Please use this identifier to cite or link to this item: http://hdl.handle.net/1843/MAPO-77KNK6
Type: Dissertação de Mestrado
Title: Influência da deformação na laminação de encruamento nas propriedades mecânicas do aço acalmado ao alumínio refosforado, galvanizado a quente classe 220mpa de limite de escoamento
Authors: Carlos Augusto Carvalhido
First Advisor: Berenice Mendonca Gonzalez
First Co-advisor: Gláucio Bórtoli da Cruz Rabelo
First Referee: Dagoberto Brandao Santos
Second Referee: Odair Jose dos Santos
Third Referee: Glaucio Bortoli da Cruz Rabelo
Abstract: A contínua busca da melhoria da competitividade do aço frente aos sucedâneos tem levado ao desenvolvimento de aços mais resistentes, permitindo atender a três das principais demandas do setor automotivo: redução de peso, economia de combustível e aumento da segurança do usuário. Outra grande preocupação das montadoras e das usinas siderúrgicas é no aumento da resistência à corrosão dos aços, resultando no aumento constante do consumo de aços galvanizados.Este trabalho estudou a influência da deformação na laminação de encruamento nas propriedades mecânicas do aço acalmado alumínio, refosforado, galvanizado a quente, concentrando em aços com limite de escoamento mínimo de 220MPa. De maneira geral, observou-se maior resistência ao retorno do escoamento descontínuo e do aumento da deformação no patamar de escoamento, em materiais com maior graude deformação aplicado no laminador de encruamento, devido a maior densidade de deslocações geradas nestes materiais. Destaca-se também que o projeto utilizando grau de deformação na laminação de encruamento igual a 2,3% foi o mais adequado para a fabricação do aço estudado.
Abstract: Votorantim Metais Zinco, a fully Brazilian company, belonging to the Votorantim group, is the only producer of zinc and lead in the country. The industrial operations are located in the state of Minas Gerais, divided in two mining enterprises, in Vazante and Paracatu, and two metallurgical plants, in Três Marias and Juiz de Fora. The ore from the Paracatu deposit contains lead and zinc sulphides, galena and sphalerite, respectively. The ore is extracted from an underground mine and sent to the concentrator to be processed in a sequence that involves crushing, grinding, lead flotation, zinc flotation and filtration. This investigation was performed with samples from the Paracatu deposit aiming at studying the influence of the dispersion of the particles in the pulp on lead and zinc flotation. Samples of ore and also of the minerals sphalerite, galena, pyrite, and dolomite were selected for the experiments. Nine types of dispersing agents and six combinations among them were employed. A set of three dispersing agents was selected for the flotation of lead and another set of three was chosen for zinc flotation. The criteria for the selection of reagents were: high dispersion degree for galena and low for the other species, high dispersion degree for sphalerite and low for the other species, low dispersion degree for pyrite and high for the other species and high dispersion degree for all species. Lead flotation experiments were performed under three conditions aiming at verifying the influence of the dispersing agent, of the pH, and of sodium carbonate. The zinc flotation test was carried out at pH = 10.5 modulated with lime. The use of dispersing agents in lead flotation did not improve the overall efficiency of the circuit for, despite improving the lead metallurgical recovery, they increase significantly the zinc losses in the lead concentrate. Sodium carbonate presented a low dispersion degree and did not affect the lead flotation results when compared with those achieved at natural pH and at pH = 9.8 modulated with lime. Two dispersing agents were particularly effective in zinc flotation: dispersant 3223 sodium polyacrylate and sodium hexametaphosphate. Both reagents significantly enhanced zinc recovery without impairing the quality of the concentrate.
Subject: Engenharia metalúrgica
Metalurgia física
Aço Indústria
Laminação (Metalurgia)
Aço galvanizado
language: Português
Publisher: Universidade Federal de Minas Gerais
Publisher Initials: UFMG
Rights: Acesso Aberto
URI: http://hdl.handle.net/1843/MAPO-77KNK6
Issue Date: 23-Mar-2007
Appears in Collections:Dissertações de Mestrado

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