TN77 Metal Detector for Mining & Quarrying

The TN77 Industrial Metal Detector detects damaging tramp metal present in conveyed materials such as aggregates, mined ore, and recycled materials.  This includes identifying both tramp iron and low-grade manganese steel (e.g. digger teeth).  Once detected, the problematic metal is removed either manually or automatically, preventing damage to screens, crushers and conveyors.  The TN77 design is easy to install and simple to operate, making it one of Bunting’s most popular metal detectors.


The tunnel-type TN77 Metal Detector is generally used to detect tramp metal in conveyed materials and is easily installed onto new or existing conveyors.  The TN77 is especially popular with users due to the simplicity of operation and fully adjustable levels of sensitivity and detection.

The TN77 provides a continuous inspection of any non-metallic or non-conductive material, identifying and locating problematic tramp iron and low-grade manganese steels.  Such tramp metal damages processing equipment such as screens, crushers and conveyors.  Unlike many other Metal Detectors, the TN77 is capable of indicating if 1 of 2 pieces of tramp metal are simultaneously detected.  The Metal Detector also overlooks non-magnetic copper-alloy belt fasteners, which may cause false ‘trips’.

The search coil is supplied from either a range of standard sizes or made to meet customers’ specific requirements, with aperture heights to suit specific processes.  The TN search coil is also easily dismantled for ease of installation around a customers’ existing belt conveyor.

The TN77 Metal Detector is operated via a separate mounted control.  The wall-fixing control cabinet is IP52 rated and designed for local or remote fixing.


When the TN77 Metal Detector detects tramp metal in the conveyed material, a signal is generated in the search coil and transmitted to the control unit.  This signal is processed and used to control other circuits, which include the interlocking of the belt conveyor, operating audible or visual alarms, marking devices or suitable rejection mechanisms.

Typical tramp metal detected includes:

  • Digger teeth
  • Drill rods
  • Crusher plates
  • Bars
  • Chains
  • Nuts and bolts


The versatility of the TN77 makes the metal detector suitable for a wide range of applications in the mining, quarrying, and recycling sectors.   Typical materials inspected include limestone, granite, sand and gravel, clay, coal, and mineral ores.


Bunting – TN77 Metal Detectors Datasheet