IMS 2025 JV video: DST touts cyanide-free gold, arsenic-capturing glass

Dundee Sustainable Technologies: Innovative Metallurgical Processes for the Mining Industry

Key Concepts:

• Chlorination: A metallurgical process utilizing chlorine-based compounds for metal extraction, particularly effective for metals not amenable to traditional leaching or flotation.
• Vitrification (Glasslock Process): A method of permanently stabilizing hazardous waste, like arsenic, by encapsulating it within a glass matrix.
• Refractory Ores: Ores that are difficult to process using conventional methods due to mineralogical complexities (e.g., gold encapsulated within sulfide structures).
• Arsenopyrite: A sulfide mineral containing arsenic, often associated with gold and posing environmental challenges during processing.
• Tailings: The waste material left over after the valuable minerals have been extracted from ore.
• Cyanide & Arsenic: Common contaminants in mining operations, subject to increasing environmental scrutiny.
• Dore: A semi-pure alloy of gold and silver, often the product of initial gold extraction.

I. Company Overview & Historical Development

Dundee Sustainable Technologies (DST), based in Quebec, Canada, specializes in the development and commercialization of novel metallurgical processes for the mining industry. Founded approximately 15 years ago, the company’s origins lie in addressing the significant challenge of 400 million tons of asbestos tailings at the Tetford Mines, Quebec site. These tailings contain approximately 0.25% nickel, initially prompting DST to explore nickel recovery using a chlorination approach in 2006. However, a subsequent drop in nickel prices led to a strategic shift towards gold recovery, resulting in the development of the “Clever” process.

A pilot plant was constructed in 2008 and operated until 2011, followed by the establishment of an industrial demonstration plant in 2015 with a capacity of 5,000 tons per year of concentrate. This plant processed a wide range of refractory and complex materials, often containing gold encapsulated within sulfide structures, particularly arsenopyrite. The decomposition of arsenopyrite generated an arsenic byproduct, necessitating the development of the “Glasslock” process for its permanent stabilization through vitrification.

The Glasslock pilot plant was built in 2016, followed by an industrial demo plant in Namibia in 2018, focused on stabilizing arsenic trioxide from a copper smelter. More recently, in 2024, DST tested the Clever process on electronic waste, demonstrating its potential applicability beyond traditional mineral ores.

II. Core Technologies: Clever & Glasslock

A. Clever Gold Extraction Process:

DST’s Clever process utilizes a chlorination approach for gold recovery. Specifically, it employs a dilute solution (2-4%) of sodium hypochlorite (household bleach) with a catalytic amount of sodium hypobromide in an acidic pH environment. This rapidly solubilizes gold, leveraging the efficiency of bromide as a catalyst. The sodium hypochlorite is then regenerated using a membraneless electrolysis cell, reducing the stringency of brine control. DST emphasizes transparency in its process, stating it utilizes readily available equipment commonly found in the mining industry.

B. Glasslock Arsenic Vitrification Process:

The Glasslock process addresses the challenge of arsenic stabilization. Arsenic is known to volatilize at low temperatures, hindering traditional pyrometallurgical approaches. DST’s innovation lies in forming a stable intermediate compound that can be incorporated into a glass structure at melting temperatures. The resulting glass is amorphous (non-crystalline), preventing the remobilization of arsenic. The process involves a pyrolysis step to remove arsenic from sulfide concentrates, stabilize it, and generate an arsenic-depleted metal concentrate.

III. Market Applications & Client Base

DST serves a diverse client base, ranging from junior exploration companies with early-stage projects to major mining corporations. They provide metallurgical testing and flow sheet development for projects with challenging ore compositions. The company’s services are particularly relevant for:

• Tailings Projects: Increasingly common due to the focus on resource recovery from waste materials.
• Refractory Ores: Ores requiring specialized processing due to mineralogical complexities.
• High-Arsenic Concentrates: Materials posing significant environmental and economic challenges due to arsenic content.

DST has worked on projects across the Americas and internationally, assisting companies in optimizing their processes and meeting environmental regulations.

IV. Strategic Drivers & Industry Trends

Jean Philipe Mai identifies several key drivers shaping DST’s strategy:

• High Gold Prices: Driving increased interest in tailings projects and low-grade deposits.
• Increasing Arsenic Content in Ores: As oxide deposits deplete and mining moves deeper, sulfide ores with higher arsenic concentrations are becoming more prevalent.
• Demand for Innovative Technologies: A growing need for alternatives to traditional processes like bio-oxidation and pressure oxidation, particularly for complex ores.
• Reshoring of Supply Chains & Green Metal Initiatives: Heightened focus on environmental sustainability and responsible sourcing of metals.

DST positions itself as a provider of efficient tools for the industry, focusing on reducing plant size, eliminating liquid effluent, and generating stable solid tailings. They emphasize that addressing environmental challenges is not merely a cost, but a strategic advantage.

V. Environmental Considerations & Future Outlook

DST highlights the significant costs associated with environmental remediation, citing the $4 billion budget for the Giant Mine arsenic remediation project in Canada as an example. They advocate for proactive arsenic management and offer solutions for both removing arsenic from concentrates and stabilizing it on-site.

The company is observing a trend towards stricter environmental regulations and a growing demand for technologies that can facilitate doré production within jurisdictional boundaries. DST’s technologies are designed to help mining companies meet these evolving environmental criteria and potentially benefit from emerging “green metal” premiums.

Notable Quote:

“There's a cost of not doing something. There's a cost of not dealing with your arsenic… efficiency is definitely driven or wanting to be positive in terms of a cost standpoint.” – Jean Philipe Mai, President & CEO, Dundee Sustainable Technologies.

Conclusion:

Dundee Sustainable Technologies offers innovative metallurgical solutions for the mining industry, specializing in gold extraction and arsenic stabilization. Their Clever and Glasslock processes provide efficient and environmentally responsible alternatives to traditional methods, addressing the growing challenges associated with complex ores and stringent environmental regulations. DST’s adaptable technology and diverse client base position them for continued growth in a rapidly evolving mining landscape.