Chemical, mineralogical and structural features of native and expanded perlite from Macedonia

Abstract

The physico-mechanical, chemical and mineralogical characteristics of volcanic glass (perlite) from the Mariovo region (Macedonia) as well as the mineralogical changes that occur during its thermal treatment were investigated to demonstrate its utilization for industrial use. The native perlite was characterized by chemical analysis, X-ray powder diffraction (XRPD), infrared (IR) spectroscopy, thermal analysis (TGA/DTA), scanning electron microscopy (SEM-EDX), transmission electron microscopy (TEM), and solid-state NMR. The chemical examination suggests that the perlite represents an acidic volcanic rock with a high percentage of SiO 2 (72.45%), high in alkali metal oxides (4.21 wt.% K 2 O, 3.56 wt.% Na 2 O), with a loss of ignition 3.54 wt.%. Results from the XRPD indicated major amorphous behaviour, with low amounts of feldspars, quartz, and cristobalite. SEM examinations revealed glassy structure with presence of certain pores (dimensions ranging from 50-100 μm). The determined expansion coefficient was 20 times its original volume. XRPD of expanded perlite compared to the native perlite depicted new intensive peaks of cristobalite. SEM and TEM revealed irregular morphology with broken or ragged edges. On the basis of the chemical and mineralogical composition, the studied perlite is classified as an appropriate material suitable as ceramic flux to lower the sintering temperature.

Dehydroxylation of Perlite and Vermiculite: Impact on Improving the Knock-Out Properties of Moulding and Core Sand with an Inorganic Binder

“…1.6%). Compared to Macedonian perlite [ 48 ], which is considered rich in K 2 O and Na 2 O oxides (4.21% and 3.56%, respectively), Slovak and Hungarian perlite in particular has an even higher K 2 O content, even above 8%, in the case of the medium fraction (SP2) and above 7%—the smallest fraction (SP1).…”

“…In turn, the publication [ 19 ] showed that Greek perlite consists mainly of silicate glass (amorphous) and additives in the form of biotite, quartz, and feldspar. In the case of Macedonian perlite [ 48 ], XRD analysis showed the presence of a large amount of aluminosilicate amorphous and small amounts of crystalline, represented mainly by feldspar, quartz, and cristobalite. Feldspar is represented as K-plagioclase, Na-feldspar, and microcline.…”

A study on using expanded perlite with hydroxyapatite: Reinforced bio-composites

“…Perlite is an amorphous volcanic glass that has relatively high water content, typically formed by hydration of obsidian. 15 Moreover, perlite is able to expand to 4–20 times its original volume (EP, Expanded Perlite) upon heating, resulting in flakes with porosity greater than 95%. 16 Perlite is mainly composed of SiO 2 , Al 2 O 3 , K 2 O, Na 2 O, and combined water, although it may also contain TiO 2 , CaO, MgO, and Fe 2 O 3 at minor quantities depending on its origin.…”

Effect of Thermal Treatment of Clayey Diatomite at Temperature Range 800-1200°C

“…Republic of Macedonia is rich in inorganic materials with a wide spectrum of potential use and application [1][2][3][4]. Clayey diatomite, found in the vicinity of the Bitola power plant, takes a special place amongst non-metallic materials because it represents a mixture of diatomite and clay minerals [5][6][7][8][9][10][11][12][13][14].…”