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Mullite Preparation from Kaolin Residue

2006; Trans Tech Publications; Volume: 530-531; Linguagem: Inglês

10.4028/www.scientific.net/msf.530-531.625

1662-9760

Maria Isabel Brasileiro, D.H.S. Oliveira, Hélio de Lucena Lira, Lisiane Navarro de Lima Santana, Gelmires de Araújo Neves, A.P. Novaes, J.Marcos Sasak,

Concrete and Cement Materials Research

In the process of kaolin improvement to types of residue are generated and dispose in the environment. The first residue, about 70%wt, generated from the washing of the kaolin and the second generated residue from the improvement in sieve 200 mesh (0.074mm), of the remaining of the washed kaolin 30%. These residues can present excellent qualities to be used as raw materials rich in kaolinite. Kaolinite when is submitted to heat give two stable phases: mullite and crystobalite. The properties of mullite, such as, low thermal expansion, low dielectric constant and high mechanical resistance, make this material as a good candidate to be applied in electronic products and in structural high temperature uses. In this work, compositions with residue from kaolin, alumina and ball-clay were studied to obtain mullite. The compositions were established starting from proportion between silica and alumina to obtain mullite (2SiO 2 .3Al 2 O 3 ). The samples were made by pressing processing with 27 MPa and sintering at temperatures of 1350 and 1500°C, with heating rate of 10°C/min. Through the results from chemical analysis of the formulated masses, it can be verified that the proportions of the oxides were close to the stoichiometric of the mullite and that the sintering, at studied temperatures, give the formation of mullite, and confirmed by the DRX analysis. The preliminary results showed that the compositions with low alumina content and submitted to a high temperatures, presented the best results.