This is the second of a 2-part case study on using a suspended electromagnet to remove tramp metal from coal conveyors. Part 1 (March 2021) discussed the head end modifications to the conveyor, and the tramp metal chute design. The case study concludes with the steel structures and foundations used to support the electromagnets.
Electromagnets were installed on two separate conveyors. Due to the wind and seismic loads for the project location, as well as the hot-dip galvanizing on the existing conveyor support structures, independent structures were designed to support each magnet. The new steel structures had to be positioned to allow columns, beams and bracing to clear existing cable trays, piping and access points. To accomplish this, IDI used its 3D laser scanner to capture these items and identify the size and locations on the existing structures.
One of the existing structures had a large enough mat foundation that could support the added loads from the new structure. This allowed new concrete piers to be installed on the existing foundation by using epoxy adhesive to anchor the rebar to the concrete. The other magnet support structure had to be installed on individual spread footings since the existing mat foundation was not large enough to accommodate the new columns. These spread footings were designed for a maximum bearing pressure of 1,000 psf to limit differential settlement.