Fast Method of Determining the Properties of Perlite Rock
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FAST METHOD OF DETERMINING THE PROPERTIES OF PERLITE ROCK N. V. Gurgenyan,1, 3 I. B. Khachanova,2 M. F. Kostandyan,1 A. E. Grigoryan,1 and N. K. Vardanyan1 Translated from Steklo i Keramika, No. 5, pp. 35 – 38, May, 2020.
To guarantee density uniformity of perlite rock, an extremely simple device for ascertaining the mass and volume of perlite rock directly at the rock deposit and determining the average density of the rock by using a nomogram was developed on the basis of Archimedes principle. The basic physical and mechanical properties closely correlated with the average density of rock are determined by a computational method using derived formulas. These studies make it possible to introduce the concept of grade and to stockpile the mined rock by density directly at the quarry. Key words: perlite, average density, physicomechanical properties, densitometer, Archimedes principle.
Perlites, a variety of natural glasses, are products of volcanic activity. The process leading to the formation of volcanic glasses is decisively influenced by the rate of cooling and chemical composition of lava. Since their composition is that of the primary (initial) magmatic melt, volcanic glasses occupy a special place among volcanic rocks. The subsequent rapid cooling of the glassy part of the lava flow results in its cracking and secondary hydration. The conditions of formation of perlite rocks are a result of many very complicated processes and bring in their wake the formation of structural non-uniformity in terms of both the extent of the flow and the depth at which it occurs. Also, to the indicated non-uniformity is added a non-uniformity associated with the contraction of the glassy mass accompanied by the formation of fissuring occurring as the igneous magmatic melts cool, thereby causing their volume to contract. In addition, the closer the perlite to the surface, the greater the fissuring is. The presence of different degrees of porosity and fissuring and, correspondingly, the amount of bound water and, as a result, the appearance of perlite varieties are responsible for the complex structural character of the perlite deposits. The indicated varieties, being products of one and the same magma, are distinguished by the physico-technical and technological properties. For this rea1 2 3
son proper attention must be given to exposing the technological features of perlites, since it is precisely the technological properties that determine their commercial value [1]. As a rule for each deposit the degree of uniformity of the raw material and the technological properties of perlite varieties as well as the fluctuation limits of the properties of the expanded product must be studied and the reasons for these fluctuations must be determined. In the Aragatskoe perlite deposit the range of variation of the physico-technical and technological properties of the rock is too wide, which is due to the presence of perlites with average density ranging from 600 to 2200 kg/m3. In addition the change in the average den
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