e-ISSN: 2807-2820 Natural Sciences Engineering Technology Journal [NASET Journa.
https://nasetjournal.
A Solvent-Free.
Mechanochemical Process for Sustainable Recycling of Neodymium and Dysprosium from E-Waste Magnets Khairul Raziqin 1.
Arya Ganendra2.
Abdul Malik3* Department of Chemical Engineering.
DeNovo Engineering Laboratory.
Bandung.
Indonesia Department of Literacy.
Emerald Language Institute.
Balikpapan.
Indonesia Department of Economics Education.
SSRI Research Institute.
Batam.
Indonesia
ARTIC LE
INFO
Keywords:
Mechanochemistry Neodymium Magnets Rare Earth Elements E-Waste Recycling Sustainable Metallurgy *Corresp ondi ng author:
Abdul Malik E-mail address:
abdulmalik@enigma.
All authors have reviewed and approved th e Anal version of the manuscript.
https://doi.
org/10.
37275/nasetjournal.
A B S T R A C T
The escalating demand for rare earth elements (REE.
, particularly neodymium (N.
and dysprosium (D.
, for high-performance NdFeB magnets, has created significant supply chain vulnerabilities and environmental concerns associated with primary mining.
End-of-life electronic waste .
-wast.
represents a substantial secondary resource for these critical materials.
This study introduces a novel, environmentally benign approach for recovering Nd and Dy from waste NdFeB magnets.
solvent-free mechanochemical process was developed and optimized.
Waste NdFeB magnet powder, sourced from discarded hard disk drives collected in Indonesia, was co-milled with ammonium chloride (NHCEC.
in a high-energy planetary ball mill.
The influence of key process parameters, including milling time .
-360 mi.
, milling speed .
-500 rp.
, and the mass ratio of NHCECl to magnet powder .
:1 to 5:.
, on the extraction efficiency of Nd and Dy was systematically investigated.
The structural and morphologica l transformations were characterized using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) with Energy-Dispersive X-ray Spectroscopy (EDS).
Metal recovery was quantified via subsequent wa ter leaching and analysis by Inductively Coupled Plasma -Optical Emission Spectrometry (ICP-OES).
The mechanochemical treatment successfully converted the insoluble rare earth phases within the magnet matrix into water-soluble rare earth chlorides.
Under optimal conditionsAia milling time of 240 minutes, a speed of 400 rpm, and a NHCECl-to-magnet mass ratio of 3:1Aithe process achieved remarkable extraction efficiencies of 98.
6% for Nd 2% for Dy.
XRD analysis confirmed the transformation of the NdCCFeCACEB phase into REE chlorides, alongside iron and iron boride phases.
SEM imaging revealed a significant reduction in particle size and the formation of agglomerated composite particles, crucial for the solid-state In conclusion, this study demonstrates that solvent-free mechanochemistry is a highly effective and sustainable alternative to conventional hydrometallurgical and pyrometallurgical recycling methods.
The process operates at ambient temperature, eliminates the need for corrosive acids and organic solvents, and exhibits high recovery rates, presenting a viable pathway towards a circular economy for critical rare earth elements from e-waste.
Introduction renewable energy infrastructure.
The REE group.
IThe 21st century is defined by technological comprising the 15 lanthanides plus scandium and advancements that are deeply intertwined with the use yttrium, possesses unique magnetic and optical of specialized materials.
Among these, rare earth elements (REE.
have emerged as indispensable dysprosium (D.
are critical for the manufacturing of components in a vast array of modern technologies, high-performance from consumer electronics to defense systems and permanent magnets.
These magnets are the strongest Specifically, (N.
neodymium-iron-boron (NdFeB) commercially available and are fundamental to Pyrometallurgical high-temperature miniaturization, such as electric vehicle (EV) motors, processes to separate elements based on their affinity wind turbine generators, smartphones, and hard disk for different molten phases.
While effective for large- drives (HDD.
scale operations, these methods are extremely energy- The global demand for Nd and Dy has surged intensive .
ften requiring temperatures exceeding exponentially, a trend projected to continue with the 1500 AC), lead to significant loss of volatile elements, global push towards electrification and green energy.
However, the REE supply chain is fraught with Hydrometallurgy, significant geopolitical and environmental challenges.
involves dissolving the magnet material in strong acids A vast majority of the world's primary REE production .
uch as HCl.
HCCSOCE, and HNOCE) followed by a series is concentrated in a single country, creating price of complex and reagent-intensive solvent extraction, volatility and supply chain insecurity for nations precipitation, or ion-exchange steps to selectively reliant on imports.
Furthermore, the conventional recover the REEs.
Although it operates at lower mining and processing of REEs are notoriously detrimental to the environment.
These processes volumes of corrosive and toxic chemicals, generates involve extensive open-pit substantial amounts mining and off-gases.
acidic wastewater, and chemical extraction steps, often using hazardous struggles with the economic viability of multi-step reagents like sulfuric and hydrofluoric acids.
They separation processes.
The environmental footprint of generate enormous quantities of waste tailings and these conventional methods often rivals that of wastewater contaminated with heavy metals and primary extraction.
Therefore, there is an urgent need for disruptive, degradation, water pollution, and long-term ecological green technologies that can overcome the limitations of existing recycling routes.
Mechanochemistry has In this context, establishing a robust circular emerged as a powerful tool in sustainable chemistry economy for REEs is not merely an economic and materials science, offering a paradigm shift away strategic and solvent-based, high-temperature Urban miningAithe recovery of valuable Mechanochemistry materials from typically delivered through high-energy ball milling, to promising solution.
E-waste, the world's fastest- induce chemical reactions and phase transformations growing domestic waste stream, is a particularly rich in the solid state.
The intense mechanical forces end-of-life productsAipresents critical metals.
NdFeB millingAiimpact, magnets, for instance, can contain up to 30-35% REEs frictionAicreate localized high-pressure and high- by weight, a concentration far exceeding that of temperature spots, leading to the formation of fresh, natural ores.
Recovering these elements from e-waste would simultaneously mitigate the environmental amorphous phases.
This activation can drive chemical burden of primary mining, alleviate supply chain reactions that are otherwise kinetically hindered at pressures, and address the growing problem of e- ambient temperatures.
waste management, especially in developing nations The like Indonesia, which faces a rapid increase in e-waste metallurgical processes offers several compelling advantages: .
it can proceed in a solvent-free or Current methods for recycling NdFeB magnets can minimal-solvent environment, drastically reducing broadly categorized into pyrometallurgy and chemical consumption and waste generation.
it operates at or near room temperature, significantly coil motor magnets.
The nickel-copper-nickel (Ni-Cu- lowering energy input.
it can enhance reaction N.
protective coating on the magnets was first kinetics, leading to faster and more efficient processes.
removed by mechanical abrasion.
The uncoated Several studies have explored mechanochemical- magnet pieces were then subjected to demagnetization assisted leaching, where milling is used to pre-activate by heating at 350 AC for 2 hours in a muffle furnace to ores or waste materials to improve subsequent ensure safe handling and effective milling.
hydrometallurgical extraction.
However.
The demagnetized magnet scrap was embrittled by hydrogen decrepitation.
The scrap was placed in a mechanochemistry to directly drive the conversion stainless-steel reactor, which was evacuated to 10AA reaction in a single, solvent-free step.
torr and then exposed to high-purity hydrogen gas This study aims to develop and systematically solvent-free held under these conditions for 2 hours at room mechanochemical process for the selective conversion temperature, leading to its decrepitation into a coarse, and subsequent recovery of Nd and Dy from waste friable powder.
This powder was then dehydrogenated NdFeB magnet scrap.
The central hypothesis is that by by heating under vacuum at 600 AC for 2 hours.
The co-milling the magnet powder with a carefully selected resulting coarse powder was crushed using a jaw crusher and sieved to obtain a particle size fraction inexpensive salt ammonium chloride (NHCEC.
Aithe below 250 m for use in all mechanochemical insoluble rare earth oxides and intermetallic phases Ammonium chloride (NHCECl.
Ou99.
can be directly converted into water-soluble rare earth purit.
was purchased from Merck Indonesia and used The novelty of this work lies in its departure as the reactant without further purification.
Deionized from the "acid-and-dissolve" paradigm.
We propose a (DI) water was used for all leaching experiments.
reactantAiin one-step, .
999%) at a pressure of 2 bar.
The material was solid-state metathesis reaction driven entirely by The mechanochemical conversion experiments mechanical force, which fundamentally minimizes the were performed using a Retsch PM 100 planetary ball process's environmental footprint.
The research took In a typical experiment, a specific mass of the place in Indonesia, utilizing locally sourced e-waste, to prepared NdFeB magnet powder and NHCECl were loaded into a 50 mL tungsten carbide grinding jar technology in a region grappling with the dual along with tungsten carbide balls .
mm diamete.
The ball-to-powder mass ratio (BPR) was maintained applicability of This at a constant 20:1 for all experiments to ensure comprehensive analysis of the process parameters, efficient energy transfer.
The grinding jar was sealed explores the underlying reaction mechanism through inside an argon-filled glovebox to prevent oxidation of detailed material characterization, and demonstrates the rare earth elements during milling.
a highly efficient, sustainable, and scalable pathway for closing the loop on critical rare earth elements.
A systematic parametric study was conducted to optimize the process.
The following parameters were varied: .
Milling Time: 60, 120, 180, 240, 300, and Methods 360 minutes.
Milling Speed: 200, 300, 400, and The source material for this research consisted of 500 rpm.
NHCECl-to-Magnet Mass Ratio: 1:1, 2:1.
NdFeB magnets extracted from end-of-life hard disk 3:1, 4:1, and 5:1.
During each set of experiments, two parameters were held constant at their determined collection and refurbishment centers in the Greater optimal values while the third was varied.
After Jakarta area.
Indonesia.
A total of 50 HDDs of various milling, the resulting powder mixture was collected brands and ages were dismantled to harvest the voice from the jar inside the glovebox.
(HDD.
To determine the extraction efficiency of Nd and Dy.
Electron Microscopy (SEM) and Energy-Dispersive X- the milled powder was subjected to a simple water ray Spectroscopy (EDS): The morphology, particle size, leaching process.
A 1.
0 g sample of the milled powder and elemental distribution of the powders before and was added to 50 mL of DI water in a beaker.
The after milling were examined using a JEOL JSM-IT500 suspension was stirred at 300 rpm using a magnetic SEM equipped with an EDS detector.
The samples stirrer for 60 minutes at room temperature .
AC).
were mounted on aluminum stubs using double-sided After leaching, the solution was filtered through a 0.
carbon tape and sputter-coated with a thin layer of m syringe filter to separate the aqueous leachate gold to ensure conductivity.
The microscope was containing the dissolved rare earth chlorides from the operated at an accelerating voltage of 15 kV.
EDS
solid residue mapping was used to visualize the spatial distribution .
rimarily iron, iron unreacted phase.
of Nd.
Dy.
Fe.
B, and Cl in the milled samples.
The concentrations of Nd and Dy in the filtered All experiments were conducted in triplicate, and leachate were determined using Inductively Coupled the results are presented as the mean A standard Plasma-Optical Emission Spectrometry (ICP-OES) on The significance of the effects of the process a PerkinElmer Avio 200 instrument.
The instrument parameters on the extraction efficiencies of Nd and Dy was calibrated using certified multi-element standard was evaluated using a one-way analysis of variance Each sample was diluted appropriately with (ANOVA) with Tukey's post-hoc test for pairwise 2% nitric acid to fall within the linear calibration A p-value of < 0.
05 was considered The analysis for each sample was performed in statistically significant.
Statistical analyses were triplicate, and the average concentration was used for performed using OriginPro 2021 software.
The extraction efficiency () for each metal was Results and discussion calculated using the following equation: (%) = (C y V) The / .
y 100, where.
C is the concentration of the decrepitated NdFeB magnet powder was determined metal in the leachate .
g/L).
V is the volume of the by ICP-OES analysis.
The results, presented in figure leachate (L).
m is the mass of the milled powder sample used for leaching .
w is the initial weight fraction performance sintered magnets, with iron being the of the metal in the magnet powder (%).
The initial composition of the magnet powder .
was determined Dysprosium is present as a key additive to improve by digesting a sample of the raw powder in aqua regia coercivity and thermal stability.
The XRD pattern of and analyzing the solution by ICP-OES.
the initial magnet powder is shown in Figure 2.
The The physical and chemical changes in the magnet dominant peaks correspond to the tetragonal NdCCFeCACEB powder throughout the process were monitored using phase (COD ID: 96-152-3.
, which is the primary several analytical techniques.
X-ray Diffraction magnetic phase.
Minor peaks corresponding to a Nd- (XRD): The crystal structures of the initial magnet rich grain boundary phase .
uch as NdOC.
were also powder and the milled products were analyzed using a detected, which is typical for sintered magnets.
Rigaku SmartLab X-ray diffractometer with Cu K SEM analysis of the initial powder radiation ( = 1.
5406 yI) operating at 40 kV and 30 mA.
irregularly shaped The samples were scanned over a 2 range of 20A to distribution, ranging from a few micrometers to over 80A with a step size of 0.
02A and a scanning speed of 100 m.
The particles exhibited sharp edges and a 2A/min.
relatively smooth surface, characteristic of brittle fracture from the crushing process.
The effect of Crystallography Open Database (COD).
Scanning milling time on the extraction efficiency of Nd and Dy Phase identification was was investigated by varying the duration from 60 to rpm and the NHCECl-to-magnet ratio at 3:1.
The results 360 minutes, while keeping the milling speed at 400 are plotted in Figure 3.
Figure 1.
Elemental composition of the starting NdFeB magnet powder.
As shown in Figure 3, the extraction efficiency of the results.
The extraction efficiency was highly both elements increased significantly with milling dependent on the milling speed.
At a low speed of 200 After just 60 minutes, the efficiencies were rpm, the efficiencies were only 55.
7% (N.
2% for Nd and 41.
5% for Dy, indicating that (D.
, suggesting that the energy input was insufficient the mechanochemical reaction initiates rapidly.
The to fully drive the reaction.
Increasing the speed to 300 efficiency rose steeply up to 240 minutes, reaching a rpm and 400 rpm led to substantial improvements, plateau at 98.
6% for Nd and 96.
2% for Dy.
Extending with the maximum efficiencies .
6% for Nd and the milling time to 300 and 360 minutes did not result 2% for D.
achieved at 400 rpm.
A further increase in a statistically significant increase .
> 0.
in to 500 rpm resulted in a slight but significant decrease However, prolonged milling led to excessive in efficiency .
< 0.
This phenomenon is often agglomeration and made powder recovery from the jar attributed to the "caking" effect, where the powder more difficult.
Therefore, a milling time of 240 minutes adheres excessively to the surfaces of the jar and balls was identified as the optimal duration for achieving at very high speeds, reducing the efficiency of impacts near-complete conversion without unnecessary energy and energy transfer.
Thus, 400 rpm was selected as the optimal milling speed.
Milling speed determines the kinetic energy of the The stoichiometric amount of the reactant is a grinding balls and thus the intensity of the mechanical critical factor in any chemical reaction.
The effect of Its effect was studied by varying the speed the NHCECl-to-magnet powder mass ratio was examined from 200 to 500 rpm for a fixed duration of 240 from 1:1 to 5:1, with the milling time and speed fixed minutes and a mass ratio of 3:1.
Figure 4 illustrates at 240 minutes and 400 rpm, respectively.
The results are presented in Figure 5.
larger excess of NHCECl .
:1 and 5:1 ratio.
did not The amount of NHCECl had a profound impact on the further improve the extraction efficiencies.
This At a 1:1 mass ratio, which is below the indicates that a 3:1 ratio provides a sufficient excess stoichiometric requirement, the extraction was limited of the reactant to ensure complete reaction with the 4% for Nd and 64.
0% for Dy.
Increasing the ratio available rare earth phases, while also serving as an to 2:1 and 3:1 significantly boosted the efficiency.
The optimal performance was achieved at a mass ratio of Based on these results, the optimal 3:1, yielding the highest extraction rates.
Using a NHCECl-to-magnet mass ratio was determined to be 3:1.
Figure 2.
XRD pattern of the initial NdFeB magnet powder.
A typical XRD diffractogram showing sharp, intense peaks corresponding to the NdCCFeCACEB phase, indicating a highly crystalline structure.
To understand the mechanism of the process, the of the initial phase and the formation of these new products milled under optimal conditions .
min, phases confirm that a chemical reaction, not just 400 rpm, 3:1 rati.
were thoroughly characterized.
The physical grinding, has occurred.
The broadness of the XRD analysis (Figure .
provides compelling evidence new peaks suggests the formation of nanocrystalline of the chemical transformation.
The characteristic or partially amorphous domains, a common outcome peaks of the NdCCFeCACEB phase, which dominated the of high-energy milling.
initial powder's pattern, were almost entirely absent The morphology of the optimally milled powder was after milling.
Instead, new, broader peaks appeared.
drastically different from the starting material.
The These were identified as corresponding to neodymium originally sharp, large particles were transformed into chloride (NdClCE), dysprosium chloride (DyClCE), metallic much finer sub-micron particles.
These fine particles -iron (F.
, and iron boride (FeCCB).
The disappearance were not discrete but were heavily agglomerated into larger clusters, with the NHCECl acting as a matrix.
This throughout the agglomerate, indicating that the rare intimate mixing and increased surface area are crucial earth elements had intimately reacted with the for facilitating the solid-state reaction.
EDS mapping chlorine from NHCECl.
In contrast, iron was observed to of an agglomerate revealed the elemental distribution be segregated into distinct domains, consistent with within the milled product.
The maps showed a the XRD results showing the formation of a separate metallic iron phase.
Nd.
Dy.
Figure 3.
Effect of Milling Time on the Extraction Efficiency of Nd and Dy.
A line graph showing the extraction efficiency of Nd and Dy increasing with milling time.
The efficiency rises sharply from 60 to 240 minutes and then plateaus, with Nd consistently showing slightly higher efficiency than Dy.
Error bars indicate standard deviation.
The experimental results strongly support the tungsten carbide balls cause repeated fracture and hypothesis that a solid-state metathesis reaction cold welding of the powder particles.
This leads to a occurs during the high-energy co-milling of NdFeB rapid reduction in the particle size of both the magnet magnet powder and ammonium chloride.
The overall proposed reaction for the rare earth components can interfacial contact area between the reactants.
More importantly, this process creates fresh, unpassivated representative REE: NdCCFeCACEB.
NHCECl.
Ie surfaces with a high density of crystal defects, such as 2 NdClCE.
14 Fe.
FeCCB.
* .
NHCE.
dislocations and vacancies, which are highly reactive.
HCC.
The process can be understood through a .
Decomposition of NHCECl and In-situ Formation of multi-step HCl: Ammonium chloride is known to decompose conditions within the planetary ball mill: .
Particle upon heating.
While the overall process is at ambient Size Reduction and Surface Activation: In the initial temperature, the localized points of impact between stages of milling, the high-energy impacts from the milling balls can reach transient high temperatures NHCECl, increasing the .
undreds of AC) and pressures.
These "hotspots" can ammonia (NHCE) and hydrogen chloride (HC.
trigger the thermal decomposition of NHCECl into NHCECl.
NU NHCE.
HCl.
Figure 4.
Effect of Milling Speed on the Extraction Efficiency of Nd and Dy.
A bar chart showing the extraction efficiency of Nd and Dy at different milling speeds .
, 300, 400, 500 rp.
The efficiency increases markedly from 200 to 400 rpm and then slightly decreases at 500 rpm.
This in-situ generation of highly reactive, gaseous more stable phases.
The XRD results (Figure .
HCl within the sealed milling jar is a key step.
The HCl confirm the formation of metallic -iron and iron gas can readily attack the highly activated surfaces of boride (FeCCB), indicating the decomposition of the the rare earth phases in the magnet powder.
parent ternary compound.
This phase segregation is Chlorination of Rare Earths: The primary magnetic crucial as it liberates the REEs for chlorination and phase (NdCCFeCACEB) and the Nd-rich grain boundary results in a final mixture where the REE chlorides are phases react with the generated HCl.
The rare earth physically distinct from the iron-based matrix.
This elements are significantly more electropositive than physical separation is what allows for the simple and iron and have a higher affinity for chlorine.
They are effective separation via water leaching.
selectively chlorinated to form solid rare earth The observed plateau in extraction efficiency after chlorides: 2 REE.
n allo.
6 HCl.
Ie 2 REEClCE.
3 240 minutes and at a speed of 400 rpm corresponds HCC.
to the point where the combination of accumulated This reaction is thermodynamically favorable.
The continuous grinding ensures that any passivating activation is sufficient for the reaction to reach near - chloride layer is scraped off, exposing fresh metallic Beyond this point, further energy input surfaces for yields diminishing returns, and negative effects like further reaction, thus driving the conversion to completion.
Phase Segregation: As the REEs are extracted from the NdCCFeCACEB lattice, the requirement for an excess of NHCECl is explained by its remaining iron and boron atoms rearrange to form multiple roles: it is the The primary reactant, its decomposition products drive the chlorination, and hundreds of liters of concentrated acid per kilogram of the excess solid acts as a diluent and process control magnet processed, leading to a massive wastewater agent, preventing excessive cold welding of the metallic treatment challenge.
Our process replaces this with a iron particles.
solid, recyclable reactant and a final, simple water This mechanochemical process offers profound leaching step.
The leachate produced is a relatively advantages over conventional recycling technologies.
clean solution of rare earth chlorides, which is a comparative summary is provided in figure 7.
The standard precursor for molten salt electrolysis to most significant advantage is the elimination of liquid seamlessly into existing production chains.
Traditional REE hydrometallurgy for NdFeB magnets can consume Figure 5.
Effect of NHCECl-to-Magnet Ratio on Extraction Efficiency of Nd and Dy.
A line graph showing extraction efficiency versus the mass ratio of NHCECl to magnet powder.
The efficiency climbs from a ratio of 1:1 to a peak at 3:1, after which it remains constant for 4:1 and 5:1.
Furthermore, the process operates at ambient solid residue, composed mainly of iron and iron boride, temperature, leading to substantial energy savings is relatively benign and could be repurposed in compared to both pyrometallurgy and the heating steelmaking or other applications, minimizing solid often required in hydrometallurgical leaching.
The waste disposal.
ammonia gas generated during the reaction could From potentially be recovered and reacted with HCl .
rom Indonesia, this technology is particularly attractive.
another sourc.
to regenerate the NHCECl reactant, avoids the need to import or produce large quantities further enhancing the circularity of the process.
The of hazardous chemicals and reduces the capital cost and complexity associated with building a full-scale infrastructure-intensive model for valorizing local e- hydrometallurgical plant with extensive wastewater waste streams.
treatment facilities.
It offers a more decentralized, less Figure 6.
XRD Patterns of the Initial Magnet Powder and the Optimally Milled Product.
A comparison of two XRD The top pattern .
shows sharp NdCCFeCACEB peaks.
The bottom pattern .
shows that the NdCCFeCACEB peaks have almost completely disappeared, replaced by broad peaks corresponding to NdCl CE.
DyClCE, metallic Fe, and FeCCB.
While this study successfully demonstrates the .
ons per hou.
presents engineering challenges.
While high efficiency of mechanochemical process at the industrial-scale mills, such as attritor or vibratory laboratory scale, several aspects require further mills, exist, the process parameters would need to be investigation before industrial implementation.
re-optimized for a different milling environment.
Selectivity and Purity: The current process co-extracts techno-economic analysis based on a scaled-up Nd and Dy into the leachate.
While this is sufficient for process is essential to evaluate its commercial producing a mixed rare earth oxide or mischmetal, .
Ammonia Management: The reaction many applications require separated, high-purity rare generates ammonia gas.
A closed, industrial-scale Future research should focus on developing system would require an efficient off-gas handling and selective separation techniques that are compatible recovery system to prevent its release and to potentially regenerate the NHCECl The mechanochemical routes that might offer inherent feasibility and efficiency of such a recovery loop need selectivity by using different reactants or conditions.
to be studied.
Downstream Processing: This work The co-dissolution of other minor elements (Pr.
focused on the primary extraction step.
A complete life present in the magnet also needs to be quantified and .
Scalability: The process was optimized downstream processing of the leachate to produce in a laboratory-scale planetary ball mill.
Scaling up high-purity rare earth oxides or metals and evaluating mechanochemical processes to an industrial scale the valorization pathways for the solid iron/boron assessment would require optimizing the residue.
Future research should be directed towards types of e-waste, and integrating the process with these areas.
Investigating a wider range of benign solid automated sorting and pre-treatment technologies will reactants, exploring the mechanochemistry of different be key to realizing its full potential.
Figure 7.
Comparison of NdFeB magnet recycling technologies.
Conclusion earth elements, particularly in nations like Indonesia This study successfully designed and validated a aiming to develop domestic capacity for e-waste novel, solvent-free mechanochemical process for the This research lays a strong foundation for sustainable recovery of neodymium and dysprosium the future development of scalable mechanochemical from waste NdFeB magnets.
By co-milling magnet technologies for a more sustainable materials future.
powder with ammonium chloride, the insoluble rare
earth phases were efficiently converted into watersoluble systematic optimization of References