Effects of slag composition and cooling rate on formation of glaze on MgO refractory

Abstract

The formation of a slag glaze layer on dense and porous MgO rods was studied by dipping MgO rods into liquid slag at 1873 K and thereafter cooling the rods at a predetermined cooling rate. Three different slag compositions and three different cooling rates were employed. It was found that the phases formed upon cooling were mostly dependent on slag composition and to a minor extent on the cooling rate. The initially liquid slag was transformed into crystalline phases for all the samples except the ones terminated at 1573 K and one of the samples with high cooling rate. In addition, the three slags were equilibrated at 1773, 1673 and 1573 K in order to get an understanding of the equilibrium phases and their relationship during cooling. On the basis of the experimental results, the mechanism regarding entrainment of exogenous inclusions from the refractory lining was also discussed.

Effect of ladle slag of previous heat on number of non-metallic inclusions in ladle treatment of tool steel

“…In recent studies, 15,16 the solidification of ladle glaze and the precipitation of solid particles in the ladle slag system were investigated. Four phases were mainly detected in the glazed refractory, which was in contact with the slag.…”

“…In the next heat, more non-metallic inclusions could be generated from the accumulated slag being washed out from the ladle pores. In fact, based on their experimental study, 16 the authors have shown the formation of cracks, and dusted slag occurs with high SiO 2 content slag, i.e. 12 or 15 mass-%SiO 2 .…”

Influence of final stirring treatment on inclusion number in tool steel

“…Doostmohammadi et al 2 have compared two and three dimensional methods for inclusion determinations. Song and co-workers [3][4][5][6] have studied the influence of ladle glaze on the inclusion characteristics. Bjo ¨rklund et al 7 have studied the effect of ladle treatment on the inclusion composition.…”

The structure of foaming BOF-converter slag

“…All slag compositions were successfully foaming, but unfortunately, slag 1 and slag 5 pulverised almost spontaneously after solidification, probably due to their high CaO/SiO 2 ratio which led to dusting of the slag [25]. Only the heights of these foams could be measured, while attempts to collect other information were not successful.…”

“…A concept of foaming index was introduced [8] to describe the foaming height using the retention time of gas passing through the slag. Although the foaming index has been used widely in the steel industry, researchers have also found that some slags deviate from the index equation [22,25]. Millman et al studied the refining process in an experimental converter, and at the same time slag foaming.…”