SHAFT SINKING
RUC Mining was awarded a contract for the design and construction of the two ventilation shafts at Appin back in late 2022 , with the blind sinks going down to a depth of approximately 600 m at 5.5 m and 7.5 m diameters
Sustainable sinks
To hoist , or to load : that is the question in the mine development space . Dan Gleeson speaks to the shaft sinking market to find out if there is yet a unanimous industry answer
If sustainability and emission reduction aims become overriding factors in mine project development , as expected , it is inevitable more shafts will be sunk in the future .
These aims – when quantified in an emissions intensity equation – favour shaft-supported underground operations where typical financialonly metrics would point towards declinesupported ones . This is thanks to the ability to ‘ green ’ the electricity required , the potential to regenerate energy when using an energy storage component and the ability to leverage existing material handling technology as opposed to emerging battery-electric innovations .
With this context in mind , IM heard from the leaders in this space about the latest developments going down .
Technology breeding optionality
Redpath Deilmann , the Germany-based arm of Redpath Group , has some positive project prospects on the horizon , as well as several technology developments .
Speaking to IM from its headquarters in Dortmund , Jochen Greinacher , Managing Director of the company , said his team had ongoing work in the UK and Germany , plus potential study work elsewhere .
Apart from a ground freezing project for 13 crosscuts to be frozen in a twin tunnel for the HS2 project in London , its work in the UK is solely focused on the Woodsmith polyhalite project in Yorkshire where it has been steering the sinking process of two shafts . Both 7.5 m in diameter , these shafts were originally billed as going down to 1,594 m ( production shaft ) and 1,565 m ( service shaft ) depths .
When IM spoke to Greinacher in mid-July , work on the production shaft had been halted – at a depth of 712 m – while the service shaft had just crossed the 750-m depth mark .
Redpath Deilmann ’ s original contract remit was scaled back earlier this year as part of project owner Anglo American ’ s group-wide value generation strategy , set out in May . This strategy – which saw available capital expenditure for Woodsmith cut – means Redpath Deilmann is now fully focused on developing the service shaft .
“ We just carried out the first grouting level in the service shaft around the 750-m-level to explore the occurrence of water in the sandstone ,”
Greinacher said . “ The water levels were minimal on final inspection , which meant
we did not require a huge amount of grouting .”
To this point , Redpath Deilmann has been leveraging Herrenknecht ’ s Shaft Boring
Roadheader ( SBR ) for sinking activities .
The SBR is well on its way to being commercially proven at providing safe and fast full-bottom blind sinking to depths of 1,600 m in soft to medium-hard rock applications with up to 100 MPa uniaxial compressive strength ( UCS ), having been deployed at the Jansen project ( BHP ) in Canada and the Nezhinsky project ( Slavkaliy ) in Belarus . For the efficient excavation of the rock , the SBR has been equipped with a roadheader boom and a rotating cutting drum . These cutting tools are complemented with a pneumatic mucking system .
When evaluating the company ’ s plans for sinking the Woodsmith service shaft to greater depths , Greinacher flagged future ground conditions that could result in a change of plan .
“ It is another 50 m or so until we reach the hard rock , the Sherwood Sandstone ,” he said . “ We know through testing the SBR in harder formations further up the shaft that the SBR ’ s performance may be compromised when cutting this rock .”
During a site visit in October , Tom McCulley , CEO of Crop Nutrients for Anglo American , hinted at this , pointing to a 250-m section of sinking that would “ see our rates reduced from our 1 m / d to something between 0.5 m and 0.75 m a day ”. He added during this visit : “ Once through that
Redpath Deilmann is developing a hydraulic mucking solution , the RD S100 , that could allow drilling , ripping , cutting and cleaning to take place within a shaft sinking environment on a tele-remote basis
International Mining | SEPTEMBER 2024