CSIRO ingot

Clean Mining helps gold producers power green credentials with CSIRO tech

With environmental practices increasingly in focus, the mining industry is pushing to stay at the forefront of innovation in sustainable solutions, with a particular focus on technology.

Shareholders large and small are demanding accountability from companies, and this is especially true in the resources sector. Potential negative environmental effects on air, water, and land from poor mining practices are too great to ignore, and shareholders are holding miners to account now more than ever. For this reason, Australian miners are placing sustainability at the core of their business strategy.

Clean Mining’s innovative gold processing technology

Clean Mining, a part of the Clean Earth Technologies group, is radically transforming gold production worldwide with a new mineral processing technology that eliminates harmful cyanide and mercury in the gold recovery process.

The company’s revolutionary gold recovery agent is a cost-effective, non-toxic alternative to conventional gold processing methods, and is rapidly proving itself to be the mineral processing technology of the future.

CSIRO partnership

The award-winning, non-toxic solution was developed over more than a decade by the CSIRO, Australia’s national science agency. It is cyanide-free and mercury-free, and delivers a safer, more sustainable process without leaking, spillage, or exposure to hazardous chemicals.

After successful demonstration and field trials, the technology is now being brought to market through Clean Mining.

The solution replaces cyanide with a safe, alternative compound that incorporates the well-known reagent thiosulphate. The compound dissolves gold out of ores (the gold not recovered by gravity) at similar rates to conventional techniques. It’s safe and lowers environmental impacts.

The Clean Mining solution  builds on CSIRO’s previous work tailoring a niche cyanide-free solution to Barrick Gold’s Goldstrike Mine, specific to their ore, that’s successfully been in operation since 2014 and processing at scale of up to 13,000 tonnes per day.

Further to this, a refined solution, catering to a broad range of ores was tested on these varying ore types, in Menzies, Australia, in a demonstration plant at 30tph, proven and produced the first Clean Gold™ ingots and jewellery.

This proof of concept used a vat leach process and has since been enhanced to embrace agitated leach tank for fast leaching kinetics, resin for gold extraction and dewatering processes which produce a dry tailing negating the need for dams/ponds and remediation.

CSIRO Land & Water, a separate entity from CSIRO Minerals, has also completed an environmental risk assessment on the tailings from Menzies. The report and overview indicate the non-toxic nature of Clean Mining’s process combined with dry stackable tailings.

Patented process, optimal solution

Clean Mining’s patented process takes into account that each environment, mine, and ore sample will have unique characteristics.

The company’s solution begins with service, support, and a technical discussion in order to evaluate the environment and available assets. Clean Mining then carries out an extensive ore testing program that determines gold recovery, reagent consumption as well as leaching kinetics with recycled solution. This data helps carry out the optimal approach for gold extraction and yielded optimisation, leading into the design and flow aimed at producing a cleaner, more sustainable use of the resources, lessening environmental impact.

Sustainable, economic solution

Clean Mining’s processing solution is both environmentally and financially sustainable, while mitigating hazardous chemical risks. The elimination of toxic cyanide and mercury with a non-toxic gold recovery agent benefits both staff safety and the health of the environment.

The perfect partner for all sizes of miners

Clean Mining is a perfect technology partner for miners of all sizes, be it ASGM/small projects, mid-scale mining operations, or large-scale miners.

Rate of gold extraction – does it measure up?

The solution has a gold recovery rate comparable to cyanide, without the environmental downsides. To-date, Clean Mining has conducted over 50 tests globally, with a sample of results displayed below:

Gold Extraction Results

Ease of transition

The front-end milling circuit remains the same as a cyanide-based plant, which means the new technology applies only from the leaching to gold recovery phases. This makes the transition easier and more cost-effective. Clean Mining also utilises a de-watering process for reagent recycling/reuse and to produce dry stackable tailings so there is no need for hazardous tailings dams.

Works with a range of materials

The solution has been subject to intensive testing to understand its leaching performance in association with reagent recovery and recycle. Results indicated that it can be used on a range of ore types. The testing process uses traditional cyanide circuit analysis methods with results progressing to plant design and flow.

The method possesses demonstrable capabilities, tested in the field and at scale, for removing cyanide as the primary means of leaching gold in medium to large-scale mining operations. Recently, the same solution for removing cyanide was proven to fully replace mercury use in the artisanal and small-scale mining sector.

This alternative leaching solution is unique in its versatility and scalability – capable of being applied to a wide range of gold-bearing ores encountered by different operators. Non-toxic, non-flammable, and water soluble, the gold recovery agent’s success rate in leaching gold from certain ores (e.g. carbonaceous) is 50% more effective compared to cyanide.

Drive shareholder satisfaction with a Clean Gold™ certification

Clean Mining has established a Clean Gold™ trademark to certify all gold produced via Clean Mining technology. The leaf logo may be used by gold producers, providing shareholders and consumers with the knowledge that their gold choice is contributing to a cleaner planet and healthier communities.

Growing global interest

Following the launch of the solution in mid-2019, Clean Mining has been inundated with interest from across the world. This is mainly due to the certification, branding, and provenance already built into Clean Gold™, allowing gold producers to immediately benefit from the transparency, economic incentives and sustainability credentials that come with being part of a trusted Clean Solution.

Written By Jonathan Norris
Jonathan is a founder of Mining.com.au and has been covering the resources industry since 2018. With over 17 years experience in print, broadcast and online media, Jonathan has seen first hand the transformative effect of online niche media.