Liberation Mechanism of Uranium from Radioactive Metallurgical Waste Containing Uranium by a Clean Leaching Method
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https://doi.org/10.1007/s11837-020-04264-8 Ó 2020 The Minerals, Metals & Materials Society
INTERFACIAL STABILITY IN MULTI-COMPONENT SYSTEMS
Liberation Mechanism of Uranium from Radioactive Metallurgical Waste Containing Uranium by a Clean Leaching Method FANGYING GAO,1 MI LI,1,2,3 XIAOWEN ZHANG,1,2 CHUNMEI HUANG,1 XIAOYAN WU,1,2 YICHUAN ZHOU,1 and QI FANG1 1.—School of Resource and Environment and Safety Engineering, University of South China, Hengyang 421001, China. 2.—Hengyang Key Laboratory of Soil Pollution Control and Remediation, University of South China, Hengyang 421001, China. 3.—e-mail: [email protected]
Developing a highly efficient method to recover uranium from metallurgical waste can alleviate the shortage of uranium resources. However, the dissociation of uranium is limited by the ultrafine uranium particles embedded in the gangue. Dilute alkali pretreatment is an effective process to improve the dissociation rate of uranium. Moreover, the leaching kinetics of the pulverized gangue during the pretreatment process is the decisive factor affecting the efficiency of uranium dissociation. The traditional shrinking core model cannot accurately depict the leaching kinetics of low-grade uranium ore due to the encapsulation of gangue minerals. The Avrami equation was used to investigate the dissociation kinetics of uranium during pretreatment. The results showed that the alkali pretreatment decreased the activation energy and reaction order of subsequent reactions by pulverizing the gangue structure and producing a leaching ‘‘micro-path’’, thus significantly reducing the dependence of the uranium acid leaching process on temperature and acid concentration.
INTRODUCTION Uranium is a key element in the production of nuclear power, with global demand continuously increasing.1–4 According to data from the World Nuclear Association, China’s external dependence on uranium climbed to 80.1% in 2017.5 Moreover, domestic production accounts for only a quarter of China’s uranium demand and is expected to decline even further in the near future.4 Tremendous efforts have been devoted to the extraction of uranium from other ores at the ppm level (tailings, coal), and from radioactive metallurgical waste containing uranium, to safeguard the development of the nuclear energy. In addition, the recovery of uranium from radioactive metallurgical waste can effectively reduce its radioactivity and chemical toxicity to environmental and ecological systems.6 Therefore, reprocessing and recycling uranium from radioactive metallurgical waste containing uranium (Received January 14, 2020; accepted June 29, 2020)
can provide environmental and socio-economic sustainability. However, the recovery of uranium from radioactive metallurgical waste containing uranium is arduous due to its extremely low concentration (20–200 ppm)7 and the encapsulation of uranium by a variety of gangue minerals.8–10 To accomplish this, the design of a cost-effective recovery process with fast kinetics of uranium extraction and no secondary pollution is cru
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