Mining_Methods_UnderGround_Mining - Mining and Blasting

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