Enrichment of radioactive materials in sand deposits of Vietnam as a result of mineral processing

Deposits of valuable materials such as ilmenite and zircon are located in the various coastal regions of Vietnam. Since these deposits are used for mineral extraction, investigation for assessment of the possible radiological impact to workers were carried out. External dose rate measurements at the sites show an enhanced radiation level in the range of 0.3 to 4.5 μSv/h. Sand deposits show a high level of Th (range of average content from 95 μg/g to 135 μg/g) and U (range of average content from 17 μg/g to 28 μg/g), enhanced in the products after processing (range of average content from 830 μg/g to 1110 μg/g for Th, and of 167 μg/g to 253 μg/g for U). An enhanced level of Th was found not only in monazite, as thorium mineral, concentrate, but also in the mixture of ilmenite and zircon (range of average content from 243 μg/g to 635 μg/g). The high concentration of Th in the dust (range of 95 μg/g to 450 μg/g) resulting from the extraction process requires radiation protection measures.