Utilization Rate of Magnesium in Hot Metal Desulfurization by Magnesium Vapor Injection

Abstract

To solve the technical problems such as serious splashing and low utilization rate of the desulfurizer in the traditional hot metal desulfurization by granular magnesium injection, a new idea of hot metal desulfurization with continuously controllable bottom blowing magnesium vapor is presented in this paper. An estimation model of the utilization rate of magnesium vapor was established based on the double-film theory, which shows that the utilization rate of magnesium vapor decreases with the increase of the flow rate of the carrier gas, and increases significantly with the decrease of the bubble radius of the magnesium vapor. The theoretical calculation results show that when the desulfurization temperature reaches 1 573 K and the bubble radius of the magnesium vapor is refined to 0.175 mm, the residence time of magnesium vapor in the molten iron is equal to the reaction time, and the theoretical utilization rate of magnesium vapor can reach 100%. The model was validated by high temperature experiments using bottom blowing method. The experimental results indicate that the utilization rate of magnesium vapor in the desulfurization process is inversely proportional to the desulfurization temperature, the flow rate of the carrier gas and the mass of magnesium injection. Under the condition of 1 573 K, the mass of hot metal 4.5 kg, the flow rate of 3 L/min and the injection mass of magnesium 1.55 g, the utilization rate of magnesium vapor can reach 83%. The calculated results of the model are well matched with the experimental data. KEY WORDS: hot metal desulfurization; bottom blowing magnesium vapor; utilization rate of magnesium vapor; model of the utilization rate of magnesium vapor.

A novel soft sensing modelling approach for sulphur content estimation in hot metal pretreatment process

“…Sulphur is usually considered as one of the main impurities in hot metal, and injecting magnesium powder is a common technology to achieve desulphurisation. 22 The schematic picture of the process of desulphurisation by Mg injection is shown in Figure 1. Magnesium metal has a strong affinity for sulphur, and its melting point and boiling point are relatively low.…”