Scope of work
The client’s aim is to produce fertiliser products, derived from Polyhalite, to sustainably aid the agriculture industry and grow more food. The client has completed exploration drilling and has advanced the project towards shaft sinking. The Joint Ore Reserves Committee (JORC) - compliant resource estimate of this ambitious project stands at 2.66 billion tonnes of mineral resources and the project area spans 270 km² on-shore and 525 km² off-shore.
The mine infrastructure was designed to produce 13 million mineral tonnes per annum, which would increase with a second phase to 20 million tonnes per annum.
Fraser McGill conducted the independent peer review of this challenging shaft lining design. We assembled a highly specialised team, with the right mix of experience, to perform the review diligently. The Fraser McGill team consisted of a Structural Engineer, a Geotechnical Engineer, a Mining Engineer and a shaft sinking specialist with potash experience.
The shaft headframe had to be lowered some 50 m below surface, from which a sub-bank level could be created. The sub-bank levels housed two vertical shafts that is 1,500 m deep. The basis of the shaft lining design was studied by the team and the current shaft lining stratigraphy was compared with previous designs and the different rock formations assessed. The various ground conditions were then compared with the specific shaft lining design. Special provision for dewatering was also studied for sinking through the creeping ground conditions of the Carnallitic Marl, Rot Salt and Halite seams.
To verify the shaft lining designer’s structural design, Fraser McGill staff performed various calculations, independent models and finite element analysis on the tubbing and other shaft lining structures.
The conventional underground room-and-pillar method was deemed satisfactory for the mineral resource. The sizing of the integrating tunnels was optimised for continuous miner equipment usage.
Furthermore, an underground mineral transport system was envisioned to transport minerals from the mine to the mineral processing facility 40 km away. The mineral transport system would be housed in a mining tunnel and consist of a conveyor belt, operational cables and services. Special provision was also required for a maintenance transit system.