Eddy-Current Separator Magnet System Pole Sequence
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Eddy-current separators face challenges in efficiently separating small particles and weakly magnetizable metals due to premature particle interaction and high costs associated with rare earth magnets, leading to reduced throughput and separation accuracy.
Innovation Solution
A device with a fixed magnet system arranged in a rotating drum, where the magnet poles are sequenced as NS SN or SN NS, creating a higher radial to tangential magnetic flux density ratio, allowing for effective separation of electrically conductive particles by radial force and avoiding weakly magnetizable particles from adhering to the magnet system, thus enhancing separation efficiency and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rotating pole wheel with permanent magnets is used for eddy-current separation, then electrically conductive particles can be separated by induced eddy currents, but the device incurs high costs due to rare earth magnets and high-speed rotation requirements
Solution Approach 1:
Instead of rotating the magnet system at high speeds to induce eddy currents, the patent inverts the approach by using a stationary magnet system and rotating the conveyor belt with particles at high speed (2-6 m/s). This inversion eliminates the need for expensive rare earth magnets and high-speed rotor mechanisms while maintaining effective eddy-current separation
Solution Approach 2:
The patent extracts the magnet system from the rotating component and fixes it stationary in the drum structure. Only the conveyor belt with particles rotates, removing the expensive rotating magnet assembly and its associated high-speed rotation requirements while preserving the separation function
2Measurement precision
If the magnet system is arranged to maximize magnetic flux density for effective separation, then separation accuracy improves, but weakly magnetizable particles adhere to the magnet system reducing throughput
Solution Approach 1:
The patent applies local quality by creating different magnetic flux density conditions in different spatial regions. The magnet system is positioned and configured to generate high radial flux density at the belt surface for effective eddy-current separation, while the stationary arrangement prevents weakly magnetizable particles from adhering, as they are not exposed to prolonged magnetic fields
Solution Approach 2:
The high-speed rotation of the conveyor belt creates periodic exposure of particles to the magnetic field. Electrically conductive particles experience sufficient eddy-current induction during their brief passage, while weakly magnetizable particles are not given time to adhere, maintaining high throughput
3Measurement precision
If the relative speed between particles and magnet system is increased to induce eddy currents in small particles, then separation of small particles improves, but particle-particle interactions increase randomizing trajectories
Solution Approach 1:
The patent creates a controlled magnetic field environment that induces eddy currents in particles without requiring high relative speeds. The stationary magnet system with optimized pole arrangement generates sufficient magnetic flux density to induce eddy currents in small particles while they move at moderate conveyor speeds, avoiding trajectory randomization
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 solution achieves high throughput and precise separation of non-ferrous metals, non-metals, and weakly magnetizable constituents, minimizing particle-particle interactions and maintaining high separation success rates while reducing construction and material costs by eliminating the need for costly high-speed rotor components.
Implementation Method 1
the alternating magnetic field of the rapidly rotating pole wheel induces eddy currents in electrically conductive particles, as a result of which they themselves form a magnetic field, which is in the opposite direction to the original one, and a repelling force action therefore results
Implementation Method 2
the alternating magnetic field of the rapidly rotating pole wheel induces eddy currents in electrically conductive particles
Implementation Method 3
the magnets of the at least one magnet line are arranged such that their poles have the sequence NS SN or SN NS in the circumferential direction, with the result that the ratio of the maximum radial magnetic flux density to the maximum tangential magnetic flux density on the belt surface in the region of the magnet system is greater than one
Data Source
AI summary
A device for separating a metalliferous, lumpy mixture, with a conveyor belt and with a rotating drum in which a fixed magnet system with at least one magnet line is arranged. The separating effect of the device is improved and its complexity is reduced where it is provided that the magnets of the at least one magnet line are arranged such that their poles have the sequence NS SN or SN NS in the circumferential direction, as a result of which the ratio of the maximum radial magnetic flux density to the maximum tangential magnetic flux density on the belt surface, facing the material, in the region of the magnet system is greater than one and, owing to this, the electrically conductive particles are separated out into the first partial stream by radial force action (repulsion).