The influence of porosity on the release of water from perlite glass by thermal treatment

Varga, P.; Uhlík, Peter; Lexa, Jaroslav; Šurka, Juraj; Bizovská, Valéria; Hudec, Pavol; Pálková, Helena

doi:10.1007/s00706-019-02410-w

Cited by 5 publications

(2 citation statements)

References 44 publications

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“…Based on the analysis of the chemical composition, it was found that the size of the Slovak perlite ore fraction influences the content of some oxides. As indicated in the work [ 46 ], the K 2 O/Na 2 O ratio is particularly important from the point of view of the expansion susceptibility of perlite ore. As shown in Table 4 , the K 2 O/Na 2 O ratio for the smallest fraction (SP1) is 4.17, for the average 4.36, and for the coarsest 1.20. On the other hand, for the Hungarian perlite ore, which, according to the grain composition analysis, has the main fraction collected on the same sieves as the medium-grained perlite (SP2), the K 2 O/Na 2 O ratio is 2.83.…”

Section: Resultsmentioning

confidence: 99%

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

et al. 2021

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The article presents the results of research aimed at examining the type of swelling material introduced into moulding or core sand to improve their knock-out properties. Tests on Slovak perlite ore (three grain sizes), Hungarian perlite ore and ground vermiculite (South Africa) were carried out. For this purpose, thermal and structural analyses (FTIR—Fourier Transform Infrared Spectroscopy), a chemical composition test (XRF-X-Ray Fluorescence), phase analysis (XRD—X-Ray Diffraction), and scanning electron microscopy (SEM—Scanning Electron Microscope) as well as final strength tests of moulding sands with the addition of perlite ore and vermiculite were carried out. The results of thermal studies were related to IR (Infrared Spectroscopy) spectra and XRD diffractograms. It has been shown that the water content in the pearlite ore is almost three times lower than in vermiculite, but the process of its removal is different. Moreover, the chemical composition of the perlite ore, in particular the alkali content and its grain size, may influence its structure. The phenomena of expansion (perlite) and peeling (vermiculite) have a positive effect on the reduction of the final sand strength and eliminate technological inconveniences (poor knocking out) that significantly limit the wide use of moulding sands with inorganic binders.

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Section: Resultsmentioning

confidence: 99%

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

et al. 2021

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“…Upon gradual heating of perlite samples to a rate that does not exceed 20 • C•min −1 , water removal occurs over a broad temperature interval, ranging from 100 • C to 900 • C, since different amount of thermal energy is required to release superficially adsorbed water, molecular water trapped in large pores, H 2 O bounded by capillary forces in micropores, nanopores and microcracks and for structurally bounded OH groups in the glass itself [26,34,[37][38][39]. It should be noted that, these heating times are orders of magnitude greater than the expansion times, however, prolongation of heating allows easier sample weighing, and observation of physicochemical and structural alterations that the grain experiences during the thermal treatment.…”

Section: Perlite Expansion Mechanismmentioning

confidence: 99%

Insights in the Physicochemical and Mechanical Properties and Characterization Methodology of Perlites

Angelopoulos

2024

Minerals

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Perlite is a volcanic glass that, under thermal treatment, expands, producing a highly porous and lightweight granular material which finds application in the construction, horticulture, insulation and other industrial sectors. Proper control of the feed properties and the expansion conditions allows the production of purpose-oriented grades, while the primary evaluation of its appropriateness for use in each sector is performed by the proper characterization of relevant physical, thermal or/and mechanical properties. However, due to its extreme fineness, low density, and friability, most of the available characterization methods either fail in testing or provide erroneous results, while for certain properties of interest, a method is still missing. As a consequence, the way towards the evaluation of the material is rife with uncertainties, while a well-defined methodology for the characterization of the critical properties is of practical importance towards the establishment of a pathway for its proper analysis and assessment. This article presents the available methodology for determining the main properties of interest, i.e., the size and density, water repellency/absorption and oil absorption, the microstructural composition, crushing and abrasion resistance and isostatic crushing strength, and also sampling and size reduction processes. The issues raised by the application of existing methods are analyzed and discussed, ending up to a proper methodology for the characterization of each property, based on the long-term experience of the Perlite Institute. The study is supplemented by updated insights on ore genesis, physicochemical properties, mineralogical composition and the expansion mechanism, as background information for the sufficient comprehension of the nature and properties of perlite.

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Re-evaluation of perlitic textures and fracture behavior in silica-rich volcanic rocks

Meier,

Breitkreuz,

Groß

et al. 2023

Bull Volcanol

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The influence of porosity on the release of water from perlite glass by thermal treatment

Cited by 5 publications

References 44 publications

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

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

Insights in the Physicochemical and Mechanical Properties and Characterization Methodology of Perlites

Re-evaluation of perlitic textures and fracture behavior in silica-rich volcanic rocks

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