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.

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