Attrition is the unintentional breakage of particles during processing and handling. Comminution is the wilfully induced breakage, intended for size reduction of particles. Attrition is a problem that is common in many particle processing industries as it results in a deviation from desired product size, shape and mechanical properties. Another detrimental aspect of attrition is the generation of fine debris or dust, which can be problematic as it becomes airborne or adheres to process vessels. Attrition is common in detergent, pharmaceutical, agricultural and many other processing industries, as a result of impact, crushing or shearing events occurring throughout the manufacturing processes.

The extent of particle breakage is dependent on the strength of particles and the magnitude and loading direction(s) of the stresses they are exposed to. Due to the inherent distribution of strength, size and shape within a particle sample, and the difficulty in establishing the stresses occurring within a bed, no mechanistic models of bulk particle breakage exist. Consequently, empirical or predictive approaches are commonly applied to establish breakage rates. Our work has recently shown that by analysing the prevailing stresses in an agitated bed using DEM and incorporating an empirical, experimentally-determined breakage function an excellent prediction of particle breakage within the bed is achievable. This approach could be applied to any system where breakage occurs due to shear deformation.

Our work has also shown that breakage of particles by impacting rigid surfaces can be rapidly determined by a few impact experiments. We have shown the volume of material removed from semi-brittle particles in the chipping regime is proportional to the particle size, density, hardness, the square of the velocity and inversely proportional to the fracture toughness. If these properties are known then a few simple tests can determine the proportionality factor and describe the impact breakage, otherwise a wider range of tests can determine this.

Our research group has a number of devices for measuring particle breakage:

  • Bridgwater attrition shear cell
  • Single particle impact tester
  • Instron mechanical tester – for measuring single or bulk crushing
  • Single ball mill – for understanding bulk milling
  • Micromaterials NanoTest – for determining hardness, Young’s modulus and fracture toughness by nanoindentation
  • Micromaterial Nano-Crush for strength testing of fine particles at tribological testing

Related Projects

Current Projects

Recent Projects

  • Particle Breakage in Dryers and Agitated Beds
  • Development of a Device to Test the Strength of Enzyme Granules

Past Projects

  • Analysis of Enzyme Dust Formation in Detergent Manufacturing Plants
  • Breakage of Catalyst Carrier Particles
  • Mitigation of Attrition in Fluid Catalytic Cracking Units
  • Analysis of ISO Fluidised Bed Jet Test
  • Attrition of Particulate Solids in Fluidised Bed Jets
  • Formation, Processing and Characterisation of Pharmaceutical Powders
  • Attrition of Particulate Solids
  • Distinct Element Simulation of Attrition in an Annular Shear Cell
  • Disintegration of Weak Agglomerates
  • Hare, C., Ghadiri, M., “Influence of Measurement Cell Size on Predicted Attrition by the Distinct Element Method“, Powder Technology, Available online 5 May 2012, ISSN 0032-5910, 10.1016/j.powtec.2012.04.061.
  • Hare, C., Ghadiri, M., Dennehy, R. 2011, “Prediction of Attrition in Agitated Particle Beds“, Chemical Engineering Science, 66(20), 4757-4770.
  • Ahmadian, H., Hassanpour, A., Ghadiri, M. 2011, “Analysis of Granule Breakage in a Rotary Mixing Drum: Experimental Study and Distinct Element Analysis“, Powder Technology, 210(2), 175-180.
  • Olusanmi, D., Roberts, K., Ghadiri, M., Ding, Y. 2011. “The breakage of Aspirin under Quasi-Static Indentation and Single Particle Loading: Effect of Crystallographic Anisotropy“, International Journal of Pharmaceutics, 411(1-2), 49-63.
  • Olusanmi, D., Wang, C., Ghadiri, M., Ding, Y. and Roberts, K.J., 2010, “Effect of Temperature and Humidity on the Breakage Behaviour of Aspirin and Sucrose Particles“, Powder Technology, 201(3), 248-252.
  • Ahmadian, H. and Ghadiri, M. 2010, “Attrition Shearing of Granules using Rotating Rollers: Experimental Study and DEM Simulation“, World Congress of Particle Technology 6, Nuremberg.
  • Hassanpour, A., Antony , S.J. and Ghadiri, M., “Influence of Interface Energy of Primary Particles on the Deformation and Breakage Behaviour of Agglomerates Sheared in a Powder Bed“, Chemical Engineering Science, 63(23), 5593-5599, 2008.
  • Ahmadian, H., Ghadiri, M. , 2007, “Analysis of Enzyme Dust Formation in Detergent Manufacturing Plants“, Advanced Powder Technology, 18, pp. 53-67.
  • Hassanpour, A., Antony , S.J., Ghadiri, M. , 2007, “Effect of Size Ratio on the Behaviour of Agglomerates Embedded in a Bed of Particles Subjected to Shearing: DEM Analysis“, Chemical Engineering Science, 62(4), pp 935-942.
  • Yang, W., Kwan, C.C., Ding, Y.L., Ghadiri, M., Roberts, K.J. , 2007, “Milling of Sucrose“, Powder Technology, 174, 14-17.

Related Publications


  • Ahmadian, H. and Ghadiri, M. 2010, “Attrition Shearing of Granules using Rotating Rollers: Experimental Study and DEM Simulation“, World Congress of Particle Technology 6, Nuremberg.
  • Hassanpour, A., Antony , S.J. and Ghadiri, M., “Influence of Interface Energy of Primary Particles on the Deformation and Breakage Behaviour of Agglomerates Sheared in a Powder Bed“, Chemical Engineering Science, 63(23), 5593-5599, 2008.
  • Ahmadian, H., Ghadiri, M. , 2007, “Analysis of Enzyme Dust Formation in Detergent Manufacturing Plants“, Advanced Powder Technology, 18, pp. 53-67.
  • Hassanpour, A., Antony , S.J., Ghadiri, M. , 2007, “Effect of Size Ratio on the Behaviour of Agglomerates Embedded in a Bed of Particles Subjected to Shearing: DEM Analysis“, Chemical Engineering Science, 62(4), pp 935-942.
  • Yang, W., Kwan, C.C., Ding, Y.L., Ghadiri, M., Roberts, K.J. , 2007, “Milling of Sucrose“, Powder Technology, 174, 14-17.
  • Moreno-Atanasio, R., Ghadiri, M. , 2006, “Mechanistic Analysis and Computer Simulation of Impact Breakage of Agglomerates: Effect of Surface Energy“, Chemical Engineering Science, 61(8), pp 2476-2481.
  • Ning, Z., Ghadiri, M. , 2006, “Distinct Element Analysis of Attrition of Granular Solids under Shear Deformation“, Chemical Engineering Science, 61(18), 5991-6001.
  • Kwan, C.C., Mio, H., Chen, Y.Q., Ding, Y.L., Saito, F., Papadopoulos, D.G., Bentham, A.C., Ghadiri, M. , 2005, “Analysis of the Milling Rate of Pharmaceutical Powders using the Distinct Element Method (DEM)“, Chemical Engineering Science, 60, pp. 1441-1448.
  • Samimi, A., Hassanpour, A. and Ghadiri, M. , 2005, “Single and Bulk Compressions of Soft Granules: Experimental Study and DEM Evaluation“, Chemical Engineering Science, 60, pp. 3993-4004.
  • Subero-Couroyer, C., Ghadiri, M., Brunard, N., Kolenda, F. , 2005, “Analysis of Catalyst Particle Strength by Impact Testing: The Effect of Manufacturing Process Parameters on the Particle Strength“, Powder Technology, 160(2), 67-80.
  • Bentham, A.C., Kwan, C.C., Ghadiri, M., Boerefijn, R. , 2004, “Fluidised Bed Jet Milling of Pharmaceutical Powders“, Powder Technology, 141, pp. 233-238
  • Hassanpour, A., Ghadiri, M., Bentham, A.C., Papadopoulos, D.G. , 2004, “Effect of Temperature on Energy Utilisation of Bulk Crushing of α-Lactose Monohydrate“, Powder Technology , 141, pp. 239-243.
  • Golchert, D. J., Moreno, R., Ghadiri, M., Litster, J. D. , 2004, “Effect of Granule Morphology on Breakage Behaviour During Compression“, Powder Technology, 143-4, pp. 84-96.
  • Chen, Y.Q., Ding, Y.L., Papadopoulos, D.G., Ghadiri M. , 2004, “Energy Base Analysis of Milling α-Lactose Monohydrate“, Journal of Pharmaceutical Science, 93, pp. 886-895.
  • Kwan, C.C., Chen, Y.Q., Ding, Y.L., Papadopoulos, D.G., Bentham, A. C., Ghadiri, M. , “Development of a Novel Approach Towards Predicting the Milling Behaviour of Pharmaceutical Powders“, European Journal of Pharmaceutical Sciences, 23, pp. 327-336.
  • Samimi, A., Moreno, R., Ghadiri, M. , 2004, “Impact Damage Analysis of Agglomerates: Effect of Impact Angle“, Powder Technology, 143-4, pp. 97-109.
  • Hassanpour, A., Ghadiri, M., Bentham, A.C., Papadopoulos, D.G. , 2003, “Distinct Element Analysis of the Effect of Temperature on the Bulk Crushing of ��-Lactose Monohydrate“, Advanced Powder Technology, 14, pp. 427-434.
  • Kwan, C.C., Ghadiri, M., Papadopoulos, D.G., Bentham, A.C. , 2003, “The Effects of Operating Conditions on the Milling of Microcrystalline Cellulose“, Chemical Engineering and Technology, 26, pp. 185-190.
  • Moreno, R., Antony, S.J., Ghadiri, M., 2003, “Effect of the Impact Angle on the Breakage of Agglomerates: a Numerical Study using DEM“, Powder Technology, 130, pp. 132-137.
  • Samimi A., Ghadiri, M., Boerefijn, R., Groot, A., Kohlus, R. , 2003, “Effect of Structural Characteristics on Impact Breakage of Agglomerates“, Powder Technology, 130, pp. 428-435.
  • Subero-Couroyer, C., Ghadiri, M., Brunard, N., Kolenda F. , 2003, “Weibull Analysis of Quasi-Static Crushing Strength of Catalyst Particles“, Chemical Engineering Research and Design, 81, pp. 953-962.
  • Ghadiri, M., Zhang, Z. , 2002, “Impact Attrition of Particulate Solids. Part 1: A Theoretical Model of Chipping“, Chemical Engineering Science, 57, pp. 3659-3669.
  • Zhang, Z., Ghadiri, M. , 2002, “Impact Attrition of Particulate Solids. Part 2: Experimental Work“, Chemical Engineering Science, 57, pp. 3671-3686.
  • Ghadiri M., Moreno, R., Matsusaka, S. , 2002, “Impact Damage Analysis of Agglomerates Using Distinct Element Method“, Journal of the Society of Powder Technology Japan, 39, pp. 885-892 (in Japanese)
  • Subero, J., Ghadiri, M. , 2001, “Breakage Pattern of Agglomerates“, Powder Technology, 120, pp. 232-243.
  • Boerefijn, R., Gudde, N.J., Ghadiri, M. , 2000, “A Review of Attrition of Fluid Cracking Catalyst Particles“, Advanced Powder Technology, 11, pp. 145-174.
  • Couroyer, C., Ning, Z., Ghadiri, M. , 2000, “Distinct Element Analysis of Bulk Crushing: Effect of Particle Properties and Loading Rate“, Powder Technology, 109, pp. 241-254.
  • Couroyer, C., Ghadiri, M., Laval, P., Brunard, N., Kolenda, F. , 2000, “Methodology for Investigating the Mechanical Strength of Reforming Catalyst Beads“, Oil and Gas Science and Technology – Revue de l’Institut FranÁais du PÈtrole, 55, pp. 67-85.
  • Ghadiri, M., Ning. Z., Kenter, S.J., Puik, E. , 2000, “Attrition of Granular Solids in a Shear Cell“, Chemical Engineering Science, 55, pp. 5445-5456.
  • Scala, F., Salatino, P., Boerefijn, R., Ghadiri, M. 2000, “Attrition of Sorbents During Fluidized Bed Calcination and Sulphation“, Powder Technology, 107, pp. 153-167.
  • Couroyer, C., Ning, Z., Ghadiri, M., Brunard, N., Kolenda, F., Bortzmeyer, D., Laval, P. , 1999, “Breakage of Macroporous Alumina Beads under Compressive Loading: Simulation and Experimental Validation“, Powder Technology, 105, pp. 57-65 (correction: ibid, 111, pp. 252-253, 2000).
  • Subero, J., Ning, Z., Ghadiri, M., Thornton, C. , 1999, “Effect of Interface Energy on the Impact Strength of Agglomerates“, Powder Technology, 105, pp. 66-73.
  • Ning, Z., Boerefijn, R., Ghadiri, M., and Thornton, Thornton, C. , 1997, “Distinct Element Simulation of Impact Breakage of Lactose Agglomerates“, Advanced Powder Technology, 8, pp. 15-37.
  • Papadopoulos, D.G., Ghadiri, M. , 1996, “Impact Breakage of Poly-methylmethacrylate (PMMA) Extrudates: I. Chipping Mechanism“, Advanced Powder Technology, 7, pp. 183-197.
  • Ghadiri, M., Boerefijn, R. “A Model of Attrition in the Jetting Region of Fluidised Beds“, KONA Powder and Particle, No. 14, pp. 5-15.
  • Ning, Z., Ghadiri, M. , “Attrition of Bulk Particulate Solids in a Shear Cell: An Investigation by Computer Simulation“, Materials Review, Vol. 10, pp. 72-77 (in Chinese).
  • Ghadiri, M., Cleaver, J.A.S., Tuponogov, V.G., Werther, J. , 1994, “Attrition of FCC Powder in the Jetting Region of a Fluidised Bed“, Powder Technology, 80, pp. 175-178.
  • Arteaga, P.A., Ghadiri, M., Lawson, N.S., Pollock, H.M. , 1993, “Use of Nanoindentation to Assess Potential Attrition of Particulate Solids“, Tribology International, 26, pp. 305-310.
  • Cleaver, J.A.S., Ghadiri, M., Rolfe, N. , 1993, “Impact Attrition of Sodium Carbonate Monohydrate Crystals“, Powder Technology, 76, pp. 15-22.
  • Ghadiri, M., Yuregir, K.R., Pollock, H.M., Ross, J.D.J., Rolfe, N.J. , 1991, “Influence of Processing Conditions on Attrition of NaCl-Crystals“, Powder Technology, 65, pp. 311-320.
  • Yuregir, K.R., Ghadiri, M., Clift, R. , 1987, “Impact Attrition of Sodium-Chloride Crystals“, Chemical Engineering Science, 42, pp. 843-853.
  • Yuregir, K.R., Ghadiri, M., Clift, R. , 1986, “Observations on Impact Attrition of Antigranulocytes Sliods“, Powder Technology, 49, pp.53-57.

Related Publications

  • Hare, C., Ghadiri, M., “Influence of Measurement Cell Size on Predicted Attrition by the Distinct Element Method“, Powder Technology, Available online 5 May 2012, ISSN 0032-5910, 10.1016/j.powtec.2012.04.061.