What might we expect at Comminution ’27?

When the 14th International Comminution Symposium, Comminution ’25, gathered in Cape Town last year the mood was unmistakably one of transition. The fundamentals of crushing and grinding had, of course, not changed. Rock still has to be broken, energy is still required to break it, and the perennial challenges of wear, throughput, liberation and classification remained firmly on the agenda.

But there was a noticeable shift in the questions being asked. How can we make comminution more selective rather than simply finer? How can sensors tell us what is happening inside a mill before the operator can see the consequences? Can artificial intelligence replace some of the expensive and time-consuming conventional characterisation work? And perhaps most importantly, how do we design a circuit around the whole value chain rather than optimising individual pieces of equipment?

As we look ahead to Comminution ’27, these questions are likely to become even more prominent. So what might have changed between the presentations at Comminution ’25 and Comminution ’27?

Artificial intelligence was already impossible to ignore at Comminution ’25. The opening keynote examined how rapidly developing AI techniques were accelerating comminution modelling, while other presentations explored machine learning for mill optimisation, AI-assisted calibration, soft sensors and model-predictive control. One particularly practical example was work using machine learning to predict standard comminution parameters from Geopyörä breakage-test data.

At Comminution ’25, AI was often presented as a promising addition to existing modelling and control methods. By Comminution ’27, we may see much more emphasis on AI embedded in the workflow. That could mean AI-assisted ore characterisation, rapid geometallurgical variability assessment, real-time soft sensors, predictive control and automated optimisation. 

Another strong thread from Comminution ’25 was the rapid development of indirect ways of seeing what is happening inside equipment. Acoustic monitoring was one example. Research presented at the conference investigated how changes in AG/SAG mill feed size produced distinctive acoustic responses. Similarly, the conference included work on instrumentation and analytics for cone crushers, including the integration of noise, vibration, high-frequency monitoring and vision systems for fault detection and condition monitoring. Since the conference, the same direction has continued into fine grinding. This is significant, as for decades operators have had to infer what is happening inside a mill from measurements taken around it: power draw, pressure, density, flowrate, product size and so on. The next generation of systems may make the equipment itself an increasingly sophisticated sensor. At Comminution ’27, expect more work combining acoustic, vibration, power, pressure, vision and process data and turning those signals into information that operators can actually use.

Perhaps the most important evolution since Comminution ’25 is occurring at flowsheet level. There were already strong signs of this in Cape Town. One study presented a framework for integrated optimisation of crushing, milling and cyclone classification, explicitly considering throughput and product quality together. Another proposed a “Parallel Flow Sheet” incorporating HPGR, stirred milling and classification.

At the same time, HPGR was being considered not simply as a more energy-efficient piece of equipment, but as part of fundamentally different circuit architectures. This is a crucial distinction. For many years, comminution innovation could be discussed in terms of better crushers, better mills, better liners or better grinding media. Increasingly, the question is becoming: what is the best sequence of breakage, classification and separation operations for the ore?

That opens the door to circuits that might look very different from the conventional crushing–SAG–ball mill–flotation arrangement.  HPGR, stirred mills, dry classification, coarse particle recovery and sensor-based sorting can all become parts of the same optimisation problem. Comminution ’27 could therefore be considerably more about flowsheet architecture than equipment optimisation in isolation.

“How fine do we really need to grind?” This may ultimately be one of the biggest questions of the next decade. The conventional response to poor liberation has often been to grind finer. But finer grinding comes with a price: energy, media consumption, wear, water consumption and, potentially, the generation of fines that are difficult to recover. Comminution ’25 highlighted this tension repeatedly. There was discussion of the balance between improved liberation and fines generation, dry grinding, coarse gangue rejection, HPGR-based circuits, sensor-based sorting and alternative comminution technologies. The implication is that the optimum comminution product may not be the finest product. It may be the product that gives the best combination of liberation, particle size, shape and downstream recoverability.

That moves comminution much closer to the heart of the entire mineral-processing value proposition. This leads naturally to another likely feature of Comminution ’27: increasing interest in selectivity.

Traditional comminution is largely indiscriminate. The objective is to reduce particle size, while liberation is a consequence of the breakage process. But mineralogical information increasingly allows us to ask whether rocks can be broken preferentially along mineral boundaries, or whether valuable minerals can be liberated without unnecessarily grinding barren gangue. Comminution ’25 contained several examples of this philosophy, from high-voltage pulse power and HPGR to GRolls and mineralogical investigations of breakage.

The subsequent literature is moving in the same direction. Work on microstructure and breakage is providing a more detailed understanding of how mineral texture affects fragmentation, while research into slow-compression breakage is examining the transition between single-particle and confined-particle-bed breakage. The big prize is not simply lower specific energy. It is lower specific energy while producing a more useful particle population. That means asking what happens to the particles after they leave the crusher or mill.

One of the most interesting developments at Comminution ’25 was the growing recognition that the grinding environment can affect downstream mineral processing, including subsequent collector adsorption and flotation behaviour. This is another sign that the old boundaries between unit operations are becoming less useful. The comminution engineer cannot simply specify a P80 and hand the product to the flotation engineer. Particle shape, surface chemistry, mineral exposure, fines generation and fracture characteristics can all influence what happens next. By 2027, we may therefore see more papers evaluating comminution performance using downstream recovery and grade, rather than energy consumption and particle size alone. That would be a welcome development. After all, the purpose of grinding is not to make small particles, it is to make valuable minerals recoverable.

Energy efficiency has been a central theme of comminution research for decades, but the sustainability discussion is becoming broader. Water availability is increasingly important, particularly in major mining regions such as Australia, Chile and Peru. Comminution ’25 included several examples of dry grinding, dry classification and flowsheets designed to reduce water consumption. Dry VRM technology, for example, was presented as offering substantial energy savings relative to traditional mill systems, while dry HPGR-based flowsheets were being combined with classification and beneficiation concepts. This suggests that Comminution ’27 may increasingly evaluate technologies against several simultaneous metrics. In other words, specific energy will remain important, but it will no longer be enough. 

Comminution ’25 also contained a healthy dose of scepticism. Grant Ballantyne's keynote asked how metallurgists can distinguish the “fine wine from the snake oil” when assessing new comminution and classification technologies. A lower energy process may have higher wear; improved liberation may not translate into improved recovery; laboratory results may not survive scale-up. That may be an even more important conversation in 2027.

The industry has no shortage of exciting technologies. High-voltage pulse power, novel compression devices, advanced stirred mills, AI, sensor-based sorting, digital twins, novel liners, new grinding media and radically different circuit configurations all offer intriguing possibilities. So, what might Comminution ’27 look like? 

At Comminution ’25 we saw the beginnings of a move from understanding comminution towards controlling comminution. We saw AI beginning to enter the mainstream, sensors beginning to reveal what happens inside opaque equipment, and alternative technologies challenging the dominance of conventional SAG and ball milling. Two years later, the test will be whether those ideas have survived contact with operating plants.

That is what could make Comminution ’27 particularly interesting. Not simply what is the latest technology? But which of the technologies we were excited about in 2025 have actually delivered? And perhaps, most importantly, what new ideas will have emerged in the meantime that none of us saw coming? One thing seems certain: if Comminution ’25 was about finding new ways to break rock, Comminution ’27 may be increasingly about knowing why, where, when and how much to break it and making the entire mineral-processing circuit respond accordingly.

#Comminution27
#MEIBlog

AI, Critical Minerals and the Race to Build Processing Capacity

The extraordinary growth of artificial intelligence is creating a new and largely unexpected source of demand for minerals. As AI data centres proliferate around the world, the challenge is no longer simply about having enough computing power. Behind every new facility lies a vast physical infrastructure of electricity generation, transmission, transformers, cooling systems and equipment, all of which depend on mineral resources.

A recent study highlighted by Rare Earth Exchanges estimates that copper could account for more than 80% of the total mineral mass associated with AI data-centre infrastructure, with grid transmission and distribution responsible for a significant proportion of that demand. Grain-oriented electrical steel, a specialist steel used in transformer cores, is another potential constraint as electricity networks expand. For materials such as gallium, germanium, graphite and rare earths, however, the bigger concern is not necessarily geological scarcity, but the availability of processing capacity and the concentration of supply chains.

This distinction is important. Finding a mineral deposit is only the beginning. Turning that resource into a consistent, specification-grade material requires processing technologies, expertise, infrastructure and investment. In many cases, these downstream capabilities are considerably more concentrated than the resources themselves.

As AI adds another major source of demand, competition for processing capacity could become increasingly intense. This raises fundamental questions for the minerals industry. Can existing resources be processed more efficiently? Can valuable minerals be recovered from lower-grade ores and complex deposits? Can waste streams and end-of-life products become meaningful sources of secondary supply? And can new technologies reduce the energy, water and environmental footprint of mineral processing?

These are precisely the kinds of questions that need to be addressed by the international mineral processing and extractive metallurgy community.

But there is a bigger question surrounding the rapid expansion of AI: where is this technology taking humanity, and are its benefits sufficient to justify its growing physical and environmental demands? Concerns about employment, human creativity, privacy, misinformation, energy consumption and the longer-term role of humans in an increasingly automated world are becoming increasingly prominent.

Whatever the answers, one thing is clear: the AI revolution is not purely digital. Its expansion depends on enormous quantities of metals, minerals, energy and infrastructure. If AI is to deliver genuine benefits to society, the systems supporting it will need to be developed as efficiently and responsibly as possible.

This is where MEI Conferences can play an important role. By bringing together researchers, technology developers, equipment manufacturers, consultants and industrial practitioners, MEI provides a forum where emerging processing challenges can be discussed alongside practical experience from operations around the world.

The critical-minerals challenge is not simply a mining challenge. It is a processing, technology and knowledge-sharing challenge. Breakthroughs in mineral separation, flotation, hydrometallurgy, process mineralogy and recycling could unlock resources that would otherwise remain uneconomic or underutilised.

There is also an important circular-economy dimension. If primary supply cannot expand quickly enough to meet growing demand, greater attention will turn towards recovering critical materials from industrial residues, electronic waste and other secondary resources. Developing economically viable processes for these materials will require the kind of cross-disciplinary collaboration that technical conferences can facilitate.

The current AI expansion is therefore more than another source of mineral demand. It is a powerful reminder that the future of technology depends, in part, on our ability to innovate in mineral processing and that how we meet this demand will form part of the wider debate about the kind of technological future we want.

For MEI Conferences, that presents a clear opportunity: to bring together the scientists, engineers and industry professionals developing the technologies that could turn growing mineral demand into more secure, sustainable supply.

#MEIBlog

BME Metallurgy first time sponsors of Hydrometallurgy '27 and Flotation '27

BME Metallurgy is sponsoring MEI’s Flotation ’27 and Hydrometallurgy ’27 conferences for the first time, marking an important step in the company’s growing presence in the international mineral processing community.

The sponsorship is new, but BME Metallurgy and its predecessor business are certainly not new to MEI. Before the business was brought under the BME name, representatives of Protea Mining Chemicals were attending MEI’s flotation conferences in 2009, 2015 and 2023.

What has changed is the position of the business within the BME organisation. Protea Mining Chemicals was brought under the BME brand as part of Omnia’s strategy to create a more integrated mining offering, extending from blasting through to mineral processing. BME Metallurgy now presents itself as much more than a supplier of mining chemicals, offering expertise in flotation, leaching, solvent extraction, ion exchange, metal refining and process optimisation.

That makes the choice of MEI’s Flotation and Hydrometallurgy conferences particularly appropriate. Flotation '27 is directly aligned with BME Metallurgy’s reagent business, while hydrometallurgy is becoming increasingly important as the industry tackles more complex ores and seeks improved routes for recovering critical and battery metals.

There is also a strong sustainability theme. BME has been highlighting its work in green chemistry, chemical circularity, reagent recycling and reducing environmental impacts in mineral processing. Hydrometallurgy, in particular, provides opportunities to develop more selective and potentially more sustainable approaches to metal recovery.

The decision to sponsor both conferences therefore appears to reflect more than a conventional marketing exercise. BME Metallurgy is expanding internationally and seeking to establish itself as a technical partner to the mining industry, rather than simply a chemical supplier. MEI’s highly specialised conferences provide an opportunity to put that expertise directly in front of the metallurgists, researchers, mining companies and technology providers shaping the future of mineral processing.

In this respect, the significance of the sponsorship lies less in BME’s first appearance at an MEI conference, because its predecessor has been attending for many years,  and more in the decision to now put the BME Metallurgy name prominently behind two of the industry’s leading technical forums.

It suggests that BME sees Flotation '27 and Hydrometallurgy '27 not simply as markets for its products, but as important parts of the business it wants to build for the future.

Note that the conference has been rescheduled to September
rather than November as initially announced

#Hydrometallurgy27
#Flotation27
#MEIBlog

September Mining Sundowner and SW England's strategic minerals hub

A fine autumn evening yesterday for the September Cornish Mining Sundowner at Falmouth's Chain Locker. Although a modest turnout, it was an interesting one, with two former CSM Associates secretaries, past and current presidents of the Camborne School of Mines Student Union, one "fresher" and Sam Wood, all the way from Buxton in Derbyshire to celebrate 50 years to the day that he began his student years at CSM. I was one of his lecturers and as far as we know only one of two still alive! 

It has been an exciting few months for critical minerals in South-West England, and particularly for the old mining districts of Cornwall and Devon. The most dramatic development came last month, when the UK National Wealth Fund announced an investment of up to £71 million in Tungsten West to help restart the Hemerdon tungsten and tin mine near Plymouth in Devon. The package includes £36 million of equity and up to £35 million of debt, while the Government will have the right to secure up to half of the mine’s annual tungsten production. With tungsten now firmly recognised as a strategic mineral, and China dominating global supply, the decision is a significant indication of how seriously the UK Government is now taking domestic mineral resources.

This is particularly interesting when viewed alongside developments further west in Cornwall. At South Crofty, near Camborne, Cornish Metals continues to advance its plans for a return to tin production, following further National Wealth Fund support announced in May. Lithium developments are also progressing, with Cornish Lithium's projects seeking to demonstrate that lithium can be extracted from the region's granites and geothermal waters using innovative, lower-impact processes. The Government's new Critical Minerals Strategy specifically highlights Cornwall's work on Direct Lithium Extraction and the potential to combine lithium recovery with geothermal energy.

The really significant change is therefore not simply that individual projects are progressing, but that Cornwall and Devon are increasingly being viewed as a strategic UK mineral province. Tin, tungsten and lithium all feature prominently in the Government's critical minerals thinking, while the region is also developing expertise in processing, recycling, geothermal energy and other parts of the supply chain. The South-West has always had the geology; what has been lacking in recent decades has been the investment and confidence to turn that geological potential into operating mines and supply chains. The events of 2026 suggest that this may finally be changing.

#MEIBlog

Mantos Blancos NovaCell Pilot Study Receives Prestigious CEEC Medal

We are pleased to announce that a paper presented at MEI’s Flotation ’25 has received the highest recognition from the Coalition for Minerals Efficiency (CEEC), with the 2025 CEEC Technical Research Medal recognising an outstanding contribution to more efficient and sustainable minerals processing.

The award-winning paper, NovaCell Pilot Performance at Mantos Blancos: Advancing Toward Full-Scale Implementation, was authored by P. Amelunxen, B. Akerstrom and E. Jaques of Capstone Copper, Canada; A. Flores and L. Parraguez of Capstone Copper, Chile; M. Saavedra of Jord, Chile; and L. Cooper and S. Morgan of Jord, Australia. The paper was presented at Flotation ’25 by Alfonso Flores Carrillo of Capstone Copper, Chile.

The NovaCell is the latest flotation technology developed by Professor Graeme Jameson (seen left with Alfonso at Flotation '25). This innovative flotation device incorporates distinct recovery zones designed to improve the recovery of both coarse and fine particles. Australian company Jord holds the exclusive global commercialisation rights for the technology.

In late 2024, a NovaCell pilot plant was installed at Capstone Copper’s Mantos Blancos operation in Chile to process rougher tailings and validate encouraging laboratory results obtained in 2023. The pilot consistently exceeded expectations for both upgrade ratio and mass pull, providing strong evidence to support the advancement towards full-scale design and installation of a Jord NovaCell at the operation.

The CEEC Technical Research Medal is an important recognition of the collaborative work undertaken by the Capstone Copper and Jord teams and highlights the potential of NovaCell to contribute to more efficient and sustainable minerals processing. Congratulations to all the authors and everyone involved in the successful Mantos Blancos pilot programme.

#MEIBlog

Biology’s growing role in the critical minerals revolution

For decades, advances in mineral processing have largely come through improvements in chemistry, equipment and process engineering. Now, a new frontier is emerging, one that borrows its inspiration from nature itself. If recent developments are any indication, biotechnology could become one of the most important innovations in the recovery of critical minerals.

The latest evidence comes from Battelle, whose researchers have announced a breakthrough in the selective separation of rare earth elements using engineered proteins. Their work demonstrates that specially designed calcium-binding proteins can distinguish between chemically similar rare earths, achieving impressive levels of purity and recovery in a single-stage, water-based process without the need for conventional chelating agents. It is an exciting development because separation, rather than extraction, remains one of the greatest technical and economic challenges in the rare earth supply chain.

The announcement also provides a timely backdrop to a keynote presentation at MEI’s Critical Minerals ’26, where Chun-Xia Zhao and colleagues from Adelaide University and the ARC Centre of Excellence for Enabling Eco-Efficient Beneficiation of Minerals will present a sustainable biotechnology platform for mineral recovery that shares the same underlying vision: using peptides and proteins as highly selective molecular tools for separating valuable minerals and metals.

The principle is remarkably elegant. Instead of relying on increasingly intensive chemical processes to force materials apart, these bioinspired molecules are engineered to recognise specific minerals and metal ions with exceptional affinity. Like a lock designed for a particular key, they selectively bind target materials, including rare earth elements and precious metals, while leaving others behind. By incorporating these peptides into recyclable protein systems, the Adelaide team has created a platform capable of repeated separation cycles without losing performance, while recombinant production offers a scalable and potentially cost-effective route to manufacturing the biomolecules themselves.

Perhaps most significant is the breadth of applications. The technology is not confined to primary mining operations; it has equal relevance to the rapidly expanding field of urban mining. End-of-life photovoltaic panels, permanent magnets and batteries represent increasingly valuable secondary resources, but their complex composition makes efficient recovery difficult. Highly selective biological separation offers the prospect of recovering critical materials from these products using water-based processes that avoid many of the harsh solvents associated with conventional techniques.

It would be premature to suggest that proteins are about to replace solvent extraction plants or flotation circuits. Laboratory success must still be translated into robust, high-throughput industrial processes capable of handling the complexity and variability of real ores and recycled feedstocks. Questions of stability, regeneration, process integration and economics will ultimately determine commercial success.

What is becoming increasingly clear, however, is that biology is moving from the margins of mineral processing research into the mainstream. Independent advances from organisations such as Battelle and Adelaide University suggest a broader shift in thinking: the future of critical minerals may depend not only on discovering new deposits, but on designing molecules capable of recognising the elements we need with extraordinary precision.

For an industry challenged to produce more critical minerals while reducing its environmental footprint, that represents a genuinely transformative opportunity and one of the most fascinating themes to watch at Critical Minerals ’26.

#CriticalMinerals26
#MEIBlog

Memories of International Mineral Processing Congress 2006, Istanbul

In just over five weeks time the 32nd International Mineral Processing Congress will be held in Cape Town. The 23rd IMPC was held in Istanbul, Türkiye 20 years ago this month, from 3-8 September 2006. The location was particularly appropriate because Türkiye has a substantial and diverse mineral processing industry, including chromite, copper, lead-zinc, gold, borates, coal and iron. 

Bolstered by a huge Turkish contingent, the IMPC attracted over 900 delegates, then a record number (there were 751 at the last IMPC in USA). The conference included a strong body of research from Turkish universities and mining researchers, alongside international contributions and there were 453 presentations from 46 countries.

Three very memorable social events were held at the magnificent Dolmabahce and Beylerbeyi Palaces, the former being in the European sector of Istanbul, the latter across the Bosporus in Asia, and the farewell dinner was held at the end of the penultimate day of the conference, a magnificent affair rivalling the memorable ‘African Night’ at the previous Cape Town IMPC. In the splendid open air setting of Buyuk Klup, on the Asian side of the Bosporus, we were entertained, over an excellent 4-course meal, to live Turkish music, folk-dancing, and belly-dancing. There was a formal aspect to the evening as well, with final speeches from the organisers, and the lifetime achievement award to Prof. Heinrich Schubert. of the TU Bergakademie Freiberg, Germany.

Jon and I represented MEI, as a media partner, and some of our photos are shown below. There are many familiar faces, some sadly no longer with us, including the conference chairman, Prof. Güven Önal.

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From the rare earth supply challenge to processing solutions: Minerals Engineering and Critical Minerals ’26

A recent review in Minerals Engineering provides a timely assessment of one of the biggest challenges facing the critical minerals sector: how can countries develop secure rare earth elements (REE) supply chains in a world where production and processing remain heavily concentrated in China?

The review examines US domestic REE resources and projects, processing methods, emerging production capacity, non-traditional feedstocks and recycling. It also highlights the need for further R&D and, crucially, for the development of domestic expertise in REE separation and refining.

These are not simply US issues. They are at the heart of the global critical minerals challenge and they provide a timely introduction to the technical programme of Critical Minerals ’26, taking place in Cape Town in November.

As media partner to the conference, Minerals Engineering is particularly well placed to highlight the close relationship between the research published in its pages and the work that will be presented at the conference. The Minerals Engineering review makes an important point: identifying REE resources is only the beginning. The real challenge is developing economic and technically effective flowsheets to concentrate, extract, separate and refine the individual rare earth elements. Critical Minerals ’26 contains a whole session devoted to this challenge.

The programme begins with REE preconcentration and gangue rejection from monazite ore, followed by research into the beneficiation of yttrium and neodymium from an urban deposit. Later in the day, delegates will hear about reagent schemes for REE flotation and the optimisation of flotation from phosphogypsum.

These papers demonstrate the diversity of potential REE feedstocks. Traditional mined ores are being joined by industrial residues, urban deposits and waste materials, precisely the kind of non-traditional resources highlighted in the Minerals Engineering review.

And the programme goes further. Research from South Africa will examine REE extraction from coal fly ash and coal-derived ashes, while another paper investigates the influence of pH-redox conditions on recovering REEs and iron from discard-coal leach solutions.

The message is clear: future REE supply will not necessarily come from conventional mines alone. The review also highlights recycling as an important part of the emerging REE supply landscape. This is another area where the Critical Minerals ’26 programme provides a strong practical counterpart. On the second afternoon, delegates will hear about precipitation of REEs in materials recycling, recovery of REEs from spent computer hard disks using phosphoric acid and deep eutectic solvent leaching, and a life-cycle assessment of mixed REE oxide recovery from end-of-life NdFeB magnets.

These are particularly significant developments because NdFeB magnets contain some of the REEs that are strategically important to modern technologies. Recovering them from end-of-life products could provide a secondary source of supply while reducing dependence on primary mining. The conference therefore moves beyond the question of where can we find more REEs to the more fundamental question of how can we recover them efficiently from everything from ores to industrial wastes and discarded technologies?

Perhaps the most important connection with the Minerals Engineering review is the emphasis on processing expertise. The review points out that many countries have limited REE production capacity and relatively little expertise in REE processing. Developing alternative supply chains therefore requires more than investment in mines. It requires scientists, engineers, metallurgists and process developers capable of designing and operating the separation technologies needed to turn resources into saleable products.

The Critical Minerals ’26 programme reflects this need. Across its 39 presentations, researchers from universities, research organisations and industry will examine beneficiation, flotation, leaching, solvent extraction, ion exchange, precipitation, hydrometallurgy, recycling and process development across a wide range of critical minerals.

And REEs run like a thread through the programme. From monazite beneficiation and REE flotation from phosphogypsum, through coal-derived resources, acid mine drainage, recycling processes, hard-disk magnets and NdFeB magnet recycling, the papers demonstrate just how broad the search for future REE supply has become. The journal review sets out the strategic context: supply-chain concentration, the drive to establish alternative production, the development of domestic separation capacity and the need for R&D.

The conference programme shows that this research is already happening. It shows researchers tackling the difficult mineral processing questions that will determine whether new REE resources, conventional and unconventional, can actually contribute to secure supply.

And that is ultimately the purpose of Critical Minerals ’26: to look beyond the identification of critical mineral resources and focus on the processing and recycling technologies required to turn those resources into resilient supply chains. The conference explicitly covers processing from primary and secondary sources and recycling, including some of the most challenging materials associated with the circular economy. Critical Minerals ’26 offers an opportunity to see many of these emerging technologies first-hand and to meet the researchers and companies working to build the next generation of critical mineral supply chains.

The REE challenge identified in the pages of Minerals Engineering will be very much alive in Cape Town this November.

#CriticalMinerals26
#MEIBlog

Recovering silver from solar panels using flotation

Solar panels are one of the defining technologies of the energy transition. But as the first generations of large-scale photovoltaic installations reach the end of their useful lives, a new challenge is emerging: what do we do with millions of tonnes of spent panels?

Australia is particularly exposed to this question. Around one in three Australian households has rooftop solar, and the country is expected to generate around one million tonnes of solar panel waste by 2035. Although panels contain large quantities of glass and aluminium, they also contain smaller quantities of higher-value materials, including copper, silicon and silver.

Silver is used because it combines exceptionally high electrical conductivity allowing tiny quantities of a very valuable metal to be distributed across a huge number of microscopic conductive pathways.

Silver represents only a tiny fraction of the mass of a photovoltaic module. The Queensland Government's recent solar-panel recovery pilot, for example, estimated silver at just 0.003% of panel mass. Yet across millions of panels, even these small quantities add up. The Silver Institute reported photovoltaic demand of 193.5 million ounces of silver in 2023, highlighting just how substantial the solar industry's consumption of the metal has become.

However the silver is finely distributed, embedded within the metallisation of the cell and bonded into the surrounding material. Recovering it selectively is therefore a separation problem and that is precisely where mineral processing enters the picture. Recent research from the University of Newcastle's Centre for Critical Minerals and Urban Mining, together with the ARC Centre of Excellence, published in the July issue of Minerals Engineering, has demonstrated that froth flotation could provide a new route for recovering silver from end-of-life photovoltaic cells.

Traditional research into silver recovery from end-of-life photovoltaic modules has focused heavily on hydrometallurgical approaches, particularly acid leaching. Leaching can be effective, but treating the entire feed chemically creates its own challenges. Large quantities of reagent may be required, and much of that reagent is effectively being used to process material that contains little or no silver.

The University of Newcastle work applies froth flotation as an upstream selective recovery step for metallic silver from end-of-life photovoltaic cells. In laboratory-scale experiments, delaminated cells from waste solar panels were processed using conventional flotation reagents and the results were striking. In a rougher flotation test using tap water, the researchers achieved approximately 98% silver recovery, with a 32-fold upgrade. The flotation response was also rapid, with around 80% recovery achieved within the first minute and around 90% after approximately three minutes. Perhaps most importantly from a flowsheet perspective, flotation reduced the material requiring subsequent leaching to just 2.8% of the original feed.

The researchers' cleaner-stage experiment illustrates the potential. A rougher-cleaner configuration increased the upgrade to approximately 63, at around 87% silver recovery, producing a concentrate containing approximately 47 wt% Ag.

Of course, these are only batch laboratory results rather than evidence of a commercial-scale flowsheet. In a recent preprint they have reported impressive continuous steady state results processing the silicon wafer sourced from almost half a tonne of solar panels, bordering on 100% silver recovery with 83-fold upgrade to around 50 wt% Ag.

There is still more work to be done around feed preparation, liberation, circuit configuration, reagent optimisation, scale-up and economics. But the conceptual leap is significant. This is exactly the sort of development that demonstrates why the scope of flotation continues to expand.

MEI's Flotation '27 will bring together researchers and practitioners to discuss everything from fundamental reagent chemistry and bubble-particle interactions to flotation kinetics, hydrodynamics, scale-up, circuit design, modelling, control and environmental considerations. The solar-panel work touches on almost all of these themes.

These are not simply questions about recovering silver. They are questions about how the mineral-processing toolbox can be adapted to the emerging world of secondary resources.

The ARC Centre of Excellence is a significant University of Newcastle credential. The fact that Newcastle was awarded $35m to lead a national centre, alongside universities such as Queensland, Melbourne, Monash, New South Wales and Curtin, is strong evidence that the research group is regarded as a leading Australian centre in this area and the Newcastle group has always had a strong involvement with MEI's flotation conferences. Their involvement in the solar-recycling research is an interesting illustration of how expertise developed around conventional mineral processing problems can be transferred to entirely new resources.

The energy transition is creating a paradox. Technologies designed to reduce environmental impact require enormous quantities of materials. Those materials have to be mined, processed, manufactured and eventually recovered. The challenge is therefore not simply to build more solar panels, batteries, wind turbines and electric vehicles. It is to develop systems capable of recovering the materials contained within them when they reach the end of their useful lives. That is where mineral processing has a vitally important role.

Since publication of this post Flotation '27 has been re-scheduled to September 20-23. 2027

#Flotation27

#MEIBlog

August summary: the solar eclipse and a remarkable Cornish museum

August opened up with two more heatwaves, leading to drought conditions over most of England, including Cornwall. 

A parched Falmouth

The beaches have been packed, no more so than on the 12th of the month. August 7th-16th was  Falmouth Week, which  grew out of a sailing regatta whose roots go back to 1837. Today it's a Cornish mixture of sailing, harbour activity, live music, family events, parades and spectacular displays, bringing the town alive.

The 12th was particularly special as the Wednesday is usually dominated by an evening display by the RAF's Red Arrows, but this year there was another, more low-key evening air display and by an extraordinary coincidence the air display coincided with a 95% partial solar eclipse, the most significant solar eclipse visible from Cornwall since the total eclipse of 1999.

The aerial performances took place in the evening, from around 6pm, with the eclipsing Sun creating the backdrop as an eerie twilight descended.

Falmouth's Gyllyngvase beach at 6pm

95% totality just after 7pm

Although this was a rare occurrence I have to admit to being slightly underwhelmed. Maybe I still have in my mind exactly 27 years previously when Falmouth was on the line of totality. Although the weather was awful and the eclipsed sun was not visible I will always remember the slightly frightening sight of the black shadow racing across Falmouth Bay towards us and pitching us into total darkness as it passed.

August 11th 1999: 11am and a few minutes later

On the day after the eclipse many homes were destroyed and wildfires raged in parts of Britain as one of the highest temperatures of the year was recorded.

This summer is the hottest on record in the UK and much of Europe is on fire. The overwhelming consensus of the global scientific community is that human activity is the primary driver of current climate change (see posting of 24 August), so is 2026 the coolest year we will experience? It is an uncomfortable question, but perhaps one worth asking. The World Meteorological Organisation estimates an 86% chance that at least one year between 2026 and 2030 will be warmer than the current record year, 2024. It also puts the chance of at least one year temporarily exceeding 1.5°C above the pre-industrial average during that period at 91%. These are probabilities, not predictions that every year will be hotter than the last, since natural variations such as El Niño and La Niña will continue to cause fluctuations. But the underlying trend is clear: the baseline on which those fluctuations occur is getting warmer.

There is also a darker reminder of what a warming world can mean beyond heatwaves and wildfires. Last week, catastrophic flash floods struck Nepal after a section of glacier collapsed in the Himalayas, sending an avalanche of ice, rock and water downstream. Hundreds of people have died and thousands remain missing, with homes, roads, bridges and other infrastructure destroyed. Scientists caution that it is too early to attribute this particular event directly to climate change, but the disaster occurred in a region experiencing rapid warming and accelerating glacier loss. As glaciers retreat and high-mountain environments become increasingly unstable, the risks of landslides, avalanches and sudden floods are growing.

The Nepal disaster is a reminder that climate change is not simply a story of temperatures rising year after year. It is about a changing climate system, in which familiar patterns and natural hazards can become more dangerous. Heatwaves, wildfires, extreme rainfall, floods and the destabilisation of glaciers may look like separate events, but they are all part of a world in which the environmental baseline is shifting.

On a lighter note, last Wednesday Barbara and I celebrated our 59th wedding anniversary by visiting a remarkable museum in St. Ive (not to be confused with St. Ives), near Liskeard, 55 miles from Falmouth. The Story of Emily steps into the life and legacy of Emily Hobhouse, the famous humanitarian who was born in St. Ive, and lived from 1860 to 1926. She became internationally known for speaking out against the treatment of Boer women and children during the Second Boer War.

The British Army used a "scorched earth" policy, destroying farms and moving Boer civilians into concentration camps. Emily travelled to South Africa in 1900 to see the situation for herself. In January 1901 she visited the Bloemfontein camp, where around 2,000 women and children were being held. She was horrified by what she found. Women and children were living in terrible conditions, with inadequate food, sanitation and shelter. She documented what she saw and brought the situation to the attention of the British public and politicians. Branded an hysterical woman and traitor by many, she refused to be silenced, saving thousands of Boer women and children, leading social reforms, and single-handedly challenging an empire at war.

I remember visiting Bloemfontein in 1982. It was the capital of the old Orange Free State, one of the two Boer republics that fought Britain. The concentration camp there became one of the most important symbols of the suffering of Boer civilians and the memory was still very much alive, with some turning away as I asked for directions in English. 

Bloemfontein has the Anglo-Boer War Museum and the National Women's Memorial (left), which commemorates the women and children who died in the camps. The museum specifically tells the story of the concentration camps and the suffering of civilians, and although speaking English can cause some resentment in this predominantly Afrikaans city, ironically Emily became enormously respected among Afrikaners because she had stood up for Boer women and children and the Bloemfontein War Museum presents her positively, describing how her visit exposed the conditions in the camps and helped bring about improvements. 

She was invited to unveil the Women's Memorial in 1913, but she was too ill to attend. The wife of President Steyn unveiled it on her behalf, reading her prepared speech at the ceremony. 

Emily died in 1926. Her funeral in London was remarkably small and received little attention. A few months later, however, South Africa gave her a very different farewell.

Her ashes were sent to South Africa, where Isabella "Tibbie" Steyn, the widow of former Orange Free State president Martinus Steyn and a close friend of Hobhouse, helped organise a state funeral in Bloemfontein, the first state funeral for a woman in South Africa. It took place on 27 October 1926 at the National Women's Monument attended by more than 20,000 people. Shops and businesses closed and flags were flown at half-mast and Emily's ashes were placed at the monument.

I'm sure that South African visitors to Cornwall, and anyone interested in South African history, would find the Story of Emily of great interest. The museum is deliberately divided into two very different experiences:

• The Victorian Rectory shows Emily's childhood and early life in rural Cornwall, with restored rooms and gardens recreating the world in which she grew up.
• The War Rooms provide a modern, dark, immersive exhibition about her experiences in South Africa and the concentration camps. It uses original objects, photography, film, animation, sound and virtual reality to put visitors into the historical setting.

The contrast is intentional: the peaceful Cornish home represents Emily's early life, while the stark War Rooms represent the traumatic world she encountered later. One particularly striking feature is that the War Rooms are kept around 26°C, helping recreate the heat of South Africa. The exhibition takes visitors through different environments and uses sound, mirrors and visual effects to convey the scale and human impact of the camps.

Inside the rectory, Emily's Cornish family home

Visiting a "virtual" Boer farmhouse stoep

A devastated farmhouse during Kitchener's scorched earth policy

As well as being overshadowed by the ongoing wars in Iran and Ukraine, August will also be remembered for the loss of two iconic singer-songwriters, Bonnie Tyler and Dolly Parton, whose distinctive voices, unforgettable songs and remarkable careers left an enduring mark on popular music. Their deaths brought an end to two extraordinary chapters in music history on both sides of the Atlantic.

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Is replacing copper with aluminium the most effective way to deal with the looming global copper shortages?

A series of recent studies by reputable organisations have all forecast significant global shortages of copper starting in the mid 2030s.

In a keynote lecture at Critical Minerals '26, Martin Lynch, of the University of Queensland, will argue that substitution is the likely remedy.

Martin will highlight three main points:

• Substitutes (including PEX piping, fibre optic cables, and aluminium tubes) supplied 40% of the global demand for copper over the past 50 years, during which there were two periods of shortage.
• Of the copper consumed globally in 2023, about 70% could have been replaced by substitutes (including aluminium wiring, cables and tubes) without significant negative impacts.
• The main barrier to using substitutes is copper’s reputation for quality, and the reluctance of manufacturers and consumers to trust substitute products (including in building wire, aircon HX and renewables cabling) even though they are proven to work just as well as copper.

According to the author, history has shown that the barriers to substitution tend to crumble quite quickly when shortages appear.

Martin Lynch is the son of the late Prof. Alban Lynch, the first Director of Australia's JKMRC. He graduated in 1982 as a BE (Chem) from the University of Queensland (UQ) and worked in a series of mining companies including Rio Tinto and Iluka Resources.  During that time he wrote Mining in World History, a book which traces the history of global mining from 1500 to the 1970s (posting of 13th July 2026).  

He changed career path in 2009, becoming the owner and manager of a renewables energy business.  This was sold in 2024, following which he began a PhD at UQ focusing on the use of substitutes for copper with the aim of managing forecast global copper shortages.

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Is CO₂ Still the Most Maligned Gas in History? — Eight Years On

In the middle of August homes were destroyed as wildfires brought devastation to parts of Britain. The apocalyptic vision of the world on fire, with wildfires raging across Europe and the UK, prompted me to look again at a post I wrote eight years ago, Is CO₂ the Most Maligned Gas in History?. I wrote it in December 2018 when I was sceptical of the evidence attributing most recent climate change to human activity. Eight years later, I think some of the questions I raised remain worth asking, but the scientific answers have become considerably clearer.

The post is still relevant as a historical account of the debate, and some of its points remain valid. CO₂ is essential to life, it is quite different from conventional air pollutants, and mining will be essential to any large-scale transition away from fossil fuels. But its central scientific position, that climate change was probably mainly natural and that the contribution from human activity was uncertain, is no longer supported by the evidence.

In the 2018 article I wrote: “An increase in 40% [of CO₂] seems a lot, but in absolute terms this is an increase in concentration from just under 0.03% to the present level of just over 0.04%. Can this small increase have such a profound effect?” 

The science can now provide a much better answer to that question.

We can also now be much more precise about where the additional CO₂ is coming from. Scientists can distinguish fossil-fuel carbon from naturally circulating carbon by examining the isotopic “fingerprint” of atmospheric CO₂. Fossil fuels contain virtually no radioactive carbon-14, because it has decayed away over the millions of years that they have been underground. They are also relatively depleted in carbon-13. By measuring these isotopes in atmospheric CO₂, scientists can identify the contribution from fossil fuels and distinguish it from carbon being exchanged naturally between the atmosphere, oceans and living organisms.

This provides an important independent line of evidence. We are not simply assuming that the additional CO₂ is coming from burning coal, oil and gas because fossil-fuel use has increased at the same time as atmospheric CO₂. The chemical and isotopic fingerprints show that the extra carbon has the characteristics expected of ancient plant material,  precisely what we would expect from fossil fuels. The National Oceanic and Atmospheric Administration notes that these measurements can be used to determine what proportion of CO₂ in an atmospheric sample is derived from fossil fuels.

The important thing is not simply the percentage of the atmosphere occupied by CO₂, but the physical properties of the molecule and its effect on the Earth's radiative balance. CO₂ absorbs infrared radiation at specific wavelengths. Increasing its concentration makes it more difficult for the Earth to radiate energy back into space. The climate system then warms until outgoing radiation once again balances incoming energy. CO₂ does not have to make up a large proportion of the atmosphere to have a significant climatic effect.

Furthermore, we are no longer relying simply on correlations between CO₂ concentrations and temperature. The radiative effect of increasing greenhouse gases can be observed directly. NASA explains that its climate instruments measure how greenhouse gases affect the movement of infrared radiation through the atmosphere, and a 2024 NASA and Jet Propulsion Laboratory study directly measured how increasing atmospheric CO₂ reduces the Earth's ability to emit infrared radiation into space.

Looking back at my 2018 post, I would therefore no longer argue that the human contribution to recent warming is fundamentally uncertain. The evidence is now much stronger that the current rise in atmospheric CO₂ is overwhelmingly the result of human activity, principally the burning of fossil fuels, and that this increase is the dominant cause of the warming observed since the pre-industrial period.

But that does not make CO₂ a “villain” in the conventional sense. It remains an essential gas for life, occurs naturally, and has played an important role in regulating Earth's climate throughout geological history. Nor does recognising the importance of CO₂ mean that all environmental problems can be reduced to carbon dioxide. Conventional air pollutants such as particulate matter, sulphur dioxide and nitrogen oxides remain important threats to human health.

What has perhaps become even more relevant since I wrote the original article is the other side of the argument. If we accept the need to reduce greenhouse-gas emissions, then mining, a major emitter of CO₂, is not the enemy of the green revolution,  it is one of its essential foundations. Wind turbines, solar panels, electricity networks, batteries and electric vehicles all require large quantities of metals and minerals. The energy transition will therefore require more mining, not less (see posting of 10 April 2023).

The scale of the challenge is illustrated by the graphic below. In 2023, the world was still consuming enormous quantities of coal, oil and natural gas, with China and the United States among the largest consumers. Replacing an energy system of this scale is clearly going to be a very substantial undertaking.

Source: elements.visualcapitalist.com

This brings us back to the paradox at the heart of this article. If we accept the need to reduce greenhouse-gas emissions, mining is not the enemy of the green revolution, it is one of its essential foundations. The challenge is not simply to “stop mining”, but to produce the minerals needed for decarbonisation while reducing the environmental footprint and carbon intensity of their extraction and processing.

In that sense, my 2018 article is worth revisiting not because its scepticism about human-caused climate change has been vindicated, but because its underlying question has become even more important: how do we reconcile our environmental ambitions with the enormous material requirements of a modern, low-carbon society?

This is the paradox we should be discussing now. The route to a lower-carbon world runs, at least for the foreseeable future, through a mining industry that itself has to become substantially lower carbon.

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August Cornish Mining Sundowner, and Cornwall's next Industrial Chapter?

A cool evening, a rare occurrence this long hot summer. It was a pleasant 17C last night in Falmouth for the Cornish Mining Sundowner at the Chain Locker, with a modest attendance of around a dozen.

The Chain Locker sits by Falmouth's inner harbour, the more sheltered, upstream section around the town quays, while the wider Falmouth Harbour extends out towards Carrick Roads (the Fal estuary) and the sea, so there was something rather appropriate about discussing Cornwall’s industrial future from the Chain Locker last night.

The Inner Harbour and the Chain Locker

Look across Falmouth Harbour and you see centuries of working history, ships, quays, docks and warehouses. But the harbour may also have a role in Cornwall’s next industrial chapter.

A proposed £150 million redevelopment of Falmouth Docks aims to modernise the ageing infrastructure, increase cargo capacity and support the emerging floating offshore wind industry in the Celtic Sea. Importantly for Cornwall’s renewed interest in critical minerals, the plans could also create new import and export facilities supporting Cornish lithium and battery manufacturing.

Cornwall once exported copper and tin through its ports to markets around the world. Could Falmouth once again become part of a supply chain built around Cornwall’s natural resources, this time alongside renewable energy and modern marine engineering?

There is, however, another side to the story. The redevelopment has attracted opposition from oyster fishermen and environmental campaigners, particularly over proposed dredging and its potential impact on the Fal estuary and its habitats. So the question isn't simply whether Cornwall can bring industry back, it is what sort of industry we want, and how we balance economic opportunity with the environment and communities that make Cornwall special.

Join us at the Chain Locker for the next sundowner, which will be on Thursday September 17th, from 5.30pm.

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