Quantification of Thorium and Rare Earth Elements in Perak's Ex-Mining Monazite

Monazite is the rare-earth ore mineral that contained thorium in association with uranium and rare earth elements (REE). In Malaysia, monazite is obtained from amang; a byproduct from tin mining. The objective of this study is to quantify the content of thorium, REEs and other metals contained in monazite obtained from Perak's ex-mining area. The most common technique used to quantify thorium and REEs is energy dispersive x-ray fluorescence spectrometer (ED-XRF). Although this technique is reliable for bulk elemental analysis, but it is usually quantified with non-standard measurement. In this study, the quantification was performed using a combination of two equipment; wavelength dispersive x-ray fluorescence (WD-XRF) spectrometer and field emission scanning electron microscope (FESEM) integrated with energy dispersive x-ray spectrometer (EDX). WDXRF provides an accurate bulk elemental analysis with standard reference while FESEM-EDX gives more detailed elemental content based on microstructural spot analysis. This study compares between as received and ground (milled) monazite. Overall, both techniques show Perak's monazite is a monazite-(Ce) [(Ce, Nd, La, Gd)-PO₄ minerals contained about 7 % thorium and 0.2 % U. The content of thorium and REEs were higher in milled samples. Thus, smaller size monazite particles give higher thorium and REEs recovery. (author)