Abstract:In this study, alkali-solution desilication combined with mechanochemical extraction method is applied to recover rare earth elements (REEs) from high alumina fly ash (HAFA) and obtain high-value aluminium-rich residue. The results showed that REEs in HAFA were mainly enriched in the glass phase. The alkali-solution desilication process can be used to efficiently and selectively dissolve the glass phase (retain the aluminium-rich mullite-corundum phase) in HAFA under mild conditions, and release the REEs into NaOH solution to be converted into rare earth hydroxide precipitates. Then, EDTA was used as a leaching agent to efficiently and rapidly extract the REEs from the desilication residue by mechanochemical method. Under the optimal conditions of the leaching process, the extraction efficiencies of La, Ce, Pr and Nd were 85.99%, 83.30%, 82.03% and 88.71%, respectively, while aluminium-rich slag was obtained (Al2O3 content of 68.23 wt%; Al∶Si=2.517). This study provides a new strategy for the green and high value-added recycling of HAFA.