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By Breno Totti Maia

O BOF, Basic Oxygen Furnace, ou convertedor LD, é o processo mais utilizado industrialmente para o refino primário do ferro gusa atualmente. Para aumentar a produtividade do BOF deve-se diminuir o tempo de cada ciclo de operação, especialmente o tempo de sopro aumentado a taxa de descarburação. Durante o sopro do convertedor existem três etapas. A segunda etapa do sopro a taxa de descarburação é alta e constante sendo o fator limitante é a disponibilidade do oxigênio no banho e determina o tempo de sopro. Assim para aumentar a descarburação pode-se melhorar a interação do jato de oxigênio com o banho, configurando o convertedor. Estudando o sopro combinado em um modelo fisíco de um convertedor LD de 220t, foi testado diferentes bicos de lança com um sopro de 160Nm3/h de vazão e vazões de 4Nm3/h e 6Nm3/h nas ventaneiras. Através dos testes pode-se observar que aumentando o número de furos no bico o jato teve menor penetração, maior área de agitação e as projeções tiveram menor altitude, já a injeção pelas ventaneiras aumentou a penetração do jato e diminuiu as projeções. Foi calculado também valores para a constante K para cada configuração, assim é possível prever a penetração do jato industrialmente.

Aug 17, 2017

By Karina Aparecida Martins Barcelos Gonçalves

A evolução da microestrutura e propriedades mecânicas de dois aços inoxidáveis duplex foram estudadas via microscopia óptica e de varredura, ensaios de dureza e tração. As amostras dos aços inoxidáveis duplex foram laminadas a frio com percentual de 18,50 e 62% para o aço S32304 e 21,52 e 64% para o aço S31803. As amostras com 62 e 64% de redução foram recozidas a uma temperatura de 1055ºC com 20 s de encharque. Os resultados mostraram o efeito da deformação a frio na espessura das lamelas de ferrita e austenita, sendo este mais pronunciado na austenita. O aço inoxidável duplex S31803 apresentou maiores valores para o limite de escoamento e dureza devido ao maior percentual de molibdênio e nitrogênio, elementos que atuam como endurecedores por solução sólida.

Aug 17, 2017

By Matheus Sexto Alexandre Pereira

Controle e centralização de informações referentes ao processo industrial são imprescindíveis e considerando-se que na cadeia de suprimento o maior valor agregado costuma estar na produção, faz todo sentido investir em sistemas que possibilitem a otimização do fluxo, controle e qualidade do processo. O novo Sistema de Controle de Panelas (SIPAN) implantado na CSN permitiu monitorar em tempo real todo o ciclo operacional utilizando novas tecnologias de desenvolvimento de software web, além de melhorar o gerenciamento, comunicação com outros sistemas e rastreabilidade de todo o processo. O sistema implementado conseguiu melhorar a qualidade de informação para a equipe tornando mais rápida e assertiva a tomada de decisão.

Jul 30, 2018

By Alexander Schultz Rizek

O trabalho que será apresentado irá descrever o projeto realizado de atualização tecnológica do sistema de controle com controladores Automax instalado em um laminador de fio máquina de dois veios, a Acerías Paz del Río, da Votorantim Siderurgia na Colômbia. Este projeto consistiu na substituição do antigo sistema de controle com PLC’s Automax do laminador fio máquina de dois veios, mantendo-se parte do sistema antigo Automax convivendo com o novo sistema Contollogix. O novo PLC instalado para o controle do laminador foi o Rockwell ControlLogix, através do qual foi desenvolvido o controle principal do laminador, como: cascata de velocidade utilizando o fator R, que poderia ser ajustado do IHM (antes os ajustes eram feitos diretamente no rpm dos motores), controle de laços, controle das mesas de laço, as primeiras da Russula, produzidas e programadas em companhia com a Russula Itália exclusivamente para esse projeto, controle de tração, ciclos de posicionamentos manuais e automáticos, intertravamentos, etc.

Jul 30, 2018

By Stephen Chung, Graham Mustoe, Joe Haid

In an open cast coal mining operation, a 305 m (1000 ft) long by 49 m (160 ft) thick overburden cast blast can produce more than a million cubic yards of broken muck that needs to be removed before the coal recovery process can start. In the Powder River Basin of Wyoming, it is common to see 30 to 40 percent of the overburden cast to a spoil that does not require rehandling with heavy equipment. Therefore, the higher the percent cast, the better the cast blast is rated. However, depending on the shape of the muck profile, there is often 20 to 30 percent of the muck standing in front of the high-wall. This portion of muck would require a number of dozers to push down to the dragline pad level. From the mine operator point of view, it is believed that for a given muck profile, there should be an efficient dozer pushing method such that a dragline pad can be developed in the shortest time. As a tool for analyzing this dynamic problem, a 2-D discrete element model, i-PushTM, has been developed to simulate a dozer pushing operation. This mechanistic model takes into account the dozer blade geometry, the dozer operating procedure (e.g. cut-depth, blade fill distance, forward and reverse speeds at specific slope angles), material density and cohesion. To demonstrate how i-PushTM can be used to help determine the most productive push routine, this paper presents three dozer push methods to compare the effectiveness of pushing at 3:1, 4:1 and 5:1 push angles.

Jan 1, 2006

By E. D. Gardner

This bulletin, which discusses open-cut mining at the metal mines of the United States, is the last of a series of such papers by the Bureau of Mines describing the principal methods of mining.4 Open-cut mining is applicable to flat-lying mineral deposits relatively near the surface. Vein deposits seldom are amenable to this method, although outcrops of veins sometimes are worked as open pits. Most of the iron ore of the country is mined from open pits; according to the Minerals Yearbook, 67.4 percent was mined from open pits and 32.6 percent from underground mines in 1937. Open-cut mining is relatively new in the copper industry but yields more copper than any other method; in 1937 about 52 percent of the copper ore mined in the United States was taken from open pits. Lead-zinc ore has been produced from open pits in the Joplin (Mo.) district, but most of the deposits in this area, although flat-lying, are too deep to be mined economically by the open-cut method. In 1937 one company at Oronogo, Mo., was stripping overburden and mining mixed oxidized and sulfide ores by this method.

Jan 1, 1941

By J. L. Morning

During recent years, the Bureau of Mines has conducted an extensive investigation of the materials for making iron and steel. This work includes iron ore concentration, agglomeration, direct reduction of iron ores and concentrates, the production of pure manganese, chromium, and cobalt by electrolytic processes, the production of ferroalloys from low-grade domestic ores, and the development of special alloys to utilize these products. As a part of this general program, a Congressional appropriation allowed the con¬struction of an electric-furnace, semicommercial, ingot-producing plant at Shasta Dam near Redding, Calif. The primary objectives of the pilot plant were to determine the costs and operating problems involved in the production of steel and ferrous alloys in which sponge iron was used as melting stock, and to determine the physical properties of the materials produced. The pilot-plant equipment and the results of sponge iron-melting tests in the basic lined, electric arc furnace have been reported in previous publications.3/4/

Jan 1, 1953

By S. Jayasekera, A. M. T. S. Bandara, J. Kyle, E. Koenigsberger, L. Koenigsberger

The extraction of rare earth oxides from fluoroapatite rich phosphate concentrates often involves a weak acid leach of fluoroapatite and a sulphuric acid bake of the leach residue followed by water leach and precipitation to obtain an intermediate product. The main aim of this study was to determine and rationalize the solubility of rare earth metal ions in synthetic solutions representing various process liquors at the temperatures 40, 60 and 80oC. The liquors contained different acid and metal ion concentrations with respect to sulphuric acid, phosphoric acid and sulphate salts of sodium, magnesium, aluminium, potassium, calcium and iron(III). A solid of mixed rare earth carbonates was used as the source of rare earth metal ions. The solubility tests and characterization of solids using XRD were conducted at Murdoch University laboratories as part of the process development for the Arafura Resources Nolans rare earth project. The composition of initial carbonate solids and the solids and solutions formed after saturation were analysed for rare earth and other elements at TSW Analytical Laboratories in Perth using ICP-MS and ICP-OES. The precipitated solid in sodium-rich acidic sulphate solutions is the double salt NaRE(SO4)2 based on the solid assays. However, in acidic solutions free of sodium or of low concentrations of sodium the precipitated solid appears to be RE2(SO4)3.

Jan 1, 2014

By Takashi Furuyama, Sukeyuki Mori, Takafumi Okuma, Norio Hashiguchi

The Tower mill KD-3 is an improved version of the laboratory mills VD-1, KD-1 and KD-2 in which the classifying column has been modified to ensure a quick discharge of products from the comminution section and, on the other hand, a better separation of coarse and fine particles; the latter being collected in a cyclone with a central spiral ribbon. To level the circling airflow through the classifying column and have a strict control over the maximum size of collected particles, a series of experiments was carried out, modifying the internal structure of the column: insertion of a vertical plate, a cone, or a horizontal net. The relationship established between the maximum size of products collected in the cyclone and the duct airflow rate indicates that, independently of the latter, the insertion of a cone in the classifying column could stabilize the maximum size of products collected in the cyclone around 15.1 - 17.5µm. With a horizontal net, the maximal size could be reduced to 8.4 - 11.3µm. This occurrence might result from the collision of coarse particles blown from the comminution zone with the base of the inserted materials and their settling down the bottom of the classifying column.

Jan 1, 2003

By L. J. Vincze

The program of study of pellet binder materials was begun by the ORF in 1963 to examine various Canadian materials as substitutes for bentonite which is imported in large tonnages (199,270 tons in 1969) from the U.S.A. for Canadian pellet plant operations. Most of the raw bentonite used in Canada originates in Wyoming, North Dakota and more recently Greece, resulting in relatively high transportation costs to pellet producers. Some Canadian bentonites available in Western Canada (Alberta) can be beneficiated for uses as pellet binders but could not compete in cost with U.S. sources due to the cost of beneficiation and the higher rail transport charges to Eastern Canada. It is difficult to find a substitute for bentonite, and many materials have been investigated by research groups but, so far, no economic substitute is in use. However, some success is apparent in studies of low cost materials such as clays, sea weed, peat moss and low grade coal, The work done by the ORF over several years has covered systematic test¬ing of Ontario clays, lignite, some types of tree bark, waste sulphite liquors of various kinds, and peat moss as binders for iron ore pellets. The major effort has been concentrated on peat moss and has included a study of the influence of different additives. Since analysis of peat moss for humic acid is difficult and time consuming, a certain amount of time was devoted to development of improved methods, the most useful of which was a spectrophotometric method based on extraction of peat by sodium pyrophosphate for determination of humic substances. In the present paper, only the most recent work concerning the use of peat moss with suitable additives is discussed in detail, since it is the most conclusive and best documented portion of the program.

Jan 1, 1971

By Myles E. Robinson

During the last decade there were pronounced changes in the competitive pattern of the fossill fuels It is proposed to trace these trends and describe inter-fuel competition, first as it relates to the economy as a whole and then more specifically to examine competition of the fossil fuels as these share the electric utility market. Table 1, Competitive Fuels and Water Power Used in the United States, 1950-1959, shows the growth in the consumption of coal, oil, gas and water power 'during the past decade. Uses which are not directly competitive among the fuels, such as tractor fuel, carbon black, and consumption of petroleum products in the making of synthetic rubber, have been excluded from these statistics. The experience of the three fossil fuels in competition since 1950 shows natural gas expanding more rapidly, than oil by roughly twice as much, 219.0 percent' compared to 124.1 percent growth in B.t.u.s of oil consumed in the ten-year period. Percentagewise, water power little more than held its own, and coal, including anthracite, actually decreased more than one-fifth.

Jan 1, 1961

By H. B. Brunot

A complete list of permissible mine equipment , tested and approved by the Bureau of Mines previous to January 1 , 1947 , was published as Information Circular 7432.27 A list of permissible mine equipment tested and approved by the Bureau of Mines during the calendar year 1947 was published as Information Circular 7465.3/ The present list supplements Information Circular 7432 and includes all of the equipment approved during the calendar years 1947 , 1948 , and 1949. It therefore supersedes Information Circular 7465. The list also includes an appendix ( No. 2 ) giving the symbol that must be used by every cable manufacturer in marking trailing cables that have passed the test for flame resistance as stated in the amendment of October 21 , 1947 , to Schedule 2E . The items are numbered to indicate the consecutive order in which each type of machine or device was approved in its particular classification . Thus , Information Circular 7432 showed six air compressors on the active list ; five additional compressors , Nos . 7 to 11 , inclusive , in this category were approved during 1947 , 1948 , and 1949 . Several items that were listed in Information Circular 7432 have been repeated in this circular where it was necessary to show that approvals of such equipment were extended to cover an additional voltage rating or other changes . Equipment listed in these circulars is approved by the Bureau of Mines only when found , upon inspection and test , to comply with minimum standards of safety as outlined in schedules prepared on the basis of many years of experience in dealing with safety problems of the coal -mining industry . The use of such equipment in mines known to be gassy , as well as in those that may become so , is earnestly recommended in the interest of safety . This circular is published so that the industry may be kept informed as to the many types of machines , devices , and lamps that are available for reducing explosion and other hazards incident to coal mining . This circular and Information Circular 7432 give the complete list of permissible mine equipment that is available under the various classifications .

May 1, 1950

By L. D. Snyder, J. K. Russell

"The Lower Jurassic Iron Mask batholith intrudes Upper Triassic Nicola Group volcanic rocks in the Quesnellia terrane of southcentral British Columbia and hosts Cu-Au mineralization. The batholith comprises three mappable intrusive phases, including: Pothook gabbro to diorite, Cherry Creek monzodiorite to monzonite and Sugarloaf diorite. The Iron Mask hybrid forms a fourth mappable unit that makes up to 45% of the areal exposure in the batholith. It is highly variable in texture and composition and subdivided into three types; Type I and II have abundant (partially digested) xenoliths, many of which are derived from the Nicola Group, whereas Type III is xenolith-poor and shows extreme outcrop-scale textural diversity.Pothook and Cherry Creek rocks are similar in texture, mineralogy, whole rock and mineral composition and style of alteration. Contacts between the two can be intrusive or gradational. Rocks collected from these two suites have compositions that are permissive of a single magma batch, although simple crystal fractionation does not explain all chemical variations within and between the two suites. The Sugarloaf unit comprises a diverse group of amphibole-phyric rock types and is texturally and mineralogically distinct from Pothook and Cherry Creek suites.The Iron Mask hybrid represents progressive stages of physical and chemical interaction between Nicola Group country rocks and Pothook magma. Magmatic assimilation (selective or partial) is supparted on the basis of field relationships, petrographic observations, and REB compositional data. Thermal dehydration and partial assimilation of Nicola Group rocks by Pothook magma is shown to be a valid means of promoting early and extensive volatile saturation in the Iron Mask batholith."

Jan 1, 1995

By Thomas W. Camm

In this U.S. Bureau of Mines report, mine and mill cost models are presented to make quick estimates of the cost to develop mineral deposits in the desert region of the Southwest United States. Regression analysis was used to generate capital and operating cost equations for each model in the form Y = AXB, where Y is the cost estimated and X is the assumed daily capacity in short tons. A and B are constants determined by the regression analysis. Each is broken down into 11 subcategories to facilitate escalation of costs for inflation and to increase their versatility in economic evaluation work. This report contains 2 open pit models, 6 underground mine models, 11 mill models, and cost equations for access roads, powerlines, and tailings ponds. In addition, adjustment factors for variation in haulage distances are provided for open pit models and variation in mining depths for underground models.

Jan 1, 1991

By J. L. Kohler

The final report for Phase II of Bureau of Hines Contract J0134025 concerns the research and development of sensitive ground-fault relays for dc utilization systems in mining. Sensitive relaying employs very low pickup levels such that, when used in conjunction with very high resistance grounding, the exposure of a human to ventricular fibrillation is significantly reduced. To delineate the desired relay characteristics, the report begins by reviewing previous research in this area. A theory for the saturable transformer used to sense the fault current is presented. The design of the ground fault relay is described in sufficient detail that it may be duplicated. Test procedures and results are given. Finally, conclusions and recommendations related to Phase II are presented.

Jan 1, 1986

By Nunna Malakondaiah

Plant samples collected from the mined sites of Beulah, Center and Zap and the test sites of North Beulah 1, North Beulah If, South Beulahh and Center were analyzed for their nutrient concentrations. The vegetation from the mined areas generally showed lower concentrations of Na, P and Cu and failed to meet the nutritional requirements for beef cattle as defined by National Research Council (minimum requirements are: Na, 600; Cu, 4; P, 1800 µg/g dry weight). Plants from Beulah showed generally higher concentrations than from Center or Tap. Tissue concentrations of K varied significantly between sites for 5 species due to the low tissue concentrations at Center. Deficiencies are difficult to isolate as the sampling was done in mid-summer and generally during that season the tissue concentrations tend to decrease in several species. All of the plant species at the unmined sites, with the exception of western wheatgrass at Zap, had lower concentrations of P than the minimum nutritional requirements for beef cattle. Sodium concentration was low but Cu was marginal to adequate in plant species at the unmined sites. Concentrations of K, Mn and Cu in western wheatgrass were greater at Center than at Zap while the opposite was true of the concentrations of Zn, Cu and P in blue grama and Cu in green needlegrass. Amending the spoil with slack at North Beulah I decreased the concentrations of Zn, Cu and P in wheatgrasses grown on spoil from 0-2, 5-10, and 20-25 foot depths, respectively. In general, the mean tissue K+/Na+ ratios were greater in plants on slack amended spoils, primarily due to the reduced Na concentrations in the tissue. At North Beulah II test site, only wheatgrasses grown on spoil amended with slack showed significant increase in K and decrease in Na and Mn concentrations. At South Beulah test site which received 12" topsoil over graded spoil, leonardite amendment decreased P concentrations in all of the grasses as compared to control, whereas fertilizer treatment increased the same. Nutrient concentrations were lower in both fescue and needlegrass with leonardite treatment and higher with fertilizer treatment although not significantly different from control. The concentrations of Ca, Mg, Na, Fe, Cu and N in grasses grown on topsoil at Center test site were significantly higher than on slack amended spoil. Legumes grown on topsoil at Center site contained higher concentrations of P than those grown on spoil; there were no significant effects due to slack on spoil or topsoil. The data presented in this report act only as an indication of between-treatment and between-species differences in tissue composition of plants harvested in mid-summer season. With respect to the nutrients analyzed, since none were found to be toxic, the cattle can safely feed on the vegetation of these mined areas.

Jan 1, 1982

By D. D. Walker

Scheelite, the most abundant tungsten mineral in the Philipsburg region of Montana, is found in replacement deposits and along fissures and cracks in limestone at various distances from contacts with acidic igneous rocks. It also occurs at the limestone-igneous contacts, but typical garnet tactites are developed in only a few places in the region. The most favorable host rocks for scheelite mineralization are the Jefferson, Hasmark, and Madison limestones. Scheelite is exposed in float, outcrops, and surface and mine workings along a 2-mile-wide belt extending southwest from Lost Creek beyond Silver Lake, a distance of 15 miles or more. (See fig. 1.) Some scheelite is found in veins formerly mined for silver. Powellite and molybdenite occasionally are present with the scheelite. Hubnerite occurs in quartz veins in the Black Pine area 10 miles northwest of Philipsburg. These quartz veins occur in the quartzites of the Precambrian Spokane formation. Tungsten production in the region has come almost exclusively from scheelite deposits, both lode and placer. During a 6-year period beginning in 1943 a total of 142.0 tons of 63-percent W03 concentrate was produced by H & H Mines Co. In the early 1950's, the Trigger mine produced 4,000 tons of 1-percent W03 ore and the Tip Top 650 tons of 2.0-percent W03 ore and 2,906 tons of 2.2-percent ore. There has been sporadic production from some of the smaller properties in the area.

Jan 1, 1960

By V. E. McKelvey

Any discussion of growth and future requirements has to begin with people--both their number and their needs. Both have been rising ever since any American can remember. Together, the number of people, which has been increasing rather modestly, and their wants and desires for material things, which have been increasing very sharply, seemed to have comprised a growth imperative in mineral consumption in the United States, especially during the last several decades. While the Nation's birthrate is now well below the replacement rate and still falling, the built-in momentum of the post-World War II population boom will continue to be felt well into the 21st century. Even using the modest projection of a 0.8 percent yearly increase, we are still looking at the possibility of 265 million Americans being around by Year 2000.

Jan 1, 1975

By J. M. Davidson

The potassium mineral polyhalite (K2SO4.MgSO4.2CaSO4.2H2O) found in large deposits in western Texas and southeastern New Mexico is associated with varying amounts of halite (sodium, chloride, NaCl) and anhydrite (calcium sulphate, CaSO4). Although the anhydrite, because of its low solubility and slow rate of solution, is relatively inert, the halite is dissolved immediately in any process solution with which the polyhalite comes in contact. Limited quantities of sodium chloride in the liquors used for the hot extraction of polyhalite materially improve the results obtained, but only a very small sodium chloride content may be desired in the entering polyhalite in other procedures, such as Bureau of Mines process. In all of the processes suggested for the recovery-of potassium sulphate from polyhalite the control of the sodium chloride content will be desirable, if not absolutely essential to efficient operation.

Jan 1, 1934

By Leonard Obert

THIS REPORT presents methods and principles useful in designing underground mine openings and pillars in competent rock formations. Two types of formations are considered: (1) Massive formations, in which openings are generally mined with an arched roof, and (2) bedded formations, in which openings are generally mined with a flat roof. Design principles for openings and pillars in massive formations are obtained by considering the maximum tangential stresses developed around single and multiple openings for stress fields of various types. Design principles for openings and pillars in bedded formations are obtained by considering the average stress in pillars and the maximum stresses in roof layers. Experimental procedures for making stress, strain, and in situ physical-property measurements in underground mines to check design calculations are outlined and the results discussed.

Jan 1, 1960