Magnetic drum separators are essential tools for efficiently removing unwanted iron particles from large volumes of materials and for recovering valuable metals. Eriez offers these a series of separators in a range of sizes in its drum line, from 36 to 84 inches in diameter and 36 to 96 inches wide, making them customisable for many recycling operations.
Drum separators are available in permanent and electromagnetic designs. The main difference between electromagnets and permanent magnets lies in how they generate and retain magnetism – electromagnets rely on electricity, and their magnetism is temporary, while permanent magnets have an inherent magnetic field that persists over time.
Electromagnetic drums’ insulated wire coils are built using a solid-steel core to produce a deep magnetic field to reach ferrous materials from the burden. They require consistent DC power from a rectifier control. These drums use a rectangular core to maximise the magnetic field and provide the best possible coverage across the width of
the separator.
All electromagnet drums are prone to the same problem by the nature of their design – heat loss. As the magnet heats up throughout the day, it can lose as much as 30-35 per cent of its strength. Ferrous recovery will be best in the morning when the magnet is in the “cold condition.” After a few hours of operation, it is not unusual to see a recovery drop-off due to this design constraint. These drums typically reach their steady state (in hot condition) after two to three hours of operation.
Eriez permanent rare earth (P-Rex) drum magnets are some of the strongest drum magnets available in the industry. Using a permanent rare earth magnetic circuit, the P-Rex is nearly 40 per cent stronger than its electromagnetic counterpart. Because the P-Rex uses a permanent magnetic fixture, the magnetic field is uniform and extends from edge-to-edge, whereas electromagnetic drums’ magnetic field is stronger directly under the core and weaker towards the edge. Additionally, the permanent drum offers a wider pick-up zone, enabling an efficient collection of ferrous material. Permanent drums also maintain more strength throughout the transfer and carry-over zones.
With its permanent magnetic circuit, the P-Rex can collect heavy and hard-to-retrieve ferrous objects, including large spherical objects commonly referred to as “meatballs,” which are considered difficult to capture magnetically. Its strength allows it to pick up these large pieces of magnetic material from nearly twice the distance, making it a good option for deeper burden depths found in scrap metal processing and recycling operations.