Mineral Processing Circuits '26: a summary of the technical presentations

Mineral Processing Circuits '26 was held at the Vineyard Hotel, Cape Town from April 23-24, 2026 and was attended by 46 delegates from 15 countries.

Following is a brief summary of the presentations delivered during the two days of technical sessions, with links, via the presenter's name, to the draft papers associated with each presentation. Accompanying photographs have been taken where possible from the conference photo album.

Unfortunately, not all presenters provided draft papers, so these presentations are not included in the summary. However, short abstracts for all the conference papers are available in the programme on the conference website.

The complete programme of presentations, including links to available draft papers, can be found in the online open-access Proceedings.

The draft papers 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.

Thursday April 23rd

Technical Session 1
Chairpersons: P. Miller (BacTech Environmental Corp., Canada) and A. Hubert (Köppern Aufbereitungstechnik GmbH & Co., Germany)

Kevin Galvin, Director of the ARC Centre Of Excellence, University of Newcastle, Australia is the inventor of the Reflux Classifier used in gravity separation of fine mineral particles. In his keynote presentation he argued that minerals processing is entering a paradigm shift, implying that there is a current paradigm, and that something new will ultimately emerge. He identified the existing paradigm, an approach forged on the back of 20th century technology and looked at understanding why it persists. In moving forward we need to consider the possibilities that arise from the emergence of new technologies. Up until now we have tended to consider new technologies and how they fit within the old paradigm, but the real innovation emerges when we let go of the past. He argued that complex, inefficient, large-scale plants should give way to simpler, efficient, smaller, more purposeful units or modules, that can be formally controlled to address variability and in turn facilitate more complex forms of decision making.

Kevin Galvin (left)

In the early stages of developing a new mining project, geometallurgical studies are crucial to assess the technical feasibility. Maria Cristina Vila, an Associate Professor at the University of Porto, Portugal, showed how this was used in the flowsheet design for the recovery of rare earth minerals from an iron-dolomite-carbonatite deposit.

Magnetic separation is commonly used in pegmatite ore processing to remove iron silicate minerals, such as amphibole and tourmaline, after dense media separation and/or flotation. Janine Figueiredo, of the Federal University of Ouro Preto, Brazil, presented a study evaluating how adding a magnetic separation step before dense media separation can improve the lithium grade in the concentrate during the beneficiation of spodumene-rich pegmatites.

Maria Cristina Vila (left) and Janine Figueiredo

Hagen Gunther Jung, Executive Director with GeoEnergy Consult, Germany, examined the various options for disposal of the naturally radioactive processing residues of a rare earths project.

Hagen Gunther Jung (left)

Richmond Asamoah, of the University of South Australia, discussed the influence of microwave pre-treatment on particle breakage and comminution efficiency of mineral ores.

Richmond Asamoah (right)

The Kanyika Niobium Project in Malawi re-evaluated its 1.5 Mtpa SABC comminution circuit due to high power consumption and high niobium losses to slimes. Rex Zietsman, Chief Technical Officer at Globe Metals and Mining, Australia, described the energy-efficient alternative comminution and beneficiation circuit for the Kanyika project.

Rex Zietsman (right)

Technical Session 2
Chairperson: G. Asbjörnsson (Chalmers University of Technology, Sweden)

Rex Zietsman was back on the podium after lunch showing how gravity-magnetic integration and selective regrinding has been used for pyrochlore recovery at the Kanyika Niobium Project in Malawi.

Scaling breakage parameters from pilot-scale SAG mill tests to industrial operations is complex due to non-linear relationship driven by internal classification and grate design differences.  Pablo Pichinao, a comminution specialist at Anglo American, Chile, proposed a phenomenological framework integrating pilot-scale test campaigns with industrial sampling to develop a robust scaling methodology. The approach establishes a scientifically grounded solution for translating pilot-scale findings to full-scale SAG operations, advancing comminution research and improving predictability in mineral processing circuits.

In a second presentation Pablo, and his colleague Sebastián Urrejola described the development and calibration of a phenomenological throughput model for the Quellaveco concentrator, a a state-of-the-art processing facility in southern Peru, part of Anglo American's digitalised open-pit copper mine. It uses high-capacity grinding (SAG/ball mills) and flotation to process around 127,500 tonnes of ore daily, producing copper and molybdenum concentrates.

Sebastián Urrejola (centre) and Pablo Pichinao (right)

Paul Shelley

Grinding media plays a large role in the energy and carbon emission story for hard rock mining. A presentation by Paul Shelley of Molycop Global, USA, makes a definitive contribution to the cast media carbon footprint discussion. Major emission contributors, scrap steel, ferro-chrome manufacturing, natural gas and electricity were discussed in detail, exploring the manufacturing route of cast media and its effect on the grinding media carbon footprint. The paper explored possibilities of reducing the grinding media carbon footprint at the customer site. Media in use options were presented that take account of the mineral characteristics, the mill dynamics, and the product metallurgy to optimise both carbon footprint and media performance.

High Pressure Grinding Rolls (HPGR) have become an integral part of flowsheets in mineral processing technology. Their proven advantages, such as low specific energy consumption, high availability, low operating costs, have led to an ever-widening range of applications for HPGR. As with the cement industry, where the use of HPGR began with simple pre-grinding,developments, the mineral processing industry ise also moving away from simple flowsheets with HPGR for pre-grinding towards more complex flowsheets in which HPGR performs the majority of the comminution work.  Artur Hubert, of the Koeppern Group, Germany, presented practical examples of successful HPGR application in grinding circuits in mineral processing and the cement industry and showed the versatility of HPGR use in flowsheets.

Artur Hubert

Taswald Moodley, Principal Engineer at Mintek, South Africa, described the repurposing of an existing stirred mill to improve PGM recovery in flotation circuits treating UG2 ore. UG2 is a chromitite reef with a shallow-dipping stratiform tabular orebody in the South African Bushveld Complex.

Taswald Moodley (right)

Friday April 24th

Technical Session 3
Chairpersons: T. Moodley (Mintek, South Africa) and A. Ojaghi (DRA Global, Canada)

Unfortunately Hongli Yang, of the Taiyuan University of Technology, China, although registered, was unable to attend the conference, but her paper describes the cyclone column separator (CCS), a novel kind of water-only cyclone characterised by compound positive and negative cone structure, which has been proved to be more efficient than traditional single-cone water-only cyclones and more cost-saving than dense medium cyclones in fine coal preparation. It has found wide application in China for coal preparation plants and also proved to be efficient in the carbon-ash separation of coal gasification slags

Process control and monitoring are essential strategies for improving profitability and minimising environmental impact in mineral processing. The effective implementation of these strategies is enhanced by sufficiently accurate dynamic process models. Although extensive literature exists on modelling mineral processing operations, they often differ in scope and complexity and are frequently presented inconsistently or incomplete. Moreover, many implementations rely on expensive software, hindering reuse and transparency. Conrad Kriel, of Stellenbosch University, South Africa,  presented a transparent, modular library that enables the integrated simulation of mineral processing systems. The library includes dynamic models for crushing, milling and flotation operations, presented in a consistent format.

Conrad Kriel (right)

A new approach on simulation of closed systems was described by Abu Huraira, of Metso, Finland. The new method allows optimisation of flotation residence times for each stage simultaneously. This can lead to improved metallurgical performance and decreased number of laboratory tests. Additionally, the proposed approach provides guidance on deciding appropriate laboratory residence times to be used as a design basis for upscaling to plant scale.

The Copperwood Project, located in Michigan’s Upper Peninsula, USA, has undergone a major process redesign integrating ultrafine flotation within a mill-float-mill-float circuit to enhance metallurgical performance and reduce energy demand. The revised flowsheet incorporates a de-sliming stage between milling circuits and Jameson Cell ultrafine flotation technology. Aghil Ojaghi, of DRA Global, Canada, showed  how the combined application of flowsheet modelling, equipment selection, and pilot validation can deliver step-change improvements in circuit performance, advancing the integration of modern flotation technologies to enhance recovery, sustainability, and operating efficiency in fine-grained copper deposits.

Aghil Ojaghi

Sands from the Ravno deposit, Slovenia, were characterised to evaluate their potential for high-purity quartz production, which is a critical raw material for EU industries. Kalyani Mohanty, a PhD student at Universitat Politècnica de Catalunya, Spain, showed how process development was focused on selective flotation using Clariant reagents, combined with gravity separation (Wilfley table and Multi Gravity Separators) to remove high-density impurities and upgrade the quartz to high-purity standards.

Kalyani Mohanty (centre)

Several critical factors define the performance of the flotation process. Among these, variability in the mineralogical characteristics, especially variabilities leading to galvanic interactions between the minerals’ surfaces and grinding media, are known to control and affect the selectivity and efficiency of the flotation process. Richmond Asamoah, of Adelaide University, showed that there is good association (linear and nonlinear) between the pulp chemistry variables and rougher feed mineral content, showing relevance to advanced sensor data before the grinding stage.

Technical Session 4
Chairperson: P. Shelley (Molycop Global, USA)

Varun Gowda

Design of aggregate production operations is often based on economic viability, while limited focus is on environmental viability. With an increasing demand for low environmental impact products (aggregates), there is a need to study the features and attributes in the design and operations of aggregates production that can achieve the same. Varun Gowda, of Chalmers University of Technology, Sweden, provided a benchmark analysis of multiple aggregate production sites in Europe based on their annual site-specific data, operational characteristics (resource consumption, production, etc.), and design characteristics (machines, process layout, etc.).

Reprocessing of phosphate mine waste has become essential due to the depletion of primary resources, the growing demand for phosphate ore, and increasing concerns about the environmental impacts of waste storage. However, its development remains challenging because of the heterogeneity of these materials, arising from their lithological variability, particle size distribution, and mineralogical complexity. Mohamed Haidouri, of University Mohamed VI Polytechnic, Morocco, presented an innovative solution for transforming mine waste into a sustainable secondary resource. The approach is based on the development and comparison of mineral processing circuits to select the most efficient configuration that maximizes phosphate recovery while meeting marketable quality criteria. The proposed flowsheets integrate classification, sorting, grinding, desliming, reverse flotation, and direct reverse flotation. 

Mohamed Haidouri

In recent years, refractory low-grade ores serve as a major source of gold. The ever-increasing ore complexity warrants smart online process adaptation and development of advanced methods for sustainable, cost-effective gold extraction process. Richmond Asamoah, of Adelaide University, investigated technological challenges linked with gold extraction from refractory, auriferous sulphide ores outsourced from a common deposit but with subtle short-term variability. The changing mineral composition and the dynamics of pre-concentration and pre-treatment techniques (e.g., flotation and bio-oxidation) in maximising the leaching performance were investigated. The findings highlight the critical importance of advanced sensor and smart process adaptation for complex variable ore processing.

Millions of tonnes of flotation tailings worldwide contain significant residual metal values locked within sulphide minerals that are uneconomic to process using conventional methods. Paul Miller, of Bactech Environmental Corporation, presented a novel process integrating bioleaching with ammonia-based chemistry to recover critical metals while converting iron and sulphate streams into magnetite and ammonium sulphate. The generation of these by-products provides additional revenue streams as opposed to waste streams that can significantly offset metal recovery costs, supporting the economic viability of total tailings reprocessing.

Paul Miller (right)

High pressure acid leaching (HPAL) is widely applied for nickel and cobalt recovery from lateritic ores using sulfuric acid under elevated temperature and pressure. However, the subsequent counter-current decantation (CCD) circuits used for solid-liquid separation are characterised by high water demand,large footprint, and potential metal losses. Richmond Asamoah, of Adelaide University, showed that the resin-in-moist-mix (RIMM) process has high efficiency in recovering valuable metals from pulps and fine minerals. Integrating RIMM into the CCD circuit following HPAL offers a novel strategy to enhance metal recovery while reducing water and reagent consumption. Introducing ion-exchange resin after the first CCD stage enables selective adsorption of dissolved metal ions, decreasing dependence on multiple wash stages and minimising solution losses.

A final thanks to all those who presented their work at the conference, and we hope to see you all again at Mineral Processing Circuits '28. Reactions to Mineral Processing Circuits '26 can be seen at #MineralProcessingCircuits26.

#MEIBlog

Physical Separation '26: a summary of the technical presentations

Physical Separation '26, the 9th in the series, was held at the Vineyard Hotel, Cape Town from April 20-22 2026 and was attended by 76 delegates from 15 countries.

Following is a brief summary of the presentations delivered during the three days of technical sessions, with links, via the presenter's name, to the draft papers associated with each presentation. Accompanying photographs have been taken where possible from the conference photo album.

Unfortunately, not all presenters provided draft papers, so these presentations are not included in the summary. However, short abstracts for all the conference papers are available in the programme on the conference website.

The complete programme of presentations, including links to available draft papers, can be found in the online open-access Proceedings.

The draft papers 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.

Monday April 20th

Technical Session 1
Chairpersons: A. Pukkella (Metso, Finland) and D. Goldburn (Holman-Wilfley, UK) 

Following the keynote lecture from Kristian Waters, Associate Professor at McGill University, Canada, Priscila Esteves, Head of Technical Department at Steinert Latinoamericana, Brazil showed how sensor-based sorting (SBS) technologies have advanced significantly, driven by the demand for higher efficiency, dry processing and the benefits of pre-concentration stages. Applied in mineral processing for over a decade, SBS now faces new challenges as applications expand to complex ores, coarse particle sizes and large throughputs. Recent innovations emphasise intelligent analysis, improving detection resolution, throughput and data-driven decision-making to ensure precise classification at industrial scales. 

Priscila Esteves

Preetham Nayak is the Founder and Mining Project Consultant at InnovMine Consulting, Canada. He described the development of an integrated ore sorting strategy leveraging new technologies, shovel sense, bulk ore sorting and particle sorting, with an aim to enhance the head grades to the mill through strategic upgradation of lower grade stockpiles and mined rocks to reduce total waste generation over life-of-mine. This not only increases overall metal production and enhances operations economics but also allows for a greater rejection of coarse waste material in the mine itself.

Fabian Riedel is Managing Director of Rokksta, Germany and he described a method for predicting the performance of single particle sorters, showing that effects of feed material (intrinsic sortability), sorting process (discrimination efficiency) and sorter technology (mechanical separation efficiency) need to be considered when attempting to upscale bench-top tests and predict plant performance.

Tungsten mining supports industries like electronics and cutting tools by providing high performance materials. However, efficient ore recovery is hampered by small inclusions within ore particles, making conventional sorting methods such as X-ray less effective. This results in more valuable material being lost in waste, higher impurity levels, and increased costs. Achieving proper separation often requires crushing ore to fine sizes, which lowers throughput and raises energy and operating expenses. Kai Bartram, Global Sales Director for TOMRA Sorting, Germany discussed a study to evaluate CONTAIN, an AI-based sorting technology, in a real mining scenario under actual operating conditions. The goal was to assess its ability to overcome inclusion-related sorting challenges and improve overall process recovery.

Kai Bartram (left)

Sensor based sorting machines typically provide two output fractions. However, there is often a need to obtain more than two products for further processing. Jakub Progorowicz, of Comex, Poland. described the development of a triple product sorting machine, where the material identification process is carried out by a complex multisensory system, a two-threshold separation system allowing for triple product separation.

Maria Cristina Vila, an Associate Professor at the University of Porto, Portugal, described the development of pre-concentration strategies as part of efforts aimed at developing innovative, responsible, and sustainable beneficiation techniques for rare earth elements (REEs) from drill core samples from the Fen Deposit in Norway, an iron-dolomite-carbonatite containing rare earth minerals bastnäsite, parasite, synchysite, and monazite.

Maria Cristina Vila and Hagen Jung

Technical Session 2
Chairperson: S. Chingwaru (University of Queensland, Australia)

Hagen Jung, of GeoEnergy Consult from Germany, looked at the automated transport preparation of a naturally radioactive preconcentrate from a rare earths project. As a consultant Hagen specialises in managing natural radioactivity associated with mining and processing, and through his capabilities in environmental safety, decontamination, waste treatment and disposal, decommissioning, site remediation, etc., he provides essential support to projects and operations.

Air classifiers separate particles in a gas stream using aerodynamic forces, with performance governed by cut size and separation sharpness. Real-time knowledge of the particle size distribution (PSD) of the product stream is critical for stabilising operation, achieving target cuts, reducing energy use, and maintaining product quality. Conventional monitoring relies on intermittent off-line sampling or optical methods that struggle in opaque high-solids flows, and the time delay, sampling bias, multiple scattering/attenuation and fouling often prevent effective closed-loop control. Richmond Asamoah, of Adelaide University, proposed an in-situ vibration-sensing probe inserted directly into dense gas-solid streams, with the mechanical response to particle impacts mapped to PSD in real time, providing a calibration-based tool for dense-phase conditions and seamless integration with classifier control systems. 

Richmond Asamoah (right) and Desire Awuye (centre)

Desire Awuye, of the University of Newcastle, Australia, described how the hydrodynamic classification of two minerals of very different density, silica and hematite, was investigated using a modified Reflux Classifier known as the GradePro. The primary objective was to achieve efficient classification with no by-pass. By-pass is a common feature of cyclones in comminution circuits, responsible for overgrinding and hence lower mineral recovery, excessive energy consumption, poor mill utilisation, and increased tailings and water loss.  The classification was found to be very sharp, exhibiting closure of the partition curves and no by-pass.

To combat the issues of dropping metal prices, rising energy costs, low grade ores, and increasing environmental restraints, metallurgists are turning to innovative technology.  Because of technological advances, it is now possible to close grinding circuits entirely with screens rather than conventional hydrocyclones or in combination with hydrocyclones, allowing operators to benefit from improved grinding efficiency, higher production rates, negligible overgrinding, and better particle size distribution for downstream processing.  John Tran, of Derrick Corporation, USA, discussed the foundations of fine screens in grinding circuits as well as success stories from their use in various ore beneficiation plants.

John Tran (left)

Richmond Asamoah was back on the podium to discuss real-time monitoring of size-passing fractions in hydrocyclone overflows via probe-based force measurement.

MEI's Young Person's Award winner, Arjun Pukkella, of Metso, Finland, presented a study comparing a conventional hydrocyclone with a fishtail hydrocyclone featuring an extended overflow pipe that induces a siphon effect. Computational fluid dynamics simulations and laboratory experiments were performed to investigate the flow behaviour and performance. The fishtail design showed suppressed air-core formation and altered pressure distribution, leading to improved particle settling and underflow thickening. Experimental results confirmed higher throughput rates with increased underflow solids concentration compared with the standard design. The study demonstrates that a simple geometric modification can significantly enhance dewatering performance without compromising the original classification behaviour of hydrocyclones.

Arjun Pukkella (right)

Tuesday April 21st

Technical Session 3
Chairpersons: A. Singh (Mintek, South Africa) and M. Vila (University of Porto, Portugal)

Presenting for the second time, Metso's Arjun Pukkella examined how conic curvature and surface-wall roughness affect gas cyclone separation performance, supported by Computational Fluid Dynamics analysis. He showed that cyclone geometry and wall roughness jointly govern flow and classification behaviour, and that controlled roughness may serve as a tunable design parameter for performance optimisation.

And presenting for the 3rd time, the University of Adelaide's Richmond Asamoah looked at the Resin in Moist Mix (RIMM) process, designed for the selective recovery of valuable metals from lateritic and clay-rich ores, operating with minimal water input and offering a sustainable approach to critical metal extraction. He showed that the fine nature of RIMM residues presents challenges in maximising water utilisation through integrated solid-liquid separation. The study investigated the dewatering performance of RIMM tailings using selected flocculants to enhance sedimentation and maximise water savings. 

Nicolas Boonzaier, Product Manager at Mineral Technologies, Australia examined the critical role of earthing in high tension roll separators and the  pronounced impact of component condition on separation efficiency. When both rollers and brushes were worn, recovery was significantly reduced; replacement with new components nearly doubled recovery. The findings indicate that earthing quality deteriorates with roller and brush wear, directly influencing grade and recovery outcomes. 

Nicolas Boonzaier

ST Equipment & Technology (STET), USA has developed an innovative dry separation system based on a tribo-electrostatic belt separator, for beneficiating mineral ores without requiring water or chemical additives. This technology has been successfully scaled for industrial use across a variety of applications, including the removal of unburnt carbon from fly ash, separation of quartz from calcite, magnesite from talc, and quartz from barite. Thomas Newman, Process Engineer with STET showed how electrostatic separation technology offers an efficient and environmentally sustainable alternative to conventional mineral processing methods.

Thomas Newman

Technical Session 4
Chairperson: J. Figueiredo (Federal University of Ouro Preto, Brazil)

Magnetite is a ferromagnetic iron ore primarily used in steel making and coal washing. The demand for magnetite is dictated by the steel industry; however, growth is spurred by magnetite’s high iron content as the industry shifts towards more energy efficient and lower emission production. Nichole Maistry. a senior engineer at Mintek, South Africa, described how two low-grade magnetite ores were subjected to characterisation, followed by laboratory magnetic separation testwork to determine how the ore characteristics influence beneficiation, in terms of iron grade and recovery.

Untreated impurities in flotation concentrate used in phosphoric acid production reduce the quality of the acid produced. These impurities include iron and aluminium oxides, carbonates and silicates. When left untreated, they alter the physio-chemical properties of the acid leading to increased viscosity and densities, ultimately resulting in post acid precipitation and reduced P2O5 solubility in fertilizer applications. Getrude Marape, head of physical separation at Mintek, South Africa, presented a study which characterised and investigated iron and aluminium removal from phosphate ore by magnetic separation while assessing the phosphate upgrade. 

Nichole Maistry (left) and Getrude Marape (right)

Magnetic susceptibility of a particle determines its trajectories in magnetic separation processes, yet most magnetic characterisation methods provide only bulk-averaged magnetic susceptibility values, covering the variability among individual phases and particles. Asim Siddique, a PhD student at TU Bergakademie Freiberg, Germany, addressed that limitation by introducing a modeling approach to estimate magnetic susceptibility at the particle level. 

Wednesday April 22nd

Technical Session 5
Chairpersons: K. Galvin and D. Awuye (University of Newcastle, Australia)

Pilot dense-media separation (DMS) campaigns often show discrepancies between theoretical washability curves and actual plant performance, largely because offline tracer tests fail to capture true cut densities under live conditions. To address this, Johan Wynand Bezuidenhout, of Consulmet, South Africa, described a trial on an RFID-based online density tracer system on a 5 tph pilot DMS treating hematite ore. The system tracked tracer movement in real time, achieving seamless integration with no operational interference. The trial confirmed that reliable online tracer data enables direct transition from washability interpretation to bulk operation. Consulmet plans to deploy this system across future pilot campaigns and research collaborations, advancing confidence in DMS cut-point determination and process validation.

The energy transition has economically enabled the exploitation of pegmatite rock deposits containing minerals such as spodumene, petalite, and lithiniferous mica. Janine Figueiredo, a Professor and visiting researcher at the Federal University of Ouro Preto, Brazil, described research aiming to assess the potential of using dense media separation to recover lithium minerals from fine tailings, as an alternative reprocessing route for finer fractions. 

Janine Figueiredo (right)

Manual adjustment of hundreds to thousands of spiral splitters per concentrator plant to counter feed variability is labour-intensive and reactive, forcing conservative setpoints that result in high recirculating flows or loss of valuable mineral. Operators lack real-time visibility into individual spiral performance, preventing diagnosis of fouling, wear, or feed mal-distribution until circuit-wide degradation becomes evident. Dustin Pepper, of Mineral Technologies, Australia, described a retrofit optical sensing and actuation system (noncamera, patent pending), which addresses adoption barriers through low-cost deployment at individual spiral starts: sampled-data PID control holds the sensor signal at target grade while reporting operational telemetry. Western Australia site trials are underway and the presentation quantified recovery gains and grade variability reduction relative to manual operation.

Dustin Pepper (centre)

Gravity concentration techniques such as tabling and spiral separation, some of the oldest and most robust methods remain important in improving mineral processing upgrade/pre-concentration. Shaking tables are widely used to test ore amenability to gravity separation but their performance cannot be replicated by a single spiral. Tebogo Mokgomola, of Mintek, South Africa, described a study aiming to develop a predictive model that inputs batch spiral and shaking table results to develop pilot-scale continuous spiral circuits. The model will be used to guide industrial spiral circuits flowsheets to improve performance, remove reductant spiral stages and reduce operating costs. 

Tebogo Mokgomola (centre)

Faced with challenge of scaling up to a larger Multi-Gravity Separator (MGS) for bulk commodities, David Cadwell, of Gravity Mining, UK discussed how initially the key machine design parameters of the Gravity Mining range i.e. drum dimensions, blade configuration and scraper blade speed were compared. He showed how these parameters alone do not fully explain machine performance or help predict the potential capacity of a larger machine. This led to breaking down the physical processes within the MGS to create an overall mathematical model of recovery and throughput performance. As well as providing a window into MGS operation this model provides a tool to help make an informed estimate of scale up to production capacity from laboratory scale test data. The model also aims to help predict performance with different materials and size fractions. Validated against historical test data, this model has already been applied to the design of Gravity Mining’s latest large capacity C910 MGS.

David Cadwell (centre)

Declining global gold grades and increasing environmental liabilities have renewed interest in reprocessing legacy tailings rich in sulphides and residual gold. Steve Chingwaru, a postdoctoral research fellow at the University of Queensland, Australia, presented a  study evaluating the performance of MGS on historical Thalanga gold tailings. The results highlight significant opportunities for integrating sustainable mine waste reprocessing, sulphuric acid generation, and resource recovery to reduce environmental risks advancing circular economy strategies in the gold sector.

Steve Chingwaru (left)

In the final presentation of the conference, Kevin Galvin, Director of the Arc Centre of Excellence, University of Newcastle, Australia, addressed a longstanding problem in recovering cassiterite from tailings. He showed that by using two of his inventions, the 4th generation Reflux Classifier and the GradePro a circuit was devised which offered a viable alternative to conventional processing of low grade ores or tailings.

Kevin Galvin (centre)

A final thanks to all those who presented their work at the conference, and we hope to see you all again at Physical Separation '28.

Reactions to Physical Separation '26 can be seen at #PhysicalSeparation26.

#MEIBlog

April summary: USA, South Africa and sad news from Canada

Two events of international importance took place this month in USA.

On April 2nd the Artemis II rocket, the biggest ever built, took off on its successful manned mission around the moon.The mission highlights just how extraordinary the original Apollo landings were over 50 years ago, revealing both how far technology has advanced and how challenging lunar exploration still remains. Despite today’s cutting-edge computing, advanced materials, and global collaboration, returning humans to the moon has required years of planning, massive investment, and the development of entirely new systems, highlighting the sheer ingenuity and boldness of the 1960s missions, which achieved the same goals with far more limited technology. Artemis not only builds on that legacy with ambitions for sustained lunar presence, but also serves as a reminder that the achievements of the past were not just historic, they were astonishingly ahead of their time.

Source: The Times April 4th

Another extraordinary event took place in America this week, with King Charles III's visit to mark the 250th anniversary of American independence. Considering the strained relations between the UK and USA at the moment, and a third suspected assassination attempt on Trump a few days earlier,  it is a visit that he probably did not relish.

Source: The Times April 2nd

He needn't have worried. His visit stabilised relationships and the King received standing ovations in Congress and at a formal state dinner, his speeches emphasising democracy, NATO, climate, and unity, subtly pushing back against divisions without being overtly political.

In 1991 our first overseas conference, Minerals Engineering '91 in Singapore, was seriously affected by the first Gulf War, many delegates withdrawing due to travel restrictions.  Thirty five years later the present Gulf War also depleted our two conferences in Cape Town this month, Physical Separation '26 and Mineral Processing Circuits '26, many delegates, including presenters, being forced to withdraw due to problems with international flights, particularly those calling at Middle East hubs such as Dubai and Doha. But although the registration lists were depleted, delegates were able to enjoy unusually long breaks for networking and what was lacking in quantity was made up for with quality. And it is always great for Amanda, Barbara and me to catch up with Luxembourg-based Jon.

The Wills family at the Physical Separation '26 dinner at Kirstenbosch 

We missed the monthly Cornish Mining Sundowner in Falmouth, but it was good to have seven of the regulars in Cape Town.

Cornish Mining Sundowner regulars: Amanda and Barry Wills (MEI),
Cameron Dyer, David Cadwell and David Mildren (Gravity Mining),
Doug Caffell (Sepro Systems) and Dave Goldburn (Holman-Wilfley)

Amanda and Jon flew home after the conference, while Barbara and I spent a week on the Garden Route, relaxing at Plettenberg Bay.

It was interesting to visit Monkeyland Primate Sanctuary just outside Plettenberg Bay. This is the world’s first free-roaming, multi-species primate sanctuary, the monkeys and apes  living in a large indigenous forest and move around freely in natural social groups. The sanctuary was founded in 1998 and now cares for over 500 rescued primates across multiple species, including lemurs, capuchin monkeys, gibbons, spider monkeys, and langurs.

Some sad news from Canada this month, of the death of Dr. Gordon Agar, aged 94. Gordon was the Section Head of Mineral Processing at the former Inco Research Laboratories in Mississauga, Ontario, where he worked until his retirement in 1992.

Over his career, Dr. Agar made many significant contributions to mineral processing and published numerous technical papers. His work on flotation kinetics, locked‑cycle testing, and the scale‑up of laboratory results to flotation circuit design was pioneering and remains widely practiced today. His contributions to pyrrhotite depression and Cu/Ni separation in nickel sulphide ore processing continue to influence operating plants.

I first met Gordon at the NATO Advanced Study Institute in Bursa, Turkey, in 1984, where he inspired me with a lecture on flotation circuit design which I incorporated in the latest edition of Mineral Processing Technology. Gordon was a truly remarkable character, who didn't suffer fools too easily. Four years after the ASI I founded Minerals Engineering journal and he was one of the first people that I recruited to the Editorial Board. He became one of my most valued reviewers, although I sometimes had to edit his reviews a little to protect the sensitivities of some authors! 

I still have vivid memories of a hard drinking session with Gordon, and another of the NATO lecturers, Dick Burt, during a weekend break from the conference in Istanbul.

By the Bosporus,1984: Raj Rajamani, Bedri Ipekoglu, me, Cornelius Ek, Dick Burt,
Gordon Agar, Mrs. Ipekoglu and Jaques du Cuyper

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Welcoming Paterson & Cooke as New Sponsors for Hydrometallurgy ’27 and Flotation ’27

Paterson & Cooke is a specialist engineering consultancy that works with mining and minerals companies worldwide. Founded in 1991 it was originally headquartered in South Africa but is now a global company with offices across the UK, Europe, North and South America and Australia.

Paterson & Cooke provides engineering design, consulting, and technical services across the mining lifecycle, specialising in difficult, high-risk aspects of mining, helping mines meet environmental and safety standards and providing expertise in critical minerals processing. The company has more than thirty years of industry experience in slurry pipelines and mining related systems and has expertise in tailings and mine waste handling, long distance concentrate and bulk water supply pipelines, mine backfill process plants and underground distribution systems, marine dredging, and mineral processing. 

The company's first involvement with MEI Conferences was in Falmouth, UK, for Computational Modelling '15 and then Computational Modelling '19, where the USA office was represented. At Physical Separation '19 in Falmouth it was the UK office that was represented, and then at Flotation '23, Critical Minerals '24 and Flotation '25 in Cape Town, representation came via the South African office.

Paterson & Cooke exhibited for the first time at Critical Minerals '24 and then again at Flotation '25, but we are now delighted to welcome them as first time sponsors, of Hydrometallurgy '27 and Flotation '27 in Cape Town.

Albert du Toit and Ron Rampersad, of Paterson & Cooke, with Amanda Wills at Critical Minerals '24

Hydrometallurgy '27 is the first in what we hope will be a series, and Paterson & Cooke join early sponsors Capstone Copper and Maelgwyn Mineral Services.

A spokesman for Paterson & Cooke said "Events like these play a valuable role in moving the industry forward. At Paterson & Cooke, we continue to support the advancement of hydrometallurgical solutions through practical metallurgical and process test work, engineering excellence, and deep industry collaboration. Looking forward to the conversations and shared insights that help shape the future of our industry".

Flotation '27, although 18 months away is already off to a great start, and we welcome Paterson & Cooke who join many of our regular sponsors who committed early to the 13th conference in the series.

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Friday at Mineral Processing Circuits '26

Another beautiful sunny day to end this two-day conference, with ten presentations today and a last chance to check out the four exhibitors during the long coffee and lunch breaks.

Doug Caffell, of Sepro Systems, Canada, is based in Devon, UK, and is a regular at the Cornish Mining Sundowners. Sepro is known for innovation in gravity separation technology and the company is looking forward to a strong year. While there has currently been reasons for concern or anxiety in the world, there is also a fair bit of optimism in the mining sector. In particular with gold, tin and tungsten, Sepro's specialist areas. The application of the new Frontier bowl for additional fine gold recovery as well as Continuous Falcon concentrators for fine and ultrafine tin and tungsten recovery sees Sepro well placed to service this strengthening demand.  

Amanda with Ernest Wermuth and Doug Caffell of Sepro Systems

FLS is a regular supporter of MEI Conferences, and was showcasing its latest gravity separation technologies, which allow for gravity separation into sub 75 micron scale, which is unprecedented in the industry. On display were models of the Reflux Classifier and the GradePro, which uses the same core technology as the Reflux Classifier, but is refined and optimised for recovering value from lower-grade, more challenging material, which is where the mining industry is heading. We have been fortunate to have the inventor of these machines (and the Reflux Flotation Cell), Prof. Kevin Galvin, at both conferences this week. In the photo below Kevin and FLS' Lance Christodoulou and Anson Gilbert show models of the Reflux Classifier and GradePro to Paul Miller, of Bactech Environmental Corporation, Australia and Rex Zietsman, of Globe Metals and Mining, Australia.

Paul, Lance, Kevin, Anson and Rex

Amanda closed the conference, thanking our sponsors, the exhibitors. speakers and delegates and inviting attendance at the 2nd Mineral Processing Circuits event, which will be held in February 2028, in Kuala Lumpur, Malaysia. 

Those remaining then joined us in the hotel gardens, for the first time this week, for a farewell sundowner.

A summary of the presentations, with links to the draft papers, is scheduled for publication on the blog on Thursday 7th May.

An album of photos taken during the conference is available and you may download any of these photos for your own use. For commercial use please acknowledge the source as MEI Conferences.

Reactions to the conference on LinkedIn can be found via #MineralProcessingCircuits26.

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