针对低品位铀尾矿因脉石含量高、物相赋存状态复杂而造成的铀浸出率低的问题,提出添加辅助氧化剂破坏脉石结构而实现强化浸出铀的思路.采用单因素实验法对比常规酸浸和3种氧化剂(H2O2、MnO2和Fe3+)强化酸浸对铀浸出率的影响.结果表明:当浸出温度、硫酸浓度和液固比分别为30℃、1 mo1/L和20∶1时,采用常规酸浸6h后铀的浸出率仅为78％,而在相同的浸出条件下,强化酸浸1.5 h铀的浸出率可达到95％.浸出渣的XRD及SEM-EDS分析结果表明,H2O2及MnO2均能破坏脉石晶体结构,减少颗粒团聚,但添加MnO2后生成新的硅酸锰盐晶体,Fe3+不能破坏脉石结构,但其氧化作用在一定程度上能加快铀的浸出.
In view of low extraction rate of uranium caused by high gangue content and complex occurrence state of phases existing in low-grade uranium tailings,adding suitable oxidants in leaching process to destroy the gangue crystal structure were proposed to enhance the uranium extraction.The effects of traditional acid leaching and intensified leaching with three oxidants (H2O2,MnO2 and Fe3+) on uranium extraction were investigated using single-factor experiments.The results show that uranium extraction ratio is only 78％ after 6 h in traditional leaching at temperature,sulfuric acid concentration and liquid-solid ratio of 30 ℃,1 mol/L and 20∶1,respectively,while the extraction ratio reaches 95％ after 1.5 h in intensified leaching under the same leaching conditions.H2O2 and MnO2 can decompose the gangue crystal structure and reduce the particle agglomeration.However,manganous silicate forms when MnO2 is used as oxidants.The ferric iron has no effect on destroying the gangue crystal structure,but it can improve the uranium extraction ratio depending on its oxidation influence.
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