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煤中硫分布特征及其沉积成因研究——以鄂尔多斯盆地榆横矿区南区为例

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

  • 摘要: 鄂尔多斯盆地陕北侏罗纪煤田是我国重要的煤炭基地,以低灰、低硫、低磷、高发热量的优质煤炭资源为主。作为陕北侏罗纪煤田的一部分,榆横矿区南区原煤硫分普遍较高,中高硫煤和高硫煤资源量占总资源量的比例超过60%,属于该区一种特殊的地质现象,同时,煤中硫的富集也严重制约了该地区煤炭资源的清洁利用。为查明榆横矿区南区高硫区的分布特征、变化规律和沉积成因,以煤岩煤质和钻孔资料为基础,从煤岩学、煤地球化学和沉积学入手,揭示高硫煤分布特征和变化规律,建立了沉积微相与煤中硫分分布之间的成因联系,分析了相参数与硫分之间的相关关系,建立了陆相含煤地层中硫的富集模式,进而为煤炭资源开发总体规划、清洁利用及生态环境保护提供依据。研究结果表明,原煤全硫含量0.31%~4.95%,平均1.83%(质量分数,下同),高于全国早、中侏罗纪煤中硫含量的平均值0.58%。平面上,原煤硫分由西北向东南、由物源向湖盆方向呈增高的趋势,垂向上自下而上逐渐增高。煤中硫的聚集主要受控于成煤同生阶段和早期成岩阶段沉积微相控制,分流河道以中硫煤为主,分流间湾以中高硫煤为主,高硫煤主要分布于局限浅湖发育区。硫化铁硫含量与煤岩显微组分中的镜惰比、灰成分指数之间呈正向变化,表明凝胶化作用和还原性水介质有利用煤中硫的富集,而水介质中Fe2+丰度是影响硫化铁硫含量的重要因素。

     

    Abstract: 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.

     

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