Particulars of Foam Glass Manufacture from Zeolite-Alkali Batch
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NCE FOR GLASS PRODUCTION UDC 666.189.3:549.67
PARTICULARS OF FOAM GLASS MANUFACTURE FROM ZEOLITE-ALKALI BATCH L. K. Kazantseva1 Translated from Steklo i Keramika, No. 8, pp. 3 – 7, August, 2013. The particulars of thermally activated foaming of zeolite-alkali batch are examined. It is found that carbonation of free NaOH with formation of hydrated sodium-carbonate — Na3[CO3][HCO3] × 2H2O — occurs in dry granular batch kept in air. The same process also occurs with NaOH occluded by in-crystalline pores and zeolite channels. Sodium carbonate contained in in-crystalline pores and zeolite channels comprises an additional source of foaming agent — CO2. This makes it possible to obtain foam glass with density 100 – 150 kg/m3 from zeolite-containing rocks. Key words: foam glass, zeolite-containing rocks, carbonation of NaOH, melting, pore-forming gas.
veloped are of high quality, the manufacturing plant was not put into operation because of the high cost of energy for firing and a lack of standard furnace equipment. In order to manufacture foam materials from natural raw material at the same temperature at which foam glass is obtained by the conventional powder technology from glass (750 – 800°C), materials that lower the melting temperature of the rock are added to the silica-containing compositions. To prepare foam materials from siliceous raw materials sodium hydroxide is, as a rule, used as a flux that not only lowers the melting temperature of the rock but also forms a source of foaming gas — hydrated sodium polysilicates [8]. It is shown in [9] that the chemical interaction of sodium hydroxide with the mineral components of ZR in moist batch differs from the interaction with siliceous rock — opoka. It was also established that hydrated sodium carbonate forms in air-cured dry zeolite-alkali batch. The particularities of ZR must be taken into account in order to develop a technology for fabricating foam glass from it. In the present article we present the results of an investigation of the effect of carbonation of alkali in zeolite-containing batch on its foaming intensity and the particularities of the foam glass obtained from zeolite-alkali batch.
Foam glass block and granular foam glass are biologically safe and the most durable heat-insulating construction materials. Even though it has definite advantages over other heating-insulating materials the few producers in Russia manufacture only granular foam glass using the simplest technology based on domestic equipment. The high cost of energy in glassmaking and limited stocks of cullet impede expansion of foam glass production. Methods of manufacturing foam glass from naturally occurring raw materials without preliminary melting are being developed in order to fill the shortage of heat-insulation materials. Siliceous (opoka, tripoli and diatomite) and aluminum-silicate rocks serve as raw materials. Of the great diversity of aluminum-silicate raw materials tufaceous zeolitecontaining rocks (ZR) are the most promising. In contrast to siliceous rocks many types of natur
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