Sustainable leaching of gold made possible with new technology

The innovation company Chromafora is developing a method for leaching and separating gold from primary ore and electronic waste. The main difference from conventional cyanide leaching is that the direct danger to the working environment and the actual environment is reduced. In addition, the permit process is simplified with the new technology, which opens up for establishing new facilities.

- For us, waste streams are a potential source of sustainable resource recycling. Using our unique solution, we have been able to modify the technology so that we can leach gold from soils, slags, rock and even electronic waste. This means that we with an environmental friendly process can increase the recovery of the precious metal whether it is from waste or a mine , says Johan Seijmer, CEO of the innovation company Chromafora, where Ragn-Sells is one of the main owners.

Since the Corona pandemic outbreak, the price of gold has skyrocketed, due to increasing demand while production capacity is lagging. Every year, hundreds of thousands of tons of waste from e g households and electronics containing gold are generated. The gold in this waste is in most cases more readily available than mining gold from existing gold mines and it is significantly higher in concentration. So instead of depositing valuable resources, as is happening today in the form of landfilling, there is now a technology available that selectively extract valuable resources from waste including gold, while reducing the amount of waste.

Chromafora's technology, which is a modified method of thiosulphate leaching, has proven to be very effective in recovering gold from, for example, electronic waste and slag products. This by combining it with Chromafora’s patented Selmext technology.

- The key to creating a sustainable society is to reduce the extraction of virgin resources by reusing the raw materials that we already have taken out of the ground over and over again as much as we can and to use as gentle and efficient processes as possible for the necessary virgin extraction Therefore, it is gratifying to see that Chromafora's technology now can be used even for Gold, says Anders Kihl Director of Research & Development at Ragn-Sells and Chairman of Chromafora.

No longer expensive and complicated
So far thiosulphate leaching has been an expensive solution due to the rapid degradation of the thiosulfate, and separation stage of getting the gold has been considered very difficult. Chromafora is now in the process of solving this thanks to its expertise in selective chemical separation and membrane technology (Selmext technology). Chromafora’s combined method has optimized the extraction process so that the cost difference in relations to the conventional solution of cyanide is becoming secondary to other benefits.

Simplifies the permit process
Two main benefits of using thiosulfate instead of conventional cyanide are that the direct danger to humans and the environment is reduced. In addition, it may ease the permit process for new facilities such as mines and recycling plants. The general environmental and political trend is away from cyanide which make predictability to apply for and obtain a permit today for leaching gold with cyanide solutions, both difficult, costly and risky.

- We are working on a solution that is better for both the welfare of humans and the earth, and it has also shown to be cost-effective. Our ambition is that there should no longer be any incentives for using cyanide to produce gold when our method becomes commercial, says Johan Seijmer.

The project has received support within the strategic innovation program RE: Source, which is financed by Vinnova, the Swedish Energy Agency and Formas.

For more information, please contact:
Johan Seijmer, CEO Chromafora, +46 73 800 61 63, johan.seijmer@chromafora.com
Ragn-Sells Media Services, +46 70 927 24 00, medialinjen@ragnsells.com

Chromafora is an innovation company in chemical engineering where Ragn-Sells is one of the main owners. The company currently has two patented technologies for water purification, SELMEXT and SELPAXT. Both techniques involve detoxification and, with the help of selectivity, reduces the amount of waste. The processes also reduces’ the need for mining new raw materials, as several materials already extracted can be recovered from the waste and recirculated.

Facts: SELMEXT™ (Selective Metal Extraction)
A patented and tailored technology to handle waste streams containing dissolved heavy metals. The high selectivity also enables recycling of elements, for example REE (rare earth elements). Applications can be found e.g. within mining, industrial wastewater and landfill leachates.

With high selectivity and low chemical consumption, the amount of secondary waste that normally is generated when purifying a stream, can be decreased and in some instances almost eliminated.

The benefits of the Selmext technology are:

• High selectivity
• Minimizing secondary waste
• Low energy requirements compared to other membrane technologies
• Highly adaptable to most types of water matrices
• Useful to treat washing liquids used to purify solidified waste
• Can transform waste streams into resources