Behaviour of Ar-1%Mg Bubbles in Desulfurization of Hot Metal by Magnesium Injection

A mathematic model for an argon bubble containing magnesium vapour in hot metal was developed for interpreting the desulfurization process by injection of granulated magnesium. The change of rising velocity, pressure, size and magnesium vapour content of the bubble and the rates of desulfurization, deoxidation, magnesium dissolution by the bubble were investigated with the aid of the model. Most of the magnesium vapour in an argon bubble is consumed by the reaction with hot metal while the bubble is rising from 3.5 m depth in hot metal to the bath surface. The magnesium vapour content in the bubble decreases to a minimum halfway on the bubble's rising and slightly increases thereafter as the bubble approaches the bath surface. During the initial or middle stages of the injection process, magnesium vapour in a gas bubble is mainly consumed by the desulfurization and deoxidation of hot metal. During the final stage or within the active zone of the process, magnesium dissolution into hot metal and unreacted magnesium vapour in the bubble arriving at the bath surface become significant.