A new DeteRmInAtIOn methOD FOR COAL metAmORPhISm DeGRee Purpose. Development and approbation of a new method for determining the degree of coal metamorphism by the index of gray shade intensity of macerals for microphotographs of lump sections of coal samples. methodology. Optical spectroscopy using a videooptical complex: MBI-11, HB 200, followed by digital com puter processing (Scope photo software) of microphotographs of coal substance samples upon lump sections. Findings. A new method is proposed for determining the degree of coal substance metamorphism, the essence of which is the use of optical microscopy of lump sections of coal samples, followed by digital processing of the obtained data. The method was tested on coal samples of various ranks-from longflame to anthracite. To characterize the degree of coal metamorphism, a new index of the gray shade intensity of macerals was applied on the photographic images of the lump sections of coal samples microscopically. Correlation of the proposed index with the classical ones of the degree of coal metamorphism-vitrinite reflectance is shown. Originality. For the first time, a digital processing of photographic images of the lump sections of coal samples using a new index of gray shade intensity of macerals was applied to characterize the degree of coal metamorphism. Practical value. The proposed method can be used for practical application in order to assess the degree of coal metamorphism. This method differs by its operability and simplicity from the currently widely used one for determin ing the degree of coal metamorphism by vitrinite reflectance. The method can also be applied to assess the recover ability of coals and calculation of their maceral composition.
A new approach for the study of processes at the atomic-molecular level occurring in the current situation in fossil carbonized organics was proposed. A new phenomenological model of physicochemical transformations in a metastable coal substance with the emission of fluids has been developed. The proposed physic/chemical model is based on the genetic connection of coal methane with fossil organic matter and determines the conditions for the activation of structural transformations in coalmines. This model describes the possible options for the coal/gas system development in the current situation. The accumulation of thermal and mechanical energy by coal in the form of structural stresses in an amount, sufficient to activate free-radical reactions, was experimentally established. In the undisturbed coalrock massif the processes of the coal molecular structure transformation have the relaxation character. The result of relaxation of the accumulated energy in the conditions of a gas-saturated coalrock massif is the methane generation by coal. Gas generation in the process of coalification, in its essence, is the energy response of the system to the action of external geomechanical options (temperature and pressure), by the way of releasing the accumulated additional energy with the emission of gaseous products and the destruction of the solid phase in the organic matter of the coal.
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.
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