Tag Archives: Martin-Devid Herrenknecht

Herrenknecht making headway on hard-rock mechanised shaft sinking operations

Explosives and blasting, Mine shafts and equipment, Mining equipment, Mining events, Mining techniques, , , , , , , , , , , , ,

Herrenknecht used the Bauma 2022 stage last month to reveal details about its latest mechanised shaft sinking solution for mining, the Shaft Boring Cutterhead (SBC).

The company, which has successfully delivered its Shaft Boring Roadheader (SBR) to soft-to-medium rock sinking applications in mining, has equipped its latest concept for hard rock up to 250 MPa uniaxial compressive strength (UCS), with the machine able to carry out cutting, lining and mucking operations concurrently.

The SBC’s specification is based on the experiences from six past mechanised shaft sinking projects and was developed in tandem with a global shaft sinking company Redpath Deilmann.

Two of the projects that influenced the design used the SBR – the blind sinks at BHP’s Jansen mine in Canada and Slavkaliy’s Nezhinsky mine in Belarus. The company has also supplied two SBRs to Anglo American’s Woodsmith mine, with one already carrying out sinking operations.

Redpath Deilmann operates SBR shaft sinking operations at Woodsmith, with DMC Mining previously in charge of sinking operations at the Jansen project.

“This new generation of blind shaft machinery aims to update and adapt existing technology to current conditions and requirements,” Martin-Devid Herrenknecht, Member of the Board of Management, says.

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. The machine weight starts from 450 t and it is 45 m in length.

One of the unique elements Rennkamp highlighted was the pneumatic mucking system on board the SBC.

Building on a similar system used for the SBR, the mucking process on the SBC 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 side lines of the event, reducing wear on the cutters and keeping the machine cutting for longer.

The design ensures that 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.

Like the SBR, the machine has a gripper system to keep it in place within the shaft. There is also a lining area directly above the grippers and further work decks for concurrent work.

The company is targeting sinking rates of 6-8 m/d with the new SBC. While this is short of the progress traditional TBMs make in horizontal developments, it is quicker than traditional drill and blast methods used for blind sinking.

Herrenknecht had a team of some 40 working on the development of the SBC at its Schwanau facility in Germany. This is complemented by a team at Redpath Deilmann’s facilities in Germany, who are also providing input to the project.

To this point, the company has carried out 600 tests with different sizes of material, completing some 9 m of shaft sinking in 30-40 MPa UCS concrete with a demonstration rig that is 1:3 the size of the full-size machine.

The next steps are to invite potential customers to supply their own material for testing on the rig and validate the hard-rock cutting potential.

Herrenknecht heralds ‘game changer for shaft sinking in soft and medium-hard rock’

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Having successfully excavated two 8-11 m diameter blind shafts using Shaft Boring Roadheaders (SBRs) at the BHP-owned Jansen potash project, Herrenknecht is leveraging all the lessons it learnt in Saskatchewan, Canada, to ensure this technology proves to be a “game changer” for the sinking of shafts in soft and medium-hard rock.

Mining contractor DMC Mining Services used two SBRs to excavate the blind shafts at Jansen, with the successful project completion acting as proof of the feasibility and advantages of the Herrenknecht SBR concept for the mining industry, according to the Germany-based company.

In August 2018, the mining industry milestone was achieved with the successful completion of two blind shafts to depths of -975 and -1,005 m, respectively, at the Jansen potash project. For the first time, shafts in the mining business were sunk using only mechanical excavation for this reference project.

Two Herrenknecht SBRs excavated the ground by a partial-face cutting method, using a cutting drum mounted on a telescopic boom. The excavated rock was then conveyed from the bench by an innovative pneumatic mucking system (PNM) and transferred into muck buckets to be hoisted to surface, the company said.

An innovative laser navigation system designed by the Herrenknecht subsidiary, VMT Group, using target units mounted on the SBR and lasers connected to the shaft wall, was used to keep the machines on track.

Herrenknecht, with its experience as a technology leader in mechanised tunnelling, developed the SBR for the mechanised sinking of blind shafts in soft to medium-hard rock. Based on the proven technology of the Herrenknecht Vertical Shaft Sinking Machine (VSM), the SBR offers improved safety performance compared with conventional shaft sinking methods while also achieving higher advance rates, according to the company.

The geological conditions at Jansen, however, were anything but easy. At a depth of around 450 m, the SBR encountered a layer of extremely hard competent rock causing excessive pick wear and low rates of advance. To overcome this and some further hardness challenges, the cutting drum was upgraded to a hard-rock cutting drum and torque output was doubled.

Because an existing high-pressure underground waterway, known as the Blairmore aquifer, posed a risk for water ingress into the shaft, ground freezing was executed temporarily in 2011 by BHP to a depth of approximately 650 m.

A major success in this difficult geology was the use of a mechanical ring erector, which allowed the installation of steel tubbing segments with minimal risk to personnel and a high degree of accuracy, according to Herrenknecht. The steel liner rings were installed through the Blairmore aquifer to assist in the development of a composite steel and concrete watertight liner in both shafts.

Since the project-specific design changes at Jansen required modifications to the SBRs, Herrenknecht, together with contractor DMC Mining Services, refined the SBR technology over the long term. The result is the second generation of Herrenknecht SBR technology.

As an example, the second generation SBR is equipped with an additional stabilisation level that allows the fixation of the SBR centre pipe on both ends. This ensures a stable transfer of the reaction forces from the cutting process to the shaft wall without movement of the machine – even with fluctuating excavation diameter of 8-11 m, as encountered at the Jansen potash project.

In addition to an improved filter system, a new design of the PNM system was installed in the second-generation machine, which results in a higher degree of separation in the suction tank itself, allowing wet material and even water to be handled.

Martin-Devid Herrenknecht, General Manager Mining at Herrenknecht, said: “The technical development of the second SBR generation is based on the lessons learnt from the Jansen project.” Two SBRs of this generation are currently in operation in Belarus and achieving good performance as a result of the improvements made, Herrenknecht said. “This pioneering approach is certainly a game changer for shaft sinking in soft and medium-hard rock, impacting the whole mining industry,” he said.

After the successful excavation at Jansen, another task was to be managed: the disassembly of the huge machines in the deep shafts. To remove the SBR from the shaft bottom, it was necessary to reduce the weight of the machine from 390 t to 340 t. This was achieved by stripping all components off the SBR that were in the excavation chamber. Both SBRs were safely extracted from the two shafts at the Jansen potash project in May 2019.

The Jansen potash project, located approximately 140 km east of Saskatoon, Saskatchewan, is a BHP-owned future potential potash mine with an expected initial mining output of around 3-4.5 Mt/y with valuable expansion options.