Study on lithology and coal quality features and coal forming environment of Yan’an Formation in Yuanyanghu Mining Area

In order to reveal the formation conditions of different lithology and coal quality,based on the coal and rock,industrial analysis and ash content data analysis,the lithology and geochemical and other methods were applied to discuss the lithology and coal quality features and the coal formation environment of the mining seam in Yan’an Formation of Yuanyanghu Mining Area. The results showed that the coal in Yan’an Formation was a semi durain coal mainly. The rich inertinite group was mainly the low ash,low sulfur,low phosphor and ultra low chlorine. The ash content was mainly SiO2 and Al2O3. Vertically,from the bottom to the up,the content of the vitrinite was firstly increased and then decreased. The content of the inertinite was firstly decreased and then increased. The coal forming environment was an oxidation type - weak oxidation type or reduction type - oxidation type. The content of the inertinite in the low section and top section of the seam was high and the ash composition was high. Mainly the influences affected by paleochannel,the vitrinite and inertinite in the middle section was the same and the coal accumulation had periodical varied features. On a plane,the north part was closed to the provenance,the ash content and the sulfur content was high and the environment was the developed river and delta plain. The middle part was the regional subsidence center,the inertinite was rich,the ash content and sulfur content was low and thus the delta plain was transited to the delta leading edge and the lake environment. In the south part,the ash content and sulfur content were low,the inertinite was rich,the detrital material was reduced and the environment was a developed delta plain.