Preparation of hydro-sodalite from fly ash using a hydrothermal method with a submolten salt system and study of the phase transition process  

作　　者：Yan-bing Zong Cheng-yu Zhao Wen-hui Chen Zhao-bo Liu Da-qiang Cang 

机构地区：[1]School of Metallurgical and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China [2]China Nonferrous Engineering and Research Institute(China ENFI Engineering Corporation),Beijing 100038,China

出　　处：《International Journal of Minerals,Metallurgy and Materials》2020年第1期55-62,共8页矿物冶金与材料学报（英文版）

基　　金：financially supported by the National Natural Science Foundation of China (No. 51474028);the National Key Research and Development Program of China (No. 2017YFC0210301);China Postdoctoral Science Foundation (No. 2017M621034);the Science and Technology Benefiting Citizens Program of Ningbo, China (No. 2015C50058)

摘　　要：Hydro-sodalites are zeolitic materials with a wide variety of applications.Fly ash is an abundant industrial solid waste,rich in silicon and aluminum,from which hydro-sodalite can be synthesized.However,traditional hydrothermal synthesis methods are complex and cannot produce high-purity products.Therefore,there is a demand for processing routes to obtain high-purity hydro-sodalites.In the present study,high-purity hydro-sodalite(90.2 wt%)was prepared from fly ash by applying a hydrothermal method to a submolten salt system.Samples were characterized by powder X-ray diffraction(XRD),scanning electron microscopy(SEM),thermogravimetry and differential thermal analysis(TG–DTA),and Fourier transform infrared spectroscopy(FTIR)to confirm and quantify conversion of the raw material into the product phase.Purity of the samples prepared with an H2O/Na OH mass ratio of 1.5 and an H2O/fly ash mass ratio of 10 was calculated and the conversion process of the product phase was studied.Crystallinity of the product was influenced more by the Na OH concentration,less by the H2O/fly ash mass ratio.The main reaction process of the system is that the Si O ions produced by dissolution of the vitreous body in the fly ash and Na+ions in the solution reacted on the destroyed mullite skeleton to produce hydro-sodalite.This processing route could help mitigate processing difficulties,while producing high-purity hydro-sodalite from fly ash.Hydro-sodalites are zeolitic materials with a wide variety of applications. Fly ash is an abundant industrial solid waste, rich in silicon and aluminum, from which hydro-sodalite can be synthesized. However, traditional hydrothermal synthesis methods are complex and cannot produce high-purity products. Therefore, there is a demand for processing routes to obtain high-purity hydro-sodalites. In the present study, high-purity hydro-sodalite（90.2 wt%） was prepared from fly ash by applying a hydrothermal method to a submolten salt system. Samples were characterized by powder X-ray diffraction（XRD）, scanning electron microscopy（SEM）, thermogravimetry and differential thermal analysis（TG–DTA）,and Fourier transform infrared spectroscopy（FTIR） to confirm and quantify conversion of the raw material into the product phase. Purity of the samples prepared with an H2O/Na OH mass ratio of 1.5 and an H2O/fly ash mass ratio of 10 was calculated and the conversion process of the product phase was studied. Crystallinity of the product was influenced more by the Na OH concentration, less by the H2O/fly ash mass ratio. The main reaction process of the system is that the Si O ions produced by dissolution of the vitreous body in the fly ash and Na+ ions in the solution reacted on the destroyed mullite skeleton to produce hydro-sodalite. This processing route could help mitigate processing difficulties, while producing high-purity hydro-sodalite from fly ash.

关 键 词：fly ash submolten salt system hydrothermal method hydro-sodalite 

分 类 号：TQ536.4[化学工程—煤化学工程]