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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zinkgruVan, Sweden<br />
Boltec LC installing rockbolts in a development drift.<br />
a 165 mm hole for gravitating into Nygruvan,<br />
<strong>and</strong> a 300 mm hole for pumping<br />
under high pressure into Burkl<strong>and</strong>.<br />
The fill is transported through 6 in<br />
steel pipes along the distribution levels,<br />
connected by plastic pipes into the<br />
stopes.<br />
Advantages of longhole open stoping<br />
with paste fill are: improved working<br />
environment for all underground activi-<br />
ties with regards to exposure of open<br />
stopes <strong>and</strong> backfill; reduced pillar<br />
reservation, leading to increased ore<br />
reserves; increased flexibility, with<br />
more stopes in simultaneous production<br />
<strong>and</strong> lower grade fluctuation; all tailings<br />
can be used; no bulkheads required;<br />
reduced drainage water; <strong>and</strong> possibility<br />
of filling ab<strong>and</strong>oned stopes.<br />
Disadvantages are: higher costs than<br />
conventional hydraulic fill; <strong>and</strong> plugged<br />
fill pipes <strong>and</strong> drill holes require more<br />
effort.<br />
The long-term focus is directed towards<br />
optimization of the water/cement<br />
ratio in the paste fill, with a view to<br />
reducing the amount of cement used.<br />
lower development<br />
In order to mine below the 800 m level,<br />
the mine uses three Kiruna Electric<br />
trucks for ore <strong>and</strong> waste haulage to the<br />
main crusher. A Simba M4C longhole<br />
drill rig is used on production, drilling<br />
up to 40 m-long x 76 mm or 89 mmdiameter<br />
blastholes. The machine produces<br />
some 50,000 drillmetres/year,<br />
while an older Simba 1357 drills a similar<br />
number of metres in the 51-64 mm<br />
range. The mine is so impressed with<br />
the stability of the Simba M4C rotation<br />
unit that it has had an old Simba 1354<br />
rebuilt to incorporate the same unit. A<br />
new Simba M7C h<strong>and</strong>les the cable bolt<br />
drilling. The drilling consumables are<br />
supplied by Atlas Copco Secoroc under<br />
contract. The ramp will be driven from<br />
the current 980 m to the 1,100 m level.<br />
An Atlas Copco Rocket Boomer L2 C<br />
is used on ramp <strong>and</strong> sublevel development,<br />
where the requirement is for 18<br />
rounds/week on a 2 x 7 h shift basis.<br />
The mine has purchased a second twin-<br />
boom Rocket Boomer, this time an M2 C,<br />
which is the mining version of the<br />
Rocket Boomer L2 C.<br />
rock reinforcement<br />
The mine installs up to 20,000 resin anchored<br />
rockbolts each year, <strong>and</strong>, having<br />
upgraded its production process, found<br />
that bolting became the new bottleneck.<br />
After prolonged testing of the latest<br />
Atlas Copco Boltec LC, they ordered<br />
two units.<br />
Using these machines, the working<br />
environment for the bolting operatives<br />
has improved immeasurably, since the<br />
continuous manual h<strong>and</strong>ling of resin<br />
cartridges has been eliminated. The<br />
Boltec LC is a fully mechanized rockbolting<br />
rig, with computer-based control<br />
system for high productivity <strong>and</strong> precision.<br />
The Zinkgruvan models feature a<br />
new type of magazine holding 80 resin<br />
cartridges, sufficient for installation of<br />
16 rockbolts. It is equipped with a<br />
stinger, which applies constant pressure<br />
to keep it stable at the hole during the<br />
entire installation process. The operator<br />
can select the number of resin cartridges<br />
to be shot into the hole, for which the<br />
blow capacity is excellent.<br />
The Rig Control System (RCS) fea-<br />
tures an interactive operator control<br />
panel, with full-colour display of the<br />
computer-based drilling system. Automatic<br />
functions in the drilling process,<br />
such as auto-collaring <strong>and</strong> anti-jamming<br />
protection, as well as improved regulation<br />
of the rock drill, provide high per-<br />
formance <strong>and</strong> outst<strong>and</strong>ing drill steel<br />
economy. There is integrated diagnostic<br />
<strong>and</strong> fault location, <strong>and</strong> a distributed<br />
hydraulic system, with fewer <strong>and</strong> shorter<br />
hoses for increased availability. Data<br />
transfer is by PC-card, which also<br />
allows service engineers to store optimal<br />
drill settings.<br />
The MBU bolting unit on the Boltec<br />
LC features a single feed system, utilizing<br />
a cradle indexer at the rear end,<br />
<strong>and</strong> a robust drill steel support plus<br />
indexer for grouting at the top end. It is<br />
equipped with a low-mounted magazine<br />
for 10 bolts, designed for maximum<br />
56 underground mining methods