As electric vehicles, wind power generators, motores industriais, robôs, and consumer electronics continue to expand, the demand for NdFeB, SMCO, and other ímãs permanentes de alto desempenho is increasing rapidly. Ao mesmo tempo, magnet production scrap, discarded motor magnets, and end-of-life magnets recovered from electronic equipment are becoming important secondary sources of rare earth elements.
Permanent magnet recycling is not simply a matter of crushing used magnets and reusing the resulting material. The appropriate recycling process depends on the source of the waste, oxidation level, coating type, chemical composition, and impurity content. Atualmente, the three most widely discussed routes are physical recycling, hydrometallurgical recycling, and biological recycling.
Which technology is the most feasible? The answer depends on the characteristics of the waste and the intended recycled product.
1. Physical Recycling: Preserving the Material Value of Magnets
Physical recycling generally includes dismantling, demagnetization, esmagamento, screening, separação magnética, and hydrogen decrepitation. In a broader sense, it also covers short-loop direct recycling processes that preserve as much of the original alloy composition and microstructure as possible.
Instead of completely separating the rare earth elements from the alloy, direct recycling converts discarded magnets into reusable magnetic powder or feedstock for new magnets.
The main advantages of physical recycling include a relatively short process, limited chemical consumption, and potentially lower energy requirements. It is particularly suitable for clean NdFeB production scrap with a known composition and limited contamination.
No entanto, physical recycling places relatively strict requirements on feedstock quality. Magnets recovered from end-of-life motors, unidades de disco rígido, Aparelhos domésticos, and electronic devices may contain:
- Adhesives;
- Níquel, zinco, or epoxy coatings;
- Steel components;
- Plastic parts;
- Lubricants;
- Magnets of different grades and compositions.
If these materials cannot be separated effectively, the impurities may reduce the remanence, coercividade, mechanical performance, and consistency of the recycled magnet.
Oxidation is another important issue. NdFeB magnetic powder is chemically active. Excessive oxygen can react with the rare-earth-rich grain-boundary phases, reducing the amount of rare earth available for forming an effective microstructure. Powder preparation must therefore be carried out under carefully controlled oxygen and moisture conditions.
There are also safety considerations. Fine NdFeB powder may oxidize rapidly and can present dust or combustion hazards. Proper inert-gas protection, dust collection, temperature control, and explosion-prevention measures are essential.
2. Hydrometallurgical Recycling: A Mature Route for Complex Waste
Hydrometallurgical recycling usually begins with dismantling, demagnetization, esmagamento, or thermal pretreatment. The waste is then treated with an acidic or alternative leaching solution so that rare earth elements enter the liquid phase.
Neodímio, praseodímio, Disprósio, térbio, samário, and other elements can subsequently be separated using precipitation, solvent extraction, ion exchange, crystallization, or related purification processes.
Unlike direct recycling, hydrometallurgy does not attempt to preserve the original magnet structure. Its purpose is to convert the waste into purified rare earth salts, oxides, or other compounds that can re-enter the upstream material production chain.
This method is therefore more suitable for:
- Mixed magnet waste;
- Heavily oxidized magnets;
- Grinding sludge and contaminated swarf;
- Magnets with unknown grades;
- End-of-life magnets containing multiple coatings and impurities.
Hydrometallurgical processes can offer high recovery rates, good separation accuracy, and broad feedstock adaptability. Leaching and solvent-extraction technologies also have an established industrial foundation. For these reasons, hydrometallurgy remains one of the most important routes for recovering rare earth elements from complex NdFeB and SmCo magnet waste.
Its disadvantages include relatively high acid and alkali consumption. The process may also generate wastewater, iron-rich residues, salts, and other by-products requiring further treatment. If leaching agents are not recycled and wastewater treatment is poorly managed, the recycling process itself can create additional environmental burdens.
The economic feasibility of hydrometallurgy is strongly influenced by the rare earth concentration in the feedstock. Directly shredding complete appliances or motors without first concentrating the magnets may dilute the rare earth content and make subsequent chemical recovery less economical.
3. Biological Recycling: Promising but Still Developing
Biological recycling, also known as bioleaching or biometallurgy, uses microorganisms, biologically produced acids, or biological adsorption materials to recover metals from magnet waste.
Certain microorganisms produce organic or inorganic acids during metabolism. These substances can dissolve rare earth elements and other metals from pretreated magnetic materials. Biological adsorbents may also be used to capture rare earth ions from low-concentration solutions.
Compared with conventional strong-acid leaching, biological methods may offer several potential advantages:
- Relatively mild operating conditions;
- Lower process temperatures;
- Reduced consumption of concentrated chemical reagents;
- Potentially lower energy consumption;
- The possibility of using renewable biological agents.
No entanto, ímãs permanentes present several difficulties for biological treatment. NdFeB magnets contain a large proportion of iron, and dissolved iron can interfere with the selective recovery of rare earth elements. High metal concentrations may also inhibit microbial activity.
Além disso, biological leaching is generally slower than conventional chemical leaching. Maintaining stable microbial performance in a large industrial reactor can be difficult because temperature, pH, oxygen supply, nutrient conditions, and metal toxicity must all be carefully controlled.
Como resultado, biological recycling should currently be regarded as a promising complementary technology rather than a complete replacement for established hydrometallurgical processes. It may be particularly useful for low-grade residues, diluted waste streams, or hybrid processes that combine biological leaching with chemical separation.
4. Comparison of the Three Recycling Technologies
| Comparison factor | Physical or direct recycling | Hydrometallurgical recycling | Biological recycling |
| Primary objective | Preserve alloy or magnetic powder value | Separate and purify rare earth elements | Use biological processes to leach or capture metals |
| Suitable feedstock | Clean, traceable production scrap | Mixed, oxidized, or contaminated magnet waste | Low-grade waste, residues, or pretreated materials |
| Process length | Relatively short | Relatively long | Usually long |
| Rare earth separation capability | Limited | Strong | Depends on microorganisms and process chemistry |
| Chemical consumption | Baixo | Relatively high | Potentially low |
| Processing speed | Fast | Moderado | Generally slow |
| Feedstock adaptability | Limited to moderate | Alto | Currently limited |
| Product type | Recycled alloy powder or regenerated magnet | Rare earth salts, oxides, or compounds | Rare-earth-containing solution or concentrated product |
| Industrial maturity | Moderate to high for selected waste | Relatively high | Relatively low |
| Main challenge | Impurities, oxidação, and compositional variation | Wastewater, reagents, and separation costs | Leaching rate and industrial stability |
5. Which Permanent Magnet Recycling Technology Is More Feasible?
There is no single recycling technology that is optimal for every type of permanent magnet waste.
For clean production scrap, defective magnets, and offcuts with known chemical compositions, physical separation and short-loop direct recycling should generally be evaluated first. These methods can preserve more of the original material value while reducing repeated chemical separation and refining.
For heavily oxidized, contaminated, mixed-grade, or unknown magnet waste, hydrometallurgical recycling is usually more adaptable. It can separate valuable rare earth elements from iron, revestimentos, and other impurities, although environmental controls and reagent recycling are necessary.
Biological recycling has considerable environmental potential, but its reaction speed, process stability, and industrial scale still require further development. In the near term, it is more likely to complement physical and hydrometallurgical methods than replace them.
The most practical future solution may be a graded recycling system:
- Dismantle and identify the magnets.
- Separate them by material, grade, coating, and contamination level.
- Directly regenerate clean and traceable materials.
- Apply hydrometallurgy to complex or degraded waste.
- Use biological or other low-impact processes for suitable low-grade streams.
- Return recovered materials to magnet production.
JLMAG Innovation’s business covers magnetic materials, magnetic assemblies, motor recycling, and scrap magnet recycling. Connecting magnet design, produção, aplicativo, dismantling, and recycling can improve material traceability and support a more efficient closed-loop supply chain for ímãs permanentes.
