螯合剂浸出废弃荧光粉中稀土元素的反应特性与微波强化

In view of the high concentration of acid and alkali in the chemical leaching process of rare earth elements from waste phosphors, it is easy to cause secondary pollution and equipment corrosion. From the perspective of effective use of resources and reduction of environmental pollution, this topic makes full use of the reaction promoting effect obtained by the high temperature and high pressure conditions that creatived by microwave radiation, and the and the excellent affinity of the chelator for the rare earth element, using the chelator as the leaching agent, the new technology that chelator-induced recovery of rare earths from waste phosphors with the aid of microwave irradiation is proposed. Firstly, the leaching performance of chelator was studied, and the relationship between the structure of chelator and leaching performance was investigated. The mechanism of rare earth element conversion during leaching of chelator was studied. The decomposition characteristics, phase change and electrochemical behavior of waste phosphor during leaching were explored. Studying the influence of thermal stress of microwave radiation on the interface and microstructure of phosphor particles, revealing the dissociation mechanism of phosphor particles under the action of "super hot spot" in microwave field; the dissolution characteristics of phosphor particles and the dissolution rules of each component under microwave irradiation were clarified, and the characteristics of microwave enhanced leaching behavior were elucidated. It will lays a theoretical foundation for the green and high-efficiency leaching of rare earth elements in waste phosphors, and also provides a new technical reference for the recovery and recycling of rare earth elements in waste phosphors.

针对目前废弃荧光粉中稀土元素化学浸出工艺存在的酸碱浓度高、用量大，易造成二次污染和设备腐蚀等问题，从资源有效利用、减少环境污染的角度出发，本课题充分利用微波辐射引起的高温和高压条件获得的反应促进效果，以及螯合剂对稀土元素的优异亲和力，采用螯合剂作为浸出剂，提出“螯合剂诱导+微波辐射强化废弃荧光粉中稀土元素的浸出”新工艺。首先研究螯合剂的浸出性能，考察螯合剂的结构与浸出性能的关系；研究螯合剂浸出过程稀土元素转化机制，探索浸出过程中废弃荧光粉的分解特性、物相变化、电化学行为，阐明螯合剂浸出废弃荧光粉中稀土元素的反应规律；研究微波辐射的热应力作用对荧光粉颗粒界面和微观结构的影响；查明微波辐射下荧光粉颗粒溶解特性和各组分溶出规律，阐明微波强化浸出行为特征。实现废弃荧光粉中稀土元素的绿色、高效浸出，为废弃荧光粉中稀土元素的回收提供新的理论参考。

针对目前废弃荧光粉中稀土元素化学浸出工艺存在的酸碱浓度高、用量大，易造成二次污染和设备腐蚀等问题，本课题充分利用微波辐射引起的高温和高压条件获得的反应促进效果，以及螯合剂对稀土元素的优异亲和力，采用螯合剂作为浸出剂，提出了“微波辐射+螯合剂诱导强化废弃荧光粉中稀土元素的浸出”新工艺。研究结果表明螯合剂对稀有金属具有优异提取性能，可实现废弃荧光粉中稀土元素的绿色浸出。通过条件试验对比了乙二胺四乙酸（EDTA）、乙二胺二琥珀酸、甲基甘氨酸二乙酸或3-羟基-2,20-亚氨基二琥珀酸对废弃荧光粉中稀土元素的浸出效果，在室温下、pH=5时， 5mmol/L的EDTA溶液中稀土元素的浸出率最高（Ce，8.68%；Eu，40.26%； Tb，5.32%；Y，45.36%）。温度升高（110℃）可明显提高Eu和 Y浸出率。微波可明显提高反应过程的反应速率，浸出过程动力学模型拟合表明，与常规加热方式相比，微波浸出过程可明显降低浸出过程的反应活化能和反应级数，加快反应的进行。