Mining_Methods_UnderGround_Mining - Mining and Blasting

to the hanging wall. The fill used on
site includes uncrushed underground
development rock spoil, heavy media
reject from the process plant, or hydraulic
sand fill from the surface.
The potential hazards of loading out
from within an open stope have been
tackled by technical development. With
the benching method, teleremote production
loading was also brought in.
With this system, employing CCTV
cameras on the front and back of the
LHD, operators can now handle up to
three units by remote control from one
location. This is an air-conditioned
cabin, which may be up to 1 km away.
The system saves time spent on a job,
increases operator safety, and gives operators
more control.
The technology was practically ahead
of its time when introduced, because
it is still current. It was a step towards
the development of today’s equipment
with built-in navigational systems.
Benching has increased productivity,
improved safety, reduced costs and
provides better utilization of equipment.
The extensive mine workings at Mount
Isa incorporate a total length of under-
ground openings including road-ways,
19A
17D
18E
19/L
Huge savings in drilling consumables
Atlas Copco Secoroc workshop at Mount Isa Mines.
An alliance between MIM and Atlas
Copco Secoroc has resulted in a reduc-
tion of annual bit consumption from
28,000 to just 11,000, with no changes
in tonnages. For more than 15 years,
Secoroc had held a supply-only con-
tract for drilling consumables with
MIM. When taking over the role of
General Manager, they reviewed the
contract and found a throw-away cul-
ture that, if turned around, had the
16B
18B
19C
Tailor made stope design at Mount Isa copper mine.
orepasses and shafts, of approximately
975 km. The workings produce 10 mil-
lion t/year. Most mines have at least one
particular form of technical challenge,
and at Mount Isa it is heat, due to the
great working depths. The virgin rock
temperatures are around 60 degrees C.
MOunT iSa, auSTralia
However, with proper ventilation the
mine’s wet-bulb temperature is below
23 degrees C. The Mount Isa ventilation
system is one of the largest of its kind
in the world, and includes bulk coolers
on the surface to cool the air before it
goes underground.
underground mining methods 103
19C
18E
potential to markedly save costs and
improve safety. The original consuma-
bles contract was not providing enough
information to the supplier. This reali-
zation was instrumental in changing
the contract from supply only, to full
service and supply. MIM is a very large
and busy company, making the focus
on drilling consumables difficult.
MIM undertook the task of generating
information and sharing it with
Secoroc, to release the mutual benefits
of reduced costs for the client and
contract extensions for the supplier.
To foster continuous improvement,
quarterly meetings were implemented
to discuss the provision of service
– prompt reporting of loss, product
training and product development.
Both parties agree on what has and
what hasn’t been done, focusing on
the objectives. As a result, Secoroc is
able to provide the most suitable and
16B
19/L
Current practice in stope design
Match stope outline with grade contour.
Consider existing development horizontal
& vertical (inaccessible).
Design additional development as required
for stope extraction.
Use rock mechanics principles (pillars,
exposure dimensions).
Location & quality of faults & fill masses
(delay exposure).
Extraction options
Simplify stope extraction sequence.
Minimize remote mucking.
Delay exposing faults and fill masses.
Effective ventilation circuits.
Safety considerations & hazard ID.
Design -> Monitor operating
cost-efficient products for MIM operations,
resulting in fewer bits for the
same tonnages. MIM and Secoroc are
now really pushing the idea of reusing
material and focusing on wastage. Bit
resharpening, rod straightening and
rod clearing have been introduced with
the resharpening ratio for development
bits now averaging 1.5 times.
Consumable care is an area where
the jumbo operators can improve the
life of consumables and cost per metre,
and Secoroc is required to take a lead
in education in the use of its products.
The companies are working towards
agreeing on and setting expectations
about scaling standards, and procedures
to reduce damage.
The initial supply and service contract
ran for one year and has since
been extended for three years on a performance-based
rolling contract, with
three monthly performance reviews.