A recycling system of scrap rare earth magnets sorting and conversion into usable magnets and a method of manufacturing the same

Abstract

The present invention discloses a system and method for recycling R-Fe-X-B magnets into usable magnetic products with targeted properties from various scrap assemblies and end-of-life devices, leveraging artificial intelligence and machine learning for efficient separation based on device type and total heavy rare earth content in the scrap magnets. Utilizing various forms of thermal energy in controlled atmospheres, the process demagnetizes and separates magnets, further employing mechanical, thermal, acoustic, supercritical fluid or chemical methods to remove adhesives and surface coatings on magnets. Environmentally friendly techniques for stripping coatings and sophisticated composition-based sorting using X-ray fluorescence (XRF) spectrometry are integral for producing recycled magnets with tailored properties for useful applications. The method encompasses pulverization, blending with secondary elements / alloy powders and advanced sintering techniques to achieve optimal magnetic properties. Additionally, it facilitates the production of high resistivity, high coercivity and near net shaped recycled sintered magnets and spherical powders for additive manufacturing (AM), enabling the creation of AM magnets without relying on virgin elements. The method also enables production of rapidly solidified ribbon powders and bonded magnets.

Description

A RECYCLING SYSTEM OF SCRAP RARE EARTH MAGNETS SORTING AND CONVERSION INTO USABLE MAGNETS AND A METHOD OF MANUFACTURING THE SAMETECHNICAL FIELD

[0001] The invention pertains to the recycling of rare earth -iron-boron (R-Fe-X-B) magnets from scrap, specifically from end-of-life electric-powered devices, to conserve valuable materials.BACKGROUND OF THE INVENTION

[0002] Rare earth magnets, specifically those composed of rare earth-iron-boron (R- Fe-X-B) elements (R is at least one or more elements from rare earth Nd, Pr, Tb, Dy, La, Ce, Gd, X= other elements for example Co, Al, Ga, Cu, Zr, Nb, Ti, Mo, Mn, Si, Sn, C), are integral to a myriad of modern technologies. These magnets are renowned for their exceptional magnetic strength, durability, and performance at room temperature to high temperatures, making them indispensable in a wide range of applications. Notably, Nd-Fe-X-B magnets, which include neodymium (Nd), praseodymium (Pr), dysprosium (Dy), terbium (Tb), Lanthanum (La), Cerium (Ce), Gadolinium (Gd), iron (Fe), boron (B), and other elements (X) such as cobalt (Co), aluminium (Al), and gallium (Ga), copper (Cu), zirconium (Zr), Niobium (Nb), Titanium (Ti), Molybdenum (Mo), Manganese (Mn), silicon (Si), Tin (Sn), carbon (C) are critical components in various electromechanical / electrical devices. These devices span across diverse sectors, including industrial motors, wind turbines, electric vehicles (EVs), computing technology, healthcare equipment like MRI scanners, and even in emerging technologies such as drones and electric aircraft, apart from strategic applications.

[0003] Despite their widespread utility, the production of R-Fe-X-B magnets is fraught with challenges. The extraction and processing of rare earth elements are environmentally taxing, involving significant energy consumption and generating hazardous waste and pollution. Furthermore, rare earth elements are subject to geopolitical tensions and supply chain vulnerabilities, given that a significant portion of the world's supply originates from a limited number of countries. These factors contribute to the fluctuating availability and pricing of rare earth elements, urging the need for sustainable alternatives to mitigate these risks.

[0004] Current recycling methods for rare earth magnets are limited and often inefficient, failing to address the growing demand and environmental concerns effectively. Traditional recycling processes, such as those disclosed in patent documents like W02014 / 205002A2, WO2023 / 240346A1 and Indian Patent No 368788, offer foundational techniques for recycling magnetic materials. These methods typically involve demagnetizing waste magnets, fragmenting them into powder, extract the rare earth elements and undergoing processes such as hydrogen decrepitation or mechanical milling or chemical process. However, these approaches have limitations, including high energy consumption, potential damage to the magnetic properties of the materials, and the inability to efficiently segregate and process mixed scrap materials from a diverse array of devices. Further, limitation on efficient conversion of scrap into usable magnets with tailored properties.

[0005] Moreover, the existing recycling technologies often overlook the importance of coating removal / surface cleaning, removal of impurities and sorting of scrap magnets with definite composition, which are crucial for maintaining the magnet performance in their second life. Coatings, which protect the magnets from corrosion and enhance their physical properties, can introduce contaminants during the recycling process if not properly removed. Traditional methods for coating removal typically involve chemical treatments that may poseenvironmental hazards. The presence of impurities will also degrade the magnetic performance of the recycled magnets if the impurities are not removed to the desired level. Conventional methods of recycling leads to uncertainty in the recycled magnetic properties as the diverse scrap with different chemical compositions are processed which deviates from the required chemistry to develop various grades of high-performance magnets. Also, the scrap magnets are subjected to pyrometallurgical / hydro-metallurgical extraction processes to convert into metal oxide precursors followed by the metal reduction process to reuse in the magnet making processes are energy intensive and environmentally hazardous.

[0006] In light of these challenges, there is a pressing need for innovative recycling technologies that are not only efficient and environmentally friendly but also capable of handling the complexities associated with the diverse sources of rare earth magnet scrap. Such technologies must address the critical aspects of automated segregation of mixed scrap materials, effective detachment and separation of magnets from devices, eco-friendly coating removal processes, segregation based on composition, and the preservation or enhancement of the magnetic properties of the recycled magnets. By offering solutions to these issues, the proposed invention aims to revolutionize the recycling of R-Fe-X-B magnets, making it a cornerstone in the pursuit of a more sustainable and resilient supply chain for rare earth magnets. This invention is poised to contribute significantly to the circular economy, reducing dependence on virgin rare earth element resources, mitigating environmental impacts, and fostering the sustainable growth of industries reliant on high-performance magnets.OBJECTS OF THE INVENTION

[0007] The primary object of this invention is to provide a method and system for the efficient recycling of rare earth-iron-boron (R-Fe-X-B) magnets from scrap assemblies, including end-of-life electronic devices, transportation, and industrial equipment.

[0008] Yet another object is to facilitate the detachment of magnets from scrap assemblies in an environmentally friendly manner.

[0009] Another objective is to reduce the environmental impact associated with the production of rare earth magnets by introducing green methods for coating removal from scraped magnets, including supercritical fluid, mechano-chemical, chemical, and mechanical treatments.

[0010] Yet another object of the invention is to provide a scalable process for the production of high-quality recycled sintered and bonded magnets with targeted / desirable magnetic properties.

[0011] A further object of this invention is to enhance the efficiency and effectiveness of recycling processes.

[0012] Another object is to streamline the recycling workflow through the integration of automated systems working on artificial intelligence and machine learning tools for sorting diverse scrap, stripping of coatings, and segregation of scraped magnets.

[0013] Yet another object of the invention is to develop a method for producing recycled magnets that exhibit enhanced magnetic properties and thermal stability.

[0014] A further object is to innovate in the field of additive manufacturing (AM) of rare earth magnets by introducing processes for the production of spherical powders and AM magnets.

[0015] Lastly, an object of this invention is to promote sustainable practices within the rare earth magnet industry by providing a comprehensive recycling solution.SUMMARY OF THE INVENTION

[0016] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.

[0017] According to an embodiment of the present invention, a system for segregating and recycling Nd-Fe-X-B magnets from mixed scrap assemblies is provided. This system features an automated segregation unit that leverages artificial intelligence (Al) and machine learning (ML) algorithms in combination with imaging devices. This unit is adept at identifying and categorizing scrap assemblies into lots based on predefined criteria such as type, size, and shape. The system also includes a conveyor unit designed to efficiently transport materials between various stages of the recycling process.

[0018] In addition, the invention encompasses a thermal treatment unit equipped with a variety of technologies including infra-red light, laser, ultraviolet heating, inductive heating, joule heating, and shock waves. This unit operates in either an inert or reduced atmosphere or vacuum, applying a thermal energy flash that demagnetizes the Nd-Fe-X-B magnets and also facilitates their detachment from the scrap assemblies. Furthermore, an adhesive removal unit is part of the system, which uses a high-pressure gas pressurizer and a mechanical agitator to effectively strip off adhesive residues. Following this step, a magnet-separating unit equipped with a robot or mechanical device to detach magnets from the assemblies.

[0019] The magnet-separating unit described herein is a novel device, equipped with a robotic or mechanical device, this unit excels in identifying, isolating, and delicately detaching magnets from various assemblies, ensuring minimal damage and maximal efficiency, by employing advanced sensors and imaging technology for initial assessment and subsequent manipulation, the unit offers adaptability to separate magnets from various assembly types and sizes, for example, electric vehicle traction motor, industrial motor, windmills, hard disk drives, drone motors and etc.

[0020] In a further embodiment of the present invention, includes a coating stripping unit designed for the removal of surface coatings from the magnets. The unit utilizes mechanochemical, chemical, thermal, supercritical CO2, thermo-mechanical and mechanical treatments to efficiently remove various types of coatings, preparing the magnet surfaces for further recycling processes. This step is essential for ensuring the purity and quality of the recycled magnets, making them suitable for a wide range of applications.

[0021] According to another embodiment of the present invention, the segregation unit is enhanced with a composition analyzer. The analyzer utilizes non-destructive testing technologies, including X-ray fluorescence (XRF) spectrometry, enabling rapid determination of each magnet's chemical composition. This capability is crucial for facilitating the sorting of magnets based on their heavy rare earth (HRE) element (Tb, Dy, Gd, Ho) content, ensuring that the recycling process is both efficient and precise in producing recycled magnets with targeted / desired properties.

[0022] In a further embodiment, the automated segregation unit is refined to integrate size and shape recognition capabilities. This allows the unit to distinguish between different types of scrap materials, such as electric vehicle (EV) motors, hard disks, and windmillcomponents, enabling targeted recycling processes that are tailored to the specific characteristics of each scrap type.

[0023] Another embodiment specifies that the thermal treatment unit is configured to maintain temperatures above the Curie temperature of Nd-Fe-X-B magnets, ranging from 25°C to 650°C. This temperature control is pivotal for achieving optimal demagnetization and adhesive disintegration, ensuring that the magnets are prepared for the subsequent steps of the recycling process without compromising their integrity.

[0024] According to yet another embodiment of the present invention, to enhance the magnetic properties of the recycled magnets, a specialized process is included. This process involves pulverizing the sintered magnets to a desired particle size range, blending them with secondary element / alloy powders, aligning the powder in a magnetic field, compaction and subjecting the resultant green compacts to thermal heat-treatment. This meticulous procedure produces recycled magnets with significantly enhanced and desired magnetic properties.

[0025] According to an embodiment of the present invention, a method is provided for recycling Nd-Fe-X-B magnets from mixed scrap assemblies. This method involves several key steps to ensure the efficient processing and repurposing of the magnets. Initially, scrap assemblies are segregated into lots based on their type through an automated system that utilizes artificial intelligence (Al) and machine learning (ML) algorithms, along with imaging devices, to accurately identify and categorize the materials.

[0026] Following the segregation, the assemblies are subjected to a thermal energy flash within either an inert or reduced atmosphere, or vacuum. This process is crucial for demagnetizing the Nd-Fe-X-B magnets and disintegrating any adhesives that bind the magnets to their assemblies, preparing them for the subsequent stages of recycling.

[0027] To further clean the assemblies, high-pressure gas and mechanical vibrations are applied to remove any residual adhesive materials. This step ensures that the magnets are free from adhesives and other contaminants that might affect their quality and performance.

[0028] In the next phase of the process, the magnets are detached from the assemblies using robot or mechanical device. This device is specifically designed to handle the delicate task of separating the magnets without causing damage, thus preserving their integrity for future use.

[0029] Additionally, the surface coatings on the magnets are stripped away as part of the recycling process. Removing these coatings is essential for preparing the magnets for their eventual repurposing, ensuring that they meet the necessary quality standards for recycled magnets.

[0030] According to another embodiment of the present invention, the chemical composition of each magnet is analyzed using non-destructive methods, such as X-ray fluorescence (XRF) spectrometry. This analysis allows for the sorting of magnets into groups based on their content of heavy rare earth (HRE) elements. AI / ML algorithms are used to sort the magnets into groups with definite composition range. Such precise sorting is vital for optimizing the recycling process and ensuring that the recycled magnets meet specific performance criteria.

[0031] According to yet another embodiment of the present invention, the selection of secondary additive to be added with the scrap magnetic powder for realizing the predefined targeted magnetic properties in the final recycled magnets is carried out by the AI / ML algorithms with given database of composition and properties of scrap magnets as well as secondary additive.

[0032] In a further embodiment, the method includes maintaining the temperature above the Curie temperature of the Nd-Fe-X-B magnets during the thermal energy flash. This specific temperature control is critical for ensuring the efficient demagnetization and disintegration of adhesives, thereby facilitating the clean and easy removal of magnets from their assemblies.

[0033] According to yet another embodiment of the present invention, recycled magnets with enhanced magnetic properties are produced through a series of carefully designed steps. These steps include pulverizing demagnetized magnets, blending them with secondary element / alloy powders, aligning the powder in a magnetic field, compaction and subjecting the resultant green compacts to thermal heat-treatment. This comprehensive approach to recycling not only preserves the valuable magnetic properties of the Nd-Fe-X-B magnets but also enhances them, making the recycled magnets suitable for a wide range of applications.

[0034] In a further embodiment of the present invention describes the preparation of recycled Nd-Fe-X-B magnets that includes coating the recycled powders with a thin layer of dielectric material, wherein the processes such as chemical vapor deposition or electrophoresis are employed to achieve this coating, which significantly increases the resistivity of the magnets and reduces eddy current loss. The other approach adopted to prepare magnets with increased resistivity is that the dielectric materials were placed as layers at different thicknesses in the powder layers while preparing the green compact. The coated powders or layered powders are further processed into sintered magnets using the process steps described above. This innovative step further enhances the performance of the recycled magnets, making them more efficient and suitable for advanced applications where reduced energy loss is critical.

[0035] According to yet another embodiment of the present invention, recycled magnets with high operating temperature are produced adopting grain boundary modificationmethod. This involves diffusion of HRE and its alloys into the recycled magnets. The steps include coating the recycled magnet with HRE or its alloy hydride powders, and subjecting them to diffusion heat treatment in vacuum. The process enhanced the coercivity of the recycled magnets with usage of less amount of HRE in making the magnets suitable for high temperature applications.

[0036] According to yet another embodiment of the present invention, Nd-Fe-X-B spherical powders from scrap magnets are produced for additive manufacturing. Further, additively manufactured magnets and bonded magnets with precise complex geometrical features are produced.

[0037] In a further embodiment of the present invention, rapidly solidified ribbon powders from the scarp magnets are produced for bonded magnet applications. The steps include rapid solidification of scrap magnets after composition adjustment, and pulverization to make powders. Further, bonded magnets with various shapes, sizes are produced with the powders.

[0038] These and other aspects of the embodiments herein will be better appreciated and understood when considered in conjunction with the following description and the accompanying drawings. It should be understood, however, that the following descriptions, while indicating the preferred embodiments and numerous specific details thereof, are given by way of illustration and not of limitation. Many changes and modifications may be made within the scope of the embodiments herein without departing from the spirit thereof, and the embodiments herein include all such modifications.BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The other objects, features and advantages will occur to those skilled in the art from the following description of the preferred embodiment and the accompanying drawings in which:

[0040] FIG. 1 to 7 illustrates the process of the recycling of scrap rare earth magnets and the method of manufacturing usable magnets, according to the present invention.

[0041] Although the specific features of the present invention are shown in some drawings and not in others. This is done for convenience only as each feature may be combined with any or all of the other features in accordance with the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0042] In the following description, a reference is made to the accompanying drawings that form a part hereof, and in which the specific embodiments that may be practised are shown by way of illustration. These embodiments are described in sufficient detail to enable those skilled in the art to practice the embodiments and it is to be understood that other changes may be made without departing from the scope of the embodiments. The following description is therefore not to be taken in a limiting sense. The various embodiments of the present invention provide for a recycling approach of scrap rare earth magnets sorting and conversion in to usable magnets and method of manufacturing the same.

[0043] According to an embodiment of the present invention, a system for segregating and recycling Nd-Fe-X-B magnets from mixed scrap assemblies is provided. This system features an automated segregation unit that leverages artificial intelligence (Al) and machine learning (ML) algorithms in combination with imaging devices. This unit is adept at identifying and categorizing scrap assemblies into lots based on predefined criteria such as type, size, and shape. The system also includes a conveyor unit designed to efficiently transport materialsbetween various stages of the recycling process. The provided Al and ML algorithms integrated into an automated segregation unit, enhance the efficiency and accuracy of the magnetrecycling process. Utilizing advanced image recognition capabilities, pre-defined algorithms analyze data from imaging devices to identify and categorize scrap assemblies based on predefined criteria, including type, size, and shape. Continuously learning from incoming data and refining their models, the Al and ML tools adapt to variations in assembly types, sizes, and shapes, optimizing performance and ensuring consistent results. Moreover, the Al and ML algorithms enable real-time decision-making regarding the sorting and routing of materials, thereby contributing to the overall speed and effectiveness of the recycling process.

[0044] According to an embodiment of the present invention, the system further provided with , an adhesive removal unit is part of the system, which uses a high-pressure gas pressurizer and a mechanical agitator to effectively strip off adhesive residues. Following this step, a magnet-separating unit equipped with a vacuum suction duct is employed for the extraction of disintegrated adhesives and the complete detachment of magnets from the assemblies.

[0045] In addition, the invention encompasses a thermal treatment unit equipped with a variety of technologies including infra-red light, laser, ultraviolet heating, inductive heating, joule heating, and shock waves. This unit operates in either an inert or reduced atmosphere or vacuum, applying a thermal energy flash that demagnetizes the Nd-Fe-X-B magnets and facilitates their detachment from the scrap assemblies.

[0046] According to another embodiment of the present invention, a secondary segregation unit is enhanced with a composition analyzer. The analyzer utilizes non-destructive testing, including X-ray fluorescence (XRF) spectrometry, enabling rapid determination of each magnet's chemical composition. The capability is crucial for facilitating the sorting ofmagnets based on their heavy rare earth (HRE) element content, ensuring that the recycling process is both efficient and precise in producing recycled magnets with targeted / desired properties.

[0047] In a further embodiment, the automated segregation unit is refined to integrate size and shape recognition capabilities. This allows the unit to distinguish between different types of scrap materials, such as electric vehicle (EV) motors, hard disks, and windmill components, enabling targeted recycling processes that are tailored to the specific characteristics of each scrap type.

[0048] Another embodiment specifies that the thermal treatment unit is configured to maintain temperatures above the Curie temperature of Nd-Fe-X-B magnets, ranging from 25°C to 650°C. This temperature control is pivotal for achieving optimal demagnetization and adhesive disintegration, ensuring that the magnets are prepared for the subsequent steps of the recycling process without compromising their integrity.

[0049] According to yet another embodiment of the present invention, to enhance the magnetic properties of the recycled magnets, a specialized process is included. This process involves pulverizing the sintered magnets to a desired particle size range, blending them with secondary element / alloy powders, aligning the powder in a magnetic field, and subjecting the resultant green compacts to thermal heat-treatment. This meticulous procedure produces recycled magnets with significantly enhanced magnetic properties.

[0050] According to an embodiment of the present invention includes a coating stripping unit designed for the removal of surface coatings from the magnets. This unit utilizes, chemical, mechanical, mechano-chemical, thermal, supercritical CO2, and thermo-mechanical to efficiently remove various types of coatings, preparing the magnet surfaces for furtherrecycling processes. This step is essential for ensuring the purity and quality of the recycled magnets, making them suitable for a wide range of applications.

[0051] According to an embodiment of the present invention, the chemical method includes chemical reactions to corrode or dissolve the coating using the metal stripper chemicals such as nitric acid, sodium hydroxide, acetone, methylene chloride, dimethylformamide, toluene etc. The system consists of reaction vessel with top lid for placing the scrap magnets and bottom lid wherein a sieve is placed above the lid to drain the liquid.

[0052] According to an embodiment of the present invention, the mechanical method, abrasive particles such as sand, alumina are propelled by compressed air to remove the coating by means of wear or abrasion. This is called sand or abrasive blasting. A combined approach of mechanical and chemical method can be more effective for removing tougher coatings on magnets. Mechano-chemical process such as ultrasonic bath with a stripping solution can agitate the coating and help loosen it from the magnet surface, combining the mechanical energy of ultrasonic waves with the chemical action of the cleaning solution. Another method using ball milling with stripping solution, where the magnets are placed in a rotating drum with grinding media and stripping solution.

[0053] According to an embodiment of the present invention, the thermal process to remove surface coatings from magnets uses heat to decompose or break down the coatings in controlled atmosphere. Polymer or epoxy or resin like coatings can be removed adopting thermal process through controlled heating in a furnace or oven.

[0054] According to an embodiment of the present invention the supercritical CO2 method is very effective, and environmentally friendly to remove coatings from magnets, especially for polymer or epoxy or resin coatings. The method utilizing the unique properties of supercritical CO2 that combine the solvent-like properties of CO2 with the physicalcharacteristics of a gas, allowing for efficient coating removal without damaging the base magnet. The supercritical CO2 has the ability to penetrate coatings and dissolve, weaken or break down coatings, especially epoxy, resins, and polymers. The device is a pressure vessel with provision to introduce supercritical CO2 with high flow rate. Additionally, it is aided by mechanical agitation or ultrasonic waves within the vessel to facilitate effective removal. In some cases, solvents such as dimethylformamide, sodium hydroxide, acetone, toluene, methylene chloride etc are added to enhance the removal process. The process steps include placing magnets in a pressure vessel, introducing the supercritical CO2 and mechanical agitation.

[0055] According to an embodiment of the present invention, the method to remove metal coatings such as Ni, Ni / Cu / Ni, Zn, Cr from scrap magnets is described. This kind of coating removal involves thermo-chemical process using metal strippers. In brief, few kilograms of stripper powder are added to the deionized water in the stainless-steel tank with a heater-assembly. The solution is heated to 50- 60 °C, and then the scrap magnets are racked and immersed in the solution. The solution maintained at 50- 60 °C for 1 hr. The rate of removal is about 10-20 micron per hour. Once the coating is removed, the magnets are washed thoroughly using de-ionized water to clean the surface and dried in vacuum. This process is environmentally friendly and easy to handle without any toxic fumes. The same method can be used in the low-speed mechanical device or tumbling device to remove the coatings from the scrap magnets. Another method to remove the metal coating from the scrap magnets is by passing the magnets through a sand blaster line where blast materials such as sand, or AI2O3 are used. Then, these are cleaned with in an organic solvent such as acetone and dried in vacuum.

[0056] According to an embodiment of the present invention, a method for segregating randomly mixed scrap / used / rejected assemblies containing Nd-Fe-X-B magnets into lots based on the type of assembly / device, such as EV motors, hard disks, windmills, etc., is described. This process employs automated machines that operate based on artificial intelligence and machine learning tools in conjunction with imaging devices. The size and shape features are used to define a particular group for segregation into lots. This method ensures that waste magnets are converted into useful recycled magnets with minimum assured properties, depending on the starting scrap magnet grade and chemistry, or produce recycled magnets with improved performance by modifying the chemistry.

[0057] According to another embodiment of the present invention, a method is provided for detaching / separating Nd-Fe-X-B magnets from scraped assemblies / devices. This process involves subjecting assemblies to thermal energy flash, such as infra-red light, laser, ultraviolet heating, inductive heating, joule heating, or shock waves, in an inert or reduced atmosphere or in vacuum for a short duration of time. The temperature is maintained above the Curie temperature of the magnet, from 25°C to 650°C, for demagnetizing the magnet and rapidly quenching the assemblies to cryogenic temperatures. This step aids in disintegrating the adhesive, typically epoxy resin, that bonds the magnet to sub-assemblies, thus facilitating clean and easy removal of magnets.

[0058] According to another embodiment of the present invention, the assemblies that have undergone rapid heating cooling and quenching are exposed to high-pressure gas while the assemblies are undergoing mechanical vibrations / agitation / acoustic / ultrasound / shock wave / electromagnetic wave methods to knock out / remove / stripping off the fragmented epoxy resin / glue from the assemblies.

[0059] The accumulated epoxy resins are sucked using vacuum systems to separate them from assemblies. With the aid of magnet-separating device, the magnets are completely detached from the assemblies. The entire process is automated based on the machine learning / Al data approach in order to separate the magnets based on the size, shape, structure, type of coating and etc.

[0060] In an another embodiment of the present invention, an environmentally friendly method is provided for stripping coating on the magnets. This process includes various treatments such as chemical, mechanical, mechano-chemical, thermal, supercritical CO2, and thermo-mechanical treatments or combination of these at different temperatures and pressures, with or without inert gas atmospheres. The coatings, which may include Ni, Zn, Au, Al, Ni / Cu / Ni, Cr, Ag, epoxy resin, teflon, parylene, glue, plastic / ABS, or any other materials, are removed using the above said methods which also includes ultrasonic waves, electromagnetic, shock waves, and acoustic methods. This approach ensures the removal of impurities and contaminants, preparing the magnet surface for further recycling processes.

[0061] According to yet another embodiment of the present invention, a method is described for secondary separating scrap magnets into lots / groups based on their composition / chemistry automatically by employing machines that operate on artificial intelligence and machine learning tools. The composition of each scrap magnet is quickly measured by X-ray fluorescence (XRF) spectrometer or other non-destructive methods remotely and robotically in line with the process. This separation is crucial for converting waste magnets into useful recycled magnets with minimum assured properties or producing recycled magnets with improved performance by modifying the chemistry without melting the scrap magnets. The composition of the precursor determines the final properties of the recycled magnets. As per the embodiment, the segregation of scrap magnets based on composition isbased on the total content of the heavy rare earth (HRE) elements (Tb, Dy, Gd, Ho) in the magnets. The total HRE content in each of the scrap magnet is denoted by Y in weight percentage. The scrap magnets with Y range O<Y<1 is grouped into a single lot. Similarly, magnets with Y range 1<Y<2, 2<Y<3, 3<Y<4, 4<Y<5, 5<Y<6, 6<Y<7, 7<Y<8, 8<Y<9, and 9<Y<10 are grouped into respective lots.

[0062] In another embodiment of the present invention, a method is provided to prepare a sintered recycled R-Fe-B magnet with useful magnetic properties for device applications. This method includes the steps of pulverizing scrap magnets, blending with secondary element / alloy powder, aligning the powder in a magnetic field, and subjecting the resultant green compacts to thermal heat-treatment. The final magnetic properties of the recycled magnet depend on the initial composition of the scrap magnet and the secondary alloy composition, ensuring the production of high-quality recycled magnets suitable for various applications.

[0063] According to an embodiment of the present invention for sintered recycled R- Fe-B magnet, a method is provided for pulverizing demagnetized magnets to achieve a desirable average particle size range of 1 to 5 microns with a low oxygen concentration (<1000 ppm). This pulverization process may employ hydrogen reactive gas explosion, high-pressure gas milling, or mechanical milling techniques. The hydrogen reactive gas explosion turns the material into coarse powders, which are then further refined to the desired particle size through additional milling processes. The low oxygen concentration in the demagnetized magnetic material is achieved by removing nonmagnetic oxide phase material using a magnetic separation method or a sieve method when the size of the oxide phase material is larger than the average size of the R2Fei4B phase.

[0064] In another embodiment of the present invention, a method includes blending scrap magnet powder with secondary element / alloy powder to prepare a homogeneous powdersuitable for creating recycled sintered magnets. The selection of secondary additive is based on the initial scarp magnet composition and the final targeted magnetic properties to be achieved in the recycled magnets. The automatic selection of secondary additive is done by using AI / ML algorithms with predefined targeted magnetic properties. The secondary element / alloy powder is in a mass fraction between 0.5 to 25%. The secondary element / alloys, which may be based on rare earth hydrides (R-H) or rare earth alloys (R-Z) where R includes elements such as Nd, Pr, Tb, Dy, La, Ce, Gd, and Z includes elements like Fe, Co, Al, Ga, Cu, B, are milled under high pressure or mechanically to achieve fine powders with a mean particle size ranging from 0.5 to 5 microns. This homogenization process ensures a uniform distribution of secondary elements / alloy and scrap magnet powders.

[0065] According to a further embodiment of the present invention, a method for aligning the powder and pressing is provided. The mixed powder is filled in a rubber mold of a definite shape within a chamber filled with a protective gas atmosphere, such as argon and / or nitrogen. The mold filled with powder is subjected to a pulse magnetic field of intensity in the range of 2-4 Tesla to orient the particles along the field direction. This alignment process may be repeated 1-5 cycles. The rubber mold with aligned powder is then isostatically pressed in a liquid, preferably water-based, at a pressure of 1-3 kbar for 1-5 minutes to convert it into a green compact. In some implementations, the powder is filled in a nonmagnetic die and aligned in magnetic field of 2 T and compacted using uniaxial pressing. The pressed compacts are further isostatically pressed to improve the green compact density.

[0066] In a further embodiment, the powder is filled in a metallic / graphite molds with the magnet shapes required for the final application and aligned in a pulse magnetic field of 2- 4 T. The density of the green body in the mold was increased by vibration / automated tapping of the mold. In this particular implementation, no pressure was applied to the powders in themold. This method allows for the production of near-net shape magnets without applying pressure to the powders in the mold. The process was handled entirely in an inert atmosphere to avoid oxygen pick-up.

[0067] Another embodiment involves sintering the resulting green compact or molds filled with the powder at temperatures ranging from 900°C to 1130°C in a vacuum furnace under a protective atmosphere such as argon or vacuum for a period of 1 to 6 hours. After sintering, the sample is quenched with argon gas to a temperature below 200°C. This process is followed by a post-sintering heat treatment in the range from 450 °C to 900°C for 1 to 5 hours conducted under vacuum or protective atmosphere in two steps: initial tempering treatment and a second tempering treatment, cooling the samples to room temperature afterward.

[0068] According to an additional embodiment of the present invention, a method for producing recycled sintered magnets with a range of properties, including energy product from 25 to 48 MGOe and intrinsic coercivity from 10 to 30 kOe, is disclosed. These properties are at least the same as, or a maximum of 5% less than, those of the scrap R-Fe-B magnets. In some implementations, the coercivity of the recycled magnet is at least 40% higher than the value of the scrap magnets, with the remanence of the recycled magnet being the same as or at least 5-20% higher than that of another scrap magnet.

[0069] Furthermore, an innovative approach for preparing high resistivity sintered magnets is described. This involves coating the recycled powders with a thin layer of dielectric material using chemical or chemical vapor deposition or electrophoresis or alternate layer deposition processes. The precursor dielectric materials are either oxides, phosphates, glass, or fluorides or sulphides or combination of these materials. The thin surface coating of less than 500 nm coating encapsulates the rare earth magnet powders and is sintered using the standardsintering procedure as mentioned in the previous section. The dielectric precursor powder materials are amorphous / crystalline materials which undergoes a chemical reaction during sintering and converted into crystalline structure during the sintering process. The dielectric coating helps the magnets to reduce the eddy current loss and increasing the performance of the magnets in the devices. The other approach is that the dielectric materials were placed as layers at different thicknesses in the powder layers while preparing the green compact. The dielectric layer thickness varies between 0.1 micron and 1000 microns. The dielectric layer is either wet or dry or a slurry paste and incorporated as layers in the green compact. The entire process is carried out in an automated line in an inert atmosphere. The further alignment and sintering steps are same as described in the previous embodiments. The final product has 3 to 100 times electrical resistivity compared with the standard sintered R-Fe-X-B magnets. This high resistivity sintered recycled magnets suppress the eddy current loss and hence increase the overall efficiency of the devices for examples motors and generators.

[0070] In the further embodiment, a strategy for converting recycled magnets into high temperature magnets adopting grain boundary modification method is described. This involves diffusion of HRE and its alloys into the magnets. The sintered magnets were coated with HRE or its alloy hydride powders with a thick layer of 1-40 microns. The coated magnets were subjected to heat treatment process under vacuum better than 10'4milli bar to induce grain boundary diffusion process with temperatures maintained between 800 - 1000° C for 1 to 10 hours followed by annealing between 400 - 600° C for 1-5 hours. The process enhanced the coercivity of the recycled magnets with usage of less amount of HRE in making the magnets suitable for high temperature applications.

[0071] According to an embodiment of the present invention, a method is provided for producing R-Fe-X-B spherical powder from scrap magnets for additive manufacturing. Thepulverized powders of the scrap magnets are subjected to a plasma spheroidization process in an inert atmosphere, yielding spherical powders with a size range from 10 microns to 150 microns. This process is designed to produce powders with high density and sphericity, meeting the requirements for various additive manufacturing processes and enabling the production of additively manufactured magnets and bonded magnets with precise complex geometrical features.

[0072] In another embodiment of the present invention, scrap magnets are processed through melting in an induction furnace under a vacuum or inert atmosphere, followed by gas atomization and in particular, vacuum inert gas atomization to prepare precursor spherical powders for additive manufacturing. This technique generates spherical powders within the size range of 10 microns to 150 microns, suitable for additive manufactured magnets and bonded magnets for a wide range of applications.

[0073] Additionally, an embodiment of the present invention describes a process where scrap magnets are melted in an induction furnace under a vacuum or inert atmosphere and casted in the form of ribbons with high cooling rate, followed by mechanical milling or jet milling. This method produces powders with a size range from 50 to200 microns, facilitating the fabrication of bonded magnets with specific magnetic and physical characteristic tailored to specific use.

[0074] In another embodiment of the present invention describes a process for making bonded magnets with use of scrap magnet powders. The scrap magnet powders are mixed with epoxy / resin, followed by pressing / molding in the desired shape / size and curing.

[0075] According to further embodiments of the present invention related to additive manufactured (AM) magnets from the spherical powders made out of scrap magnets, various innovative approaches are detailed; The first aspect focuses on usage of powder bed fusion ordirect energy deposition methods to print / additively manufacture the magnets with custom sizes and shapes in inert gas atmosphere to avoid oxidation. The as-printed magnets undergo thermal treatment in the temperature range 500-1000° C for 1 to 5 hours to improve the magnetic performance. The second aspect introduces binder jetting or extrusion methods for making AM bonded magnets with required size and shape.

[0076] Additional aspects of the present invention include developing processes for creating isotropic and anisotropic sintered magnets and bonded magnets through additive manufacturing, and sintered magnet development focusing on high strength, thermal stability and high resistivity. Particle size distribution (PSD) control, uniform blending of powders, and the use of machine learning and artificial intelligence to reduce bottlenecks in magnet recycling are also highlighted.Embodiments

[0077] The following below embodiments demonstrate that the recycling of scrap magnets from mixed end of life assemblies / devices of different composition or grades into useful products such as high-quality recycled sintered and bonded magnets, rapidly solidified ribbon powders, spherical AM powders and AM magnets with tailored properties required for various applications.Embodiment 1

[0078] The mixed scrap assemblies and devices that contain R-Fe-X-B magnets are segregated into lots based on the type of device such as hard disk drive, electric vehicle motor, wind mill, industrial motors etc in automatic line using the artificial intelligence methods that use imaging devices. The size and shape features are used to define a particular group forsegregation into lots. Each lot is recycled independently to maximize the recycled product performance. In this particular embodiment, the industrial motor scrap is used for demonstrating the present invention.

[0079] The scrap magnets containing motors are loaded in a heating chamber and evacuated to reach vacuum of level 10'2mbar and continued the evacuation process to maintain vacuum. A thermal flash using infra-red heating was used to heat the assemblies rapidly to a temperature of 400°C and maintained the temperature for 10 min. The heated assemblies are rapidly cooled to temperatures below 30 °C using high pressure inert gas quenching. This process enabled demagnetization of the magnets and aided in disintegrating the epoxy adhesive and facilitated easy removal of magnets. Using the magnetic separating device, the motors are cut open and magnets are identified and detached from the assemblies / devices using the robotic arm. In this process, the disintegrated epoxy is effectively removed from the magnets by high- pressure gas pressurizer and a mechanical agitator. The detached magnets are subjected to the next step of coating / plating removal. The magnets had Ni coating on it. The magnets are placed in metal stripper liquids and heated to 50- 60 °C for 1 hr. This process removed the coating effectively, and then the scrap magnets are thoroughly cleaned with acetone using ultrasonic bath and dried in vacuum.

[0080] The composition of each scrap magnet is quickly measured by X-ray fluorescence (XRF) spectrometer inline in the process. The magnets have different compositions. The AI / ML tools are used to segregate the scrap magnets automatically into groups / lots based on the total content of the heavy rare earth (HRE) elements (Tb, Dy, Gd, Ho) in the magnets. The total HRE content in each of the scrap magnet is denoted by Y in weight percentage (wt%.). The scrap magnets with Y range x<Y<x+l(x=0-9) is grouped into different lots. For embodiment, magnets with Y content from 0 to 1 wt% is grouped into a single lot,and 1 to 2 wt% into another single lot and so on. Each lot with different Y content is recycled separately to prepare various grades or type of magnets, or AM powders to maximize the efficiency and effective use of recycled products. The average composition of each lot segregated based on Y content is shown in Table 1 for 3 different Y contents. The magnetic properties of few scrap magnets were measured for reference and average values are shown in Table 2. In the present embodiment, the scrap magnets lot A with Y content 0 to 1 wt% is further processed into recycled magnets to show the process of making recycled magnets. The scrap magnets lot, that are surface cleaned / coating removed, is placed in furnace chamber and created a vacuum in the chamber better than 5 x 10'2mbar. The scrap magnets were exposed to 1-2 bar of hydrogen gas at room temperature for hydrogenization for 1-4 hrs and then, heated the same in-situ to 450-550° C for 2-4 hrs for partial dehydrogenization while evacuating to vacuum followed by cooling to room temperature. After this process coarse powders were obtained with size range 20-300 micron. The coarse power was passed through a vibro-sieve to effectively remove the particles larger than 200 microns which are mostly oxide particles. This process helps to minimize the oxide fraction in the recycled magnet powder. Further, these powders were reduced to fine powders with mean particle size of 4 microns or less through high pressure jet mill using inert gas Nitrogen.

[0081] Separately, the secondary additive powder Nd hydride (Nd-H) was prepared by exposing the Nd to hydrogen at a pressure of 2.5 bar at room temperature for 1 hr to convert Nd into Nd hydride. The Nd hydride is ground by ball milling into a fine powder in organic solvents having particle size of less than 3 pm. The Nd hydride is blended with the scrap magnet powder using the V-cone blender mixer. The mass fraction of Nd hydride secondary element powder is varied from 1-4%.

[0082] The mixed powder was filled in rubber mould with tap density of 35% in a glove box with nitrogen atmosphere and oriented by applying pulse magnetic field of 3-4 Tesla repeatedly 1-5 times by changing the field direction. The resultant rubber mould was subjected to cold isostatic pressing at a pressure of 1.5-2 kbar. The pressed body was sintered at 1000 - 1110°C for 4 hrs in a high vacuum sintering furnace. Subsequent heat-treatment was done at 900°C for 2 h, and later at 500°C for 3h. The density of the sintered magnet was varied between 7.54 to 7.61 g / cm3. The recycled magnets thus prepared was characterized utilizing a hysteresis loop recorder. The magnetic properties of the recycled magnet are shown in Table 3.

[0083] The secondary element / alloy addition is primarily for the compensation of loss of rare earth in the form of oxide or grain boundary phase and in some cases for modifying the grain boundary phase and microstructure. This secondary alloy addition will aid in sintering process and formation of rare earth rich grain boundary phase. In some examples, the secondary element / alloy additive diffuses along the grain boundaries to restore the microstructure and composition of the recycled magnets. Therefore, the magnetic properties of the original scrap magnets may be restored or improved in the recycled magnets by the addition of small quantities of virgin secondary elements / alloys.Embodiment 2

[0084] In this embodiment, scrap lot A powders was utilized like in embodiment 1, but the secondary additive was changed to Dy-H instead of Nd-H. Added 1-4 wt% of Dy-H with the lot A scrap powder and prepared recycled sintered magnets. The remaining process was the same as in case of embodiment 1. The magnetic properties of the recycled magnets are shown in Table 4.Embodiment 3

[0085] The method of grain boundary diffusion on recycled sintered magnets is described in this embodiment to enhance the coercivity of the magnets. A recycled sintered magnet of thickness 5 mm (diameter of 50 mm) was coated with Dy-H powders using dip coating method. The average particle size of the Dy-H powder is 3 microns. The thickness of the coated layer is 30 microns. The coated magnets were subjected to heat treatment under vacuum better than 10'4milli bar to diffusion Dy into grain boundaries of sintered magnets at 900° C for 5 hours followed by quenching the samples to a temperature less than 100° C. A post diffusion annealing was performed at 500° C for 3 hours. This process enhanced the coercivity of the recycled magnets with usage of less amount of HRE in making the magnets suitable for high temperature applications. Similarly other HRE element hydrides, i.e. Tb-H powder was also used as diffusion source. The remaining process was the same as in case of Dy-H. The magnetic properties of the grain boundary diffused recycled magnets are shown in Table 5.Embodiment 4

[0086] The following embodiment illustrate the method of preparing the high resistivity recycled sintered magnets. In this embodiment, scrap lot A powders with mean particle size of 4 microns or less prepared through high pressure jet mill was utilized like in embodiment 1. Coating of scrap lot A powders with dielectric layer of CaF2 was performed by chemical method. Ca(NO3)2 and KF solutions were used as precursors for coating the layer of CaF2 on scrap magnetic powders. Scrap lot A powders were added into CafNOsh solutions with 5 mol / 1 concentration. The solution was subjected to intense stirring for 5 min. Then, KF solutions with the same concentration was gradually poured into the Ca(NO3)2 solution under continuous stirring for a time period of 40 min. After 40 min. of coating process, the solution mixture was washed with ethanol and dried in vacuum. The thicknesses of the CaF2 coating on scrap magnetic powder was in the range 200-300 nm. Separately, high resistivity secondary additive powder of Y2O3 with particle size of 400-500 nm was prepared using high energy ball milling of micron sized Y2O3 powder in organic solvent such as toluene. The ball milled powder was dried in vacuum. The Y2O3 and Nd hydride powders (particle size of less than 3 pm) were added to the scrap magnet powder coated with CaF2 layer. The mixture was then blended using the V-cone blender. The mass fraction of Nd hydride secondary element powder added was 2 wt.% of the scrap magnetic powder. The mass fraction of Y2O3 high resistivity secondary additive powder was 1 wt.% of the scarp magnetic powder.

[0087] The mixed powder was filled in rubber mould with tap density of 35% and oriented by applying pulse magnetic field of 3-4 Tesla repeatedly 3-5 times by changing the field direction. The resultant rubber mould is subjected to cold isostatic pressing at a pressure of 1.5-2 kbar. The pressed body was sintered at 1000 - 1130°C for 4 hrs in a high vacuum sintering furnace. Subsequent heat-treatment was done at 900°C for 2 h, and later at 500°C for 3h. The density of the sintered magnet was 7.52 g / cm3. The high resistivity recycled magnets thus prepared were characterized for magnetic and electrical properties. The obtained recycled magnet had electrical resistivity of 800-1000 pQ cm, which was about 340% increase compared to that of the uncoated recycled magnets (150-200 pQ cm). The value of the resistivity can be tailored by changing the thickness of CaF2 layer, and the amount of Y2O3 addition. The magnetic and electrical properties of the high resistivity recycled magnet are shown in Table 6.Embodiment 5

[0088] The method of producing rapidly solidified ribbon powders from the scarp magnets is described in this embodiment. In the present embodiment, the scrap magnets lot A is processed to produce rapidly solidified ribbon powders. The uncoated scrap magnets lot is placed in the crucible of melt spinner furnace. Virgin elements of Nd of 2 wt% was added to the scrap magnets to compensate the rare earth loss. A vacuum in the chamber better than 8 x10'4mbar is created and back filled the chamber with Argon gas to a partial pressure of 300 mbar. The scrap magnets are melted with the help of induction power and the molten liquid was ejected onto a rotating Cu wheel to form the rapidly solidified ribbons. The high cooling rate achieved in this process resulted in randomly oriented fine grain (20-70 nm) structure in the rapidly solidified ribbons. The obtained ribbons were crushed using ball mill or jet mill and produced the powders with particle size range 50-200 micron suitable for bonded magnet applications. The magnetic properties of the recycled rapidly solidified powder are shown in Table 7.Embodiment 6

[0089] The following embodiment illustrates the method of preparing the bonded magnets from the recycled scrap rapidly solidified powders. In this embodiment, rapidly solidified powders made from the scrap magnet lot A, as prepared in the embodiment 5, was used for manufacturing the bonded magnets. Rapidly solidified powders with particle size range 50-200 micron were mixed with thermosetting resin that consist of epoxy resin and hardening agent. The ratio of magnet powder and thermosetting resin is 80 volume % and 20 volume %. The mixed powder was injection moulded to the desired shapes and sizes. The obtained magnets are isotropic in nature. The magnetic properties of the recycled bonded magnet are shown in Table 8.Embodiment 7

[0090] The method of producing spherical powders from the scarp magnets is described in this embodiment. The spherical powders are required for additive manufacturing of magnets and bonded magnets. These powders are known as AM powders. In the present embodiment, the scrap magnets lot A is processed to produce spherical powders employing vacuum inert gas atomization process. The uncoated scrap magnets lot is placed in the crucible of vacuum inert gas atomizer furnace. Virgin elements of Nd of 2 wt% was added to the scrap magnets to compensate the rare earth loss. A vacuum in the chamber better than 8 x 10'4mbar was created. The scrap magnets are melted with the help of induction power in inert atmosphere of argon. The molten liquid was then poured in a tundish having a nozzle at the bottom of it. The liquid alloy was ejected through the nozzle. The ejected liquid was impinged with a highspeed inert gas argon to atomize and breakup the molten liquid into small droplets then solidified into spherical alloy powders. The obtained powders have high sphericity, narrow particle size distribution and low satellites with average particle size of 45 microns. By varying the process parameters inert gas pressure and nozzle size, powders with size ranging from 10- 150 microns were produced. These powders are called AM powders suitable for producing AM magnets and also bonded magnets for a wide range of applications.Embodiment 8

[0091] In this embodiment, another method of producing spherical powders, known as AM powders, from the scarp magnets is described. In the present embodiment, the scrap magnets lot A is processed to produce spherical powders employing plasma spheroidization process. The preparation of precursor powders required for the plasma spheroidization process is described here first. The uncoated scrap magnets lot is placed in furnace chamber and created a vacuum in the chamber better than 5 x 10'2mbar. The scrap magnets were exposed to 1-2 bar of hydrogen gas at room temperature for hydrogenization for 2-4 hrs and then, heated the same in-situ to 450-550° C for 2-4 hrs for partial dehydrogenization while evacuating to vacuum followed by cooling to room temperature. This process resulted in coarse powders with size range 50-300 micron.. Then, these powders were subjected to high pressure jet milling using inert gas Nitrogen to reduce the average size to 10-150 microns, more precisely 50 microns in this present case. These powders are later subjected to plasma spheroidization process. In this process, the powders are introduced into plasma zone where they melt partially or fully based on plasma temperature. As the molten particles are exposed to the plasma, surface tension causes them to form into spherical shapes. The level of spheroidization is controlled by the time duration of the plasma exposure. Once the particles attain the shape, they are cooled quickly by inert gas to solidify. Process parameters such as plasma plate power of 5-10 kW, feed rate of 0.5-1.5 kg / h, and plasma gas flow rate of 5-12 slpm were used in the experiment. The process yielded spherical powders with average size of 50-100 microns. The oxygen content in the powder is much less than the feed stock materials.Emodiment 9

[0092] The method of producing additive manufactured (AM) magnets from the spherical powders made out of scrap magnets is described in this embodiment. In this embodiment, spherical powders made from the scrap magnet lot A, as prepared in theembodiment 7, were used for preparing AM magnets. The laser powder bed fusion technique was used for 3D printing / AM magnets with custom sizes and complex shapes in inert gas atmosphere to avoid oxidation. The average particle size of the feed powders were 45 microns. To modify the grain boundary chemistry and micro structure to enhance the properties, 1-5 wt% of secondary alloy additive, R-Z where R includes elements such as Nd, Pr, Tb, Dy, La, Ce, Gd, and Z includes elements like Fe, Co, Al, Ga, Cu, B, was mixed with spherical powders made out of scrap magnets. In the present embodiment, 5 wt.% of Nd-Cu secondary alloy additive with average particle size 30 micron was mixed with the spherical powders. These powders were blended using the V-cone blender for 2 hours for uniform mixing. The mixture was used as feed stock for AM. The powder is placed into the chamber of the additive manufacturing device, present case laser powder bed fusion, filled with argon gas. The laser power and scanning speed were varied. The laser power varied from 150-350 W and scan speed varied from 200-900 mm / s. Samples of custom sizes and complex shapes were printed. The as- printed magnets undergo thermal treatment in the temperature range 500-1000° C for 1 to 5 hours to improve the magnetic performance. The AM magnets displayed isotropic magnetic properties. The magnetic properties of the recycled AM magnets are shown in Table 9.

[0093] These embodiments exemplify the comprehensive and innovative approaches of the present invention toward recycling scrap magnets into high-quality bonded and sinteredmagnets, additive manufactured magnets, and high-quality powders emphasizing sustainability, efficiency, and the potential for customization in magnet production.

[0094] These embodiments highlight innovative aspects of the present invention aimed at promoting the recycling of R-Fe-X-B magnets from scrap, employing environmentally friendly processes and enhancing the efficiency and sustainability of producing recycled magnets with desirable properties. The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and / or adapt for various applications such as specific embodiments without departing from the generic concept and therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments.

[0095] It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modifications. However, all such modifications are deemed to be within the scope of the claims.

Claims

We Claim:

1. A system for segregating and recycling R-Fe-X-B magnets (R is at least one or more elements from rare earths Nd, Pr, Tb, Dy, La, Ce, Gd, where X= other elements for example Co, Al, Ga, Cu, Zr, Nb, Ti, Mo, Mn, Si, Sn, C) from mixed scraps, the system comprising: an automated segregation unit, configured to employ artificial intelligence (Al) and machine learning (ML) algorithms in conjunction with an imaging device for identifying and categorizing scrap assemblies into lots based on predetermined criteria including type, size, and shape; a conveyor unit to move the material from various units; a thermal treatment unit including an infra-red light, laser, ultraviolet heating, inductive heating, joule heating, and shock waves in an inert or reduced atmosphere or vacuum for a thermal energy flash to demagnetize and facilitate the detachment of R-Fe-X-B magnets from assemblies. an adhesive and coating removal unit with a chemical, a high-pressure gas pressurizer and a mechanical agitator to strip off adhesive residues; a magnet-separating unit for the complete detachment of magnets; a secondary segregation unit, wherein the segregate processed material as per the composition; and a magnetizing unit, wherein the segregated material is magnetized.

2. The system for segregating and recycling R-Fe-X-B magnets from mixed scraps claim 1, further comprising of a secondary segregation unit configured with AI / ML algorithms and provided with a composition analyser for a non-destructive testing including X-rayfluorescence (XRF) spectrometry for the rapid determination of each magnet's chemical composition to facilitate separation of R-Fe-X-B magnets and sorting of R-Fe-X-B magnets based on heavy rare earth (HRE) element (Tb, Dy, Gd, Ho) content.

3. The system for segregating and recycling R-Fe-X-B magnets from mixed scraps claim 1, wherein the automated segregation unit machine learning algorithms integrates size and shape recognition capabilities to distinguish between different types of scraps such as electric vehicle (EV) motors, hard disks, and windmill etc. components for targeted recycling processes.

4. The system for segregating and recycling R-Fe-X-B magnets from mixed scraps claim 1, wherein the thermal treatment unit is configured to maintain assembly temperatures above the Curie temperature of R-Fe-X-B magnets, between 25°C to 650°C, for optimal demagnetization and facilitating detachment of magnets from assemblies.

5. The system for segregating and recycling R-Fe-X-B magnets from mixed scraps claim 1, for improving the magnetic properties of the recycled magnets the scrap magnets pulverized to a desired particle size range, blending with secondary element / alloy powders, alignment in a magnetic field, compaction, and thermal heat-treatment to produce recycled magnets with enhanced magnetic properties.

6. The system for segregating and recycling R-Fe-X-B magnets from mixed scraps claim 1, wherein the artificial intelligence algorithms employed in precise control of composition of recycled magnets while selection and sorting into lots and blending of secondary additive element / alloy to the scrap powder for realizing targeted magnetic properties.

7. The system for segregating and recycling R-Fe-X-B magnets from mixed scraps claim 1, wherein the coating stripping unit for the removal of surface coatings from the magnets utilizesmechano-chemical, chemical, thermal, supercritical CO2, thermo-mechanical and mechanical treatment.

8. A method for recycling R-Fe-X-B magnets from mixed scrap assemblies, the method comprising: segregating scrap assemblies into lots based on type, shape, size using an automated system employing artificial intelligence and machine learning tools in conjunction with imaging devices; subjecting the assemblies to thermal energy flash in an inert or reduced atmosphere or vacuum for demagnetization and adhesive disintegration; applying high-pressure gas and mechanical vibrations for adhesive removal; detaching the magnets from assemblies using a robot or mechanical device; stripping surface coating from the magnets; secondary segregating the processed material as per the composition; and magnetizing the segregated processed material.

9. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in claim 8, further comprises analyzing the chemical composition of each magnet via nondestructive methods, including X-ray fluorescence spectrometry, and sorting the magnets into lots / groups based on heavy rare earth (HRE) element content for further processing into recycled magnets.

10. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in claim 8, wherein the scrap magnets are grouped into lots with Y range 0<Y<l,l<Y<2, 2<Y<3, 3<Y<4, 4<Y<5, 5<Y<6, 6<Y<7, 7<Y<8, 8<Y<9, and 9<Y<10 for further processing each lotseparately into recycled magnets with targeted properties, where Y is total HRE content (in weight percentage) in each of the scrap magnet.

11. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in claim 8, wherein thermal energy flash includes maintaining the temperature above the Curie temperature of Nd-Fe-X-B magnets to ensure efficient adhesive disintegration and demagnetization of the magnet.

12. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in claim 8, wherein the preparation of recycled magnets with enhanced magnetic properties comprising of pulverizing scraped demagnetized magnets, blending with secondary element / alloy powders, aligning the mixed powder in a magnetic field, compaction and subjecting the resultant green compacts to thermal heat-treatment.

13. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in 12, wherein the content of the secondary element / alloy powder added to the scraped magnet powder is in a mass fraction between 0.5 to 25%, wherein the secondary element / alloys are based on rare earth hydrides (R-H) or rare earth alloys (R-Z) where R includes elements such as Nd, Pr, Tb, Dy, La, Ce, Gd, and Z includes elements like Fe, Co, Al, Ga, Cu, B, wherein the selection of secondary additive to be added with the scrap magnetic powder for realizing the predefined targeted magnetic properties in the final recycled magnets is carried out by the AI / ML algorithms with given database of composition and properties of scrap magnets as well as secondary additive.

14. The method for recycling R-Fe-X-B scrap magnets from mixed scrap assemblies as claimed in claim 12, wherein the preparation of recycled R-Fe-X-B magnets further includes coatingthe recycled powders with a thin layer of dielectric material using processes such as chemical vapor deposition or electrophoresis or layers of dielectric materials were placed at different thicknesses in the powder while preparing the green compacts to increase the resistivity and reduce eddy current loss in the final recycled magnets.

15. The method for recycling of R-Fe-X-B magnets of claim 14, wherein the final high resistivity recycled R-Fe-X-B magnets exhibit electrical resistivity 3 to 100 times higher than that of standard sintered R-Fe-X-B magnets.

16. The method for recycling of R-Fe-X-B magnets of claim 12, where preparation of green compact from the mixed powder to manufacture the recycled magnets comprises: aligning the powder by pulse magnetic field strength of 2-4 T with change in field polarity alternatively for improved magnetic orientation, compaction of aligned powders by cold isostatic pressing in a pressure range of 1.5-2 kb ar.

17. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in claim 12, wherein the preparation of recycled R-Fe-X-B magnets further includes sintering the green compacts at 1000 - 1110°C for 2-4 hrs in a high vacuum followed by a heat-treatment at 800-900°C for 2-4 h, and later at 400-600°C for 2-3 h.

18. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies as claimed in claim 12, wherein the preparation of recycled R-Fe-X-B magnets further includes diffusion of HRE elements or its alloys into the recycled magnets through grain boundaries to enhance the coercivity as a result temperature capability of the recycled magnets while using less amount of critical HRE elements.

19. The method for recycling of R-Fe-X-B magnets of claim 18, wherein the grain boundary diffused recycled sintered magnets show coercivity at least 30% higher than the correspondingrecycled magnets, and contains 30-50% less HRE content compared to the conventional processed R-Fe-X-B magnets.

20. The method for recycling of R-Fe-X-B magnets of claim 12, wherein the energy product and coercivity of the recycled R-Fe-X-B magnets is at least the same as the scrap magnets, or a maximum of 5% less than those of the scrap magnets or in some implementations, the coercivity of the recycled magnet is at least 30% higher than the value of the scrap magnets, with the remanence of the recycled magnet being the same as or at least 5-20% higher than that of another scrap magnet.

21. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies of claim 8, further comprises producing near net shaped recycled magnets where the process comprises of: filling the scrap magnetic powder in a metallic / graphite molds with the magnet shapes required for the final application, vibration / tapping of the mold for uniform packing of powder, aligning the powder in a pulse magnetic field of 2-4 T, sintering the molds with powder in vacuum at 900 - 1110°C for 2-4 hrs, post-sintering at 400-600°C for 2-3 h.

22. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies of claim 8, further comprising of producing spherical powder with a size range from 10 microns to 150 microns for additive manufacturing and bonded magnet applications, wherein the process is carried out by plasma spheroidization or inert gas atomization.

23. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies of claim 8, further comprises producing rapidly solidified ribbon powders with a size range from 50 to 200microns for bonded magnet applications, wherein the process is carried out by rapid solidification followed by mechanical milling or jet milling.

24. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies of claim 8, further comprises producing additive manufactured magnets with various geometries, wherein powder bed fusion, direct energy deposition, binder jetting or extrusion methods used.

25. The method for recycling R-Fe-X-B magnets from mixed scrap assemblies of claim 8, further comprises producing bonded magnets with various geometries, wherein injection moulding used.

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