In recent years, under the background of global low-carbon development, the production of NdFeB magnets has increased dramatically. With the end of magnet life, a large number of discarded products will be produced in the future. At the same time, 6–73% of industrial waste will be produced in the manufacturing process of magnets. The rare earth content (about 30 wt.%) of these magnet scraps is generally higher than that of raw ore, and the recovery of rare earth elements from them helps to stabilize the global rare earth supply chain. In addition, NdFeB scrap contains about 70 wt.% of iron, which is currently unable to be utilized with high added value. If iron can be recycled based on recycling rare earth elements, it is expected to realize the full component recycling of NdFeB waste and reduce the full life cycle environmental load of NdFeB products. This paper summarizes the properties, recycling potential, and existing recycling technologies of NdFeB waste, and it summarizes the principles, advantages, and disadvantages of various recycling methods, such as direct reuse, pyrometallurgy, hydrometallurgy, and electrochemistry. Among them, the electrochemical recovery method was emphatically reviewed as a newly proposed method. On this basis, the future development direction of NdFeB waste recycling has been prospected, and the research idea of avoiding the shortcomings of various recycling methods through the combined process is proposed. It is proposed that low environmental hazards, low energy consumption, and a closed-loop process are the main goals to be achieved in the recycling process.

The lead–zinc ore is a typical low-grade complex polymetallic sulphide ore. Its typical mineralogy is characterized by a high content of cryptocrystalline graphite, low content of lead, zinc, and copper, and fine grain size. However, the aggregation size of sulfide mineral aggregations is coarse, and the symbiotic relationship is relatively simple. Conventional process treatment requires the fine grinding of ore into mineral monomer dissociations followed by preferential flotation, but this method has a poor sorting index and high production cost. In this paper, the grain size of the sulfide mineral aggregates determined by mineralogical studies is used to determine the fineness of the grinding, so that the liberation degree of the sulfide ore in the coarse grinding product reaches 70%, and each flotation process is used to collect rough concentrate. In the first step of flotation, the carbon in lead–zinc sulfide ore was removed by adding #2 oil to the flotation tank at a dosage of 40 g/t. In the second flotation process, the pH was adjusted to 7.2, the dosage of isopropyl xanthate was 20 g/t, the dosage of #2 oil was 30 g/t; the flotation reagent in the third step was isopropyl xanthate, and the dosage was 7.5 g/t, with a #2 oil of 15 g/t. Each flotation process concentrate is collected. Finally, the grades of lead and zinc in the final concentrate were 1.6% and 5.71%, respectively. In addition, the recoveries of lead and zinc were 91.78% and 92.07%, respectively. The yield of tailings was 50.6%. By the flotation of sulfide aggregates, a large number of gangues are avoided to participate in fine grinding, which helps to reduce the energy consumption of the mill.

With the increasing consumption of NdFeB, it becomes an important secondary resource and its recycle is getting more and more attention. In this paper, a combined electrochemical-hydrometallurgical process is proposed to recover Nd and Fe from NdFeB permanent magnet Spent, and the feasibility of electrolytic separation is demonstrated by electrochemical analysis (CV). In the aqueous system, Nd3+ shifts the reduction peak potential of Fe2+ negatively and the electrodeposition of Fe2+ can still proceed. During electrolysis process, spent NdFeB was used as the anode, and titanium plate was used as the cathode. NdFeB is oxidized and decomposed to Nd3+ and Fe2+ at the anode, and Fe2+ is electrodeposited to iron at the cathode. The effect of various variables including electrolyte concentration, pH, temperature and current density on the degree of neodymium enrichment in the electrolyte, cathode product purity and cathode current efficiency were investigated. 2-Ethylhexyl phosphate 2-ethylhexyl phosphate (P507) was selected as the extractant, and Nd3+ and Fe2+ in the electrolyte was extracted by two-stage staggered flow. The loaded organic phase was reverse extracted by H2C2O4 and H2SO4, and Nd3+ was selectively precipitated as Nd2(C2O4)3·10H2O, while Fe2+ remained in the reverse extract solution. The strip liquor and the raffinate was reused after Fe2+ replenishment, forming a closed-loop process without waste discharge, consuming only electricity and FeSO4, with no negative impact on the environment.