Understanding the effects of the process parameters on the distribution behaviour of antimony between metal and slag in the iron blast furnace is critical to develop a universal method of controlling temper embrittlement in commercially pure low alloy steels.

As carbon dissolution rates have been determined for a few chars only, a systematic and comprehensive study was undertaken in this project on the dissolution behaviour of carbon from non-graphitic materials into liquid iron. In addition to measuring the kinetics of carbon dissolution from a number of coal chars into liquid iron as a function of parent coal and coal ash composition, the influence of chemical reactions between solute/solid carbon and ash oxides was also investigated. These studies were supplemented with investigations on one metallurgical coke for the sake of comparison. The wettability of coal chars and coke with liquid iron at 1550 degrees C was measured as a function of time. Being essentially non-wetting, only a marginal improvement in contact angles was observed with time. The accumulation of alumina at the interface was detected for all materials and was seen to increase with time in all cases. Calcium and sulphur also appeared to preferentially accumulate at the interface, concentrating at levels in excess of those expected from the ash composition alone. Despite the high levels of silica in the ash initially, very little silica was detected in the interfacial region, implying ongoing silica reduction reactions. A small amount of silicon was however detected in the iron droplets, indicating silica reduction with solute carbon. It was identified that the reduction reactions can also consume solute carbon in the liquid iron. As this is occurring simultaneously with carbon dissolution into liquid iron, the interdependency of silica reduction and carbon dissolution could potentially limit the observed carbon dissolution rate. A theoretical model was developed for estimating the interfacial contact area between chars and liquid iron. Wettability was found to have a very significant effect on the area of contact. A two-step behaviour was observed in the carbon dissolution of two chars and coke. Slow rates of carbon dissolution in stage II were attributed to very high levels of interfacial blockage by reaction products leading to much reduced areas of contact between carbonaceous material and liquid iron. The first order dissolution rate constants for four chars/coke and the observed trend in first order dissolution rate constants were calculated. These dissolution results compare well with the previously measured dissolution rate constants. The trends in dissolution can be adequately explained on the basis of carbon structure, silica reduction, sulphur concentration in the metal and ash impurities.

No description available.

Thesis (Ph.D.)--University of Wollongong, 2005. / Typescript. Includes bibliographical references: leaf 252-266.

Orientador: Vladimir Antonio Paulon / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-05T19:59:19Z (GMT). No. of bitstreams: 1 Massucato_CarlosJose_M.pdf: 776667 bytes, checksum: f202112f226f07e627ccbebfb07f5bed (MD5) Previous issue date: 2005 / Resumo: Este estudo teve como objetivo principal avaliar propriedades oriundas da adição de escória de alto-forno à carvão vegetal, do concreto no estado fresco e endurecido, produzido com cimentos que já utilizam em sua composição a escória de alto-forno. Com a determinação da quantidade de escória de alto-forno pelo método de dissolução seletiva, foi possível adicionar escória de alto-forno no concreto até os limites estabelecidos na especificação do cimento de alto-forno (CPIII) pela NBR 5735 (ABNT, 1991) e conhecer o efeito na resistência mecânica, módulo de elasticidade, abatimento, incorporação de ar, tempo de pega e exsudação, em traços de concreto sem adição e com adição de escória de alto-forno à carvão vegetal e à coque. As indústrias de cimento utilizam, em sua maioria, escórias provenientes dos altos-fornos à coque. Entretanto, o tratamento adequado nas escórias de alto-forno à carvão vegetal pode ampliar o consumo deste produto como adição mineral diretamente nas centrais de concreto, com a vantagem de ser uma fonte renovável de energia e eliminar este resíduo que se acumula nas usinas siderúrgicas. O estudo comprovou que, a utilização da escória de alto-forno à carvão vegetal como adição, não provoca alterações nas propriedades do concreto no estado fresco, em comparação com a escória de alto-forno à coque. A resistência à compressão com adição da escória de alto-forno à carvão vegetal aumentou em até 5% em idades superiores a 60 dias em comparação com o concreto sem adição de escória / Abstract: This study had the main purpose to evaluate properties of fresh and hardened concrete in with slag addition of blast furnace from charcoal in concrete produced with cements that already use in its composition the blast furnace slag. With the determination of the amount of slag of blast furnace by the selective method of dissolution, it was possible to add slag of blast furnace in concrete up to the limits established by NBR 5735 (ABNT, 1991) and to know the effect in concrete resistance, modulus of elasticity, slump test, air entrained concrete, setting of the cement and bleeding, in the mix proportions of concrete with and without slag addition of blast furnace from charcoal and coke. The cement industries use in its majority slag from coke deriving from blast furnace. However, the suitable treatment in slag of blast furnace from charcoal can extend the consumption of this product as mineral addition directly in the concrete plant, with the advantage of being a renewable source of energy and to eliminate this residue that accumulates in the siderurgical plants. The study proved that the use of the slag of blast furnace from charcoal as addition in concrete presented the same properties of fresh concrete compared with the slag of blast furnace with coke. The compressive strength increased in 5% at superior ages at 60th day in comparison without slag addition / Mestrado / Edificações / Mestre em Engenharia Civil

Orientador: Carlos Kenichi Suzuki / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-07-25T04:29:58Z (GMT). No. of bitstreams: 1 Mendes_Wanderley_M.pdf: 9018563 bytes, checksum: 6fc26478d4581cd787ef07e1923cfa7f (MD5) Previous issue date: 1999 / Resumo: A indústria siderúrgica é historicamente um setor que produz impactos ambientais inerentes ao seus processos de produção. Anualmente são gerados 135 milhões de toneladas de escórias para uma produção de 700 milhões de toneladas de aço. As novas regulamentações dos órgãos ambientais têm motivado a pesquisa em busca de novas aplicações destes resíduos. Atualmente, as escórias tem sua aplicação na indústria de cimento Portland e vidros, na pavimentação de estradas, revestimentos acústicos e térmicos, neutralizante de solos, mas há necessidade de novas aplicações das escórias devido ao montante gerado pelas usinas. Neste contexto, a caracterização física, química e de impactos ambientais das escórias se faz necessária, visando uma nova aplicação tecnólogica, tendo em vista que as suas propriedades físicas e químicas estão diretamente relacionadas as suas estruturas. Com o objetivo de determinar a composição química e determinação estrutural, métodos analíticos foram aplicados em escórias de alto forno (AF) e conversores LD (CLD) utilizando-se das técnicas de espectroscopia de fluorescência (FRX) e difração de raios-X (DRX). O presente trabalho foi desenvolvido em duas etapas: (1) a determinação e quantificação química das escórias por FRX; (2) caracterização estrutural das fases presentes e quantificação da fase mervinita cristalina Ca2Mg(SiO4h que se fez presente em todas as amostras analisadas de escórias de alto forno. Foram utilizadas duas metodologias nas escórias analisadas por FRX: métodos de parâmetros fundamentais (PF) e análise semi-quantitativa (SQ), onde as diferenças nas concentrações foram significativas, justificadas pela maior acuracidade nas medições realizadas pelo PF, haja visto uma maior interação númerica e utilização de curvas de sensitividade para a análise. Também verificamos a presença de impurezas que não foram detectadas no SQ e observadas no PF, tais como: P, N, V, Cr. Com os resultados obtidos na análise por DRX observamos os diferentes graus de cristalização/amorfo; a caracterização de fases presentes, mesmo quando se encontravam em baixas porcentagens nas amostras, além da quantificação da fase mervinita utilizando-se do método de padrão interno / Abstract: Steel plants are historicalIy associated with environrnental impacts because of their manufacture processoIn that process, there are generations of 135 million tons of slag from 700 million tons of steel produced. The new regulations of environrnental agencies have stimulated research of new uses for the generated wastes. Nowadays, slag is re-used in Portland cement plants, glass manufacture, paving highways, acoustic and thermal insulating, and soil neutralization. Despite those applications, the slag generation is large enough to demand new innovative technologies. In this context, it is necessary to accomplish physical and chemical characterization of slag to extend knowledge of its structure and properties. Analytical methods for chemical and structural determination of slag were applied in blast furnace slag (AL) and steel converter unit slag (CLD) by using X-ray Fluorescence Spectroscopy (FRX) and X-ray Diffraction (DRX). The present research was carried out in two stages: (1) determination of chemical elements presents in slag followed by quantitative analysis of these elements (by FRX); (2) structural characterization followed by quantitative determination of merwinite crystalline phase [CazMg(SiO4)z]present in alI analyzed samples. There were used two methods for FRX characterization of slag: Fundamental Parameter (PF) and Semi-Quantitative Analysis (SQ). Those methodologies were divergence in the results, maybe due to the higher accuracy with PF methodology that utilizes more interactions and sensibility curves in the optimization processoAIso in PF method, there were observed presence of impurities that were not detected in SQ method such as: P, Nb, V, Cr, Y. The DRX analysis showed several stages of crystalline/amorphous structures, determination of crystalline phases even in low concentration and quantification of merwinitic phase by using internal standard method in DRX analysis / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

In the zinc slag fuming process, zinc is extracted from lead blast furnace slag by reduction with a coal/air mixture injected into the slag through submerged tuyeres. The furnace is constructed of water-cooled jackets to contain the molten bath and freeze a protective slag layer. The slag layer greatly reduces vessel wear caused by the corrosive and violently agitated bath. However, the jackets are known to develop cracks in the working face panel that initiate on the slag face and propagate towards the water cavity. If the cracks reach the water cavity explosions may result should the molten slag come into contact with the water. In this study an analysis of heat transfer in the jacket has been carried out using in-plant measurements and mathematical modelling. The working face of a water jacket was instrumented with thermocouples and positioned in a fuming furnace at the Trail smelter of Cominco Ltd. Measurements revealed the presence of large thermal transients or temperature "spikes" in the panel approximately 20 cm above the tuyeres. The transients were observed during charging and tapping of the furnace and are likely associated with slag fall-off due to surface wave action and gas injection effects when the bath level is low. Temperatures at the mid-thickness were seen to rise by as much as 180 °C above the steady-state level. Under these conditions large compressive stresses are produced in the panel that are sufficient to cause yielding. Over time, the transients lead to low-cycle fatigue of the working face panel with crack formation initiating at pre-existing surface flaws. A mathematical modelling analysis of the transient freezing phenomena has been carried out using the finite element method. The results indicate that the temperature spikes are associated with the sudden removal of patches of slag and molten slag coming into direct contact with the jacket. The temperature spikes are large enough to generate compressive stresses that cause yielding of the material in the exposed area. In order to reduce the damage caused by the removal of the slag shell an increased number of anchoring studs should be used in critical areas and a higher water circulation velocity should be employed to increase the size of the frozen slag layer and its strength. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

No description available.

Orientadores: Ana Maria Frattini Fileti, Andre Pitasse da Cunha / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-06T08:56:35Z (GMT). No. of bitstreams: 1 Medeiros_FernandoTadeuPereirade_D.pdf: 2343033 bytes, checksum: 9407aef56d1977bfd109c78806bb29de (MD5) Previous issue date: 2006 / Resumo: Este trabalho descreve o desenvolvimento de um modelo capaz de prever as condições operacionais do processo de redução de minério de ferro em alto-forno a partir de características das matérias-primas e da composição da carga e do sopro, fornecendo aos operadores e engenheiros de processo, uma ferramenta de planejamento e de análise de desempenho da operação. A motivação para este trabalho deveu-se à constatação de que existe uma deficiência de modelos capazes de identificar cotidianamente os fatores críticos na operação dos altos-fornos siderúrgicos. Os modelos encontrados são excessivamente simples para preverem condições futuras de processo ou são demasiadamente complexos para o uso operacional diário ou no pJanejamento estratégico da produção. Os altos-fornos e os conversores de aço são as unidades centrais de uma usina siderúrgica integrada. O primeiro obtém o ferro primário a partir dos óxidos contidos nos minérios e o segundo refina e ajusta a composição química do metal produzindo o aço. O modelo desenvolvido e aplicado tem natureza híbrida, combinando algoritmos simuladores baseados em balanços de massa e energia com variável grau de desvio estequiométrico e térmico. O valor de cada indicador de desvio é previsto por uma rede neural cujas variáveis de entrada quantificam características das matérias-primas e condições de sopro e carga do alto-forno. A aplicação industrial do modelo comprovou sua capacidade de prever as condições do processo e sua aplicação resultou em aumento da produtividade média do processo e menor consumo específico de redutores, decorrentes da melhor efetividade das ações operacionais. Além disso, o modelo, associado a um módulo de balanço do setor primário da usina, vem sendo aplicado na simulação de alternativas de padrões operacionais, atividade fundamental para o planejamento estratégico do negócio / Abstract: This work describes the development of a model capable of evaluating and predicting iron ore reduction process in blast-furnaces based on raw materiais characteristics as well as burden and blast composition. It provides a planning and analysing toll to operators and process engineers. The motivation for this development resides on the lack of this kind of model in the ironmaking industry. The many models found are either toa simple and not capable of predicting raw materiais parameters effects on the furnace performance or toa complexo The latter are useful in technology potential identifications but not in the daily work or ordinary operation planning. Blast-furnaces and oxygen converters are the core units in a integrated steel works. The former one produces primary iron from oxides bared by iron ores and the latter one refines molten iron into steel, adjusting its chemical compositiono The developed and applied model is hybrid in nature, combining simulating algorithms based on mass and energy balances with variable lack of fitnesso The value of each lack-of-fitness index is estimated by a neural model in which the input quantify burden materiais characteristics as well as blow and charging conditions. The model has shown its predicting capacity during its industrial application, which lead to higher average productivity and lower specific fuel consumption are expected following better operation action and process planning efficiency. In addition, the model is now being associated to a plant mass balance module to asses alternative operation pattern simulation for the hole company which is a fundamental activity in strategic business planning / Doutorado / Sistemas de Processos Quimicos e Informatica / Doutor em Engenharia Química

The blast furnace process for the reduction of iron ore to pig iron faces problems such as emission of air pollutants, high investment cost and the current major problem of decreasing supplies of coke. Coke is used in large quantities to promote a combination of direct and indirect reduction within the furnace. Due to the lack of good coking coal within South Africa, and dwindling supplies worldwide, new iron-making processes, are being developed using coal and/or natural gas to replace coke as the reductant. The new processes allow efficient use of carbon, fed in the form of coal pellets (coalbased processes) or natural gas (gas-based processes), as the reducing agent. Presently, most coal-based processes Use an excess of coal, up to 500% stoichoimetric addition, and are run at temperatures up to ±1200°C, although reduction tends to proceed at ±850°C. This project developed a low temperature process using mixed pellets of fine waste iron oxide and fine domestic coal with a natural carbonaceous binder (a by-product from local pulping industry). Reduction tests performed on composite pellets in a tube furnace and thermobalance indicated, upon analysis by X-Ray Diffraction and Scanning Electron Microscope, that reduction occurred gradually at 900°C. Implementing induction heating of bulk pellets reduced heating times substantially. Induction heating also resulted in direct reduced iron [DRI] containing 75 - 80% metallic iron. Energy consumption based on coal usage amounted to 23.71 GJ/ton DRI, which compares with the calorific consumption of most coal-based processes, i.e. coal consumption range between 15 and 25 GJ/ton DRI. Energy consumed during induction heating amounted to 9.94 GJ/ton DRI, as electricity. This energy consumption value does not take into account the efficiency of the primary energy required to generate electricity. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.