不同地浸采铀工艺主要元素迁移强度与饱和状态研究

Research on Migration Intensity and Saturation State of Main Element in Different In-situ Leaching of Uranium Processes

针对新疆某铀矿床矿石碳酸钙含量高的特点,为掌握酸法、碱法及CO 2+O 2中性3种原地浸出采铀工艺条件下主要元素的迁移强度和矿物饱和状态,开展了3种工艺条件下的室内及现场浸铀对比试验,并应用水文地球化学原理对碳酸钙与硫酸钙的饱和指数进行了计算。结果表明,酸法浸出时U、Ca、Mg、Al、Fe的迁移强度高于碱法及中性时的;碱法与中性浸出时,U的迁移强度基本相同,中性浸出Ca、Mg的迁移强度大于碱法,两种工艺下Fe、Al的迁移强度均弱于U、Ca、Mg。中性浸出时,硫酸钙始终未发生沉淀,pH值控制在6.6以下时,碳酸钙不会发生沉淀;碱法浸出时,碳酸钙不可避免地会发生沉淀;酸法浸出时,硫酸钙不可避免地会发生沉淀。对于该矿床,CO 2+O 2中性浸出工艺为首选,控制pH值在6.6以下可有效避免碳酸钙沉淀,确保铀正常浸出。

According to the characteristics of high calcium carbonate content of ore at a uranium deposit in Xinjiang,in order to master the migration intensity of main elements and mineral saturation state using acid leaching,alkali leaching and CO 2+O 2 neutral in-situ leaching(ISL)processes,three different leaching tests were carried out indoors and outdoors.The hydrogeochemical principles were used to calculate saturation index of calcium carbonate and calcium sulfate.The results show that the migration intensity of U,Ca,Mg,Al and Fe using acid ISL is stronger than using alkali and neutral ISL.The migration intensity of U using alkali ISL is basically the same as using neutral ISL.The migration intensity of Ca and Mg using neutral ISL is stronger than using alkali.The alkali and neutral ISL migration of Fe and Al are weaker than U,Ca and Mg.During neutral leaching,calcium sulfate never precipitates,when the pH value is controlled below 6.6,calcium carbonate will not precipitate.Calcium carbonate precipitation is inevitable in alikaline leaching,and calcium sulfate precipitation is inevitable in acid leaching.For this deposit,CO 2+O 2 neutral leaching process is the first selection.Controlling the pH value below 6.6 can effectively avoid the precipitation of calcium carbonate and ensure the normal leaching of uranium.