Experimental data on thermal conductivity of packed beds composed from various refractory particles (corundum, silica, magnesia, baddeleyite, yttrium oxide, spinel) obtained in the temperature range 400-2000 K in various gases are presented. It is found that thermal conductivity of a bed composed from crushed refractory particles may change after the first and subsequent heatings. This occurs as a result of smoothing of particle surfaces and decreasing of contact heat barrier resistances between the granules. The influence of smoothing is most significant for beds composed from particles with sizes below 2 mm. In polydisperse beds, containing micrometer-size particles, sintering processes were found to occur at temperatures above 1600 K. This led to a sharp increase of the bed thermal conductivity. In regimes where sintering did not take place, decreasing of particle size resulted in a decrease of the effective thermal conductivity. This is attributed to the increased number of contacts between the particles and the scattering of thermal radiation.

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A major requirement imposed on steel melting production under conditions of intensification of the processes in the iron and steel industry is the production of high quality metal, which to a large degree is determined by the teeming conditions. The appearance of leaks of metal in teeming of steel from ladles with slide gates unavoidably leads to poorer ingot quality in top teeming into molds. In this case it is difficult to overrate the value of reliable operation of the slide gate, the final link in the process of teeming steel from ladles. With observation of the temperature conditions of the metal being teemed and of the method of preparation of the ladles and assembly of the slide gates one of the reasons for breakdowns in the teeming conditions is failure of slide plates.An increase in the operating reliability of slide plates is an important problem for refractory personnel.Its solution is impossible without a clear concept of the mechanism of a failure of plates in service. However, in the literature there is insufficient information on the mechanism of wear of slide plates.In many steel plants in the USSR and abroad plates of high-alumina composition are used. Therefore the purpose of this work is a study and analysis of the wear of high-alumina plates in service, construction of a model of the wear and failure of the refractories, and determination of the resulting requirements for plate quality. A solution of this problem makes it possible to determine means of improving the technology for high-alumina composition plates.Refractory plates of types KP-95 and MKTsP-82 to Technical Specification 14-8-385-81 and also plates of CZ* composition were investigated. The investigations were made in the AllUnion Refractory Institute and under the conditions of Western Siberia Metallurgical Combine. The characteristics of the refractory materials of these plates and the method of their production were given earlier [1][2][3][4].It is desirable to note only the main differences in their structure -the quantity and character of distribution of the glassy phase. For example, the KP-95 plates are made up of crystals of corundum between which the glassy phase is uniformly distributed. The quantity of glassy phase (7-8 wt.%) and the character of its distribution are similar in the grain and binder portions of the charge [2, 4].In the MKTsP-82 plates the same quantity of glassy phase is concentrated in the grains of the filler while in the binder portion of the charge the glassy phase is present only in the form of separate drop inclusions [2].The structure of the KTsMKhP-90 plates and of the inserts of the MKSPK-90 plates is characterized by the minimum (about 1.3%) content of glassy phase in the form of separate drop inclusions in the grains of the filler and in the binder [4].Such a distribution of the glassy phase in the plates is the result of technical features of their production. The KP-95 plates are produced according to a briquette method *At present, plates of CZ composition are designated type and composite ...

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