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About 150 flotation tests were done on Elliot Lake ore with 15 reagents as collectors in order to screen and choose an attractive collector for uranium flotation. Several variables were studied including pH, conditioning time and mode of collector addition. The tests were done in a Denver or Agitair subacration cell. The particle size of the ore was kept at 85% below‐325 mesh. Three reagents (Kelex 100, TOPO, and cupferron) were identified as having the most promise. The best results were obtained with cupferron, where 93‐95% of the uranium was recovered in 25‐30% of the mass of original ore. Radium in the tails varied between 15 and 30 pCi/g depending on the mass of uranium floated. Radium was recovered in proportion to uranium in the tests done at neutral pH. The preconcentration results obtained by flotation alone were comparable to those obtained by Raicevic of CANMET using pyrite flotation and wet high intensity magnetic separation of uranium. The consumption of cupferron was 4 kg/Mg ore for each flotation stage. This was 10‐15 times larger than the collector usage in conventional oxide flotation. This scheme did not require other reagents as depressants, activators or modifiers. Reproducibility was good and similar recoveries were obtained with fresh or old ores, and with distilled or mine water. The selectivity of cupferron for uranium in the ore studied was outstanding.

Measurements are reported for the equilibrium adsorption of cupferron from solutions by uranium oxide, quartz, illite, a mixture of these three, pitchblende, pyrite and brannerite ore. The cupferron concentration ranged from I to 6 g/L, and the pH was 7 and 8. Most isotherms followed the Langmuir model, although Freundlich behaviour was observed for illite and pitchblende. Most adsorption was pH independent except for illite and pitchblende. The adsorption isotherms for a mixture of uranium oxide, quartz and illite in the same proportions as in the naturally occurring ore agreed with the adsorption on the pyrite-free ore at pH 8 but not pH 7. We attribute the discrepancy to the use of illite as the model clay.The specific adsorption of cupferron on quartz and illite is lower by a factor of about 50 and 5 , respectively, than the adsorption on uranium oxide. Specific adsorption less than 1 mg cupferron per gm of pyrite free ore does not float the mineral. The corresponding equilibrium concentration of cupferron is 0.5 g/L. A qualitative model is given, and the implications of this work for practical operations are presented.On prksente des mesures relatives a 1'Cquilibre d'adsorption du cupferron en solution sur I'oxyde d'uranium, le quartz, l'illite, un melange des trois, la pechblende, la pyrite et le minerai brannerite. La concentration du cupferron est comprise entre I et 6 g/L et le pH est de 7 et 8. La plupart des isothermes suivent le modkle de Langmuir, bien qu'on ait observe un comportement de Freundlich pour I'illite et la pechblende. La plupart des adsorptions ne dependent pas du pH, sauf pour I'illite et le pechblende. Les isothermes d'adsorption pour un melange d'oxyde d'uranium, de quartz et d'illite, dans les m&mes proportions que dans celles du minerai naturel, sont en accord avec I'adsorption sur le minerai sans pyrite a pH 8, mais cela n'est pas le cas a pH 7; on attribue cette contradiction a I'emploi de I'illite comme modble de I'argile.L'adsorption spkcifique du cupferron sur le quartz et I'illite est plus faible que I'adsorption sur I'oxyde d'uranium respectivement par un facteur de 50 et 5. Une adsorption spkcifique infkrieure ii 1 mg de cupferron par g de minerai sans pyrite ne permet pas la flotation du mineral. La concentration d'equilibre correspondante du cupferron est 0.5 g/L. On prksente un modble qualitatif et on indique les implications pratiques de ce travail. reviously, we reported (Muthuswami et al., 1983) that

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