عنوان مقاله [English]
The Olang area is located in 70 km of northeast Shahroud. This area is situated in Gheshlagh Olang syncline, which is a member of the EasternAlborzCoalBasin. The optical microscopes and X-ray diffraction (XRD) analysis on coal and coal ash samples and also SEM-EDX results revealed kaolinite, quartz, siderite, pyrite, biotite, chlorite and illite minerals in coal seams at the Olang coal mines. Pyrite is observed as syngenetic (framboidal) and epigenetic (filling of the cell cavity, vein, and veinlet).The abundance of syngenetic siderite and absent sulphate minerals is usually thought to indicate deposition of the coal mainly under nonmarine conditions, or at least under the influence of swamp or formation waters with low sulphate content. The study of 15 potentially hazardous trace elements (PHTEs) includes: (Ba ®1054.7 ppm), (Co ®51.32 ppm), (Cr ®161.1 ppm), (Cu ®129.3 ppm), (Mn ®1600 ppm), (Mo ®19.56 ppm), (Sn ® 4.78 ppm), (Ni ®139.7 ppm), (Pb ® 48 ppm), (Tl ®1.36 ppm), (Th ®27.6 ppm), (U ® 9.45 ppm), (V ® 232.9 ppm), (Zn ®101/78 ppm(, (P® 6500 ppm) in coal ash deposits of the Olang region compared with the average of the world coal ash, shales, soils and also crustal Clarke. The results show that these coals are enriched in Mn, Mo, U, Pb, Zn and P and are dangerous elements.