CO2+O2地浸采铀中CaCO3沉淀堵塞条件模拟

CO2+O2地浸工艺是我国第三代铀矿采冶技术，地浸过程中溶浸液与含矿层矿物反应后，在将铀从矿石中浸出的同时，由于地下水矿化度增高又会产生化学沉淀，导致含矿层堵塞。CaCO3沉淀是CO2+O2地浸采铀过程中含矿层堵塞的重要原因。根据内蒙古纳岭沟铀矿CO2+O2浸铀过程中浸出液化学成分数据，通过水文地球化学模拟，对含矿层堵塞的水文地球化学条件进行了系统研究。结果表明，CaCO3沉淀是造成CO2+O2地浸中含矿层化学堵塞的重要原因。当溶浸液pH>6.5时，CaCO3将发生沉淀，溶浸液的pH、HCO3-浓度、Ca2+浓度是影响CaCO3沉淀的主要因素，过高的pH与HCO3-浓度、Ca2+浓度都会造成CaCO3沉淀的产生。根据模拟结果获得了不产生CaCO3沉淀条件下pH、HCO3-浓度、Ca2+浓度三者之间的关系，并由此认为，维持溶浸液较低的Ca2+浓度与较低的pH是预防与缓解CaCO3沉淀堵塞的有效途径。

Simulation on CaCO3 Precipitation and Blockage Conditions in CO2+O2 In-situ Leaching of Uranium

CO2+O2 in-situ leaching of uranium process is the third generation of uranium mining and metallurgical technology in China, during the in-situ leaching process, the dissolved liquid reacts with the ore-bearing seam minerals to extract uranium from the ore, at the same time, chemical precipitation will occur due to the increase of groundwater mineralization, resulting in ore-bearing seam blockage. CaCO3 precipitation is an important cause of ore layer blockage during in uranium leaching in CO2+O2. In order to explore the conditions of CaCO3 precipitation and blockage, hydrogeochemical conditions of ore-bearing seam blockage were systematically studied through hydrogeochemical simulation, according to the chemical composition data of CO2+O2 uranium leaching solution from uranium ore in Nalinggou in Inner Mongolia The results show that CaCO3 precipitation is the important cause of chemical blockage of ore-bearing seams in CO2+O2 in-situ leaching of uranium. When the pH value of the leaching solution 6.5 above, CaCO3 will precipitate, the pH value, concentration of HCO3- and Ca2+ of the immersion solution are the main factors affecting CaCO3 precipitation, and excessive pH value and concentration of HCO3- and Ca2+ will cause the production of CaCO3 precipitation. According to the simulation results, the relationship between pH value, and concentrations of HCO3- and Ca2+ without CaCO3 precipitation is obtained, and it is concluded that maintaining the lower Ca2+ concentration and lower pH value of the leaching solution is an effective way to prevent and alleviate CaCO3 precipitation blockage.