Granular size segregation in sintering packed beds: Insights into balancing permeability and high-temperature performance

Abstract

Sintering is an energy-intensive and high-emission process critical to ironmaking, contributing approximately 289.1 million tons of CO₂ emissions annually. Improving the permeability of the sintering packed bed can enhance sintering efficiency and reduce energy consumption. Among various technical measures, optimizing the operational parameters of granules chargers has proven to be an effective and straightforward approach. However, previous studies have not addressed a key issue: how to balance permeability with the overall sintering process performance. To address this gap, this study develops an eleven-roller charging model and employs the Discrete Element Method (DEM) to simulate and analyze granular segregation in the entire sintering process. The effects of operational parameters, such as roller speeds and angles, on segregation are systematically investigated. Cold-state permeability experiments are conducted to evaluate the permeability of granular packed beds, while high-temperature sintering cup experiments determine the optimal segregation level for superior sintering performance. Computational fluid dynamics (CFD) simulations further reveal that changes in bed porosity play a crucial role in sintering performance. The results indicate that reducing roller speed increases particle velocity differences, enhancing segregation and improving packed bed permeability. Adjusting the roller angle also significantly affects permeability. High-temperature sintering cup experiments show that, under present conditions, a segregation ratio of 5 % optimally balances permeability and sintering efficiency, and the vertical sintering rate increases from 16.5 mm/min to 19.2 mm/min, and productivity improves from 1.30 t/m²·h to 1.60 t/m²·h, significantly enhancing overall sintering performance.