REFINING OF URANIUM FROM LEACH PLANT ION EXCHANGE NITRATE ELUATES BY EXTRACTION WITH DIBUTYL BUTYLPHOSPHONATE. Mines Branch Investigation Report IR 60-120

Continuous liquid-liquid extraction tests were done on current samples of ion exchange nitrate eluates with 25% v/v dibutyl butylphosphonate in kerosene. From eluates containing 15 to 28 g U/sub 3/O/sub 8//l, recoveries of 99% or better were obtained in four countercurrent stages. The effects of nitrate and sulfate concentrations on extraction equilibria were determined. The extract, analyzing 75 to 95 g U/sub 3/O/sub 8//l, was stripped effectively in four stsges with 5 to 10% ammonium sulfate solutions at pH's ranging from 3.5 in the first stage to 6.0 in the last. The uranium was precipitated as ammonium diuranate by gaseous ammonia, and the barren strip was recycled to the circuit. The effect of temperature and dilution of the ammonia with nitrogen on the filtering rate of the ammonium diuranate (ADU) precipitate and the subsequent reduction and sintering properties were investigated. The product was of nuclear grade purity and was used to produce high density (>10.5) uranium dioxide pellets. (auth)