A study of the crystalline structure of vermiculite from the Tebinbulak deposit

Abstract

The results of studies of vermiculite rock from the Tebinbulak deposit are given. It is established that this vermiculite rock consists of biotite mica minerals. The crystalline lattice of these minerals contains interpack water known as zeolite water, which is responsible for swelling of the rock in heating. Vermiculite rock fired at 200 -900°C is capable of absorbing water, i.e., of rehydration. This is important in using swelled vermiculite in the production of fire-retardant paints. The compositions of fire-retardant paints and the results of their testing for heat resistance according to GOST 30402 are given. It is established that all the developed mixtures impart fired-retardant properties to timber.The development of new technologies and promising materials make it necessary to expand the list of available raw materials. Among the promising products are fire-retardant paints that are used in different sectors of industry. Swelled vermiculite is widely used as a filler in fire-retardant paints. Such paints are not produced in the Republic of Uzbekistan and have to be imported from other countries. The development of a large deposit of vermiculite ore in Tebinbulak will make it possible to start the production of fire-retardant paints in Uzbekistan.The vermiculite ore from the Tebinbulak deposit belong to biotite mica. It should be noted that very few varieties of vermiculite rocks belong to biotite mica. For instance, the large Kovdor deposit in Russia mainly consists of phlogopite mica; therefore, all previous studies of vermiculite have been performed on these phlogopite rocks. The present study has been carried out on the biotite vermiculite rock in order to determine its applicability for the production of fireproof paints. Vermiculite samples taken from the Tebinbulak deposit have a dark gray color and comprise mainly biotite, hydrobiotite, and vermiculite minerals. The chemical composition of vermiculite samples is given in Table 1.The crystal-optical properties of vermiculite ore were determined using a microscope in immersion liquids for the biotite -vermiculite series (and for rehydrated vermiculite as well); the refraction index N*m and its variation under firing samples to 1000°C was estimated as well. As the degree of hydration grows, we observe a decrease in the refraction index from biotite to vermiculite (Table 2), which was earlier reported in studies performed on phlogopite -vermiculite minerals [1]. The refraction index presumably decreases due to the increasing content of water in mica, which is typical of many other minerals as well [2,3]. As the firing temperature grows, the refraction index perceptibly increases. Thus, N m in biotite slightly grows when fired to 800°C and then abruptly grows from 1.595 to 1.645 when fired to 1000°C. A possible reason for the increasing refractive index in biotite is the transition of Fe 2+ to Fe 3+ , which is corroborated by the color of biotite changing from dark gray to gray-brown, which is caused by oxide iron above 800°C [4].The refractive index N...

Enhancement and mechanism of vermiculite thermal expansion modified by sodium ions

“…Due to the multiple action of natural weathering, hydrothermal action, and percolating ground waters in geological processes, vermiculite is formed with a layered structure containing plenty of interlayer water. [4][5][6] When heated during a short period of time, vermiculite can rapidly expand or exfoliate many times its original thickness because of the interlaminar water vapour pressure. 7,8 Because of numerous excellent properties, such as low density, low thermal conductivity, high temperature resistance, and high thermal stability, expanded vermiculite is usually used as a thermal insulating material.…”

A new data set of soil mineralogy for dust-cycle modeling

“…Therefore, we assign calcite to both the clay and silt fractions. Journet et al (2008), Seabaugh et al (2006), Taylor et al (2000), Gold et al (1983), Robert (1973), Carroll 4.3 % andStarkey (1971), Deer et al (1962) Smectite Journet et al (2008), Ramesh et al (2007), Bayrak (2006), Garcia-Rodriguez et al (1995), Yilmaz (1981), 2.6 % Osthaus (1956) Kaolinite Journet et al (2008), Temuujin et al (2001) 0.23 % Chlorite Cathelineau and Nieva (1985), Kramm (1973) 12.5 % Vermiculite Andronova (2007), Seo et al (2005) 6.7 % Feldspars Journet at al. 20080.34 % 7.…”