2. 11. 2023
Separation of magnetic and non-magnetic metals in a municipal incineration plant (case study)
Our client, a large municipal incineration plant, was building a new waste sorting line. The client wanted to separate ferrous and non-ferrous metals from municipal waste in order to recycle and reuse them.
On the newly built municipal waste sorting line, it was necessary to separate metal materials from the household waste transported with a belt conveyor of 1,000 mm. As a specialized manufacturer of magnetic and non-magnetic metal separators, we were approached to offer our technology for this line.
The needed separation system should be fully automatic (i. e., requiring no human operators) and its control system had to be fully compatible with the control system of the entire separation line.
The first step was to remove ferromagnetic particles:
That is why we proposed to use a self-cleaning overband magnet suspended over the conveyor belt. The advantage of this type of magnetic separator is that it lifts and automatically removes ferrous metal from the conveyed material.
We have chosen the most powerful model of the DND-AC Mx3 F BEAST overband magnet, whose unique properties include:
- Suspension height up to 450 mm
- Max. conveyor belt speed up to 3 m/s
The second step was to separate the non-ferrous metals:
The basic condition for the successful separation of non-magnetic metals is the previous removal of iron particles (this was done in the 1st step).
The non-ferrous metals can be separated by special magnetic separators based on eddy currents. That is why these separators are called eddy current separators (or non-ferrous metal separators). They include a magnetic cylinder (rotor) with very strong magnets, which at high revolutions (when the magnetic poles alternate rapidly) creates a magnetic field that magnetizes even non-ferromagnetic metallic materials for a short term.
The magnetic polarity of the particles magnetized in this way is the same as the polarity of the magnetic field created by the separator rotor. Therefore, magnetized materials are repelled and automatically ejected out of the conveyor belt.
There are two main types of eddy current separators:
- Separators with concentric magnetic rotors (ECS-C RAM) - These separators are designed for the separation of larger metal pieces (from 50 mm). They are therefore suitable for the treatment of e. g. municipal waste. The advantage is their lower price and high processing capacity. The rotor comprises 4 magnetic poles.
- Separators with eccentric magnetic rotors (ECS-E BULL) - Thanks to their design, they allow the induction of a strong magnetic field and are thus suitable for the separation of even very small metal particles (from 5 mm).
Since it was necessary to separate non-ferrous metal pieces larger than 50 mm, we chose the ECS-C 1500 RAM separator with a concentric magnetic rotor.
A precondition for the successful separation of non-ferrous metals is a uniform distribution of the treated material on the ECS separator belt. Therefore, we designed a 1,500 mm wide separator that should on the one hand reduce the thickness of the material layer and on the other hand better spread the material on the separator belt.
Benefits of using the eddy current separator ECS-C 1500 RAM together with the overband magnet DND-AC Mx3 F BEAST:
By using the most powerful overband magnet DND-AC Mx3 BEAST, we were able to separate ferromagnetic particles and achieve the material purity needed for the downstream application of the eddy current separator.
The eddy current separator ensures the separation of non-ferrous metals from municipal waste. Thanks to the favorable price of ECS-C RAM, the return on investment is very attractive.
The customer is satisfied with our solution - we were able to separate ferrous as well as non-ferrous objects from municipal waste, thereby enabling further efficient sorting of this waste.
Advantages of the eddy current separator ECS-C 1500 RAM
- Separation of metal particles from 50 mm
- Concentric rare earth rotor
- Magnetic rotor comprising 4 poles
- Working widths from 500 to 2 000 mm
Advantages of the self-cleaning overband magnet DND-AC Mx3 F BEAST
- Automatic cleaning without the interruption of the material flow
- Suspension height up to 450 mm
- Separation of magnetic particles from 0,5 mm
- Max. conveyor belt speed: 3 m/s
- 10-year warranty
- All-stainless steel design
- No dead spots between the magnetic core and separator cover
- Weight from 440 kg - easy installation
- Magnetic flux density of 1010 G (at the distance of 200 mm from separator belt)
- Ferrite as well as light neodymium variants