Removal of Inclusions Using Micro-bubble Swarms in a Four-strand, Full-scale, Water Model Tundish

Abstract

Water model experiments were performed in a full-scale, delta-shaped water model tundish, in order to study the removal of inclusions by micro-bubbles. Micro-bubbles were generated using a specially designed ladle shroud with twelve laser-drilled orifices. Gas flow rates, injection positions and multi-port injection were all taken into consideration to create different bubble conditions. Bubbles were recorded using a high speed camera and post-processed with commercial software, Image J. Hollow glass borosilicate microspheres, smaller than 100 μm, were used to simulate inclusions, and detected, in-situ, using a new generation of the Aqueous Particle Sensor, APS III. The results revealed that the effect of microbubbles on inclusion removal depends greatly on the gas injection protocols used. The optimum gas flow rate was an intermediate value, which indicates a minimum particle number density, n p , of about 7.85/ml. This results from the counter-balancing effects of bubble sizes against the total number of bubbles. The highest inclusion removal rate was 80%, when gas was injected through the four ports located closest to the slide gate, at a gas flow rate of 0.2 L/min.

“Vacuum Shroud (VS)”-A Green Flow Control Device (FCD) towards Replacement of “Turbo Stop” In Tundish Metallurgy

“…Full scale dimensions for different pouring nozzle were used and water, kerosene oil, air, argon were used as a simulating fluid as a representative of liquid steel and slag as the kinematic viscosity of the water and liquid steel are same respectively. 10 mm argon particles were injected for current study and the inclusions diameter was taken 50µm as this is the critical diameter of inclusion for generating sliver complaint in steel semi finished product [30]. The details dimensions and operating parameters are explained clearly in Table 1.…”

“…So it is highly desirable to judge the inclusion removal efficiency of different types shroud and impact pad combinations. As 50µm is the critical diameter of the inclusions as mentioned literature [30]. So it's floatation characteristics from stokes law were evaluated in current study.…”

Fluid Flow and Heat Transfer in a Tundish with Channel Type Induction Heating

“…1) The low‐melting‐point metal, such as mercury, is toxic to humans. 2) The low melting point metal is not transparent, it is difficult for us to observe the transfer process. Compared with low‐melting‐point metal model, water model has the advantage of low cost, convenient operation, and safety . It should be noted that it is difficult to study the electromagnetic characteristics because of its low electrical conductivity.…”

Modeling Slag Behavior When Using Micro‐Bubble Swarms for the Deep Cleaning of Liquid Steel in Tundishes

“…Nowadays, with highly developed tundish designs and flow controllers, most of the inclusions larger than 50 µm can be floated up, and be absorbed by an upper slag layer. For enhanced cleaning of the liquid steel, submerged gas bubbling within the tundish has been employed, in order to enhance the removal of inclusions smaller than 50 µm, either through attachment to the bubble surfaces, or being captured in a bubble's wake …”