Calcium chloride (CaCl2) roasting and nitric acid (HNO3) leaching were combined to remove uranium and radioactivity from uranium tailings. The results show that the uranium and gross α and β… Click to show full abstract
Calcium chloride (CaCl2) roasting and nitric acid (HNO3) leaching were combined to remove uranium and radioactivity from uranium tailings. The results show that the uranium and gross α and β radioactivity removal efficiencies improve with increasing CaCl2 addition and HNO3 leaching time and reach maximum values of 81.5%, 87.9% and 86.5%, respectively, after roasting with 50% CaCl2 for 120 min, followed by 1 mol L−1 HNO3 leaching. The uranium leaching rate is 62.3% higher than with direct acid leaching. The mineralogical characteristics of the roasted clinker show that roasting uranium tailings with CaCl2 changes their mineral phase, and Ca2+ becomes incorporated into the silicate matrix, which is beneficial for removing uranium and other radionuclides by acid leaching.
               
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