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By Lucas Teixeira Costa

A crescente demanda por aços ultrabaixo enxofre em usinas integradas a carvão mineral tem levado a esforços para reduzir o teor de enxofre no gusa e no aço. Todavia, a falta de uma visão integrada dos processos acarreta em otimizações isolados que nem sempre contribuem para uma efetiva redução de custos e aumento de produtividade final. No presente trabalho, foi construído e validado um balanço de massa capaz de realizar uma previsão do teor de enxofre de final de sopro a partir das entradas iniciais de enxofre na carga metálica e nas adições de fundentes. Para isso, considera-se que ocorre transferência de enxofre entre as fases, segundo seus teores e o coeficiente de partição de enxofre. A raspagem de escória de tratamento de gusa deve ser feita com muito cuidado para promover a melhor remoção da camada sobrenadante e ao mesmo tempo evitar perdas no rendimento metálico no processamento do aço. Utiliza-se o teor de enxofre do gusa carregado no LD como o principal parâmetro de controle, e recomenda-se que seu teor seja superior a 20ppm, uma vez que o esforço necessário para reduzir para teores abaixo desse limite será totalmente perdido no LD, devido à reversão durante o sopro.

Aug 17, 2017

By Amanda Martins Fernades

O presente trabalho tem como objetivo estudar a influência da adição do rejeito de pó de balão nas propriedades mecânicas do concreto destinado à fabricação de pavers, visto que a indústria da construção civil é a maior responsável pela geração de resíduos, sendo responsável pelo consumo de aproximadamente 40% dos recursos naturais extraídos. Sendo assim, o rejeito foi analisado granulometricamente por peneiramento e foram feitos dois traços, um denominado traço referência e o outro denominado traço substituído, sendo este último com adição de 4% em massa do pó de balão. A partir dos traços calculados foram moldados corpos de prova e avaliados a resistência à compressão destes. Os corpos de prova moldados a partir do traço substituído exibiram maior resistência à compressão tanto na idade de 7 dias quanto na idade de 28 dias, quando comparados aos corpos moldados a partir do traço referência. Esse incremento na resistência mecânica é justificado pela distribuição granulométrica do pó de balão, que por ser constituído em sua maior parte por finos inferiores a 0,15mm atua preenchendo vazios, reduzindo zonas de transição interfacial e formando uma microestrutura mais refinada.

Aug 17, 2017

By Alexandre Aparecida Morais

O rompimento de pele (breakout) é considerado uma das anomalias mais danosas ao processo de lingotamento contínuo de placas de aço. Esta ocorrência, além dos riscos de segurança durante a limpeza do aço derramado, resulta em pesadas perdas de produção e danos aos equipamentos. Estima-se que o custo potencial de um rompimento de média intensidade possa atingir a cifra de US$270.000,00, considerando a perda potencial de produção, o custo de reprocessamento do material e a recomposição dos equipamentos como segmentos, moldes, etc. Portanto, tão importante quanto evitar o breakout é também reduzir as suas consequências. Dentro deste contexto visando mitigar os danos de um rompimento quando o vazamento não é imediatamente reconhecido, desenvolveu-se um sistema pneumático de detecção de vazamento na saída do molde, envolvendo os edge e foot rolls. Basicamente, o sistema é um circuito fechado constituído de tubos de pequeno diametro com gás nitrogenio pressurizado. Se ocorrer um vazamento de aço, este funde o tubo (provocando perda de pressão ou excesso de vazão) ativando o sistema de alarme de indicação de vazamento, que fecha automaticamente a válvula gaveta do distribuidor para o veio e coloca a placa em extração. Atualmente todos os moldes da ArcelorMittal Tubarão possuem este sistema visando mitigar as consequencias de um vazamento.

Aug 17, 2017

By E. S. Longfellow, S. H. Katz

Poisonous hydrocyanic acid gas (HCN) is sometimes evolved in dangerous quantities from cyanides used in metallurgical and chemical operations. This gas is much used for fumigating buildings, ships, greenhouses, and such commodities as grain and cotton to destroy rats, mice and insect pests. Wherever cyanide fumes are evolved, thorough ventilation is necessary in order to render the sur- rounding air safe to breathe. Many persons have been killed by entering tanks and fumigated places too soon, and a simple test for this gas would promote safety. In view of the need for an easy method for quantitatively determining HCN in air, the three color reactions used originally for testing HCN in solution tions *** were modified and adapted. The reactions employ (1) picric acid (CH(NO2)3OH) which is yellow but combines with hydrogen cyanide to form a red- purple dye, isopurpuric acid****; (2) phenolphthalin (CH1604), which is a reduc- tian product of the phenolphthalein (CH4) used for acid indicator, this colorless substance is oxidized***** by presence of HCN to pink colored phenolph- thalin; and (3) guaiacum which oxidized from colorless to blue******. Phenolph- thalin and guaiacum require the presence of copper compounds which catalize the color formation by reduction of cupric cyanide. The chemical processes involved *Associate physical organic chemist, Bureau of Mines, Department of the Interior. **Assistant gas chemist, Bureau of Mines, Department of the Interior. 2014 20 *** Kohn-Abrest, E., Notice toxicologique sur les gas: Arnales des Falsifica- tions, vol. 8, 1915, pp. 215-35. (Tested air with picric acid and guaiacum papers). **** Élasiwietz, H., Ueber eine neue Zersetzungsweise der Trinitrophenylsaure: Anal. der Chemie, vol. 110, 1859, pp. 289-303. ***** Weehuizen, F., Phenolphthalin as reagent for HCN: Pharmaceutrisch weekblad, Utrecht, vol. 42, 1905, pp. 271-2. Abstract, Jour. Chem. Soc., vol. 88, part 2, 1905, p. 489. ****** Schonbein, C. F., Ueber den thatigen Zustand der Helfte des in dem Kupfer- oxydenthaltenen Sauerstoffs und ein darauf beruhendes hochst empfindliches Reagens auf die Blausaure und die loslichen Cyanmetalle: Jour. fur. Praktische Chemie, vol. 106, 1869, pp. 263-70.

Jun 1, 1923

Jan 1, 1963

By L. L. Wyman

THE resultant embrittlement caused by the exposure of oxygen-bearing copper when hot and exposed to reducing gases has been the subject of many studies.1 Little attention, however, has been given to the possible embrittling effects due to atmospheres or conditions that under some circumstances might be the source of a reducing gas. At rather infrequent intervals there occur reports of copper becoming embrittled during normal annealing cycles in commercial steam-atmos-hered furnaces such as customarily are used for this operation. As might be expected, several other factors exist-such as oil, dirt on the wire, or in the furnace, or metallic surface contacts that might produce reducing gases and be the source of the trouble. However, in consider-ation of the statement made by Ruder,2 it would seem that under some conditions steam itself might prove to be the source of trouble. A consideration of the amount of the dissociation of water vapor up to temperatures of the melting point of copper shows that' the amount of hydrogen that could come from this source is far too minute to account for any embrittlement. What such information does not tell is what will happen at the surface of copper when subjected to steam at elevated temperatures, for entirely different conditions may persist, which would account for Ruder's observation. Furthermore, there are no data as to what might happen at the surfaces of other materials present, the result-ant of which might affect the condition of the copper present. For this reason, it was decided to make a series of experiments com-parable to those previously conducted by the writer,1 which would clarify the effect of the steam on copper, and in copper in the presence of steel.

Jan 1, 1940

By Marina de Menezes Lopes

Sabe-se que a presença de ultrafinos em plantas de beneficiamento de minérios pode comprometer a eficiência dos processos principalmente os de flotação, uma vez que fenômenos como o slime coating e o arraste hidrodinâmico das partículas ocorrem fortemente. Além disso, concentrados contendo uma proporção significativa de ultrafinos terão dificuldade de serem filtrados gerando tortas de alta umidade. Este trabalho teve por objetivo estudar o efeito do dispersante AGLP consumido atualmente na planta de beneficiamento da Votorantim Metais Vazante, na flotação do minério silicatado de zinco e avaliar o efeito da sua dosagem na umidade do concentrado final produzido. Para tanto foi realizada a caracterização granulométrica das amostras e conduzidos testes de bancada de sedimentação, filtração e flotação em diferentes dosagens de AGLP. Como era de se esperar, os resultados identificaram que o concentrado de granulometria mais grosseira obteve melhor sedimentação e umidade. Já os testes de flotação indicaram que a dosagem ótima do dispersante em torno de 400g/t garante um concentrado de qualidade, sem perda de recuperação metalúrgica e com umidade adequada para que seja transportado.

Aug 17, 2017

By Rodrigo Martins Barbosa

A água é utilizada em processos industriais desde o começo da era industrial. Sua utilização é variada, desde como matéria prima, até como utilidades. Muito se discute a respeito da qualidade da água para descarte e seus possíveis danos ambientais, mas é importante mostrar que, além disso, existe um impacto financeiro ao trabalharmos com a má qualidade da água industrial. Este trabalho propõe demonstrar a influência da qualidade da água nos processos industriais, através da avaliação do resultado da instalação de um filtro de água na tubulação de entrada de um trocador de calor.

Aug 17, 2017

By Richard E. Chism

Some years ago, when I was seeking an illusive fortune and gaining a precarious existence in the primeval forests of Brazil, there penetrated, even to my headquarters in that far-off land, the story of a new-found mining district, where mountain peaks were ribbed with silver, and valleys teemed with virgin gold. Such were the stories that caused hundreds of men to seek their fortune in Sierra Mojada, and to return heaping curses, loud and deep, upon the vivid imaginations that had evolved the glittering fiction. Nevertheless, the rumors had some foundation of truth. The ribs of silver exist, if not the placers of gold; and a flourishing town, of some three thousand people, with two leading mining companies and several smaller ones, in operation, represents what was permanent in the excitement of 1879. Geographical Situation. The town of Sierra Mojada is situated in the State of Coahuila, Republic of Mexico, in latitude 27' 24' N., and longitude 26' 40' W. of Washington, 4' 36' W. of the City of Mexico, and 103' 43' TV. of Greenwich. It lies about 70 miles, in an air-line, N. E. of Escalon station, on the Mexican Central Railroad; but by the present wagon-road, which makes a long detour to turn the mountain range, the distance to the station is about 105 miles. The nearest towns are Huajuquilla, in the State of Chihuahua, about 125 miles due west, and Cuatro Cienegas, in the State of Coahuila, 112 miles to the eastward. Between these points and the town of Sierra Mojada, and to the north of this town, the country is an immense desert, entirely uncultivated, almost uninhabited, and very little known. This

Jan 1, 1887

By Byron M. Bird

JIGGING is the stratification of a mass of solid particles in upward pulsations of water or in alternating upward and downward pulsa¬tions. The stratification usually is effected in a rectangular open¬top container having a perforated bottom through which the pulsations of water are applied to the materials to be separated; in separating coal, to a mass of coal and refuse. Jigging usually is a continuous process involving three steps: (1) the reception of the raw coal, (91) the stratification of the coal and refuse so that the refuse settles to the screen plate, and (3) the overflow of the cleaned coal and the withdrawal of the refuse collected on the screen. The jig is the most universal washer ever devised. It is handling in practice a wide range of closely sized coals and ores, mixed sizes of coal from 8-in. to 0 through %-in. to 0, and mixed sizes of ores down to %3 O-in. to 0 and even smaller. It is treating materials ranging in specific gravity from that of gold at 19 to that of coal at 1.30. It is handling feeds in which the proportions of high-gravity materials range from 90 per cent or higher, as for some iron ores, to 10 percent or less for some coals. It is handling feeds containing all shapes of particles-round, rectangular, and flat. It is handling simple separation problems and difficult separation problems. Thus, it is an almost universal separating device. One might add that it has been one of the most misunderstood types of washers, from both a theoretical and a practical point of view. Although con¬siderable progress has been made in coal jigging in the past 10 years, the jig probably has more unexplored possibilities than any other type of washer. In this chapter the object has been to treat the jigging process in a practical manner and to give information that will help the reader to improve his particular operation. Inasmuch as performance data from operating plants would contribute little of value, none has been given. Instead, the emphasis is upon jigging principles as a foundation for attacking the problems that arise. These principles are in reality tenta¬tive conclusions from research in the field of jigging during the past 10 years and most of this chapter should be regarded as a progress report on an investigation still under way.

Jan 1, 1943

By A. G. Storey, J. B. W. Bailey

"The Noranda Process at the Horne Division ofNoranda Mines Limited now smelts approximately 350,000 short dry tons of concentrate a year, which is 40% of the total smelter throughput. Campaigns are averaging 200 days and refractory consumption is much lower than in the conventional smelter.In this paper, details ofrecent operation are given, together with updated projections for operation with higher levels of oxygen enrichment.IntroductionThe Noranda continuous smelting process has been in operation at Noranda, Quebec, for six years and in that time it has smelted a million and a half tons of concentrate. It is currently smelting 1,200 to 1,250 tons per day of concentrate on an instantaneous basis"" and it is handling approximately 40% of the Horne smelter throughput.This paper will describe the current operation of the process and the improvements that have been made since 1976, when the process was described by L.A. Mills et al.lSince early in 1975, a high-grade matte averaging 73% copper has been produced, which is then sent to the converter aisle for final treatment. All the information in this paper refers to the operation of the process in the matte mode .Early in 1978, Kennecott Copper Corporation started up their new smelter near Salt Lake City, Utah , which has three Noranda Process reactors operating with high oxygen enrichment of the tuyere air (2). These furnace s incorporate some design improvements, which will be described briefly."

Jan 1, 1980

By B. I. Ferber

Toxic and explosive atmospheres are discussed, along with some of the instruments commercially available for their detection. No attempt has been made to evaluate the accuracy of anyone device. This circular has been prepared primarily to aid mine inspectors in selecting suitable instruments for underground gas detection.

Jan 1, 1972

By Jorge Da Silva

El presente trabajo señala la importancia de la función del área de Tecnologías de la Información en el logro de los objetivos de la empresa minera Yanacocha a través de un programa de excelencia operacional, donde se optimiza y distribuye de mejor manera los recursos de la empresa, se explora nuevas áreas, se legaliza los permisos correspondientes para acceder a nuevas tierras y se compromete a los trabajadores con los objetivos de la corporación.

Sep 9, 2007

By John Griffen

HYDRAULIC classification as explained by Rittinger and others was largely restricted to conditions wherein the free-falling velocities of the particles were conceived as governing the separations effected (see chapter 9). The laws governing classification under free-falling conditions have been summarized by Chapman and Mott as follows:

Jan 1, 1943

By R. R. Klimpel

The process of froth flotation as a means of upgrading the quality of coal by removing ash/pyrite and of separating selected mineral(s) from undesired gangue materials is certainly one of the most common unit engineering operations in use today. Flotation has been successfully practiced at the industrial scale for well over 50 years, and if anything, its use is increasing due to the ever decreasing feed grades of the coals and minerals being processed. Flotation, as a process, has also shown itself to be an extremely flexible process that lends itself well to a wide variety of solid/solid separations. Thus separations can involve very different particle sizes, particle densities, relative weight ratios of materials to be separated, etc., with surprisingly little modification in equipment and operating philosophy required.

Jan 1, 1988

By G. E. Wasson

Coal in most refuse ponds including those owned by Consolidation Coal Company can be recovered by froth flotation techniques. Laboratory studies show that the flotation conditions required for coal recovery varied greatly from pond to pond. The variables found to be most important for high coal recovery and low product ash were: a) the amount and type of flotation reagents and b) the degree of conditioning before flotation. Coal recovery at a rate of 0.504 kg/s (2 tons/hr) was demonstrated at a pond site employing a mobile froth flotation unit.

Jan 1, 1988

By AIME AIME

PERHAPS the outstanding characteristic of the newly elected President of the Institute is his rare ability to set aside nonessentials, and pick out the few basic elements on which a valid conclusion on any question can be drawn. This holds whether he is appraising a mining enterprise, selecting a man for an important position, deciding whether to buy or sell a bond, or choosing the best method for mining a huge body of ore. For example, he has pointed out that the two primary factors that make for success in a copper-mining venture are a large reserve of reasonably good ore and competent management. Usually the first is not as difficult to gauge accurately as the second. In a big enterprise the quality of the management

Jan 1, 1939

JamEs F. Kemp, New York, N. Y.:—Mr. Hewett's paper is one of exceptional interest, because it not only adds an important contribution regarding one of the rarer, valuable elements, but also because it introduces compounds hitherto unknown and in associations no less novel. While we have occasionally discovered and recorded asphaltite in metalliferous deposits, for example in the Joplin and Granby districts, we have not seen a metallic ore in a deposit eesentially asphaltite. The source and method of introduction afford a subject well worth serious reflection.

Jan 1, 1910

By C. O. Tarr, G. V. Smith, R. F. Miller

METALLURGISTS have long recognized that the Fe3C type of carbide is not a stable phase in steel and that, given sufficient time, it will decompose with formation of graphite, at least at temperatures below about 2050°F.1 This slow graphitization has never been of much concern to users of hypoeutectoid steels, for in such steels it occurs only during prolonged exposure at elevated temperature. In 1935, Kinzel and Moore2 reported complete graphitization of the carbide of a 0.1 5 per cent carbon steel that had been in senrice for about 26,000 hr. at a temperature of about 1100° to 1200°F. In discussing this paper, both Mathews and Sauveur reported graphitization of slightly hypereutectoid steels. In an extensive investigation of graphitization of high-purity iron-carbon alloys, Wells1 produced graphite at 7o0°C. (1290°F.) in an alloy containing as little as 0.13 per cent carbon, and showed that graphite may precipitate either directly from austenite or from decomposition of Fe3C, also that the rate of graphitization tends to increase with increase of temperature, at least up to a certain point, and with the presence of graphite nuclei. Jenkins, Mellor and Jenkinson,3 studying the structural changes in carbon steels ranging from 0.17 to 1.14 per cent carbon during stress-rupture tests at elevated temperature, obsenred graphite in an aluminum-killed 0.40 per cent carbon steel after fracture in 4340 hr. under a stress of 17,900 lb. per sq. in. at 840°F. and in many of the steels after stress-rupture test at 1200°F. Unstressed samples of 0.60, 0.86 and 1.14 per cent carbon steels graphitized almost completely in 360 hr. at 1200°F., while samples of 0.90 and 1.10 per cent carbon steels were somewhat graphitized, and steels containing 0.24, 0.40 and 0.57 per cent carbon showed no sign of graphite. Their results indicate that graphite precipitates the more readily the higher the carbon content, though this tendency is influenced to some extent by deoxidation practice, and that graphitization is accelerated by plastic deformation. In a recent study of the graphitization of 0.4 and 0.6 per cent carbon steel strip, made by M. A. Hughes,4 it was found that at 1200°F. graphite appeared after 72 hr. in aluminum-killed but not in silicon-killed steel, and that the rate of graphitization was increased by slow cooling from 1600°F. and by cold-working prior to annealing. In creep tests of normalized o. I 5 per cent carbon steel killed with 2.5 lb. of aluminum per ton, at the U. S. Steel Corporation laboratory at Kearny, spheroidization and some graphitization were found after 3000 hr. at 1000°F. under a stress as low as 15m lb. per sq. inch.

Jan 1, 1944

By J. A. Morgan, R. E. Lund, D. E. Warnes

The design, operation, and performance of an integrated pilot plant for recovering zinc and copper from a complex sulfide ore are described. Metallurqical processing comprised selective sulfate roasting in a fluid bed, leaching in a weak sulfuric acid solution, recovering copper by cementation with scrap iron, air oxidation to remove soluble iron, more-or-less conventional Purification for removal of impurities deleterious to zinc electrolysis, recovering zinc by electrolyzing solutions, and recycling spent electrolyte to the sulfating roaster. The effects of several feed preparation and roasting variables on the sulfation response of zinc, copper, and iron are set forth, together with the electrolyzing characteristics of the zinc solutions. SEVERAL years ago, St. Joseph Lead Co. undertook a research program to develop procedures for winning values from a complex ore. The deposit was a massive sulfide ore body containing upwards of 65 pct pyrite. Gangue, composed principally of quartz, calcite, dolomite, and alumina, comprised only 10 to 20 pct of the mineralized zones. Zinc, lead, and copper values were variable, but averaged about 6.7 pct Zn, 2.6 pct Pb, and 0.4 pct Cu. Early in the exploratory test work, it was established that the intimate physical association of the minerals in the ore made beneficiation by conventional flotation procedures difficult. Accordingly, in addition to a comprehensive program to investigate physical methods of ore beneficiation, a research program was established to develop a direct metallurgical method for processing the ore. After surveying a number of potential methods for recovery of both metal and sulfur values, effort was concentrated on the development of a sulfate roasting process. It is the pilot-plant development of the sulfate roasting-solution purification—electrolyzing procedures which forms the subject of the present paper. PREPILOT PLANT INVESTIGATIONS From a thermodynamic viewpoint, it is feasible to sulfate selectively a host of metals, including Zn, Cu, Pb, Cd, Ni, and Co, in an iron sulfide ore without sulfating iron. Of course, a number of conditions such as roasting temperature and gas composition must be controlled. In addition, as first disclosed by Hybinette,' an alkali metal salt is frequently beneficial in promoting the sulfation reactions. The application of fluid bed roasting to the sulfate roasting of nonferrous metals was pioneered by Stephens of Battelle Memorial Institute.' Subsequently, Falconbridge Nickel Mines, Ltd. developed an unique process for selectively sulfating and recovering nickel, copper, and cobalt from their nickeliferous pyrrhotite, which recently has been described in an excellent paper by Thornhill.3 One of the unique features of the Falconbridge process is that the feed is introduced into the fluidized roasting furnace in a manner such that the feed slurry is broken up into droplets and the droplets lose their moisture before contacting the surface of the fluidized bed. The dried droplets do not tend to cake or fuse, but rather remain as discrete agglomerates of concentrate particles and roast without significant degradation. St. Joseph, aware that Battelle Memorial Institute had participated in the development of the Falconbridge process, obtained permission from Falcon-

Jan 1, 1962