Study On The Recovery Process Of Rare Earth In The Waste Of CeFeB Magnet

Based on its excellent comprehensive magnetic properties,NdFeB permanent magnet materials have been widely used in many fields,such as electronic information,automobile industry,medical equipment,energy transportation,etc.The rapid development of NdFeB permanent magnet materials consumes a lot of valuable elements such as Nd,Pr,Dy and Tb in rare earth resources,while the large backlog of high-abundance rare earth elements such as Ce causes the imbalance of rare earth utilization.In order to reduce the application of rare earth Nd,Pr and increase the high abundance of Ce in permanent magnet materials,a new type of permanent magnet material CeFeB has been prepared in recent years.This kind of magnet can not only keep good magnetic properties,but also greatly reduce the material cost of the magnet.In the production and processing of CeFeB permanent magnetic materials,the utilization rate of raw materials is only about 80%,and about 20%of waste materials are produced.Therefore,it will have great economic and social benefits to extract rare earth from CeFeB waste.This paper,three methods are used to separate and extract rare earth elements from CeFeB.The methods are oxidation roasting-hydrochloric acid high pressure leaching,sulfuric acid-selective roasting-water leaching,direct reduction-slag gold melting-slag hydrochloric acid leaching.CeFeB are oxidized and roasted,and the related elements are transformed from alloy state to oxide state.By means of SEM,XRD and other research methods,the phase transformation laws of various elements in the process of cerium iron boron roasting were analyzed and discussed.The results showed that the stable compounds were formed by four times of oxidation roasting.The phase structure of the complete oxide was Fe₂O₃,NdBO₃,GdFeO₃ and CeO₂.In the experiment of CeFeB oxidation roasting hydrochloric acid high pressure leaching,the effects of leaching temperature,time and hydrochloric acid dosage on the rare earth leaching rate were discussed.The results show that the best leaching temperature and time of CeFeB calcine are 110℃and 30min,and the rare earth leaching rate is 78.80%;the amount of hydrochloric acid is 1.15 times of the theoretical amount of hydrochloric acid is the best condition,and the rare earth leaching rate decreases gradually with the decrease of the amount of hydrochloric acid;part of Ce is found to enter the rare earth leaching solution during the high-pressure hydrochloric acid leaching experiment,which has an impact on the rare earth leaching rate.In the experiment of CeFeB sulfation selective roasting water leaching of rare earth,the effects of sulfation and selective roasting temperature on the leaching rate of rare earth were studied respectively,and the optimal sulfation selective roasting temperature was 250℃,stirring and 750℃,and the leaching rate of rare earth was 95.46%.Subsequently,the sulfation selective roasting water leaching method was used for cerium iron boron powder with different oxidation degree,the leaching rate of rare earth is ideal.In the experiment of CeFeB direct reduction slag gold melting separation hydrochloric acid leaching rare earth,the coal-based direct reduction H₂ secondary reduction was carried out on the cerium iron boron complete oxide.The slag obtained from the slag gold melting was49.28%REO-27.38%SiO₂-14.18%Al₂O₃-4.40%B₂O₃-4.67%FeO.The rare earth was extracted from the slag by hydrochloric acid high-pressure leaching method.Under the condition of leaching temperature and time of 110℃and 30min,the rare earth leaching rate was 96.93%.