| 英文摘要 |
“Development of circular and short-processed recycled NdFeB rare earth magnet fabrication technology with NdFeB waste.” NdFeB magnet is one of key rare earth resources required in terms of demand and economic value.
With the soaring demand of high-efficient products, it is expected that the waste produced will also be on a rise. The trading restriction laid upon rare earth by various countries and geopolitical risk have fueled uncertainties, and thus making rare earth recovery from waste critical for autonomy in supplies. The project aims to establish a short-processed high efficient circular NdFeB magnet pilot production line by recycling and refabricating NdFeB magnet waste. Fabrication of recycled NdFeB magnet is made possible by producing recycled alloy powders through hydrogen decrepitation before mixing them with new alloy powders and sintering into recycled magnet blank. A pilot production line is delivered by the end of the project. Rare earth and key element analysis of 30 different wastes,under 5 categories, bearing rare earth content has been conducted. Among these electrical equipment waste, magnets found in compressor rotors of air-conditioners accounts for the highest volume, while that of voice coil motors of hard disk drives and variable frequency drives of washing machines follows. When evaluating the economic value of recycled NdFeB magnets, by recycling these wastes into magnets instead of billet steel, the value of NdFeB magnet is 20 times higher. The carbon emission of recycled NdFeB magnet blank with 45% recycled content is 92.52 kg CO2e, while a magnet blank made with 100% new material accounts for 124.73 kg CO2e of carbon emission. Thus, by adopting 45% recycled content can lower the carbon emission by 26%. The magnetic property of recycled magnet blank with a maximum 45% recycled content produced in the project is in line with that of an N48 grade magnet. By recycling tailings generated along the NdFeB waste collection, recycle and fabrication process, it is discovered that physical separation allows 94% of the nickel content to be segregated,and a total of 97% of rare earth can be used as the feeding material for hydro-metallurgy method where nickel and rare earth can be separated.
Hydro-metallurgy process further separate 99.9% of iron in the tailing and resulted in a rare earth recycling rate of 91.7% with purity of rare earth oxide reaching 99.8%.
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