Project COFUND – ERAMIN-3 2022

Rare Earths Elements (REE) are essential materials in connected and electrical technologies, and the transition to a decarbonisation and greener economy, due to their unique properties making them suitable for use in various automotive, electronics, industrial, power generation, and other applications as for example permanent magnets, sensors, catalysts, rechargeable batteries, etc. Technical innovations including advanced physical separation techniques, new treatment for an increased recovery of valuable metals and technologies are needed to recover metals from residues by physical, chemical, biological methods, or combinations thereof. The MW4REMAM aims to develop an innovative technology for efficient recovery of both rare earth metals and plastics from end-of-life WEEE and urban mines. Then re-use them as raw material for fabrication of plastic-RE composite filaments and create new magnetic components via additive manufacturing. The objective is fully in line with topic 4. Recovery of raw materials from End-of-life products, sub-topic 4 Recover metals and rare earth elements from urban mines via innovative, clean, and environmentally friendly processes (hydrometallurgy, pyrometallurgy…) and separation techniques from ERAMIN Roadmap.
The expected results are: elaboration of an efficient technology for recovery of plastic and metallic parts from small WEEE at the End of Life; elaboration and optimization of the MW technology for recovery of REEs by metal extraction; methodology for full characterization of REEs obtained by MW process; innovative solutions for establishment, optimization and improvement of mechano-synthesis of micro/nano powders for Additive Manufacturing; obtaining of filaments from recycled plastics and REE and testing for FDM of new magnets; measurement of the environmental and economic impact of new technologies.

STAGE I    2022

During the first stage of project execution, the following activities were foreseen:

• Verification of different types of WEEE from the point of view of metal and plastic composition
• Preliminary experiments for the separation and processing of different types of WEEE
• Characterization by different physical-structural methods (elemental composition, DRX)
• Modernization and testing of microwave treatment equipment

The different types of WEEE were classified and the REE content was determined by chemical methods of analysis. The main REE recovery methods were then briefly analyzed.
An experimental model was developed and preliminary experiments were carried out for the recovery of REE from WEEE by molten Mg bath extraction using microwave energy for heating.
The microwave facility was upgraded by fitting higher power magnetrons and the Mg distillation retort was designed and executed for the recovery of REE from the treated waste. The first batches of Mg-REE alloy powder were obtained, which will be further used for the recovery of Nd and Dy from recycled magnets for subsequent use in the re-manufacturing of magnets by the 3D printing method.

STAGE II    2023

Extraction with molten Mg is an efficient method of separating REE elements – Nd, Sm, Dy, etc. from accompanying elements (Fe, B) in permanent magnets NdFeB, method based on high differences in solubility in bath of components. The difference between the vapour pressure of Mg (0.73 atm at1000°C) and Nd (<10-6 at1000°C), respectively, allows their separation by evaporation and condensation of Mg at temperatures of 800…1000°C and a residual pressure of 400…600 mmHg. The degree of shredding of REE magnet waste drastically influences extraction yields, experimentally it was determined that a shredding at sizes of 2…5 mm is sufficient to achieve extraction yields of ≈ 90%. At sizes smaller than 1 mm, due to oxidation, extraction yields decrease.
Based on the experimental results, a laboratory technology (TRL4) for REE recovery by microwave field extraction was developed. The Nd content in the sponge resulting after Mg evaporation is 96-98%.
The elaborated methodology of physicochemical characterization of samples is according to standards and includes the necessary steps for a complete analysis: average sampling, elementary chemical analysis by instrumental methods, microstructure analysis (MO, SEM, RDX) and phase transformations.
Microwave system was improved by mounting new magnetrons enabling increase of power to extract REEs from WEEE. The installation was completed with design, execution and implementation of the evaporation system to obtain Nd-rich sponge after pyrometallurgical treatment with molten Mg.
IMNR First Refined REE alloy feed available. Powders with 96-98% Nd were obtained and samples were delivered to IC-BAS. A first joint review publication is in course.

Fig. no. 1 Types of NdFeB EoI magnets recycled by MW process

STAGE III    2024

As a result of the experimental works carried out, a laboratory technology (TRL4) was developed for the recovery of Nd from permanent magnet waste based on NdFeB alloy, by extraction with liquid metal (Mg) in the microwave field. Mg-Nd alloys with Nd content of 42…47% were obtained with calculated Nd extraction yields of 72 … 88%.
Following the distillation of Mg from the Mg-Nd alloys obtained, Nd of purity > 96% was obtained. Other chemical elements present in recovered NB (Fe: 0.11 … 3.64%), Mg (0.1 … 2.66%), Dy, Pr, Sm, B, Al existing as alloying elements in commercial NdFeB magnets.
The powders obtained by grinding in a vibratory mill, under lamp oil and hexane, respectively NdFeB magnet powder, Mg-Nd alloy powder, respectively recovered Nd powder, have the characteristics required for testing for additive manufacturing (mechanical-chemical synthesis, obtaining polymer matrix composites): granulation: < 25 μm, B: < 1 mT.

Publications

Zara Cherkezova-Zheleva, Marian Burada, Anca Elena Sobetkii (Slobozeanu), Daniela Paneva, Sabina Andreea Fironda , Radu-Robert Piticescu; “Green and Sustainable Rare Earth Element Recycling and Reuse from End-of-Life Permanent Magnets” – MDPI, Metals 2024, 14(6), 658; https://doi.org/10.3390/met14060658

Sabina Andreea Fironda, Cristina Ioana Badea, Marian Burada, Radu-Robert Piticescu, Lidia Licu; “Recovery of Nd from spent HHD permanent magnets by MW LME and Mg distilling” – MDPI, Magnetism; Manuscript ID: magnetism-3274495 în curs de evaluare.

Conferences

Sabina Andreea Fironda, Adelina Ionela Matei, Anca Elena Sobetkii (Slobozeanu), Lidia Licu, Marian Burada, Radu-Robert Piticescu, Sorin Axinte, O. Jay; “Recovery of Nd from HDD Magnets” – International Chemical Engineering and Materials Symposium, SICHEM 2024, April 11-12, 2024, Bucharest, Romania;

Sabina Andreea Fironda, Anca Elena Sobetkii (Slobozeanu), Adelina Ionela Matei, Marian Burada, Radu-Robert Piticescu, Zara Cherkezova-Zheleva; “Towards the Circular Economy of Rare Earth Elements: Applications and Recycling” – Advanced Structures, Materials and Electrical Systems, ASMES 2024, May 9-12, 2024, Tulcea, Romania;

Sabina Andreea Fironda, Cristina Badea, Marian Burada, lidia Licu, Radu-Robert Piticescu, Zara Cherkezova-Zheleva, Sorin Axinte, O. Jay; “LCA Study on Recycling Neodymium from Spent HDD Permanent Magnets” – The 7th International Conference EMERGING TECHNOLOGIES IN MATERIALS ENGINEERING – EMERGEMAT, October 30-31, 2024, Bucharest, Romania.

Workshop: “MICROWAVE ENHANCED RECOVERY OF REES AND PLASTIC FROM WEEE AND RE-USE IN ADDITIVE MANUFACTURING OF NOVEL MAGNETIC COMPONENTS“ – The 7^th International Conference EMERGING TECHNOLOGIES IN MATERIALS ENGINEERING – EMERGEMAT, October 30-31, 2024, Bucharest, Romania.