ESTUDO CINÉTICOS DA REDUÇÃO DE PELOTAS DE POEIRA DE ACIARIA LD POR HIDROGÊNIO
KINETIC STUDY OF REDUCTION OF BASIC OXYGEN FURNCE DUST PELLETS BY HYDROGEN
Junca, Eduardo; Restivo, Thomaz Augusto Guisard; Espinosa, Denise Crocce Romano; Tenório, Jorge Alberto S.
http://dx.doi.org/10.4322/2176-1523.0788
Tecnol. Metal. Mater. Min., vol.12, n1, p.12-19, 2015
Resumo
A geração de poeira de aciaria LD é um dos problemas encontrados por empresas do setor siderúrgico. Desta forma, torna-se importante o desenvolvimento de estudos que possam viabilizar, ou pelo menos indicar um caminho para a reutilização deste resíduo. A técnica de redução direta pode ser uma alternativa, uma vez que, produtos ricos em ferro metálicos são obtidos. Assim, este trabalho tem por objetivo estudar a cinética de redução de pelotas feitas com poeira de aciaria LD através de uma mistura contendo hidrogênio e argônio, obtendo assim os mecanismos que estão envolvidos na redução das pelotas e a energia de ativação aparente envolvida em cada etapa. Aplicou-se a técnica conhecida como Forced Stepwise Isothermal Analysis na investigação cinética entre as temperaturas de 500°C a 1.100°C. Os resultados mostraram que a reação de redução ocorreu em três etapas. Na primeira etapa, o mecanismo controlador foi por nucleação com uma energia de ativação de 24 kJ/mol. Na segunda e terceira etapa, o mecanismo controlar foi por difusão, porém, na segunda etapa, a energia de ativação aparente obtida foi de 54,9kJ/mol enquanto que na terceira etapa foi de 80,7 kJ/mol.
Palavras-chave
Cinética química, Poeira de aciaria LD, Redução direta.
Abstract
The generation of basic oxygen furnace dust is a problem that companies found in the steel industry. In this way, studies are important to obtain, or at least indicate a way to recycle this waste. The direct reduction can be an alternative, once this method produces rich in iron. Thus, the goal of this paper is study the kinetic of reduction of basic oxygen furnace dust pellet using a mixture containing hydrogen and argon. Thereby, the mechanism and apparent activation energy that involve the reduction can be found out. The kinetic analysis was carried out applying the Forced Stepwise Isothermal Analysis method. The temperatures used in the test were between 500°C to 1,100°C. The results showed that reduction occurred in three steps. In the first step, nucleation was the control mechanism. It was found an apparent activation energy about 24kJ/mol in this step. In the second and third stage, the control mechanism was diffusion. In the second step, the apparent activation energy was 54.9 kJ/mol, while in the third step the apparent activation energy was 80.7 kJ/mol.
Keywords
Chemical kinetics, Basic oxygen furnace dust, Direct reduction.
Referências
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5. Scheele JV, Johansson M. XYFINES a new technology for in-plant recycling of dust and sludge in metal production industries, recycling and waste treatment in mineral and metal processing. Technical and Economic Aspects. 2002;1:109-118.
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10. Sørensen OT. Quasi-isothermal methods in thermal analysis. Thermochimica Acta. 1981;50(1-3):163-175. http://dx.doi.org/10.1016/0040-6031(81)85052-6.
11. Nigel JC, Andrew KG. Decomposition Reactions of Solids (An Experiment In Reviewing). Thermochimica Acta. 1984;79:323-370. http://dx.doi.org/10.1016/0040-6031(84)87118-X.
12. Sorensen OT. Thermogavimetric and dilatometric studies using stepwise isothermal analysis and related techniques. Journal of Thermal Analysis. 1992;38(1-2):213-228. http://dx.doi.org/10.1007/BF02109120.
13. Roduit B, Maciejewski M, Baiker A. Influence of experimental conditions on the kinetic parameters of gas-solid reactions -parametric sensitivity of thermal analysis. Thermochimica Acta. 1996;282-283:101-119. http://dx.doi.org/10.1016/0040-6031(96)02882-1.
14. Piotrowski K, Wiltowskim T, Mondal K, Stonawski L, Szymanski T, Dasgupta D. Simultaneous influence of gas mixture composition and process temperature on Fe2O3 - FeO reduction kinetics – neural. Brazilian Journal of Chemical Engineering Network Modeling. 2005;22:419-432.
15. Jung SS, Lee JS. In-Situ Kinetic Study of Hydrogen Reduction of Fe2O3 for the Production of Fe Nanopowder. Materials Transactions. 2009;50(9):2270-2276. http://dx.doi.org/10.2320/matertrans.MRA2008472.
16. Restivo TAG. Redução carbotérmica de óxidos de urânio assistida por banho solvente [tese de doutorado]. São Paulo: Escola Politécnica, Universidade de São Paulo; 2003.
17. Chen F, Sorensen OT, Meng G, Peng D. Thermal decomposition of BaC2O4.0,5H2O studied by stepwise isothermal analysis and non-isothermal thermogravimetry. Journal of Thermal Analysis. 1998;53(2):397-410. http://dx.doi.org/10.1023/A:1010124905090.
18. Maqueda LAP, Ortega A, Criado JM. The use of master plots for discriminating the kinetic model of solid state reactions from a single constant-rate thermal analysis (CRTA) experiment. Thermochimica Acta. 1996;277:165-173. http://dx.doi.org/10.1016/0040-6031(95)02746-7.
19. Lin Q, Liu R, Chen N. Kinetics of Direct Reduction of Chrome Iron Ore. Journal of Thermal Analysis and Calorimetry. 1999;58(2):317-322. http://dx.doi.org/10.1023/A:1010190802394.
20. Rao YK. Mechanism and the intrinsic rate of reduction of metallic oxides. Metallurgical Transactions. B, Process Metallurgy. 1979;10(2):243-255. http://dx.doi.org/10.1007/BF02652469.
21. Themelis NJ, Gauvin WH. Mechanism of reduction of iron oxides. Canadian Mining and Metallurgical Bulletin. 1962;55:444-456.
22. Hayes PC. The kinetics of formation of H2O and CO2 during iron oxide reduction. Metallurgical Transactions. B, Process Metallurgy. 1979;10(2):211-217. http://dx.doi.org/10.1007/BF02652465.
23. El-Rahaiby SK, Rao YK. The kinetics of reduction of iron oxides at moderate temperatures. Metallurgical Transactions. B, Process Metallurgy. 1979;10(2):257-269. http://dx.doi.org/10.1007/BF02652470.
24. Khawam A, Flanagan DR. Solid-state kinetic models: basics and mathematical fundamentals. The Journal of Physical Chemistry B. 2006;110(35):17315-17328. http://dx.doi.org/10.1021/jp062746a. PMid:16942065
25. Pineau A, Kanari N, Gaballah I. Kinetics of reduction of iron oxides by H2 Part II. Low temperature reduction of magnetite. Thermochimica Acta. 2007;456(2):75-88. http://dx.doi.org/10.1016/j.tca.2007.01.014.
26. Weiss B, Sturn J, Voglsam S, Strobl S, Mali H, Winter F, et al. Structural and morphological changes during reduction of hematite to magnetite and wustite in hydrogen rich reduction gases under fluidised bed conditions. Ironmaking & Steelmaking. 2011;38(1):65-73. http://dx.doi.org/10.1179/030192310X12700328926065.
27. Lin HY, Chen YW, Li C. The mechanism of reduction of iron oxide by hydrogen. Thermochimica Acta. 2003;400(1-2):61-67. http://dx.doi.org/10.1016/S0040-6031(02)00478-1.
28. Szekely J, Evans JW, Sohn HY. Gas-solid reaction. New York: Academic Press; 1976. The elements of gas-solid reaction systems involving sigle particles; p. 8-64.
2. Kelebek S, Yörük S, Davis B. Characterization of basic oxygen furnace dust and zinc removal by acid leaching. Minerals Engineering. 2004;17(2):285-291. http://dx.doi.org/10.1016/j.mineng.2003.10.030.
3. Evestedt M, Medvedev A. Model-based slopping warning in the LD steel converter process. Journal of Process Control. 2009;19(6):1000-1010. http://dx.doi.org/10.1016/j.jprocont.2009.01.002.
4. Hay SM, Rankin WJ. Recovery of iron and zinc from blast furnace and basic oxygen furnace dusts: A thermodynamic evaluation. Minerals Engineering. 1994;7(8):985-1001. http://dx.doi.org/10.1016/0892-6875(94)90028-0.
5. Scheele JV, Johansson M. XYFINES a new technology for in-plant recycling of dust and sludge in metal production industries, recycling and waste treatment in mineral and metal processing. Technical and Economic Aspects. 2002;1:109-118.
6. Szekely J, Evans JW, Sohn HY. Gas-solid reaction. New York: Academic Press; 1976. Reaction of porous solids; p. 108-175.
7. Bessières J, Bessières A, Heizmann JJ. Iron oxide reduction kinetics by hydrogen. International Journal of Hydrogen Energy. 1980;5(6):585-595. http://dx.doi.org/10.1016/0360-3199(80)90037-3.
8. Pineau A, Kanari N, Gaballah I. Kinetics of reduction of iron oxides by H2 Part I: Low temperature reduction of hematite. Thermochimica Acta. 2006;447(1):89-100. http://dx.doi.org/10.1016/j.tca.2005.10.004.
9. Junca E, Oliveira JR, Espinosa DCR, Tenório JAS. Characterization of dust generated in the BOF converter. In: The Minerals, Metals & Materials Society. Proceedings og the 141st The Minerals, Metals & Materials Society – TMS; 2012; Orlando, Estados Unidos da America. TMS; 2012. p. 221-227.
10. Sørensen OT. Quasi-isothermal methods in thermal analysis. Thermochimica Acta. 1981;50(1-3):163-175. http://dx.doi.org/10.1016/0040-6031(81)85052-6.
11. Nigel JC, Andrew KG. Decomposition Reactions of Solids (An Experiment In Reviewing). Thermochimica Acta. 1984;79:323-370. http://dx.doi.org/10.1016/0040-6031(84)87118-X.
12. Sorensen OT. Thermogavimetric and dilatometric studies using stepwise isothermal analysis and related techniques. Journal of Thermal Analysis. 1992;38(1-2):213-228. http://dx.doi.org/10.1007/BF02109120.
13. Roduit B, Maciejewski M, Baiker A. Influence of experimental conditions on the kinetic parameters of gas-solid reactions -parametric sensitivity of thermal analysis. Thermochimica Acta. 1996;282-283:101-119. http://dx.doi.org/10.1016/0040-6031(96)02882-1.
14. Piotrowski K, Wiltowskim T, Mondal K, Stonawski L, Szymanski T, Dasgupta D. Simultaneous influence of gas mixture composition and process temperature on Fe2O3 - FeO reduction kinetics – neural. Brazilian Journal of Chemical Engineering Network Modeling. 2005;22:419-432.
15. Jung SS, Lee JS. In-Situ Kinetic Study of Hydrogen Reduction of Fe2O3 for the Production of Fe Nanopowder. Materials Transactions. 2009;50(9):2270-2276. http://dx.doi.org/10.2320/matertrans.MRA2008472.
16. Restivo TAG. Redução carbotérmica de óxidos de urânio assistida por banho solvente [tese de doutorado]. São Paulo: Escola Politécnica, Universidade de São Paulo; 2003.
17. Chen F, Sorensen OT, Meng G, Peng D. Thermal decomposition of BaC2O4.0,5H2O studied by stepwise isothermal analysis and non-isothermal thermogravimetry. Journal of Thermal Analysis. 1998;53(2):397-410. http://dx.doi.org/10.1023/A:1010124905090.
18. Maqueda LAP, Ortega A, Criado JM. The use of master plots for discriminating the kinetic model of solid state reactions from a single constant-rate thermal analysis (CRTA) experiment. Thermochimica Acta. 1996;277:165-173. http://dx.doi.org/10.1016/0040-6031(95)02746-7.
19. Lin Q, Liu R, Chen N. Kinetics of Direct Reduction of Chrome Iron Ore. Journal of Thermal Analysis and Calorimetry. 1999;58(2):317-322. http://dx.doi.org/10.1023/A:1010190802394.
20. Rao YK. Mechanism and the intrinsic rate of reduction of metallic oxides. Metallurgical Transactions. B, Process Metallurgy. 1979;10(2):243-255. http://dx.doi.org/10.1007/BF02652469.
21. Themelis NJ, Gauvin WH. Mechanism of reduction of iron oxides. Canadian Mining and Metallurgical Bulletin. 1962;55:444-456.
22. Hayes PC. The kinetics of formation of H2O and CO2 during iron oxide reduction. Metallurgical Transactions. B, Process Metallurgy. 1979;10(2):211-217. http://dx.doi.org/10.1007/BF02652465.
23. El-Rahaiby SK, Rao YK. The kinetics of reduction of iron oxides at moderate temperatures. Metallurgical Transactions. B, Process Metallurgy. 1979;10(2):257-269. http://dx.doi.org/10.1007/BF02652470.
24. Khawam A, Flanagan DR. Solid-state kinetic models: basics and mathematical fundamentals. The Journal of Physical Chemistry B. 2006;110(35):17315-17328. http://dx.doi.org/10.1021/jp062746a. PMid:16942065
25. Pineau A, Kanari N, Gaballah I. Kinetics of reduction of iron oxides by H2 Part II. Low temperature reduction of magnetite. Thermochimica Acta. 2007;456(2):75-88. http://dx.doi.org/10.1016/j.tca.2007.01.014.
26. Weiss B, Sturn J, Voglsam S, Strobl S, Mali H, Winter F, et al. Structural and morphological changes during reduction of hematite to magnetite and wustite in hydrogen rich reduction gases under fluidised bed conditions. Ironmaking & Steelmaking. 2011;38(1):65-73. http://dx.doi.org/10.1179/030192310X12700328926065.
27. Lin HY, Chen YW, Li C. The mechanism of reduction of iron oxide by hydrogen. Thermochimica Acta. 2003;400(1-2):61-67. http://dx.doi.org/10.1016/S0040-6031(02)00478-1.
28. Szekely J, Evans JW, Sohn HY. Gas-solid reaction. New York: Academic Press; 1976. The elements of gas-solid reaction systems involving sigle particles; p. 8-64.
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