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.     

Magnesia blocks formed on a 3000-ton hydraulic press

Conclusions A production line containing a 3000-ton hydraulic press is used for manufacturing unfired chrome magnesite and forsterite concrete blocks for repairing the lining of heat-consuming plant by mechanical means.An analysis was carried out of the variation of the properties and chemical composition through the block and with the heat treatment temperature, and of the deformation and thermophysical properties and slag resistance of the blocks. The blocks can be recommended as lining material for the walls of the slag pockets and vertical channels of open-hearth furnaces of varied capacity, and for the floor and lower part of the walls of soaking pits.With these blocks the process of lining metallurgical equipment can be mechanized, labor productivity is higher, and the useful life of the individual lining elements longer. The savings achieved from using the blocks as lining material amount to 13–15 rubles/ton blocks.Translated from Ogneupory, No. 6, pp. 4–9, June, 1976.     

Service of Bakor-33 and Corhart-Zac in a glass furnace

Conclusions Bakor-33 in the main is as good in its physicochemical and service properties as the Corhart-ZAC refractory. The use in the walls of a tank furnace of Bakor-33 and dense silica allowed us to raise the melting temperature from 1480 to 1505–1510°C, to improve the quality of the glass, to prolong the campaign from 22 to 27 months and to melt an extra 46,000 tons of glass or more.When high-temperature melting (above 1500°C) is used it is best to employ Soviet fusion-cast Bakor-33 for the upper course of the tank walls in the melting part if window and technical glass are being produced. It is undesirable to use Bakor-33 blocks in the pouring section inside the furnace.In view of the serious wear of firebrick with high-temperature melting it is recommended that the low-lying courses of the walls of the melting part be made of fused corundum refractory Bakor-20.The first five pairs of ports in the glass furnace should be made of Bakor-33 blocks and the other of silica.To obtain high-grade glass from high-temperature melting it is desirable to make the upper courses of the walls of the cooler and working parts in fused corundum or Bakor-20, and in the extreme case, of high-Al₂O₃ blocks.     

Tests on dinas concrete blocks in soaking pits of a blooming mill

Conclusions Dinas brick in the lining of soakingpits at 1400 – 1450 showed the same resistance as dinas brick, to the separating wall under the refractory layer the dinas concrete did not fuse and after 8 months of service was still suitable for further use.Temperature measurements show that the surface of the brickwork below the refractory lining heats up to 1200. This excludes the possibility of using heat-resistant concrete with a portland cement base and a chamotte filler in the brickwork of the basic walls of pits.Dinas concrete blocks can be used to replace dinas brick in the working lining of soaking pits and chamotte in the     

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.     

旋风炉SiC质炉衬损毁机理研究

热电厂旋风炉ＳｉＣ炉衬，由于受液态渣的侵蚀，在短期内损毁。本文研究了液态渣的物相、渣村的相互关系，认为ＳｉＣ炉衬的侵蚀机理：一方面由于增钙，液态渣变稀，渣中多钙、铝而少硅，对炉衬的渗透力强，能夺取ＳｉＣ中的硅，造成化学侵蚀；另一方面是由于旋风燃烧的作用，液态渣对炉衬的机械侵蚀。该研究结果为研制新炉衬提供了依据。     

Service of refractory concretes in the lining of steel-teeming ladles

Conclusions An investigation of the temperature and slag regimes of concrete linings has shown that one half of the lining's thickness, the one on the metal melt side, is subjected to severe cyclical changes in temperature, whereas the other half operates under steady thermal conditions throughout the furnace campaign.It has been established that cooling of the lining with water sharply reduces the temperature of the contact layer of the lining, i. e., it leads to thermal shock with accompanying crack formation.The durability of the lining is largely determined by the correspondence of the chemical nature of the lining material with the chemical composition of the slags. Under the influence of converter slag with a basicity of 3,1–4.5, the rate of transfer of SiO₂ from the acid lining to the slag increases by 2–3 times in comparison that observed for slag with a basicity of 2.5–3.35. This in tarn leads to more intense decrease in the basicity of the ladle slag, enhancing its fluidity and causing intense wear of the lining in the lower sector of the ladle.The results of industrial tests showed that the most agressive effect on an acid lining is exerted by fluid slags with a basicity of 2.1–2.7. Slags of lower basicity are more viscous and closer in chemical composition to that of the lining. Slags of higher basicity have a higher viscosity and their penetrative power is therefore less.Translated from Ogneupory, No. 7, pp. 28–33, July, 1979.     

Models for Local Wear of the Lining of a Converter

Models for the wear of the lining produced by dissolution of the refractory oxide in slag and by the impact of droplets of metal and slag on the surface of the lining are considered. The wear rate and location of the zone of local wear as predicted by a model analysis conform with actual data.     

The production of refractory concrete and aluminosilicate Gunite compositions in Poland

Conclusions In view of the relatively short period of time elapsed since refractory concretes based on alumina cement were introduced in ferrous metallurgy and other industries, and in view, moreover, of the limited area of application of the concretes, the experiments with various types of concrete and the investigation of the technologies of their application should be continued.Phosphate-bonded refractory blocks and reinforced concretes should be subjected to tests in soaking pits operating under demanding conditions (at 1400–1450°C with liquid slag removal).The top part of the lining of soaking pits should be made of cast concrete reinforced with ceramic brick, or of a chemically bonded ramming compound which improves the stability of the concrete lining.In view of the considerable economic benefit than can be achieved by reconditioning the lining of heat-using equipment by guniting, this method should be introduced on a broad scale in ferrous metallurgy and other industries.The technique of guniting the hot lining of furnaces with chemically bonded compositions requires refining and calls for the use of special equipment (water-cooled nozzles of various cross sections).The users of Gunite compositions should be supplied guniting equipment, the shortage of which at present impedes the further spread of the practice of guniting heat-using equipment.Translated from Ogneupory, No. 2, pp. 50–61, February, 1977.     

Effects of mixture composition on the lining stability of a crucible induction furnace

Research results are reported on the effects of components on the resistance of acid lining for the crucible induction furnace. To raise the lining resistance, one needs to eliminate components that react with the silica crucible. The extent of silicon reduction from the lining is dependent on the heating of the metal and the contents of carbon and silicon in the liquid. Increasing the carbon content and reducing the silicon concentration in the metal favor wear on the crucible. The slag components most actively influencing the resistance of the lining are magnesium and calcium oxides, which are produced on modifying cast iron, ferrous oxide, and manganese on account of reduction in the viscosity of the slag, increase in its wetting power, and penetration into the pores and unevenness in the walls of the crucible. Translated from Novye Ogneupory, No. 5, pp. 41–43, May, 2008.     

Wear of the periclase-lime lining of steel teeming ladles in ladle desulfurization of steel

Conclusions Wear of a periclase-lime steel teeming ladle refractory lining is a complex physicochemical process in which it is practically impossible to distinguish a predominant elementary direction of action of the molten slag and metal.Replacement of liquid synthetic slags with solid slag-forming mixtures in ladle desulfurization of steel does not have a significant influence on wear of the lining working layer.An increase in the amplitude and number of thermal cycles significantly increases formation of cracks in the refractory lining and, consequently, accelerates its wear. An increase in temperature gradient within the refractory layer significantly increases crack formation.The presence of high-temperature contact of the periclase-lime lining working layer with strong deoxidizers accelerates its wear.Reduction of the magnesium and calcium of the refractories by the carbon of the binder under ladle service conditions may occur only with escape of gaseous CO through the reinforcing layer and the joints of the refractory lining in special gas escape holes in the ladle shell.Translated from Ogneupory, No. 3, pp. 33–36, March, 1993.     

The effect of phase formation during use on the chemical corrosion of magnesia–chromite refractories in contact with a non-ferrous PbO–SiO2 based slag

One of the main factors limiting the lining lifetime in pyrometallurgical smelters is continuous refractory oxides dissolution in the slag bath. The overall wear is accelerated when the slag infiltrates the porous brick and the dissolution thus occurs in a larger part of the lining. This work investigates the possibility of preventing deep infiltration by sealing off the pores with newly formed phases. Static finger tests at constant temperature (1200 °C) were performed in contact with a synthetic non-ferrous PbO–SiO₂–MgO slag, showing the formation of forsterite (Mg₂SiO₄) throughout the refractory sample by the reaction between SiO₂ (slag) and MgO (refractory). This phase grows with time, eventually sealing off the pores near the interface with the bath. The phase grows too slow to prevent full infiltration of the refractory but creates an equilibrium state in the sealed off part of the sample, ceasing the chemical corrosion in that part of the sample.     

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.     

New Formulations of Fused Periclase-Based Refractory Materials for the Lining of Steel Ladles

New formulations of fused periclase-based carbon-containing refractory materials for differentiated use in the lining of steel ladles (bottom, slag zone, and walls) are proposed. The use of new refractory materials made it possible to improve the lining durability from 80 to 100 heats.     

An Electronic Technology for Refractories Based on the Periodic Law

Prospects for development of electronic technologies in the production of refractories are discussed. Principles of the electron technology of refractories are given and techniques for control of electron supply in the electrochemical, thermochemical, and electrothermochemical treatment of refractory materials are described. The potential use of electromagnetic fields to increase the slag resistance of refractory linings is considered. Electronic wear as an initial stage in the wear of refractory materials is considered. Decreasing the diffusion of electrons from metal and slag to refractory may inhibit the electronic wear of refractory lining. Interested readers are invited to take part in a discussion of the material of this paper. __________ Translated from Novye Ogneupory, No. 10, pp. 75 – 83, October, 2005.     

The nature of the destruction and method of increasing the resistance of electric furnace linings

Conclusions During service, abundant saturation of the lining by components of the melting region is observed. The amount of silicates in the slag belt reaches 40–60% and in the high-lying lining — 10–15%.In regard to composition of the silicate bond in the working zones the lining is divided in height into two zones: the slag belt and the high-lying part. In the slag belt the bond is composed chiefly of cuspidine and fluorite; in the high-lying part — of dicalcium silicate and glass.Formation in the silicate bond of cuspidine and fluorite is due to the high rate of wear of the lining of the slag belt.In refractories of high density there is a smaller zone impregnated with reagents of the melting region, and so there is less wear during service.Further increase in the life of the lining can be obtained by using refractories with a minimum porosity in the slag belt and opposite the hot-phase arc; such refractories include fusion-cast blocks.     

On a Mechanism of Wear of the Periclase-Carbon Lining for Oxygen Converters

Effects associated with the capillary impregnation of the refractory materials with melted slag, the chemical interaction of graphite carbon with slag, and the dissolution of periclase in slag are considered. The time needed for melted slag to penetrate to the hot-layer depth of the refractory lining is a matter of several seconds. The carbon component on its contact with melted slag is reduced with FeO to yield CO. The partial pressure of carbon monoxide p _CO is calculated as a function of temperature (1500 – 1700°C) and FeO activity (0.1 – 0.5) in melted slag. The pressure p _CO is shown to exceed the capillary pressure of melted slag in pores, which prevents the easy penetration (because of the CO bubbles formed) of the slag into the periclase-carbon lining. The lining-wear effects due to the MgO concentration in the slag and to the size of periclase crystals are considered.     

Degradation of MgO–C refractories by MnO-rich stainless steel slags

In order to identify the influence of MnO on the wear rate of MgO–C bricks for the production of high Mn stainless steel, MgO–C refractory samples were exposed to slags containing different MnO levels (up to 26 wt.%). Although the investigations of the worn brick microstructures revealed the presence of numerous Mn-rich metal particles and the formation of a (Mg,Mn)O solid solution at the slag/refractory interface, no clear evidence of wear rate enhancement was observed due to high MnO concentration in the slags. With respect to refractory wear, the MgO content in the slag is the dominant factor. The degradation processes are discussed by combining experimental results and thermodynamic calculations.     

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].     

A Technology for Production of Composite Refractory Materials for the Lining of Steel Ladles

Results of the testing of new refractory materials for the lining of steel ladles are reported. Refractories based on coarsely crystalline periclase (98% MgO) for the slag zone with an endurance of 55 – 60 heats and wear rate of 2.3 mm/heat were tested. For the bottom lining of the steel ladle, alumina-periclase-carbon refractories using fused or sintered alumomagnesian spinels are developed. Performance characteristics of the newly developed refractory materials are discussed.__________Translated from Novye Ogneupory, No. 1, pp. 6 – 9, January, 2005.