A study of the slag-induced wear of the refarctories made from magnesia-spinellid bodies with an argillaceous binder

Abstract

The application of the out-of-furnace treatments of steel (vacuum degassing, adjusting the chemical composition, treating with synthetic slags, injecting powdered reagents, etc.) requires basic refractory materials for lining the molten steel-containing ladles [i]. In view of the fact that mechanized ramming is the most promising among the refractory lining operations involving mechanization and automation, it is necessary to introduce a plasticizer into the body compositions [2-4] so as to ensure satisfactory formability of the body and mechanical strength of the lining after ramming and drying. Refractory clays and bentonite are the most frequently used inorganic plasticizers.An important quality index of the lining is its ability to resist the destructive action of the slags accidentally falling into the ladle along with the metal from the steel making furnace and the slags specially introduced into the ladle for treating the molten steel. It was previously shown [5] that the degree of chemical destruction of the magnesia-spinelled refractories that are in contact with calcareous alumina melts is determined by the silica content in the original refractories. During the first stage of interaction of the melt penetrating into the refractory with the phases constituting the refractory, dissolution of silica-bearing (siliceous) phases takes place; gehlenite is the main product of crystallization of such a melt. Subsequently, periclase dissolves in the melt as indicated by the melt. Subsequently, periclase dissolves in the melt as indicated by the presence of the melilitegroup minerals in the zone of slag formation.A study of the slag-induced wear (erosion) of the basic refractories established the positive effect of the increased content of direct bonds of periclase-periclase, periclasechromite, and chromite-chromite (without intermediate silicate layers) on the resistance of the refractories [6]. This paper deals with the determination of the stability of various silica and aluminabearing phases in a synthetic slag environment and a study of the slag-induced wear of the magnesia-spinellid systems containing an argillaceous binder that are in contact with the synthetic slag and with a i:i mixture of the synthetic and the converter slags. The magnesiaspinellid mixture forms the main (basic) component of the bodies. In order to evaluate the resistance to the synthetic slag, we introduced 25%* fused and sintered magnesia-alumina spinels, electrocorundum, alumina fired at 1200~ forsterite, mullite, and tricalcium and dicalcium silicates. Bentonite and the Latnensk and Novoraisk refractory clays were used as the inorganic plasticizers. Table 1 shows the chemical composition of the original (raw) materials and the slags.Crucibles measuring 25 man in diameter and 20-25 n~n in height were compacted from the magnesia-spinellid mixtures containing 25% additives at a presssure of 10 MPa. A synthetic slag pellet was placed in the opening of the crucible; the refractory:slag ratio was maintained at 3:1. Along with the slag, th...