Fractal Characteristics of the Pore Network in Diatomites Using Mercury Porosimetry and Image Analysis

Abstract

The complex pore space considerably affects the unique properties of diatomite and its significant potential for many industrial applications. The pore network in the diatomite from the Lower Miocene strata of the Skole nappe (the Jawornik deposit, SE Poland) has been investigated using a fractal approach. The fractal dimension of the pore-space volume was calculated using the Menger sponge as a model of a porous body and the mercury porosimetry data in a pore-throat diameter range between 10,000 and 10 nm. Based on the digital analyses of the twodimensional images from thin sections taken under a scanning electron microscope at the backscattered electron mode at different magnifications, the authors tried to quantify the pore spaces of the diatomites using the box counting method. The results derived from the analyses of the pore-throat diameter distribution using mercury porosimetry have revealed that the pore space of the diatomite has the bifractal structure in two separated ranges of the pore-throat diameters considerably smaller than the pore-throat sizes corresponding to threshold pressures. Assuming that the fractal dimensions identified for the ranges of the smaller pore-throat diameters characterize the overall pore-throat network in the Jawornik diatomite, we can set apart the distribution of the pore-throat volume (necks) and the pore volume from the distribution of the pore-space volume (pores and necks together).

Diatomaceous rocks of the Jawornik deposit (the Polish Outer Carpathians) - petrophysical and petrographical evaluatio

“…The best sorption properties possess massive, light-coloured diatomites BL that disintegrate into blocks, which are characterized by the lowest -Warchoł B., Stańczak G., Rembiś M., Toboła T. values of apparent density (1.20-1.26 g/cm 3 ) and the highest total porosity (38-43%). The pore structure of these rocks being dominated by macropores (60-71%) is the closest to that arrived at in the model of cylindrical capillaries with a high degree of complication, the conclusion also corroborated by high values of their fractal sizes (Stańczak et al 2015). Slightly worse are the sorption properties of dark-coloured diatomites also disintegrating into blocks (BD): apparent density 1.31-1.49 g/cm 3 , total porosity 33-39%, distinctly lower content of macropores 46-54%.…”

“…One of such novel applications is their capability to adsorb from water solutions various salts , mainly chlorides of sodium, magnesium and potassium. Initial results obtained in this range by the authors for various types of diatomites have revealed that these rocks have differing fractal dimensions of their pores, which must result from a variable ordering of the rock pore space and significantly affect the process of salt precipitation and an amount of the salt crystals formed (Stańczak et al 2015.…”