Effective rare earth extraction from Nd-Fe-B waste by liquid cuprum extraction method

Abstract

Recovery of rare earth (RE) elements from Nd-Fe-B waste is one of the ways to solve the problem of so-called RE-crisis. An alternative approach of extracting RE elements from Nd-Fe-B waste by molten Cu extraction based on liquid-solid diffusion and reaction is reported in this paper. The extraction process, product microstructure and extraction efficiency were systematically studied. The results show that the extraction rate of RE at 1200 °C is about 20% higher than that at 1100 °C. The enhanced extraction efficiency at 1200 °C results from the fact that the liquid Fe and Fe2B are not co-soluble with Cu. Reducing the mass ratio of Cu to waste and the size of the waste scraps is also beneficial to enhancing the separation of RE and Fe elements. In addition, the extraction time should be well controlled, for example, less than 2 h at 1100 °C, in order to avoid the increased Fe content in the extracted product. Based on optimized process, the RE elements can be almost fully extracted from the waste. This work thus provides an effective method to recover the RE elements.