SHAFT SINKING
“ As always , with shaft access typically being the most critical component of a new mine , finding the right partners to bring in new innovation is tricky ,” Kevin Melong , Vice President , Shafts and Technical Services , Redpath Canada , says .
“ We have to get creative on how we put ‘ skin in the game ’ to bring that innovation into the industry .”
The wider Redpath group is doing as much as anyone in the field in terms of putting that skin in the game .
Redpath Deilmann , the Germany-based arm of the group , has already successfully applied the second generation of Herrenknecht ’ s Shaft Boring Roadheader ( SBR ) sinking technology to sink two 8-m diameter shafts ( one to 750-m depth and one to 697-m depth ) in Belarus at Slavkaliy ’ s Nezhinsky potash project .
It is also in the middle of sinking two shafts – production and service shafts with 7.5-m diameters and depths of 1,594 m and 1,565 m , respectively – using the technology at Anglo American ’ s Woodsmith mine in the UK .
Alongside this , Redpath Deilmann is working with Herrenknecht on a hard-rock equivalent of the SBR , the Shaft Boring Cutterhead ( SBC ), while developing its own in-house , semiautonomous system for concurrent mucking and liner installation during shaft sinking – the RD S100 .
The core tenets of all these developments are
Concepts , engineering and designs for fullymechanised shaft sinking projects continue to be refined , yet the ‘ silver bullet ’ to replace drill & blast remains elusive ,
Dan Gleeson reports
Skin in the sinking game
to standardise as many aspects of the shaft sinking process as possible , according to Melong .
“ Our goal is to simplify the shaft sinking process ; make it safer and more repeatable ,” he said . “ Surety of safety and schedule is good for our clients .”
Melong and his colleague Jochen Greinacher , Managing Director of Redpath Deilmann , are aware no two shaft sinking projects are the same , but they believe these technologies will allow them to carve out a niche that sees greater uptake of innovation in this sector .
“ As much as possible , we want to prove out every element of these new technologies before we commit to utilising the full application on a project ,” Melong says .
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 ).
For the efficient excavation of the rock , the SBR has been equipped with a roadheader boom and a rotating cutting drum . This allows the creation of variable shaft diameters between 7 and 12 m . Based on the Herrenknecht Vertical Shaft Sinking technology , the SBR offers a higher level of work safety compared with conventional shaft sinking with simultaneously higher advance rates , Herrenknecht says .
Redpath Deilmann is working with Herrenknecht on a hard-rock equivalent of the SBR , the Shaft Boring Cutterhead , that has been designed for hard rock up to 250 MPa UCS , with the machine able to carry out cutting , lining and mucking operations concurrently ( pictured is the demonstration rig that is 1:3 the size of the fullsize machine )
After debuting at BHP ’ s Jansen potash project in Saskatchewan , Canada , it excelled in Belarus , being behind several daily and monthly development rate records .
From the latest Anglo American half-year report , the two SBRs working at Woodsmith are making good progress , with the service shaft down to circa-500-m depth and the production shaft circa-245-m deep as of the end of June .
The SBC ’ s development is also progressing well , with Herrenknecht using the latest Bauma event in Munich , Germany , to highlight this .
The Schwanau-based company has equipped its latest concept for hard rock up to 250 MPa UCS , with the machine able to carry out cutting , lining and mucking operations concurrently .
Speaking in Munich in a presentation titled , ‘ Mechanised sinking of deep shafts in hard rock ,’ Patrick Rennkamp , Product Manager Mining , Herrenknecht , said the SBC had been designed for shaft diameters up to 9 m and shaft depths of circa-1,500 m .
One of the unique elements Rennkamp highlighted was the pneumatic mucking system on board the SBC , which builds on a similar system used for the SBR , but is tied to the circular motion of the cutter discs situated on the full-face cutterhead . The movement of the discs and suction , combined , ensures the machine only cuts the material once , Rennkamp explained to IM on the sidelines of the event , reducing wear and keeping the machine cutting for longer .
The design ensures the cut material filters into the centre of the machine where the suction element is most effective . The cuttings then go up the suction pipe into a suction box before being filtered into coarse and fine material and blown further upwards where they can be transported to another overhead station for removal – via buckets – to surface .
The company is targeting sinking rates of 6-8 m / d with the new SBC . While this is short of the progress tunnel boring machines typically make in horizontal developments , it is quicker than traditional drill and blast methods used for blind sinking .
Herrenknecht has carried out 600 tests with different sizes of material , completing over 10 m of shaft sinking in 30-40 MPa UCS concrete with a demonstration rig that is 1:3 the size of the fullsize machine . This rig was showcased at an event earlier this year , attended by major mining companies looking for more mechanised means of shaft sinking .
24 International Mining | SEPTEMBER 2023