Atherton Material Handling has installed a Bunting Suspension Electro Magnet at a calcium carbonate quarry in Melton, UK. The Suspension Electro Magnet removes tramp ferrous metal prior to a metal detector, reducing the number of metal detection trips and increasing productivity.
Bunting is one of the world’s leading designers and manufacturers of magnetic separators, eddy current separators, metal detectors and electrostatic separators, with globally located manufacturing facilities.
Atherton Material Handling originally contacted Bunting to find a solution to the problem of a metal detector in the quarry tripping too frequently. Tom Higginbottom, Bunting’s Technical Sales Engineer, was invited on site by the Atherton team to review the installation.
Bunting had supplied the original metal detector, a model TN77 series, which was identifying tramp metal that could damage crushers, screens, and conveyors. The metal detector was operating perfectly, but the quantity of tramp metal contamination resulted in frequent tripping, and the need to stop the conveyor for removal of the metal. Even though the metal detector’s performance was providing the ideal protection of processing plant, the frequency of metal-trips was affecting productivity.
Bunting recommended the installation of a Suspension Magnet prior to the metal detector. This would remove all tramp ferrous metal, which is magnetic, leaving the metal detector to focus on non-ferrous tramp metal such as manganese steel digger teeth.
The troughed conveyor transporting the quarried calcium carbonate was 600 mm wide, carrying a densely packed 100 mm burden depth of material. This led to the recommendation of a Suspension Electro Magnet, which produces a strong, deep field powerful enough to attract tramp ferrous metal at the bottom of the burden.
The selected Suspension Electro Magnet, model 60 OCW 20, is cooled by oil and weighs just over one tonne. The magnet width is wider than the conveyor, at 925 mm, and stretches along the conveyor 925 mm. This provides plenty of dwell time under the magnet for the magnetic attractive force to pull the ferrous tramp metal through the burden.
The Suspension Electro Magnet has three suspension points, which connect up to a hand-geared travelling trolley, installed by Atherton Material Handling. This system enables the easy moving of the Suspension Electro Magnet away from the conveyor for safe and effective removal of all captured tramp ferrous metal off the magnet face. In operation, the maintenance crew manoeuvres the Suspension Electro Magnet into position over a chute before turned off the magnetic field and allowing all captured metal to discharge from the face of the magnet, under gravity, into a separate collection area.
The Suspension Electro Magnet, suspended 200 mm above the conveyor, generates 650 Gauss on the surface of the belt, which is enough magnetic force to remove a wide range of tramp ferrous metal.
Once installed, the resultant reduction in the number of times the metal detector trips will reduce production downtime without any compromise on protecting the crushers and other processing equipment from tramp metal damage.
“We worked closely with the Atherton Material Handling team to find a solution for their client,” explained Tom. “The final solution not only maintains and improves important protection against tramp metal damage, but also makes it easy and safe to operate and clean the Suspension Electro Magnet.”
