No time to waste


Richard Roberts

Management of mine waste ‘at a pivotal juncture’

Not too long ago Anita Parbhakar-Fox would have struggled to fill a room with people looking to get up to speed on mine waste valorisation and ponder future net zero scenarios. Earlier this month she had to turn them away.

The renowned mine waste expert and associate professor at the Sustainable Minerals Institute in Brisbane, Queensland, was one of the architects behind the 2024 Australian Mine Waste Symposium.

Organisers thought they’d get 80 people to the University of Queensland venue but had to stop taking registrations at 170 because of capacity constraints.

Mine waste exploitation, valorisation, even minimisation, are clearly getting more attention from miners and other stakeholders. Nirvana is a future place where any mine waste is recycled or repurposed. Economics have undermined this concept until now, though recent catastrophic events involving mine waste have put some real costs of failure on the table.

An unintended consequence of new mine waste atlases and value audits is going to be a more intense public spotlight on the staggering scale of mining’s waste problem.

Parbhakar-Fox said a question she put to a day-one panel at the symposium was: “Is net zero mine waste possible by 2050?”. Another question that might have been considered was, will net zero mine waste be required, by communities, regulators and even investors, by 2050?

Parbhakar-Fox wrote in a recent GeoScienceWorld op-ed that about 100 gigatonnes of mine waste was being produced annually around the world. The global mine waste footprint could be more than 50,000 square kilometres – almost the size of Costa Rica.

“Taking just one commodity, copper, tailings production [is predicted] to increase from 4.3Gt a year in 2020 to 16Gt/y in 2050. In total, 858Gt of mine waste could be produced for this metal alone up to 2050,” Parbhakar-Fox wrote.

An estimated 90-98% of copper ore processed ends up as tailings.

“The United Nations declared acid and metalliferous drainage [AMD] the second biggest global environmental challenge after climate change as typically, once AMD has started to form, it is very difficult to contain,” Parbhakar-Fox wrote.

“Whilst the engineering design of mine waste facilities attempts to prevent AMD, the majority fail to do so in the long run.

“Turning wastes into resources must be the final goal to avoid all the risks and mitigation measures.

“However, this will only be possible if we know what these wastes are, geometallurgically speaking, in advance or once deposited.

“[So] the technological innovations for multi-scale ore characterisation and the data sets collected must also be applied to mine waste characterisation. If this information is routinely and continuously collected over time, then better geoenvironmental and economic decisions can be made across the life-of-mine.”

The volume of talk in the mining industry about better resource and waste characterisation is getting louder as the spectre of bigger waste mountains, connected to increased mineral demand, declining grades and deeper mines, looms.

BHP’s global resource characterisation practice lead, Kerry Turnock told a Perth mining conference last September (and multiple other industry events in recent times) miners were “going to have to start characterising waste to a very similar level that we characterise our ore”.

“We need to think about how we characterise the rock mass,” she said. “We need to think about the changing environment that we’re going to be operating within.”

Turnock says: “In terms of resource characterisation for ore and waste it is absolutely the time to change and drive this home. No longer is resource classification enough.”

BHP’s veteran geoscience boss Cam McCuaig told another industry event earlier in 2023 that “front-end loading” of data that could radically change decision-making across mining value chains required smarter use of available drilling and ground-sensing technologies. And then the use of adequately trained AIs to help turn all the data generated into better insights and decision-making.

Australian Mine Waste Symposium delegates, an international mix of industry professionals, government representatives, academics and students, were exposed to new research and ideas to help them “truly think about [the net zero question] in a balanced manner”, Parbhakar-Fox said. The symposium gave them “a space to allow them to reflect on the technology, policy and appetite needed to move towards this”.

“The answer may not be black and white,” she said.

“But a shift in waste reduction earlier in the mine life cycle – identifying reusable minerals and metals as a mine project during the feasibility stages – could be significant, as well as finding new ways to define value and recover it.”

On the technology front, Parbhakar-Fox said the invention and application of drill-core scanning platforms was “revolutionary in reducing waste footprints from the outset as we have high resolution data on more material and the mineralogy, too, and that’s the key to designing mines with smaller waste footprints”.

She said while geostatistical approaches were being taken to map spatial heterogeneity of geochemically important parameters in waste-rock piles, new technologies could also be used to enhance or improve the accuracy of the models.

“Hyperspectral technologies, also known as infrared spectral imaging drill-core techniques, are the most promising as they provide micro-structural and mineralogical insights at the right scales to complement the geoenvironmental risk evaluation of a mineral deposit.”

The symposium heard from InnovEco Australia managing director Henry Sukhinin that the world’s mass of mine tailings was thought to contain trillions of dollars worth of valuable metals.

Leigh Staines, a senior mining and energy industry figure, told InvestMETS.com she saw evidence at events such as the Australian Mine Waste Symposium, including the high attendance level, of a growing appetite to better understand the pros and cons of waste valorisation.

“There was definitely a theme that kept coming up around the need to really consider value in all of the outputs from a mine, whether that be a tailings facility or the output of a production mine, and really starting to see all of that as product, not as waste,” she said.

“There was a range of really good examples that came through.”

Staines said the case studies were vital.

“I think there’s a growing desire to pursue mine waste valorisation,” she said.

“In theory it’s a great idea; lovely connection to circular economy principles, etc. But in reality, it hasn’t really been proven yet.

“So there is genuine desire to understand more about it. Is it viable? Can it work and how is it going to work? Are there new approaches that we haven’t heard of?”

Panel discussion at the Australian Mine Waste Symposium (pictured left to right): Jonathan Loraine of Core Resources, Queensland Department of Resources’ Dr Janelle Simpson, Dr Simon Johnson from the Geological Survey of Western Australia, Anita Parbhakar-Fox, Cobalt Blue’s Dr Helen Degeling, Jane Thorne of Geoscience Australia and Queensland University of Technology’s professor Sara Couperthwaite

Jonathan Lorraine, founder and chair of metallurgical and environmental solutions company, Core Resources, said at the symposium financial and reputational (not to mention environmental and people) damage caused by major tailings dam failures was forcing both miners and governments to take them more seriously.

“I think there’s a very good incentive and activity from government supporting this for good reasons. The other thing is major mining corporations, it’s become really front of mind to them.

“You’re seeing them [big miners] putting serious money into producing less tailings and managing tailings properly and extracting full value from tailings materials,” he said.

Ashleigh Morris, CEO of Brisbane-based Coreo, has worked with a number of mining and other industry clients on “catalysing the transition to a circular economy”.

She says management of mine waste is “at a pivotal juncture”.

“Historically, mine waste has been viewed as a problem rather than an opportunity,” she said.

“It has often been considered a necessary byproduct, leading to inefficiencies and missed opportunities for value creation.

“Transitioning to a circular economy involves more than just technical adjustments; it necessitates a systemic shift in how mining operations are conceived.

“Needless to say, when it comes to our mindsets around waste it’s our biggest barrier, and certainly one of the biggest barriers facing the mining industry.

“But if we look at nature there is no waste in nature. Materials flow cyclically, restoring and regenerating the natural capital, which underpins the functioning of the natural world.

“So my key message really, is why can’t we learn more from nature and consider how we can design out waste entirely from our mindsets, vocabularies and economies.”

 

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