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Taseko Mines using innovation to increase production and efficiencies

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The Taseko Mines story is indicative of the current environment miners find themselves in – maximise productivity to grow margins at existing operations or invest in innovative new methods of extracting critical metals that come with a reduced footprint.

The Vancouver-based company is pursuing both options at the two main assets on its books – the Gibraltar copper mine in British Columbia, Canada, and its Florence Copper project in Arizona, USA.

Gibraltar, owned 75% by Taseko, initially started up in 1972 as a 36,000 t/d operation. It was shut down in 1998 due to low copper prices before Taseko restarted it in 2004. In the years since, the company has invested over $800 million in the mine, increasing the throughput rate to 85,000 tons per day (77,111 t/d), where it’s been operating at since 2014.

The asset now sits as the second largest open-pit copper mine in Canada – with life of mine average annual production of 130 MIb (59,000 t) of copper and 2.5 MIb of molybdenum.

Stuart McDonald, President and CEO of the company, says the company continues to work on the trade-off of upping throughput – potentially past the nameplate capacity – and improving metallurgical recoveries at the operation.

This became apparent in the latest quarterly results, when Taseko reported an average daily throughput of 89,400 tons/d over the three-month period alongside “higher than normal” mining dilution.

The company believes Gibraltar can improve on both counts – mill throughput and mining dilution.

“We were optimistic coming into the new pit (Gibraltar Pit) that, based on the historical data, we could go above 85,000 tons/d as we got settled in and mined the softer ore,” McDonald told IM. “We still believe there are opportunities to go beyond that level, but, at some point, it becomes an optimisation and trade-off between throughput and recoveries.

“In our business, we’re not interested in maximising mill throughput; we’re interested in maximising copper production.”

On the dilution front, McDonald believes the problem will lessen as the mining moves to deeper benches in the Gibraltar Pit.

“As we go deeper, the ore continuity improves, so we hope the dilution effect will continue to improve too,” he said.

“The dilution rate is still not quite where we want it to be, so it’s a matter of looking at our operating practices carefully and following through a grade reconciliation process from our geological model through to assays from our blast holes, assays into the shovel bucket and all the way through to the mill.”

‘Assays into the shovel bucket’?

McDonald explained: “We do use ShovelSense® technology on two of our shovels, so that helps us assess the grade of the material in the shovel bucket.”

To this point, the company has leveraged most value from this XRF-based technology, developed by MineSense, when deployed on shovels situated in the boundaries between ore and waste. This offers the potential to reclassify material deemed to be ‘waste’ in the block model as ‘ore’ and vice versa, improving the grade of the material going to the mill and reducing processing of waste.

ShovelSense has been successful in carrying out this process with accuracy at other copper mines in British Columbia, including Teck Resources’ Highland Valley Copper operations and Copper Mountain Mining’s namesake operation.

McDonald concluded on this grade reconciliation process: “We just have to make sure we are tracing the material through all of those steps and not losing anything along the way. Gibraltar is a big earthmoving operation, so we must continue to keep the material flowing as well as look at the head grade.”

A different type of recovery

In Arizona at Florence Copper, Taseko has a different proposition on its hands.

Florence is a project that, when fully ramped up, could produce 40,000 t of high-quality copper cathode annually for the US domestic market.

It will do this by using a metal extraction and recovery method rarely seen in the copper space – in-situ recovery (ISR).

The planned ISR facility consists of an array of injection and recovery wells that will be used to inject a weak acid solution (raffinate – 99.5% water, 0.5% acid) into copper oxide ore and recover the copper-laden solution (pregnant leach solution) for processing into pure copper cathode sheets. The mine design is based on the use of five spot well patterns, with each pattern consisting of four extraction wells in a 100 ft (30.5 m) grid plus a central injection well. This mine outline and associated infrastructure comes with a modest capital expenditure figure of $230 million.

The company has been testing the ISR technology at Florence to ensure the recovery process works and the integrity of the wells remains intact.

Since acquiring Florence Copper in November 2014, Taseko has advanced the project through the permitting, construction and operating phase of the Phase 1 Production Test Facility (PTF). The PTF, a $25 million test facility, consists of 24 wells and the SX/EW plant. It commenced operations in December 2018.

Over the course of 18 months, Taseko evaluated the operational data, confirmed project economics and demonstrated the ability to produce high-quality copper cathode with stringent environmental guidelines at the PTF, the company says.

McDonald reflected: “We produced over 1 MIb [of copper] over this timeframe and then switched over from a copper production cycle into testing our ability to rinse the orebody and restore the mining area back to the permitted conditions.

“We’re proving our ability to do the mining and the reclamation, which we think is a critical de-risking step for the project.”

Over an 18-month period, Taseko produced 1 MIb from the ISR test facility at Florence

Taseko says Florence Copper is expected to have the lowest energy and greenhouse gas-intensity (GHG) of any copper producer in North America, with McDonald saying the operation’s carbon footprint will mostly be tied to the electricity consumption required.

“Our base case is to use electricity from the Arizona grid, which has a combination of renewables, nuclear and gas-fired power plants,” he said. “In the longer-term, there are opportunities at Florence to switch to completely 100% renewable sources, with the most likely candidate being solar power.

“At that point, with renewable energy powering our plant, we could be producing a copper product with close to zero carbon associated with it.”

Gibraltar has also been labelled as a “low carbon intensity operation” by Skarn Associates who, in a 2020 report, said the operation ranked in the lowest quartile compared with other copper mines throughout the world when it comes to Scope 1 and 2 emissions.

When it comes to the question of when Florence could start producing, Taseko is able to reflect on recent successful permitting activities.

In December 2020, the company received the Aquifer Protection Permit from the Arizona Department of Environmental Quality, with the only other permit required prior to construction being the Underground Injection Control (UIC) permit from the US Environmental Protection Agency (EPA).

On September 29, the EPA concluded its public comment period on the draft UIC it issued following a virtual public hearing that, according to Taseko, demonstrated strong support for the Florence Copper project among local residents, business organisations, community leaders and state-wide organisations. Taseko says it has reviewed all the submitted comments and is confident they will be fully addressed by the EPA during its review, prior to issuing the final UIC permit.

Future improvements

In tandem with its focus on permitting and construction at Florence, and upping performance at Gibraltar, the company has longer-term aims for its operations.

For instance, the inclusion of more renewables to get Florence’s copper production to carbon-neutral status could allow the company to benefit from an expected uptick in demand for a product with such credentials. If the demand side requirements for copper continue to evolve in the expected manner, it is easy to see Taseko receiving a premium for its low- or no-carbon product over the 20-year mine life.

At Gibraltar, it is also pursuing a copper cathode strategy that could lead to the re-start of its SX-EW plant. In the past, this facility processed leachate from oxide waste dumps at the operation.

“As we get into 2024, we see some additional oxide ore coming out of the Connector Pit, which gives us the opportunity to restart that leach operation and have some additional pounds coming out of the mine,” McDonald said.

Alongside this, the company is thinking about leaching other ore types at Gibraltar.

“There are new technologies coming to the market in terms of providing mines with the opportunity to leach sulphides as well as oxides,” McDonald said. “We’re in the early stages of that work, but we have lots of waste rock at the property and, if there is a potential revenue stream for it, we will look at leveraging that.”

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

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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.”

Sandvik to deliver ‘biggest BEV fleet to date’ for Foran’s McIlvenna Bay

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Foran Mining has selected Sandvik Mining and Rock Solutions to supply a fleet of 20 battery-electric vehicles (BEVs), including trucks, loaders and drills, for its McIlvenna Bay project in Saskatchewan, Canada.

Set to be one of the world’s first carbon-neutral copper development projects, McIlvenna Bay will be powered by clean hydroelectric power and designed to take advantage of Sandvik’s latest technological advances in sustainable mining, the OEM says.

Sandvik’s biggest BEV fleet to date will include seven Sandvik 18-t-payload LH518B loaders (pictured dumping into a TH550B), six Sandvik 50-t-payload TH550B trucks, four Sandvik DD422iE jumbo drill rigs, two Sandvik DL422iE longhole drills and one Sandvik DS412iE mechanical bolter. Delivery of the equipment is scheduled to begin next year and continue into 2025, Sandvik says.

Sandvik will also provide on-site service support and Battery as a Service by Sandvik at the underground copper-zinc mining project located in east-central Saskatchewan.

Jakob Rutqvist, VP Strategy and Commercial for Sandvik Mining and Rock Solutions’ Battery and Hybrid Electric Vehicles (BHEV) Business Unit, said: “This record contract is the culmination of a year-long collaborative effort between Foran Mining and Sandvik and demonstrates a shared vision that electrification will drive the future of sustainable mining. BEVs have enormous potential to reduce a mining operation’s carbon footprint, and Canada continues to be the epicentre for mining electrification and a blueprint for what to expect in other major mining regions very soon.”

Copper and zinc are critical metals for the transition to a low-carbon future as essential elements of electrical grids, solar panels, wind turbines and batteries. The McIlvenna Bay project intends to supply those minerals in a way that will not only be carbon neutral but ultimately have a net positive impact on the climate, according to Sandvik.

Dave Bernier, Chief Operating Officer of Foran Mining, said: “This is a very exciting period for Foran as we continue to execute on our initiatives to permit, construct and operate McIlvenna Bay. Sandvik is a global leader in industrial battery technology and we look forward to working together on our project. Utilising battery-electric equipment with semi- and fully-autonomous capabilities can help us achieve carbon neutral targets and provide a safer working environment, which is part of our Net Positive Business strategy as we look to deliver critical metals essential for global decarbonisation in a responsible and socially-empowering way.”

Foran Mining conducted a thorough analysis during its 2020 prefeasibility study to determine the investment case for BEVs compared with diesel. The company determined that BEVs would deliver better financial results at McIlvenna Bay when considering the savings generated through lower ventilation capital and operating costs.

That report, authored by AGP Mining Consultants Inc, envisaged the potential use of 7 Sandvik LH517i LHDs and 11 Artisan Vehicles (Sandvik) Z50 battery electric trucks for a 3,600 t/d of polymetallic ore operation.

Stefan Widing, President and CEO of Sandvik, said: “I am very pleased that Foran Mining has chosen Sandvik to deliver our leading battery-electric solutions for the pioneering McIlvenna Bay project. We see very strong momentum for our mining electrification offering, which offers great potential in driving more sustainable mining, helping customers to boost productivity, reduce greenhouse gas emissions and improve workers’ health.”

A dedicated on-site project team will be jointly working with the mine’s operations team to ensure the products and services in the delivery scope support the alliance on Foran’s journey towards more productive, efficient and sustainable mining, Sandvik said.

“Battery as a Service by Sandvik will enable McIlvenna Bay to get the most out of its battery-electric equipment by relying on unrivaled expertise to manage the capacity and health of batteries and chargers throughout their long lives,” it added.