Novel Approach for the Simultaneous Recovery of Nd from Nd2O3-Containing Slag and the Preparation of High-Purity Si

The extraction of rare earth elements (REEs) from rare earth oxide slag is a major challenge of recycling REEs from REE- containing wastes using pyrometallurgical approaches, especially the recycling of Nd from spent NdFeB permanent magnets. In this study, a novel and effective approach is proposed for extracting Nd from Nd2O3-containing slag. First, low-purity Si (99.2%) was used as a reductant to extract Nd from Nd2O3-containing slag to prepare a bulk Si-Nd alloy. The bulk Si-Nd alloy represents one of the final products and achieves the purpose of Nd recycling because of its wide applications; alternatively, the bulk Si-Nd alloy can be further separated into Si powder and Ndcontaining HCl solution by HCl acid leaching. Thereafter, three methods can be used to recover Nd from the Nd-containing HCl solution: (1) NH3 center dot H2O can be used to precipitate Nd3+ as NdOCl hydrate sediment, which is roasted to obtain high-purity NdOCl (99.0%); (2) HF can be used to precipitate Nd3+ as NdF3 (97.0%); or (3) NdCl3 center dot 6H(2)O (98.1%) can be obtained after completely distilling the Nd-containing HCl solution. This new technology not only permits the recovery of Nd from the Nd2O3-containing slag but also increases the purity of Si from 99.2 to 99.997%.

Automated summary

A novel and effective approach for extracting Nd from Nd2O3-containing slag using low-purity Si as a reductant is proposed in this study. Three methods are used to recover Nd from the Nd-containing HCl solution, resulting in increased purity of silicon from 99.2% to 99.997%.