Extraction of Aluminum from Coal Fly Ash by Alkali Activation with Microwave Heating

Abstract

Recovering aluminum from coal fly ash (CFA) is a practical option for its value-added utilization. The alkali activation of CFA with Na2CO3 was carried out using two heating methods: the conventional heating (CH) and microwave heating (MWH). Compared to CH, MWH enhanced the atomic diffusion and mass transportation in the CFA-Na2CO3 mixture, accelerated the decomposition of mullite and the formation of the soluble Al-containing materials, thus greatly reducing the sintering temperature and dramatically shortening the activation reaction time. Under the moderate activation condition in MWH (700°C and 20 min), the aluminum extraction could reach 95.52% or more.