Improved Modelling of the Cohesive Zone of an Ironmaking Blast Furnace
The high temperature zones in the ironmaking blast furnace are complex due to the number of phases and phenomena involved. The liquid phases –iron and slag- are formed in the cohesive zone and then descend through the moving coke bed, interacting with the ascending gas and coal powder phases. An analysis of the literature reveals that although there are a variety of overall blast furnace mathematical models, there is a shortage of investigations focusing on cohesive zone phenomena and its effect on the gas and liquid distribution. Improvements were made to BlueScope Steel's blast furnace model "SHAFT". Among the changes performed on SHAFT, actual iron ore burden softening-melting data was fed and latent heats of melting were introduced for the three burden species present at cohesive zone level (iron, gangue, wustite). A pseudo-layered cohesive zone was also introduced by means of a new fraction which measured the relative heights of the coke and the softening ore layers. This enabled the separate calculation of convective heat transfer between gas-coke, gas-ore and across the softened ore-coke layer interface.