The study of aluminum loss and consequent phase transformation in heat-treated acid-leached kaolin
- Malaysian Nuclear Agency (Nuclear Malaysia) Bangi, Selangor (Malaysia)
This study investigates the effect of Al leaching during Fe removal from kaolin to mullite. Heat-treated kaolin was obtained by heating natural kaolin at 400, 500, 600, 700, 800 and 900 deg. C. The heat-treated kaolin was then leached at 100 deg. C with 4 M, 3 M, 2 M, 1 M, 0.2 M solution of H{sub 2}SO{sub 4} and 0.2 M solution of oxalic acid. The dried samples were sintered to 1300 deg. C for 4 h at a heating rate of 10 deg. C min{sup -1}. X-ray diffractometry and differential thermal analysis were used to study the phase transformation of kaolin to mullite. It was found that 700 deg. C is the optimum preheat-treatment temperature to leach out Fe and also Al for both types of the acids used. The majority of the 4 M sulfuric acid-treated kaolins formed the cristobalite phase when sintered. On the other hand, 1 M, 0.2 M sulfuric acid and 0.2 M oxalic acid leached heat-treated kaolin formed mullite and quartz phase after sintering. - Research Highlights: {yields} Preheat-treatment of kaolin improves the leachability of unwanted iron. {yields} The optimum preheat-treatment temperature is 700 deg. C. {yields} Sintered 4 M sulfuric acid-treated kaolin majorly formed the cristobalite phase. {yields} Sintered 0.2 M oxalic acid-treated kaolin formed lesser amorphous silicate phase.
- OSTI ID:
- 22063678
- Journal Information:
- Materials Characterization, Vol. 62, Issue 4; Other Information: Copyright (c) 2011 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
- Country of Publication:
- United States
- Language:
- English
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