Immobilization of Radium in Uranium Mine and Mill Tailings

摘要

Radium has been coprecipitated from solution as the arsenate in which ferric iron, barium, copper and lead are the macro ions. The order of efficiency of the macro ions in removing radium was found to be Ba > Fe > Pb > Cu at a pH of 6. It is expected that at higher pH's i.e., greater than 8, ferric iron will change positions. This change in position will be caused by the formation of ferrate ion hence increasing the solubility of ferric arsenate. The removal of radium from solution by ion exchangers consisting of the arsenates of ferric iron, barium, copper and lead was successful. As the pH is increased from 4 to 10 the efficiency of these exchangers in removing radium increases. The columns removed over 99 percent of the radium at pH's of 5.6 and higher. The order of efficiency of the exchangers in removing radium is not well defined. Thorium has been precipitated as the arsenate over the pH range of 2 to 9.6. This reaction suggests the possibility of using arsenate to remove thorium from uranium mill plant streams and as a reagent to keep thorium in the tailings ponds. (Atomindex citation 16:054967)