A high-alumina mass for gunniting the lining of steel-casting buckets

Abstract

Aluminosilicate masses are currently being widely used for gunniting the linings of steel-casting buckets [1][2][3].In the No. 1 oxygen converter shop of the Novolipetsk Metallurgical Plant (NLMP), steel of several grades is cast from buckets with a tamped silica--alumina lining while the pipe grades of steel are smelted using synthetic slag and are cast from buckets with a highalumina tamped lining [4][5][6].The composition of the masses for gunniting the tamped high-alumina lining were selected from high-alumina chamottes, with an A1203 concentration of ~58, 72, and 85%.* Chamottes with an A1203 concentration of e 58 or 72% were obtained by firing the natural raw material; chamotte with ~85% of alumina, by firing a mixture of industrial alumina with LTI clay.The chamotte with an A1203 concentration ofe58% consisted of 40-45% of fired kyanite with fine-crystal mullite precipitated on its grains. Mullite in amounts of 10-12% was also present in the form of well-crystallized aggregates.The mullite crystals of prismatic shape with a predominant size of 4 x 20 to 8 x 40 Hm were cemented by a brown, glassy substance.Corundum in amounts of 6-8% wasencounteredinthe form of colorless or gray aggregates of irregular form with a predominant size of 10-60 ~m.The mineral composition of the chamotte with a concentration of AI20~ ~72% AI20~ was 65-70% mullite in the form of prismatic isometric colorless grains of 4-12 ~m, and occasionally of prismatic crystals up to 40 Dm in length; 17-20% of corundum in the form of isometric colorless grains measuring 8-20 ~m; and 12-15% of cryptocrystalline and glassy materials forming films between the mullite and corundum grains which were also encountered in the form of independent clusters with a refractive index from 1.560 to 1.620.The chamotte with the A1203 concentration ofm85% had the following mineral composition: 60-65% of dispersed mullite and a cryptocrystalline material; 30-35% of corundum in the form of isometric grains of 1-4 ~m; 1-2% of a glasslike material mainly in the spaces between the mullite and corundum. Huilite was observed also in the form of prismatic and acicular crystals with maximum size of 4-8 x30-40 ~m.The masses for study were prepared from 70% high-alumina chamotte (coarse-grained component of <2.0 mm) and 30% of a mixture from the combined milling in a tubular mill of white *Mass fractions are indicated in this paper in the case of the chemical, grain, and material composition;for the mineral composition, volume fractions are given.