Sunday, 31 May 2026

May summary: sad news from South Africa, and the first heatwave of the year

None of the MEI team were at home on the first of the month. Amanda was in the Isles of Scilly, competing in the annual World Gig Championships.

Jon and family were camping in Nommerlayern, Luxembourg and Barbara and I were enjoying our last day at Plettenberg Bay, before the long taxi ride to George airport the next day, a short flight to Cape Town, the long flight to London and the long train journey to Cornwall.

A farewell to Plettenberg Bay

There was also sad news from South Africa early in the month. A memorial was held at the University of Cape Town on the 8th of the month, for Martin Harris, who died the previous month at the age of 66.

After completing his Masters degree at UCT, Martin joined the Centre for Minerals Research (CMR) in 1987. and made many contributions to the research carried out at the CMR. His initial involvement was in coal processing under the tutelage of his Master’s supervisor Professor JP Franzidis. Subsequently he specialised in the area of flotation circuit modelling, playing a key role in the development of flotation models under the AMIRA P9 project as one of the lead flotation researchers in that international flagship project. He attended few conferences, apart from some IMPCs and his last MEI Conference was fifteen years ago at Flotation '11, although Jon has good memories of socialising with him at the Centenary of Flotation in 2005. Tributes to Martin can be found on LinkedIn.

It is a while since I undertook a serious hike on the Cornish coastal path, part of the 630 miles (1014 km) South-West Way. The Cornish section is 300 miles (480 km) long and is notoriously rugged with many up and down sections. I can cope easily with the uphill sections, but struggle going downhill due to ancient knees!

Although the north coast, exposed to the Atlantic Ocean, has the most strenuous walks, there are some tough walks on the south-east path from St. Mawes to the Devon border and I have only done a few hikes along this stretch, a tough one being Carne Beach to Portloe, then on to Portholland, and especially Mevagissey to Charlestown, probably the most demanding hike on Cornwall's south coast. This month Amanda and her rowing friend Mo, walked the 77 miles from St. Mawes to Plymouth in six days. 

Amanda at Mevagissey harbour ready for the gruelling walk to Charlestown
Replica of the Nao Santa María in Charlestown harbour.
The ship is a full-scale replica of the 15th Century sailing ship used by
Christopher Columbus on his first expedition across the Atlantic in 1492.
Although the hike is generally considered moderate overall, Amanda and Mo welcomed their overnight stops, remarking that there are definitely some demanding sections as the path constantly goes down into coves and back up cliffs, so the cumulative ascent is substantial.
A welcome stop at Portloe

Mixing with the locals in Plymouth

Luckily the weather was perfect for hiking, unlike the following weekend where the UK was hit by a heatwave, with temperatures well over 30C recorded. Temperatures reached 27C here in Falmouth, and the beaches were packed during the Bank Holiday weekend, when Jon and family called in for a few days, giving us the opportunity for a family reunion on the beach.

Falmouth's Gyllyngvase beach, Bank Holiday Saturday
Family reunion on the beach

#MEIBlog

Thursday, 28 May 2026

Mining the Pixels: AI Image Processing for Mineral Processing

Artificial intelligence (AI) enabled image processing is rapidly becoming a core measurement layer in modern mineral processing, converting visual process states into quantitative variables for monitoring, optimisation, and, less commonly but most invaluably, closed-loop control. Yet the field remains fragmented: flotation research focuses on froth and bubble interpretation; comminution applications focus on conveyor-based fragmentation and oversize detection; ore sorting emphasises sensor physics (often XRT/HSI) and classification; and mineralogical characterisation leverages microscopy and 3D X-ray volumes for phase segmentation and liberation metrics. 

At MEI's inaugural AI in Mineral Processing '27 conference in Cape Town, Saeed Chelgani, of Luleå University of Technology, Sweden, will present a keynote lecture unifying these streams under a single "industrial AI vision" framework that spans sensors, model classes, deployment constraints and process value pathways.

Saeed will show how current AI vision systems are used at the industrial scale in mineral processing, where they fail in practice; which emerging computer-vision paradigms, mature in adjacent high-technology domains but underused in mineral processing, offer opportunities to improve robustness, generalisation, and interpretability; and how these opportunities can be realised.

Although Convolutional Neural Network (CNN) based architectures and standard object detection models remain the dominant approach for mineral processing tasks such as bubble segmentation and particle sizing, their performance often declines when applied across changing ore bodies. In most cases, they also offer limited support for explicitly modeling temporal dynamics or prediction confidence. 

Saeed will suggest that the next leap in industrial performance in mineral processing requires integrating next-generation architectures such as Vision Transformers (ViTs), Graph Neural Networks (GNNs), and foundation and diffusion models. Together, these models offer superior handling of complex texture discrimination and can be retrained and fine-tuned via self-supervised learning to address the lack of high-quality labeled data. By shifting toward generative pipelines for synthetic data augmentation and adopting Bayesian or conformal approaches for safety-critical decisions, the field can move away from fragile, label-hungry models toward more resilient systems that better support operational reliability

Saeed is a professor of mineral processing and the Director of the Swedish School of Mines at Luleå University of Technology. His work primarily focuses on mineral processing, particularly flotation separation, AI modeling, surface chemistry, and the development of materials for both primary and secondary mineral processing. His research spans from fundamental studies on particle-bubble interactions to applied projects in battery recycling, green flotation mechanisms, chemicals, and new reagent development. Currently, he is involved in projects on lithium-ion battery recycling, phosphate flotation in collaboration with LKAB, and AI modeling of industrial units.

#AI27
#MEIBlog

Monday, 25 May 2026

A spectacular journey over the mountains from George to Cape Town

The International Mineral Processing Congress  and MEI's Process Mineralogy '26 and Critical Minerals '26 are only 5 month's away (posting of 18th May) and there will be many for whom this will be a first visit to South Africa and the beautiful Western Cape region.

I hope that you will stay on after any of these events to sample what this amazing country has to offer. Staying on in Cape Town is a good choice, but if you would like to take a truly memorable experience home with you, I can recommend a 6 day (minimum) spectacular drive from George, over the mountains via two scenic mountain passes, the Karoo desert, a quirky old town, and some of the finest wine districts. Barbara and I have travelled this route several times and recommend it as a great South African 'taster'. 

The town of George is 435 km from Cape Town, but there are regular one-hour flights from Cape Town International Airport to the airport at George, and cars can be rented from here. Because of the easily accessible airport, George is often regarded as the start of the famous Garden Route, the N2 motorway taking you east to the resorts of Wilderness, Knysna and Plettenberg Bay. This is a favourite tourist route but I find it personally underwhelming as the famous route is mostly just the N2 highway, and large parts are inland, suburban, forested, or commercial rather than constantly scenic ocean views. Over-development has changed the feel in some areas. Locals and environmental groups frequently complain that estate developments, road traffic, and urban sprawl are eroding the old "untouched paradise" image.

Travelling inland from George is, however, an overwhelming experience.

After a first night in George, the drive between George and Oudtshoorn is one of the classic short scenic road trips in South Africa’s Garden Route region. It is only about 60 km and usually takes 45-60 minutes. Heading north on the N12 a gradual climb leads to the Outeniqua Pass, a winding mountain road through the dramatic Outeniqua Mountains, with great viewpoints over valleys and mountains.

Barbara, Amanda and Jon on the Outeniqua Pass, 1982

Then there is a sudden landscape shift to green mountains and the dry semi-desert Karoo leading to Oudtshoorn, the ostrich capital of the world. The town built its wealth in the late 1800s and early 1900s on the ostrich feather boom and even today visitors are welcomed to some of the large ostrich farms around the town.

Oudtshoorn

A short detour from Oudtshoorn is to the Cango Wildlife Ranch, renowned for its cheetah conservation, operating one of the world’s largest cheetah breeding centres and maintaining some of the highest survival rates for cubs globally.

The nearby Cango Caves is one of South Africa’s most famous natural attractions. The massive limestone cave system contains dramatic stalactites and chambers and options range from easy guided walks to adventure crawling routes.

Cango Wildlife Ranch and Cango Caves, 1982
I would recommend an overnight stop in Oudtsdoorn and then the next day keep fingers crossed that the R328 to Prince Albert is open as the Swartberg Pass is one of the most famous mountain roads in South Africa, a dramatic gravel pass crossing the Swartberg Mountains. It is widely considered one of the great scenic drives in the country. The southern Oudtshoorn side climbs gradually through red rock formations and then becomes steeper near the summit at 1580m. The northern side descending toward Prince Albert is the most dramatic, with classic zigzags and sheer drops, but despite the exposure, most of the pass is manageable in a normal car in dry weather if driven slowly and carefully.
Swartberg Pass, 1997
Built in the 1880s the pass is considered an engineering masterpiece because it was constructed largely by hand using dry-stone retaining walls, which have survived more than a century of weather, floods, and mountain conditions.
Swartberg Pass, 2008, showing dry stone retaining walls
If the Swartberg Pass is closed due to bad weather, the best alternative from Oudtshoorn is the N12 to De Rust through Meiringspoort, which is also spectacular, and then the R407 to Prince Albert, a great place for a third overnight stop. Prince Albert is known for its well-preserved Cape Dutch and Victorian architecture and has developed a reputation for quality food. There is an abundance of accommodation from historic guesthouses to farm-style cottages and we have always stayed overnight at the Dennehof Karoo Guest House, set in a restored 19th-century homestead.
Prince Albert
The next day is a leisurely 160 km drive from Prince Albert to Matjiesfontein, a classic Great Karoo road trip through some of the most open, quiet, and scenic semi-desert landscapes in the Western Cape, where wild flowers suddenly bloom after heavy rain.
Wild flowers in the Great Karoo
The R407 leads to the N1 motorway and on to the little village of Matjiesfontein, an historic village, known for its well-preserved Victorian architecture and railway heritage. Founded in the late 19th century, it gained prominence as a fashionable health resort and a key stop on the Cape’s main railway line (the famous Blue Train makes its only stop here on route to Pretoria from Cape Town). 
It's definitely worth spending a night here at the historic Lord Milner Hotel in the centre of the village. The Lord Milner is part hotel, part museum-piece, and part old colonial time capsule.
The Lord Milner Hotel, 2008
The London bus village tour and a great pub atmosphere in the hotel
Back on the N1 the drive from Matjiesfontein to Worcester is one of the classic Western Cape transitions, leaving the stark, open Karoo and gradually descending into fertile wine country framed by dramatic mountains.
Wine country near Worcester
Worcester is the gateway to the wine districts and from here you can explore the Robertson, Paarl and Stellenbosch wine routes, but if time is limited I recommend taking the road to Franschhoek, one of the most beautiful towns, with some of the best restaurants in South Africa. One of our favourites is La Petite Ferme, with its stunning views of the Franschhoek Valley, but there are many wine estates with fabulous views and food.
La Petite Ferme, 2008
Lunch at Mont Rochelle Estate, 2009
When you feel the time is right to leave Franschhoek, I suggest a great full day journey back to Cape Town via three short stops. Leave Franschhoek on the R45 towards Paarl then take the R310 towards Stellenbosch, but shortly after joining the R310 drop into Boschendal, one of the country's most famous and historic wine estates, dating back to 1685. Boschendal is a great place to stop for morning coffee, or for wine tasting under the shade of the oak trees.
The Manor House at Boschendal
Wine tasting, 2008
Back on the road, the R310 takes you to the second oldest town in South Africa, Stellenbosch. Founded in 1679, Stellenbosch is best known for its Cape Dutch architecture, oak-lined streets and its main avenue, Dorp Street, which is often called a "museum street" because the architecture and urban layout are preserved so well that the entire street functions like a walk-able exhibition of centuries of town history. It's also a great place to eat before moving on to the last stage of our journey.
Dorp Street, Stellenbosch
Take the R44 south from Stellenbosch to Somerset West and then exit toward Lourensford Road to the Vergelegen Wine Estate, one of the standout destinations in the Cape Winelands. It is famous for its heritage gardens and preserved Cape Dutch architecture and for its fine wines.
Vergelegen
From Vergelegen it is only about 30-40 minutes to Cape Town International Airport, and to Cape Town itself a further 30 minutes or so, along the N2. The end of a fantastic journey, which I am sure you will never forget. I rate it the best road journey in South Africa, but if you have other ideas please let us know.

Friday, 22 May 2026

May Cornish Mining Sundowner, with welcome guests from the North

There was a good turnout for the May Cornish Mining Sundowner last night, with around 25 represented at Falmouth's Chain Locker.

A surprise guest was a CSM student from half a century ago, Sam Wood, who had travelled the 350 miles from his home in Buxton just for the sundowner.

Sam Wood 2nd right

And from the opposite side of the Pennines it was good to see Laura Smith again, from the School of Earth, Environment & Sustainability at the University of Leeds. She attended the May sundowner last year, when she was visiting Cornwall as her group of social scientists was conducting research on UK sourcing of critical materials in the context of the energy transition and was developing case studies of Cornwall's lithium and tin as well as Aberdeenshire's nickel. 

This year the group has two mining-related projects, the first a piece of research looking at the dynamics of tungsten mining in Europe, with Hemerdon mine (Tungsten West) in Devon and Salau mine in France as case studies. Laura would like to speak to a range of stakeholders about the past, present and future of Hemerdon Mine. If anyone is interested please email Laura: L.e.smith1@leeds.ac.uk. Luckily last night she got the chance to talk to Klaas (KP) van der Wielen, consultant with Ausenco, who was plant metallurgist at Hemerdon from 2015-17.

Laura and KP

The other project is ‘Grounded Engagement’ and is a participatory film project, bringing together mining stakeholders to create stories about the revival of mining in Cornwall. This will involve geologists, anthropologists, community groups and sustainability consultants coming together to talk about community engagement during mineral exploration and how creative methods can help us better understand people’s experiences and perspectives. The workshop will take place in Redruth on June 3rd and 4th, and Laura would like to hear from you if you are interested in getting involved.

The price of tin has risen 45% this year, to $55,000 per tonne and China has a stranglehold on supplies so it was good to see Cornish Metals featured in an article in The Times last week. Cornish Metals' South Crofty mine in Camborne struggled after the tin price collapsed to $4000 per tonne in 1985, where it remained for two decades.

Hopefully the mine will start production again in two years time, producing 4,700 tonnes/year at an operating cost of $13,400/tonne. Pumping water from the mine is well under way and mining permits are agreed until 2071. It is hoped that the project could directly employ up to 300 people and bring more than 1000 jobs into this deprived area. There is a strategic need for more tin supplies outside of Asia and a future market expected to drive demand for tin, a critical metal, an essential ingredient in the solder required for nearly all electrical equipment.

The next Cornish Mining Sundowner is on Thursday June 18th at the Chain Locker from 5.30pm.

#MEIBlog

Thursday, 21 May 2026

Reactions to blog posts

We really appreciate all the interaction that we get to postings on the blog, mainly via LinkedIn. All the blog postings are listed chronologically on LinkedIn via the hashtag #MEIBlog. Clicking on this hashtag shows the postings and all their likes, reposts and comments.

Our most active recent hashtags are #PhysicalSeparation26 and #MineralProcessingCircuits26 where postings on Physical Separation '26 and Mineral Processing Circuits '26  from LinkedIn members are compiled.

There have also been comments directly to the blog since the last update:


If you do not have a Google account, the simplest way to add a direct comment is by selecting 'anonymous' as your profile, but please leave your name and affiliation in the comment. Alternatively, email your comment directly to bwills@min-eng.com.
If you would like a weekly email alert to postings on the blog, please subscribe here.

Monday, 18 May 2026

Cape Town: a hub for mineral processing in 2026

Cape Town is the place to be this year if you are a mineral processor. MEI's two smallest conferences, Physical Separation '26 and Mineral Processing Circuits '26, were held at Cape Town's beautiful Vineyard Hotel last month, and now there is a five month gap in which we look forward to three major conferences in South Africa's spring, the best time to be in Cape Town.

The XXXII International Mineral Processing Congress will be one of the most influential global gatherings in mineral processing, hopefully bringing together over 1000 professionals and academics from more than 50 countries, including leading universities, major mining companies, and global technology providers. Hosted at the Cape Town Convention Centre in the City Bowl, with its iconic view of Table Mountain, the congress creates a platform for knowledge exchange, collaboration, and the latest innovations shaping the future of the industry.

If you are a first-timer to South Africa, this IMPC video will show you what to expect from this wonderfully diverse country and particularly its jewel in the crown, Cape Town, and the South African section of the blog might whet your appetites for ideas for staying on after an event.

MEI is an IMPC media partner and we will be represented at the congress by Amanda, Will and me. Barbara and I, and Will and his girlfriend, have decided to remain after the IMPC finishes and base ourselves at Green Point, close to the Cape Town Waterfront. A wonderful place to spend some time, as there is so much to see and do in Cape Town, with its multitude of high quality restaurants, and Ubers are never more than a few minutes away to whisk you to the world's most beautiful wine estates, beaches and mountain hikes.

Just over 3 weeks after the end of the IMPC, as the early summer warms Cape Town, we move to the other side of the Mountain for MEI's Process Mineralogy '26 and Critical Minerals '26, with the full MEI team in attendance.

Table Mountain from the Vineyard Hotel

Process Mineralogy '26 is the 8th in this popular series and there is now a final call for abstracts. We invite you to submit your abstracts for review by the end of this month.

Critical Minerals '26, the 2nd in the series, immediately follows Process Mineralogy '26 and abstracts are invited by the end of the month.

A lot to look forward to in the Mother City later in the year!

#IMPC26
#ProcessMineralogy26
#CriticalMinerals26
#MEIBlog

Thursday, 14 May 2026

Critical Minerals ’26: Copper Demand, Substitution, and the Future of Processing

Critical Minerals ’26, the second in the series, is shaping up very well, with abstracts already submitted covering a broad range of critical minerals, including both recycling and primary processing routes.

Copper remains one of the most important critical minerals. Modern society is deeply dependent on it, as it sits at the centre of how we generate, transmit, and use electricity and heat. It is essential for electric grids, electric vehicles, renewable energy systems, data centres, and emerging AI infrastructure. Electrification alone significantly increases copper intensity, electric vehicles typically using two to three times more copper than conventional petrol vehicles. At the same time, grid expansion and the rapid growth of AI-driven data centres are adding sustained, long-cycle demand (see also posting of 22 September 2025).

While forecasts vary, the overall direction is clear; copper demand is expected to continue rising annually in the near term. Longer-term projections indicate a substantial structural supply gap unless new mining capacity is brought online at an accelerated pace. However, supply is increasingly constrained by declining ore grades, long development timelines for new mines, often 10 to 20 years, ESG-related delays, and operational disruptions due to mine outages.

We are pleased to welcome Martin Lynch to his first MEI Conference. The son of the legendary Alban Lynch, Martin will present a thought-provoking paper arguing that substitution with aluminium may represent the most effective response to looming global copper shortages. He will highlight evidence suggesting that, of the copper consumed globally in 2023, approximately 70% could have been replaced by alternatives, including aluminium wiring, cabling, and tubing, without significant performance penalties. He will further argue that the principal barrier to substitution is not technical feasibility, but rather copper’s entrenched reputation for quality and the reluctance of manufacturers and consumers to adopt alternative materials, even in applications such as building wiring, air conditioning heat exchangers, and renewable energy cabling, where substitutes have been shown to perform effectively.

The conference will also feature two high-profile keynote lectures. Professor Chun-Xia Zhao of the University of Adelaide will explore whether peptides could enable a new mineral processing paradigm (see posting of 8th September 2025). Professor Jacques Eksteen of Curtin University will discuss circular hydrometallurgy approaches aimed at more sustainable processing of critical minerals (see posting of 9 November 2025).

Finally, we extend our congratulations to Professor Eksteen, who was awarded the 2026 Alan Taylor Award for Innovation in Metallurgical Processing at the annual ALTA Conference awards dinner earlier this month.

#CriticalMinerals26

Monday, 11 May 2026

Welcoming Gebr. Pfeiffer as a Sponsor of Comminution ’27

Gebr. Pfeiffer is a German engineering company specialising in the design and supply of industrial grinding and processing systems for heavy materials industries. Its expertise spans equipment and complete plant solutions for cement, coal, lime and gypsum, ceramics, and other minerals.

At the core of Gebr. Pfeiffer’s capabilities is advanced grinding technology, particularly high-efficiency milling solutions. Its flagship product line, the MVR vertical roller mill, is widely recognised across the globe for delivering high-capacity, energy-efficient grinding while handling a broad range of materials. Compared to traditional ball mills, these systems significantly reduce energy consumption, making them a preferred choice in certain processing operations.

Gebr. Pfeiffer first participated in an MEI Conference at Comminution ’25 as an exhibitor. Following a highly positive experience, we are delighted to welcome them not only back to the exhibition but also as a sponsor of Comminution ’27 in Cape Town.

Christian Altherr and Caroline Woywadt, of Gebr. Pfeiffer
with James Pownell, of FLS, Australia, at Comminution '25

Head of Global Marketing, Stephanie Husken, says: "For us, Comminution ’27 in Cape Town is much more than a date in the conference calendar. It is a place where our industry comes together to openly exchange ideas, challenge established approaches, and shape the future of comminution technology. That is exactly why we are actively supporting the event as a sponsor.

We value the symposium’s unique mix of researchers, universities, equipment manufacturers, engineering companies, consultants, and mining operators. This diversity fosters meaningful discussions that directly connect research with real-world applications.

The Comminution exhibition is known for its open atmosphere and high-quality dialogue, making it an ideal platform to discuss new technologies, learn from peers, and build long-term relationships. By sponsoring the event, we underline our commitment to innovation, collaboration, and continuous improvement in mineral processing and we look forward to engaging with the global comminution community in Cape Town".

We look forward to building a strong and lasting relationship with Gebr. Pfeiffer. A reminder that the call for abstracts for Comminution ’27 is now open, with submissions due by the end of October.

#Comminution27

Thursday, 7 May 2026

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.

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