‘The war on waste’: How could the mining industry respond?

This is the question that Dr. Anita Parbhakar-Fox will ask at her keynote lecture at Sustainable Minerals '20 in Falmouth. Anita is the leader of the Geometallurgy, Geoenvironment and Mining program at the Centre for Ore Deposit and Exploration Science, University of Tasmania, Australia. Her research is focussed on mine waste characterisation to facilitate environmental conscientious mine planning and improved waste management practices.  She is committed to improving mine closure practices and in 2018 became a member of the Victorian Government’s Technical Review Board for Mine Rehabilitation. 

According to Anita an international ‘war on waste’ is waging whereby industries and consumers are becoming increasingly aware of the environmental impacts our linear ‘take-make-dispose’ economy facilitates. The promotion, and in some cases adoption, of circular economy principles has grown in recent years but how has this impacted on the mining industry, and more specifically, mine waste characterisation and management practices?  Fundamentally, we mine waste, not ore. The large tonnages of waste rock handled at mine sites, particularly open cuts, illustrates this, and we will continue to mine in this manner to meet the metal demands of our growing global community. Therefore, it is imperative that the waste we produce is thoroughly characterised to determine: i) if it can be further utilised i.e., following circular economy principles; or ii) if it truly is waste how can it be disposed of so that the environmental risk is minimised?  

Traditionally mine waste characterisation involves the integrated use of geochemical static tests with mineralogical tools used only where classification conflicts arise. However, with new tools becoming available to the mining industry (e.g., portable technologies, hyperspectral infrared and XRF platforms for drill core analyses, machine learning algorithms for image processing) the opportunity has arisen to improve waste characterisation protocols to better understand their properties, in particular their mineralogy, which is the key to improving waste management practices.

Once produced, mine waste materials are stored in piles or other designated repositories and are engineered to minimise environmental risk. However, if detailed waste characterisation is not undertaken then determining if it has any functionality is challenging. Performing geometallurgical studies on existing waste, including the use of mineral chemistry tools, could resuscitate operations on the brink of closure by identifying commodities not originally sought. Therefore, searching in our mine waste presents an opportunity to identify and market ‘green metals’ with the very real benefit of environmental de-risking (i.e., if the waste contains fertile sulphides prone to generating acid drainage).

If mine waste properties are understood, then these materials can be carefully engineered to assist with managing other industrial waste products, for example, carbon dioxide emissions. Recent studies have discussed the role of mine tailings in carbon sequestration and by using new technologies during early life-of-mine stages the industry can rapidly identify if their tailings have amenable mineralogical properties to enable this. More opportunities lie in blending or co-disposing of mine waste with alkaline wastes generated by a range of industries including paper milling (green liquor dregs), aluminium refining (red-muds) and even fisheries (spent shells). By marrying waste from two industries, the overall waste footprint (and associated management costs) can be reduced, and the risks associated with both minimised.

Anita will show that whilst pilot studies have demonstrated the application of these research endeavours, how this translates into routine practice remains a fundamental challenge. 

Updates on Sustainable Minerals '20 can be found at #SustainableMinerals20.