铀矿酸浸过程中脉石蚀变对铀解离的影响机理研究

The exploitation of low-grade uranium ores has become a hot topic for relieving the shortage of uranium resources in the world.In addition, the serious radioactive contamination of tailings from low uranium recovery processes by leaching complex mineralogy uranium ores with high content of gangue in a leaching system that has synergistic effects caused by environmental factors, is a key problem in uranium production industry. Based on the relationship between gangue alteration and uranium dissociation, process mineralogy and materials science research methods were used to find out the micro-structure environment of uranium ores in this program, which could assisted to predict inert structure features of uranium ores. Therefore, the related hydrometallurgical theories were used to reveal the gangue alteration features during acid leaching from the perspective of thermodynamics and kinetics. The crystal structure refinement methods were applicated to investigate the effect of environmental factors on uranium dissociation during gangue alteriation process in micro level. Besides, the controling methods of gangue alteriation will be found through comparative study of gangue alteriation characteristics and the variation of uranium leaching rate to establish the dynamic structure activity relationships between gangue alteriation and uranium dissociation, to provide scientific evidences for developing intensification techniques to recover uranium from low-grade ores.

低品位难冶铀矿资源的开发已成为缓解全球核工业资源短缺的发展趋势与研究热点，而铀矿脉石含量高、矿相环境复杂以及浸出体系下环境因素的协同效应造成的铀回收率低,以及由此带来的尾砂放射性污染严重是铀矿冶领域的核心瓶颈问题。本项目拟从酸浸过程脉石蚀变与铀解离的关系出发，运用工艺矿物学及材料学的研究方法，查明铀矿的矿相微区环境，揭示铀矿的内在惰性结构特征；以此为基础，运用湿法冶金学的相关理论，从热力学与动力学角度揭示酸浸过程脉石的蚀变特征；运用晶体结构精修的方法，在微观尺度上探讨脉石蚀变过程的环境因素对铀解离的影响机理；通过对脉石蚀变特征与铀浸出率变化规律的对比研究，阐明脉石蚀变与铀解离的动态构效关系，建立脉石蚀变过程的原位调控方法，为低品位铀矿强化提铀工艺的开发提供科学依据。

针对低品位铀矿脉石含量高、矿相环境复杂以及浸出体系下环境因素的协同效应造成的铀回收率低难题，具体分析了低品位铀矿的工艺矿物学特征，查明了铀在低品位铀矿中的赋存状况，确定了铀以难溶的四价铀形式存在以及超细粒均匀分散于脉石矿物中是导致铀难以浸出的主要原因；基于此，绘制了多元组分-铀-硫酸体系的Eh/pH图，研究了氧化强化浸铀工艺及动力学，发明了酸碱联合工艺促进脉石的蚀变以提高铀的浸出率，阐明了酸碱联合工艺中脉石的蚀变特征以及其对铀解离的影响；开展了电辅助调控浸铀工艺研究，揭示了电场对杂质离子以及脉石蚀变产物物相转化的影响机理，解决了脉石蚀变产物在浸出过程中对铀反吸附等不利因素的影响；针对低品位铀矿浸出后浸出液浓度低的问题，提出了低浓度含铀浸出液电沉积回收铀的工艺，从电沉积参数及沉积产物的稳定性等方面阐明了铀的电沉积机理，形成了低品位铀矿中铀的高效提取技术原型。