SHAFT SINKING
be able to realise with another mechanised technology that could sink shafts in much harder rock .
The Shaft Boring Cutterhead ( SBC ) being developed by Herrenknecht with support from Redpath Deilmann is that technology , according to Greinacher .
The SBC is expected to be able to cut rock with a uniaxial compressive strength ( UCS ) of up to 260 MPa rock down to 1,500 m depths with shaft diameters ranging from 8-9 m .
Greinacher said the experience both companies have gained using the SBRs has been leveraged for the design and engineering of the SBC .
Built with a cutterhead like a tunnel boring machine ( TBM ), it can deliver an advance rate of 6 m / d under the right conditions , according to Herrenknecht . It is also equipped with a pneumatic mucking system able to handle more abrasive rock like that of the latest generation SBR .
COVID-19 has pushed some of the SBC testing timelines back , but work to optimise the shape of the cutterhead – one of the core components of the machine considering it could be faced with cutting rock that has a UCS of up to 260 MPa – is currently taking place at Herrenknecht ’ s facility in Schwanau , Germany .
Both Herrenknecht and Greinacher are hopeful of the core cutter section being built and tested within the first half of 2022 . During the latter stages of testing , interested parties are likely to be invited to Schwanau to witness this system in action .
Speaking of interested parties , Greinacher said he has already had conversations with miners in Kazakhstan and Russia avidly watching developments with the SBC .
While large-diameter raiseboring technology ( explored in more detail later ) is being factored into studies looking at mechanised sinking options in North America , the SBC technology is an easier sell in Russian-speaking countries , according to Greinacher .
“ On one project looking at sinking three shafts , we proposed sinking two shafts with the SBC and raiseboring or pilot and slashing the third one ,” he said . “ They rejected the idea for the third shaft and were more open to the use of the SBC as , for them , it is proven TBM technology that has simply been turned on its head .
“ At the same time , in the geologies we are looking at there are sometimes softer sections of rock to cut . If you are to raisebore big shafts of over 1,000 m successfully , you require stable hard rock over the entire length .”
Consistent conditions are hard to come by in any sinking project and that is why Redpath Deilmann – and the wider Redpath group – is also pursuing a project to automate both the drill and blast part of conventional shaft sinking , as well as the mucking element .
Greinacher provided details of this concept in last year ’ s shaft sinking feature and was ready to tell more when IM spoke to him last month .
“ The design is more or less complete and we ’ re on the procurement phase now ,” he said . “ We will have the prototype assembled shortly and then we will start the testing at our factory .”
The idea is to have all functions carried out independent of the main galloway , removing personnel from the shaft bottom , while increasing sinking performance . Such an innovation is likely to leverage the Redpath Shaft Control System : a patented communication system to collect information from virtually any electronic device on the market in real time to maintain operations within anticipated parameters .
The initial design includes a backhoe-type mucking system attached to the galloway that allows the mucker to advance towards the muck pile while the operator sits in the galloway .
“ If you have a 5 m muckpile on the bench , you can lower the excavator to capture more muck in the bucket ,” Greinacher explained , adding that the patent for this system was in preparation , hence the reason he could not share more details .
From here , the aim is to assemble the machine and test its functionality on a manual basis from the galloway in a process representing step one of the project .
“ It is set up to be semi-automated ,” Greinacher said . “ But the vision and the systems are designed that all functions can be carried out remotely , either from surface or from somewhere else . Eventually this work could be carried out autonomously .”
This vision – representing step two or three of the project – will be facilitated by 3D cameras and sensors that have been tested and developed within the wider Redpath Group .
Advanced communications
While Redpath Deilmann has been advancing this system in Dortmund , Germany , Redpath ’ s office in North Bay , Canada , has been collaborating and reviewing the work-up of design criteria and functional approaches for the unit , according to Kevin Melong , Vice
Redpath Raiseboring completed a record-breaking hole at Kirkland Lake Gold ’ s Macassa Mine in Ontario , Canada , with a manufactured-in-Ontario Redbore 90 . At a length of 1,010 m , the raise became the longest raisebore hole ever accomplished in the Northern Hemisphere and all the Americas
President – Shafts and Technical Services . For Melong , the concept represents “ the next significant step-change in shaft sinking ”.
Being able to muck the shaft bottom independently of the main galloway with no workers present on the bottom comes with obvious safety benefits , but also offers the ability to safely perform concurrent shaft and lining work with automated bottom mucking to provide a potential productivity boost .
More broadly , Melong and his Redpath colleagues have been exploring the knock-on benefits that come with applying the Redpath Shaft Control System , which is now embedded within all the group ’ s shaft sinking work .
This uses a combination of hardwired and wireless technologies and protocols , such as programmable logic controllers and sensing equipment , to safeguard against unwanted equipment interactions and optimise routine tasks . The ability to record and trend this information promotes opportunities for continuous improvement and optimisation to both operational procedures and equipment use , Redpath said .
“ These systems allow us to reimagine the shaft sinking approach as data transfer leads to a myriad of control and automation possibilities ,” Melong told IM .
Wireless communication has also allowed the company to receive visual information from mounted cameras on both the crossheads travelling in the shaft , as well as the various decks of the galloway , to more closely monitor the interaction between hoist conveyance and the galloway .
“ The statuses of the crosshead rope button release and latch arm positions is also transmitted wirelessly to the safety control
108 International Mining | SEPTEMBER 2021