Tramp Metal Collection from Conveyed Coal – Part 1 of 2

When a coal-fired power station needed a suspended electromagnet added above two existing conveyors, they chose IDI to modify the head end of each conveyor, design a tramp metal chute and design the steel structure to support the electromagnet.  Part 1 discusses the head end modifications and tramp metal chute design.  Part 2 will be in the April newsletter and discuss the steel support structure.

Stray metal objects mixed with coal are called tramp metal which can damage conveyor belts and downstream equipment.  Suspended electromagnets can be installed above conveyors to remove these metal objects and improve product purity.

A new stainless steel head box was designed to allow the electromagnet to be installed on an angle above the head end of the conveyor.  The head box had to seal to form a dust tight seal with the existing coal chute under the conveyor and could not have any ledges or gaps on the interior to prevent coal and moisture from collecting.  Access doors were included and located for cleaning and maintenance.  Inside the head box was a divider plate which provided manual adjustment for the flow of tramp metal to the chute.  The adjustment mechanism was designed on the exterior of the head box to allow the divider plate to be moved without having to reach inside reducing pinch points and increasing safety.

An expansion joint was designed between the electromagnet and the top of the head box to permit the electromagnet to move independently and to ensure that no vertical or horizontal forces from the electromagnet were transferred to the head box.  This expansion joint was also designed to create a dust tight seal at this interface.

Once the magnet extracts the metal from the coal, it is discharged to a chute and emptied into a mobile steel hopper at the bottom of the chute.  The chute design required multiple angles and changes of direction to enable it to fit within the existing platform structure and maintain optimal flow of the tramp metal to the hopper.