Rare-Earth Magnet Powder Classification for Impurity Removal
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Solution Overview
Problem
Existing methods for producing starting materials for rare-earth magnets are costly and inefficient due to the presence of impurities such as oxygen, nitrogen, and carbon, which degrade the magnetic properties and corrosion resistance of the magnets, and often require scarce and expensive rare-earth metal alloys.
Innovation Solution
A method involving the comminution of magnetic materials into a powdered intermediate product, followed by classification using a dynamic classifier to separate impurities into two fractions, with the second fraction being used as a starting material for rare-earth magnets, and optionally using auxiliary substances to minimize impurity absorption during comminution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If scrap magnets are used as raw material for rare-earth magnets, then resource utilization is improved and costs are reduced, but impurity content increases which degrades magnetic properties and corrosion resistance
Solution Approach 1:
The patent extracts and removes impurities (oxygen, nitrogen, carbon) from the powdered intermediate product through a classification process. The dynamic classifier separates particles based on size, with finer particles containing higher impurity concentrations being removed as reject material, while cleaner larger particles are retained as starting material for rare-earth magnets.
Solution Approach 2:
The patent changes the particle size distribution parameter through controlled comminution and classification. By adjusting the particle size cutoff in the dynamic classifier, the process optimizes the balance between impurity removal and material utilization, producing a starting material with controlled impurity levels suitable for high-performance magnets.
2Manufacturing precision
If conventional comminution techniques are used to produce fine powder, then particle size is reduced to desired range, but impurity absorption from environment increases
Solution Approach 1:
The patent conducts the comminution process in an inert atmosphere (nitrogen or argon) to prevent oxidation and absorption of atmospheric impurities by the rare-earth metal powder. This protective atmosphere maintains low impurity levels throughout the particle size reduction process.
Solution Approach 2:
The patent implements a continuous process where comminution, classification, and collection occur in sequence without exposing the powder to atmospheric conditions. The inert atmosphere is maintained continuously throughout the process, and the classified powder is immediately collected and protected, minimizing exposure time and impurity absorption.
3Manufacturing precision
If dynamic classifier is used to separate impurities, then starting material purity is improved, but process complexity increases
Solution Approach 1:
The patent replaces complex chemical purification methods with a mechanical classification system. The dynamic classifier uses aerodynamic forces and particle size separation to remove impurities, avoiding the need for chemical treatments, multiple processing steps, and complex control systems while achieving high purity starting material.
4Object-affected harmful factors
If protective gas atmosphere is used during fine grinding, then impurity absorption is reduced, but production costs and process complexity increase
Solution Approach 1:
The patent combines the comminution and classification operations into an integrated process flow within a single inert atmosphere environment. The protective gas atmosphere is established once at the beginning and maintained throughout all operations, eliminating the need for separate protective measures at each stage and reducing overall process complexity.
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
The method effectively reduces impurities to a negligible level, producing a homogeneous starting material that enhances the magnetic properties and corrosion resistance of rare-earth magnets, thereby optimizing the production process and reducing costs.
Implementation Method 1
the powdered intermediate product is classified according to at least one criterion, in particular by particle size, by at least one dynamic classifier, which divides the powdered intermediate product into at least two fractions
Data Source
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AI summary
A process and an apparatus for producing a powdered starting material (AM) intended for the manufacture of rare-earth magnets are disclosed. First, at least one magnetic material (M) and/or at least one rare-earth metal alloy, containing a low concentration of impurities, is provided, which is then comminuted into a powdered intermediate product (ZP) with a potentially higher concentration of impurities.The powdered intermediate product (ZP) is then classified according to at least one criterion, wherein at least one dynamic classifier is provided for the classification of the powdered intermediate product (ZP) with the increased concentration of impurities, which divides the powdered intermediate product (ZP) with impurities into at least two fractions (F1, F2) according to the at least one criterion, wherein at least a high concentration of impurities accumulates in a first fraction (F1) and no impurities or at least a lower concentration of impurities than in the first fraction (F1) accumulates in a second fraction (F2), and wherein the fraction without impurities or with a low concentration of impurities forms the starting material for the production of rare-earth magnets.