American Quarries Install TN77 Metal Detectors

TN77 Metal Detectors are proving popular with quarry operators in the USA.  The ‘Metal Detection‘ branded equipment is used to identify tramp metal in conveyed aggregate and prevent damage to screens and crushers.

TN77 Metal Detector Installed in a USA quarry

Metal Detection is part of the Bunting Magnetics group, one of the world’s leading designers and manufacturers of magnetic separators and metal detectors for the recycling, quarrying and mining industries.  Their wide range of metal separation and detection equipment is manufactured at their Master Magnets facility in Redditch, just outside Birmingham, UK.

The TN77 metal detector is a tunnel-type Metal Detector used widely in the quarrying, mining and recycling industries where the conveyed material is non-metallic or non-conductive.  The TN77 detects tramp iron and manganese steel such as digger teeth, drill rods, crusher plates, bars, chains, nuts and bolts.  Such tramp metal causes significant damage to other processing equipment such as crushers, shredders, screens and conveyors.

TN77 Metal Detector in Operation

In operation, the coil of the Metal Detector (surrounding the conveyor) continuously emits a magnetic field.  Any tramp metal passing through the metal detector changes the magnetic field, which is registered by a control.  When a change in magnetic field is registered, the control processes the signal from the search coil and then sends a second signal to other circuits which stop the conveyor, operate an audible and/or visual alarm, or initiates a rejection mechanism.  One useful optional extra is a marker, whereby either a flag or spray of ink is deposited when tramp metal is detected.  This makes it easier to locate and remove the tramp metal.  Each TN77 Metal Detector installed in the USA has a control unit housed in an IP52 wall fixing cabinet.  This is positioned locally or remotely from the search coil of the Metal Detector.