Gold, one of the most precious metals in the world, with estimated reserves of 54,000 ton, can be extracted from primary (mineral deposits) or secondary resources (recycling of printed circuit boards (PCBs)). Ore deposits are becoming poorer and more complex. PCBs exhibit ahigh gold content, but their availability cannot be consistent to justify the investment on a processing plant. 

Thus, a hybrid approach that combines the processing of both materials can be the key to introduce an attractive business concept to the gold industry. In line with this, the project pretends to address the following needs and challenges: 

i) Proof of concept regarding the impact of Electric Pulse Fragmentation (EPF) to increase gold liberation from complex ores, to reduce energy consumption and to improve the performance of the subsequent processing stages; 

ii) Study of greener reagents that can be applied to the flotation and leaching stages; 

iii) Development of a cost-effective device to improve the rejection of sterile material from the PCBs;

iv) Design of a hybrid hydrometallurgical approach that would combine gold processing from ores and from PCBs; 

v) Identification of techniques to enhance the recovery of critical elements during the hydrometallurgy stage; 

vii) Elaboration of an action plan to promote good practices and better information for citizens and activation of research ecosystem focused on raw materials. 

The project will start with the preparation and characterization of the materials that will be studied (WP1) - samples of PCBs will be provided by a recycling company and ore samples will be collected from a mine site and a tailings dam in Portugal. Then, innovative comminution techniques based on EPF will be compared to the conventional comminution pathway (WP2), evaluating its potential to enhance the liberation of gold and to reduce the overall energy consumption. 

Regarding the physical processing of ores and e-waste (WP3), several scenarios would be considered: 

i) froth flotation and gravity concentration tests to assess the effect of EPF; 

ii) application of greener reagents in gold flotation of ores and PCBs; 

iii) the development of a prototype, based on jigging principles, to reject sterile material from PCBs. 

Then, the hydrometallurgy stage will be carefully studied (WP4) to develop a hybrid process, based on the use of greener reagents (thiosulfate, halides, etc.) to dissolve gold from ores and PCBs. 

Additionally, the feasibility of a staged leaching process to recover critical elements would be assessed. An action plan to face the public perception regarding mining industry (WP5) will be prepared and implemented during the project activities. Finally, WP6 is devoted to the project management, ensuring the timely delivery and dissemination of the project results. 

INN4MIN will follow a strict I&D methodology to promote the recovery of gold from primary and secondary resources, supported by a technological monitoring of innovative practices in the gold processing stages that will include the activation of stakeholders and identification of potential collaborative projects. This will make sure that the project outcomes are aligned with the recent development on the project domains. Innovative methods and products will be investigated having as main drivers the reduction of environmental impacts, the improvement of mineral processing efficiency and the promotion of good practices in mining industry to change the public perception related to the mining sector. In terms of experimental test work, lab-scale tests will be carried out aiming a TRL of 4. Additionally, the development of a prototype can increase the TRL of the project, depending on its success. The consortium is composed by 5 partners, who have been selected based on their complementary expertise in terms of detailed technical competence on EPF comminution (BRGM), physical processing (FEUP/LNEG), hydrometallurgy (GEOS/FEUP) and business & social experience (INOVA+).