Pressure oxidation leaching behavior of chalcopyrite in sulfuric acid solution from 110 °C to 150 °C were investigated by in-situ electrochemical methods. Leaching experiments under saturated vapor pressure conditions were used to simulate the anoxic environment that may be encountered in industrial applications. Scanning electron microscope and X-ray photoelectron spectroscopy were used to characterize the morphology and the chemical status of chalcopyrite surface. Results show that the copper extraction was increased with the increase of leaching temperature. Under the optimal leaching conditions under saturated vapor pressure, the copper and iron extraction are 8.3% and 29.8%, respectively. When the temperature increased from 110 °C to 150 °C, the self-corrosion potential and electrochemical reaction resistance firstly increased and then decreased. In contrast, the resistance of the passive film was always increased with the increase of temperature. The electrochemical study results indicated that the increase in temperature affected the oxidation of chalcopyrite by altering the kinetics of the cathodic reaction and the anodic passivation. Both the self-corrosion current density (icorr) and rate constant were affected by the reduction of Fe(III). The XPS results show that elemental sulfur and H3O(Fe3(SO4)2(OH)6) were the main leaching solid products. The formation of H3O(Fe3(SO4)2(OH)6) not only caused a decrease in cathodic reaction kinetics, but also increased the resistance of mass transfer process. Due to the faster release of iron, copper-rich sulphides were formed, which mixed with the elemental sulfur and/or H3O(Fe3(SO4)2(OH)6) led to coverage of the chalcopyrite surface. 相似文献
In this paper, the cavitation performance and corresponding pressure pulsation, noise and vibration induced by the choked cavitating flow in a Venturi reactor are investigated experimentally under different cavitation conditions by using high-speed camera and high frequency sensors. Based on the instantaneous continuous cavitation images, the Proper Orthogonal Decomposition (POD), a tool to analyze the large-scale cavitation flow structure, is applied to investigate the choked cavitating flow dynamics. The POD results show that two mechanisms, re-entrant jet flow mechanism and shock wave mechanism, govern the shedding and collapse of cavitation cloud at different pressure ratios. These mechanisms contribute to the variation of pressure pulsation, noise and vibration at different pressure ratios. The pressure pulsation spectrum behaves differently in various cavitation regions induced by the choked cavitating flow. Due to the existence of low pressure in re-entrant region, the influence of high frequency fluctuation on pressure pulsation caused by re-entrant flow is small. Moreover, with the increase of pressure ratio, the induced noise and vibration intensity decreases gradually, then increases and reaches a maximum value. Finally, it drops to a low and stable level. Despite different inlet pressures, the intensity of cavitation noise and vibration reaches the maximum value at the same pressure ratio. Specifically, the FFT analysis of noise and vibration signals indicates that low frequency component prevails at small pressure ratio owing to the re-entrant jet mechanism, while high frequency component prevails at large pressure ratio owing to the shock wave mechanism. The relationship between the choked cavitation dynamics and the induced pressure pulsation, noise and vibration in the Venturi reactor is highlighted. The results can provide guidance for the optimal operation condition of the Venturi reactor for cavitation applications such as water treatment. 相似文献
Adsorptive separation is an energy-efficient alternative, but its advancement has been hindered by the challenge of industrially potential adsorbents development. Herein, a novel ultra-microporous metal-organic framework ZU-901 is designed that satisfies the basic criteria raised by ethylene/ethane (C2H4/C2H6) pressure swing adsorption (PSA). ZU-901 exhibits an “S” shaped C2H4 curve with high sorbent selection parameter (65) and could be mildly regenerated. Through green aqueous-phase synthesis, ZU-901 is easily scalable with 99 % yield, and it is stable in water, acid, basic solutions and cycling breakthrough experiments. Polymer-grade C2H4 (99.51 %) could be obtained via a simulating two-bed PSA process, and the corresponding energy consumption is only 1/10 of that of simulating cryogenic distillation. Our work has demonstrated the great potential of pore engineering in designing porous materials with desired adsorption and desorption behavior to implement an efficient PSA process. 相似文献
Low-dimensional (low-D) organic metal halide hybrids (OMHHs) have emerged as fascinating candidates for optoelectronics due to their integrated properties from both organic and inorganic components. However, for most of low-D OMHHs, especially the zero-D (0D) compounds, the inferior electronic coupling between organic ligands and inorganic metal halides prevents efficient charge transfer at the hybrid interfaces and thus limits their further tunability of optical and electronic properties. Here, using pressure to regulate the interfacial interactions, efficient charge transfer from organic ligands to metal halides is achieved, which leads to a near-unity photoluminescence quantum yield (PLQY) at around 6.0 GPa in a 0D OMHH, [(C6H5)4P]2SbCl5. In situ experimental characterizations and theoretical simulations reveal that the pressure-induced electronic coupling between the lone-pair electrons of Sb3+ and the π electrons of benzene ring (lp-π interaction) serves as an unexpected “bridge” for the charge transfer. Our work opens a versatile strategy for the new materials design by manipulating the lp-π interactions in organic–inorganic hybrid systems. 相似文献
High-mobility and strong luminescent materials are essential as an important component of organic photodiodes, having received extensive attention in the field of organic optoelectronics. Beyond the conventional chemical synthesis of new molecules, pressure technology, as a flexible and efficient method, can tune the electronic and optical properties reversibly. However, the mechanism in organic materials has not been systematically revealed. Here, we theoretically predicted the pressure-depended luminescence and charge transport properties of high-performance organic optoelectronic semiconductors, 2,6-diphenylanthracene (DPA), by first-principle and multi-scale theoretical calculation methods. The dispersion-corrected density functional theory (DFT-D) and hybrid quantum mechanics/molecular mechanics (QM/MM) method were used to get the electronic structures and vibration properties under pressure. Furthermore, the charge transport and luminescence properties were calculated with the quantum tunneling method and thermal vibration correlation function. We found that the pressure could significantly improve the charge transport performance of the DPA single crystal. When the applied pressure increased to 1.86 GPa, the hole mobility could be doubled. At the same time, due to the weak exciton coupling effect and the rigid flat structure, there is neither fluorescence quenching nor obvious emission enhancement phenomenon. The DPA single crystal possesses a slightly higher fluorescence quantum yield ~ 0.47 under pressure. Our work systematically explored the pressure-dependence photoelectric properties and explained the inside mechanism. Also, we proposed that the external pressure would be an effective way to improve the photoelectric performance of organic semiconductors. 相似文献
India has abundance of biomass such as rice husk, bagasse, wheat straw, sawdust etc. which is used as a main or auxiliary fuel in the fluidized bed combustor, gasifier and pyrolizer. Design of such fluidized bed equipments require the knowledge of minimum fluidization velocity (Umf), complete fluidization velocity (Ucf) and transport disengagement height (TDH). The present work reports the fluidization characteristic, Umf, Ucf and TDH of the individual size groups of sawdust and mixture thereof. The results indicate that the Umf and Ucf have a tendency to increase with increase in particle diameter, however the TDH shows the reverse trend. The sawdust particle size of 925 and 1200 μm showed significant difference between their Umf and Ucf, an essential parameter for controlled fluidization. Based on the experimental work new correlations for the prediction of Umf, Ucf and TDH for sawdust sample are proposed. The proposed correlations of Umf, Ucf and TDH are in good agreement with experimental values and the deviations found within the range of nearly ±10% for all the samples. 相似文献
Oil–water two-phase flow experiments were conducted in a 15 m long, 8.28 cm diameter, inclinable steel pipe using mineral oil (density of 830 kg/m3 and viscosity of 7.5 mPa s) and brine (density of 1060 kg/m3 and viscosity of 0.8 mPa s). Steady-state data on flow patterns, two-phase pressure gradient and holdup were obtained over the entire range of flow rates for pipe inclinations of −5°, −2°, −1.5°, 0°, 1°, 2° and 5°. The characterization of flow patterns and identification of their boundaries was achieved via observation of recorded movies and by analysis of the relative deviation from the homogeneous behavior. A stratified wavy flow pattern with no mixing at the interface was identified in downward and upward flow. Two gamma-ray densitometers allowed for accurate measurement of the absolute in situ volumetric fraction (holdup) of each phase for all flow patterns. Extensive results of holdup and two-phase pressure gradient as a function of the superficial velocities, flow pattern and inclinations are reported. The new experimental data are compared with results of a flow pattern dependent prediction model, which uses the area-averaged steady-state two-fluid model for stratified flow and the homogeneous model for dispersed flow. Prediction accuracies for oil/water holdups and pressure gradients are presented as function of pipe inclination for all flow patterns observed. There is scope for improvement for in particular dual-continuous flow patterns. 相似文献
Microstructure heat exchangers have unique properties that make them useful for numerous scientific and industrial applications. The power transferred per unit volume is mainly a function of the distance between heat source and heat sink—the smaller this distance, the better the heat transfer. Another parameter governing for the heat transfer is the lateral characteristic dimension of the heat transfer structure; in the case of microchannels, this is the hydraulic diameter. Decreasing this characteristic dimension into the range of several 10s of micrometers leads to very high values for the heat transfer rate.
Another possible way of increasing the heat transfer rate of a heat exchanger is changing the flow regime. Microchannel devices usually operate within the laminar flow regime. By changing from microchannels to three dimensional structures, or to planar geometries with microcolumn arrays, a significant increase of the heat transfer rate can be achieved.
Microheat exchangers in the form of both microchannel devices (with different hydraulic diameters) and microcolumn array devices (with different microcolumn layouts) are presented and compared. Electrically heated microchannel devices are presented, and industrial applications are briefly described. 相似文献
Atmospheric pressure waves are a notable phenomenon associated with explosive volcanic eruptions. They can provide us with information about eruption processes that are useful both scientifically and practically. In this paper, we give a brief review of studies that have been carried out on this phenomenon in the field of volcanology. Then, we introduce a prototype tool called ‘MOVE’ (Mobile Observatory for Volcanic Explosions). It is a remote-controlled vehicle carrying various instruments to observe pressure waves and the eruption processes.
PACS 91.40.Dr · 91.40.Ft · 93.65.+e · 93.85.+qThis paper was based on work presented at the 2nd International Symposium on Interdisciplinary Shock Wave Research, Sendai, Japan on March 1–3, 2005. 相似文献