Recovery of Rare Earth Elements from Spent NdFeB by Hematite Precipitation Method
Efficient recovery of rare earths from spent NdFeB is a key way to alleviate the shortage of rare earth resources.At present,the difficulty in recovering rare earths from spent NdFeB is the deep separation of rare earths and iron.The purpose of deep separation of rare earth and Fe is achieved by removing the Fe from NdFeB hydrochloric acid leaching solution by hematite precipitation.The factors affecting the leaching rate of rare earth and the separation effect of rare earth and iron were investigated in detail.The results show that the leaching rate of REO and praseodymium-neodymium is 95.91%and 97.99%,respectively,and the leaching selectivity of iron and rare earth of acid leaching solution s(Fe2O3/REO)is 4.37%under the conditions including dosage of oxidant NaNO3 of 60 mg/g of raw material,dosage of HCl of 0.663 mL/g,leaching temperature of 180℃,leaching time of three hours,liquid solid ratio of 2.5 mL/g and stirring speed of 300 r/min.XRD and SEM results show that the main composition of the leaching residue is hematite with good filtration performance.
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