Novel Approach for the Simultaneous Recovery of Nd from Nd2O3-Containing Slag and the Preparation of High-Purity Si
Novel Approach for the Simultaneous Recovery of Nd from Nd2O3-Containing Slag and the Preparation of High-Purity Si
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DOI：
10.1021/acssuschemeng.1c05731
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发表时间：
2021-11
影响因子：
8.4
通讯作者：
Minpeng Lei;Yong He;Wenhui Ma;Rilin Zhang;Yun Lei
中科院分区：
文献类型：
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作者：
Minpeng Lei;Yong He;Wenhui Ma;Rilin Zhang;Yun Lei
从稀土氧化物渣中提取稀土元素是利用火法冶金方法从含稀土废物中回收稀土元素的主要挑战，特别是从废钕铁硼永磁体中回收钕。本研究提出了一种从含nd2o3渣中提取Nd的新方法。首先，以低纯度（99.2%）Si作为还原剂，从含nd2o3的炉渣中提取Nd，制备块状Si - Nd合金。块状Si-Nd合金是最终产品之一，由于其广泛的应用，达到了Nd循环利用的目的；也可以通过HCl酸浸将大块硅- nd合金进一步分离成硅粉和含nd的HCl溶液。然后，从含Nd的HCl溶液中回收Nd可采用三种方法：(1)NH3·H2O将Nd3+沉淀为NdOCl水合物沉淀物，焙烧得到高纯度的NdOCl (99.0%)；(2) HF可使Nd3+以NdF3的形式析出（97.0%）；(3)将含nd的HCl溶液完全蒸馏得到NdCl3·6H2O（98.1%）。该工艺不仅可以从含nd2o3的渣中回收Nd，而且可以将Si的纯度从99.2%提高到99.997%。
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 Nd-containing HCl solution by HCl acid leaching. Thereafter, three methods can be used to recover Nd from the Nd-containing HCl solution: (1) NH3·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) NdCl3·6H2O (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%.