Petrological characteristics of coal and their control on gas emission of Upper Permian in eastern Yunnan

Based on petrological characteristics of the Upper Permian coal in eastern Yunnan and the statistic analysis of gas content, gas emission and coal mine gas accidents, this paper conducted comparative research on petrographic composition, coal structure, coal screening test results, gas content of each coal seam and gas emission. The results show that petrological characteristics of coal, such as metamorphism degree, coal maceral, size fraction and porosity have determined gas accumulation and resulted in the regional differences of the gas emission. The emission category of Upper Permian in eastern Yunnan can be divided into several types:uniform emission of low rank coal, uniform emission of middle rank coal, non-uniform bursting of middle rank coal, uniform emission and non-uniform bursting of high rank coal. The uniform emission of middle rank coal is dominant.