CONTINUOUS CUTTING
The Epiroc Mobile Miner 40V is currently in Sweden at Epiroc ’ s own test mine where interested mining companies have been visiting
machine to the veins that would be mined at the seismically active operation . Yet , the successful application of a new mining method – Underhand Closed Bench – at the mine recently led to Hecla deciding against the machine ’ s use at Lucky Friday .
Around this time last year , discussions between Epiroc and Hecla continued about deploying the 40V at Greens Creek in Alaska , a Hecla-owned mine that primarily uses cut and fill , and drift and fill techniques , supplemented by longhole stoping where orebody geometry permits . This is different to the primary mining method of underhand stoping with paste backfill that Lucky Friday was leveraging and the 40V had been designed for .
This application of the 40V at Greens Creek was always hard to reconcile – due , in part , to the different mining method and ramp-only access offered by the operation – and the parties have since decided to look for an alternative site to test the machine .
Markus Eklind , Epiroc Global Business Line Manager – Mechanical Rock Excavation , told IM : “ Hecla and Epiroc remain committed to this project and , together , we are currently investigating potential partners that can get involved with the machine ’ s development and offer up a test site . We are focused on proving the technology on a continuous basis in a reallife operation .”
The machine is currently in Sweden at Epiroc ’ s own test mine where interested mining companies have been visiting .
“ I am optimistic that during 2024 we will be able to communicate something significant on this project ,” Eklind said .
When it comes to the 22H , Epiroc is also expecting a busy 2024 .
This machine – with certain adaptations – was previously tested at the Twickenham PGM mine in Limpopo Province , South Africa , where it advanced at over 10 m / d in 140-150 MPa UCS rock in a trial that was curtailed due to the mine being placed on care and maintenance . It is designed for low-seam or low-profile mining where tunnels as low as 2.2 m are required .
Eklind says the OEM continues to work with Anglo American as part of its FutureSmart Mining™ vision , with the 22H currently at Bentley Park , just outside of Johannesburg , South Africa , at a training facility owned by Murray & Roberts Cementation .
“ Together with Anglo American we are preparing for some tests involving mechanical rock cutting and preconditioning ,” Eklind said .
Speaking along these lines at the recent Bank of America 2023 Smart Mine 4.0 conference , Donovan Waller , Anglo American Group Head of Technology Development , said the company had been testing preconditioning ore technology application methods with microwaves over the past few years and the effect on in-situ ores in both underground and surface mines .
He said : “ We are currently testing a production cutter in a quarry and , if successful , we will install a first-generation microwave preconditioning system in a production environment at an Anglo American site in 2024 .” Outside of these two developments , Eklind was pleased to see more talk of MRE among the mining community .
“ From my perspective , any progress with MRE equipment benefits MRE in general ,” he said .
“ For us , the concept of the Mobile Miner fits very well into the mine of the future in that it is a continuous process , comes with no diesel emissions , no blast fumes , etc . That is why it is even more important to us to prove these are not just prototypes but are effective machines .
“ I don ’ t think there are doubts about the rock cutting ; we use traditional TBM technology and can predict penetration rates and wear on the tools as there are thousands of metres drilled with these steel discs every year . What we need to prove is the system , the availability and production rates , along with the required personnel to operate it .”
Komatsu MC51 on the up
Komatsu ’ s MC51 machine has already been tested at three mines to date , with the OEM having a bank of data and learnings to work from when it comes to new hard-rock applications .
The latest mining assignment is in Canada at Vale ’ s Garson mine in Sudbury , where the MC51 is working mainly in waste rock around the Mini McConnell orebody as part of the mechanical cutting demonstration within the CMIC Continuous Underground Mining project .
The MC51 leverages DynaCut technology , an undercutting disc technology for mechanical cutting . It has a cutter on a single , five-axis robotic boom that can profile any shape within a 5 x 5 m profile , according to Komatsu . The machine is also able to cut within 50 mm of plan , with the resultant excavations already exhibiting high tunnel quality and a reduction of over break .
After the machine cuts the rock – 200-250 MPa in the case of the rock in Sudbury – into consistently-sized small chunks , the material is gathered into the centre and conveyed to LHDs , trucks or external conveyors to be hauled away . At Garson , it is a 7-t payload Komatsu WX07 carrying out the mucking .
The result of more than 10 years of research and development , the MC51 is fully electric , outputting zero emissions . It also offers increased levels of automation , with the machine able to be operated remotely via line of sight .
Many of these functions have been tested in some form on previous assignments at Newcrest Mining ’ s Cadia copper-gold operation , in New South Wales , and Hillgrove Resources ’ Kanmantoo copper project , in South Australia .
IM reported on progress in Canada at Garson last year , with Andy Charsley , Principal Mining Engineer at Vale , explaining some 30-40 m of development had been carried out with the machine in waste rock .
In the 12 months that have passed , further progress has been made on what is now a threestage R & D program due for completion by the end of the year .
“ We appear to have figured out many of the kinks that come with any R & D project like this ,” Charsley said . “ Both companies remain committed , and we continue to keep the other CMIC partners ( Glencore and Agnico Eagle Mines ) regularly informed on progress .”
Stage one – which has been completed – saw a 30 m straight advance excavated . This stage exhibited some understandable cutter disc and mechanical challenges .
This was followed by stage two – another 30 m of straight advance in a different area of the mine focused on improving cutter life and reducing the forces exerted on the exciter ( positioned behind the cutter ). This advance was deemed a success , with an increase in the size of the buttons on the cutter head ( each cutter is made up of 92 buttons ), a change in the cutting pattern and upgrades to the on-board positioning system addressing the issues experienced during stage
42 International Mining | NOVEMBER / DECEMBER 2023