| 高铝粉煤灰脱硅反应工艺优化及机理探讨 |
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| 引用本文： | 孙应龙,梁振凯,祁光霞,徐辉,李磊,袁超,王毅.高铝粉煤灰脱硅反应工艺优化及机理探讨[J].环境科学研究,2016,29(5):753-760. |
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| 作者姓名： | 孙应龙 梁振凯 祁光霞 徐辉 李磊 袁超 王毅 |
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| 作者单位： | 1.清华大学环境学院, 北京 100084 |
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| 基金项目： | 国家自然科学基金青年科学基金项目(2014130052) |
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| 摘 要： | 为探究高铝粉煤灰脱硅最佳工艺条件及了解其脱硅过程物相转化机理,通过正交试验研究了w(NaOH)(10%~30%)、灰碱比(质量比,取1∶0.3~1∶2.0)、时间(1.0~4.0 h)和温度(90~150 ℃)对脱硅效率及铝硅比(质量比)的影响. 结果表明:w(NaOH)为20%、灰碱比为1∶0.5、反应时间为2.0 h、反应温度为120 ℃是粉煤灰脱硅反应的最佳条件；在最佳条件下铝硅比由原灰的1.23升至2.02以上,脱硅效率达38.6%.反应温度、灰碱比、碱液浓度、时间对脱硅率的影响依次减弱. 通过定量X射线衍射(XRD)分析了脱硅前后物相的变化,当温度高于120 ℃时,有大量方钠石形成,并且方钠石生成量(X)与铝硅比(Y)呈显著负相关,有Y=-0.012 8X+2.03 (R2=0.930,P<0.01). 由扫描电镜(SEM)对粉煤灰脱硅前后的表观形貌变化观察可知,粉煤灰在脱硅过程中非晶态SiO2部分溶解,从而进一步证实了方钠石的生成是影响脱硅效率的关键因素.
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| 关 键 词： | 高铝粉煤灰 脱硅 铝硅比 物相变化 方纳石 |
| 收稿时间： | 2015/12/2 0:00:00 |
| 修稿时间： | 2016/2/1 0:00:00 |
Optimization of Reaction Conditions and Mechanism of Desilication of High-Alumina Fly Ash |
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| SUN Yinglong,LIANG Zhenkai,QI Guangxi,XU Hui,LI Lei,YUAN Chao and WANG Yi.Optimization of Reaction Conditions and Mechanism of Desilication of High-Alumina Fly Ash[J].Research of Environmental Sciences,2016,29(5):753-760. |
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| Authors: | SUN Yinglong LIANG Zhenkai QI Guangxi XU Hui LI Lei YUAN Chao and WANG Yi |
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| Affiliation: | Department of Environmental Engineering, School of Environment, Tsinghua University, Beijing 100084, China,Department of Environmental Science and Engineering, Beijing Technology and Business University, Beijing 100048, China,Department of Environmental Engineering, School of Environment, Tsinghua University, Beijing 100084, China ;Department of Environmental Science and Engineering, Beijing Technology and Business University, Beijing 100048, China,Department of Environmental Engineering, School of Environment, Tsinghua University, Beijing 100084, China ;Northwest Institute of Nuclear Technology, Xi''an 710024, China,Department of Environmental Engineering, School of Environment, Tsinghua University, Beijing 100084, China,Department of Environmental Engineering, School of Environment, Tsinghua University, Beijing 100084, China and Department of Environmental Engineering, School of Environment, Tsinghua University, Beijing 100084, China |
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| Abstract: | To explore the optimal conditions of fly ash desilication, and to understand the phase transformation mechanisms during the process, this study investigated the effects of concentration of sodium hydroxide, ash alkali ratio, reaction time and temperature on desilication efficiency by orthogonal experiments. The optimal conditions determined were:the optimal sodium hydroxide concentration was 20% (m/m); the optimal ash alkali ratio was 1∶0.5; the optimal reaction time was 2.0 h; and the optimal reaction temperature was 120 ℃. After desilication, the Al/Si ratios increased from 1.23 to 2.02, and desilication efficiency reached 38.6%. The effects of reaction temperature, ash alkali ratio, sodium hydroxide and reaction time weakened according to the order. The changes of mineral phases were analyzed by quantitative X-ray diffraction (XRD). The results showed that mass sodalite was formed when the reaction temperature was higher than 120 ℃. The quantitative effect of sodalite generation on aluminum-silicon ratio was determined as well. The results indicated that the production of sodalite (X) was negatively correlated with aluminum silicon ratio (Y), Y=-0.0128X+2.03 (R2=0.930, P<0.01). The morphology changes during desilication were studied by scanning electron microscopy (SEM), confirming the partial dissolution of amorphous glass, and further verifying that sodalite generation during the desilication process was the key factor affecting desilication efficiency. |
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| Keywords: | high-alumina fly ash desilication Al/Si ratio phase transformation sodalite |
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