Influence of synthetic primary slag on fracture of kaolin refractories for blast-furnace stacks

Abstract

The service life of refractories in a blast-furnace stack is 3.5-4 years, whereas in the hearth and hearth bottom it is from 10 to 12 years [1]. This means that an increase in the period between stack repairs is an urgent problem which requires a tLmely solution.The durability of the stack lining depends on the composition of the primary slags, the amount of alkalies and zincite in the blast-furnace charge, the composition of the gaseous medium, the abrasive wear by the charge, the thermal stresses, and the conditions under which the furnace is operated, its design, and other factors [2].The specific influence exerted by each of these factors on the durability of the lining differs from one factory to another. This complicates the creation of a universal refractory with all the necessary properties and makes it difficult to establish the most important characteristics governing the stability of artifacts during service. For this reason, there is no agreement concerning the selection of refractories for blastfurnace stacks; however, laboratory and factory investigations have shown that compact kaolin refractories with an A1203 content of 42-45% are promising materials for the lining of the cooled part of the stack.Compact kaolin artifacts with a porosity of less than 12% are being manufactured at the Zaporozhe Refractory Works and the Chasov Yar Refractory Artifact Works, and chamotte artifacts with a porosity of

Main causes of refractory wear in the shaft of a blast furnace and means of improving the resistance

“…One of the chief sources of contamination is secondary oxidation of the metal during pouring. At present in continuous casting the stream of metal is protected only in the section from the intermediate ladle to the crystallizer [1], while in the section from the steel-pouring ladle to the intermediate ladle it is open and thus subject to the action of the air.…”

“…The increased stability of conditions has increased the demands for better refractories. The problem of the next five-year plan is to increase the average resistance of the shift refractories to 9-10 years, and in the bosh and hearth to 18-20 years [1]. On the basis of a study of the operation of refractories in the blast furnace structure and postserviee studies it was established that the resistance depends on a combination of many critical factors [2][3][4][5][6][7][8].…”

“…To make the refractory tubes, the same materials have been used as for immersible nozzles --quartz ceramic and a composite of alumina with graphite [1]. Like immersible nozzles, the quartz tubes are used to pour nonmanganese steel, and the alumina--graphite ones for manganese steel [13,21,27].…”