Preparation of Xonotlite Nano-Fibres Using the Silica Source from Coal Fly Ash and Ca(OH)₂

Abstract:

Extracting aluminum oxide from high-alumina coal fly ash are significant to make up for the inadequacy of bauxite resource in China. How to comprehensively utilize silica components in coal fly ash is a key technical question in industrialization for extracting of alumina from coal fly ash. Desilication of coal fly ash (CFA) and preparation of xonotlite were studied using the silica-rich solution from the CFA as silica source and calcium oxide as calcium source respectively. The CFA is from a power plant at Shizuishan city in Ningxia, China. Xonotlite was successfully prepared by a series processes including predesilication, hydro-thermal synthesis. The experimental results indicated that SiO₂ in the coal fly ash changed into NaSiO₃ after the coal fly ash was treated by desilication using NaOH solution. Hydrated calcium silicate was obtained from the reaction of the solutions produced by desilication and Ca (OH)₂ at the condition of Ca/Si (mol)=1, T=160°Cand t=1h. Xonotlite was synthesized by the hydrated calcium silicate using the hydrothermal temperature of 260°C for 2 hours. Keywords: Coal Fly Ash, Pre-desilication, alkali Hydrothermally-treated, Xonotlite nanofibres

• Periodical: Key Engineering Materials (Volume 633)
• Pages: 7-10
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.633.7
• Online since: November 2014
• Authors: Jing Yang, Xin Zhang, Hong Wen Ma, Ming Wei Wang, Han Wu
• Keywords: Alkali Hydrothermally-Treated, Coal Fly Ash, Pre-Desilication, Xonotlite Nanofibres

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