Flotation '25, the 12th in the series, was held at the Vineyard Hotel, Cape Town from November 17-20, 2025 and was attended by 401 delegates from 32 countries.
The following is a brief summary of the presentations delivered during the four 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 are not included in the summary. However, short abstracts for all technical session papers are available in the programme on the conference website.
Many of the 92 poster presenters also submitted drafts. The complete programme of oral and poster presentations, including links to available draft papers, can be found in the online open-access Proceedings.
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 100 papers were presented in the technical sessions. Very loosely these are grouped as:
Technical Session 1: Flotation circuits and design
Technical Session 2: Flotation circuits, AI and optimisation
Technical Session 3: Flotation reagents, innovations, green reagents, collectors
Technical Session 4: Flotation reagents, collectors, depressants
Technical Session 5: Flotation reagents, frothers, surfactants. Flotation machines
Technical Session 6: Flotation machines
Technical Session 7: Flotation of critical minerals, lithium, rare earths,titanium, vanadium, battery minerals recycling
Technical Session 8: Mineralogy, control, bubbles and froths.
Monday November 17th
Technical Session 1
Chairpersons: Kirsten Corin (University of Cape Town, South Africa) and Mehdi Safari (Mintek, South Africa)
The conference opened with a keynote lecture from Chris Greet, of Magotteaux, Australia, and was followed by presentations on flotation circuits and design.
Cong Wang is a PhD candidate at Central South University, China. He described a case study of galena in adjusting grinding media shape to optimise mineral electrochemical properties and flotation behavior.
Paulina Vallejos of the Universidad Técnica Federico Santa María, Chile, was the 2023 recipient of the MEI Young Person's Award. She presented a kinetic characterisation of three flotation banks, two in a rougher stage and one in a cleaner-scavenger operation, of a copper industrial plant located in Perú. The results were used to calibrate a simulation tool for industrial operations, allowing a more in-depth analysis of the process, including internal variables, such as froth recovery, bubble load grade, and size-by-liberation characterisation.
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| Paulina Vallejos (2nd left) |
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| Luis Cisternas |
Luis Cisternas, a professor in the Department of Mineral Processing and Chemical Engineering at the Universidad de Antofagasta, Chile is another familiar face at MEI Conferences. He provided insights into the effects of incorporating geometallurgy in the design of flotation circuits, highlighting both its benefits and limitations.
Barry Lumsden is Technical Director at Ausmetec, Australia. During his PhD, under the Supervision of Professor Graeme Jameson, Barry developed the magnetic conditioning technology that has now been tested and installed in some of the largest flotation plants. Magnetic conditioning was trialed in the cleaner flotation circuit at Oyu Tolgoi, Mongolia to enhance fine copper recovery. Barry described how the work contributed valuable insights into the dynamics of operational changes in large-scale flotation circuits and underscore the importance of both sample strategy and data timing in plant-scale evaluations.
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| Barry Lumsden (right) |
Ahmad Hassanzadeh is an independent consultant and the Chief Research Officer at Maelgwyn Mineral Services, UK. He was the recipient of the 2020 MEI Young Person's Award (posting of 15 March 2021). He showed how hybrid flotation circuits, a combination of mechanical flotation cells with reactor-separator machines, offer a solid solution to avoid losing (ultra)-fine particles to the tailings.
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| Ahmad Hassanzadeh (right) |
Mayra Jefferson, a research fellow at JKMRC, Australia, is a geometallurgy specialist with extensive experience leading geometallurgical studies and developing predictive models for greenfield and brownfield mining projects, Building on previous research demonstrating the significant influence of pyrite textures and mineralogy on flotation performance at the Mount Isa Copper deposit, this study investigates flotation behaviour differences between two selected ore samples exhibiting distinct mineralogical characteristics. Mount Isa's iconic underground copper mine officially ceased production in July after seven decades of operation, marking the end of an era for one of Australia's most significant mining operations.
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| Mayra Jefferson (2nd left) |
Junior Mulanga is a senior setallurgist at Kamoa Copper, Democratic Republic of Congo. He presented results from a deep investigation and an intensive test work program on optimisation opportunities for the Kakula Concentrator of Kamoa Copper S.A, aimed at improving copper flotation recovery with an optimised flowsheet.
The Jameson Cell is increasingly being applied in rougher flotation duties as a means of debottle-necking concentrators and addressing space constraints while delivering high metallurgical performance. Adam Price, of Glencore Technology, Australia, discussed the Jameson Cell’s effectiveness in these duties, with a particular focus on how recent design developments have enabled its use in larger throughput applications. The development of the specific suite of cells suitable for rougher and scavenger duties, capable of treating up to 4500 tph, represents a significant advancement in Jameson Cell technology. In rougher-scalping applications, the Jameson Cell has demonstrated its ability to produce final concentrate grade material, bypassing cleaning stages entirely.
Carolina Perez, of CODELCO, Chile, showed how new strategies are being used to revalue fresh and historic tailings, focusing on the recovery of critical minerals for several industrial uses. El Teniente Division already reprocesses its tailings to extract copper and molybdenum. but this study seeks to evaluate pyrite recovery through flotation using two approaches: first processing the pyrite concentrate to extract cobalt and obtain valuable byproducts; and second reducing the potential for acid drainage.
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| Carolina Perez (centre) |
Xu Jiang is a PhD candidate at Central South University, China. His research focuses on the regulation of grinding processes in sulfide ores and the design of flotation separation techniques. Copper and nickel are critical metals for modern industry and renewable energy development, making their efficient recovery imperative. In the flotation of copper-nickel sulfide ores, grinding-induced redox reactions significantly affect mineral surface hydrophobicity and, consequently, separation efficiency. His presentation examined the effects of grinding media with varying chromium contents on the collectorless flotation behavior of copper-nickel sulfides.
Technical Session 2
Chairpersons: Farhana Diba (JKMRC, Australia) and Luis Cisternas (Universidad de Antofagasta, Chile)
Lindon Pyle, of Hatch, Australia, looked at ways of improving metallurgical performance and operational reliability at the Pb/Zn flotation circuit of Zhairem, one of Kazakhstan's largest polymetallic deposits, which has rich reserves of zinc-lead,barite-polymetallic, and ferriferous-manganese ores. He detailed the flotation circuit bottlenecks and the initiatives implemented to improve metallurgical performance and operational reliability. Emphasis was given to the laboratory and on-site piloting of six Jameson Cells to manage changing oxide and sulphide ore feed blends, insufficient residence time and froth tenacity issues.
Claudia Johana Beltran Parada is a PhD candidate at Arcelormittal and the Université de Lorraine, France. Electric arc furnace dust (EAFD), a hazardous by-product of steelmaking, typically amounting to 10-20 kg per ton of steel produced, contains significant concentrations of valuable metals such as zinc (20-30%) and iron (20-40%). Claudia looked at the selective recovery of zinc and iron from electric arc furnace dust by froth flotation.
Melanie Duvenhage is a research microbiologist at AECI Mining Chemicals, South Africa. She discussed how froth flotation requires substantial water usage, prompting mines to recycle water and incorporate inadequately treated water sources. The intricate chemical and physical properties of water can influence flotation. While the effect of ions in process water is well documented,the impact of microorganisms on flotation is underexplored and numerous mines have reported operational issues in their flotation circuits potentially linked to microorganisms in flotation water. However, tailored microbial communities within controlled settings have also indicated advantageous effects of microorganisms on flotation and the study aimed to assess microorganisms in the process water of a Platreef ore mine and their effect on PGM flotation.
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| Melanie Duvenhage (3rd left) |
Soluble salt flotation faces unique challenges: operation in saturated brine creates high viscosity and complex ion chemistry; limited reagent options are further constrained by brine conditions; and particle sizes often exceed 1mm, dramatically larger than in metallic ore processing. These factors necessitate an integrated approach to circuit design. Carlos Perucca, Director of Carlos Perucca Process Consulting, Canada outlined the comprehensive methodology required to design efficient, contemporary salt flotation circuits that simultaneously address the multifaceted challenges of processing salt, potash and sulfates in saturated environments.
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| Carlos Perucca (right) |
Olivier Diat, a Deputy Director at ICSM, France, presented a study exploring a sustainable method for extracting tungsten from scheelite mining residues using a new concept, superchaotropic flotation, a technique leveraging nano-ions with low charge densities to be selective in recovery by ion flotation.This robust method enables mild leaching and sustainable tungsten recovery from complex ores, even in iron-rich conditions.
Osvaldo Bascur is Principal at OSB Digital, USA, and was the 2014 recipient of the prestigious SME Antoine Gaudin Award. He discussed the rise of artificial intelligence for maximising metal production by dynamic management of water using a digital twin. The work of Osvaldo highlights the potential of hybrid models to advance industrial process control, reduce costs, and enhance sustainability in mineral processing operations.
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| Osvaldo Bascur (right) |
Grade-recovery curves are a standard method for assessing the performance of a flotation bank and can be especially useful in determining whether changes to the design or operation of a bank have had a positive or negative impact on the performance. The challenge for industrial measurement is the substantial variability in both the feed rate and composition that can occur, making fair comparisons hard. Stephen Neethling, Professor of Minerals Processing at Imperial College, UK looked at methods for accounting for feed variability including introducing an alternative method.
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| Stephen Neethling (left) |
Paulina Quintanilla is a lecturer at University College London, UK and a recipient of the 2021 MEI Young Person's Award. Peak air recovery is a well-established indicator of optimal flotation performance, which is explicitly influenced by air flow rate, overflowing froth velocity, and overflowing froth height. Paulina discussed the quantification of the key drivers of peak air recovery using a global sensitivity analysis and Bayesian inference approach.
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| Paulina Quintanilla (right) |
Tuesday November 18th
Technical Session 3
Chairpersons: Olivier Diat (ICSM, France) and Peter Amelunxen (Capstone Copper, Canada)
The mining flotation chemicals market is undergoing significant growth, driven by rising global demand for minerals and a recovering mining sector. As ore bodies become more complex and the demand for specific minerals increases, flotation chemicals are playing an increasingly critical role and Liza Forbes, program leader - flotation chemistry, at Australia's JKMRC, set the scene for a full day on flotation reagents with her keynote lecture examining new directions in flotation chemistry research.
Sancho Nyoni is a PhD candidate at the University of Cape Town and an engineer in the Minerals Processing Division of Mintek. He looked at the effects of milling media and recycled water on pulp chemistry and flotation performance for single-mineral and mixed sulfide ores.
Gabriela Budemberg, a PhD Candidate at Luleå University of Technology, Sweden, asked what are green flotation reagents? She said that no clear definition has been developed to categorise these additive chemicals for flotation operations worldwide. Her study focused on deeply defining and classifying a green flotation reagent based on the four main pillars: sustainable raw materials, green production, biodegradability, and low toxicity. This aims to show a clear picture of some of the main reagent profiles applied in flotation nowadays and, therefore, establish the basis for providing an initial path for developing new eco-friendly reagents.
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| Gabriela Budemberg (3rd left) |
Martin Rudolph, of the Helmholtz Institute Freiberg for Resource Technology, Germany, discussed eco-friendly reagents upscaling and optimisation in froth flotation. with case studies on HF and NaSH substitution.
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| Martin Rudolph (2nd left back row) |
Kalyani Mohanty, a researcher at the Universitat Politècnica De Catalunya, Spain, studied the absorption mechanisms of quartz and K-feldspar using biodegradable chemicals and suggested a promising eco-friendly alternative to traditional collectors.
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| Kalyani Mohanti (left) |
Oznur Onel is a staff scientist at Nalco Water an Ecolab Company, USA. She has two PhDs in Mining and Minerals Processing Engineering from Virginia Tech and Dokuz Eylul University. She showed how clay minerals create significant challenges in flotation by affecting slurry rheology, froth stability, and surface interactions. Her study investigated a novel chemistry designed to minimise the impact of clay-related issues, with particular focus on non-swelling varieties.
Reverse anionic flotation is a common method for the beneficiation of iron ores, typically employing multivalent cations to activate quartz and depressants to selectively suppress hematite. Rocky Mensah, a PhD candidate in Chemical Engineering at the University of Newcastle, Australia, presented a novel study investigating the performance and selectivity of a novel bio-based collector derived from vitamin E in the reverse flotation of hematite, with CaCl₂ and soluble starch serving as the activator and depressant, respectively.
Most studies on collectors have focused on conventional flotation systems and typical particle size ranges, leaving a gap in understanding how different collector types perform under the hydrodynamic and surface chemistry constraints of coarse particle flotation. Daniel Nyarko, a PhD candidate at the University of South Australia, evaluated the performance of different collector types including xanthates, dithiophosphates, thionocarbamates and mercaptans, with a specific focus on coarse particle recovery in advanced flotation systems such as the Eriez HydroFloat.
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| Daniel Nyarko |
Copper ore deposits often contain iron sulphides, such as pyrite and pyrrhotite, which can interfere with the beneficiation process by reducing the selectivity and grade of the copper concentrate. These iron sulphides are typically associated with copper sulphide minerals such as chalcopyrite, bornite and chalcocite. Traditionally, these iron sulphides are depressed by raising the pH using lime. However, Natalie Shackleton, R&D Manager: Mining Metallurgy at AECI Mining Chemicals, South Africa, showed that a novel collector has been developed that selectively targets the copper minerals, thereby eliminating the need to alter the pH for iron sulphide mineral depression.
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| Natalie Shackleton (left) |
Yesica Botero, a post-doctoral researcher at the University of Lorraine, France, looked at an innovative approach of desulfurisation for the flotation of all sulfides in the rougher stage, followed by the selective separation of collector-activated pyrite from copper sulfides to enhance mineral recovery while promoting environmentally responsible practices. Her work focuses on the intricate surface chemistry mechanisms that are crucial for effective mineral separation. The findings reveal that it is possible to reverse the floatability of pyrite that has already been floated using H2O2, these insights proposing parameters that can be used for a selective separation of pyrite from copper sulfides in a copper-iron concentrate.
Itayi Marufu, a technical manager at Metsop, South Africa highlighted how MetSop developed Optimaviz, an advanced data analytics tool, to evaluate and optimise the performance of a new co-collector during a flotation plant trial at a South African PGM concentrator. He stressed that these findings offer valuable lessons for the industry, demonstrating how analytics can unlock performance in complex orebodies, paving the way for broader applications in flotation and environmentally responsible mining.
In a further presentation from Metsop, Liberty Chipise, research and development manager, looked at response surface modelling of co-collector interactions in the flotation of Zimbabwe's Great Dyke PGM ores, using co-collectors as partial or full substitutes for sodium isobutyl xanthate to reduce reagent costs without compromising recovery and concentrate grade.
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| Liberty Chipise |
Alfredtina Abrafi Appiah, a PhD candidate at the University of Tasmania, investigated the separation of silica from magnesite using the cationic collector Flotigam, an alkyl ether amine, in a continuous reverse flotation process. She focused on the Arthur River magnesite deposit in northwestern Tasmania, demonstrating an effective and innovative approach to purifying magnesite through reverse flotation using Flotigam.
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| Alfredtina Abrafi Appiah (right) |
Technical Session 4
Chairpersons: Ted Nuorivaara (Geological Survey of Finland, Finland) and Richard Lee (University of Queensland, Australia)
Gillian Omaga, a PhD candidate at Université de Lorraine, France, discussed the improved flotation of complex iron ore minerals using mixed cationic collectors with reduced starch dosage. The findings support the development of tailored collectors systems for complex ores of the Thabazimbi iron deposit in Limpopo, South Africa. Her presentation won one of the student prizes at the conference.
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| Gillian Omaga (centre) |
Neymayer Lima is a specialist engineer at Vale S.A., Brazil. He presented a study investigating, at bench scale, the injection of amine coated nanobubbles (NBs) in Brazilian reverse iron rougher flotation samples, both with and without the addition of microbubbles. The NBs enhance the capture of silica particles and increase their hydrophobicity, while microbubbles contribute to a higher lifting power.
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| Neymayer Lima (centre) |
Asmae El Bahi is a PhD student at Mohammed VI Polytechnic University, Morocco, She looked at advanced mineralogical insights for optimising phosphate recovery from waste rock using biobased flotation collectors.
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| Asmae El Bahi (5th left) |
Water quality is a critical yet often overlooked factor in phosphate beneficiation. Cationic species like Ca²⁺ and anions such as F⁻ can impair froth flotation by reducing collector efficiency and blocking calcite-active sites on apatite. André Braga, a laboratory coordinator at BASF, Brazil, discussed the creation of chemistry to overcome water quality issues, using tailored collectors in apatite flotation.
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| André Braga (right) |
Pyrrhotite, a common sulfide gangue mineral in copper-gold ores, presents significant challenges in flotation due to its variable surface chemistry and tendency to float when activated by dissolved ions like Cu²⁺. Its recovery not only contaminates final product concentrates but also contributes to SO₂ emissions during smelting. Traditional depressants like sodium metabisulfide (SMBS) combined with triethylenetetramine (TETA) suppress pyrrhotite effectively but pose environmental, and selectivity concerns. Richard Lee, of the University of Queensland, looked at tailored oxidised starch derivatives for enhanced selectivity of pyrrhotite depression in gold-copper flotation.
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| Richard Lee (left) |
Sodium hydrosulphide is known to depress copper sulphide minerals and has been successfully used to reduce their floatability in the selective flotation of molybdenum minerals. Gonzalo Montes-Atenas of the University of Chile and Empirica Co, discussed the impact of NaHS dosing strategies in molybdenum selective flotation.
Pentlandite-pyroxene composites are prevalent gangue minerals in platinum group metals (PGMs) ores, which reduce froth flotation efficiency by lowering concentrate grade and recovery. Martha Phasani, a senior metallurgist at Metsop, South Africa, presented a study evaluating high-substitution carboxymethyl cellulose as a depressant to suppress hydrophobic talc-pyroxene composites while preserving PGMs recovery.
The presence of organic carbon in an ore can create challenges within the flotation circuit, but also in downstream processing. The processing routes for managing organic carbon that are typically employed by the industry are pre-flotation to remove the naturally hydrophobic carbon, utilising depressants, or a combination of both. Graeme Stewart, a global development specialist at BASF, Germany, demonstrated the process improvements obtained by replacing a conventional depressant (polysaccharide) with BASF’s carbon depressant LUPROSET D-1313 in a lead-zinc concentrator that utilises carbon pre-flotation.
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| Graeme Stewart (4th left) |
Wednesday November 19th
Technical Session 5
Chairpersons: Lucas Pereira (Helmholtz Institute Freiberg for Resource Technology, Germany) and Bogale Tadesse (Curtin University, Australia)
Reagents were the main theme again for most of this session, with papers on frothers and surfactants, beginning with an opening keynote lecture from Jim Finch, of McGill University, Canada. Frothers provide three key functions: maintaining small bubble size, reducing bubble rise velocity, and contributing to froth stability. Studies have linked these to frother structure. The first two were the focus of Jim's keynote.
The key to increasing throughput at Cu-Au-Mo plants is to improve the recovery of coarse particles. Floating these coarse particles requires strong frothers. However, using these strong frothers results in a very persistent stable froth downstream in the cleaner operations resulting in poor concentrate grade. These strong frothers also affect downstream solid-liquid separation and Cu-Mo separation. Esau Arinaitwe of Syensqo, USA showed how switchable frothers behave as strong frothers in the rougher circuit, but switch to a weaker frother when the pH is increased in the regrind/cleaning stages. Esau illustrated the benefits of the switchable frothers in being able to improve concentrate grades in the cleaning stages and thickening, using a case study at a Cu plant.
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| Esau Arinaitwe (2nd left) |
The concentration of valuable minerals from low grade ores through flotation has a heavy reliance on water as both a reagent and transport medium. Most mining activities in South Africa occur in water scarce regions, resulting in competition for freshwater and large volumes of contaminated water discharge. As a result, the mining industry is exploring increasing water recirculation on site. Mthulisi Moya, an MSc candidate at the University of Cape Town and researcher at Mintek, discussed the impact of frother dosage and ionic strength of process water on the flotation performance of a PGM ore.
Frother potential refers to the combined effect of added frother, residual frother, reagents, dissolved ions,and other substances in flotation process water that influence bubble size. Accurately dosing frother is challenging due to unknown contributions from recycled water, as well as the volatility and partitioning of frother down the bank. Mark Lepage, a researcher at McGill University, Canada, applied a dilution curve methodology to determine the frother potential of flotation process water.
Air recovery is a flotation indicator of froth stability and has been correlated with overall flotation performance. Jose Martinez, a PhD student at Imperial College, UK, examined, for the first time, the influence of frother chemistry on air recovery. Results showed that, regardless of the frother type, air recovery increased with frother concentration up to a certain value, beyond which it remained relatively constant at higher dosages. these findings demonstrating for the first time a relationship between frother type and dosage and air recovery as a measure of froth stability. Jose was one of the student prize winners for best presentations.
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| Jose Martinez (2nd right) |
Floating particles at a coarse size offers significant technical, economic, and sustainability benefits, as the most profitable tailings management strategy. Coarse particle flotation (CPF) is determinant for tailings scavenging circuits and coarse gangue rejection. However, at the same time turbulence is imperative for bubble particle collision, a high mechanical energy dissipation rate that increases the centrifugal force leading to the detachment of coarse particles, unless a high enough contact angle and bubble attachment is stabilised. In this context, Livia Faustino, a project manager at Clariant, Brazil, discussed the theory and practice of new frothers and collectors suitably designed for CPF.
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| Livia Faustino (left) |
At Evolution’s Northparkes operations in Australia, flotation is employed to recover both copper and gold, as is common in other porphyry copper-gold deposits. However, a proportion of gold minerals, particularly Au-Ag tellurides, are lost to the flotation tailings despite being well liberated. Masashi Yamane, a senior metallurgist at Sumitomo Metal Mining Co. Ltd, Japan, reported that the addition of sodium silicate to the conditioning stages prior to rougher flotation significantly reduced gold losses and sodium silicate has now been permanently incorporated into the reagent scheme at Northparkes.
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| Masashi Yamane (right) |
Coarse particle flotation is challenging because of bubble-particle detachment caused by the turbulence in the mechanical cell, especially for composites with low surface liberation and limited surface exposure of valuable minerals for collector attachment. Azeez Aregbe, a PhD candidate at the University of Melbourne studied kerosene-in-water emulsions with two types of surfactants for coarse chalcopyrite-quartz flotation in a mechanical cell. One surfactant, stabilising the oil droplets, guides the adsorption of oil to chalcopyrite patches. A second surfactant then causes the oil to spread onto the gangue surfaces of the same particle. The deposited oil layer on the composite particle surface improves bubble-particle attachment and reduces detachment. The flotation results showed improved copper recovery but reduced copper grade due to the increased recovery of coarse composite particles.
Azeez's was the last of the many presentations showing innovation in flotation chemistry and reagents, and for the rest of the day attention turned to flotation machines.
Mechanical flotation cells exhibit poor recovery of coarse material. A critical challenge is maintaining particle suspension without inducing excessive turbulence, which promotes detachment from bubbles. Optimal coarse particle flotation likely occurs at the suspension impeller speed (Njs), where complete off-bottom suspension is achieved with minimal turbulence. German Lastra, a PhD candidate at JKMRC, Australia, investigated coarse particle suspension in a 1 m³ mechanical flotation cell equipped with interchangeable features, focusing on the effect of key design and operational parameters - impeller size, off-bottom clearance, baffling and air rate - on Njs. The results showed that coarse particle suspension is highly sensitive to air rate,impeller size and baffling arrangement. Impeller off-bottom clearance has a smaller but noticeable effect.
The collection of fine and ultra-fine particles requires a high level of energy dissipation, which is why intensified flotation cells have emerged. The Concorde cell is a pneumatic device that operates under moderate pressure, increasing the efficiency of particle/bubble aggregates formation. Paulina Vallejos, of Universidad Técnica Federico Santa María, Chile and recipient of the 2023 MEI Young Person's Award, presented a modelling tool built to characterise the Concorde cell.
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| Paulina Vallejos (2nd left) |
Peter Amelunxen was the first recipient of the MEI Young Person's Award, in 2011. He is Senior Vice-President, Technical Services at Capstone Copper, Canada. He discussed the compartmental model of flotation, which has become the standard approach to flotation cell modeling and simulation since its introduction 40 years ago. However, with increasing acceptance of pneumatic and other flotation cell designs, it has become apparent that this approach breaks down for dual-chamber machines. Peter described an alternative three-compartment model that can be used to model both dual-chamber and traditional single-chamber flotation machines. An application of the method is demonstrated using a pilot test program conducted at Pinto Valley’s copper/molybdenum concentrator in Arizona.
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| Peter Amelunxen |
WEMCO flotation cell technology was first developed in the 1930s, updated in 1968 and has been the same ever since. Although this robust and impressive design has been a technology standard for many decades, FLS has set out to improve the original design with a new rotor and stator configuration which improves hydrodynamic, kinetic, and metallurgical performance. Dariusz Lelinski, Global Director for FLS Flotation and Reflux Technologies, USA, reported on the performance of a WEMCO II 250m3 installed in a Cu-Mo rougher application in a South American Concentrator with comparison to a standard WEMCO.
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| Dariusz Lelinski (left) |
The scale-up of flotation machines can not only improve economic efficiency and production efficiency, but also optimise hydrodynamic characteristics, meet large-scale mining demands, and simplify operation and maintenance. However, with the continuous development of flotation machine scale-up, traditional scaling methods can hardly support the design requirements of super-large flotation machines. Ming Zhang, of the BGRIMM Technology Group, China described the development of the world's largest flotation machine (single-tank volume reaching 800m³) based on an innovative five-zone flotation dynamics framework, which optimised bubble loading capacity while maintaining hydrodynamic similarity, and improved froth transport and recovery efficiency.
Technical Session 6
Chairpersons: Osvaldo Bascur (OSB Digital, LLC, USA) and Pablo Brito-Parada (Imperial College, UK)
Nathalie Kupka, Technology Manager at Metso, Finland presented a first look at Metso’s groundbreaking Coarse Particle Flotation technology at industrial scale. Coarse particle flotation has emerged as a promising method for reducing environmental impact while enhancing operational efficiency. Metso has developed a novel Coarse Particle Flotation technology that will be launched at the end of 2025. This pneumatic flotation technology involves feed slurry on top of a deep froth and provides an alternative to the more conventional approach of fluidised beds. Testwork for a South American copper concentrator was conducted in both gangue rejection and scavenging applications, showing good promise in both duties. A demonstration plant of 25 tph was delivered to site in August 2025 and Nathalie presented first results from lab to industrial scale.
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| Nathalie Kupka (left) |
Beneficiation of low-grade iron ores is critical to meeting global steel production demands, with flotation playing a key role in enhancing the operational and environmental sustainability of the integrated steelmaking process. Pedro Mesquita, of Eriez, Brazil, described a joint pilot study by Eriez and a pioneering Indian steel producer evaluating the Eriez CavTube Column to produce DRI-grade pellet feed from a fine, banded hematite quartzite feedstock via reverse flotation. Laboratory and pilot-scale testing confirmed the CavTube Column’s metallurgical scalability and superior separation over mechanical and jet-induced pneumatic flotation cells piloted in parallel.
Invented by Prof. Graeme Jameson and licensed to Metso, the Concorde Cell is a high-intensity pneumatic flotation technology dedicated to the flotation of fines and ultrafines. Berivan Tunç, Flotation Test Work Manager at Metso, Finland, presented a study which confirms the potential of Concorde technology to advance reverse flotation processes for producing high-quality DRI-grade iron concentrates from low-grade ores.
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| Berivan Tunç (left) |
A Concorde Cell was commissioned and taken into operation at Boliden's Kevitsa Cu-Ni-PGM concentrator in Finland in January of this year. Metso Technology Manager Toni Mattsson, reviewed the performance of the industrial scale Concorde cell in the tested Ni cleaner flotation applications.
The latest invention by Graeme Jameson is the the NovaCell, an innovative flotation device with distinct recovery zones for coarse and fine particles. Jord, of Australia holds exclusive global commercialisation rights and Technology Manager Sherwin Morgan assessed the NovaCell's performance at the Pinto Valley copper mine in Arizona, in the coarse particle flotation circuits. The analysis provided valuable insights into current practices and highlighted the potential to adopt more sustainable mining techniques through the adoption of NovaCell technology.
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| Sherwin Morgan (left) |
In late 2024, a NovaCell pilot plant was installed at Capstone Copper’s Mantos Blancos site in Chile to process rougher tailings and validate promising 2023 laboratory results. As explained by Alfonso Flores Carrilo, of Capstone Copper, Chile, the pilot cell consistently exceeded expectations for upgrade ratio and mass pull. the results supporting advancing to full-scale design and installation of the Jord’s NovaCell at the Mantos Blancos operation.
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| Alfonso Flores Carrilo (left) |
Eriez's HydroFloat Coarse Particle Flotation (CPF) has had significant attention in the mining industry due to its potential to improve the profitability and environmental sustainability of mining projects. Despite these advantages, evaluating the integration of CPF into mineral processing circuits remains technically challenging given its interactions with preceding or succeeding flotation circuits, grinding requirements, tailings disposal, and overall plant design. Drew Hobert, of Eriez, USA, presented a study investigating the application of the Integrated Extraction Simulator of Orica, Australia, as a comprehensive tool for simulating and assessing the implementation of CPF in both pre-concentration and tailings scavenging duties within a 100 ktpd porphyry copper processing plant. The results highlight the value of simulation in guiding design decisions and evaluating trade-offs when integrating CPF into large-scale copper operations.
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| Drew Hobert (2nd left) |
The HydroFloat cell has advanced the recovery of coarse particles by leveraging a fluidised bed environment to overcome the limitations of conventional flotation. However, the presence of fine particles in the feed presents significant challenges to both bed stability and metallurgical performance. While desliming is commonly applied to control fines content, some fine material inevitably remains, and its impact on fluidisation dynamics and separation efficiency is not yet fully understood. Richel Dadzie, a PhD student at the University of South Australia, investigated the effects of fine particles (<53 µm) on fluidised bed flotation performance through a series of controlled laboratory-scale experiments. The results underscore the importance of fines management in HydroFloat operations.
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| Richel Dadzie (right) |
Shiva Chahardahmasoumi is a PhD student, supervised by Prof Galvin at the University of Newcastle, Australia, focusing on fundamental bubble-particle interactions in the tubular spargers of Prof. Galvin's invention, the Reflux Flotation Cell. Shiva looked at ways of promoting fine and coarse particle flotation performance using the REFLUX Flotation Cell.
Homie Thanasekaran, Global Product Manager at Eriez, Australia, showed how Eriez's StackCell technology introduces a revolutionary two-stage flotation paradigm that decouples particle collection from froth recovery. The first stage uses a high-shear environment to maximize bubble-particle collisions and attachment rates, while the second stage provides a quiescent, low-turbulence zone that promotes efficient froth recovery with reduced entrainment. This separation of functions allows for significant improvements in metallurgical performance, particularly for fine particles, while maintaining a compact plant footprint.
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| Homie Thanasekaran (2nd left) |
Separation of ultrafine magnesite from dolomite tailings is challenging due to the poor floatability of fine particles and the similar surface characteristics of magnesite and dolomite. Olcay Ayoglu, a Doctoral Researcher at the University of Oulu, Finland, explored the application of a laboratory-scale pneumatic Imhoflot V-018 flotation cell, manufactured by Maelgwyn Minerals Services, UK, to enhance ultrafine magnesite recovery.
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| Olcay Ayoglu (right) |
Thursday November 20th
Technical Session 7
Chairpersons: Amal Abbou (University Mohammed VI Polytechnic, Morocco) and Kevin Galvin (University of Newcastle, Australia)
The global demand for lithium is expected to outpace supply over the coming decades; governments around the world have responded by incentivising the rapid development of their lithium resources,including hard-rock mineral deposits. To extract lithium from hard rock ore, lithium-bearing minerals first must be separated from associated gangue by two primary methods: dense media separation and/or flotation. Dense media separation is a straightforward process with relatively low operating costs, making it a preferred processing route for lithium mineral recovery. However, when finer grinding is required to liberate lithium minerals from ores with greater mineralogical complexity, flotation is the critical method of separation.
In her keynote lecture, which set the scene for a full technical session on the flotation of critical minerals, Charlotte Gibson. an Assistant Professor at Queen's University, Canada, explored the industrial history of lithium mineral flotation around the globe, highlighting practical challenges and gaps in our understanding of flotation mechanisms. A review of recent advances in lithium flotation research reveals a pressing need to expand global research and innovation capacity in the field, from reagent development to bespoke equipment design.
Aubin Tshibanda, is a PhD student at Liege University, Belgium and University of Kolwezi, Democratic Republic of Congo. He examined the sequential flotation of spodumene and lepidolite from a mixed ore from the Manono deposit in the DRC.
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| Aubin Tshibanda (left) |
Spodumene separation from gangue minerals like quartz is challenging as both silicate minerals are activated by metal cations, naturally present in process water, such as Ca2+. Espoir Murhula, a PhD Candidate at Queen's University, Canada. showed that Na2CO3, used as a pH modifier in the industrial flotation of spodumene, can depress both minerals in the presence of Ca2+, but the mechanisms remain unclear. His research examined the interaction of Na2CO3 with Ca-activated quartz and spodumene surfaces and the consequences for their selective flotation. Overall, the study demonstrated that, in addition to being a pH modifier, Na2CO3 acts as a selective gangue depressant in the spodumene flotation system. Since quartz is the main gangue in most flotation systems, these findings can be extended to benefit other flotation systems.
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| Espoir Murhula (centre) |
Rare earth elements (REEs) play pivotal roles in modern technologies, from clean energy and defence applications. Jing Liu, a senior metallurgist at SGS Natural Resources, Canada, presented a compilation of recent case studies focused on rare earth flotation, including flowsheet development, laboratory trials,and pilot plant operations. Various mineralogical compositions, ranging from bastnaesite and monazite to xenotime and allanite were examined alongside their associated gangue minerals such as calcite, dolomite, ankerite, silicates, and iron oxide. This provided insights into REE behavior based on recent studies, highlighting the influence of mineralogical composition and texture on their extraction behaviours.
Bogale Tadesse, an associate professor at Curtin University, Australia, showed how there has been little research on the flotation of rare earth minerals in the presence of water impurities. He examined the impact of specific anions, such as Cl-, SO4 2- and HCO3- on the flotation performance of a rare earth ore.
In the recycling of battery materials, black mass refers to the fine residue following the shredding and removal of copper, aluminium, steel and plastic components that make up the battery casing and wrapping. Black mass primarily consists of graphite as the anode material and metal oxides (including Li, Ni, Mn, Co) that make up the cathode. Will Ng, a research fellow with the University of Melbourne, presented work in applying flotation-based solutions to the separation of the anode and cathode materials, and discussed some of the key learnings and outcomes. Studies are ongoing to determine the performance of the recycled graphite as well as the reusability of the metal oxide tails following purification.
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| Will Ng (3rd right) |
Marek Pawlik, a professor at the the University of British Columbia, Canada showed how the separation of black mass from recycled batteries by froth flotation relies on the natural hydrophobicity of graphite (anode active material) and high hydrophilicity of metal oxides (cathode active materials). He discussed the factors which negatively impact the separation results, oxidation of graphite and the presence of oxidation products in water, organic coatings on black mass particles, and the very fine nature of black mass particles were found to be the main issues.
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| Marek Pawlik (left) |
The global push towards electrification is driving a sharp rise in silver demand, raising concerns about long-term supply security and the environmental impacts of conventional extraction methods. End of life (EoL) photovoltaic (PV) panels represent a promising secondary source of silver, with concentrations typically ranging from 300 to 500 ppm, comparable to high-grade primary ores. The volume of decommissioned PV panels is projected to exceed 60 million tonnes globally by 2050. If not properly managed, this waste stream could become a significant source of landfill burden and valuable resource loss. Current recovery approaches are dominated by acid leaching, which is chemically intensive and environmentally burdensome. Hamidreza Saffarian, a PhD student at the University of Newcastle, Australia, introduced a paradigm shift in PV recycling by applying physical separation techniques rooted in conventional mineral processing and beneficiation. specifically for the first time demonstrating the effectiveness of froth flotation as a pre-treatment step to selectively concentrate metallic silver prior to leaching.
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| Hamidreza Saffarian (right) |
Titanium and vanadium are critical materials for the modern society, essential for advancing technology, improving infrastructure, and supporting sustainable energy solutions. However,they are not extensively mined in Europe due to limited techno-economic feasibility. Ted Nuorivaara, a researcher at the Geological Survey of Finland, presented a study seeking to enhance the viability of their extraction by establishing a foundation for efficient flotation, utilising novel processing techniques. The chosen approach comprises grinding in an inert (N or CO2) atmosphere as well as using a combined microflotation technique, which have demonstrated improved flotation performance in the presence of low-grade metal sulfide ores.
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| Ted Nuorivaara (centre) |
Eiman Amini, Executive Director at MinDet, Australia, discussed the development of a module which performs rapid mineralogical analyses, providing plant operators with actionable insights in real time to optimise operations. MinDet utilises machine vision and a trained AI algorithm to estimate the modal mineralogy of a slurry stream in real time. The algorithm continuously analyses samples from the slurry stream, reporting mineralogy by size, particle size distribution, mineral liberation, and associations within the slurry particles.
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| Eiman Amini (4th left) |
Taswald Moodley, Principal Engineer at Mintek, South Africa, described work to design a flowsheet that maximises Cu recovery while minimising gangue entrainment. Using modal, deportment, and liberation data from a mineralogical scoping study, a mass-balance model was developed to predict theoretical recovery limits for both true flotation and total recovery (including entrainment). If validated, this framework could predict performance, grind targets, and reagent schemes, minimising the need for costly testwork in similar low-grade copper ores.
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| Taswald Moodley (2nd right back row) |
Lucas Pereira, of Helmholtz Institute Freiberg for Resource Technology, Germany is a keynote speaker at next year's Process Mineralogy '26. He showed how operating flotation plants predictively, instead of reactively. is challenging given the compositional variations of the feed material, where only chemical assays are typically insufficient. This challenge is even more pronounced when the target metal is within minerals of unique flotation behavior, e.g. primary and secondary Cu-sulfides together with Cu-oxides and Cu-bearing silicates. This complex assemblage can be found in the Kansanshi Mine in Zambia, the case study investigated by Lucas aiming to quantify the most important mineralogical properties when forecasting the flotation circuit recovery. The results shed light on the most meaningful mineralogical properties controlling plant recovery, serving as the basis for better troubleshooting daily operations.
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| Lucas Pereira (left) |
Mineral processing plants rely on online slurry analysers for real-time elemental analysis, crucial for optimising extraction processes. However, complex ore structures pose challenges that traditional methods cannot address, necessitating advanced techniques for effective response to variable feedstocks. Nur Muhamad, of Thermo Fisher Scientific, Australia discussed Prompt Gamma Neutron Activation Analysis (PGNAA) technology, which revolutionises process control in iron ore flotation plants by providing accurate, real-time elemental analysis of multiple slurry streams, including light and heavy elements.
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| Nur Muhamad (centre) |
Positron Emission Particle Tracking (PEPT) is a powerful technique for resolving multiphase flow in flotation systems. Diego Mesa, a research fellow at Imperial College, UK, introduced novel "mixed" PEPT tracers designed to emulate partially liberated particles, with controlled ratios of hydrophobic to hydrophilic surface exposure. These tracers were tracked in a continuously overflowing flotation cell at PEPT Cape Town, under realistic three-phase operating conditions. The approach offers a more mechanistic understanding of how partial liberation influences particle transport, flotation zone transitions, and ultimately, separation performance, highlighting the potential of PEPT to quantify the role of composite surface properties in flotation fluid dynamics.
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| Diego Mesa (2nd right) |
Technical Session 8
Chairpersons: Jim Finch, McGill University, Canada and Espoir Murhula (Queen's University, Canada)
Residual flotation reagents in process water can have adverse effects on the flotation performance and the environment (e.g., frother buildup). The treatment of process water to remove residual reagents enables the water to be recycled, reducing water consumption and minimising environmental impacts. Ken Rahal, of FLS, USA, showed how the degradation of flotation reagents by ultra-violet irradiation is an attractive approach as it is simple to operate and does not require additional chemicals.
Marnus Olivier leads the Advanced Process Control (APC) team at Stone Three, South Africa. He discussed the benefits of automated control and metallurgist-led initiatives (blending strategies, grind size control, reagent dosing, mass pull targeting, and standardising operating philosophies) of an industrial copper-silver flotation circuit. The recent installation of advanced process control improved the stabilisation of flotation bank feeds and flotation cell levels, which allowed metallurgists to improve overall recovery through the previously mentioned initiatives.
Microbubbles are bubbles less than 100 µm in size. They are solving the problem of fine particle recovery by flotation. However, microbubbles lack buoyancy. Minuk Jung, a PhD student at the University of New South Wales, Australia has explored the use of acoustic agglomeration to recover fine particles by segregating the microbubbles from the tailing flow. The findings provide valuable guidance for designing advanced microbubble flotation reactors to enhance the kinetics and separation efficiency of ultrafine particles.
Bubble-particle attachment is a vital flotation subprocess governed by complex physical and chemical principles. Though informative, traditional experimental flotation techniques often fail to isolate attachment from collision and detachment effects. To address this, Guihua Zheng, a PhD candidate jointly with the China University of Mining and Technology and the University of Queensland, presented a novel method utilising rising bubbles and a stationary particle bed to quantify attachment dynamics and efficiency. The study examined both spherical and non-spherical particles, revealing the significant influence of particle shape on attachment efficiency and flotation kinetics. This offers a fresh perspective on the role of colloidal interfacial interactions. These findings offer significant insights into bubble-particle interactions, enhancing flotation modeling and optimisation. Guihua was one of the student prize winners for best oral presentations.
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| Guihua Zheng (right) |
Varying feed conditions, operational challenges, changing mineralogy and suboptimal reagent dosing can cause abnormal and undesirable events that destabilise and reduce flotation performance. An industrial case study on the use of real-time pulp measurements to detect abnormal events and aggregate their impact on flotation performance to support early intervention by metallurgists was presented by Attie Haasbroekt, of Stone Three, South Africa. Since mechanisms of flotation in the pulp and froth phases are complex, multivariate, and sensitive to disturbances, the availability of real-time pulp bubble measurements can provide valuable information on flotation performance to allow timely corrective actions.
Sebastian Maaß, CSO at SOPAT GmbH, Germany, highlighted the value of inline, real-time measurements based on microscopic technologies for measuring the bubble size distribution in flotation cells as well as the particle size of the slurry. Inline bubble size data have not been a standard in the mining industry, but image analysis with the new possibilities of AI has the potential of becoming that standard. However, the training of the AI needs to be automated and efficient and the presentation showed ways to overcome these challenges.
Froth monitoring has great potential for optimising flotation processes as the froth phase strongly influences the overall flotation performance. The overflowing froth height is commonly used to estimate the air recovery, and typically measured point-wise using laser distance sensors based on a time-of-flight principle. Tine Marquardt, a PhD student at Helmholtz-Zentrum Dresden-Rossendorf, Germany, presented laser triangulation and stereo photogrammetry as non-invasive trigonometry-based techniques for determining the froth surface shape. Overall, measuring the froth surface shape across an area provides a more accurate basis for estimating the air recovery and offers valuable insights into froth rheology, highlighting the potential for enhanced froth monitoring and process control.
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| Tine Marquardt (3rd left) |
The mining industry struggles with low copper and molybdenum recoveries, especially from low-grade ores. Copper is often associated to gangue, while clays and phyllosilicates worsen slurry rheology and reduce flotation efficiency. Molybdenum recovery is further affected by calcium and magnesium ions. These challenges highlight the need for new technologies to improve metal recoveries. Leopoldo Gutierrez, a Professor at the Universidad de Concepción, Chile, presented a study investigating the use of the patented BCR (bubbles conditioning reactor) technology which involves coating air bubbles with flotation collectors to enhance particle-bubble adhesion. Improved adhesion led to markedly increased recoveries of valuable metals, specifically copper and molybdenum.
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| Leopoldo Gutierrez (right) |
A final thanks to all those who presented their work at the conference, and we hope to see you all again at Flotation '27.
Reactions to Flotation '25 can be seen at #Flotation25.
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