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Strabag Yorkshire mine tunnelling contract extended

Sirius minerals vertical shaft sinking machine vsm october 2018

Strabag’s contract with Sirius Minerals has been extended to cover the entire 37km mineral transport system under the Yorkshire Moors for a new £1.5bn polyhalite mine.  

Sirius Minerals has announced an extension to its agreements with Austrian contractor Strabag for works at the new Woodsmith mine in Yorkshire.  

The amended agreement means Strabag will be responsible for the procurement, engineering, and construction of the fit-out of the mine’s lengthy mineral transport system - as well as other services relating the mineral transport system’s operations. 

The contract originally only covered works to a 13km section of tunnel as part of the mine’s underground transport system. 

The full 37Km tunnel and conveyer system will be used to transport polyhalite - a mineral used to produce fertiliser – out of the mine and to a materials handling facility and harbour in Tees Valley. 

The material from the tunnels will also be used on the Woodsmith mine site to build up bunds around the buildings, hiding the mining site from view and meaning the material does not need to be transported offsite. 

Cut and cover was suggested as a possible method of constructing the tunnels, but instead three tunnel boring machines (TBMs), each starting from different locations, will excavate the tunnel simultaneously at a rate of approximately 17m per day.  

Strabag have already begun the first of three drives, launched from ground level from Wilton to Lockwood Beck in in June.  

The other two TBMs will be constructed underground and launched from the mine site in Woodsmith, 360m below ground. 

Sirius minerals   project overview

Sirius minerals project overview

Construction of the 37km, 6m diameter mineral transport system tunnel is expected to be undertaken using tunnel boring machines

The conveyer system, the longest in the UK, will handle 20 million tons of polyhalite a year. 

Sirius Minerals chief executive Chris Fraser said the company was now focussed its plan to full finance the mine:  

“Our efforts are now focussed on the successful execution of our financing plan to fully finance the construction of our world-class, long-life polyhalite project,” he said.  

The final price of the mineral transport system fit-out was not announced, although Sirius Minerals said it was in line with the re-estimated total capital cost estimate.  

The costs of the project have risen dramatically following changes to the tunnelling for the transport system 

An increase in the planned internal diameter of the tunnel from 4.3m to 4.9m and an increase in lining thickness from 250mm to 350mm caused the price of tunnelling to rise from £858M to over £1.46bn.

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