Antonio Cezar Faria Vilela

Numerical model of electromagnetic stirring for continuous casting billets

This paper introduces a numerical model of an electromagnetic rotary stirrer based on the finite-element model. Such stirrers are used to improve the quality of continuously cast steel, particularly billets and blooms. The method determines the magnetic flux density profile and compares it to experimental measurements. In addition, it calculates the Lorentz force field as a function of the stirrer position, the current applied, and the frequency. The stirrer position at the end of the mold affects the profile symmetry of the force, creating a z component of the force. With this model, it will be possible to simulate the fluid dynamics effects in the molten steel.

EAFD GENERATION – TERMODINAMIC ANALISYS OF Fe-Zn-O-Cl-H-C SYSTEM

The steel production in mini mills generates several process residues, among them there is the electric arc furnace dust (EAFD). This residue has as main elements Fe, O, and Zn, being classified as hazardous by the presence of Pb and Cd. Thermodynamic studies related to the formation of mineral species containing Fe, O and Zn elements were carried on due to the influence of these compounds in hydrometallurgical EAFD recycling processes. In recent years, a rise in the chlorine content of this residue was observed, mainly motivated by the increased use of scrap with polymeric impurities containing this element. In this work, based on computational thermodynamics tool FactSage, a general overview of gaseous and minerals species (found in EAFD) formed by Fe, Zn, O, Cl, H and C is shown – representing the organic origin of chlorine. For this study, the PVC polymer was used as the chlorine carrier substance which contaminates the EAF load.

INFLUÊNCIA DA PROPORÇÃO ENTRE AS VAZÕES DE OXIGÊNIO E GÁS NATURAL DO SISTEMA DE INJEÇÃO DE UM FORNO ELÉTRICO A ARCO NO CONSUMO DE ENERGIA TOTAL

In electric steelmaking, consumption of inputs plays an important role on the final billet cost, with particular emphasis to the energy consumption in the electric arc furnace, which can represent up to 30% of the operational cost in a melt shop. To quantify the contribution of different types of energy in EAF, it is used the performance indicator of total energy consumption, which associates equivalency factors for each type of energy, so that their measurement unit can be transformed to the base unit kWh/t. In this work, a test was conducted on a design of experiments format, varying the flow of natural gas and/or oxygen in a burner mode and in three lance modes, in order to modify their O2/GN ratio and evaluate the impact in total energy consumption.

ESTUDO DA PARTIÇÃO DO FÓSFORO DE ESCÓRIAS DE UM FORNO ELÉTRICO A ARCO ATRAVÉS DA TERMODINÂMICA COMPUTACIONAL

Resumo O fósforo é um elemento crítico para a qualidade dos aços, tornando a redução dos teores desse elemento uma exigência para a indústria siderúrgica. Uma forma de se medir a eficiência da desfosforação é através do coeficiente de partição do fósforo (Lp=%P(escória)/%P(aço)). O objetivo principal deste trabalho é avaliar escórias de um forno elétrico a arco através da comparação entre o Lp real com o Lp calculado por simulação termodinâmica, avaliando, também, o comportamento da partição de fósforo com relação à composição química. A partir de dados de composição química de amostras de escória e aço de uma usina siderúrgica, foram feitas simulações termodinâmicas utilizando o software FactSage. Com base nesses resultados, concluiu-se que o cálculo computacional através do software descreve bem o comportamento termodinâmico, mas tende a superestimar o Lp, provavelmente por questões cinéticas e/ou de transferência de massa e calor. Palavras-chave: Desfosforação; Partição de fósforo; Forno elétrico a arco; Termodinâmica computacional.

Caracterização e estudo termodinâmico de inclusões do aço SAE 8620 produzido via Aciaria Elétrica

The concept of quality is strongly linked to the steel micro-inclusionary cleanness. The aims of the correct refining practices are: 1) to adequate the non-metallic inclusions amount to acceptable values; and 2) to guarantee that the remaining inclusions will not be detrimental to the mechanical properties of steels. To reach such aims, the present work will evaluate the non-metallic inclusions analysis during steel making via EAF process. The characterization of inclusions consisted in the sampling of steel during the SAE 8620 refining. This steel is used in the production of automotive components industry. The characterization of steel inclusions consisted in analyzing 1) area occupied by inclusions and their size and; 2) chemical composition. The results were analyzed via ternary and pseudo-ternary phase diagrams. Some correlations between inclusion composition and steel making process were also done. The inclusions appear mainly as Si/Mn oxides in the beginning of the ladle furnace processing, and as Ca-Al oxides in the beginning of the continuous casting. The inclusions medium size was determined in the range of 4 to 10Pm. It was also observed a gradual decreasing of the occupied area by inclusions during the process, which is an important aim of the refining practices. A thermodynamic study was carried out were the results of inclusion analysis was compared with FactSage simulations and the results are compatible. The results of this work shown that the application of different techniques becomes possible the study and development of high quality steels. Key words: SAE 8620 steel, characterization, inclusions, FactSage.