Study on speciation and effect of ionic strength on U Migration in Mineral-Water system

An experiment was designed to study the speciation of uranium (U) at mineral-water interface and to study the effect of ionic strength (IS) of different salts on the migration of U from solid to liquid phase both in binary system (Mineral-water) and ternary system (Mineral-Water-Humic Acid). For the study ores bearing U-minerals differ in their host rocks were chosen and mineralogical study was carried out using XRD. All the experiments were designed taking ore to water in the ratio 1g:10 mL. Speciation study of U in aqueous phase using speciation code MEDUSA revealed that (UO2)2 CO3(OH)3−, UO2(CO3)22-, UO2(CO3)34-, UO2CO3, UO2(OH)2, and UO2OH+ are the predominate species for both the systems. Study of speciation of U in terms of oxidation states indicates that about 5.4% of total U exist as U(VI) in ore A and reaming 94.6% in U(IV) state, whereas in Ore B about 9% of total U exist as U(VI) and reaming 91% in U(IV) state. Study of ionic strength versus desorption of U reveals that, there occurs an increase in U desorption from both the Ore A and B with Ca2+ increase in IS of the aqueous phase. salts induces desorption more in comparisons to-Na+ salt and among anions NO3 salts causes more desorption in comparison to Cl −salts. Study of ternary system (Ore-Water-Humic acid) revealed that, presence of humic acid (HA) accelerate the desorption in the experimental range of IS of all salts except in case of Ca-salts at higher ionic strength the U concentration reduces in aqueous phase of ternary system.