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THE DEFLUIDIZATION OF THE ROCKS AND GENESIS OF GOLD DEPOSITS DURING DEFORMATION AND METAMORPHISM: AN EXAMPLE FROM THE JINPING MOUNTAIN
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作者 Li Sheng(Chengdu Institute of Geology and Mineral Resources, Chengdu, 610082,China) 《地学前缘》 EI CAS CSCD 2000年第S1期411-412,共2页
The Jinping mountain region on the western margin of the Kang\|Dian axis is situated in the area bordered by the eastern margin of the Qinghai—Xizang Plateau on the west and the western margin of the Yangtze plate on... The Jinping mountain region on the western margin of the Kang\|Dian axis is situated in the area bordered by the eastern margin of the Qinghai—Xizang Plateau on the west and the western margin of the Yangtze plate on the east, and consists of three\|layer structures: basement (Kang\|Dian axis), detachment zone (sliding surface of lateral extension and thrusting) and the overburden of the Jinping mountain nappe. The intense intracratonic deformation and metamorphism within the Kang\|Dian axis resulted in the activation, migration and enrichment of mineral elements and finally the formation of ore deposits in the Jinping mountain region. As for the Kang\|Dian axis as the crystalline and folded basement, the lower background values ((0 4~0 8)×10 -9 ) of the element Au don’t represent the initial contents, which have mostly been activated and moved away.. In the Lizhuang\|Lawo\|Bazhe zone as the detachment structural zone, the high er background values ((6~10)×10 -9 ) of the element Au don’t represent the initial contents as well, which have received more gold from the multistage ductile shear zones in the detachment zone. As a result of the lower degrees of deformation and metamorphism within the overburden of the Jinping mountain nappe, the lower temperatures and pressures are insufficient to activate and migrate the element Au; the Au contents available represent the initial Au contents ranging between 1 6 and 2×10 -9 , which are equal to the crustal clarke values from Li Tong and Dai Wentian. The activation and migration of the element Au are believed to be governed by the temperatures and transported media especially variable valent elements and their compounds (principally H 2O, Cl, CO 2 , S and Fe). The associated sediments are also correlated with the transported media especially the valence numbers of the above\|mentioned multivalent elements. The element Au often behaves as a liquid phase element and a multivalence\|phile element in the course of deformation and metamorphism, in which the active components such as H 2O, S, OH - and SiO 2 tend to be moved away to form fluids, while the enrichment process of the inactive ones such as Zr, Ti and P and trace elements is referred to as the defluidization of the rocks due to the variations in mineral phases and formation of different deformational fields (P—Q fields) during the deformation and metamorphism. The widespread defluidization within the Kang\|Dian axis as the basement may allow the element Au with the lower background values to be moved away within the extent of the granulite facies and high amphibolite facies or moderately deep and deep structural facies. The detachment zone of lateral extension and thrusting is manifested as the migration surface of the ore\|forming fluids and the transformation surface of the physicochemical fields of mineralization. In general, the metamorphic facies include greenschist facies and low amphibolite facies or shallow to moderately deep structural facies. It can be seen that both the dynamic and thermodynamic factors are favourable for the emplacement and mineralization of ore\|bearing solution. The further enrichment of mineralized material may permit the first\|order source beds to develop. The temperatures within the overburden are not high enough to be favourable for the activation and migration of Au. (The best conditions for gold migration is in the greenschist facies. The defluidization of the rocks in the higher\|grade metamorphic facies may cause Au to be activated and moved away easily, whereas the dehydration of the rocks in the lower\|grade metamorphic facies may not do so.) It appears that almost all of the rocks are capable of contributing sufficient mineralized material for the formation of gold deposits. The defluidization of the rocks is a key process in the course of deformation and metamorphism. The amphibolite facies, granulite facies and even higher\|grade metamorphic facies are generally favourable for the activation and migration of gold due to the more complete and thorough 展开更多
关键词 defluidization source bed BASEMENT detachment zone of ext ension and THRUSTING (slide surface) OVERBURDEN
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A Model for Agglomeration in Bio-fuel Fired Fluidized Bed 被引量:3
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作者 Shiyuan Li Linlin Shang +1 位作者 Haipeng Teng Qinggang Lu 《Journal of Thermal Science》 SCIE EI CAS CSCD 2010年第5期451-458,共8页
A mathematical model has been developed to describe the agglomeration process in bio-fuel fired fluidized bed combustor. Based on the balance mechanism of the adhesive force caused by liquid bonding between two parti-... A mathematical model has been developed to describe the agglomeration process in bio-fuel fired fluidized bed combustor. Based on the balance mechanism of the adhesive force caused by liquid bonding between two parti- cles and the breaking force induced by bubbles in the fiuidized bed, the model considers modified Urbain model and chemical equilibrium calculations using FactSage modeling. This model prediction accounts for the evolve- ment of the adhesive and breaking forces, and clearly demonstrates that the different composition of ash, the in- creasing liquid phase matter and the fiuidization velocity cause defluidization in fluidized bed. In this model, it is the first time to hypothesize that the bonding stress between two particles is proportional to mass fraction of liq- uid phase and inversely proportional to the diameter of particles and viscosity of liquid phase. The defluidization time calculated by this model shows good agreement with that from the experimental data. 展开更多
关键词 BIO-FUEL Fluidized bed AGGLOMERATION defluidization Force balance
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Direct reduction of hematite powders in a fluidized bed reactor 被引量:8
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作者 Qingshan Zhu Rongfang Wua Hongzhong Li 《Particuology》 SCIE EI CAS CSCD 2013年第3期294-300,共7页
Ultrafine hematite powder was reduced to produce ultrafine iron powder in a 50%Ar-50%H2 atmosphere at 450-550 ℃ in a fluidized bed reactor. The ultrafine hematite powder shows the typical agglomerating fluidization b... Ultrafine hematite powder was reduced to produce ultrafine iron powder in a 50%Ar-50%H2 atmosphere at 450-550 ℃ in a fluidized bed reactor. The ultrafine hematite powder shows the typical agglomerating fluidization behavior with large agglomerates fluidized at the bottom of the bed and small agglomerates fluidized at the upper part of the bed. It was found that defluidization occurred even at the low temperature of 450 C with low metallization rate. Defluidization was attributed mainly to the sintering of the newly formed iron particles. Granuation was employed to improve the fluidization quality and to tackle the defluidization problem, where granules fluidized like a Geldart's group A powder. Granulation was found to effectively reduce defluidization during reduction, without however sacrificing reduction speed. The asreduced iron powders from both the ultrafine and the granulated hematite exhibited excellent sintering activity, that is, fast sintering at temperature of as low as ~580℃, which is much superior as compared to that of nano/ultrafine iron powders made by other processes. 展开更多
关键词 Direct reduction Granulation defluidization Sintering Ultrafine iron powder
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