DRILL & BLAST
A
s he drives down a foggy access tunnel, Jani Ollikainen comments, “It’s toughest in the winter
– sometimes you can hardly see anything.” T e production planner at Agnico Eagle’s Kittilä goldmine is en route to see the Rhino 100HM raise borer work on a previously mined and back-fi lled stope, opening up a new slot hole into the next stope above. T e Rhino is a highly productive raise boring system, and the team at Kittilä is taking advantage of its benefi ts to meet ever-increasing production targets. T e Agnico Eagle Kittilä goldmine, a two-hour ride north of the Arctic circle in Finnish Lapland, is a 4,000-tonne-per-day operation that expects to produce around 200,000 ounces of gold in 2016. It uses the Rhino 100HM raise borer for slot hole drilling in production and also for drilling shafts for the mine infrastructure. At the underground mine, the largest primary gold producer in Europe, raise boring of slot holes replaced drop raises built by drilling and blasting using regular long-hole top-hammer drill rigs, which had become a bottleneck. “When we realised that the traditional raise drilling method did not meet our production needs, we had a joint vision of the way we should move forward,” says Matias Suomela, general supervisor, underground, at Kittilä.
Deciding factors Using long-hole drilling for the drop raises not only doubled the number of holes, due to the smaller diameter, but also made it necessary to blast the drop raise in fi ve-metre breaks, which requires a lot of space and involves considerably more work stages. Now,
with a raise borer, all of this could be replaced with a single machine and a single operator.
A safety consideration was also
involved in the initial process design stage. T e old method required redrilling after each blast to open closed holes thanks to the challenging rock conditions in the sulphide-rich mineralisation. Redrilling holes after blasting is inherently risky because of any undetonated explosives possibly left in the holes that could explode during redrilling. T e new method eliminates this risk entirely because the slot holes require no blasting at all. TRB-Raise Borers, a nimble mine technology company based in Tampere, Finland, nearly 900km south, had a solution for the demanding specifi cation. Together with Sandvik – the Rhino is equipped with Sandvik tools and distributed by Sandvik – the company has supplied raise boring solutions for diameters of up to 4.5m since 1972. T e applications have mostly involved conventional raise boring and box boring jobs to build ventilation shafts, ladderways and even nuclear waste depositories. In addition to the actual drilling unit, the rubber wheeled unit powered with a turbo-charged 186kW diesel engine carries all the required auxiliary equipment, including drill rods and non-rotating stabilisers, a hydraulic crane for handling them, hydraulic power pack and pressure washer as well as the necessary power and water supply connections. T e operator sits in an air-conditioned and soundproofed safety cabin. In other words, the Rhino 100HM is a self- suffi cient unit and can transport all the equipment required in the Kittilä mine’s conditions.
A turbo-charged 186kW diesel engine carries all the required auxiliary
www.engineerlive.com 7
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52