REDUÇÃO CARBOTÉRMICA DE ALUMINA EM PRESENÇA DE ESTANHO COMO SOLVENTE
CARBOTHERMAL REDUCTION OF ALUMINA IN THE PRESENCE OF LIQUID TIN
Mourão, Marcelo Breda; Takano, Cyro; Ferreira Neto, João Batista
http://dx.doi.org/10.4322/tmm.2011.037
Tecnol. Metal. Mater. Min., vol.8, n4, p.237-242, 2011
Resumo
A redução carbotérmica da alumina apresenta um rendimento energético potencialmente superior ao do processo eletrolítico de obtenção de alumínio primário. Além disto, questões ambientais, grande área da instalação e de custos de capital fazem com que a busca por um processo carbotérmico viável continue, apesar das dificuldades que tentativas anteriores encontraram. Este trabalho estuda o emprego de estanho como solvente para coletar o alumínio gerado como produto da reação, de modo que a atividade do alumínio seja reduzida, evitando-se a formação de oxicarbetos de alumínio. Termodinâmica computacional é usada na análise teórica. Foram realizados experimentos entre 1.750°C e 2.000°C, em equipamento montado especialmente para essa finalidade, utilizando pressões reduzidas de 0,7 bar a 0,1 bar, bem como experimentos à pressão atmosférica. O produto obtido foi caracterizado pelas técnicas de microscopia óptica e de microscopia eletrônica, e análise por EDS.
Palavras-chave
Alumina, Redução carbotérmica, Solventes, Estanho
Abstract
Carbothermic reduction of alumina presents potential for higher energy yield as compared to that of the electrolytic process for primary aluminum production. Besides this, environmental questions, large area of the facilities, and high capital costs justify the search for a viable carbothermic process in spite of the enormous difficulties which previous attempts have found. The present work presents a thermodynamic analysis of the carbothermic reduction of alumina, including the use of a metallic solvent. Experiments were performed between 1750°C and 2050°C, in a special equipment, under pressures of 0.7 bar to 0.1 bar, as well as experiments at atmospheric pressure. The products obtained were characterized by electronic microscopy, EDS and X-ray fluorescence techniques. It has been shown that the presence of the metallic solvent allows the use of lower temperatures, avoiding the formation of aluminum oxicarbides.
Keywords
Alumina, Carbothermic reduction, Solvent, Tin
Referências
1 RICHARDS, N. E. Evolution of carbothermic reduction of alumina. In: ELLIOTT SYMPOSIUM ON CHEMICAL
PROCESS METTALLURGY, 1990, Cambridge. Proceedings… Warrendale, Pa: TMS, 1990. p. 509-17
2 SAAVEDRA, A. F.; KIBBY, R. M. Investigating the viability of carbothermic alumina reduction. Journal of Metals, v. 40, n. 11, p. 32-6, Nov. 1988.
3 QIU, C., METSELAAR, R. Thermodynamic evaluation of the Al2O3-Al4C3 system and stability of Al-oxycarbides. Zeitschrift fur Metallkunde, v. 86, n. 3, p. 198-205, Mar. 1995.
4 DEWING, E. W. The thermochemistry of aluminum smelting. In: SAVARD /LEE INTERNATIONAL SYMPOSIUM ON BATH SMELTING, 1992, Montreal. Proceedings… Warrendale, PA: TMS, 1992. p. 341-51.
5 GRJOTHEIM, K.; WELCH, B. Technological developments for aluminum smelting as the industry enters the 21st century. JOM, v. 41, n. 11, p. 12-6, Nov. 1989.
6 HOWELL, W.; ECKERT, C. A.; ANDERSON, R. N. Carbothermic reduction using liquid metal solvents. Journal of Metals, v. 40, n. 7, p. 21-3, July 1988.
7 FRANK, R. A.; FINN, C. W.; ELLIOTT, J. F. Physical chemistry of the carbothermic reduction of alumina in the presence of a metallic solvent: Part II. Metalurgical and Materials Transactions B, v. 20, n. 2, p. 161-73, 1989. http://dx.doi.org/10.1007/BF02825597
2 SAAVEDRA, A. F.; KIBBY, R. M. Investigating the viability of carbothermic alumina reduction. Journal of Metals, v. 40, n. 11, p. 32-6, Nov. 1988.
3 QIU, C., METSELAAR, R. Thermodynamic evaluation of the Al2O3-Al4C3 system and stability of Al-oxycarbides. Zeitschrift fur Metallkunde, v. 86, n. 3, p. 198-205, Mar. 1995.
4 DEWING, E. W. The thermochemistry of aluminum smelting. In: SAVARD /LEE INTERNATIONAL SYMPOSIUM ON BATH SMELTING, 1992, Montreal. Proceedings… Warrendale, PA: TMS, 1992. p. 341-51.
5 GRJOTHEIM, K.; WELCH, B. Technological developments for aluminum smelting as the industry enters the 21st century. JOM, v. 41, n. 11, p. 12-6, Nov. 1989.
6 HOWELL, W.; ECKERT, C. A.; ANDERSON, R. N. Carbothermic reduction using liquid metal solvents. Journal of Metals, v. 40, n. 7, p. 21-3, July 1988.
7 FRANK, R. A.; FINN, C. W.; ELLIOTT, J. F. Physical chemistry of the carbothermic reduction of alumina in the presence of a metallic solvent: Part II. Metalurgical and Materials Transactions B, v. 20, n. 2, p. 161-73, 1989. http://dx.doi.org/10.1007/BF02825597
Facebook
Google+
Twitter
LinkedIn
Mendeley
StumbleUpon
CiteULike
Reddit
Email