A futuristic mining method for a mineral of the future

As an essential component for technologies such as electric vehicles and wind power turbines, copper is a critical element of the future. Salomae Haselgrove finds out how methods for mining copper are changing to match its green potential.

Two years ago, copper miner OZ Minerals turned heads when it released data from the Mt Woods project in South Australia on the internet for anyone in the world to access.

This bold move is one that OZ head of exploration and growth Richard Holmes stands by, with him saying at the 2020 International Mining and Resources Conference (IMARC) that sharing knowledge and collaboration is the way forward to make new discoveries in the mining industry.

“The collaborative aspect is really what is going to push exploration in Australia and globally. It’s much faster than the old traditional ways,” Holmes explains at the event.

“I absolutely encourage it. It’s something I’m very passionate about. It takes time for people to grasp getting their executive management and board comfortable with releasing all of their data to the internet, it’s been a very interesting journey.”

However, Holmes believes the risk is worth the reward and the way forward to making more new copper discoveries.

New copper discoveries are essential to modern development, with the mineral being used in vital infrastructure, including electric vehicles, wind turbines, electrical wiring and motors and infrastructure.

Junior explorer Thor Mining is taking its own approach in this way. Rather than sharing data of completed exploration, Thor is changing the way it mines the copper itself.

At its South Australian projects in Kapunda in the Barossa Valley and Alford on the Yorke Peninsula, Thor is experimenting with in-situ copper recovery, which has a lesser impact on the environment and allows for cheap mineral extraction.

This is particularly important for the regions in which Thor operates, with the Barossa Valley and Yorke Peninsula being key tourism and farming regions, meaning there can be some community fear about the impact mining has on the land needed for these primary industries.

As Thor executive chairman Mick Billing explains, in-situ allows for minerals to be dissolved out of the ground while leaving the surface untouched, allowing for reuse of the land quicker than in a conventional mining operation.

“What we do in in-situ recovery is we don’t sterilise the land,” Billing tells Australian Mining.

“It is a very elegant solution to dissolve the copper but leave the surface effectively untouched, provided you have the sorts of ground conditions that allow you to do it.

“Within a couple of years or less of completing extraction of copper, the farmer can continue to farm that land as if the miners have never been there.

“It’s an environmentally sensitive and extraordinarily cheap way of mining.”

Dissolving the minerals means that mining operations move far less dirt and do not need advanced drilling, blasting and crushing equipment, significantly cutting the costs of establishing a mining operation.

In-situ recovery is a rarer method than regular copper mining, as the minerals must be in soluble form and located below the water table, while the ground must be permeable to allow fluid to pass through to dissolve the metal from the rocks before extraction.

While South Australia’s largest copper mine, Olympic Dam, may not be appropriate for this method, Thor Mining’s Kapunda and Alford projects look promising for in-situ recovery.

“On Yorke Peninsula, we believe in-situ recovery is going to work, based on the test work we have done,” Billing says.

“The water table over there is quite saline, it is of no use to the farming community because it’s too salty, which means we must ensure it doesn’t splash across to the nearby farmland.

“We have established the proof of concept at our Kapunda site. We know we can dissolve the copper in the ground by putting fluid into one bore hole and pumping out fluid for another.”

Pitching this method of mining to the Kapunda and Alford communities, Thor Mining has been able to demonstrate its commitment to operating alongside the local communities and their other key industries.

“Our team, particularly at Kapunda has been engaging with the local community for the last couple of years,” Billing says.

“In general, the community are supportive of the in-situ recovery process and what is being planned. Kapunda has a mining history and heritage it is quite proud of and if it can continue to have a life of producing valuable copper without negatively impacting the town, the community will be very supportive.”

Thor has a 25 per cent equity interest in EnviroCopper, which prides itself on creating “the invisible mine” through its team of geologists exploring the potential of in-situ recovery.

EnviroCopper has been working side by side with the South Australian Government’s Department for Energy and Mines to not only research the in-situ mining method, but to also establish a regulatory framework around it and use it to mine in historic towns like Kapunda and Alford.

Company managing director and senior geologist Leon Faulkner has previously explored this method in the uranium field at the Honeymoon mine in South Australia.

With EnviroCopper, Faulkner has also worked alongside the University of Adelaide on several research projects about which lixiviants liquid metals are the most appropriate for dissolving the copper without interrupting the natural groundwater.

“The key findings are that there are a whole range of lixiviant chemicals that can dissolve the metals in a range of PH solutions,” Faulkner explains.

“The traditional approach in uranium would be to go for a PH of roughly neutral (seven), put the acid in there then drop the PH to two or three to dissolve and process the uranium, while leaving the groundwater natural.

“For copper, we have found that the lixiviant systems of two to three range up to the neutral range of seven to eight works in an alkaline PH range.

“This means rather than having to change the groundwater solutions we can simply choose the lixiviant to suit them, so we are working with the environment, not against it.”

EnviroCopper is also using in-situ recovery for resource estimation, giving an accurate estimate of the copper to be recovered and measured in real-time, narrowing down resource estimation to create more definitive feasibility studies.

With this game-changing method allowing for less impactful methods of mining a crucial resource for future industries, both Thor and EnviroCopper are ramping up their in-situ projects in 2021 and beyond.

“If we can use in-situ recovery to show local communities how the environmental parameters compare to how we said they were going to go, it should go a long way in developing an in-situ recovery operation in South Australia,” Faulkner concludes.

This article also appears in the February issue of Australian Mining.

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