Recycling of SmCo 5  magnets by HD process

Eldosouky, Anas; Škulj, Irena

doi:10.1016/j.jmmm.2018.01.064

Cited by 16 publications

(12 citation statements)

References 11 publications

(14 reference statements)

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“…We posited (post-hoc) that the virgin raw material is mechanically different from the recycled raw material due to the process they each undergo in their production. While the recycled material is obtained from the decrepitation of hard-sintered magnets undergoing mechanical agitation under high hydrogen pressure [ 29 ], the virgin material is instead a product of jet milling. Jet milling involves high-energy comminution to fine particles in the size range of tens of microns.…”

Section: Resultsmentioning

confidence: 99%

“…Our material choice is dictated by the naturally large saturation magnetization available in Fe: M s ≈ 215 Am 2 /kg and the high intrinsic anisotropy of SmCo 5 : K 1 ≈ 17.2 MJ/m 3 . The SmCo 5 , (production supply; MAGNETI Ljubljana d.d., Slovenia) used was either virgin (jet-milled particles <40 μm), or recycled from production magnets by hydrogen decrepitation (coarse particles ~200 μm) [ 29 ]. The Fe used was produced by inert gas atomization (size <40 μm; Högnäs AB, Sweden).…”

Section: Methodsmentioning

confidence: 99%

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Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

et al. 2020

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Nanostructured alloy powders of SmCo5 + 10 wt% Fe obtained using recycled material were studied for the first time. The SmCo5 precursor was obtained from commercial magnets recycled by hydrogen decrepitation. The results were compared with identically processed samples obtained using virgin SmCo5 raw material. The samples were synthesized by dry high-energy ball-milling and subsequent heat treatment. Robust soft/hard exchange coupling was observed—with large coercivity, which is essential for commercial permanent magnets. The obtained energy products for the recycled material fall between 80% and 95% of those obtained when using virgin SmCo5, depending on milling and annealing times. These results further offer viability of recycling and sustainability in production. These powders and processes are therefore candidates for the next generation of specialized and nanostructured exchange-coupled bulk industrial magnets.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

et al. 2020

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“…Screening tests were carried out on Sm-Co PMs, on which we are working with HD. 5 A comparison was planned among the ve 1 vol% bromine solutions in DMF, EG, EtOAc, EtOH and MeOAc, a solution of 1 vol% bromine in water and a solution of 2 M HNO 3 , which is a common oxidizing lixiviant in industry. However, bromine is poorly soluble in water at room temperature and this solution could not be prepared.…”

Section: Dissolution Experimentsmentioning

confidence: 99%

“…Two processes, hydrogen decrepitation (HD) or hydrogen-decomposition-desorption-recombination (HDDR) have already been successfully applied at pilot scale and could be commercially feasible, especially for Nd-Fe-B magnets. [5][6][7][8][9][10][11][12] However, the magnet coating partly ends up as a contamination in the decrepitated powder, dilutes the magnet alloy and deteriorates the magnetic properties of the recycled PM. 9,13 Different materials are being used for coatings, depending on the application of the PMs, for instance epoxy resins, zinc, nickel-copper, and nickel-copper-nickel.…”

Section: Introductionmentioning

confidence: 99%

“…The samples of SmCo5 or Sm 2 Co 17 in 2 M HNO 3 were stirred at room temperature (RT) at 500 rpm for 210 min and samples were taken at 30, 60, 90 and 210 minutes. Metal-coated Nd-Fe-B magnets were also treated with 10 mL of the best performing bromine solutions at room temperature for 60 min with samples taken at 5, 10, 20, 30, 45 and 60 min.The solvents where chosen for their different polarity.…”

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Removal of metallic coatings from rare-earth permanent magnets by solutions of bromine in organic solvents

et al. 2019

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Electrochemical routes for environmentally friendly recycling of rare-earth-based (Sm–Co) permanent magnets

Khoshima

Karajic

et al. 2022

J Appl Electrochem

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The consumption of critical raw materials, especially those in permanent magnets of Nd–Fe–B and Sm–Co-type, has significantly grown in the past decade. With predictions on further electrification growing exponentially the demand for these materials will even increase. This implies that efforts in assuring sustainability must involve recycling from secondary resources. In recent years the electrochemical approaches in recycling have been extensively investigated and applied owing to their advantages of high efficiency and selectivity, easy operation, low energy consumption, and environmental friendliness. In this paper, we investigate the Sm2(Co,Fe,Cu,Zr)17 permanent magnet leaching process using the anodic oxidation to be paired with the metal deposition on the cathode. Linear sweep voltammetry was performed from − 0.15 to 1 V versus Pt quasi reference electrode that indicated current peaks that would correspond to some preferential leaching of the crystal phases contained in the magnet. The latter was confirmed using the SEM/EDXS analysis. The continuous leaching of the Sm2(Co,Fe,Cu,Zr)17 magnet was performed at a direct current density of 2, 4 and 8 mA cm−2 at the time period of 0–240, 240–480 and 480–720 min, respectively. The ICP-MS results confirmed the leaching of all the metals from the original Sm2(Co,Fe,Cu,Zr)17 permanent magnet. The concentration of Sm3+, Cu2+, Fe2+ and Zr2+ increases linearly along with the leaching time. Reversely the concentration of Co2+ decreases linearly due to its consumption by electrodeposition of Co, Fe and Cu on the cathode. The presented paired electrochemical process could serve as a starting point for the recycling and recovery of critical raw materials without any acid usage and waste generation. Graphical abstract

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Recycling of SmCo 5 magnets by HD process

Cited by 16 publications

References 11 publications

Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

Magnetic Properties of SmCo5 + 10 wt% Fe Exchange-Coupled Nanocomposites Produced from Recycled SmCo5

Removal of metallic coatings from rare-earth permanent magnets by solutions of bromine in organic solvents

Electrochemical routes for environmentally friendly recycling of rare-earth-based (Sm–Co) permanent magnets

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