Critical Minerals '24: a summary of the technical presentations

Critical Minerals '24, the 1st in what we hope will develop into an important series, was held at the Vineyard Hotel, Cape Town from November 14-15, 2024 and was attended by 64 delegates from 15 countries.

Following is a very brief summary of the presentations made over the two days.  This summary is intended to guide you to the extended abstracts associated with the presentations, most of which are available online as open-access. Unfortunately not all presenters responded to requests for drafts, but for those that did their names are linked directly to their papers in the online Proceedings.

The drafts 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 November 14th

Technical Session 1: Chairpersons: Mehdi Safari (Mintek, South Africa) and David Currie (British Geological Survey, UK)

The conference got underway with a keynote lecture from Markus Reuter, Chief Expert with the SMS Group, Germany. Markus said that there is a lot of talk about greening society, greening the supply chain, circular economy etc. The question that needs to be answered is how green is all of this and what shade of green (or grey) is achievable? He discussed the key role of metallurgy and minerals processing in applying its simulation methods and theory and how they can be applied to understand the greenness of systems and in fact what the limits are of the system.

In a follow-up to his plenary lecture at last month's IMPC, Richard Williams, Principal and Vice Chancellor at Heriot-Watt University, UK, reviewed the surveys of societal-technological policies of a range of mining corporations and offered key recommendations for areas of focus for pathways that might achieve a step-change to net-zero operations.

Markus Reuter and Richard Williams

The progressive integration of cutting-edge technologies into sensor-based mineral processing systems is a key objective for stakeholders in the mining sector. Markus Firsching, of the Fraunhofer Development Center X-ray Technology, Germany, looked at the application of X-ray transmission sorting as a pre-concentration method, exploring its potential to enhance processing efficiency and to reduce associated costs. The latest generation of X-ray sensor sorting technology was evaluated, assessing its capability to identify a diverse array of critical minerals,including metaliferous oxides and sulphides, rare earth phosphates, graphite, and others encapsulated within run-of-mine rocks. 

Markus Firsching (right)

Conference sponsor Steinert is one of the leading players in sensor-based sorting and Lutke von Ketelhodt, the Business Development Manager with Steinert, Germany discussed the sensor-based sorting of low-grade nickel ores. Nickel is one of the critical minerals that is necessary for the clean energy transition. The demand for nickel is primarily driven by stainless steel production and the growing demand for electric vehicles and energy storage. High- to medium grade nickel ore deposits are nearing depletion leaving low grade marginal deposits, so innovative technologies and approaches are essential to break away from traditional mining and mineral processing methods to sustain long term supplies.

Lutke von Ketelhodt (2nd left)

South Africa is renowned for vast mineral wealth, including platinum group elements (PGEs), chrome, gold, manganese, diamonds and coal. The mining industry faces challenges with efficient resource extraction and utilisation resulting in significant mine waste generation. The primary objective of a study described by Mohau Rampou, of Mintek, is to meticulously characterise the ore material and address the challenges associated with extraction of valuable metals/minerals, maximise resource utilisation, and aid meeting the demand for precious metals.

Historical mine tailings represent an environmental liability and simultaneously a significant reservoir of unrecovered critical and strategic minerals.  Nikita Malafeevskiy, PhD candidate at the Norwegian University of Science and Technology, presented a study investigating the reprocessing challenges posed by the sulfide-rich historical Joma mine tailings, of the Grong Ore District, in Norway. 

Nikita Malafeevskiy (2nd right)

Emmanuel Mends

Emmanuel Mends, a Graduate Research Assistant at the University of Nevada, Reno, USA, described an investigation into the selective extraction of metals from nickel sulfide tailings using salt roasting and acid leaching.

Reprocessing mine tailings to deliver critical metals for the energy transition is an economic rehabilitation strategy gaining traction, said Anita Parbhakar-Fox, Principal Research Fellow at the University of Queensland, Australia. A Tasmanian mine site, with a dam containing 38 Mt of pyritic tailings was studied in this context. The results have provided a strategic understanding of the site as a potential Co resource.

Anita Parbhakar-Fox with Markus Reuter

Mehdi Safari is Head of Flotation in the  Mineral Processing Division of Mintek, South Africa and he described an investigation of physical and chemical parameters on the flotation performance of copper, perhaps the most critical of metals.

Mehdi Safari (2nd left)

Copper has been highlighted as a critical mineral to mitigate climate change and provide clean energy, however major deficits are forecasted and therefore copper demand is expected to rise. This situation will become more severe if copper’s production continues at its current rate, and given the declining copper head grades as well as the long time span needed for exploration of new sites it has become necessary to improve existing processes. Natalie Shackleton, Metallurgy Consultant with conference sponsor AECI Mining Chemicals, focused on copper’s flotation performance using novel co-collectors developed for improved extraction of various copper-bearing minerals.

Natalie Shackleton (2nd right) with AECI colleagues at Groot Constantia Wine Estate

Zikhona Magaxeni, a Senior Lab Technician at Mintek also looked at copper flotation, describing work undertaken at Mintek to identify the most effective collector blend for achieving optimal flotation performance for PGM ores and copper ores.

Zikhona Magaxeni (4th left) with Mintek colleagues

Technical Session 2: Chairperson: Lucas Pereira (Helmholtz Institute Freiberg for Resource Technology, Germany)

Damien Krebs

Rare earths were the subject of the papers in the afternoon session, beginning with a keynote lecture from Damien Krebs, Principal Process Consultant with Primero, Australia. Damien provided an introduction to the extractive metallurgy of rare earths covering all major deposit types. The key rare earth bearing minerals were presented and discussed from a metallurgical amenability point of view and the major processing steps covered in a sequential process showing the equipment and chemistry involved. 

Ruhany Sheherazad Azeez, a researcher at the Tallinn University of Technology, Estonia, described the hydrochloric acid treatment of Estonian phosphate rock to recover rare earth elements.

Ruhany Sheherazad Azeez (right)

Walter Ngobeni is a Flotation Principal Engineer with Mintek, and he described the selective flotation of REEs from calcite and hematite from a Southern African repository.

Walter Ngobeni (2nd left)

Nathan Fox, a Senior Research Fellow at the University of Queensland described the exploration of rare earth element opportunities in Australia’s mine waste and unconventional sources.

Nathan Fox, with wife Anita Parbhakar-Fox

In the final presentation of the day, Lev Filippov, a Professor at the University of Lorraine, France, described an alternative extraction strategy for rare earth elements from the bauxite residue of the Friguia alumina plant in Guinea, through the development of a pretreatment strategy and leaching using soft acids.

Lev Filippov (left) at Groot Constantia Wine Estate

More on Day 1

Friday November 15th

Technical Session 3: Chairpersons: Andrew Menzies (Bruker Nano Analytics GmbH, Germany) and Richard Williams (Heriot-Watt University, UK)

Lithium is currently and forecast to be the material of choice for mobile batteries due to the high power density provided by fundamental atomic properties. The global transition from combustion engine vehicles to electric vehicles and hybrids will require vast expansion of global lithium production. This applies to both mine production as well as refining of mineral concentrates to produce battery pre-curser chemicals.

The major hard rock source of lithium is from the mineral spodumene which is found in pegmatite deposits. These pegmatite deposits are mined and processed to produce spodumene mineral concentrates which is typically between 5 and 6.5% lithia. Yesterday's keynote speaker, Damien Krebs, described methods for refining of spodumene concentrates.

In a double-act Camila Senna, Area Sales Manager Mining with Steinert Latinamericana, Brazil, and Poliana Ferreira, of Lithium Ionic Corp., Brazil, showed how integrating Dense Medium Separation and sensor-based sorting can produce cleaner spodumene concentrates, minimise environmental impact and operational costs, and improve resource management.

Poliana Ferreira and Camila Senna

Diego Arteaga, a researcher at the University Of Oulu, Finland, looked at flowsheet development for zero-waste processing of lithium hard rock ores, using DMS in particular.

Diego Arteaga (centre)

Lucas Pereira, Group Leader at the Helmholtz Institute Freiberg For Resource Technology, Germany, assessed the selectivity of lithium aluminate recovery in flotation against several gangue phases from a slag system under different reagent systems.

Lucas Pereira

Identification of new resources is both economically and strategically important, driving a boom in lithium exploration, said Andrew Menzies, of  Bruker Nano Analytics, Germany. He showed how rapid mineralogy mapping can support exploration, presenting mineral characterisation from a number of potential lithium resources in Portugal. Preliminary results suggest significant added value of the micro-XRF approach, where a much-improved mineral textural understanding aids exploration and ongoing evaluation of deposit potential.

Lev Filippov of University of Lorraine, France then discussed challenges in the recovery of lithium minerals from pegmatite and rare metals granite ores.

Graphite is important in transitioning to a green economy and while Southern Africa has substantial graphite resources, China remains the leader in terms of production and reserves. However, Southern Africa's high-grade deposits and ongoing exploration efforts indicate its growing importance in the global graphite supply chain, particularly as demand increases for graphite in batteries and other green technologies. Mintek plays a key role in the graphite sector and Mehdi Safari summarised Mintek's graphite R&D, with a particular focus on minerals processing.

Lawrence Bbosa, also from Mintek, highlighted the critical role of selecting an appropriate comminution process for improving flotation recovery and upgrading graphite ores. While size reduction is essential to enhance liberation and recoveries, caution is required to preserve larger flake sizes.

Lawrence Bbosa (left) and Mehdi Safari (2nd left)

David Currie, of the British Geological Survey (BGS), showed that Mozambique and Madagascar are currently the world’s second and third largest producers of natural graphite behind China. Around 50 natural graphite occurrences are known across eastern Africa including several in Eastern Province, Zambia. The BGS carried out fieldwork alongside Geological Survey Department for Zambia and Copperbelt University to sample these occurrences, then used optical and scanning electron microscopy, X-ray diffraction, and thermogravimetry-mass spectrometry to analyse the sample set. It was shown that the Paleoproterozoic paragneiss of the Eastern Province of Zambia has the potential to host a natural flake graphite deposit. 

David Currie (right) co-chairing session 1

In the final paper of the morning session Aishvarya Venkataseetharaman, Principal Scientist at CSIR-Institute Minerals and Materials Technology, India, discussed how energy metals such as Mn, Ni,Co, Cu, are often found in leaner ore grades which are locked within complex oxide matrices. To address this, non-conventional anoxic bioleaching using metal reducing bacteria has been developed, targeting metal recovery from ferruginous manganese oxide and lateritic ores, offering significant advantages over conventional aerobic bioleaching.

Aishvarya Venkataseetharaman (2nd left) at the conference dinner

Technical Session 4: Chairperson: Lawrence Bbosa (Mintek, South Africa)

Vanadium's unique properties and strategic importance in various industrial applications make it a critical element in modern technology. This metal is often extracted as a byproduct from the smelting of titanomagnetite ores. Mohamadbagher Fathi, a Research Fellow at the University of Tasmania, presented a study on the extraction of V2O5 from the slag produced during the smelting of titanomagnetite ores.

Mohamadbagher Fathi (3rd right) at Groot Constantia wine estate

The depletion of the high-grade Ni sulfide deposits has resulted in efforts focused on processing the alternative low-grade ultramafic ores. However, these contain considerable MgO, silica, and gangue rocks, challenging their processing. Smelting has been predominantly used for Ni extraction from sulfides as hydrometallurgical methods are associated with vast chemical usage/wastewater. However, high smelting temperatures (>1300℃), refractory corrosion, and significant emissions remain the main smelting drawbacks. Brian Makuza, a PhD candidate at the University of Toronto showed that thermal treatment (<1000℃) of the ultramafic concentrates blended with Fe additive is a promising approach for upgrading these concentrates. 

With Brian Makuza

Colwyn van der Linde, of TCM Research, Ireland, is currently an MEng student at the University of Pretoria. He described a dry chlorination flowsheet for the extraction of critical metals from primary nickel (copper, cobalt, PGMs and iron) sulphide concentrates.

Mixed Hydroxide Precipitate (MHP) is an important nickel and cobalt containing intermediate for producing battery-grade metals and salts. Currently extraction and refining of metals from MHP is via complex hydrometallurgical processes, which are sensitive to feed material composition and require elaborate waste stream treatment. Dmitri Terekhov, also of TCM Research, Ireland, showed that the Reduction/Carbonylation method, mostly used for sulphide intermediates refining, is ideal for MHP refining. 

Colwyn van der Linde and Dmitri Terekhov

Skarns today represent around 50% of the global tungsten reserves. Considering their fine textures and the trend of scheelite to form fine particles during the milling stage, the use of froth flotation is mandatory for their processing. However, tungsten skarns generally contain significant amounts of calcium minerals such as fluorite, apatite, and calcite, which reduce selectivity in the flotation stage. Yann Foucaud, Associate Professor at the University of Lorraine, France, presented work on the selective recovery of scheelite from an archetypal tungsten skarn using amine and fatty-acid flotation.

Yann Foucaud (2nd right) at the conference dinner

In the final presentation of the conference, James Strongman, Technical Director of conference sponsor Petrolab, UK, gave a review and case study of how mineralogical investigations and ore characterisation are vital for the development of critical mineral deposits. The energy transition is driving the development of both new types of deposits and previously challenging ores. These create new challenges for both mineralogists and metallurgists and James showed how new analytical techniques and workflows are being utilised to generate the information to answer complex questions around extraction, beneficiation and refinement. To demonstrate some of these techniques a case study of the mineralogical drivers behind the failure of a tin-tungsten mine was presented, along with how a deeper understanding of mineralogy is now taking the project forward. 

James Strongman (left)

More on Day 2

A final thanks to all concerned in making this a great conference, the sponsors, exhibitors, chairpersons, presenters and delegates, and last but not least the wonderful staff at the Vineyard Hotel.  We would greatly appreciate your comments on this posting.

A reminder also that the next conference in the series, Critical Minerals '26, will be held in November 2026. The venue is at yet undecided but will probably be in Spain.

Check out the reactions to the conference on LinkedIn at #CriticalMinerals24.