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By Marcio José Cuccolo Rosales

A soldagem por brasagem a vácuo promove a união de materiais dissimilares com alto valor agregado. Este trabalho visa estudar a interação química do nitreto de boro hexagonal (h-BN) na interface de ligação brasada do par Kovar®/h-BN. As variáveis de processo são determinantes para formação da junta brasada metalurgicamente estável. O trabalho estuda a molhabilidade do h-BN quando em contato com ligas de adição do sistema eutético Ag-Cu durante a solidificação. Foram conduzidos ensaios no h-BN a fim de caracterizar sua aplicação no sensor de posição do feixe de elétrons (BPM) do projeto do Sirius, e as propriedades que influenciam o seu processamento durante a brasagem, como coeficiente de expansão térmica e molhabilidade superficial. Os ensaios de brasagem com a liga Ag-Cu-4,5Ti, mostraram boa molhabilidade e espalhamento na superfície, favorecendo a formação da junta sem descontinuidades. As reações na interface são complexas no sentido de formação de novas fases e intermetálicos e, influenciadas pela seleção dos materiais, que possuem diferentes temperaturas de fusão e coeficientes de expansão térmica. Os resultados indicam que a seleção da liga com Ti, que é o elemento de ativação, promove a interação na superfície do h-BN com os demais materiais da junta.

Oct 30, 2017

By Thiago Augusto Ávila

A limpidez de aços e a diminuição de problemas de lingotabilidade em aciarias tem sido alvo constante de esforços de engenheiros na siderúrgica. O bom entendimento dos efeitos do processo e as suas respectivas particularidades garantem a redução de ocorrências de inclusões e má lingotabilidade. Dentre os principais aços de construção mecânica com maior ocorrência de problemas de inclusões e lingotabildade estão os aços “Baixo Si” e aços com faixa de S e acalmados ao Al e Si/Mn. Entre os parâmetros de análise, a ordem de adição de ligas, definição de temperatura de lingotamento e a estabilidade térmica e química, são os de maior influência na quantidade de inclusões e problemas de lingotabilidade. Para aços baixo Si, a pré-desoxidação com Al, auxiliada por maiores temperaturas de lingotamento, confere inclusões líquidas no inicio do processo promovendo a maior remoção destas. Da mesma forma, aços com S e Al são beneficiados pelo aumento da temperatura de lingotamento, mas fortemente afetados pela estratificação térmica do aço na panela, quando é elevado o teor de S e Al nestes. Sendo assim, o tempo de espera e o estado térmico da panela e distribuidor passam a ser um fator importante para redução da estratificação térmica bem como a redução de problemas com macroinclusão e má lingotabilidade.

Jul 30, 2018

By E. P. Ferrero

Crude oils from fields throughout the world are analyzed by the Bureau of Mines to determine the characteristics of the oils and their contribution to the petroleum resources of the world. Analyses are reported for 169 foreign crude oil samples from 122 oilfields in Africa, Asia, Australia, the Caribbean, Europe, North America, and South America. Tables show the geographic and geo- logic origin of the samples, names of companies that supplied the samples, annual production for the fields, general characteristics and analytical and computed data, hydrocarbon-type data, cumulative production of the larger fields, and references to sources of geological and field development information. The analyses were made by the Bureau of Mines routine method and comparisons may be made with more than 8,000 other such analyses.

Jan 1, 1972

By R. L. King

This report describes a method for designing and constructing ground beds that has been developed under the sponsorship of the Bureau of Mines. The procedures for designing and constructing a driven-rod ground bed with a resistance of 5 ohms or less are given. Some of the theory of soil resistivity and fall-of-potential resistance measurements is included. Results of a bed constructed at the Bureau of Mines mine car roadway are presented.

Jan 1, 1978

By Mervin D. Marshall

A quick-reaction, mine permissible rescue vehicle (MERV) was developed for use by rescue teams. The MERV is a 6-wheeled, battery-powered unit with life support equipment and instrumentation; designed for a two-man team, with provisions for handling two victims or tools in a trailer. The vehicle is 100 inches long, 56 inches wide, and maximum height of 34 inches. It can be lowered down most mine shafts and has clearance to travel mine railways. The vehicle has power to all six wheels with power transmitted separately to either or both sets of wheels. Low-pressure, high-traction tires give the vehicle the ability to handle soft, muddy mine floors, flooded areas and significant obstacles, and can negotiate a 45% grade. Power and life support are sufficient for a 4-hour mission. The life support system is a commercially-available, approved unit currently used by MESA rescue personnel. A payout wire system provides communication between the vehicle and home base over a distance of 10,000 feet. On-board monitoring of carbon monoxide, methane and oxygen is provided, with master and individual alarms to warn of gas concentrations outside pre-set limits. A lightweight, water-tight trailer was developed for carrying victims or hauling tools and equipment.

Jan 1, 1979

By Josué Mesquita de Souza Junior

A concentração gravítica corresponde a uma das mais antigas e importantes formas de processamento mineral, sendo utilizada para beneficiar uma grande variedade de minérios. Neste contexto, a melhor maneira de investigar e prever resultados de processos gravíticos é a chamada “curva de lavabilidade”. Estas curvas apresentam a distribuição das partículas de um dado um material segundo as suas densidades e são construídas a partir de dados experimentais obtidos nos denominados testes de flutua-afunda. Para a realização destes testes são utilizados líquidos com diferentes densidades, os quais correspondem a substâncias muito tóxicas, voláteis, de difícil manuseio e, na maioria dos casos, muito caras. Além disto, por não existirem líquidos com densidades muito elevadas, os mesmos não podem ser usados no fracionamento de sulfetos ou óxidos metálicos, o que restringe o uso das curvas de lavabilidade a materiais leves. Pensando nisto, procedeu-se ao desenvolvimento do presente trabalho, cujo objetivo é apresentar uma nova metodologia para a construção das curvas de lavabilidade a partir da análise de imagens digitais. Com esta metodologia será possível construir curvas de lavabilidade de uma maneira mais rápida e segura, além de tornar possível a aplicação desta ferramenta para minérios que possuam partículas com densidades mais elevadas.

Aug 17, 2017

By H. H. Wade, N. F. Schulz

The large quantities of iron-bearing materials, including taconite, semi-taconite,* and other low-grade ferruginous materials occurring in Minnesota and elsewhere, constitute an important potential source of iron. Satisfactory grade and recovery of iron ore concentrate cannot ordinarily be obtained from these ferruginous materials by simple methods of beneficiation. Iron is distinctive in that the free metal and two of its oxides [magnetite (Fe2O3) and maghemite (gamma-Fe2O3) ] are strongly ferromagnetic. The successful magnetic separation of natural magnetite from taconite has already been established on a commercial scale. The iron in semi-taconite, however, occurs largely as goethite (Fe2O3-H4O) and hematite (Fe2O3) which do not respond to ordinary magnetic separation methods. Magnetic roasting converts these iron oxides to magnetite, which can, after liberation, be magnetically concentrated. MAGNETIC ROASTING Hematite undergoes a stepwise reduction when exposed at moderately elevated temperatures to a reducing atmosphere containing hydrogen or carbon monoxide: Fe2O3? Fe3O4 ? FeO ? Fe Since the desirable product in magnetic roasting is Fe3O4, the conversion is halted after the first stage by controlling the reduction potential of the gas mixture with water vapor or carbon dioxide. The reducing gas mixture must be such that the oxygen partial pressure at the solid-gas reaction interface will be maintained intermediately between the oxygen partial pressures in equilibrium with Fe2O3 and Fe3O4 at the prevailing temperature. Because of the rapid increase in decomposition pressure of Fe3O4 with increase in temperature, the practical upper limit of useful reaction temperature is about 1400°F, above which over-reduction usually occurs in atmospheres containing hydrogen or carbon monoxide. On the other hand, useful reaction rates usually occur only above 800°F. Goethite reacts similarly except that the combined water probably has to be driven off thermally before the reduction to magnetite occurs. Iron carbonate must also be decomposed thermally to an oxide before conversion to magnetite. Iron silicates are apparently not amenable to magnetic roasting. The rate of penetration of the reaction toward the interior of a given ore fragment is dependent on the chemical composition and physical structure of the solid. Most ore fragments tested here reduced satisfactorily to 1/4-in. depth in less than 14 min at 1200°F. Some very dense fragments, however, were reduced to less than 1/32-in. depth under the same conditions. Determination of the optimum temperature, gas composition, ore fragment size, or time of exposure

Jan 1, 1961

By R. S. Bowman, G. S. Austin, J. M. Barker, P. S. Freeman

The physical, chemical and mineralogic characteristics of zeolites allow commercially important applications. While adoption of zeolite technology is slow in the United States compared to other regions of the world, continued testing and research has shown a wide range of uses for these minerals. They are important catalysts in petroleum refining, molecular sieves able to separate gases, and chemically inert carriers of reactants. The zeolite clinoptilolite produced by St. Cloud Mining Company (clino) (SC) is used in animal hygiene and animal feed, especially concentrated animal feeding operations (CAFOs), horticulture, water treatment, floor dry, aquariums, air and other filters, and odour control. Clino can remove cations from solution, and surface-modified zeolite (SMZ) is a sorbent for the removal of anions and neutral organics from water. Specific clino applications are: control of chemical pollution in groundwater, removal of organic compounds from oil field waters, and elimination of pathogens from sewage effluent. Combining the sorption capabilities of SMZ with chemical or biological transformations can yield complete removal of toxic materials from contaminated water. Continued development and marketing of zeolite products will be a growth market far into the future. The CAFO market for zeolites is the most significant growth area in the United States over the next few years. SMZ, currently less than 1% of St. Cloud sales, will continue to gain market penetration for many years.

Jan 1, 2004

By Guo H. Lei

Over the last four decades, barrettes have been ever-increasingly adopted as the foundations for tall buildings and heavy infrastructure projects all over the world. Many findings have been gained from practical applications and theoretical researches. In this article, a collection of literature is reviewed on the installation effects and load-carrying behaviour of barrettes derived from field and laboratory tests and theoretical studies. It covers many aspects, such as the ground deformations and stress changes caused by the installation of barrettes, the shaft resistance mobilisation behaviour, the construction effects on the shaft resistance, and the effects of pile spacing, pile shape and pile group layout on the load-carrying behaviour of barrettes.

Jan 1, 2006

For tax purposes a mining company is a New Zealand company whose principal source of income is from the business of mining, or exploring for certain specified minerals in New Zealand. New Zealand tax law distinguishes between a non-resident mining operator and a mining company, with the only major difference in tax treatment being the corporate tax rates. New Zealand mining companies are taxed at 28 per cent, whereas non-resident mining operators are taxed at 33 per cent of taxable income. These provisions also apply to the petroleum mining industry. Individuals who carry on the business of mining are also specifically defined in the Act. They are termed as 'resident mining operators'. Non-resident mining operators are non-residents of New Zealand who carry on mining ventures as a business in New Zealand. Mining ventures are defined as the exploring, searching and mining of specified minerals, including development work carried out for profits. Similar provisions apply to the petroleum mining sector. Specified minerals are defined in the Income Tax Act 1976 ('the Act') and while no useful purpose is obtained by listing them in the paper, they include a larger number of industrial and commercial minerals. The Minister of Finance is also empowered to add to the list by publishing his determination in the Gazette.

Jan 1, 1988

The method of investigation was to study the distribution of ore in great detail, to make a thorough structural study of the lode and the mine area, and then to compare the results of the two studies. Such a comparison usually reveals a very close relationship between geological structure and ore distribution, and can often lead to important conclusions which would not be reached in the ordinary working of a mine.The Triton mine lies 30 miles E.N.E. of Cue, or 380 miles N.W. of Kalgoorlie, in typical pre-Cambrian rocks, consisting of gTeenstone lavas and tuft's, interbedded with slates and some sediments, and intruded by granite and porphyry. Fig. 1 (at end of paper) is a longitudinal section of the mine and shows that the workings consist of the main North Emu and the smaller South Emu, separated by a distance of about 1 of a mile. Both orebodies occur on the same lode, which strikes north and south and dips practically vertically. On the same line, and of 1/2 a mile and a mile respectively to the north of the North Emu, are the small Rand and North Rand workings, where a big width of lode material has proved to be very low grade. In the North Emu the lode width averages 12 to 15 feet; it is seldom less than 5 feet and in places reaches 30 feet. In the South Emu the lode is wide, but only portion of it is payable.The lode is a mineralised bed occurring between massive lava flows on the east and a mixed series of tuft's and thin lava flows on the west. The lode material is hard, fine grained, and dark coloured, and generally has a faint banding which is believed to indicate a tuft'aceous origin of the original lode rock. Microscopic examination shows that the original lode rock has undergone considerable albitisation;' there has also been considerable formation of biotite which gives the lode material a characteristic sheen. The mineralisation consists of abundant fine pyrite, which is auriferous, and a lesser development of pyrrhotite which is, however, barren of gold.THE OREBODIES AND THEIR CHARACTERISTICSThe distribution of ore is best studied from gold contours, as these reveal features that cannot be detected in an ordinary assay section. Gold contours (see Fig. 3) are developed' by plotting the width and grade of all development and stoping assays throughout the mine on a longitudinal projection, representing each sample by a coloured dot according to a suitably chosen range of assay values, and then outlining areas of similarly coloured dots (see H. J. C. Conolly, Econ. Geol., April, 1936). Both width and grade must be taken into account and the simplest method of gold contouring is to use dwt.lft. values, but difficulties arise here with big widths of low grade and small widths of high grade ore. To choose an extreme case, 30 ft. of 2 dwts. and 2 ft. of 30 dwts. both equal 60 dwts.lft., and would therefore be given the same value in dwt.lft. contouring...

Jan 1, 1943

By G. E. Agar, W. B. Kipkie, V. K. Drylie

"This paper describes mineral processing test work on drill core samples from an ilmenite deposit in Terrebonne County just north of Montreal.Mineralogical examination showed that the intimate associa¬tion between ilmenite and hematite precluded their separation. The maximum concentrate grade was therefore limited to 22.9% Ti. Liberation of gangue from the hemo-ilmenite grains occurred around 400 µm, a size which proved to be too coarse for recovery by flotation.Other physical separation techniques, such as elec¬trodynamic, magnetic and jigging, were tried in order to take advantage of the relatively coarse liberation size. An all-flotation procedure and a combination of jigging and flotation yielded similar separations.IntroductionInco Metals Company, through its subsidiary Canico, optioned an ilmenite deposit in Terrebonne County, just north of Montreal, and conducted a drilling campaign to confirm previous geological assessments of the deposit and to provide core samples for mineralogical study. Parts of these core samples were used for mineral processing studies, which will be described in this report. The objective was to identify suitable upgrading procedures, to determine the optimum combination of concentrate grade and recovery, and to provide suitable batches of concentrate for further treatment."

Jan 1, 1980

By R. G. Turner, M. G. Hubbard, A. E. Dukler

Gas phase hydrocarbons produced from underground reservoirs will, in many instances, have liquid phase material associated with them, the presence of which can affect the flowing characteristics of the well. Liquids can come from condensation of hydrocarbon gas (condensate) or from interstitial water in the reservoir matrix. In either case, the higher density liquid phase, being essentially discontinuous, must be transported to the surface by the gas. In the event the gas phase does not provide sufficient transport energy to lift the liquids out of the well, the liquids will accumulate in the wellbore. The accumulation of the liquid will impose an additional back pressure on the formation that can significantly affect the production capacity of the well. In low pressure wells the liquid may completely kill the well; and in the higher pressure wells there can occur a variable degree of slugging or churning of the liquids, which can affect calculations used in routine well tests. Specifically, the calculated bottom-hole pressures used in multirate backpressure tests will be erroneous if the well is not removing liquids on a continuous basis, and gas:liquid ratios observed during such a test may not be correct. Several authors1,3,8,14 have suggested methods to determine if the flow rate of a well is sufficient to remove liquid phase material. Vitter14 and Duggan' proposed that wellhead velocities observed in the field would be adequate for keeping wells unloaded. Jones8 and Dukler3 presented analytical treatments resulting in equations for calculating, from physical properties, the minimum necessary flow rate. An analysis of these studies indicates the existence of two proposed physical models for the removal of gas well liquids: (1) liquid film movement along the walls of the pipe and (2) liquid droplets entrained in the high velocity gas core. Although there probably is a continuous exchange of liquid between the gas core and the film, they will be treated separately for the purposes of this study. The development and comparison of these separate models with experimental data will permit the determination of which, if either, is the controlling mechanism for the removal of liquids from gas wells. The Continuous Film Model Liquid phase accumulation on the walls of a conduit during two-phase gas/liquid flow is inevitable due to the impingement of entrained liquid drops and the condensation of vapors. The movement of the liquid on the wall is therefore of interest in the analysis of liquid removal from gas wells. If the annular liquid film must be moved upward along the walls in order to keep a gas well from loading up, then the minimum gas flow rate necessary to accomplish this is of primary interest. The analysis technique used follows Dukler2 and Hewitt5 and involves describing the profile of the velocity of a liquid film moving upward on the inside of a tube. The minimum rate of gas flow required to move the film upward is then calculated.

Jan 1, 1970

THE following really forms the second part of, or a sequel to, a paper, " Ventilating Metalliferous Mines: a Method of Attack," read before the Broken Hill Branch of the Australasian Institute of Mining and Metallurgy in May, 1920. In that paper the writer advocated a consideration of the question of ventilation in metal mines from a different aspect to that 'which had hitherto prevailed locally. Various factors regarded as having an important bearing on the subject were set forth, together with the results of observations made during ventilation tests carried out at the mining department of the Zinc Corporation.During the subsequent discussion the question was raised of the possibility of any practical application of the method of attack described, and also whether the theoretical considerations mentioned were likely to be of any real utility to the mining engineer engaged in ventilation work in a metalliferous mine.

Jan 1, 1923

By I. L. Nichols

The Bureau of Mines is investigating vanadium recovery from various domestic resources. A low-grade carnotite ore sample containing 0.34 pct V20S and 0.04 pct U30S was leached, and the results were compared with those of similar leach tests using a mill-grade sample containing 1.26 pct V205 and 0.19 pct U308. Experiments on the two ore samples included agitation leaching, pugging, salt-roast leaching, and autoclave leaching. None of the leaching methods investigated showed any significant advantage over another except autoclaving, which reduced the leach time but at the expense of greater acid consumption. Typical of the experimental results attained are the data gathered from the agitation leaching tests. Agitation leaching of the mill-grade ore with 100 lb/ton H2S04 resulted in extractions of 94 pct U308 and 33 pct V205. To increase the vanadium extraction from 33 to 91 pct required concentrations of 300 lb/ton H2S04 and 10 lb/ton NaC103. Complementary agitation leach tests on the low-grade ore required 200 lb/ton H2S04 to extract 94 pct U308, and 300 lb/ton H2S04 and 10 lb/ton NaC103 to extract 90 pct V205.

Jan 1, 1983

By Mao Bai

In predicting the integrity of under-mined structures, surface horizontal displacements and curvatures are frequently of greater importance than the more homogeneous vertical displacements. Accurate evaluation of mining induced subsidence and horizontal displacement further requires that the predictive model adequately represents the subsurface geology, mining geometry and extraction sequencing. The following documents an extension of the Subsidence Prediction and System Identification method (SPASID) to the evaluation of horizontal strains. Comparisons are made between predictions from SPASID and two other empirical methods against measured data from a case study. The system identification method is illustrated to predict horizontal displacements and strains most consistently with the in situ data.

Jan 1, 1989

By Sávia Cristina Lacerda Poubel Pinheiro

A cada sequencial iniciado, as primeiras toneladas de aços que caem no distribuidor podem ser contaminadas pelos refratários, bem como pelo oxigênio do ar. Na Aciaria da Vallourec Soluções Tubulares do Brasil (VSB), em Jeceaba, desde o start up tem-se como prática o sucateamento de aproximadamente 17 toneladas de aço no início de lingotamento, com o objetivo de minimizar problemas de qualidade no tubo devido fornecimento de barras com baixa qualidade. Neste contexto, estudos foram realizados para avaliar a qualidade destas primeiras barras de primeira corrida do sequencial, com foco em barras de diâmetro de 310mm. A avaliação compreendeu a análise do teor de oxigênio total ao longo da primeira barra e qualidade de tubos laminados provenientes das mesmas. Os resultados indicaram que parte da primeira barra apresenta boa qualidade para ser aplicada na laminação de tubos, reduzindo o sucateamento de barras de início de lingotamento em 7 t.

Oct 30, 2017

By Madan B. Karkee

The understanding and the development of sound theoretical basis concerning the pile foundations has been phenomenal during the past few decades, considering the thousands of years the piles have evidently been in use. The importance of the quality assurance and the need for verification of load bearing capacity is being further reinforced rather than undermined by these developments. This is evidenced by significant developments made in the pile load test technology in recent decades, making it possible to make judicious selection of a test method, or a package of test methods, suitable for a given situation. The selection depends on the objective of carrying out the test and the reliability desired. Presently, the possible selection ranges from dynamic to static methods. The extent of dynamic effect in a test can be reckoned based on a dimensionless parameter defined as the 'relative duration'. Examples of different load tests are given for illustration of the different methods currently in use.

Jan 1, 1997

"Guests and Members of the Rocky Mountain Coal Mining Institute: "It gives me a great deal of pleasure to call the Fifty-Second regular meeting to order this morning. "I think that you will agree with me that we have an excellent program planned for the next three days, comprising various interesting and educational subjects by authors of prominence, which will be of keen interest to all of us in the coal industry. "The Program Committee, chairmanned by John Peperakis, has done an excellent job in securing this very splendid talent for our convention. "I would like to say a word as to the, condition of the coal industry in our part of the country as well as elsewhere. I believe we can look at it with more optimism than in the past several years, particularly in the state of Colorado, with which I am more familiar. "Annual coal production in Colorado gradually dropped from around 12 million tons during the years of World War I to as low as 8 million tons during the last war, and to less than 3 million tons in the year of 1954. We believe that it touched bottom that year, as in 1955 the state production went up again to nearly 3,400,000 tons, equivalent to an increase of 15%. As you know, the national increase in bituminous coal production for the year of 1955 was roughly 2000 over 1954. "The national increase for the first two months of 1956 over the same period of 1955 is approximately 2100. Colorado's production is running around 1000 over the comparable period of last year, and the 5 states represented by our Institute came up with a nice increase in 1955 over 1954 of 1000. "Figures on the increase so, far in 1956 for this group of states are not readily available, but I fully believe that. our industry locally, as well as nationally, is now starting out on a steady rise despite the fanfare of nuclear energy and its more glamorous competitor, solar energy. Many authorities tell us that real competition from these sources is a long way off and that the atomic energy program will consume far more coal than is displaced by nuclear power. "I do not mean to infer that we coal people are out of the woods by a long way' so far as holding and regaining markets, for our coal. The captive operators, which are well represented here, have not lost their market for coking coal, since coke is still a necessary

Jan 1, 1956

By Brad R. Blair

This paper will review impacts on longwall design and ground stability assessment due to advances in mine automation and sensing technology. Several new approaches to the prediction and monitoring of longwall panel and gateroad stability have recently become mature, and are ready for application in problematic ground control situations. These methods are revealing significant detail regarding deformation and failure mechanics of critical underground structures. Examples of how these technologies have worked successfully will be given, and applications for the use of these tools for cost-effective engineering design and monitoring will be suggested.

Jan 1, 1996