Effect of Flux Dispersion Behavior on Desulfurization of Hot Metal

Abstract

In order to improve the efficiency of the desulfurization process utilizing the mechanical stirring method, the effect of flux dispersion on the hot metal desulfurization reaction was investigated in 1/8-scale water model and 70 kg-scale hot metal experiments.Flux dispersion behavior is divided into three stages, i.e., "non-dispersion," "transition," and "complete dispersion." The desulfurization rate increases remarkably from the "non-dispersion" to the "complete dispersion" stage, corresponding to the change in the condition of particle dispersion.The relationship between the impeller position and the vortex depth is defined as the dispersion index, I. When the dispersion index was over 1, complete dispersion occurred in water model experiments, and the apparent rate constant increased remarkably in hot metal experiments.The observed diameter of the desulfurization slag was 1.4 mm, which is in good agreement with the calculated value, 1.55 mm. This means that fine desulfurization flux aggregates immediately after the addition of the flux. In order to increase desulfurization efficiency, it is important to control this particle aggregation.

Solid/liquid Mass Transfer Correlated to Mixing Pattern in a Mechanically-stirred Vessel

“…It was kept nearly constant at lower level in the region I, monotonically increased in the region II except near the region III and its increasing rate decreased in the region II near the region III. However, there is few cold model investigation on the effect of solid/liquid mixing pattern on solid/liquid mass transfer rate with particles lighter © 2014 ISIJ than liquid, with the exception that Nakai et al 12) studied a relation between solid/liquid mixing pattern by cold model experiment and desulfurization rate by hot model experiment.…”

An Evaluation of Gas Injection Effects in a Mechanically Stirred Hot Metal Desulfurization System

“…Fluid dynamics behavior on a stirred tank depends on different factors, such as impeller rotation speed, gas flow rate, impeller depth, gas injection position and others [2,9,10]. Even so, no remarkable difference is noticed when gas flow rate increases, Figure 3 and Figure 4.…”

“…Due to centripetal forces considerable amount of gas dispersed inside the melt is pushed towards the longitudinal axis and then some is trapped in a conical shape underneath the impeller, Figure 5. Air from the atmosphere can be sucked to this position specially at higher impeller velocity and smaller impeller depth of immersion [9]. Thus inert gas can be used to flush out the air avoiding metal contamination.…”

Simulation on Mixing Behavior of Desulfurizer and High-sulfur Hot Metal Based on Variable-velocity Stirring

“…Shiba et al 7) investigated the operation parameters and the structure parameters on the constant-velocity KR desulfurization process, and Nakai et al 8) changed the velocity and the depth of impeller in order to understand the effect of particles dispersion in KR mechanically-stirred vessel under the constant-velocity stirring method. Wu et al, 9,10) Liu et al 11) decreased the mixing time and developed the efficiency of the desulfurization by adopting different rotation modes under the other refine process.…”