CO2+O2地浸采铀脉石矿物与浸矿剂相互作用研究

在CO2+O2地浸采铀应用过程中，浸矿剂不仅与载铀物质发生反应，亦与脉石矿物发生反应。为探索砂岩型铀矿主要脉石矿物与浸矿剂的相互作用，在中性条件下（pH分别为6.20、6.40、6.60、6.80和7.00）对脉石单矿物及天然铀矿石进行高压釜静态浸出试验，对比浸出溶液中各种离子浓度变化和反应后渣样的形貌变化特征。发现：1）方解石溶解可产生HCO3-和Ca2+，HCO3-升高能加速铀浸出，而Ca2+浓度升高会增加石膏和方解石沉淀风险；2）黄铁矿与浸矿剂反应易产生H+，阻碍CO2与水反应生成HCO3-，不利于铀浸出，但当黄铁矿与方解石同时存在，黄铁矿同浸矿剂相互作用会加速方解石的溶解，故对富方解石的矿石来说，黄铁矿的存在有利于铀的浸出；3）钾长石溶解可形成黏土矿物，对溶出的铀酰离子有一定的吸附性；此外，黏土颗粒细小，在地浸工业应用过程中增加黏土物理堵塞的风险；4）高岭石在浸出过程中会释放其所吸附的其他离子，同时吸附铀酰。渣样矿物学分析结果显示，各种矿物在浸出过程中均发生差异性溶解，其中方解石溶解最明显，表面逐步被侵蚀粗糙，钾长石表面溶蚀微弱；黄铁矿表面随着浸矿剂的作用逐步覆盖一层铁氧化物或者铁的氢氧化物；高岭石的微观形貌变化不明显。

Interaction between Gangue Mineral and Leaching Agent in CO2+O2 In-situ Leaching

In the process of uranium mining by CO2+O2 in-situ leaching, leaching agent reacts not only with uranium-carrying materials but also with gangue minerals. In order to study the interaction between main gangue minerals of sandstone type uranium deposit and leaching agent, the static leaching tests of gangue single minerals and natural uranium ore were carried out under neutral conditions (pH values of 6.20, 6.40, 6.60, 6.80 and 7.00). The changes of ions concentration in leaching solution and morphologies of the slag samples after reaction were compared. The results show that: 1) The dissolution of calcite can produce HCO3- and Ca2+. The increase of HCO3- can accelerate the leaching of uranium, while the increase of Ca2+ concentration will increase the risk of gypsum and calcite precipitation. 2) The reaction between pyrite and leaching agent is easy to produce H+, which hinders the reaction between CO2 and water to form HCO3-, which is not conducive to uranium leaching. However, when pyrite and calcite exist simultaneously, the interaction between pyrite and leaching agent will accelerate the dissolution of calcite. Therefore, for calcite rich ores, the presence of pyrite is conducive to uranium leaching. 3) The dissolution of potassium feldspar can form clay minerals, which have certain adsorbability to the dissolved uranyl ions. Furthermore, the clay particles are small, which increases the risk of physical clogging of clay in the process of in-situ leaching industrial application. 4) During the leaching process, kaolinite will release other ions adsorbed by it and adsorb uranyl at the same time. The results of slag mineralogical analysis show that all minerals dissolved differently during the leaching process, among which calcite dissolved most obviously, the surface is gradually eroded rough, and feldspar surface dissolved weakly. The surface of pyrite is gradually covered with a layer of iron oxides or iron hydroxides with the action of leaching agent. The morphology of kaolinite does not change obviously.