Tag Archives: cyanide

Green Gold to test cyanide reduction tech on Poseidon’s Windarra gold tailings project

Poseidon Nickel says it has signed a binding heads of agreement with Green Gold Projects Pte Ltd (GGP) for the processing of the Windarra Gold Tailings Project in Western Australia.

The agreement could see Green Gold deploy its patented technology at the project, which includes ReCYN, which, through the use of a resin-bead absorbent, can reduce cyanide consumption by 50%, capturing free cyanide from the plant tailings and recycling it back into the leach circuit while recovering metal complexes and making them available for sale.

In the process, ReCYN detoxifies the tailings stream and guarantees 100%-compliant clean water discharge, according to Green Gold.

Its technology is already being tested at PT Agincourt Resources’ Martabe gold-silver operation in Sumatra, Indonesia, to detoxify tailings and recover cyanide and copper.

The binding agreement outlines the proposed partnership with GGP for the processing of the tailings, with a final agreement subject to GGP being satisfied with the outcome of metallurgical test work and a bankable feasibility study being completed at GGP’s expense.

The Windarra Gold Tailings Project consists of the Windarra and Lancefield (pictured) tailings with combined mineral resources of 5.96 Mt at 0.84 g/t Au and 2.1 g/t Ag, containing 180,000 oz of gold. A definitive feasibility study (DFS) was completed by Poseidon and released in mid-2021, which investigated using two different mining methods on the Windarra tailings, amphibious dredging or hydraulic mining and the construction of a modular 1.5 Mt/y processing plant to recover up to 55,000 oz of gold over a 45-month period.

The economic analysis indicated a project with an net present of circa A$20 million ($13.5 million) and internal rate of return of 45-50% depending on the mining method, assuming a gold price of $1,750/oz and an exchange rate of A$1 to US$0.75.

“While the outcome of the DFS was positive, the company is focused on the restart of the Black Swan project and decided that finding a partner to develop and operate the Windarra Gold Tailings Project was the best outcome for shareholders,” Poseidon said. “This process commenced earlier in the year and significant interest was received from various parties.”

Poseidon Nickel Managing Director and CEO, Peter Harold, said: “This agreement (with GGP) is a significant milestone in the company’s strategy to monetise the Windarra Gold Tailings Project. Green Gold Projects is an experienced developer and operator and is currently active in 30 projects globally.”

Upon achieving the test work and feasibility study milestones, GGP will earn a farm-in interest in the project. In return, Poseidon will receive consideration in the form of cash payments – upfront and upon project financing and a free carried profit interest of 8%. The funding, development and operation of the project will be the responsibility of Green Gold.

“The proposed partnership with Green Gold is an ideal outcome for Poseidon given our focus on the development of our nickel projects,” Harold said.

GGP was selected as the preferred partner given its experience as a developer and operator of similar projects, Poseidon said. Its patented technology has the potential to improve the economics of the project, according to the company.

The binding agreement outlines certain conditions to be met to reach a final agreement to develop the project. These include:

  • Metallurgical test work performed by GGP on the Windarra and Lancefield tailings to determine if its patented technology can improve gold recovery;
  • The rights and obligations of the Lancefield tailings right-to-treat Agreement are assigned to GGP; and
  • GGP receiving Foreign Investment Review Board and any other anticipated approval if required.

Subject to the satisfaction of these pre-conditions, Poseidon will grant GGP the right to farm-in to the project subject to the completion of the following milestones:

  • Milestone 1: GGP making a non-refundable upfront payment of A$250,000 upon satisfying the pre-conditions mentioned above to earn an initial 13.8% interest in the project;
  • Milestone 2: GGP completing a positive bankable feasibility study on the project to earn a further 13.8% interest in the project; and
  • Milestone 3: GGP making a final investment decision, securing funding for the project, and making a non-refundable payment of A$1 million to Poseidon to earn a further 64.4% interest in the project.

Poseidon will then retain an 8% free carried profit interest in the project, which entitles the company to 8% of the profit while not contributing to any capital or any other payments. The binding agreement also specifies that the project must be in production within three years from the date that the last farm-in milestone is satisfied, and that GGP will be solely responsible for meeting any rehabilitation or other environmental liabilities arising from the project.

Gekko Systems improves carbon sampling accuracy, safety at Cowal gold mine

The technical team at Gekko Systems has released further data that, it says, supports the benefits of new technology that optimises carbon management systems in gold processing facilities.

Optimising carbon management in the carbon-in-leach (CIL) circuit reduces gold solution losses and improves gold circuit recovery. This is essential for sites needing to offset higher inflationary costs with improved revenue, Gekko says.

The case study, released today, reviews operational performance of Gekko’s Carbon Scout at Evolution’s Cowal Gold Operation in New South Wales, Australia.

The Carbon Scout is a self-contained, ground-level sampling system that measures carbon concentration, as well as pH, DO and, more recently, has an option to measure gold loading on carbon using XRF technology on an hourly basis. Optimising the Carbon Scout for site conditions allows for more accurate, reliable and repeatable measurement of the carbon inventory of the CIL
circuit, Gekko says. Automating data collection and process actions such as carbon transfer, meanwhile, reduces operator risk exposure and person-hours (previously dedicated to the manual data collection tasks).

Installation of the Carbon Scout at Cowal commenced in February 2019, with the Gekko Systems Digital Services and Technical team providing ongoing support – both onsite and remotely – in the initial months of the system’s operation to ensure maximum availability was achieved and Evolution Mining was receiving the full benefit of the Carbon Scout.

After a few months of integration with the SCADA system, the Carbon Scout was able to use the data and analysis to facilitate automated transfer of the carbon inventory within the circuit to maintain pre-determined concentrations, according to Gekko.

The Carbon Scout at Cowal has successfully reduced operator exposure to slurry containing hazardous materials including cyanide and improved sample authenticity by collecting a more representative and repeatable sample, Gekko said in the case study.

The other critical success achieved by the Carbon Scout is its ability to take a larger CIL tank sample that is more representative. This is achieved by the Carbon Scout drawing from deeper within the tank, where more superior slurry-carbon mixing occurs, and a larger sample of up to 20 litres is taken, which is 10-20 times the typical manual sample size. Additionally, the sample is extracted from a consistent point each time the Carbon Scout cycle samples from that tank.

Gekko concluded: “Optimising the Carbon Scout for site conditions allows for more accurate, reliable and repeatable measurement of the carbon inventory of the CIL circuit. Utilising these measurements and integrating with a plant’s SCADA system, the automatic control of carbon concentrations through the CIL circuit can be achieved. Automating data collection and process actions such as carbon transfer reduces operator risk exposure and man hours previously dedicated to the manual data collection tasks.

“The improvement derived from the utilisation of the Carbon Scout should lead to increases in circuit recovery by reducing soluble gold losses.”

The Carbon Scout was originally the brainchild of Curtin University’s Gold Processing team, led by Dr Teresa McGrath and Bill Staunton. Curtin University selected Gekko Systems as its commercialisation partner.

Staunton noted that “real-time data collection instrumentation and related analysis is essential to the future of the gold processing industry”.

Gekko Systems’ Technical Director, Sandy Gray, said: “The increasing installation base of the Carbon Scout globally is providing a fantastic baseline of evidence that supports the benefits of quality data collection and automation.”

Orica’s Chemicals business eyes new complementary opportunities

Orica’s Investor Day, taking place last week, highlighted potential growth areas in one of the company’s less-publicised ‘verticals’, its Chemicals business.

Mining, Quarry & Construction and Digital solutions often steal the headlines in quarterly updates, but Adam Hall, Group Executive & President of Asia & Chemicals, showed there is plenty going on within the company’s fourth vertical.

This business, which covers the fields of ore processing, chemical stabilisation and recovery & treatment, strengthens Orica’s presence across the mining value chain, having a strong alignment with its global footprint and understanding of customer needs, the company says. It also acts as a complementary component of Orica’s “new solutions offerings”.

Orica’s current exposure is to leaching agents and emulsifiers, with cyanide making up its biggest product today.

As one of the largest producers of sodium cyanide for mining, Orica delivers the leaching agent in briquette form in circa-1 tonne boxes that are easily containerised, or within an Orica-designed Sparge isotainer system, or in liquid form via purpose-built iso tanks suitable for safe road or rail transport around the world.

It relies on the Yarwun, Gladstone Cyanide Manufacturing Facility in Queensland for this supply, which has an annual capacity of 95,000 t/y and is compliant with ISO9002 and the International Cyanide Management Code. This facility is complemented by the company’s sodium cyanide transfer stations in Peru, Ghana and Malaysia.

Hall was positive about potential growth opportunities in the cyanide space, explaining demand for cyanide was expected to outpace the predicted growth in gold ore treated to 2026 as the complexities involved with treating orebodies continued to increase.

He said the Yarwun facility had great brownfield growth opportunities around the site, with the company evaluating potential expansions in the region of “high single digit” or “low double digit” percentages.

Hall was equally positive about cyanide retaining its presence in the gold leaching process, saying that, while substitution questions continued to come up, the realities associated with such a transition meant it was infrequently feasible.

“There is one major mine that has switched away from using cyanide into a different reagent,” he said. “That cost them north of $100 million, and our understanding is they would not necessarily do it again. Also, that specific mine has a certain lithography that lent itself to using that reagent.”

Hall said Orica’s emulsifiers – which allow it to differentiate its explosives products through maintaining the stability of the mixture – represented “a small but mighty part” of the company’s product suite. He saw potential growth opportunities for emulsifiers, which he said contained the “secret sauce for emulsification”.

Outside of these two Orica mainstays, Hall highlighted the potential for Orica to play in both flotation and solvent extraction markets as part of growth opportunities that added up to A$23 billion ($16 billion).

In flotation, collectors, frothers and flocculants are integral to optimising the process. The same can be said for solvent extractants in the SX space.

“We see all of these as potentially interesting for Orica,” Hall said. “These are all big fields…but each of them has something we could potentially partner or bring to our clients, and something we will be looking to do over the next five years or so.”

Partnerships could potentially see Orica team up with big chemical players that have a by-product or comparatively small value stream coming out of an integrated facility where Orica could bring its “deep understanding of what the miners need and how we can deliver against that using the products that are produced”, he explained.

This could see Orica act as an agent, an offtaker, or purchaser of the by-product production unit.

As with all other Orica verticals, the Chemicals business will be looking at any potential bolt-on to the emulsifier and cyanide offering as a way to influence more of the value chain, ensuring changes made up- or down-stream provide value throughout the full flowsheet.

Draslovka eyes base metal leaching prize with MPS glycine technology

Draslovka Holding made its presence felt in the mining chemicals space about a year ago when it announced plans to acquire Chemours Company’s Mining Solutions business, a deal that has since seen it become one of the largest North American producers of solid sodium cyanide.

This acquisition, completed in December for $521 million, also laid the groundwork for a separate transaction that could see the Czech Republic-based company diversify into the in-demand battery metals arena.

Australia-based Mining & Process Solutions (MPS) had been on the Mining Solutions business radar for at least two years prior to the Draslovka transaction, according to James Stockbridge, Director of Draslovka Mining Solutions. Stockbridge, formerly of Chemours and DuPont, said that his team at Draslovka realised MPS had something on its books that could solve many of the challenges the industry was experiencing and transform mining solutions by using an amino acid called glycine.

“For more than a decade now, the industry has recognised that orebodies are becoming lower grade, processing them is becoming more complex and the environmental regulations associated with leaching are becoming stricter,” Stockbridge told IM.

“It is the challenge of our time, and we think MPS has something quite unique to offer here.”

With roots in the gold technology group at the renowned Curtin University in Western Australia, MPS’ glycine leaching technology has the potential to change both the gold and base metal leaching space.

In gold, MPS’ GlyCat™ process was invented to reduce cyanide consumption while maintaining gold recovery for gold ores from deposits containing nuisance copper. GlyCat has been designed to enhance the dissolution of gold and copper in gold/copper ores where glycine is used as a catalyst with cyanide in a cyanide-starved leaching environment. It doesn’t replace cyanide, but, in fact, enhances its leaching capabilities by dealing with the high-cyanide consuming copper within these gold-copper orebodies.

In copper, nickel, cobalt and zinc leaching, GlyLeach™ is able to leach the targeted metals with enhanced selectivity compared with conventional methods. It will solubilise copper, nickel, cobalt and zinc, while gangue minerals such as iron, manganese, silicates and carbonates remain in the leach residue, MPS says.

Both technologies are environmentally safe, work effectively at alkaline pHs and ambient temperatures (with no heating cost or pressure vessels) and come with low operating costs due to their low consumption and recovery/recycling traits, according to the company.

While it is the gold side of glycine leaching testing that has, so far, taken the headlines thanks to several trials with mining companies in Australia (including Evolution Mining) and the technology’s potential ability to partially replace cyanide in the leaching process, Stockbridge and his colleague Jackson Briggs (Corporate Development Manager for Draslovka) said Draslovka was most excited about what the technology could offer the base metal space.

Briggs said: “It gives us the opportunity to expand our leadership position in gold leaching agents into base metals. At the same time, it also allows us to incorporate our expertise in that chemistry and chemical manufacturing side of things.”

Stockbridge – not wanting to give away too much – hinted at how this latter opportunity could play out.

“The leaching technology will also influence the way you, for instance, operate, monitor and control the plant,” he said. “This process will be different, and we will be bringing in new technologies to cater to this.”

Considering Draslovka can produce glycine from its existing hydrogen cyanide production footprint, there is potential for a very smooth integration on the supply chain side of things.

Asked to quantify some of the benefits of the technology, Stockbridge was happy to point out GlyLeach’s potential to “simplify the flowsheet” for, say, nickel production, removing the smelting aspect and resultant ore transportation – providing capital and carbon footprint benefits.

Briggs added: “It can change a lot from ore-to-ore with GlyLeach, but, in a really strong business case, you are looking at a 25% reduction in processing costs.”

This is on top of a 10-35% improvement on the recovery side, compared with conventional leaching, Stockbridge said, citing “proof of concept” studies.

As for GlyCat, the sweet spot – as already hinted at – is in gold-copper orebodies where copper is a large cyanide consumer, with the technology allowing cyanide to work more efficiently and effectively.

Both technologies recently featured in OZ Minerals Ingenious Extraction Innovator challenge outcomes publication, while GlyCat has also been the subject of a one-off study looking at combining it with Sixth Wave Innovations’ IXOS® molecular imprinted polymer for gold extraction.

Australia’s Future Battery Industry Cooperative Research Centre, which is sponsored by the likes of Sandfire Resources, Barrick Gold, Coda Minerals (previously Gindalbie Metals) and Poseidon Nickel, is also coordinating some of the work towards commercialising GlyLeach.

There is a strong business case for both technologies first being deployed at scale on tailings deposits that have been deemed to have no associated value – a point both Stockbridge and Briggs acknowledged.

Briggs said: “In terms of accelerating the development of the technologies, there are tailings deposits and waste piles situated all over the globe with high amounts of precious and base metals that have not been extracted due to the limitations and economies associated with current processing technology. We could provide an economic way of extracting those.

“It would also provide us a project with much reduced start-up times compared with, say, a greenfield project.”

Stockbridge added: “We have carried out some work on this type of application before and believe there is the potential to extract 50% of the nickel that they couldn’t access with existing technology by using GlyLeach.”

From the mining company perspective, deploying a new technology on material already written off comes with a lot less risk too.

That is before appreciating that the material won’t have to be smelted on site, that the process produces no free cyanide and that gangue materials do not come out in solution.

It is no wonder the Draslovka duo are excited about the technology’s potential; GlyLeach in particular.

“The ability to help nickel and copper miners produce more metal to rescue some of these deposits that have been forgotten or under-developed because of technology limitations and be able to do so in a way that is more environmentally friendly is exciting.

“Potentially, this technology could help localise more electric vehicle supply chains by removing the need for smelting and providing a cost-effective and environmentally friendly means of extracting metals.

“We cannot wait to get started.”

Gold industry ready to take action on cyanide use, DST’s Lemieux says

The move away from cyanide in gold processing has been talked of for many years, with words often not followed by actions, yet David Lemieux, President and CEO of Dundee Sustainable Technologies (DST), believes the industry is now starting to get serious about assessing alternative lixiviants.

His assertion comes on the back of one of the biggest gold miners in the world recently making such a move with the help of DST.

Back in December, Newmont signed a Technology Transfer Licensing Agreement with DST to use its cyanide-free gold extraction technology, known as the CLEVR Process™.

The CLEVR Process 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. With fast leach kinetics of 1-2 hours, the ability to treat refractory ores and handle base metals, plus a competitive capital/operating expense, the solution has been gaining prominence in the gold market.

Having tested the process out on a variety of ores from various sources, DST is now in the commercialisation phase with CLEVR.

The pact with Newmont follows a successful test work program in the March quarter of this year, after which the gold miner expressed its interest in the execution of such an agreement. This led to Newmont conducting laboratory CLEVR leaching tests in its technical facilities in Englewood, Colorado.

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

  • A two-year, non-exclusive licence for the use 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.

Lemieux said the agreement should be viewed as an indication the gold industry is serious about assessing alternative processing approaches.

“DST’s CLEVR Process is a mature and developed novel gold processing technology that allows majors to properly assess how it can be implemented within a given project in terms of environmental benefits, operational efficiency, and operating and capital costs,” he told IM. “Such a level of detail then allows for properly integrated decision making.”

He said there had been increased interest over the years from the industry with regards to alternative processing approaches, which is likely to continue as more jurisdictions target cyanide operations and pressure operators to reduce their dependency on the lixiviant as the main and sole gold recovery mean.

CLEVR is one of two “novel metallurgical processes” DST has in its portfolio, the other being its GlassLock Process™.

GlassLock is a patented process for the sequestration and stabilisation of the arsenic often associated with copper, gold, silver or polymetallic deposits.

Dundee Sustainable Technologies GlassLock industrial demonstration plant on site at an operating copper smelter

In DST’s approach, the arsenic is incorporated into a highly stable and insoluble glass form that can contain up to 20% arsenic, while meeting or exceeding the requirements of the USA EPA’s toxicity characterisation leaching procedure and the Synthetic Precipitation Leaching Procedure, the company said.

Also in the commercialisation phase, GlassLock has been operating at an industrial scale thanks to a demonstration facility built and operated by DST.

According to Lemieux, the increased number of complex orebodies currently being developed means there is likely to be more interest in both CLEVR and GlassLock.

“The chemistry and conditions of the CLEVR process can allow for improved gold recoveries,” he said. “This, combined with DST’s ability to efficiently and permanently stabilise arsenic using GlassLock, is providing good opportunities for DST.”

The Glasslock process, he said, is equally targeting existing operations that have immediate arsenic production and stabilisation needs as well as operations/miners required to address and stabilise legacy arsenical material as part of their permitting requirements.

These abilities were recently recognised by engineering firm Hatch, which entered into a Technology Framework Agreement with DST that could see GlassLock used in combination with Hatch’s fluid bed reactor and arsenic dry scrubbing technologies on gold and arsenopyrite projects.

The objective of the agreement was to “synergise” Hatch’s extensive client base, commercialisation and marketing expertise, fluid bed reactor and arsenic dry scrubbing technologies, and large-scale equipment engineering, supply, procurement, and life cycle services capabilities with DST’s innovative technology to identify and develop potential gold and arsenopyrite projects using GlassLock, the companies said.

While they cannot point to specific results of these two technologies complementing each other, Lemieux said DST has continued and is currently working on testing programs where the roasting and vitrification approach is applied on complex gold concentrates.

“These programs were generated and originate from DST’s own development efforts, but we hope to see more similar opportunities coming from Hatch in the future,” he said.

Lemieux concluded: “Implementing novel metallurgical processes within the industry takes time and DST has progressed greatly, and continues to do so, on the design and operating parameters of specific on-site implementations of GlassLock and/or CLEVR facilities.”

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.”

CyanoGuard set for South America cyanide monitoring pilots

CyanoGuard says it is rapidly expanding its customer base in the Americas following widespread customer success with its ground-breaking cyanide monitoring solution.

With active or upcoming pilots in Brazil, Colombia, Mexico, and Peru – some of the leading gold-producing countries, CyanoGuard is closing in on its mission to minimise cyanide consumption and operational costs and improve precious metal recoveries for gold mines, it said.

Andres Pereira, Senior Engineer from NALCO Water, which is overseeing the implementation and daily usage of the CyanoGuard cyanide monitoring solution at a gold mining operation in the Antioquia region of Colombia, said: “The protocol, the procedure, and the equipment are everything we expected. We are so happy with CyanoGuard’s technology since it will make our lives easier. It also minimises our exposure to chemicals which is also very valuable to us.”

Margarita Zvezda, Head of Sales at CyanoGuard, added: “We are very excited to learn that senior industry experts like Andres recognise the substantial value our solutions add to their application in gold mining. Our goal is to support more miners in the Americas in their efforts to optimise production processes, minimise costs and carry out responsible business practices.

“We are pleased to see that gold miners in the region are enthusiastic about introducing innovative technologies to improve their performance. We believe that this factor will be largely decisive in determining the future competitive positions of players in the gold market.”

This news comes in the wake of many recent initiatives and accomplishments of the company, including expanded concentration ranges now available to cover the entire spectrum from 0.1 to 4,000 parts per million of free cyanide; and successful CE-Certification of the latest CyanoSmart Cyanide analyser.

Hycroft Mining continues evaluation of novel sulphide heap oxidation/leach process

After testing out a “novel” oxidation and leaching process at the Hycroft Mine in Nevada, USA, Hycroft Mining Holding Corp is making plans to go back to a conventional oxide leaching setup in 2021.

The company produced 27,392 oz of gold and 178,836 oz of silver in 2020, an almost three-fold increase over 2019. It hit these numbers while operating at a pre-commercial scale using the novel process, which oxidises sulphides ahead of leaching.

It is now planning for run-of-mine production of 45,000-55,000 oz of gold and 400,000-450,000 oz of silver in 2021 using conventional cyanide heap leach.

It is anticipated that mining in the first four months of 2021 will be performed using the existing Hycroft fleet and a rental fleet, moving approximately 1.5 Mt/mth of ore and waste. For the remainder of the year, Hycroft intends to mine some 500,000 t of oxide and transitional ore and waste per month with a more cost-effective mining fleet.

Diane R Garrett, President & Chief Executive Officer, reflected on the results: “2020 was an important year for Hycroft as the company continued to focus on the restart of the Hycroft Mine. Throughout the year, we advanced work on the proprietary two-stage sulphide heap oxidation and leach process and made several important findings that will need to be addressed prior to our implementing the novel technology on a commercial scale.

“In 2021, we expect to mine predominantly oxide and transition material, which are more economic when treated using a conventional run-of-mine heap leaching method, which gives us the opportunity to continue to refine the operating parameters and flowsheet for the new heap leach pad and novel process. While the company continued to make significant progress in better understanding this proprietary process and its application on a commercial scale, the past year also presented some operational challenges, including learning to navigate in a newly emerged COVID-19 world.”

In the last few months, Hycroft says it has worked alongside consultants to identify and investigate opportunities for improvements in operating parameters for the two-stage sulphide heap oxidisation and leach process. The result of the work to date has identified several items that were not considered or included in the original plan and design but are critical to the success of this process. These findings include:

  • Adding a forced air injection system for the leach pad which is a key component of the oxidation process;
  • Developing a system for segregating solution flows to and from the heap leach pad to avoid co-mingling of solutions among heap lifts and ore processing stages that negatively impact recoveries and conditions on the leach pads;
  • Identifying that the finer crushed material requires agglomeration in order to achieve optimal permeability and gold/silver recoveries;
  • Understanding that higher soda ash, caustic soda, and cyanide consumption will be required which Hycroft experienced throughout the 2020 pre-commercial test pad programs and recently confirmed through the review of the test work;
  • Determining that some transitional ores are more economically attractive when processed as direct leach, run-of-mine material; and
  • Concluding that additional variability metallurgical and mineralogy studies will be required to better understand each of the geometallurgical domains in the orebody. While there was some variability work completed in the past, the recent test work has revealed that additional variability test work and compositing is necessary to fully understand the geometallurgy of each domain, and that additional sampling, including sampling below the water table where the predominance of the sulphide resources exist, is required given the complexity and variability of the large orebody.

The additional variability test work will also include detailed mineralogy studies as it is important to understand the role other minerals may play in the overall oxidation process and to enhance Hycroft’s ability to measure oxidation rates accurately and consistently, it said.

The team at Hycroft has developed an approximate $10 million program for drilling and additional metallurgical and mineralogical studies in 2021. This program of work has been approved by the Board of Directors of Hycroft and can be funded from existing cash and Hycroft’s current operating plans.

Hycroft expects to mine and stockpile at least 300,000 tons (272,155 t) of sulphide ore in 2021 that, once sufficient additional work on the novel process has been completed, will be available for testing to further refine operating parameters and measure its performance for large scale application of the oxidation heap leach.

Garrett added: “2021 is a foundational year designed to advance the work necessary in preparation for larger-scale sulphide operations. The team is working diligently to optimise current and future heap leach mine plans and to evaluate all opportunities for more profitable mine plans in the near and medium term. This work involves taking a ‘ground up’ approach working from the orebody out. The company’s prior plan was developed using a $1,200/oz gold price pit shell which leaves profitable ore behind in the current gold and silver price environment. By running pit shells at recent gold and silver prices, we have identified additional areas of oxide mineralisation that can generate cash flows over the next several years and we have already begun to identify areas of higher-grade mineralisation that will become important for mine sequencing and further improving cash flows prior to accessing sulphide material.”

As the company considers life-of-mine development and planning for the Hycroft deposit, particularly in the current gold and silver price environment, Hycroft says it is prudent to evaluate proven processing technologies for treating some ore types that may be more profitable than only using the two-stage sulphide heap oxidation and leaching process.

Potential opportunities being examined by the company in 2021 include: developing an understanding of the grade range distribution of the sulphide material; completing on-going work on the higher-grade areas of Hycroft; and following up on historical high-grade intercepts.

In order to capitalise on these potential opportunities, which take advantage of the current commodity price environment, Hycroft believes that it should also evaluate the benefits of a multi-process operation. Long-term operating scenarios may include conventional run-of-mine cyanide heap leaching for the oxide and transitional material, sulphide heap oxidation and leaching using the novel process, and an appropriately sized milling and flotation plant for processing the higher-grade ranges of sulphide material.

“The company believes that the plan it has put in place for 2021 will provide the new team the time to fully consider and evaluate these opportunities and make any necessary changes to improve the leach pads, process plants and process flowsheet, maintain and develop its workforce, and advance the project, in order to further enhance the value of the project,” it said. “As the test work advances and alternative processes are considered, the company expects to perform technical studies and trade-off evaluations which may result in an updated feasibility study.”

BQE Water achieves several firsts with Zhongkuang SART plant operation

BQE Water says it has advanced the SART plant it designed for a gold metallurgical facility owned by Shandong Zhongkuang Group Co Ltd, in China, to full production.

Located in the Shandong Province in eastern China, the plant is now being operated under the ongoing technical supervision of BQE Water.

Implementing SART (sulphidisation, acidification, recycling and thickening) at the site improves both the environmental performance and project economics of the metallurgical facility, BQE said. Specifically, the SART plant eliminates the need for cyanide destruction, recovers copper and zinc as separate sulphide concentrates, and recycles free cyanide recovered by the plant to gold leaching.

BQE was awarded the SART plant contract back in 2019 following the positive outcome of an engineering feasibility study and on-site testing completed by BQE Water earlier in the year.

The Zhongkuang SART plant also represents many firsts, according to BQE:

  • It is the first application of SART globally where the cyanide competing base metals, copper and zinc, are recovered simultaneously from the leach solution as two separate high-grade concentrates that can be sold to generate incremental revenues;
  • It is the first commercial scale application of SART in China;
  • It is the first SART plant where lime is used to control gas emissions to reduce operating costs and control the build-up of salts in the process water; and
  • It is the first SART plant to be integrated into a complex metallurgical flowsheet that combines mineral flotation with cyanidation and SART in a Zero Liquid Discharge metallurgical facility with complete water recycle.

Songlin Ye, Vice President for Asia at BQE Water, said: “We are very proud of our China-based operations team for this significant achievement and that they were able to do so considering the challenges associated with the COVID-19 pandemic. The Zhongkuang SART plant is our flagship project for the China gold sector and other gold producers in the country are taking notice.”

David Kratochvil, President & CEO of BQE Water, added: “The many firsts associated with the Zhongkuang SART plant demonstrates our leadership in SART technology. And through the unique combination of engineering know-how and operations expertise, the project also shows our ability to reduce risks and achieve predictable outcomes for our clients.”

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.