The impact of modifications of the smectite-bearing raw materials on their thermal expansion ability
PBN-AR
Instytucja
Wydział Inżynierii Materiałowej i Ceramiki (Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie)
Informacje podstawowe
Główny język publikacji
EN
Czasopismo
Journal of Thermal Analysis and Calorimetry
ISSN
1388-6150
EISSN
1588-2926
Wydawca
Springer
DOI
Rok publikacji
2016
Numer zeszytu
2
Strony od-do
1153--1161
Numer tomu
123
Link do pełnego tekstu
Identyfikator DOI
Liczba arkuszy
0.7
Autorzy
Słowa kluczowe
EN
clays
thermal expansion
smectites
hot-stage microscopy
acid activation
Open access
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Creative Commons — Uznanie autorstwa
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Razem z publikacją
Streszczenia
Język
EN
Treść
The effects of modifications of the clay rocks containing smectite on their thermal expansion have been studied at the example of the claystones from DylA...gwka (Dynw Foothills, south-eastern Poland). Hot-stage microscopy was employed combining a dedicated procedure of digital image analysis. The chemical modification of three rock types from the DylA...gwka deposit included the treating with an addition of Na2CO3, activation with a H2SO4 solution, and firing at 560 A degrees C. X-ray diffraction and thermal analyses (DTA, TG) helped determine the impact of the modification processes on the structural changes in smectite, the major component of the rocks in question. The investigations into thermal expansion have shown that the clay rock varieties poor in CaO can be acid-activated with a significant improvement their expansion in comparison with such an ability of natural rock equivalents. It is a result of introducing silica into the melt that forms on heating the natural clay rock at high temperatures due to its presence of alkalis (Na2O and K2O). The silica, in turn, comes from the protonated silica gel generated due to the acid treatment of smectite-bearing rocks. The liquid phase (the melt) with a high viscosity may form a cover on the surface of granules of the product being fired and prevents the expulsion of gases into the ambience. An addition of Na2CO3 is favourable as it considerably lowers the firing temperature of the expanded product, both in the case of clay raw materials poor and rich in CaO. The acid activation of the latter variety (CaO-rich) is less effective because of the reaction of acid (H2SO4 used by the authors) with calcite; the mineral is decomposed, and at least part of the acid does not activate a clay material.
Cechy publikacji
original article
peer-reviewed
Inne
System-identifier
idp:103592
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