Structure and properties of fused periclase and periclase-chromite blocks produced from beneficiated starting materials

Conclusions Fused periclase and periclase-chromite blocks containing a high proportion of highmelting oxides of magnesium and chrome were produced from beneficiated starting materials.The structure and properties of the periclase and periclase-chromite were analyzed zonewise in the blocks. The thickness of the block zones with a high content of magnesium oxide and the yield of high-quality periclase and periclase-chromite depend on the degree of purity of the chemical composition of the starting materials.The content of magnesium oxide is highest and the proportion of contaminating oxides low in fused periclase produced from chemically beneficiated Satkin magnesite, and in the monocrystalline subzones of the blocks. An increase in the proportion of chromite in the mix results in a higher porosity and in a higher content of spinel and ferrochrome in the fused material. The properties are optimal in the case of a periclase-chromite material from a mix containing 15–20% chromite.Translated from Ogneupory, No. 3, pp. 37–44, March, 1978.     

Refractories from fused periclase

Conclusions High-grade refractories can be produced from periclase containing at least 97% MgO by preparing a suitable grain size distribution with a vibro-ground component in the powder, molding in stages at high specific pressures (1500–2000 kg/cm²), and firing for 8 h or more at a high temperature (1750°C or higher).Translated from Ogneupory, No. 6, pp. 5–8, June, 1974.     

Magnesia refractories from Slovakian periclase

The Nikitovsk Dolomite Plant has produced an experimental industrial batch of magnesia articles based on Slovakian periclase. Results have shown that the articles made of Slovakian periclase correspond to the requirements of GOST 10888-76 for periclase-chromite refractories and GOST 4689-74 for periclase refractories. Translated from Ogneupory i Tekhnicheskaya Keramika, No. 5, pp. 27–30, May, 1996.     

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.     

Production of refractories from Chinese periclase

Periclase refractories from Chinese periclase are produced by the Chasovo-Yarsky Refractory Plant. The refractories have been tested with positive results at a number of metallurgical works, and specifications have been established for articles.Translated from Ogneupory, No. 1, pp. 21 – 26, January, 1995.     

The thermal conductivity of periclase and periclase — Spinel refractories

Conclusions It was established that it is possible to vary the thermal conductivity of periclase and periclase- spinel refractories within fairly wide limits by varying their phase composition and structure.Translated from Ogneupory, No. 3, pp. 48–50, March, 1975.     

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.     

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.     

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.     

Obtaining magnesia and periclase refractories from bischofite from the volgograd deposits

Conclusions Experimental work was carried out to obtain from bromine liquors of bischofite of the Volgograd deposits magnesium oxide, using low capacity industrial equipment for chemical purification of magnesite, including a recuperator, a tank-collector, a spray-reactor, a cyclone, an absorption column, spray traps, a vacuum pump, and a filter press.We worked out the parameters for the processes of boiling off the liquor, thermohydrolysis of the magnesium chloride, absorption of the hydrogen chloride with the production of hydrochloric acid, washing and leaching the hydrolytic magnesium oxide, and filtration of the resulting magnesium hydroxide. During the reprocessing of the liquor containing the bischofite, using this technology, without preliminary purification to remove boron and sulfates, we obtained magnesium hydroxide with a high purity level (98.5–99.5% MgO on the calcined weight).It is shown that the magnesium hydroxide thus obtained is a high-quality raw material for the production of fused and sintered periclase with a purity of 98–99.5% MgO. The technology of sintering, including carbonization of the magnesium hydroxide, hot palletizing without bond, and firing at moderate temperatures, ensures the production of densely sintered periclase. Tiles with inserts made from fused periclase of high purity with a clear anisotropic structure facilitate the casting of two heats through the gate valves.The results obtained can serve as the starting data for the development of specifications (TLZ) and planning the production of magnesium oxide from the debrominized bischofite liquors at the Volgograd site using the thermohydrolysis method. We need to solve the problem of the use of the 20% HCl that is obtained.Translated from Ogneupory, No. 1, pp. 27–30, January, 1988.     

Production of fused periclase from natural raw materials

Conclusions The properties and microstructure of periclase were studied. The influence of the original raw materials on the chemical composition and microstructure of periclase across the zones was established. In any raw material the minimum quantity of periclase impurities is noted in the single-crystal zone, but partial removal of impurities during fusion is not sufficient if the original raw materials do not possess the necessary purity. The use of chemically enriched Tal'sk magnesite improves the properties of periclase and the homogeneity of the block across the zones. It is necessary to carry out systematic research work on the preparation of raw materials and to elucidate the optimum parameters for fusion technology, ensuring improvements in the quality of the periclase.Translated from Ogneupory, No. 7, pp. 5–11, July, 1972.