Model experiments on mass transfer in ladle metallurgy

Abstract

Model experiments on mass transfer in gas-stirred ladles were carried out in reactors of different geometric dimensions. The model system consists of: water, cyclohexan as model slag, iodium as element to be extracted from water into slag phase, and compressed air as stirring gas. The experimental results show that when using an eccentric bottom nozzle, rate constants of mass transfer are always smaller than with centric gas injection. Centric stirring leads to comparatively larger increases of rate constants if a certain gas flow rate is exceeded. Both results can be explained by different emulsification conditions of slag phase. Theoretical calculations of residence times show that mainly the emulsification of small droplets taken along by the recirculation flow is responsible for accelerations of mass transfer in gas-stirred ladles. Modellversuche zum Stoffubergang in der Pfannenmetallurgie. Modellversuche zum Stoffuberqanq wurden in Reaktoren unterschiedlicher geometrischer Abmessungen durchgefUhrt. Das Modellsystem besteht aus: Wasser, Cyclohexan als Modellschlacke, Jod als zu extrahierender Stoff und PreBluft als Ruhrgas. Die Versuchsergebnisse zeigen, daB bei Verwendung einer exzentrischen Bodenduse die Geschwindigkeitskonstanten des Stoffuberqanqs stets niedriger Iiegen als beim Gasruhren mit zentrischer Duse. Nach Oberschreiten einer bestimmten Gasmenge ist beim zentrischen Gaseinblasen ein vergleichsweise starkerer Anstieg der Geschwindigkeitskonstanten festzustellen. Beide Befunde k6nnen durch unterschiedliche Emulgierungsbedingungen der Schlackenphase erklart werden. Theoretische Rechnungen zur Verweilzeit zeigen, daB im wesentlichen die Emulgierung kleiner, von der Umlaufstr6mung mitgenommener Schlacketropfen fUr die starke Beschleunigung des Stoffaustausches in gasgeruhrten Pfannen verantwortlich ist.

Cold Model Study of Emulsification Behavior in Bottom Blown Metallurgical Baths Covered with Thick Slag

“…(1). There are several studies of mass transfer rate in cold systems such as water/oil, [22][23][24] water/benzene, 25) water/clyclohexane, 26) mercury/aqueous and amalgam/aqueous, [27][28][29][30] and melts such as lead/molten salt. 30,31) Considerable amount of knowledge has been accumulated on the overall mass transfer rate between two immiscible liquids, by generally monitoring the transport of a tracer with a specific partition ratio between the two liquids.…”

Promotion of Desulphurization in Ladle through Slag Emulsification by Stirring with Stationary AC Electromagnetic Field

“…On the emulsification phenomena in the case of gas stirring was studied by Mietz et al 1,2) on the critical condition and the size distribution of the entrained particles.…”

Transient Flow and Mixing in Steelmaking Ladles during the Initial Period of Gas Stirring.

“…Numerous physical and mathematical model studies on fluid flow, [1][2][3] slag-metal mass transfer, 4,5) melting, 6,7) dissolution, 8,9) mixing phenomena [10][11][12] etc. in gas stirred ladle systems have been carried out and reported during the last three decades or so.…”

“…Similarly, physical modeling of industrial ladle processing operations were also carried out under steady flow conditions, ensured by blowing the gas through the bath for a prolonged period of time prior to any detailed measurements. [1][2][3][4][5][6][7][8][9][10][11][12] Thus, practically very little or no information on ladle hydrodynamics, under transient flow conditions (which is relevant particularly during the initial as well as the post gas injection period) has been reported in the literature.…”