Holger Lieberwirth: No More Potential for Breakthrough Developments in Comminution?

Abstract:  The number of breakthrough developments in comminution has been limited in recent decades. A recent research experimentally comparing the minimum comminution energy experimentally determined in single-particle-single-layer breakage with the specific energy consumption of the industrial circuits comminuting the same three ores reveal substantial potential for energy savings in comminution. Considering constraints by physics and technical and economical limitations the request is derived to develop new solutions in comminution to meet the growing demand for mineral resources in the future.

Short CV: Prof. Dr.-Ing. Holger Lieberwirth is currently director of the Institute of Mineral Processing Machines and Recycling Systems Technology (IART) at the TU Bergakademie Freiberg. His short professional biography includes CEO Asia, TAKRAF, Leipzig, Germany (2010 – 2013), Vice President, TAKRAF, Leipzig, Germany (2006 – 2010), Managing Director Sales, Beumer Maschinenfabrik, Beckum (2002 – 2006) Managing Director Sales and Technology, Maschinenfabrik Effing, Ahaus (2000 – 2002) Chief Engineer, Business Unit Essen, Krupp Fördertechnik (1997 – 2000) Chief Representative, China, Krupp Fördertechnik, Beijing (1996 – 1997) Project Manager Sales, Krupp Fördertechnik, Essen (1991 – 1995). Some selected projects since 2013 are selective comminution of ores, spars, slags, …; design/ application of crushers, HPGR, VRM; smart screening machines + air classifyers; briquetting, pelletizing, agglomerating machines and recirculation of secondary raw materials.

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Magnus Evertsson: Optimisation of compressive crushing

ABSTRACT: Compressive crushing is applied in crushing plants used in mineral, mining, and aggregate industry for fragmentation of rock materials. From a global perspective, the total volume of crushed rock is massive and corresponds to several billion tons. All societies have to fulfil a daily need of rock material products and its derivatives such as metals and minerals. The market for metals and minerals is global while the aggregates production is mainly a local industry. This lecture presents a broader overview of optimisation with respect to "product yield, use of natural resources and energy consumption". High level plant optimisation of compressive crushing plants is covered as well as real-time optimisation and optimisation of single production units. Each of optimisation areas is presented and a discussion around how these three areas will be able to communicate with each other is given. Several models, e.g. process performance behaviour with respect to wear, as well as fitness functions can be common for all three areas. Well-defined and representative fitness functions are of the utmost importance in order to assure that the optimisation results reflect the production targets. It is concluded that great benefits can be achieved by linking together different areas of optimisation. The future for compressing crushing lies, without a doubt, in tailored processes both with respect to machines optimised for each customer, plant parameters and operation routines as well as an on-line adjustment, which takes into account current information and control possibilities.

Key words: Crushing, Optimisation, Fitness function, Energy Efficiency

Short CV: Prof. Dr. Magnus Evertsson is professor in Machine Elements at the department of Industrial and Materials Science of the Chalmers University of Technology. He received his PhD from Chalmers in 2000 and was appointed Docent in 2006. His own research is on machine elements and systems with a focus on rock processing equipment and process plants used in the aggregates producing industry and mining. He has a close collaboration with the leading manufacturers of rock processing equipment, producers of aggregates and mining companies. Several research results and patent has been implemented in industrial applications and commercial products.

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Sanjay Kumar: Mechanical Activation of Waste and Secondary Resources: Our journey of 25 years.

Abstract: We started our activities in the area of mechanochemistry during the year 1999.  The present abstract is the summary of our journey of 25 years.  The activity was started to improve the resource and energy efficiency of cement production. With the use of mechanical activation, we are able to use 55% fly ash in Portland Pozzolana Cement, and 90% granulated blast furnace slag (GBFS) in Portland Slag Cement. The important learning was that fly ash and GBFS behave differently under similar condition and alteration in reactivity is mechanism specific. We have started a comprehensive program with the name of MARS (mechanical activation & reactivity of solids) under the guidance of Dr. Rakesh Kumar. This program encompasses both basic research and technology development. We were the first one to combine mechanical and chemical activation to develop geopolymer cement from fly ash. We could achieve a compressive strength of 120 MPa and 8 GPa flexural strength. With this understanding, we have developed the technology of quick road repairing material and transferred to an industry. Some of the area we studied mechanical activation are construction and demolition waste, enhancing ion exchange in gluconite, geopolymer cement from volcanic ash, and so on. Our current activities include the carbon sequestration using mechanical activation of slag, development of hybrid geopolymers, and improved recovery of metals from the black mass of lithium ion batteries.

Short CV: Prof. Dr. Sanjay Kumar is currently Chief Scientist & Head, Metal Extraction & Recycling Division, CSIR-National Metallurgical Laboratory, Jamshedpur, India and Professor, Academy of Scientific and Innovative Research (AcSIR), India. He is M.Sc & M.Phil in Geology, Ph.D in Chemical Technology (Ceramic Area), and P.G.Diploma in Cement Technology. He is currently Chairman, Indian Ceramic Society, Jamshedpur Chapter, Fellow, Indian Institute of Ceramics and Council Member, Indian Ceramic Society. He is also visiting faculty at University of Miskolc, Hungary. He is having 30 years of research experience in the area of waste utilization and recycling, low carbon cements, mechanochemistry, and circular economy. He has transferred and implemented three technologies in the industry. He is on the editorial board of two journals of repute. Dr. Kumar has edited 1 book, authored 5 book chapters, published 150 papers with more than 7000 citations, having 26 patents and delivered more than 50 keynote and invited talks.  He has mentored 3 Post Doc, guided 6 Ph.D and 14 M.Tech student. Dr Kumar is in the various international and national expert advisory committees of funding and policy making bodies. He is recipient of many prestigious awards like Pro Facultate Rerum Metallicarum Award by University of Miskolc, Hungary, 2018, NMD award from Ministry of Steel 2013, Viswakarma Award by Construction Industry Development Board 2013, Sarswat Award for best Eco-Innovation project 2012, Altekar Award for Best Technology 2011, and 2016, Tamotia Award in 2006 and 2015, Nijhawan Award 2005, and many more. His current research interest is extraction of critical metals and sustainable technology from waste, secondary and byproducts.

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Malcolm Powell: What are the limits of practical comminution energy?

Abstract: As industries utilising energy to reduce particle size to recover minerals and produce final products, we contribute an essential service to society, but at a significant energy cost. This motivates the increasing emphasis on reducing energy use in comminution processes. Theoretical calculations of minimum energy for rock breakage place industrial efficiency at somewhere between 0.1% and 1%. The value and validity of these figures are dubious, for they ignore the practicality of applying energy at industrial scale, the inherent (and irrecoverable) activation energy of crack propagation, and complexity of mineral grain boundaries in determining rock competence. Mechanical fracture is most efficiently achieved through single-particle stressing causing failure along the resultant tension planes. A relatively simple rolls breakage device was proposed in 2014 which has been developed to accurately measure this for many particles through a wide size range down to final product size below 200 µm. The results presented in the form of minimum practically achievable comminution energy by Ali et al (2003), Ali (2024) are most illuminating, indicating that the common conclusion of higher particle competence with decreasing size is incorrect. It is probable that this conclusion is a consequence of measuring increasing inefficiency of comminution at finer sizes, rather than rock competence. The results assessed against laboratory tests and industrial operations indicate that a viable target for reduction of energy in comminution circuits may be 75%. The uptake of this understanding should be via a structured approach to comminution device and circuit development. The consequences should provide a synergy of less energy with lower overall environmental impact – in terms of water use, tailings production, dust emission, contaminated waste – while enabling improved utilisation of our resources.

Ali, S., Powell, M.S., Yahyaei, M., Ballantyne, G.R. and Weatherley, D.K., 2023. Assessing comminution circuit performance using precision measurement of size specific energy.  Proc. Int. autogenous and semi-autogenous grinding and high pressure grinding roll technology 2023, Sep. 25-28, Ed. Simonian et al, Published CIM.

Ali, S., 2024.  Development of a novel ore characterisation method for the precise measurement of practical minimum comminution energy. Submitted in fulfilment of PhD, University of Queensland, February.

Short CV: Prof Malcolm Powell, Emeritus Professor University of Queensland, Honorary Professor University of Cape Town, Director of Liner Design services, Comminution & Transportation Technologies Inc., & CTO Geopyörä. Malcolm has applied fundamental comminution research to design and process improvement on over 70 mines worldwide during 40 years at Mintek, leader comminution at Centre for Minerals Research UCT, Professor of comminution at the JKMRC in Australia, and now independently. His work is published in over 240 papers and has been presented in as many conferences worldwide. Malcolm collaborates extensively, with close compatriots on 5 continents forming the Global Comminution Collaborative (GCC) – providing an expert research and consulting base covering the full comminution process chain, and developing people for our future industry. Malcolm’s research vision is of integrated total process simulation as a tool for innovation – linking geology, mining, energy and size reduction, gangue rejection and recovery into flexible process design and process optimisation. Through his research companies, Malcolm is currently applying advanced modelling techniques and knowledge of fracture to the development of new highly energy-efficient, processes enhancing and lower environmental impact equipment to be integrated into flexible processing of the future.

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Abstract: Fluidised bed reactors are particularly advantageous for conducting solid–gas chemical processes. Nonetheless, solid particles placed in a state of fluidisation are subject to comminution phenomena (attrition and fragmentation) with alteration of their residence time distribution and reactive performances. This contribution focuses on the comminution behaviour of limestone sorbent particles which in a fluidised bed have the ability to capture CO₂, in processes of: 1) gasification for the production of syn-gas with increased H₂ content ("sorption-enhanced gasification”); 2) removal of CO₂ from industrial gaseous effluents (“calcium looping”); 3) thermochemical solar energy storage (“TCES”). The inter-relationships between operating conditions, tendency to comminution phenomena (e.g. surface wear and impact fragmentation) and performances of the sorbent in terms of CO₂ capture capacity, in the processes listed above, will be highlighted.

Short CV: Fabio Montagnaro, Ph.D. in Chemical Engineering, is Professor of Chemical Plants and Italian Delegate at European Federation of Chemical Engineering - Working Party on Comminution and Classification. Apart from comminution of solid materials in reactive processes, other main research activities deal with: thermochemical solar energy storage; biomass thermo-conversion to produce energy vectors; purification of gaseous streams from pollutants and greenhouse agents; liquid-solid and gas-solid adsorption; synthesis of innovative/eco-sustainable binders; re-use of solid wastes of different nature; chemical processes in fluidised bed reactors; design and modelling of chemical reactors and plants; fractal dynamics in heterogeneous processes. Fabio is author of about 140 Journal-papers, with global “Hirsch index” of 37. His scientific activities have been carried out in collaboration with several public and private partners, and within international and national financed projects. Invited speaker/organiser for numerous international Conferences, Fabio has been (2015–2021) Associate Editor for Royal Society of Chemistry, and is currently Guest Editor/Member of the Editorial Board of other Journals. Contact and info: This email address is being protected from spambots. You need JavaScript enabled to view it.; www.docenti.unina.it/fabio.montagnaro. 

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Peter Baláž: MECHANOCHEMISTRY IN EXTRACTIVE METALLURGY, MATERIALS SCIENCE AND MEDICINE: GOOD PERSPECTIVE FOR MY FOLLOWERS

Institute of Geotechnics, Slovak Academy of Sciences, Košice, Slovakia

Abstract: In this retrospective lecture the overall view on my activities in mechanochemistry during more than 40 years stay at Slovak Academy of Sciences will be presented. The agenda of results in science and technology of extractive metallurgy, materials science and medicine will be incorporated.  Knowledge which we obtained from treatment of nature minerals to obtain metals and application of the minerals in cancer treatment  was later broaden for preparation of synthetic minerals to obtain advanced materials with the application in photovoltaics and thermoelectrics.  All the mentioned approaches represent contribution to the common aim of mechanochemists: to prepare new materials with the desired properties in a reproducible way under easy-operating, environmentally friendly and essentially waste-free conditions. However, the presented results required cooperation with scientists from many foreign institutions. The great help of my followers who performed PhD studies under my supervision is strongly appreciated.

Short CV: Dr.h.c. Prof. RNDr. Peter Baláž, DrSc. is a specialist in the field of materials science, extractive metallurgy and mineral processing. He is member of Department of Mechanochemistry which is a centre of the research in mechanochemistry in Slovakia. Prof. Baláž is a member of various institutions such as IMA (International Mechanochemical Association) at IUPAC (International Union of Pure and Applied Chemistry), RFM (Reseau Francais de Mechanosynthese) and the Learned Society of Slovak Academy of Sciences. In the years 2000, 2008 and 2015 he obtained the Prizes of the Slovak Literary Foundation for his monographs “Extractive Metallurgy of Activated Minerals” (Elsevier) and “Mechanochemistry in Nanoscience and Minerals Engineering” (Springer). His SCI records in the year 2001, 2006, 2009, 2012 and 2014 has been awarded by Slovak Literary Found. During his carrier he completed long-term stays at Technical Universities in Berlin and Clausthal (Germany), University of Maryland Baltimore County (USA) and Busan National University (South Korea). He is active as PhD supervisor. Under his supervision 10 PhD thesis were successfully defended. He published 4 books, 16 chapters in monographs, 292 scientific papers in journals registered in Scopus. According to Scopus his papers have been cited more than 5500 times. His Hirsch index is 35.

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Ádám Rácz: Particle shape modification by comminution in mineral and waste processing

Institute of Raw Material Preparation and Environmental Processing, University of Miskolc, Hungary

Abstract: The change of particle shape is a side effect in the comminution process; however in some cases the main objective of the comminution process can be the modification of particle shape as well. The particle shape modification can be achieved during the reduction of the particle size and without significant particle size decrease as well. In the presentation the different cases of targeted particle shape modification and their applications will be shown and the evaluation of the process by particle shape distribution and by efficiency parameters will be discussed for brittle and non-brittle materials as well.

Short CV: Dr. Ádám Rácz, PhD, associate professor at the Institute of Raw Material Preparation and Environmental Processing, University of Miskolc, Hungary. He has studied process engineering at University of Miskolc and received his PhD title in 2014. He has more than 15 years of experience in mineral and waste processing. His research interests are focused on the comminution processes for brittle and non-brittle materials also. In his previous work, he dealt with dry grinding and shape modification in stirred media mill, and later broadened his research area and worked in the field of design and optimization of waste preparation technologies and comminution of non-brittle materials. He has participated in many industrial research projects and in several Hungarian-European projects involving industrial and academic partners.