城市矿山中高值稀土高效优浸回收机理的研究

Research on the Recovery Mechanism of High-efficiency and Optimal Leaching of High-value Rare Earths in Urban Mine

提出了一种利用HCl溶萃一体化加压浸出永磁废料的方法,考察了预处理方法、浸出条件对稀土浸出率及选择性的影响,研究了常用浸出剂与新型浸出剂对稀土浸出和选择性能对比,并对浸出机理加以解释。试验结果表明,经过研磨、过筛200目后,可以达到98%的氧化率。在浸出温度140℃、浸出时间8 h、浸出剂(HCl)浓度0.5 M的条件下,获得99.30%的Pr、96.19%的Nd、94.34%的Gd、16.36%的Ce以及0.94%的Fe的最佳浸出效果,氧化铁几乎全部留在残渣中。浸出结果与常用浸出剂相比表现出了更优异的浸出率以及选择性,浸出顺序符合客观规律,体现了回收率高、选择性强、环境友好、成本低廉的特点。分析了浸出机理,通过计算离子晶体分解的晶格能U以及U/x的值,对金属氧化物的溶解顺序以及溶解度差异进行了解释,为二次资源回收奠定理论基础。

This paper proposes a new method of using HCl leaching and integrated pressure leaching to extract permanent magnet waste. The effects of different treatment methods and leaching conditions on the leaching rate and selectivity were investigated, compares it with common leaching agents and new leaching agents, the leaching mechanism was explained. Research indicates that after grinding and sieving 200 meshes, an oxidation rate of 98% can be achieved. The best leaching rate is 99.30% for Pr, 96.19% for Nd, 94.34% for Gd, 6.36% for Ce and 0.94% for Fe under the conditions of leaching temperature 140 ℃, leaching time 8 h and leaching agent(HCl) concentration 0.5 M, almost all iron oxide remains in the residue. Compared with the commonly used leaching agents, the leaching results showed better leaching rate and selectivity. The leaching sequence conformed to objective laws, reflecting the characteristics of high recovery rate, strong selectivity, environmental friendliness and low cost. The leaching mechanism was analyzed, and the lattice energy U and U/x values of the decomposition of ionic crystals were calculated to explain the dissolution sequence and solubility differences of metal oxides, laying a foundation for the recovery process.