铀水冶废渣氯化焙烧强化预处理提铀工艺研究. (Chinese)

For a uranium purification enterprise in the south of China, the waste residue (uranium grade 12000%), which is a mixture of rubble from the extraction in the purification system and other wastewater passing through the plate and frame after resting, has a complex composition, with the presence of diatomaceous earth as a filter aid in addition to the impurities such as acidic solids and organic matter produced in the uranium leaching process. The conventional natural treatment method has a poor leaching effect and a low uranium recovery rate with nitric acid heating. To this end, low-temperature chlorination roasting nitric acid leaching study was conducted, in which sodium chloride was added to the specimen for roasting pretreatment. Then the roasted model was leached using nitric acid. The effects of roasting temperature, sodium chloride addition, roasting time, sample size and other influencing factors on the leaching behavior of uranium were investigated. The experimental results show that the uranium leaching rate reaches 95.97% under the conditions of 20% NaCl addition, 200 ℃ roasting temperature, 2 hour roasting time, 7.4 mol/L nitric acid concentration, 80 ℃ leaching temperature and 2 hour leaching time, which is 19.52% higher than that of the conventional acid leaching process. The results show that the waste slag’s specific surface area and porosity increase significantly after pretreatment with sodium chloride roasting, which promots the dissociation of uranium and increased the contact area between uranium and acid, thus leading to a significant increase in the uranium leaching rate. And the chlorination roasting can have an activating effect on the metal components in the specimen. It can play a role in screening some oxides, such as silica, iron oxide, etc. Combined with the specimen’s physical and chemical composition analysis, it is due to the formation process of the illustration mixed with iron-containing flocculants, binders, and other substances to form uranium wrapping. At the same time, the chlorine and hydrogen chloride gas generated by sodium chloride roasting can be part of the iron components chlorinated into ferric chloride, and with the iron oxide in the process of confinement due to chemical gas phase migration reaction to generate chloride, which not only to uranium wrapping structure. This not only causes damage to the uranium wrapper structure, which allows more exposure of the uranium component but also has a catalytic effect on the uranium leaching process, which leads to a significant increase in the leaching rate of uranium. At the same time, because solid sodium chloride is used, the roasting conditions are relatively mild, and therefore the generation of contaminating gases is within the control range. [ABSTRACT FROM AUTHOR]

针对某铀水冶企业生产过程中产生的废渣（铀品位12000%）浸出效果不佳,铀回收率低,至今尚未回收利用的现状,开展了低温氯化焙烧强化预处理-硝酸浸出试验研究,考察了焙烧温度,氯化钠添加量,焙烧时间,样品粒度等因素对铀浸出行为的影响.结果表明：在氯化钠添加量为样品量的20%,焙烧温度200 ℃,焙烧时间2 h,硝酸浓度7.4 mol/L,浸出温度80 ℃,浸出时间2 h的条件下,铀浸出率达到95.97%,与传统酸浸工艺相比,提高了19.52%.物相分析结果表明：经过氯化钠焙烧预处理后的废渣比表面积和孔隙率明显增加,促进了铀的解离,加大了铀与酸的接触面积,从而使得铀浸出率大幅提升.该工艺为铀水冶工艺废渣的回收利用提供了技术支撑. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)