离子吸附型稀土矿电动开采技术初探

Preliminary study on electrokinetic mining technology for ion-adsorption rare earth deposits

离子吸附型稀土矿是我国的特色资源,为全世界提供了90%以上的中、重稀土。然而,现有的离子吸附型稀土矿中铵盐原地浸出开采工艺存在环境污染严重、资源利用率低、开采周期长和滑坡地质灾害频发等问题,开发新一代高效绿色的离子吸附型稀土矿提取技术是国家稀土战略的紧迫需求。本文介绍了电动开采离子吸附型稀土矿的概念设想,并对电动技术的特点进行了初步探索。通过实验室土柱实验证实了电动开采离子吸附型稀土矿的可行性,结果表明:电动法稀土采收率高,约为同等条件下传统直接浸出方法的2倍。电动开采过程中,电压梯度对稀土回收有重要影响:电压梯度升高,稀土元素浸出速率提高,但同时电解强烈,导致阴极附近稀土元素沉淀含量增加,浸出液中稀土元素含量降低。其次,电动开采过程必须添加提取剂,提取剂起到增加体系导电性和交换解吸风化壳中稀土离子的作用。最后,结合电动过程阳极由于电解产生H^(+)的特点,本文还提出了采用碳酸钙作为复合提取剂成分的设想,起到了有效缓解土壤pH值变化,并释放钙盐的作用。

Ion-adsorption rare earth deposits(IADs)are the dominant heavy REE(HREE)natural repositories discovered in South China,providing more than 95%of the global HREE demand.However,conventional mining techniques that use ammonium salts as leaching agents have problems such as serious environmental pollution,long leaching periods,and low resource utilization.Thus,green and efficient technologies that can recover REE from IARDs are urgently required.In this paper,the concept of electrokinetic mining of IARDs is introduced,and the characteristics of the electrokinetic mining technology are preliminarily explored.The feasibility of electrokinetic mining is demonstrated by simulated column experiments,and the resultant REE recovery efficiency is approximately twice that of conventional leaching techniques.In the process of electrokinetic mining,the voltage gradient has an important impact on the recovery of REE:the increase in the voltage gradient increases the leaching rate of REE,but at the same time,the electrolysis is strong,which leads to an increase in REE precipitation near the cathode and a decrease in REE in the leaching solution.Moreover,a leaching agent must be added during electrokinetic mining,which plays a role in increasing the conductivity of the system and exchanging REE ions in the weathering crust.Finally,to solve the issue of excess H^(+)generated near the anode by electrolysis,the addition of calcium carbonate into the leaching agent is also proposed,which can effectively alleviate the change in soil pH and release calcium salt.We suggest that the electrokinetic mining technology can recover REE from IARDs.