Investigation of organic material self-heating in oxygen-depleted condition within a coal-waste dump in Upper Silesia Coal Basin, Poland

摘要

Self-heating occurring was studied in the Bytom coal-waste dump using petrographic, mineralogical, and organic geochemical to assess the changes induced by heating on organic material and quantify-qualify the emitted gases. The distribution of geochemical markers such as n-alkanes, alkylbenzenes, alkylcyclohexanes, phenols, sulfurous compounds, and emitted gases in the waste dump is outlined. Heating of organic material there is indicated by high vitrinite random reflectance (R-r)% values that typically characterize samples with short-chain n-alkanes, alkylbenzenes, and alkylmethylbenzenes. Contents of minerals showing minor alterations are high with ~ 90% in burned-out samples. Inside the dump where temperatures can reach up to 700-1300 degrees C and oxygen contents are significantly reduced, conditions favor coking. This situation is confirmed by the formation of enormous quantities of phenols and alkylbenzenes or by elevated amounts of H-2 formed under low-oxygen conditions (pyrolysis). Aromatization, pyrolysis (thermal cracking), and oxidation are associated with the heating in the dump. Gases such as methane, ethane, propane, and ethylene formed during self-heating can serve as fuel for the fire inside the dump, in the process generating huge amounts of CO2.