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.