Determination of thermophysical properties for molten slags by maximum bubble pressure method

摘要

The knowledge and precise experimental determination of material properties such as density and surface tension for molten slags and fluxes is necessary in industrial steel making processes, e.g. correct simulations of metallurgy casting processes, mathematical modeling of emulsification between steel and slags and computer fluid dynamics. Thermophysical properties of slags are dependent upon temperature and their chemical compositions. Due to the introduction of new steel grades produced in metallurgical plants also new slag related systems were developed. For investigations on these slag systems and their behavior of absorption for nonmetallic inclusions from steel bath right thermophysical properties have to be determined for these systems. Furthermore mold powders are used in continuous casting processes whereby the material properties also affect the efficiency of the casting and the steel cleanness of the semi-finished goods. For estimation of these values the maximum bubble pressure method was introduced at the Institute of Iron and Steel Technology at Technical University Bergakademie Freiberg, Germany, were measurements are done in the melts without contact to ambient atmosphere. The method was now adapted in this work for the measurement of molten slags and industrial mold powder slags. First in the experimental work a binary system with 50 wt. % CaO and 50 wt. % Al2O3 and a synthetic CaO-SiO2 system with different SiO2 content were investigated followed by an industrial CaO-SiO2-Al2O3 blast furnace slag system. Moreover investigation on industrial available mold powder slags with high transient CaF2 (14 wt. %) content were initiated with step wise reduced Na2O content. The results for density and surface tension were discussed in relation to the chemical composition and temperature of the melts.