Effects of Blast Furnace Main Trough Geometry on the Slag‐Metal Separation Based on Numerical Simulation

Abstract

The complete separation of hot metal from slag is expected in the main trough of a blast furnace. However, in practice slag may take some hot metals away when it goes through the slag port. Therefore, it is important to optimize the slag‐metal separation in order to decrease the metal loss associated with the slag. The present work establishes a three dimensional unsteady model of the main trough of a blast furnace in Panzhihua Steel. The model is then applied to investigate the effects of the width, depth, and bottom slope on the flow behavior and slag‐metal separation. The results show that the high velocity regions and the velocity difference between the hot metal and slag are the main cause of hot metal drawn into the slag. The change of main trough geometry has a major impact on the flow behavior and slag‐metal separation. The slag‐metal separation is improved a lot by decreasing the bottom slope of the main trough or increasing its width. Therefore, it is strongly recommended that the main trough have a horizontal bottom or that its width be increased in order to obtain a better slag‐metal separation.

Numerical Analysis on Erosion and Optimization of a Blast Furnace Main Trough

“…The shear stress on the wall increases with the angle of the skimmer dam. Additionally, using Fluent, Kou et al [9] concluded that the performance of slag-iron separation can be optimized by reducing the slope of the trough and increasing the width of it. Sun et al [10] carried out hydraulic model experiments to analyze the flow state of the main trough with different slopes and found that a smaller slope of the trough gives a longer replacement time of hot metal, fewer temperature swings in the trough and less damage caused by temperature changes.…”

Modeling of Two‐Phase Flow in Blast Furnace Trough

“…As a result, some simplifications are quite common as described by Rezende, [ 11 ] Chang et al, [ 15 ] Wang et al, [ 10 ] Kou et al, [ 16 ] and Geyer and Halifa. [ 17 ] Common hypotheses are as follows: transient gas–liquid flow or else pseudo transient; the phases are continuous and fluids are Newtonians; the flow is isothermal, isochoric, and turbulent; the law of wall approximation remains valid even if two or three phases are present; mass transfer between phases is disregarded and interface tension is constant; and the turbulence models developed for monophasic flow are applicable to multiphase flow.…”

“…Wang et al [ 10 ] and Kou et al [ 16 ] used a numerical approach to describe the flow of hot metal and slag in the BF trough and the separation efficiency. Wang et al [ 10 ] and Kou et al [ 16 ] took into account both heat transfer phenomena and the way liquids are discharged into the runner, to replicate the actual operation.…”

“…Kou et al [ 16 ] pointed out that the high velocity regions are located in the taphole and impact zone. In addition, changing geometric settings such as increasing width and depth or decreasing channel slope reduces turbulence levels.…”