Nuton venture aims to grow Rio Tinto’s copper business, accelerate decarbonization agenda

Nuton technology pilot plant at Rio Tinto’s Bundoora Technical Development Centre in Australia. Image from Rio Tinto.

Arizona Sonoran Copper Company (TSX:ASCU)  has entered into a strategic partnership with Rio Tinto (ASX: RIO) focused on the world’s second biggest miner’s Nuton technologies, that includes participation in a private placement of up to C$35 million ($27.3m). 

On completion of the offering, Rio Tinto is expected to hold 7.2% of the outstanding share capital of the company. Arizona Sonoran Copper’s asset, Cactus, is a brownfield copper mine located on private land in western Pinal County, Arizona.  

Last month, Lion Copper and Gold entered into an option to earn-in agreement with Rio Tinto to advance studies and exploration at Lion CG’s copper assets in Mason Valley, Nevada. Under the agreement, Rio has the option to earn a 65% interest in the assets, comprising 34,494 acres of land.  

At both sites, Rio will evaluate the potential commercial deployment of its Nuton copper heap leaching technologies, which it developed to deliver increased copper recovery from mined ore and access new sources of copper such as low-grade sulphide resources and reprocessing of stockpiles and mineralised waste. 

With very few new copper mines coming online, combined with existing mines getting progressively more challenging in terms of declining grades and depth, the industry is looking at new technology to produce more out of existing operations.  

Rio estimates that more than 100mt of copper is contained in tailings globally. 

The technologies, the company said, have the potential to deliver improved environmental performance through more efficient water usage, lower carbon emissions, and the ability to reclaim mine sites by reprocessing waste. 

According to the company, the Nuton technologies have the potential to economically unlock low-grade sulphide resources, copper bearing waste and tailings, and achieve higher copper recoveries on oxide and transitional material, increasing copper production with a lower corresponding carbon footprint.  

One of the key differentiators, the company said, is the potential to deliver ESG performance, such as more efficient water usage, lower carbon emissions, and the ability to restore and reclaim mine sites by reprocessing mine waste 

“We see Nuton as a venture that’s innovative and really intended to help grow our copper business and accelerate our decarbonization agenda,” Adam Burley, Rio Tinto’s lead of the Nuton venture told  

“We see real opportunity in the Nuton portfolio of technologies to unlock new sources of copper — that may come from lower grade material in existing mines, or potentially material with complex mineralogy at new greenfield projects, or copper in mine waste,” Burley said.  

“In the leaching of oxides we’ve been doing that as an industry for decades, it’s really that primary, chalcopyrite-dominated material that holds the key,” he said. “What we see through Nuton is a step change in the recovery of copper from that chalcopyrite. We expect to deliver copper recoveries in excess of 80% on those chalcopyrite-dominant ores.” 

Burley said the Nuton portfolio is the product of nearly 30 years of in-house research and development, and that the aim is to deliver carbon- neutral copper and that based on its averages, Rio estimates it can deliver 0.4 tonnes of Co2 equivalent for Scope 1 and 2 emissions per tonne of Nuton copper produced, compared to 5.2 tonnes of C02 equivalent as per standard, conventional primary copper production.   

“It’s heads and shoulders above the next best,” Burley said. “We’re really excited to market it at this point and roll the technology out across the industry.”