Safety in the deep

Atlas Copco’s new Roofex Rx20 rock bolt is what the company hopes will soon become an industry standard in rock reinforcement thanks to its design capabilities to handle a sliding load up to 20 tonnes and an energy absorption of 60 kJ.

The new bolt has been well received by CANMET, a leading international testing and research agency, based in Canada. In-laboratory tests show the Roofex Rx20 to be 50 to 100 times better than any comparable rock bolt on the market.

Millan Herce, a rock reinforcement specialist at Atlas Copco, Canada says: “This is very encouraging at a time when deep and high stress mining is very much in focus here and in other parts of the world.

“The mining industry is facing new challenges to extract mineral resources at increasing depths and effective bolting is a big issue in this respect.”

Roofex rock bolts are designed to extend with the movement of rock while constantly retaining their full load capacity. This is especially useful where frequent rock movements occur and for areas that are prone to seismic activity and rockburst.

“Many of our customers with very deep mining operations appreciate the Roofex Rx8 concept, but they told us they also need a bolt with much higher capacity for those extremely difficult areas and depths. We listened, and then went home and started to design it,” said Herce.

The bolt itself is also larger in diameter (50 mm) and stiffer than the 30 mm Roofex Rx8. This makes the installation procedure easier as it will not bend when it comes into contact with the rock or resin.

The bolts are also produced with a high precision “hazard” indicator which can easily be seen in roofs up to 5 m high and shows, at a glance, if rock movement has taken place.

“This gives the mine captain peace of mind. A number of companies are looking to develop the next generation bolt but we think Atlas Copco has already done it,” said Herce.

The laboratory findings will be presented in more detail at the 5th International Seminar on Deep and High Stress Mining in October this year in Chile.