Modeling and simulation of green iron ore pellet classification in a single deck roller screen using the discrete element method

Abstract

Bed permeability is a critical parameter in induration of green iron ore pellets in travelling grate furnaces. Its control and optimization must be pursued in order to achieve higher productivity, lower fuel consumption and higher quality and uniformity of fired pellets. One important method of improving bed permeability is to strictly control the size distribution of green pellets prior to feeding the induration furnace. Given the limited control that exists in the sizes of pellets that leave pelletizing drums or discs during balling, size classification by screening becomes of central importance. The work analyzes the performance of the main type of screen used in classification of green iron ore pellets, the roller screen, through simulations using the discrete element method. Recognition of the sticky nature of the material led to the choice of the Hertz-Mindlin model with JKR cohesion to describe the contacts. Material characterization tests were conducted that resulted in the estimation of detailed material and contact parameters for simulation. Finally, simulations using the discrete element method were used to analyze the sensitivity of the roller screen performance to selected material and operating variables.