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By Rubens Lincoln Santana Blazutti Marçal

O objetivo deste trabalho foi avaliar o comportamento do niobato de alumínio (AlNbO4) como aditivo na sinterização de alumina (Al2O3). O composto AlNbO4 foi sintetizado através de reação no estado sólido dos compostos Al2O3 (0,5 Mol) e Nb2O5 (0,5 Mol). A técnica de difração de raios X foi utilizada para comprovar o sucesso da síntese. Para o estudo da sinterização, o composto sintetizado (AlNbO4) foi adicionado à alumina nas concentrações de 0, 1, 2 e 3 % em peso e prensados unixialmente à 60MPa. A sinterização foi conduzida à 1400 ºC. Os corpos sinterizados foram caracterizados quanto a densificação, pelo método de Arquimedes, e microdureza superficial Vickers. Os resultados demonstraram clara influência do composto AlNbO4 na sinterização da alumina elevando os valores de densificação e microdureza quando comparados à alumina sem adição.

Oct 30, 2017

By Alexandre Gonçalves Andrade, Crisley Dellaqua Pacheco, Gabriel Miranda Teixeira, Aline Maria Santoro Nasaré, Tatiane Ferreira Alvarenga

Diffuse emissions are that directly related to particulate matter suspended from civil structures, materials disposed in conveyor belts carried out by wind, stack e reclaimers operations and that one where dust collectors are not able to act correctly. Vale implemented in the last years a unique system capable to measure this kind of dust, called RAMPs (Dust Monitoring Automatic Network), which creates an analytical net in Tubarao industrial site, located in Vitória, ES. In order to prevent diffuse emissions in Tubarao’s pellets stockyard, it was proposed and developed a predictive model based on operational and climate variables available on the site, using big data and advanced analytics tools. The models developed shows to be adherent to the real emissions rates measured by the RAMPs and proved to be an efficient tool to predict emissions over the internal target with 4 hours of precedence.

Oct 1, 2019

By Daniele Tolazzi

Electric Arc Furnaces keep evolving into highly powerful melting units, shrinking taptotap times by increasing the effectiveness of the energy sources and the material fluxes used in the process. Steelmakers are targeting to increase the efficiency of their injection package in order to reduce the overall conversion costs, seeking for technologies specifically designed to promote the metallurgical reactions in a predictable and reproducible process automatically controlled at the correct timing. Many technological enhancements have focused in the gas management, improving the burner design and the penetration capacity of oxygen injectors, dedicated to decarburization and the other exothermic reactions. Instead, lower evolution efforts have been addressed to engineered solutions for managing the addition of solid materials required in slag forming, although they are playing a key role in EAF process optimization, as well. The paper describes the latest solutions designed to manage efficiently the injection of fuel, oxygen and powdered materials in several EAFs and presents the operational results achieved. Accurate control of reliable additions of coal, lime and magnesia proved crucial for the control of the slag FeO and viscosity, generating stable foamy slag and producing cleaner steel.

Aug 17, 2017

By Wemerson Junio Gandra

Para a redução do minério de ferro no alto-forno é necessária a utilização de uma fonte de carbono, que pode ser encontrada no carvão mineral e/ou carvão vegetal. Diante do cenário atual, a busca constante por maior competitividade, associada ao atendimento da qualidade e aos requisitos ambientais, exige a implementação de várias ações alternativas no processo de fabricação de gusa. Dentre elas, destaca-se a utilização de combustíveis alternativos no sistema de injeção dos altos-fornos, como por exemplo, a substituição parcial do carvão mineral pelo carvão vegetal. Do ponto de vista ambiental, é altamente favorável a utilização de uma fonte renovável de carbono. O objetivo desse trabalho é apresentar a adequação do processo, desde o recebimento do material até sua injeção nos altos-fornos, bem como os resultados já alcançados e os desafios futuros. A utilização do carvão vegetal na mistura de carvão pulverizado resulta em flexibilidade na utilização de matérias primas e contribui para preservação do meio ambiente.

Oct 30, 2017

By Breno Totti Maia

In the present paper, a new energy balance equation was developed, considering the slag phase, in order to define the effects of jet penetration and determine a new value for the factor K. The factor K measure the resistance to momentum transference between exit nozzle and metallic bath. The experiments were performed based on the same conditions of the article used as a comparison. The results showed the same behavior between the experiments and it was possible to determine a new value for the factor K, which changed from the unit order for the metal phase system to hundredths order for the metal and slag phase systems. These results are considered unprecedented.

Aug 17, 2017

By Afshin Sadri

One of the main reasons for blast furnace reline is the loss of refractory lining, particularly in the hearth and taphole regions. Intense operation of the blast furnace can result in extensive refractory wear and deterioration. This can then affect the continuity of the operation and the furnace campaign life. Novo-Lipetsk (NLMK) and Hatch developed a systematic approach to monitor the condition of blast furnace hearth linings using Acousto Ultrasonic-Echo (AU-E), a non-destructive testing system developed by Hatch. Continuous and periodic inspections of blast furnaces revealed areas with accelerated refractory deterioration, formation of elephant foot, extent and speed of refractory wear, as well as cracks and other anomalies. Improvement in coke quality, stave washing, the addition of titania, and other changes were recommended and implemented to prolong furnace life while maintaining the intensity of furnace operation. This paper demonstrates how the coordinated efforts between NLMK and Hatch resulted in prolonging the blast furnace campaign life.

Aug 17, 2017

By Andreas Volkert

Energy efficiency, equipment reliability and cost reduction are of the key factors in any efficient plant. Badische Stahlwerke (BSW) started using its own burner technology in 2001, this was developed by Badische Stahl-Engineering (BSE). Over the past 15 years, Badische improved all aspects of its Virtual Lance Burner (VLB), to perfectly fit all steelmaking requirements. This tiltable VLB was first tested at BSW’s electric arc furnace no. 2 in 2012. Promising results like reduction of refractory wear, energy efficiency, reliability, etc., were obtained. At the same time the existing VLB system was further improved with regards to the design of the water-cooled copper box. Today in 2016 both EAFs at BSW are equipped with the new patented tiltable system and the new copper box design. The paper will describe the results of the past years at Badische, but will also show the performance at other installations.

Aug 17, 2017

By Dustin Vickress

The premature failure of copper staves in the lower stack and bosh is frequently the cause for an interim blast furnace repair at great cost to the blast furnace owner. Protective accretions may form on the stave hot face, but when these accretions are lost the staves can begin to deteriorate both due to abrasive wear from exposure to the descending burden materials and due to thermal cracking from exposure to hightemperature process excursions. These mechanisms can lead to failure of cooling passages, which forces blast furnace operators to shut off these channels, accelerating the rate of copper stave wear. Finger cooler technology was developed to extend blast furnace life by restoring cooling to damaged staves. Evidence for their effectiveness is presented herein in the form of experimental test work and conjugate heat transfer (CHT) analysis carried out using computational fluid dynamics (CFD) simulations. These tests demonstrate that under typical blast furnace excursion conditions, a stave fitted with finger coolers will undergo half the temperature rise of a stave fitted with conventional cigar coolers.

Aug 17, 2017

By Jim Belous

Fluid Dynamic Modeling (FDM) was used to develop solutions how to eliminate the fugitive emissions from the meltshop building and to comply with the EPA “6% opacity from the furnace operations” rule. Secondary Emission Control (SEC) system performance was simulated by an inverted 1:96 scale Plexiglas model of the entire meltshop, utilizing the negative buoyancy effects of saline solution in water. Test results show that with the installation of the internal partition wall which separates furnace aisle from the caster aisle, significant improvement of the SEC system is achievable, thereby avoiding large expenditure for the expanding a fume collection system capacity.

Aug 17, 2017

By Ismar Antônio Sardinha

Usually outer straight steel tubes are used to blow supersonic oxygen into LD converters (BOF) to make liquid steel, although conical tubes are used too. Inner tube for oxygen blow and intermediary tube for water IN and water OUT are normally straight steel tubes. Present paper shows the influence of outer tube shape and metal used to in lance cooling and, consequently, a skull retention on lance surface. There are two parameters more important related to lance cooling: velocity of water out and the total lance cooling by addition of thermal conductivity of outer tube metal to it. For this comparison outer tubes are made of carbon steel or copper, and can be straight or conical. As related to velocity of water OUT, outer straight tubes have bigger efficiency than conical tubes. As related to total lance cooling, outer tube metal made of copper has much bigger efficiency than steel because of its thermal conductivity 7 to 12 times more depending on work temperature. The lance cooling has much bigger efficiency for the patented SKULLS3® technology with no skulls on the lance and no skulls into the mouth of LD converters (BOF).

Aug 17, 2017

By Michael Brandner

HSM can be divided into different groups such as Conventional HSM with Roughing stands and HSM without Roughing stands = Mills with just finishing stands. The roll requirements for different stands are quite different. In Roughing stands the temperature of the slab is very high. Therefore the resistance against thermal wear/fatigue is the most dominating factor. Today mostly Chrome Steel, Semi HSS and HSS rolls are applied. A comparison and evaluation of such rolls will be described. In the finishing mill the tendency/wish is to use HSS rolls in all the stands. The grade HSS is defined by at least a certain amount of carbide forming elements such as V, W, Mo, Nb etc. The matrix and other precipitations can be adjusted according to the need and situation in the mill. In the pre-finishing stands the HSS is already well introduced. In the last finishing stands the original HSS tended to stick and the cobble rate increased. New development decreased the problem and gave some very promising results. In the last finishing stands beside the high performance a higher resistance against incidents is needed. Solutions in this direction including e.g. residual stresses and special core material will be discussed. Proper testing and grinding procedures can avoid losses and reduce the TCO. Data sourcing and evaluation in regards of rolling and grinding is the key for the optimization of the TCO. Several examples and comparison between different applications will be given in detail and explained. Future possibilities will be discussed as well as results of latest trials in mills.

Aug 17, 2017

By Yasser Ghobara

Phosphorus is a problematic impurity that has challenged steelmakers for decades. Steel producers have developed specific technologies to eliminate phosphorus prior to and during steelmaking. These process technologies reduce phosphorus to various degrees and increase the cost of making steel. The state-of-the art dephosphorization technologies are described and operating costs compared for each of the established technologies. Costs are discussed in terms of price penalties for high P iron ore and selling premiums for low P steel. From this, strategies to control P in a cost effective manner are described.

Aug 17, 2017

By Jorge Madias

O trabalho está centrado na análise comparativa de normas de vinte paises/regiões sobre vergalhão, escolhidos levando em conta os principais paises productores, exportadores, e consumidores deste produto para a construção civil. São comparadas as propriedades mecânicas: limite de escoamento, resistência à tração, elongamento à rotura, elongamento uniforme, relação escoamento/tração), a análise química, testes especiais como fadiga e adherência e outros ítens. Tambén é tida em conta a evolução dos quesitos das normas ao longo do tempo. O foco é o comportamento anti seismo do vergalhão.

Oct 30, 2017

By Douglas Glenn Stalheim

Production of structural hot strip coils in yield strengths up to 700 MPa and higher is increasing worldwide. In addition to requiring higher strengths, structural designs require good formability, toughness and weldability. Toughness and formability come from optimization of ductility properties while weldability comes from lower carbon equivalent alloy designs. The key to the production of optimized cost effective hot strip produced structural coils is to create the correct balance of a proper alloy/processing design to create as fine and uniformly distributed cross sectional grain size as possible. In addition to the creation of the fine/uniformly distributed cross sectional grain size, the correct microstructure needs to be created. In the higher yield strength grades, not only does the grain size/distribution play a role but a proper understanding and control of microalloying precipitation kinetics is required. This paper will present various examples of hot strip alloy designs to produce cost effective hot strip structural coil in yield strengths up to 700 MPa with good ductility and weldability. In addition, steelmaking/casting parameters will be discussed to assure successful production. Optimized reheating, rolling and cooling parameters of these alloy designs will be introduced in an accompanying paper.

Aug 17, 2017

By Andreas Rohrhofer

Reliable high end automation and process optimization systems are main factors for excellent product quality, safe operation and maximized plant performance in the steel industry and its designated environmental plants. Primetals Technologies introduces new automation packages for consequent safe and cost efficient production. Many areas within the steelplant interested to be monitored and measured automatically are not implemented in the automation system due to limited access or technical reasons. A wireless, self-organizing network facilitates wide ranging data transmission in previously inaccessible areas and opens up a wide range of new opportunities. With Fluid Guard a system to detect leakages with highest accuracy and reacts properly for all kind of water cooled circuits is available, improving the safety in steelmaking process. Lance Guard can be utilized for all fully automatic and semi-automatic lance appliances, but is especially suitable for the products of Primetals Sublance Standard/2.0 and LiquiRob applications, since these systems make seamless integration particularly simple. Manual lance appliances may also be tested and diagnosed. Environmental plants have become a main part in steelmaking plants. Highest performance in combination with optimized energy consumption is the main target in Primetals Technologies’ innovations in automation optimization packages for dedusting systems. A new approach for preventive maintenance and operator assistance is introduced with the Acoustic Expert System. In combination with the new Ask cloud based system, Primetals enables a 24/7 monitoring and a whole lifetime observation of any equipment within a steelplant. Furthermore it is now enabled to check the condition of the plant at a fingertip at any time.

Aug 17, 2017

By Raíra Morais Alcântara Nunes

No laboratório de fundição da Universidade Federal do Ceará, foi desenvolvido novas técnicas de fundição de precisão visando reduzir os custos utilizando materiais reciclados, como sucatas e cinzas residuais de termoelétrica. Ademais, ocorreu a preparação das peças modelo, utilização de silicone para a produção de moldes, preparação das peças em cera e canais de vazamento, fabricação da casca cerâmica refratária, vazamento da liga metálica (ZAMAC), obtenção da peça rústica e processo de usinagem. Desse modo, concluímos nosso projeto dando utilidade para um material poluente e reciclando sucata de zinco e, por consequência, baixando os custos desse processo e podendo haver, também, a geração de emprego para comunidades carentes.

Oct 30, 2017

By Alexandre da Silva Rocha, Luiz Maurício Barreto de Azevedo, Leonardo Sales Araújo, Rafael Menezes Nunes, Matheus Campolina Mendes, Thiago Marque Ivaniski, Luiz Henrique de Almeida

Superliga 718 é uma liga de níquel endurecida majoritariamente por precipitação controlada. As suas principais aplicações são nas indústrias aeroespacial, óleo e gás e nuclear devido a capacidade da manutenção das suas propriedades desde a temperaturas criogênicas até aproximadamente 650°C. Para atenuar fenômenos deletérios de natureza intergranular, neste material são feitos tratamentos termomecânicos específicos para se se aumentar a fração dos contornos do tipo Σ3n.Portanto, o objetivo deste trabalho é analisar duas rotas termomecânicas capazes de aumentar a fração destes contornos por ciclos iterativos de deformação por trefilação, seguido de solubilização em temperaturas sub-solvus  e super-solvus  e envelhecimento além de avaliar a influência da trefilação na precipitação de  mesotextura e tamanho de grão  Para a análise microestrutural, foram feitas imagens de microscopia eletrônica de varredura(MEV) e difração de elétrons retroespalhados (EBSD). Foi feita simulação computacional por elementos finitos do processamento termomecânico para avaliar a distribuição e o grau da deformação no processo. Os resultados mostram que é possível atingir uma elevada fração de contornos do tipo Σ3n pelo processo de trefilação, contudo, a heterogeneidade da deformação ao longo da seção radial influencia em parâmetros microestuturais .

Oct 10, 2019

By Marco Polo da Silva Peixoto

O presente trabalho tem por objetivo apresentar a redução do número de queima de placas de refrigeração no Alto Forno 2 da C.S.N, onde são destacadas as principais ações operacionais implementadas para obtenção dos resultados até a presente data e a redução de perdas no custo e elevação da produtividade.

Aug 16, 2017

By Saul Garcia Hernandez

The research work objective is to study a new ladle shroud internal design to reduce the slag emulsification in the tundish during ladle transient periods. A 3D mathematical model of the tundish was created to solve the fundamental equations, a turbulence model, and a multiphase model. The results show that using a conventional ladle shroud, the fluid is delivered with an excessive amount of kinetic energy being dissipated inside the tundish bath, generating strong mixing flow patterns and entrapping a massive amount of slag. In the other hand, the proposed ladle shroud dissipates the kinetic energy before the fluid enters the tundish promoting less intense mixing patterns; thus, the amount of slag emulsification is reduced significantly. Consequently, if the internal design of the ladle shroud is able to dissipate the kinetic energy before the fluid enters the tundish, it shall be possible to reduce considerable the slag emulsification and the slag opening area.

Aug 17, 2017

By Claudeir Carvalho Silveira

A necessidade da indústria automobilística de redução de peso, desenvolvimento de designs arrojados e aumento da resistência a corrosão dos automóveis obrigou as indústrias siderúrgicas a produzirem aços galvanizados de alta resistência. Entretanto, para que haja este desenvolvimento é necessário maior conhecimento do comportamento dos revestimentos galvanizados quando submetidos a processos de estampagem. Desgastes da superfície galvanizada, formação de pós, redução da resistência a corrosão e atrito das superfícies são aspectos importantes a considerar no projeto do ferramental de estampagem. Este trabalho teve, portanto, como objetivo a avaliação do efeito dos revestimentos Galvanizing e Galvannealed no coeficiente de atrito de um aço Dual Phase 600. Para avaliação do coeficiente de atrito foi utilizado um tribômetro de ferramenta plana que simula o atrito na estampagem de peças. O trabalho apresenta ainda a caracterização microestrutural do revestimento realizada por microscopia ótica (MO) e eletrônica de varredura (MEV) e espectroscopia de energia dispersiva (EDS). Para avaliação das propriedades do substrato e do revestimento foram utilizadas também medidas de Microdureza. Após a realização dos ensaios, foi caracterizada ainda a evolução dos revestimentos após desgaste promovido pelo tribômetro de ferramenta plana e a identificação e caracterização do fenômeno de stick-slip.

Aug 8, 2018