Shape Characterization of Ferrous Burden Material of Blast Furnace Feed using Image Analysis

TL;DR

The paper develops a size-range independent framework to quantify the shape of ferrous-burden feed components (pellets, sinter, and iron ore lumps) using 2D image analysis. By systematically evaluating mean, minimum, maximum, and deviation length scales, along with perimeter and area metrics, the authors identify independent scales and define 11 non-dimensional shape descriptors. Among these, three descriptors—$b/a$ (aspect/axial ratio), $\langle e\rangle/D_p$ (average contact eccentricity), and $\pi D_p/P$ (2D sphericity proxy)—emerge as uncorrelated and highly informative across all materials and size ranges, enabling robust characterization for DEM simulations and bed packing analyses. The results show pellets are nearly spherical while sinter and lump ore display pronounced non-sphericity, with implications for blast furnace operation and modeling of granular flow and packing.

Abstract

In this study, we attempt to characterize the shape of three different types of grains commonly used in the iron and steel-making industry, namely pellet, sinter and iron ore lump. We choose particles over the entire size ranges used in industrial-scale blast furnace and consider two different size ranges of pellet particles and four different size ranges for sinter and iron ore lumps. We perform image analysis to calculate size and shape-related properties of the grains. We select some of the common length scales used to measure the size of the particles and categorize them in different classes. We show that the length scales of a particular category class are well correlated with each other. We identify the independent, uncorrelated length scales for the particles from different categories. Using these uncorrelated length scales, we define different shape descriptors and obtain the distribution of these shape descriptors for each component of the blast furnace feed. Our image analysis results show that the cumulative distribution curves for these shape descriptors turn out to be nearly independent of the size range for a given type of material. Our study identifies the three key shape descriptors that are required to characterize the shape of the blast furnace feed. Two of these shape descriptors, namely the aspect ratio and the circularity, have been considered important by the researchers earlier as well. The third shape descriptor, the average contact eccentricity to the projected particle diameter ratio, usually not considered to be an important shape descriptor in previous studies, is of high relevance for Discrete Element Method simulations of granular materials.

Figures (24)

• Figure 1: (L-R) Pellets, sinter and iron ore lumps.
• Figure 2: Schematic describing the methodology used for 2D image analysis.
• Figure 4: Relationships between mean length scales. All units in mm. Rectangular box shows the sieve size limit and the solid line corresponds to $y=x$ line.
• Figure 5: Cumulative distribution of $D_p$ (mm). Broken vertical lines show the sieve size limits.
• Figure 6: Relationships between minimum length scales. All units in mm. Solid line shows the $y=x$ line.