Auxilium Technology Group (ATG), a start-up connected to the University of Arizona, in collaboration with Metso Outotec, has been announced as one of two finalists in the BHP Tailings Challenge, an international competition to promote the development of new technologies to reuse mine tailings.

Last year, ATG was one of 10 companies and academic research groups chosen to move on to the laboratory stage of the BHP Tailings Challenge, from an initial field of 154 applicants from 19 countries. Metso Outotec and ATG signed an agreement to collaborate on this initiative and, in April 2022, BHP chose two finalists, ATG and Americas Tailings Inc, a company that has developed a process to turn mine tailings into fertiliser products.

For the next phase, ATG plans to build a pilot tailings processing plant at the San Xavier Underground Mining Laboratory, owned by University of Arizona. Metso Outotec will contribute with advice on engineering and scale up using Metso Outotec products.

Metso Outotec supported the ATG process design concept by estimating engineering costs and providing Metso Outotec Plant Solutions technology competence. The concept considers pre-designed plant units known as “Process Islands” for almost all the process areas of the future plant, the company said.

Metso Outotec’s approach supported the project from optimal equipment sizing to optimising engineering costs and modularising the plant to meet future capacity requirements.

Mining companies like BHP are eager to find alternatives for the use of tailings, which are costly to store and regulated under environmental laws because they contain pollutants.

After initial cleaning of the tailings, the proposed process includes use of the material as construction aggregate or an insulating “geofoam” that can be sprayed or 3D printed to produce insulating blocks.