ESTUDO DA FUSIBILIDADE DAS CINZAS DE CARVÕES EM FUNÇÃO DA COMPOSIÇÃO QUÍMICA E MINERALÓGICA
COAL-ASH FUSIBILITY ANS ITS RELATION TO CHEMICAL AND MINERALOGICAL COMPOSITION
Bagatini, Mauricio Covcevich; Ghiggi, Maria Luisa F.; Osório, Eduardo; Vilela, Antônio Cezar F.; Defendi, Guilherme
http://dx.doi.org/10.4322/tmm.00304009
Tecnol. Metal. Mater., vol.3, n4, p.52-58, 2007
Resumo
Considerando a intensa utilização do carvão no setor siderúrgico e energético, é indispensável o conhecimento mais aprofundado da matéria inorgânica desse insumo. Nesse trabalho busca-se relacionar as fases minerais contidas nas cinzas de carvão ao seu respectivo comportamento de fusibilidade. Foram selecionados para esse estudo três diferentes tipos de carvão. Inicialmente foi feita uma identificação da matéria mineral dos carvões através da DRX. As cinzas obtidas com a queima dos carvões foram caracterizadas através das técnicas de FRX e DRX. As propriedades reológicas das cinzas foram estudadas através de testes de fusibilidade. Como ferramenta auxiliar aos testes de fusibilidade também foi utilizado o MEV. Verificou-se a presença de diferentes fases cristalinas entre as amostras. Os ensaios de fusibilidade também evidenciaram o comportamento distinto entre as cinzas. Para os carvões em estudo, constatou-se que as fases ilita e quartzo tendem a baixar a temperatura de amolecimento. As fases ricas em alumínio tendem a elevar a temperatura de fusão das amostras, enquanto que a presença dos óxidos de K, Na, Ca e Mg nas fases formadas contribuem para a fluidez das cinzas.
Palavras-chave
Cinzas, Fusibilidade, Composição química, Composição mineralógica
Abstract
Due to the great use of coal in the ironmaking plants and powerstations, it is very important to have a deeper knowledge of inorganic matter of this raw material. This study aims to identify the mineral phases responsible for the fluidity behavior of the coal ashes. Three differents types of coal were selected for this study. At first an identification of the mineral matter of the coals was done through the XRD. The ashes from the coals combustion were characterized through XRF chemical analysis and XRD. The rheologic properties were studied by the ash fusion tests in oxidant atmosphere. As an auxiliary tool in the fusibility tests, SEM was also used. The presence of different crystaline phases among the samples via XRD was also observed. The fusibility tests showed the different behaviour of the ashes in their respective temperatures of softening and fusibility. Concerning the studied coals, the illite and quartz phases tend to decrease the softening temperature. The phases rich in aluminium tend to increase the fusion temperature of the samples, whereas the presence of K, Na, Ca e Mg oxides in the formed phases contribute to the ashes fusibility.
Keywords
Ash, Fusibility, Mineral composition, Chemical composition
References
1 BRYERS, R. W. Fireside slagging, fouling, and high-temperature corrosion of heat-transfer surface due to impurities in steam-raising fuels. Progress in Energy and Combustion Science, v. 22, n. 1, p. 29-120, 1996.
2 ICHIDA, M.; ORIMOTO, T.; TANAKA, T.; KOIZUMI, F. Behavior of pulverized coal ash and physical property of dripping slag under high pulverized coal injection operation. ISIJ International, v. 41, n. 4, p. 325-32, 2001.
3 KALKREUTH, W.; BORREGO, A.G.; ALVAREZ, A. D.; MENENDEZ, R.; OSÓRIO, E.; RIBAS, M; VILELA, A; CARDOZO ALVES, T.C. Exploring the possibilities of using Brazilian Bubbituminous coalsfor blast furnace pulverized fuel injection. Fuel, v. 84, n.6, p. 763-72, Apr. 2005.
4 VASSILEV, S. V.; KITANO, K, TAKEDA, S.; TSURUEB, T. Influence of mineral and chemical composition of coal ashes on their fusibility. Fuel Processing Technology, v. 45, n.1, p. 27-51, Oct.1995.
5 VARGAS S.; FRANDSEN, F. J.; DAM-JOHANSEN, K. Rheological properties of high-temperature melts of coal ashes and other silicates. Progress in Energy and Combustion Science, v. 27, n.3, p. 237-429, Mar. 2001.
6 VAN DYK. J. C.; BAXTER, L. L.; VAN HEERDEN, J. H. P.; COETZER, R.L.J. Chemical fractionation tests on South African coal sources to obtain species-specific information on ash fusion temperatures (AFT). Fuel, v. 84, n.14-5, p. 1768–1777, Sept. 2005.
7 GUPTA, S.K.; WALL, T.F.; CREELMAN, R.A.; GUPTA, R.P. Ash fusion temperatures and the transformations of coal ash particles to slag. Fuel Processing Technology, v. 56, n.1-2, p. 33–43, July 1998.
8 HUFFMAN, G. P.; HUGGINS, F. E.; DUNMYRE, G. R. Investigation of the high-temperature behavior of coal ash in reducing and oxidizing atmospheres. Monroeville: US Steel Corporation, 1980.
9 DEUTSCHES INSTITUT FÜR NOMUNG. DIN 51730: Testing of solid fuels - Determination of fusibility of fuel ash. Berlin, 200-?.
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