DBPapers
DOI: 10.5593/SGEM2014/B13/S3.032

EXAMINATION OF ADSORPTION AND DESORPTION OF ETHYLENE ON SEVERAL SAMPLES OF POLISH HARD COALS

A. Dudzinska
Wednesday 1 October 2014 by Libadmin2014

References: 14th International Multidisciplinary Scientific GeoConference SGEM 2014, www.sgem.org, SGEM2014 Conference Proceedings, ISBN 978-619-7105-09-4 / ISSN 1314-2704, June 19-25, 2014, Book 1, Vol. 3, 241-248 pp

ABSTRACT
Ethylene is a component of mine air. Its presence in the atmosphere of a coal mine is closely related to the evolution of the processes of self-heating of coals. Based on the measured concentration of ethylene, fire indices are determined, which are used for the current evaluation of fire hazard. In this study an influence of ethylene adsorption on hard coals on the assessment of the self-heating processes development was investigated. The adsorption tests were carried out on 4 samples of hard coals having various content of carbon and oxygen, varied porosity and different hydrophilic nature of their surface. It was shown that the quantities of adsorbed ethylene are quite large and depend on the degree of metamorphism of coals, their porosity, carbon and oxygen content, polar groups containing oxygen and moisture contained in coal matter. The largest amounts of ethylene are adsorbed by low-rank coals having high content of oxygen, moisture, porosity and increased values of specific surface area. Tests on ethylene desorption on hard coals were also performed, using the method of lowering ethylene pressure above the adsorbent. The desorption isotherms do not converge with the adsorption isotherms, forming an open hysteresis loop. In the coal structure there are likely to remain certain amounts of ethylene linked more strongly with the coal structure and these quantities depend on the type of coal. The process of ethylene adsorption can lead to a reduction in its concentration in the mine atmosphere and thus can affect correctness of the self-heating phenomenon assessment.

Keywords: adsorption, desorption, ethylene