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Onset and Stability of Thermally-Driven Fluid Convection in a Vertical Rock Crack and Their Implication for Hydrothermal Ore-Forming Processes
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作者 Bao ZhengyuChina University of Geosciences , Wuhan 430074 《Journal of Earth Science》 SCIE CAS CSCD 1992年第1期43-54,共12页
Dynamic equations controlling the thermally-driven fluid convection in a single rock crack are established in the paper . The critical criteria for the onset of convection in such a configuration are found by linear d... Dynamic equations controlling the thermally-driven fluid convection in a single rock crack are established in the paper . The critical criteria for the onset of convection in such a configuration are found by linear dynamic analysis of the equations and the stability of the convection discussed by nonlinear analysis method . The research demonstrates that the critical Rayleigh number has a magnitude 103. While the Rayleigh number R of real ore-forming fluids exceeds this value , the convection happens , and as R becomes larger , the fluid convection pattern develops from nonequilibrium steady states to double-periodically produced limit cycles and eventually to chaos (turbulences ).The implication of these dynamic analyses for the ore-forming processes of late-magma tic hydrothermal deposits is also discussed in the paper . 展开更多
关键词 thermally -driven fluid onset of convection STABILITY double -diffusive convection dynamics of ore -forming processes hydrothermal deposit .
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Characteristics of Pegmatite-Related Fluids and Significance to Ore-Forming Processes in the Zhaxikang Pb-Zn-Sb Polymetallic Deposit,Tibet,China 被引量:6
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作者 XIE Yuling WANG Bogong +4 位作者 LI Yingxu LI Guangming DONG Suiliang GUO Xiang WANG Lei 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2015年第3期811-821,共11页
The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less... The Zhaxikang Pb-Zn-Sb polymetallic deposit is one of the most important deposits in the newly recognized southern Tibet antimony-gold metallogenic belt.Compared to the porphyry deposits in the Gangdese belt,much less researches have addressed these deposits,and the genesis of the Zhaxikang deposit is still controversial.Based on field investigation,petrographic,microthermometric,Laser Raman Microprobe(LRM) and SEM/EDS analyses of fluid,melt-fluid,melt and solid inclusions in quartz and beryl from pegmatite,this paper documents the characteristics and the evolution of primary magmatic fluid which was genetically related to greisenization,pegmatitization,and silification in the area.The results show that the primary magmatic fluids were derived from unmixing between melt and fluid and underwent a phase separation process soon after the exsolution.The primary magmatic fluids are of low salinity,high temperature,and can be approximated by the H_2O-NaCl-CO_2 system.The presence of Mn-Fe carbonate in melt-fluid inclusions and a Zn-bearing mineral(gahnite) trapped in beryl and in inclusions from pegmatite indicates high Mn,Fe,and Zn concentrations in the parent magma and magmatic fluids,and implies a genetic link between pegmatite and Pb-Zn-Sb mineralization.High B and F concentrations in the parent magma largely lower the solidus of the magma and lead to late fluid exsolution,thus the primary magmatic fluids related to pegmatite have much lower temperature than those in most porphyry systems.Boiling of the primary magmatic fluids leads to high-salinity and high-temperature fluids which have high capacity to transport Pb,Zn and Sb.The decrease in temperature and mixing with fluids from other sources may have caused the precipitation of Pb-Zn-Sn(Au) minerals in the distal fault systems surrounding the causative intrusion. 展开更多
关键词 Zhaxikang Pb-Zn-Sb deposit South Tibte Sb-Au metallogenic belt fluid inclusion pegmatite ore-forming process
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Fluid Evolution and Ore-forming Processes of the Jiama Cu Deposit, Tibet: Evidence from Fluid Inclusions 被引量:2
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作者 YAO Xiaofeng LIU Jiajun +2 位作者 TANG Juxing ZHENG Wenbao ZHANG Zhi 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2018年第1期127-143,共17页
The Jiama deposit is a large copper deposit in Tibet. Mineralization occurs in three different host rocks: skarn, hornfels and porphyry. A detailed fluid inclusion study was conducted for veins in the different host ... The Jiama deposit is a large copper deposit in Tibet. Mineralization occurs in three different host rocks: skarn, hornfels and porphyry. A detailed fluid inclusion study was conducted for veins in the different host rocks to investigate the relationship between fluid evolution and ore-forming processes. Based on examination of cores from 36 drill holes, three types of veins (A, B and D) were identified in the porphyries, four types (I, II, III and IV) in the skarn, and three (a, b and c) in the hornfels. The crosscutting relationships of the veins and that of the host rocks suggest two hydrothermal stages, one early and one late stage. Fluid inclusions indicate that the Jiama hydrothermal fluid system underwent at least two episodes of fluid boiling. The first boiling event occurred during the early hydrothermal stage, as recorded by fluid inclusions hosted in type A veins in the porphyries, type a veins in the hornfels, and wollastonite in the skarns. This fluid boiling event was associated with relatively weak mineralization. The second boiling event occurred in the late hydrothermal stage, as determined from fluid inclusions hosted in type B and D veins in the porphyries, type I to IV veins in the skarns, and type b and c veins in the hornfels. This late boiling event, together with mixing with meteoric water, was responsible for more than 90% of the metal accumulation in the deposit. The first boiling only occurred in the central part of the deposit and the second boiling event took place across an entire interlayered structural zone between hornfels and marble. A spatial zoning of ore-elements is evident, and appears to be related to different migration pathways and precipitation temperatures of Cu, Mo, Pb, Zn, Au and Ag. 展开更多
关键词 fluid inclusion fluid evolution ore-forming processes Jiama deposit TIBET
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Modeling Hydrothermal Transfer Processes in Permafrost Regions of Qinghai-Tibet Plateau in China 被引量:4
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作者 HU Guojie ZHAO Lin +6 位作者 LI Ren WU Tonghua WU Xiaodong PANG Qiangqiang XIAO Yao QIAO Yongping SHI Jianzong 《Chinese Geographical Science》 SCIE CSCD 2015年第6期713-727,共15页
Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global wanning. In this study the coupled heat and mass transfer model for (CoupModel) the soil-plant-atmosphere-syst... Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global wanning. In this study the coupled heat and mass transfer model for (CoupModel) the soil-plant-atmosphere-system is applied in high-altitude permafrost regions and to model hydrothermal transfer processes in freeze-thaw cycles. Measured meteorological forcing and soil and vegetation properties are used in the CoupModel for the period from January 1, 2009 to December 31, 2012 at the Tanggula observation site in the Qinghai-Tibet Plateau. A 24-h time step is used in the model simulation. The results show that the simulated soil temperature and water content, as well as the frozen depth compare well with the measured data. The coefficient of determination (R2) is 0.97 for the mean soil temperature and 0.73 for the mean soil water content, respectively. The simulated soil heat flux at a depth of 0-20 cm is also consistent with the monitored data. An analysis is performed on the simulated hydrothermal transfer processes from the deep soil layer to the upper one during the freezing and thawing period. At the beginning of the freezing period, the water in the deep soil layer moves upward to the freezing front and releases heat during the freezing process. When the soil layer is completely frozen, there are no vertical water ex- changes between the soil layers, and the heat exchange process is controlled by the vertical soil temperature gradient. During the thaw- ing period, the downward heat process becomes more active due to increased incoming shortwave radiation at the ground surface. The melt water is quickly dissolved in the soil, and the soil water movement only changes in the shallow soil layer. Subsequently, the model was used to provide an evaluation of the potential response of the active layer to different scenarios of initial water content and climate warming at the Tanggula site. The results reveal that the soil water content and the organic layer provide protection against active layer deepening in summer, so climate warming will cause the permafrost active layer to become deeoer and permafrost degradation. 展开更多
关键词 PERMAFROST coupled heat and mass transfer model (CoupModel) soil temperature soil moisture hydrothermal processes active layer
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Dynamics of Ore-Forming Processesof the Stratabound Skarn Copper Depositsof Tongling, Anhui Province 被引量:2
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作者 Yu Chongwen, Jiang Yaosong and Xiao Zhengyu China University of Geosciences, Beijing 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 1996年第1期59-73,共15页
The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and ... The skarn and ore bodies of the stratabound skarn copper deposits of Tongling, Anhui Province, are both controlled by definite stratigraphic horizons, and they are concordant with the strata. They occur as layers and layer-like bodies in permeable carbonate rocks of the Middle-Upper Carboniferous Huanglong and Chuanshan Formations which are underlain by impermeable shale or siliceous rocks of the Upper Devonian Wutong Formation. The authors study the dynamics of ore-forming processes of the ore deposits with the dynamic model of coupled transport and reaction, and the following results are obtained: The salinity gradient and flow rate of the ore-forming fluids can both promote the mixing and reaction of juvenile water and formation water, and the permeable strata are favourable sites for the intense transport-reaction of mixing and the formation of deposits. (2) As isothermal transport-reaction took place along the bedding of strata, the moving transport-reaction front formed at the contact between the ore-forming fluids and the rocks advanced slowly along the permeable strata, and then stratiform skarn and ore bodies concordant with the strata were formed. (3) The gradient transport-reaction taking place across the isotherms in the cross-bedding direction caused the mineralogical composition to alter gradually from magnesian skarn to sulphide ore bodies. 展开更多
关键词 stratabound skarn ore deposit dynamics of ore-forming processes dynamics of coupled transport and reaction transport-reaction of mixing isothermal transport-reaction gradient transport-reaction
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Hydrothermal Processes in the Solar System:A Review 被引量:3
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作者 Franco PIRAJNO Martin J. Van KRANENDONK Long XIAO 《地质科技情报》 CAS CSCD 北大核心 2008年第1期1-12,共12页
最近美国航空与空间计划署(NASA)开展的卡西尼—惠更斯外空探测计划发现,在直径为500km的卫星——土卫二上存在水冰和间隙泉的喷发活动。这一现象和在火星上工作的"机遇号"和"勇气号"漫游车所发现的液态水一起,证... 最近美国航空与空间计划署(NASA)开展的卡西尼—惠更斯外空探测计划发现,在直径为500km的卫星——土卫二上存在水冰和间隙泉的喷发活动。这一现象和在火星上工作的"机遇号"和"勇气号"漫游车所发现的液态水一起,证明了除地球以外的其他星球上过去和现在都存在水,其中的一些星体还有火山活动的证据,这意味着这些星球上可能存在过热液活动地质过程。讨论了火星、木卫二和土卫二可能存在的热液系统类型。这些热液系统类型是根据地球上的构造背景进行相似性研究后得出的,例如海底、火山和裂谷系统。将东非裂谷和贝加尔湖裂谷系统与火星Tharsis高原上巨大的水手大峡谷进行了对比,这些地区都是由地幔柱作用下构造—热液活动导致的地壳抬升、火山和裂谷作用。在火星上,地下冰或低温层会在火山活动和(或)小行星或彗星撞击作用下溶解而形成热液对流。 展开更多
关键词 热液活动过程 火星 木卫二 土卫二
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A preliminary study on microtextures,structures and mineralizing processes of hydrothermal chimneys in Mariana Trough
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作者 Zhang Deyu 《Acta Oceanologica Sinica》 SCIE CAS CSCD 1996年第4期469-483,485-492,共24页
Microtextures and struetures of 9 hydrothermal chimneys sampled on the small spreading ridge Of the Mari ana Trough during SONNE Cruise 57 (SO57) and 69 (SO69) in 1988 and 1990 were studied by means of scanning elec... Microtextures and struetures of 9 hydrothermal chimneys sampled on the small spreading ridge Of the Mari ana Trough during SONNE Cruise 57 (SO57) and 69 (SO69) in 1988 and 1990 were studied by means of scanning electron microscope. The results reveal that the two types of chimneys from the Mariana Trough. the 'silicic chimneys' containing Fe sulfide and the pure 'silica chimneys' without sulfide, vary distinctly not only in mineral and chemical compositions, but also in microtextures and structures. The silicic chimneys generally show three major types of microtextures.The inside of the chimneys is dominated by holocrystalline or semicrystalline idiomorphic and hypidiomorphic granular textures and the outwall by amorphous colloidal texture. In some of the silicic chimneys relict texture is observed. However,the pure silica chimneys show chiefly amorphous colloidal texture from the inside to the outwall. Microstructurally. theinside of the silicic chimneys is dominated by a 'silica-covering' structure and a 'voidfilling' structure, and the outwall by a chain-like or three-dimentional chain-network structure built up by individual opal globules, whereas the pure silica chimneys are mainly three-dimentional chain-network and the dense silica bands in structure. These variations suggest that not only mineralizing conditions but also processes differ distinctly during the formation of the two types of chimneys, and that hydrothermal mineralization in the Mariana Trough shows a multistage or multieplsodical nature. 展开更多
关键词 The Mariana Trough hydrothermal chimneys microtextures and structures mineralizing processes
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Conversion of ferric oxide to magnetite by hydrothermal reduction in Bayer digestion process 被引量:5
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作者 李小斌 刘楠 +4 位作者 齐天贵 王一霖 周秋生 彭志宏 刘桂华 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第10期3467-3474,共8页
Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina productio... Digesting aluminum-bearing minerals and converting ferric oxide to magnetite simultaneously in Bayer digestion process is crucially important to deal with high-iron diasporic bauxite economically for alumina production.The reaction behaviors of hydrothermal reduction of ferric oxide in alkali solution were studied by both thermodynamic calculation and experimental investigation.The thermodynamic calculation indicates that Fe3O4 can be formed by the conversion of Fe2O3 at proper redox potentials in alkaline solution.The experimental results show that the formation ratio of Fe3O4 either through the reaction of Fe and Fe2O3 or through the reaction of Fe and H2O in alkaline aqueous solution increases remarkably with raising the temperature and alkali concentration,suggesting that Fe(OH)3- and Fe(OH)4- form by dissolving Fe and Fe2O3,respectively,in alkaline aqueous solution and further react to form Fe3O4.Moreover,aluminate ions have little influence on the hydrothermal reduction of Fe2O3 in alkaline aqueous solution,and converting iron minerals to magnetite can be realized in the Bayer digestion process of diasporic bauxite. 展开更多
关键词 Bayer process DIGESTION hydrothermal reduction ferric oxide MAGNETITE
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Impact of hydrothermal process on the nutrient ingredients of restaurant garbage 被引量:16
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作者 REN Lian-hai NIE Yong-feng +2 位作者 LIU Jian-guo JIN Yi-ying Sun Lu 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2006年第5期1012-1019,共8页
In order to recover the nutrient resource from restaurant garbage, a complete trial with 2 factors on 5 levels of experiments was carried out. The temperature and heating time are the main factors influencing on hydro... In order to recover the nutrient resource from restaurant garbage, a complete trial with 2 factors on 5 levels of experiments was carried out. The temperature and heating time are the main factors influencing on hydrothermal process (HP) by which improves the degradability and digestibility of the restaurant garbage favorably to make animal feeds or fertilizer. The results showed the variation of protein, saccharide, and oil in the garbage. It showed that protein dissolved and liquefied during hydrothermal process, which made organic nitrogen in solid phase transfer to liquid phase. After heating at 180℃ for 60min, organic nitrogen in liquid phase began to transform into ammonia. It also showed that hydrothermal process could promote the dextrinization, dissolution of the starch and its hydrolysis to reducing sugar, due to that starch in the restaurant garbage decreases and reducing sugar increases. When the temperature reached 140℃, the reducing sugar started to decrease due to chemical reactions. The cellulose was stable at 100-180℃. The floatable oil increased markedly in the hydrothermal process. The suitable condition for de-oil was observed at 160℃ heating for 80 min. Furthermore, the extraction of grease from the solid phase accords with first-order reaction dynamic model. 展开更多
关键词 restaurant garbage hydrothermal process PROTEIN SACCHARIDE LIPID
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Application of Spectral Angle Mapper Classification to Discriminate Hydrothermal Alteration in Southwest Birjand, Iran, Using Advanced Spaceborne Thermal Emission and Reflection Radiometer Image Processing 被引量:5
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作者 Maryam ABDI Mohammd H. KARIMPOUR 《Acta Geologica Sinica(English Edition)》 SCIE CAS CSCD 2012年第5期1289-1296,共8页
The purpose of this study is to evaluate the Spectral Angle Mapper (SAM) classification method for determining the optimum threshold (maximum spectral angle) to unveil the hydrothermal mineral assemblages related ... The purpose of this study is to evaluate the Spectral Angle Mapper (SAM) classification method for determining the optimum threshold (maximum spectral angle) to unveil the hydrothermal mineral assemblages related to mineral deposits. The study area indicates good potential for Cu-Au porphyry, epithermal gold deposits and hydrothermal alteration well developed in arid and semiarid climates, which makes this region significant for Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) image processing analysis. Given that achieving an acceptable mineral mapping requires knowing the alteration patterns, petrochemistry and petrogenesis of the igneous rocks while considering the effect of weathering, overprinting of supergene alteration, overprinting of hypogene alteration and host rock spectral mixing, SAM classification was implemented for argillic, sericitic, propylitic, alunitization, silicification and iron oxide zones of six previously known mineral deposits: Maherabad, a Cu-Au porphyry system; Sheikhabad, an upper part of Cu-Au porphyry system; Khoonik, an Intrusion related Au system; Barmazid, a low sulfidation epithermal system; Khopik, a Cu-Au porphyry system; and Hanish, an epithermal Au system. Thus, the investigation showed that although the whole alteration zones are affected by mixing, it is also possible to produce a favorable hydrothermal mineral map by such complementary data as petrology, petrochemistry and alteration patterns. 展开更多
关键词 hydrothermal alteration Spectral Angle Mapper Advanced Spaceborne Thermal Emission and Reflection Radiometer image process Iran
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Lincang Superlarge Germanium Deposit in Yunnan Province,China: Sedimentation,Diagenesis,Hydrothermal Process and Mineralization 被引量:3
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作者 Zhuang Hanping Lu Jialan Fu Jiamo Liu Jinzhong Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640 《Journal of Earth Science》 SCIE CAS CSCD 1998年第2期37-44,共8页
The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements ... The mineralization is related closely to sedimentation, diagenesis and hydrothermal processes. In this paper, investigations are carried out on coal occurrence, maceral composition, inorganic minerals, trace elements and huminite reflectance. It is concluded that the source of Lincang superlarge deposit is mainly the muscovite granite in the west edge of the basin. During sedimentation, Ge (germanium) was leached out and entered the basin. Ge was adsorbed by lower organism and humic substances in water. Lincang lignite underwent three thermal processes: peatification, early diagenesis and hydrothermal transformation. During peatification, Ge was adsorbed or complexed by humic colloids. During early diagenesis, the Ge associated with humic acids was hard to mobilize or transport. Most of Ge entered the structure of huminite while a small amount of Ge was associated with residual humic acids as complex or humate. During hydrothermal transformation, the heated natural water or deep fluid from basement encountered the coal layer within tectonic weak zone. SO 2- 4 was reduced by coal organic matter. Pyrite and calcite formed. Hydrothermal process did not contribute significantly to mineralization. 展开更多
关键词 Lincang superlarge germanium deposit SEDIMENTATION DIAGENESIS hydrothermal process mineralization.
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Developing super-hydrophobic and corrosion-resistant coating on magnesium-lithium alloy via one-step hydrothermal processing 被引量:5
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作者 Guowei Wang Dan Song +5 位作者 Yanxin Qiao Jiangbo Cheng Huan Liu Jinghua Jiang Aibin Ma Xiaolong Ma 《Journal of Magnesium and Alloys》 SCIE EI CAS CSCD 2023年第4期1422-1439,共18页
Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium allo... Formation of super-hydrophobic and corrosion-resistant coatings can provide significant corrosion protection to magnesium alloys.However,it remains a grand challenge to produce such coatings for magnesium-lithium alloys due to their high chemical reactivity.Herein,a one-step hydrothermal processing was developed using a stearic-acid-based precursor medium,which enables the hydrothermal conversion and the formation of low surface energy materials concurrently to produce the super-hydrophobic and corrosion-resistant coating.The multiscale microstructures with nanoscale stacks and microscale spheres on the surface,as well as the through-thickness stearates,lead to the super-hydrophobicity and excellent corrosion resistance of the obtained coating. 展开更多
关键词 Magnesium-lithium alloy Super-hydrophobic coating One-step hydrothermal process Corrosion resistance Multiscale microstructure
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In-situ experiment investigations of hydrothermal process of highway in deep seasonal frozen soil regions of Inner Mongolia, China 被引量:5
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作者 ZHANG Hong-wei WANG Xue-ying +1 位作者 ZHAO Xin LIU Peng-fei 《Journal of Central South University》 SCIE EI CAS CSCD 2020年第7期2082-2093,共12页
To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years,... To reveal the influencing factors and changing rules for the hydrothermal interaction process of highway subgrade, the field measurements of Shiwei-Labudalin Highway in Inner Mongolia, China was conducted for 3 years, based on which the freezing-thawing rules and water content changing characteristics were analyzed. The main results show the subgrade presents a frequent freezing-thawing alternation, and the water content of subgrade exhibits an obvious seasonal alternation. The subbase has the maximum water content, while the base has the minimum water content. The change of water flux is concentrated in the thawing period and consistent with the change of temperature gradient. The subbase layer has the most active water flux due to the heat absorption and impermeability of pavement that easily causes the water accumulation in this layer. Therefore, the prevention and treatment for the freezing-thawing disease should be started from heat insulation and water resistance. 展开更多
关键词 subgrade engineering hydrothermal process field observation seasonal frozen soil regions freezing-thawing disease
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Seasonal freezing-thawing process and hydrothermal characteristics of soil on the Loess Plateau, China 被引量:3
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作者 CHOU Ya-ling WANG Li-jie 《Journal of Mountain Science》 SCIE CSCD 2021年第11期3082-3098,共17页
In seasonally frozen soil regions,freezing-thawing action and hydrothermal effect have strong influence on physical and mechanical behavior of shallow soil.A field experiment on the Loess Plateau in Northwest China wa... In seasonally frozen soil regions,freezing-thawing action and hydrothermal effect have strong influence on physical and mechanical behavior of shallow soil.A field experiment on the Loess Plateau in Northwest China was carried out to analyze the freezing-thawing process and hydrothermal characteristics of shallow soil considering the climate influence.The results show that the maximum seasonal freezing depth under bare ground surface in this area is from 20 cm to 50 cm.The ground temperature shows a similar changing trend with air temperature,but it has lagged behind the air temperature,and the ground temperature amplitude exponentially decreases with the increase of soil depth.The seasonally frozen soil has experienced four typical stages:unfrozen period,alternate freezing period,freezing period and alternate thawing period.The freezing-thawing process is characterized by unidirectional freezing and bidirectional thawing.The water content of shallow soil is significantly affected by air temperature,evaporation and precipitation,and the soil water content shows a"low-high-low"changing trend with the increase of depth.The soil temperature and water content interact with each other,and are often coupled.The variation trend of soil moisture with time is consistent with the change trend of the ground temperature with time in each soil layer,andthe degree of consistency is higher in the near surface soil than that in the lower layer.Also,the spatial-temporal characteristics of soil moisture and temperature is that the volumetric water content and ground temperatureof near surface soil have strong variability,and the range valueKa and coefficient of variation Cvof soil water content and ground temperaturein different seasons show a decreasing trend with the increase of depth. 展开更多
关键词 Seasonally frozen soil Freezing-thawing process hydrothermal characteristics Loess Plateau
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Hexagonal hematite platelets synthesized from pyrite cinders by hydrothermal process 被引量:3
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作者 刘昭成 郑雅杰 《Journal of Central South University》 SCIE EI CAS 2011年第5期1377-1382,共6页
Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process, using a highly concentrated ferric hydroxide as precursor. The precursor was prepared by adding ammonia to the ferr... Well-crystallized hexagonal hematite (α-Fe2O3) platelets were synthesized by hydrothermal process, using a highly concentrated ferric hydroxide as precursor. The precursor was prepared by adding ammonia to the ferric sulfate solution which was obtained by leaching pyrite cinders with sulfuric acid. Structure and morphology of the synthesized products were investigated by X-ray diffraction, scanning electron microscope, transmission electron microscope and selected area electron diffraction. The results reveal that the reaction temperature has significant effects on the structure, size and shape of the synthesized hematite particles. Typical hexagonal hematite platelets, about 0.4-0.6 μm in diameter and 0.1 μm in thickness, were prepared at 230 ℃ for 0.5 h. Al^3+, contained in the sulfuric acid leaching solution as an impurity, plays an extremely important role in the formation of hexagonal hematite. In addition, a possible mechanism about the formation of hexagonal hematite platelets was proposed. 展开更多
关键词 HEMATITE Α-FE2O3 pyrite cinders hydrothermal process hexagonal platelets
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NMR studies of stock process water and reaction pathways in hydrothermal carbonization of furfural residue 被引量:1
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作者 Fen Yue Christian Marcus Pedersen +5 位作者 Xiuyin Yan Yequn Liu Danlei Xiang Caifang Ning Yingxiong Wang Yan Qiao 《Green Energy & Environment》 SCIE 2018年第2期163-171,共9页
Hydrothermal carbonization(HTC) is a valuable approach to convert furfural residue(FR) into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains... Hydrothermal carbonization(HTC) is a valuable approach to convert furfural residue(FR) into carbon material. The prepared biochars are usually characterized comprehensively, while the stock process water still remains to be studied in detail. Herein, a NMR study of the main components in stock process water generated at different HTC reaction conditions was reported. Various qualitative and quantitative NMR techniques(~1H and ^(13)C NMR,~1H-~1H COSY and ~1H-^(13)C HSQC etc.) especially 1D selective gradient total correlation spectroscopy(TOCSY NMR) were strategically applied in the analysis of HTC stock process water. Without separation and purification, it was demonstrated that the main detectable compounds are 5-hydroxymethylfurfural, formic acid, methanol, acetic acid, levulinic acid, glycerol, hydroxyacetone and acetaldehyde in this complicate mixture. Furthermore, the relationship between the concentration of major products and the reaction conditions(180-240 ℃ at 8 h, and 1-24 h at 240 ℃) was established. Finally, reasonable reaction pathways for hydrothermal conversion of FR were proposed based on this result and our previously obtained characteristics of biochars. The routine and challenging NMR methods utilized here would be an alternative other than HPLC or GC for biomass conversion research and can be extended to more studies. 展开更多
关键词 NMR hydrothermal carbonization Furfural residue Stock process water
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Dechlorination Behavior of Mixed Plastic Waste by Employing Hydrothermal Process and Limestone Additive 被引量:1
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作者 P. Prawisudha T. Namioka L. Liang K. Yoshikawa 《Journal of Environmental Science and Engineering》 2011年第4期432-439,共8页
The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal tre... The usage of plastic-impregnated waste derived solid fuel in conventional combustor is hindered by many technical factors, especially its organic chlorine content. In this paper, experimental study of hydrothermal treatment on mixed plastic waste using the mixture of polypropylene, polystyrene, polyethylene and polyvinyl chloride (PVC) has been performed to observe the dechlorination effect of hydrothermal treatment on the waste. The system was generally applying saturated steam at around 2.4 MPa in a stirring reactor for about 90 minutes. After undergoing the process, the organic chlorine in treated plastic waste was reduced to 1,700 ppm level while the inorganic chlorine content was increased, suggesting an organic chlorine conversion phenomenon to inorganic chlorine, accompanied with low pH due to dehydrochlorination process. Additional limestone (Ca(OH)2) in subsequent experiment showed that the similar phenomenon was occurred but with higher pH and lower chlorine content in the condensed water, suggesting the production of inorganic salt rather than hydrochloric acid. Laboratory scale experiment was also performed to confirm the dechlorination phenomena especially for PVC, and the result showed that the main parameter which affected the dechlorination phenomena was the amount of water in hydrothermal process rather than limestone addition. It is suggested that a combination ofhydrothermal process and alkali addition would produce a low-chlorine solid product from plastic waste, promoting its usage as alternative solid fuel. 展开更多
关键词 Plastic waste treatment chlorine removal hydrothermal process alkali additive
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Synthesis and photocatalytic properties of InVO_4 sol containing nanocrystals by mild hydrothermal processing 被引量:3
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作者 方海波 徐明霞 +1 位作者 戈磊 何智远 《中国有色金属学会会刊:英文版》 CSCD 2006年第B01期373-376,共4页
The precursor precipitation of InVO4 was synthesized by co-precipitation using indium trichloride (InCl3), ammonium metavanadate (NH4VO3) and ammonia (NH3·H2O) as raw materials. The InVO4 sols with orthorhombic p... The precursor precipitation of InVO4 was synthesized by co-precipitation using indium trichloride (InCl3), ammonium metavanadate (NH4VO3) and ammonia (NH3·H2O) as raw materials. The InVO4 sols with orthorhombic phase were obtained by hydrothermal treatment (the precursor precipitation solution at 423 K, for 4 h). The precursor and sol of InVO4 were characterized by X-ray diffraction (XRD), Fourier Transform Infra-red spectra (FT-IR), scanning electron microscopy (SEM) measurements. The XRD patterns indicate that the InVO4 precursor is amorphous phase, InVO4 sol contains orthorhombic InVO4 nanocrystals. The results also reveal that the pH value of the reaction mixture and reaction temperature play important roles to the target phase. InVO4-TiO2 thin films on glass slides were prepared by the dip-coating method from the composite sol. The photocatalytic properties of the InVO4-TiO2 thin films were investigated by the photocatalytic degradation of methyl orange solution. The results indicate that it has better photocatalytic activities than pure TiO2 thin films or pure InVO4 thin films with UV light. 展开更多
关键词 中度水热法 InVO4纳米晶溶胶 共沉淀 合成 光催化性质
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Gas Sensing Properties of ZnO Tetrapod-Like Whiskers Prepared by Hydrothermal Process
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作者 Jiaqiang Xu Yuping Chen +1 位作者 Huanxin Wang Jianian Shen 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2006年第A03期185-187,共3页
ZnO tetrapod-like whiskers were prepared through a hydrothermal process using zinc powder as raw material.Its microstructure and morphology were characterized by X-ray diffraction (XRD) and transmission electron micro... ZnO tetrapod-like whiskers were prepared through a hydrothermal process using zinc powder as raw material.Its microstructure and morphology were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The XRD results showed that the crystal structure of as-obtained sample can be indexed to hexagonal wurtzite ZnO.TEM results revealed that the ZnO sample took on tetrapod-like whisker shape.The gas sensors were prepared with the traditional sintering process and their gas sensitivities were detected.The test results of gas sensitivity showed that the sensors based on ZnO tetrapod-like whiskers are very sensitive to dilute ethanol vapor and H_2S.The relatively high sensitivity and selectivity of these sensors made from ZnO tetrapod-like whiskers demonstrated the potential for developing a new class of selective ethanol sensors. 展开更多
关键词 hydrothermal process gas sensor zinc oxide WHISKER
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Effects of Processing Conditions on Hydrothermal Synthesis of K_(0.5)Bi_(0.5)TiO_3 Nano-Powders
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作者 Hongyan Miao Min Dong Guoqiang Tan Jia Li 《稀有金属材料与工程》 SCIE EI CAS CSCD 北大核心 2006年第A03期561-563,共3页
Potassium bismuth titanate nanosized powders were prepared by the hydrothermal method using Ti(C_4H_9O)_4 and Bi(NO_3)_3·5H_2O as raw materials in alkaline solution.The phase composition,particle size and morphol... Potassium bismuth titanate nanosized powders were prepared by the hydrothermal method using Ti(C_4H_9O)_4 and Bi(NO_3)_3·5H_2O as raw materials in alkaline solution.The phase composition,particle size and morphology of the powders were studied by XRD and TEM analysis.The results showed that the powders were well crystallized and dispersed.The crystal phase of the powders was K_(0.5)Bi_(0.5)TiO_3 with the grain size of about 50 nm~100 nm.Hydrothermal temperature and alkaline concentrations had great effects on the phase composition and morphology of the resultant powders.Pure K_(0.5)Bi_(0.5)TiO_3 powders could be synthesized at 170℃~180℃with KOH concentration of 8 mol/L~12 mol/L. 展开更多
关键词 processing conditions hydrothermal synthesis potassium bismuth titanate POWDERS
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