Study On Identification Of Original CO In Xunyao Mining Area Based On Oxygen Isotope Method

Coal spontaneous combustion is one leading hazard during coal exploitation and transportation. Gas analysis, especially CO analysis, is widely used to predict spontaneous combustion, domestically and internationally. In recent years, we found CO burst without the commonly associated coal spontaneous combustion. Therefore, where dose the CO come from remains controversial. In this thesis, CO occurrence in Xunyao diggings is researched, along with CO adsorption & desorption characteristics. By introducing analyzing oxygen isotope of CO from coal seam and coal oxidation, we finally found out where dose the CO come from in Xunyao diggings.Through analyzing coal samples exploited from Xunyao diggings, we investigated CO occurrence in both coal seam and rock strata. We made comparisons of CO value in different sites within Xunyao diggings, which demonstrates that there is CO in rock strata while its value varies from site to site.We studied the influence of particle size, temperature, pressure and moisture content on coal’s CO adsorption capacity at normal pressure and temperature. Therefore, we found out CO adsorption patterns with particle size changing and revealed that coal’s gas adsorption capacity varies from different gases(CO2>CO>CH4>N2). Also, we compared coal’s adsorption capacity of CO and mixed gas and further analyzed how moisture content, temperature and gas pressure affect coal’s CO adsorption & desorption capacity.We analyzed gas samples gathered from different sites and indentified their Oxygen isotope value. Also we detected oxygen isotope value in the oxidation product of coal samples in different gases(air and argon) at various temperatures. It is well acknowledged that oxygen isotope value in coal pyrolysis product overwhelms that of coal oxidation product. And higher temperature leads to less oxygen isotope value in coal oxidation and pyrolysis. Even so, oxygen isotope value is mainly decided by coal’s surrounding atmosphere. Therefore, it reveals that CO in Xunyao mining area is mainly derived from the coal forming process,which belongs to original CO.We found that oxygen isotope value in CO collected in coal seam is similar to that of CO produced during coal oxidation in argon. Therefore, we presume that there is original CO within coal seam. Meanwhile, we selected CO increase rate and change in oxidation isotope as indicators to predict coal spontaneous combustion.Based on the geologic feature of Xunyao diggings, we analyzed its CO occurrence in coal seam by performing massive amount of laboratory experiments and field ones. As investigation against CO adsorption & desorption characteristics further conducted, we analyzed oxygen isotope values and finally put forward fitting measures to predict coal spontaneous combustion in Xunyao diggings.