Refractories based on sintered and fused periclase-chromite

Conclusions Replacing fused periclase-chromite by sintered material in PShPKh batches did not adversely affect the level of their technical properties.In terms of a combination of technical properties the experimental refractories may be recommended for tests in especially rigorous conditions, e.g., in the lining of a converter in equipment used for gas-oxygen refining of special steel.Translated from Ogneupory, No. 1, pp. 18–19, January, 1991.     

Experience in using periclase-chromite refractories in roofs of tilting open-hearth furnaces

The workers of the Azovsta’ integrated iron-and-steel works have determined the causes of early wear of main roofs of open-hearth furnaces. They have resorted to lining the main roofs by periclase-chromite refractories of grade LIIIV produced in Slovakia. The use of refractories of grade LIIIV has increased the endurance of the main roofs of open-hearth furnaces by 100 heats. A petrographic study has shown that the high operating properties of articles made of LIIIV are due to their composition and structure, obtained as a result of the use of high-quality initial materials (chromite ore and magnesite powder) and a modern manufacturing process. Introduction of the developed manufacturing process has increased substantially the endurance of the linings and reduced the number of cold repairs of the open-hearth furnaces and the consumption of refractories. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 6, pp. 34–38, June, 1997.     

Service of fused periclase refractories in linings of converter steel discharge holes

Conclusions Periclase and periclase-spinel blocks for lining the discharge apertures of steel melting converters made on the basis of fused periclase, in conditions at the Chelyabinsk Metallurgical Plant, have a resistance of 164–214 heats.The maximum wear resistance is possessed by periclase-spinel blocks made on the basis of fused periclase which is confirmed by the minimum wear during the heat (despite the relatively high initial porosity of the products), the number of thermal cracks, the extent of the working zone, and also the minimum quantity of fusible new formations in this zone.Important significance, in order to guarantee sufficient service, is attached to the rational selection of the diameter of the channel in the blocks. In conditions at the Chelyabinsk Plant it is desirable to try blocks with a channel diameter of 140 mm.Further increases in the resistance of periclase and periclase-spinel blocks, made on the basis of fused periclase, to the action of liquid and gaseous reagents of the melt should be achieved by improving the chemical and phase compositions and structure (for example, reducing the quantity and size of the pores).Translated from Ogneupory, No. 2, pp. 30–37, February, 1973.     

Research in the production of periclase-chromite refractories from beneficiated raw materials

Conclusions Laboratory and technological investigations of periclase-chromite refractories produced from beneficiated starting materials were carried out for the purpose of defining more precisely the required grainsize distribution of the starting components of the mix. The structural characteristics (the nature of the porosity, the development of a fragmented macro- and microstructure, and the formation of a direct intergranular bond) were analyzed in relation to the composition and grain-size distribution of the mix.The process of the formation of direct chrome-spinel-periclase bonds depends primarily on the firing temperature. The degree of the development of direct bonds can be regulated, however, by varying the composition of the mix in addition to which the process can be intensified by adding some of the chromite to the fine-ground part of the mix and increasing the proportion of coarse-grained chromite. An increase in the molding pressure and a decrease in the upper limit of the coarseness of the granular chromite also contribute to the formation of direct bonds.To ensure that the properties of the refractories, more particularly the thermal-shock resistance, are as required and that the standard specifications for the Cr₂O₃ content are met the proportion of the granular chromite in the mix must be 10–15% and that of the fine-ground component 5–10%. It will be necessary to verify the compositions in production conditions and to investigate the durability of the refractories in service.Translated from Ogneupory, No. 7, pp. 30–38, July, 1978.     

Service of basic refractories with additions of fused aluminomagnesia spinel in open hearth roofs

Conclusions We developed the basic technical parameters for making high-quality roof refractories, using electrofused spinel.Tests carried out in the roofs of large tonnage open-hearth furnaces, working with the use of oxygen, showed that the wear resistance of these refractories is 30% greater than that of ordinary periclase-spinel.Refractories containing 30% nonchromite spinel should be considered as the most promising.It would be desirable to produce and test large batches of these refractories in service.Translated from Ogneupory, No. 5, pp. 22–27, May, 1968.     

Periclase-chromite refractories from fused materials

Conclusions Experiments were carried out to obtain high-grade fused chromite-periclase. It is shown that during the melting of batch consisting of raw magnesite and chromite ore we eliminate the process of reducing the chromite ore to metallic ferrochromium, which adversely affects both the content of Cr₂O₃ in the fused material, and also the commerical appearance of the resulting refractories. We developed a technology for preparing periclase-chromite refractories with chromite-periclase constituents. The goods obtained possess good physicoceramic properties and a low content of silicates.The articles thus prepared were used to make the linings of the most critical parts of converters, Kivset unit in PZhV furnaces, which allowed an increase to be made in the duration of campaigns for these units of 1.5–2 times.Translated from Ogneupory, No. 3, pp. 41–44, March, 1985.     

Tarred magnesite refractories for oxygen converters

Conclusions A technology was developed for producing tarred magnesite refractories for lining steel converters. The average monthly life of the lining of the converters at the ZSMZ was increased to 624 heats (August 1970) with a maximum life of 662 heats.The tarred magnesite refractories based on MDPK-75 powder possess excellent resistance to hydration and have a high strength. Considering these facts and also in view of the high capacity of the refractories division of ZSMZ it is possible to transport tarred magnesite products over appreciable distances and to deliver them to converters in newly constructed factories.The outstanding feature of tarred magnesite refractories is their slight tendency to slagging, in connection with which the life of the tarred magnesite linings largely depends on the daily output of the converters. To reduce the consumption of refractories in each converter at the ZSMZ it is necessary to arrange more than 30 heats per day during the entire campaign period.Translated from Ogneupory, No. 1, pp. 4–9, January, 1971.