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    28 November 2024, Volume 24 Issue 11
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    Contents
    Cover and Content
    The Chinese Journal of Process Engineering. 2024, 24(11):  0. 
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    Review
    Research progress of lithium extraction technology from lepidolite
    Hong YANG Wei ZHONG Faping ZHONG Jiahui ZHAO Dong LI Lei ZHANG Xueyi GUO
    The Chinese Journal of Process Engineering. 2024, 24(11):  1251-1262.  DOI: 10.12034/j.issn.1009-606X.224019
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    Lithium and its compounds are indispensable materials in modern industry and have important applications in the fields of batteries, ceramics and lubricants. China is rich in lithium resources, most of which occur in salt lake brine. However, due to the limitation of resource endowment and geographical location and climate, its production capacity cannot meet the needs of the rapid development of new energy industry in China, and lithium extraction from ores has become an important source of lithium products. Yichun, Jiangxi province has the largest associated lepidolite resources in China, and the development and utilization of lepidolite resources is of great significance to ensure the sustainable development of lithium resources in China. In this review, the principle, advantages and disadvantages of the existing lithium extraction processes from lepidolite are summarized. Based on the understanding of the existing methods, typical lithium extraction processes from lepidolite such as acid method, alkali method and salt method are summarized and evaluated. Among them, the acid method is mature, but there are some problems such as difficulty in impurity removal from leaching solution, low efficiency in lithium extraction and equipment corrosion. Although the alkali process has high efficiency of extracting lithium, its reaction mechanism is not clear, and the waste residue is difficult to use. Although the salt process has high selectivity to lithium and simple process, it also has the problems of high energy consumption and large amount of slag. The development direction of lepidolite extraction technology should focus on the collaborative treatment of multiple technologies to achieve efficient, economical and environmentally friendly extraction of valuable elements. Therefore, some measures to improve the process are put forward, aiming at providing reference for the future research, development, optimization and industrial application of the process.
    Research Paper
    Numerical simulation of filtration characteristics of flat ceramic membrane
    Zheng LU Yan AN Yang DENG Ran CHENG Hai LIU Mengkui TIAN
    The Chinese Journal of Process Engineering. 2024, 24(11):  1263-1273.  DOI: 10.12034/j.issn.1009-606X.224044
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    Flat ceramic membranes, prized for their corrosion resistance, abrasion resistance, and substantial processing capacity, find extensive applications in the filtration and separation processes of metal and non-metal pulp, such as iron ore, copper ore, and phosphate ore. In pursuit of a comprehensive understanding of the intricate internal flow dynamics inherent to flat ceramic membranes during the phosphorus concentrate separation process, this study aims to meticulously scrutinize the intricate nuances of flow field characteristics. In order to refine and optimize various parameters encompassing process intricacies, membrane architecture intricacies, and strategies for mitigating membrane fouling phenomena, a structural model for flat ceramic membranes is set up. Experimental and computational fluid dynamics (CFD) analyses are employed to validate the reliability of the porous media model in simulation. Subsequently, gas-liquid multiphase flow model and realistic gas model are integrated to investigate the dynamic variations in internal pressure and flow rate during the filtration of water through ceramic membranes. Additionally, the impact of air ingress, operating pressure and slurry concentration on the filtration process are analysed. Simulation results indicate that the entry of air has the most significant influence on vacuum degree when the operating pressure is set at -0.08 MPa. Transient simulations unveil the entire process dynamics of ceramic membrane filtration, from initial air evacuation to stabilized flow, revealing the first 3 seconds as the high-efficiency filtration interval. Subsequently, the flow rate decreases and stabilizes, with the stabilized flow rate contingent upon the outlet operating pressure. The difference in cumulative filtration flow rates between operating pressures of -0.06 and -0.08 MPa within 5 seconds is minimal. The research outcomes provide valuable theoretical guidance for determining the most suitable filtration durations and pressure settings tailored to diverse process specifications, as well as contributing to the enhancement of production efficiency and the reduction of energy consumption.
    Effect of roasting modification on visible light photo-Fenton catalytic performance of zinc-containing electric furnace dust
    Rui ZHOU Shiyu HUANG Weiming LIU Zhaojin WU
    The Chinese Journal of Process Engineering. 2024, 24(11):  1274-1283.  DOI: 10.12034/j.issn.1009-606X.224047
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    Zinc containing electric arc furnace dust (EAFD) is a hazardous solid waste generated during the electric arc furnaces steelmaking process, which contains a large amount of zinc and iron oxides. Systematically studying its photocatalytic performance is of great significance for its high value-added utilization. Herein, the EAFD collected from Masteel is treated by roasting modification, and the effect of roasting on its visible light photo-Fenton catalytic activity is evaluated using acid orange II (AOII) as a model pollutant. The phase structure, microtexture, and photoelectrochemical properties of EAFD are analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and photoelectrochemical workstation, and the relevant mechanisms are discussed. The results indicate that EAFD has good visible light catalytic activity, and calcination has a significant impact on its phase components, carrier concentration, separation and transport behavior of photo generated electrons/holes, thereby regulating its photo-Fenton catalytic performance. Calcination at 260℃ can effectively remove inert attachments on the surface of particles without changing their main phase composition, exposing more active sites on the surfaces of catalytic active phases Fe3O4, ZnFe2O4, and ZnO. Compared to the uncalcined EAFD sample, the carrier concentration has increased by 1.66 times, and it possesses the lower electrochemical impedance and better photo-generated electron/hole separation efficiency. Compared with the uncalcined sample, its degradation rates for AOII at 2, 4, and 6 h increase by 47.6%, 11.1%, and 7.4%, respectively, with a degradation rate of 94.2% after 6 h. Further increasing the calcination temperature to 510 and 650℃, the degradation rates of AOII over the calcined EAFD samples decrease to 87.8% and 63.8% within 6 hours respectively, being attributed to the transformation of ZnO and some Fe3O4 in EAFD into ZnFe2O4 and particle coarsening above 510℃. Mildly roasted zinc containing electric arc furnace dust can be used as a low-cost, high visible light activity photocatalytic material, with potential applications in the treatment of organic pollutants in industrial wastewater. It has positive significance for the high value-added utilization of metallurgical solid waste and sustainable environmental development.
    Parameter prediction and optimization of liquid hydrocarbon recovery unit based on BP neural network and genetic algorithm
    Zilong WANG Guilian LIU
    The Chinese Journal of Process Engineering. 2024, 24(11):  1284-1296.  DOI: 10.12034/j.issn.1009-606X.224072
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    The natural gas light hydrocarbon recovery unit contains a number of key operation parameters, including the composition of the mixed-refrigerant, the temperature of cryogenic separator, plate pressure, etc. These parameters directly affect the energy consumption and product quality of the system. The relationship among these parameters are complex and interrelated, which makes it complicated to build theoretical models systematically. Based on the actual production data of a liquid hydrocarbon recovery unit, a BP neural network model for optimizing and predicting the mixed refrigerant composition and other key operation parameters was established to achieve the goal of saving energy and increasing efficiency. The model can adapt to the changes in natural gas feed and production requirements and the overall prediction accuracy was high. Most of the mean absolute percentage error (MAPE) of the output parameters was less than 5%, and the minimum error was as low as 0.118%. The output parameters with unsatisfactory prediction effects were optimized by genetic algorithm (GA). After the optimization, the error of the liquid phase flow rate of the refrigerant separator decreased from 9.208% to 3.321%, and the error of plate pressure of the demethanizer reduced from 9.602% to 4.051%. Based on the established GA-BP neural network model, the refrigerant components and liquid phase flow rate and pressure of the refrigerant separator were optimized under different feeding conditions in summer and winter. The optimization results showed that the molar fraction of methane, propane, and isobutane in mixed-refrigerant and the flow rate of refrigerant separator should be appropriately increased in summer, and the molar fraction of ethylene should be reduced. In winter, the molar fraction of isobutane and the pressure of liquid refrigerant should be properly reduced. Taking the summer feed conditions as an example, the optimization of the mixed refrigerant proportion and various operating parameters resulted in a reduction of the refrigeration system's energy consumption by 518.12 kW. The optimization of key operation parameters based on the neural network model can increase the ethane yield and reduce cross-section temperature difference of main cold box, which is of great significance for actual production process.
    Research on extraction of calcium from steel slag based on orthogonal test
    Rui WANG Feng YAN Chuiyuan KONG Changxi TANG
    The Chinese Journal of Process Engineering. 2024, 24(11):  1297-1307.  DOI: 10.12034/j.issn.1009-606X.224032
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    Steel slag and CO2 are the two major wastes emitted by the iron and steel industry. Indirect carbonation of steel slag can achieve the dual benefits of Ca circulation and carbon emission reduction. Effective leaching of Ca from steel slag is a key step in the indirect carbonation process. However, Ca in steel slag exists in different Ca-based phases, and different active phases lead to different leaching efficiency. In order to investigate the dissolution law and reaction mechanism of the Ca-based phase of steel slag in the leaching process and the influence of the leaching process on leaching efficiency, ammonium chloride solution was employed as an extractant to leach steel slag. Furthermore, a thermodynamic calculation method was utilised to predict the dissolution behaviour of the calcium-containing phase of steel slag. The relationship between solid-liquid ratio, extractant concentration and leaching temperature on leaching efficiency was investigated by means of an orthogonal test. In addition, the mineral composition, surface morphology, element distribution and particle size change of steel slag before and after leaching were characterised by XRD, SEM-EDS, and particle size distribution. The results showed that the factors affecting the leaching efficiency of Ca in steel slag were solid-liquid ratio, leaching agent concentration and leaching temperature according to their influence. Under the conditions of solid-liquid ratio of 1:40, leaching temperature of 80℃, and leaching agent concentration of 3 mol/L, the concentration of Ca2+ in the solution was 4689.4 mg/L after leaching for 1 h, and the leaching rate was 63.1%. The results of thermodynamic calculations, XRD, and SEM-EDS analysis indicated that ammonium chloride selectively extracted calcium from the calcium-containing phase, while the iron remained in the slag to form enrichment. In this process, the particle size of the steel slag gradually decreased, and cracks and holes were generated on the surface, which was beneficial to increase the contact area between the steel slag and the ammonium chloride solution.
    Reaction influence of iron oxides for arsenic removal and scorodite synthesis from high-arsenic waste acid
    Zengbin CHAI Xing ZHU Boyu DU Nan JIANG
    The Chinese Journal of Process Engineering. 2024, 24(11):  1308-1317.  DOI: 10.12034/j.issn.1009-606X.224079
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    In order to achieve harmless disposal of high-arsenic waste acid and efficient arsenic solidification, the idea of using solid iron sources for arsenic removal from waste acid was proposed, and the influence of solid iron oxide on the arsenic removal process from high-arsenic waste acid and the synthesis of scorodite was explored. The results showed that the full reaction between solid iron oxide and waste acid at room temperature could provide initial iron ions for the arsenic removal reaction and reduces the pH of the solution. This reaction was conducive to the initiation of arsenate precipitation reaction, and aided in the stable nucleation and good crystallization of scorodite. During the experiment, it was found that the presence of arsenate ions can promote the dissolution of solid iron oxides in the system, and it was revealed that the mutual promotion effect of "solid iron oxide dissolution-arsenate precipitation" existing in an acidic environment was an important way to achieve efficient arsenic removal. Fe3O4 magnetic nanoparticles (MNPs) underwent Fenton reaction during the arsenic removal process, producing abundant hydroxyl radicals. This reaction can promote the dissolution of Fe3O4 in the solution and accelerated the precipitation of arsenate, giving the Fe3O4 the best arsenic removal performance. When the reaction time was 12 h, the pH was 1.5, the Fe/As molar ratio was 2, and the reaction temperature was 90℃, Fe3O4 had the best arsenic removal efficiency in waste acid, which could reach 99.93%. Based on this, a new process was proposed for the efficient treatment of contaminated water using Fe3O4, including efficient arsenic removal of high-arsenic contaminated acid and further purification of low-arsenic contaminated acid. This process has a high arsenic removal rate while avoiding secondary pollution. By using scorodite to remove arsenic, the adsorption and magnetic characteristics of MNPs were used to achieve deep removal and efficient solidification of arsenic in waste acid.
    Study on the influence of diamine agents on the flocculation settling performance of aegirite and their adsorption mechanisms
    Yiming HU Yang CAO Cheng YANG Yang HUANG Xiangpeng GAO Mingyang LI
    The Chinese Journal of Process Engineering. 2024, 24(11):  1318-1325.  DOI: 10.12034/j.issn.1009-606X.223367
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    Aegirite is a gangue mineral often associated with iron ore. Due to its low hardness, it is easier to be crushed and argillated than iron ore in the grinding process. The argillated fine aegirite further increases the difficulty of iron tailings treatment. In this study, the effects of 6 kinds of diamines with different molecular chain lengths and both ends were amino on the flocculation performance of aegirite were explored through flocculation sedimentation test, and 1,8-octamethylene diamine (ODM) with the best flocculation effect was selected through free sedimentation test, flocculant type test, pH test and flocculant concentration test in sequence. The adsorption mechanism of ODM on the surface of fluorite was investigated using Zeta potential measurements, Fourier-transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) analysis. The results of flocculation and sedimentation test showed that the best flocculation effect of ODM on aegirite was achieved when pH=6 and ODM concentration was 0.1wt%. In this case, aegirite settles completely within 60 s, and the rate of flocculation settlement is about 4 times that of free settlement. In addition, the Zeta potential of aegirite before and after the flocculation reaction was measured by the mechanism test. After adding the flocculant, the zero potential point of aegirite moved from 4.56 to 6.56, indicating that the interaction between the flocculant and the surface of aegirite was obvious. The adsorption behavior of the flocculant on the surface of aegirite was verified by FTIR analysis, and the functional groups belonging to the flocculant were adsorbed on the surface of aegirite. The adsorption mechanism was verified by XPS. It was found that the high resolution spectra of C 1s and N 1s after the treatment of the agent showed obvious new peaks, which further indicated that the agent was adsorbed on the surface of aegirite, and the binding energy of the upper peak of the Fe 2p spectrum was shifted by 0.1 eV, indicating that the adsorption behavior was non-chemisorption. The mechanism test results showed that ODM acts on the surface of aegirite mainly through electrostatic adsorption and hydrogen bond adsorption, and electrostatic adsorption played a dominant role in the adsorption process.
    Wettability and interfacial behavior between vanadium titanium magnetite sodium smelting slag and SiC refractory
    Fei ZHAO Zhiwei BIAN Hongxin ZHAO Desheng CHEN Lina WANG Yulan ZHEN Zhangfu YUAN Tao QI
    The Chinese Journal of Process Engineering. 2024, 24(11):  1326-1334.  DOI: 10.12034/j.issn.1009-606X.224108
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    To investigate the corrosion resistance of SiC refractory materials in the sodium smelting process of vanadium titanium magnetite, the wettability and interface behavior between vanadium titanium magnetite sodium smelting slag and SiC refractory substrate were studied in this research. In the process of the research, the sodium smelting slag of vanadium titanium magnetite and SiC refractory substrate were used as the experimental materials, a high-temperature wetting experimental device was used to investigate the influence of Na2O content changes on the wetting and interfacial behavior between the slag and the SiC refractory by the sessile drop method. The results indicated that as the Na2O content in the slag increased, the melting point of the slag significantly decreased, improving the wetting and spreading on the SiC substrate. At the same time and temperature, the contact angle between the molten slag and the SiC refractory substrate decreased with the increase of Na2O content. The interfacial energy between the refractory substrates was also reduced, leading to a tight bond between the slag and the SiC refractory substrate and easier wetting between the two phases. The formation of numerous sodium-containing low-melting compounds in the slag reduced its viscosity and enhanced its fluidity, thereby intensifying the diffusion of molecules or ions within the slag, which accelerated the oxidation of the SiC refractory material. As the Na2O content increased from 20.00wt% to 40.00wt%, the interaction between the slag and the substrate transitioned from a separated to an adhesive state, eventually forming a uniform reaction layer. The SiC refractory material exhibited good corrosion resistance to slag with 20.00wt% Na2O content, but this resistance gradually decreased as the Na2O content increased. These research results may provide some theoretical basis for the study of slag resistance in refractory materials during the sodium smelting process of vanadium titanium magnetite.
    The role and mechanism of dihydromyricetin in the flotation of chalcopyrite and galena
    Shuang QIN Jianjun FANG Haiyang HE Zhilian QIU Liguo PENG Shiqin DONG
    The Chinese Journal of Process Engineering. 2024, 24(11):  1335-1343.  DOI: 10.12034/j.issn.1009-606X.224074
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    This study investigated the effect of dihydromyricetin on the flotation behavior of chalcopyrite and galena throught pure mineral flotation test, contact angle measurement, ultraviolet spectrophotometer and X-ray photoelectron spectroscopy analysis. At the same time, the mechanism of dihydromyricetin on the inhibition of galena was also studied. The research results indicate that the flotation index of single mineral is in good condition. When using 1.0×10-4 mol/L dihydromyricetin in the flotation test of artificial mixture, the grade and recovery rate of copper concentrate are 29.28wt% and 99.04%, respectively, and the grade and recovery rate of lead concentrate are 86.29wt% and 87.55%, respectively. The larger the contact angle on the mineral surface, the more hydrophobic and floatable of the mineral is. The contact angle measurement show that after adding dihydromyricetin, the contact angle of chalcopyrite decreases by 5.40°, while the contact angle of galena decreases by 13.78°, which significantly affects the wettability of galena surface. The adsorption capacity test results show that the galena has a higher affinity for dihydromyricetin than chalcopyrite. After treatment with dihydromyricetin, the adsorption capacity of galena on the mineral surface significantly decreases, while the adsorption capacity of chalcopyrite changes slightly. The difference in the adsorption amount of the collector further increases the floatability difference between the two. The XPS results show that the content of Pb(OH)2 increases significantly after dihydromyricetin treatment, from 11.72% to 24.73%, and the hydroxyl group of dihydromyricetin and the metal hydroxide oxidized on the surface of galena are adsorbed on the mineral surface through the interaction of Bronsted acid and alkali, which hinders the interaction between the collector and the mineral, what's more, this leads to two different flotation phenomena of chalcopyrite and galena.
    Effect of experimental conditions on the impurity content in Ni0.8Co0.1Mn0.1(OH)2 synthesized by co-precipitation
    Qianying HAN Li YANG Haoliang WANG Rizhi CHEN Jingcai CHENG Chao YANG
    The Chinese Journal of Process Engineering. 2024, 24(11):  1344-1353.  DOI: 10.12034/j.issn.1009-606X.224102
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    During the synthesis of precursor materials for ternary lithium battery cathodes via co-precipitation, the presence of impurities such as iron, aluminum, magnesium, copper, and sulfur can adversely affect the electrochemical performance of the final cathode materials. The existing studies are lack in mechanism analysis of the influence of coprecipitation conditions on the inclusion of impurities in precursor particles. The impurities in Ni0.8Co0.1Mn0.1(OH)2 synthesized via co-precipitation have been analyzed using multiple characterization methods. The impurities primarily consist of sodium, magnesium, calcium, iron, copper, zinc, aluminum, and sulfur, and may be distributed within the crystal lattice, interstitial sites, or on the surface of the precursor particles. The results indicate that the concentration of ammonia has a significant effect on the contents of iron, copper, zinc, and aluminum. The precursor synthesized under the condition of pH 11.7 is colloidal and has a larger specific surface area, which adsorbs the highest amounts of sodium and sulfur, being 28134.62 and 12898.50 μg/g, respectively. The variation in stirring speed has a certain effect on the distribution of sulfur content. Optimizing the process conditions of ternary precursor co-precipitation process is of great significance to control the impurity content in the precursor and improve the electrochemical performance and safety of the final ternary cathode material.
    Design and preparation of three-dimensional hollow porous Mn2O3 nanosphere for enhanced Zn2+ storage
    Shichang HAN Shuihua YU Hanfang ZHANG Zekai ZHANG Huaqiang CHU
    The Chinese Journal of Process Engineering. 2024, 24(11):  1354-1363.  DOI: 10.12034/j.issn.1009-606X.224052
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    Manganese sesquioxide (Mn2O3), as an cathode material for aqueous zinc ion batteries (AZIBs), has received extensive attention from researchers due to its excellent energy storage potential. However, its application is constrained by factors such as the volume expansion of the material and the poor reversibility caused by manganese dissolution. In order to overcome these limitations, Mn2O3 nanospheres with a unique three-dimensional hollow porous structure were successfully prepared in this study by the hydrothermal method and heat treatment process. This unique three-dimensional hollow porous structure endowed Mn2O3 with a larger specific surface area and superior ion diffusion channels, resulting in excellent zinc storage properties. The Mn-450-2h electrode materials showed a high discharge specific capacity up to 636 mAh/g at a current density of 0.1 A/g and remain at 330 mAh/g after 50 charge/discharge cycles. Meanwhile, the discharge specific capacity of the Mn-450-2h electrode material can be stabilized at 100 mAh/g after 500 cycles at a current density of 0.5 A/g. In addition, a detailed analysis of the electrochemical zinc storage mechanism revealed the relationship between the physicochemical properties and electrochemical performance of the obtained materials, which provides a new perspective and direction for the construction of advanced manganese-based oxide electrode materials.
    Antibacterial properties of graphite carbon nitride materials based on piezoelectric response
    Wenjun MA Xiaoze WANG Jingkun ZHANG Yunfa CHEN
    The Chinese Journal of Process Engineering. 2024, 24(11):  1364-1374.  DOI: 10.12034/j.issn.1009-606X.224098
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    The piezoelectric effect in asymmetric semiconductors has been shown to be an effective strategy to reduce carrier recombination in photocatalysis. This means that mechanical energy-induced piezoelectricity can act as a flexible automatic valve to regulate the transfer and separation of light-induced carriers in the bulk phase and on photocatalyst surfaces. Two-dimensional graphitic carbon nitride (g-C3N4) has a non-centrally symmetrical pore structure and uniform pore distribution, so it has piezoelectric response characteristics, and has received extensive attention in the field of antibacterial applications. The molecular engineering of g-C3N4 can change the piezoelectric polarization of g-C3N4 to a certain extent, which will enhance the role of the piezoelectric effect in the antimicrobial process of g-C3N4. Therefore, in this work, two-dimensional g-C3N4 materials containing hydroxyl and carboxyl oxygen-containing functional groups were synthesized by KOH with high temperature alkali treatment and KSCN calcination acid leaching, respectively. The results show that g-C3N4 still exhibits a graphite structure after the modification of the agglomeration of oxygen. The piezoresponse force microscopy (PFM) confirms the non-uniform surface potential distribution of these composite materials, and significantly improves the piezoelectric performance after the carboxyl branching. Scanning electron microscopy (SEM) show that the composite material causes a certain physical damage to the bacteria. The active oxygen (ROS) test shows that the induction effect is introduced to promote the separation of the electron-acupuncture point, which enhances the ability of the materials to capture electrons in the piezoelectric field. As a result, the captured electrons are restarted around the adsorption oxygen, generating a large amount of superoxide anion, and inducing a change in the active oxygen level within the bacteria to change, causing bacterial death. In vitro, the oxidation-induced oxidation stimulation combined with physical cutting of the antibacterial activity to Escherichia coli (E. coli) is 5log (99.999%), and the antibacterial activity against Staphylococcus aureus (S. aureus) is 4log (99.99%), which is higher than the pure g-C3N4. These findings emphasize the antibacterial potential of the carboxylated g-C3N4 material, which may be a promising candidate as an antibacterial material in the light-restricted environment.