Radiation doses in heavy mineral sands mining

Heavy mineral sands mining are expanding worldwide to provide zirconium and Rare Earth Elements (REE) to microelectronics industry. Heavy mineral deposits often are located in coastal sand dunes, where the REE and zirconium are co deposited with uranium and thorium minerals. Extractive procedures include segregation of heavy minerals with rejection of the less dense minerals, in order to producing heavier minerals concentrates for stocking and export. Measurement of radiation doses received by workers at work posts were carried out in a mining facility and concentration plant in Mozambique. Radiation dose rates ranged from 1-3 μSv/h by most workplaces and up to 8 μSv/h by the stock piles of segregated non-magnetic mineral fractions, all well above the regional radiation background of 0.40 μSv/h. Analysis of the materials by radiochemistry and alpha spectrometry indicated that radionuclides present were mostly from the uranium and thorium series and their concentrations are reported. Workers in mineral separation facilities and mineral storage warehouses may be exposed to radiation doses exceeding the dose limit to members of the public, 1 mSv/year. Radiation protection measures need to be implemented at workplaces and the radiological risk for the public should be assessed in the surrounding environments. (author)