SORPTION AND COPRECIPITATION OF TRACE CONCENTRATIONS OF THORIUM WITH VARIOUS MINERALS UNDER CONDITIONS SIMULATING AN ACID URANIUM MILL EFFLUENT ENVIRONMENT

Sorption of thorium by pre-existing crystals of anglesite (PbSO4), apa tite (Ca-5(PO4)(3)(OH)), barite (BaSO4), bentonite (Na0.7Al3.3Mg0.7Si8 O20(OH)(4)), celestite (SrSO4), fluorite (CaF2), galena (PbS), gypsum (CaSO4 . 2H(2)O), hematite (Fe2O3), jarosite (KFe3(SO4)(2)(OH)(6)), ka olinite (Al2O3 . 2SiO(2) . 2H(2)O), quartz (SiO2) and sodium feldspar (NaAlSi3O8) was studied under conditions that simulate an acidic urani um mill effluent environment. Up to 100% removal of trace quantities o f thorium (approx. 1.00 ppm in 0.01 N H2SO4) from solution occurred wi thin 3 h with fluorite and within 48 h in the case of bentonite. Quart z, jarosite, hematite, sodium feldspar, gypsum and galena removed less than 15% of the thorium from solution. In the coprecipitation studies , barite, anglesite, gypsum and celestite were formed in the presence of thorium (approx. 1.00 ppm). Approximately all of the thorium presen t in solution coprecipitated with barite and celestite; 95% coprecipit ated with anglesite and less than 5% with gypsum under similar conditi ons. When jarosite was precipitated in the presence of thorium, a sign ificant amount of thorium (78%) was incorporated in the precipitate.