This work investigates the interactions of carbonaceous materials (metallurgical coke, natural graphite and HDPE/coke blends) with three EAF slags [FeO: 24% to 32%]. Experiments were conducted using the sessile drop technique (1500??C-1600??C) with off-gases (CO, CO2) measured using an IR analyzer; the wetting behaviour was determined from contact angle measurements. Estimation of slag foaming behaviour was determined from the droplet volume changes calculated using specialized software. At 1550??C, all slags were non-wetting with coke due to increased surface tension due to sulphur. At 1550??C, slag 1 was initially non-wetting on natural graphite due to gas entrapment in the slag droplet; the wetting improved after that. Other slags showed comparatively better wetting. At 1600??C, all slags were non-wetting with coke. Slags showed a shift from non-wetting to wetting behaviour with natural graphite. Slag/coke reactions produced high off-gases levels causing extensive FeO reduction; gas entrapment in the slag was poor (small volume droplets). Slag/natural graphite interactions revealed both slow gas generation rates and FeO reduction, and excellent gas entrapment (higher droplet volumes) with minor changes in slag properties due to low ash levels. The iron oxide reduction rates were determined to be 1.54x10-5 and 4.2x10-6 mol.cm-2/sec (Slag 1, 1550??C) for metallurgical coke and natural graphite respectively. Slag interactions with coke/HDPE blends showed increasing off-gas levels with increasing HDPE levels. Blend#3 produced the highest off-gas levels, extensive FeO reduction and displayed significantly higher slag foaming and better wetting compared to coke. Our line on trends compared well for slag/carbon interactions and resulted in deceased specific energy consumption and carbon usage and increased productivity. These findings have enhanced the possibility of utilizing polymeric wastes in blends with coke in EAF steelmaking for slag/carbon interactions.

In the present thesis a study on the thermal state of steelmaking ladles was undertaken. The transient hot wire method was verified for thermal conductivity measurements on metallurgical slags and applied to ladle slag measurements. Temperature measurements on ladles in an industrial environment were carried out. The emissivities of the outer and inner shells of steelmaking ladles were investigated. Two dynamic models were developed to predict the heat transfer and fluid flow in a preheating and teeming ladle. The gathered thermal conductivity values for ladle slag were used to study the effect of the slag layer on the top surface of the melt on heat transfer and fluid flow in a teeming ladle. In the first stage, the transient hot-wire method was verified to measure the thermal conductivity of metallurgical slags at steelmaking temperatures. A numerical model was developed, cold model experiments were conducted and test measurements using a high temperature experimental setup were carried out. To minimize natural convection and to obtain more reliable measurements, the crucible diameter, the hot-wire diameter, the applied current, the position of the wire in the crucible and the cooling on the upper surface of the crucible were studied. Investigations into the choice of sheathing material of the circuit exposed to the slag were also made. It was found that only certain materials were suitable for slag measurements depending on slag composition and temperature. The electrical resistivity of the hot wire was measured to make the thermal conductivity calculation more reliable. The wire diameter also played a major role due to the heat generation per surface area. The thermal conductivity should be derived from the values measured during the first seconds. In this initial stage, the effect of the natural convection as a function of the wire position in the crucible, the cooling on the top surface and the diameter of the crucible are negligible. A compromise has to be made in choosing the electrical current, since higher current results in higher sensitivity but at the same time in more natural convection. In the second stage, the thermal conductivities of four different ladle slags were measured at 1773 K, 1823 K, 1873 K and 1923 K using the transient hot wire method. Very good reproducibility was obtained. The thermal conductivity did not vary substantially with the variation of slag composition at 1873 K and 1923 K, at which the slag samples were all entirely liquid. The thermal conductivities were low. It was found that the precipitation of solid phase resulted in a considerable increase of thermal conductivity. In the third stage, a two dimensional model was developed in order to predict the temperature distribution in the ladle wall during the preheating process. The model calculated the heat transfer and the velocity field in the gas phase inside the ladle as well as the heat transfer in the solid walls during the preheating process. Measurements of the temperature profiles in an industrial ladle were carried out using an infrared thermography. The measurements were made both inside and outside the ladle. The model predictions were found to be in reasonably good agreement with the measured temperatures. It was found that the preheating time could be minimized when the working lining became thinner. The effect ofthe distance between the lid and the ladle was also studied by the model. The results indicated that there was no significant temperature change on the upper side wall of the ladle. On the lower side wall and bottom the temperature changed slightly. The temperature difference in the lower part of the ladle could be explained by the larger flame distance from the bottom layer. In the fourth stage, a two dimensional axisymmetric model was developed to predict the heat flux in a steelmaking ladle during the teeming process. The model predicts dynamically the flow fields in both the liquid phase and the gas phase along with the movement of the liquid upper surface. The model also predicts the temperature distributions in the liquid metal, gas phase and all layers in the ladle wall. Again, industrial measurements were performed using an infrared thermography, both inside the ladle after teeming and at the wall outside the ladle during the whole process sequence. The model predictions were found to be in agreement with the measured data. It was found that the heat transfer to the surrounding atmosphere and the conductivity of the highly insulating layer were the most important factors for the heat loss. The decrease of the thickness of the working lining was found to have limited effect on the total heat flux. In the fifth and final stage, the effect of the slag layer on the top surface of the melt, on fluid flow and on heat transfer in a teeming ladle was investigated theoretically. The two dimensional axisymmetric model developed in the fourth stage was used. To predict the effect of the slag layer a stationary heat conduction boundary condition including thermal conductivity and slag layer thickness was employed. Different calculations with differing thermal conductivity values for the slag layer were carried out. The calculations showed that the effect of the slag layer was insignificant. This could be explained by the similarity of the thermal conductivity of slag and gas phase. / <p>QC 20121010</p>

In this study it was aimed to analyse refining processes such as decreasing reducible oxide content of ladle slag with affecting parameters in low carbon aluminum killed grades and for the research Erdemir low carbon steel grades 7112K and 7110K are selected. There was a negative correlation between reducible oxide amount in ladle slag and desulphurization capacity of ladle slag with metal-slag reaction and steel internal cleanliness. To refine these properties of slag, aluminium dross, which was aluminium production discard and has a metallic content around %30-35 was used and after ladle treatment operation, decrease in reducible oxides such as FetO, MnO, SiO2, P2O5 was analysed. After the study it was observed that 653 kg. of converter slag leaked during tapping of steel and SiO2 ve P2O5 content of ladle slag had negligible change after ladle treatment. According to the results, it is observed that initial %10-12 (FetO + MnO) content was reduced to % 4.5-5.0 (FetO + MnO) after ladle treatment with use of aluminium dross. Beside of this, in order to see the effect of this slag reduction on steel cleanliness, low carbon aluminium killed grades were compared with ultra-low carbon aluminium killed grades having (FetO + MnO) content of %16-17 in slag. It was seen that reoxidation of aluminium (loss of dissolved aluminium) during continuous casting for ULC (ultra-low carbon) gradesis 144 ppm but for LC grades it was 94 ppm and it was being expected that ULC steel group would have higher inclusion content after casting.

This work investigates the interactions of carbonaceous materials (metallurgical coke, natural graphite and HDPE/coke blends) with three EAF slags [FeO: 24% to 32%]. Experiments were conducted using the sessile drop technique (1500??C-1600??C) with off-gases (CO, CO2) measured using an IR analyzer; the wetting behaviour was determined from contact angle measurements. Estimation of slag foaming behaviour was determined from the droplet volume changes calculated using specialized software. At 1550??C, all slags were non-wetting with coke due to increased surface tension due to sulphur. At 1550??C, slag 1 was initially non-wetting on natural graphite due to gas entrapment in the slag droplet; the wetting improved after that. Other slags showed comparatively better wetting. At 1600??C, all slags were non-wetting with coke. Slags showed a shift from non-wetting to wetting behaviour with natural graphite. Slag/coke reactions produced high off-gases levels causing extensive FeO reduction; gas entrapment in the slag was poor (small volume droplets). Slag/natural graphite interactions revealed both slow gas generation rates and FeO reduction, and excellent gas entrapment (higher droplet volumes) with minor changes in slag properties due to low ash levels. The iron oxide reduction rates were determined to be 1.54x10-5 and 4.2x10-6 mol.cm-2/sec (Slag 1, 1550??C) for metallurgical coke and natural graphite respectively. Slag interactions with coke/HDPE blends showed increasing off-gas levels with increasing HDPE levels. Blend#3 produced the highest off-gas levels, extensive FeO reduction and displayed significantly higher slag foaming and better wetting compared to coke. Our line on trends compared well for slag/carbon interactions and resulted in deceased specific energy consumption and carbon usage and increased productivity. These findings have enhanced the possibility of utilizing polymeric wastes in blends with coke in EAF steelmaking for slag/carbon interactions.

O setor siderúrgico, assim como os demais setores da indústria, vem buscando alternativas para a redução dos custos de produção e aumento de produtividade. Em aciarias elétricas, os principais custos de produção do aço podem ser divididos, de forma simplificada, entre o custo dos insumos e o custo das matérias primas. Os refratários estão entre os cinco maiores custos na produção do aço em usinas semi-integradas. Entretanto, o conhecimento detalhado da microestrutura e do comportamento desses materiais ainda é bastante restrito aos seus fabricantes. Tendo em vista a importância dos refratários na produção do aço, este trabalho teve como objetivo gerar conhecimento acerca de sua microestrutura e comportamento em operação, com foco na diminuição do consumo e maximização dos lucros da empresa. Para tal, com o intuito de conhecer detalhadamente sua microestrutura e prever seu desempenho, foram realizadas análises de caracterização em laboratório e testes que simularam as condições de operação. Após os testes laboratoriais, os materiais selecionados foram testados em operação em forno elétrico a arco, buscando encontrar o melhor conjunto de materiais sob o ponto de vista de estabilidade do processo e custo de refratários. O cenário que apresentou melhores resultados em relação à performance e ao consumo específico foi a configuração A, onde foram utilizados os tijolos A, massa de soleira X, massa de reparo K e canal EBT P. Além disso, a substituição do tijolo C pelo tijolo A gerou uma redução de custo de 40%, e o conhecimento gerado com a caracterização do canal EBT proporcionou uma redução de 29,9% no preço desse item. / The steel industry, like other sectors of the industry, is seeking alternatives to reduce production costs and increase productivity. In electric steelworks, the main steel production costs can be divided, in a simplified way, between the cost of inputs and the cost of raw materials. Refractories are among the five largest costs in steel production in semi-integrated mills (mini-mills). However, detailed knowledge of the microstructure and behavior of these materials is still quite restricted to their manufacturers. Given the importance of the refractories in the production of steel, this study aimed to generate knowledge about their microstructure and behavior in operation, focusing on the reduction of consumption and maximization of profits. For that, in order to know in detail the microstructure and predict its performance, characterization analyzes and tests simulating the operating conditions were performed in the laboratory. After laboratory tests, the selected materials have been tested in operation in electric arc furnace, seeking to find the best set of materials from the point of view of stability of the process, and cost of refractories. The scenario that best results presented, in terms of performance and the specific consumption, was Configuration A, where bricks A, ramming mix X, repair mix K and EBT P were used. Moreover, the replacement of Brick B by brick A, generated a cost reduction of 40%, and the information gathered with the characterization of EBT, reduced the price of that item by 29.9%.

O setor siderúrgico, assim como os demais setores da indústria, vem buscando alternativas para a redução dos custos de produção e aumento de produtividade. Em aciarias elétricas, os principais custos de produção do aço podem ser divididos, de forma simplificada, entre o custo dos insumos e o custo das matérias primas. Os refratários estão entre os cinco maiores custos na produção do aço em usinas semi-integradas. Entretanto, o conhecimento detalhado da microestrutura e do comportamento desses materiais ainda é bastante restrito aos seus fabricantes. Tendo em vista a importância dos refratários na produção do aço, este trabalho teve como objetivo gerar conhecimento acerca de sua microestrutura e comportamento em operação, com foco na diminuição do consumo e maximização dos lucros da empresa. Para tal, com o intuito de conhecer detalhadamente sua microestrutura e prever seu desempenho, foram realizadas análises de caracterização em laboratório e testes que simularam as condições de operação. Após os testes laboratoriais, os materiais selecionados foram testados em operação em forno elétrico a arco, buscando encontrar o melhor conjunto de materiais sob o ponto de vista de estabilidade do processo e custo de refratários. O cenário que apresentou melhores resultados em relação à performance e ao consumo específico foi a configuração A, onde foram utilizados os tijolos A, massa de soleira X, massa de reparo K e canal EBT P. Além disso, a substituição do tijolo C pelo tijolo A gerou uma redução de custo de 40%, e o conhecimento gerado com a caracterização do canal EBT proporcionou uma redução de 29,9% no preço desse item. / The steel industry, like other sectors of the industry, is seeking alternatives to reduce production costs and increase productivity. In electric steelworks, the main steel production costs can be divided, in a simplified way, between the cost of inputs and the cost of raw materials. Refractories are among the five largest costs in steel production in semi-integrated mills (mini-mills). However, detailed knowledge of the microstructure and behavior of these materials is still quite restricted to their manufacturers. Given the importance of the refractories in the production of steel, this study aimed to generate knowledge about their microstructure and behavior in operation, focusing on the reduction of consumption and maximization of profits. For that, in order to know in detail the microstructure and predict its performance, characterization analyzes and tests simulating the operating conditions were performed in the laboratory. After laboratory tests, the selected materials have been tested in operation in electric arc furnace, seeking to find the best set of materials from the point of view of stability of the process, and cost of refractories. The scenario that best results presented, in terms of performance and the specific consumption, was Configuration A, where bricks A, ramming mix X, repair mix K and EBT P were used. Moreover, the replacement of Brick B by brick A, generated a cost reduction of 40%, and the information gathered with the characterization of EBT, reduced the price of that item by 29.9%.

Made available in DSpace on 2015-05-08T14:53:43Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 957374 bytes, checksum: e23cd9d17f61c26c6a38fae6c9d85a0e (MD5) Previous issue date: 2010-07-23 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / This research has as main objective to propose an alternative use for a ERP tool to generate information that permit incorporation of control of environmental spending on management system in a steel industry. For this, present a literature review with the evolution of environmental issues, the main methods and costing systems and some existing approaches to issue environmental costs. The searched literature supported the theoretical analysis of the costing method in an existing steel plant and how it treats its costs of environmental management. The field research was based on the identification and analysis of the costing method and the environmental management system existing in the steel industry investigated, which led to the development and implementation in a pilot area of an ERP tool capable of identifying spending on environmental management. The results showed that the search dests costing methods are insufficient for analysis of environmental costs and therefore the developing of a tool capable of identifying the costs of environmental management, which hitherto were hidden in the process, became is essential for the incorporation of control of these expenses in the management system of the company studied. / A presente pesquisa tem como objetivo principal propor uma alternativa de uso para uma ferramenta de um ERP para gerar informações que permitam a incorporação do controle dos gastos ambientais no sistema de gestão de uma indústria siderúrgica. Para isso, apresenta uma revisão bibliográfica com a evolução da questão ambiental, os principais métodos e sistemas de custeio existentes e algumas abordagens para a variável custos ambientais. Este referencial teórico subsidiou a análise do método de custeio existente em uma usina siderurgia e a forma como esta trata os seus custos com a gestão ambiental. A pesquisa de campo baseou-se na identificação e análise do método de custeio e do sistema de gestão ambiental existentes na indústria siderúrgica pesquisada, o que proporcionou o desenvolvimento e implantação, em uma área piloto, de uma ferramenta de um ERP capaz de identificar os gastos com gestão ambiental. Os resultados desta pesquisa mostraram que os métodos de custeio existentes são insuficientes para análise dos custos ambientais e que a ferramenta desenvolvida foi capaz de identificar os custos da gestão ambiental, que até então estavam ocultos no processo, tornando-se fundamental para a incorporação do controle destes gastos no sistema de gestão da empresa estudada.

O uso de escoria de aciaria, principal subproduto das industrias siderúrgicas do processo de conversão do ferro gusa em aço, como matéria-prima na produção de cimento Portland a partir de substituições de parte da escoria de alto forno, apresenta benefícios econômicos e ecológicos, visto que um resíduo industrial tornar-se-á matéria-prima na fabricação do cimento, reduzindo custo de energia, material e depósitos para estocagem de resíduos. Para tal estudo, a escória de aciaria foi submetida a refusão e a diferentes taxas resfriamento, com o objetivo de formar escorias com diferentes graus de cristalinidade. Após resfriamento foram conformados corpos de prova com adição ao cimento Portland de 0; 1,8; 3,6 e 5,4% em peso de escoria de aciaria. Foram determinados tempo de início e final pega, resistência a compressão após 3, 7, 28 e 91 dias da conformação dos corpos de prova, expansibilidade a quente e a frio. Os resultados confirmam que a escória de aciaria apresenta potencial para ser utilizada na indústria cimenteira. A verificação da influência da adição das escorias dará suporte para a Companhia Siderúrgica Nacional (CSN) decidir quanto a viabilidade da mudança do processo atual de resfriamento e quanto a destinação do resíduo. / The use of steel slag, the main byproduct of the steel industries of the process of converting pig iron into steel as raw material for the production of Portland cement by replacing part of blast furnace slag, offering economic and ecological benefits, as that an industrial - waste becomes the raw material in cement production, reducing energy costs, equipment and tanks for storage of waste. For this study, steel slag was subjected to remelting and cooled at different rates, with the goal of forming slag with different degrees of crystallinity. After cooling, specimens with addition to Portland cement of 0, 1,8; 3,6 and 5,4% steel slag were conformed. Were determined the start time and end handle, compressive strength after 3, 7, 28 and 91 days of conformation, hot and cold expandability. The results confirm that the steel slag has the potential to be used in the cement industry. The verification of the influence of the addition of slag will support the National Steel Company (CSN) on the feasibility of changing the current cooling process and the allocation of the new waste.

O aumento da demanda por aços cada vez mais exigentes, em termos de composição química e limpidez interna, faz com que as condições de refino nas aciarias sejam cada vez mais severas. Ao mesmo tempo, o aumento dos tempos de tratamento do aço, aliado às outras variáveis operacionais como quantidades e tipos de adições químicas, etc. fazem com que haja um aumento no tempo de contato entre o revestimento refratário das panelas de transporte de aço e escórias com conseqüente redução do desempenho (vida) de tais revestimentos refratários. Apesar dos esforços no intuito de redução de custos com redução de consumos de refratários, é cada vez maior a pressão sobre os custos de produção e de segurança operacional. Neste sentido, a construção de modelos de previsão de vida em função de tais variáveis é de extrema importância para a gestão de processos e contratos, estabilidade operacional e segurança. Além disso, os estudos de post-mortem podem contribuir no sentido de compreensão física e química de tais fenômenos e mecanismos de desgaste, contribuindo assim para a validação de tais modelos determinísticos. Neste estudo, buscou-se verificar quais variáveis operacionais influem no desempenho (vida) das panelas através de correlações estatísticas. O modelamento levou em consideração os dados de 6 meses de operação da aciaria de uma usina integrada com capacidade de 4,5 Mt/ano. O estudo post-mortem realizado em uma das panelas, após o final de sua campanha, mostrou-se eficiente na validação de tais correlações e no entendimento físico e químico dos possíveis fenômenos e mecanismos de desgaste. As análises mostraram que as variáveis que impactam a vida das panelas de aço são a temperatura de vazamento do aço, temperatura do aço na panela pós vazamento, quantidade de aço chapas grossas (CG) produzido, rota de tratamento dessulfurado, tempo de panela cheia, participação do forno panela no refino secundário, condições da panela, carga de aço na panela, adições de nefelina, escória sintética, fios de cálcio silício (CaSi) e ferro alumínio cálcio (FeAlCa), ligas de manganês e tempos de tratamento no refino secundário. O estudo de post-mortem de amostras de refratário da linha de escória extraída de uma das panelas revelou que o principal mecanismo de desgaste desta região é a corrosão química pela escória que é facilitada pelas adições de nefelina. / The increased demand for increasingly demanding steels, in terms of chemical composition and internal sanity, makes the conditions of refining in steelmaking plants are increasingly stringent and select. At the same time, increasing metallurgical treatment times, combined with the various other operating variables such as the quantities and types of chemical additions, etc. makes that there is an increase in contact time between the refractory coating of steel transport ladles and slag with a consequent reduction in performance (life) of such refractory linings. Despite efforts in order to reduce costs with a reduction of refractory consumption, it is increasing the pressure on the costs of production and operational safety. In this sense, the construction of life prediction models according to such variables is extremely important for cost reduction, process management and procurement, operational stability and safety. Moreover, post-mortem studies can contribute towards chemical and physical understanding of such phenomena and wear mechanisms, thus contributing to the validation of such deterministic models. In this study, we sought to determine which operating variables really influence the performance (life) of the ladles through statistics correlations. The modeling took into account data from 6 months of operation of an integrated steelmaking plant with capacity of 4.5 Mt / year. The study post-mortem conducted on some ladles, after the end of their campaigns, was effective in the validation of such correlations and in the physical and chemical understanding of possible phenomena and wear mechanisms. The analysis showed that the variables that impact in the life of steel\'s ladles are the steel taping temperature, the steel taping temperature in the ladle after taping, amount of produced plate mill (CG) steel, desulfurized treatment route, ladle full time, participation of the ladle furnace in the secondary refining, ladle conditions, steel load in the ladle, nepheline additions, synthetic slag, calcium silicon (CaSi) and iron aluminium calcium (FeAlCa) wires, manganese alloys and treatment times in the secondary refining. The post-mortem study of slagline\'s refractory samples extracted from ladles in operation revealed that the main wear mechanism in this region is the chemical corrosion by slag and is facilitated by additions of nepheline.

This diploma thesis deals with the influence of graded deformation of 8Cr3MoV steel rolling mills on the structure and mechanical properties. The theoretical part of this thesis describes general requirements for rolling mills, commonly used material, and the making of hot rolling mill rolls with emphasis on 8Cr3MoV steel. The second part is a report on experimental material and used methods. Then the results are presented. The influence of distance from the longitudinal axis of ingot and graded deformation on the forged shaft on the structure and mechanical properties are discussed at the end of this thesis, as well as a comparison of structure and mechanical properties of ingot and forged shaft.