Permanent Suspension Magnets
A permanent suspension magnet is the simplest, lowest-cost form of above-conveyor iron extraction. A heavy-duty permanent magnet block — ferrite or rare-earth — is suspended above a conveyor belt by chains or a fixed framework. As material flows below, ferrous particles in the burden are attracted upward and stick to the magnet's face plate. Periodically the magnet is moved away from the conveyor (or the conveyor stopped) and the accumulated iron is manually cleared. Despite the manual cleaning requirement, suspension magnets remain the right answer in many applications because of their unmatched simplicity, robustness, and total absence of moving parts.
Mitool Equipments manufactures permanent suspension magnets in a wide range of sizes — from compact units protecting short FMCG or food handling conveyors, to massive blocks suspended above heavy mining and cement plant belts. Both ferrite and rare-earth versions are available, with the magnet block sized to the conveyor belt width, working gap, and expected tramp iron size at each customer's installation.
• Working principle
The suspension magnet is mounted above a conveyor belt at a calculated working gap — typically 150–400 mm between magnet face and top of material burden. The magnetic field penetrates the burden, attracts ferrous particles upwards out of the material, and holds them against the magnet's face. As long as the magnet is positioned correctly and the burden is within design depth, ferrous extraction is continuous and reliable.
Cleaning is by manual removal — periodically (depending on tramp iron loading, typically once per shift or once per day) an operator stops the line, swings the magnet away or covers the face with a stripper sheet, and removes the accumulated iron. For high tramp loading, the self-cleaning overband variant is preferred — see the dedicated Overband Magnetic Separator page.
• Construction
- Magnet block: ferrite ceramic or NdFeB rare-earth magnets stacked and arranged for maximum field at the working face
- Pole plate (face plate): wear-resistant mild steel or stainless steel, replaceable
- Housing: heavy-gauge MS welded enclosure, fully sealed against dust and moisture
- Suspension: chain hangers with adjustable links, or fixed steel framework, for accurate height adjustment
- Lifting eyes: for safe installation and periodic cleaning
- Optional stripper plate: manual lever-operated stripper for easier iron removal
• Suspension magnet specifications
| Parameter | Range |
|---|---|
| Magnet Type | Ferrite Ceramic / NdFeB Rare Earth |
| Face Plate Size | Custom — Matched to Belt Width (Typically 600 mm – 2400 mm Wide) |
| Working Gap (Face to Material) | 150 mm – 400 mm (Typical) |
| Field Strength at Working Face | Ferrite: 800 – 1500 G; NdFeB: 1500 – 3000 G (At Working Gap) |
| Housing Material | MS Painted / SS-304 (Corrosive Environments) |
| Suspension | Chain Hangers (Adjustable) or Fixed Framework |
| Cleaning | Manual — Periodic Swing-Away or Stripper Plate |
| Cleaning Frequency | Once Per Shift to Once Per Day (Application Dependent) |
| Power Requirement | Zero (No Motor or Electrical Connection Required) |
• When to choose a suspension magnet vs an overband
| Choose Suspension Magnet When... | Choose Overband When... |
|---|---|
| Tramp iron loading is light and predictable | Tramp iron loading is heavy or unpredictable |
| Periodic shutdown for cleaning is acceptable | Production cannot be stopped for cleaning |
| Lowest capital cost is the priority | Continuous self-cleaning operation is required |
| No electrical supply is available at the location | Electrical supply for cleaning belt drive is available |
| Conveyor handles relatively clean material | Conveyor handles dirty or recycled material with heavy tramp |
| Manual labour is available for cleaning | Operator labour needs to be minimised |
• Industries & applications
- Cement plants: raw mill feed, clinker conveying
- Mining & quarry: ore and aggregate conveying
- Power plants: coal handling lines
- Foundry: moulding sand return belts, scrap conveying
- Food processing: grain, sugar, salt, spice conveying (sanitary SS construction)
- Chemical & fertiliser: granular product handling
- Recycling: as a low-cost protection magnet ahead of an overband for heavier tramp
- Glass, ceramics: raw material conveying
• Why choose Mitool suspension magnets
- No moving parts: nothing to wear out, nothing to maintain, no power required
- Long magnet life: ferrite or NdFeB magnets retain effective full strength for the design life of the unit
- Custom sized to your conveyor: magnet block dimensions, working gap, and field strength engineered for your belt width and burden
- Lowest cost-of-ownership: lowest capital cost in the magnetic separator family; zero electricity, zero spare parts (other than face plate)
- Optional stripper for safer cleaning: lever-operated stripper plate makes manual cleaning faster and safer
Frequently Asked Questions
A. Cleaning frequency depends entirely on tramp iron loading. For typical Indian cement and mineral processing applications, once per shift (every 8 hours) is common. Food and chemical lines with very low iron contamination may go several days between cleanings. Mitool engineers can estimate frequency once material characteristics are known.
A. Yes — this is the most common installation method. The magnet is suspended from existing structural steel above the conveyor, or from a new support framework added for this purpose. No modification to the existing conveyor system is required.
A. Standard suspension magnet sizes cover conveyor belts up to 2400 mm wide. Larger belt widths can be handled by installing two suspension magnets in parallel, or by using an overband magnetic separator, which is generally more practical for wider conveyors.
A. Yes — sanitary SS-304 or SS-316 construction with polished welds and food-grade gaskets is available for food and pharmaceutical applications. The magnet assembly is fully sealed inside the housing, preventing metal contamination of the product stream.
A. As iron accumulates on the face plate, it gradually reduces the effective magnetic field, meaning incoming ferrous material may no longer be captured efficiently. This can allow tramp iron to pass through to downstream equipment. Regular cleaning is essential. If continuous operation without manual cleaning is required, an overband magnetic separator is recommended.
