CONTINUOUS CUTTING
The Sandvik MX650 has been optimised for 5 x 5 m tunnels, but has the capacity to work effectively in environments ranging from 4.8 x 4.8 m to 6 x 5.5 m
were among a list of mining companies to have witnessed some of this testing, with these three now part of a consortium, led by ReThink Mining, developing a second generation MX650. second drive being 95 m in July 2025. Progress has been hampered by difficult ground conditions and large inflows of water at plus-50 ° C. Robbins says it is optimistic about improving on these rates, with the MDM5000 becoming a machine that Fresnillo will have in use for years of operation.
Robbins’ third-generation machine is also in the works, providing an alternative horseshoe type tunnelling profile, the company says. The machine uses a standard TBM cutterhead plus bottom cutters to excavate the bottom 12 % of the tunnel, with a capability of excavating rock at traditional TBM advance rates of 400-800 m / mth depending on ground conditions.
Master Drilling’ s MTB
And finally an update from Master Drilling on its continuous cutting advances.
The South Africa-based company issued its half-year results recently, reporting that its Mobile Tunnel Boring( MTB) machine has been successfully placed with a client in the country. It noted:“ The contract negotiations have been finalised and operations are expected to start in the fourth( December) quarter of 2025.”
This MTB is a“ Mark 4” first-generation machine that has been re-built over time following deployment at a soft-rock quarry in Italy and stints in South Africa at Northam Platinum’ s Eland platinum group metals operation and Anglo American Platinum’ s Mogalakwena mine.
Robbins’ engagement at the Fresnillo face
Robbins’ MDM5000 continues to make progress at Fresnillo’ s namesake mine in Mexico, helping contribute to a rising mine development rate, which is currently 3,500 m / mth on average.
This machine, which uses disc cutter technology proven on traditional circular machines, can excavate rock up to 200 MPa in rectangular cross section tunnels with dimensions of 5 x 4.5 m. This is thanks to a reciprocating cutterhead able to exhibit a swinging motion.
In addition to the cutting element, continuous ground support is placed immediately behind the cutterhead in a pattern that is mine-standard, according to Robbins. Ground support and installation of utilities such as piping, ventilation and lighting are carried out simultaneously to boring, with the MDM5000 providing a complete mechanical rock excavation system.
The ability to excavate a flat tunnel invert for immediate use by rubber-tyred vehicles is a key selling point of the technology, as well as a major differentiator to standard TBMs.
On the machine’ s first drive, rates up to 190 m / mth were achieved prior to hitting an unexpected fault zone, which took the mine 18 months to grout-off, retract the MDM5000 and relaunch. Robbins took part of this time to make some refinements to the system. The MDM5000 restarted operations last year.
The original trial at Fresnillo was scheduled to be 5,000 m of straight development and Lok Home, President of Robbins, said Fresnillo is still committed to this trial, with the best month of this
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International Mining | NOVEMBER / DECEMBER 2025 27