Tag Archives: gold processing

EnviroGold highlights sustainable metal reprocessing credentials at Hellyer, Buchans Tailings projects

EnviroGold Global Limited says the precious (gold, silver) and battery metals (copper, zinc, lead) to be produced at the company’s Hellyer Tailings and Buchans Tailings reprocessing projects are expected to show a 96% reduction in greenhouse gas (GHG) intensity per gold-ounce-equivalent produced and an over 80% reduction in energy intensity relative to industry averages for conventional mining.

EnviroGold Global’s circular-economy business model is designed to produce precious, critical and strategic metals while reprocessing mine waste (tailings), which often contain significant quantities of valuable precious, critical and strategic metals.

EnviroGold Global’s analytics-driven approach to project origination and development leverages extensive mine production data, mill production data and geological records to identify tailings sites that are expected to contain significant quantities of residual metals due to refractory mineralogy and/or to the inefficiency of outdated technology used during legacy mining operations. In addition to recovering precious, critical and strategic metals, the company says it remediates the tailings consistent with environmental best practices, thereby reducing the environmental footprint of legacy mining. Further, by eliminating the extractive phase (mining) of metal production, the company expects to reduce the energy intensity of metal production by over 80%.

Leveraging the framework set forth by the World Resources Institute’s Greenhouse Gas Protocol, EnviroGold Global’s detailed assessments of expected Scope 1 and Scope 2 emissions for the company’s planned operations at the Hellyer Tailings and Buchans Tailings reprocessing projects indicate that the carbon intensity of the gold-equivalent ounces of precious, critical and strategic metals produced by the company will be 96% lower than industry averages for conventional mining. S&P Global Market Intelligence reports that the typical conventional mining operations generated nearly 1 tonne of CO2 per gold ounce produced.

Just last month, EnviroGold Global executed a binding definitive agreement with Hellyer Gold Mines Pty Ltd to reprocess the tailings owned by HGM at its namesake mine in Tasmania, Australia (pictured). Hellyer is owned by NQ Minerals, with the company having a plan to increase its financial year production to 1.5 Mt of tailings reprocessing in 2022, from the estimated 1.4 Mt in 2021. Earlier this month, EnviroGold announced that test work completed to date on its proprietary flowsheet demonstrated gold recovery rates of 83.5% and silver recovery rates of 94.6% from the refractory, volcanogenic massive sulphide tailings at Hellyer.

In 2021, it announced the execution of binding commercial agreements, which saw the Buchans River Delta Reclamation Project added to its portfolio of environmental remediation and asset reclamation projects, saying that it planned to deploy proprietary modular, scalable reclamation technology & systems able to process up to 1,000 t/d of reclaimed tailings to remediate the legacy tailings while removing environmental contaminants and reclaiming valuable commodities at the project.

EnviroGold Global CEO, Dr Mark Thorpe, said: “Whether serving as critical components for batteries, electric vehicles and clean-energy infrastructure, or as a store of value and hedge against inflation, metals have never been more critical to the modern, global circular economy. EnviroGold Global’s Metals Without Mining business model is designed to sustainably satisfy the world’s increasing demand for precious, critical and strategic metals by eliminating the most carbon and energy intensive phases of metal production, creating a win-win for corporate, community and environmental stakeholders.”

The Global Tailings Review reports that the total number of active, inactive and closed tailings storage facilities worldwide exceeds 8,500. The global footprint of tailings exceeds 280,000 Mt with an additional 12,700 Mt produced annually. The value of precious, critical and strategic metals contained in global tailings sites is estimated to exceed $3.4 trillion.

EnviroGold Global’s commercial strategy involves identifying, qualifying and developing tailings reprocessing opportunities, generally targeting tailings sites with at least 6 Mt of tailings and gross recoverable metal value of $124/t of tailings. Tailings sites meeting EnviroGold Global’s internal assessment criteria pass through an advanced screening process, which includes detailed technical/economic modelling incorporating expected recovery rates and site-specific process-level economic analysis.

The company has reviewed over 325 global tailings sites to date and has eight “major projects” in its global tailings reprocessing portfolio. EnviroGold Global expects to commence commercial metal production in 2022 at its Hellyer Tailings reprocessing project. The company will continue to acquire the rights to tailings reprocessing opportunities around the globe and subsequent to achieving commercial metal production at the Hellyer project will leverage strategic operating partnerships to scale up commercial metal production at multiple projects simultaneously.

Chemours offloads Mining Solutions business to Czech-based cyanide producer

The Chemours Company has entered into a definitive agreement to sell its Mining Solutions business for $520 million in cash to Draslovka Holding as, a Czech-based private company specialising in cyanide production.

The transaction is expected to close in the December quarter of 2021 subject to regulatory approvals and other customary closing conditions.

Chemours announced back in March that it had initiated a strategic review to assess the potential sale of its Mining Solutions business, which is a part of Chemours Chemical Solutions segment and is one of the largest North American producers of solid sodium cyanide.

Mark Newman, Chemours President and CEO, said: “Today’s announcement of the Mining Solutions divestiture furthers our strategy of focusing on our three principal businesses in order to drive long-term shareholder value. Leveraging differentiated strategies, we feel confident that our businesses are well positioned to deliver growth and higher-quality earnings through economic cycles.

“The entire Mining Solutions team has worked hard to create a leading business with an unmatched record of safety and supply chain stewardship. Draslovka’s long-standing expertise in cyanide, coupled with a strategy devoted to growing this business, makes them an ideal partner invested in the success of our Mining Solutions employees and customers.”

Pavel Brůžek, CEO of Draslovka, added: “The acquisition marks Draslovka’s first major investment in the US and advances Draslovka’s international expansion plans. Our ambition is to use Draslovka’s CN-based specialty chemicals expertise and technological capabilities to support our global growth plans, and drive improvements in safety, efficiency, and environmental considerations throughout the industry.”

Gekko installs OLGA, Carbon Scout solutions at Gruyere as part of collaborative project

Gekko Systems, as part of a collaborative project to collect and analyse real-time gold reconciliations and automate gold processing plants, has installed its OLGA and Carbon Scout solutions at the Gruyere gold mine in Western Australia.

In October 2020, METS Ignited Industry Growth Centre announced the consortium of Gold Fields, Orway IQ, CSIRO, Curtin University and Gekko Systems as recipients of the Tranche 4 Collaborative Project Funds. The METS Ignited funding will assist the development of this project.

In a world-first, the project draws together a range of technologies, including the Gekko OLGA and Carbon Scout, and skill sets that are the first step to truly understanding what is happening in a gold production plant in real time and will eventually lead to a fully autonomous gold plant, Gekko said.

Gekko recently installed the OLGA and Carbon Scout at Gruyere (a joint venture between Gold Fields and Gold Road Resources), the site where the project will become reality.

“The Gekko OLGA and Carbon Scout will revolutionise the industry’s ability to measure gold circuit inventory and recovery in real time, move it into the digital world and provide opportunity for full automation,” Gekko said.

OLGA is a world first on-stream analyser designed to continuously read low grade gold grades in slurries and solutions, giving operations the ability to see and control their plants in real time, the company says. The alternative traditional sampling methods involve significant delays – of up to one or two days for feedback.

The Carbon Scout is a self-contained, ground-level sampling system to improve carbon concentration measurements in carbon-in-leach and carbon-in-pulp circuits to an accuracy of ±0.5 grams of carbon per litre of pulp. Uniquely, multiple other data points include slurry density, pH, DO and gold loading on carbon, Gekko explained. Data profiles are provided in every tank, every hour.

“The combination of OLGA and Carbon Scout, supported by the Gekko Sample Delivery System, means all CIL/CIP sampling can be done conveniently and safely at ground level,” it said. “Each tank is sampled by a patented pumpless delivery system. All samples in the plant including leach feed and tails will be delivered through this system to potentially alleviate the need for expensive cross-cut samples.”

The team of Orway IQ will deliver the data through the Trinity program. With the MillROC data system and the Gekko technical team using the data for system analytics.

The ultimate aim of the project is to have gold process and recovery data being analysed within minutes rather than days from anywhere in the world and for production to be adapted to reflect this data, Gekko said.

DST to help Newmont go cyanide-free with CLEVR agreement

Dundee Sustainable Technologies has entered into a Technology Transfer Licensing Agreement with Newmont for the use of DST’s cyanide-free gold extraction technology, known as the CLEVR Process™.

DST has been in ongoing discussions and technology review with Newmont regarding its CLEVR gold extraction process to evaluate and quantify its applicability on projects selected by Newmont.

Following a successful test work program in the March quarter of this year, Newmont expressed its interest in the execution of such an agreement allowing Newmont to conduct laboratory CLEVR leaching tests in its technical facilities in Englewood, Colorado.

The method used by DST uses no cyanide, produces no toxic liquid or gaseous effluent, and the solid residues are inert, stable and non-acid generating, according to the company.

David Lemieux, President and CEO, said: “We are very pleased to announce this agreement with Newmont which is the culmination of much work and dialogue between our companies. Our collaboration with a global gold producer is the result of years of continuous efforts in developing an innovative and technically sound process for the industry.”

He added: “Today’s announcement is further validation of DST’s CLEVR Process as one of the leading cyanide-free alternatives for the gold industry, and it represents an important milestone in the early-stage adoption and understanding of our technology by a world leading gold company.”

As part of the agreement, DST and Newmont, agreed to:

  • A two-year, non-exclusive licence for the utilisation of CLEVR at the laboratory scale in its Colorado technical facilities with an option to renew, for an additional two-year period under the same terms;
  • Technology implementation support by DST, including all technology laboratory protocols in addition to technical training sessions to initiate and support the technology transfer and practical operations;
  • Ongoing technology support and for DST to review the laboratory test plans, execution, and results conducted by Newmont; and
  • Any process scaling-up requirements, resulting from positive applications of CLEVR, will be conducted jointly with Newmont at DST’s technical facilities in Canada and/or on-site using DST’s technology and engineering group expertise.

The objective of the agreement is to facilitate the adoption, understanding and application of CLEVR on various gold projects being, or to be, developed by Newmont. The agreement was executed on November 25, 2020.

Heritage eyes up Mount Morgan riches, rehabilitation

A partnership between GreenGold Engineering and Heritage Minerals Pty Ltd has plans to return the Mount Morgan gold mine in Queensland, Australia, to some of its former glory by creating a mean and green way to extract gold from its ample tailings deposits.

The cooperation allows Heritage Minerals to develop the project in a proactive program to maximise the best chance of project success, the company says. Heritage admits it has a big task on its hands, facing doubters that have witnessed a string of false starts at Mount Morgan.

The story behind Mount Morgan dates to 1882 when a syndicate was created to open a gold mine at Ironstone Mountain, 39 km south of Rockhampton.

Ironstone Mountain, later renamed Mount Morgan, was originally operated as an open-pit gold mine at the top of the mountain, before being converted to an underground copper and gold mine.

In 1935, it transitioned back to an open-pit operation and continued until the mine closed in 1980. After this, Peko Wallsend Ltd ran a tailings treatment operation from 1982 until 1991, recovering gold from 27 Mt of tailings.

Mount Morgan pioneered many metallurgical processes to cope with the unique properties of the ore over this time. From chlorine leaching in the early days to various flotation and smelting furnace techniques for the copper/gold ore, the Mount Morgan tailings stockpiles have a rich and varied history.

At different stages over the life of the mine, copper was either a bonus or a nuisance. When copper grades were high, copper was a financial benefit; when the copper grade was low, the metal increased the operating cost associated with gold recovery.

This more than century of mining and processing came with consequences.

The pyrite remaining in the mine and tailings dumps is acid-forming and has generated a significant environmental legacy which remains today. This legacy has become the responsibility of the State of Queensland (1993) and is managed by the Department of Natural Resources and Mining’s (DNRM) Abandoned Mines Division.

Despite these environmental liabilities, five companies have come back to Mount Morgan since Peko Wallsend stopped operations in the early-1990s, encouraged by higher yellow metal prices and improved processing options for the refractory ore.

“We’re the sixth company to have a shot at reprocessing the tailings, with none of the companies before us getting past the feasibility study stage into financing,” Peter Mellor, Corporate Secretary at Heritage Minerals, told IM.

All of them were unsuccessful primarily because of the presence of nuisance copper and the high cyanide consumption that comes with removing this, according to Mellor.

The most recent company to try its luck at Mount Morgan is a case in point.

ASX-listed Carbine Resources developed a process flowsheet to remove part of the troublesome copper by acid leaching the tailings and producing copper sulphate. Additional revenue from the production of pyrite concentrate supplemented gold sales.

It was the production of premium quality (50% sulphur) unroasted iron pyrite concentrate that enabled the commencement of the reduction of acid-forming material at Mount Morgan, Carbine said.

Despite coming up with a 1.1 Mt/y blueprint that, in the expanded case, could operate for 20 years and produce 23,000 oz/y of gold, 2,700 t/y of copper sulphate and 200,000 t/y of pyrite concentrate, the plan ultimately fell down on the projected economic returns, negatively impacted by excessive royalty liabilities.

A February 2018 update came with a revised operating model at Mount Morgan showing all-in sustaining costs (AISC) of A$862/oz ($621/oz), A$313/oz higher than the company’s December 2016 feasibility study.

“The increase is due primarily to higher cyanide consumption and lower by-products credits due to a lower pyrite price and the loss of copper sulphate premium associated with a change in the copper products produced,” Carbine explained.

Fresh approach

To be fair to Mellor and the Heritage team, they are not looking to repackage the same project blueprint in a markedly better gold price environment as other companies have been known to attempt. Instead, they are setting up the project and the town of Mount Morgan for a brighter and sustainable future.

After gaining rights to the project from Norton Gold Fields following Carbine’s exit, one of the first things Heritage did was appoint GreenGold to carry out the definitive feasibility study.

Equipped with its ReCYN resin-based technology that has been shown on other projects to reduce cyanide consumption by up to 50% through capturing free cyanide from plant tailings and recycling it back into the leach circuit, the selection was an obvious choice.

The company could potentially detoxify the tailings stream and clean up the water discharge at Mount Morgan. This would be a boon for the DNRM, which currently treats the water from the open pit and tailings deposits before being released into the local creek due to the low pH levels caused by the acid-forming pyrite.

“Our process plant will use this water, treat it and send it out as clean water down the creek,” Mellor explained.

This is one of several changes the company is implementing to make the project viable.

“For example, Carbine were previously looking to float off the nuisance copper at the start, which came with the associated capital costs of building a flotation plant,” Mellor said. “Yet, the copper really represented a low amount of revenue (2,700 t of copper sulphate in the studies) overall.”

The ReCYN resin plant can deal with the higher cyanide consumption needed to treat the copper at the back end of the flowsheet. This will allow the company to focus on the gold – which represents 90% of revenue – that can be processed by a technically-simple carbon in leach plant.

Malcolm Patterson, MD of Heritage Minerals, and Peter Papa, Technical Director of Heritage Minerals, observe the task ahead at Mount Morgan

The open pit is partially filled with previously processed tailings, with Mellor saying the reprocessing of 10 Mt of tailings (averaging 1.1 g/ Au) can help complete the rehabilitation process.

“We have come up with a really neat environmental rehabilitation scenario where we fill the existing open pit up, and cap it all off nicely so the surface water cannot penetrate,” he said.

Set to build a 2 Mt/y plant to re-process this material, Heritage is only looking five years out from first production, although there is potential for this processing quantity to be doubled.

Even with this near-term gaze, the definitive feasibility study (DFS) anticipates a one-year payback and an upfront capital expenditure bill of A$74 million (compared with Carbine’s last A$96 million estimate).

“There is more potential than this,” Mellor says of the feasibility study, highlighting several areas of interest within proximity of the existing open pit. “Yet, we wanted to get the economic, environmental and social aspects ticked off first before laying out any longer-term plans.”

The company has been very thorough in coming up with this five-year plan.

Already blessed with an extensive JORC resource database from previous Mount Morgan tailings reprocessing protagonists, the company continued to drill for tonnage and bulk density definition of the tailings resource; the latter with a Dando percussion drill rig capable of punching 1 m cores down to 30 m depth.

With a board decision on the DFS expected before the end of the year, Heritage could soon enter the financing stage, followed (hopefully) by construction.

If all goes to plan, operations – a simplified earthmoving and processing method – could begin in 2022.

“Mount Morgan is definitely not the easiest site, but it is the most prestigious in terms of history and challenges,” Mellor says.

Heritage and GreenGold will soon be judged by the financing community on whether they are up to such a challenge.

Corem’s cyanide recovery and recycling process wins federal, provincial backing

Quebec-based Corem is to receive C$2.1 million ($1.6 million) of funding from the Canadian government to support the development of an innovative process for the recovery and recycling of cyanide in the gold extraction process.

This new process is more environmentally sustainable and reduces the impact of gold mining on the aquatic ecosystem, according to Natural Resources Canada.

The announcement was made by Jean-Yves Duclos, President of Treasury Board of Canada and Member of Parliament for Quebec, on behalf of Seamus O’Regan, Canada’s Minister of Natural Resources. The Quebec Ministry of Energy and Natural Resources is also contributing an additional C$100,000 to this project, according to the government.

Following this cash injection provided through Natural Resources Canada’s Clean Growth Program, Corem will work to accelerate the deployment of the process at commercial scale by constructing a pilot-scale processing plant, NRC said.

“Corem’s promising recycling technology is expected to reduce the volume of contaminated water stored in tailings ponds, thereby contributing to the sustainability and competitiveness of the mining industry,” it added.

Francis Fournier, President and Chief Executive Officer of Corem, said: “This financial support demonstrates the importance and interest in the development of clean technologies for the mining industry and the Government of Canada. It allows Corem to pursue its mission of developing innovative solutions for the benefit of a sustainable mining industry and of working closely with our members, our customers and our partners.”

The Clean Growth Program invests in clean technology research and development projects in Canada’s energy, mining and forest sectors. The program is a C$155 million investment fund that helps emerging clean technologies further reduce their impacts on air, land and water while enhancing competitiveness and creating jobs, it says.

It also provides federal laboratory support for innovators under the Science and Technology Assistance for Cleantech initiative, which is intended to help bring Canadian clean technologies to market by providing federal research expertise, facilities and equipment.

Classic Minerals enlists Gekko gravity unit for processing Kat Gap gold

Western Australia-focused gold exploration and development company Classic Minerals says it has secured a Gekko gold gravity processing plant to be used for future on-site processing of gold ore at its Kat Gap gold project.

Kat Gap, around 120 km southeast of Southern Cross, Western Australia, has an existing 93,000 oz JORC resource with strong exploration upside and scope for high grade open-pit mining, the company says.

Gekko is a leader in the manufacture of gold processing plant and machinery with its plants boasting small footprints and low environmental impact.

An added attraction to Classic is that the Australia-made Gekko plant is modular and mounted on containerised elements providing for scalability and ease of modification, it said. The plant has a 30 t/h capacity and is scalable to a Gekko Python plant (pictured) with a processing capacity of 250 t/h, Classic added.

“Also, the mobility associated with the modular construction enables Classic to locate the plant adjacent to the orebody, which further minimises cartage and processing costs,” it said.

Classic’s purchase is for a two-stage gravity concentration plant from Gekko, which will be provided fully refurbished to new condition. The two-part plant will form the basis of the processing facility to be set up and operated by Classic at Kat Gap.

The company said: “Classic is now on track to set-up, commission and test the Gekko plant and commence processing of the gold rich ore at Kat Gap. The Gekko plant is ideally suited to processing Kat Gap ore, which has a unique high gravity gold concentration. Classic will have the capability and capacity to commence production as soon as the mining approvals (MLA 74/249) have been granted.”

To provide an immediate revenue stream, Classic has also commenced negotiations to toll treat any initial parcels of ore from Kat Gap, while the full-scale plant is configured to suit Kat Gap ore, it added.

Outotec addresses cyanide consumption with new BIOX refractory gold process

Outotec has introduced its new MesoTHERM BIOX process to significantly reduce cyanide consumption in refractory gold ore treatment.

Traditionally, cyanide consumption with conventional bio-oxidation residues is higher than with residues produced through other oxidative technologies. The Outotec MesoTHERM BIOX® process, based on Outotec’s existing mesophile BIOX process, offers an easy, cost-effective upgrade path that can cut cyanide consumption by as much as 50% compared with conventional bio-oxidation, the company claims.

The BIOX process, which has been in commercial operation for over 30 years, was developed for the pre-treatment of refractory concentrates ahead of conventional cyanide leaching for gold recovery.

“The Outotec MesoTHERM BIOX process enhances the established mesophile BIOX process by combining mesophile bio-oxidation technology with a higher-temperature thermophile oxidative stage to enable an even more effective overall sulphide oxidation step,” Outotec says.

On top of cutting cyanide consumption by as much as 50% compared with conventional bio-oxidation, MesoTHERM BIOX significantly reduces the formation of thiocyanate – a common and stable cyanide species traditionally formed as a further by-product, the company said.

Solubilised species prevalent in the mesophile stage are decanted off in an inter-stage thickening step between the two oxidative processes, simplifying operation of the thermophile stage, the company explained.

For existing BIOX customers, upgrading to BIOX MesoTHERM is a “relatively simple process”, Outotec says. It involves reconfiguring the circuit with the addition of Outotec’s High Rate Thickeners for inter-stage thickening and Outotec OKTOP® Atmospheric Reactors for the thermophile step.

Craig van Buuren, Senior Process Engineer, Outotec, said: “Our conventional mesophile BIOX process has enabled the production of over 25 Moz of gold to date. This novel process takes advantage of these proven technologies to help our customers achieve significant cost savings while also reducing their environmental footprint.”

DST’s CLEVR Process ups gold extraction yields in metallurgical test work

Dundee Sustainable Technologies (DST) has hit a new milestone, with results from metallurgical testing on mineralised samples from a top tier gold producer achieving extraction yields of up to 95.6% with the help of its cyanide alternative CLEVR ProcessTM.

DST received a circa-10 kg sample of material from an operating gold mine in South America, with the company mandated by the producer to conduct a metallurgical test program at its facilities in Thetford Mines, Canada. The objective was to define and quantify the gold extraction amenability of the CLEVR Process on the provided material.

In May 2020, DST completed the metallurgical test program and says the direct application of the CLEVR Process on the producer’s sample achieved gold extraction yields of up to 95.6%. Given the low sulphide concentration of the sample, no oxidation was necessary before proceeding to the CLEVR Process leaching step, it noted.

The method used by DST uses no cyanide, produces no toxic liquid or gaseous effluent, and the solid residues are inert, stable and non-acid generating, according to the company.

“The direct CLEVR Process leaching, without any pre-treatment, was successful and demonstrated higher gold extraction yields (>90%) when compared with cyanidation (67.6%) tests conducted on the same material,” the company said. “DST’s standard CLEVR Process conditions were utilised, which allowed for superior gold yields in a fraction of the time (one-hour leaching time).”

In addition, the solid tailings residues produced by the CLEVR Process met the US Environmental Protection Agency’s Toxicity Characterisation Leaching Procedure and may be considered as non-hazardous waste products, DST explained.

“DST is very excited with the results obtained using the CLEVR Process and the collaboration with the producer,” the company said. “The corporation will continue its development efforts with the producer to further develop this promising opportunity and the technical and economic parameters of DST’s Technology.”

In March 2020, DST tested two distinct lots of circa-50 kg and circa-30 kg samples of representative material from a gold miner’s operating mine in the Asia-Pacific region. The laboratory metallurgical test program showed the direct application of the CLEVR Process on oxidised samples achieved gold extraction yields of 93.5% and 94.2%, respectively, for the distinct lots tested.

GreenGold’s ReCYN processing pipeline continues to grow

GreenGold Technology has been making huge waves of late, with its biggest ReCYN resin-based technology build to date nearing completion and several new projects on the horizon.

ReCYN reduces cyanide consumption by up to 50% by capturing free cyanide from plant tailings and recycling it back into the leach circuit while recovering metal complexes and making them available for sale, according to the company. In the process, it detoxifies the tailings stream and guarantees 100%-compliant clean water discharge.

Such technology is in serious demand considering the industry’s operational cost focus, increased stakeholder pressure around the use of cyanide, the need to recycle and replace as much water as possible, and a necessity to improve project economics through the recovery of all payable metals.

On top of this, new and existing gold projects are becoming difficult to process through conventional means with problems around by-products such as copper often proving to be the difference between a sub-economic and economic mine development proposition.

The ReCYN process is based on the use of a functionalised resin bead, pre-treated to allow the dual duty of recovering free and complexed cyanide ions from solution with a high degree of efficiency. GreenGold works with local construction companies to customise treatment plants for each operation to match the various solution chemistries and throughputs, it says.

“The two areas of cyanide recovery and metal detoxification are balanced to achieve the desired compliance levels,” GreenGold says. “Equally applicable to slurries and solutions, the process is technically and economically superior to all others currently available for the detoxification of gold plant tailings.”

The company currently has four ReCYN options for clients, according to Commercial Director, Peter Mellor.

ReCYN I is for active (free) cyanide reduction, while ReCYN II has been devised to include detox applications to recover cyanide complexes such as copper. ReCYN III adds gold recovery as a “secondary function” to the mix.

The fourth option (ReCYN IV) includes gold recovery as a primary option, Mellor told IM, explaining that the development of a plant offering in this configuration could remove the need for a carbon in leach treatment plant in some applications.

It is a ReCYN II installation the company is currently putting the finishing touches to at PT Agincourt Resources’ Martabe gold-silver operation in Sumatra, Indonesia (graphic above).

This project, which will detoxify tailings and recover cyanide and copper, was previously estimated by Whittle Consulting to provide a $126.9 million upside to the project.

Speaking to IM from Australia, Mellor said the company was just over a month away from completing the plant at Martabe before COVID-19 restrictions hit progress. He was confident the company would be back completing plant commissioning before the end of the year.

By far the biggest ReCYN installation of the technology, the ReCYN II plant at Martabe will fit into the 5.5 Mt/y circuit and treat around 1.2 t/d of copper, Mellor said. It will also have benefits in terms of reduced cyanide consumption and improved water quality at the operation.

While work in Indonesia is currently not taking place, the company is making significant progress elsewhere.

Mellor said GreenGold had started detailed engineering for a plant in the Ivory Coast, while it had also completed an economic study on a legacy gold operation in Australia that showed compelling economics and the potential for a ReCYN IV installation for processing gold-bearing tailings.

The company also has some 40 projects it is working on in the laboratory – from Australia to the US – with client awards expected in the next few months.