Guniting the lining of 300-ton steelcasting ladles

Conclusions The 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.Deceased.Translated from Ogneupory, No. 2, pp. 29–32, February, 1978.     

Gas-flame guniting of the lining of intermediate continuous steel-casting ladles

Conclusions As a result of laboratory investigations and rig testing of the flame guniting of intermediate ladles for continuous steel-casting plant we recommend the following bodies: 90% corundum, 10% sodium tripolyphosphate; 80–90% corundum, 20–10% chamotte; 80–90% high-alumina chamotte, 20–10% chamotte. The particle size of the corundum body is <0.088 mm, high-alumina <0.25 mm.The optimum guniting cycle is: consumption of natural gas 60 m³/h, oxygen 100 m³/h, gunite body 150–200 kg/h, guniting distance 450–550 mm, rate of moving the burner 1.0 m/min.In the case of chamotte, the coefficient of gunite body utilization equals 0.75, for high-alumina 0.70, and for corundum 0.40, with an open porosity in the gunite coating of 10–15, 8–10,and 4–6%, respectively.Using the experimental equipment the body made from 90% corundum and 10% sodium tripolyphosphate was used to gunite the side surface of the lining of an intermediate ladle. The wear of the gunite section of the lining was 1.3–2.5 mm per heat.Translated from Ogneupory, No. 4, pp. 37–42, April, 1973.     

Mechanized guniting of the lining of steelcasting ladles

Conclusions A method has been developed and equipment constructed for guniting steelcasting ladles without any manual labor. Experiments and tests were carried out with compositions based on quartzite, Chasov-Yar semiloamy sand, and fine-ground chamotte. The industrial-scale guniting tests showed that the durability of the lining of 130-ton steelcasting ladles increases by 30% (4.7 melts) on average with one guniting per ladle campaign.Translated from Ogneupory, No. 5, pp. 32–36, May, 1977.     

Improving the efficiency of guniting steel-pouring ladles

Conclusions Hot guniting of steel-pouring ladles without cooling the lining enables us to reduce the time taken to prepare them for pouring, and creates conditions for repeated hot guniting within a ladle campaign. This will make it possible to increase the stability of the lining and to reduce the energy expended on drying the gunite layer.The efficiency of mechanized guniting can also be improved by differential use of gunites with rational compositions.Translated from Ogneupory, No. 7, pp. 38–41, July, 1981.     

Composition and erosion of Gunite coatings and the technology of converter guniting

Conclusions Spalling and slag erosion are the principal forms of wear of the Gunite coating in converters. Spalling is caused mainly by the difference in the thermal conductivity of the magnesite coating and the tar-bonded dolomite-magnesite lining bricks. Spalling can be prevented without impairing the slag resistance of the coating by applying the Gunite mix in thin layers after every 2–4 melts. The coating was gradually dissolved in the slag before reaching the spalling stage.Tests were carried out with 130-ton converters at the Il'ich Metallurgical Plant in Zhdanov. Regular guniting increased the durability of one of the converters by 120 melts. On another converter a firm 70-mm-thick coating, which did not crumble even when the converter was cooled down for cold overhaul, was produced in the journal zones in 12 guniting operations after the lining had burnt through to the shell.Petrographic investigations showed that the principal phases of the Gunite coating after service in the converter are periclase, magnesiowuestite, calcium ferrite, dicalcium silicate, a vitreous silicate bond, and RO-phase; inclusions of metallic iron occur here and there.Translated from Ogneupory, No. 1, pp. 34–40, January, 1977.     

Guniting the lining of steel-casting ladles

Conclusions In a joint investigation by the Serp i Molot Metallurgical Plant in Moscow and the All-Union Institute of Refractories the advantages were demonstrated of guniting the lining of steel-casting ladles. The first industrial-scale trials showed that guniting results in a significant increase in the durability of the lining and in a decrease in the consumption of ladle brick. In order to extend the practice of guniting steel-casting ladles it will be necessary to organize the production of gunite at specializing establishments of the refractories industry.Translated from Ogneupory, No. 8, pp. 37–39, August, 1975.     

Guniting of the monolithic lining of steel-teeming ladles

Conclusions The authors have developed the principles of guniting the monolithic lining of steel-teeming ladles with semidry masses. Determination of the wetting of a vitrified siliceous monolithic lining with aqueous solutions of additives and suspensions of these solutions, plasticizing additives, and refractory filler has shown that a coating can be deposited onto the surface of a monolithic lining. Formation of a ceramic bond between the coating and the vitrified surface of a monolithic lining takes place at high temperatures (900°C or above). Masses of siliceous, aluminosilicate, and periclase-chromite compositions have been developed for guniting the monolithic lining of steel-teeming ladles.A procedure for guniting the monolithic lining of 180- and 350-ton steel-teeming ladles has been developed and tested. The best results have been obtained with use of gunite masses of periclase-chromite composition.Translated from Ogneupory, No. 6, pp. 25–30, June, 1981.     

Guniting the lining of heating furnaces of rolling mills

Conclusions Guniting mass compositions and a procedure for guniting worn brickwork of continuous heating furnaces of rolling mills have been developed. At a number of metallurgical factories the worn brickwork of eight continuous heating furnaces of rolling mills have been repaired by guniting. The use of guniting enables the period between furnace lining repairs to be doubled (from 1 to 2 years), the volume of brickwork repair and the length of the repair work to be reduced, and a saving of 5000 rubles per annum per furnace to be obtained (merely by reducing the amount of repair work).Using IR spectroscopy the authors have investigated hydration and dehydration in alumina and high-alumina cements and aluminosilicate guniting masses with additives of these cements. They have shown that during guniting by the semidry method, hydration of the cements included in the composition of the gunite coatings does not go to completion and ends in the stage of formation of CaO·Al₂O₃·10H₂O; dehydration of the gunite coatings is completed below 300°C.Translated from Ogneupory, No. 5, pp. 30–35, May, 1980.     

Mixer lining life lengthened by guniting

Conclusions The mixer lining is destroyed by the penetration of liquid high-phosphorous pig iron into the joints of the brick lining and by the resulting volumetric changes in the lining.A guniting technology was evolved which produces a protective gunited layer on the lining, the result being that the useful life of the lining is doubled.Translated from Ogneupory, No. 8, pp. 25–28, August, 1973.     

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.     

The service of periglase-chromite refractories in the bottom of a converter with combined blowing

Conclusions Without the use of guniting and effective buildup of a crust the life of a converter bottom lining under the conditions of Nizhnii Tagil Metallurgical Combine does not exceed 400–450 heats.Unstable life (150–300 heats) of the upper layer of the bottom lining is an indication of irrational heating up of the converter before service.As follows from the experimental heats, to increase the life of the area near the tuyeres and the joint of the converter bottom and wall linings it is necessary to use BPGK-72-12 periclase-carbon blocks.Translated from Ogneupory, No. 4, pp. 48–50, April, 1990.     

Guniting the roof of open-hearth furnaces at the Zaporozhstal' plant

Conclusions Laboratory analyses and industrial-scale tests resulted in the development of the technological parameters for guniting the lining of the main roof of 500-ton open-hearth furnaces operated at an accelerated melting cycle.The microstructure of chromite and chrome — magnesite coatings containing low-melting additives was analyzed and the chemical composition and structure of coatings which had served in the roof of an open-hearth furnace were determined.The work carried out at the Zaporozhstal' Steel Plant confirmed the effectiveness and advantages of guniting the roof of large-tonnage open-hearth furnaces.Translated from Ogneupory, No. 5, pp. 28–35, May, 1976.     

Mixtures of a base composition: Consumable lining of tundish ladles of continuous casting machines

Work on creating a refractory mixture of a base composition for consumable linings of tundish ladles of continuous casting machines is described. Various binders for mixtures deposited on the working lining of the tundish ladle by guniting have been tested. The endurance of a consumable lining based on periclase with an elevated content of CaO was 5 heats on a CCM of an electric steelmaking shop.Translated from Ogneupory, No. 4, pp. 28 – 30, April, 1996.     

A method of calculation of a guniting flame

Conclusions A physicomathematical model and a method of calculation of the guniting flame making it possible to calculate the basic characteristics of flame guniting — combustion of the fuel and heating of the refractory — have been developed.An example is given of calculation of the guniting flame with parameters characteristic of industrial equipment. Based on its results the processes occurring in the guniting flame are described qualitatively.Translated from Ogneupory, No. 6, pp. 46–49, June, 1986.     

Obtaining gunite-bodies with the additions of the waste products of the aluminum industry

Conclusions We studied the possibility of using the waste products of the aluminum industry as additives for obtaining gunite-bodies. In order to carry out guniting of the electrolytic cells, we suggested the application of the lining-slag type systems and the systems based on corundum for improving the service life of the refractory lining of these units.Translated from Ogneupory, No. 1, pp. 8–10, January, 1990.     

Separation of refractory particles in flame guniting of the linings of oxygen converters

Conclusions It is theoretically shown that in flame guniting there are always maxima in the deposition of the Gunite. The maxima become flatter as the converter diameter increases or as the position of the nozzle is changed. By varying the angle of inclination of the nozzle or the distance between the nozzle and the lining, we can increase or decrease the area of the deposited Gunite.Translated from Ogneupory, No. 5, pp. 31–34, May, 1979.     

Optimization of the operating conditions of pneumatic transport systems for loose materials

Conclusions The new device for control of delivery of loose materials developed and installed provides uniform and stable flow of guniting mixture during guniting. In addition pulsations of the metal hoses through which the guniting compound is supplied are not observed.A constant flow of the solid constituent of the guniting compound to the outlet from the nozzle (nozzles) provides a stoichiometric composition of combustion with a constant specified flow of oxygen, and complete combustion of the carbon-containing constituent and fusion of the refractory constituents are obtained.Guniting with installation of the new device for controlling delivery of the guniting compound has made it possible to reduce its consumption by 0.74 kg/ton of steel under otherwise similar conditions.Translated from Ogneupory, No. 7, pp. 27–28, July, 1991.     

Guniting linings of oxygen converters in the course of melting without stopping the blow

Problems arising in guniting converter linings in the course of melting without stopping the oxygen blow are considered. Deposition of a mixture based on magnesite is conducted in an oxygen jet. As the powder particles move in the vessel, they are heated due to the heat of the converter and afterburning of carbon monoxide, which ensures their strong cohesion with the surface of the lining. The velocity and diameter of the gas-powder jet are calculated as a function of the concentration of the periclase powder, the distance from the tuyere nozzle, and the temperature of the magnesite particles heated in the vessel. An experimental installation is developed and experiments on guniting in the course of melting without interrupting the blow are conducted. It is established that the gunited coating is deposited on the lining only at the end of melting. The endurance of the coating is 1–4 heats. In guniting, the temperature of the metal increases by 20–70°C. The experiments showed the possibility in principle of guniting a converter lining in the course of melting without interrupting the blow. Translated from Ogneupory, No. 3, pp. 27–31, March, 1996.     

Separation of the refractory powder in the flame-guniting of converters

Conclusions An analysis of the deposition of the refractory particles on the converter lining in cyclonic-flame guniting revealed the presence of a conspicuous maximum deposition which coincided with the site of the peak depositions in a hot converter model and in a real 130-ton converter.Erosion of the converter lining is uneven and the local burns can be effectively repaired by depositing a maximum of gunite in the zone where the residual thickness of the lining is at minimum.Translated from Ogneupory, No. 5, pp. 49–52, May, 1975.     

Gunited concrete linings of conveyer sintering machines

Conclusions The construction of unique heating equipment requires the development of composite programs with a single center of control, coordination, and financing of all work: scientific research, planning and design, construction and assembly, and start-up and adjustment. Further introduction of gunited concrete linings requires standard production by the refractory industry of guniting mixtures, for which successful use may be made of VTs-75 cement of ferroalloy production clinker, using additional working with the addition of special inspection on the basis of petrographic or x-ray diffraction analyses or on the basis of the criterion M (limits of variation 3.2–4.1). In mineral composition the clinker must meet the following requirements: 73–78.2% CaO·2Al₂O₃; 5% max·CaO·6Al₂O₃; 3% max· MgO·Al₂O₃; 6–9% CaO·Al₂O₃; up to 4% chromium regulus.As the result of the work conducted, a method was developed for guniting linings of various degrees of complexity with a refractory layer thickness up to 200 mm operating at a temperature up to 1450°C in an oxidizing, iron, gas, and dust atmosphere.The method may find wide use for lining of thermal equipment both in the steel industry and in other branches of industry.Translated from Ogneupory, No. 4, pp. 51–57, April, 1988.