Investigation of LaF3 and ThF4 Sorption under Column Conditions in the LiF–NaF–KF–Activated Carbon System

Sorption of neodymium, lanthanum and thorium fluorides from melt under column conditions using AG-3 activated carbon at a temperature of 650°C was studied for the first time. The known eutectic mixture of alkali metal fluorides LiF–NaF–KF was employed as a melt. A special setup for studying the sorption process under column conditions was developed and created for the experiments. Three main sections were identified in the process of sorption of neodymium and lanthanum fluorides: the sorption front formation zone, sorption and breakthrough zones. It was shown that under the considered conditions, purification of thorium fluoride from lanthanum fluoride is possible. The sorption capacity towards lanthanum fluoride more than 5 mg/g at its maximum reached and depended on the melt flow rate through the activated carbon zone. Thorium fluoride was not sorbed by activated carbon under the studied conditions.