European Symposium on Comminution and Classification (ESCC '19)

The European Symposium on Comminution and Classification (ESCC) started over 55 years ago, held mainly in Germany with the past two Symposia held in Sweden and Turkey, and on September 2-4 for the very first time in UK, at the University of Leeds.

The iconic University of Leeds Parkinson Building

Sponsorship support was provided by DEM Solutions, ESSS, Freeman Technology, Hosokawa Micron, IFPRI, MEI, Quadro, Retsch, Surface Measurement Systems, WAB and Ytron.

Around 80 extended abstracts were received, which were scheduled for two parallel oral presentation sessions and two evening poster sessions along with exhibitions by the symposium sponsors. There were three plenary and six keynote lectures from leaders in the field, outlining the recent progress relevant to chemical and allied, food, mineral and pharmaceutical industries. The programme included the following themes: fundamentals of size reduction, innovations in milling and classification, nanomilling, mechano-chemistry and solid state transformations, pharmaceuticals and foods, attrition and wear, and related modelling. The notable number of abstracts received on modelling made it possible to divide them into sub-themes: mechanistic, population balance, discrete element and coupling with computational fluid dynamics.

The extended abstracts are available for download as a pdf file, and it is planned to make them searchable and available for future reference via the University of Leeds website.  The Elsevier journal Powder Technology will publish a selection of the contributions in extended full manuscript.

Monday September 2nd

After a brief opening by the conference chairman, Prof. Mojtaba Ghadiri, of the University of Leeds, who welcomed the 103 delegates, 36% from UK and 26% from Germany, the first plenary lecture was given by Arno Kwade, of Technische Universität Braunschweig, Germany.

Mojtaba Ghadiri and Arno Kwade

The most used energy storage system today is the lithium-ion battery, and Prof. Kwade discussed how mills are used for particle breakage and particle dispersing within the long process chain from the raw material to the final lithium-ion battery cell and its recycling at end of life.

Following the keynote the morning split into parallel sessions on Fundamentals, and Mechanistic Modelling of Size Reduction.

There were two keynotes in the afternoon session.

Lian Liu

Lian Liu of the University of Surrey, UK, showed how predictive modelling of comminution processes is essential for improving the process design, process optimisation, quality control and reducing operational cost. In her talk, two examples of dynamic mill models based on the population balance model were presented. The first one is for tumbling mills such as ball and SAG/AG mills used in the mining industry. The mill models for tumbling mills were developed in a generic dynamic model structure which incorporates ore breakage characteristics, transport, classification along the mill, a discharge function, and energy consumption.

Surface properties are critical for pharmaceutical manufacturing with an increasing trend towards the use of fine particles in pharmaceutical development where the surface will be increasingly important. Milling is often a unit operation of choice for size reduction in pharmaceutical processing although a range of surface changes can occur in crystalline solids subsequently affecting further processing, handling and performance. Jerry Heng, of Imperial College, UK showed that crystalline materials are anisotropic and milling results in the generation of new surfaces exposing different crystal facets varying in facet specific surface energy.

The International Fine Particle Research Institute hosted a reception in the evening to coincide with the display of the thirteen posters submitted.

 

Tuesday September 3rd

The day began with a plenary lecture by Michael Juhnke, of Novartis Pharma AG, who discussed the production of engineered drug particles by size reduction techniques, providing case studies for commercialized products where size reduction techniques could provide an essential element to enable key drug product features.

In a mid-morning keynote Wolfgang Peukert, of Institute of Particle Technology, Friedrich-Alexander University Erlangen-Nürnberg, Germany showed how milling at the nanoscale is a fascinating field involving aspects of nanomechanics, internal defect formation and defect stability, colloid and formulation science as well as mechanochemistry. Inorganic and organic nanoparticles including drug particles, novel 2D materials such as graphene or boron nitride and even nanoemulsions can be produced this way.

Wolfgang was a keynote speaker at Comminution '14, and is shown below (right) with fellow Comminution '14 keynote speakers Tim Napier-Munn and Alan Muir.

Luís Marcelo Tavares, of Universidade Federal do Rio de Janeiro, Brazil, is a familiar face at MEI's comminution conferences, and will be a keynote speaker at Sustainable Minerals '20 next year. In the first of the afternoon's keynotes Marcelo discussed how the discrete element method (DEM) is a powerful tool to describe the behaviour of particulate flows. However, in some cases, breakage is not taken into account, leading to biased results. This becomes critical for simulations where particle flow and particle size reduction cannot be properly decoupled. The Tavares breakage model, implemented in the commercial platform Rocky DEM, takes in consideration important rock behaviour based on the energy dissipated in a contact to determine if a particle will break or not, specifying the progeny size distribution generated on a breakage event.

The final keynote lecture of the day was given by Steffen Sander, of Hosokawa Alpine Aktiengesellschaft, Germany, who showed how air classification utilising deflector wheel classifiers has been state of the art in powder processing for many decades. The micro processes taking place inside these machines are still not fully revealed and remain subject to further investigations and he gave some examples of technical solutions to meet the requirements.

The day ended with a fine conference dinner at University House, with an entertaining after dinner talk from Jonathan Seville, Professor of Formulation Engineering at the University of Birmingham. Jonathan was for many years editor-in-chief of Elsevier's Powder Technology.

Conference chairman Mojtaba Ghadiri, with (clockwise) Wolfgang Peukert, Jonathan Seville, Arno Kwade,
Iain and Nicky Crosley, Willie Hendrickson and Lian Liu

Klaas Van der Wielen, Rudolf Landsmann and Marko Hilden

Paul Cleary with Barbara and Barry Wills

 

Marcelo Tavares, Mojtaba Ghadiri, Aubrey Mainza and Malcolm Powell

 Wednesday September 4th

The final day began with a plenary lecture from Malcolm Powell, of the University of Queensland's JKMRC, and a regular contributor to MEI's comminution conferences, who said that it is high time to dramatically upgrade historic empirical comminution models, that are based on back-fitted breakage rates, to mechanistic models. He presented an approach to embracing the available computational power and the progress in understanding of comminution systems to rewrite models to be predictive and reliable with respect to the range of conditions to be encountered in the current and future devices we use in industry. Underpinning such an approach is the need for appropriate measurement of breakage properties, that include mineral association, that respond to the range of conditions encountered in comminution equipment for mineral processing.

Malcolm is the founder of the Global Comminution Collaborative (GCC), a collaboration between the JKMRC in Australia, Sweden's Chalmers University, the University of Cape Town, Germany's Technische Universitat Braunschweig, the University of Rio de Janeiro, and Turkey's Haceteppe University, all, apart from Turkey, being represented in Leeds this week. 

GCC members Malcolm Powell (Australia), Arno Kwade (Germany), Magnus Evertsson (Sweden),
Aubrey Mainza (South Africa), Marcelo Tavares (Brazil) and Hakan Benzer (Turkey) at Comminution '14

GCC stalwart Aubrey Mainza, of the University of Cape Town, has been a long-time consultant to MEI's comminution series and in the final keynote lecture he showed how integrating classification into circuits during design and equipment selection is an important aspect in developing robust comminution circuits.

ESCC '19 has been a very well organised conference, so congratulations to Prof. Ghadiri and his team. The final act of the day was the presentation of prizes, sponsored by DEM Solutions, to the best student presentations. Well done Lori Gonnet of IMT Mines Albi, France, and Paul Fabio Prziwara of Technische Universitat Braunschweig, Germany.

ESCC '21 will be held in Toulouse, France, the exact dates yet to be finalised.

@barrywills