GROUND SUPPORT
Fibre shotcrete - it ’ s all about the mix
Fabian Erismann , Head Mining , Sika Services , outlined to IM how fibre reinforced shotcrete has proven to be the material of choice when it comes to safe , rapid , and efficient underground fortification in large mining projects . “ For large caving and long hole stoping projects , in cycle shotcrete is particularly interesting as it allows rapid footprint development in order to shorten the construction time to access first ore from draw-points . Application speed , applicability , yielding characteristics , durability , and strength , are favourable characteristics that make fibre reinforced , sprayed concrete the go-to primary support component in most modern , large mining operations around the globe . Integrating an effective shotcrete set-up in mining operations requires solid expertise in concrete production , spray application and the selection of the best performing materials .” This is especially important when it comes to the supply of large shotcrete and concrete volumes to remote mine sites in challenging climatic conditions . Particular attention is dedicated to screening the top mix design for any given mining operation , and how this mix can be efficiently produced or blended at the mine site resulting in the best cost performance .
“ Finding an optimised solution in terms of the accelerator and admixture selection with given raw materials , the choice of the right fibre and dosage , as well as optimising the mix design from a cost performance perspective , are key to harvesting the main benefits of an integrated shotcrete support . By doing so , the shotcrete will yield its main benefits such as high early strength development that allows safe and fast re-entry time after spraying , as well as high energy absorption capabilities of the cured shotcrete liner to cope with the expected lithostatic , and seismic induced loads and deformations .” The same applies for cemented paste backfill projects where cement consumption , strength development as well as the transport along the paste reticulation system , can be greatly improved by a good paste design that meets the mines requirement at a minimised cement consumption .
Erismann says Sika is at the forefront in optimising cement intensive applications in the global mining industry . “ Our products are market leading in every aspect . From our inhouse fibre technologies for shotcrete and concrete - our pumps and machinery to spray efficient and highquality shotcrete liners - to our market leading , customized admixture solutions for paste plants . Not only are we committed to performance excellence , but also to industry leading EESG goals that we want to achieve together with our clients .”
Sika is at the forefront in optimising cement intensive applications in the global mining industry
With King Shotcrete joining the global Sika team in 2019 , a broad range of unique specialty products completed the Sika shotcrete offering . With a strong focus on the North American mining industry , King products include shotcrete for rapid mine development due to their fast curing , very high and fast energy absorption for seismic prone areas and high abrasion resistance for ore pass liners as well as products developed specifically for permafrost applications . “ Many projects in the Canadian Arctic rely on the easy to apply , ready bagged shotcrete solutions from King-Sika . We tick many boxes to lift underground construction to the next level , relying on over a century of underground construction excellence across the globe .”
He adds : “ Lessons learned from projects such as El Teniente , Grasberg , Kiruna , Chuquicamata , Oyu Tolgoi and many more , have resulted in many best practices that our dedicated teams help to implement in the far corners of the globe . The employment of local staff in our over 100 country subsidiaries globally , the development and production of underground construction materials , as well as the wealth generation in the countries that we do business in , is of the utmost importance to us here at Sika . One of the key factors to the ongoing and lasting success of our company is that we are committed to contributing and adding to the local value chain wherever and whenever possible .”
worthy of marking , but we ’ re not standing still ,” adds MacLean President , Kevin MacLean . “ We are now hard at work in the product development and testing phase for the next generation of Maclean bolter that will follow in the footsteps of the original Maclean paradigmchanger but also forge its own path by introducing robotics to our bolting philosophy and engineered design . Stay tuned because exciting things are on the horizon .”
Moving to BEVs and a new shotcretetransmixer combination that , MacLean says , will make it the only OEM able to offer fully electrified , articulated shotcrete operations purpose-designed for underground mining applications . Jonathan Lavallee , Product Manager – Shotcrete Equipment says it has exceeded expectations .
Filling out an offering of shotcrete sprayers that includes the diesel-powered SS2 and SS3 machines , the battery-powered SS5 shotcrete unit is close to 7 ft ( 2.13 m ) wide and is the firstever MacLean sprayer to have a forward-facing cab for a better view of shotcreting operations from inside the cab .
In addition to a better view , the shift from mid-ship to forward-facing cab has also aided with placing the batteries and the EV components on the rear side of the machine to ensure rebound dust and particulates from shotcrete operations are not getting inside the EV components , Lavallee said .
Alongside this machine will be the 2.59-mwide battery-powered TM3 concrete transmixer , which is based on a diesel-equivalent machine already on the market and will serve the SS5 ’ s shotcrete needs .
Like all of MacLean ’ s EV Series machines , the
SS5 sprayer will be able to tram on battery and connect to the power infrastructure within the mine for spraying .
“ Depending on the size of your heading , the battery re-generation capability on site and the air quality / quantity , there could be an option to shoot on pure battery ,” he said . Testing at the MacLean Research and Training Facility in Sudbury saw the prototype machine complete two full mixer trucks worth of shotcrete – roughly 12 m 3 – while still having enough battery power remaining to conduct a thorough wash down and washout of the equipment and tram to the nearest point of recharge , according to Lavallee .
While there was no on-board compressor fitted to this prototype – with the machine using mine air at the test facility – Lavallee is confident the commercial unit will provide the option of
74 International Mining | AUGUST 2021