Zh. N. Demidova

Survey of Russian Federation inventions on refractories

Mullite-corundum refractory prepared from mixes, including corundum, clay, orthophosphoric acid and an additive distinguished by the fact that the addition to the mix contains a barium oxide concentrate with a barium sulphate content of not less that 85 wt.% with the following ratio of components, wt.%: barium oxide concentrate 6 – 10; refractory clay 1 – 4, corundum 79 – 88, orthophosphoric 5 – 7.

Investigation of Taimyrsk graphites for producing periclase-carbon ladle refractories

ConclusionsThe investigations showed that Taimyrsk graphite corresponds in chemical composition to foundry and crucible graphite.The content of crystalline graphite equals 13.0–26.3%. The characteristics of periclase carbon goods based on foundry and Taimyrsk graphites correspond to the demands placed on ladle refractories. The wear factors of these products in the slag belt of the lining of 350-tonne steel ladles are on practically the same level.Taimyrsk graphites may be used for the production of periclase-carbon ladle refractories in place of crucible or foundry graphite.

Refractory compounds of basic composition for the monolithin lining of steel-teeming ladles

ConclusionsQuestions of the method of production of basic ramming compounds at Panteleimonovka Refractory Plant and their use in the monolithic lining of the walls of 160-ton steel-teeming ladles of the No. 2 Converter Shop of Kirvoi Rog Steel Combine are considered.An analysis of the wear of the lining during service showed that it occurs as the result of spalling of the sintered zone and salamandering of the lining. The use of a movable thermally insulated lid made it possible to hold the temperature of the ladle lining within limits of 730–1120°C between heats and to obtain a basic rammed lining life of 21–39 heats as opposed to an average life for the shop of 14.8 heats.A reserve for increasing the ladle basic lining life is optimization of the thermal conditions of its service, including high-temperature heating of the lining before pouring of the metal, the use of thermally insulated lids with the minimum consumption of time for placing of them, an increase in the life of the well refractory to the life of the walls and bottom, and elimination of cooling of the lining between heats.

Influence of the aluminum oxide content of chamotte gunite masses on their slag resistance

ConclusionsThe authors investigate the influence of the aluminum oxide content of chamotte gunite masses on their slag resistance in contact with converter and synthetic slags. The refractory undergoes wear by dissolution of its surface in the fused slag; the slag does not penetrate very deeply into the refractory.A significant increase in slag resistance is observed only when the aluminum oxide content of the slag is 40% or more. An increase in the aluminum oxide content from 34–35 to 37–39% is not accompanied by a marked increase in the slag resistance. Linear regression equations with high correlation coefficients (0.70–0.98 in absolute value) have been constructed for different aluminum oxide content ranges.A more significant decrease in slag corrosion can be attained by introducing special additives into the chamotte mass composition.

Guniting the lining of 300-ton steelcasting ladles

ConclusionsThe practice of guniting the lining of steelcasting ladles has been introduced for the 300-ton ladles of the open-hearth division of the Cherepovetsk Metallurgical Plant. The guniting parameters are as follows: the temperature of the lining of the ladle wall should be 60–120°C; the amount of wetting agent (sodium silicate solution) for the optimal adhesion of the G unite layer to the brick masonry should give the G unite mix a moisture content of 8–15%, and the density of the aqueous sodium silicate solution should be 1.15–1.30 g/cm3.The guniting operation is carried out with a remote-controlled centrifugal-action machine which permits the operation to be carried out at a temperature in the ladle of 200°C. The durability of the ladle lining increases significantly when the lining is gunited regularly up to five times per campaign. The estimated economic benefit from the practice of guniting the 300-ton steelcasting ladles is 85,000 rubles/yr.

Drying the monolithic lining of 300-ton steelcasting ladles

ConclusionsThe optimal drying temperature for the monolithic silica lining of 300-ton steelcasting ladles is 500°C for a drying time of 18 h, provided the ladle casing contains an adequate number of ventilation holes.

A monolithic lining for 300-ton steelcasting ladles

ConclusionsIt was shown that in principle it is possible to produce a rammed lining in 300-ton steelcasting ladles by means of a template. A total of 20 experimental linings were produced by this method. The durability of the monolithic lining produced in 300-ton ladles at the Cherepovets Metallurgical Plant by a refined ramming technology was 11 melts on average, i.e., the same as that of a brick lining. The vertical distribution of the hardness of the lining is more even when the clearance between the reinforcing layer and the template is 170 mm wide. No distinct relation was found to exist between the durability of the lining and its hardness immediately after ramming. The variation of the hardness is the most significant factor in the durability of the lining. The durability of monolithic linings produced with a quartzite-based ramming compound is greater than that of a lining produced with a compound based on Chasov-Yar loamy quartz sand (10–13 melts as against 9–11).

High-refractory ceramics based on calcium and strontium zirconate

ConclusionsAn investigation was made of the sintering of calcium and strontium zirconate with combined synthesis, different plasticizing bonds being used. The relative densities obtained fluctuated within the limits 80–97%.Two-stage sintering of the zirconates ensures an almost completely stable densification. A relative density of the products of 97% can be achieved by a primary firing of the sinter at 1100°C followed by fine pulverization and a second firing of the products at 1710°C.The investigated properties of the sintered ceramics based on the zirconates characterized them as high-refractory, electrical insulating materials.The ceramics of granular structure based on calcium and strontium zirconates obtained with fine-ground bonds of the same composition fired at different temperatures can be characterized by relative densities of the order of 80–85% and good thermomechanical properties (4% deformation at1900–2000°C). The ceramics with the raw mix bond possessed less good properties.