Technology of dehydration and transformation of silicic acid
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Technology of dehydration and transformation of silicic acid Xiao-Cai He*, Gang Xie, Hui-Re Li, Rong-Xing Li, Da-Jin Yang, Qing-Xin Xu
Received: 23 July 2012 / Revised: 12 October 2012 / Accepted: 20 October 2012 / Published online: 20 August 2013 Ó The Author(s) 2013. This article is published with open access at Springerlink.com
Abstract The technology that silicic acid was pressurized under high temperature in order to dehydrate and transform was investigated in the paper. The effects, such as the ratio of liquid to solid, pressure, temperature, and reaction time on the dehydration rate and volume shrinkage rate, were researched. The experimental results show that the dehydration rate of silicic acid is up to 41.20 %, accompanying with the volume shrinkage rate of 40.37 % after silicic acid is pressurized under high temperature in the high-pressure kettle. The results of silicic acid tested by SEM indicate that the metasilicate acid molecules and water molecules are closely arranged, and there are almost no gaps before pressure reaction. There are many gaps accompanying with formatting lamellar structure after pressure reaction. The experimental results indicate the effect that silicic acid is dehydrated and transformation is obvious under high temperature and pressure. Keywords Silicic acid; Pressurized; Dehydration; Transformation
1 Introduction Silicic acid is important raw materials for high-purity quartz, light-guide fiber, metallurgical polycrystalline
X.-C. He*, G. Xie, R.-X. Li Faculty of Metallurgical and Energy Engineering, Kunming University of Science and Technology, Kunming 650051, China e-mail: [email protected] X.-C. He, G. Xie, H.-R. Li, D.-J. Yang, Q.-X. Xu Department of Metallurgical Researching, Kunming Metallurgy Research Institute, Kunming 650031, China
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silicon, and refractory materials [1–3]. On the one hand, silicic acid is used as catalyst or catalyst carrier in petroleum, chemical industry, synthetic fiber, synthetic rubber, and so on [4–6]. It is also a better kind of adsorbent, desiccant, or moisture proof agent [7–10]. On the other hand, silicic acid is also utilized as filling material or reinforcing material [11, 12]. More importantly, it is a kind of inorganic salt industrial products. But silicic acid has some obvious shorts, such as many pore structure and containing water of crystallization [13]. Silicic acid usually contains about 70 %–75 % water [14], which not only increases cost of transportation and raw materials but also limits the usage of silicic acid. Silicic acid was decomposed out from sodium silicate solution through carbonating process and acid pickling process, which usually had about 70 wt%–75 wt%, so the technology that silicic acid was pressurized under high temperature and pressure in order to dehydrate and transformation was investigated in the paper. Owing to the high temperature and pressure, some of the crystal water could be removed quickly and easily accompanied the destructing and recombining processes
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