Mechanochemical treatment of talc

abstract

English

With the development of blended cements and alkali activated materials, the importance of an use of pozzolanic materials constantly grows. One of the most frequently used pozzolanic materials is metakaolin, a product of thermal dehydroxylation of kaolinite. It is not possible to prepare a meta stable phase of talc, the most common magnesium silicate clay mineral, this way, due to its quick recrystallization to enstatite over 800 °C. On the other hand it was found out that a preparation of this phase, called meta talc, is possible via mechanochemical activation, a process where a raw material (talc in our case) is exposed to high level of mechanical energy. This process is typically carried out in high energy mills (vibrating mill, planetary mill, attritor). This contribution is focused at an investigation of an effect of milling time in a vibrating mill on structure and properties of talc Luzenac H70. A progress of loss of crystallinity during mechanochemical activation was studied by X-Ray diffractometry. Simultaneous TG-DTA was used for studying of dehydroxylation progress and thermal behaviour of mechanochemically activated talc. It was found out that an amorphisation of both main phases of talc sample used in this work, talc and clinochlore, makes its biggest progress in first 10 minutes and with increasing time the amorphisation rate decreases. TG curves showed that a mass loss during heating increases with prolonged milling. DTA curves indicate that prolonged high energy milling leads to structure changes like dehydroxylation of phyllosilicate sheets and creation of water coordinated and adsorbed on talc surface.

talc, mechanochemistry, vibrating mill, XRD, TG-DTA

BEDNÁREK, J.; HAVLICA, J.

23. 3. 2017

Vysoké učení technické v Brně, Fakulta chemická, Purkyňova 464/118, 602 00, Brno

Brno

978-80-214-5488-0

Studentská odborná konference Chemie je život 2017. Sborník abstraktů

78

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