As the Australian uranium industry continues to grow, South
Australia finds itself at the forefront of that growth.
The State is already home to two of Australia’s three existing uranium mines in BHP Billiton’s Olympic Dam and Heathgate Resources’ Beverley mine.
In addition, July this year saw Federal Environment Minister Peter Garret approve the development of the FourMile uranium mine approximately 550 kilometres north of Adelaide, while construction at the Honeymoon mine 600 km north-east of Adelaide began in April.
In the case of the existing Beverley mine and the upcoming Honeymoon and FourMile operations, all three uranium deposits are housed underground in sandstone deposits, which means that each employs, or will employ, the method of uranium extraction known as in-situ recovery.
In-situ recovery is used when the ore body exists in a sandstone aquifer and is saturated with ground water. The process involves removing the uranium via wells which are drilled into the ore body.
The overall procedure of in-situ recovery is a far less intensive practice than either underground or open-cut mining, both in terms of labour and equipment.
According to Heathgate Resources vice-president operations Ric Phillips, this is a significant advantage of the
“With open-cut uranium mining you have a larger footprint because you have a huge hole in the ground,” he told Australian Mining.
“You also have to excavate the ore using heavy equipment.”
The in-situ recovery method that will ultimately be used at three of the four uranium mines in South Australia eliminates the need for larger operations and helps to minimise the environmental footprint of the mining process.
“The geology in this area of South Australia is right for these sandstone
hosted uranium deposits that are amenable to in-situ recovery,” Phillips said.
“At a hard rock deposit like Olympic Dam you have to dig out the ore either through open-cut or underground, as they are doing at the moment.”
In-situ recovery leaves the ore under the ground for whole of the mining process, Phillips said.
“The process involves drilling water wells and putting screens down those wells in the ore body,” he said.
“You then circulate the ground water through the ore body from what are called injection wells to extraction wells.
“The uranium containing ground water is then pumped to the surface.”
While this type of extraction represents a reasonably straight forward removal process, according to Phillips it is not as simple as it sounds.
The ore must be treated with either an acid or alkali depending on the geological characteristics of the orebody.
“We use a small amount of sulfuric acid and some hydrogen peroxide, which dissolves the uranium coating on the sand grains, and the water then carries that uranium to the surface,” Phillips said.
According to Heathgate president David Williams, by not having to actually go underground to retrieve the uranium, in-situ recovery places far less stress on the surrounding area.
“There is less of an impact on the environment in that you do not end up with a big hole in the ground and a hill of overburden,” he told Australian Mining.
In-situ recovery also eliminates the need to process the ore once it is brought to the surface, rendering much of the larger surface operations unnecessary.
“There is no heavy equipment such as trucks and shovels,” Phillips said.
“There are also no conveyors, no mills and no crushers.”
Ore is moved on the surface through the use of plastic pipes that can later be removed.
“A site might look a bit ugly on the surface, but we don’t even dig trenches to bury pipes, we just lay them on the ground,” Williams said.
“They are plastic pipes and once you have finished you can simply pick them up and walk away.”
Heathgate Resources will play an important role in the development of South Australia’s newest in-situ mine as it moves towards operation.
The FourMile uranium deposit is located adjacent the existing Beverley operation and Heathgate will act as mine manager on behalf of the Quasar—Alliance Joint Venture responsible for the mine.
“When the FourMile project gets up and running it is intended that Heathgate will be the operator and part of the process would be through the Beverley facility,” Williams said.
The two projects will be linked in their operations and methods.
“You could essentially call those operations one in the same project,” he said.
• Heathgate Resources
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