Magnesite brick for open-hearth furnace regenerator checkers

Conclusions Investigation and service tests showed that in gas regenerator checkers for open-hearth furnaces magnesium parts made of metallurgical powder with a small iron oxide content do not frumble and are marked by good wear resistance.The technology of making dense magnesite fired and nonfired checker brick of small dimensions has been tested at the Panteleymonovo Plant.The tests on fired and non-fired checker brick in gas regenerators in 370-ton furnaces using oxygen showed their good wear resistance, the absence of wear and tear from the second and third courses upward and the possibility of keeping them for additional runs in the basic arch.     

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.     

Manufacture of magnesite-chrome brick for open-hearth furnace roof with heat insulation

Conclusions Roof brick with trapezoidal openings instead of round ones was manufactured under industrial conditions.The possibility in principle has been shown of mass-producing intricately-shaped units with holes not only of re rectangular shape, but also with sharp corners, in the form of a dovetail. The batch production of these parts on hydraulic presses with a single pressing cycle is advised.Research should be carried out on further improving the shape of roofbrick and ceramic suspensions for heat insulated roofs.     

Unfired chemically bonded magnesia products for open-hearth roofs

Conclusions An experimental batch of unfired reinforced products having a chemical bond was produced and tested in the roof of a small open-hearth furnace. The wear intensity of these refractories is 30–60% less than the wear of ordinary fired roof products produced by enterprises in the Ogneuporerud Trust. The properties of the unfired products are improved by using better raw materials.Translated from Ogneupory, No. 8, pp. 9–17, August, 1972.     

Use of dense magnesite-chrome brick in roof of rocking open-hearth furnace

Conclusion The use of dense magnesite-chrome brick for the basic roof of rocking open-hearth furnaces processing high-phosphorous pig irons increase the wear resistance of the roofs by 7–17%, which makes it possible to intensify the operation of the furnaces.The nature of the wear and tear in the dense magnesite-chrome brick in the roof of a rocking furnace does not differ from that of normal magnesite-chrome brick and shows up as the splitting of the working zone.The slighter wear and tear in dense magnesite-chrome brick is due to reduction in the rate of formation of zones on account of retarded migration of the melts into the brick.To increase the wear-resistance of magnesite-chrome roof refractories, they have to be pressed at a greater specific pressure and at optimum grain composition.     

Testing magnesite-chromite products in the roofs of open-hearth furnaces

Conclusions There is a relationship between the firing temperature, the degree of recrystailization of periclase and also the rate of erosion of the bricks in service.With high-temperature firing (1650–1750°C) and use of chromite and magnesite enriched with highly refractory oxides, a high resistance is possessed by roof bricks MKhS, RPShS and periclase-spinelide brick with additions of chromemagnesite clinker.Results of our work show the absence of a connection between the rate of wear of products and property factors provided for in standards for testing. The exception to a certain degree is thermal shock resistance (spalling resistance) and then only in the case of low values (a batch of dense products made of chromemagnesite clinker).In connection with this it is desirable to develop a method of determining those properties in the goods which directly or indirectly would influence their erosion (wear) resistance during use. These properties include in particular the dimensions of the crystals of periclase and the degree of the density of their reciprocal arrangement, which fundamentally characterize their specific surface.For more detailed study of the influence of the crystals of chromespinelides on the behavior of roof bricks in service, it is desirable to make additional tests of trial batches of brick in comparative service conditions.     

On the question of the life of magnesite-chromite roofs for open-hearth furnaces

Summary The wear of magnesite—chromite roofs in open-hearth furnaces is affected considerably by the method of assembling the roof, the shape and dimensions of the roof, and the service conditions.In planning open-hearth furnaces it is necessary to aim at getting a reduction in the span of the roof. The design of the roof should be such that the thrust load is transferred to the cold rings of bricks.The life of the roof is more correctly determined not only by the number of heats, but by the length of the campaign in terms of the number of hot days.