The continuing evolution of mineral processing

In the middle of the 19th century mineral processing as a professional discipline did not exist. Simple upgrading of ore by hand sorting and gravity concentration was handled by lowly paid mine workers, often women, and it wasn't until the early 20th century, with the introduction of froth flotation, that mineral processing became a recognised profession, with chairs in the subject springing up in universities around the world. 

There were some significant innovations at this time, such as the introduction of tumbling mills to replace stamp mills, but evolution in the first half of the century was slow, and by the 1970s little had changed in the design and operation of mills since the 1930s.

Typical mid 20th century ball mill classifier layout

Evolution was given a boost in the 1980s with the rapid development of computers, and the pioneering of mathematical modelling and automatic control, which led to the trend to increasingly larger flotation machines and grinding mills, and the widespread use of SAG mills.

The 21st century has seen a rapid increase in innovation, with the introduction of novel flotation machines, such as the Jameson Cell and the Hydrofloat, and grinding circuits incorporating high pressure grinding rolls and stirred mills. Enhanced gravity concentrators and high intensity magnetic separators have also played their part and there is now an increase in the use of sensor-based electronic sorters to pre-concentrate ores and reduce energy and water costs.

Now, as we enter the 4th industrial revolution, the 'green' revolution, mineral processing is recognised as one of the most important technologies in satisfying the increasing demand for all metals, particularly those that are critical in the manufacture of renewable energy sources, and for electric vehicles. There are tremendous challenges facing mineral processors, particularly in the need to recycle as much of these metals as possible from end of life resources, such as electronic waste, which will be a focus of July's Sustainable Minerals '22. At last month's Physical Separation '22 panel discussion, it was noted that processes such as gravity, flotation and magnetic separation will need to be integrated more in future as ores become more complex, and how mineral processing will evolve in the future will be the subject of the 2 hour panel discussion at IntegratedMinPro '22 which begins online in 2 weeks' time.

The panel will be chaired by Stuart Saich, of conference sponsor Promet 101. The conference's keynote speaker, Osvaldo Bascur, will be joined on the panel by Stephen Rayward, of MIDAS Tech International, Australia and Diego Mesa, representing Imperial College, UK, and Aminpro, Chile. The discussion will be live streamed and delegates will be invited to submit questions to the panel.

The conference will be held online over two days, June 13-14 and recordings of all the presentations and the panel discussion will be available on demand to registered delegates for a period of 6 months.

#IntegratedMinPro22

Process Mineralogy '22: Final Call for Abstracts

Join us in beautiful Catalonia, Spain, in November, for Process Mineralogy '22, MEI's first face-to-face conference since the start of the pandemic.

If you would like to present a paper at the conference, then please submit your abstracts by June 7th (more information on the posting of 28 March). All presenters will be invited to submit papers for peer-review after the conference, and accepted papers will be published immediately in the first available regular issue of Minerals Engineering, and included in the Virtual Special Issue of the conference on ScienceDirect.

The conference will be held at the Meliá Sitges Hotel, in Sitges, just 20 minutes by road from Barcelona airport and 30 minutes from the centre of Barcelona. The hotel has spectacular views of the Garraf Natural Park and the Mediterranean sea, and the Congress and Convention Centre has high speed WiFi internet in all its rooms.

As with all previous Process Mineralogy conferences there will be an associated exhibition, and if you would like to exhibit, or sponsor the conference, please contact jon@min-eng.com for details.

#ProcessMineralogy22

Recycling critical metals from e-waste

The programme for the final day of July's Sustainable Minerals '22 is devoted to critical minerals, those that  are essential to the green revolution, but whose future supply cannot be guaranteed due to scarcity and geopolitical factors. The day will end with a 2 hour panel discussion "Will the production of critical minerals be sufficient to satisfy the green revolution". The image below from the European Chemical Society, shows very clearly the elements in the Periodic Table which are most at risk.

Primary mining alone will not be enough to satisfy future supplies and major research efforts are being made around the world to develop methods of recycling these minerals from end of life commodities. The second day of the conference will focus solely on recycling and we welcome further input from workers involved with this crucial area of research.

Much of the research into secondary sources is focused on e-waste and the Royal Society of Chemistry (RSC) has recently said that the recycling of e-waste must urgently be ramped up because mining the Earth for precious metals to make new gadgets is unsustainable. One study estimated that in 2021 the world's mountain of discarded electronics weighed 57 million tonnes. All the while, the amount of e-waste generated is growing by about two million tonnes every year, and less than 20% is collected and recycled. 

Over 60% of the world’s population owns a mobile phone and smartphone adoption continues to rise in developing countries around the world, and as technology continues to improve so will the demand for the metals necessary for the next generation of smartphones, most smartphones carrying roughly 80% of the stable elements in the periodic table.

Breakdown of critical metals in a smartphone
Source: University of Birmingham

"Our tech consumption habits remain highly unsustainable and have left us at risk of exhausting the raw elements we need," said Prof Tom Welton, president of the RSC, adding that those habits were "continuing to exacerbate environmental damage".

So do try and join us online in July for Sustainable Minerals '22, and if you have something to say it is not too late to submit an abstract.

#SustainableMinerals22

Interesting news and people at the Cornish Mining Sundowner

There was a great turnout of around 25 at last night's sundowner at Falmouth's Chain Locker, with a number of new faces adding to the regular attendees.

Some of the sundowner 'regulars'

It was particularly good to welcome Mohammad Hadi Mohammadi from Afghanistan. As an academic he was vulnerable to the Taliban, and the Camborne School of Mines (CSM) and the CSM Trust arranged his appointment at CSM where he will work with CSM's Prof. Frances Wall on a 2-year research fellowship. The move was facilitated by the Council for At-Risk Academics (CARA), a charitable British organisation dedicated to assisting academics in immediate danger.

Mohammad with Frances Wall and the CSM Trust's Tony Batchelor and Nick Clarke

It was also good to meet representatives from London's Natural History Museum, who are in Cornwall for project meetings assessing the geology and processing of lithium deposits in the county.

The Natural History Museum visitors

I was pleased to offer my congratulations to a sundowner regular, and old friend, Mike Hallewell, who has been appointed as Consulting Metallurgist for Cornish Metals and so will be leading the process development effort for the impending studies for the regeneration of the old South Crofty tin mine.  Mike is the ideal person for this role as he worked in the tin industry from 1984 to 1998 and played a key role in the development of the Wheal Jane flowsheet for treatment of South Crofty Ore at the Wheal Jane Processing plant near Truro. Mike led the team that was responsible for the successful implementation of the Mozley MGS technology (posting of 4 June 2015) as a final stage of cleaning on tin flotation, a success that was copied by many tin mining operations globally at that time.

Mike Hallewell (2nd right) with fellow mineral processors BW,
Dave Goldburn (Holman-Wilfley) and Andy Wilkinson (Metso Outotec)

Andy Wells

Mike's mentors at South Crofty and Wheal Jane were Tony Elliott and Andy Wells respectively and he said that he always has and will remember them for their metallurgical standards. Mike took over as Mill Superintendent from Andy Wells in 1991 when Andy left to join the Neves-Corvo zinc-copper mine in Portugal and Mike went on to become the longest serving Mill Manager (7yrs) at Wheal Jane.

Mike also had some sad news, of the death earlier in the year of Andy Wells. Andy left Neves-Corvo in 1996 and returned to the UK to become principal metallurgist and later a director of IMC Mackay & Schnellmann. In 2004, he joined the London-based consulting partnership, Saint Barbara, where he continued his engagement in minerals projects as principal metallurgist, manager and then as owner. A full obituary is on the IOM3 website.

Missing from the usual attendees was Nick Wilshaw, as on the previous evening he attended a mineral processing sundowner 200 miles away in Cardiff, hosted by Maelgwyn Mineral Services, with staff from MMS, SRK Consulting, and Nick's Cornish company Grinding Solutions.

The Cardiff sundowner: Liam Macnamara (SRK), Dave Pattinson (SRK), Dan Abraham (GS),
James Gaydon (GS), Nick Wilshaw (GS), Mike Battersby (MMS), Steve Flatman (MMS)
John Willis (SRK) and Ryan Schultz (MMS)

Liam Macnamara has recently joined SRK after many years with FLSmidth, and Ryan Scultz is a recent addition to the MMS Cardiff Office, after spending some time at MMS in Johannesburg. Ryan’s responsibilities at MMS, from his 10 years of operational experience in South Africa on PGMs and chromite sands and the Democratic Republic of Congo on copper and cobalt, are to implement all the required systems around the Aachen technology, while building and maintaining client relationships, by ensuring the best performance of the MMS technology through regular consultations and servicing.

The next sundowner, at the Chain Locker, is on Thursday June 16th from 5.30pm. We will be very pleased to see you if you are in the area.

@barrywills

A brief update on Metcelerate

Metcelerate is a two year Professional Formation programme for mineral processing engineers. It is online and requires a few hours of learning each week and equips metallurgical professionals with the knowledge and practical skills they require to manage effectively metallurgical processes, assess risk and identify opportunities to enhance value. 

The Metcelerate program took in its first cohort of 45 learners in July 2000. Attendees came from around the globe; PNG, Australia, Ghana, Suriname, Chile, Peru, Mexico, Canada and the USA. This cohort is now completing the course, and the next cohort start in July of this year.

Metcelerate's Chief Financial Officer, Prof. Jan Cilliers, has sent me this brief update, and full details can be found on the website:

The Metcelerate program was developed with industry, based on a review of current training and critical gaps. This established the core topics and course content. 

The 20-month Metcelerate curriculum has seven taught modules (51 weeks in total) and a final Project, world-leading subject matter experts (Finch, Hadler, Seitz, Holtham, Napier-Munn and Wills, amongst others) having developed the training material as slides, videos, papers and exercises. E-learning specialists transformed this into on-line training material.

Successful course completions earn digital badges for sharing on social media, and printable certificates. Badges are certified through the London City and Guilds Institute. 

The Metcelerate programme is offered through companies that sponsor their learners. It requires commitment not only from learners, but also from site mentors; assignments and project must be agreed, monitored and evaluated. Buy-in across the company structure is essential, and has been a major factor in the success to date. 

Prof Cilliers says that both learner and company feedback has been very positive.

The contribution of mineralogy to sustainability in the mine life cycle

It is well known that mining is an essential enabler to sustainable development. Understanding and appreciating the mineralogy of the ores and waste material we produce is a key component of this. In November's Process Mineralogy '22 in Sitges, Prof. Megan Becker, of the University of Cape Town will present a keynote lecture considering the contribution of mineralogy to sustainability through the mine life cycle, looking through the lens of the domains of process mineralogy, environmental mineralogy and medical mineralogy and their relationship to the pillars of sustainability - profit, planet and people, respectively. Using several case studies, Megan will show how the application of mineralogy and the tools used for characterisation have evolved over the decades from some of the early pioneering mineralogists to some of the most recent work where mineralogy is fully integrated into all aspects of ore and waste use and valorisation. 

Prof. Becker's research and teaching at UCT focuses on the application of mineralogical knowledge for the understanding, optimisation and prediction of key unit processes within the mining industry from techno-economic and environmental aspects. She has successfully integrated process mineralogy into the activities of the Centre for Minerals Research and other research groupings within the Chemical Engineering Department at UCT. She has close to 90 peer reviewed publications, and in 2018 she was nominated as one of the top 100 Global Inspirational Women in Mining. 

Megan is consultant to MEI's Process Mineralogy conferences and is a co-author of the JKMRC monograph Process Mineralogy, which was showcased at Process Mineralogy '17 in Cape Town.

Megan (centre) with co-authors Elaine Wightman and Cathy Evans

We look forward very much to meeting Megan again in Sitges, which is just outside Barcelona in Spain. It will be our first face to face process mineralogy conference since Process Mineralogy '18 in Cape Town. It will be great to see people in person again, and now is a timely reminder that the deadline for abstract submission is the end of this month. More details can be found on the posting of 28th March. Once again I thank our current sponsors, Bruker, Zeiss and Promet101, and our media partner, International Mining, for their support.

#ProcessMineralogy22 

Physical Separation '22 Day 3: Classification, and panel discussion on the future of physical separation

Wednesday 11th May

The theme of the final day's technical session was Classification and Solid-Liquid Separation, with eight presentations, from Australia, Canada, Chile, India and Peru.

Perhaps the most ubiquitous separation machine in the minerals industry is the hydrocyclone, and five of the presentations involved the use and design of these important devices.

Shashank Shekhar Pathak, of Weir EnSci, Weir Mineral India, presented a theoretical approach to develop a predictive model of the air core in hydrocyclones and Shuvam Mohanty, of the University of New South Wales, Australia, described the parametric analysis of axial flow hydrocyclones with suitably designed numerical experiments at various operating conditions. The effect of inlet dimensions, vortex finder length, and vortex finder diameter on the performance and flow pattern were computationally investigated using large eddy simulation for twelve hydrocyclone separators altogether. The results shows that the maximum tangential velocity and axial velocity profiles in the hydrocyclone decreases with increasing inlet dimensions, vortex finder length and diameter. 

The handling of tailings is of great importance in mining. Efficient tailing management is necessary for safe disposal as well as reutilisation of tailings to provide a sustainable solution to the modern mining industry. The Double Effect (DE) hydrocyclone is a double efficiency classification unit, working as a single stage without the need for additional pumping. The double classification helps dramatically reduce the amount of fine material entrained by coarse material, that might occur with a single stage and, at the same time, helps improve water recovery in the process. Chandranath Banerjee, of Weir EnSci, Weir Mineral India, presented a parametric study to analyse the physical response of design and operating variables of a DE hydrocyclone on the classification behaviour of mine tailings.

The KREBS CycloWash is an FLSmidth patented, ancillary elutriation (cleaning) device that markedly improves the desliming performance of standard cyclones, as it also reduces operating costs. The CycloWash, located in the lower/apex section of the hydrocyclone, injects water into the cyclone, and the injection water displaces the fines-laden water in the partially thickened underflow pulp. The result, essentially, is a second stage of classification taking place, where the displaced water with fines joins the normal cyclone overflow. The coarse solids are thickened, and they discharge through the apex orifice as a thoroughly deslimed underflow. 

Pablo Hinojosa, of UNSA, Peru, said that there must be a contingency plan for the classification of tailings via hydrocyclones in situations of high fines in the tailings entrance feed, so that actions including shutting down cyclones are avoided. If cyclones are closed, the pressure will increase and therefore more sand will be lost in the overflow (especially in conditions of tailings with good quality of input material, that is, a feed with coarse quality). He proposed reducing the content of fines in the underflow by reducing the diameter of the truncated cone of the CycloWash (a size that is close to the diameter of the apex), with the aim of improving the quality of underflow. In this way, a better quality underflow will be obtained when there is a high content of fines in the feed.

The design and operation of hydrocyclone cluster distributors is reported to have a significant impact on grinding circuit classification and therefore the overall minerals processing circuit performance.  Nirmal Weerasekara, of Weir Minerals, Australia, introduced a novel approach of assessing the performance of hydrocyclone distributors by employing a coupling between Computational Fluid Dynamics assessment and JKSimMet cyclone assessment, including classification and roping detection, novel hydrocyclone distributor designs then being compared against traditional designs using this approach.

According to Joshua Starrett, of the University of Newcastle, Australia, high-performance particle size classification is emerging as an enabler for achieving step change improvement in mineral beneficiation. He said that conventional mechanical screens provide sharp separations but are limited by decreasing performance at lower cut sizes and impacts of wear. Similarly, traditional devices such as hydrocyclones can offer good separations but are significantly impacted by water entrainment of fine particles. Joshua presented a study utilising a REFLUX™ Classifier, with water as a fluidising medium, to classify feed suspensions based on particle size. The partition curves were remarkably sharp, exhibiting virtually no ultrafine entrainment with the coarse underflow, and virtually no oversize particles in the overflow. 

The slurry flow properties in the compression zone of a thickener are challenging to predict, mainly due to the high concentration of solids causing non-Newtonian flow behavior. More accurate prediction of slurry sliding velocity at the thickener floor would enable the development of better thickener models, control strategies, and unit designs. An inclined open flume is often used to investigate such flows, where the slurry with known properties is fed and monitored as gravity-driven. Guilherme Anrain, of University of British Columbia, Canada, presented work using open-channel flow data available from the literature and data from their experiments to train machine-learning models — parameters including flow rate, flume slope, slurry depth, and slurry rheological properties.

In the final presentation in the session Christian Ihle, of the University of Chile, highlighted how water shortage and low ore grades present in many mineral processing plants lead to high water recirculation, which can lead to low water quality without proper treatment. Inclined plate clarifiers are a low footprint solution to remove turbidity from such streams. The presentation focused on the study of the effect of heating of the downward facing wall of such inclined elements, both on particles settling and re-suspension. 

After a short break, Erin Bobicki, of the University of Alberta, Canada, chaired a two hour panel discussion on 'Looking to the Future: Physical Separation in 2030'. The panelists were Peter Amelunxen, formerly with Hudbay Minerals, Canada, now Vice-President of Technical Services at Capstone Copper, Canada, Priscila Esteves, of Steinert, Brazil, Kevin Galvin, of University of Newcastle, Australia, and Neil Rowson of the University of Birmingham, UK.

There was wide range of discussion, including how different processes, such as gravity, flotation and magnetic separation will need to be integrated more in future as ores become more complex. It was a superb discussion, led by an excellent chairperson in Erin Bobicki, with highly experienced panelists with diverse specialties. It should be essential viewing for anyone in our industry.

Following the discussion, Jon Wills thanked the panelists and all those who have presented work over the last 3 days. He hoped that by the time of the next Physical Separation conference, in two years time, we would be meeting face to face again in Falmouth.

The recordings of the panel discussion and all the presentations at the conference are available on demand for the next 6 months, so it is not too late to register to access these.

All presenters have been invited to submit papers on their work for peer-review in a virtual special issue of Minerals Engineering.

Once again, we thank our sponsors for their support throughout these difficult times.

#PhysicalSeparation22

Physical Separation '22 Day 2: Magnetic Separation and Sorting

Tuesday 10th May

Magnetic Separation was the theme of the first session this morning, with three presentations, starting with a keynote lecture from Neil Rowson, Emeritus Professor of Minerals Engineering at the University of Birmingham, and Laboratory Manager at Bunting-Redditch. Neil gave an overview of the role of magnetic separation in the development of critical and strategic metal recovery flowsheets (see posting of 25 October 2021).

Neil Rowson (left) at Physical Separation '19

Following the keynote, George Abaka-Wood, of the University of South Australia, presented a study where mineralogical and strategic beneficiation tests were undertaken on complex low grade saprolite ore to assess the feasibility of recovering valuable rare earth elements minerals as by-products of gold leaching by magnetic separation.

Panagiotis Angelopoulos of the National Technical University of Athens, Greece, then discussed the two-stage processing of bauxite residue towards the recovery of residual Al and the production of Fe- and REE-rich concentrates through magnetic separation.

Electronic sorting was the theme of the afternoon session. It is ironic that sorting, once a major method of concentrating ores by hand, became effectively redundant, but is now enjoying a very strong resurgence thanks to high speed computers which allow pre-concentration of ores at very high rates, reducing comminution energy and water costs.

Typical sensor-based sorter

Conference sponsor Steinert is a major player in this field and there were two presentations from Steinert Latinoamericana, Brazil this afternoon. Priscila Esteves, who will be a representative on the panel discussion tomorrow, discussed the applicability of sensor-based sorting technology for improving the quality of Brazilian iron ore lump. The iron ore industry faces the transition to low grade deposits with increasing pressure for a more sustainable approach. There is increasing importance for concentration methods that can improve quality of lump material and sensor-based sorting technology is an option for increasing lump quality by applying a low cost and dry beneficiation technique. 

Edwardes Dias, head of Customer Support for Steinert Latin America, explained how sensor based sorting technology has been used to separate chromite lump from low grade rocks for the past seven years in the northeast of Brazil, replacing a hand-picking operation. He discussed how data analysis on chromite rock scans has been used to assist the improvement of a sensor- based sorting algorithm.

TOMRA is also a major manufacturer of electronic sorting machines, and TOMRA sensor-based particle ore sorting has been in operation since 2015 at the San Rafael tin mine in Peru for pre-concentration of hard rock cassiterite ore. Aysa Moslemiyekan, of SIX-S GmbH Consulting, Germany, described  a new methodology and results from a simulation developed to further optimize the particle ore sorting plant.

Modern electronic sorters employ sensors to distinguish differences in various properties of rocks, and Beichen Duan, of the University of Toronto, Canada, presented an interesting study to investigate if microwave imaging (MWI) can be used to distinguish rocks that contain valuable minerals or metals from those that do not, for potential application as a new sensing method.  Compared to more established sensors MWI has the potential to penetrate deeper into ore particles and to analyse those ores with high contrast in electromagnetic properties between valuable minerals/metals and gangue minerals. 

In another presentation from Canada, Patrick Mercier, of COREM, explained that ore sorter manufacturers typically provide technology evaluation by carrying out production tests using 50 to 5,000 kg of feed material. Whereas the resulting cumulative mass pull-recovery curves obtained for such pilot-scale tests provide a quantitative estimate of the expected ore sorting performance, their potential uncertainty, due to, for example, feed composition variability, is not assessed. Patrick presented a methodology to cross-validate pilot-scale results against bench-scale amenability testing on a sub-sample of rocks hand-picked from the ore feed, demonstrating how to forecast the variability of sorting performance at scale fora given ore type over a range of feed compositions expected during sorter operations.

Today has been another interesting day of presentations, all of which are available on demand for the next 6 months.

#PhysicalSeparation22

Physical Separation '22 Day 1: Gravity Concentration, and Plant Practice

Monday 9th May

Physical Separation '22 is the 7th in the MEI series, and the first to be totally online. We have a fine programme over the next three days, covering gravity and magnetic separation, sorting and microwaves, classification and solid-liquid separation.

Amanda and Jon Wills opened the conference this morning, welcoming our 50 delegates from 13 countries, and thanking our sponsors, Hudbay Minerals, Gravity Mining and Steinert, our Media Partners International Mining and Imformed, and Industry Advocates the Coalition for Eco-Efficient Comminution (CEEC), the Cornwall Mining Alliance and the Critical Minerals Association.

Amanda explained that we had to commit to an online event some time ago due to the pandemic, but previous physical separation conferences have been held in Falmouth, where we hope to be back in 2 years time. Cornwall is the most appropriate venue for these events, as the county is regarded as being the birthplace of modern mining, and in its 19th century heyday the tin and copper miners upgraded their ore by physical methods, gravity concentration and hand sorting, the only methods available at that time. These methods began to fail as the ores mined became leaner and more finely grained, and froth flotation came to the rescue in the early 20th century.

Gravity concentration has, however, over the past few decades enjoyed a strong revival, with the development of enhanced gravity machines allowing the treatment of finer grained ores. There is also a strong awareness that gravity concentration is more environmentally friendly than flotation, and is cheaper and simpler. Improvements have also been enhanced by more efficient classification methods and we were fortunate to have Kevin Galvin, Laureate Professor at the University of Newcastle, Australia, the inventor of the Reflux Classfier, open the first technical session, Gravity Concentration, with a keynote lecture "New challenges for gravity concentration and classification of fine particles" (see posting of 7th February 2022).

Kevin Galvin (right) at Physical Separation '19, with Stuart Saich of Promet101

Following Kevin's keynote were six presentations from Australia, Canada, France, South Africa and Turkey.

Mineral processing flowsheets that include gravity concentration typically utilise significant quantities of energy and water for materials transport and optimum metallurgical performance. These flowsheets are prime candidates to benefit from innovative approaches to lower water consumption. Edward Hart, of Mineral Technologies, Australia, described a proprietary surge bin design that has recently demonstrated suitability in upgrading minerals by rejection of fine/low specific-gravity particles and in addition allowing pumping of high pulp density slurries that were previously not considered practical.

Water-pulsated jigging is one of the earliest methods of gravity concentration but, as explained by Mahmut Camalan, of the Turkish Energy Nuclear and Mineral Research Agency, the process is adversely affected if drag forces cause particles to fall at constant or terminal velocities and he proposed two methods, sample preheating and polymer addition to the jig water, to reduce drag forces, sample preheating enhancing separation at low to moderate pulsation, and polymer addition at moderate to fast pulsation.

Falcon SB concentrator

Over the years innovations in gravity concentration have allowed the treatment of much smaller particles than in the past and enhanced gravity devices have become standard equipment in most gold recovery processes because they are a simple, inexpensive, and effective way of recovering free gold. The Falcon Concentrator is one such device and Sepro Systems of South Africa has developed a new centrifuge bowl that significantly improves gold recovery from grinding circuits. Wynand Erasmus described the evolution of the Falcon gravity concentrator from inception to present day and presented a case study illustrating the gold recovery improvements of the new Sepro Frontier™ bowl at the pilot and industrial plant scale.

Gillian Omaga, of Université de Lorraine, France, described the use of a Falcon Concentrator to recover critical metals as by-products of lithium processing from a rare-metal granite. The application of a Selfrag high-voltage electric pre-treatment stage before grinding increased the performance of the separation. 

Numerical and experimental invesigations on a Falcon Concentrator were performed at the University of British Columbia, Canada, using a fully coupled numerical model for slurry flow, which  was developed to be generalisable for dense slurry flows. Utkan Caliskan compared the numerical results to the experimental results obtained on a lab-scale Falcon L40 unit.

Franco van der Venter, of Gravitas Minerals, South Africa, described the Optima Classifier™, a multi-commodity hindered settler, which separates fine minerals based on density. The beneficiation of fine coal, chrome and iron ore was evaluated in this study. It was found that the Optima Classifier™ was able to produce market specific products in a single stage for all commodities evaluated. It was also found that using the Optima Classifier™ to beneficiate fine minerals is not only economically feasible, but also reduces the environmental impact of fine mineral disposal.

Optima Classifier

Following the mid day break were three presentations on Plant Practice.

Much of the remaining iron ore resources in Brazil consist of low-grade itabirite, which are currently processed in complex circuit flowsheets. Accordingly, a typical industrial itabirite circuit would include a four-staged crushing/screening plant, followed by grinding in a closed-circuit ball mill, desliming in hydrocyclones and final ore mineral concentration in reverse flotation circuits. In recent years Vale implemented various initiatives for investigating alternative processes towards simplified flowsheets. Accordingly, the proposed disruptive flowsheet consists of a primary crushing stage, SAG milling, primary concentration using Vertically Pulsating High-gradient Magnetic Separation, and a final concentration stage using the Reflux Classifier. The inventor of the Reflux Classifier, this morning's keynote speaker, Kevin Galvin, described such a circuit, which would eliminate several unit operations, by excluding secondary to quaternary crushing, desliming stages, complex flotation circuits, thickening and the flotation reagent plant. 

Artisanal gold mining is based on empirical methods which reduce the efficiency of concentration processes and increase their environmental impact. Flor Granda-Arce, of Universidad de Ingenieria y Tecnologia, Peru, described the use of a water-only cyclone (WOC) for the concentration of valuable heavy minerals from placer deposits in Madre de Dios, one of the richest (and most affected) areas in the Amazon basin. The presentation highlighted the potential of using WOCs as an environmental alternative for the processing of placer deposits in this region and the specific behaviors for different minerals, especially those carrying rare earths (Ce, La) and transition metals (Zr, Ti).

The concentration and transportation of ore, concentrates, or tailings are two common challenges mining companies today. Mining companies are seeing lower available valuable metals or minerals with an increased gangue-minerals concentration which makes handling of slurries more difficult. Difficulties in handling of slurries can lead to a reduction of a mill's working life due to the filling of tailings ponds, or there can be difficulty in filtration of tailings or concentrates or pumping ore that has been slurried over long distances in pipelines. While synthetic polymers are necessary to achieve faster liquid-solid separation rates, polymers can impart negative rheological characteristics to slurries. In the final presentation of the day Lawrence Andermann, of Suez Water Technologies & Solutions, USA, discussed methodologies for measurements of rheological properties of various kinds of slurries; such as viscosity, slump tests, Marsh Funnel, and Vane Rheometry.

All of the conference presentations are available on demand, so it is not too late to register.

#PhysicalSeparation22

Integration, Optimisation & Design of Mineral Processing Circuits (IntegratedMinPro '22) programme now available

As the demand for resources continues to increase, and amidst growing challenges of processing complex ores while minimising energy and environmental impact, we are entering an exciting time for innovation in mineral processing. Innovation in individual unit operations is complemented by innovative approaches to the entire mineral processing flowsheet, from rearrangement of an existing circuit to a new approach for a greenfield development.

IntegratedMinPro '22 is a new conference from MEI, and is sponsored by Promet101 and Hudbay Minerals, with Media Partner International Mining, and Industry Advocates the Coalition for Eco-Efficient Comminution (CEEC), Cornwall Mining Alliance and the Critical Minerals Association.

Over two days, June 13-14, this online event will feature papers from around the world, on new approaches to mineral processing circuits, whether through design, modelling, optimisation or operation. This includes integration of unit operations (e.g. comminution and flotation), novel flowsheets that incorporate new equipment and new approaches to optimising circuit design. 

Included in the programme are two keynote presentations from well known figures in the industry. Elizabeth Lewis-Gray of Gekko Systems Integrated Mineral Processing, Australia, will discuss the critical need for accelerating innovation in the mining sector and Dr. Osvaldo Bascur, of OSB Digital LLC & SEEQ, USA, will discuss net metal production optimisation in the digital age.

On the final day there will be a 2-hour live panel discussion on the continuing evolution of mineral processing, chaired by Stuart Saich, of conference sponsor Promet 101.

The programme is now available for viewing and all presentations will be available on demand for 6 months after the event. Registration is open, and we look forward to your contribution to this important online conference.

#IntegratedMinPro22

April summary

The war in Ukraine dominated the news again last month, with ever worsening reports of atrocities. Boris Johnson visited the capital, Kyiv in the middle of the month, to pledge support, and a few days later was issued a fixed penalty notice, along with Chancellor Rishi Sunak and others, from the Metropolitan Police, for his part in the Downing Street lockdown parties. He thus became the first standing UK Prime Minister to be sanctioned for breaking the law, and despite having lied to Parliament about his partying he still refused to resign, one leading conservative saying that the fine ought to close this matter, as there is a war on and the Prime Minister, supported by the Chancellor, provides the leadership the nation needs. Many would argue about this, as the UK is not at war, and it must be noted that the UK changed its leadership during the first and second world wars, and during the Boer War, the Korean War, the Iraq War, and four times during the war in Afghanistan!

The Times, 29th April

The UK Government unveiled its future energy strategy at the beginning of the month, whereby up to 95% of the UK's electricity could come from low-carbon sources by 2030. The strategy, which aims to increase UK energy independence, includes plans to boost nuclear, wind and hydrogen power. There was no mention of geothermal energy in the mix, despite progress in Cornwall on the United Downs Deep Geothermal Power Project, the first geothermal power plant in the UK. The aim of the project is to produce power and heat from the hot granite rocks beneath Cornwall and two deep, directional wells have successfully been drilled; the production well to a depth of 5275m and the injection well to 2393m. Both wells have intersected the target Porthtowan Fault Zone located approximately 800m to the west of the site.

Nor was there a mention of the potential use of nuclear fusion, which Johnson enthused about at the Conservative Party Conference in October 2019, clarifying his position on this by saying "They (UK scientists) are on the verge of creating commercially viable miniature fusion reactors for sale around the world. "I know they have been on the verge for some time,” he continued, “It is a pretty spacious kind of verge.” But now, he assured his audience, “we are on the verge of the verge."

There is a big focus on offshore wind in the strategy, with a new target of producing up to 50 gigawatts (GW) of energy from this source by 2030 and Boris Johnson has called for a “colossal” floating wind farm in the Irish Sea. Just over 2 years ago he promised that Britain would become the "Saudi Arabia of wind".

A large wind turbine requires around 5 tonnes of copper, and at the recent 2022 CRU World Copper Conference held in Santiago, Chile, attendees heard the latest assessments on supply, demand, prices in the refined copper, concentrates and recycling markets. Erik Heimlich, head of base metals supply at CRU said that the world needs eight projects the size Escondida in Chile, the world’s largest copper mine, in the next eight years, the global copper industry needing to spend more than $100 billion to build mines able to close what could be an annual supply deficit of 4.7 million tonnes by 2030. The analyst said the supply gap for the next decade is estimated at six million tonnes per year, as the clean energy and electric vehicles sectors ramp up.

The big news from MEI last month was that Jon and his family are to shortly leave Cornwall for a new life in Luxembourg. Jon's partner, Dr Kathryn Hadler, formerly with Imperial College, London, and a regular at MEI's flotation and other conferences, has been appointed Director of the European Space Resources Innovation Centre at the Luxembourg Institute of Science and Technology as of 1 April 2022. Kathryn is currently commuting back to Cornwall at weekends, before Jon and the two children join her in Luxembourg in July.

Kathryn at Physical Separation '19 with Kristian Waters
Both former editors of IJMP, Kristian is now an editor with Minerals Engineering

And not a mention of Coronavirus this month, for the first time in 2 years. Has the pandemic gone away? It's easy to be fooled into thinking so, as life in UK now goes on as normal. But things have a habit of biting back so maybe we shouldn't be too complacent. I suppose at the moment there are more worrying things globally, such as Putin's escalation of the war in Ukraine and the possibility of it spilling onto a wider stage.

@barrywills