A new method for determining the individual sources of goaf gas emissions:A case study in Sihe Coal Mine

This paper describes a new method for determining the individual sources of goaf gas emissions in Shihe coal mine. Desorbed gases from coal seam No. 3 and its seven neighboring seams were respectively sampled and analyzed of their composition including CH4 ,C2 H6 ,stable carbon isotopes in CO2 and hydrogen isotopes in CH4 . Based on the ana- lyzed results,a mathematical model was developed for calculating the sources of goaf gas emissions. The model was then applied in No. 5302 panel in Shihe coal mine to determine the emission sources of the goaf gas from each of the coal seams. The results show that CH4 concentration,stable carbon isotopes in CO2 and hydrogen isotopes in CH4 increased with the depth of No. 3 seam. In terms of the characteristics of goaf gas emissions in No. 5302 panel,it can be divided into three stages with the panel advance. In the initial stage,the goaf gas emission was dominated with gas de- sorbed from the mining No. 3 seam,this dominance weakened as the panel advances and stabilized at around 20% -25% of the total goaf gas emissions. In the second stage,gas from neighboring seams started to play an important role in the goaf gas,taking up 20% -25% of the total goaf gas emissions. In the third stage,the sources of the goaf gas e- mission became stable and gases desorbed from No. 9 and No. 15 seams made up 20% -25% and 30% -35% of the total goaf gas emissions respectively. This isotopes based method,in comparison with the tradition method for determi- ning the sources of goaf gas emissions,can give quantitative description of dynamic change in the individual sources of goaf gas emissions with the advance of a mining panel,enabling a more targeted and effective control of goaf gas emis- sions.