Thorium in ilmenite and its radiological implications in the production of titanium dioxide

This study gives the results of measurements of 232 Th and 228 Ra in the titanium mineral ilmenite and its derived products and an assessment of related radiological issues in mineral separation and titanium dioxide production plants in India. The concentrations of 232 Th and 228 Ra in ilmenite, synthetic rutile and TiO 2 are presented along with percent distribution of the radionuclides in different stages of process. External gamma exposure rates and airborne thorium levels in plants processing such minerals are studied. The study estimated a potential external gamma exposure of 1 mSv and an inhalation dose of 0.7 mSv annually to the occupational worker due to the presence of naturally occurring radioactive material in these industries. The concentrations of the nuclides in liquid effluent and solid wastes are analysed, and disequilibria with respect to 228 Ra are observed.