Damage of monolithic refractory linings in steel ladles during drying

Abstract

Safety linings of steel ladles are made of high content alumina castable. In situ observations confirm that during drying a network of macrocracks appears in the monolithic castable lining, owing to both dehydration of the cement paste and temperature. Crack formation kinetics have been characterised over the life of the lining. To simulate the behaviour of the lining, the thermomechanical behaviour of the castable was characterised in compression and three point bend tests, thermal dilatation tests and TGA analysis in the 20–600°C temperature range. The change in properties is shown to be due mainly to transformation of hydrates in the castable. Numerical simulations of the lining drying process were also performed using a finite element code to verify the causes of cracking. A parametric study was carried out to examine the possibility of reducing the stresses induced by thermal loading. Improved thermal insulation and better control of heating reduce the risk of failure in the lining.     

Kyanite compounds for guncreting the linings of steel ladles

Conclusions A study was made of the properties of guncrete compounds based on kyanite suitable for service in steel ladles. The best properties were possessed by a compound containing 80% kyanite, 10% clay, and 10% binder.Industrial trials with the guncrete compounds were completed. The life of the new compounds is 20% longer than that of similar compounds based on Novoselitsk kaolin.Translated from Ogneupory, No. 8, pp. 25–29, August, 1981.     

Unmolded refractories of basic composition for monolithic linings of steel-casting and intermediate ladles

Conclusions The Magnezit Combine has developed bodies for monolithic linings of steel ladles, providing more effective use of starting materials with a simultaneous increase in the resistance of the metallurgical equipment. However, to achieve the advantages it is necessary to redesign the existing production line, especially the mixing and weighing sections.Translated from Ogneupory, No. 3, pp. 5–9, March, 1990.     

Mullite-corundum ramming compound for the pits of steel casting and donkey ladles

Conclusions A composition consisting of mullite corundum ramming compound MMK-72 was developed for making the bottoms of steel casting and intermediate (donkey) ladles of the converter shop of the Azovstal' factory; it was prepared from high-alumina chamotte and kaolin with a bond of orthophosphoric acid. Using the standard TU 14-297-17-78, the production of the compound is being organized at the Zaporozhe factory. The MMK-72 compound is being introduced in the converter shop of the Azovstal' factory.Translated from Ogneupory, No. 2, pp. 12–13, February, 1981.     

High-Alumina ramming bodies for lining steel casting ladles having provision for vacuum refining

Conclusions At the electric steelmaking shop of the Cherepovetsk Steel Plant, the high-strength MK-90 corundum body produced by the Kazogneupor Factory was used for lining the cavities of the nozzles and the bottom portions of the 130 ton steel casting ladles in which argon blowing (lancing) and vacuum treatment of steel are carried out. The service life of the rammed ladle-base lining made from the MK-90 body (under the replaceable working layer) increased up to 3–4 months. Ramming of the cavity is carried out once during the campaign of the working layer of the ladle base.In order to obtain monolithic lining of the ladle walls, we developed a ramming body based on electromelted corundum and containing coarse-grained corundum and a plastic refractory clay as additives and a binder made from orthophosphoric acid. Industrial production of this body was assimilated at the Kazogneupor Factory under the trademark MK-65. The life of the lining of the ladle walls made from this body amounts to 13–14 fillings (heats) as compared to 8–10 fillings when using ladle bricks.We suggested the composition of the ramming body containing a carbonaceous additive in the form of spent electrodes of the steelmaking arc furnaces and having an increased slag- and metal-resistance.The first discussion was published in Ogneupory, No. 8 (1988) and the subsequent discussion was published in Nos. 9–12 (1988) and Nos. 1–3 (1989).Translated from Ogneupory, No. 5, pp. 1–5, May, 1989.     

A ramming mixture for cupola linings

Ramming mixtures with a carbon-containing component and mullite-corundum chamotte from Chinese bauxites instead of electrofused corundum have been developed for linings of cupolas designed for a prolonged continuous melting campaign. Ramming mixtures of grade MMKU are produced by the Semiluki Refractory Plant in correspondence with modification No. 2 of TU 14-8-559-88. Use of the mixture in the lining of a bottom, a hearth, and a compression siphon provided an endurance of the cupola equal to that of a lining from a conventional mixture based on electrofused corundum.Translated from Ogneupory, No. 2, pp. 26 – 27, February, 1996.     

Compounds based on novoselitsk kaolin for the gunite linings of steel ladles

Conclusions A study was made of the properties of Gunite compounds based on Novoselitsk kaolin suitable for service in steel ladles. The best composition was: 90% chamotte, 10% kaolin, and 10% (on 100%) bond. A State Standard was developed for Gunite powder. Industrial trials were done on the new compounds. The results of the trials confirmed that it is feasible to use Novoselitsk kaolin for producing Gunite compounds.Translated from Ogneupory, No. 2, pp. 10–13, February, 1979.     

Cast magnesia-spinel concrete linings for steelcasting ladles

Conclusions The magnesia-spinel concretes developed by the writers possess good mobility, thermal-shock resistance, volumetric stability, and low porosity. The concretes settle without additional compaction.A simple technology was developed for the production of cast concrete linings in steelcasting ladles. In transformer steel production the lining of 25-ton recasting ladles lasted six times longer than a chamotte brick lining and the specific consumption of refractories was four times lower; in 35-ton steelcasting ladles a lining of concrete MShG-15 lasted twice as long as a chamotte brick lining and the specific consumption of refractories was 1.3 times lower.An installation was devised for the production of cast concrete linings in steelcasting ladles.Translated from Ogneupory, No. 5, pp. 9–15, May, 1977.