Increasing energy efficiencies in mineral processing operations
The Collaborative Consortium for Coarse Particle Processing Research (CPR) focuses on the multidisciplinary aspects of coarse particle processing – such as flotation, comminution, classification, equipment design and process chemistry – to reduce energy use and the environmental footprint of mining operations. The Complex Orebodies Program (COB) supported the early development of this industry–research partnership.
Crushing and grinding rock (comminution) in the processing stage is incredibly energy-intensive – accounting for nearly half (40 per cent) of the energy that mining operations use. One estimate puts comminution at 0.4 per cent of the world’s total electricity use for producing base and precious metals.
Reducing the energy cost of comminution is therefore a prime target for the mining industry and researchers. If flotation circuits could work with coarser particles (0.5–1 mm), much less crushing and grinding would be needed.
Flotation is the process where fine mineral particles are added to large bubbling tanks, and the valuable particles are recovered at the top in the form of a mineral froth.
Diagram of flotation process
Diagram of flotation process
The good news, Associate Professor Liza Forbes said, is that there is an existing technology.
Associate Professor Forbes is the co-technical director of CPR and leads the Flotation Chemistry Research Group at the Sustainable Minerals Institute Julius Kruttschnitt Mineral Research Centre (JKMRC).
“We are trying to develop and integrate technology that is able to process particles and extract value from them without having to grind them very fine.”
Increasingly difficult mining context drives coarser particle processing
Associate Professor Forbes explained that modern issues have accelerated the urgency of processing coarse particles:
- There is now less metal in the ore extracted by mining.
- More energy use leads to more greenhouse gas emissions, exacerbating climate change.
- Using more energy costs mining operations more money, and more comminution takes more time.
- Earthen tailings dams, which store fine mine waste, can be huge hazards if they fail.
- Processing only fine particles reduces the ability to reclaim tailings wastewater.
- There are stricter regulations for tailings disposal.
“Being able to process coarse particles is acknowledged as a key method for industry to improve the energy efficiency of its processing operations.
“This is all about achieving a very substantial drop in energy consumption and, in turn, reducing greenhouse gas emissions,” Associate Professor Forbes said.
She also highlighted that improving coarse particle processing increases the ability to recycle the water that mining operations use by reclaiming it when tailings are disposed on mine waste sites – which could move the industry towards using dry stacking [tailings], instead of tailings dams that are prone to catastrophic failure.
Image credit: Adobe Stock / Alexey Rezvykh
New flotation technology comes with its own challenges for industry
Associate Professor Forbes said “the traditionally conservative background of the mining industry means there is little appetite for risk”, so uptake of new technology – such as the market-ready technology called Eriez HydroFloat® – is low.
“We want to fully unlock all its possibilities. We are finding out the best way to make use of it in the industry to give mining companies enough understanding and enough comfort to be able to implement it in their operations.”
Patented in 2002, HydroFloat® technology has proven successful for recovering larger particles with much less exposure of the valuable minerals on their surface. However, it cannot immediately replace traditional systems: it does not work well with very fine particles, so they need to be removed before the process.
Untangling this problem – and others such as performance, reliability and maintenance – requires careful work between mining companies with researchers. In 2018, Associate Professor Forbes and Associate Professor Kym Runge initiated that process after receiving support from the Complex Orebodies Program.
“We discovered that all our industry contacts had similar problems in common,” Associate Professor Forbes said.
Genuine, open collaboration flowed from COB cultivating atmosphere of trust
The long consultation process began with CPR’s first key partners, Eriez FD and Newcrest Mining, and rested upon an important foundation of trust.
“People were very reserved – these are highly competitive institutions – but Kym and I were very careful to make sure we did everything with complete transparency.”
“We had representatives from Newcrest, Rio Tinto and Anglo American talk about some of the plan trials that had not been successful, and going into reasons why.
“This momentum has continued: the industry–researcher forum meets every quarter, and every six months for a full technical review.”
Associate Professor Forbes said the forum has created a pool of diverse knowledge about mining operations, their understanding and concerns.
The consortium of CPR members includes researchers from SMI’s JKMRC and representatives from Anglo American, Aeris Resources, the Eriez Flotation Division, Glencore, Hudbay Minerals, Newcrest Mining and Newmont.
Image credit: Adobe Stock / OlesiaRu
CPR projects will deliver results plus a very valuable collaboration
The CPR has developed an ambitious scope of work to meet five main objectives: maximising recovery of coarse particles; predicting what will be recovered, how and how much; optimising the flotation circuits; evaluating the advantage of the HydroFloat® technology; and scaling up HydroFloat® technology.
“We will then assess how far we can go with implementing this technology with the information that we have,” Associate Professor Forbes said.
“In research, your work never ends, because you always find something that you don’t know. But the collaborative structure of the forum and the framework of what we’re doing is almost as valuable as the technical work itself.”
“It’s exciting to get all of these minds together, to collaborate and work together for a free and collegial sharing of information and discussion.”
Contact details
Associate Professor Liza Forbes
Group Leader - Flotation Chemistry Program
Technical Director – Coarse Particle Research (CPR) Program
Julius Kruttschnitt Mineral Research Centre
Sustainable Minerals Institute, The University of Queensland
Email: l.forbes@uq.edu.au
Profile: smi.uq.edu.au/profile/4524/liza-forbes
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