Petrological And Mineralogical Features Of Tonstein Intercalations In The Anthracite Bed And Their Significance

The article studied the petrological and mineralogical features of tonstein intercalations in the anthracite bed of Jincheng coal mine and discussed the main changing reasons and the influence factors of kaolinite, the main composition of tonstein. A series of instrumental means, such as microscopic identification, differential thermal analysis, X-ray powder diffraction analysis, infrared absorption spectrum analysis, transmission electron microscope identification etc. were used to study the samples which were collected on the working field by the author. It has been find that kaolinite influenced by different factors. transformed toward different directions The results suggested that kaolinite transformed toward illinite, accompanied by appearing of I/M and montmorillonite. The main reason for the rise of the coal rank and its composition transformation is the process of regional metamorphism and the influence of medium conditions around it. With the rise of the coal rank, the crystallinity of kaolinite and its order in the anthracite bed go up. The same kaolinite which has the best crystallinity as that in the Baishui River was found in Jincheng coal mine. When the coal rank reaches a certain degree(at least from soft coal to anthracite ),if the alkaline medium has rich k~+, kaolinite transforms toward illinite, if it has rich Na~+ ,kaolinite transforms toward montmorillonlite.The tonstein intercalations in anthracite bed in the No.3 coal mine in Jincheng can be divided into four types: kaolinite, kaolinite-illinite, illinite and montmorillonite-I/M tonstein intercalations. In the No.3 coal is 1MD.At the same time, montmorillonite-I/M minerals appear, The type of the illinite, at the top of the coal bed is 2M .The quartz content of the top roof of the coal bed is much higher than that in the tonstein intercalations in the coal bed .The nearer to the coal bed , the lower the quartz content becomes. thus ,study on the change of the mineral in the kaolinite tonstein intercalations in the coal bed has great significance.The study results show that in the soft coal bed of low coal rank, the main composition of the clay mineral in the tonstein intercalations is kaolinite. With the raise of the coal rank , the medium conditions around change, so the combination of the clay mineral change . that is, kaolinite transforms toward illinite, montmorillonite and I/M mineral. In the lean coal bed and anthracite bed of high coal rank, the main composition of the clay mineral in the tonstein intercalations is illinite, Kaolinite takes second place. Instead, the coal rank can be forecasted by studying the change of the mineral in the tonstein intercalations.