Thermodynamic analysis of the conditions of deoxidation and secondary treatment of low-silicon steel grade

Abstract

This article is concerned with analysis and production testing of technological solutions aimed at reducing the consumption of aluminium for steel deoxidation and reducing level of metal contamination by oxide non-metal inclusions, as well as preventing silicon reduction during out-of-furnace treatment. The conditions of low-silicon steel deoxidation and out-of-furnace treatment have been analysed. It has been found that the scope of oxygen activity variation in the converter before tapping increases while the mass fraction of carbon in the metal decreases. For the converter meltings with a mass fraction of carbon over the range 0,05-0,07 % [C] before tapping the real range of variation was 150-300 ppm. The effect of meltings carburizing on aluminium consumption and the degree of aluminium assimilation have been analysed. It has been shown that in fact the same specific consumption of ferromanganese and comparable changes within the metal oxidation change range before tapping (400-1100 ppm) the addition of the carburizer decreases the consumption of aluminium by 0,15 kg/t (in amounts of pure aluminium). The variation interval of assimilation degree of aluminium, consumed for binding the dissolved oxygen in metal and for dissolution in metal has been found. It has been shown that in the melting of low-silicon steel with out- of-furnace treatment but without the use of furnace-ladle unit the rational limit of variation of mass fraction of magnesium oxide variation in the ladle slag is equal to- 6-8 % by weight