Production of refractory concretes and practice in using them in glass-melting aggregates

Abstract

The refractory concrete items and refractory pastes used in glass-melting aggregates manufactured by Semiluki Refractory Factory are presented. Their specifications are reported -strength, density, porosity, etc.In glass production, refractory concretes -unfired composite materials -have already been used for more than 30 years. Use of a new generation of concretes -low-cement concretes -has expanded in the past five years. The cement content in them is a maximum of 8 -10%, which allows using a wide range of fillers -from corundum to chamottewithout worsening the high-temperature properties. Even concretes of chamotte composition have better high-temperature properties than the indexes for traditional fired chamottes due to the minimal content of calcium oxide bound in high-melting hexaaluminate. In addition, such a low cement content in the new concretes reduces to the minimum the negative effect of the destructive processes that take place in dehydration and recrystallization of the calcium hydroaluminates in cement, which are the cause of the well-known weakening interval in traditional concretes.In modern furnace building, the small-piece lining is being replaced by the monolithic lining and assembly of prefabricated slab articles. For the users, this is freedom of design using articles of different shapes and sizes, reducing the number of joints in the refractory lining due to the use of large blocks, and mechanization and continuity of assembly of the lining due to the accuracy of the geometric dimensions of the refractories. Refractory production is changing from semidry molding technologies to vibromolding of articles from low-cement thixotropic pastes.The low-cement concrete mixture is thixotropic, i.e., it acquires fluidity in vibration, which allows it to fill a concreting volume (mold) of any configuration. In vibration, the particles of the material are compacted without destruction and deformation, in contrast to the method of semidry molding, where elastic expansion of the particles causes the appearance of internal stresses and perturbation of the continuity of the body of the stock, i.e., crack formation. This is a very important reason why semidry molding is being replaced by vibrocasting, especially in production of large items.Due to vibromolding, the structure of concretes becomes microporous, and the pores have a round structure and basically do not communicate, so that the channel porosity of concrete articles is much lower than for fired rammed articles. How are the properties of concrete and traditional fired refractory articles comparable? Refractory concretes are more thermostable and less heat-conducting than fired items of the corresponding composition and have a lower CLTE [1]. The drawbacks of concretes are always the low abrasion resistance. Technology for production of high-quality cements and materials for the matrix constituent of concretes

Application of IR spectroscopy for studying structure formation in low-cement concretes

“…Glass production is no exception. At the present time, low-cement concrete (LCRC) with an aluminosilicate composition with fillers from the chamotte, mullite-alumina, mullite, and mullite-corundum groups are most widely used in glass production lines [3].…”