The
Ranger uranium mine is surrounded by Kakadu National
Park
, in the Northern Territory
of Australia, 230 km
east of Darwin
. The orebody was discovered in 1969, and the
mine commenced operation in 1980, reaching full production of
uranium oxide in 1981. It is operated
by
Energy Resources of
Australia, a 68% subsidiary of
Rio
Tinto Group.
Uranium mined at Ranger is sold for use in
nuclear power stations in Japan, South
Korea, UK, France, Germany, Spain, Sweden and the United
States.
The original orebody was completely mined out by the end of 1995,
although some ore remains stockpiled. A second orebody ("Ranger 3")
began mining in 1997. Both have been
open-pit mines.
Discovery and operation of the mine
Ranger 3 open pit, Northern Territory,
Australia: Uranium mineralised Cahill-Formation as visible in the
pit is unconformably overlain by Kombolgie sandstone forming the
mountains in the background
The orebody was discovered in 1969, and the mine commenced
operation in 1980, reaching full production of
uranium oxide in 1981.
Owing to the environmental sensitivity of the site, a special
statutory authority, the
Supervising Scientist, was created to
provide oversight of the operation and conduct environmental
research in the region.
The Ranger Uranium Mine covers two of a line of uranium orebodies
that extend from near Nourlangie Rock in Kakadu north-eastwards to
Koongarra, underneath Mount Brockman, then northwards through the
Ranger One line of orebodies (in order Number 2, Number 1, and
Number 3), then via Hades Flat, where there is uranium
mineralisation, to Jabiluka where the line turns westward through
the Barote and Ranger 4 orebodies. The mine covers No 1 Orebody and
No 3 Orebody. No 2 orebody was excluded from the mining lease at
the request of the traditional owners and included in Kakadu
National Park. From Ranger 4 the line again turns northwards and
then swings westward round an Archaean basement dome before turning
south towards Nourlangie Rock again. Uranium mineralisation is
known at several other places along this line but has never been
explored in detail because of the creation of Kakadu. The name
'Ranger' for the series of discoveries made by Geopeko Limited, the
exploration arm of the Australian mining company Peko-Wallsend
Limited, in the period 1969 to 1972, was thought up by Judy Ryan,
the wife of the geologist in charge of the program. Koongarra and
Jabiluka were retained by the companies that found them: Noranda
Australia and Pancontinental Mining respectively, although since
sold to other parties. The other discoveries are enclosed in the
National Park, locking up an energy source that is estimated to be
greater than the oil reserves of Saudi Arabia. (12)
Ore processing
Ore is ground, then leached with
sulfuric
acid. Uranium is removed using
kerosene
with
amine then stripped with
ammonium sulfate solution and gaseous
ammonia.
Ammonium diuranate is precipitated by
increased
pH and converted to uranium oxide
(U
3O
8) in a furnace.
In early 2006, ERA announced an expansion to the ore processing
plant which will allow production to extend into lower-grade
material and in November 2006 the company announced plans to invest
in a
laterite processing plant, which will
allow it to process ore with a high clay content that has been
stockpiled since the mine began operating. This ore had been
already included in stated reserves. The laterite processing plant
will contribute 400 tonnes of uranium oxide per year from 2008
until 2014. .
Environmental issues
The main long-term environmental impact of uranium mining is that
posed by the large volumes of tailings, mining waste in the form of
particularised sand, which remain on the minesite. Guidelines from
the International Atomic Energy Agency describe the project area as
particularly unsuitable for tailings storage. The original pit is
now being used to store tailings.
Due to inadequate estimation of annual rainfall in the design
phase,
the mine has continued to suffer routine seasonal failure of the
water management systems.
A mine closure model has been developed by the company and is
provided for in the balance sheet to the value of over
AU$180 million. However opponents warn
that this may be as little as one fifth of the final cost of
rehabilitation.
The rehabilitation plan has not been made public, and
environmentalists warn that plans for further expansion
will further widen the gap between needs and means for remediation
of the mine site.
Safety breaches and controversy
Environment Australia (an
agency of the
Government of
Australia) have documented over 200 environmental incidents
since 1979.
In May 2005, the company was convicted for breaching environmental
guidelines - the first such prosecution of a mining company in the
Northern Territory, relating to accidental radiological exposure to
ERA employees. Radiologically contaminated process water had
contaminated the drinking water supply and some workers drank and
washed in the contaminated water. The maximum radiation exposure of
workers was likely to have been much less than the regulatory
limit, and no harmful long-term health effects are likely.
Other incidents involving decontamination of vehicles have been
identified.
When the work-for-welfare mechanic in
Jabiru
opened the engine bay, he was unaware of the nature
of the mud and dirt which fell on the floor. The court heard
that in the following weeks, after he had swept the material
outside his shed, his children played and built sandcastles in mud
contaminated with uranium.
Another significant controversy over Ranger's environmental impact
is the public legal confrontation over releases into Magela Creek
in the 1995 wet season. More recently, the ARRAC report from 2002
details a major leak of about 2 megalitres of potentially polluted
water, over a number of months.In 2007, water breached a retention
pond, overflowing back into the pit. The original authorisation
required that this water be contained at all times. In 2006, water
management systems were knocked into disarray by
Cyclone Monica.
See also
References
- Current Practices for the Management of Uranium Mill Tailings.
Technical Report Series No. 335, IAEA, Vienna 1992
- John Carroll v Energy Resources of Australia [2005] NTMC
067
12 IAEA, 1980. URANIUM IN THE PINE CREEK GEOSYNCLINE (Eds J
Ferguson and A B Goleby). Proceedings of the international
symposium on the Pine Creek Geosyncline, Int. Atomic Energy Agency,
Sydney, Australia, 4-8 June, 1979.
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