The raw diatomaceous earth from the vicinity of Bitola (North Macedonia)
showed low bulk density (0.61-0.69 g/cm3), high-water absorption (75-81%)
and porosity (66- 72%). The chemical composition was determined with ICP-MS,
revealing the following results for the diatomaceous earth: SiO2 (63.69
wt%), Al2O3 (11.79 wt%), Fe2O3 (5.95 wt%), MnO (0.15 wt%), TiO2 (0.65 wt%),
CaO (1.51 wt%), MgO (2.24 wt%), P2O5 (0.13 wt%), K2O (1.64 wt%), Na2O (0.93
wt%), LOI (11.21 wt%). XRPD data of the examined sample of clayey diatomite
mainly depicted crystalline behavior with a small presence of amorphous
phase. The crystalline mineral phases mainly comprise: silica (quartz),
feldspars (plagioclase), mica (muscovite), chlorites and dolomite. SEM and
TEM results show cased presence of micro- and nanostructures with pores
ranging from 250 to 600 nm. The clayey diatomite was sintered at three
temperatures (900, 1000 and 1100?C) for a period of 1 h. XRPD of the
sintered samples at 1100?C showed certain thermal stability and formation of
new phases (mullite and tridymite) that makes the analyzed diatomaceous
earth suitable for production of various types of ceramic, construction and
thermal insulating materials.
Trepel is the local name for a mixture of diatomaceous earth and clay minerals. It represents a greyish, soft, very light, weakly cemented, fine biogenetic sedimentary rock. The studied material is taken from the vicinity of Bitola city (Republic of Macedonia). Here, trepel was treated up to three temperature intervals (800, 1000 and 1200C) for a period of 1 hour. The X-ray powder diffraction results indicate the presence of both an amorphous phase and the following crystalline phases: quartz, feldspars (plagioclase), mica (muscovite) and chlorites. The results of SEM analysis revealed skeletons of alga Diatomeae with nano-pores. By thermal treatment of the samples, a gradual change in color as well as higher bulk density and compressive strength was observed. The increase of the temperature, in addition, affected the mineralogical composition and increased the presence of the amorphous phase (aluminasilicate glassy phase). SEM results of the thermally investigated samples depicted morphological changes expressed by shrinkage of the pore diameters in comparison to the initial material. The major and minor constituents were established by chemical analysis revealing the following chemical composition of raw trepel: SiO2 (63.65 wt%), Al2O3 (11.76 wt%), Fe2O3 (5.93 wt%), MnO (0.13 wt%), TiO2 (0.63 wt%), CaO (1.42 wt%), MgO (2.22 wt%), P2O5 (0.11 wt%), K2O (1.63 wt%), Na2O (0.92 wt%), LOI (11.50 wt%).
Trepel is the local name for a mixture of diatomaceous earth and clay minerals. It represents a greyish, soft, very light, weakly cemented, fine biogenetic sedimentary rock. The studied material is taken from the vicinity of Bitola city (Republic of Macedonia). Here, clayey diatomite was treated up to three temperature intervals (800, 1000 and 1200 o C) for a period of 1 hour. The X-ray powder diffraction results indicate the presence of both an amorphous phase and the following crystalline phases: quartz, feldspars (plagioclase), mica (muscovite) and chlorites. The results of SEM analysis revealed skeletons of alga Diatomeae with nano-pores. By thermal treatment of the samples, a gradual change in color as well as higher bulk density and compressive strength was observed. The increase of the temperature, in addition, affected the mineralogical composition and increased the presence of the amorphous phase (aluminasilicate glassy phase). SEM results of the thermally investigated samples depicted morphological changes expressed by shrinkage of the pore diameters in comparison to the initial material. The major and minor constituents were established by chemical analysis revealing the following chemical composition of raw clayey diatomite: SiO 2 (63.65 wt%), Al 2 O 3 (11.76 wt%), Fe 2 O 3 (5.93 wt%), MnO (0.13 wt%), TiO 2 (0.63 wt%), CaO (1.42 wt%), MgO (2.22 wt%), P 2 O 5 (0.11 wt%), K 2 O (1.63 wt%), Na 2 O (0.92 wt%), LOI (11.50 wt%).
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