NERDG 2026
Poster 9 Abstract
Understanding Particle Attrition for Reactive Systems and Crystallization with CFD-DEM Predictions
Saeed Najafian (1), Sean Ross (2), Simon Velasquez (2)
(1) University of Connecticut, (2) AbbVie
Presenting Author: Saeed Najafian
Corresponding Author: Sean Ross, [email protected]
Purpose
Reactions in organic solvents that rely on insoluble inorganic bases often show large performance differences depending on the input particle size and extent of particle grinding. In many cases pre-milling is not practical because these solids are hygroscopic, and their surfaces can quickly become coated with by-products that slow reaction rates. Therefore, an in-situ process to regenerate fresh surface area offers a promising alternative. However, selecting the appropriate technology and scaling up particle size reduction remain challenging. This work investigates particle breakability across materials and mixing technologies and uses CFD-DEM modeling to understand the mechanisms responsible for size reduction in reactive slurries.
Methods
We evaluated particle breakability using an Aero Malvern Mastersizer by correlating inlet air pressure, particle velocity, and changes in specific surface area, enabling estimation of material hardness and fracture toughness. CFD-DEM simulations were then developed to model solid–liquid mixing under several geometries, including saw-tooth impeller, as well as a probe wet-mill device. Simulations tracked particle motion, suspension quality, impact velocity, and collision forces under varying speeds and solid loadings. Experimental particle size reduction data from potassium carbonate, cesium carbonate, and other representative materials were used to interrogate model predictions and compare performance across mixing technologies.
Results
Breakability assessments showed strong linear correlations between impact velocity and increase in specific surface area, with slopes reflecting material sensitivity to breakage. Across impeller types, CFD-DEM simulations showed differences in dead zones, suspension quality, and collision frequency strongly influenced the likelihood of attrition. Moreover, simulations revealed that although high-shear impellers create vigorous flow, the resulting particle impact velocities are significantly lower than the velocities predicted to cause fracture for many solids. While wet-mill technology generated higher normal forces compared to impellers at equivalent tip speeds.
Conclusion
This work demonstrates that under these experimental conditions impact is not the dominant breakage mechanism during mixing and that attrition, chipping, or fragmentation may better explain observed size reduction. Integrating breakability assessment with CFD-DEM provides a practical workflow for identifying suitable technologies, optimizing operating conditions, and guiding scale-up for reactive systems where particle attrition influences performance.
Keywords
CFD-DEM, Particle attrition, Particle size reduction, Scale-up
Poster 9 Abstract
Understanding Particle Attrition for Reactive Systems and Crystallization with CFD-DEM Predictions
Saeed Najafian (1), Sean Ross (2), Simon Velasquez (2)
(1) University of Connecticut, (2) AbbVie
Presenting Author: Saeed Najafian
Corresponding Author: Sean Ross, [email protected]
Purpose
Reactions in organic solvents that rely on insoluble inorganic bases often show large performance differences depending on the input particle size and extent of particle grinding. In many cases pre-milling is not practical because these solids are hygroscopic, and their surfaces can quickly become coated with by-products that slow reaction rates. Therefore, an in-situ process to regenerate fresh surface area offers a promising alternative. However, selecting the appropriate technology and scaling up particle size reduction remain challenging. This work investigates particle breakability across materials and mixing technologies and uses CFD-DEM modeling to understand the mechanisms responsible for size reduction in reactive slurries.
Methods
We evaluated particle breakability using an Aero Malvern Mastersizer by correlating inlet air pressure, particle velocity, and changes in specific surface area, enabling estimation of material hardness and fracture toughness. CFD-DEM simulations were then developed to model solid–liquid mixing under several geometries, including saw-tooth impeller, as well as a probe wet-mill device. Simulations tracked particle motion, suspension quality, impact velocity, and collision forces under varying speeds and solid loadings. Experimental particle size reduction data from potassium carbonate, cesium carbonate, and other representative materials were used to interrogate model predictions and compare performance across mixing technologies.
Results
Breakability assessments showed strong linear correlations between impact velocity and increase in specific surface area, with slopes reflecting material sensitivity to breakage. Across impeller types, CFD-DEM simulations showed differences in dead zones, suspension quality, and collision frequency strongly influenced the likelihood of attrition. Moreover, simulations revealed that although high-shear impellers create vigorous flow, the resulting particle impact velocities are significantly lower than the velocities predicted to cause fracture for many solids. While wet-mill technology generated higher normal forces compared to impellers at equivalent tip speeds.
Conclusion
This work demonstrates that under these experimental conditions impact is not the dominant breakage mechanism during mixing and that attrition, chipping, or fragmentation may better explain observed size reduction. Integrating breakability assessment with CFD-DEM provides a practical workflow for identifying suitable technologies, optimizing operating conditions, and guiding scale-up for reactive systems where particle attrition influences performance.
Keywords
CFD-DEM, Particle attrition, Particle size reduction, Scale-up
