A new determination method for coal metamorphism degree

This paper reports determining the grayscale intensity of macerals in the coal lump polished sections oriented along and across the layering of three main groups of sub-bituminous, high volatile bituminous, low volatile bituminous coals. All measurements have been performed in white, red, yellow, green, blue light. The influence of all selected factors and most of their combinations on grayscale intensity is reliable; the most pronounced effects are established for the optical filter color and the maceral type. Comparative analysis of the grayscale intensity data array with the spectra of full reflectance in the visible region and the coefficient of diffuse reflection in the white light of fine powders of the same samples has been carried out. Green light yields a very dark image of vitrinite and liptinite with the grayscale intensity approaching zero. In two of the six samples, the reflectance level of inertinite in yellow light is significantly higher than the grayscale intensity of white light. This anomaly is associated with a hypsochromic shift in the inertinite maximum absorption. The approach used is an alternative method for quantifying the relative changes in reflectivity and position of the diffuse spectral minimum without applying a microspectrometer.

Section: Introductionmentioning

confidence: 96%

Comparative analysis of optical properties of coals by petrography and spectroscopy methods

Bezruchko

Baranovskyi

Balalaiev

et al. 2022

“…The work [9] proposes a new method for determining the degree of metamorphism based on the index of gray shade intensity (GI) for microphoto images of lump sections in coal preparations with subsequent digital computer processing. Subsequently, the spectral characteristics of this method were refined [10].…”

Section: Introductionmentioning

confidence: 99%

Fractal dimension of the morphology on differently oriented surfaces of coal preparations

Bezruchko,

Pymonenko,

Baranovskyi

2024

Choosing the surface of a lump section was justified to determine the degree of metamorphism by the index of gray shade intensity. The main method is optical spectroscopy using a video-optical complex MBI-11, NB 200 with subsequent digital computer processing and calculation of the fractal dimension (Scope photo software) of microphoto images of coal matter preparations by lump sections. The values for the index of gray shade intensity of photographic images of surfaces (section, bedding, cut) for lump sections based on samples of coals of various grades were analyzed. It has been established that the average values of the degree of metamorphism indices for different surfaces of the preparation differ, which is confirmed by low correlation coefficients: 0.585 (section-bedding), 0.666 (section-cut), 0.462 (cut-bedding). It has been found that the fractal dimension, which characterizes the complexity of the morphology of the surfaces under study, reflects an increase in the amount and orderliness of hydrocarbons associated with a change in the degree of metamorphism. It was proven that its most natural decrease related to an increase in the degree of metamorphism, is observed on surfaces perpendicular to the bedding (section).

“…The Institute of Geotechnical Mechanics of the National Academy of Sciences of Ukraine has developed a new method for determining the degree of metamorphism (coalification) of a coal substance [4], the essence of which is the use of optical microscopy of polished sections of coal samples, followed by digital processing of the data obtained. For the first time, to characterize the degree of metamorphism of coals, digital processing of photographic images of polished sections of coal samples has been applied using a new indicator of the intensity of shades of gray color of macerals (Grey Intensity -GI).…”

Section: Introductionmentioning

confidence: 99%

Petrographic and technological aspects of improving the methodology for alternative determination of the degree of carbonification

Bezruchko

Baranovskyi

2023

The methodology for determining the earlier proposed indicator of the intensity of the shade of grey (Grey Intensity) as an alternative to the normative indicator of the reflectivity of vitrinite has been improved. The values of this indicator have been analyzed in the polished section specimen on the surfaces of the cut, layering, and tangential sections along the macerals of all three groups (vitrinite, liptinite, inertinite). The studies have been conducted in natural incident light as well as in the light passing through yellow, red, blue, and green filters. A large factual material has analyzed the petrographic and technological difficulties of measuring the Grey Intensity indicator. It is associated with the spatial arrangement of the observation planes of preparations relative to the natural occurrence of coal beds, the surface features of macerals, the influence of chemical (fluidization, gas generation) and tectonic (dynamic metamorphism) processes on the transformation of the gelled substance as the main object of research. Recommendations on the choice of a lens and a platform for measurements have been given, taking into consideration the optical system of incident light. The expediency of using color filters has been considered.