Tag Archives: electrowinning

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.”

Metso Outotec books zinc plant order as it agrees sale of aluminium business

Metso Outotec has signed a contract to deliver a complete package of key process equipment for a greenfield zinc plant in the Chelyabinsk region in Russia.

The contract value of approximately €100 million ($122 million) has been booked in Metso Outotec’s Decemeber quarter order intake, a quarter of which will be booked in Minerals segment and the rest in Metals segment.

The order for the Verkhny Ufaley plant includes an equipment package for zinc concentrate processing, iron precipitation, solution purification and electrowinning (EW) technologies for safe and sustainable zinc processing based on OKTOP® reactor and plant products.

The order also contains a circuit heat recovery system, zinc EW and ingot casting equipment, as well as high-efficiency cooling towers for zinc EW and gypsum removal with drastically reduced emissions compared with conventionally-designed cooling towers, the company said. Clarifying solutions for consistent solid-liquid separation, high-performance Larox® FP and RB filters with low energy consumption, as well as fully integrated digital process automation for more reliable and flexible operation are also part of the order.

“Metso Outotec has been supplying minerals processing and metals refining technologies to our customers in Russia for a long time,” Jari Ålgars, President, Metals business area at Metso Outotec, said. “The new zinc plant will utilise Metso Outotec’s proprietary technology, which is both sustainable and highly cost effective.”

Stephan Kirsch, President of the Minerals business area at Metso Outotec, added: “Metso Outotec provides leading-edge technology for extensive zinc processing plants. This includes proprietary process equipment and know-how from raw material to final zinc product and various by-products.”

The technology to be delivered is the most cost-efficient technology available for zinc raw material processing, enabling efficient zinc and by-product recovery from a wide range of primary zinc raw material, according to Metso Outotec.

In a separate press release, Metso Outotec announced it had agreed to sell its Aluminium business to REEL International, headquartered in France. The business was put up for sale a year ago and has since been reported under the company’s discontinued operations.

The business to be divested comprises of green anode plants, anode rodshops, and casthouses used in aluminium smelters as well as related equipment and services. Approximately 120 Metso Outotec employees will join REEL upon closing, which is expected to take place during the March quarter of 2021, Metso Outotec said.

The parties have agreed not to disclose the value of the transaction.

Outotec improving energy consumption, efficiency at Glencore Nikkelverk refinery

Outotec has agreed with Glencore Nikkelverk AS on the delivery of coated titanium anodes to the new tankhouse for its copper electrowinning plant in Norway.

The delivery will include over 5,000 of the new mixed metal oxide coated titanium anodes, with the order value, booked into Outotec’s September quarter order intake, being some €10 million ($11 million).

Glencore’s Nikkleverk refinery in Kristiansand, Norway, produces around 40,000 t/y of copper.

Outotec’s coated titanium anodes were tested on-site for five years, with the results verifying that Outotec anodes will significantly reduce energy consumption and provide higher current efficiency than traditional lead anodes, the company said.

Outotec said: “Outotec Coated Titanium Anodes provide totally lead-free electrowinning operations and increased occupational health and safety by eliminating lead and lead sludge handling.”

The end result for Glencore Nikkelverk AS is green technology electrowinning operations with higher quality copper product at lower energy consumption and operating costs, it concluded.

Kalle Härkki, Head of Outotec’s Metals, Energy & Water business area, said: “This is one more reference delivery of Outotec Coated Titanium Anodes in the copper electrowinning industry. The energy efficiency benefits and lower operating costs of our anodes enable Glencore Nikkelverk to improve their profitability in a sustainable way.”