Removal of Fe from fly ash by carbon thermal reduction

Main chemical compositions of fly ash is SiO2 and Al2O3, which are also main chemical components of zeolite. Therefore, fly ash can be used to prepare zeolite after removing impurities such as Fe. Previous studies have only used the methods of magnetic separation and acid leaching to remove impurities, which can not wipe out the impurities thoroughly, especially Fe impurities. In the paper, carbon thermal method is used to reduce hematite, and then low valence Fe is removed by magnetic separation and acid leaching. The experimental results derived from XRF, XRD, SEM/EDS analysis show that the total iron content of the fly ash is reduced to be 0.49% from 4.62%, the CaO content is reduced to be 2.08% from 9.61% after 1 pretreatment cycle. The raw material requirements for the preparation of zeolite are preliminarily achieved. (C) 2017 Published by Elsevier Inc.