Mathematical Model of Hot Metal Desulphurization by Powder Injection

Abstract

A macro kinetic analysis of the hot metal desulphurization with powder injection has led to that there are three basic parameters which determine the desulphurization rate, as well as the power utilization efficiency. They are the penetration ratio (PR) of injected powder into the melt, the residence time distribution (RTD) of injected powder in the bath, as well as the homogeneous mixing time (HMT) of the bath. Both PR and HMT have been experimentally determined with water modeling, while the RTD has been determined from either flow field information or experimental measurements of water model with stimulus-response method, arriving at the correlation formulas between the parameter and the injection operation variables as well as powder characteristics. This has enabled the development of a mathematical model to predict the desulphurization process.Based on further analysis of the mechanism and macro kinetics of the process, a mathematical model has been developed, with the three basic parameters being taken into account, to simulate the variation of [S] in hot metal with time. Water-model experiment results, flow field information and industrial data are used to determine the model parameters and verify the model, leading to the result that the prediction from the model agrees well with practical results. In addition to CaO and CaC2 powders, the use of granular Mg has been particularly included and emphasized in the model for its more and more popular application. The coupling effect of hot metal desulphurization by injection of magnesium-CaC2 mixture was discussed.