Following is a very brief summary of the presentations made over the four days. This summary is intended to guide you to the extended abstracts associated with the presentations, oral and poster, most of which are available online as open-access. Unfortunately not all presenters responded to requests for extended abstracts, but for those that did their names are linked directly to their papers in the online Proceedings. Short abstracts for all technical session papers can be found on the programme on the conference website.
The extended abstracts have not been refereed, but all the presenters have been invited to submit their final papers for peer-review to a virtual special issue of Minerals Engineering.
Over the past few years Artificial Intelligence (AI) has been revolutionising many fields, including comminution, by predictive modelling, AI driven calibration, optimisation and process control or via the use of surrogate models. In the first keynote lecture of the conference, Carsten Schilde, Professor for Digitisation of complex systems in process and production engineering, at TU Braunschweig, Germany, showed how rapid leaps in AI methods are accelerating comminution modelling.
Fine grinding of multi-component systems is of great importance in numerous industries, especially prevalent in minerals engineering and recycling, but there is a lack of systematic studies that describe their grinding behaviour in the micron and submicron range. To address this challenge, Maximilian Tobaben, a research associate at TU Braunschweig, Germany, focused on the description of multi-component fine grinding tests using a model mixture of quartz and limestone through a mechanistic modelling approach.
Innovation and digital transformation are seen as key tools to develop (left) new products and solutions that significantly improve operating processes, particularly in improving energy and water usage while minimizing waste, said Yufan Mu, an R&D Engineer at Molycop, USA. She presented a case study of machine learning's role in optimising mill performance, identifying different mill environments for semi-autogenous and overflowing ball mills using clustering.
Depending on ore texture, minerals can display breakage behavior independently of grain boundaries and result in mostly random breakage or can break along grain boundaries resulting in preferential liberation and non-random breakage. Understanding the fracturing behaviour using tests developed for measuring rock mechanics parameters can inform how rocks and minerals respond to external stresses in comminution applied to particles across different scales. Carolina Carvajal, a PhD Student at the JKMRC, Australia, discussed micromechanics of minerals by nanoindentation, leading to insights into fracture behaviour from onset to propagation.
Tim Lundquist, the Global Director of Mineral Processing Sales with Disa Technologies, USA, described Disa's High-Pressure Slurry Ablation (HPSA) technology. HPSA processes solid feed material in slurry form, propelled by high-pressure pumps through opposing nozzles that generate impinging jets within a collision housing. This process induces particle-to-particle collisions in a high-energy zone, creating intergranular fractures along grain boundaries. Tim reviewed potential applications and future developments. Vivian Moutinho is a PhD Student at the University of Rio de Janeiro, Brazil and she looked at the influence of mineralogy and texture on the fragmentation behavior of iron ores.
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| Vivian Moutinho |
Gauti Asbjörnsson, Associate Professor at the Chalmers University of Technology, Sweden, then explored the potential of signal integration of instrumentation, such as noise, vibration, high-frequency monitoring and vision systems and the implementation of novel analytics, such as fault detection and condition monitoring, to improve the operational performance and lifetime of cone crushers.
The performance of ball mills is influenced by ore characteristics, the design of the mill and the operating conditions. It is common knowledge that the feed characteristics have a significant influence on milling performance. The main feed characteristic considered are ore competence and particle size distribution (PSD). Fortune Mdluli, Metallurgy Leader at Two Rivers Platinum, South Africa showed how the influence of feed PSD on the performance of ball mills in an industrial plant was quantified by a grind curve approach.
Adolph Mwale is Head of Technology Management at Metso, South Africa. He described a study commissioned to develop a model for predicting ball mill performance which incorporates the influence of discharge configuration in addition to other operational and design variables.
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| Adolph Mwale (right) |
In the final paper of the day Arno Kwade, Head of Institute TU Braunschweig, Germany, discussed dry fine grinding in ball mills and stirred media mills. which is becoming of increasing importance. In recent years, tumbling ball mills and stirred media mills have been designed for dry processing and up-scaled to industrially relevant sizes. However, the transport of the dry powder through the mill chamber, which influences the holdup and mean residence time. is very much different from wet milling and Arno discussed the transport and milling behaviour in the mill as a function of the flowability of the powder.
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| Arno Kwade (centre) |
More on Day 1
Tuesday April 1st
Technical Session 3
Chairpersons: Richmond Asamoah (University of South Australia, Australia) and Bern Klein (University of British Columbia, Canada)
Energy efficiency is a primary focus for the mineral processing flowsheets of the future. In recent years, High Pressure Grinding Rolls (HPGR) have demonstrated significant energy savings as compared to conventional SAG mill circuits. Investigations have demonstrated the potential for replacement of ball mills with more energy efficient technologies. In parallel, advances in sensor-based sorting (SBS) allow the rejection of low grade rock ahead of energy intensive comminution. The integration of energy efficient comminution with sensor-based sorting has the potential to significantly reduce overall mineral processing energy usage, as discussed by Bern Klein, of the University of British Columbia in his opening keynote address.
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| Bern Klein (left) |
Mark Drechsler has over 40 years mining and infrastructure engineering industry experience and in April started his PhD at the University of South Australia researching the energy and mineral processing benefits of his innovative comminution technology called GRolls. He presented a paper showing the results of an extensive laboratory testing program to determine the size reduction and energy efficiency performance of the GRolls technology for a wide range of industry supplied ore feed materials.
It was good to see that one of my old CSM students, Graham Davey, is now Director, Stirred Mills at Metso. Graham is based in the UK providing stirred mill product management and process engineering for mining and engineering companies throughout the world and he discussed the Vertimill. which has been widely adopted but has faced challenges in managing wear life and measuring charge levels. To address these issues, a new detection system has been developed, in conjunction with a DEM model. By combining the technologies, a novel way to determine and manage wear life and optimise liner design has been developed. Graham showed the practicality of the DEM model for Vertimill liner wear prediction with a sample numerical case for the Vertimill and how it can be used to validate new screw designs without long onsite trials.
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| Graham Davey (centre) |
HPGR circuits are being increasingly adopted in the mining industry’s pursuit of processing higher volumes of ore. Bjorn Dierx has the global responsibility for the HPGR product line at Weir Minerals, The Netherlands, and he discussed advancements in HPGR-based comminution circuits and reported the value proposition and limitations for adopting multi-staged HPGR circuits, combined with innovative dry classification and beneficiation opportunities.
Felix Heinicke, Senior Process Manager at Köppern, Germany, reviewed fundamental research on the downstream effect of HPGR, and reporting on its physical basis and limits. Two examples for leaching of gold ore and application of bottle roll testing were presented to support the general findings.
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| Felix Heinicke (right) |
Leseka Moatlhodi holds a BEng and a MEng in Mineral Processing from the University of Leeds. She is now a PhD student at the University of Cape Town, developing methods to minimise diamond breakage in comminution circuitsand she looked at the effect of HPGR operating pressure and roll speed on the breakage of diamonds.
Sonny Mwansa, Principal Process Engineer-Mills, with Bradken Resources, South Africa, discussed the revision of top-up ball size and liner design post pre-crushing ahead of a SAG mill circuit.
In the final paper of the session Adam McElroy, Specialist Development Engineer at Boliden Mineral, Sweden, discussed the effect of feed size distribution on autogenous milling, using Boliden case studies.
Technical session 4
Chairperson: Sherry Bremner, University of Cape Town, South Africa
Jaclyn Kogler, a process engineer with Metso, USA, detailed the complexities, including commissioning procedures and operational intricacies, of a Metso Single Stage semi-autogenous (SAG) pilot mill, operated in closed circuit with a Metso Ultrafine Screen. The findings of the pilot trial are beneficial for determining SAG mill scale-up in accordance with design criteria, providing guidance for future applications in mineral processing.
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| Jaclyn Kogler |
SAG milling circuits are almost always associated with high throughput mining operations with aggressive production targets. The main role of the SAG mill is to achieve and maintain the desired feed rate while the role of the ball milling circuit is to achieve and maintain the target product size. While there are a few industrial levers available to make it easier to maintain the desired feed rate, the simplest change is to increase the SAG mill ball size. The key benefits include unlocking a wider operational range and reducing ball consumption. Other benefits could be an increase in SAG mill feed rate, or maintaining the same feed rate at a lower ball load and/or slower mill speed. Brian Cornish, of ME Elecmetal provided valuable insight into optimising SAG milling performance with bigger balls.
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| Brian Cornish |
In his second presentation at the conference, Sandile Nkwanyana of Mintek then discussed the effect of ball load on SAG mill collision environment and performance.
Paul Cleary is a Chief Research Scientist at CSIRO Data61, Australia. He has been at the forefront of the development and application of particle based computational methods for the prediction of the behaviour of physical systems for many years and is recognised as one of the great pioneers of the Discrete Element Method (DEM). He is also a leading developer of the Smoothed Particle Hydrodynamics (SPH) method for industrial fluid dynamics and he presented a complete particle scale model for the prediction of SAG mill performance, based on a coupled DEM+SPH model which can be used to predict the motion of solid charge and the slurry phase respectively.
Mario Calvo is the Managing Director of Electrodrives, Spain. He described the optimisation of comminution at Ban Houayxai mine, Laos, by upgrading to variable speed in a fixed-speed SAG mill.
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| Mario Calvo (left) |
The final paper of the day was given by Richmond Asamoah, a Senior Research Fellow at the University of South Australia. He presented a study investigating the unique acoustic frequency signature of varying mill feed size with links to ore mineralogical characteristics in an autogenous and semi-autogenous mill.
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| Richard Asamoah (left) |
More on Day 2
Wednesday April 2nd
Technical Session 5
Chairpersons: Mark Drechsler (University of South Australia and Gyratory Roller Solutions Pty Ltd, Australia) and Graham Davey (Metso, UK)
The day began with a keynote lecture from Grant Ballantyne, Technical Director at Ausenco, Australia. He discussed how new comminution and classification technologies are regularly hitting the market with promises to reduce energy, improve liberation and reduce costs, but asked how can we identify the fine wine from the snake oil? For example, improved energy efficiency can be achieved at the detriment of wear, or improved liberation can be achieved without improving recovery. Grant explored the range of evaluation methodologies that are available for the discerning metallurgist, as well as some lessons that can be learned from previous ineffective assessments.
The keynote was followed by two presentations which promise a lot. In the posting of 10th February, the question was asked if high voltage pulse power is the next great innovation in comminution.
Flávio André, a research officer at Australia's JKMRC presented a study, co-authored by the late Frank Shi, detailing the development and optimisation of a laboratory-scale HVP electrode-grizzly system. Findings highlight HVP’s capacity to separate valuable minerals from gangue before energy-intensive grinding stages, offering a more sustainable mineral processing alternative.
Following Flávio's presentation, Nathan Flaman, the CEO of French company I-ROX, showed how the company is collaborating with BHP to scale up its own application of the pulsed power technology. I-ROX aims to reduce the cost of comminution by slashing the energy and consumables required and increasing flotation recoveries as a result of improved mineral liberation. The effects on mineral liberation were shown in a paper presented at Process Mineralogy '24.
Collectors are vital flotation reagents, but collector adsorption behaviour linked to mineral surface alterations due to varying grinding conditions is not well understood, as the grinding environment, wet or dry, significantly alters the surface and pulp chemistry of sulphide minerals,affecting collector adsorption. Theophilus Amos-Judge, a postgraduate student at the University of South Australia, examined the collector adsorption behaviour of copper sulphide ores and model minerals, specifically chalcopyrite, subjected to both dry and wet grinding with different grinding mechanisms. Results highlighted the critical importance of controlling the comminution environment on downstream flotation performance, particularly for slow floating particles.
Harshita Gupta, Manager Research & Discovery Portfolio at BHP, Australia, presented insights from a 12-week open innovation comminution challenge ran by Think & Act Differently, the innovation team at BHP. Twelve innovators collaborated to test their technologies against conventional BHP processes. The outcomes of this challenge not only demonstrate the potential for innovation within the sector but also serve as a model for future collaborative efforts aimed at addressing industry challenges.
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| Harshita Gupta (bottom right) |
Kanishk Bhadani, post-doc researcher at Chalmers University of Technology, Sweden, presented a study to develop a framework for integrated optimisation of crushing, milling and classification (cyclone) processes to enhance throughput and product quality reporting to the downstream process.
Jeremy Hanhiniemi, Director of Technology and Innovation with Weir, Australia and Adjunct Fellow at the JKMRC, Australia, described the ‘Parallel Flow Sheet’: a HPGR-Stirred-Mill-CPF flow sheet concept for energy efficiency and tailings improvement.
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| Jeremy Hanhiniemi (2nd left) |
Johnny Kalala is a senior process consultant with DRA Global, South Africa and he looked at the use of breakage rates trends in (S)AG mill followed by ball mill circuits to explain past comminution circuit trends and to propose new circuits.
Taking us to the lunch break, Leonardo Espinoza, a metallurgical technician with Antamina, Peru described the analysis and prediction of ball mill overload in SABC circuits.
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| Leonardo Espinoza (centre) |
Technical Session 6
Chairpersons: Jenny Wiese (Metcelerate, South Africa) and Warren Little (Kansanshi Mining, Zambia)
Most crushing and grinding circuits are designed to handle variable ore feed with changing competency and hardness. However, ore with high clay content presents unique challenges that necessitate careful consideration in the flowsheet design. Rajiv Chandramohan, Director and Head of Process Optimisation, at Ausenco, Australia, offered a technical guide with practical design and operating strategies, supported by examples, for processing high clay ores.
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| Rajid Chandramohan (right) |
Classification plays an important role in the grinding circuit. The benefits of improved classification efficiency on wet-grinding ball mill circuit have been reported in the past. Despite its poor classification efficiency, hydrocyclones are still the most used classifiers in these grinding circuits. Vladimir Jokovic, Team Leader at CSIRO, Australia, discussed the benefits of semi-inverted hydrocyclones in a closed grinding circuit pilot scale study.
The performance and energy efficiency of SAG and ball mills is highly affected by the mills’ charge composition of ore and media. In his second paper of the day, Jeremy Hanhiniemi proposed a relationship between size specific energy achieved by SAG mills, and their media volumetric fractional filling in the charge and in the mill overall. Flowsheet designs in brownfield expansions employing pre-crushing, for example, can be devised considering this to both best utilise the existing mill assets, as well as employ the new equipment investment effectively.
SABC circuits are energy and water intensive large, fixed plant that require grinding media and liners. The innovative GRolls comminution technology is low energy,requires no grinding media, is flexible and modular in operation suitable for wet or dry circuits to process complex low grade future ores using renewable energy sources. Mark Drechsler, in his second presentation at the conference, presented the results of an extensive laboratory testing program to determine the size reduction, energy efficiency, breakage mechanisms and mineral liberation performance of the GRolls technology for both dry and wet feed, the benefits for downstream beneficiation processes including early gangue minerals rejection strategies, and the potential for the new comminution technology to augment or replace SABC circuits.
Although cheaper energy processes are developing, access to water is often restricted or limited, particularly in some of the main mining countries with scarce water resources, such as Australia, Chile or Peru. Carsten Gerold, of Loesche, Germany, described a recent development allowing integration of intermediate sorting of a middlings size fraction, via magnetic separation or coarse flotation, into the dry Loesche Vertical Roller Mill grinding-classifying process while still producing a primary feed for the downstream process. enabling the separation of coarse gangue at an early stage of the process.
Reduced energy and water consumption are mandatory for enhanced sustainability. The Vertical Roller Mill (VRM) is a dry grinding system that is capable of achieving this said Caroline Woywadt, Director Process Technology at Gebr. Pfeiffer, Germany. She said that dry grinding with VRM gives a substantial benefit in energy savings, the energy consumption being about 30 to 40% lower than that of traditional mill systems in the mining industry.
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| Caroline Woywadt (left) |
Recovery losses resulting from the fines fraction of the grinding circuit product is an issue in many gravity and flotation circuits, said Brian Putland, Managing Director with Orway Mineral Consultants, Australia. Losses need to be balanced against improved liberation from grinding finer. and predicting the fines content is essential for accurate full-scale plant design and optimisation, particularly for plants with deslime circuits. Brian examined the factors influencing fines generation in various comminution circuits.
More on Day 3
Thursday April 3rd
Technical Session 7
Chairpersons: Brian Cornish (ME Elecmetal, Australia) and Gauti Asbjörnsson (Chalmers University of Technology, Sweden)
Chris Greet is a Principal Consultant at Mineralis Consultants, Australia, and is now part-time at Magotteaux as a Global Mineral Processing Specialist. A regular at MEI's comminution and flotation conferences, he presented the first paper in the morning session, asking "so, you want to change the grinding media in your ball mill- what happens next?
Paul Shelley of Molycop, USA presented work exploring an alternative to the Marked Ball Wear Test for evaluating the abrasion performance of grinding balls.
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| Chris Greet and Paul Shelley |
Ion Gurnett, Senior Metallurgist with Glencore Technology, Australia said that it has been hypothesised that increasing the specific gravity of the grinding media within a stirred mill will result in subsequent increased efficiencies within the milling process. Ion's paper challenged that hypothesis by IsaMill testwork aiming to develop an economic model to use as for evaluating ceramic media selection in a stirred horizontal mill.
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| Ion Gurnett (left) |
Pieter Kruger, Regional Applications Engineer with Russell Mineral Equipment, South Africa, described recent advancements in relining technology and support tailored for African mill operators, including site case studies for enhancing efficiency, safety, and operational uptime.
Stephen Gwynn-Jones, Group Manager-Products at Russell Mineral Equipment, Australia, presented a data-driven framework for enhancing mill relining performance and safety.
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| Stephen Gwynn-Jones and Pieter Kruger |
Rajiv Chandramohan, Director and Head Of Process Optimisation at Ausenco, Canada discussed focused investigations providing insights into how grinding mills should potentially be operated to improve grinding efficiency by leveraging media shape.
Ersin Yazici of Karadeniz Technical University, Türkiye, discussed the development of a wireless sensor network system for real-time abrasion monitoring and forward prediction for rubber lifter bars in grinding mills.
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| Ersin Yazici (right) |
Paul Toor, Comminution Consultant with Toornado Metallurgy, Australia looked at designing SAG mill liners for performance, not life, an update on a paper given at Comminution '12.
The high cost of horizontal grinding mill downtime is well known and widely discussed, yet many of the up-front design considerations that can minimise downtime are overlooked or forgotten. Jared Le Cras, Director-Mill Reline Equipment at Metso, Australia, addressed this issue, by systematically reviewing every aspect of grinding mill maintenance that should be considered during the plant engineering phase.
In his second paper of the morning, Glencore's Ion Gurnett discussed the factors involved in the design of stirred mill testwork, how these can influence the overall specific energy, and why it is important to thoroughly evaluate the ability to scale up when conducting technology trade-offs.
Technical Session 8
Chairpersons: Alex Wang (King’s Beads Ltd, China) and Aubrey Mainza (University of Cape Town, South Africa)
Matthew Toll is a Metallurgical Account Manager with Global Met Tech, Australia, He described an improved signature plot analysis approach to incorporate variable feed particle size in the determination of stirred mill grinding energy requirement.
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| Matthew Toll (centre) |
Ion Gurnett was back for his third presentation of the day. Using the IsaMill as a case study, he showed how material selection may not only reduce mill downtime, but also influence the overall specific energy for grinding, and why it is important to understand materials of construction in testwork, and the processes involved in evaluating new materials and designs prior to market release.
Sherry Bremner, a Senior Lecturer at the University of Cape Town is a physicist and academic with expertise in granular flow modelling, mineral processing, and comminution. She looked at single particle tracking in DEM for use in validation of PEPT experiments in a horizontal stirred mill.
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| Sherry Bremner |
Okay Altun, an Associate Professor at Hacettepe University, Türkiye, discussed the energy optimisation opportunities, and the result of modelling works for HIGMill operation at a copper regrind application.
The Ro-Star vertical stirred mill has been many years in development. Its inventor, Rainer Imhof, was cognisant of the high energy requirements to liberate minerals at such fine sizes and decided to go back to first principles and revisit the design to improve the efficiency of the mill. The new Ro-Star mill is a joint-venture development between Maelgwyn Mineral Services (MMS) Ltd of Wales and ERSEL Heavy Machinery Inc. of Türkiye. Michael Battersby, Managing Director of MMS detailed the principal and concepts behind the new design together with the design, development and testing of a laboratory, pilot and an industrial sized 600kW unit.
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| Michael Battersby (left) |
Luis Marcelo Tavares, a Professor at the University of Rio de Janeiro (UFRJ), Brazil, described advances in vertical stirred media mill modelling using the UFRJ mechanistic mill model.
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| Luis Marcelo Tavares (left) |
In the final paper of the conference Kai Johnston, a metallurgist at Glencore Technology, Australia discussed how in standard stirred mill laboratory testwork, the particle sizing method employed and how it affects the reported specific energy requirements are often overlooked. Lasersizing is often employed as the industry gold standard for its ability to achieve consistent and accurate results across several different commodities. However, in the context of stirred milling, particle characteristics like shape and surface properties can compromise its ability to accurately portray the sample’s particle size. The underlying impact of this can be detrimental to the resulting mill sizing causing overestimation of reported power requirements. Using the IsaMill as a case study, Kai demonstrated why it is important to understand how the particle sizing technique selected can influence signature plot results, when to apply alternate analytical particle sizing techniques and how to improve lasersizing for signature plot testwork.
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| Kai Johnston (centre) |
More on Day 4
A final thanks to all those who presented their work at the conference, and we hope to see you all again at Comminution '27.
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