Energy efficient process for recovery of rare earths from spent NdFeB magnet by chlorination roasting and water leaching

Kumari, Aarti; Raj, Raman; Randhawa, N S; Sahu, Sushanta Kumar

doi:10.1016/j.hydromet.2021.105581

Cited by 43 publications

(20 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Melting of a relatively large batch of magnetic slag material as a consumable anode or by addition to a molten bath [16] Melt spinning Remelting of magnet scraps by induction heating and conversion of the material into a master alloy [27] Treatment with liquid metals Selective extraction of neodymium from magnet scrap with liquid magnesium or molten silver [28][29][30] Chlorination roasting REE extraction from neodymium magnet sludge by chlorination with FeCl 2 [31][32][33] Sulfation roasting REE extraction by suitable selective roasting and water leaching treatment after completely transforming powdered samples into sulfate mixture [34] Oxidation roasting Oxidation of NdFeB magnets at a high temperature followed by selective leaching. Before roasting, the magnets are demagnetized, crushed and grinded [35][36][37] Hydrogen decrepitation (HD) process and re-sintering NdFeB magnet scrap recycling by processing it in hydrogen, then milling, aligning, pressing and re-sintering it [38][39][40] Although different methods for NdFeB magnet recycling have been reported in the literature, only one piece of technology has been applied in practice by the Urban Mining Technology Company [40].…”

Section: Hydrometallurgymentioning

confidence: 99%

“…The grinding step, although valuable, as it increases the surface area of particles, is also the most energy consuming step in the recycling process [41,42]. Additionally, the roasting step used in many methods described in the literature [31][32][33][34][35][36][37] consumes a lot of energy [33]. Therefore, the grinding and roasting operations negatively affect the economics of the recycling process by increasing its costs.…”

Section: Hydrometallurgymentioning

confidence: 99%

See 1 more Smart Citation

Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

et al. 2021

View full text Add to dashboard Cite

A simplified approach for rare earth elements leaching from NdFeB (neodymium-iron-boron) magnets was investigated. The possibility of simplifying the magnet recycling process by excluding grinding, milling and oxidative roasting unit operations was studied. Attempts to skip the demagnetization step were also conducted by using whole, non-demagnetized magnets in the leaching process. The presented experiments were conducted to optimize the operating conditions with respect to the leaching agent and its concentration, leaching time, leaching temperature and the form of the feed material. The use of hydrochloric and sulfuric acids as the leaching agents allowed selective leaching of NdFeB magnets to be achieved while leaving nickel, which is covering the magnets, in a solid state. The application of higher leaching temperatures (40 and 60 °C for sulfuric acid and 40 °C for hydrochloric acid) allowed us to shorten the leaching times. When using broken demagnetized magnets as the feed material, the resulting rare earth ion concentrations in the obtained solutions were significantly higher compared to using whole, non-demagnetized magnets.

show abstract

Section: Hydrometallurgymentioning

confidence: 99%

Section: Hydrometallurgymentioning

confidence: 99%

Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In the last century, the extraction of Ti from titanium ore by chlorination method has been industrialized [23]. Chlorinating agent plays an important role in chlorination metallurgy, which is divided into solid (NaCl, KCl, CaCl 2 , AlCl 3 , FeCl 2 , FeCl 3 , MgCl 2 , NH 4 Cl, NaClO, NaClO 3 ) and gas (Cl 2 , HCl, CCl 4 ) [24][25][26][27][28][29]. Compared with gaseous chlorinating agents, the solid chlorinating agents are easier to handle and more environmentally friendly.…”

Section: Introductionmentioning

confidence: 99%

Extraction of the Rare Element Vanadium from Vanadium-Containing Materials by Chlorination Method: A Critical Review

Liu

Xue

Wang

2021

Metals

View full text Add to dashboard Cite

Vanadium as a rare element has a wide range of applications in iron and steel production, vanadium flow batteries, catalysts, etc. In 2018, the world’s total vanadium output calculated in the form of metal vanadium was 91,844 t. The raw materials for the production of vanadium products mainly include vanadium-titanium magnetite, vanadium slag, stone coal, petroleum coke, fly ash, and spent catalysts, etc. Chlorinated metallurgy has a wide range of applications in the treatment of ore, slag, solid wastes, etc. Chlorinating agent plays an important role in chlorination metallurgy, which is divided into solid (NaCl, KCl, CaCl2, AlCl3, FeCl2, FeCl3, MgCl2, NH4Cl, NaClO, and NaClO3) and gas (Cl2, HCl, and CCl4). The chlorination of vanadium oxides (V2O3 and V2O5) by different chlorinating agents was investigated from the thermodynamics. Meanwhile, this paper summarizes the research progress of chlorination in the treatment of vanadium-containing materials. This paper has important reference significance for further adopting the chlorination method to treat vanadium-containing raw materials.

show abstract

“…Spent NdFeB permanent magnets are considered secondary resources for the recovery of REEs. Approximately, 23% of REEs (mainly neodymium, praseodymium, and dysprosium) are used to prepare NdFeB permanent magnets . Although China has the world’s largest reserves of REEs, the environmental problems associated with the hazardous wastes that are discharged after REE extraction and the costs of treating the hazardous residues cannot be ignored, as the hazardous residues contain some radioactive elements derived from REE ores.…”

Section: Introductionmentioning

confidence: 99%

“…Approximately, 23% of REEs (mainly neodymium, praseodymium, and dysprosium) are used to prepare NdFeB permanent magnets. 6 Although China has the world's largest reserves of REEs, the environmental problems associated with the hazardous wastes that are discharged after REE extraction and the costs of treating the hazardous residues cannot be ignored, as the hazardous residues contain some radioactive elements derived from REE ores. The recovery of REEs from REE-containing wastes such as NdFeB magnets could aid the sustainable development of REE resources and benefit the environment.…”

Section: ■ Introductionmentioning

confidence: 99%

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

Lei

et al. 2021

ACS Sustainable Chem. Eng.

View full text Add to dashboard Cite

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 Nd 2 O 3 -containing slag. First, low-purity Si (99.2%) was used as a reductant to extract Nd from Nd 2 O 3containing 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) NH 3 •H 2 O can be used to precipitate Nd 3+ as NdOCl hydrate sediment, which is roasted to obtain high-purity NdOCl (99.0%); (2) HF can be used to precipitate Nd 3+ as NdF 3 (97.0%); or (3) NdCl 3 •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 Nd 2 O 3 -containing slag but also increases the purity of Si from 99.2 to 99.997%.

show abstract

Energy efficient process for recovery of rare earths from spent NdFeB magnet by chlorination roasting and water leaching

Cited by 43 publications

References 51 publications

Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

Extraction of the Rare Element Vanadium from Vanadium-Containing Materials by Chlorination Method: A Critical Review

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

Contact Info

Product

Resources

About

Energy efficient process for recovery of rare earths from spent NdFeB magnet by chlorination roasting and water leaching

Cited by 43 publications

References 51 publications

Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

Leaching of Rare Earth Elements from NdFeB Magnets without Mechanical Pretreatment by Sulfuric (H2SO4) and Hydrochloric (HCl) Acids

Extraction of the Rare Element Vanadium from Vanadium-Containing Materials by Chlorination Method: A Critical Review

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

Contact Info

Product

Resources

About

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