Uranium Recovery from Uranium Tailings Using the Low-Temperature Chlorination Roasting and Nitric Acid Leaching Process

To address the problems of low leaching efficiency and the fact that the uranium content in leaching residue is higher than the emission standard in the traditional nitric acid leaching uranium tailing and uranium extraction process, the experimental study of low-temperature chlorination roasting and nitric acid leaching was carried out. The effects of roasting temperature, NaCl addition, and roasting time on uranium leaching rate were investigated, and the morphological structure change and phase transformation of roasted minerals were analyzed. After the low-temperature roasting of sodium chloride, the mineral structure was obviously destroyed, the structure became loose, the voids and microcracks increased, and the size of tailing particles decreased. This is mainly due to the reaction of NaCl with metal compounds in minerals. However, when the sodium chloride is excessive, the formation of hydrogen chloride will promote the formation of new compounds, such as Na2Pb2O7 and Zr7O9F10, and form a secondary coating of uranium, resulting in a decrease in the leaching rate. The optimum process conditions of chlorination roasting are as follows: a roasting temperature 250 °C, a 20% addition of NaCl to the tailing mass, a roasting time of 120 min, and a uranium leaching rate of 93.38%. Compared with traditional nitric acid leaching, the leaching rate of uranium increased by 16.64%.