In POLE POSITION!

Drill rigs triumph at two tough sites

Atlas Copco drilling equipment is earning praise at two demanding sites in Poland - one of Europe's largest copper ore mines where drift height is less than three metres, and a basalt quarry said to have the worst rock conditions in the country.

One of the main products from the copper ore produced at the KGHM Polkowice-Sieroszowice mine in south-west Poland is information technology network cables. And demand for the product is high with the mine working three shifts a day round the clock.

Production stopes have a very low roof height of 2.5-3 metres which means that small and versatile drilling rigs are essential which is why the mine uses four low-built Atlas Copco drill rigs.

One single-boom Boomer 126-4/28 has been operating there since 1996 and three new Boomer rigs joined it in April this year. And these are all equipped with COP 1238 ME rock drills which drill 3 metres per minute.

There's little room for manoeuvre in the confined space of the KGHM Polkowice Sieroszowice copper mine, where production drifts are less than three metres high. A fleet of low-built Atlas Copco drill rigs was chosen for the job.

The technique employed is room-and-pillar mining in dolomite rock and 35,000 tonnes of ore is mined per day. Total drilling time at a depth of 800 m is 4.5 hours per day, with scaling and rock reinforcement taking approximately one hour. Hole diameters are 45, 52 and 64 mm and work is carried out at a minimum of four faces per shift.

Josef Machel, Mechanical Supervisor, Underground, says that production from the Boomer rigs is higher than from other rigs at the mine.

"We are extremely pleased with the productivity of the Boomer rigs," he says. "The drilling is highly effective and the servicing is good. They are easy to manoeuvre and are well-suited to the restricted space in this mine. A single set-up for the whole face also makes the work easier and more precise."

The mine employs some 4,000 people and is part of the state-owned KGHM organisation which also operates the divisions of Lubin and Rudna mines on the same orebody. At its current production rate, the 400 square kilometre orebody, is estimated to have a life of another 50 years.

The Rebiszòw quarry in the south-west, produces basalt and the contractor there is Polskie Kruszywa Mineralne (PKM).

Bad conditions

The heavily-fissured and loose rock at the site is accompanied by water and clay - and the conditions for drilling have been described as "the worst in the country." Total excavation at the quarry was only 800 tonnes per year and it was decided to boost productivity by switching from pneumatic to hydraulic drilling. PKM set out to find the best equipment for the job.

Lech Rajca, Technical Manager of PKM, says: "We are confident the F7 will help us reach our target of 3,000 drillmetres per month."

Says Technical Manager Lech Rajca: "The rock is extremely troublesome and we had problems trying to drill holes with some of the hydraulic equipment we tried before. Drill steel got stuck in holes and was lost, delaying the project and reducing the number of holes we were able to drill per day."

PKM finally chose a ROC F7 crawler rig from Atlas Copco, equipped with COP 1840 HEX rockdrills, and drilling operations are now proceeding successfully.

Good choice

"The rockdrill is equipped with an extractor that reverses drilling to prevent the drill string from getting stuck," says Mr Rajca. "Our decision to choose an Atlas Copco rig was obviously a good one and we now have normal production in the quarry. In fact, we are confident of reaching a higher target - 3,000 drillmetres per month - which is what we really need."

Penetration at the quarry is around one metre per minute using TAC guide tubes. Holes of 102 mm are drilled in a pattern of 2x2 metres on the 16-18 m benches.

Lech Rajca concludes: "Atlas Copco has a Poland-based company and this was an important factor in choosing the ROC F7. We feel happier having a local company than a dealer representing Atlas Copco - especially as we may go for a service contrac later on."

All smiles underground: The hard-hat team at Polkowice Sieroszowice, one of Europe's largest copper mines, takes a break to welcome Mining & Construction's correspondent Charlotte Ericsson to the site in south-west Poland.