Tag Archives: gold leaching

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.”

Newlox heralds the potential of OAR gold leaching technology following test work

Newlox Gold Ventures Corp’s affiliate has reported what it says are “excellent results” from Stage 1 testing of the new Organic Aqua Regia (OAR) gold leaching technology on high-grade gold ore samples.

Newlox Research and Development Corp’s final analysis of the results from Stage 1 testing indicated not only is a gold recovery of 94.68% achieved at ambient temperature, but also a 100% recovery is achieved at 80°C.

The company is investigating the use of OAR technology as a non-toxic and water-free alternative to cyanidation to produce both gold and other precious metals. This will benefit Newlox Gold Ventures Corp’s ambition to recover residual precious metals and contaminants from historical tailings.

Newlox R&D is developing OAR in conjunction with the University of British Columbia in Canada and Chiba University in Japan to leach gold with this reagent, which is both non-toxic and widely used in other industries, according to the company. The main advantages include that it is non-toxic, is recyclable, extracts gold faster than cyanide, does not use water, and does not require carbon or electrowinning.

The company undertook Stage 1 testing on a high-grade gold ore grading an average of 48.87 g/t. The ore was ground in a BICO mill to reach a point where 80% of the material was below a grain size of 0.12 mm (P80 -0.12 mm) before leaching with OAR. Newlox’s research team used the Yates model in 16 experiments to investigate several combinations of reagent dosage and leaching time, it said.

Newlox R&D Corp undertook leaching tests in Vancouver, with the gold dissolution in the OAR calculated based on the gold grade in residues obtained after filtration. A third-party metallurgical laboratory (Global Mineral Resources) in Burnaby, British Columbia, was used to verify the results using aqua regia digestion and Atomic Absorption Spectroscopy (AAS).

The company explained: “The R&D team used the Yates testing protocol to modify various factors during testing and evaluate their effects and relevant interactions. The Yates protocol identified the most significant factors in overall gold recovery. Most encouragingly was the feature that all samples returning over 90% recovery during Stage 1 testing had reagent dosage commonalities, indicating a clear route forward for Stage 2 testing.”

Parallel testing was undertaken at the University of Chiba in Japan on the same ores tested by Newlox R&D in Vancouver. The Japan-based team experimented with alternative reagent additives and different leaching temperatures and found significant effects based on those factors.

Leaching tests undertaken in Japan at 80°C achieved 100% gold recovery in four hours, followed by precipitation of the dissolved gold by adjusting the solution’s pH. The pH control enabled pure gold recovery while concurrently suppressing the precipitation of other elements in the precipitate.

“This promising result indicates that gold may be recovered from the solution without the need for electrowinning,” the company said.

Stage 2 testing is now underway to both reproduce the results seen in Stage 1 testing and further investigate the effect of reagent dosage, time, and temperature on leaching mechanics. Additionally, the R&D team is focused on testing both the recyclability of the OAR reagent, and methods for recovering gold from the solution.

Ryan Jackson, President & CEO of Newlox, said: “We are most encouraged to report that the first round of testing achieved up to 100% gold recovery, using the cutting-edge OAR leaching technology. This initial round of testing forms part of the Newlox R&D 12-month OAR development program.

“We are gratified to realise such early positive results. OAR leaching promises to become a paradigm-shifting technology applicable not only to the $180 billion formal global gold mining industry but also as a method to bring the $27 billion informal gold mining industry into the 21st century.”

Sixth Wave and MPS team up to cut cyanide usage, costs in gold processing

Sixth Wave Innovations says it is working with Australia-based Mining and Process Solutions (MPS) on test work initiatives in North America and Australia integrating Sixth Wave’s commercially available IXOS® molecular imprinted polymer for gold extraction with the MPS GlyCat™ process.

The GlyCat process was invented to reduce cyanide consumption while maintaining gold recovery for gold ores from deposits containing nuisance copper. For gold applications, the IXOS platform, meanwhile, is capable of selectively targeting gold while rejecting contaminants such as copper, mercury, and other non-target elements potentially contained in a gold-bearing cyanide leach solution.

The two companies are also working in collaboration with the Centre Technologique des Résidus Industriels (CTRI) and a top 10 gold producer in Canada. This project aims to develop an environmentally-friendly flowsheet for the gold mining industry, examining MPS’ acidic and alkaline leaching technologies, together with Sixth Wave’s molecular imprinted IXOS resin technology for the extraction of gold from alternative lixiviants. Testing is to be undertaken on ores provided by the Canadian mining partner, Sixth Wave said.

A recent study published in the Hydrometallurgy Journal titled ‘Gold recovery from cyanide-starved glycine solutions (Glycat) in the presence of Cu using molecularly imprinted polymer IXOS-AuC’ found that “gold recovery increased, while copper recovery decreased with the increasing gold concentration”, Sixth Wave said. The adsorption behaviour of IXOS-AuC had “the best selectivity compared to three other gold selective resins”, the study added. Other outcomes from the study showed the IXOS-AuC polymer was very robust, allowing reuse without deterioration of the polymer physically (assessed by scanning electron microscopy) or in performance.

“Our collaboration with MPS is an important initiative for Sixth Wave and our IXOS high performance gold extraction products,” Dr Jon Gluckman, President & CEO of Sixth Wave, said. “The industry is keenly interested in new and innovative approaches to leach and recover gold as a replacement, in whole or in part, for conventional processes. In order to focus on lowering capital expenditure and operating expenditure, and to comply with environmental and regulatory constraints, Sixth Wave is extremely interested in leveraging our technology with the benefits of the MPS glycine leaching and recovery process.”

Ivor Bryan, Managing Director of MPS, said: “Our respective technological approaches can bring tremendous value to prospective customers by significantly cutting cyanide usage along with the associated costs and environmental impact.”

Earlier this week, Sixth Wave Innovations signed a non-binding Letter of Intent to trial its IXOS purification polymer at the Rio2 Ltd-owned Fenix gold project in Chile.