Fabrication of Ceramic Monoliths from Diatomaceous Earth: Effects of Calcination Temperature on Silica Phase Transformation
Abstract
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 1100ºC) for a period of 1 h. XRPD of the sintered samples at 1100ºC 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.
Copyright
Authors retain copyright of the published article and have the right to use the article in the ways permitted to third parties under the Creative Commons Attribution 4.0 International license. Full bibliographic information (authors, article title, journal title, volume, issue, pages) about the original publication must be provided and a link must be made to the article's DOI. This license allows to copy and redistribute the material in any medium or format, remix, transform, and build upon it for any purpose, even commercially, as long as appropriate credit is given to the original author(s), a link to the license is provided and it is indicated if changes were made.