Fluid Mixing Process Research Articles

Numerical analysis of effect of Reynolds number on interaction of density-stratified fluid with a vortex ring

In this study, the effect of Reynolds number (Re) on the mixing process of a two-layer density-stratified fluid, caused by the interaction between a vortex ring and the density interface, was numerically investigated using an improved vortex-in-cell method. The density-stratified fluid consisted of water (upper layer) and an aqueous sodium chloride solution (lower layer). Re of the simulated vortex ring was varied from 644 to 1932. We numerically investigated the behavior of the vortex ring and density-stratified fluid, and compared the same with that from a previously conducted experimental study from the literature. The vortex structure generated during the interaction was visualized in three dimensions. Furthermore, the mixing process was evaluated in terms of the stirring index, gradient of concentration, and stirring efficiency. The mixing behavior of the vortex ring was a function of the interaction pattern. For example, for a large Re, with the penetrative pattern, the stirring efficiency reached a constant value that was smaller than that from the partially penetrative pattern. The results showed that a strong stirring caused by an increase in Re of the vortex ring would not always lead to effective mixing.

An experimental investigation on the fluid flow mixing process in agitated vessel

The fluid mixing process is a common supportive phenomenon that often occurs in a large number of industrial systems. This phenomenon is the subject of many numerical and experimental analysis. The mixing process effectiveness depends on: mixing tank construction, mixing phases viscosity, temperature, density of liquids and, what is crucial, the impeller shape. The optimal design of impeller geometry is still an open issue. In this research work, the main objective is experimental investigations of the influence of the newly constructed impeller type on the fluid flow motion phenomena and energy consumption. Flow field values were evaluated using PIV measurement and the power consumption using precise torquemeter. The comparison between the Rushton turbine and a novel impeller is presented and discussed. The basis for the assessment of the intensity degree and efficiency of mixing was the analysis of velocity vectors distribution and power number. Results show that the power number for both impellers are similar but the fluid motion is quite different. The pumping capacity Qz for the novel impeller in reference to the Rushton turbine is for many cases at least one order of magnitude higher. This shows that the proposed impeller can be a very promising alternative to the classic blades and non-blades based impeller types.

Numerical study of effect of magnetic field on laser-driven Rayleigh-Taylor instability

Rayleigh-Taylor instability (RTI) is a fundamental physical phenomenon in fluids and plasmas, and plays a significant role in astrophysics, space physics, and engineering. Especially in inertial confinement fusion (ICF) research, numerous experimental and simulation results have identified RTI as one of the most significant barriers to achieving fusion. Understanding the origin and development of RTI will be conducive to formulating mitigation measures to curb the growth of instability, thereby improving the odds of ICF success. Although there have existed many theoretical and experimental studies of RTI under high energy density, there are few experiments to systematically explore the influence of magnetic fields on the evolution of magnetized RTI. Here, a new experimental scheme is proposed based on the Shenguang-II laser facility on which the nanosecond laser beams are used to drive modulation targets of polystyrene (CH) and low-density foam layers. A shock wave is generated after the laser’s CH modulation layer has been ablated, and propagates through CH to low-density foam. Moreover, Richtmyer-Meshkov instability is triggered off when the shock wave accelerates the target. When the laser pulse ends, the shock wave evolves into a blast wave, causing the system to decelerate, resulting in RTI in the reference system of the interface. In this paper the open-source radiation MHD simulation code (FLASH) is used to simulate the RTI generated by a laser-driven modulation target. The evolution of RTI under no magnetic field, under Biermann self-generated magnetic field, and under different applied magnetic fields are systematically investigated and compared with each other. The simulation results show that the Biermann self-generated magnetic field and the applied magnetic field parallel to flow direction do not change the interface dynamics in the evolution process of RTI. Nevertheless, the applied magnetic field perpendicular to flow direction can stabilize RTI and the Kelvin-Helmholtz vortex at the tail of the RTI spike. Magnetic pressure plays a decisive role. The present results provide a reference for the follow-up study of target physics related to ICF and deepen the understanding of the fluid mixing process.

Native gold enrichment process during growth of chalcopyrite-lined conduits within a modern hydrothermal chimney (Manus Basin, PNG)

Abstract Seafloor hydrothermal chimneys from back-arc basins are important hosts for metals such as Cu, Zn, Pb, Ag, and Au. Although the general growth history of chimneys has been well documented, recent studies have revealed that the fine-scale mineralogy can be highly complex and reflects variable physicochemical conditions of formation. This study utilized a novel combination of scanning electron microscopy (SEM)-based electron backscattered diffraction (EBSD) and synchrotron X-ray fluorescence microscopy (SXFM) to uncover the detailed growth processes of multiple chalcopyrite-lined conduits within a modern chalcopyrite-sphalerite chimney from Manus Basin and to assess the controls on native gold precipitation. On the basis of previous studies, the chimney conduit was thought to develop from an initial sulfate-dominated wall, which was subsequently dissolved and replaced by sphalerite and chalcopyrite during gradual mixing of hydrothermal fluids and seawater. During this process, sphalerite was epitaxially overgrown by chalcopyrite. Accretionary growth of chalcopyrite onto this early formed substrate thickened the chimney walls by bi-directional growth inward and outward from the original tube wall, also enclosing the outgrown pyrite cluster. A group of similar conduits with slightly different mineral assemblages continued to form in the vicinity of the main conduit during the further fluid mixing process. Four types of distinct native gold-sulfide/sulfosalt associations were developed during the varying mixing of hydrothermal fluids and seawater. Previously unobserved chains of gold nanoparticles occur at the boundary of early sphalerite and chalcopyrite, distinct from gold observed in massive sphalerite as identified in other studies. These observations provide baseline data in a well-preserved modern system for studies of enrichment mechanisms of native gold in hydrothermal chimneys. Furthermore, native gold is relatively rarely observed in chalcopyrite-lined conduit walls. Our observations imply that: (1) native gold is closely associated with various sulfides/sulfosalts in chalcopyrite-lined conduit walls rather than limited to the association with tennantite, Bi-rich minerals, and bornite as reported previously; and (2) the broad spectrum of gold occurrence in chalcopyrite-line conduits is likely to be determined by the various mixing process between hot hydrothermal fluids with surrounding fluids or seawater. Quantitative modeling of fluid mixing processes is recommended in the future to probe the precise gold deposition stages to efficiently locate gold in modern hydrothermal chimneys.

Evidence of a new geothermal prospect in the Northern-Central trans-Mexican volcanic belt: Rancho Nuevo, Guanajuato, Mexico

Thermal manifestations are commonly found in central Mexico as result of the volcanic activity originating from the formation of the Trans-Mexican Volcanic Belt during the Quaternary. The Rancho Nuevo hot spring is one of them that has not been described before with a discharge temperature near 92 °C. The goal of the present study is to provide geothermal characteristics of thermal manifestations at Rancho Nuevo location based on geochemical and mineralogical results to explain deep-subsurface processes that occurred in the geothermal system. The presence of kaolinite, montmorillonite, opal, zeolite, barite, pyrite, and stibnite in altered soil sediments or around the hot springs identified by the techniques used in the present study, confirms the presence of hydrothermal activity. In addition, based on the X-ray diffraction, calcite precipitates at the surface of the thermal springs. This mineral association reflects deep geothermal processes and is eventually deposited in shallow zones. Fluid mixing processes and variations in redox conditions are suggested by mineral association and isotopic sulfur data. Finally, based on the physicochemical data provided by the water samples and the discharge conditions of the springs, stability diagrams were constructed for pyrite, barite, and zeolites using the Geochemist’s Work Bench program to corroborate these data with the mineralogical results. The mineralogical results and distribution, as well as the N-S trend of mineral associations suggest interaction processes between geothermal fluid and rocks of the stratigraphic sequence, and active major faults, enabling the upward flow of deep geothermal fluids. The approach to the conceptual model of the Rancho Nuevo geothermal prospect reveals an attractive potential for the exploration of a viable geothermal resource in central Mexico.

Fluid Mixing Process Based on Programmable Logic Controller as Training Kit for Electrical Engineering Education Students

The Department of Electrical Engineering, Universitas Negeri Surabaya (Unesa) is developing a laboratory, including a control system laboratory. The control system engineering teaching team prepares themselves by making a PLC training kit to accompany the existing modules. With the aim that students know and understand the application of control systems in industry. This can foster student learning motivation in attending lectures and greatly support student competence before entering the workplace. The study used is development research by producing a product prototype in the form of a fluid mixing process training kit. The steps taken are designing, making tools, integrating software to hardware and validating the tools. The result of the research is that the fluid mixing process training kit has worked according to the instructions given and is suitable for use as a learning medium.

Multiple sulfur isotopes in post-Archean deposits as a potential tracer for fluid mixing processes: An example from an iron oxide–copper–gold (IOCG) deposit in southern Peru

Sulfur has multiple stable isotopes (32S, 33S, 34S, and 36S), but little research has been conducted to investigate the information that low abundance sulfur isotope ratios (i.e., 33S/32S and 36S/32S) may carry on ore-forming processes in post-Archean deposits. In this study, the Cretaceous Mina Justa iron oxide–copper–gold deposit, was selected to examine the capability of multiple sulfur isotopes to trace ore-forming processes in post-Archean mineral deposits. In situ secondary ion mass spectrometry was applied to the pyrite of the magnetite–pyrite stage in the deposit to characterize the spatial variation of multiple sulfur isotopes at the microscale. This revealed a clear co-variation trend between δ34S (= 1000 × [(34S/32S)sample/(34S/32S)V-CDT − 1]) and Δ33S (= δ33S − 1000 × [(1 + δ34S/1000)0.515 – 1]). Simple modeling suggests that the triple sulfur isotope data recorded is best explained by mixing magmatic and externally derived (e.g., basinal brine) fluids. The contribution of external fluids is also supported by the trace element distribution patterns in pyrite, as revealed by laser ablation-inductively coupled plasma-mass spectrometry. This study is the first attempt to use multiple sulfur isotopes to trace ore-forming processes in post-Archean deposits and demonstrates that multiple sulfur isotopes are a faithful recorder of ore-forming processes at the microscale, especially when multiple fluids mix.

Analysis of Lateral Fluid Gradients From DFA Measurements and Simulation of Reservoir Fluid Mixing Processes Over Geologic Time

Downhole fluid analysis (DFA) is one pillar of reservoir fluid geodynamics (RFG). DFA measurements provide both vertical and lateral fluid gradient data. These gradients, especially the asphaltene gradient derived from accurate optical density (OD) measurements, are critical in thermodynamic analysis to assess equilibration level and identify RFG processes. Recently, an RFG study was conducted using DFA and laboratory data from an oil field in the Norwegian North Sea. Fluid OD gradients show equilibrated asphaltenes in most of the reservoir, with a lateral variation of 20%. This indicates connectivity, which is confirmed by three years of production data. Two outliers are off the asphaltene equilibrium curve implying isolated sections, one each on the extreme east and west flank. Their asphaltene fraction varies by a factor of six. Such a difference reveals that different charge fluids entered the reservoir, and the equilibrated asphaltenes are the result of an after-charge mixing process. Meanwhile, different gas-oil contacts (GOCs) exist in the reservoir, indicating a lateral solution-gas gradient. Geochemistry analysis shows the same level of mild biodegradation in all the fluid samples, including those from two isolated sections. This means that biodegraded oil spills into the whole reservoir with little or no in-reservoir biodegradation. Furthermore, lateral asphaltene gradients at different times after charge have been preserved; it was a factor of six in asphaltenes content initially and is now 20% in the present day. This unique data set provides a valuable constraint to simulate reservoir fluid after-charge mixing processes to present day, aiming to investigate the factors impacting the evolution of lateral composition gradients in geologic time in a connected reservoir. Numerical simulations were performed over geologic time in reservoirs filled by oil with a lateral density gradient, which imitates the lateral compositional gradients in the gas-oil ratio (GOR) and asphaltenes measured in the above oil field. Simulations show that this lateral gradient creates lateral differential pressures and causes a countercurrent fluid flow forming a convection cell. In reservoirs with realistic vertical-to-horizontal aspect ratios, such fluid flows are not rapid, and lateral gradients can be partially retained in moderate geologic times. Additionally, diffusion was included in the simulation. The reservoir model was initialized with two GOCs producing subtle lateral GOR and density gradients. The simulated mixing process transports gas from higher GOR regions to lower GOR regions and reduces the GOC difference. However, the flux of solution gas transport is small. Consequently, we conclude that lateral GOR and asphaltene gradients can persist for moderate geologic time, which is consistent with observation from the field.

Epithermal Mineralization in the Busang Southeast Zone, Indonesia: New Insight into the Au Prospect at the Center of the Bre-X Fraud

The Busang mineral prospect in Kalimantan, Indonesia, was reported to host a large Au resource until 1997 when it was revealed that drill core samples had been deliberately and systematically contaminated (“salted”) with extraneous Au to falsify resource estimates. One month before the fraud was uncovered, Dr. G. Milligan, then professor emeritus of geology, visited the site to collect a suite of core samples for academic study that was deemed representative of the host rocks, alteration, and mineralization of the Busang Southeast Zone. These samples were re-examined here by optical microscopy, electron microprobe (EMPA), whole-rock geochemistry, and fluid inclusion microthermometry to characterize the subsurface geology and hydrothermal mineralization, and to assess reasons why the system is of uneconomic character. The host rocks were variably altered calc-alkaline porphyritic subvolcanic diorites, typical of the lithological units along the mineralized trend in the Kalimantan Gold Belt. Early hydrothermal mineralization with quartz-sulfide (pyrite, chalcopyrite, Cu-sulfosalts) stockwork veinlets associated with pervasive phyllic and propylitic alteration was overprinted by crudely banded quartz-carbonate-sulfide/sulfosalt (pyrite, sphalerite, chalcopyrite, galena, tennantite-tetrahedrite, bournonite-seligmannite) veins. The stockwork veins were associated with up to 140 ppb bulk rock Au, some of which was hosted by Cu-sulfosalts. Microthermometry on quartz-hosted aqueous fluid inclusion assemblages (FIA; n = 13) and single inclusions (non-FIA; n = 20) in quartz-carbonate-sulfide/sulfosalt veins yielded an overall range in homogenization temperatures (Th) between 179 °C and 366 °C and bulk salinities between 1.1 wt.% to 8.6 wt.% NaCl equivalent, with much smaller data ranges for individual FIA (e.g., FIA 3; 239.1 °C to 240.5 °C and 0.5 wt.% to 1.4 wt.% NaCl equivalent). Primary FIA along growth zones in quartz were identified, providing constraints on fluid characteristics at the time of quartz growth. Carbonate-hosted FIA (n = 3) and single inclusions (non-FIA; n = 3) in the same veins yielded Th between 254 °C and 343 °C and bulk salinities of 1.1 wt.% to 11.6 wt.% NaCl equivalent. Likewise, data ranges for individual FIA were much smaller. Many of the geological characteristics of the Busang Southeast Zone were compatible with a telescoped, intermediate-sulfidation epithermal system, having formed from diluted magmatic fluids that precipitated weak base metal mineralization. However, the system was unproductive with respect to Au and Ag, at least within the studied area. Of note, vein textures and fluid inclusion characteristics indicative of boiling or efficient fluid mixing—processes both considered critical for the formation of economic lode gold deposits—were absent in the samples.

Miniaturized magnetic stir bars for controlled agitation of aqueous microdroplets

Controlled stirring of tiny volumes of aqueous fluids is of particular importance in the life sciences, e.g. in the context of microfluidic and lab-on-chip applications. Local stirring not only accelerates fluid mixing and diffusion-limited processes, but it also allows for adding controlled active noise to the fluid. Here we report on the synthesis and characterization of magnetic nano-stir bars (MNBs) with which these features can be achieved in a straightforward fashion. We also demonstrate the applicability of MNBs to cell extract droplets in microfluidic channels and we show that they can introduce active noise to cell extracts as evidenced by altered fluctuations of ensembles of cytoskeletal filaments.

Study on Flow Characteristics of Microfluid in Electroosmotic Flow Mixer

As one of the important components of modern microfluidic devices, micromixers have attracted more and more attention. Among many microfluidic mixers, electro-osmotic flow mixers have been widely studied and applied due to their advantages such as simple structure, convenient control and remarkable mixing effect. In this paper, a two-dimensional numerical model of an electro-osmotic flow micromixer with an annular mixing chamber is established by means of the simulation software COMSOL Multiphysics. The mixing process of fluid in the electro-osmotic flow micromixer is simulated, and the flow characteristics of fluid in the micromixer are analyzed. The analysis shows that the electroosmotic flow micromixer generates electroosmotic flow under the action of alternating electric field, and disturbs the fluid to form vortex, thus greatly improving the mixing efficiency. The results show that the micromixing efficiency increases with the increase of zeta potential and applied alternating electric field potential, and in a certain range, the micromixing efficiency increases first and then decreases with the increase of alternating electric field frequency.

Geology and fluid geochemistry of the Na-metasomatism U deposits in the Longshoushan uranium metallogenic belt, NW China: Constraints on the ore-forming process

The Longshoushan belt in Gansu Province is a very important uranium metallogenic belt in Northwest China and contains a series of different types (magmatic, Na-metasomatism, supergenetic) of uranium deposits and occurrences. Of all these mineralization types, the Na-metasomatism type is the most predominant with great potential, represented by two Na-metasomatism uranium deposits (Xinshuijing and Jiling). Different from the fluorite-, illite-, quartz-dominated alteration minerals in other hydrothermal uranium mineralization system, the Na-metasomatism type uranium deposits are characterized by the unique albite-dominated (up to 90 vol%) alteration mineral assemblage, which is referred to albitite in many literatures. All the uranium orebodies in both the Xinshuijing and Jiling deposits are hosted within the metasomatic albitites, and controlled by the subsidiary faults of the regional Malugou Fault. The mineralization process in both deposits can be divided into four stages, namely: the Na-metasomatism stage, U mineralization stage, post-mineralization stage and supergene mineralization stage. The Na-metasomatism stage is predominantly composed of albite (with hematite staining), with minor chlorite and anatase, while the U mineralization stage is characterized by the occurrence of uranium minerals (mostly pitchblende), intergrown with some tiny albite, calcite, chlorite, pyrite, apatite, REE-minerals and sometimes hydrothermal zircons. The mineral assemblages of the Na-metasomatism stage and U mineralization stage are too intimately related to each other and might be the products of the evolution from the same ore-forming fluids. The post-mineralization stage is mainly the calcite-quartz veinlets or occur as aggregate clusters, while the supergene mineralization stage includes mineral assemblage of secondary uranium mineralization-clay minerals (e.g. kaolinite)-limonite. Mineralogical studies and comparison of major and trace elements assay results between fresh biotite granite (predominate host rocks), albitite and uranium ores suggest that the ore-forming fluids resulting in the formation of the Na-metasomatism alteration are oxidized and rich in Na, Sc, V, Cr, Co, Ni, U, Th, while the ore-forming fluids of the U mineralization stage are relatively reduced and rich in heavy rare earth elements, U, Th, PO34-. Fluid inclusion and calcite C-O isotope studies indicate that the ore-forming fluids are meteoric water-dominated, which circulated at depth (~8 km, by fluid inclusion geobarometer) and scavenged uranium from the host biotite granites and metamorphic rocks of the Longshoushan Group. The ore precipitation is mainly attributed to physicochemical changes (fO2, temperature, fluid composition) from fluid-rock interaction and further temperature decrease of the ore-forming fluids, while fluid boiling and fluid mixing processes are limited. The proposed ore-forming process is not only important for the understanding of the ore genesis for the Na-metasomatism mineralization systems in Longshoushan, but also highlights the significance of albite alteration, which could be used as an important indicator during further uranium exploration.

An experimental study on metal precipitation driven by fluid mixing: implications for genesis of carbonate-hosted lead–zinc ore deposits

A type of carbonate-hosted lead–zinc (Pb–Zn) ore deposits, known as Mississippi Valley Type (MVT) deposits, constitutes an important category of lead–zinc ore deposits. Previous studies proposed a fluid-mixing model to account for metal precipitation mechanism of the MVT ore deposits, in which fluids with metal-chloride complexes happen to mix with fluids with reduced sulfur, producing metal sulfide deposition. In this hypothesis, however, the detailed chemical kinetic process of mixing reactions, and especially the controlling factors on the metal precipitation are not yet clearly stated. In this paper, a series of mixing experiments under ambient temperature and pressure conditions were conducted to simulate the fluid mixing process, by titrating the metal-chloride solutions, doping with or without dolomite, and using NaHS solution. Experimental results, combined with the thermodynamic calculations, suggest that H2S, rather than HS− or S2−, dominated the reactions of Pb and/or Zn precipitation during the fluid mixing process, in which metal precipitation was influenced by the stability of metal complexes and the pH. Given the constant concentrations of metal and total S in fluids, the pH was a primary factor controlling the Pb and/or Zn metal precipitation. This is because neutralizing or neutralized processes for the ore-forming fluids can cause instabilities of Pb and/or Zn chloride complexes and re-distribution of sulfur species, and thus can facilitate the hydrolysis of Pb and Zn ions and precipitation of sulfides. Therefore, a weakly acidic to neutral fluid environment is most favorable for the precipitation of Pb and Zn sulfides associated with the carbonate-hosted Pb–Zn deposits.

Experimental Investigation of Fluid Mixing Process with Newly Designed Conduit-Type Mixer and Fin-Type Mixer

In the present paper, fluid mixing process in a stirred tank with a newly designed conduit-type mixer has been investigated by the flow visualization and the concentration measurement. The results of the new conduit-type mixer are compared with a conventional fin-type mixer. Although the concentration measurement indicates that the mixing time by the conduit-type mixer is slightly longer than that by the fin-type mixer, the flow visualization shows that the conduit-type mixer generates the wider circulatory flow pattern and stirs the fluid over a vast area of the tank. Consequently, it is indicated that the conduit-type mixer has an advantage to stir the fluid uniformly in space.

LIF study of temporal and spatial fluid mixing in an annular downcomer

In possible accident scenarios of the reactor coolant system, the convection and mixing characteristics of borated water have a great influence on reactivity variations in the reactor, and then impact the reactor safety. The mixing and diffusion characteristics of the boric acid solution in the annular downcomer is studied by laser-induced fluorescence (LIF). An aqueous solution of Rhodamine B (RhB) fluorescence dye, which is used to simulate boron solution, was injected in the coolant inlet to visualize the fluid mixing process in the annular volume. Laser sheet was formed by optical system to emit the fluorescence, a high-speed camera was used to capture the fluorescence information for reconstructing the concentration distribution of dye. In order to guarantee the experimental accuracy, LIF image processing and a calibration technology are applied. The concentration profiles were implemented to illuminate the fluid mixing between dye solution and diluted water in the downcomer. The coefficient of variation (COV) was conducted to quantify the spatial and temporal transport of dye in the annular downcomer. The results indicate that a higher flow improves the transport ability of dye in the transverse direction, and shortens the distance and time to uniform. The mass force can accelerate the dye transport in the vertical direction. The whole-field measurement technique implemented in this study is expected to provide an insight in the research of flow mixing in the complex geometry. The experimental results can provide a better understanding of mixing phenomena in annular downcomer, and it is also useful for the annular downcomer CFD validation.

The connection between hydrothermal fluids, mineralization, tectonics and magmatism in a continental rift setting: Fluorite Sm-Nd and hematite and carbonates U-Pb geochronology from the Rhinegraben in SW Germany

Understanding the physical basics of tectonic events, related fluid flow and ore deposition represents one of the great challenges in modern geosciences. In this contribution, Sm-Nd ages of hydrothermal fluorites and U-Pb ages of carbonates and iron oxides from unconformity-related vein type deposits in the Schwarzwald next to the Upper Rhinegraben rift in SW Germany are used to distinguish different pulses of hydrothermal fluid activity and to understand their relation to large-scale tectonics and magmatism. While the fluorites are of Early Jurassic to Oligocene age, carbonate (calcite, dolomite, siderite) and hematite dated by U-Pb small-scale isochrons records formation from Permian to Quaternary with a clear culmination in the Neogene.These new age-data in combination with microthermometry data of primary fluid inclusions from growth zones in the fluorites and carbonates are used to constrain the timing of fluid signatures. This contribution shows that the ages are correlated with changes in fluid properties and/or tectonic events in the evolving continental crust. Comparison with published thermochronological data, apparent ages of URG-related volcanic rocks and the tectono-sedimentary evolution of the Upper Rhinegraben rift show clear correlations between the intensity of hydrothermal mineralization (and, hence, the intensity of fracture-bound fluid flow) with the U-Pb carbonate ages. This method accordingly provides an excellent tool to date rift-related processes like fluid flow, ore deposition and tectonic activation or reactivation of fractures.Fluid properties changed after the deposition of Middle Triassic Muschelkalk evaporites from low salinity, high temperature (1–6 wt.% NaCleq, 200–270 °C, cooling late-metamorphic basement fluids) to high salinity, moderate temperature (20–26 wt.% (NaCl + CaCl2), 50–170 °C, mixture of a modified bittern brine (“basement brine”) with halite dissolution brine). This change led to large scale ore deposition (fluorite-barite-quartz with Pb-Zn-Cu, Bi-Co-Ni-Ag-U, Fe-Mn ores). During the Paleogene and Neogene, previously separated aquifers from various sedimentary units were connected by juxtaposition of the fluid source rocks during Rhinegraben rifting, which resulted in variable salinity and temperature fluids (1–26 wt. % (NaCl + CaCl2), 50–350 °C) by a multi-component fluid mixing process. Typical mineralization related to this shows barren or Pb-Zn-Cu veins with large amounts of barite.

Numerical simulation of fluid flow and mixing process in a SCR denitration system

Selective Catalytic Reduction (SCR) with ammonia is a key technology to reduce the NOx emissions from the coal-fired power stations. The denitration efficiency of SCR system depends on whether the flue gas and ammonia can get a good mix in the reactor. The fluid flow and the mixing process in a SCR denitration system have been analysed to gain an insight into the characteristic of the mixing process and to check the numerical simulation as a tool for the optimization design of the SCR system. Combined with the component transfer model and porous medium model, the large eddy simulation (LES) was carried out to portray the performance of the SCR system in a 310MW coal-fired station. Both the transient and time-averaged velocity fields and concentration fields in different cases were obtained. It has been found that mixing quality is improved significantly by incorporating a series of gate leafs.

Effect of the 6PBT stirrer eccentricity and off-bottom clearance on mixing of pseudoplastic fluid in a stirred tank

The aim of this work is to investigate the effect of the shaft eccentricity on the flow field and mixing characteristics in a stirred tank with the novel stirrer composed of perturbed six-bent-bladed turbine (6PBT). The difference between coaxial and eccentric agitations is studied using computational fluid dynamics (CFD) simulations combined with standard k−ε turbulent equations, that offer a complete image of the three-dimensional flow field. In order to determine the capability of CFD to forecast the mixing process, particle image velocimetry (PIV), which provide an accurate representation of the time-averaged velocity, was used to measure fluid velocity. The test liquid used was 1.25%(wt) xanthan gum solution, a pseudoplastic fluid with a yield stress. The comparison of the experimental and simulated mean flow fields has demonstrated that calculations based on Reynolds-averaged Navier-Stokes equations are suitable for obtaining accurate results. The effects of the shaft eccentricity and the stirrer off-bottom distance on the flow model, mixing time and mixing efficiency were extensively analyzed. It is observed that the microstructure of the flow field has a significant effect on the tracer mixing process. The eccentric agitation can lead to the flow model change and the non-symmetric flow structure, which would possess an obvious superiority of mixing behavior. Moreover, the mixing rate and mixing efficiency are dependent on the shaft eccentricity and the stirrer off-bottom distance, showing the corresponding increase of the eccentricity with the off-bottom distance. The efficient mixing process of pseudoplastic fluid stirred by 6PBT impeller is obtained with the considerably low mixing energy per unit volume when the stirrer off-bottom distance, C, is T/3 and the eccentricity, e, is 0.2. The research results provide valuable references for the improvement of pseudoplastic fluid agitation technology.

Geology, fluid inclusion and stable isotopes (O, S) of the Hetaoping distal skarn Zn-Pb deposit, northern Baoshan block, SW China

The Hetaoping zinc–lead deposit is located in the northern Baoshan block, Sanjiang region, SW China. The ore deposit comprises massive orebodies in the lower part and lenticular and vein-like orebodies in the upper part, both of which are hosted in the marbleized Upper Cambrian limestone and slate of the Hetaoping Formation. Three mineralization stages of Hetaoping skarn system have been recognized based on petrographic observation, which are pre-ore stage (pyroxene–garnet–actinolite–epidote–magnetite), syn-ore stage (sulfides–quartz–calcite–fluorite), and post-ore stage (calcite–quartz–chlorite). Andradite and hedenbergite are dominant in pre-ore garnet and pyroxene, respectively. Ore minerals consist of mainly pyrite, sphalerite, chalcopyrite, bornite and galena. Three types of fluid inclusions have been identified in Hetaoping, including primary two-phase (A type), primary three-phase (B type) and secondary two-phase (C type) inclusions. Based on fluid inclusion microthermometric study, the fluids forming the Hetaoping skarn minerals and sulfides evolved from high-moderate temperature (255–498°C) and low-moderate salinity (5.0–18.0wt.% NaCl equiv) in pre-ore stage, through moderate-low temperature (152–325°C) and low salinity (0.4–14.2wt.% NaCl equiv) in syn-ore stage, to low temperature (109–205°C) and low salinity (0.9–10.0wt.% NaCl equiv) in post-ore stage. The sulfide δ34S values range from 3.7 to 7.1‰ (mean=5.2‰, n=29), indicative of a dominantly magmatic sulfur origin. Silicate and carbonate oxygen isotopes give calculated δ18OH2O ranges of 3.9–11.1‰ in prograde stage, −0.9 to 4.6‰ in early retrograde stage, and −1.3 to 2.9‰ in late retrograde stage (syn-ore stage), The oxygen isotope data reveal that the prograde fluid in Hetaoping could be primarily magmatic, which has been mixed significantly with meteoric water in the late retrograde stage. Such a fluid mixing process is considered to be a key factor controlling ore precipitation.

The Effect of Velocity Ratio Study on Microchannel Hydrodynamics Focused of Mixing Glycerol Nitration Reaction

The paper describes the effect of velocity ratio for mixing glycerol nitration in microchannel hydrodynamic that focused on the stream width. The method used are experimental and theory modeling of hydrodynamic fluid flow focused on predicting behavior stream width glycerol nitration.The research uses microchannel hydrodynamics focused on consisting of three channels inlet (one core and two sheaths). The core glycerol the beginning of the sheath distributed nitric acid with sulphuric acid as a catalyst. The length channel dimension of inlet and outlet of L1, L2, L3 = 1000 μm, L4 = 4000 μm with the width of D1, D2, D3, D4= 300 μm, and the depth of w =200 μm. using transparent material that is acrylic with thickness (T1 and T2 ) as 5 mm arranged accumulated. Fluid volume glycerol of the core of 2 ml, and volume nitric acid of 1.05 ml (+ aquades 0.75 ml) and sulphuric acid 0.1 ml (+ aquades 0.1 ml). The independent variable namely variation the velocity ratio (v2 / v1 ) 0.5,1,2,3,4,5,6,7,8,9,10, and 11. It is Added a slight coloring yellow to fluid glycerol and red to a fluid mixture of nitric acid and sulphuric acid, to understand the mixing process of fluid at the reaction of glycerol nitration. The mixing of the measurement of stream width performed on the ratio of the length (α = L4 / L1 ) of 1 , 2 and 3.The result shows that diffusion of regional differences takes place in the velocity ratio shown by color changing of data on the picture. The width of focus stream is smaller as increasing the velocity ratio. This is caused by the pressure of a fluid channel sheath against core channel fluid is greater than diffusion reaction, as well as the energy required that is used to form a molecular bond.