Burning of briquette to chamotte in a tunnel furnace

The possibility of producing chamotte by burning briquettes of semidried pressed kaolin from the Angrenskoe deposit in charges up to 1.5 m high is investigated.Translated from Ogneupory, No. 5, pp. 29 – 31, May, 1994.     

Strength properties of chamotte concretes based on phosphate binders

Conclusions The authors have investigated the strength properties of chamotte concretes based on phosphate binders over a wide range.They have shown the dependence of the compressive strength of the concretes on the type of phosphate binder used, the heat treatment temperature of the concrete, and its test temperature. Maximal compressive strength is exhibited by concretes roasted at 1450°C.They have established a relation between the physicochemical transitions taking place in a phosphate binder during heating and the strength characteristics of the concrete.Simultaneous introduction of phosphate binder and clay to the extent of 10–20% into chamotte concretes increases their strength at 20°C and during heating.Translated from Ogneupory, No. 6, pp. 32–36, June, 1979.     

Tunnel-type kiln for firing chamotte parts with hot air feed to burners

Conclusion Experience in operating tunnel-type No. 2 at the Borovichi Combine, designed by the All-Union Institute of Refractories, has confirmed the advisability of feeding hot air to the burners through injectors, and spacing the burners in the high-temperature zone at intervals of 1.5 m, leaving corresponding gaps in the batching on the car.Research work and adjustment are required in order to reduce the temperature of the parts coming from the kiln, to level the temperature throughout the length and width of the batching, and also to cut down heat losses; it is absolutely essential to handle cars with wares at elevated temperatures correctly.     

Methods of eliminating expansion and embrittlement during firing of products based on chamotte from rotary furnaces

Conclusions We established the mechanism of expansion in the firing of articles made on the basis of grog obtained from rotary furnaces. The cause of the expansion is the incompleteness of the process of vitrification (sintering) during rapid heating, giving rise to the formation of closed pores. During repeat firing the expansion of the gaseous phase trapped in the closed pores gives rise to an increase in the volume of the grains.The expansion of the grog may be eliminated or substantially mitigated by breaking up the closed pores by means of an addition to the original batch of nonplastic materials or kaolins which are not prone to form expanding grog.Translated from Ogneupory, No. 4, pp. 36–41, April, 1967.     

Effect of chamotte grain size on the properties of foamed insulating products

Conclusions The fineness of the mineral constituent of the batch is especially important in the production of foamed insulating refractories, determining the stability of the foam mass, and the strength of the refractory, which are improved with an increase in the ehamotte's content of finely dispersed fractions, and a reduction in the maximum grain size.Translated from Ogneupory, No. 1, pp. 56–59, January, 1972.     

Effect of microsilicon on the properties of heat-resistant castable with chamotte scrap filler

Chamotte scrap with an elevated water absorption is used as a filler in low-cement heat-resistant concretes (castables) of the new generation. The studied castable compositions contain from S to 16% microsilicon. The effect of heat treatment of the castable to up to 1300°C on the change in its density, the ultimate compressive strength, deformation, and the speed of an ultrasonic pulse is determined. It is shown how microsilicon affects the setting of mortar and a hypothesis is made on the mechanism of the interaction of thin-phase components in the studied composition.     

Intensification of sintering and properties of kaolin chamotte parts

Refractories and Industrial Ceramics - We discovered certain individual additives (MgO and MnO2) and also some combined additives which have a beneficial effect on the sintering of kaolin. It is...     

Microstructure and phase composition of the crust formed on the surface of the lining of a rotating kiln in firing of mullite-corundum chamotte

Conclusions Samples of the crust formed on the lining of a rotating kiln in firing of mullite-corundum chamotte were investigated. The crust consists of a mullite-glass mass and grains of corundum. Depending upon the medium in the furnace it has different structures, phase compositions, and colors.The white crust is less sintered and has a porous and loose structure. The size of the pores is up to 2.4×1.36 mm. The structure of the black crust is monolithic porous with a pore size up to 1.2×0.47 mm. The rust-colored crust has a coarse porous structure and a pore size of up to 1.7×0.9 mm.The crust is nonuniform in phase composition. The greatest mullite content is in the white crust and the least in the rust-colored.Translated from Ogneupory, No. 8, pp. 58–60, August, 1985.     

Influence of structural and phase conversions on the thermomechanical properties of chamotte concrete based on high-alumina cement

Conclusions The dehydration of the calcium hydroaluminates and aluminum hydrates when the concrete is heated causes the binder to lose strength and results in the formation of a porous structure.The structure of the cement block depends on the fineness of the cement. During heating at 1100°C, two processes develop in the binder, viz., solid-phase diffusion sintering accompanied by shrinkage, and coalescence of the pores.The reaction of the cement with the chamotte results in the formation of low-temperature minerals in the form of calcium aluminosilicates, the consequence being that liquid-phase sintering continues accompanied by considerable shrinkage.Above 1200°C and especially above 1300°C a large amount of liquid phase is formed in the concrete and dissolves the crystalline minerals (calcium aluminosilicates, mullite, cristobalite, and corundum).The peak temperature at which the chamotte concrete based on high-alumina cement can be used is 1350°C.Translated from Ogneupory, No. 1, pp. 52–57, January, 1977.     

Improving the structure and properties of a refractory castable containing porous chamotte fillers

The potential use of a porous (20%) chamotte filler in a low-cement castable with an integrated matrix is considered. Results of a study of the properties of conventional, medium-cement, and low-cement castables are presented.Translated from Novye Ogneupory, No. 7, July, 2004, pp. 46–49.