钕铁硼油泥稀土和铁同步浸出与分步提取研究

Research on simultaneous leaching and stepwise extraction of rare earth and iron from NdFeB sludge

钕铁硼废料是一种宝贵的稀土二次资源,对其进行综合高效回收对实现稀土可持续发展与循环利用具有重要的现实意义。以钕铁硼油泥为研究对象,通过对其进行低温氧化焙烧、盐酸浸出、草酸沉淀稀土、还原沉淀铁进行研究,提出了一种钕铁硼油泥稀土和铁同步浸出与分步提取的新工艺。结果表明,在较优焙烧温度和浸出条件下,稀土和铁浸出率分别为98.80%和98.41%,实现了同步浸出。在n(H_(2)C_(2)O_(4))∶n(RE^(3+))=3∶1、沉淀温度60℃、沉淀时间30 min条件下,稀土沉淀率达98.43%,铁共沉淀率仅为0.5%,获得了纯度为98.34%的草酸稀土产品,稀土总回收率为97.24%,实现了稀土和铁的选择性分离。在n(H_(2)C_(2)O_(4))∶n(Fe)=1.5∶1、n(Fe)∶n(Fe^(3+))=1∶1、沉淀温度30℃、沉淀时间30 min条件下,铁沉淀率为94.28%,获得了纯度为99.22%的草酸亚铁产品,铁总回收率为92.34%,达到了综合回收的目的。相对传统钕铁硼废料回收工艺,该工艺具有资源综合利用率高、固体废弃物量少等优点,为稀土二次资源综合利用提供了新思路。

NdFeB waste is a precious rare earth secondary resource,and its comprehensive and efficient recovery is of great practical significance for the sustainable development and recycling of rare earth.In this paper,with neodymium iron boron oil sludge as the research object,a new process of simultaneous leaching and step-by-step extraction of rare earth and iron from neodymium iron boron oil sludge was proposed by studying its processes of low-temperature oxidation roasting,hydrochloric acid leaching,oxalic acid precipitation of rare earth,and reduction precipitation of iron.The results show that at the optimal roasting temperature and leaching conditions,the leaching rates of rare earth and iron are respectively 98.80%and 98.41%,a synchronous leaching being achieved.Under the optimal conditions of n(H_(2)C_(2)O_(4)):n(RE^(3+))=3:1,precipitation temperature of 60℃,and precipitation time of 30min,the precipitation efficiency of rare earth elements is 98.43%,the coprecipitation efficiency of iron is only 0.5%,the oxalate rare earth products with purity of 98.34%are obtained,and the total recovery rate of rare earth is 97.24%,realizing the selective separation of rare earth and iron.Under the optimum conditions of n(H_(2)C_(2)O_(4)):n(Fe)=1.5:1,n(Fe):n(Fe^(3+))=1:1,precipitation temperature of 30℃and precipitation time of 30min,the iron precipitation rate is 94.28%,the ferrous oxalate products with purity of 99.22%is obtained,and the total iron recovery rate is 92.34%,realizing the comprehensive recycling.Compared with the traditional NdFeB waste recycling process,this process has the advantages of a high comprehensive utilization rate of resources,and less amount of solid waste,providing a new idea for the comprehensive utilization of rare earth secondary resources.