Study on distribution characteristics and sedimentary genesis of sulfur in coal:taking southern Yuheng Mining Area of Ordos Basin as a case

As an important coal base in China,Jurassic Coalfield in Northern Shaanxi of Ordos Basin is famous for producing high quality coal with low ash,low sulfur,low phosphorus and high calorific value.As a part of Jurassic Coalfield in Northern Shaanxi,the sulfur in coal in southern Yuheng Mining Area is generally high,and the resources of medium sulfur coal and high sulfur coal account for more than 60% of the total resources,it is a special geological phenomenon in this area,at the same time,the enrichment of sulfur in coal seriously restricts the clean utilization of coal resources in this area.In order to find out the distribution characteristics,variation rules and sedimentary genesis of high sulfur area,based on the data of coal petrology,coal geochemistry and sedimentology,the distribution characteristics and variation rules of high sulfur coal are revealed,the genetic relationship between sedimentary microfacies and sulfur distribution in coal is established,the correlation between facies parameters and sulfur content is analyzed,and the enrichment model of sulfur in continental coal bearing strata is established,and then provide the basis for the overall planning of coal resources development,clean utilization and ecological environment protection.The results show that the total sulfur content of raw coal ranges from 0.31% to 4.95%,with an average of 1.83% (mass fraction,the same below),which is higher than the national average value of 0.58% in early and Middle Jurassic coal.On the plane,the sulfur content of raw coal increases from northwest to southeast,from provenance to lake basin,and increases from bottom to top in vertical direction.The accumulation of sulfur in coal is mainly controlled by sedimentary microfacies in coal forming contemporaneous stage and early diagenetic stage.The distributary channel is dominated by medium sulfur coal,and the distributary bay is dominated by medium high sulfur coal.The high sulfur coal is mainly distributed in limited shallow lake development area.There is a positive correlation between sulfur content of iron sulfide and vitrinite and inertinite ratio and ash composition index,it is shown that there is enrichment of sulfur in coal by gelation and reductive water medium,and the abundance of Fe2+ in water is an important factor affecting sulfur content of iron sulfide.