Sirius Minerals and its partners working on the UK’s York Potash project have set a new world record for the deepest shaft ever excavated with a Vertical Shaft Sinking Machine (VSM), reaching a depth of over 115m.
The 75-tonne Herrenknecht VSM was used to construct the initial 120m of the 360m deep access shaft at Woodsmith Mine that will allow the company to construct its 36.8km long tunnel that will transport mined ore to Teesside. Once the shaft is complete, a TBM will be lowered to its base and assembled in a cavern to drive north towards Teesside.
The highly specialised VSM was deployed at Woodsmith Mine for the first time in the UK in order to enable the team to construct the shaft as efficiently, expediently and safely as possible. The team’s application of its innovative technology – developed by Herrenknecht – enabled the sinking of the shafts through near-surface water aquifers, due to the fact that the machine is designed to work underwater with a shaft lining being lowered behind.
Typically, shaft lining would be created from pre-cast concrete segments but, in conjunction with contractors Careys Civil Engineering and Joseph Gallagher Limited, Sirius utilised the ‘slip form’ technique to pour the concrete lining. Using this technique, by continuously pouring the shaft walls simultaneously with the VSM’s excavation activity, the team was able to line the shaft more safely, rapidly and cost-effectively. Cutting-edge 3D, 4D and virtual reality (VR) modelling technologies were also used to digitally construct the shaft, forecasting a range of possible outcomes for each aspect of the construction process.
The machine reached a total depth of 115.2m in May 2019, surpassing the previous world record of 84m previously set in St Petersburg.
Chris Fraser, Managing Director and CEO of Sirius Minerals said: “Using this cutting edge machine is proof of our determination to use the best, most effective engineering solutions to build this mine and the successful completion of the vertical shaft sinking machine’s operations is another important sign of progress for our project”.