离子型稀土原地浸矿场清水淋洗室内模拟试验研究

Laboratory simulation test research on in-situ leaching field of ionic rare earths under water leaching

离子型稀土开采以硫酸铵为浸矿剂进行原地浸矿,大量的浸矿剂通过离子交换作用置换出稀土元素离子后,高浓度的氨氮则留存于稀土矿层土壤中。以广东某稀土矿区为研究对象,采用土柱模拟试验,对浸矿后的土柱体进行清水淋洗,研究了不同pH值浸矿剂、不同清水淋洗工艺特征下氨氮的解析规律。结果表明,以出水氨氮浓度达到《稀土工业污染物排放标准》(GB26451—2011)且变化平稳为淋洗终点,所用淋洗水量与矿样体积比在2.1~2.3倍,氨氮淋出率大于62%,硫酸盐淋出率大于58%,淋洗初期淋洗液氨氮浓度大幅下降,而后随着淋洗水量增加缓慢下降。研究结论为离子型稀土矿区土壤氨氮污染控制奠定一定理论基础。

In the ionic rare earth mining,ammonium sulfate is used as a leaching agent for in-situ leaching.After a large amount of leaching agent replaces the rare earth element ions through ion exchange,the ammonia nitrogen of high concentration remains in the rare earth mineral layer soil.In this paper,taking a rare earth mining area in Guangdong as the research object,after leaching with water on the soil column that completely leached,in condition of using different leaching agents of pH values and different water leaching process characteristics,the desorption rules of ammonia nitrogen was studied.The results showed that,taking the time when the concentration of ammonia nitrogen stable compliance with the"Rare Earth Industry Pollutant Discharge Standard"(GB26451—2011)as the leaching end point,The ratio of the leaching water volume to the volume of the rare earth ore was between 2.1 and 2.3 times,and the leaching removal rate of ammonia nitrogen was larger than 62%,the leaching removal rate of sulfate was larger than 58%,the ammonia nitrogen concentration of the leaching liquid at the initial stage of leaching dropped significantly,and then slowly decreased as the amount of leaching water increases.The research conclusions can lay a theoretical foundation for soil ammonia nitrogen pollution control in ion-type rare earth mining areas.