Mining_Methods_UnderGround_Mining - Mining and Blasting
Mining_Methods_UnderGround_Mining - Mining and Blasting
Mining_Methods_UnderGround_Mining - Mining and Blasting
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
garPenBerg, Sweden<br />
Simba M7 C production drill rig at Garpenberg.<br />
mine led to the progressive extension<br />
of a 1:7 ramp down to the 910 m level.<br />
In 1998-9, it was extended to the 1,000<br />
m level, increasing the overall length to<br />
8.7 km.<br />
To increase hoisting capacity at the<br />
Garpenberg mine, the new Gruvsjö production<br />
shaft was completed in 1997<br />
<strong>and</strong> the original shaft was converted<br />
for personnel <strong>and</strong> materials hoisting.<br />
With a hoisting capacity of 450,000<br />
t/y, the newer shaft connects with a<br />
ramp accessing the Kanal <strong>and</strong> Str<strong>and</strong><br />
orebodies.<br />
The present operating area extends<br />
approximately 4.5 km SW to NE from<br />
the original shaft to the Gransjön mining<br />
section.<br />
Concentrate production<br />
Upgraded in the early 1990s, the concentrator<br />
yields separate zinc, lead,<br />
copper <strong>and</strong> precious metals concentrates.<br />
The zinc <strong>and</strong> lead concentrates<br />
are trucked to Gävle harbour <strong>and</strong> ship-<br />
ped either to Kokkola in Finl<strong>and</strong> or Odda<br />
in Norway. Copper <strong>and</strong> precious metals<br />
concentrates are railed to the Rönnskär<br />
smelter in Sweden. Since 1957, Boliden<br />
has milled over 20 million tonnes of ore<br />
at Garpenberg.<br />
While the new shaft raised hoisting<br />
capacity, <strong>and</strong> ramp extension accessed<br />
new ore in the North mine, metals production<br />
rose to record levels in 1998.<br />
However, this improvement could not<br />
be maintained. Zinc concentrate output<br />
fell from 69,051 t in 1998 to 61,126 t in<br />
2001, despite a rise in ore production.<br />
And proven plus probable ore reserves<br />
declined from 5.7 Mt in 1998 to 2.2 Mt<br />
at 4.0% Zn in 2003, putting a question<br />
mark on the future of the mine.<br />
However, Boliden continued to make<br />
investments in technology for the long<br />
term at Garpenberg. The mine, the company<br />
<strong>and</strong> the market are now benefiting.<br />
And the geologists are very popular.<br />
new reserves<br />
Probably the most significant event at<br />
Garpenberg during the period of decline<br />
was the discovery in 1998 of a new orebody<br />
between Garpenberg North <strong>and</strong><br />
Dammsjön, named Lappberget. This<br />
encouraged the company to start development<br />
in 2000 of an approximately<br />
3.0 km-long drift to connect the 900 m<br />
level at Garpenberg North, first to Lapp-<br />
berget for exploration access, <strong>and</strong> thence<br />
to the ramp at the 800 m level at Garpen-<br />
berg. During 2001, Boliden started core<br />
drilling at the 800 m <strong>and</strong> 1,000 m levels<br />
in Lappberget, <strong>and</strong> by February, 2003<br />
was able to start mining ore from the<br />
new source. Zinc concentrate production<br />
in the year increased to 80,748 t.<br />
In March, 2004 the connecting drift<br />
was completed, <strong>and</strong> the formerly separate<br />
mines have since been regarded <strong>and</strong><br />
managed as a single operation. The drift<br />
allows access <strong>and</strong> infrastructure deve-<br />
lopment of new mineable areas, <strong>and</strong><br />
Garpenberg quickly boosted mine output.<br />
The main focus has been on Lappberget,<br />
including driving a ramp close to the ore-<br />
body from the 350 m level, with connection<br />
to the surface scheduled for 2007.<br />
The Tyskgården mineralization, discovered<br />
in the early 1980s, also became<br />
accessible, <strong>and</strong> mining started there in<br />
2003-4. In 2004 Boliden discovered an<br />
extension of the Dammsjön mineralization<br />
around the 800 m level, <strong>and</strong> during<br />
2005 a new discovery was made, the<br />
reportedly large <strong>and</strong> potentially highgrade<br />
Kvarnberget deposit.<br />
Higher output<br />
In 2005, the mine produced 1,102,000 t<br />
ore grading 5.75% Zn, 2.28% Pb, 0.09%<br />
Cu <strong>and</strong> 117 g/t Ag. Approximately 40%<br />
of the ore came from Lappberget. The<br />
mill yielded 101,000 t of 55.3% zinc<br />
concentrate; 29,000 t of 72% lead concentrate<br />
with 1,800 g/t silver; 2,800 t<br />
of 15% copper concentrate with 40,000<br />
g/t; <strong>and</strong> 120 t of precious metal concentrate<br />
grading 65% lead, 40,000 g/t<br />
silver <strong>and</strong> 400 g/t gold. Some 967,000<br />
t of tailings retained 0.34% Zn, 0.29%<br />
Pb, 0.02% Cu <strong>and</strong> 25.5 g/t Ag. By end-<br />
2005 Boliden employed 280 people at<br />
Garpenberg, with a further 70 working<br />
for contractors at the site.<br />
The operation works around the<br />
clock 7 days/week in both the concentrator<br />
<strong>and</strong> the mine, with mining<br />
carried out by four production teams<br />
supported by a development crew <strong>and</strong><br />
a charging crew. Garpenberg is the<br />
Hedemora Community’s largest private<br />
sector employer.<br />
Since the start of 2005 exploration<br />
has continued, not only adding tonnes,<br />
but also raising average grade. Thanks<br />
to the exploration effort, Garpenberg<br />
also started 2006 with proven reserves<br />
of 4.73 Mt grading 6.0% Zn, 2.5% Pb,<br />
48 underground mining methods