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Bulletin of the Korean Chemical Society (BKCS)

ISSN 0253-2964(Print)
ISSN 1229-5949(Online)
Volume 33, Number 8
BKCSDE 33(8)
August 20, 2012 

 
Title
Study on the Kinetics and Mechanism of Grain Growth during the Thermal Decomposition of Magnesite
Author
Da-xue Fu, Nai-xiang Feng*, Yao-wu Wang
Keywords
Grain growth, Kinetics, CO2 adsorption, Highly reactive MgO, Magnesite
Abstract
The X-ray line broadening technique was used to calculate the grain size of MgO at 1023, 1123, 1223 K respectively either in CO2 or during the thermal decomposition of magnesites in air as well as in vacuum. By referring to the conventional grain growth equation, Dn = kt, the activation energy and pre-exponential factor for the process in air are gained as 125.8 kJ/mol and 1.56 × 108 nm4/s, respectively. Ranman spectroscopy was employed to study the surface structure of MgO obtained during calcination of magnesite, by which the mechanism of grain growth was analyzed and discussed. It is suggested that a kind of highly reactive MgO is produced during the thermal decomposition of magnesites, which is exactly the reason why the activation energy of the grain growth during the thermal decomposition of magnesite is lower than that of bulk diffusion or surface diffusion.
Page
2483 - 2488
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