Understanding concave particle morphology is essential for characterizing granular materials and their mechanical behavior. This study introduces a unified computational framework for quantifying concavity in three-dimensional (3D) rock, sand, and rubber particles. The framework integrates algorithms for identifying convex and concave surface points, quantifying local concavity, and performing optimized concavity-driven convex decomposition without conventional pocket and bridge operations. A novel descriptor, three-dimensional Concavity Driven Weight (3D CDW), measures morphological complexity through the minimum number of dominant convex components required to represent a prescribed proportion of particle volume. Sensitivity analyses examine the effects of computational parameters and cumulative volume thresholds on decomposition and particle ranking. Relationships between 3D CDW and conventional descriptors, including concavity number, depth, and surface complexity, are investigated to assess its geometric significance. Mechanical relevance is explored through associations between 3D CDW and a von Mises stress-based localization index under external loading. Evaluation across rock, rubber, and coral sand particles supports the framework’s applicability to complex particle geometries. The proposed algorithms have been verified, providing a foundation for improved morphological characterization and future investigations of shape-dependent mechanical responses in granular materials.
The electric smelting furnace (ESF) is emerging as a low-carbon alternative to conventional blast furnaces, but particle segregation in the burden has not yet been well understood. In this work, the charging process in the ESF is studied and the effects of several key variables on particle segregation are quantified under industrial ESF conditions, including reductant particle size, metallisation and charging layout, using discrete element method (DEM) simulations. The distribution of reductant mass fractions, Beaudry mixing indices, and reductant contact networks are analysed during the charging process. The results show that reductant particle size plays an important role in segregation; smaller reductant particles mix more thoroughly and have a higher mixing index, while forming a more extensive reductant contact network and minimising segregation. The influence of metallisation degree is less than that of reductant particle size: a higher degree of metallisation reduces the mixing index, indicating increased segregation, and decreases the extent of the reductant contact network due to lower coke content. The two-port feed layout significantly improves burden distribution compared to a single-port feed, with a higher mixing index and shorter dominant reductant contact chains.
