SELECTIVE LEACHING OF URANIUM FROM PHOSPHATE ROCK BY DILUTE MINERAL ACIDS

The present study deals with the separation, under suitable conditions, of uranium from carbonate containing phosphate ores by leaching with mineral acids. If calcined rock is treated with dilute acid, approximately 70% of the uranium, and only 15 to 20% of the phosphate pass into solution. Four factors have been found to influence the uranium extraction the temperature of calcination, the state of oxidation of the uranium in the rock, the concentration of sodium in the rock, and the porosity of the rock. Satisfactory extraction of the uranium is achieved when the rock is calcined at 700 to 800 deg C under oxidizing conditions and in the presence of at least 1% of sodium ions. Neglect of any one of these factors leads to poorer uranium extraction. (auth)