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中南大学学报(自然科学版)

Journal of Central South University

第49卷    第7期    总第287期    2018年7月

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文章编号:1672-7207(2018)07-1590-08
粉煤灰组成结构及其对碱溶预脱硅性能的影响
连选,彭志宏,齐天贵,周秋生,刘桂华,李小斌,肖小龙

(中南大学 冶金与环境学院,难冶有色金属资源高效利用国家工程实验室,湖南 长沙,410083)

摘 要: 采用傅里叶红外光谱和核磁共振波谱仪等现代检测技术,研究3种不同类型高铝粉煤灰的组成结构及其对碱溶预脱硅过程中溶出性能的影响。研究结果表明:粉煤灰中的硅主要以Q2(架状硅酸盐)和Q4(链状硅酸盐)的形式存在,铝主要形成四配位的[AlO4]四面体和六配位的[AlO6]八面体。低温形成的粉煤灰中硅和铝主要以非晶态玻璃体形式存在,对碱溶预脱硅过程不利,预脱硅率低;经高温热处理活化后,非晶态玻璃体转化为稳定的γ-Al2O3、β-石英、Al-Si尖晶石和莫来石相,可以明显改善粉煤灰预脱硅性能。钙对碱溶预脱硅过程不利,粉煤灰中的钙易与溶出的硅和铝发生反应形成大量的钙硅渣,导致预脱硅率降低。

 

关键词: 高铝粉煤灰;结构;碱溶液;预脱硅;莫来石

Composition and structure of coal fly ash and its effect on pre-desilication in alkali solution
LIAN Xuan, PENG Zhihong, QI Tiangui, ZHOU Qiusheng, LIU Guihua, LI Xiaobin, XIAO Xiaolong

National Engineering Laboratory for Efficient Utilization of Refractory Non-ferrous Metal Resources, School of Metallurgy and Environment, Central South University, Changsha 410083, China

Abstract:The compositions and structures of three forms of high aluminum fly ashes and their effects on pre-desilication in alkali solution were studied by using modern detection techniques of Fourier infrared spectroscopy and nuclear magnetic resonance spectrometer. The results show that the silicon in fly ashes exists mainly in the forms of Q2 (tecto-silicates) and Q4(chain-silicates), while aluminum is in four-coordinate and tetrahedral crystal [AlO4] or six-coordinate and octahedral crystal [AlO6]. Silicon and aluminum in fly ashes formed at low temperature mainly exist as amorphous vitreous phases, which are disadvantageous to the alkali-soluble pre-desilication process, resulting in a low pre-desilication ratio. Amorphous vitreous phases convert to more stable γ-Al2O3, β-quartz, Al-Si spinel, and mullite phases with the treatment at elevated temperature, which can obviously improve the pre-desilication performance of fly ashes. Additionally, calcium has an adverse effect on alkali-soluble pre-desilication process and decreases the pre- desilication ratio, for it easily reacts with the dissolved silicon and aluminum to form a large amount of calcium aluminosilicate hydrate.

 

Key words: high aluminum fly ashes; structures; alkali solution; pre-desilication; mullite

中南大学学报(自然科学版)
  ISSN 1672-7207
CN 43-1426/N
ZDXZAC
中南大学学报(英文版)
  ISSN 2095-2899
CN 43-1516/TB
JCSTFT
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