Abstract
Minerals in coal are of great significance in determining coal properties,washing,combustion,gasification and liquefaction. In order to realize the clean and efficient utilization of coal resource in Fukang,11 coal samples were collected from Xiaohuangshan Mine in Fukang area. Proximate,total sulfur and gross calorific value were analyzed for these coal samples. The composition,and micro-topography of samples were studied by X-ray fluorescence(XRF),low-temperature ashing-X-ray diffraction(LTA-XRD)and electron probe microanalyzer(EPMA). The results indicate that the No.6 coal of Xiaohuangshan Mine are characterized by low moisture,medium-high volatiles,low ash,and low sulfur coals. The average content of Na2O in the ash of No. 6 coal seam samples was 10.91%,which was characterized by high content of Na2O in the top and bottom coal seams and low content of Na2O in the middle.The analysis showed that the minerals in coal were not the source of Na. Part of the Na in the coal may come from the topsoil,which was carried into the coal seam by the surface water in the process of infiltration. The other part may come from the overpressured Na2SO4 water in Mesozoic strata. The mineral composition(low temperature ashes)is as follows:dolomite,dawsonite,quartz,albite,clay minerals,and calcite. In addition,a trace of apatite and gogethite also found by the electron probe microanalyzer. It is speculated that during the peat depositional period,silicate minerals were carried to the peat swamp by water and reacted with CO2 released from the coalification process to form dawsonite. Dolomite and calcite in coal are formed from CO and CO2,which are produced from coalification process,reacting with the fluid in coal. The apatite may either be formed by migration of hydrothermal solutions or from local remobilization of phosphate,formed earlier within the coal seam or associated strata. Gogethite is the oxidation product of iron sulfides in coal.
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