A new consolidation process for expanded perlite particles

Zeolitisation of perlite fines : mineralogical characteristics of the end products and mobilization of chemical elements

Novel mechanical behaviour of perlite/sodium silicate composites

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 SiO2 (72.45%), high in alkali metal oxides (4.21 wt.% K2O, 3.56 wt.% Na2O), 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.

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

Expanded perlite was used as a bleaching agent to remove dark colour from repeatedly used palm oil. It was found that non-activated expanded perlite was able to bleach the dark colour. The expanded perlite samples were also activated by acid and base before use. The base-activated perlite was able to bleach the dark colour of the repeatedly used palm oil but acid-activated perlite was not. The efficiency of base activated perlite was slightly better than that of non-activated expanded perlite. The bleaching mechanism could be explained mainly by physical adsorption. It was found that not only the colour of used oil was reduced but also the peroxide and acid values. Perlite could also adsorb the toxic compound benzo(a)pyrene from palm oil. Apart from measurement of the colour of oil, the peroxide and acid values as well as compositions of oil before and after bleaching were studied. Perlite samples before and after use were studied by scanning electron microscopy and Fourier transform infrared spectroscopy. The non-activated and activated perlite samples were also studied with X-ray diffraction.

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Carmelo Arcoraci

Papers

Physico-chemical characterization of perlite of various origins