Research Progress on the Preparation of Aerogel from Coal Gangue

Coal gangue is the waste produced in the process of coal mining and processing. It has large volume, high pollution and difficult to deal with. Coal gangue contains a lot of silicon and aluminum components, so making full use of it will be a very valuable silicon and aluminum resources.Aerogel is a kind of porous lightweight material with controllable structure. It is a solid substance with the smallest known volume density. It can be used in many fields such as thermal insulation, catalysis and aerospace.How to use cheap raw materials to prepare high performance aerogel to reduce production cost and realize high value utilization is one of the key technologies to develop aerogel materials.The dissolution effect of silica and aluminum from coal gangue under calcination activation and alkali fusion activation, as well as several means of removing impurities from activated leaching solution, such as water washing, solvent replacement, ionic liquid extraction and cation exchange resin, are described.The process scheme and final product performance of SiO₂ aerogel and SiO₂-Al₂O₃ aerogel prepared by one-step dissolution method and two-step dissolution method were compared, aiming to provide reference for high-value utilization of coal gangue and low-cost preparation of aerogel.