A Guide to the Ideal Location for Magnetic Separators and Metal Detectors in a Pet Food Processing Plant
Ensuring Pet Food is metal free before it reaches the consumer is critical. However, reports of foods being recalled due to metal contamination occur several times each year [Sainsbury warns of Metal in Bread, Jan 2016]. To assist processors and producers, Bunting has developed a series of typical plant flowsheets showing proposed locations for Magnetic Separators and Metal Detectors. This blog reviews a flowsheet for a typical Pet Food Processing Plant.
The flowsheet shows material being fed into the plant through to packaging and shipment to retailers. The type and location of the Metal Separation equipment is detailed as follows:
- Infeed Material
- Dry Side – Dry materials are often fed into the plant from transportation via a pneumatic line. To remove ferrous metals (eg nuts, bolts, nails, etc) then a Pneumatic Inline Magnet is recommended. Additionally, after storage in the primary silo, the dry material is passed through a Plate Housing Magnet before being mixed with any other materials, such as meat;
- Meat Side – After discharge from the transportation, material is commonly fed up a conveyor. Positioned above the conveyor to lift and remove larger ferrous metal is a Suspended Plate Magnet and this is then followed by a Metron C Metal Detector to identify any non-ferrous metals such as stainless steel. This ensures that no metal is fed into the grinder where is could damage equipment and also be fragmented into smaller parts that are more difficult to detect and remove;
- After 1st Stage Mixing
- After mixing, when the material is now in a slurry form, a Magnetic Liquid Trap with high strength Rare Earth Magnets is ideal to remove any smaller ferrous metals and any metal that originates from the wear of processing equipment;
- On the Wet Line prior to Canning
- To ensure a metal-free product prior to canning, a P-Tron-O Metal Detector can be used on the line to detect and remove smaller ferrous and non-ferrous metals;
- On the Dry Line prior to Bagging
- After extrusion and just prior to bagging or insertion into cartons or boxes, a Quicktron Metal Detector is ideal to detect and remove any smaller remaining ferrous and non-ferrous metals;
- As a final check, the filled and sealed bags are commonly passed through a Metron C Metal Detector which can detect metal inside a package;
The type and design of Magnetic Separator and Metal Detector and the recommended location has been determined following several decades of working with food producers and processors all over the world. There are always variations to plant designs and layouts that mean different types of Metal Separation equipment is needed and an onsite review by a Bunting engineer will help ascertain the best solution.