LAUSR

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.