Tag Archives: heap leaching

BASF and hydroGEOPHYSICS to pair solutions to optimise copper leach extraction

Global chemical company BASF and hydroGEOPHYSICS Inc (HGI) have announced an exclusive partnership aimed at combining expertise in mineral processing, hydrometallurgy and deep well injection.

The collaboration aims to optimise copper extraction in the mining industry by using HGI’s geophysical techniques to identify areas within the heap that currently offer poor recovery and will involve the design and implementation of a deep well injection program, incorporating BASF’s LixTRA leach aid to facilitate a significant uplift in copper extraction.

HGI employs state-of-the-art geophysical technologies to characterise the structural components of heap leach pads, enabling the design, operation and monitoring of targeted lixiviant injection wells, the companies explain. By adding BASF’s LixTRA leach aid, greater ore-lixiviant contact is made, which ultimately leads to higher copper dissolution and increased metal recovery. Initial results from a customer’s site have demonstrated a 20% increase in copper recovery during the trial period, prompting further testing on a larger scale to quantify the benefits, they added.

Caren Hoffman, Vice President Mining Solutions at BASF, said: “Technological advancements are essential if the industry is to meet the projected copper demand going forward. Using HGI’s expertise to identify areas of poor heap leach performance and then targeting these areas through deep well technology and BASF’s LixTRA reagent is a great example of how partnerships can drive sustainable process improvements in the mining industry.”

Brian Cubbage, Executive Vice President, Operations at HGI, added: “Enhancing copper recovery is a sustainable and safe manner is the main focus for most of the mines HGI works with. Leveraging HGI’s expertise in locating and enhancing copper recovery in underperforming areas in heap leach pads, with applying BASF’s LixTRA reagent through our injection programs, has provided a significant boost in the efficiency of copper recovery.”

Terrafame leveraging Kelluu hydrogen-powered airship mine monitoring solution

Terrafame, a responsible battery chemicals producer for electric vehicles, has selected Finland-based airship development company Kelluu to provide accurate and geo-referenced terrain data for continuous monitoring of its 60 sq.km industrial site.

The aerial monitoring has been done mainly using satellites or helicopters, battery-powered drones, or land-based surveys.

Kelluu develops long-distance, self-flying and hydrogen-powered airship concepts mounted with several spectral cameras, sensors and scanners that can gather real-time data on terrain, vegetation and infrastructure. It then processes the data to create an accurate 3D digital twin of the environment, enabling Terrafame in this instance to monitor and forecast dynamic changes at the industrial site and optimise its infrastructure maintenance and production processes, and further strengthen the environmental safety of the site, Kelluu says.

Aki Ullgren, Senior Geotechnical Engineer at Terrafame, said: “The combination of high-resolution RGB, multispectral and Flir images, combined with the same 3D mesh, is a fascinating tool, especially in heap leaching and open-pit slope stability modelling. We’re happy to welcome Kelluu to the group of monitoring services we use to promote safety and efficiency at our Terrafame site.”

Kelluu’s airships are highly efficient, emitting 99.5% less CO2 emissions than traditional aerial monitoring, and frequently cover mission times of over 12 hours, the company claims. The airships are effectively operational in sub-zero temperatures.

Kelluu says its facility in Finland is the only airship factory and product development laboratory in northern Europe.

Janne Hietala, CEO of Kelluu, said: “It is truly mesmerising to see the Kelluu’s airships in the air at Terrafame. We felt a strong connection with Terrafame’s commitment to positively impacting the world by reducing emissions of electromobility. What Terrafame does for mobility, we do it for aviation. Together, we provide increased safety using Kelluu’s breakthrough intelligent airship technology.”

Terrafame has one of the world’s largest production lines for chemicals used in electric car batteries on its industrial site in Finland. The plant can produce nickel sulphate for around 1 million electric cars per year, it claims. The carbon footprint of the nickel sulphate produced by Terrafame is among the smallest in the industry.

As Terraframe produces hydrogen onsite and the airships are powered by hydrogen, Kelluu has built a ground base for its airships on Terrafame’s industrial site. Kelluu will autonomously transfer its airship from its current base in Joensuu, Finland, to Terrafame’s base in Sotkamo.

In addition to Kelluu, Terrafame has multiple other partners helping to monitor its site and develop its operations and occupational and environmental safety.

Freeport furthers its leading copper leaching excellence

Among the new applications, technologies and data analytics Freeport-McMoRan is advancing as part of a plan to improve copper recovery from its leach processes in North and South America is Jetti Resources’ patented catalytic technology, the company has confirmed to IM.

In its December quarter and 2022 annual results, released late last month, the leading copper miner said it believed the leach innovation initiatives it was pursuing provided potential opportunities to produce incremental copper from its large existing leach stockpiles and lower-grade material currently classified as waste.

The company has been exploring the potential for incremental low-cost additions to its production and reserve profile for some time, saying in the latest results release that it had identified opportunities to achieve an annual run rate of 200 MIb/y (90,718 t/y) of copper through these initiatives by the end of 2023.

Freeport has a long history of copper leaching production with its Americas division, which includes assets such as Morenci and Cerro Verde, having developed and implemented industry-leading technologies for leaching of oxide ores.

The company has been pursuing internal and external initiatives to expand this leading position, focusing on traditional ores and sulphide orebodies that have been typically considered difficult to leach, like chalcopyrite.

This is where Jetti’s technology comes in.

The Colorado-based company has developed catalytic technology to allow for the efficient and effective heap and stockpile leach extraction of copper. This bolts onto existing solvent extraction/electrowinning (SX/EW) leaching plants so it can be deployed rapidly with limited capital expenditure and, because it uses no heating or grinding, has low operational costs. In addition, there are huge environmental benefits from using leaching over pyrometallurgy, according to Jetti.

A Freeport spokesperson confirmed to IM that the company was in a trial of the Jetti technology through “a commercial installation” at its Bagdad mine in Arizona, USA. This mine is one of its major leaching test hubs, with the company targeting over 3 MIb/y of incremental copper cathode production from the open-pit copper mine through this work.

Bagdad has a 77,100 t/d concentrator that produces copper and molybdenum concentrate, an SX/EW plant that can produce approximately 6 MIb/y of copper cathode from solution generated by low-grade stockpile leaching, and a pressure-leach plant to process molybdenum concentrate.

The spokesperson added: “There is potential to expand production via the treatment of additional stockpiles at Bagdad in the future based on results.”

The use of Jetti’s technology is one of several leaching initiatives the company is pursuing – some with outside vendors, some using its own technology and some with joint venture partners.

All of these are focused on not only adding low-cost production to Freeport’s large production base, but also achieving a lower carbon footprint.

Jetti, which Freeport is an investor in, has been conducting a carbon footprint study and Life Cycle Assessment (LCA) of its technology, with the LCA including analyses of typical copper mining operations without Jetti’s technology and a mining operation with Jetti’s technology installed. The LCA is being conducted in conformance with the ISO 14040/44 standard and will be critically reviewed by an independent expert.

Jetti Resources has developed catalytic technology to allow for the efficient and effective heap and stockpile leach extraction of copper

Jetti has also committed to starting to track water usage and waste at all its operations and sites, which includes the installation it has at Capstone Copper’s Pinto Valley operation, also in Arizona.

At Capstone’s operation, Jetti technology is being used extensively as part of a plan to recover up to 350 MIb of cathode copper over the next two decades from historic and new mineralised waste piles.

Teck Resources has also taken an interest in Jetti’s technology having signed an agreement for the evaluation of the solution at a number of Teck’s assets with potential copper resources outside of existing mine plans. BHP, through its BHP Ventures arm, is also an investor in Jetti.

As to Freeport’s wider leaching plans, it said it was looking to use data analytics to provide new insights to drive additional value, while new applications to retain the heat in the stockpiles were “yielding results”.

The company has assessed that it has some 38,000 MIb of contained copper in leach stockpiles deemed “unrecoverable” by traditional leach methods. Of this amount, about 50% is from the massive Morenci mine, which already has leaching production capacity of 900 MIb/y of copper.

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.”

Antofagasta readies primary sulphide leaching technology options

The ability to leach primary copper sulphides has, on many occasions, proved a hurdle too much, with conceptual work in the laboratory or pilot scale falling down on sub-economic or volatile recovery rates when working out in the field.

This problem tends to result in one of two things: new capital-intensive concentrators are brought into process these sulphides, or brownfield oxide operations are drafted up that prolong existing leaching operations for a few more years when – hopefully – copper prices are higher.

Antofagasta has come up with an alternative option that leverages chloride-based reagents and 20-years of knowledge leaching secondary sulphides.

Called Cuprochlor®-T, the proprietary process has undergone five years of intense development leading to the point that the company is now open to talking about its potential.

It leverages off the first iteration of leaching technology Antofagasta devised for secondary sulphides – Cuprochlor.

Cuprochlor, which is now working at the Michilla mine in Chile (which Antofagasta sold in 2016), effectively binds together the particles of mineral – particularly fine in the case of Michilla – into a porous but manageable material that can then be heap leached. The agglomeration is achieved by mixing the mineral and leach solution with chloride salts and sulphuric acid, which react to form a plaster-like paste.

Over the years, the process has been refined, going on to consistently deliver recovery rates of around 90%.

Sitting on an expansive base of primary sulphide resources – mainly chalcopyrite – and the success of Cuprochlor, Antofagasta, around five years ago, began a series of tests, adjusting variables such as temperature, reagent concentrations and particle size to see if the chloride leaching process could be adapted for the treatment of primary sulphides.

Temperature proved to be one of the keys, with tests showing that by elevating the temperature of the heap to around 30°C, Cuprochlor-T was able to stimulate the required chemical reaction for recovering copper from primary sulphides such as chalcopyrite.

Another key differentiator between the two chloride leaching technologies is the “reagent recipe” and particle size distribution (PSD), Alan Muchnik, VP Strategy & Innovation for Antofagasta, told IM.

“Providing a constant temperature throughout the process is very important, but the real innovation is the approach we have used,” he said. “It involves a combination of factors, including, among others, the recipe for reagent concentrations and the required PSD.”

While not wanting to reveal the ‘secret sauce’, Muchnik said the PSD consideration goes beyond the usual P80 industry reference point.

It is this balance that has landed the company with recoveries of over 70% after approximately 200 days of leaching on the heap in test work.

Muchnik expanded on this: “The Cuprochlor-T process, in simple terms, involves leaching in a chloride environment – where there are no passivation layer bonds. This allows for the copper, iron and chloride ions to react, which, at a controlled temperature, results in the economic production of copper.”

This is through three stages:

  • First up is an agglomeration stage where the necessary reagents are added and are left to rest at a constant aeration and temperature;
  • Second, the ore is irrigated intermittently with continued aeration, also maintained at a constant temperature; and
  • Finally, after 200 days, the ore completes the leaching cycle and allows the company to obtain recoveries of 70% copper or more.

What started with laboratory testing and progressed to pilot testing and a “semi-industrial” test on several different heaps at Centinela has recently concluded with an industrial test of over 40,000 t of primary sulphide material averaging 0.4% Cu – containing more than 90% chalcopyrite – that, using the same process outlined by Muchnik, showed consistent recoveries of over 70%, he said.

Alan Muchnik, VP Strategy & Innovation for Antofagasta

Asked if the company is eyeing even higher recoveries that can compete with the levels Cuprochlor is achieving on secondary sulphides, Muchnik said it was all about an economic tradeoff.

“It may be possible to hit such a percentage [as Cuprochlor], but that is not the aim or expectation with the kinetics we are currently seeing in Cuprochlor-T,” he said. “There is always a tradeoff between the length of irrigation time, the PSD and the recoveries, all of which are related to capital costs, operating costs and the payback associated with the process.”

The Antofagasta planning and operations teams have now got their hands on the Cuprochlor-T ‘licence’ and will be busy outlining potential deployments for consideration in the company’s annual planning cycles.

There are some obvious places to start.

The Zaldívar open-pit, heap-leach copper mine, 175 km southeast of Antofagasta, is currently in the process of transitioning to chloride leaching operations with Cuprochlor.

The project, which includes an upgrade of the SX plant and the construction of new reagent facilities and additional washing ponds for controlling chlorine levels, was completed in January 2022 and is now being commissioned. It is set to boost copper recoveries by approximately 10 percentage points, increasing production at Zaldívar by around 10,000–15,000 t/y over the remaining life of mine.

“In addition to transitioning to chloride leaching with Cuprochlor for secondary sulphides, we are currently progressing studies for the primary sulphide orebody that currently lies below the Zaldívar reserves to prove if Cuprochlor-T leaching can work,” Muchnik said. “Within our resource base, there are approximately 460 Mt of primary sulphide resources declared here.”

Both Centinela and Antucoya have primary sulphide resources and existing heap leach and SX-EW facilities that would fit the Cuprochlor-T blueprint too.

Muchnik said: “One of the technology attractions of Cuprochlor-T is the ability to use otherwise idle leach pad and SX-EW capacity. That it is the scale limitation at our current operations, but the technology can be gradually deployed within a plant that is already adapted for chloride leaching, phasing this in during the life of mine to fit requirements.

“It provides an ongoing adoption process option rather than an immediate infrastructure project that sees an operation shift from oxide leaching to a different kind of heap leaching in one go.”

The advent of Cuprochlor-T does not mean the company will completely drop potential concentration projects, Muchnik clarified, highlighting the second concentrator project currently subject to a feasibility study at Centinela.

In addition to the capital and operating cost benefits that would come with Cuprochlor-T over the concentration route, there is likely to be a sustainability benefit.

“It’s only an indicative reference as each case is different, but you would expect the energy consumption associated with Cuprochlor-T leaching and SX-EW treatment to be less than half of the normal route of copper concentration and SX-EW,” Muchnik said.

In this respect, it is a favourable consideration for Antofagasta’s long-term carbon-neutral goals.

While each potential Cuprochlor-T implementation will have to go through corresponding project studies, Muchnik was confident in predicting that new copper from Cuprochlor-T would be produced this decade.

With five years of substantial testing under its belt, not many metallurgists would bet against him.

McEwen Mining progresses gold-silver heap leach plan at Fenix

McEwen Mining looks to have found a way to prolong its operations at the El Gallo Complex in Sinaloa, Mexico, with the feasibility study for its 100%-owned Fenix project highlighting a 9.5-year operational blueprint.

Using gold and silver prices of $1,500/oz and $17/oz, McEwen has estimated an operation able to produce 26,000 oz of gold production in phase one (years one to six) and 4.2 Moz of silver-equivalent in phase two (years seven to nine-and-a-half).

Phase one comes with an initial capital bill of $42 million and an all-in sustaining cost (AISC) estimate of $1,042/oz of gold. Phase two would require a $24 million incremental capital injection in year six, with the AISC calculated at $14.28/oz of silver-equivalent.

The company’s El Gallo mine (pictured) produced 240,000 oz of gold and 125,000 oz of silver from 2012-2017, yet, due to the transition to deeper sulphide mineralisation not amenable to heap leaching, mining and crushing activities ceased in the June quarter of 2018.

While residual heap leaching is set to continue to produce gold for several years, the company has been working on a new project for the El Gallo Complex, which is where Fenix comes in.

The Fenix 2018 preliminary economic assessment evaluated the potential extension of production in the complex, based on a two-phased transformation of the processing from the El Gallo mine, innovative in-pit tailings disposal and sourcing from several deposits.

The latest feasibility study has run with that plan, with the critical path environmental permits in hand for the first phase of production, according to Rob McEwen, Chairman and Chief Owner of McEwen Mining.

“Our next steps will involve detailed engineering, assessment of procurement options and the evaluation of financing alternatives,” Rob McEwen said.

He added: “The project will incorporate an environmentally progressive method of tailings management, using in-pit storage that creates multiple benefits, most importantly a secure containment of tailings, enabling better reclamation results.”

Corvus Gold weighs heap leach, BIOX route at Mother Lode project

Corvus Gold has announced the results of a preliminary economic assessment (PEA) for its Mother Lode project (MLP) in southwest Nevada, USA.

The study outlines a project able to produce 170,980 oz/y of gold and 79,600 oz/y of silver through a combination of heap leaching and biological oxidation (BIOX).

Based off measured and indicated resources of 1.55 Moz of gold and 1.51 Moz of silver, and inferred resources of 170,000 oz of gold and 400,000 oz of silver, the study estimated an operation with an eight-year mine life and an initial price tag of $406 million. Using a $1,500/oz gold price, the payback period was estimated at 2.7 years.

Jeffrey Pontius, President and CEO of Corvus, said: “The results from our initial PEA study of the Mother Lode standalone project are encouraging. The potential projected annual gold production of over 200,000 oz/y during the first three years is significant, especially as a new project, which could provide an increase to the Corvus Gold future production profile. The PEA demonstrates the preliminary potential for the project, on its own, to produce significant free cash flow and after-tax NPV.

“Corvus now has a number of strategic alternatives available to it to drive shareholder value. Given the recent interest in the Bullfrog Gold District from multiple producing companies with adjacent land packages, Corvus’ compelling and accretive projects and its commanding land position with what we believe is demonstrated high exploration potential, has positioned the company to deliver increased shareholder value.”

The Mother Lode project is modelled as a large, open pit, with a biological oxidation mill to treat the higher-grade sulphide mineralisation and a heap leach pad for treatment of oxide mineralisation. The mining plan uses standard mining practices and has a production scale that is currently being used by many operating mines, the company said.

The new PEA study, which assumes a standalone project, also includes a number of other changes to the previously assumed concept for the combined Mother Lode-North Bullfrog project configuration, which enhance the project. This includes:

  • Employing BIOX to treat the MLP sulphide mineralisation would increase gold recovery by 11%. Metallurgical testing of a stirred BIOX process on the MLP whole sulphide mineralisation from Mother Lode demonstrated gold recoveries of 91-92% as compared with the previous testing on MLP flotation concentrate;
  • Eliminating the need for the concentrator, oxygen plant and autoclave components of the previous plant concept simplified the plant conceptual design and would reduce the process plant capital cost;
  • Ongoing work expanding Mother Lode resources in the CIZ area and the main Zone with ongoing work at improving the open-pit mining and development plans will enhance project economics; and
  • New experimental work on conducting the BIOX process in a heap is being tested as follow-up on past successful studies and could substantially cut operation and capital costs with the elimination of the mill circuit.

The PEA only includes drill results completed up until September 2020. In addition, Corvus will continue follow-up mineral resource expansion work and new discovery drilling on priority targets at both the North Bullfrog and Mother Lode properties through 2021, it said.

Rio2 to test Sixth Wave’s IXOS polymer tech at Fenix heap leach gold project

Sixth Wave Innovations Inc and Rio2 Ltd have executed a non-binding Letter of Intent for the trialling of Sixth Wave’s patented IXOS® purification polymer at the Fenix gold project in Chile.

Under the terms of the LOI, Rio2 will send representative ore samples from its Fenix project to Sixth Wave for testing and analysis in its Salt Lake City, Utah, facility. Sixth Wave will perform a combination of leaching and recovery tests using its IXOS technology on these samples consistent with protocols for the expected heap leach mining activity planned for Fenix.

Upon completion of the testing, to be performed in October, and pending positive results, the two companies will work to negotiate a definitive agreement to proceed to a complete on-site pilot adsorption/desorption/recovery (ADR) plant scaled to operate on a 400 t pilot leach pad.

A prefeasibility study on Fenix outlined a heap leach gold mine producing an average of 93,000 oz/y during the first 13 years and 50,000 oz/y during the final three years of production as stockpiled ore is being crushed and leached.

IXOS, meanwhile, has been demonstrated to capture up to 99% of gold from cyanide leach solutions in laboratory and mine site testing where the data was analysed by the mine operator, representing a material increase relative to activated carbon, which recovers between 85% and 95% of the gold, as reported by potential mining customers of IXOS. Additionally, the increased selectivity of IXOS results in the capture of fewer other competitive base metals, Sixth Wave says.

Testing at multiple mine sites has shown more than 90% gold purity captured on IXOS, as opposed to 40%-70% for those generated by activated carbon, resulting in efficiencies in the refining process used to generate higher purities of gold.

The objective of this work, from Rio2’s perspective, is to determine whether Sixth Wave’s IXOS technology can be successfully applied to enhance the extraction of gold from Fenix gold ore by using molecularly imprinted polymers rather than traditional carbon for the gold adsorption process.

If successful, the application of IXOS is expected to result in a reduction of capital expenditure and operating expenditure related to the gold extraction process.

Upon successful completion and positive results of the pilot program, the companies would then move to an implementation phase incorporating IXOS into the actual processing plant to be constructed at Fenix.

Dr Jon Gluckman, President and CEO of Sixth Wave Innovations Inc, said: “We are very excited about this project and working with Rio2. The IXOS process should excel in comparison to traditional activated carbon because of the high rejection of base metal and scaling and the smaller process plant required for IXOS. Substantially lower power consumption in the desorption and recovery stages, and no need for regeneration, will also play a large role in reduced opex.”

He added: “It is exciting to be involved with Rio2 at this phase of the Fenix gold project as it allows us the ability to optimise the design of the ADR circuit without having to worry about retrofit constraints.”

Alex Black, President and CEO of Rio2, said: “Rio2 is always looking to embrace and trial new technology with the objective of bringing enhanced value to our stakeholders through the reduced capex/opex opportunities that innovative technologies can bring.

“The Fenix gold project is currently the largest undeveloped gold heap leach project in the Americas and we look forward to working alongside Sixth Wave during the development phase of the project.”

Hycroft Mining ups the proprietary heap leach process ante

Hycroft Mining Holding Corp has continued to demonstrate the viability of its proprietary heap leach oxidation process at its Hycroft gold mine in Nevada, USA, over the June quarter, with the company hitting several milestones.

The Hycroft gold-silver mine was restarted in 2019 to demonstrate this process, which oxidises sulphides prior to leaching, on a commercial scale. Based on the success of initial operations and a 2019 feasibility study, Hycroft began implementing the long-term mine plan with the start of construction in April 2020 of the first phase of a large leach pad capable of processing the resource base with more than 30 years of mine life.

While gold and silver production fell below expectations over the period, the company was able to demonstrate the process on initial leach pads one and two at Hycroft, achieving higher than feasibility level gold recoveries for Brimstone ore (82% versus 65% in the feasibility study) and Central ore (91% versus 70% in the feasibility study).

It also improved the solution management system to increase solution distribution to the leach pads, while commencing the leach pad expansion on the north side of the mine in anticipation of starting heap leach stacking in the December quarter of 2020, Hycroft said.

The expansion project will provide the company with the leach pad space required for future operations, the company added.

“The initial stage of the leach pad project is being constructed in two phases by a contractor, with the first phase consisting of approximately 4 million sq.ft (3.7 million sq.m) of pad space and infrastructure for ponds, pipes and electricity, and the second phase consisting of approximately 4.6 million sq.ft, which we expect to construct in 2021,” the company said.

“With respect to the first phase, we expect the earthworks and leach pad construction to be completed in the fourth (December) quarter of 2020 and infrastructure completed and initially commissioned shortly thereafter.”

On the process side, the downstream process infrastructure is in place to ramp up operations. Hycroft is currently operating the Brimstone Merrill-Crowe facility and refinery, but it has begun planning to restart the 21,500 gallons/min (1,629 l/s) North Merrill-Crowe plant in 2021 to meet increasing solution flows from the new leach pad.

To facilitate these heap leach changes, the company expanded its mining fleet with the rental of seven 240 ton (218 t) trucks and one loader to increase mining capabilities over the quarter. It also improved its mobile equipment maintenance team to transition to self-performed maintenance and discontinue the contractor-led maintenance applied since start-up. Lastly, it began active in-pit drilling and blasting of fresh ore and reduced the mining of stockpiles.

On the crusher side, it refurbished and recommissioned the crushing system, which saw the average amount of material crushed go from 338,000 tons/mth (306,628 t/mth) in the March quarter to 459,000 tons/mth in the June quarter, an increase of 36%. It also established a comprehensive preventative maintenance program and initiated an ongoing operator training program to improve crusher efficiency and reduce downtime.

Steve Jones, Interim President and CEO of Hycroft Mining, said: “There have been a number of improvements at the mine recently that are building a strong foundation for the next phase of operations, including adding experienced technical people and increasing the reliability of process infrastructure.

“While the next few months are still considered to be transitional, we are looking forward to utilisation of the new leach pad and being able to ramp up to feasibility study operating levels.”

Centerra Gold’s Öksüt mine comes to life with first pour

Centerra Gold has achieved the first gold pour from its Öksüt mine, in Turkey, on schedule and ahead of budget.

Additionally, the project achieved a significant safety milestone last week, achieving two million work hours lost time injury free.

Scott Perry, President and Chief Executive Officer of Centerra, said: “This is an important milestone for the project and for the growth of the company as Öksüt is now our third operating mine and our third source of gold production going forward. Reaching the first gold pour is a testament to the dedication and hard work that our Öksüt team has put in to reach this goal safely.”

He added: “This milestone would not have been achieved without the initial conviction and perseverance from the Centerra exploration team given that the Öksüt mine, originally started as a greenfield exploration venture in 2009.”

Öksüt was planned as a conventional truck and shovel open-pit heap leach mining operation with a stacking rate of 11,000 t/d. The initial eight-year mine life was expected to process around 1.2 million contained ounces of gold from two open pits, the Keltepe pit and the smaller Güneytepe pit.