DETERMINATION OF RARE EARTH ELEMENT CONTENTS IN THE PULMODDAI-BASED MONAZITE.

Rare Earth Elements (REE) have become significant to our technological world as they have unique magnetic, phosphorescent and catalytic properties. The demand for REE has increased in recent past because they can be employed as both metals and alloys. The Pulmoddai deposit is the largest known heavy mineral sand deposit in Sri Lanka. Monazite is a mineral containing thorium which can be used instead of uranium for nuclear power generation and is common in the Pulmoddai deposit. The aim of the study was to diagnose the common heavy minerals using physical and optical properties, estimate the heavy mineral composition and quantify the rare earth element contents in Pulmoddai based monazite. A sand sample was collected upto 50-75cm depths and heavy minerals were separated through gravitational and magnetic separations. Monazite was microscopically recovered using the optical microscopes. Rare earth element analysis was done using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). According to the results obtained, ilmenite, garnet, rutile, zircon, spinal, silimanite and monazite were major heavy minerals present in the mineral sand deposit. The REE percentages contained in monazite were Cerium (̴28%), Lanthanum (̴15%), Neodymium (̴10%), Promethium (̴3%), Samarium (̴2%), Gadolinium (̴2%) and Yttrium (̴1%). sand. Due to the higher cerium concentration, value of the Pulmoddai monazite is considered to be economically enhanced and avenues for value addition by extraction of REE from Pulmoddai monazite should be critically evaluated.