The Chinese Journal of Process Engineering

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Chin. J. Process Eng.. 2018, 18(3): 0.

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Model of Particle Deposition and Adhesion on Blade Surface of Flue Gas Turbine

Shuaifu CHEN Jianjun WANG Youhai JIN

Chin. J. Process Eng.. 2018, 18(3): 447-453. DOI: 10.12034/j.issn.1009-606X.217291

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A model of catalyst particles deposition and adhesion on the blade surface of flue gas turbine was promoted, treating the collision between catalyst particles and the blade surface as elastic-perfectly plastic spheres collision with rigid plane, which was used as the basis of numerical calculations. The results showed that the location of catalyst particles deposition and adhesion on the blade surface of flue gas turbine predicted by the model was consistent with the location of deposition and adhesion found in actual conditions, proving that the model can predict the occurrence location of the catalyst particles deposition and adhesion effectively.

Flame Spread Characteristics over Building Decoration Material of PMMA with Different Placed Angles

Xinjie HUANG Wei LIU Gongjian CHEN Chunjie WANG Gang TANG Hao ZHANG

Chin. J. Process Eng.. 2018, 18(3): 454-460. DOI: 10.12034/j.issn.1009-606X.217298

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In order to reveal the effect of placed angle on flame spread characteristics over polymethyl methacrylate (PMMA), a small-scale flame spread setup was established and then a series of flame spread experiments on PMMA samples with width 3 cm, thick 2 mm and different placed angles were carried out. The results showed that the pyrolysis zone and preheating zone length were largely influenced by placed angle through infrared image analysis. The average flame angle increased greatly when the placed angle changed from 15° to 30° and from ?60° to ?75° (for upward flame spread, the placed angle is positive, and for downward flame spread, the placed angle is negative). Meanwhile, for upward flame spread, the flame length decreased slowly and then increased with placed angle, however, for downward flame spread, the flame length decreased slightly with the absolute value of the placed angle. As for the upward flame spread, when the placed angle changed from 0° to 15°, the average flame spread speed will increase greatly. And for the downward flame spread, the average flame spread speed decreased slightly with the absolute value of the placed angle.

Simulation of Atomization Characteristics in High Efficient Spray Tower Nozzle of New OG System of Primary Dedusting System for Converter

Xiaoping HUANG Fuping QIAN Laiyong WANG Yongjun XIA Jia HU Deming SHI Yunlong HAN

Chin. J. Process Eng.. 2018, 18(3): 461-468. DOI: 10.12034/j.issn.1009-606X.217299

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The gas?liquid two-phase coupled flow of the atomization field in the nozzle of the high efficiency spray tower of new oxygen converter gas recovery (OG) system of primary dedusting system for converter was simulated by using the discrete phase model. The influences of the spray angle, the atomizer pressure, the atomizer mass flow rate and the horizontal distance between two nozzles on Sauter mean diameter (SMD) and the evaporation efficiency of the atomization field were analyzed. The results showed that with the increase of the spray angle, the coverage of the droplet in the atomization field was wider, the droplet residence time was longer, the evaporation efficiency of the droplets increased, and the SMD of the atomization field decreased. When the injection angle was greater than 60o, the SMD decreased slowly. With the spray pressure increased, the evaporation efficiency of the droplets increased, and the atomization field SMD decreased. When the pressure was greater than 1.0 MPa, the influence of the spray pressure on SMD was small. With the increase of jet mass flow rate, the evaporation efficiency of the droplets decreased, and the SMD of the atomization field increased. When the flow rate was less than 0.15 kg/s, the SMD had not much increase. The larger the horizontal distance between two nozzles, the wider the droplet distribution, but the horizontal distance had less impact on the atomization field SMD. Under certain conditions, when the nozzle distance was about 800 mm, the cross-sectional velocity distribution was more uniform.

Effect of Pore Distribution on Flow and Heat Transfer in Porous Media

Tingfang YU Aliang LIU Ying ZHANG Zhiqiang WANG Wenlin YE Jincong SUN

Chin. J. Process Eng.. 2018, 18(3): 469-476. DOI: 10.12034/j.issn.1009-606X.217320

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Sierpinski carpet was used as the model of porous media by changing the position of solid matrix in the model to study the effect of pore distribution on the transmission characteristics and heat transfer efficiency of porous media. The three pore distributions were distributed in a fractal primary solid matrix at the center (A), in the upper middle (B), and in the upper right (C). When the fluid flowed stably through the porous media model, the different pore distribution showed different flow and heat characteristics. The results showed that the pore distribution was an important factor affecting the transmission characteristics and heat transfer efficiency of porous media. The dimensionless permeability was expressed as k*C>k*B>k*A. Especially when the porosity of porous media was more than 0.8, the effect of pore distribution on porous media permeability was more obvious. When the fluid flows through porous media with different pore distributions, the area of the fluid?solid contacting surface at the same porosity is A>B>C, and the heat transfer effect shows that A is the best and the C is the worst. At the same time, the pore distribution affects the change of the dimension of the non-dimensional local entropy. The pore distribution influences the dimensionless local entropy generation, and the entropy generation caused by heat conduction represented by Be is the main entropy in the three kinds of pore distribution.

Comparison of Filtration Performance in Two Fixed Granular Beds with Different Granules

Shen YAN Guogang SUN Minshu ZHAN Zhongli JI

Chin. J. Process Eng.. 2018, 18(3): 477-483. DOI: 10.12034/j.issn.1009-606X.217324

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Similarities and differences of filtration performances of granules were investigated in two beds of ceramic balls and quartz sands. The results showed that the filtration performances of two kinds of granules with similar mean diameter and steady-state filtration pressure drop except for shape and surface condition were basically identical. The filtration efficiency increased at first and then decreased with increasing dust mass deposition (?m), while the deviation degree of pressure drop with steady-state pressure drop (correcting factor, G) presented an increasing trend. The filtration efficiency and G decreased with increasing superficial gas velocity for the same ?m, but G at high superficial gas velocity would be close to G at low superficial gas velocity during the later period of filtration operation. Although there was no significant change in total filtration efficiency, the grade filtration efficiency of dust particles bigger than 0.7 ?m increased when inlet dust concentration increased. At the same time, G under the condition of higher inlet dust concentration was larger. The most penetrant dust particle size was in the range of 0.35~0.6 μm for these two kinds of granules. However, certain differences also existed in filtration performances of these two kinds of granules because of different shape and surface condition. Other conditions being equal, the total and grade filtration efficiency of quartz sands were higher than ceramic balls, and the G of quartz sands was also larger. In addition, the filtration efficiency of quartz sands varying with ?m changed very little with increasing of inlet dust concentration.

Residence Time Distribution of Particles in Fluidized Bed with Spiral Internal

Yiwei DU Xin WU Daojie LIU Junhui LI

Chin. J. Process Eng.. 2018, 18(3): 484-490. DOI: 10.12034/j.issn.1009-606X.217329

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Effects of spiral internal, solid feeding rate, fluidized gas velocity, particle size and bed height on the particle residence time distribution were investigated in a cold bubbling fluidized bed using the tracer technique. The results showed that the dimensionless variance of particle residence time reduced from 0.558 without spiral internal to 0.085 with a spiral internal, indicating that the spiral internal helped restrain the back mixing of particles and made the flow approach the plug flow. When the solid feeding rate was doubled, the residence time of particles decreased by approximately 50% and the flow was closer to plug flow. As the increased bed height caused severe back mixing, both average residence time and dimensionless variance increased and the solid flow tended to be complete stirred flow. The average residence time of particles extended with the increasing of fluidized gas velocity. Particle size had a little effect on the residence time distribution under present experimental conditions.

Separation and Purification of Natural Gas Hydrate Slurry Mixture by Double Cone-Inner Cone Hydrocyclone

Hao CHEN Wenke WU Bin LV Jingwen CHEN Laiqiang FU Gang YIN

Chin. J. Process Eng.. 2018, 18(3): 491-495. DOI: 10.12034/j.issn.1009-606X.217343

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A double cone?inner cone hydrocyclone suitable for removing gas and sand in mixed slurry of natural gas hydrate was designed for the presence of natural gas in the mixed slurry of submarine natural gas hydrate. The effects of particle size, cone angle combination, inlet pressure on separation efficiency of solid particles and natural gas were studied. The results showed that under the conditions of the solid particle diameter 50?90 ?m, the natural gas bubble diameter 400?800 ?m and the inlet pressure 4.3?7.3 MPa, the optimum separation efficiency can be archived, the optimum cone angle combination was 10o–5o.

Optimization of Crude Tin Vacuum Distillation by Response Surface Methodology

Zhenghao PU Jibiao HAN Yifu LI Bin YANG Yongnian DAI

Chin. J. Process Eng.. 2018, 18(3): 496-502. DOI: 10.12034/j.issn.1009-606X.217301

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Effects of the distillation temperature, the holding time and raw materials mass on vacuum distillation of crude tin were studied by response surface methodology. The results showed that the distillation temperature and holding time had remarkable influences and raw materials mass had little influence on vacuum distillation. The impurities in crude tin were effectively removed at 1350~1400℃ for 40~60 min. After vacuum distillation crude tin of 97.4185% at 1400℃ for 60 min, tin was purified up to 99.8752% with 0.012% Pb, 0.045% Sb, 0.0005% Bi, 0.0005% As with no variation of Fe and Cu content, and the direct recovery rate of tin was 99.89%.

Desorption Behavior and Kinetics of Resorcinol from Activated Carbon in Rotating Packed Bed

Fang GUO Youzhi LIU Qiang GUO

Chin. J. Process Eng.. 2018, 18(3): 503-508. DOI: 10.12034/j.issn.1009-606X.217328

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The desorption behavior and kinetics of resorcinol from activated carbon in rotating packed bed were studied by the pseudo-second-order kinetic model, compared with that in the traditional fixed bed. The optimal operation conditions were determined with temperature of 20℃, high gravity factor of 32.63, pH value of 11, flow rate of 50 L/h, desorption agent ethanol of 40wt% and desorption time of 90 min. In these case, desorption rate of resorcinol reached 93.90%. Compared with the fixed bed, desorption rate increased about 58.54% under the same operating conditions in rotating packed bed. The high gravity technology was beneficial to desorption performance by enhancing the mass transfer from liquid phase to solid phase. The desorption rate constant increased with the increased of flow rate and high gravity factor. In addition, the desorption rate constant improved from 13.27×10?3 g/(mg?min) with ultrapure water as desorption agent to 25.48×10?3 g/(mg?min) with ethanol as desorption agent.

Low-temperature Selective Catalytic Reduction of NOx over Ce-modified Fe2O3/AC Catalysts

Shoulai YIN Baozhong ZHU Yunlan SUN Zhaohui ZI Cheng CHEN Guobo LI Tianyu XU

Chin. J. Process Eng.. 2018, 18(3): 509-516. DOI: 10.12034/j.issn.1009-606X.217360

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A series of Fe2O3/AC and Ce?Fe2O3/AC catalysts with activated coke as support, iron and cerium as active ingredients were prepared by impregnation method. The influences of iron and cerium concentrations on the denitrification performance of the Fe2O3/AC catalyst at low temperature were investigated and these catalysts were characterized. The results showed that the Fe2O3/AC catalyst with 6wt% Fe had the best NOx conversion rate of 93.9% at 240℃. The NOx conversion rate using Ce-modified Fe2O3/AC catalyst was obviously improved. When the mass ratio of Ce to Fe was 0.5:6, the NOx conversion rate using Ce?Fe2O3/AC catalyst was higher 5%?20% than that using Fe/AC catalyst with 6wt% Fe at 120~200℃, and it showed a good sulfur resistance. The NOx conversion rate stabilized at 94.1% when the 100?10?6 (vol) SO2 was introduced at 240℃. The γ-Fe2O3 uniformly dispersed on the surface of catalyst after Ce modification, surface-adsorbed oxygen Oα ratio increased and reducibility was good, improving the NOx conversion rate.

Arsenic Removal by Scorodite Synthesis Using Ozone Oxidation

Junya CAO Kailun ZHANG Yuanyuan LI Guangji ZHANG

Chin. J. Process Eng.. 2018, 18(3): 517-521. DOI: 10.12034/j.issn.1009-606X.217417

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The ozone generated by the ozone generator was used to oxidize lab made acidic arsenic-containing wastewater to synthesize scorodite at 95℃ for 7 h. The effects of oxidizing rate of Fe(II) and initial pH of the solution on the arsenic removal rate and the scorodite formation were studied. The results showed that increasing the oxidizing rate of Fe(II) and initial pH can enhanced As precipitation. With the ozone oxidation, 89.64% arsenic was removed from the solution at initial pH=2, and the scorodite has large particle size and good crystallization.

Mechanism and Reaction Kinetics of Acidic Oxidation Pretreatment of Arsenic and Sulfur-bearing Gold Concentrate

Yingqiang MA Qiuyue SHENG Wanzhong YIN Zhengxiu HONG Langfeng TANG

Chin. J. Process Eng.. 2018, 18(3): 522-529. DOI: 10.12034/j.issn.1009-606X.217288

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Gold leaching for a gold concentrate was difficult due to the fine disseminated grain sizes and large amounts of the gold mineral wrapped by pyrite and arsenopyrite. Some of tests regarding acidic oxidation pretreatment in the systems of HCl?H2O2 and the mechanism and reaction kinetic analysis were carried out. The results showed that under the conditions of dosage of HCl 0.7 mol/L, pulp contentation of 40 g/L, particle size of less than 48 μm accounted for more than 90%, stirring speed of 400 r/min, reaction temperature of 60℃, dosage of H2O2 0.5 mol/L, the dissolution rates of iron and arsenic were 45.9% and 99.6%, respectively, acidic oxidation pretreatment benefited the gold leaching. Under acidic conditions, pyrite and arsenopyrite in gold concentrate could be oxidized by H2O2, the process conforms to the shrinking core model (SCM), and the reaction velocity was controlled by the products layer diffusion.

Direct Reduction Kinetics of Carbon Bearing Briquettes of High-phosphorus Iron Ore

Zhen WANG Tiejun CHUN Dongsheng LI Chao NING Gutian MU Mengfei ZHU Hongming LONG

Chin. J. Process Eng.. 2018, 18(3): 530-536. DOI: 10.12034/j.issn.1009-606X.217289

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The reduction kinetics of carbon bearing briquettes of high-phosphorus iron ore under base condition (without adding Na2SO4 and waste plastics), adding 4% Na2SO4 and adding 4% Na2SO4 with waste plastics replacing 25% coke fines were carried out respectively. The results showed that the control process of carbon bearing briquettes under three conditions was gas diffusion. Compared with the base condition, the apparent activation energy of adding 4% Na2SO4 decreased from 204.92 kJ/mol to 158.81 kJ/mol. The addition of 4% Na2SO4 with waste plastics replacing 25% coke fines was also beneficial to the reduction reaction, and the activation energy reduced from 204.92 kJ/mol to 172.89 kJ/mol.

Effect of SiO2 on Preparation of Ferrotitanium Alloy from Ilmenite Concentrate by Electroreduction in CaCl2 Molten Salt

Ganghua AI1 Yixin HUA Cunying XU Teng WU Bo SU Yun WANG

Chin. J. Process Eng.. 2018, 18(3): 537-543. DOI: 10.12034/j.issn.1009-606X.217303

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The effect of SiO2 on preparation of ferrotitanium alloy from ilmenite concentrate by electroreduction in CaCl2 molten salt was investigated against electrolysis time and cell voltage. The results showed that the ferrotitanium alloy was prepared via electroreduction in CaCl2 molten salt at 900℃ with a cell voltage of 3.2 V for 2 h when the mixture of ilmenite concentrate and SiO2 with a molar ratio of Ti:Fe:Si=1.2:1:0.2 was served as cathode and the graphite rod as anode. The FeTi product prepared was porous in structure and uniform in particles size. The intermediates CaTiO3 and Fe?Ti?O were observed during the electroreduction of FeTiO3. The SiO2 added in the cathode was preferentially reduced to Si, which could in turn participate in the reduction of CaTiO3 and other intermediates. The theoretical potentials for the formation of FeTi alloy from the intermediates would be reduced. Therefore, addition of a suitable amount of SiO2 into the cathode could accelerate the electroreduction rate for the preparation of ferrotitanium from ilmenite concentrate.

Effect of Surfactant HLB Value on the Dispersion Stability of Carbon Black Paste

Pan ZHOU Shoujun LIU Ruidong ZHANG Xinyi ZHANG Hongliang DIAO

Chin. J. Process Eng.. 2018, 18(3): 544-550. DOI: 10.12034/j.issn.1009-606X.217307

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The influences of the hydrophilic hydrophobic equilibrium value (HLB) and the amount of surfactant on wettability, dispersivity and stability of carbon black in color paste were investigated. By means of equivalent wetting contact angle, wetting heat, constructing the dispersion function and stable function, setting up the ideal model and so on, the paste stability of the color paste were evaluated. In the meantime, the stability mechanism was analyzed. The results showed that whether added single or complex surfactant, the HLB value was close to the carbon black HLB that good wetting, dispersing and stabilizing effect can be achieved. The dispersion stability of using complex surfactant was better than using single surfactant. In addition, adding anionic and nonionic surfactants had a better dispersion than adding non-ionic and nonionic surfactant. When the amount of surfactant achieved to 5.0wt%, the dispersion stability of the system was the best. The theories of adsorption layer and binding force can explain the phenomenon of the best addition and the best HLB value preferably.

Effect of Furnace Height on Performance of Walking-beam Reheating Furnace

Hao LI Fangqin DAI Cuijiao DING Yue GUO

Chin. J. Process Eng.. 2018, 18(3): 551-556. DOI: 10.12034/j.issn.1009-606X.217309

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Based on energy balance, energy-balance equations for gas volume zones, furnace surface zones and slab surface zones were set up by radiation zonal method, by the slab surface heat flow and internal thermal equations coupling solution. And the temperature profiles of gas volume zones and furnace surface zones were obtained by using the main variable correction method, the slabs temperature profiles by finite difference method. The correctness of the model was verified by comparing the slab temperature with the actual situation. The influence of the height of the upper furnace on the temperature field and the exhaust gas temperature of the slab were analyzed. The results showed that for the preheating section height of 0.5~0.9 m, with the height of each increase of 0.2 m, the upper surface temperature before the slab released increased by about 2.8℃, the exhaust temperature decreased by about 10℃. For the first heating section of height of 0.9~1.9 m, with the height of each increase of 0.2 m, the upper surface temperature before the slab released increased by about 2.5℃, the average exhaust gas temperature decreased by 8.5℃. The influence of the height on the temperature of the second heating section and the soaking section were not significant. It can be seen that it was reasonable to determine the height of the preheating section and the heating section to facilitate the heating of the slab and fuel consumption saving.

Measurement data and correlation of liquid-liquid equilibria for aqueous two-phase systems of HPP-Na2SO3-H2O

Zhengzhi ZHENG Yating LIU Peng CUI

Chin. J. Process Eng.. 2018, 18(3): 557-562. DOI: 10.12034/j.issn.1009-606X.217312

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The binodal and liquid?liquid equilibrium data of the 1,4-bis-(2-hydroxypropyl)-piperazine (HPP)–Na2SO3–H2O system at different temperatures were determined by cloud point method and phase component analysis method respectively. The binodal data were fitted by polynomial equation, empirical equations and effective excluded volume theory models respectively and the liquid?liquid equilibrium data were fitted by NRTL model. The results showed that empirical equations can provide better correlations for the binodal data than the polynomial equation and the effective excluded volume theory ones, and the NRTL model was suitable for the liquid?liquid equilibrium relationship of HPP–Na2SO3–H2O. Except the effective excluded volume theory model neglecting volume fraction f213, the parameters of equations and models were consistent with the actual calculation and engineering application requirements.

Thermal Conductivity of Carbon Nanotubes-Expanded Graphite/Epoxy Resin Composite

Yanjie LIU Jiangyin LU Ling LI Xiaofeng WU Yanbin CUI

Chin. J. Process Eng.. 2018, 18(3): 563-569. DOI: 10.12034/j.issn.1009-606X.217325

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Multi-walled carbon nanotubes (MWCNTs) and expanded graphite were added into epoxy resin to improve the thermal conductivity. The results indicated that the maximum thermal conductivity of composite was 0.3448 W/(m?K) by adding 0.5wt% MWCNTs, which was improved by 30% than epoxy resin. When 0.75wt% MWCNTs-COOH was added into epoxy resin, the maximum thermal conductivity of composite was 0.3813 W/(m?K), which was improved by 40% than epoxy resin. The thermal conductivity of epoxy resin could reach up to 0.4039 W/(m?K) by adding hybrid filler (MWCNTs-COOH and expanded graphite). A thermally conductive network was formed in epoxy resin when MWCNTs-COOH and expanded graphite were added into epoxy resin and the thermal conductivity of polymer could be further improved.

Preparation of Ca-Mg-Al-Fe Layered Double Hydroxides Using Steelmaking Slag as Raw Material and Its Adsorption to Methyl Orange

Chenye WANG Yan CHEN Zhancheng GUO Huiquan LI?

Chin. J. Process Eng.. 2018, 18(3): 570-574. DOI: 10.12034/j.issn.1009-606X.217335

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Ca?Mg?Al?Fe layered double hydroxides (LDHs) was synthesized via coprecipitation using steelmaking slag as raw material. The LDHs was characterized, and its absorption property to methyl orange was also studied. The results showed that the LDHs presented well-defined crystal structure and shape. The absorption process fitted Langmuir isotherm absorption model well, and the absorption kinetics followed a pseudo-second order kinetic model.

Analysis of Energy Balance during Biomass Torrefaction

Yangtian YE Honghong CHEN Ping LU

Chin. J. Process Eng.. 2018, 18(3): 575-581. DOI: 10.12034/j.issn.1009-606X.217337

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Calculation method of energy balance during biomass torrefaction was established based on the analysis of biomass torrefaction process. According to the results of polar branch (PB) torrefaction in a fixed bed reactor, the effect of torrefaction temperature and holding time on characteristics of torrefied products (PB biochar, liquid product and gaseous product), heat requirement and energy distribution during torrefaction were studied. The energy balance of PB torrefaction was also discussed. The results indicated that torrefaction temperature was a key influence factor on biochar mass yield, heating value and energy distribution. The mass yield of PB biochar decreased significantly and mass yields of liquid and gaseous products increased gradually with increasing torrefaction temperature. At the same time, the heating values of PB biochar and gaseous product increased, and the heating value of liquid product had no remarkable change correspondingly. The energy of PB biochar was significant higher than that of liquid and gaseous products. The energy balance ratio of PB torrefaction showed a tendency of increase first and then to be stable with increasing torrefaction temperature. 64.0% of biochar mass yield can be obtained through PB torrefaction at the temperature of 225℃ and the holding time of 30 min, and the relevant energy balance ratio was 2.5. At this condition, the heat produced from combustion of gaseous and liquid products could completely meet the requirement of energy self-supported during PB torrefaction.

Preparation of Low-silicon Aluminum Alloy from High-silicon Aluminum Alloy Melts by Electromagnetic Separation Process

Yufeng ZHANG Guoqiang LV Wenhui MA Yun LEI Yunfei HE Guangjie XIE

Chin. J. Process Eng.. 2018, 18(3): 582-589. DOI: 10.12034/j.issn.1009-606X.217340

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The effects of current frequency, pull-down velocity, holding temperature and crucible materials on the separation efficiency of Al?Si alloy with 45wt% Al were studied which the impurity elements were not considered. The results showed that the mass ratio of silicon to aluminum reduced 0.0939 by using graphite crucible as the container under the conditions of current frequency of 3 kHz, holding-temperature of 1000℃ and pull-down velocity of 10 ?m/s. Holding-temperature had the biggest effect on the removal of silicon in the alloy, under the same conditions, the mass ratio of Si to Al in alloy was 0.11439 at 1500℃. The low frequency alternating current strengthens the electromagnetic stirring to enhance the mass transfer. Reducing the pull-down velocity had an effect on reducing the silicon content in the alloy and can make the separation interface more flat.

Application of Fault Classification Method Based on VAE-DBN in Chemical Process

Xiang ZHANG Zhe CUI Yuxi DONG Wende TIAN

Chin. J. Process Eng.. 2018, 18(3): 590-594. DOI: 10.12034/j.issn.1009-606X.217345

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To extract the fault feature from a large quantity of high-dimensional data, a variational auto-encoder (VAE) and deep belief network (DBN) combined fault diagnosis method was proposed for chemical process. In the encoding process of VAE, constraints were added to the latent variable space Z, and the backward propagation training was carried out by the re-parameterization method. The latent variables corresponding to different faults could be learned without supervision. Subsequently, the latent variable features learned by VAE were used as input features of the DBN classification model to diagnose the faults. The results showed that VAE could extract more abstract and effective features from the original data, and VAE?DBN had excellent performance in classification accuracy.

Influence Mechanism of Al3+ from Recycled Water of Mineral Processing on Floatability of Molybdenite

Hui LI Tingshu HE Jianping JIN Chonghui ZHANG Zhen WANG Hang YUAN

Chin. J. Process Eng.. 2018, 18(3): 595-599. DOI: 10.12034/j.issn.1009-606X.217347

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The influences of Al3+ from recycled water of mineral processing on molybdenite floatability and its mechanism of action were systematically studied, through flotation tests of molybdenite, measurement of electric potential, Al3+ solution chemical analysis, and X-ray photoelectron spectroscopy (XPS). The results indicated that Al3+ can worsen the flotation index of the molybdenite and lead to a significant deviation of its surface potential, indicating that there is lots of Al3+ adsorption on the surface of molybdenite. Al3+ in solution mainly exists in the forms of aluminum ion, hydroxy aluminum ion and aluminum hydroxide. Hydroxy aluminium ion, aluminum hydroxide precipitation with a strong polarity, can adsorb on lively “edge” of molybdenite, and the aluminum ions can produce chemical reaction with MoO42? because of molybdenite “edge” oxide generated. With the reason of the area of “edge” much smaller than that of “face”, the aluminum ions are mainly adsorbed on the “edge”, so the content of aluminum is not much, but the aluminum ions can adsorb on the surface of molybdenite, indeed both physical adsorption and chemical adsorption.

Leaching Process of Roasting Clinker with Vanadium Slag

Fuhuai LUO Nianxin FU Lin ZHANG Wuhan LIU Ganfeng TU

Chin. J. Process Eng.. 2018, 18(3): 600-604. DOI: 10.12034/j.issn.1009-606X.217348

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对钒渣钙化焙烧后的熟料用硫酸浸出，分析了不同条件下焙烧的熟料对钒浸出渣物相、钒浸出率的影响及钒损失的原因. 结果表明，钒浸出渣的主要物相为不溶于酸的致密固溶体R2O3和铁板钛矿Fe2TiO5，其间混有硅酸盐辉石相和少量钒酸盐相. 钒浸出率随焙烧温度、焙烧时间和钙钒质量比增加呈先增加后减小的趋势. 硅酸盐种类及其对钒酸盐的影响、尖晶石氧化不完全、R2O3相中固溶V和钒青铜及正、焦、偏钒酸钙最佳浸出酸度不同是造成钒损失的原因.

High Voltage Electrochemical Properties of FEC/PC/DMC Electrolyte with LiDFOB

Liang ZHANG Lan ZHANG Shimou CHEN Yibo WANG Xingmei LV

Chin. J. Process Eng.. 2018, 18(3): 605-611. DOI: 10.12034/j.issn.1009-606X.217371

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Fluoroethylene carbonate (FEC) and lithium oxalyldifluoroborate (LiDFOB) were regarded as the excellent solvent and additive for high voltage lithium-ion battery electrolyte due to their excellent electrochemical stability and protection film forming ability. LiDFOB and Tris(trimethylsilyl)borate (TMSB) were chosen as additive of 1 mol/L LiPF6 FEC/Propylene carbonate (PC)/Dimethyl carbonate (DMC) electrolyte for LiNi0.5Mn1.5O4 battery. The electrochemical performances of the electrolytes LiDFOB and additive TMSB have been systematically investigated. The differences between these two electrolytes were also demonstrated by SEM and cyclic voltammetry. The results showed that decomposed potential of the electrolyte with LiDFOB+additive TMSB can be enhanced to 5.5 V (vs. Li/Li+) and the Al current collector could be effectively passivated. The initial discharge capacity of Li/LiNi0.5Mn1.5O4 half cell operated with electrolyte with LiDFOB and TMSB was 126.8 mA?h/g, the coulomb efficiency was 99%. After 200 cycles, the discharge specific capacity was 108.2 mA?h/g, and it added retained 85.3% of its initial discharge capacity, while it is only 60.7% after 85 cycles for the one operated with the same basic electrolyte but without additive.

High Efficient Recovery of Oxidized Lead?Zinc Minerals from a Multi-metal Ore in the Eastern Region of Yunnan Province

Jinpeng CAI Kaiwei SONG Peilun SHEN Jianmin LI Ruizeng LIU Dianwen LIU?

Chin. J. Process Eng.. 2018, 18(3): 612-617. DOI: 10.12034/j.issn.1009-606X.217409

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A selective flotation process of lead minerals was developed to a lead?zinc oxide ore in the eastern region of Yunnan Province, China. The flotation process with two roughing, one cleaning and one scavenging was adopted in the recovery of lead and zinc. The results showed that the valuable elements in the ore were lead, zinc and silver. The main minerals of lead cerussite and anglesite, zinc were smithsonite and hemimorphite respectively, and silver minerals associated mostly with lead minerals. The dissemination of valuable minerals was relatively fine. The lead concentrate grade was 61.45% with Pb recovery rate 86.41%, the grade of Ag was 451.58 g/t and the recovery rate was 66.73%, containing 3.68% Zn. The zinc concentrate grade was 42.32% and the recovery of Zn was 90.63%, containing 1.39% Pb. The amphoteric collector R144 showed better performance both in collecting ability and selectivity to zinc minerals than that of dodecylamine, octadecylamine and combined amines.

Effects of Ce Addition on Microstructure and Properties of Sn-58Bi Solder Alloy

Jinfa LIAO Liukui GONG Dawei YUAN Dongdong WANG Huiming CHEN?

Chin. J. Process Eng.. 2018, 18(3): 618-623. DOI: 10.12034/j.issn.1009-606X.217412

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Sn?58Bi alloys with different Ce contents were fabricated by vacuum smelting and casting. The microstructure, phase composition and properties of the alloys were investigated. The influence of Ce on shear strength of Sn?58Bi/Cu solder joints was emphasized. The results showed that the Sn?58Bi eutectic microstructure were refined, and the melting point and melting range were less affected by Ce addition. The wettability of Sn?58Bi alloys reduced when the Ce content increased, the shear strength was maximum when the content of Ce was 0.1wt%.

High Cell Density Fermentation of Chlorella Based on Kinetics Model

Youcai ZHOU Yongjin HE Linsheng LI Mingzi WANG Bilian CHEN Xing ZHENG

Chin. J. Process Eng.. 2018, 18(3): 624-631. DOI: 10.12034/j.issn.1009-606X.217318

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The kinetic model of batch fermentation of Chlorella sp. MBFJNU-17 in a 50 L fermenter was built, fed-batch strategy for high cell density cultivation was established. The application of carbon source was investigated. Furthermore, real-time quantitative PCR was used to determine the gene levels of key metabolic enzymes such as diaminopimelate isomerase (dapF), citrate synthase (CS) and glucose?6-phosphate dehydrogenase (G6PDH) in fed-batch fermentation. The results showed that the cell dry weight of Chlorella sp. MBFJNU-17 was 106.65 g/L, the average growth rate was 0.89 g/(L?h) and the yield of cell dry weight on glucose was 0.56 g/g, respectively, after fed-batch culture for 120 h. The gene levels of dapF, G6DPH and CS of Chlorella sp. MBFJNU-17 were strongly related with the concentrations of glucose and urea during the fermentation.

Optimization of Cellulase Assisted Extraction Conditions for Sulfated Polysaccharide (Ascophyllan) from Ascophyllum nodosum by Response Surface Methodology

Qingyun BAO Jingliuyi WEI Zedong JIANG Gang YU Gaoling HUANG Yanbing ZHU Anfeng XIAO Hui NI Qingbiao LI

Chin. J. Process Eng.. 2018, 18(3): 632-638. DOI: 10.12034/j.issn.1009-606X.217355

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In order to obtain the optimum parameters for the cellulase assisted extraction of ascophyllan from brown seaweed Ascophyllum nodosum, the effects of several factors including water to biomass ratio, cellulase concentration, enzymolysis temperature, and enzymolysis time on the extraction yield of ascophyllan were investigated by using a single factor experiment and further optimized by using Box-Behnken experiment and response surface methodology (RSM). The results revealed that the optimal parameters for ascophyllan extraction were ratio of water to biomass 30 mL/g, cellulase concentration 200 IU/mL, enzymolysis temperature 50℃, enzymolysis time 2.0 h. Under these conditions, the actual extraction yield of ascophyllan was 14.65%±0.73%, in keeping approach with the predicted value by RSM (14.75%). Therefore, it is feasible that utilized RSM to optimize the conditions of extracting ascophyllan with the assist of cellulase.

Process Characteristics on Replacement of Bulk-methane Hydrates with Liquid Cardon Dioxide

Fengqi ZHANG Guoxing CHEN Kaihua GUO Aohan DU

Chin. J. Process Eng.. 2018, 18(3): 639-645. DOI: 10.12034/j.issn.1009-606X.217304

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Second types of in situ replacement of methane hydrate by liquid carbon dioxide replacement were proposed and verified by experiments. Through visible hydrate reaction device and image equipment to intuitively record injecting CO2 and gas hydrate decomposition in situ hydrate, and maintain the bulk of hydrate stable structure, proved the feasibility of hydrate decomposition and generation in second types of in situ replacement process at the same time. By controlling the pressure properly, the CH4 replacement process in the four phase zone (Hydrate?Water?Liquid?Vapor) of the CO2?CH4 mixed hydrate was realized, and the rich CH4 gas production was obtained. The CH4 gas production characteristics and the replacement rate of CO2 to CH4 hydrate were analyzed by gas chromatography and gas production measurement. The results showed that lower pressure was favorable for obtaining better replacement effect, compared with 5 MPa, the gas production increased by 14.6% and the methane hydrate replacement rate increased by 13.7% at 4.5 MPa.

Catalytic Wet Peroxide Oxidation of Methylene Blue Solution Using Fe-5A

Jian LIU Yanxiang WANG Gang PENG Huiping ZHANG

Chin. J. Process Eng.. 2018, 18(3): 646-651. DOI: 10.12034/j.issn.1009-606X.217321

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Fe?5A catalyst was prepared by wet impregnation method using Fe(NO3)3?9H2O and column 5A zeolite as raw materials. Batch experiments using Fe?5A as catalysts were conducted to investigate the effects of pH and temperature on methylene blue conversion. In addition, the effects of catalysts filling amount, feed flow rate, temperature and inlet methylene blue concentration on the of methylene blue degradation performance using Fe?5A catalyst in a continuous fixed bed reactor were studied. The results showed that the conversion rate was 95.9% at 20 min when the inlet methylene blue concentration was 50 mg/L, temperature was 70℃ and pH was 2. The conversion of methylene blue decreased with the decrease of temperature or the increase of flow rate during the fixed bed reaction. The change of methylene blue conversion rate and chemical oxygen demand (COD) conversion rate were very small as the increase of inlet methylene blue concentration. The conversion rates of methylene blue and COD were above 98% and 82%, respectively, and iron leaching concentration was below 3.5 mg/L under the conditions of initial concentration of methylene blue 50?300 mg/L, temperature of 70℃, pH of 2, feed flow rate of 4 mL/min, and Fe?5A catalyst filling amount of 1.25 g when the fixed bed was running continuously for 5 h. The methylene blue (50 mg/L) conversion rate was only 73.3% in the fixed bed of 2.5 g 5A zeolite at the same experimental conditions.

Dehydrogenation Performance and Reaction Kinetics of Isopropanol in Liquid Film Reactor

Shikun LI Min XU Jun CAI Xianfang YUE Xiulan HUAI

Chin. J. Process Eng.. 2018, 18(3): 652-656. DOI: 10.12034/j.issn.1009-606X.217333

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Effects of the feed rate, the amount of catalyst and the reaction temperature on the multiphase dehydrogenation reaction of isopropanol in a liquid film reactor with the amorphous alloy Raney nickel as catalyst were studied. The reaction kinetics was researched. The results showed that the effect of temperature was the most significant factor. Compared with the liquid phase dehydrogenation of the stirred tank, this reaction mode effectively improved the hydrogen production rate. The kinetic of Langmuir?Hinshelwood was obtained which agreed well with the experimental results.

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