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Effect of Modeling Flows on Mixing Time in 40t Ladle with Bottom Gas Blowing Process

Le Wang, Liu Liu and Bingji Yan

Abstract Base on the generalized similarity principle, water model experiments had been conducted to investigate mixing phenomena of argon injection from the ladle bottom with eight types of tuyere arrangement. In this research, the harmonic number (H0) was considered as an evaluating indicator and four variables were mainly investigated, which were the blowing position, aspect ratio, Froude number and gas flowrate. All of these parameters were dimensionless. Furthermore, A fitting equation was newly proposed for mixing time as a function of four influencing factors. As a result, It was showed that the arrangement of tuyeres has a great effect on mixing time in the ladle and a placement of single tuyere at 2/3R away from the bottom center gave the shortest mixing time.

Keywords Steel ladle Water modeling Influencing factor Mixing time

Introduction

Secondary steel making is today a very important practice in the steel industry because of stringent quality demands regarding steel cleanliness. In the ladle, typically an insert gas like argon is purged through a porous plug or two porous plugs fitted at the bottom to circulate the steel. Gas bubbling in ladles is used to obtain chemical and thermal homogenization, as well as to accelerate the absorption of harmful nonmetallic inclusions into an overlaying slag, etc. [1-4]. Mixing time is a very important parameter in this regard because reducing the mixing time improves the efficiency of the process. It is meaningful to study the mixing phenomenon in ladle refining by water modeling.

L. Wang (H) • L. Liu

Center of Iron and Steel Research Institute, Beijing, China e-mail: This email address is being protected from spam bots, you need Javascript enabled to view it

B. Yan

Soochow University School of Iron and Steel, Suzhou, China © The Minerals, Metals & Materials Society 2017

A. Allanore et al. (eds.), Materials Processing Fundamentals 2017,

The Minerals, Metals & Materials Series, DOI 10.1007/978-3-319-51580-9_11

Helle proposed [5] an empirical formula by dimensionless analysis, which showed the relationship between the mixing time and the ladle bottom diameter, the liquid depth, surface tension. According to them, the equation developed in this study for the circulation of the mixing time required during gas rinsing could be used with sufficient accuracy for production purpose.

Some researchers had reported on the various factors which influence mixing time [6]. They were ladle aspect ratio (H/D), presence of upper buoyant phase (slag), nature of motion of the liquid phase, purging location and tracer addition point. Trukoglu and Farouk had demonstrated that both vessel aspect ratio and gas injection play crucial roles in the flow structure in the bath and hence affected mixing time [7].

The purpose of the present research was to study the mixing characteristics in gas injected molten metal baths. The effects of vessel aspect ratio (H/D), the tuyere positions, the flow rate and liquid-gas density ratio on the mixing efficiency were investigated. We carried out water model experiments and proposed an equation for the mixing time.

 
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