Reduction of UO2 and ThO2 content in zircon mineral from Bangka Region using calcium borate and hydrochloric acid

Abstract

In an effort to reduce radiation exposure in the use of zircon minerals as opacity for the ceramic industry, it is required that the concentrations of UO2 and ThO2 contained in zircon must be less than 500 ppm. The purpose of this study was to reduce the concentration of UO2 and ThO2 in zircon minerals. The experimental investigation was initiated by synthesizing of calcium borate (CB), roasting of zircon concentrate with CB at various temperatures, and leaching with hydrochloric acid. The product quality of zircon minerals before and after roasting and leaching was characterized by Fourier Transform Infrared Spectrometer, X-Ray Diffractometer, and X-ray Fluorescence Spectrometer. The experimental results show that roasting zircon concentrate with CB at a zircon/CB ratio of 5/5 (weight/weight), a temperature of 1200 °C, a contact time of 3 h, and the leaching of the roasted results with 6 M HCl can reduce the total concentration of UO2 and ThO2 in zircon from 2008,1 ppm to 498.4 ppm. It can be concluded that the prototype zircon product from the experimental results has fulfilled the premium grade zircon with UO2 and ThO2 content of less than 500 ppm.