Multi-Plate™ Structure just the ticket for coal bin replacement

In what is an innovative application of an existing and longstanding product, Multi-Plate™, Rocla has developed a unique fit for purpose replacement solution for an aging coal bin at the Ulan Coal Mine in NSW.

The original coal bin structure was imported from the UK and installed around 20 years ago, which meant there was no technical information available such as drawings or mechanical properties. Rocla’s design engineers collaborated with Dean Morrison from Aspec Engineering Pty Limited to find a solution appropriate for the highly corrosive environment.

Round Multi-Plate™, as a buried metal structure most often used for culverts, stormwater drains, tunnels and bridges, carries vertical loads through a combination of internal capacity and soil arching around the structure.

Using a buried structure designed in accordance with AS2041 for above ground application naturally raised a few concerns.

The largest obstacle was to ensure the structure could perform in the absence of haunch support from soil followed by manufacturing a durable product with a 15 year design life in a highly corrosive mine environment.

The final round Multi-Plate™ structure comprised 49 pieces of galvanised 5mm steel plates (10 plates per ring x 4 constructed using 10 bolts/m) with a total mass of 464kg. It featured a rise of 7.05m and diameter of 9.00m, a 12mm base, lifting brace and vertical support bracket all in accordance with AS2041, AS3774 and AS1170.

The client was provided with design loads acting on the storage bin based on the bulk material properties on site, followed by 2D Finite element analysis and design for all support structures including beams, pedestals and base plate, fabrication drawings and certified drawings.

Rocla expects further aging coal bin structures in NSW to be replaced with the round Multi-Plate™ structure over the next 12 months.