准格尔煤田高铝煤物质组成及成因

利用煤岩学、矿物学和地球化学等研究方法，在分析准格尔煤田的构造背景和聚煤环境的基础上，研究了准格尔煤田6号煤层的煤岩煤质特征、煤和夹矸中无机矿物组成、分布及赋存特征，并探讨其成因。研究表明，6号煤层有机显微组分中惰质组、镜质组、壳质组平均含量分别为59 %、28 %、13 %，与华北其他地区晚古生代煤相比，其中的惰质组含量偏高，反映6号煤层形成时地表水供给充分；煤中无机显微组分及夹矸中主要矿物为高岭石和勃姆石，还有少量的石英、方解石、菱铁矿、黄铁矿、硬石膏、锐钛矿和磷锶铝矾等；6号煤层中部富集大量勃姆石，上部和下部则主要富集高岭石；高岭石成因主要有胶体沉积结晶、陆源搬运沉积和火山灰蚀变3种，勃姆石成因主要有氧化铝胶体沉淀结晶和高岭石脱硅蚀变2种。

Composition and origin of high-alumina coal in Jungar coalfield

Based on the analysis of tectonic background and coal-accumulating environment of Jungar coalfield, the coal petrological characteristics, inorganic mineral composition, distribution and occurrence regularity of coal and gangue in No.6 coal of the Junger coalfield are studied, and the genesis is determined byutilizing the research methods of coal petrology, mineralogy and geochemistry.The study shows that the average contents of the inertinite, vitrinite and exinite in the maceral of No.6 coal in the study area are 59 %, 28 % and 13 %, respectively.Compared with the Late Paleozoic coals in other areas of North China, the content of the inertinite is high, which reflects an adequate supply of surface water during the formation of No.6 coal seam.The main inorganic minerals in coal and gangue are kaolinite and boehmite, associated with quartz, calcite, siderite, pyrite, anhydrite, anatase and svanbergite.The vertical changes of the mineral composition and main chemical elements of No.6 coal indicate that the middle of the coal seam is rich in boehmite, while the upper and lower parts are rich in kaolinite.There are three origins of kaolinite: colloidal precipitation crystallization, terrestrial transport sedimentation and volcanic ash alteration.And there are two origins of boehmite: alumina colloidal precipitation crystallization and desilication alteration of kaolinite.