Dissolution of Rare Earth Elements from Coal Fly Ash Particles in a Dilute H 2 SO 4 Solvent

Abstract

Recently, the worldwide supply of rare\rearth element (REE) resources will be severely restricted. On the other hand,\rcoal fly ash particles emitted from coal-fired electric power plants contain\rrelatively high concentrations of REEs. The contents of REEs in coal fly ash\rare regularly several hundreds of ppmw. In order to extract and recover REEs\rfrom coal fly ash particles, as a first step, we have investigated their\rdissolution behavior in a dilute H2SO4 solvent. The REE\rcontent of coal fly ash specimens has been precisely determined, and their\rpresence in the ash component of the original coal and their enrichment in coal\rfly ash particles during coal combustion have been suggested. REEs in coal fly\rash dissolve gradually in H2SO4 over time, and this\rimplies two types of occurrences of the REEs in coal fly ash particles. By\rapplying the unreacted core model to the dissolution behavior of REEs in a H2SO4 solvent, we can explain both types of occurrences.