Experience with the industrial use of refractory concrete

Summary At KMK (Kuznets Steel Combine) extensive tests were made to fit various furnace parts with concrete containing Portland cement and aluminous cement, and also magnesia concretes containing sulfuric-acid bond.The concrete blocks and monolithic linings in a number of places exhibit advantages over brick structures.Concrete blocks behaved successfully in the air heaters, in the walls of heat-treatment furnaces for sheet rolling, in the covers of charging windows of open hearths, in the covers of charging traps of coke batteries, and in the dampers of periodic kilns for firing refractories.Concrete insulation was successfully applied to beam pipes.Experiments to use concrete to line the upper parts of soaking pits of blooming mills were unsuccessful.     

World Production of Steel and Magnesia Refractories: State of the Art and Trends of Development

The state of the art and the trends of development of the world production of steel, nonferrous metallurgy, and the cement industry -- the chief users of magnesia refractory materials -- are considered. A new generation of magnesia refractories developed for oxygen converters, electric furnaces, post-furnace and continuous steel-casting technologies, nonferrous metallurgy, and the cement industry provide conditions for environment-friendly, competitive, and effective applications in various branches of industry.     

The wear of magnesia refractories in electric furnaces for melting cast iron

Conclusions The wear of magnesia refractories, i. e., magnesite, perictase — spinel, and magnesite — chromite bricks and magnesite — phosphate mortar, in the walls of electric furnaces for melting cast iron is the result of the solution predominantly of the periclase crystals and to a lesser extent of the spinel in the lowbasicity ferrosilicate slag melt. Brick of the PShS type proved to be the most durable refractory. The use of high-alumina brick in the roof of the furnaces accelerates the wear of the magnesia bricks in the walls.To increase the durability of the lining of these furnaces trials should be carried out with an all-basic wall lining constructed of high-density PShSP-type brick on MF-1-type magnesite — phosphate mortar and a roof lining constructed of MKhS brick and the same mortar.Translated from Ogneupory, No. 4, pp. 44–49, April, 1976.     

Production and use of cast forsterite concrete blocks

Conclusions The technology for the production of cast forsterite concrete blocks with excellent thermal-shock resistance has been developed. The production of these blocks has been organized at the Experimental Plant of the Eastern Institute of Refractories. The use of cast forsterite concrete blocks in open-hearth furnaces has made it possible to reduce threefold labor costs in maintenance, and to shorten the repair time also threefold; in pit furnaces it has been possible to lower labor costs in maintenance threefold and to reduce the repair time by 25%.Translated from Ogneupory, No. 3, pp. 19–22, March, 1982.     

Experience with the use of highly refractory concrete in slit heat-treatment furnaces

Conclusions A highly refractory concrete based on Portland cement containing chromite aggregate proved to have a high resistance in heat-treatment furnaces.This type of concrete can be used in furnaces for ferrous metallurgy and the machine-building industry, mainly where chromemagnesite brick is at present in use.Wider use, in the building of heating equipment, of large blocks of highly refractory concrete should help to mechanize installation work, reduce costs and sharply reduce building time, and also prolong the furnace life.     

Experience with the use of refractory concretes in structural components of open hearth furnaces

Conclusions Production tests showed that the wear of the blocks made of refractory concretes based on periclase cement and on Portland cernent in the walls of vertical channels, in the back wall and in the front columns of open-hearth furnaces does not exceed the wear of structures of refractory brick.It would be advantageous to continue tests on blocks of refractory concretes in open-hearth furnaces by extending the scale of the trials. The sizes of the blocks should be increased and their weight brought to three tons.For the large-scale use of large blocks of refractory concrete in open-hearth furnaces it is necessary to organize the plant manufacture of all components and to mechanize repair operations.A classification of refractory concretes was given in Ogneupory No. 5 for 1960 and in SNiP part I, section B, chapter 3, p. 11, Gosstroiizdat, 1963 [in Russian].     

Wear of MgO-C Refractories in EBT Type Furnaces Experienced at Iranian Mobarakeh Steel Plant

Mobarakeh Steel Company produces 3 million tons ofsteel annually with eight 180 tons EBT furnaces. Differ-ent types of magnesia-carbon refractories have been em-ployed at slagline during last 5 years. In the present studythe wear and corrosion of MgO-C refractories of these fur-naces have been studied via post-mortem analysis of usedbricks and the observation of operational effects. Laborato-ry corrosion tests were also arranged to investigate the effectof slag chemistry and the mechanism of chemical corro-sion. Characterization of different magnesia-carbon bricksclarified that the crystal size, type and chemistry of mag-     

Behavior of magnesia bricks in furnaces for the production of manganese alloys

Conclusions The application of dense magnesia bricks contributes to increased durability of the lining in metal manganese and manganese slag producing furnaces.The life of magnesia brick linings with an 11 to 13% porosity amounts to 45 days.The employment of large-size bricks hightens the resistance of the furnace bottom.Periclase-spinel brick proved unsuitable in the production of manganese slag.It is suggested that bricks with a porosity of 14 to 16% be tested for the purpose of determining optimal porosity.     

Use of large magnesiospinellide concrete parts soaking pit hearths

Conclusions A method of production of large magnesiospinellide concrete parts for soaking pit hearths based on slag- and iron-impregnated scrap of magnesia refractories has been introduced in Khristoforovka Refractory Block and Concrete Plant.The parts have been introduced in practically all steel plants of the country, which has made it possible to industrialize hearth repair and to replace scarce chromite-periclase b brick with concrete parts of production waste and thereby to save a significant quantity of magnesite, chromite, fuel, and electric power.The effectiveness of the development will be increased significantly with the use as the filler of the refractory concrete of magnetic scrap of enriched LMO magnesia scrap, which is disposed of in the dump at present.In connection with the above, supplementing the production plans for separation of magnetic scrap from the slag-contaminated scrap of Nikitovskii Dolomite and Zaporozhe Refractory Plants with appropriate equipment to obtain magnetic scrap of the finer than 20-mm fraction is recommended.Translated from Ogneupory, No. 3, pp. 40–46, March, 1988.     

Production and service testing of magnesite-chrome concrete

Conclusions In addition to magnesite-chrome concretes with periclase cement base, they can also be manufactured using a periclase-spinel cement. These concretes show less initial strength, but they soften to a lesser degree over the range 400 to 1000–1200°, hence after heating their strength is not lower than concrete with a periclase-cement base.The least softening of magnesite-chrome concretes over the given temperature range is shown by those with the addition of magnesium sulphate solution and soluble glass; as the modulus of the soluble glass is reduced, the compressive strength of the concretes under air-dry conditions and during heating increases. To obtain strong concretes, the soluble glass modulus must come within 1,8–2,2.In pneumatic tamping the strength of magnesite-chrome concretes is much greater than in vibration methods.In the spouts of electric steel-smelting and open-hearth furnaces, magnesite-chrome concrete showed a high degree of resistance, and its use for this purpose should be widely recommended.In the walls of an electric steel smelting furnace, the magnesite-chrome concrete was not inferior in strength to magnesite brick. The concrete containing magnesium sulphate was particularly satisfactory in this respect.The positive results of the test show the advisability of using concretes with a magnesium sulphate bond in the walls of electric furnaces with a view to replacing rammed linings made with a tar and pitch bond.The use of concrete for lining arresters in vacuum steel casting ensures satisfactory steel casting and has no effect on the quality of the metal.     

The production and service testing of magnesia wares from Rapna magnesia

Conclusions Magnesite refractories from Rapna magnesia are of high quality.Tests on periclase — spinel wares from Rapna magnesia in the crowns of Marten's furnaces working under intensified conditions showed that their wear was 15 to 17% lower than that of regular periclase — spinel bricks.It was shown that, by the use of periclase — spinel bricks from Rapna magnesia in the crown of a Marten's furnace working with an oxygen jet, it will be possible to lengthen the run of the furnace by 16–21%.Translated from Ogneupory, No. 7, pp. 1–6, July, 1969.     

Construction of renewable roofs for continuous heating furnaces

Constructions are considered for renewable roofs of continuous heating furnaces using different lining materials: chamotte refractories, monolithic refractory concrete, and refractory ceramic fiber. It is established that it is most desirable to use panel roofs using modular blocks made of refractory ceramic fiber. __________ Translated from Novye Ogneupory, No. 11, pp. 23–27, November 2007.     

Use of electric power in glass melting

The advantages and disadvantages of electric furnaces for melting frits and enamels and glasses for special applications were examined. It was shown that low-efficiency electric furnaces are more economical than furnaces heated by organic fuel. The main advantage of electric furnaces is the reduction in harmful emissions.Translated from Steklo i Keramika, Nos. 3–4, pp. 8–10, March–April, 1994.     

Use of magnesite concrete in open-hearth furnaces

Conclusions Many years practical experience with the use of refractory magnesite concretes in open-hearth furnaces at the KMZ confirmed that it is rational to use them even for preparing concretes and blocks on the working sites of open-hearth shops, and it also confirmed the unacceptability of open-hearth furnace structures for placing the concretes.A project for a furnace framework should be developed bearing in mind the use of blocks of maximum sizes which will accelerate repairs.Simultaneously with the increase in the output of chrome-magnesite mixture for the production of concrete it is necessary to produce this mixture with greater fineness for the wash materials.Translated from Ogneupory, No. 6, pp.31–35, June, 1972.     

An analysis of the reasons for the increased wear of the walls of the soaking pits of the 1150 slabbing mill of Il'ich plant

Conclusions It has been established that the increased wear of the silica refractory parts (concrete blocks and brick) in the soaking pit walls of the 1150 slabbing mill is caused by chemical interaction of the iron-manganese slag containing the aggressive intermetallic phase Fe_xAl_y with the silica lining with the formation of low-viscosity molten material.The type of steel has a significant influence on the wear of the lining. The most aggressive are killed and semikilled steels, which in contrast to rimmed steels are deoxidized with aluminum.The structure of refractories has a definite influence. The more dense dinas parts, which possess a strong tridymite bond of the crystals in the finely dispersed portion, are more wear resistant than the silica concrete blocks not containing tridymite.Testing of refractory concrete parts of magnesia spinellide or forsterite compositions in the walls (or only in the support zone) of soaking pits with liquid slag removal is recommended.Translated from Ogneupory, No. 3, pp. 42–46, March, 1986.     

Service of fireclay blocks with clay — Phosphate bonds in blooming soaking pits

Conclusions A technology was developed for making chamotted concrete blocks with clay-phosphate bond. A cycle was selected for thermal processing.Blocks were tested in the walls of the working cells of soaking pits used for blooming. The resistance of the block lining is 50% higher than that of the brick lining.The blocks wear out mainly because of slag formation at the surface and the edges, and also because of mechanical failure. Scaling was noted during service of the blocks after natural drying.The phosphate bond during prolonged heating contributes to the decomposition of the mullite, and has a mineralizing effect on the polymorphic inversions taking place in the silica.Chamotte concretes with clay-phosphate bonds can be recommended for use in heat-treatment furnaces.Translated from Ogneupory, No. 2, pp.21–26, 1971.     

Effect of boric oxide on the electric conductivity of polycrystalline magnesia

Conclusions New data were obtained for the electric conductivity of magnesia sintered with boric oxide additions in the range 1000–1600°C. This additive affects the electric properties of the magnesia, substantially increasing the electric conductivity at temperatures above 1300°C.Translated from Ogneupory, No.2, pp. 44–46, February, 1970.     

Sighting tubes for temperature measurements in open-hearth roofs

Conclusions Service tests of sighting tubes made from corundum and magnesia spinel showed that a gas permeability of 0.0009–0.00006 liter·m/m²·h·mm water guarantees the measurement of temperature with optical pyrometers without interference from the gaseous atmosphere.The maximum life of sighting tubes placed in the roof of open-hearth furnaces is obtained only when the articles are fixed at a distance not exceeding 40–50 mm in front of the roof surface; the minimum life is possessed by those products protruding into the furnace space by a magnitude equal to 3 diameters. The greatest resistance is shown by articles made from magnesia spinel.The sighting spinel, thin-walled tubes can be used for short control temperature checks of the roof of open-hearth furnaces; corundum and spinel tubes can be used for automatic measurements of temperatures in periodic kilns for firing refractories.Translated from Ogneupory No. 6, pp. 7–10, June, 1968.     

Roof bricks from well-brine magnfsia

Conclusions Existing production equipment at the Nikitov Dolomite Plant was used for establishing the production parameters for magnesite-chromite roof brick from well-brine magnesia, and two large experimental batches of brick were produced. The bricks possessed good physicoceramic properties and increased durability in the roof of high-productivity open-hearth furnaces.Translated from Ogneupory, No. 5, pp. 10–15, May, 1976.     

Melting refractory borosilicate glass in electric furnaces

The advantages of melting refractory borosilicate glasses in electric furnaces as compared to gas furnaces are described. The processes that occur in liquid glass melted in deep electric furnaces and technologies producing liquid glass of high quality are considered.