PROCESSES FOR EXTRACTING RADIUM FROM URANIUM MILL TAILINGS

摘要

ABSTRACT OF THE DISCLOSUREThe removal of radium from acid-leached uranium milltailings has been difficult due to its strong retention as mixedsulfates and in adsorbed forms. With this invention theleaching action of a complexing agent (reducing the free radiumcation concentration in solution) is combined with that of areducing agent. Thus, high valency metal hydroxides and basicsalts (notably Fe3+) which tend to retain radium are convertedto the lower valency form which is much more soluble in thecomplexing agent. The reducing agent employed is sodiumhydrosulfite, in combination with various organic complexingagents; the preferred complexing agent is EDTA. Over 90% ofthe radium in uranium leach tailings from Elliot Lake can beremoved in 1 hour contact at room temperature with a solutioncomprising 0.04M of both sodium hydrosulfite and EDTA, with 1.0Mpotassium chloride added as a surface charge depressant. Thegradual addition of the solids to liquid permits the use of lowliquid/solid ratios.