Björkdalsgruvan discovers the benefits of SSAB Virsbolt

SSAB approached Björkdalsgruvan in 2023 and presented their SSAB Virsbolt expandable rock bolt. This bolt is a well-established product since several decades. It consists of a folded pipe that is expanded with high pressure water inside a borehole. The friction against the rock creates a strong holding force, effectively securing the tunnel roof or wall.

After some testing in 2023, the team at Björkdalgruvan started to use SSAB Virsbolt 240 in 3.6 meter length regularly. During 2024 they have continued to order more bolts, now also in 5 meter length.

Before SSAB Virsbolt came into the picture, Björkdalsgruvan relied exclusively on cement-grouted rebars and cable bolts as rock support for the mine.

“We still use a lot of rebar, but SSAB Virsbolt is a lot less hassle for our operators. Anybody can use it and get a consistent result, which of course is a vital safety issue. With rebars, grout has to be mixed to the right thickness and that leaves room for variations. It also needs a lot of cleaning that is messy and takes up time. SSAB Virsbolt is easier to use and we are very happy so far.”

Fredrik Wallström at Björkdalsgruvan

The mine is also looking into two other versions of SSAB Virsbolt, the coated version and the 240 light version. The coated bolts are to meet regulations on public safety decades into the future, if or when the mine is depleted. Tests are currently under way to establish the corrosive conditions in the rock as a base for assessing the probable lifespan. The Virsbolt light version is made of an even more high strength steel then the regular Virsbolt. That makes the light version to perform the same as the regular Virsbolt but with less weight. This improves the work environment and makes the manual handling of the bolts easier for the miners. It also more cost efficiency for the mine since the freight cost getting lower.