When drilling and blasting permits, Atlas Copco Boomer L2 rigs are used, while in the poorer formations, hydraulic hammers HB 2500 and HB 7000 mounted on excavators are used. Pipe roofing is carried out using the Atlas Copco Symetrix system, radial MAI SDA self-drilling anchors and MAI M400NT pumps are used in rock reinforcement work.
“We also use steel arches and pre-cast concrete and two layers of wire mesh,” adds Kovacˇevc´, noting that in good rock, only one layer is required or no wire mesh is used at all. “If we’re lucky, our shotcrete only needs to be about 20 cm thick but often it can be over 30 cm,” he says, adding that this is proof of the poor quality of the ground. Šarani also employs three Atlas Copco Unigrout grouting platforms, two of which are Unigrout Flex M E22. Ventilation in the tunnels is provided by a fan fitted with 1 400 m of Atlas Copco flexible ducting.