• PLANT AND EQUIPMENT
in a range of other applications – from ventilation raises and escape routes to ore passes and connections between tunnels .
“ Using conventional drill and blast methods , these vertical or inclined holes can take mines three to six months to complete ,” he says . “ With the Rhino 100 , we are talking about durations of less than a week .”
Drilled as relief holes in sub-level open stoping , slot raises provide the necessary void space for blasting , allowing the expansion of blasted rock into the void to improve fragmentation . Dean Zharare , sales engineer for underground drilling at Sandvik Mining & Rock Solutions , highlights that the conventional blasting of slot raises often creates a bottleneck for mines .
“ We have encountered situations where mine personnel have to return two or three times to a slot raise before it is ready , due to misfires , for instance ,” says Zharare . “ This creates a bottleneck in the mining process , reducing the monthly metres achieved .”
The mobility and drilling speed of the Rhino 100 can transform this scenario , he says , with an expectation that monthly metres drilled could be improved by 65 %. There is even the possibility that one of the units in South Africa will be operated remotely with the operator based on surface while it drills underground stopes .
Drilling holes of 750mm in diameter , the Rhino 100 boasts penetration rates of about 2 metres per hour , more than double the rate of conventional methods . As important as the speed , he says , is the reliability of the result .
“ These larger holes make the blast much more reliable , avoiding any time consuming and dangerous redrilling in the even of a block ‘ freezing ’ after an unsuccessful blast ,” he says .
Underpinning the machine ’ s mobility is its ability to carry its own components , including rods , cables , hydraulics and the raiseboring head . It is pulled by a specially adapted doubleaxle John Deere tractor . To optimise the set-up time – which can take as little as 10 minutes – it has outriggers for stability rather than needing a concrete pad to be poured . No roof bolting is required either , as an inclinometer gives the operator the necessary coordinates for a surveyor to confirm before drilling operations begin .
Since the Rhino 100 was launched 2017 , it has achieved a strong global footprint , with over 20 units operating worldwide . Australia has seen particularly strong take-up , with one contractor already ordering four machines . Underground expansions at almost a dozen operations around southern Africa present exciting opportunities for the future of the Rhino 100 in this region , says Zharare . •
38 • African Mining • September 2021 www . africanmining . co . za