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The nuts and bolts of Virsbolt from SSAB

SSAB expandable bolts have a new name but the same quality. Quarry learns how the resources industry around the world has put them to good use.

Heavy industries rely on quality equipment, not only to keep the job done, but also to keep workers safe.

SSAB developed its Virsbolt, previously known as the ERB, to ensure workers in these industries can reinforce the rock roof, especially when mining or drilling into rocks.

Cimertex executive director Álvaro Bastos told Quarry he saw the quality of the product to be “unmatched” on the market.

“Our SSAB Virsbolt bolts are by far the market leaders because of quality and logistics,” he said.

“When our customers source the bolts, they also expect a high level of local service, and we have a structure to provide that.

“The support from SSAB is world-class, from quality and traceability to sales management.”

The Virsbolt’s fundamental feature is speed. SSAB designed the bolt to be installed and expanded as soon as the hole is drilled and water from a high-pressure pump is applied.

When the rock is expanded, it squeezes against the rock and is secured. It may seem small, but this easy install-and-expansion process saves operators from waiting for grout or resin to set or working with dangerous chemicals.

The process is conducted in four stages. The operator drills the necessary hole and the bolt is inserted before the pressure pump is attached to expand the pipe. Finally, the pressure pump is removed, and the bolt is secured in the rock.

The bolt forms a mechanical interlock between the borehole wall and the bolt over the full bolt length. When the SSAB Virsbolt is inflated, it also contracts in the bolt length, effectively tensioning the bolt’s face plate against the rock surface.

The rock bolts are designed to accommodate large rock movements and maintain their high load-bearing capacity. SSAB Virsbolt is suitable for both manual and mechanised installation.

The Virsbolt, made from pure steel, does not impact the natural environment negatively and is not disrupted by drill vibrations.

The SSAB Virsbolt was previously known as the ERB. Image: SSAB

The Neves-Corvo underground copper-zinc mine in Portugal, operated by Somincor, has used Virsbolts for years. The mine processes around 2.6 million tonnes per year, which means its products need to withstand high drilling loads.

The company has employed the use of SSAB’s Virsbolt across its mining operations due to its installation process, which prioritises worker safety.

“SSAB Virsbolts fit our needs regarding our safety standards and the fact that we do not feel the necessity of change because operational and performance issues prove that this support has been fulfilling our operational requirements,” Somincor, head of rock mechanics Rodolfo Machado, told Quarry.

“The fact that the industry is moving in a sustainable direction also speaks strongly for this technology.”

In the Neves-Corvo underground mine, the SSAB Virsbolt serves as key support in the production phases. The Virsbolts work in challenging terrain containing sulphide.

The Virsbolt can handle arduous conditions because SSAB manufactures the bolts with high-quality Nordic steel and an extensive testing regime. This ensures the Virsbolt can handle the rigours of heavy industries, including quarrying and mining.

The bolts are guaranteed to a minimum breaking load and undergo eddy current non-destructive testing, as well as inflation and flattening tests, before being sold.

Dragon Mining, which operates the Jokisivu gold mine in Finland, attests to its structural quality. The company has used the Virsbolt at depths of 645m for rock roof support.

“We prefer inflatable bolts instead of split-set bolts due to split set’s availability issues in the Nordic region,” Jokisivu mine manager Timo Ridaskoski said.

“It’s also easier to run one bolting system rather than two. We can get the bolts directly from SSAB in Sweden, which secures our supply of bolts.” •

For more information, visit ssab.com

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