Resistance of steel-teeming stoppers

Conclusions In order to make spalling-resistant stoppers which can be used to teem metal satisfactorily, the charge at the refractory shop of the Nizhnly Tagil Metallurgical Combine should include 7–10% chamotte coarser than 2 mm and 45–50% finer than 0.54 mm. The temperature should be raised from 30 to 150° at the rate of 5–7°/hr, and from 800 to 1200° at the rate of 20–25°/hr. The holding time at 1280–1300° should be 10 hours.When laying down new specifications for standards for steel-teeming stoppers, it is essential to stipulate a porosity of 15–20% at refractoriness-under-load of 2 kg/cm² of not less than 1320 or not more than 1380°     

Press-moldcases made from centrifugally cast wear-resistant alloys

Conclusions The cases of press-molds having large linear dimensions and thin walls can be obtained from centrifugally cast high-chromium cast iron with subsequent hardening at 1080–1100°C in oil. The resistance of the experimental cases when first placed in the mold is three times greater than in ordinary cases made of 20Kh steel. The regrinding of the cases within the tolerance limits for refractory products, specified by GOST 5500-75, and subsequent operation without additional heat treatment, makes it possible to boost their overall resistance.Translated from Ogneupory, No. 1, pp. 21–23, January, 1981.     

The influence of technological factors on the densification of forsterite green ware

Conclusions The grading of bodies made of dunite containing 20% additions of metallurgical magnesite ensuring a reduction in green porosity lies in the range 50–80% fraction 3–0.5 mm, 0–30% 0.5–0.088 mm and 20–50% finer than 0.088 mm.With an increase in fabricating pressure the relationship between the porosity of the green ware and grading diminishes.With a reduction in the grain sizes of the top and lower fractions the green porosity increases. An increase in moisture content from 4 to 6% in most cases increases the green porosity.An addition of 2–4% sulfite lye reduces the porosity (without a correction for pore filling by lye).The porosity of the green brick is greatly increased during firing. With the presence in the body of finely ground metallurgical magnesite the region of minimum porosity of fired specimens compared with the corresponding region for green brick moves to the side with the large content of fines.Dunite bodies with 20% fine magnesite giving the minimum porosity and shrinkage in firing should be used with the following grading: 10–40% fraction 3-0.5 mm, 10–40% 0.5–0.088 mm, and 50–70% finer than 0.088mm.An increase in the fines in the body leads to high shrinkage and deformation of the specimens in firing.     

Increasing wear resistance of stoppers for 140-ton steel-casting ladles

Conclusions Among the principal reasons for partial or substantial leaking of the metal stream are the following: burning away of the stopper, breaking off of the spherical part of the head, wear and tear of the head and sleeve bricks and opening up of the seams through deformation of the rod.The stoppers burn away on account of a great deal of wear and tear in the pipes, erosion of the seams, formation of cracks in the pipes and head and deformation of the stopper on account of the rod becoming too hot.The amount of slag in the ladle is one of the main factors for corrosion wear in stopper pipes. The aggressive action in the slag increases as the temperature of the metal and casting time are increased.Breaking off of the spherical part of the head during the first stopper opening due to the formation of skull between the stopper saddle and head can be avoided by using a graphite filling.Insulation of the stopper rod reduces the temperature during casting by 150–300°. The use of good quality mortar in assembling stoppers reduces the erosion of seams, while the use of a high-alumina putty prevents wear in the pipes.     

The service of refractories in stream treatment of metal with continuous casting of the steel

Conclusions The service of monoblock stoppers, controlling nozzles, and submerged nozzles with stream blowing of the metal with gas was studied. The desirability of use of a monoblock stopper with a hole in the lower portion and a thread in the upper for treatment of the metal with gas in the intermediate ladle was concluded.The service of straight-through submerged nozzles under conditions of blowing was studied and means of increasing their life were noted.Translated from Ogneupory, No. 2, pp. 47–50, February, 1984.     

Making siphon and ladle products from Arkalyksk clay

Conclusions It is possible to use Arkalyksk clay in the bonding part of the batch in amounts of 3% for preparing siphon tubes with physicochemical properties corresponding to the requirements of GOST.With combined firing of experimental siphon tubes and ladle brick it was possible to increase the firing temperature by 50°C, as a result of which the porosity of the ladle brick drops 1%, and the wear 2–3 mm/heat. The experimental siphon tubes tested for casting steel had a satisfactory resistance.Translated from Ogneupory, No.2, pp. 1–3, February, 1970.     

Service of refractories in the continuous casting of 100 ton converter heats

Conclusions Refractories for steel-casting ladles used at present in the converter shop of the Novolipetsk Factory can be used for casting 100-ton heats. However, it is necessary to increase the resistance of the ladle linings.Ladle bricks, stopper tubes, and zircon nozzles provide reliable casting of 3–4 heats in series without replacing the intermediate ladle.To provide reliable covering of the jets where necessary it is recommended that use be made of highalumina plugs for intermediate ladle stoppers.Translated from Ogneupory, No. 7, pp. 37–41, July, 1968.     

Semiacid products from Latnensk clay

Conclusions The Semiluks Refractories Plant has established that it is possible to produce semiacid brick from 70% briquetted dry and then ground semiacid grade LT2PK, and 30% chamotte.The porosity and strength of the products is largely determined by the final firing temperature.The quality of the products made by the new briquette technology satisfies the requirements of GOST 4873-49 for semiacid products, and in terms of physical properties GOST 390-54 for firebrick. Using the technology developed by the Ukrainian Research Institute of Refractories and the Semiluks Refractory, Latnensk clay LT2PK can be used as a completely satisfactory raw material for manufacturing semiacid refractories.Translated from Ogneupory, No. 6, pp. 2–6, June, 1970.     

Differentiated use of refractories in blast-furnace hot blast stoves

Conclusions In the service of blast furnace hot blast stoves the lining and checkerwork fail in individual zones as the result of deformation of the refractories, formation of cracks, and chemical corrosion of the lining under the action of low-melting dust at high temperatures.It was shown that the deformation of aluminosilicate refractories depends not only upon temperature, load, and hold but also to a large degree upon the physicochemical properties of the parts, especially upon the composition and quantity of impurities.On the basis of an analysis of the service of refractories in hot blast stoves recommendations were developed on differentiated use of refractories in the different zones of the lining and checkerwork.For lining of the walls and the checkerwork of high-temperature hot blast stoves operating with a blast temperature up to 1300°C (temperature under the crown 1500–1550°C) the use of the following forms of refractories (GOST 20901-75) is recommended: 1550–1200°C temperature zone — type DV dinas parts; 1200–1100°C temperature zone — type MKV-72 mullite-corundum parts; 1100–900°C temperature zone — type ShV-42 chamotte parts; 900–700°C temperature zone — type ShV-37 chamotte parts; 700–400°C temperature zone — type ShV-28 chamotte parts.To line the lower portion of the combustion chamber mullite-corundum parts of types MK-80 to Technical Specification 14-8-405-82 or MKV-72 must be used.Lining of the crown, the inner wall of the combustion chamber, the hot blast lines, and the gas burners must be done with mortars corresponding to the types of refractories used (dinas and VT-1) with the addition of 10–12% orthophosphoric acid.Type MKRP-340 mullite-silica fiber parts to GOST 23619-79 and other fiber materials are recommended for use as the compensation gap filler up to temperatures of not higher than 1150°C, and asbestos-vermiculite plates to GOST 13450-68 in the up to 600°C temperature zone.The shell of the hot blast stove in the high temperature zone must be covered with thermal-insulation gunited concrete.Translated from Ogneupory, No. 7, pp. 44–50, July, 1986.     

The durability of acoustically tested SP-11-type mullite-corundum stoppers

Conclusions An investigation carried out at the Novolipetsk Metallurgical Plant of the performance of the SP-11-type mullite-corundum stoppers produced by the Semiluk Refractories Plant showed that the durability was highest in the case of stoppers with a resonance frequency of 10,000–12,000 Hz. The stoppers falling into that frequency range account for about 70% of the total output.Culling out the stoppers with resonance frequencies below 10,000 and above 12,000 Hz and the deaf stoppers by acoustic testing increases the performance reliability of the stoppers of pony ladles and lengthens their useful life by 0.25 melt.Translated from Ogneupory, No. 4, pp. 11–12, April, 1977.     

Steelcasting and intermediate ladles for equipment for the continuous casting of steel

Conclusions The life of linings in large ladles depends on the grade of steel, the amount, chemical composition and consistency of the slag.The intermediate ladle made in the factory ensures reliable operation during the casting of metal by the continuous steel casting operation.Heating the intermediate ladle to 1100–1200°C by means of compact burners, working on coke gas, and new designs for cooled stoppers and stopper devices greatly reduces slab loss.In the process of evaluating the casting of transformer steel the loss due to nonmetallic inclusions was greatly reduced, but not completely eliminated.Further work must be done to explain the causes of the formation of slag inclusions and methods of handling the problem.     

Selecting alumina grades for making densely sintered alumina ceramics

Conclusions The rheological properties of slips and the properties of the castings based on the aluminas investigated are very satisfactory and correspond to those obtained for specimens based on G00 alumina. The exceptions are the increased zeta-potential values in the slips made from aluminas GA5 and G0, and the reduced kinetic stability of the slip made from alumina GK.The specimens obtained from alumina of all the grades investigated at 1750° sinter until the apparent porosity completely disappears. The castings made from GK alumina have very high deformation in firing.The highest mechanical and dielectric properties are obtained with specimens of grades GA85 and GA8 aluminas.Sintered vacuum-type products with high electrical and mechanical properties should be made by using alumina grades GA85 and GA8 specified by GOST 6912-64 (instead of G00 as specified by GOST 6912-54).Translated from Ogneupory, No. 7, pp. 39–45, July, 1970.     

Stability of caprolactam on storage under manufacturing conditions

Conclusions Caprolactam which has starting quality indices that conform to the requirements of All-Union StateStandard (GOST) 7850-74 retains its quality for 15 days during the process of storage at 353 K under a nitrogen blanket containing no more than 1×10^–3% oxygen by wt.The duration of quality retention by caprolactam at 353 or 373 K is considerably reduced under a nitrogen blanket containing 6.7×10^–3% oxygen.The quality indices of caprolactam which have been made to conform to All-Union State Standard (GOST) 7850-74 canbe preserved only on the condition of storageat the minimum temperature which ensures keeping the caprolactam melted (T_cr=341.8 K) and in a medium of nitrogen containing no more than 1 × 10^–1% oxygen.Translated from Khimicheskie Volokna, No. 1, pp. 32–33, January–February, 1987.     

Production of roof refractories using magnesite chromite clinker

Conclusions A method for producing roof products using magnesite-chromite clinker from caustic magnesite and Kimpersai chromite was developed and tested on an industrial scale. The dry method of producing the clinker from 20–25% chromite and 75–80% magnesite powder is the best.Roof refractories made with the use of magnesite-chromite clinker satisfy the requirements of GOST for all factors except spalling resistance.Translated from Ogneupory, No. 7, pp. 9–14, July, 1967.     

Life of stopper heads in continuous steel casting

Conclusions Chamotte heads with 5, 10 and 15% graphite differ from conventional chamotte by high thermal endurance, thermal conductivity and wear resistance. The increased rigidity of stopper heads with a graphite content of 5 to 15% used in combination with magnesite sleeves enhances the formation of longitudinal cracks.Chamotte specimens fired at 1230° C are endowed with high wear-resistance. They differ from conventional chamotte refractories by higher thermal endurance and provide for good stopper service in reladling killed steel.High-alumina SP-9-type heads made at Chasov-Yar Combine wear less in intermediate ladles and are endowed with greater thermal strength than chamotte heads.The higher quality of the chamotte heads under conditions of Stalino Metallurgical Plant in comparison to that of Krasnoye Sormovo Plant is not only due to the quality of the refractory but also to such factors as the rate and degree of preheating intermediate ladles before filling with metal, careful placement of the stoppers, and use of graphite packing around the teeming head.Despite higher wear SP-12-type chamotte heads made at Chasov-Yar Combine allowed normal teeming of rimmed steel in 50 ton ladles.To ensure a steady service of the stoppers in continuous steel casting the preheating of intermediate ladles of 1300 and the use of precooled stoppers are recommended.     

Two-piece nozzle-batchers for continuous casting of electrical-engineering steel

Conclusions A design and production technology were developed for making fireclay two-piece elongated steelcasting nozzle batchers with an apparent porosity of 14–17%. The resistance of the nozzles is satisfactory and they form a satisfactory jet, despite the retarding action of the stopper plug.The nozzles are being introduced at the Novolipetsk Metallurgical Factory and their production organized at the Semiluki Refractories Factory. The use of elongated nozzles and improved insulation of the working zone in the crystallizer during the continuous casting of electrical-engineering and carbon steel permitted a substantial improvement to be made in the purity of the surface of the cast slabs and the quality of the metal, and also yielded 46,000 rubles annual savings.Translated from Ogneupory, No. 4, pp. 4–6, April, 1967.     

Thermal conductivity of insulating refractories measured by the standard method and by the cylinder method

Conclusions The coefficients of thermal conductivity of insulating refractories measured by the method prescribed in GOST 12170-66, using the recommended thermometers with a scale division of 0.1°C and thermal insulation made from firebrick with an apparent density of 1.0 g/cm³, are appreciably higher than data obtained by the cylinder method. At average temperatures of 200–500°C (400–1000°C on the hot face) the discrepancy comes within the range 50–200%; when T_mean=600–700°C (1200–1300°C on the hot face) the discrepancies diminish to 0–30%.The maximum apparatus error in determining the thermal conductivity according to GOST 12170-66 with the use of Beckmann thermometers and low thermal-conducting linings is 10–30% for – 0.2–1.0 kcal/(m·h·deg), which greatly exceeds that indicated in the standard, ±10%. The maximum proportion in the error comes from the measurement of the drop in water temperature as it passes through the calorimeter. Consequently, the use of the standard recommended thermometers with scale divisions of 0.1°C is unacceptable for measurements on materials with a low thermal conductivity, since it may lead to errors of about 100%.Detailed comparison of the results of measuring this factor on standard equipment using the Beckmann thermometers, and on the improved instrument designed by the Ukrainian Institute (the cylinder method), showed that the mean square deviation of the experimental values for thermal conductivity for identical specimens with respect to the interpolation curves in the case of standard determinations is 2–3 times greater than the corresponding deviation for the cylinder method.In most experiments the interpolation curves =f(T) for the standard method is different by ±15–25% from the curves obtained with the cylinder method. This displacement apparently is due to certain constant errors connected with the unaccounted-for sources of error in the standard methods.The proposed method of determining the coefficient of thermal conductivity is of interest for scientific-research work. The use of the cylinder method is industry is associated with difficulties in preparing the specimens — Editors.Translated from Ogneupory, No. 8, pp. 45–52, August, 1971.     

Technology for producing large dense kaolin blocks

Conclusions The Ukrainian Scientific-Research Institute of Refractories has developed the main technical parameters for obtaining dense kaolin products with relatively moderate specific pressing pressures (about 500 kg/cm²), The Podol'sk Refractories Plant produced an experimental batch of kaolin blocks with a porosity of less than 12% based on chamotte made from Novoselitsk kaolin. The main properties of the kaolin blocks are better than those required by GOST for brick class-A produced for blast furnaces, and correspond to the properties of dense kaolin blast furnace brick.Translated from Ogneupory, No. 6, pp. 2–6, June, 1971.     

Production and use of low-fired stopper tubes

Conclusions Fireclay stopper tubes made by semidry pressing and fired at 800–900° C are suitable for service in steel casting ladles in the open-hearth departments of NTMK. Compared with ordinary low-fired stopper tubes they are more spalling resistant and less thermal conducting.The use of low-fired stopper tubes is economical owing to the reduction in loss and fuel consumption in firing.Translated from Ogneupory, No. 5, pp. 8–10, May 1967.     

Dependence of SiO2> Gel Structure on Gelation Conditions and Sol Reaction Temperature as Followed by FTIR and Nitrogen Adsorption Measurements

The acid catalyzed hydrolysis and condensation of tetraethyl orthosilicate (TEOS) in the absence of alcohol was studied using cylindrical internal reflectance Fourier transform infrared (CIR-FTIR) spectroscopy at four temperatures. Special attention was given to the low-frequency band around 940 cm^-1 and its evolution corresponding to the changing silicic acid concentration. This method compared well with other published methods for studying condensation kinetics.Three different conditions for gelation were used to determine temperature and humidity effects on resultant gels. In addition, effect of reaction temperature on gel porosity and surface area was studied. Sols that were gelled at high humidity (84–96% R.H.) and room temperature, 22–24°C, had a much higher surface area and porosity than those gelled at low humidity (5–50% R.H.) and room temperature, 22–24°C, whereas sols gelled at high humidity (79–98% R.H.) and low temperature, 7–8°C, had an intermediate surface area and porosity. Temperature of hydrolysis and condensation reactions did not have a significant effect on surface area. It is proposed that differences in surface area and porosity are mainly caused by the rate of solvent evaporation. Rapid evaporation of solvent and quick gelation of the low humidity samples results in a close-packed microporous xerogel. This is in contrast to the slow gelation and increased available time for condensation in the higher humidity samples, resulting in a more open structure.