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By Ailton Lopes de Oliveira

A Usiminas, como empresa de ponta na produção de aços planos, visando manter e ampliar a sua liderança na produção e comercialização destes produtos, investiu uma elevada soma na modernização de sua linha de produção. Em 2012 foi instalado na Usina de Cubatão, o moderno Laminador de Tiras a Quente e, em agosto de 2013, foi dada a partida operacional da nova linha de Decapagem 03. O objetivo da nova Decapagem 03 é agregar valor em seu portfólio de produtos, complementando assim a nova linha de produtos ofertados com novas dimensões e qualidades. A nova mistura de produtos laminados a quente atende maiores faixas de espessura e largura, além de oferecer tipos de aço não produzidos anteriormente. Este trabalho visa mostrar as principais etapas deste projeto, os benefícios e os resultados preliminares alcançados com a instalação da nova linha de produção. A Decapagem 03, por seu elevado nível tecnológico, é considerada "estado da arte em produção de bobinas decapadas", garantindo assim a obtenção de produtos de grande valor para os clientes, atendendo aos mais rigorosos padrões de qualidade.

Jul 30, 2018

By L. Zhou, D. Bahrami

Mine ventilation is one of the most important aspects of mining operations in underground mines. It is critical to maintain and deliver required fresh air to the active areas to reduce the risk of overexposure to hazardous contaminants or explosive atmospheres. An unexpected or unknown event such as roof collapse, unexpected mine door closure/opening, a fire/explosion, or fan malfunction could adversely alter the airflow distribution within the mine ventilation network that could lead to a hazardous underground environment. Knowing the occurrence and location of such an incident is of critical importance. In this study, the authors developed a novel methodology to assist mine operators in quickly identifying the location of any abnormal airflow change within the network using the airflow changes at monitored airways. The concept is based on a direct derivative method developed by the authors. This paper provides the details of the developed method as well as numerical verification examples. The application of this method can benefit mine operators and safety personnel in making better decisions during a mine emergency response operation to mitigate hazardous conditions arising from an unexpected airflow disturbance

Mar 2, 2022

By Haysler Apolinário Amoroso Lima

O desempenho de uma Aciaria depende da estabilidade dos equipamentos industriais. A conservação do refratário do convertedor garante produtividade, evitando paradas para reparo e campanhas antecipadas. A proteção do revestimento como um todo garante uma maior eficiência do sopro combinado, obtendo ganhos de qualidade e redução de ressopro. O presente trabalho refere-se à busca de soluções de engenharia para aumentar o desempenho do refratário dos convertedores e conservação do sopro combinado pelas ventaneiras. Através do estudo dos mecanismos de desgaste dos refratários, optou-se pelo ajuste dos escorificantes, melhoria das práticas de reparo com escória, mudança do projeto dos tijolos e ajuste da vazão das ventaneiras. Com as melhorias implantadas, houve redução do consumo de massa de projeção e aumento em 100% da vida útil das ventaneiras.

Jul 30, 2018

By J Rutter, S Dunham

Technological advances in sensor and material handling technology has enabled a step change in mine operations performance. Sensors capable of monitoring the grade of broken rock mass can be mounted on shovels, truck loading units or conveyors allowing highly precise ore/waste decisions to be made on small parcels of rock, increasing selectivity. This increased selectivity has the potential to remove sub-economic material from the product stream prior to incurring ore treatment costs. Bulk ore sorting is capable of intervening at <10t “pods” on Run Of Mine conveyors, or alternatively at per bucket loading (5-100t) or truck scale (30-350t) parcels of ore. This Grade Engineering technique being developed by CRCORE (Rutter, 2017) can improve mill feed grade, remove deleterious materials and ensure that the high capital intensity ore treatment facility is presented with the best ore feed strategy. While this technology can improve mine economics, estimating the performance of a bulk ore sorting system is challenging. Traditional resource estimation practices such as Ordinary Kriging and Inverse distance weighting (IDW) are based on weighted averages, a process that smooths the grade profile, reducing modelled variance and dispersion. Its purpose is to generate a globally unbiased result but is less suited to generating a model of adequate granularity to enable confidence in local grade heterogeneity. This is an essential component for bulk ore sorting success. Estimating ore sorting performance requires knowledge of the grade-tonnage curve at the scale of the sensor diversion unit (SDU). Evaluation based on an estimator that smooths the SDU distribution will not correctly predict ore/waste separation or economic performance. Alternatives to traditional linear geostatistics have been tested on a variety of mineralisation styles. Additionally, a number of heterogeneity metrics have been developed to assist with evaluation and assessment. The difference between estimation for grade (metal) and modelling for traditional mining block models, versus methods used for predicting heterogeneity and variability are explored.

Nov 10, 2020

By Francesco Chiappalone, Marco Invernizzi, Franco Gasperin, Brad Yoder, Fabrizio Fara

The Ship Canal Water Quality Project includes a 2.7-mile, 18-ft and 10-in internal-diameter tunnel that extends from Ballard to Wallingford, two popular neighborhoods in the West of Seattle. During the TBM Main drive a 12' × 12' boulder with variable strength up to 47,000psi was encountered resulting on signicant damages to the Cutter ead. The rst part of this paper describes the design and construction of an underground recess in front of the TBM to create a safe working environment for the TBM repairs. The second part describes an injection campaign performed to seal an unforeseen water inow appeared during the excavation of the 11 Avenue Diversion Structure.

Jun 23, 2024

By James Gayley

(Wilkes-Barre Meeting, June, 1911.) THE paper presented to the Institute in 1910, by H. 0. Hofman, on Recent Progress in Blast Roasting,1 has called the attention of the iron industry to the adaptability of these processes to the reclamation of by-products such as flue-dust and blue billy, and the better preparation of concentrates and fine ores for use in blast-furnaces. The waste of valuable iron-ore through the production of flue-dust has increased at an enormous rate, and much of it has in reality been wasted as far as future recovery is concerned. Only in recent years has a possible future value been recognized, and the material stored. The increased use of Mesabi ores, which carry considerable fine ore, is principally responsible for the great increase in the production of flue-dust. The amount of fine material that is carried over depends on the fineness of the material and the velocity of the gases, and also to a very great extent on the regularity or irregularity of the working of the furnace. Attempts to recover a part of this loss have been made by recharging a portion of the production into the furnace, but as this material has been once carried out from the furnace, it is naturally in good shape to be carried out again. A recent practice at some works, is to soak the flue-dust thoroughly with water to give it more cohesiveness, but by many this is considered of doubtful advantage in the furnace, and the gases are in consequence heavily laden with moisture. There are vast deposits of magnetic iron-ores in the United States and Canada that are too low in iron for use at the present time, but which can be economically concentrated into very rich material ; in many cases the fineness of crushing necessary to secure proper concentration has prevented their

Aug 1, 1911

By Joseph W. Richards

THIS method of briquetting flue-dust, or flue-dust mixed with fine ores, or, in a few exceptional cases, coke-dust, has come into large commercial use in Europe, and a small plant is already in operation in the United States. It promises to become of such great importance to the iron industry of the United States that the following description will certainly interest the majority of our pig-iron producers. Discovered in 1908, the process rests upon the observation of Dr. Schumacher that blast-furnace flue-dust, while possessing of itself no binding or cementing properties, acquires strong cementing properties if mixed with a very small amount of certain salt solutions, the amount of which is so small that the resulting cementation appears to be rather by catalytic action of the salts added than by the mass-action of such chemicals. To be more specific, fresh blast-furnace flue-dust mixed with from 5 to 10 per cent. of its weight of magnesium chloride or calcium chloride solution-that is to say, with from 0.25 to 2 per cent. of its weight of magnesium chloride or calcium chloride-acquires the property of setting within a short time, from 15 to 60 min., and forming a hard cemented briquette. Alkaline solutions appear to have no action such as described, and they even interfere, if present, with the action of the magnesium and calcium solutions. When treated in this way the flue-dust briquette sets very hard, apparently from pure excess of cementing- and setting-power. It is, therefore, possible to . mix with the flue-dust a considerable proportion of inert ore or like material, which has no setting-power by this process, and thus to make a compound briquette containing large quantities of ore mixed with flue-dust, but in which the flue-dust may be regarded as the cement or binding-material. A particularly strongly cementing flue-

May 1, 1912

By James P. Chivilo, Gregory R. Meeder, Scott J. DiFiore, Matthew H. Johnson

New construction in metropolitan areas has direct impacts on immediate neighbors and abutters. While noise and dust are generally nuisance concerns, demolition, vibrations, excavation, and dewatering can cause structural damage to adjacent structures. Different cities, states, or jurisdictions have different regulations that dictate requirements, roles, or responsibilities for varying parties during construction. The authors will introduce and discuss risks of new construction adjacent to existing structures, and the legal framework in Illinois which requires the owner of the new construction project to provide adequate protections for adjacent existing structures. The authors, who are engineers and attorneys, will discuss technical and legal concerns, and will highlight the importance of early and frequent communication among project participants to manage risks, despite whether or not any local regulations exist to drive the process. RISKS IN ADJACENT CONSTRUCTION New construction in metropolitan areas inherently involves some combination of noise, dust, ground-borne vibrations, earth excavation, and subgrade dewatering. These issues have potential to directly and adversely affect abutters and their property. Noise and dust can be nuisance concerns, while vibrations, excavation, and dewatering can result in damage to abutters’ structures. Noise and dust are unlikely to lead to physical damage to abutters’ property, and can be controlled with limited work hours and good housekeeping practices. Vibrations and excavations, however, if not well understood, planned for, and mitigated, can result in serious damage to abutters’ structures. In turn, this damage introduces additional and often significant costs and schedule delays.

Jan 1, 2019

By Alexandre de Aparecida Morais

No processo de lingotamento contínuo a secagem e o pré-aquecimento do refratário do distribuidor são de fundamental importância. Estes são realizados visando: reduzir a perda de calor do aço líquido, reduzir as bolhas nas primeiras placas, evitar respingos de aço (reações) ocasionados pela umidade e prevenir a degradação refratário por choque térmico. Para aços planos, os sistemas para promover a secagem e pré-aquecimento podem ser do tipo a "quente" (mais usual) ou a "frio". É denominado "partida a quente" quando se realiza a secagem e o pré-aquecimento; e de “partida a frio”, quando apenas a secagem é realizada. Têm-se como características distintas entre os processos: - A Quente: maior consumo de gás; forte degradação do refratário; temperatura de trabalho do distribuidor mais elevada, deteriorando as condições do ambiente; - A Frio: menor consumo de gás; redução da degradação do refratário; no entanto, exige um controle rigoroso da curva de secagem, o que implica maior investimento inicial no equipamento de secagem. Em 2002, após uma análise de viabilidades a ArcelorMittal Tubarão implementou o sistema de frio. Este artigo mostra a evolução deste sistema após a sua implementação, analisando a correlação com defeitos, a implementação de melhorias e os ganhos obtidos.

Jul 30, 2018

By T. N. McVay

The various applications of beryllium and its compounds in atomic - energy technology and a growing recognition of possible increased utilization of the metal in the aircraft and space - missile fields have resulted in increased interest in domestic and world reserves of beryllium . Unfortunately, little dependable data on beryllium resources and reserves are available , as past consumption of the element has been small and only limited prospecting and exploration work has been done . The scarcity of resource information is attributed partly to the difficulty of recognizing beryllium minerals in the field . These minerals frequently do not have distinctive characteristics of specific gravity, color , or other physical properties , that enable ready identification by the average prospector . This is particularly true of fine - grained minerals . As a result , a simple field test for identifying beryllium- bearing rock is needed . Recognizing this , technologists of the Federal Bureau of Mines investigated several of the proposed qualitative chemical tests for beryllium . This report describes various modifications of one of these methods to make it more suitable for use in the field . In the modified method , duplicate samples are fluxed -- one with potassium bifluoride and one with potassium bisulfate -- followed by dissolution of salts in water , conversion of the solution to an alkaline condition, addition of morin , and examination of the solution for fluorescence under short -wave ultraviolet light . This method provides a fast , dependable field test for beryllium minerals containing as little as 0.2 percent beryl or its equivalent . The test involves no radiation hazards , and it can be performed by persons having no technical training ; therefore , it should be useful to prospectors in discovering beryllium mineralization .

Jul 1, 1960

By Van E. Shaw, D. J. Bauer

Conversion of euxenite concentrate to sulfates with sulfuric acid and solvent extraction of the yttrium- rare - earth mixture with EHPA were studied to determine extraction and separation characteristics . Digestion with 3.5 pounds of 96 percent sulfuric acid per pound of concentrate at 336 ° C for 4 hours resulted in an easily handled product with a yield in excess of 98 per- A thorium- free product was obtained by calcining the sulfated material for 3.5 hours at 650 ° C prior to leaching with water . Di ( 2 - ethylhexyl ) phosphoric acid solvent is an effective extractant with preference for cerium ( IV ) and heavy - group rare - earth elements including yttrium . Separation of complex rare - earth mixtures into light- and heavy - group fractions is feasible , and these fractions can be further processed to isolate ytterbium , neodymium , and dysprosium by changing processing conditions to obtain separation factors greater than two between these and adjacent elements .

Jan 1, 1965

By V. Sheikhzadeh, M. Saghaeian, N. Esmaeili, R. Hejazi, A. D. Ahmadabadi

The main challenges in most low grade iron ore deposits are finding the optimum flowsheet for beneficiation to achieve a final concentrate from both technical and economic viewpoints. Dry preconcentration techniques are being used to assist in reducing the amount of ROM feed to the plant. In this paper the benefits of utilising a dry cobbing magnetic separation technique for upgrading the product of HPGR in a closed circuit with dry screen 4 and 1.4 mm by performing a pilot scale test work was investigated. The experimental test work was done on two sample types of Yogi BIF magnetite iron ore located in Western Australia. Prior to magnetic separation studies, detailed characterisation of the feed materials including physical, chemical, mineralogical and magnetic properties were carried out. Furthermore, the effects of process parameters: drum rotation speed (1.5, 2.5 and 3.5 m/s), magnetic field intensity (1100 and 3800 gauss) and feed size (minus 4 and 1.4 mm) were investigated. The results revealed that sample type1 with 33.90% Fe could be upgraded to 41.51% Fe by using a stage of 1100 gauss dry magnetic separator with 69.12% weight recovery and 84.36% Fe recovery at a size of 4 mm. Also for sample type2, it is possible to increase Fe grade from 29.84% to above 36.68% with 75.58% weight recovery and 90.32% Fe recovery by applying one stage of 1100 gauss dry magnetic separator to a 4 mm size sample. Keywords: Banded iron formation (BIF), pre-concentration, dry cobbing technique, magnetic separator

Jan 1, 2020

By Kleber da Silva Pazeto

No presente trabalho foram realizadas análises metalúrgicas para determinação das causas da falha em uma tubulação soldada de aço UNS S32750, que conduzia água do mar como captada. Foram realizados testes mecânicos, químicos e metalográficos para verificar a adequação da liga para a presente aplicação, e para investigar as causas do vazamento. Foi possível concluir que a falha foi causada pelo baixo teor de ferrita na raiz da solda, de forma que esta se tornou susceptível à corrosão por pites, ao interagir quimicamente com o meio corrosivo rico em cloretos.

Oct 30, 2017

By Lindaura de Souza Cândido d'Avila

O presente trabalho é parte de um estudo mais abrangente que busca o desenvolvimento da mistura de diferentes tipos de minérios de ferro para a maximização da produtividade na sinterização. Essa etapa do estudo teve o intuito de avaliar as diferentes características do minério de ferro itabirítico e sua influência na produtividade da sinterização em escala piloto. Inicialmente foi realizada a caracterização dos minérios de ferro hematítico e itabirítico oriundos do Quadrilátero Ferrífero. Em seguida, foram testadas em escala piloto misturas de minério de ferro com proporções variadas de minério hematítico e itabirítico. A partir dos resultados de produtividade e de qualidade do sínter obtido foi possível avaliar o efeito do minério itabirítico na mistura de sinterização. Tais resultados indicam diferentes desempenhos desses parâmetros na unidade piloto de sinterização.

Aug 16, 2017

By Anderson Lúcio de Souza

Foram realizados testes completos de pelotamento para avaliar os efeitos da adição de uma solução de cal hidratada ao pellet feed na etapa de pelotamento. Foram preparadas soluções com diferentes concentrações de cal hidratada e após a mistura das mesmas no pellet feed foram realizados testes de pelotamento onde os principais parâmetros de qualidade das pelotas cruas geradas foram avaliados. O diâmetro médio final das pelotas foi o principal parâmetro influenciado pela adição de cal hidratada. A presença dos íons Ca2+ e CaOH+, em função da dosagem de cal, altera o estado de dispersão do minério de ferro, afetando assim o processo de formação das pelotas. Ainda, os cátions Ca2+ presentes no pellet feed interagem com o aglomerante orgânico e com a bentonita, reduzindo a capacidade desses agentes em controlar o crescimento das pelotas.

Aug 1, 2018

By Aprígio Ângelo de Jesus

No presente trabalho, foram avaliados os efeitos do tratamento térmico de alívio de tensões na microestrutura e propriedades mecânicas de juntas soldadas dos aços SA516-70 e SA387-11 (ambos aplicados na fabricação de vasos de pressão). Chapas com 40 mm de espessura de ambos os aços foram soldadas por arco elétrico com arame tubular e, posteriormente, submetidas a tratamento térmico para alívio de tensões. A variação de dureza ao longo da solda e a resistência à tração dos materiais soldados e tratados termicamente foi avaliada. A microestrutura dos materiais soldados foi acompanhada por microscopia ótica convencional. Por meio do tratamento térmico empregado foi possível observar a redução do nível de encruamento nos metais base e zonas termicamente afetadas das juntas em ambos os materiais com aumento de ductilidade no aço SA516-70.

Aug 8, 2018

By Jorge Alberto Soares Tenório, Denise Crocce Romano Espinosa, Beatriz Peralta Oruê

Manganese, a toxic mineral, related to manganism may have high added value for the steel industry. The difficulty in obtaining manganese encourages the exploration of new secondary sources such as the lateritic nickel effluent. In Brazil, nickel reserves are predominantly lateritic, making the country a potential producer. For the tests, a synthetic solution was used which simulates the lateritic nickel effluent from leaching. The oxidative precipitation with ozone occurred at the oxygen flow rates: 0.5; 1.0 and 2.5L/min, at the original pH 1.5 at 21°C in a 500 mL bubble column reactor. O3 was produced in the benchtop generator feed by 99% oxygen. The ozonation time was determined by the oxidation potential1.55V. The ozonated solution was centrifuged and filtered. The filtrate and collected samples were characterized in ICP-OES. Optimization tests with ultracentrifuge were performed. The best precipitation reached 97% at 0.5L/min O2 at 6.07 ± 0.045mg/min of O3 dosage and resulted in a solution 10-15mg/L Mn+2, above 1mg/L, maximum value acceptable by Conama 2011, to be retreated before being discharged into the water body or being reused as a manganese source.

Oct 3, 2019

By Antônio Augusto de Morais Piau, Miguel Araujo de Vasconcelos Filho, Bruno Mynelly Galdino de Sousa

Sludges and dusts generated by steel mills usually cause environmental problems and has a high cost solution. This presentation offers a different aproach to the problem with a solution that not only solves the enviromental issue but also brings great savings to the mill. This technology, reuses dusts and sludges in the sintering process, after they are mixed to the right composition.

Oct 1, 2019

By Caio Fernando Dias Guillen

Ao longo dos anos os aços para moldes plásticos tornam-se cada vez mais importantes no campo de aços ferramenta. A aplicação destes materiais estende-se pela indústria de processamento de diversos polímeros. Assim são esperadas propriedades específicas dos aços utilizados em cada condição: resistência mecânica, polibilidade, usinabilidade, resistência à corrosão e resposta à texturização são fatores determinantes na escolha do aço. O presente trabalho objetivou caracterizar, com relação às propriedades mais importantes para os moldes plásticos, uma gama selecionada de aços. Através de ensaios foi possível elaborar um quadro comparativo que define os aços que melhor respondem à determinada solicitação. A caracterização dos aços ocorreu através de ensaios de tenacidade, impacto, tração, dureza, características micorstruturais.

Jul 30, 2018

By A. D. Garman

This paper presents one of a series of digests of foreign mining legislation and court decisions which is being prepared in advance of a general report relative to the right of American citizens to explore for minerals and to own and operate mines in various foreign countries. This interpretation of the laws of Guatemala has been prepared from the best available information in Washington, but is released subject to correction and amplification, if necessary, by the proper American diplomatic and consular officers to whom it is being referred through the courtesy of the Department of State.

Oct 1, 1929