Formation of a pore-forming gas source by wetting natural aluminum-silicate with NaOH solution

Kazantsev, L. K.; Zheleznov, D. V.; Seretkin, Yu. V.; Rashchenko, Sergey V.

doi:10.1007/s10717-013-9478-9

Cited by 9 publications

(11 citation statements)

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“…A particularity of foam-glass manufacture from zeolitealkali compositions is carbonation of alkali in dry batch when held in air [9]. X-ray diffractometry shows hydrated sodium carbonate in such batch -trona (Na 3 …”

Section: Resultsmentioning

confidence: 99%

“…In [9] it is established that when ZR powder is wetted with a water solution of sodium hydroxide the NaOH transforms only partially into a bound state -water sodium polysilicates (Na 2 O × mSiO 2 × nH 2 O). A large part of the NaOH is found in a free state in batch with a film distribution over the powder particles.…”

Section: Resultsmentioning

confidence: 99%

“…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.…”

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confidence: 99%

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Particulars of Foam Glass Manufacture from Zeolite-Alkali Batch

Kazantseva

2013

Glass Ceram

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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 -Na 3 [CO 3 ][HCO 3 ] × 2H 2 O -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 -CO 2 . This makes it possible to obtain foam glass with density 100 -150 kg/m 3 from zeolite-containing rocks.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 natural zeolites are capable of foaming at the natural melting temperature -1100 -1200°C. The nature and mechanism of thermally activated foaming of natural zeolites have been studied and are presented in [1 -4]. Technologies for fabricating different types of porous construction materials -block and granularunder the trademark Sibeerfoam â from zeolite-containing nature raw materials at the natural melting temperature of ZR have been developed [5 -7]. Even though the foam materials obtained by means of the high-temperature technology developed 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 glas...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Particulars of Foam Glass Manufacture from Zeolite-Alkali Batch

Kazantseva

2013

Glass Ceram

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“…Heating mixtures of siliceous rock and NaOH in the temperature interval 200 -800°C also results in foaming and is accompanied by a density reduction of the specimens [15]. The density starts to increase at temperatures 800°C and higher.…”

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confidence: 99%

“…For example, hydrothermal leaching of opoka at 90°C increases the content of dissolved SiO 2 , which intensifies pore formation and results in a density reduction of the specimens foamed at 850°C as compared with the samples without hydrothermal treatment [15].…”

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Diatomites in Granular Foam-Glass Technology

2014

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The present status of research on the production of foam-glass from siliceous rock by the one-step scheme is examined. The main technological principles of the experimental production of granular foam-glass based on diatomites are formulated. The production process is described and the main properties of the 5 -10 mm fraction as compared with the normative requirements are presented.The simplification and cost reduction of the technology of granular foam-glass, which is an environmentally clean material in high demand, are problems of current interest [1 -5]. The trends in this field consist of the following.The process of obtaining foam-glass in the form of granules is the most easily implementable technology for producing foam-glass in the form of a building product ready for use.In the heat-treatment process the cross section of a granule is subject to smaller temperature gradients than foamglass blocks, which simplifies the foaming and annealing processes. A tunnel furnace many meters long and a stock of special molds are not required. Granular foam-glass has a wide range of applications, starting from heat-insulation fills and fillers in light concretes to thermal stabilization of the foundations of engineered structures. It is especially important to obtain fine granular foam-glass for developing new materials in order to impart special properties to them.

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