The XXXI International Mineral Processing Congress (IMPC) was held at National Harbor, Maryland, USA, from September 29th to October 3rd 2024. The IMPC's have a 2-year cycle, but due to Covid disruption this was the first since Moscow in 2018 and the first for me since 2016 in Quebec City.
The Congress, attended by 751 delegates from 39 countries, was hosted this year by the Society for Mining, Metallurgy and Exploration (SME) and had as its theme Mineral Processing for the Energy Transition, addressing how mineral processing is playing an increasingly important role in securing the cost-effective supply of a wide range of minerals for a sustainable and stable future.
This is not a report on the technical sessions, as there were over 400 papers presented in the parallel sessions and by poster. It is not often, however, that you get the chance to meet up with such a large number of mineral processors, so this is essentially a pictorial record of my encounters during the week, and I hope that the 66 photos below will reflect the overall atmosphere of the event. I’ve added captions only to photos where I could identify all the faces, so I apologise if your name isn’t included.
Sunday September 29th
The congress got underway late afternoon with an informal 2-hour opening reception in the exhibit hall, the first chance to meet the 23 exhibitors and to catch up with many familiar faces as well as many new ones. It was particularly good to see so many young people, the lifeblood of the minerals industry.
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| Ted and Claire Bearman, KP van der Wielen and Adam Johnston |
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| Jannie van Deventer, Kevin Galvin, Jacques Eksteen and Aubrey Mainza |
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| Jayson and Sheri Ripke with Nick Hazen (centre) |
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| Kristian Waters and daughter, Gonzalo Larrabure and Pablo Brito-Parada |
I was surprised and delighted to see my old friend and former Camborne School of Mines colleague Dave Osborne, and his wife Hazel. Dave won't admit it, but he played a big part in kick-starting my career, getting the 1st edition of Mineral Processing Technology off the ground in the mid 1970s (posting of 10 August 2015). Dave was representing Somerset International, providing innovative technologies for sustainable tailings management and resource recovery from tailings.
Monday September 30th
Early morning coffee provided another chance to catch up with people, including very strong contingents from China and Brazil.
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| Coffee break (left) in the impressive atrium |
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| Chinese delegates |
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| Brazilian delegates |
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| Ralph Holmes, Courtney and Miriam Young |
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| Silvia Franca, Priscila Esteves and Seher Ata |
At the Bookstore was Osvaldo Bascur, with his new book "The Engineering Science of Mineral Processing" (posting of 21 November 2023). Osvaldo is hoping to present a paper on the theme of his book at Flotation '25 and says he is looking forward to my 80th birthday celebrations at the event!
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| Osvaldo with the Bookstore's Melissa Serdinsky |
The morning sessions then got underway with four plenary lectures (see also posting of 11th August) addressing the critical issues affecting the mineral processing sector.
Karen Hanghøj, the Director of the British Geological Survey, showed how mineral raw materials are important for society in general, and for the transition to a green economy in particular. They are key for achieving the goals set out in COP21 and for achieving several of the United Nations Sustainable Development Goals. Emerging energy and mobility technologies create a strong demand for certain raw materials, where demand will dramatically exceed current production in the next decades. Potential scarcity and criticality of these materials might negatively impact the energy transition, and the downstream supply chain significantly. Sustainable and responsible sourcing of these metals is thus going to important on a global level in the decades ahead. To meet these challenges we need to design smarter solutions for the sustainable extraction, processing and use/repairing/recycling of raw materials from both primary and secondary sources. Furthermore, we must ensure that used materials and products find their way into new product lifecycles in an energetically and economically meaningful way. We need to maintain products and materials in the economy as long as possible through waste valorization, industrial symbiosis, reuse, repairing, remanufacturing and recycling.
Richard Williams, Principal and Vice-Chancellor at Heriot-Watt University, UK also showed how global demand and the societal need for minerals and metals places mineral processing at the heart of the energy transition agenda. Practices to enhance the sustainability of minerals processing are part of a global green innovation supply chain. In looking to the future, pathways to assure a ‘low carbon minerals processing’ there is a need to examine its role in a range of domains and Richard presented some future scenarios, which he will discuss further at next month's Critical Minerals '24 in Cape Town.
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| With Richard Williams |
Markku Teräsvasara, President, Metso Minerals, Finland showed how maximising process circuit productivity requires a systematic and methodical approach as well as breaking away from conventional thinking. By integrating key elements such as optimised sustainable flowsheets, high-performance process equipment, digitalisation, and automation, substantial improvements can be achieved. In the presentation, Markku outlined a three-tiered strategy with practical examples to achieve remarkable productivity enhancements.
Finally, Mallory Clites, Technology Deployment Manager, Batteries and Critical Materials at the U.S. Department of Energy discussed the importance of critical minerals in battery production.
Following the keynotes there was an update on IMPCs. I was pleased to see that MEI's comminution consultant, Aubrey Mainza, has been elected Vice-President of the International Minerals Processing Council. Aubrey is also the Chairman of the next IMPC, to be held in Cape Town from October 18-22, 2026. The 2028 congress will be held in Melbourne, and there have been bids from Changsha, China, and Rio de Janeiro, Brazil for 2030.
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| Aubrey with his University of Cape Town team |
Lunch was held in the exhibition area, which also displayed the poster presentations.
There was very strong representation at the exhibition from two of our MEI Conference sponsors.
Metcelerate is sponsoring Comminution '25 and Flotation '25 and will be exhibiting at both. Metcelerate offers professional development for young and talented engineers through a unique, flexible, global and workplace-based training program, focused on plant operations.
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| The Metcelerate team |
Nalco, a major IMPC sponsor, is also a sponsor of Flotation '25 and will be exhibiting at the event. Nalco Water, an Ecolab company, plays an important role in the management of water, from the time it enters a facility until the moment it is returned back into the environment.
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| Nalco delegates |
Lunch was followed by three keynote lectures.
David Dreisinger, of the University of British Columbia, Canada discussed nickel and cobalt, critical elements for the electric vehicle transition, and new strategies being developed for recovering nickel and cobalt from sulphide and laterite resources to meet the expected future demand. These include pressure oxidation of nickel sulphide concentrates to form battery chemical precursors, the CO2 Mineralisation and Selective Leaching (CMSL) process for limonite and saprolite treatment and the ATLAS Materials process for low carbon nickel and cobalt from saprolite ores.
Enabling the energy transition requires the mining industry to generate unprecedented amounts of metals such as Li, Cu, Co, Ni and the REE, said Megan Becker, of the University of Cape Town, who is MEI consultant to Process Mineralogy '24. Dependent on metal concentrations, these geochemically scarce metals may occur in discrete minerals, or substitute for other elements in more common minerals subsequently forming complex, refractory ores. Megan highlighted the pivotal role of process mineralogy and geometallurgy in facilitating the sustainable processing of these complex ores, thus ensuring a successful transition towards cleaner energy sources.
In her keynote lecture Saskia Duyvesteyn, of Rio Tinto, USA, asked how can we re-innovate innovation in the mining industry? The mining industry is facing unprecedented pressures from environmental, social, economic, and regulatory factors. To survive and thrive in this complex and dynamic context, the industry needs to re-innovate its innovation processes and practices. Saskia identified drivers, barriers, and enablers of innovation in the mining industry, and suggested some directions for future research and practice, such as developing new frameworks and tools to support innovation, fostering cross-sectoral and multidisciplinary collaboration, and enhancing the social license and sustainability of mining innovation.
Following the keynotes were nine parallel sessions, and the papers are available as a Proceedings via the SME Bookstore. Parallel sessions are always a major concern and criticism of IMPCs but in fairness they are an inevitable consequence of large numbers. Many people, particularly academics, can only receive funding to attend events such as these if they are presenting a paper, so in order to attain high numbers, many papers must be accepted and in order to accommodate them many parallel sessions are required.
IMPCs are intended to bring mineral processors of all disciplines together to encourage debate and some lateral thinking but parallel sessions essentially segregate people into their specialties. Even flotation scientists were segregated this afternoon with four parallel sessions on flotation: application of flotation for battery recycling; sulfide flotation applications; hydrodynamics and gas dispersion; and industrial minerals flotation.
But after a long day, there was a further sea of mineral processing faces in the evening during the very relaxing exhibit hall welcoming reception.
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| Indresan Govender and Taswald Moodley |
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| At the CMD Consulting booth |
There were a number of Camborne School of Mines alumni at the reception and in the photo below are KP van der Wielen (2013), Ted Bearman (1987), Claire Bearman (1990), Daniela Munoz (2009), Dave Meadows (1985) and mineral processing lecturers Dave Osborne (1970-75) and me (1974-1996).
It was good to see much interest in the exhibition booths. Derrick Corporation is a family-owned and operated company focused on pioneering fine separation technology, leading the industry in the design and manufacture of patented high-frequency vibratory screening machines and screen surfaces. The company is a sponsor of Comminution '25.
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| Derrick Corporation |
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Juan Yianatos and Paulina Vallejos with Hasan Altuncu and Eyup Altuncu,
of the Turkish company FKK Mining |
Tuesday October 1st
Kevin Galvin, of the University of Newcastle, Australia, is the inventor of the Reflux Classifier and the Reflux Flotation Cell, and he presented the first of the three keynote lectures this morning, showing how ultrafine colloidal particles, otherwise known as slimes, impede gravity and flotation separations to a degree that is often not widely appreciated. These particles produce exponential increase in suspension viscosity and contamination of mineral and bubble surfaces. He showed that the Boycott Effect, operating with counter current washing via fluidisation provides the essential elements for effective desliming. The approach forms the basis of a platform technology that includes the Reflux Classifier for gravity separation, the Reflux Flotation Cell, and the Graviton for ultrafine desliming. Kevin described the synergy between the Boycott Effect and the fluidisation, including the synergy between these different technologies.
Rare earth elements are critical to many modern devices. Much of their low market availability and relatively high cost are related to their similarities in properties, which make them difficult to separate. Michael Free, of the University of Utah, provided a brief overview of various fundamental principles that can be applied to separate rare earth elements. The principles that establish what is possible in terms of extraction, separation, and recovery of rare earth elements and critical elements are based on the atomic level properties of the elements as well as the processing methods with related time, temperature, and mass transport parameter effects.
Mining is reliant on inputs of both water and energy, without these it would not be viable, said Laurie Reemeyer, of Resourceful Paths, Canada. Water is a more complex utility than energy as both quantity and quality attributes must be considered. Competition for water supply and environmental effects of mining on water resources have the potential to create tensions between indigenous groups, local and regional communities, and industry, leading to political instability if not properly managed. How mining companies deal with fresh water is often the main concern of the community at large.
The coffee break gave me the chance to catch up with a few more mineral processors, then the world of water in mining was one of the nine parallel sessions which followed the keynotes, taking us up to noon and lunch two floors down in the exhibit hall.
Although four years late, due to the Covid pandemic, it was a pleasure to present the 2019 MEI Young Person's Award to Nikhil Dhawan, now an Associate Professor in the Department of Metallurgical and Materials Engineering at the Indian Institute of Technology. Full details are on the posting of 7th May 2020.
In the exhibit hall I called in to see Adrian Singh, of GoldOre, South Africa, a sponsor of Flotation '25. GoldOre supplies the MACH Reactor, a hydrodynamic cavitation/shear reactor that generates pico-bubbles, that selectively nucleate on and aggregate valuable fine mineral (below 20 microns) to a size that is easier to float in flotation plants.
Weir is a sponsor of Comminution '25 and a major sponsor of the IMPC. Weir is a global leader in innovative mining technology and recently launched the all-new ENDURON® Orbital range of vibrating screens. Engineered for sand and aggregate, construction, and small tonnage mining operations, the new screens are designed to meet the most demanding of applications as they feature an all-bolted construction, significantly improving reliability by eliminating welding in high-stress areas, the leading mode of failure in vibrating screens. Weir announced last week the award of a £25m contract to provide industry-leading energy efficient, sustainable solutions to the next phase of OCP Benguerir and Louta greenfield phosphate projects in Morocco. The full order includes a range of both WARMAN® slurry pumps and CAVEX® hydrocyclones.
Two more keynotes after lunch. Pablo Brito-Parada of Imperial College, UK, is the editor-in-chief of Minerals Engineering and he described advances in model predictive control (MPC) for flotation. MPC strategies rely on the model that represents the dynamics of the process, which has often hindered its application in flotation. Pablo presented a new dynamic flotation model that incorporates froth physics, and which is suitable for MPC. Unlike other flotation models for control, the model includes important variables related to froth stability and pulp-froth interface physics, and incorporates phenomenological equations for froth recovery and entrainment. The model is the basis for an economic MPC strategy that was implemented in both simulations and a laboratory-scale flotation rig, with encouraging results for its exploitation in industrial flotation circuits.
Dry processing is important for the future of mineral beneficiation to reduce water consumption and improve sustainability, especially with the impending energy transition, said Jayson Ripke, of McCarl's Technical Services, USA. Dry unit operations include grinding, magnetic, gravity, electrostatic, screening, and sensor-based separation. Jayson reviewed the current state of the art in dry beneficiation and provided two case studies used in operation.
And dry processing was one of the nine parallel sessions following the keynotes, which included four more sessions on flotation!
The evening cultural reception was a very pleasant couple of hours, with classic American flavours both in food and drink on offer. It was a great networking event and Dave Osborne and I, both former Camborne School of Mines lecturers, were pleased to congratulate 1985 graduate Dave Meadows on his promotion to Chief Technology Officer with Bechtel Mining and Metals, USA.
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| With Dave Meadows and Dave Osborne |
Dave Meadows is a man of many talents and even provided half of the the background entertainment during the reception.
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| Dave Meadows and Jason Tomasino of Metso |
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| Chalmers University, Sweden |
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| With Peter Radziszewski |
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| Helmholtz Institute Freiberg for Resource Technology, Germany |
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| Bourbon tasting with Jan Cilliers |
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| Fardis Nakhaei, me, Jim Finch, Mulenga Chibesa |
Wednesday October 2nd
The day got underway with three keynote lectures, before splitting into the morning nine parallel sessions.
The energy transition will require unprecedented quantities of metal. To help satisfy this demand, it will be imperative that flotation be conducted optimally, said Kym Runge, of SMI-JKMRC, Australia, in the first keynote lecture. The mining industry is currently undergoing a transformation with many new technologies being developed that have the potential to improve flotation performance. New flotation machines are emerging that can recover coarser and finer particles, traditionally not recovered well during flotation. Flotation reagents with increased specificity have the potential to enable selective separation of minerals of similar chemical structure. New comminution methods are improving the liberation and thus the selectivity achievable in flotation. Advanced ore characterisation tools and improved methods of process measurement provide means of better overcoming bottlenecks in our flotation processes. Kym provided an overview of these emerging new flotation technologies and outlined the challenges that must be overcome to enable fast adoption by what is a traditionally conservative mining industry.
Comminution is an area often singled out by those looking to criticise mining and processing, according to Ted Bearman, of Bear Rock Solutions Pty Ltd., Australia. The sector is often subject to disparaging comments in relation to the energy and water footprint of comminution, particularly as it relates to tumbling mills, use of steel media and the speed of change, but is this fair? Given the rapidity that is demanded in relation to change, the mining sector does struggle, often due to the long life, capital intensity and risk-averse nature of both mining companies and investors, but change is happening, albeit not at the pace that some expect. The rise of compressive grinding, more efficient multi-stage systems, early waste rejection and customised flowsheets, are all examples of changes in the core thinking, but deployment is slow. Ted said that currently, we do not have all the answers, amongst others, we still need to improve our understanding of ore and gangue behavior, how complexity is traded-off against non-traditional metrics, and the role of non-mechanical comminution and scalability of concepts. Many of the changes will be uncomfortable, but our sector can, and has, responded to imperatives in the past and this gives us reason to believe we can continue to do so.
What can we do as engineers to overcome the natural resistance to change within our perceived "risky business"?, asked Richard Johnson, of JohnsonMCS, USA. Mining is a conservative industry and is slow to accept anything new. Richard said that mid-tier companies seem to adapt innovative technology at a faster rate than the majors, but do they take these risks to be more competitive or are they more encouraged to take risks?
During lunch I passed the Scantech booth. Scantech, who will be exhibiting at Comminution '25, provide online elemental analysers, moisture analysers and particle size analysers to monitor and control bulk material applications, optimising plant operations through real-time process control.
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| Scantech |
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| Luis Cisternas and Yesica Botero |
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| Mineral Technologies |
MolyCop is a sponsor of Comminution '25 and a major sponsor of the IMPC. The company is a pioneer supplier of breakthrough technologies and cutting-edge solutions who collaborate with partners to deliver effective outcomes for their customers. They have by far the largest booth in the exhibition.
Following lunch were two more keynote lectures.
New technologies in tailings management continue to emerge and become refined, but the age-old questions remain "why can’t we always put all the tailings back from where they came? Why do we feel compelled to change improved deposition practices? Are filtered tailings a panacea or doomed to mediocrity? Two examples of emerging technologies and their practical applications and limitations were explored by Christopher Hatton, of WSP, USA, in his keynote.
For most of the 20th century, our metallurgical focus has been on metallurgical bulk commodities that could be concentrated, smelted, converted, and refined under less stringent constraints imposed by communities, water availability, safety, and governments, said Jacques Eksteen, of Curtin University, Australia. As ore grades decreased and ores also became more polymetallic, and as the risks around critical minerals became clear, particularly insofar they are used in the renewable energy transition, and compliance to ESG targets became essential, a sea change has been required in how we extract and refine metals. The high-grade requirements imposed by smelters (or pressure leach operations) have become hard to satisfy without significant recovery loss at the mine and concentrators. As the value of water increased in many mining jurisdictions and the industry has become more focused on Circular Economy drivers, the reuse, repurpose and recycle of water and reagents and wastes have become essential. Dry disposal of tailings has also become a major driver to recycle the water and chemicals back to the metallurgical operations. Conventional hydrometallurgical operations, which mostly used either mineral acids such as sulfuric acid, ammonia, or sodium cyanide for metal recovery, has become problematic due to their lack of selective dissolution, the need for expensive post-treatment (neutralisation and detoxification) and the poor ability to recover, recycle and reuse the reagents have become problematic and often not sustainable.
The keynotes were followed by nine parallel sessions. One of these was Extreme Environments and it was good to see my daughter-in-law, Kathryn Hadler, formerly with Imperial College, London, and former editor of International Journal of Mineral Processing, presenting a paper on Mineral Processing on the Moon. Kathryn is Director of the European Space Resources Innovation Centre in Luxembourg.
The main social event of the Congress was the Awards Banquet where outstanding contributions to the global mineral processing community were recognised.
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| Curtin University |
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| Jim Gebhart, Frank Crundwell and Adam Johnston |
In a very low-key evening, Lifetime Achievement Awards were made to Robin Batterham and John Herbst. John Herbst was chairman of the 1995 IMPC in San Francisco and he had proposed the establishment of the IMPC Lifetime Achievement Award for that event. At the San Francisco congress Douglas Fuerstenau was the first recipient of the award. Prof. Fuerstenau regretted that he was unable to attend this year's IMPC and it was sad to hear that, due to illness, John Herbst was also unable to attend to receive his own Lifetime Achievement Award.
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| Robin Batterham and his partner, Hanne |
The Distinguished Service Award was made to Tim Napier-Munn, who was also unable to attend. Tim was my co-editor for the 7th edition of Mineral Processing Technology. The 8th edition was co-edited with Jim Finch and I was pleased to see Jim presented with his 2020 Lifetime Achievement Award (posting of 26th November 2020), made belatedly due to the pandemic.
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| Jim and his wife Lois |
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| With Jim and Sheila Devasahayam |
It was particularly pleasing to see the recipients of the 2024 IMPC Young Authors' Awards called up to receive their awards, representing the future of mineral processing.
Thursday October 3rd
There was only one keynote lecture this morning, but it was an important one, Diana Drinkwater, of Metcelerate, Australia looked at critical skills for critical minerals. The mining industry is currently riding a wave of opportunity generated by new technologies and it is also encouraging to see an acknowledged need for investment in education. The International Mineral Processing Council has conducted several studies aimed at identifying good practice in mineral processing education and the broader environmental factors required to ensure best outcomes. Diana reviewed the work done to date and suggested some actions that directly address the needs of the critical minerals boom. The policymakers may not yet realise how much they need us, but eventually they will, and we need to be ready.
Following Diana's keynote last night's Lifetime Achievement Award winner, Robin Batterham gave his award lecture. Unfortunately I had to miss this as I was returning to UK, but I am sure it was a great success. I have heard Robin speak many times, including in Falmouth, where he gave a keynote lecture at Sustainable Minerals '16. He always has something interesting to say, and he says it so eloquently.
I have enjoyed my week in Maryland, the IMPC, as always, being a great networking event. Chairman John Marsden and his team are to be commended on finding an outstanding venue and putting all this together.
I now look forward to the next major SME event, the Annual Meeting in Denver in February, which will include a symposium honouring Professor S. Koma Kawatra and also the World Gold Conference, so this is going to be a big one. Also next year MEI has its two biggest conferences, Comminution '25 and Flotation '25 in Cape Town.
So, much to look forward to next year, but in the meantime I invite your views on #IMPC2024 and constructive criticisms which may help future IMPCs.
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