BHP tailings challenge: Repurposing copper tailings

Each year, multi-million tonnes of copper tailings are generated by the mining industry’s operated assets across North and South America.  

Tailings are the leftover materials from the processing of mined ore. They consist of ground rock, unrecoverable and uneconomic metals, chemicals, organic matter and effluent from the process used to extract the desired products from the ore. Tailings generally leave the mine processing plant in a slurry form (diluted with water) and are often stored on the surface in tailings storage facilities (TSFs). Safe and effective operation and closure of TSFs is a BHP priority.  

In 2020, BHP launched a tailings challenge with the aim of developing innovative solutions to repurpose copper tailings, which could in turn reduce the volume of tailings requiring storage. The challenge received more than 150 submissions from 19 countries with 10 shortlisted to progress through to the proof-of-concept stage. In mid-2022, two finalists were selected to perform pilot testing in a controlled environment.  

Auxilium Technology Group, in collaboration with Metso Outotech, was one of the finalists. Its solution aims to fully repurpose copper tailings. Copper and other valuable metals are recovered, then water is removed from the remaining tailings, which can then be used as construction aggregate or converted to an insulation material.  

The second finalist was a consortium comprising Americas Tailings Inc. and Advancing Materials Processing Inc., which aims to produce fertiliser from copper tailings.  

By the end of FY2023, both projects had completed controlled testing, however analysis of the results from the trial determined they were not suitable for replication at this stage.