Non-toxic leaching and recovery of gold using thiosulfate based lixviant and Selmext metal separation technology

Important results from the project

The project has demonstrated the Tiosulfat-Selmext technology in pilot scale. The goal of taking the technology from bench scale to pilot scale and showing its economic potential has been met. Set research goals for an improved process have been achieved including e.g., limiting leaching factors, optimization of the leaching process, reuse of lixiviant solution, and ultrasound-assisted leaching. The project has led to good supplier contacts and new ideas for the full scale equipment.

Expected long term effects

Hopefully, this is the basis for reducing cyanide use in gold leaching. Cyanide leaching is associated with increased environmental and health risks, capital availability, activism, bad publicity, social acceptance, insurance and environmental permits. In some parts of the world, cyanide use is more accepted but in others there is a ban or even social reluctance or activism. Tiosulfat-Selmext can eliminate the toxic risk posed by cyanide and enable local leaching and gold extraction at the mine.

Approach and implementation

The project has been completed with good cooperation between the parties. The project has been delayed and is therefore extended by 6 months due to the Swedish Migration Board´s processing time for LTU´s post doc. Furthermore, the project has been affected by some external factors such as Covid, which caused us to use other means to achieve the same results, eg. reduced travel and more digital meetings and the relocation of the pilot from the mine to Chromafora´s premises in Stockholm.