Sorption and Micro-Scale Strength Properties of Coals Susceptible to Outburst Caused by Changes in Degree of Coalification.

Katarzyna Godyń,Barbara Dutka

doi:10.3390/ma14195807

Katarzyna Godyń, Barbara Dutka

Open Access

https://doi.org/10.3390/ma14195807

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Abstract

Coals from the south-western part of the Upper Silesian Coal Basin have a strong outburst susceptibility. The objective of this study was to identify the influence of coalification degree on methane sorption and micro scale strength properties of 24 coals from Jastrzębie Zdrój. Coal samples showed a reflectance Ro between 0.98 and 1.25%. Sorption measurements were carried out by gravimetric method. Sorption capacities were determined at mean deposit temperature of 35 °C. Using the unipore model and solution of Fick’s second law, the effective diffusion coefficients of methane in the studied coals were obtained. The Vickers method was used to study the microhardness and the modulus of elasticity. It has been shown that the increase in the coalification degree reduces the sorption capacity of coal and also reduces the rate of methane emission. Coals the most susceptible to outbursts, were the most brittle. With the increase in Ro, the methane seam pressure p increased as well as desorbable methane content DMC, both due to the reduction in the sorption capacity of coal. The increased dp index is a warning sign indicating an increased total methane content of coal seam, an increased seam pressure or an alternation of coal structure.

Highlights

IntroductionCoal is still the basic energy resource in Poland [1]
The part of this paper presents an analysis of the influence of the degree of coalification on sorption properties of coal seams towards methane and their microscale strength properties
The susceptibility of coals to outbursts is closely related to the coalification of seams, which contributes to undesirable properties of seams increasing the probability of outbursts in the conditions of increasing total methane content, decreasing sorption capacity and coal diffusivity

Summary

Introduction

Coal is still the basic energy resource in Poland [1]. Combined energy management, including the simultaneous production of electricity and heat, is currently the optimal way of coal management. An alternative way of using coal is the production of coke, of which Poland is a significant European producer. Various products of modern organic chemistry can be obtained from coal [3]. The process of coal hydrogenation allows for the production of synthetic fuels [4]. Underground gasification of coal deposits enables the extraction of methane (ecological fuel) and such gases as hydrogen and carbon monoxide. Actions taken to protect the climate result in a reduction in the consumption of hard coal in the entire European Union [5]

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