Size Reduction

IFPRI Strategic Plan for Supporting Research in Size Reduction of Particulate Solids

Since the formation of IFPRI in 1979, its membership has been interested in the millennia-old process of size reduction, as it is the most energy intensive and inefficient particulate solids process and is also complex and the least understood.  From the process engineering view point, the interest is in the energy utilisation and scale-up of various mill types, issues which have been besetting the industry forever.  The materials-related aspects of interest are:

  1. the smallest possible particle size, which could be comminuted, for a number of applications, such as the highly sought-after ‘top-down’ approach to nano-particle production;
  2. the most desirable, yet challenging issue of having predictive size distribution of comminuted materials for feed materials larger than the above limit;
  3. appropriate methods of application of stresses for a given material, i.e. point loading, distributed loading or loading accompanied by frictional traction, low or high strain rate loading, level of stresses required for comminution to a certain size range, and environmental conditions;
  4. For crystalline solids, the role of crystal habit in affecting the product properties, in particular the changes brought about by milling in surface structure, properties and chemical activity, phase transformations, and functionality.
  5. For amorphous solids, the chemical and physical stability following size reduction.
  6. In a liquid environment can the surfaces be modified and in a gas environment, what is the effect of humidity?

IFPRI’s approach in defining the strategic research direction and new programmes is by consultation with the members, helped by workshops in which the states of the art and understanding are critically reviewed and analysed by leading experts in the field.   IFPRI organised a strategic workshop in 2011 to identify research needs to achieve a better understanding of size reduction.  Nine topics were addressed: energy utilisation, scale-up, current capabilities in modelling, role of feed properties, solid state and structure, product characteristics/attributes, milling aids, mechano-chemical activation, nano-milling and undesirable effects, such as electrostatics, contamination and wear.  Considering the generic needs of IFPRI members, the workshop identified five paramount research priority topics:

  1. Review of dry/wet grinding and processing aids
  2. Molecular modelling of mechanical properties
  3. Manufacturing micron sized advanced materials: the mill as a reactor
  4. ‘Grindability’ test: modelling, measurement and mill fingerprinting
  5. Assessment of energy utilisation distribution throughout the mill across scales


Currently, IFPRI is supporting a research programme on modelling of grindability by the Discrete Element Method by Professor Jin Ooi, School of Engineering, The University of Edinburgh,, and a review on innovative non-mechanical approaches to milling by Professor Luis Marcelo Tavares, Dept de Engenharia Metalurgica e de Materiais Cid. Universitária-Centro de Tecnologia –Rio de Janeiro,





Past sponsored research projects and reviews in size reduction include:


  1. Characterisation of Particle Grindability by Indentation and Impact, Hare and Ooi, Leeds/ Edinburugh, UK (2014)
  2. Agglomerate and Aggregate Strength, Salman, Sheffield, UK (2008)            
  3. Milling of Organic Solids, Ding, Leeds, UK (2005-2009)
  4. Sub-micron particle production in stirred media mills, Kwade, Braunschweig, Germany (2006)
  5. Nanomilling of Inorganic Particles in Different Solvents in Stirred Media Mills, Peukert, Erlangen, Germany (2004-2007) 
  6. The Influence of Interparticle Interactions on Rheology and Stability in Stirred Media, Peukert, Erlangen (2004)
  7. The Influence of Interparticle Interactions on Rheology and Stability in Stirred Media Mills, Peukert & Wagner, Erlangen & Delaware (2004-2005)
  8. Study on small grinding media for submicron particle production in stirred media mills, Schwedes, Braunschweig, Germany (2000-2004)
  9. Mechanochemistry of Materials - Relation between Mechanochemical Phenomena and Media Motion in a Mill,   Saito & Baron, Tohoku and Ecole des Mines d’Albi (2000) 
  10. Parameters of controlled grinding, Leschonski, Clausthal, Germany (1999-2000)     
  11. Mechanochemical Reactions systems by Ball Milling, Saito, Tohoku, Japan (1998-2003)              
  12. Impact Attrition of Agglomerate Particulate Solids, Ghadiri, Surrey (1992-1998)
  13. Achievements in Size Reduction, de Jong, Akzo, The Netherlands (1998)
  14. Dispersion Characteristics of Agglomerated and Non-Agglomerated Powdered Materials, Schubert, Karlsruhe, Germany (1997-1998)            
  15. Computer Simulation of Particle Fracture, Campbell, UCLA (1992-1998)
  16. Preparation of Well Dispersed systems: The Role of Oxide Bridging in Agglomerate Formation, Smith, New Mexico, USA (1992)
  17. An Experimental Study of Fragmentation by High Velocity Impacts on a Target and by Air Jet Milling,          Guigon, Dodds & Pons, Compiegene, Albi, Nancy, France (1993-1998)              
  18. Methods for Increasing the Steepness of the Particle Size Distribution in the Grinding of Chemicals and Pharmaceuticals, Klimpel, Midland, Michigan, USA (1996)
  19. Test Devices for Comminution, Schonert  , Clausthal, Germany (1995)
  20. Impact Attrition of Agglomerate Particulate Solids, Ghadiri, Surrey (1992-1996)
  21. Experimental Simulation of Processes in Ball Mills by Fragmentation of Particle Assemblies, Weichert, Clausthal, Germany (1991-1994)
  22. Fragmentation of Particle Assemblies, Weichert & Rajamani, Clausthal and Utah, Germany & USA (1990-1991)
  23. The Rate and the Limit Particle Size of Ultrafine Grinding of Hard Materials in Liquid, Jimbo, Nagoya, Japan (1991-1994)           
  24. Agglomeration in powder Processing and Agglomerate Strength Determination for the Preparation of well dispersed systems, Thoma, New Mexico, USA (1990)   
  25. Review of Fracture Mechanics, Isherwood, Imperial College (1990)
  26. Review of Comminution by Impact, Leschonski, Clausthal (1989)   
  27. Review of Size Reduction and Comminution research at the University of Karlsruhe, Weichert, Clausthal, Germany (1989)       
  28. Review of Size Reduction and Comminution research at the University of Karlsruhe, Weichert, Clausthal Zellerfeld (1989)
  29. Impact Attrition of Polymeric Particulate Solids, Ghadiri, Surrey (    1988-1992)
  30. Some Observations on the Possible Application of Fracture Mechanics to Particle Breakage, Isherwood, Imperial College (1988)
  31. Impact Grinding, Leschonski, Clausthal Zellefeld (1987-1989)
  32. Critical Parameters in the Wetting of Powder Agglomerates by Aqueous Media, Ayala, Carnegie Mellon (1986)
  33. Impact Attrition of Crystalline Particulate Solids, Ghadiri, Surrey (1984-1988)
  34. Attrition of Bulk Particulate Solids, Bridgwater, Birmingham (1982-1989)
  35. Particle Attrition, Vervoorn, Delft (1982-1986)
  36. Mechanical Properties of Powder and Methods of Their Estimation, Makino, Kyoto, Japan (1983-1984)
  37. Attrition studies, Beddow, Iowa (1983)    
  38. Studies on abrasive and erosive wear of materials by particle in Japan, Hashimoto, Sintokogya Ltd, Japan (1983)      
  39. Effect of temperature on the agglomerate strength of polymeric particles, Sekiguchi, Chuo, Japan (1982)         
  40. Size Reduction of Particles, van Brakel, Delft (1981)           
  41. A State of the Art Review for the Four R & D Projects of Particle Technology in Japan, Iinoya, Tokyo, Japan (1980)