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Wang R.,China University of Mining and Technology | Sang S.-X.,China University of Mining and Technology | Wang W.-F.,China University of Mining and Technology | Yi T.-S.,Guizhou Provincial Coalfield Geological Bureau | Zhao X.,Guizhou Provincial Coalfield Geological Bureau
Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology | Year: 2011

The concentration, distribution occurrence modes of gold and mechanism of its accumulation in No.17 coal seam of Pu'an coalfield, Guizhou Province were studied using neutron-activation method (INAA), scanning electron microscope with an energy-dispersive X-ray (SEM-EDX) and electron probe analysis (EMPA). The results show that the content of gold in the No.17 coal seam is 2.61×10-9~9.73×10-9, with the mean value (6.29×10-9) higher than that in coals from China and the world. The gold in coal mainly exists in form of inorganic mineral. The carrier minerals are pyrite and clay. The source of gold is epigenetic hydrothermal, which can be captured by the loose and porous coal seam. In addition, closed hallow sea environment provides favorable conditions for gold accumulation. Deep fault-hydrothermal process is the mainly type of gold accumulation in the No.17 coal seam. Source


Wang R.,China University of Mining and Technology | Sang S.-X.,China University of Mining and Technology | Wang W.-F.,China University of Mining and Technology | Yi T.-S.,Guizhou Provincial Coalfield Geological Bureau | Zhao X.,Guizhou Provincial Coalfield Geological Bureau
Meitan Xuebao/Journal of the China Coal Society | Year: 2010

Twenty-one samples of raw coals, coal rock and gangues from the Southwestern area of Guizhou Province were analyzed for Au by using the neutron-activation method(INAA), no flame atomic absorption spectrometry(AAN), scanning electron microscope with an energy-dispersive X-ray(SEM-EDX) and electron probe analysis(EMPA). The volatilization law of Au in the coal-fired process(laboratory-ashing) was discussed. The results show that the gold's loss rate of the coal is more than 75%, Au is a more volatile element in the coals of the coal-fired process. But the loss rate in the coal rock is less than 10%, gold is a less volatile element in the coal rock. During coal-fired process, the main factors which affect the dissipation of Au in the raw coal is the occurrence mode of gold. Au in the coal of the study area is mostly in the form of nano-gold. The mineralization and enrichment of Au is pyrite. Due to the low melting point of nano-gold, the decomposition of pyrite can cause the melting, merging and volatilization of nano-gold. In addition, the fly ash(especially granules of unburned carbon) can also adsorb nano-gold which will lead to the dissipation of Au. Source


Wang R.,China University of Mining and Technology | Sang S.-X.,China University of Mining and Technology | Wang W.-F.,China University of Mining and Technology | Yi T.-S.,Guizhou Provincial Coalfield Geological Bureau | Zhao X.,Guizhou Provincial Coalfield Geological Bureau
Meitan Xuebao/Journal of the China Coal Society | Year: 2013

The anomalous concentration of gold in coals makes it a potential resource exploitation area of gold that has win geological workers' attention. Instrumental neutron activation analysis (INAA) on concentration of gold of 116 coal samples and gangue samples of Longtan Formation of the upper Permian and Changxing Formation in Southwestern Guizhou Province was conducted so as to make investigations on gold's distribution characteristics and occurrence modes and to further probe into its main source and enrichment mechanism. Studies show that concentration range of gold in coals in Southwestern Guizhou is from 1 ng/g to 30 ng/g, with an average value being 13.75 ng/g, which is well above the sedimentary rock abundance and the world average abundance of coal. Areas where the anomalous concentration of gold is really high are principally in the "triangle" area composed of Ziyun-Yadu deep fault, Shizong-Guiyang deep fault and Kaiyuan-Pingtang fault. Hydrothermal solution containing gold is the main material source for the gold in coals in Southwestern Guizhou Province while mantle plume and deep magmatic activities are the thermodynamic source for the solution's migration into coal beds, that is, after the hydrothermal solution containing gold, under tectonic forcing, migrated to the coal bed along fault belt, ore-forming fluid would lose stability because of organic matter effect and physicochemical changes such as concentration, temperature, pressure and pH value, which led to the precipitation and enrichment of ore-forming elements like gold in coals in the research area. Source

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