Removal behavior of inclusions in molten steel by bubble wake flow based on water model experiment

Abstract

In order to make clear the mechanism how the non-metallic inclusions were removed by bubble wake flow in the molten steel, water model experiments were conducted by high speed video and image processing software. The bubble wake flow zone was partitioned and the characteristics of removing inclusions through bubble wake flow were analyzed, and the effects of various factors including bubble size, inclusion size and concentration on the removal behavior of inclusions were also investigated. The results show that the bubble wake flow is useful for the floatation of inclusions. The bubble wake flow involves the boundary zone and the rising zone, and the process of inclusion removal by the bubble wake flow can be decomposed into three sub-processes: firstly approaching and passing into the boundary zone, secondly passing into the rising zone and finally going on floating up or escaping from the rising zone. The increasing of the bubble diameter Db and the particle concentration Cp is in favor of inclusion removal by bubble wake flow. If the particle diameter Dp is smaller, the inclusions are easier to be removed by wake flow. © 2014 ISIJ.