Permanent Overband Magnetic Separators
A permanent overband magnetic separator is suspended above a conveyor belt — either in line with the belt or across it — to continuously extract tramp iron from the material flowing below. The overband has its own short conveyor belt wrapped around a magnet block; as iron pieces are lifted up out of the material burden by the magnetic field, the overband's own belt carries them sideways and discharges them into a collection bin, well clear of the main product stream. The result is continuous, automatic, self-cleaning iron removal — protecting crushers, mills, kilns, screens, and other downstream equipment from damage by tramp metal.
Mitool Equipments manufactures permanent overband magnetic separators in both ferrite and rare-earth configurations, with magnet block sizes and lift heights customised to the conveyor belt width, material burden depth, and expected tramp size at each customer's installation. They are the standard choice in mining, cement, sponge iron, recycling, glass, ceramics, and foundry applications wherever heavy tramp iron must be removed reliably from a busy conveyor.
• Working principle
The overband consists of a powerful permanent magnet block, an enclosing housing, and a short cleaning belt that wraps around the magnet and runs continuously on its own motorised drive pulleys. The unit is suspended above the main product conveyor with adjustable suspension chains or a steel framework, at a height such that the magnetic field penetrates the material burden and reaches the iron pieces.
As tramp iron is attracted upwards out of the material, it sticks to the cleaning belt. The cleaning belt's motion then carries the iron sideways, away from the magnet's field zone, and finally — once it has cleared the magnet — the iron drops off the belt by gravity into a dedicated collection chute or bin. The product on the main conveyor continues forward, now cleaned of tramp metal.
• Configurations
In-line overband (parallel to the conveyor belt)
Overband oriented in the same direction as the main conveyor belt. Iron is captured and carried in the same direction as material flow, discharged off the front or rear end of the overband. Simplest configuration when there is enough conveyor length to position it.
• Cross-belt overband (across the conveyor belt)
Overband oriented at 90° to the main conveyor belt. Iron is captured and carried sideways, discharged off one end of the overband to either side of the main conveyor. Preferred where the main conveyor is short or where the iron collection bin must be located beside the conveyor rather than at the end.
• Self-cleaning vs manual-cleaning
All Mitool overband separators are self-cleaning by default — the continuously moving cleaning belt makes them so. The "manual-cleaning" variant (simply a suspension magnet without a cleaning belt) is covered separately on the Suspension Magnet page.
• Working principle
| Parameter | Range |
|---|---|
| Magnet Type | Ferrite Ceramic / NdFeB Rare Earth |
| Magnet Block Size (Length × Width) | Custom — Sized to Conveyor Belt Width and Burden Depth |
| Working Gap (Magnet Face to Material) | 150 mm – 450 mm (Typical) |
| Cleaning Belt Width | Slightly Wider Than Magnet Block |
| Cleaning Belt Drive | Geared TEFC Motor with Chain or Direct Drive |
| Suspension | Chain-Suspended or Framework-Supported |
| Housing | Heavy Gauge MS, Painted; SS Optional for Corrosive Environments |
| Cleaning Belt Material | Reinforced Rubber with Raised Cleats |
| Voltage | 415 V, 3-Phase, 50 Hz (For Cleaning Belt Drive) |
| Configuration | In-Line / Cross-Belt |
• Industries & applications
- Mining & mineral processing: ore conveying — protection of primary and secondary crushers
- Cement plants: limestone, clinker, and additive conveying — protection of mills
- Sponge iron plants: raw material feed conveyors — kiln protection
- Power plants: coal handling — protection of pulverisers and feeders
- Recycling: MSW, construction & demolition waste, glass cullet, plastic and rubber recycling — ferrous recovery and downstream equipment protection
- Foundry & steel mill: scrap handling conveyors, sand reclamation belts
- Quarry & aggregate: crushed stone conveyors before fine crushers
- Glass & ceramics: raw material handling — protection of product quality
• Advantages of Mitool overband separators
- Continuous self-cleaning: no manual cleaning required during normal operation
- Effective for heavy and deep tramp: high field strength plus close working gap captures large iron pieces
- Wide configuration options: in-line or cross-belt to suit any plant layout
- Permanent magnet: no power consumption by the magnet itself — only the cleaning belt drive uses electricity
- Rugged construction: designed for dusty, hot, vibrating environments
- Adjustable working gap: suspension chains or framework allow the working gap to be tuned to the actual burden depth
Frequently Asked Questions
A. Both are mounted above a conveyor belt. A suspension magnet is a stationary magnet block — captured iron sticks to its face and must be removed by stopping the line and manually cleaning. An overband magnetic separator has its own cleaning belt that continuously sweeps captured iron sideways and discharges it into a separate bin — fully automatic, with no manual intervention required.
A. The "working gap" between the magnet face and the top of the material burden is critical. Typical working gaps are 150–450 mm depending on magnet strength and tramp iron weight. A larger gap allows deeper material cleaning, but field strength at the iron is lower. Mitool engineers will calculate the optimum working gap for your specific application.
A. Neither is inherently better; it depends on plant layout. Cross-belt configuration is more compact and suits short conveyors. In-line configuration allows the magnet to be longer, providing more dwell time in the magnetic field, which can improve capture of small or deep tramp iron.
A. The cleaning belt is a reinforced rubber belt with raised cleats, driven by a small geared motor. Maintenance is similar to any short industrial conveyor — including belt tension checks, drive motor greasing, and belt replacement at the end of its service life (typically 2–5 years of continuous operation depending on tramp severity).
A. Yes — for high-temperature applications, the magnet block can be heat-shielded and ferrite magnets (instead of NdFeB) are used. For wet or dusty environments, sealed housings and corrosion-resistant materials are specified. The operating environment must be confirmed at the enquiry stage.
