SULPHUR DISTRIBUTION BETWEEN LIQUID IRON AND CaO-MgO-Al2O3-SiO2 SLAGS USED FOR LADLE REFINING.

Abstract

In order to obtain the equilibrium data about the ladle desulphurization of liquid steel, experiments have been done to measure the sulphur distribution between liquid iron and CaO-MgO-Al//2O//3-SiO//2 (SiO//2 equals 0 approximately 20 wt%) slag of calcium aluminate base in a magnesia crucible at 1 575, 1 600 and 1 650 degree C. The transfer of sulphur between liquid iron and slag is slower than the dissolution of magnesia from the crucible into slag, and it takes more than 4 hr to attain the sulphur partition equilibrium. The sulphide capacity (C//S) of slag and the sulphur partition ratio (L//S) between liquid iron and slag can be expressed by the following equations as functions of temperature, slag composition and theoretical optical basicity ( LAMBDA ). log C//S equals 3. 44(N//C//a//O plus 0. 1N//M//g//O minus 0. 8N //A//l//2//O//3 minus N//S//i//O//2) minus 9894/T plus 2. 05 log C//S equals 14. 20 LAMBDA minus 9894/T minus 7. 55 log L//S equals 3. 59(N//C//a//O plus 0. 1N//M//g//O minus 0. 8N //A//l//2//O//3 minus N//S//i//O//2) minus 0. 905 log N//F//e//O minus 4640/T plus 0. 385 The validity and applicability of these equations have been discussed in comparison with the data reported by the other investigators.