Geochemical Characteristics Of The Nos.15-3 And 18 Coals Of The Dabaoding Coal Mine,Panzhihua City,Sichuan Province

The Panzhihua City of Sichuan Province is an important ilmenite production base in China.Coals from the Dabaoding Coal Mine are mainly used for local steel production.The geochemical characteristics of coals would directly affect the quality of produced steel and the mining area environment.The Dabaoding Coal Mine is located in the southwest of Panzhihua City.The coal mine is tectonically located on the western margin of the Yangtze block and above the Kangdian Oldland.The Baoding Basin,where the coal mine is located,is a fault basin with coal accumulation activities throughout the late Triassic.The coal-bearing strata included the Daqiaodi Formation and the Baoding Formation.To ascertain the geochemistry of Dabaoding coals,a total of 15 coal samples,6 parting samples,and 4 roof and floor rock samples from the D15-3 and D18 coalbeds in the Daqiaodi Formation were subjected to proximate and ultimate analyses for coal quality,by using LTA-XRD with Siroquant software for minerals,XRF for major element oxides,ICP-MS for trace elements.The reason of rare earth element anomalies in coal is analyzed and the sediment source region of coals is identified.Results indicate that:(1)The ash yields of the D15-3 and D18 coals is 14.63%and 12.15%,respectively,which are classified as low ash coal.(2)Terrigenous clastic minerals account for the majority of minerals in coal seams.There are some differences in mineral types and contents between coal and host rocks.Clay minerals,such as kaolinite,illite,and chlorite are the most abundant minerals in the D15-3 and D18 coals.The content of quartz in two coal seams is second only to that of clay minerals.Moreover,there are a certain amount of muscovite and albite,calcite,and dolomite in coal and host rocks.The content of quartz and clay minerals in the D15-3 coals is higher than that in the D18 coals,while the content of calcite and dolomite in the D18 coals is higher than that in the D15-3 coals.(3)Compared to Chinese coals,most major element oxides in the D15-3 and D18 coals are at normal or depleted levels.The enrichment degree of SiO2,TiO2,Al2O3 and CaO in the D15-3 coals are at normal levels,Fe2O3,MnO,Na2O and P2O5 are depleted,and MgO and K2O are slightly enriched.For the D18 coals,the enrichment degree ofSiO2,CaO,and K2O are at normal levels,TiO2,Al2O3,Fe2O3,MnO,Na2O,and P2O5 are depleted,and MgO are slightly enriched.(4)Compared to Chinese coals,most of the trace elements in the D15-3 and D18 coals are at normal or depleted levels.The slightly enriched trace elements include Cr and Rb in D15-3 coal,and Cr in 18 coals.Compared to world hard coals,most of the trace elements in the D15-3 and D18 coals are also at normal or depleted levels.Chromium and cobalt were slightly enriched in the D15-3 coals,while only Cr was slightly enriched in the D18 coals.(5)The REY distribution patterns of the D15-3 and D18 coals are M-type with positive Ce anomalies,negative Eu anomalies,positive Gd anomalies,and positive Y anomalies.And(6)based on mineralogical,major elements oxides,trace elements,and REY evidence,and combined with the investigation of igneous rocks surrounding Baoding basin,the sediment source rocks of the D15-3 and D18 coals in Dabaoding Coal Mine are identified as granite and trachyte.Figure[19]Table[7]Reference[80]...