硫化物除杂法回收钕铁硼废料中稀土元素的研究

Study on the Sulfide Impurity Removing Method to Recycle RE Elements from NdFeB Waste

为了回收废旧NdFeB永磁材料中的稀土元素Pr、Nd,本文采用硫化物除杂法除去废料中的Fe等杂质元素。研究了沉淀剂(NH4)2S加入前、后溶液的pH值;沉淀剂的用量以及反应时间对稀土元素回收率和纯度的影响。得到硫化物除杂法的最佳工艺参数:沉淀剂加入之后溶液pH值保持在4.8;沉淀剂(NH4)2S与原料中Fe的物质的量比为3∶1;在室温下反应过程不少于40 min。该条件下得到的的产物中稀土元素占金属总质量的97.34%,稀土Pr、Nd的回收率达到83.24%。

The sulfide impurity removing method was used for removing the impurities such as iron to recycle RE elements praseodymium and neodymium from the waste NdFeB permanent magnetic material. The influence of solution pH values both before and after adding the precipitating agent （ NH4 ） 2S on the overall recovery and purity of RE elements was investigated, as well as the dosage of precipitating agent and the reaction time. The optimized condition for removing impurity was obtained which was shown that： （1） the pH value was kept at 4.8 after adding precipitating agent; （2） the molar ratio of Fe in raw material and （NH4 ）2S was 1： 3; （3） the reaction took more than 40 min at room temperature. The overall recovery of RE and the mass percentage of rare earth in the obtained production were as high as 83.24% and 97.34%, respectively.