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Kinetics of Hydrothermal Reactions of Minerals in Near-critical and Supercritical Water

Acta Geologica Sinica(English Edition) 2000年第2期74卷 400-405页

作者： zhang Ronghua HU Shumin zhang xuetong Open Research Laboratory of Geochemical Kinetics Chinese Academyof Geological Sciences26 Baiwanzhuang RoadBeijing 100037

This work presents new experimental results on the kinetics of mineral dissolution in near-critical and supercritical water in a temperature range (T) from 25 to 400°C and a constant pressure of 23 MPa. Kinetic experiments were carried out by using a flow reactor (packed bed reactor) of an open system. The dissolution rates of albite and magnetite were measured under these experimental conditions. Na, Al and Si release rates for albite dissolution in water were measured as a function of the temperature and flow velocity in the reaction system. The maximum release rates of Na, Al and Si of albite dissolution in the hydrothermal flow systems under different flow velocities were always obtained at 300°C, that is to say, the maximum albite dissolution rates in the flow systems, regardless of different flow rates, were repeatedly measured at 300°C. Results indicate a wide fluctuation in albite dissolution rates occurring close to the critical point of water. The dissolution rates increased when the temperatures increased from 25 to 300°C and decreased when the temperatures increase from 300 to 400°C. At some flow velocities, the dissolution rates rose as the temperature surpassed 374°C. Albite dissolution was incongruent in water at most temperatures. It was only at 300°C that albite dissolution was congruent. The albite dissolution from 25 to 300°C (at 23 MPa) will change from incongruent to congruent, whereas from subcritical 300 to 400°C (at 23 MPa), the dissolution will change from congruent to incongruent. The release ratio of Al/Si (or Na/Si) is positive at T300°C. The dissolution rates of magnetite in water increased with increasing T until T at the critical point of water or around it. The authors believe that this is caused by the wide fluctuations in water properties under the conditions from the near-critical to supercritical state.

关键词： kinetics hydrothermal reaction critical state

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A Study of Near-and Super-Critical Fluids Using Diamond Anvil Cell and in-Situ FT-IR Spectroscopy

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Acta Geologica Sinica(English Edition) 2000年第2期74卷 412-417页

作者： HU Shumin zhang Ronghua zhang xuetong Open Research Lab.of Geochemical Kinetics Chinese Academy of Geological Sciences26 Baiwanzhuang RoadBeijing100037

The phase relation and solution structure of water and NaCl aqueous solution have been observed and examined by using the hydrothermal diamond anvil cell (HDAC) at elevated temperatures and pressures and the in situ FT-IR spectroscopy. The temperature of observations ranges from 25 to 850°C and the pressure up to 10 or 30 kb. At first, we observed the phase transition process from halite+liquid+vapour (H+L+V) to L+H, then to L (or supercritical fluid, SCF), and another path: H+L+V→L+V→L (or SCF) in heating process. By means of the visual microscope, the authors found that in the L+V immiscibility field L+V exhibits an ordered structure, i.e. a large visual cluster of solvent around ions. The liquid phase is manifested by vapour bubbles. When phase transitions are observed, the authors examined their infrared spectra by using the FT-IR microscopy simultaneously. In the case of the phase transition from liquid (L) to liquid + vapor (L+V) immisciblity field of NaCl solutions, a sudden change (strong frequency shift) of infrared spectra of the aqueous solution is observed near the critical temperature of water as the temperature is raised from 25 to 650°C. The frequency of the maximum intensity of OH symmetric and asymmetric vibration varies with respect to temperature. The sharp peak of the OH stretching vibration of the maximum intensity appears in an interval from 300 to 400°C. It is indicated that the hydrogen bonding network is weakened and broken at last near the critical point of water, which causes the aqueous solution to become more associated. Besides, a pressure indicator (a mineral or compound) was introduced to the HDAC.

关键词： diamond anvil cell critical state in situ IR microscopy

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Experimental Study of the Distribution of Au and Cu in Aqueous Vapor Phase at High Temperatures and Its Role on Ore-forming Transportation

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Acta Geologica Sinica(English Edition) 2008年第4期82卷 875-883页

作者： zhang Ronghua HU Shumin zhang xuetong Open Research Laboratory of Geochemical Kinetics Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing 100037

This study focuses on experiments of Au and Cu dissolved in vapor phase in hydrothermal fluids. Experiments prove that Au and Cu can re-distribute in vapor phase and liquid phase during separation of Au- and Cu-bearing supercritical fluids to vapor and liquid phases. These experimental results can illustrate some ore geneses, where boiling phenomena of ore fluids were found. Au- and Cubearing NaHCO3-HCl solutions were heated up to more than 350℃ in the main vessel, and then passed through a phase separator in a temperature range from 250℃ to 300℃, separated into vapor and liquid phases. We collected and analyzed the liquid and vapor samples separately, and found that Au and Cu dissolved and distributed in vapor phase. In some cases, the concentrations of Au and Cu in vapor are higher than those in liquid phase. Those experiments are used to interpret field observations of fluid inclusion data of some Au and Cu deposits, and demonstrate that some Au and Cu ore deposits are derived from metals transportation in vapor phase.

关键词： Au and Cu in vapor phase ore genesis boiling phenomena liquid and vapor phase separation metal transportation in gases

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Calcium-Doped Boron Nitride Aerogel Enables Infrared Stealth at High Temperature Up to 1300℃

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Nano-Micro Letters 2022年第1期14卷 295-306页

作者： Mengya Zhu Guangyong Li Wenbin Gong Lifeng Yan xuetong zhang School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026People’s Republic of China Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of SciencesSuzhou 215123People’s Republic of China School of Physics and Energy Xuzhou University of TechnologyXuzhou 221018People’s Republic of China School of Chemistry and Materials Science University of Science and Technology of ChinaHefei 230026People’s Republic of China Division of Surgery&Interventional Science University College LondonLondon NW32PFUK

Boron nitride(BN)aerogels,composed of nanoscale BN building units together with plenty of air in between these nanoscale building units,are ultralight ceramic materials with excellent thermal/electrical insulation,great chemical stability and high-temperature oxidation resistance,which offer considerable advantages for various applications under extreme ***,previous BN aerogels cannot resist high temperature above 900℃ in air atmosphere,and hightemperature oxidation resistance enhancement for BN aerogels is still a great ***,a calcium-doped BN(Ca-BN)aerogel with enhanced high-temperature stability(up to~1300℃ in air)was synthesized by introducing Ca atoms into crystal structure of BN building blocks via high-temperature reaction between calcium phosphate and melamine diborate *** Ca-BN aerogels could resist the burning of butane flame(~1300℃)and keep their megashape and microstructure very ***,Ca-BN aerogel serves as thermal insulation layer,together with Al foil serving as both low-infrared-emission layer and high-infrared-reflection layer,forming a combination structure that can effectively hide high-temperature target(heated by butane flame).Such successful chemical doping of metal element into crystal structure of BN may be helpful in the future design and fabrication of advanced BN aerogel materials,and further extending their possible applications to extremely high-temperature environments.

关键词： Aerogel Boron nitride Calcium doping Infrared stealthy Butane flame

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Mineral Surface after Reaction with Aqueous Solution at High Temperatures and Pressures

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Acta Geologica Sinica(English Edition) 2000年第2期74卷 406-411页

作者： zhang xuetong zhang Ronghua HU Shumin YU Wenbin Open Research Laboratory of Geochemical Kinetics Chinese Academy of GeologicalSciences26 Baiwanzhuang RoadBeijing 100037

This work presents new experimental results on surface chemistry of reacting minerals and interface kinetics between mineral and aqueous solutions. These experiments were carried out using a flow reactor (packed bed reactor) of an open system as well as a continuous stirred tank reactor, CSTR. The authors measured reaction rates of such minerals as zeolite, albite and carbonate (rhodochrosite, dolomite) in various solutions, and tested corresponding mineral surface by using SEM, XPS, SIMS, etc. This paper mainly presents the experimental results of zeolite dissolution in water and in low pH solutions at room temperature, and dolomite dissolution at elevated temperatures. The results show that the release rates of Si, Al and Na of zeolite are different in most cases. The incongruent dissolution of zeolite is related to surface chemical modifications. The Na, Al and Si release rates for dissolution of albite and zeolite in water and various solutions were measured as a function of temperature, flow velocity, pH and solution composition in the reaction system. In most cases, dissolutions of both albite and zeolite are incongruent. Dissolution of dolomite is also incongruent in most cases and varied with T, pH, and nature of aqueous solutions. For dolomite dissolution, the release rates of Mg are less than those of Ca at high temperatures as T increases from 25 to 300°C. SIMS study indicates that the contents of Al, Na and Si in the leached layer of zeolite or albite surface, change with the distance from the surface, exhibiting a non-linear behaviour within a thickness range of 1000%. The distributions of Ca, Mg, Mn, H and Cl in the leached surface layer of carbonate have a non-linear behaviour too.

关键词： mineral surface kinetics liquid/solid interface reaction

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Versatile Recyclable Kevlar Nanofibrous Aerogels Enabled by Destabilizing Dynamic Balance Strategy

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Advanced Fiber Materials 2023年第3期5卷 1050-1062页

作者： Lishan Li Jing Lyu Qingqing Cheng Chen Fu xuetong zhang Suzhou Institute of Nano-Tech and Nano-Bionics Chinese Academy of SciencesSuzhou 215123People’s Republic of China Division of Surgery and Interventional Science University College LondonLondon NW32PFUK

Aerogels are of great interest in diverse fields including thermal insulation,environmental protection,liquid separation,electromagnetic shielding,***,the development of renewable and recyclable aerogels,especially synthetic pol-ymer-based ones,remains an enormous challenge,which seriously hinders the practical application of ***,utilizing Kevlar nanofibers(KNFs)as representative synthetic polymer building blocks,a destabilizing dynamic balance(DDB)strategy is proposed to fabricate recyclable aerogels with high reprocessing *** specifically,aprotic esters(e.g.,di-tert-butyl decarbonate,DiBoc)and alkalis(e.g.,potassium tert-butoxide,t-BuOK)are introduced to trigger the destabilizing dynamic balance between deprotonation–protonation of KNFs,resulting in a reversible sol–gel ***,the duration of sol–gel transition(i.e.,gelation)time,adjustable from 10^(–2)to 10^(3)min,is compatible with versatile processing methods,such as static mould casting,dynamic wet spinning,dynamic blade coating and dynamic 3D *** unique advantages enable the fabrication of various KNF aerogel products(i.e.,continuous fibers,continuous films,large-sized monoliths and 3D-printed articles)with low density(33–165 mg/cm3),high compressive modulus(up to 52 MPa),high specific surface area(360–404 m^(2)/g)and low thermal conductivity(0.027–0.050 W/m·K).Notably,these properties are comparable or superior to that of previously reported KNF aerogels and far superior to that of recyclable *** with direct fabrication from raw materials,the DDB strategy reduces the cost by 50.5%and 82.5%when products are made from recycled aerogels and wet gels,*** cost reduction further increases with the number of recycling cycles,which is calculated as$275 per kilogram KNF aerogel with 5 *** work develops extraordinary KNF aerogels those can be recycled and reused,as well as provides a strategy that can be applied to design mor

关键词： Aerogel Kevlar Recyclability Versatile processing Dynamic balance

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Development of Zr/ZrO_2 high temperature and high pressure sensors for in-situ measuring chemical parameters of deep-sea water

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Science China(Technological Sciences) 2009年第8期52卷 2466-2473页

作者： zhang xuetong, zhang RongHua, HU ShuMin & WANG Yong Open Research Laboratory of Geochemical Kinetics, Institute of Mineral Resources, Chinese Academy of Geological Sciences, Beijing 100037, China Open Research Laboratory of Geochemical Kinetics Institute of Mineral Resources Chinese Academy of Geological Sciences Beijing China

In order to in situ measure chemical parameters of deep-sea water and hydrothermal fluids at midocean ridge(MOR), it is necessary to use high temperature and high pressure chemical *** new sensors is essential to measure in-situ pH and other chemical parameters(dissolved H2, dissolved H2S) of deep-sea water and hydrothermal fluids in a wide temperature range(2℃―400℃) at MOR *** YSZ(Yttria Stabilized Zirconia, 9%Y2O3) ceramic-based(HgO/Hg) chemical sensors possess excellent electrochemical properties at high temperatures, which have been used to measure chemical parameters of hydrothermal fluids above 200℃.A novel Zr/ZrO2 oxidation/reduction electrode was constructed by oxidation of Zr wire in Na2CO3 *** Zr/ZrO2 electrode has good chemical stability while measuring pH of high-temperature aqueous solutions, combined with a Ag/AgCl reference *** of the Zr/ZrO2 sensor in association with a Ag/AgCl reference electrode vary linearly with pH over a wide pH range, as tested by various NaCl-HCl-H2O solutions(NaOH-NaCl-H2O for basic solutions), at temperatures in the range of 20℃―200℃.Thus, the Zr/ZrO2 sensors can be utilized in monitoring the fluids over the temperature range of 2℃―200℃.The Zr/ZrO2 electrode combined with Ag/AgCl, Ag/Ag2S, and Au electrodes has been used to measure pH and other chemical parameters(dissolved H2, dissolved H2S) of aqueous fluids from low to high temperatures and high pressures in the laboratory and to monitor those parameters of deep-sea water in South China Sea.

关键词： Zr/ZrO2 sensor melt oxidation method high temperature and high pressure chemical parameters investigation in the deep ocean

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Kinetics of ore-forming fluids in epithermal systems

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Chinese Science Bulletin 1999年第S2期44卷 5-6页

作者： zhang Ronghua, zhang xuetong and HU Shumin Open Research Laboratory of Geochemical Kinetics, Institute of Mineral Deposits, Chinese Academy of Geological Sciences, Beijing 100037, China Open Research Laboratory of Geochemical Kinetics Institute of Mineral Deposits Chinese Academy of Geological Sciences Beijing 100037 China

As verified by the data of fluid inclusions in minerals in some paleo-hydrothermal systems, a lowering intemperature of the ore-forming fluids and a decrease in salinity occurred simultaneously from the centralzone （deep part） of the deposit profile to its outer zone （shallow part）. The usual situation shown byexperimental data is that solubility rises with an increase in temperature, as shown by quartz and manyore minerals. However, the solubility of some minerals increases as the temperature decreases within acertain temperature range. Therefore, continuous deposition cannot be achieved as the temperature of thesystem decreases, as in the cases of calcite, fluorite, and anhydrite. In water and NaCl-H2O systems,the solubility of calcite （or anhydrite） decreases with a rise in temperature at < 300℃ (or < 450℃

关键词： kinetics ore-forming fluids epithermal systems.

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长江中下游典型火山盆地的水岩相互作用和金属矿床蚀变分带

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岩石学报 2017年第10期33卷 3302-3318页

作者：张荣华胡书敏张雪彤中国地质科学院矿产资源研究所地球化学动力学实验室国土资源部成矿作用和资源评价重点实验室北京100037

长江中下游火山岩盆地中金属矿床和蚀变分带的的地球化学研究表明,它们具有内带深色蚀变带和外带浅色蚀变带,形成于600℃到100℃范围。两类蚀变带分界温度大致是300℃。大金属矿床蚀变分带剖面显示出热液系统存在有明显的温度梯度。通... 详细信息

长江中下游火山岩盆地中金属矿床和蚀变分带的的地球化学研究表明,它们具有内带深色蚀变带和外带浅色蚀变带,形成于600℃到100℃范围。两类蚀变带分界温度大致是300℃。大金属矿床蚀变分带剖面显示出热液系统存在有明显的温度梯度。通过与背景岩石(玄武岩石)对比研究表明,自下而上的不同蚀变岩石中主要元素含量显著变化,交代作用中的代出和代入元素在空间上是演化的。25~400℃和23MPa下矿物(钠长石、阳起石、透辉石、钙铁辉石)-H2O、岩石(玄武岩)-H2O反应的化学动力学实验表明,金属元素释放速率是温度的函数。在恒压升温过程中,从20℃到400℃,硅酸盐矿物、玄武岩中Si溶解速率不断上升;在300~350℃时,Si、Al溶解速率到最大数值。随后,温度再上升导致溶解速率下降。在300℃时,Si溶解快于其他金属元素,溶液中金属元素与硅摩尔浓度比(Ca/Si、Mg/Si、Fe/Si、Na/Si)等都低于矿物中的计量比。矿物反应后的表面缺少硅的淋失层,或者有贫硅矿物和铁氧化物出现。作者还进行23~35MPa、20~550℃玄武岩与水反应实验。上述高温高压下矿物在水溶液中的溶解反应动力学实验和流体-玄武岩相互作用实验,对于理解金属矿床及蚀变分带形成机制提供新的依据。

关键词：蚀变分带溶解反应速率化学动力学流体-玄武岩相互作用

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庐枞火山岩盆地正长岩与水反应动力学实验研究

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岩石学报 2017年第10期33卷 3319-3331页

作者：张雪彤张荣华胡书敏中国地质科学院矿产资源研究所地球化学动力学实验室国土资源部成矿作用和资源评价重点实验室北京100037

为了模拟庐枞火山盆地基底的水热反应和正长辉长岩-二长岩-正长岩与水相互作用,深入剖析深部流体携带金属来源的可能性,本文利用开放流动体系的叠层流动反应器实验研究25~435℃、23~35MPa条件下二长岩-正长岩与水相互作用的化学动力学... 详细信息

为了模拟庐枞火山盆地基底的水热反应和正长辉长岩-二长岩-正长岩与水相互作用,深入剖析深部流体携带金属来源的可能性,本文利用开放流动体系的叠层流动反应器实验研究25~435℃、23~35MPa条件下二长岩-正长岩与水相互作用的化学动力学过程。研究表明,造岩元素、成矿元素和痕迹元素,在低温至水临界态的升温过程中溶解产物在水中的浓度(或溶解速率)不断变化,它们的最大溶解速率出现在不同温度。主要元素Si、Al等最大溶解速率出现在300~400℃范围,即,在跨越水的临界温度时出现溶解速率的涨落。或者说,正长岩-H2O体系中元素的溶解速率主要是温度的函数,此外,压力也对大部分元素的溶解速率产生影响,但是,对于各元素溶解速率随温度而变化的基本规律影响不大。实验重要的发现:相当于中地壳的温度即300~400℃时反应很特殊。硅酸盐矿物的硅被强烈溶失和矿物岩石会垮塌。实验表明:相当于中地壳温度(300~400℃)发生的二长正长岩与水相互作用对庐枞火山盆地深部矿床形成产生重要影响。长期的含金属流体活动造成了金属矿石的形成。水/岩反应动力学过程的温度因素:不同金属元素的最容易溶解和沉淀温度的区别导致了金属-蚀变分带性。实验还揭示,纯水与二长正长岩的反应可以淋滤出大量有色金属元素,在溶液的浓度可以到几百×10^(-9),如Ni、Mn、Cu、Zn,它们从二长正长岩里被溶解释放速率也很高。以往,研究表明火山盆地铁矿的物质来源于围岩。这次实验研究显示:水与二长正长岩的反应同样影响着盆地金属矿的形成和盆地深部、上中地壳的流体性质。实验对于理解上中地壳发生的水岩相互作用也有普适性意义。

关键词：正长岩动力学研究水/岩相互作用高温高压实验

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