Tag Archives: gold processing

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

Environmental, Metallurgy, Mineral processing, Mining services, Precious metals, Sustainable mining, , , , ,

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

Base metals, Environmental, Mineral processing, Mining equipment, Mining services, Precious metals, Water management, , , , , , , , ,

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.

McLanahan and Mincore collaborate on gold processing plant upgrade

Environmental, Mine operation news, Mineral processing, Mining equipment, Mining services, Precious metals, Water management, , , , , , , ,

McLanahan recently helped process consultancy firm, Mincore, come up with a solution for managing the gold leach tailings at one of Australia’s oldest gold operations near Bendigo, Victoria.

With the gold processing plant recently undergoing a series of process upgrades, several technology partners were engaged by Mincore. McLanahan was one, with its 10M Elevated Thickener coming into play.

Richard Williams, McLanahan Global Product Manager, said: “Mincore and McLanahan have worked on a number of project studies previously. Having local engineering capability and support on both sides made the engagement much more efficient in being able to review process data and confirm the specific thickener operation and construction requirements.”

Williams said a local manufacture and relatively low overall delivered cost solution would be the best fit for the client. “Modular design provides the flexibility to manufacture in more locations and provides more certainty around time-sensitive projects,” he explained.

Due to the nature of the processing plant, Mincore specified material and design aspects to account for the highly acidic and corrosive process streams, according to McLanahan. A specific sealant was procured for the thickener flanges to perform at the correct duty, as well as stringent paint quality assurance including DFT, WFT, pinhole and holiday testing specified by Mincore to confirm coating integrity.

The thickener was designed in-house at McLanahan’s New South Wales location and included several process instruments, including bed pressure, bed level, rake torque and overflow clarity. The tank, support structures and bridge were all manufactured locally for a faster delivery time, taking only 14 weeks for final delivery to the customer’s site, according to the company.

Mincore’s site team was able to support installation by using four experienced technicians and one small mobile crane to place the thickener onto a prepared concrete-bunded hardstand. The modular nature of the tank and bridge allowed for safe, fast and efficient site installation, McLanahan remarked.

Dry commissioning includes checking for correct tank assembly, along with the installation and application of protective treatments, the company said. “During this time, the drive and instrumentation are wired, and the mechanism is checked for correct alignment.”

Once successfully completed, a wet commissioning will be conducted, where the feed to the thickener is introduced and the process outcomes are evaluated for consistency. The process will ensure the instrumentation is operating correctly, and that the data received, and process outcomes, meet the design requirements and overall client specifications.

For this thickener, McLanahan’s customised approach included minimising the number of different fastener sizes and increasing assembly speed by minimising tooling and guesswork on site.
Additionally, McLanahan designed in the following aspects:

  • Integrated lifting attachment points preventing damage to paint and eliminating the need for the customer to source specialised lifting equipment;
  • A completely match-marked assembly system using large weld metal as marking to increase assembly speed;
  • Integrated electrical cable trays and conduits that reduce site work and damage to paint coating;
  • Local marshalling panel readout of all instruments complete with trending and status providing operator feedback in real time without needing to return to the control room;
  • Maximised space and clearance under the tank, facilitating pump and instrument access and maintenance; and
  • Integrated product sampling points at multiple locations around the tank to confirm process outcomes.

CyanoGuard receives EU, investor backing for next gen cyanide monitoring solution

Environmental, IoT, Mineral processing, Mining services, Mining software, Precious metals, , , , , , , ,

Switzerland-based chemtech startup CyanoGuard has completed a fundraising and been awarded a non-dilutive SME Instrument grant by the European Union’s Horizon 2020 program that, it says, will speed up market penetration and develop further applications for its next generation cyanide monitoring solutions.

Established in 2016, CyanoGuard has since developed and commercialised its solutions for gold mining operations, food safety testing and healthcare.

Co-Founders Benedikt Kirchgässler (CEO) and Mathias Cherbuin (CTO) transformed a chemical technology for rapid toxin detection from the labs of the University of Zurich into a “comprehensive digital solution package” that has found its first commercial application in the gold mining industry.

The company has now raised more than CHF3 million ($3.12 million) to help further develop the technology, which CyanoGuard says can minimise cyanide consumption by 12% while maximising extraction efficiency through real-time, instaneous measurement results.

Kirchgässler said: “These funds enable us to scale our ground-breaking monitoring solutions and roll them out to gold mines around the world.

“I am excited about the positive impact that our digital, artificial intelligence-based technology has on the global gold mining industry as well as the local communities and the environment.

“I believe that we will benefit from both the experience of leading venture funds…as well as the support of the European Union to speed up market penetration and develop further applications for our technology.”

With the newly raised capital from this seed round, CyanoGuard plans to accelerate its go-to-market strategy in the global mining industry.

Alex Stöckl, Founding Partner at Wingman Ventures, who has joined CyanoGuard’s Board of Directors following the funding round, added: “With its current offering, CyanoGuard has a unique value proposition for its mining clients that is beyond improved cyanide testing. This encompasses an efficiency-enhancing digitisation of process control and a more sustainable usage of cyanide in mining operations.

“We are convinced that Benedikt, Mathias and their team will drive CyanoGuard to become a globally leading provider of digital mining solutions.”

The freshly obtained funds are also intended to further expedite the development of CyanoGuard’s product offering for food safety and healthcare applications, the company said.

Outotec addresses carbon losses in CIP, CIL gold circuits

Automation, Metallurgy, Mineral processing, Mining equipment, Mining services, Precious metals, , , , , ,

Outotec has released a fully automated in-situ measurement system that, it says, can minimise gold solution losses in carbon-in-pulp (CIP) and carbon-in-leach (CIL) circuits.

Outotec CarbonSense is a system that is directly immersed in the slurry, eliminating the need for sample transfer and ensuring optimal carbon management, according to the company. It is designed to operate continuously in the agitated area of the reactor to ensure a highly representative analysis. It also features a reference probe to ensure reliable measurement even in changing process conditions.

As part of the solution, a single connection cabinet can support up to eight measurement assemblies, along with fibre-optic and copper media connections to the plant network, according to Outotec. “The system supports virtually any network topology, including star and ring configurations,” it said. “Maintenance is simplified with all power supplies and fuses located in one place.”

The portable calibration unit uses authentic slurry and carbon to ensure the best possible results and reliable measurement performance, Outotec said. No recalibration is needed when slurry properties change since the measurement is based on the difference between the measurement probe and the reference probe.

Continuous and reliable carbon concentration measurements minimise gold losses by enabling accurate control over carbon transfer between reactors, according to Outotec, with the Outotec ACT Carbon Management application designed to take full advantage of the measurement data.

The system is delivered as a ready-to-install package including measurement assemblies, connection cabinets and analysis software and licences.

The key benefits of Outotec CarbonSense, according to the company, are:

  • Enables continuous, representative, and reliable carbon measurement;
  • Supports development of efficient strategies for advanced CIP/CIL control;
  • Fully automatic operation;
  • Simple to install, operate, and maintain with no moving parts or sample transfer; and
  • Increases safety by helping to avoid blockages and other sampling issues.

EnviroLeach test results bode well for gold market take-up

Environmental, Mineral processing, Precious metals, , , ,

EnviroLeach Technologies has announced the successful completion of what it says is a comprehensive lab and bulk sample program using its patented cyanide-free formula on high-grade gravity table tailings material from a mid-tier gold producer.

Estimated gold recoveries from the bulk sample (2.7 t of material) averaged 97% and produced 277.8 oz of gold using the EnviroLeach process, which can effectively dissolve gold into aqueous solution with similar leach kinetics and economics to that of cyanide but is sustainable, safe and environmentally friendly, according to the company.

Following extensive lab and bench scale test programs, a locked cycle, bulk test program (leaching, filtering and electrowinning) was carried out on this 2.7 t bulk sample of table tails from the gold mining operation. The objective of the bulk test program was to determine the efficacy and recovery rates of gold from the host material using EnviroLeach’s proprietary formula and to collect key operational data such as leach kinetics, chemical reusability, reagent consumption and costs, the company said. The bulk test produced no tailings effluent, as all filtrate/liquids were reused in the process.

The test results report an overall average estimated gold recovery of 97% and three gold bars were produced having a combined gold content of 277.8 oz.

Duane Nelson, EnviroLeach CEO, said: “This successful bulk test on these high-grade gravity tails clearly validates the proficiency of our patented formula to offer a cost-effective, sustainable and environmentally friendly extraction alternative to the gold mining sector.

“Thousands of gold mines around the world rely on gravity-based concentration. This bulk test demonstrates that many of these mine operations could benefit from our eco-friendly extraction alternative.

“The adoption of the EnviroLeach process could reduce the industry’s reliance on the conventional cyanide and smelting methods used today and contribute to environmental sustainability across the gold mining sector.”

EnviroLeach cyanide-free tech to be tested on Golden Predator’s 3 Aces gold

Environmental, Metallurgy, Mineral processing, Mineral project development, Precious metals, Water management, , , ,

EnviroLeach Technologies and Golden Predator Mining have entered into an agreement that will see EnviroLeach’s proprietary cyanide-free hydrometallurgical technology extract gold from gravity concentrate produced at Golden Predator’s 3 Aces project in the Yukon of Canada.

This working relationship provides both companies with the first on-site bulk test of EnviroLeach’s new cyanide-free technology, they said.

Initial laboratory, pilot scale and production scale testing was successfully conducted at EnviroLeach’s facility in Surrey, British Columbia, prior to on-site testing at Golden Predator’s processing plant in the Yukon. All tests were conducted under the supervision of EnviroLeach and Golden Predator personnel with results to be released shortly, they said.

The initial 5 t bulk test will be conducted in phases and completed at the plant, they added.

Golden Predator operates the plant for the purposes of bulk sample testing of gold concentrate from its 3 Aces project. As part of its processing plant, Golden Predator developed a mobile batch recovery unit (Secondary Recovery Unit or SRU™) for the recovery of gold from its sulphide concentrate. Golden Predator intends to use the EnviroLeach proprietary cyanide-free technology in the SRU, it said.

Duane Nelson, President and Chief Executive Officer of EnviroLeach, said: “The gold recovery from Golden Predator’s arsenopyrite concentrate confirms the ability of our new eco-friendly formula to extract gold into solution from sulphide ores and recover it using conventional technologies.

“EnviroLeach is the only commercial-scale, economically viable and safe hydrometallurgical gold extraction process in the world. Our unique and eco-friendly process will change the way the world produces and recycles gold.”

Janet Lee-Sheriff, Chief Executive Officer of Golden Predator, added: “The plant and SRU are examples of the continuing ways that Golden Predator works to be innovative, testing new methods that have the ability to change how we operate at projects like 3 Aces.

“Working with EnviroLeach provides us a unique opportunity to lead the way for safe and responsible new cyanide-free extraction methods in processing gold bearing concentrates.”

The EnviroLeach process can effectively dissolve gold into aqueous solution with similar leach kinetics and economics to that of cyanide but is sustainable, safe and environmentally friendly, according to the company. This water-based process has a broad applicability spectrum and is effective on most gold ores and concentrates, the company said, potentially unlocking the value of many deposits located in environmentally sensitive areas that cannot be developed using current extraction methods.

Golden Predator’s test processing plant (pictured), the first of its kind in Yukon, Canada, commenced operations in 2016 providing increased metallurgical and geological understanding of its 3 Aces project. The plant is a relatively simple gravity circuit using a closed-circuit water system with no added chemicals due to the free-milling nature of 3 Aces gold.

The 50 t/d closed circuit plant recovers gold from #1 concentrates realising over 85% recovery of contained gold with doré bars sent to a commercial refinery for final processing. Golden Predator is currently testing EnviroLeach’s patent pending technology in it’s SRU for the extraction of gold from their #2 concentrates.

The 3 Aces Project is an orogenic gold project in southeast Yukon which provides the testing material for the processing plant. Golden Predator has to date focused exploration on a broad gold-in-soil anomaly, where numerous orogenic gold-bearing quartz veins have been discovered.

Golden Predator made an early decision to bulk sample at its 3 Aces project when it realised that much of the gold contained in its veins is high grade (not uncommonly over 30 g/t gold) and nuggety. The best way to determine the true gold value of a nuggety gold system is to conduct large scale bulk sampling which also allows Golden Predator the opportunity and ability to conduct on-site bulk metallurgical and processing tests.

Novo looks to scrap metal industry for Egina gold nugget separation options

Comminution of minerals, Environmental, Mineral exploration, Mineral processing, Mining project news, Precious metals, Water management, , , , , , , , , ,

Novo Resources says it has completed encouraging processing trials on gravels extracted from its joint venture Egina gold project, in the Pilbara of Western Australia, at Steinert’s testing facility in Cologne, Germany.

Phase one of the company’s joint venture with Sumitomo Corp at the Egina gold project centres around gaining a better understanding of geology (grade, continuity, controls, gold particle size distribution, gold location within gravels, gold genesis, etc.) but also involves high level desktop studies and trials to develop potential future processing and mining methodologies.

Preliminary tests of eddy current separator (ECS) technology indicate promising potential to directly extract gold nuggets from gravel, the company said. This is one of several dry processing methodologies being considered by Novo for gold recovery at the project.

Tests conducted on a spectrum of nugget sizes ranging from 1-10 mm demonstrated consistently high gold nugget recovery via ECS technology. Nuggets that underwent testing were recently extracted from gravels at Egina, the company said.

ECSs are predominantly used to recover select metals in the scrap metal industry. Material is fed onto a conveyor, the head pulley of which contains an adjustable high-powered magnet spinning at very high rotation rates, 4,000 rpm in Novo’s tests, independent of the speed of the conveyor, Novo said. This spinning magnet induces an alternating magnetic field that differentially repels non-magnetic metals such as gold.

This magnetic repulsion causes gold nuggets to lift, or fling, off the end of the conveyor belt where they can be separated from waste material by a steel plate. These trials were designed to establish whether Egina gold nuggets react sufficiently to reliably be separated from waste material.

Novo said: “Gold at Egina predominantly occurs as free nuggets of which most are above 1 mm in size. This presents opportunity to explore innovative technologies, some used commercially in other applications such as ECS technology, to assess their efficacy for use at the Egina gold project.”

In addition to ECS technology, Novo conducted initial testing of Steinert mechanical sorting technology to detect small gold nuggets utilising an Argos EM electro-magnetic sensor, it said. Fine gold nuggets, around 1 mm, were consistently and readily detected indicating potential for direct mechanical sorting of gold nuggets, Novo said.

As a result, a combination of mechanical sorting and ECS technology is also being considered as a potentially viable means of dry processing at Egina, the company said.

Rob Humphryson, CEO and Director of Novo, said: “We are very encouraged by these initial laboratory test results utilising ECS technology. Our mantra when testing new technology and its application to our projects is to ‘test quickly and test cheaply’, and we now have in hand sufficient encouragement from these tests to consider ECS technology highly prospective for application in the field.”

The company said this preliminary testing shows ECS technology can play an important role at Egina, with potential application as a processing solution or an exploration tool, or both. “This technology generates significant inherent advantages: it requires no water, no chemicals, is of low capital cost and is readily mobile. It can also be employed along with other technologies and is scalable,” the company said.

Novo thinks field tests are warranted at larger scale to better understand recovery efficiencies, operating costs and throughput rates and the Company plans further work with Steinert to study schemes in which ECS machines, or ECS machines in combination with mechanical sorting technology, can achieve efficient recovery of gold nuggets at Egina.

The company concluded: “As Novo learns more about gold size particle and mass distribution of gold in Egina gravels, the company can then begin to estimate gold recovery.”

Dundee Sustainable Technologies makes CLEVR, GlassLock process progress with China

Base metals, Environmental, Metallurgy, Mineral processing, Mining services, Precious metals, Sustainable mining, , , , , , ,

Dundee Sustainable Technologies says it has received a mandate from a Chinese customer to continue testing of the cyanide alternative CLEVR Process™.

The company has received a 30-kg sample of mineralised material from the customer and a payment for this work, DST said, explaining that the goal of the work is to demonstrate its proprietary CLEVR Process can extract gold at a rate of 95% or better.

Brian Howlett, President and CEO, said: “Management of DST is very excited to be developing our CLEVR Process technology into China at this time. China controls a key portion of the gold and base metals processing capacity in the world and will be a key market going forward for our technologies.”

DST, back in December, said it had completed analysis of the samples from this customer and had been able to increase recovery of the gold from the customer’s concentrate from 71% using cyanide to over 90% at a lab scale using its technology.

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

DST Management has also submitted a 5-kg sample of glass from its GlassLock Process™ to Chinese authorities for regulatory testing with the goal of classifying the glass as non-hazardous waste product suitable for disposal in the Chinese market.

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