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Mining with Liquids

New minerals research at the South Australian Museum is set to change the face of the mining industry, with Head of Earth Sciences Professor Allan Pring and his team working on the concept of ‘liquid mining’.

“Imagine being able to get copper out of an ore body without having to dig any holes – that’s the holy grail that we are working towards,” says Professor Pring.

The disturbance that mining can cause to the natural environment is one of the most controversial aspects of the industry. The South Australian Museum team is working on a method to inject liquid into underground ore deposits and dissolve the minerals out of the ground, meaning very little natural disturbance at all. They are studying the precise chemical and physical conditions that help form valuable ore deposits, like those at South Australia’s Olympic Dam, 560km north of Adelaide. Around 180,000 tonnes of copper are produced from Olympic Dam each year.

“The processes that form huge ore bodies like Olympic dam, which is approximately 6 km long and 3 km wide, actually operate at the atomic or molecular scale,” says Professor Pring.

That’s why scientists at the South Australian Museum are also able to make copper in our laboratories, using high temperatures and pressure. However, their new approach is much more unique – they’re working to make minerals from water-based solutions.

“If we can form a mineral from an aqueous solution, then we will know the conditions needed for a mineral to become stable. We can then work out the reverse process needed to make the mineral unstable, and move,” says Professor Pring says.

This potential breakthrough would help mining companies extract the prized minerals from the ground. Specially-designed liquids could be injected into an ore deposit and then target a particular mineral, dissolving it out of the ore. The liquid could then be pumped up to the surface where the metal could be easily collected.

The mining industry is not the only sector to benefit from Professor Pring’s research: it could also improve efficiency in the geothermal and oil industries.

“If we can work out the right solution that will dissolve certain minerals, then we will effectively be able to open and close rocks,” Professor Pring says.

Once the right conditions for mineral formation have been identified in the laboratory, then this can be used with knowledge of local geology to better predict the distribution and grade of ores within the landscape. This will lead to better exploration outcomes as well as increasing the efficiency of mining, ore treatment and waste rock management.
Geothermal systems use hot rocks in the earth to heat water and the heat is harnessed to create energy or electricity. Water is pumped through minute cracks in the rocks, often at high pressures. The ability to open and close rocks using liquid solutions would help to increase the capacity and efficiency of geothermal energy systems.

This process would also improve oil extraction rates. At the moment only about 50% of the oil in reservoirs can be extracted. The remaining oil is often trapped within small pores in rocks and cannot be pumped out. If the pores within the rock could be broken open by a tailor-made liquid, then the remaining oil would also become available.

“It’s like a giant jigsaw puzzle. We’re working in one area and we can see how our work will impact on many other areas,” Professor Pring says.

New mineral species are now discovered at a rapid pace, around 50–100 each year, as analytical techniques have improved. Professor Pring’s group describes about six new minerals a year with colleagues, as part of the research within the MM&S group at the Museum.

South Australian Museum