A (critically) wasted opportunity?

This article was originally published in the Global Mining Review, 27 May 2022.

Associate Professor Anita Parbhakar-Fox, Group Leader – Mine Waste Transformation & Characterisation (MIWATCH), discusses the best way for the mining industry to reduce mine waste.

A waste revolution is truly upon us. No longer are the mountains of waste rock and piles of tailings seen as a tax-payer burden. Instead, they represent a new business opportunity – introducing the secondary resources sector¹. Well established mining practices have long since sought to extract commodities, such as: copper, iron, gold, nickel, lead, and zinc. However, the associated mine waste can contain significant concentrations of highly sought-after critical metals including cobalt, rare earth elements, vanadium, and indium. Whilst mine waste will not deliver all the metals required (i.e. 390 000 t of cobalt will be required by 2030), reprocessing these materials can supplement future demands and offers many environmental benefits. From reducing the likelihood of acid mine drainage formation, minimising geo-stability risks right through to reducing overall mining footprints.

Whilst major mining companies are starting to invest in secondary exploration, as seen in late 2021 when Rio Tinto announced funding for Washington-based start-up Resolve,² projects by junior operators are well underway as demonstrated by New Century Resources, Queensland,³ Mt Carbine, Queensland,⁴ and Hellyer, Tasmania⁵. But in Australia, it is really the state and federal government agencies who are driving change. For example, the Queensland Government and Geoscience Australia have invested in secondary exploration research at the Sustainable Minerals Institute, University of Queensland. These programs aim to identify secondary resources of critical metal at both operational and abandoned mine sites. To date, exploration focus has been in northwest Queensland, with new potential deposits of cobalt identified. One of these prospective sites, the Rocklands Cu mine, has attracted external investment from the Japan Oil, Gas, and Metals National Corporation (JOGMEC), with their funds enabling additional mineralogical characterisation and determining metallurgical options for cobalt recovery.⁶ It is only a matter of time until the mineral processing companies, with a recent AUS$240 million dollar investment from the Australian Federal Government,⁷ turn their attention to using mine waste materials as feed stocks, with Cobalt Blue already recognising the importance of mine waste as a critical source of future metals.⁸

But the revolution does not just stop there. Once critical metal resources have been recovered, what of the residual waste? Motivated by Circular Economy principles, innovative valorisation options are being developed globally. These range from using benign tailings to manufacture bricks for affordable housing⁹ to the production of geopolymers.¹⁰ However, one of the most promising applications, is the recovery of ‘ore sands’¹¹ with major mining companies, such as Vale, interested in determining the suitability of their tailings to this potentially lucrative valorisation option. Many markets remain untapped, for example, the billion-dollar beauty industry requires micas for a range of cosmetic products. But, with controversies associated with mica mining,¹² perhaps another option is to source it from mine waste?

Ultimately, the best way to reduce mine waste is to design it out right from the start. As the mining community braces itself for a critical metal mining boom, using multi-scale technologies to facilitate early total deposit characterisation is the key to approaching another important net zero… net zero mining waste.

References

1. VAN DER ENT, A., PARBHAKAR-FOX, A., and ERSKINE, P. D., ‘Treasure from trash: Mining critical metals from waste and unconventional sources’, Science of The Total Environment, 758 143673, 143673, (2020), https://doi.org/10.1016/j.scitotenv.2020.143673
2. ‘Rio Tinto invests in start-up to support habitat restoration’, Rio Tinto, (9 November 2021), https://www.riotinto.com/news/releases/2021/Rio-Tinto-invests-in-start-up-to-support-habitat-restoration-final
3. New Century Resources, https://newcenturyresources.com/
4. EQ Resources, https://www.eqresources.com.au/site/content/
5. ‘Hellyer’, NQ Minerals, https://nqminerals.com/hellyer/
6. ‘Trash to treasure: copper mine waste could hold key to renewable revolution’, Queensland Government, (26 October 2021), https://statements.qld.gov.au/statements/93604
7. BELOT, H., ‘Government commits $240 million to critical minerals projects in mission to end Australia's reliance on China’, ABC News, (15 March 2022), https://www.abc.net.au/news/2022-03-16/government-funds-critical-minerals-end-china-reliance/100912002
8. ‘NSW Deputy Premier Announces Mine Waste Re-Use Initiative at the Broken Hill Cobalt Project Demonstration Plant’, Australian Government, (20 April 2022), https://cobaltblueholdings.com/news/nsw-deputy-premier-announces-mine-waste-reuse-initiative/
9. Mobile Crisis Construction, https://www.crisisconstruction.com/
10. MAZZINGHY, D.B., FIGUEIREDO, R.A.M., PARBHAKAR-FOX, A., YAHYAEI, M., VAUGHAN, J., and POWELL, M.S., ‘Trialling one-part geopolymer production including iron ore tailings as fillers’, International Journal of Mining, Reclamation, and Environment, (16 March 2022), pp. 1-12., https://www.tandfonline.com/doi/abs/10.1080/17480930.2022.2047271
11. GOLEV, A., GALLAGHER, L., VANDER VELPEN, A., LYNGGAARD, J.R., FRIOT, D., STRINGER, M., CHUAH, S., ARBELAEZ-RUIZ, D., MAZZINGHY, D., MOURA, L., PEDUZZI, P., FRANKS, D.M., ‘Ore-sand: A potential new solution to the mine tailings and global sand sustainability crises – Final Report’, The University of Queensland & University of Geneva, (March 2022).
12. VELLA, H., ‘Mining mica: can the industry overturn its legacy of exploitation?, Mining Technology, (28 January 2020), https://www.mining-technology.com/analysis/mining-mica-can-the-industry-overturn-its-legacy-of-exploitation/