Influence of coke breeze positioning on the sintering behavior of pellets and raw material bed with embedded pellets

Abstract

The influence of coke breeze positioning on the sintering behavior of pellets and raw material bed with embedded pellets was investigated. With increasing the coke breeze ratio in the green pellet made from ore and coke mixture fine of -125 μm, the tensile strength of the green and dried pellets decreased. Based on the evaluations under the green and dried pellet equations concerning particle bond, it was presumed these results were caused by the decrease in the contact points between particles due to the reduction of mixture fine's specific surface area. With increasing the coke breeze ratio in the nucleus pellet, the tensile strength of the burned pellets also decreased. From the change in the porosity up to 900° C, sintering was predominant to the tensile strength. In the temperature from 900° C to 1 200° C, the increase of strength became small by adding coke breeze in the nucleus pellet. It was presumed this result was caused by remarkable increase of void after coke combustion. In the sintering of raw material bed with embedded the coke breeze coating pellet, the surrounding temperature of pellet increased and the large void was generated below the pellet. Based on the 2-dimensional numeric evaluation, it was found the heat amounts of the pellet and gas heated by coke combustion were transported to the region under the pellet where the gas flow rate was low. It was considered this heat concentration caused the remarkable melting and large void formation.