Evaluation method of direct liquefaction based on coal facies analysis:Take main coal seams of Yan'an formation in Yuanyanghu mining area in Ningdong Coalfield

WEI Yingchun; DONG Bo; CAO Daiyong; JIA Xu; NING Shuzheng; ZHANG Yun; LI Xin; WANG Xin

doi:10.3969/j.issn.1007-7677.2026.01.01

Abstract：In order to quantitatively evaluate the coal performance for direct liquefaction,the"Worst Restriction Law"or"One-vote-down System"was adopted to classify and evaluate for bituminous coal for direct liquefaction.The microlithology combined with coal quality and geochemistry were used to expound the relationship among coal petrolo-gy and quality-coal facies-direct liquefaction behavior,which provide a theoretical basis for new evaluation method of direct liquefaction.The results show that paleomire sequences of single coal seam are different under the control of different sedimentary environment,the No.2 coal seam has four cycles under the control of fluvial facies,in compari-son,the No.6 coal seam has two cycles influenced by lacustrine deltaic facies.Under the same cycle of coal facies,characteristics of coal petrology and organic facies in the No.2 and No.6 coal seams vary consistently,from the bot-tom to the top,macroscopic lithotypes of coals vary from bright or semibright coals to semidull or dull coals,vitrinite-decreased and inertinite-increased,the percentage of herbaceous plants decreases but woody plants increases,the a-queous dynamic condition in swamps undergoes the weak-strong evolution,the aqueous medium in peat swamp trans-forms from reduction to weak oxidizing environment.The coal formed from wet herbaceous swamp facies is suitable for direct liquefaction,while the coal formed from wet forest marsh facies can be used for hydrogenation liquefaction.The coal derived from dry forest marsh facies is not suitable for liquefaction.According to the evaluation method of coal di-rect liquefaction performance based on coal facies analysis,the No.2 coal seam can be used as liquefaction coal after washing,whereas,the No.6 coal seam is not suitable for direct liquefaction.