Carbon Mineralization Integrated Alkali Activation for Eco-Friendly Enrichment of Rare Earth Elements from Circulating Fluidized Bed Fly Ash

Abstract

Coal combustion and coal ash generation has been of global issue in both CO₂ emission and waste generation. As rare earths became critical, the significant content of rare earths in coal ash making it a prospect source for rare earths. Rare earths commonly compacted within the amorphous phase with Si, Al, Ca, and Fe. Alkali activation has been proved as the effective method for rare earths enrichment through decomposing amorphous compound. The CO₂ emission could be used in the carbon mineralization process to promote alkali activation for rare earths enrichment. This study integrated carbon mineralization and alkali activation into three step of experiments including alkali activation one, carbon mineralization, and alkali activation two for rare earths enrichment. The integrated method had the capacity of CO₂ mineralized at 55.37 kg per ton of coal ash and the enrichment rate of rare earths at 25.33%.