Testing unfired volume-constant magnesite-chromite products in open hearth roofs

Conclusions Tests in the main roof of a 160-ton open-hearth furnace showed that the wear of unfired volume-constant magnesite-chromite products on average is the same as that of fired products MKhS worked in the same section of the roof. The minimum wear is shown by unfired products based on fused magnesite.The mechanism of the wear in unfired and fired magnesite-chromite products is basically the same.Translated from Ogneupory, No. 4, pp. 29–34, April, 1969.     

Unfired chemically bonded reinforced magnesite-chromite refractories

Conclusions Basic parameters were developed for producing unfired chemically bonded products using internal and external reinforcement. Tests showed that the life of the unfired products is the same as that of the fired products during service in the roof of a large furnace, and much greater during service in the roof of a small furnace.Translated from Ogneupory, No. 3, pp. 5–10, March, 1973.     

Unfired quartz nozzles for teeming of steel

Conclusions Unfired quartz nozzles hardened by hydrothermal treatment for teeming of steel are no poorer in life than fired. In addition in contact with aggresive (manganese) steels the wear of the unfired ceramic is somewhat less. There was no penetration of the unfired material by the products of interaction of the metal with the refractory during service.Unfired nozzles based on suspensions produced by grinding in an acid medium and stabilized in an alkaline medium showed the least wear in service.Translated from Ogneupory, No. 1, pp. pp. 39–43, January, 1989.     

Use of unfired magnesia roof refractories

Conclusions We developed a technology and produced at the Panteleiminov Refractories Factory an experimental-industrial batch of unfired magnesite-chromite refractories in cladding with internal baffles (grids). These refractories can be used in the roofs of open-hearth furnaces with charges of up to 100 tons. The roof life is no shorter than with the use of ordinary fired magnesite-chromite bricks. The structure of the roofs can be built with the ordinary thrust-suspension system, but using asbestos inserts or board inserts for thermal-expansion compensation in the joints between the bricks in the rings.In heavy working conditions the wear intensity of unfired refractories in the open-hearth furnace roofs sharply increases.Unfired reinforced magnesite-chromite refractories can be successfully used in building the walls of the heads and vertical channels.It is necessary to test unfired reinforced magnesite-chromite refractories in the roofs of the lower structure of open-hearth furnaces.To increase the economic advantages of using unfired reinforced chromite refractories it will be necessary to reduce the costs of making the cladding.Translated from Ogneupory, No. 5, pp. 29–36, May, 1967.     

Tests of tar-bonded refractories in the lining of nickel converters

Conclusions Tar-bonded unfired type MDTBS-70 and MDTBS-75 parts produced by Chelyabinsk Metallurgical Combine were tested under the conditions of the South Ural Nickel Combine in nickel production converters. The life of the refractories in the tuyere belt and in the wall above the tuyeres was the same as for KhPT parts and the rate of wear was 3–5 mm/h.The primary factor influencing the wear rate of the refractories is the chemical reaction of the calcium oxide and the dolomite with the high-iron slags.Translated from Ogneupory, No. 6, pp. 55–58, June, 1985.     

Steelcasting nozzles of calcined dunite

Conclusions Dunite steelcasting nozzles were subjected to testing with melts of the entire range of steel grades produced by the Nizhne-Tagil Metallurgical Combine.The nozzles gave normal casting and no difference was noted in the behavior and wear of unfired dunite and magnesite nozzles with channel diameters of 30 and 70 mm. The quality of rail steel in terms of surface flaws was the same for both nozzle types.In casting wheel and tire steels the experimental nozzles proved to be superior. Dunite nozzles are less susceptible to channel constriction but more susceptible to burn-through by oxygen.Channel encrustation was more prevalent in fired than in unfired dunite nozzles but less prevalent than in unfired magnesite nozzles, in addition to which wear was more rapid in the case of the latter.Translated from Ogneupory, No. 4, pp. 3–7, April, 1975.     

Unfired volume-stable magnesite chromite products

Conclusions We investigated the conditions for obtaining volume-stable unfired products from magnesite and chromite. The use of finely ground chromite together with a reduction in shrinkage of the products contributes to an increase in the strength of the dispersed bond of the products in the temperature range 600–1200°C.In industrial conditions, using sintered and fused magnesite and Kimpersai chromite, we obtained unfired magnesite-chromite products, the changes in whose linear dimensions at 1700° C were from +0.3 to –0.6%.Unfired volume-stable magnesite-chromite products with regard to strength characteristics at elevated temperatures were as good as products MKhS.Translated from Ogneupory, No. 2, pp. 4–12, February, 1968.     

Magnesia roof refractories with fused spinel in the batch

Conclusions Dense highly fired roof refractories based on sintered magnesite powder and electrofused aluminomagnesia spinel are characterized by high volume constancy and a 30–50% lower wear compared with ordinary periclase — spinel products in comparative tests in the roofs of 600 ton open-hearth furnaces working with the use of oxygen.The wear of magnesite — spinel refractories containing 20, 30, and 40% electrofused spinel in the batch during service in the roofs of open-hearth furnaces occurs by fusion.Translated from Ogneupory, No. 1, pp. 24–28, January, 1971.     

Tests of mullite-corundum refractories based on fused mullite in the roof of an electric steel-melting furnace

Mullite-corundum refractories based on 63 – 90% fused mullite have been produced and tested in the roof of a 50-ton electric arc furnace. It has been established that their wear resistance is no worse than that of heat-resistant mullite-corundum bricks of grade MK-80 produced according to TU 14-80405-82. The tested refractories were worn due to their saturation with oxides from the molten products and the interaction of the latter with the structural components of the refractory. This promoted the decomposition of mullite into corundum and a glass phase with aftercompaction ands spalling of the refractory.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 12, pp. 31 – 35, December, 1996.     

Refractories based on fused material in the dolomite-magnesite system

Conclusions Fused materials in the CaO-MgO system ware obtained by electric-arc firing of dolomite and magnesite. These materials have a dense fine-grain (unoriented) structure with bonds between the periclase and lime grains.The refractories based on the fused materials of the CaO-MgO system, whether unfired tar-bonded or fired pitch-impregnated, are better than the refractories based on sintered materials. They have greater density and strength; higher resistance to hydration and the effect of slag; and a lower rate of established deformation at operational temperatures.The tests in an experimental converter of tar-bonded unfired refractories based on fused materials showed that the wear for these products is 30% lower than for the corresponding refractories made from sintered materials. The wear of the fired, pitch-impregnated refractories based on fused materials is 1/2 that for the corresponding unfired refractories.Translated from Ogneupory, No. 2, pp. 44–50, February, 1980.     

Using production scrap from alumina insulating refractories

Conclusions A method was developed for making rational use of waste from the production of alumina lightweight insulating products. The bodies based on these waste products are recommended for lining the pedestals (stands or rigs) of cupola furnaces by casting with templates.The unfired corundum products which were prepared are also recommended for lining the bases of the furnaces. The unfired double-layer corundum refractories were obtained with a strengthened working surface.Translated from Ogneupory, No. 8, pp. 20–23, August, 1971.     

Periglase-spinel refractories based on magnesite powder from caustic dust

Conclusions Periclase-spinel products in whose batch ordinary magnesite powder of fractions 3-1 mm is replaced with powder of the same fraction but obtained by burning caustic magnesite without sintering additives are satisfactory as regards all factors except thermal-shock resistance, and meet the requirements of GOST 10888-64.The resistance and wear of the experimental periclase-spinel products in the roof of an open-hearth furnace are about the same as for ordinary roof magnesite-chromite refractories.Translated from Ogneupory, No.5, pp. 12–13, May, 1970.     

Production of unfired steel pouring funnels with use of acid waste

Conclusions The basic technical standards have been developed for production of unfired steel pouring nozzles with use of a composite binder of production wastes as the binder. An experimental lot of unfired funnels was produced. Tests showed the possibility of their use for bottom pouring of steel. The advantage of unfired funnels is their high heat resistance.Translated from Ogneupory, No. 5, pp. 25–27, May, 1992.     

Quartz glass-base unfired Refractories

Conclusions Quartz-glass-base increased heat-resistance unfired quartz refractories were produced having after hardening a compressive strength of 24–26 MPa and an open porosity of 14.3–14.5%. Their strength may be increased by heat and moisture treatment. Such refractories do not lose strength in the whole range from 110 to 1300°C and are promising for the steel and construction material industries.Translated from Ogneupory, No. 8, pp. 34–37, August, 1985.     

Effects of melting parameters on the roof stability in a high-load electric steel-melting furnace

Conclusions The central part of the roof in a large arc steel-melting furnace is made of periclase-chromite refractories and wears 2–3 times more rapidly than the edge. The wear rate is governed by spalling in the working surface.There is no marked effect on the roof resistance from a maximum metal temperature averaged over a campaign in the range 1678–1690°C, but the resistance is much reduced if the temperature is raised further. The limit for the roof is metal at 1745–1748°C. The temperature of 1800°C is the critical one that destroys the roof.Increasing the melting cycle time (melting, preparation, and use) reduces the resistance, as does an elevated dust level.The conditions are most favorable for the roof when the charge contains steel scrap and metallized granules. The roof wears more rapidly when the batches do not contain scrap.Translated from Ogneupory, No. 1, pp. 31–32, January, 1991.     

A resource-saving technology for manufacturing unfired articles for bottom casting of steel

Basic parameters of a resource-saving technology for manufacturing unfired articles for bottom steel casting that was developed under laboratory conditions are presented. Industrial tests of an experimental batch of unfired bottom tubes produced by the suggested technology have shown high performance properties for them and applicability of them for bottom casting of steel.Translated from Ogneupory i Tekhnicheskaya Keramika, No. 8, pp. 27–29, August, 1996.     

Obtaining fused magnesia-alumina spinel and using it to produce magnesite-spinel roof refractories

Conclusions A method was developed for producing fused spinel which, when used in place of chromite as a component of the charge for basic refractories, yields roof products characterized by enhanced refractoriness under load, and also by low creep at elevated temperatures. This ensures high factors for the other properties. The preliminary testing of the refractories in the roofs of electric-steel melting furnaces demonstrated an increase in their wear resistance by 26–33% compared with the resistance of the currently supplied periclase-spinel refractories, which are used normally in these conditions.Translated from Ogneupory, No. 4, pp. 12–17, April, 1973.     

Service of mullite-corundum refractories in the center portion of the roof of high-power electric arc furnaces

Conclusions Type MKS domestic mullite-corundum parts to Technical Standard 14-8-140-75 have been introduced for the center portion of the water cooled roof of high-power arc steel melting furnaces at Belorussian Metallurgical Plant. The length of the roof campaign reached 180–220 heats without intermediate repairs, which is 25% longer than the life of imported refractories.The design of the center portion of the roof without a hole for charging of loose materials provides with the forms and dimensions of the parts used a symmetric lining and uniform distribution in it of the thermomechanical loads, which provides uniform wear of the lining and eliminates deformation of it during service of furnaces.On the basis of investigation of samples of the imported and domestic mullite-corundum roof parts after service it was established that wear of the lining occurs by fusion as the result of interaction of the refractories with the melting dust at 1660–1710°C.Different relative rates of chemical transformation and fusion of the mineral phases of the refractories were revealed. Mullite interacts with the melting reactants and fuses most intensely. In connection with this its content in mullite-corundum roof parts must not exceed 15–20%.Translated from Ogneupory, No. 1, pp. 56–60, January, 1987.     

High density corundum refractories

Conclusions We developed a technology for making high-density corundum products from granular unfired briquette made completely from finely milled, unfired processed alumina.We determined the rational firing cycles and methods of setting the products, having a shrinkage during firing of up to 20% linear.We established the possibility of firing corundum products from granulated bodies in a single-course setting with an accelerated cycle, with a total time of about 45 h, including cooling, and also the possibility of double stage firing at 1300 and 1750°C in a setting with a height of four rows.Translated from Ogneupory, No. 1, pp. 30–36, January, 1971.     

Making magnesite roof refractories with additions of fused spinel

Conclusions The Nikitov Dolomite Combine has produced an industrial batch of magnesite — spinel roof products containing fused spinel in the batch. The experimental refractories have very high quality factors.Testing of these products in the roof of a large open-hearth furnace with intensive oxygen blow in the bath showed that their resistance is 19% higher than the resistance of roofs made from periclase — spinel brick in identical furnaces at the Krivoi Rog Metallurgical Factory (with a simultaneous increase in output of 3.1%)Translated from Ogneupory, No. 4, pp. 1–6, April, 1971.