University of Leeds unravels complex particle interactions using Rocky DEM

A world leader in particle technology research, the University of Leeds is successfully applying Rocky discrete element modeling (DEM) software to gain an accurate understanding of particle behavior in specific systems – a simulation practice that bulk-material-handling and processing industries can readily translate into reduced prototyping, time and costs. In the latest investigation, researchers at the School of Chemical and Process Engineering used Rocky DEM to accurately predict material behavior within pin-milling equipment, an application that has seen limited study.

A pin mill efficiently and quickly breaks up particulate solids, employing metal pins that repeatedly move past each other in a grinding motion. Such equipment is ideal for a broad range of pharmaceutical, detergent and agrochemical products. Traditionally, it has been extremely difficult to leverage bench-test data and prototypes to predict individual particle behavior within such a bulk assembly, with an objective to optimize size-reduction equipment. More-recent practices rely on basic DEM software, whose solutions use simple spheres to represent particles. These results have been largely inaccurate because, in the real world, particles are often non-spherical in nature (concave, convex, irregular, elongated, for example).

Performance improvement in industrial operations

“Rocky DEM first got our attention due to its capability to model faceted particles along with its intrinsic particle breakage feature, both which stand out from the traditional bonded-spheres model,” said Mojtaba Ghadiri, professor at the School of Chemical and Process Engineering. “The role of particle shape is critical in many process industries. Supplementing with material properties characterized experimentally, Rocky DEM makes it easy to incorporate more-realistic particle shapes in modeling a range of industrial operations, concerning size enlargement and reduction, powder mechanics and environmental effects.”

Ghadiri added that powder’s macroscopic bulk behavior is governed by microscopic activity of individual particles in an assembly. Analyzing these particle interactions can lead to improved technology for mixing and segregation as well as other applications, such as fluidization and dispersion from aggregate to lean phase. “There are quite a few research projects in our group that focus on particle breakage in different operation units, and the ability to visualize breakage with real polyhedral particle shapes is an added advantage,” noted Wei Pin, a member of the specialized Ghadiri Research Group within the school. His role is to analyze the interaction between the pin mill’s rollers and particles as well as to study breakage modeling.

The group intends to continue its Rocky DEM investigations, trying to fill in the gaps in understanding powder behavior, especially in processes where limited work has been done, such as milling, coating and flowability. The introduction of Rocky DEM to the group has widened their horizons.

About the University of Leeds

The University of Leeds is one of the top 100 universities in the world and renowned for its teaching and research quality. Its interdisciplinary and impact-orientated research addresses challenges at regional, national and global levels. Programs are user-led and solution-focused, driven by the needs of partners and stakeholders. Ghadiri Research Group is a specialized unit within the School of Chemical and Process Engineering at the
University of Leeds, focusing on the fundamentals of particle technology, in particular the development of relationships between microscopic and macroscopic properties and phenomena.

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