Mining_Methods_UnderGround_Mining - Mining and Blasting
Mining_Methods_UnderGround_Mining - Mining and Blasting
Mining_Methods_UnderGround_Mining - Mining and Blasting
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History<br />
<strong>Mining</strong> has been conducted at Garpenberg<br />
since the 13th century. The present<br />
operations started in 1950-53, when<br />
AB Zinkgruvor developed a new main<br />
shaft <strong>and</strong> concrete headframe <strong>and</strong> the<br />
adjacent concentrator. Boliden acquired<br />
the mine in 1957 <strong>and</strong> completed the<br />
development of a second shaft in 1972,<br />
accessing the 800 m level at Garpenberg<br />
North, having a hoisting capacity of<br />
850,000 t/y <strong>and</strong> effectively creating a<br />
second <strong>and</strong> larger mine.<br />
Between these two shafts, the company<br />
located another orebody under a<br />
lake at Dammsjön <strong>and</strong>, in the 1980s,<br />
considered draining the lake in order<br />
to develop an open pit.<br />
The mineralization in the Garpenberg<br />
area occurs in a long, narrow synclinal<br />
structure which is believed to be<br />
Middle Precambrian, but may have been<br />
remobilized later. The orebodies are<br />
vertically extensive lenses that are usually<br />
narrow, much folded <strong>and</strong> therefore<br />
twisting <strong>and</strong> irregular.<br />
Cut <strong>and</strong> fill<br />
Until very recently all of the ore, subdivided<br />
in 100 m-high slices, was extracted<br />
by cut-<strong>and</strong>-fill mining, taking<br />
garPenBerg, Sweden<br />
innovative mining at garpenberg<br />
0 Z<br />
400 Z<br />
800 Z<br />
1200 Z<br />
Garpenberg<br />
Lina shaft<br />
Kanal Ore<br />
Str<strong>and</strong> Ore<br />
Potential ?<br />
One million<br />
tonnes of ore<br />
Gruvsjö shaft<br />
Capacity: 450 000 tpa Smältarmossen<br />
Finnhyttan<br />
Tyskgården<br />
Production levels<br />
Potential areas outside ore reserves 2005-01<br />
The Garpenberg mine, located<br />
200 km northwest of Stockholm,<br />
extracts more than 1 million t/y of<br />
ore. The ore is polymetallic <strong>and</strong><br />
contains mainly zinc, silver <strong>and</strong><br />
also some lead, copper <strong>and</strong> gold.<br />
Additionally, about 500,000 t of<br />
development waste is excavated<br />
annually. Over recent years, Gar-<br />
penberg has been forced to add<br />
reserves, or reconsider its future.<br />
Happily, more orebodies have<br />
been discovered, <strong>and</strong> new stoping<br />
methods <strong>and</strong> drilling technology<br />
introduced. Atlas Copco has co-<br />
operated closely with Garpenberg<br />
management to resolve technical<br />
issues, designing <strong>and</strong> supplying<br />
equipment to suit the<br />
evolving objectives. As a result,<br />
the mine achieved over 1 Mt of<br />
ore in 2005, at very acceptable<br />
grades.<br />
?<br />
?<br />
Dammsjön<br />
Dammsjö Agmin<br />
500-785 Z<br />
925-1100 Z<br />
700-<br />
1000 Z<br />
Dammsjön Kvarnberget<br />
Lappberget<br />
Kaspersbo<br />
910 Z<br />
1000-1300 Z<br />
5-6 m-thick slices drilled horizontally<br />
from 50-300 m-long <strong>and</strong> up to 15 mwide<br />
stopes. Rock fill was used in the<br />
bottom cut, <strong>and</strong> either plain s<strong>and</strong> or<br />
cemented hydraulic fill above. The<br />
s<strong>and</strong> comes from the coarse fraction of<br />
the mill tailings, <strong>and</strong> the fill is supplemented<br />
by development waste.<br />
<strong>Mining</strong> starts normally at the centre<br />
of the base level of the stope <strong>and</strong> progresses<br />
towards the ends <strong>and</strong> upwards.<br />
The last cut, just below the crown pillar,<br />
is heavily reinforced to facilitate the<br />
recovery of the 8-15 m-high pillar using<br />
up holes drilling <strong>and</strong> blasting.<br />
The undercut-<strong>and</strong>-fill method, progressing<br />
downwards, was used in the<br />
Str<strong>and</strong>gruvan section from the mid-70s<br />
until 2001, when the ore was mined out.<br />
This method provided a safe working<br />
roof in the weak, fractured ore with<br />
unstable footwall, for just the extra<br />
cost of cement <strong>and</strong> rebar reinforcement.<br />
The method was suited to the orebody<br />
irregularities, <strong>and</strong> no crown pillar had<br />
to be left or recovered. The introduction<br />
of trackless mining <strong>and</strong> further exploration<br />
of the mineralization in the North<br />
underground mining methods 47<br />
500-<br />
800 Z<br />
1100-<br />
1400 Z<br />
Garpenberg North<br />
Shaft<br />
Capacity: 850 000 tpa<br />
Gransjön<br />
1600 Y 2000 Y 2400 Y 2800 Y 3200 Y 3600 Y 4000 Y 4400 Y 4800 Y 5200 Y<br />
Idealized long section at Garpenberg showing all orebodies <strong>and</strong> shafts.<br />
870 Z<br />
0 Z<br />
400 Z<br />
800 Z<br />
1200 Z