On the characterization and leaching of rare earths from a coal fly ash of Indian origin

Abstract

ABSTRACT Fly Ash from a lignite coal-based power plant was spotted in southern India to contain economic concentration of total Rare Earth Elements (TREE) in the order of 2100 mg/kg, of which 20% are heavier rare earth elements (HREE). Optical microscopy revealed that the portion of Lighter rare earth elements (LREE) occurs in the form of Zircon and Monazite minerals. Direct leaching of the fly ash yielded differential solubilization LREE(50%) and HREE(90%), equivalent to 60% recovery of TREE, under the optimum conditions: Sulfuric acid (1.5 M initial concentration), 20% solids (by wt.), Room Temperature (25°C), 5 h contact time.