Spout Eyes Area Correlation in Ladle Metallurgy.

Abstract

In ladle metallurgical operations, it is common practice to use an inert gas for stirring. The stirring is used to achieve homogenization and to pursue chemical and physical changes. The raised region where the gas discharges from the bath during argon stirring is usually called a spout.Where the spout is uncovered by slag, the region is called the spout eye.1) The spout region is significance in industrial practice, since it is an important site for slag-metal reactions and the site of undesirable reactions between metal and air. However, there has been relatively little study to elucidate the phenomena.Recently, Yonezawa and Schwerdtfeger 1,2) reported a comprehensive investigation of the spout region. They studied the phenomena with the objectives to determine the dimensions of the spout and the spout eye. Data were obtained from cold model experiments, by using mercury and silicon oil for simulating metal and slag, respectively, and plant measurements on a 350 t ladle. A video camera was employed to measure the spout formation and spout eye area. For measuring the height of the spout, electroresistivity probes were used for the cold model and the dissolved tube length technique for the plant measurements. The results indicated that spout eye formation and spout eye size are highly dynamic, as a consequence of the discontinuous gas discharge at the nozzle and of the subsequent disintegration into bubbles.Despite their success in measuring spout eyes, both in the cold model experiments and plant trials, they failed to develop an adequate functional correlation between eye area, A es , and operational variables. By employing dimensional analysis technique,

Some Considerations Concerning Empirical Correlations for Plume (Spout) Eye Area in Slag Covered Metalic Melts

“…1. 2) The arguments and analysis presented by Yonezawa and Scwerdtgfeger 1) as well Subagyo et al 2) in support of their empirical correlations contradict published literature as well as theory on several counts and therefore, can be debated. For example, • A large number of investigations carried out till date indicate [3][4][5] that hydrodynamic conditions at nozzle/tuyere are not critical to the overall performance of the gas stirred ladle systems.…”

“…...... (2) It was shown 2) that the preceding relationship, deduced on the basis of a simple regression, describes experimental data 1) regardless of nozzle dimensions, vessel geometry and type of fluids in a unified fashion, relatively more accurately than Eq. (1).…”

“…In a subsequent and more recent study published in this journal, Subagyo et al 2) argued that the dimensionless variable, A es /hH, employed to characterize the surfacing plume eye area earlier, 1) is difficult to justify from a physical standpoint. It was also suggest 2) that the dimensionless correlations, proposed by Yonezawa and Schwerdtfeger, 1) do not unify the plant as well as cold model measurements sufficiently accurately.…”

“…• Subagyo et al 2) 1,2) that the dimensionless parameter, Q 2 /gH 5 appearing in Eqs. (1) and (2) were carried out under different flow conditions, since the range of Froude number (or, Q 2 /gH 5 ) investigated was rather large (e.g., from 10 Ϫ1 to 10 4 , as seen from Fig.…”

“…A need for an unique, physically meaningful and relatively more accurate correlation was therefore advocated by these authors. 2) Thus, Saubagyo et al introduced a new dimensionless variable, A es /(hϩH) 2 and carried out a fresh analysis of the experimental data1 to propose a new empirical correlations between A es /(hϩH) 2 and Q 2 /gH 5 as:…”