钕铁硼废料焙砂的碳热还原试验研究

Carbon-Thermal Reduction of Neodymium Iron Boron Scrap

钕铁硼废料中含有大量的铁,现有回转窑焙烧-HCl浸出预处理工艺难于将其回收利用。基于稀土氧化物和铁氧化物还原性质差异,以钕铁硼废料焙烧产物(简称为焙砂)为对象,在高温井式窑炉中开展焙砂碳热还原试验研究,考察了还原介质(焦炭、石墨和块煤)、介质粒度、还原温度、还原时间、配碳比、物料厚度等条件对铁还原率的影响。结果表明,焦炭具有较好的还原效果,在还原温度为1200℃,还原时间为4 h,配碳比为30%,物料厚度为22 mm的条件下,焙砂中铁的还原度高达88.08%,为综合回收利用钕铁硼废料中铁资源提供了理论基础和方法途径。

A large amount of iron contains in NdFeB scrap which is difficult to be recycled in the existing rotary kiln roasting-hydrochloric acid leaching pretreatment. Based on the difference reduction properties of rare earth oxide and iron oxide, calcination of neodymium iron boron scrap(abbreviated as calcine) was carried out in a high-temperature well-type kiln to investigate the effect of reducing medium(coke, graphite and lump coal), media particle size, reduction temperature, reduction time, carbon ratio, material thickness and other conditions on the iron reduction rate. The results showed that the coke has a good reduction effect. Under the conditions of reduction temperature of 1200 ℃, reduction time of 4 h, carbon ration of 30% and total mass of 50 g, the reduction degree of iron in calcine is up to 88.08%. It provides a theoretical basis and method approaches for the comprehensive recovery and utilization of iron resources of NdFeB scrap.