Rare Earth Extraction from Permanent Magnets
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Solution Overview
Problem
Current methods for recycling rare earths from permanent magnets in waste electrical and electronic equipment are inefficient due to safety concerns with chlorine or fluorine gas, high energy expenditure, and difficulties in separating rare earths from iron, making them costly and unsuitable for massive forms of magnets.
Innovation Solution
A process involving heat treatment above the Curie temperature, controlled grinding to select particles less than 2 mm, treatment with an organic acid solution for dissolution, and separation of the liquid phase to extract rare earths, which includes demagnetization and selective precipitation of iron to isolate rare earths effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If direct chlorination or fluorination is used to recover rare earths from magnets, then rare earth extraction is achieved, but safety risks increase due to the dangerousness of chlorine or fluorine gas circulation
Solution Approach 1:
The patent replaces dangerous halogen gases (chlorine, fluorine) with organic acids to perform the extraction function. The harmful chemical agents are substituted with safer reagents (acetic acid, oxalic acid, citric acid) that achieve the same rare earth dissolution and separation objectives without the safety hazards of gas handling, storage, and circulation infrastructure
Solution Approach 2:
The patent introduces an organic acid as an intermediary substance to mediate between the magnet material and the rare earth extraction process. Instead of directly using hazardous halogen gases, the organic acid serves as a safe intermediate agent that dissolves the magnet components and enables rare earth separation through controlled chemical reactions
2Productivity
If melting process is used to recycle rare earths from magnets, then rare earth recovery is achieved, but energy expenditure increases leading to high cost
Solution Approach 1:
The patent fundamentally changes the operational parameters from high-temperature melting (requiring thousands of degrees) to moderate-temperature acid treatment (room temperature to moderate heating). This parameter change transforms the process from energy-intensive thermal treatment to chemical dissolution, dramatically reducing energy consumption while maintaining effective rare earth recovery
Solution Approach 2:
The patent replaces the mechanical/thermal melting system with a chemical dissolution system. Instead of using thermal energy to melt and separate materials, the process uses chemical reactions with organic acids to selectively dissolve magnet components, enabling separation through chemical rather than thermal mechanisms
3Productivity
If aluminothermy reaction is used to extract rare earths from magnets, then rare earth separation is achieved, but process complexity increases due to delicate management requirements
Solution Approach 1:
The patent extracts and removes the complex aluminothermy reaction step from the process. Instead of using the complicated multi-step aluminothermy method with its delicate management requirements, the patent directly applies organic acid treatment to achieve rare earth separation, eliminating the need for complex intermediate reactions and management procedures
Solution Approach 2:
The patent inverts the conventional approach by not using aluminothermy reduction followed by separation, but rather directly dissolving the magnet in organic acid to achieve separation. This inversion simplifies the process by eliminating the need for complex reduction reactions and their associated management challenges
4Productivity
If magnet powder is ground and treated with acid solution, then rare earth dissolution is achieved, but separation from iron becomes difficult
Solution Approach 1:
The patent applies local quality by selecting organic acids with specific chemical properties that selectively interact with rare earth elements versus iron. The organic acids (acetic, oxalic, citric) have specific binding affinities that enable selective dissolution and complexation of rare earths, creating local chemical environments that favor rare earth separation from iron through controlled precipitation or extraction
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This process achieves over 70% extraction of rare earths with reduced energy expenditure and safety risks, allowing for efficient recycling of rare earths from NdFeB type magnets, including those with added rare earths like Dy and Pr, while minimizing the dissolution of coatings like nickel.
Implementation Method 1
heat treatment of the permanent magnet at a temperature greater than or equal to its Curie temperature
Implementation Method 2
treatment with stirring of the particles selected at the end of the grinding step with a solution containing an organic acid
Implementation Method 3
separation of the liquid phase from a possible solid phase at the end of the treatment with the solution containing the acid
Data Source
Figure 1
Figure 2a~3
Figure 4~5
AI summary
The invention relates to a method for extracting rare earth elements contained in permanent magnets, which comprises the steps of thermal treatment of the permanent magnet, crushing at the end of the thermal treatment in order to obtain particles with a size smaller than 2 mm, treatment by agitation of the particles in a solution containing an organic acid, and separation of the liquid phase from the solid phase.