Mining_Methods_UnderGround_Mining - Mining and Blasting

7 m
9 m
gerMany/SOuTH kOrea
Pillar
Vertical benching of bottom parts
Principle mining method at Yongjeung.
Pillar
that over 5.5 million t will eventually
be mined. Average chemical analysis of
the limestone bed is CaO 54.4%, SiO 2
0.78%, MgO 0.53%, Al 2O 3 0.03%, and
Fe 2O 3 0.17%.
Around 25,000 t/month of limestone
is produced for markets that include
companies operating plants for the
manufacture of desulphurization products,
quicklime, calcium carbonate and
chicken feed.
The limestone bed is mined in three
steps, starting with 15 m-wide x 7 mhigh
room and pillar, followed by a 9 m
bench. A Rocket Boomer L1C-DH diesel
powered drill rig is the main production
machine in the room and pillar faces,
© Atlas Copco Rock Drills AB, 2000
drilling 4 m-long x 51 mm-diameter
holes. Generally, 50 holes are drilled in
each face, and three faces are drilled in
each 8 h shift. This affords a capacity
of 3,000 t/day or 70,000 t/month. When
drilling, the rig’s diesel engine operates
for around 1 min/drilled metre, consuming
0.31 litres of fuel. Returns from
rig consumables are: rods 975 m; bits
750 m; shanks 3,900 m; and sleeves
1,950 m.
An Atlas Copco ROC D5 crawler rig
is used for downhole drilling of the
bottom bench. This rig has a long folding
boom which allows the operators to
drill at a comfortable 5.5 m from the
edge of the crater, a major improvement
over the previous pneumatic rigs, which
needed to be within 2 m of the edge.
Conclusions
Where there is no suitable electricity
supply to the mining areas to power an
electro-hydraulic rig, as at Auersmacher
and Yongjeung, diesel-driven hydraulic
rigs offer a means of upgrading mining
efficiency without excessive capital
expenditure. At these mines, drilling
rates doubled with the introduction
of the Rocket Boomer L1C-DH, and
round depths increased significantly.
These machines, equipped with water
tanks and water mist flushing, operate
efficiently despite the absence of mains
supplies of water and electricity. They
are also adaptable, performing on both
production and development, and handling
rockbolt and ancillary drilling.
Production and efficiency gains have
been recorded wherever the Rocket
Boomer L1C-DH has been introduced,
making it a boon to mines where every
penny counts.
acknowledgements
Atlas Copco is grateful to the managements
at Auersmacher, Heidelberg,
TKDZ and Yongjeung for their inputs
to this article and for permission to
publish.
Rocket Boomer L1 C-DH on demonstration at Yongjeung limestone mine. Atlas Copco ROC D5 drilling the bench at Yongjeung.
128 underground mining methods