving surface properties. - Enhancing application and processing properties. - Extending prime pigments. - Controlling viscosity and package stability - Lowering overall costs of the finished product. The principal minerals used as functional pigments are kaolin, ground calcium carbonate, talc, and asbestos. Other minerals include barytes, attapulgite, diatomite, mica, ground silica, wollastonite, and nepheline syenite. Several synthetic products, including precipitated calcium carbonate; precipitated, gel, and fumed silica; alumina trihydrate; and barium sulfate, compete with mineral products. They are more expensive, but often have more closely controlled particle size or other properties because they can be tailor-made according to the requirements. This paper covers only natural products selling for $10 or more a ton, approximately the lower limit for pigment grades. Data refer only to consumption in pigment applications. For example, such applications as filter aids for diatomite are not included. Key properties of the major mineral pigments are given in Table 2. It is important to note that these properties are primarily physical rather than chemical. In general, these products are sold to performance specifications for what they can do rather than on chemical composition specifications on what they contain.

Jan 1, 1969

By Afonso Garcez de Azevedo

As indústrias cerâmicas do Parque Industrial do Município de Campos dos Goytacazes-RJ utilizam como matéria-prima a argila oriunda das jazidas presentes na planície de inundação do Rio Paraíba do Sul. Os artefatos produzidos por essas indústrias, que são na sua maioria tijolos e telhas, apresentam propriedades provenientes das transformações que ocorrem na constituição mineralógica da matéria-prima após queima, bem como do processo de fabricação empregado. Com o intuito de melhor entender o processo de fabricação destes artefatos e como suas propriedades se desenvolvem, este trabalho pretende caracterizar e identificar os minerais constituintes de uma camada argilosa do Município de Campos dos Goytacazes-RJ, usando, para isso, técnica de Difração de Raios-X, e analisar as transformações térmicas ocorridas através de ADT/ATG/TG e microscopia óptica.

Oct 30, 2017

Over 45 of the Best Qualified Technical Specialists, Consultants, Engineers, Scientists, Explosive Supplies, Educators and Mine Operators in the World!

Jan 1, 2000

By C. O. Fairchild

ONE of the fundamental principles of efficiency is the use of adequate and permanent records. The rapid increase in the manufacture and use of recording pryometers is a proof of the appreciation of efficiency principles on the part of the manufacturers engaged in the various technical industries. Where recording pyrometers are not employed in an industry in which temperature measurements are necessary, one will generally find that a printed form is used upon which is written, periodically, the temperatures measured by an indicating instrument. It is no serious condemnation of the workman to state that such records are often "doctored," but it is rather a reflection upon the executive who puts such temptation in the way of a workman. One of the well-known "tricks of the trade" is to "force." a furnace so that it will be at the proper temperature during the periodic trips of the foreman or other official. Indicating instruments and recorders may be used together to great advantage. The recorder furnishes .a printed record and a check upon the operator of the furnace, and a record of value in correlating properties of the finished product with the heat treatment. The indicator should be of assistance to the operator in controlling the furnace or oven. Modern practice requires a temperature-recording instrument that is as simple as possible, rugged, reliable, and sufficiently accurate. Of these qualifications reliability is paramount, particularly in cases where the recorder is used for controlling the temperature automatically. By a reliable instrument is meant one that will run continuously with little attention and with a consistent degree of accuracy. That is, if it is in error by 5 per cent. one day, it must be in error by a like amount on any other clay, and not by 2 per cent. or 10 per cent. The earlier forms of recorders were complex and delicate, or mechanically unsatisfactory and inaccurate, and required considerable attention to keep them in operation. Within the past few years, however, the development in the manufacture of temperature recording devices has been highly satisfactory and many excellent instruments are now available. .

Jan 9, 1919

By J. R. Bhamidipati, Nagy EI-Kaddah

"Over the years, mathematical modeling has been established as a viable tool for design and analysis of melting and solidification processes. Modeling of electromagnetic casting and melting systems involves three coupled problems -- determination of the containment field, the shape of the meniscus, and the temperature field -- which have to be solved simultaneously. One of the difficulties in numerical simulation of these systems is in defining and gridding the solution domain as the meniscus shape of the liquid region is not known a priori. This paper describes a methodology for solving these coupled problems in a two-dimensional electromagnetic containment field. This method is based on the solution of the electromagnetic, free surface dynamic, and heat transfer equations in a fixed domain in computational space by mapping the physical space into an invariant computational space during the search for the equilibrium shape using a variable non-orthogonal coordinate transformation. This approach, also, eliminates the need for regridding the liquid and solid regions during phase change. This methodology is demonstrated for two electromagnetic confinement systems -- the Magnetic Suspension Melting process and the electromagnetic casting of aluminum. The model predictions are in good agreement with available data for these systems. It is suggested that the methodology presented here is likely to provide a useful tool in the design, analysis, and optimization of electromagnetic confinement systems. IntroductionDuring the past decade, mathematical modeling has emerged as a viable tool for the design, analysis, and optimization of casting and melting processes /1-2/. It is generally recognized that the usefulness of modeling to study the interplay between the various process parameters without resorting to extensive experimentation relies heavily on accurate representation of the physical phenomena in these systems. In modeling electromagnetic confinement casting and melting systems, it is important that the model address all aspects of electromagnetic field interaction with the metal, if accurate predictions are to be obtained /3/. The electromagnetic field affects the heat transfer phenomena primarily through joule heating. In addition, the electromagnetic forces play a key role in heat redistribution in the molten pool via melt stirring, and, in confinement systems, support the molten metal pool."

Jan 1, 1994

By C. F. Feng, L. Froyen

"In-situ processes have emerged as new and promising techniques for metal matrix composite fabrication. They offer significant technical and economic advantages over conventional processing. One of the in-situ processing routes that have been used is reactive free sintering of a mixture of powder reactants. However, materials synthesised via this route are always porous because of density differences between reactants and products. An example are the porous Al/(TiB2+Ah03) MMCs obtained by heating powder mixtures of Al+ Ti02+B with Ti02 and B in stoichiometric ratios for forming TiB2• In this study, porous Al/(TiB2+Ah03) composites were further processed by hot-pressing at temperatures above 600°C. This processing cycle was designed so that the composites could be densified. Furthermore, the reaction kinetics of the in-situ processing are studied by means of DSC analysis measured at different heating rates. The activation energies of the three intermediate steps that are involved in the reactive processing for preparing AV(TiB2+Alz03) MMCs are determined to be 923 kJ/mole, 241 kJ/mole and 235 kJ/mole respectively.XRD proved that the hot-pressed products consist of Al, TiB2 and Al203- Properties of the products are assessed by microstructural characterisation (LOM, SEM and EDS), microhardness, Young's modulus and bending tests. The results show that good microstructures, elastic properties and strengths, as well as acceptable ductilities were achieved. For the composition 79.74wt% Al-15.95wt% Ti0z-4.31wt% B, after the reactive free-sintering and hot-pressing cycles, Young's modulus is 105 GPa, bending strength is 509 MPa and maximum strain is 5.0%; for composition 88.73wt% Al-8.87wt% Ti0z-2.40wt% B, they are 89 GPa, 311 MPa and 8.2% respectively. It can be seen that the properties of products can be tailored by adjusting the relative amounts of reactants in green samples. Furthermore, for comparison reasons, Al and a binary system Al-Ti02 were identically processed as the ternary systems. Their microstructures and properties were studied."

Jan 1, 1998

By Michel Chouteau

"A very conductive zone was revealed in 1977 and 1978 by magnetotelluric (MT) measurements carried out near Ste-Mathilde, 6 km northeast of La Malbaie . In order to identify the structure causing the anomaly, thirty-five MT soundings were recorded in 1980 and 1981 on and around the conductor within a radius of4 km. Results confirmed that the conductor is of limited extent (less than 2 km by 0.4 km). The proposed model is a highly conductive vertical slab, the top of which is within 200 m from the surface. At a depth of approximately 825 m this structure joins a conductive layer which extends to the northwest but not to the southeast. The large conductivities and the depths involved can only be explain ed by a fractured zone flooded with electrolytic solutions, by graphite veins or by metallic mineralization (sulphides). The former seems to be the most likely hypothesis because an EW fault running across this zone could have allowed percolation of water and the leaching of disseminated pyrite out of a mylolisthenite filling the fault.IntroductionLa Malbaie is located 130 km northeast of Quebec City on th e North Shore o f the St. Lawrence River (Fig. I). Four major groups o f rocks have been mapped in this area: charnockitic rocks to the west , granitic rocks in the north east and southeast, gneiss and pegmatites northwest and south of La Malbaie , and Paleozoic sediments in the Clermont-La Malbaie Valley and along the shore of the St. Lawrence River (Rondot, 1966). Two major features dominate the structure of the region: Logan ' s line , a major thrust fault beneath the St. Lawrence which separates the Grenville Province to the north from the Appalachian regime to the south, and the Charlevoix Crater , a large Paleozoic impact crater that created an almost perfect annula r structure centred on Mont des Eboulements (Rondot, 1970). Ste-Mathilde is a village lying 6 km northeast of La Malbaie, just outside the ring-like graben zone caused by readjustments after meteorite impact. The survey area spreads over a granite body which is more than 2 km long and 0.6 km wide, surrounded by a wide migmatite zone which is injected by many bodies of pegmatite, the latter likely related to the granite body (Fig. 2). A zone of leptynites lies west of the area. An east-west trending fault (FA1) related to the Charlevoix Crater runs mid -way across the survey area; a second parallel fault (FA2) south of FAI separates the gneissic rocks from the Paleozoic sediments. The overburden is usually thin with outcrops frequently encountered except for the centre of the survey are a where 10 m of glacial sediments are expected (E. Gaucher, 1982, personal communication)."

Jan 1, 1985

By Saulo Brinco Diniz

O presente trabalho faz a caracterização microestrutural e mecânica da liga de alumínio 3105 submetida a duas técnicas de Deformação Plástica Severa (NECAE - Extrusão em Canais Não-Equiangulares, e Laminação Assimétrica), a fim de se eleger entre as duas técnicas a melhor para se obter uma microestrutura mais encruada e refinada. As avaliações microestrutural e mecânica foram feitas por Difração de Raios-X (DRX), análise dilatométrica e ensaio de dureza Vickers, as quais permitiram avaliar de forma indireta o grau de encruamento / refinamento da estrutura resultante de cada processo de Deformação Plástica Severa, avaliando o incremento de dureza, perfil do pico de DRX e temperatura de início de recristalização. Conclui-se que a técnica mais efetiva no encruamento/refinamento da estrutura foi a Laminação Assimétrica, tendo em vista a geometria adotada na técnica de NECAE.

Aug 7, 2018

By H. EI-shall

In this paper, the results of bench scale testing of five different flotation processes to separate dolomite from phosphate are discussed. The effectiveness of each process interms of phosphate recovery and MgO content in the concentrate is used together with the reagent consumption as the basis of comparison. The water quality is found to play a major role in the performance of these processes. Effect of water hardness as well as other parameters are discussed.

Jan 1, 1995

La incidencia de silicosis en algunos asientos mineros, conlleva la necesidad de un estudio evaluativo del departamento de Higiene industrial sobre aquellos yacimientos situados a 4000 m.sn.m, para determinar las condiciones del medio ambiente y estado de salud de sus 200 trabajadores. Por tal motivo, el presente trabajo señala el proceso de adquisición sobre la enfermedad durante la estadía del trabajador en la mina, y su posterior evolución, pese a las medidas preventivas. Las condiciones ambientales para el desarrollo de la silicosis son el terreno cuarcífero y los lugares de ventilación ventilación deficiente, donde el término medio de partículas de polvo encontradas fue de 0.7 a 1.15, incidiendo particularmente en el operador de lampa. Para ello, se recomendaron medidas preventivas como la adecuada ventilación de los frontones, la omisión inicial de la perforación en seco, el uso de respiradores adecuados para las trabajadores y el empleo de un mejor equipo para la ventilación de los stops. Sin embargo, los resultados obtenidos del proceso, no ofrecieron mejoras sobre el avance de la enfermedad, situándola en un primer estadío con 7.0% en comparación con otras enfermedades. Después de un periodo de 7 años, el departamento de Higiene industrial, nuevamente reevalúa este estudio, encontrando resultados similares con los anteriores, sin reparar en las recomendaciones sostenidas. Así, de los 200 trabajadores examinados, se conoce el estado actual de 103, de los cuales 97 trabajadores tienen silicosis sin determinar aún su estado de su evolución. Luego, en 1956 se diagnosticó que el 27.3% de trabajadores silicosos, evidenciaba un porcentaje considerable en el primer estadio y una dismimución en el estado de sílico-tuberculosis. Por consecuencia, se necesita mejorar no solo las condiciones del ambiente del trabajador, sino eliminar las jornadas laborales de 12 horas de trabajo en subsuelo. Así como la evaluación periódica, integral, radiográfica del estado del trabajador por medio de un personal médico altamente capacitado.

Jul 20, 1957

By Robson Leandro Silva

O processo de descarburação de aço inoxidável contendo alto teor de carbono inicial via processo VOD foi estudado utilizando o aço AISI 304. Devido a questões operacionais, o carbono inicial aplicado no processo VOD da Villares Metals é próximo a 1% e a pressão de trabalho de 600mbar. O objetivo do trabalho foi encontrar o instante em que se torna possível a redução da pressão do sistema de acordo com o carbono inicial do processo. Para isso foram realizados testes em corridas industriais de 25 t interrompendo o sopro de oxigênio e realizando análise química em diferentes tempos de sopro. O resultado dos testes mostrou que após 11min de sopro de oxigênio é possível reduzir a pressão do sistema levando em consideração as limitações operacionais, podendo assim reduzir a oxidação de elementos de liga durante essa etapa.

Oct 30, 2017