Extraction of Aluminum Hydroxide from Coal Fly Ash by Pre-Desilication and Calcination Methods

Abstract

Using coal fly ash from one thermal power plant in Ningxia, China as the raw material, aluminum hydroxide powder was successfully extracted by pre-desilication , calcination, dissolution and carbonation precipitation processes. The research results indicated that the mullite, Quartz and glass phase in the coal fly ash could be changed into NaSiO3, NaAlO2 and Na2CaSiO4 after the coal fly ash was treated by desilication and calcination. The SiO2and Al2O3 components in the coal fly ash were mainly separated by dissolving the calcined sample using water. The dissolution rate of Al2O3 from the calcined sample is 91%. The aluminum hydroxide powder extracted from the coal fly ash is bayerite with the particle size of more than 50m. The extraction rate of the aluminum hydroxide from the coal fly ash can be up to 83%.