Investigation on the radiation decontamination of lanthanum oxide during its production from ion-adsorption rare earth ores in China

Abstract

A systematic study on radiation decontamination in lanthanum oxide production from ion-adsorption rare earth ores in China was conducted. The distribution characteristics of radiation levels during the production process was clarified, and effective measures for radiation decontamination were proposed. The results showed that during the lanthanum oxide production process, radiation would be separated from lanthanum and enter the production wastewater along with calcium, which is easily decontaminated through sodium carbonate precipitation. The percentage decontamination of calcium was close to and less than those of total α and total β, and it could be used for evaluating the percentage decontamination of radiation to ensure that the radiation level is controlled at a low level, as required in practice, instead of waiting for 140 days to analyse the values of total α and total β. Under the optimal condition of maintaining the terminal pH at 8.0–10.0, 99.66% of total α and 99.56% of total β in the production wastewater were decontaminated, and the radiation level of total α and total β could be drastically decontaminated to much lower than the national discharge standard of China, GB8978-1996 (total α < 1.0 Bq/L and total β < 10.0 Bq/L).