Tag Archives: Nuton

Rio Tinto’s Nuton ready to leverage its leaching R&D legacy

More than a few companies and technology providers claim to have solved the primary copper sulphide leaching conundrum, but only one has close to 30 years of R&D and the Rio Tinto name behind it.

Rio, through its Nuton venture, is the latest to table a solution to treat primary copper sulphides such as chalcopyrite, having introduced the company to the sector earlier this year in an attempt at growing the miner’s copper business.

At its centre is a portfolio of proprietary copper leach related technologies and capability that, Nuton says, offer the potential to economically unlock known low-grade copper sulphide resources, copper bearing waste and tailings, and achieve higher copper recoveries on oxide and transitional material. This allows for a significantly increased copper production outcome, according to the company.

One of the key differentiators of Nuton is the potential to deliver leading environmental performance, including more efficient water usage, lower carbon emissions and the ability to reclaim mine sites by reprocessing mine waste, it claims.

Column test work at Rio Tinto’s R&D centre in Bundoora, Melbourne

Adam Burley, Rio Tinto’s Nuton venture lead, said at the core of Nuton is an elevated temperature bioleaching process that can, in the right thermochemical conditions, deliver “peak” copper recovery from primary sulphides such as chalcopyrite.

“Taking advantage of naturally-occurring processes, we have nurtured a culture of microorganisms that establish and thrive in those optimised conditions,” he told IM. “The elevated temperatures are generated by the work of the bacteria; under the base case, we don’t need to heat the heap from external sources, which can often be financially and environmentally costly.”

This leaching core is enhanced by a range of “additives” and expertise that can, for example, deal with high precipitation and cold weather climates.

Having assembled and extensively tested this portfolio, Nuton and Burley are confident enough to state expectations of delivering greater than 80% copper recoveries from chalcopyrite ore with its process.

“This is, from our understanding, some way above the next best leaching technologies available,” Burley said.

The testing behind such numbers is extensive, dating back to 1994 when the company carried out its pilot heap leach operation and developed its initial predictive modelling capabilities at the Kennecott copper mine in Utah, USA.

“Since that time, we’ve conducted hundreds of column tests across tens of orebodies,” Burley said. “We have run columns at a range of scales – a metre high to 10 metres high – and a range of diameters – from tens of centimetres to 5-metre diameter cribs. Some of those range from tens of kilograms to 300 tonnes – large scale with a lot of instrumentation.”

Combining this body of work with a 70,000 t leaching trial the company carried out at Kennecott from 2012 to 2014, Nuton has been able to calibrate its computational fluid dynamic models to accurately predict a range of inputs and outputs for leaching suitability.

“We are left in a position today where we have a high degree of confidence in being able to evaluate the suitability of different ore types and Nuton’s leach response fairly quickly,” Burley said.

This has led to the company going out to market, partnering with companies that own deposits that pass the Nuton thresholds.

The company has signed deals with Lion Copper and Gold Corp, and Arizona Sonoran Copper Company to test out the technology on Lion’s copper assets in Mason Valley, Nevada, and Arizona Sonoran’s Cactus Mine and Parks/Salyer projects, in Arizona.

It has also more recently agreed a pact with McEwen Copper on the Los Azules project in Argentina.

These assets, agreements and potential leaching applications are all different – covering former operating mines and greenfield assets; earn-ins, exclusivity periods and equity stakes; and oxides and sulphides.

“We recognise that due to the high variability of copper deposits and mine waste that one size doesn’t fit all,” Burley said. “A single technology solution is unlikely to perform well at every site.

“Our approach is to work with our partners to understand site-specific characteristics, such as the mineralogy of the available ore and waste, designing a tailored approach by selecting the most applicable technology configuration from within the Nuton portfolio.”

And, according to Burley, these current and future agreements could see Nuton operate the equipment and plant associated with the Nuton process.

“In many cases, we envisage supporting our partners with an end-to-end process, including engineering, build out and operating the gear,” he said.

The test site at Kennecott being prepared and lined ready for the rock to be leached

While the sulphide copper recovery numbers are likely to take the headlines, Burley was able to point out several key differentiators from other leaching solutions targeting minerals such as chalcopyrite.

“Those recovery numbers are a step change, as opposed to an incremental improvement,” he said. “That gives us a lot more optionality in terms of the cutoff grade of the material we can process economically.”

And, with that higher resource utilisation, comes less waste and an overall higher process efficiency, meaning, under certain conditions, Nuton can compete with a pre-existing processing route such as a concentrator, Burley says.

“In some cases, in a greenfield setting, we could see a better economic and environmental outcome than a concentrator, particularly given no tailings or smelting is required, and you could have a finished product produced in country.”

He continued: “Our focus on ESG and our ability to process waste due to that low cutoff grade is one of the key differentiators that opens a whole set of use cases in the legacy mine domain too. Being able to restore and reclaim mine sites by reprocessing waste is very attractive.”

The eventual aim, according to Burley, is to deliver carbon-neutral copper from the Nuton process, yet Rio estimates it can already deliver 0.4 tonnes of CO2 equivalent for Scope 1 and 2 emissions per tonne of Nuton copper produced, compared with a global average of 5.2 tonnes of CO2 equivalent as per standard, conventional primary copper production.

Away from the technical elements, the “partnership” business model Nuton uses also stands out.

Nuton testing up and running at Kennecott (from previously mentioned trials)

“The approach is to work with our partners and assess the value case at specific sites, agreeing a commercial framework that works for everyone,” Burley said. “We are quite open minded as to what that might look like – it could be ownership and equity participation to royalty and licensing type arrangements.

“So, there is the financial strength Rio brings, as well as the deep technical expertise.”

These elements are clearly beneficial to any of Rio’s fellow mining companies that have projects with copper sulphides or those that will be transitioning to sulphide processing in the future, yet a lot of the progress made with these technologies was tied to the development of Rio’s own project, La Granja.

“In that case, part of the resource contains high arsenic and arsenic-related mineralogy,” Burley said of La Granja. “That was the trigger really for a concerted effort to look at an alternative to a concentrate and processing route. We made quite a number of Nuton breakthroughs in our study of that deposit.”

La Granja has been in Rio’s portfolio since winning the right to develop it in 2005, but is not currently in the development pipeline.

Asked if other assets within the company’s portfolio are potential Nuton candidates, Burley answered: “The potential exists to deploy Nuton within the Rio Tinto copper portfolio. We are currently evaluating a number of internal deployment options across our assets and joint ventures, but we also recognise the full value potential of Nuton – environmental and social, as well as financial – lies outside of the Rio Tinto portfolio.

“To capture the full size of prize that Nuton offers, we need to go out to market, which is what we have been doing pretty aggressively throughout the year and will continue to do going forward.”

Rio Tinto’s Nuton to test leaching tech at McEwen Copper’s Los Azules project

McEwen Copper’s Los Azules project in Argentina looks like becoming the latest potential leaching asset put under the Nuton® Technologies microscope after the signing of a collaboration agreement between McEwen Copper and Nuton.

The agreement, tied to an oversubscribed $81.85 million offering of McEwen Copper shares, will see Nuton, a Rio Tinto Venture, test its technology for compatibility with Los Azules copper mineralisation.

Nuton, for its part, also contributed $25 million into the funds raised by McEwen Copper.

Rio Tinto’s copper leaching technology venture has been in the headlines of late, signing deals with, among other companies, Arizona Sonoran Copper Company Inc and Lion Copper and Gold, to test out its solutions.

Nuton is aimed at growing Rio Tinto’s copper business. At its core is a portfolio of proprietary copper leach related technologies and capability – a product of almost 30 years of research and development.

Rio says the Nuton technologies offer the potential to economically unlock known low-grade copper sulphide resources, copper bearing waste and tailings, and achieve higher copper recoveries on oxide and transitional material, allowing for a significantly increased copper production outcome, according to Rio. One of the key differentiators of Nuton is the potential to deliver leading environmental performance, including more efficient water usage, lower carbon emissions, and the ability to reclaim mine sites by reprocessing mine waste, Rio claims.

McEwen Copper and Nuton will jointly undertake copper leach testing using Nuton Technologies with samples from Los Azules. McEwen Copper has agreed to grant exclusivity to Nuton for one year in the area of novel, patented or trade secret leaching technology, while it will continue its independent test work and studies using conventional leach technologies.

McEwen Copper Chief Executive, Rob McEwen, said: “We recognise the potential opportunity of using Nuton Technologies to produce copper in greater amounts, more rapidly, and with less impact on the environment and water resources. I trust that our relationship with Nuton and Rio Tinto will accelerate the process of realising the enormous potential of Los Azules.”

Rio Tinto Chief Executive Copper, Bold Baatar said: “This agreement will allow us to evaluate the potential to commercially deploy Rio Tinto’s innovative Nuton Technologies for copper leaching in McEwen Copper’s planned development of Los Azules. Our Nuton Technologies have the capacity to unlock increased copper production for Rio Tinto and our partners, with a low carbon footprint and leading environmental performance.”

The next milestones at Los Azules are the upcoming drilling season from October 2022 to June 2023, the completion of an updated preliminary economic assessment early in the March quarter, and the planned initial public offering of McEwen Copper in the first half of 2023.

Los Azules’ current copper resources are estimated at 10.2 billion pounds (4.6 Mt) at a grade of 0.48% Cu (indicated category) and an additional 19.3 billion pounds (8.8 Mt) at a grade of 0.33% Cu (inferred category).

Rio Tinto signs pact to test Nuton copper heap-leach tech on Cactus primary sulphides

US-based copper developer and near-term producer, Arizona Sonoran Copper Company Inc, has entered into a one-year exclusivity period with Nuton™, a Rio Tinto Venture that, at its core, is a portfolio of proprietary copper leach related technologies and capability.

The exclusivity was triggered by successfully modelling the Cactus and Parks/Salyer ore samples and achieving the previously contemplated indicative metallurgical recoveries of at least 72% (copper recovery to cathode), which included chalcopyrite, under an investor rights agreement, Arizona Sonoran said.

Nuton will continue to test the application of its copper heap-leach related technology to the primary sulphide component of the Cactus Mine and Parks/Salyer Projects, in Arizona, through column leaching and scoping out capital and operating costs and design parameters, it added.

The sulphide potential is not included in the 2021 Cactus preliminary economic assessment, which contemplated a simple heap leach and SX-EW operation over an 18-year mine life, producing an average of 28,000 t/y of LME Grade A copper cathode.

Within the current Cactus project resource base is a primary sulphide mineral resource of 77.9 million short tons (70.7 Mt) at 0.35% CuT (indicated) and 111.2 million short tons at 0.35% CuT (inferred).

George Ogilvie, Arizona Sonoran President and CEO, said: “The Nuton preliminary work results indicate optionality for unlocking the substantial primary resource at Cactus, which is currently stranded at the bottom of the pit. Although we are in the early stages of testing chalcopyrite recoverability on an economic basis, we are encouraged by the initial results and the significant potential to continue building scale at Cactus and potentially at Parks/Salyer in the longer term.”

The preliminary metallurgical testing program covered ore sample selection, preparation and mineralogical characterisation to produce CFD modelling results providing early-stage indicative recoveries in respect of various ore types and specifically the chalcopyrite ore at Cactus. Further test work underway covers test column leaching and scoping out capital and operating costs and design parameters, the company said.

Nuton is an innovative new venture that aims to help grow Rio Tinto’s copper business. At its core is a portfolio of proprietary copper leach related technologies and capability – a product of almost 30 years of research and development. The Nuton technologies offer the potential to economically unlock known low-grade copper sulphide resources, copper bearing waste and tailings, and achieve higher copper recoveries on oxide and transitional material, allowing for a significantly increased copper production outcome, according to Rio. One of the key differentiators of Nuton is the potential to deliver leading environmental performance, including more efficient water usage, lower carbon emissions, and the ability to reclaim mine sites by reprocessing mine waste, it claims.