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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BarrOCa gr<strong>and</strong>e, POrTugal<br />
Scooptram ST600LP under maintenance.<br />
Crushed ore discharges onto the<br />
1,203 m-long, 17% inclined Santa Barbara<br />
conveyor belt that connects with a<br />
3,000 t-capacity coarse ore bin located<br />
beneath the mine office.<br />
Primary mine ventilation is provided<br />
naturally by several ventilation raises.<br />
Airflow is controlled by curtains in main<br />
areas <strong>and</strong> assisted by axial flow fans<br />
where needed, particularly in the stopes.<br />
Compressed air is needed for the<br />
charging of the blast holes with ANFO,<br />
Schematic of stope layout.<br />
Initial pillar Final pillars<br />
11 m<br />
5 m 3 m 5 m 3 m<br />
<strong>and</strong> a new compressor unit was installed<br />
underground in 2002.<br />
The mine is supplied by 3.0 kV electrical<br />
power, which is reduced to 380 V<br />
for distribution to equipment.<br />
<strong>Mining</strong> method<br />
The stoping process begins when spiral<br />
ramps are driven up to access the mineralized<br />
veins, <strong>and</strong> the orebody is opened<br />
in four directions <strong>and</strong> blocked out.<br />
Wolframite seam<br />
East-west oriented tunnels are called<br />
Drives, <strong>and</strong> those trending north-south<br />
are called Panels. Drives <strong>and</strong> Panels are<br />
driven 5 m-wide <strong>and</strong>, where they intersect,<br />
1.8 m-diameter raises are bored<br />
between haulage levels to act as orepasses<br />
for all of the stopes. Chutes are<br />
installed in the bottoms of the orepasses<br />
to facilitate the loading of trains.<br />
The height of the stopes is nominally<br />
2.1 m, but can increase to 2.3 m in areas<br />
where ore bearing veins are more variable<br />
in their dip, strike or thickness.<br />
Precise survey control is maintained,<br />
so that all final pillars are aligned vertically.<br />
Experience has shown that the<br />
stopes will usually begin to collapse<br />
about 4 or 5 months after extraction,<br />
which gives plenty of time to glean any<br />
remaining fines from the floor.<br />
Stope drilling is carried out by new<br />
generation Atlas Copco Rocket Boomer<br />
S1L low profile electric hydraulic single<br />
boom jumbos. Rounds are drilled 2.2<br />
m-deep, utilizing a Vee-cut, <strong>and</strong> 41 <strong>and</strong><br />
43 mm-diameter drill bits. Drilling is<br />
carried out on two shifts, with about<br />
28 holes required per 5 m-wide round.<br />
ANFO is loaded pneumatically into<br />
138 underground mining methods