Working together with the Rio Tinto mining company, Herrenknecht engineers developed a Shaft Boring Machine (SBM) to extend safe, economical and, above all, rapid exploration capabilities to deep-lying deposits. This highly mechanized machine can create blind shafts with diameters of up to 12 meters in stable rock down to depths of 2,000 meters.
Innovation from proven technology
Some basic differences in comparison to horizontal tunnelling had to be considered in the development of this new shaft boring machine, which is similar to a conventional tunnel boring machine. One major challenge was to raise the excavated rock from the shaft bottom and to transport it vertically through the machine up to the transfer point for shaft conveyance. The solution: The cutting wheel was turned by 90 degrees and the rock is excavated in two consecutive steps.
In the first step, the cutting wheel penetrates the rock like a circular saw, thus creating a slit with a depth of 1.5 meters. In the second step, it rotates around the vertical axis of the machine to cut out the entire shaft profile. In doing so, the cutting wheel not only loosens the rock but also serves as a paddle wheel which transports the muck via integrated channels to the center. There the material is transferred to a vertical belt conveyor, which transports it to the transfer point for shaft conveyance. Up to 3 gripper systems brace against the shaft wall and thus stabilize the entire system during the tunnelling procedure.
High safety thanks to modern technology
In the development of the SBM, a strong focus was placed on increasing occupational safety. As is the case with a hard rock TBM, shotcrete is introduced per remote control directly behind the cutting wheel. The disc cutters are replaced in a specially secured working area which is easily accessible and protected against falling rock. Thus, no personnel have to remain in dangerous areas during normal operation.
With the Shaft Boring Machine SBM Herrenknecht has developed, together with Rio Tinto, a machine concept that meets the new requirements of the mining industry. Both the rapid construction time for shafts and the high level of safety are placed in the focus of new developments for the mining sector.
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