The Distribution,Occurrence And Enrichment Genesis Of Hazardous Trace Elements In Coals From The Eastern Yunnan And Western Guizhou

The migration characteristics of hazardous trace elements during utilization in coal are closely related to their content and occurrence state.Southwest China is an important coal resource producing area.It is of great significance to study the hazardous trace elements in coal for the clean utilization in the region.Therefore,the content,distribution and occurrence of hazardous trace elements in coals in Southwest China is of great significance for its migration characteristics in the subsequent utilization process and reducing environmental pollution.In this paper,by means of proximate analysis,total sulfur analysis,ICP-MS,AFS,SEM analysis and other testing methods,combined with coal geochemistry,mineralogy,statistics and sedimentology,the occurrence characteristics,spatial and temporal distribution and enrichment patterns of hazardous trace elements were discussed.The main achievements are as follows:(1)The coal petrology and coal quality characteristics of Longtan Formation in Laochang mining area of the East Yunnan and Rongyang coal mine are defined.The coal samples belong to anthracite in the study area.The coal macerals are dominated by vitrinite.The proportion of inertinite in coal in Laochang mining area is relatively low,and the exinite component accounts for less in Rongyang coal.All coal samples are geared to medium ash coal.The No.3 coal seam of Laochang mining area belongs to ultra-low sulfur coal,the Nos.7+8#,11#,13#coal seams belong to medium sulfur coal,and the upper Permian coal in Rongyang coal mine belongs to high sulfur coal.Rongyang coal mainly contains kaolinite,quartz,pyrite and other minerals,while the main minerals in Laochang mining area are quartz,pyrite,calcite,etc.(2)The distribution characteristics of harmful trace elements in coal in the study area were discussed.On the whole,the content of hazardous trace elements in coal in Laochang mining area is lower than or close to Chinese coal and world coal.Some harmful trace elements(Pb,As,Th,Cr)in Xingbo coal mine in Laochang mining area are slightly enriched,and the overall content is not high.The harmful elements V,Mo and Sn in Rongyang coal mining are slightly enriched,and U is enriched.On the whole,the content of harmful trace elements in Rongyang coal mine is higher than that in Laochang mining area.(3)The occurrence characteristics and enrichment genesis of Laochang mining area and Rongyang coal are revealed.The possible occurrence states of harmful trace elements in coal in Laochang mining area are analyzed:F,Cr,Ba,Tl,Pb and Th are closely related to silicoaluminate minerals;Ni and C_O have close correlation with ash and total sulfur,and mainly coexist with pyrite in the form of sulfide binding state;The high S_iO₂/Al₂O₃ ratio in some coal samples in Laochang mining area may be affected not only by the intrusion of siliceous solution precipitated by Emeishan basalt during weathering,but also by the intrusion of underground silicon rich low-temperature hydrothermal fluid.The high content of total sulfur in some coal seams of Rongyang coal mine and Laochang mining area and the high content of harmful trace elements and pyrite in Rongyang coal mine are related to the intrusion of seawater during coal formation.