Distribution of Arsene and Mercury in the Coal Seam k5 of the Kapitalna Mine, Donbas

Abstract

The aim of the research is to establish the characteristics of the As and Hg distribution, which belong to the main toxic elements of coal, in the coal seam k5 of the minefield Kapitalna (Krasnoarmiiskyi geological and industrial area of Donbas) and their main genetic factors. The applied methods include sampling coal from mine workings and from core-samples duplicates of wells from 1981 to 2014; identification of the inorganic part of the coal seam, macroscopically diagnosed by standard mineralogical methods as sulfide, silicate and carbonate fractions. According to textural and structural features, they are divided into groups of syngenetic and epigenetic origin; the mineral composition of these two groups was determined by optical microscopy using MIN-8 and MBS-9 microscopes and by X-ray diffraction analysis. Fractional analysis of the density of coal from duplicates of the original samples was carried out to identify the substance of the inorganic part of the coal seam; Arsenic and Hg contents were determined by atomic absorption analysis in the substance of all initial and final samples; normalization of all values of Hg and As concentrations and technological parameters of coal; statistical processing of all geochemical information using Excel 2016 and Statistica 11.0, which included correlation and regression analysis; calculation of the coefficients of affinity of Hg and As with organic matter, the coefficients of the reduced concentration of the investigated elements, the coefficients of the reduced extraction of these elements in the fraction of different densities; construction of maps of normalized isoconcentrates; changes in the regional component of normalized content and gradient of normalized content were performed using the program Surfer 11. We found a genetic link between high concentrations of As and Hg in the coal seam k5 of the minefield Kapitalna with tectonic features, the Central overthrust and associated zones of increased fracturing. The accumulation of As and Hg in the coal seam k5 of the minefield Kapitalna, bound to the organic component of the coal seam, is epigenetic. The practical significance of the work is that their high concentration in the high-density fractions of coal will lead to their gravitational accumulation in the waste.