Record-breaking raise boring by Drillcon at Zinkgruvan with Sandvik tech
Long raise bore shafts require extensive planning, skilled operators and reliable drilling tools. Combining these elements can lead to remarkable achievements, such as breaking the Scandinavian record by drilling a +700 m ventilation shaft in a single pass.
At Zinkgruvan Mining, the southernmost mine in Sweden, Drillcon Group commenced the raise bore project for ventilation shaft number five in April 2024. This shaft is the second of two parallel shafts, and part of the Dalby mine expansion. The raise bore operations followed a conventional approach, starting with a +700 m pilot hole down and then reamed back up 700 m with a 4.1 m reamer. However, the tools provided by Sandvik were anything but conventional. The Drillcon team utilised the newly launched and innovative Sandvik RR890 pilot bit, the latest design of the 12EL reamer head and modernised cutters equipped with patented PowerCarbide® technology.
“Completing a full raise without needing to replace the cutters or service the reamer is a remarkable achievement, and we are thrilled to have the Sandvik raise boring team supporting us in making this happen,” said Jonas Myrzell, Production Manager Raise Boring at Drillcon Group.
The revised raise boring tools are part of Sandvik’s commitment to offering premium quality, long-lasting and high-performing products to its global customers. By incorporating the latest innovative technology, along with comprehensive support and service, Sandvik says it ensures its customers can keep drilling efficiently.
“We are thrilled with the successful raise boring results Drillcon achieved in this project, and the high expectations we had for our optimised raise boring tools were met,” said Russell Clayton, Product Manager Raise Boring at Sandvik Rock Tools. “Our new Sandvik RR890 pilot bit features PowerCarbide® inserts, full leg protection and a patented dual-seal roller bearing to extend service life and enable more even rock breaking. Together with Drillcon, we also trialed our upcoming generation of cutters equipped with PowerCarbide® inserts, focusing primarily on enhanced wear resistance and extending service life. We also upgraded our standard reamer head model based on field experience in general, and close collaboration with Drillcon, to meet the specific needs of this raise.”
The results speak for themselves, and calculations by Drillcon verify the successful outcomes. The pilot bit showed a 69% increase in performance compared to previous Sandvik versions, and the reaming lasted an entire 700 m pass without changing a single cutter.
Operators described the user experience of the updated raise boring tools as smooth, reliable and consistent, with excellent tracking of the drill plan in terms of metre advancement per day.
“Our top priority for all raise bore operations is to provide a safer work environment for everyone involved, while also ensuring continuous speed and progress, and maintaining a cost-effective approach throughout all drilling steps,” Myrzell said. “With the tools from Sandvik lasting a full +700 m raise, we can confidently tick all the boxes. Not only did we save over three weeks in service time, but we also avoided having our operators underground, mitigating the risks associated with tool changes, heavy equipment handling and potential hazards from falling rocks.”
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