Dissolution Rate of Al2O3 into Molten CaO-SiO2-Al2O3 Slags.

Abstract

The dissolution rate of Al 2 O 3 into the CaO-SiO 2 -Al 2 O 3 slag system was investigated at 1 873 K by employing a novel experimental method which involved continual measurement of the torque variation on a rotating alumina rod dipped into a molten slag. Measured torque variation was successfully related to the dissolution rate of the rod. The dissolution rate of alumina was found affected by a number of factors: the rate increased with increasing temperature, the rotating speed of the rod, the CaO content in the slag, and the Al 2 O 3 content in the slag for a fixed CaO content. It was found that the dissolution rate was highly dependent on the viscosity and the diffusivity of slags. The activation energy obtained from an Arrhenius type analysis was in the range of 84 kJ mol Ϫ1. It was concluded that the dissolution of Al 2 O 3 into the CaO-SiO 2 -Al 2 O 3 slag system was controlled by the mass transfer in the slag phase. An iso-dissolution rate diagram was constructed for the dissolution of Al 2 O 3 into the CaO-SiO 2 -Al 2 O 3 slag system at 1 873 K.

Dissolution Kinetics of Alumina into Mold Fluxes for Continuous Steel Casting

“…5) The mass transfer of alumina in liquid slags was found to be the rate-limiting step of the dissolution process. 4,6,7,11) The present study aims to examine dissolution kinetics of alumina into a mold flux for the continuous steel casting by employing the rotating cylinder method. Mold flux compositions are based on a CaO-SiO 2 -Al 2 O 3 system and additives such as MgO, CaF 2 and Na 2 O.…”

“…1,2) Dissolution of oxides including alumina in molten slag/flux has been studied by several researchers. [3][4][5][6][7][8][9][10][11] It was reported that the dissolution rate of alumina is influenced by many factors, e.g. viscosity of liquid slag, 7) temperature, 11) convection flow 4) and so on.…”

A New Experimental Design to Study the Kinetics of Solid Dissolution into Liquids at Elevated Temperature

“…They reported that the dissolution rate was not affected by the porosity of the sample. Choi et al [10] investigated the dissolution of Al 2 O 3 in the CaO-SiO 2 -Al 2 O 3 slag system. The torque of the rotating alumina rod dipped into liquid slag was found to be related to the dissolution rate.…”

“…[10,[16][17][18] To determine whether the dependence of the dissolution on rotation rate is actually due to the slightly misaligned rod or the oscillation of the rod would need careful study of the experimental setups. However, some researchers reported that the dissolution rate could also be controlled by other mechanisms.…”

“…THE rotating disk/cylinder (rod) method has been widely applied to study the dissolution of solids in liquids for decades, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] in particular for high-temperature systems such as dissolution of solid metals into liquid metals, and dissolution of ceramic solids into liquid oxides (slags). While valuable information have been gained by these studies, some misconceptions in using this method need to be addressed and analyzed.…”