Otimização da Injeção de gás inerte no Convertedor MRP-L

• Ano de defesa: 2005
• Autor(a) principal: Joao Domingos Guimaraes de Athayde Junior
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Gás; inerte; MRP-L; Engenharia metalúrgica; Engenharia de minas; Aço Metalurgia; Metalurgia extrativa
• Link de acesso: http://hdl.handle.net/1843/BUOS-8DJE2Q

This paper shows the metallurgical benefits gained by producing grain oriented silicon steel (GO) and non oriented grain silicon steel (NOG) in Acesitas converter MRP-L Metal Refining Process by Lance. The MRP-L, which replaced converter LD in 2001, features a combined blowing system in which oxygen is blown from the top by a lance and an inert gas is blown from the bottom through plugs. Whereas LD had only the oxygen top blowing system. The focus of this paper is a better understanding of the effects of the inert gas rate of flow (Nm3/min) injected from the bottom of the converter during production of GO andNOG steel in the MRP-L, aiming at optimizing this feature. Regarding NOG, a mathematical equation was created relating the bath oxidation level to the variables: endpoint carbon, time and inert gas rate of flow in the last phase of oxygen blowing. This equation was made by multiple linear regression, using the Excell tool Regression and the Minitab statistical analysis tool. In addition to the endpoint carbon percentage the equation showed the influence of time and rate of flow of the inert gas injected through the plugs. The relation of oxygen dissolved in the steel and endpoint carbon to the total iron percentage (FeT) in the slag is also shown. For the NOG, the percentage of oxygen in balance with CO gas and the percentage of FeO in the slag was calculated, in order to know these curves and compare them to the experimental curve of oxygen dissolved in the NGO steel in balance with the endpoint carbon. Regarding GO, the effect of the variation of the inert gas rate of flow through the plugs in the percentage of manganese and phosphor was evaluated during re-blowing and post-stirring, since residues of these elements greatly affect magnetic properties in this steel. The volume of oxygen during re-blowing and the variables: inert gas rate of flow, aimed carbon percentage in the ladle, endpoint carbon and temperature at the end of blowing were correlated in a mathematical equation. As was done for NOG, the equation for GO, was made by multiple linear regression, using the same Excell analysis tool. The equation allowed a better standardization of the volume of oxygen used during re-blowing, helping to reduce the level of oxidation during GO processing. For the GO, the percentage of oxygen in balance with the CO gas was calculated, in order to know these curves and compare them to the experimental curve of oxygen dissolved in this steel in balance with the endpoint carbon. To conclude, improvement of results are shown for the years 2005 (Jan to Mar) and 2004, compared to the year 2003, which is before the experiments proposed by this paper were made.