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Impressive Output

Svea North is located some 40 km from

Spitsbergens main town of Longyearbyen,

and there is a fully-functioning mine

encampment at the site. There is no road,

and the only access is by boat in summer,

snowmobile in winter, or by the daily

flights into the airstrip.

Despite its remote location, Svea North

produced an output of nearly 2.7 million t

from its single longwall face in 2003.

Indeed, in October, 2003, the mine pro-

duced a creditable 460,000 t, taking it to

the number one position in Europe.Average output per miner of 75 t/shift

makes it one of the most efficient under-

ground coal mines in the world.

The seam averages 3.8 m thick, with

few geological faults, and good overall

conditions. It lies under 400 m of rock and

200 m of ice at its deepest, while at its

shallowest point, there is just 50 m of rock

between the coal seam and the glacier. The

estimated coal reserve is 40 million t, of

which SNSK expects to mine something

like 32 million t. It is a very marketableproduct at 32 MJ/kg, with a low ash

content of 5%, and a low sulphur content

at 0.6%.Svea North is accessed by simply

driving into the drift in a conventional

four-wheel drive vehicle.

SPITSBERGEN, NORWAY

FACE DRILLING 43

Tunnelling Beneath a Glacier

Record PerformanceSpitsbergen, a Norwegian archipel-ago located in the Arctic ocean some12 degrees south of the North Pole,was first mapped officially by Dutchsailor Willem Barents in the late16th century. Russian geologist, VARusanov, discovered extensive coaldeposits in 1912, which are currentlyexploited under an internationaltreaty. Svea North mine, developedin 1999, is located beneath a glacier,over which owner SNSK has had tohaul its output along an ice roadto the port area. The solution was to

drive a tunnel beneath the glacierand replace trucks with conveyor. Inthis remote and harsh location, con-tractor Leonhard Nilsen & Sonner(LNS) needed reliable equipmentwith good manufacturer support.They chose an Atlas Copco RocketBoomer L2 C drillrig, and not onlycompleted on time, but also broke afew tunnelling records along theway!

Svea North is accessed by sea during

the summer.

Charging the face from the rig basket.

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Since production commenced, a com-

bination of on-off highway trucks and

ADTs has hauled the coal the 6 km or so

from the stockyard at the pit entrance to

the port area, making up to 50,000journeys/year.

As the fjord freezes during winter, the

coal is kept in a 1.6 million t-capacity

stockpile beside the port until the ships can

again make their way to the dock.

Keeping an ice road open in such a

climate is not easy, with around NKr 5 mil-

lion/year spent on grading alone, to main-

tain the required capacity of 16,000 t/day.

The wear and tear on trucks and loading

equipment added greatly to this bill,

making it imperative that an alternative

solution be found.SNSK decided to replace the ice road

with a tunnel under the glacier. The 2.6%

dipping tunnel alignment lies beneath the

production seam, and it is designed to house

both a conveyor system, and a channel to

drain ground water percolating through the

mine from a lake beneath the glacier.

The mine has suffered problems with

excessive water, despite its powerful

installed pump station and lengthy

pipelines. Water ingress is greater in

summer because of the thaw, evidenced bythe longwall being put out of action by

flooding for much of July and August,

2002.

Tunnel Drivage

LNS was awarded the contract for the

5.6 km-long x 38 sq m tunnel, and started

its development in November, 2002, using

a new Atlas Copco Rocket Boomer L2 C

drillrig. Planned advance of 100 m/week

was easily exceeded, with a world

drill/blast record of 150 m being achieved

in the best week.

This rate of advance is normally

achieved using TBMs, and is extremely

significant for a drill and blast operation

because of the dramatic difference in capi-

tal employed.

Rock conditions are relatively soft,

competent and not generally abrasive,although there is some quartzite intrusion.

LNS used 48 mm bits with three holes in

front and ballistic buttons, which lasted

from 300-500 m before regrinding. For

each round, the blastholes were drilled to

depths of 5 m and took around 1.5-3 min-

utes apiece, with 75-76 holes required for

a full pattern. Productivity was kept at a

high average rate, with LNS achieving 3-4

rounds/day, and sometimes five. In the

worst conditions, this dropped to two

rounds/day.For charging the upper holes and the

cut, the Rocket Boomer was equipped with

a Dyno hose charger mounted in the

basket. With this device it was possible to

regulate the volume of explosives injected

into each hole. A second hose was used

manually for charging the holes in the

lower part of the face, without the option

to regulate the volume of explosives

injected. A standard emulsion explosive

was used, mixed in the hole and detonated

using Nonel. Emulsion explosives are

more expensive than ANFO, but theirmuch-reduced blasting fumes allow opera-

tors to return to the face quicker after each

blast. Another advantage is that emulsion

components can be transported under the

flammable material rules, and are not

classified as explosive until they are in the

hole.

The mucking operation took around

1.5-2 h for around 380 t of blasted rock. A

conventional loader was used, with a fleet

of six trucks, with a grader keeping the

roadway clear and smooth. A face crew ofsix was sufficient for each of the two

SPITSBERGEN, NORWAY

44 FACE DRILLING

Atlas Copco Rocket Boomer L2 C at the

face.

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shifts/day, while the total LNS crew on this

project was 52.

The tunnel was started in permafrost,

with a 400-500 m transition zone at each

end to reach solid rock. In these zones,

melting ice caused problems with the shot-

crete application. LNS employed an accel-

erant in the shotcrete mix, and reinforced it

with steel fibres. Two rockbolts were gen-

erally required for each metre advance, but

problems with rock pressures sometimes

necessitated more extensive bolting, and

use of a hydraulic scaler. Polyester roof-

bolts were replaced by 2.4 m and 3 m

Swellex Manganese bolts in some of the

more difficult areas.

The drill and blast portion of the tunnel

project is now complete. Fitting out, and

installation of the ventilation and conveyor

systems, should be finished by the end ofthe first quarter of 2004.

Equipment Modifications

The Rocket Boomer L2 C drillrig was

fitted with Atlas Copcos ABC Regular

control package, which indicates the hole

positions, but does not include full-function

automatic boom movement.

The contractor has had experience using

a computerized Rocket Boomer XL3 C on

the Norwegian mainland, but it was still amajor decision to send an RCS drillrig to a

remote location like Spitsbergen. During

commissioning, Atlas Copco provided

three or four days of basic training at site

to the new operators. The instructor then

remained in support for another three

weeks, and returned some months later for

a week of follow-up training. The contrac-

tor has taken care of maintenance and

operation of the rig during the entire pro-

ject using his own people, without the need

of outside assistance.

In the transition zone between the per-mafrost and the rock, it was found that the

conventional anti-jamming system fitted to

the drillrig did not give sufficient warning

of jamming, resulting in some rod damage.

Atlas Copco suggested an alternative pro-

gram, which suited the conditions better by

simultaneously monitoring rotation, feed

rate and water flow. This resolved the

problem, and there were no more instances

of rod damage caused by jamming.

By agreement with LNS, Atlas Copco

evolved a package of spares suited to theremoteness of the operation. However,

reliability was good, and only the usual

service parts such as filters and hoses were

required.

The SNSK mine also has an Atlas

Copco Swell bolter, originally supplied in

1986. This rig was rebuilt in 2001 and

equipped with the new HBU bolting unit

with a COP 1028 hydraulic rock drill. This

bolting unit is used in parts of the mine

with hard sandstone layers, where rotary

drilling cannot be used.

Svea Norths future looks good. The

mine has a projected life until 2013, andthere are another two deposits of 3.5

and 2.7 million t nearby that SNSK may

wish to develop. The company is also car-

rying out exploration work elsewhere on

Spitzbergen.

Acknowledgements

Atlas Copco is grateful to SNSK and LNS

for permission to publish this article,

which is derived from a site report written

by Mike Woof, editor of World MiningEquipment magazine.

SPITSBERGEN, NORWAY

FACE DRILLING 45

Rockbolts and shotcrete provide the

main support.