Low-temperature synthesis of granular glass from mixes based on silica-alumina-containing components for obtaining foam materials

Abstract

It is established that granular glass can be obtained as an intermediate product for foam glass crystal materials based on common silica component (marshallite, diatomite, opoka) at temperatures not exceeding 900°C. It is shown that the use of granular glass with glass phase present in amounts greater than 80 wt.% makes it possible to obtain foam crystal glass materials with density up to 250 g/cm 3 .Ecologically safe and fireproof long-lived thermal insulation materials are now of practical interest in the construction industry. Foam glass materials meet all these requirements, but questions concerning expansion of the raw materials base for the production of such materials remain topical. There is a need to develop more readily accessible materials, for example, such as foam crystalline materials, which might be obtainable by a two-stage technology that includes synthesis of granular glass by means of low-temperature treatment of a mix with a certain composition (RF Patent No. 2326841).The objective of our work is to establish the possibility of obtaining granular glass as an intermediate product for foam glass crystalline materials based on common silica components at temperatures not exceeding 900°C.One condition for the formation of melt and a glass phase at relatively low temperatures is high dispersity of the main refractory components of the mix -silica. In a previous work we established that the silica size fraction is less than 100 mm [1]. The use of natural finely dispersed materials will expand the raw materials base for obtaining granular glass, since classic glassmaking is based on quartz sand with particle size 0.1 -0.5 mm. To preserve the chemical uniformity of a finely dispersed mix during heat-treatment and to increase its chemical activity the mix was first densified by rolling in a dish-shaped granulator and a granular glass was obtained in the form of partially fused porous granules [2,3].In addition to a high dispersity of the refractory material, an important condition for synthesis of the granular glass is the composition of the initial mix, which is based on three components: high-silica glass former, alkali (fluxing addition), and alkaline-earth, which affects primarily the viscous properties of the melt. To determine the component composition of the mix, the phase diagrams of the three-component system Na 2 O -CaO -SiO 2 were analyzed and a base composition was chosen for the glass. The concentration range of the glass was determined taking account of the following limiting requirements: the amount of the glass formers in the composition must exhibit high stability with respect to glass formation; the silicon oxides content of the glass must be no lower than 60 and no higher than 75% 4 ; the content of alkali metal oxide should be in the range 13 -22%, for which a glassy state obtains after the melt cools;the prescribed composition of the mix should lie near the boundary lines and eutectics, this corresponds to a lower melting temperature and the highest crystallization power of the me...

Using quartzofeldspathic waste to obtain foamed glass material

“…The work produced frit at a temperature of 800-900 °C based on a two-stage process developed for this purpose [14]. During the first stage, frit was synthesised by thermal processing of the initial batch from waste.…”

Peculiarities of the use of siliceous raw materials of the Russian Far East in the integrated pipeline protection

“…It is important to note that any large-scale production requires a local raw material base. The possibility of using amorphous raw materials in both silicate enamel technology [8][9] and foam glass technology [10][11][12][13] has been confirmed by a number of studies. Therefore, the presence of extensive deposits of amorphous silica [14] and silica-bearing rocks in Eastern Siberia and the Far East, as well as the possibility of synthesizing amorphous silica from quartz-containing raw materials [15] makes it possible and necessary to develop the proposed technology for integrated protection of pipelines in the evolving network of oil and gas pipelines of the Russian Far East.…”

Non-destructive testing of amorphous component density in foam nature-like materials

“…4 для построения двух зависимостей на одном графике предлагается методом нормировки получить два независимых графика. Такой метод нормировки уже давно используют, пересчитывая все в процентах [9,10]. В нашем же случае все измеряемые величины были пересчитаны в безразмерные (в доли).…”