Loading...
Welcome to visit The Chinese Journal of Process Engineering, Today is

Table of Content

    28 February 2022, Volume 22 Issue 2
    Previous Issue    Next Issue
    Contents
    Cover and contents
    The Chinese Journal of Process Engineering. 2022, 22(2):  0. 
    Asbtract ( )   PDF (1901KB) ( )  
    Related Articles | Metrics
    Reviews
    Chemical oxidation strengthening cleaner production of hydrometallurgy: progress and prospect
    Sihan SUN Fusheng PAN Yongbing XIE Hongbin CAO Yi ZHANG
    The Chinese Journal of Process Engineering. 2022, 22(2):  145-161.  DOI: 10.12034/j.issn.1009-606X.221073
    Asbtract ( )   PDF (953KB) ( )  
    Related Articles | Metrics
    Hydrometallurgy has been increasingly used in the treatment of low-grade refractory ores owing to its relatively low energy consumption and cleaner process. Metal leaching is the primary step in hydrometallurgy, but there are still some acute problems such as low metal recovery rate and long reaction time. Chemical oxidation can transfer metal sulfides into metal ions or change the valence state of metals, and thus benefit the following separation and enrichment of the target metals. In this process, the metal leaching rate can also be further improved by external field enhancement. This review mainly describes the application and the main reaction mechanisms of five typical less corrosive chemical oxidants (Fe3+, O2, H2O2, O3 and persulfate), as well as the relevant collaborative oxidation methods in the hydrometallurgical processes, and introduces four strengthening methods by pressurization, special reaction medium, microwave and ultrasonic. Fe3+ is widely used in acidic leaching of chalcopyrite, sphalerite and other sulfide ores. The unique ion pair cycle enables Fe3+ to form a synergistic oxidation leaching mechanism with a variety of oxidants. O2 often enhances the oxidation leaching efficiency by pressure strengthening, which can promote the oxidative decomposition of refractory sulfide ores. H2O2 has attracted wide attention due to its strong oxidizing property and clean oxidation products, and has been widely used in electronic wastes treatment. O3 oxidation can help to effectively release wrapped gold into solution from refractory gold concentrate containing sulfur. Persulfate is relatively stable with strong oxidation ability, and can be activated to generate reactive oxygen species. Collaborative oxidation and four strengthening methods can further take the advantages of each oxidant to improve the oxidation effect and reduce the cost. Finally, the prospect and technical challenges of chemical oxidation strengthened hydrometallurgical technology are prospected, which has guiding significance for the development of clean production technology in hydrometallurgy.
    Preparation methods of g-C3N4 and its photocatalytic performance improvement approaches—a review
    Hanxiao DU Juan JI Chenwei QIN Ze ZHANG Fengfeng LI Yi SHEN
    The Chinese Journal of Process Engineering. 2022, 22(2):  162-175.  DOI: 10.12034/j.issn.1009-606X.221054
    Asbtract ( )   PDF (15934KB) ( )  
    Related Articles | Metrics
    The polymer semiconductor g-C3N4 has attracted widespread attention in fields such as pollutant degradation and clean energy production due to its features such as narrow band gap, high stability, low cost, etc. However, there are some drawbacks of g-C3N4 that it has low charge separation rate, high charge recombination rate, etc., which lead to its unsatisfactory photocatalytic ability. Therefore, improving the photocatalytic performance of g-C3N4 has become a research hotspot in the field of photocatalysis. The g-C3N4-based photocatalysts prepared by heterojunction construction, elemental doping and other modification methods can enhance the absorption of visible light and have strong photocatalytic ability, which have wide industrial application prospects. In this work, firstly, the research actuality of g-C3N4-based photocatalysts was briefly introduced. Secondly, this work discussed the research status of preparation methods and introduced several preparation methods for g-C3N4. It also explained the problems that should be paid attention to when applying different preparation processes. In addition, various mechanisms of the approaches to improve its photocatalytic performance were illustrated, and the development directions were pointed out, summarized and prospected. In the follow-up research, if the advantages of material science and environmental science can be effectively combined to prepare g-C3N4-based photocatalyst composites with stable structure and excellent photocatalytic performance, it will be of great significance to improve practical value of g-C3N4.
    Research Paper
    Preparation and performance of PB/ITO-PET flexible electrochromic films
    Duoyin ZHU Zhihao JIN Wenli LI Qianyu WANG Rongcheng WU Yanbin CUI
    The Chinese Journal of Process Engineering. 2022, 22(2):  176-185.  DOI: 10.12034/j.issn.1009-606X.221005
    Asbtract ( )   PDF (2787KB) ( )  
    Related Articles | Metrics
    Due to the advantages of small volume, light weight and flexibility, flexible electrochromic (EC) devices have drawn much attention in various fields, such as flexible display screens, smart windows, information storage, electronic paper and energy-saving bracelets, etc. EC materials can be classified into two categories: inorganic and organic systems. Compared with organic EC materials, inorganic EC materials display good stability and reliability. Prussian blue and transition metal oxides are the two major classes of inorganic EC materials. Up to now, most reported EC devices in literatures are deposited on rigid substrates. It is still a major challenge to realize excellent EC devices on flexible substrates. Combining EC materials with flexible substrates is expected to have great application prospects in future smart clothes and implantable displays. In this work, potassium ferricyanide, potassium chloride and anhydrous ferric chloride were used as precursor. Prussian blue (PB) was deposited on ITO-PET flexible substrate by electrodeposition method to prepare PB/ITO-PET EC film. Scanning electron microscope, ultraviolet spectrometer and electrochemical workstation were used to characterize its microstructure and electrochemical performance. The experimental results showed that the light absorption rate of PB/ITO-PET EC film with the electrodeposition time of 200 s was 0.755 at the wavelength (λ) of 700 nm. The PB/ITO-PET EC film was colored and faded at low voltage (0.6 V/-0.3 V). The light modulation range, coloring/fading response time, coloring efficiency were 68%, 9 s/8 s and 108 cm2/C, respectively. The light modulation range and coloring efficiency of PB/ITO-PET EC film after 1000 coloring-fading cycles were 68% and 100.3 cm2/C. The coloring efficiency was 105.5 cm2/C after 500 bending, and the coloring efficiency and light modulation range of PB/ITO-PET electrochromic film were 91 cm2/C and 65% after 500 bending and 1000 coloring-fading cycles. Finally, a flexible EC device was assembled using ITO-PET as ion storage layer (counter electrode), gel electrolyte and PB/ITO-PET as working electrode, and its light modulation range and coloring/fading response time were 53% and 13 s/18 s, respectively.
    Crystal growth mechanism in the process of iron removal by shear-enhanced goethite method
    Qiang ZHU Jianguang YANG Yuanlin ZHOU Wenchao WANG Tianxiang NAN Chaobo TANG Weizhi ZENG
    The Chinese Journal of Process Engineering. 2022, 22(2):  186-194.  DOI: 10.12034/j.issn.1009-606X.221003
    Asbtract ( )   PDF (4826KB) ( )  
    Related Articles | Metrics
    Removing iron from the solution is an indispensable procedure to ensure the quality of zinc products in zinc hydrometallurgy. Regarding the requirements of economic cost and environmental protection, the goethite method has a significant advantage in iron removal. However, due to the existing regulation technology of iron removal by the goethite process, the crystal shape of goethite residue is difficult to be controlled stably, which leads to the problems of poor filtration performance. At the same time, the iron grade is low and the zinc content is high in the produced goethite residue. The mechanism of crystal structure, microscopic morphology and element occurrence in the homogeneous and heterogeneous nucleation crystal growth process was investigated by X-ray diffraction spectroscopy, scanning electron microscope, and inductively coupled plasma emission spectroscopy in the ZnSO4-FeSO4 system. Moreover, the regularity of iron removal by shear-enhanced goethite was verified in a real solution. The results showed that there were no obvious goethite crystal characteristics at the initial stage of iron settling slag in the process of homogeneous nucleation, and the amorphous nuclei were spherical. The iron grade and zinc contented fluctuate greatly, increased from 43.13wt% and 4.57wt% in the early stage to 57.76wt% and 6.12wt%, respectively. In the early stage of heterogeneous nucleation, the secondary growth of the seed was the main method, which effectively avoided the generation of a large number of amorphous iron residues. Compared with homogeneous nucleation, the size of the crystal was larger and the crystallinity was higher, and the zinc was finally controlled at 5.60wt%. Compared with the simulated solution, the growth and development of goethite crystal in the real solution with complex properties were more difficult to control, but it can ensure the goethite crystal precipitation, and the content of iron and zinc in the iron-settling slag was controlled at 57.63wt% and 5.90wt%, respectively. The industrial zinc oxide fume was used as a neutralizing agent to obtain the final goethite residue containing 52.59wt% iron and 6.93wt% zinc. This study provided a theoretical basis for the application of shear strengthening technology and the selection of nucleation mode in the hydrometallurgical zinc-goethite process.
    Preparation and immunogenicity of alum-stabilized Pickering emulsion
    Sha PENG Yufei XIA Xiaodong GAO
    The Chinese Journal of Process Engineering. 2022, 22(2):  195-203.  DOI: 10.12034/j.issn.1009-606X.221017
    Asbtract ( )   PDF (4377KB) ( )  
    Related Articles | Metrics
    Combating against the emerging pandemics, exploring the immunogenicity of the approved formulations is regarded as the optimal strategy for rapid clinical translation. To date, aluminum hydroxide adjuvant (termed as "alum"), which was composed by AlO(OH) has been used as the sole licensed adjuvant approved in China. Unfortunately, they seldom induce effective T cells-mediated immune response to produce efficient protection to meet the increasing demand for vaccine adjuvant. Therefore, the rational design of alum-based adjuvant may offer a novel and clinical-translatable vaccine platform for the potent immune activations and safety profile. In this work, alum particulate emulsion (APE) droplets were prepared by alum, and alum was adsorbed on the interphase between the US food and drug administration (FDA)-approved squalene and water. In contrast to the surfactant-stabilized emulsion, alum tends to adsorb on the squalene/water interphase, conferring a low surface tension and enhanced stability. After a series of optimizations, APE was prepared, with an average size of 2723.7±435.3 nm and a Zeta potential of +40.5±1.5 mV. Centrifugation demonstrated that 2.0 mg/mL was the minimum particle concentration to stabilize the emulsion droplets, which possessed just enough alum to avoid both the coalescence of the emulsions and the formation of larger aggregates due to excess in the continuous phase. SEM images indicated that alum was closely wrapped on the oil/water interphase, demonstrating a raspberry-like morphology. Additionally, CLSM images illustrated that the antigens were adsorbed on the squalene/water interphase of emulsion droplets in high efficiency. When treated with dendritic cells (DC), the enlarged internalization and lysosomal escape of the antigens were observed, indicating the potential for higher immune responses. After intramuscular injection, ELISpot results showed that IFN-γ secreted T cells increased by about 300% compared with that of alum accepted group, suggesting that prepared emulsion droplets were efficiently stimulated the cellular immune response. Collectively, with the feasibility of alum adsorptions on the oil/water interphase, as well as the bedside mixing of antigens, APE may provide insights for the development of a safe, accessible, and efficient adjuvant strategy for potent cellular immune response, which may offer an efficient strategy for clinically approved vaccine formulations.
    The improvement effect of modified fly ash on the physical properties of sandy soil
    Mingzhe LI Shuhua MA Jianbing WANG Xiaohui WANG Tongyu YAO Chenxu LIU
    The Chinese Journal of Process Engineering. 2022, 22(2):  204-213.  DOI: 10.12034/j.issn.1009-606X.220418
    Asbtract ( )   PDF (1822KB) ( )  
    Related Articles | Metrics
    Aiming at a series of problems such as large amount of fly ash (FA), low utilization rate and serious desertification of local soil in Ximeng Region of Inner Mongolia, this work put forward a new idea of using fly ash to improve desert soil. Firstly, the inert fly ash was activated by sulfuric acid. Scanning electron microscope (SEM) and X-rays diffraction (XRD) were used to study the structural changes of fly ash. X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TG) were used to analyze the surface hydroxyl of fly ash qualitatively and quantitatively, so as to clarify the surface hydroxylation effect of fly ash. Secondly, the influence of modified fly ash on the stability of sand soil was studied by using fly ash before and after modification as soil reinforcement agent. The results showed that the number of hydroxyl groups on the surface of the particles increased by 4 times compared with the original fly ash after pre-modification with 1.5 mol/L sulfuric acid solution. According to the mass ratio of 1:9, fly ash before and after acid modification was mixed with sand and stood for 15 days, respectively, and the mechanical strength of the mixed soil was measured. The cohesion between the original sand was 0.29 kPa, and the cohesion between fly ash and sand before modification was 0.88 kPa. However, the cohesion of the modified fly ash-sand mixture was increased to 3.51 kPa. The fly ash-sand composite soil prepared by adding modified fly ash and sand soil had the functions of sand fixation, water retention, nutrient supply and soil aggregate structure reconstruction.
    Preparation and humidity-regulation performance of gelatin based natural polymer/graphene oxide composite microcapsules
    Xueyan HOU Lihao NI Haitao ZHAO Wenbo ZHANG Yuqi ZHANG Jijiang WANG
    The Chinese Journal of Process Engineering. 2022, 22(2):  214-221.  DOI: 10.12034/j.issn.1009-606X.221035
    Asbtract ( )   PDF (5433KB) ( )  
    Related Articles | Metrics
    It is an environmental friendly and energy saving passive humidity regulation technology to use humidity control materials, which has been widely used in indoor humidity control, food packaging, cultural relic protection and other fields. The chitosan, liquid paraffin and graphene oxide were used as the microcapsule core materials. The surfactant-like hydrophilic and oleophilic chitosan-graphene oxide complex was formed by the electrostatic interaction between chitosan and graphene oxide. And the emulsion micelle was obtained emulsified by the combined assistance of emulsifier and chitosan-graphene oxide complex. Then using the emulsion micelle as template, the gelatin-based natural polymer/graphene oxide composite microcapsules (M-GO) were fabricated by the crosslinking of glutaraldehyde. The influence of graphene oxide dosage and emulsifying pH value on the micelle size and stability of emulsion was investigated. The microcapsules were obtained under the optimal emulsifying condition. The effect of graphene oxide on the structure and moisture adsorption/desorption performance of microcapsules were studied. The as-prepared microcapsules were characterized by Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and N2 adsorption-desorption isotherms. The humidity-regulation performance was studied by measuring the moisture absorption and desorption rates. The results showed that emulsion micelle size was uniform with good stability when the dosage of graphene oxide was 3 mL (1 mg/mL) and the emulsifying pH value was 5.10. The results indicated that the microcapsules were successfully prepared by the interaction between graphene oxide, chitosan and gelatin. The microcapsule without graphene oxide showed a closed microsphere structure. After introducing graphene oxide, the microcapsule M-GO exhibited an open hollow shell and had larger surface area and pore volume, which was beneficial to adsorption moisture. The saturated moisture content and adsorption/desorption rate of M-GO in different humidity conditions were better than those of microcapsules without graphene oxide. It indicated that the introduction of graphene oxide can improve humidity-regulation performance by changing the microstructure and increasing the surface area for adsorbing moisture.
    Consideration on removal of non-spherical solid inclusions at steel-slag interface
    Yelian ZHOU Zhiyin DENG Miaoyong ZHU
    The Chinese Journal of Process Engineering. 2022, 22(2):  222-231.  DOI: 10.12034/j.issn.1009-606X.221013
    Asbtract ( )   PDF (1499KB) ( )  
    Related Articles | Metrics
    In order to understand the phenomenon that solid inclusions are easier to be removed in contrast to liquid inclusions during steelmaking process, a mathematical model was established to describe the separation processes of octahedral and plate-like inclusions based on the analysis of the forces acting on inclusions at the steel-slag interface. Besides drag force, buoyancy force and capillary force as well as added-mass force considered in the previous mathematical models, the interfacial resistance force caused by the deformation of the steel-slag interface was further considered in the model of this study. Based on the model, the effects of interfacial tension between phases (steel, slag and inclusion) and slag viscosity on the separation process were studied. The results showed that the capillary force was the driving force for solid inclusion crossing the interface between steel and slag, and it was determined by the overall wettability of the system (steel, slag and inclusion) and the shape of an inclusion. Meanwhile, the drag force was the resistance force for the separation of an inclusion at the steel-slag interface, and the slag viscosity was an important factor to this force. Without the consideration of chemical dissolution, the released interfacial free energy of the steel-slag-solid inclusions system was a driving energy for the separation of solid inclusions at the interface, and it would be sufficient to make most solid inclusions separate from the interface. Furthermore, the Gibbs free energy released during the dissolution of inclusions was much larger than the interfacial free energy. According to the principle of minimum free energy, the dissolution process would promote the entering of solid inclusions into slag. Therefore, the Gibbs free energy was also a driving energy for the separation process. Considering the separation time was very short (less than 10-3 s), in steelmaking process, solid inclusions would be removed quickly at steel-slag interface, once they contact with the steel-slag interface.
    Study on granulating mechanism of iron ore powder in drum mixer based on liquid-bridge effect
    Shuguang GONG Ming LIAO Xingfu LU Zhijian ZUO Kejian LIU
    The Chinese Journal of Process Engineering. 2022, 22(2):  232-239.  DOI: 10.12034/j.issn.1009-606X.221051
    Asbtract ( )   PDF (2701KB) ( )  
    Related Articles | Metrics
    To solve the problem of granulating with different magnitude sizes of particles in the drum mixer, the existing calculation formula of liquid bridge force was modified and the corresponding discrete element model was established in this work. Through the combination of experimental test and simulation, the influence of the correction coefficient on particle motion was discussed, and the correction coefficient of 0.6 was found to be suitable. Taking the accumulation angle of the iron ore powder mixture as a reference, the physical property parameters of the mixture were obtained through simulation and experimental tests. On this basis, the movement law, agglomeration mechanism, and the distribution of agglomerates of iron ore powder mixture were discussed. The results showed that the larger the spin velocity and the smaller the sheer force of agglomerate powder, the more favorable the granulation was. The particle size of agglomerate increased first and then decreased along the radial direction of the cylinder, and there was an "efficient granulation zone" under the surface layer of the mixture, in which the particle size of agglomerates was the largest, the shear force was the least and the spin velocity was high. It was suggested that the collision frequency or energy loss of the agglomeration particle can be used as the criterion to stop the agglomeration of particles, to achieve the purpose of energy-saving. The conclusions can provide a design basis for the research and development of iron ore powder drum mixer.
    Adsorption and reaction of CH3Cl on both ZnO(001) and ZnO(100) surface based on the first principles calculation
    Yazhuo ZHANG Jinhui ZHAN
    The Chinese Journal of Process Engineering. 2022, 22(2):  240-248.  DOI: 10.12034/j.issn.1009-606X.221064
    Asbtract ( )   PDF (3903KB) ( )  
    Related Articles | Metrics
    Based on the first principles method of density functional theory, the adsorption models of ZnO(100) and ZnO(001) surfaces were established to investigate the adsorption and reaction mechanisms of CH3Cl on ZnO surface through considering the adsorption sites, adsorption energy, charge density, density of states and transition state. The simulated results indicated that the adsorption of CH3Cl on both ZnO(100) and ZnO(001) surfaces was chemical adsorption. When CH3Cl was completely adsorbed, a weak chemical bond was formed between Cl and Zn atoms on ZnO surface. The adsorption of CH3Cl on ZnO(100) surface was more stable because the adsorption energy (-0.57 eV) of CH3Cl on ZnO(100) surface was lower than that (-0.42 eV) on ZnO(001) surface. When CH3Cl was adsorbed on ZnO(100) surface, the peaks of state density formed by the 3p orbital of Cl atom shifted to the left and the peak value near the Femi level was diminished comparing with that before the adsorption of CH3Cl. Thus the bonding effect of CH3Cl on ZnO(100) surfaces was more stronger and improved the stability of the system. During the dissociative adsorption of CH3Cl, the C atoms in methyl radical can be adsorbed to O(2a) and O(3a) on the surface of ZnO(100), respectively. The adsorption energy of CH3Cl dissociation adsorption on Zn(2a)/O(2a) site was -1.09 eV. There were three resonance peaks between O 2p and C 2p orbitals on the left side of the Fermi level. It was proved that there was a strong interaction between C and O atoms. On the other hand, the adsorption energy for CH3Cl dissociating on Zn(2a)/O(3a) site was -1.02 eV, and there was a resonance peak of O 2p and C 2p orbitals on the right side of Fermi level, indicating that there was a certain antibonding interaction between C and O atoms. The calculation results of reaction path way showed that the transition state energy of CH3Cl dissociation adsorption at Zn(2a)/O(2a) site was 1.69 eV, while it was 2.06 eV at Zn(2a)/O(3a) site. Therefore, the dissociation adsorption reaction of CH3Cl tends to occur at Zn(2a)/O(2a) site and to form the stable structure.
    Dynamics performance of pressure swing distillation for acetone and cyclohexane separation
    Chunhua ZHANG Lin ZHU Liping LÜ Qian ZHOU Shisheng JIN
    The Chinese Journal of Process Engineering. 2022, 22(2):  249-257.  DOI: 10.12034/j.issn.1009-606X.221022
    Asbtract ( )   PDF (1545KB) ( )  
    Related Articles | Metrics
    As significant chemical raw material and solvent, acetone and cyclohexane are widely applied in chemical industry. However, the mixture of them will form a minimum boiling homogeneous azeotrope at atmospheric pressure, which severely hinders the separation of them. Based on the advantages of pressure swing distillation (PSD) and the pressure sensitivity of the azeotropic mixture of acetone and cyclohexane, the investigation of the design and the simulation of PSD are implemented by Aspen Plus software. The results show that the purity of products achieve 99.9wt%. In order to save the total annual cost (TAC) and energy, based on the heat integration technology and economic optimization, it is implemented that the process enhancement with the minimum TAC as objective function. Furthermore, the TAC of the steady-state process of conventional, partial and full heat integration PSD are 3.64×105, 2.83×105, 2.76×105 $/y, respectively. Compared with the conventional PSD, the economic reduction rate of partial and full heat integration are 22.36% and 24.18%, respectively, and the full heat integration is most economical. In view of these, the different control structures are established by Aspen Plus Dynamics, and the anti-disturbance performance is investigated by changing the feed flow rate and composition, the dynamic performance of the full heat integration PSD process is assessed. The dynamic response results indicate that the control structure with a fixed reflux-to-feed flow rate ratio is better than the control structure with a fixed reflux ratio in terms of settlement time. However, the control structure with a fixed reflux-to-feed flow rate ratio cannot maintain product purity, up to the design value of 99.9wt%. For meet the goal of the requirements of products purities, an improved control structure with feed forward proportional (reboiler heat duty to feed flow rate ratio) control and composition-temperature cascade control are proposed, which can effectively ensure that the product purity reaches more than 99.9wt%.
    Experimental study and simulation calculation on compressive performance of coal with fracture
    Fangyue SHI Minmin LI Haixiao LIN Gaowei YUE
    The Chinese Journal of Process Engineering. 2022, 22(2):  258-267.  DOI: 10.12034/j.issn.1009-606X.221033
    Asbtract ( )   PDF (1921KB) ( )  
    Related Articles | Metrics
    As a heterogeneous brittle material, coal contains many micro pores and randomly distributed cracks, which are difficult to observe. With the help of industrial CT scanning equipment and three-dimensional image reconstruction technology, the location and distribution characteristics of the main primary fractures which are irregular and concentrated in the coal section can be effectively restored. On this basis, the conventional triaxial compression tests with confining pressures of 1 MPa and 3 MPa were carried out. Furthermore, the original fracture data were imported into the discrete element software to obtain the meso scale parameters consistent with the indoor test stress-strain curve, and then the biaxial compression numerical simulation tests with confining pressure of 0, 1, 3, 5, 7, 9 MPa and loading rate of 0.01, 0.1, 0.2, 0.3, 0.4, 0.5, 0.7, 0.9, 1.0 m/s were carried out for the models with different distribution patterns of original fractures to compare the different confining pressures. The results showed that the compressive strength, elastic modulus, crack growth morphology and other mechanical parameters of the specimen changed with the loading rate. The results showed that the DEM can be used to simulate the mechanical properties of coal under the influence of primary fractures. With the gradual increase of confining pressure, the compressive strength of coal increased exponentially, and the change of elastic modulus was not sensitive. The failure of the specimen was affected by the primary fracture, which was more significant under low confining pressure. With the increase of loading rate, the compressive strength of the sample increased slowly at first, then increased rapidly and tends to be flat. The failure mode of the sample was significantly affected by the primary cracks at low loading rate, and the failure of the sample end was more obvious at high loading rate.
    Study on sulfur removal from ferric phosphate by high-temperature calcination
    Wenbo LOU Ying ZHANG Yang ZHANG Xiaojian WANG Jianzhong LI Shan QIAO Shili ZHENG Yi ZHANG
    The Chinese Journal of Process Engineering. 2022, 22(2):  268-275.  DOI: 10.12034/j.issn.1009-606X.221043
    Asbtract ( )   PDF (1247KB) ( )  
    Related Articles | Metrics
    Iron phosphate is the main material for the synthesis of lithium iron phosphate battery cathode material, which is mainly produced by co-precipitation method of using ferrous sulfate and phosphate salt. The sulfur content in the iron phosphate prepared by the co-precipitation process in the sulfate system is high, which has to be removed by washing with large amount of water of around 60~100 tons per ton of iron phosphate, bringing a huge burden of sulfate-bearing wastewater treatment. To reduce the amount of wastewater from the source, this research proposed an alternative way for desulfurization by high-temperature calcination based on the feature of sulfate decomposition at high temperatures. The thermodynamic feasibility and kinetics of the desulfurization were studied. The results showed that the sulfur in ferric phosphate existed in the form of sulfate, which can be effectively removed by high-temperature calcination. A higher temperature was preferred for a more satisfactory desulfurization efficiency. Kinetic study uncovered that the desulfurization reaction order was 2, and the activation energy was 88.075 kJ/mol, indicating a chemical reaction control mode. The sulfur content in iron phosphate can be reduced to less than 0.01wt% by calcining at 1173 K for 10 min.
    Experimental study of effect of coalescence layer arrangement on filtration performance of filter for high-pressure natural gas purification
    Jun HE Xiaofeng ZHONG Feng CHEN Zhuangzhuang HUANG Jiachang LIU Yaohan WU Zhongli JI
    The Chinese Journal of Process Engineering. 2022, 22(2):  276-284.  DOI: 10.12034/j.issn.1009-606X.221353
    Asbtract ( )   PDF (1154KB) ( )  
    Related Articles | Metrics
    In the field of high-pressure natural gas purification, it is a challenging problem to improve the performance of coalescence filter element. In this work, the filtration performance of filter elements with the same coalescence filter materials and combination of different coalescence filter materials were studied, and the effects of the arrangement of coalescence layers on the filtration efficiency, pressure drop, saturation and liquid distribution were analyzed by using the experimental device for the filtration performance of coalescence filter element. The results showed that the filtration efficiency of the filter element composed of the same filter materials increased with the decreasing pore size of filter material, but due to the higher pressure drop, the overall filtration performance was the worst for the minimum pore size case. The coalescence layer arrangement of oleophobic layer in front and oleophilic layer in back could improve the filtration efficiency of the filter element and reduce the secondary entrainment of droplets. The filtration efficiency of the filter element staggered with two layers of the same filter material was significantly higher than that of the single-layer filter material, and the pressure drop was relatively low, which greatly improved the overall filtration performance. Further increase of the number of oleophobic layers on the inlet side delayed the increase of pressure drop and improved the operation life, and the steady-state quality factor of the filter element reached the maximum value (0.30 kPa-1). The influence of coalescence layer arrangement on the filtration performance of filter element was mainly realized by changing the liquid distribution form, and the channel structure change of last filter layer was the main reason for the filtration performance difference of filter elements with various coalescence layer arrangements.