Ways to increase the slag resistance of unfired siliceous articles for teeming ladle linings

Abstract

Based on laboratory investigations and industrial tests, the expediency and efficiency of using unfired siliceous articles produced with addition of milled chromite to a quartz charge for linings of slag belts of teeming ladles is established.Teeming ladles are laid for the most part with chamotte articles produced by various refractory enterprises [1]. The lining of teeming ladles is often made of quartz-clay and sand-clay ramming mixtures applied by sandblasters; the binder is commonly liquid glass and orthophosphoric acid [2 -6]. In recent years teeming ladles, including those for out-of-furnace treatment of steel, are laid with basic refractories, namely, fired and unfired forsterite-containing articles, chromite-periclase articles, and periclase-spinellide articles [7 -11 ]. The endurance of the lining of the slag belt of a teeming ladle made of these refractories exceeds that of chamotte and high-alumina refractories by a factor of 2 -3.The Pervouralsk and Krasnoarmeisk Dinas Plants have organized production of unfired siliceous ladle articles based on a quartz charge and liquid glass [12]. The endurance of a lining made of unfired siliceous ladle articles used for casting converter steel is 20 -25 pourings with intermediate repair of the lining of the slag belt after 12 -15 pourings.The present article presents results of an investigation aimed at increasing the slag resistance ofunfired siliceous ladle articles. In laboratory experiments we tried to reach this goal by introducing widely available additives into the quartz charge while maintaining the high properties of the refractories required for operation in teeming ladles. For comparison, we prepared specimens from the charge used by the Krasnoarmeisk Dinas Plant for the production of unfired siliceous articles for linings of teeming ladles (charge 0).In order to eliminate the effect of fluctuations in the ~ain composition of the charges on the properties of the specimens, milled Ovruch quartzite was preliminarily sieved into individual fractions (2 -3, 1 -2, 0.5 -1, and < 0.5 mm), and the charge was additionally mixed with quartzite of a fraction finer than 0.09 mm milled in a tube mill.Ukrainian Research Institute of Refractories, Kharkov, Ukraine.The grain composition of the charge was corrected using specific amounts of different quartzite fractions. It included 15% fraction 2 -3 mm, 25% fraction 1 -2 mm, 10% fraction 0.5-1 ram, and 50% fraction finer than 0.5 mm, 30% of which was f'mer than 0.09 mm.The additives were Kimpersaisk chromite of a fraction finer than 3 mm, Saranovsk chromite of a fraction finer than 0.5 mm, periclase of a fraction finer than 0.09 mm, and scrap of chromite-periclase articles of a fraction finer than 0.5 mm. In order to remove oil and moisture the slurry was preliminarily fired at 850°C. The compositions of the charges with the aforementioned additives are presented in Table 1. In preparing the siliceous mixtures 7.5% (above 100%) liquid glass