Mining_Methods_UnderGround_Mining - Mining and Blasting

geology
The Olympic Dam mineral deposit
consists of a large body of fractured,
brecciated and hydrothermally altered
granite, a variety of hematite-bearing
breccias and minor tuffs and sediments.
The breccia lies under 300-350 m of
barren flat-lying sediments comprising
limestone overlying quartzite, sandstone
and shale. The deposit contains semidiscrete
concentrations of iron, copper,
uranium, gold, silver, barium, fluorine
and rare earth elements. These are scattered
throughout an area 7 km-long and
4 km-wide, and having a depth of over
1,000 m. There are two main types of
mineralization: a copper-uranium ore
with minor gold and silver within numerous
ore zones, making up most of
the resource; and a gold ore type which
occurs in a very restricted locality.
There is distinct zonation evident
throughout the deposit, ranging from
iron sulphide (pyrite) at depth and
towards the outer edges of the deposit,
through to copper-iron sulphides and
increasingly copper-rich sulphides to-
wards the central and upper parts of the
deposit. The zonation can continue with
rare native copper through to goldenriched
zones, and finally into silicified
lithologies. Uranium occurs in
association with all copper mineralization.
The predominant uranium mineral
is uraninite (pitchblende), but coffinite
and brannerite occur to a lesser extent.
Virgin rock stress conditions are
comparable in magnitude with most
Australian mines, with the principal
stress horizontal and approximately 2.5
times greater than the vertical stress,
due chiefly to the weight of overlying
rock.
With few exceptions related to weaker
areas, the workings are generally dry.
In-situ rock temperatures range from 30
to 45 degrees C.
Mine programme
The Olympic Dam mine comprises under-
ground workings, a minerals processing
wOOMera, SOuTH auSTralia
Sublevel stoping at Olympic
dam
rapid expansion
Since discovery of the massive
Olympic Dam orebody in 1975,
and the establishment of the mine
in 1988, the complex has been
through a series of rapid expansion
programmes. Owned and op-
erated by BHP Billiton, it is the largest
single underground mine in
Australia, with a production rate of
30,000 t of ore per day to produce
around 185,000 t of copper product
annually and significant quantities
of uranium, gold and silver. Total
mineral resource underground is
3,810 million t grading 1.1% copper
and 0.4 kg/t uranium oxide. The
mine’s staged expansion has been
run in parallel with a philosophy of
continuous improvement of mining
methods. They employ a fleet
of Atlas Copco Simba rigs for down-
hole production drilling within a
carefully planned and controlled
sublevel stoping method of production.
Perth
Darwin
Western
Australia
Northern
Teritory
Victoria
Melbourne
Tasmania
Queensland
Brisbane
New South
Wales
Sydney
Canberra
plant, and associated infrastructure with-
in a mining lease area of 29,000ha.
Situated 80 km north of Woomera, and
560 km north-north-west of the South
Australia state capital of Adelaide, the
mine has sufficient estimated reserves
for a possible life of 70 years within cur-
rent rates of production, although the
actual mine plan is in place for only 20
years at present. The mine has its own
purpose-built town, Roxby Downs, located
16 km away. There are around 980
employees, of which 490 work in mining,
and there are also 400 contractors
on site.
Access to the mine is through a 4 km
long surface decline and three shafts:
the Whenan shaft, which was the original
exploration access, converted for
hoisting; the Robinson shaft, sunk in
1995; and the new Sir Lindsay Clark
shaft.
The last completed expansion stage
results from a feasibility study carried
out in 1996 that recommended an
expansion of ore output from 3 million
t/year to 9 million t/year. The facilities
for this expansion were completed in
underground mining methods 109
Hobart
Olympic Dam location in South Australia.
South Australia
Coober
Pedy
OLYMPIC DAM
Woomera
Lake Eyre
North
Lake Eyre
South
Lake
Torrens
Port
Augusta
Adelaide