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    The Chinese Journal of Process Engineering 2013 Vol.13
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    The Effects of Oxidative Pretreatment of Zinc-containing Dust on Contents of Iron and Manganese in Ammoniacal Leaching Solution and Production of Zinc Oxide
    WANG Wei-zhen CHEN Qi-yuan HU Hui-ping TAN Li-ming CHEN Hui-huang
       2013, 13 (1): 0-0.  
    Abstract （653）      PDF （120KB）（206）       Save
    The zinc-containing dust was oxidatively pretreated with calcium hypochlorite, subsequently leached with ammonia/ammonium bicarbonate solution to obtain the ammoniacal leaching solution, and zinc oxide was produced by ammonia distillation of the ammoniacal leaching solution and subsequent calcination. The elements of iron and manganese could not be detected in ammoniacal leaching solution, and the extraction rate of zinc was 98.2% in ammoniacal leaching process. The zinc oxide content in the product is 99.5%(w), and the contents of iron and manganese in the product were 0.0028‰ and 0.00084‰(w), respectively. The analyses of the valence states of iron and manganese in the zinc-containing dust with and without pretreatment were performed by chemical analysis and XPS, and the possible oxidation mechanism of the oxidative pretreatment of the dust was discussed. It is concluded that Fe2+-oxide and Mn2+-oxide in the dust were oxidized to Fe3+-oxide and/or its hydrate and Mn4+-oxide and/or its hydrate by calcium hypochlorite during the oxidative pretreatment process, respectively.
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    Mass Transfer Characteristics of VOC Emission from Wood Furniture
    SONG Wei KONG Qing-yuan LI Hong-mei LI Qiang LI Ji-guang
       2013, 13 (1): 1-9.  
    Abstract （723）      PDF （382KB）（201）       Save
    A new fully analytical model was established for describing volatile organic compounds (VOC) emission from wood furniture, which comprehensively considers the mechanisms and resistances in mass transfer and can be used in unventilated and ventilated conditions. Then this model was analyzed to propose a new method for conveniently, rapidly and simultaneously measuring four significant mass transfer parameters of target VOC, emittable concentration C0, diffusion coefficient D, partition coefficient K and convection mass transfer coefficient h, using several emission cycles' mass transfer equilibrium and process concentrations of the same furniture in an unventilated chamber. In experiments under (23±0.5)℃ and relative humidity 45%±5%, this method was used to measure formaldehyde and total VOC (TVOC) mass transfer from a piece of furniture, for formaldehyde, C0=4994 mg/m3, D=4.05′10-10 m2/s, K=499 and h=1.4′10-3 m/s, for TVOC, C0=19939 mg/m3, D=2.12′10-10 m2/s, K=1001 and h=5.0′10-4 m/s, which obeys the common range and shows a coefficient of variation less than 0.5% between the present results and calculation based on a reference treatment method. The predicted results of emission concentration in the chamber at either unventilated or ventilated condition based on measured parameters and a numerical calculating model were coincident with corresponding experimental data, showing an average deviation less than 3.5% between them.
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    Effect of EMBr on Flow Field of Molten Steel in a Continuous Casting Mold and Its Surfacial Fluctuation Measurement
    JI Chuan-bo LI Jing-she ZHANG Tong-bo CHENG Ai-min TANG Hai-yan
       2013, 13 (1): 10-16.  
    Abstract （854）      PDF （1946KB）（207）       Save
    The computational model combined with nail dipping method was applied to study the effect of a local type electromagnetic brake (EMBr) on molten steel flow in a thin slab continuous casting mold. The surface flow velocity and meniscus fluctuation were analyzed at different locations of magnetic field and strength. The computational results showed that the magnetic force suppressed the high velocity exit from the nozzle ports and decreased the impingement to mold narrow face and slag entrapment. The maximum surface velocity decreased from 0.85 m/s without EMBr to 0.5 and 0.16 m/s when the EMBr current increased from 180 to 274 A. The nail dipping measurement was economic and effective for monitoring the surface velocity. Furthermore, the EMBr current intensity could be controlled to ~260 A, which achieves to stabilize the fluid flow in the mold and thereby minimize casting defects of billets.
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    Diffusion Behavior of Carbon Atoms in Bainite of SCM435 Steel
    XU Dong JI Cheng TANG Zheng-you ZHU Miao-yong
       2013, 13 (1): 17-22.  
    Abstract （797）      PDF （713KB）（378）       Save
    In order to describe carbon atoms of diffusion behavior of bainite, two-dimensional diffusion mathematical model of SCM435 steel was established, and diffusion coefficient and activation energy of SCM435 steel were calculated based on the measured results. On this basis, the carbon diffusion behavior under different boundary conditions was sequentially obtained. The results showed that when temperature fell from 750 to 650℃ in bainite, diffusion behavior of carbon atoms of SCM435 steel was sharply reduced, and activation energy was about 407 kJ/mol. When cooling rate rised from 0.2 to 1℃/s from 750℃, the thickness of decarburization layer fell from 29 to 12.5 μm. When carbon content of carburizing atmosphere rised from 0.35% to 1 % as it had 100 μm decarburized layer, time fell from 21.5 to 8.5 min in order to eliminate the decarburization layer of metallographic sample, but its differential with the base of the carbon content of SCM435 steel gradually became higher along with more time.
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    Simulation of Thermostatic Water Mixing Valve Based on Fluent
    WU Fang-yi CHEN Hai-chu XIONG Gen-liang LIANG Fa-yun LIU Ling-teng ZHANG Ping
       2013, 13 (1): 23-27.  
    Abstract （815）      PDF （650KB）（262）       Save
    On the basis of design of thermostatic water mixing valve body model, using k-e two-equation turbulence model and CFD software Fluent the flow field of thermostatic valve was numerically simulated to obtain its distribution fields of pressure, temperature and velocity under the default of boundary conditions. The effects of hot and cold water inlet pressure, hydraulic diameter and temperature on the parameters of hot water outlet were analyzed. Finally, some experiments were carried out with the thermostatic valve prototype. The results show that the outlet flow rate will increase 10 times if the inlet pressure increases 100 times, and warm water outlet temperature will increase 1.3℃ if hot water inlet temperature increses 5℃. By comparing the results of simulation and experiment, both are basically consistent, which proves the correctness of the theoretical research, and lays the foundation for improving the design of thermostatic valves.
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    Influence of Horizontal Gas Distributor on Flow Field in COREX C3000 Shaft Furnace
    LIU Bing-nan LI Qiang LIU Hong-hua YU Ai-bing
       2013, 13 (1): 28-32.  
    Abstract （846）      PDF （585KB）（312）       Save
    A three-dimensional model was developed to simulate the gas flow distribution in COREX C3000 shaft furnace, and the effect of horizontal gas distributor (HGD) on gas distribution analyzed. The results showed that HGD increased the contact area between reduction gas and burden, so that the pressure difference was decreased significantly. HGD could also increase the gas velocity at the bustle pipe level, yet in the upper zone there was no obvious change of gas velocity, and the dead volume of gas flow in the lower zone was enlarged. HGD could commendably guide reduction gas into the central region of furnace, and had primary restraining effect on the volume of scurry gas. The volume fraction of scurry gas was decreased from 12.23% without HGD to 8.29% with HGD.
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    Non-aqueous Electrolysis Separation of Ti and Nb Bearing Inclusions in Ultra-pure Ferritic Stainless Steel and Analysis of Their Precipitation Behavior
    LIU He-li LI Guang-qiang LI YOng-jun ZHU Cheng-yi ZHANG Fan GUO Mu-xing CHEN Zhao-ping
       2013, 13 (1): 33-40.  
    Abstract （875）      PDF （1268KB）（355）       Save
    The inclusions and precipitates in Ti-Nb stabilized ultra-pure ferritic stainless steel were extracted without any damage by an electrolytic method in a non-aqueous solution. Field emission scanning electron microscope and energy dispersion spectrum were used to characterize morphology and composition of the inclusions. The results showed that most inclusions in higher Ti bearing ferritic stainless steel were Ti(C, N) in cubic structure or TiOx in dendritic structure. Inclusions in Ti-Nb double stabilized ferritic stainless steel were Ti(C, N) or Nb(C, N) in cubic structure where the TiOx+TiN was in the center and NbC in the edges of the composite inclusion. The inclusions in higher content Nb bearing ferritic stainless steel were NbC in a cross or dendritic structure. The inclusions extracted by a non-aqueous solution method provide basis for further reasonable smelting condition. The formation thermodynamics of TiN inclusions and timing of its precipitation were assessed. It is shown that when T=1873 K, [O]=0.003%, the critical value of titanium between Ti2O3 and Ti3O5 was 0.015, when [O]=0.005%, the critical value was 0.075. Ti2O3 existed in the liquid steel when [Ti]>0.075%. The core of TiOx+TiN dual phase inclusion was Ti2O3 in 445J1M ultra-pure ferritic stainless steel investigated. As temperature decreased, the segregation enriched of Ti and N occurred in the liquid steel, and TiN precipitated in solidification process of steel. With the reduction of nitrogen content in liquid steel, the timing of TiN precipitation could be put off.
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    Effect of Different Ion Exchange Resins on the Separation of L-Lac- and L-Glu- in Packed-bed Electrodialysis
    ZHANG Xiao-qin SHI SHAO-yuan ZHANG Jia-li CAO Hong-bin YANG Qiao-wen WANG Ru-nan
       2013, 13 (1): 41-47.  
    Abstract （893）      PDF （272KB）（187）       Save
    The effect of ion exchange resins with different ionic groups on the separation of L-Lac- and L-Glu- from fermentation wastewater was investigated by resin static adsorption, conventional electrodialysis and packed-bed electrodialysis. The results of static adsorption showed that the selective adsorption ratio of L-Lac- and L-Glu- adsorbed by basic resins (201′7 and WA30) was higher than that adsorbed by acid resins (001′1.1 and WK10). Compared with conventional electrodialysis, the migration quantity and separation ratio of L-Lac- and L-Glu- in the dilute compartments filled with 001′1.1 (strong acid resin) and WK10 (weak acid resin) were obviously higher, the maximal separation ratio could reach 22.22 when the 001′1.1 resin was filled in the dilute compartment of electrodialysis. However, when the basic resins (201′7 and WA30) were filled in the dilute compartment, both migration quantity and separation ratio were lower than those of conventional electrodialysis, the maximal separation ratios of L-Lac- and L-Glu- in the concentrated compartments were 5.74 and 8.28 separately. The migration quantities and separation ratio of L-Lac- and L-Glu- and energy consumption in different electrodialysis systems showed that 001′1.1 and WK10 resins filled in the dilute compartments were beneficial to the separation of L-Lac- and L-Glu- in packed-bed electrodialysis.
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    Basic Characterization and Recovery of Zinc by Acid Leaching of Steelmaking Dust from Sanming Iron and Steel Works
    XU Rui YANG Li-mei HUANG Song-tao XU Zheng
       2013, 13 (1): 48-54.  
    Abstract （751）      PDF （454KB）（158）       Save
    The basic characterization of steelmaking dust from Shanming Iron and Steel Works, such as chemical composition, granular size distribution, phase, surface topography and elemental distribution were analyzed by using chemical analysis, XRD, wet screening, microscopic examination and SEM-EDS. And through the acid leaching condition experiments, the effects of initial acid concentration, MnO2 addition, temperature and leaching time on the final pH value and filtering performance of leaching slurry, and the leaching rate of Zn, Fe and SiO2 were investigated. The results showed that in under the conditions of temperature 25℃, initial acid concentration 26.6 g/L, MnO2 addition 0.4 g, leaching after 120 min and slurry pH value in 3.5~3.7, the leaching rate of Zn reached up to 98%, but the leaching rates of Fe and SiO2 were 0.22% and 9% respectively, in the same time the filtering performance was good.
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    Experimental Study on Reduction of Stainless Steel-making Slag with CO and H2 at Intermediate-low Temperatures and Its Magnetic Separation
    LI Xin-lin LIU Xu-long LI Yuan-chao LI Qiu-ju HONG Xin
       2013, 13 (1): 55-60.  
    Abstract （829）      PDF （440KB）（301）       Save
    Pre-reduction of stainless steel-making slag was studied in a newly designed moving bed reactor with inclined tube and intermittent vibrators. The mixed gas of H2 and CO was used to simulate the exhaust gas produced and reformed in iron bath end reduction furnace to explore the possibility of preliminary separation of useful metals from stainless steel slag at intermediate and low temperatures by solid state reduction-magnetic separation. And the toxicity leaching experiment of stainless steel slag after treatment was carried out. The results show that higher productivity of magnetic product (10.53%), total iron grade (49.33%) and recovery rate of Fe (98.2%) can be obtained under the conditions of magnetic field strength at 200 mT, vibration intermittent 1:2, temperature 700~750℃ and CO/H2 volume ratio 1:4. The total amount of oxide impurities in the magnetic material after the treatment, such as CaO, MgO, Al2O3, SiO2, decreases significantly, from 80% to below 40%. And the tailings can meet the national emission standards.
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    Adsorption of Formaldehyde on the Surface of Environmental Test Chamber
    ZHANG Hao LIU Xiu-yu ZHU Qing-ming HUANG Xin-jie
       2013, 13 (1): 61-66.  
    Abstract （777）      PDF （241KB）（434）       Save
    The tracking experiments in an environmental test chamber for 25 d were carried out, including the stages of intrinsic formaldehyde concentration test, formaldehyde release, formaldehyde concentration attenuation, ventilation and formaldehyde release after it was adsorbed on the chamber surface. So it is necessary to investigate its releasing rules in order to improve the subsequent testing and propose guidance on the control of indoor pollution. The research results show that the formaldehyde concentration (C) in the chamber changes consistent with a logarithmic function: C=Alnt+B [when formaldehyde in the chamber releases, A>0, B>0, when formaldehyde attenuates, A<0, B>0, t is time (h)], where A is closely related to the relative equilibrium concentration established again after the adsorbed formaldehyde releases. Using suction type ventilation system for the chamber is in favor of residual formaldehyde reduction. After closing the ventilation system, the initial concentration of formaldehyde in the chamber increases quickly, and then a relatively low concentration of formaldehyde (0.3203 mg/m3) will be established again in balance. Adsorption degree of formaldehyde in the chamber is related to the substrate surface adsorption ratio q and hitting quantity of the adsorbate on the substrate surface U.
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    Electrochemical Behavior of Mo and W Ions in Acidic Solutions
    LI Jin-hui XIE Fang-hao QIAO Shan YANG You-ming
       2013, 13 (1): 73-77.  
    Abstract （965）      PDF （458KB）（976）       Save
    To increase the difference of electrochemical character of tungsten and molybdenum and separate them, molybdophosphate heteropoly acid and tungstophosphoric heteropoly acid solutions were prepared. Electrochemical behaviors of tungsten, molybdenum, molybdophosphate heteropoly acid and tungstophosphoric heteropoly acid in the acidic solution were studied, and some cyclic voltammetry diagrams were obtained. The results showed that the reduction potential of tungsten ion was higher than that of molybdenum ion, and the difference was less than 0.1 V, which means that tungsten could not be separated from molybdenum at this potential difference. Once tungsten and molybdenum reacted with phosphoric acid, the potential values of reduction peaks of molybdophosphate heteropoly acid and tungstophosphoric heteropoly acid were 0.401 and 0.1949 V, respectively, indicating that phosphoric acid increased the potential difference between tungsten and molybdenum.
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    Behaviors of Phosphorus in Smelting Reduction of High-phosphorus Iron Ore by Top-blown Enriched Oxygen
    WEI Ke QING Shan WANG Hua DENG Wen-long SHI Zhe
       2013, 13 (1): 78-82.  
    Abstract （751）      PDF （225KB）（277）       Save
    The iron-making process of high-phosphorus iron ore by oxygen top-blown smelting reduction was studied, the effects of slag basicity, molar ratio of carbon to oxygen, smelting temperature, oxygen blowing time (oxygen purity at 99%) and oxygen flow rate on phosphorus distribution in the process were investigated. The results showed that the phosphorus in the molten iron decreased with the increase of temperature. However, excessive temperature led to rephosphorization phenomenon. Dephosphorization rate was enhanced as rising of slag basicity, oxygen-enriched rate and time of oxygen application within a certain range. However, the dephosphorization rate declined with rising of molar ratio of carbon to oxygen. The optimum conditions were: 1550℃, molar ratio of carbon to oxygen 1.0, slag basicity 1.1, oxygen purging time 10 min, and oxygen flow rate of 250 L/h. Under these conditions, the phosphorus content in the molten iron was 0.068%, and the dephosphorization rate up to 92%. The resulting pig iron could be used in steel-making.
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    Study on Carbonation Reaction Kinetics of Ferrous Dust
    SHI Yan LIU Wen-hui HU Chang-qing
       2013, 13 (1): 83-87.  
    Abstract （797）      PDF （287KB）（164）       Save
    The carbonation reaction kinetics of ferrous dust was studied using thermal experiment for carbonate pellets. The un-reacted shrinking core model for carbonation reaction was set. The influence of reaction temperature on reaction kinetics parameters in the reaction control stage was analyzed. The results showed that raising reaction temperature was beneficial to transformation of carbonation pellets. While the temperature rising from 400℃ to 600℃, the conversion rate of CaO increased obviously, and reached the highest at 800℃. The total rate of carbonation reaction was controlled by internal diffusion and interfacial chemical reaction together. The reaction was controlled by chemical reaction in the initial reaction stage, the reaction rate was faster. Then the reaction was controlled by internal diffusion, the rate slowed down. At the temperatures of 200~800℃, its activation energy was 11.09 kJ/mol.
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    Effects of Fluxes on Fusibility Temperature of Briquette Ash
    CUI Guo-xing NIU Yu LIN Ming-sui
       2013, 13 (1): 88-93.  
    Abstract （898）      PDF （387KB）（437）       Save
    The additive of Fe2O3, MgO, CaO or solid water glass was blended with briquette ash at different proportions, respectively, as flux. The briquette ash fusibility temperature was studied under the condition of weak reduction atmosphere to lower its melting temperature. The results show that its fusibility temperature can be lowered by blending with alkaline oxides efficiently due to the fact that mineral matters react with alkaline oxides and produce low melting eutectic matters. The decrease of ash fusibility temperatures by adding the same amount (11%, w) of flux follows the sequence of MgO, CaO, solid water glass and Fe2O3, and the flow temperature is lowered by 22.0, 58.8, 81.2 and 91.9℃ respectively. Ternary phase diagram and XRD analysis were used to examine the effects of each flux on briquette ash fusibility temperature, verify the existence of mineral crystals, which is well coincided with the experiment results. The suitable adding quantity of CaO, solid water glass and Fe2O3 flux is 11%, 9% and 9% respectively, and CaO and solid water glass with both adhesive and accelerating gasification properties are found to be better fluxes of briquette ash.
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    Establishment and Application of Rist Operating Line for COREX Shaft Furnace
    DU Rui-ling WU Keng ZHAN Wen-long QU Jun-jie WU Xiao-hui WANG Meng
       2013, 13 (1): 94-98.  
    Abstract （891）      PDF （282KB）（494）       Save
    By using the Rist operating line theory of blast furnace, the energy consumption of shaft furnace in COREX process was studied with establishment of the operating line diagram. Then some limiting conditions on it were discussed. Through the simple calculation, an operating line diagram could be drawn to show the main physical and chemical reactions and energy utilization in the smelting process. It was convenient for producers and researchers to analyze the solution and improve the energy utilization. Furthermore, the operating line diagram was used to analyze the actual operation. The different compositions of charging gas and different gas utilization rates were discussed in the operating line diagram. It helps for the field technicians operating the shaft furnace, which could also lay a theoretical foundation to ensure the smooth shaft furnace operation.
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    Application of METSIM in Process Design of the Cleaner Chromate Production Using Sub-molten Salt
    LV Ye-qing ZHENG Shi-li WANG Shao-na DU Hao WANG Shao-na
       2013, 13 (1): 99-104.  
    Abstract （1145）      PDF （330KB）（465）       Save
    The cleaner chromate production process using sub-molten salt has been successfully simulated using METSIM in order to evaluate the mass balance, energy consumption, heat utilization efficiency, and other conditions necessitated for the process scaling up. Based on the simulation results, the mass and heat balances of each operation unit are obtained, providing valuable reference for the process design. Furthermore, the heat exchange network optimization using pinch technology is performed, enabling the reduction of the heat and cool energy consumption by 31.5% and 31.7%, respectively, and increase of the total energy efficiency by 11.0%.
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    Simulation and Optimization of Heat-integrated Pressure Swing Distillation for Separation of Methyl Acetate and Methanol
    YANG Jin-bei YU Mei-qiong ZHENG Zhi-gong QIU Ting
       2013, 13 (1): 105-110.  
    Abstract （1159）      PDF （330KB）（574）       Save
    Heat-integrated pressure swing distillation for separation of methyl acetate and methanol was investigated based on the pressure-sensitivity of azeotropic composition. The separation process was simulated by Aspen Plus software using the thermodynamic model NRTL with binary parameters between two components obtained by experimental data of vapor liquid equilibrium (VLE). The influences of number of theoretical plates, feeding location and reflux ratio on the separation efficiency and energy consumption of high-pressure distillation and atmospheric distillation columns were analyzed. The results show that they are efficiently separated by heat-integrated pressure swing distillation, and the optimal conditions are as follows: for high-pressure column, the pressure is 909 kPa, number of theoretical plates 32, feeding location at the 21th plate, and reflux ratio 4.2, the purity of methyl acetate reaches 99.8% at the bottom of tower; for atmospheric pressure column, the pressure is 101 kPa, number of theoretical plates 30, feeding location at the 20th plate, and reflux ratio 4.6, the purity of methanol reaches 99.0% at the bottom of tower. The heat-integrated pressure swing distillation can save energy by 45.8% compared with conventional one, and the former is also more attractive than the extractive distillation using water as an entrainer for separation of azeotropic system.
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    Optimal Design of Desalination and Power Cogeneration System Considering Different Salinity Feed Water
    WU Xian-li HU Yang-dong WU Lian-ying
       2013, 13 (1): 111-116.  
    Abstract （862）      PDF （254KB）（78）       Save
    Combined with the RO/MSF hybrid system and MSF-power cogeneration system, a new cogeneration system, including the coal-fired thermal power plant, MSF system and RO desalination system, is designed. A simplified superstructure model of the system is presented, which includes all the possible alternative configurations of the cogeneration system. Its production structure, using different salinity brackish water and seawater as feed water, is optimized. By solving the non-linear programming mathematical model of the cogeneration system with the objective of minimizing annual cost, an optimal cogeneration system can be obtained. The results show that at the low salinity (≤25000 mg/L), the optimal cogeneration structure is condensing power generation and one stage RO desalination; when the salinity>25000 mg/L, extraction condensing power generation and RO/MSF hybrid system is the optimal cogeneration system. The optimal cogeneration solution can reduce 23%~36% of the total annual cost.
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    Preparation of Novel Microcapsules Loading 5-Aminosalicylic Acid and Their Loading and Encapsulation Efficiency
    WU Qing-xi YAO Shan-jing
       2013, 13 (1): 117-123.  
    Abstract （793）      PDF （789KB）（378）       Save
    The microcapsules loading 5-aminosalicylic acid (5-ASA) were prepared with sodium cellulose sulfate (NaCS) and chitosan via orifice-polymerization method, and their average diameter was 1.89 mm. The effects of pH values of inner water and outer water phases, concentrations of NaCS and sodium polyphosphate (PPS) on the drug loading rate and encapsulation rate of microcapsules were mainly investigated. Box-Behnken method was used to design the experiments. The results showed that the pH value of inner water phase played a key role to the drug loading and encapsulation rates of microcapsules. The optimal conditions were pH values of inner and outer phases 4.25 and 6.0, concentrations of NaCS and PPS 14 and 5 g/L, the drug loading and encapsulation rates of microcapsules were 59.02% and 89.96%, respectively.
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    Fast Determination Method of Shikimic Acid Fermentation Liquor
    XU Xiao-juan WANG Zi-qiang DU Ying WANG Yun-shan; SU Zhi-guo
       2013, 13 (1): 124-128.  
    Abstract （964）      PDF （242KB）（597）       Save
    To control the production process of shikimic acid, the determination method of sucrose, shikimic acid and aromatic amino acids in fermentation liquor with HPLC was established. The analysis of above parameters was performed using a Hypersil APS-2 column (5 mm, 250 mm×4.6 mm), and an ultraviolet detector operated at 215 nm coupling a refractive index detector. The mobile phase consisted of phosphoric acid solution (pH 2.5) and acetonitrile at a 20:80 volume ratio, the elution was carried out at 30℃ and flow rate of 1.0 mL/min, and the injection volume was 10 mL. Under the conditions, the correlation coefficients of their linear regression equations reached above 0.9986. Their recovery rate was in a range from 95% to 105%, and relative standard deviation less than 2.0%.
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    Response of Genetically Engineered Synechocystis sp. to Salt Concentration for Production of Ethanol
    GE Ping-ping CHEN Lin LV Xue-feng LIU Tian-zhong;
       2013, 13 (1): 129-133.  
    Abstract （777）      PDF （235KB）（329）       Save
    The effects of NaCl concentration on ethanol production and biological response in genetically engineered cyanobacteria Synechocystis sp. PCC 6803 Syn-ZG25 were studied. The Syn-ZG25 grew in BG11 medium containing various NaCl concentrations, resulting in decreased growth rate, photosystem II activity and photosynthesis rate with increasing of salt concentration. For Syn-ZG25 growing in more than 10 g/L NaCl, dark respiration rate increased. With increasing of salt concentration, catabolism of endogenous carbohydrate increased, and ethanol excretion rate increased accordingly. The ethanol yield of Syn-ZG25 growing in 20 g/L NaCl was increased substantially by 91.8% to that in the control medium without NaCl. These results indicated that the Synechocystis sp. PCC 6803 Syn-ZG25 could regulate photosynthesis and respiration rates, presumably enhance catabolism of endogenous carbohydrate by enhancing activity of alcohol dehydrogenase, as the response to salt stress, and then resulting in the increase of ethanol yield.
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    Primary Separation of Phenazine-1-carboxylic Acid from Fermentation Broth
    ZHANG Lei-bin YU Qiu-sheng CHEN Zheng-xing
       2013, 13 (1): 134-138.  
    Abstract （782）      PDF （236KB）（336）       Save
    Antibiotic phenazine-1-carboxylic acid (PCA) was primarily separated from fermentation broth by a novel flocculation process. The solubility of PCA was firstly measured to prove rising with pH value. Based on a comparison of 9 types of flocculant, polyaluminum chloride was proved to be the best choice. The sedimentation rate of the flocs increased and PCA recovery rate severely increased after the broth was diluted. The factor of pH value had great effect on PCA recovery and purity. Temperature had obvious effect on filtration and PCA recovery rates, but not on its purity. The results of orthogonal experiments indicated that the best separation conditions were 4 times dilution, pH 8.5 and 30℃, under which PCA content of the product was 69.9%, and PCA recovery rate 91.3%.
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    Microstructure and Growth Kinetics of High Strength Low-alloy Steel with Hot-dipping of 55%Al-Zn-1.6%Si (≤0.1%Ti)
    PEI Jin-bang WU Guang-xin ZHANG Jie-yu WANG Bo
       2013, 13 (1): 139-145.  
    Abstract （855）      PDF （2039KB）（346）       Save
    Microstructure and growth kinetics of high strength low-alloy steel (H420) with hot-dipping 55%Al-Zn-1.6%Si (≤0.1%Ti) and 55%Al-Zn-1.6%Si were comparatively investigated. Optical microscope, SEM with energy dispersive spectrometer (EDS) and XRD were used to study the intermetallic layer thickness, microstructure, elemental distribution and phase composition. The results showed that the intermetallic layer was composed of Fe2Al5, Fe4Al13 and Fe-Al-Si intermetallic compound. A small amount of Fe-Al-Si-Mn solid solution existed in the border area between Fe2Al5 and Fe4Al13 phases, the reason was possibly that Mn diffused into the intermetallic layer. Meanwhile, the growth mechanism of intermetallic layer was characterized. The growth rate of intermetallic layer followed the parabolic law, Ti addition decreased the thickness of total intermetallic layer and Fe2Al5 layer about 3.25 and 1.83 mm. Ti-Al bond-energy was greater than Fe-Al one, Ti addition affected the interaction of Fe-Al bond, so the growth of intermetallic compound was restrained, and eventually reduced the intermetallic layer thickness.
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    Synthesis of MIL-101(Cr)-NH2 and Its Gas Adsorption Properties
    ZHOU Jing-jing LIU Kai-yu KONG Chun-long CHEN Liang
       2013, 13 (1): 146-151.  
    Abstract （1202）      PDF （806KB）（841）       Save
    The nano MIL-101(Cr)-NH2 material was synthesized by in situ hydrothermal method. The addition amount of NaOH in the reaction solution and its influence on the crystal structure, morphology and pore feature of MIL-101(Cr)-NH2 were investigated. Adsorption isotherms of CO2 and N2 at 273.4, 298 and 333 K on MIL-101(Cr)-NH2 were measured. And MIL-101(Cr)-NH2 was characterized. The results show that nano MIL-101(Cr)-NH2 particles with the size about 40 nm and the specific surface area as high as 2594 m2/g and pore volume 2.11 cm3/g could be synthesized at the optimal condition (NaOH:NH2BDC=4:2, molar ratio). The material has good CO2 adsorption capacity and selectivity, its CO2 adsorption capacity and ideal separation factor of CO2 over N2 could reach 25.9 mmol/g and 19.4 at 273.4 K, respectively.
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    Melting Characteristics of Microencapsulated Phase Change Material Slurry in a Circular Tube under Laminar Flow
    LU Jin-li HAN Ya-fang QIAN Fu-ping HAO Ying-li
       2013, 13 (1): 152-157.  
    Abstract （756）      PDF （465KB）（339）       Save
    Computational procedure based on two-fluid model was employed to study the melting characteristics of latent functionally thermal fluid in a circular tube with uniform heat flux and laminar flow, urea-formaldehyde resin and n-hexadecane were used as the shell and core materials, and deionized water as carrier fluid. The effects of Reynolds number (Re), concentration of microencapsulated phase change material particles and heat flux on the melting characteristics were examined. The results show that the non-melting, melting and melted regions coexist when the latent functionally thermal fluid flows in heating circular tube. With increasing of Re, the melting start and end points near the wall and center of circular tube move to outlet, and the melting region increases gradually. With increasing of particles volume concentration, the melting start and end points in the center of tube move to outlet. However, the melting start and end points near the wall are almost kept constant, and the melting region also extents to outlet. The bigger the wall heat flux, the closer to inlet the melting start and end points near the wall and center of circular tube, and the shorter the melting region.
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    Effects of Bath Annealing Process on Microstructure Properties of Ti-IF Steel
    FENG Yun-li QI Wen-jing ZHANG Dan GUO Shuai
       2013, 13 (1): 158-163.  
    Abstract （764）      PDF （1326KB）（336）       Save
    The effects of annealing temperature and holding time on the microstructure, properties and r-value of Ti-IF steel were studied, and the recrystallized texture of optimized Ti-IF steel was analyzed with optical microscope, servo tensile testing machine and X-ray diffraction. The results show that the time boundary from the partial pancake grains to most equiaxial grains in the evolution process is 8 h, the recrystallized equiaxial grains are uniform, the steel sample has r value at 2.347, tensile strength 312 MPa, extension rate 44.7% and density level of {111} texture 13.1 when the cold-rolling plate is annealed at 710℃ and holding 8 h. The Ti-IF steel can obtain good deep drawability in this process. The experimental research provides theoretical guidance for perfection of bath annealing process of Ti-IF steel sheet.
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    Study on Roasting of Carbon-containing Pellets from Blast Furnace Dust with Different Binders
    CAO Long DUAN Dong-ping HAN Hong-liang
       2013, 13 (1): 164-169.  
    Abstract （866）      PDF （291KB）（570）       Save
    Based on the physicochemical properties of blast furnace dust and binders, the compressive strength and falling strength of pellets are tested, and the effects of some sole and compound binders on the strength of blast furnace dust carbon-containing pellets are studied experimentally. The results show that the starch binders can improve the strength of pellets at low temperature. The compressive strength and falling strength of green balls are 72 N and 5.9 times, and those of dry pellets 58 N and 4.3 times, but the strength of roasted pellets is relatively low. The silicon-containing binders can improve the pellets at high temperature. The compressive strength of roasted pellets is 1764 N, but the strength of green balls and dry pellets is relatively low. Even though the strength of pellets can be raised, it still does not reach the objective. The compound binder of corn starch and sodium silicate is better than sole binders, the compressive strength and falling strength of green balls are 60 N and 5.5 times, those of dry pellets 55 N and 3.4 times, and roasted pellets 1958 N.
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    Synthesis of TiO2 Powder Doped with Rare Earth Elements by Sol-Gel Method and Its Gas Sensing Properties
    SONG Jin-ling ZHOU Chang-cai MOU Lian-wei GUO Guan-ming CAI Ying ZHANG Yin
       2013, 13 (1): 170-174.  
    Abstract （877）      PDF （356KB）（357）       Save
    TiO2 and TiO2 powders doped with different rare earth ions were prepared by sol-gel method, and their structures characterized by XRD. The results indicate that the prepared TiO2 powder has anatase structure, and rare earth ion doping can restrain the growth of TiO2 crystals. Moreover, its gas sensing properties towards formaldehyde, toluene and acetone gases were measured by a gas sensing instrument. The results show that the TiO2 doped with Ce (TiO2:Ce) exhibits better sensitivity and selectivity towards those gases, which may be attributed to the enhanced capability of adsorbed oxygen on the surface of Ce-doped TiO2. TEM analysis shows that the morphology of TiO2:Ce powder is particles with the diameters of 5~12 nm.
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    CO2 Emission in Iron and Steel Making Industry and Its Reduction Prospect
    XU Wen-qing LI Yin-jiao ZHU Ting-yu CAO Wan-jie
       2013, 13 (1): 175-180.  
    Abstract （988）      PDF （255KB）（470）       Save
    Measures of CO2 reduction are analyzed with actuality of CO2 emission from iron and steel making in China, such as, increasing the production of steel scrap-EAF process, improving the quality of iron, improving the ratio of non-fossil energy, employing low carbon technologies, enlarging scale of equipment and using energy-efficient technologies. There are many technologies of energy conservation and emission reduction in iron and steel industry such as coke dry quenching, coal moisture control, gas recycling, waste heat and energy recycling and low pressure saturated steam power technology. CO2 emission will reduce 290 million tons through the application of energy-saving technologies. In short-term and long-term aspects, the prospect of CO2 reduction in domestic iron and steel industry is analyzed.
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    Simulation Study on the Best Tertiary Air Velocity of Coal Blend Combustion in a Calciner
    XU Shun-sheng LI Luo-jun HUANG Ri-sheng DENG Bo ZHANG Li-na SHI Yong-bin
       2013, 13 (2): 181-185.  
    Abstract （870）      PDF （478KB）（330）       Save
    In order to solve the problem of coal blend ineffective combustion in a 5500 t/d triple-spouting calciner, using FLUENT software and applying two-step competitive reaction model and two mixture fraction method, the fields of velocity, temperature and composition in the calciner were studied by numerical simulation under different tertiary air velocities. The influential law of tertiary air on the combustion of coal blend was obtained, and the simulation results were verified. The simulation results show that the results computed by the two-mixture-fraction and PDF calculation are in accordance with the real combustion of coal blend in the calciner. When the third air velocity is 26 m/s, the combustion zone of coal blend accounts for 2/3 of the calciner, the maximum combustion temperature of pulverized coal is 1940 K and the burnout rate of pulverized coal 95.45% in the calciner. The temperature distribution can meet the requirements of raw material decomposition, and slagging phenomenon can be avoided.
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    Theoretical Analysis on the Influential Factors of Bubble-Particle Collision Efficiency in Hydrocyclone Flotation
    HAN Yan-he CHEN Jia-qing SANG Yi-min RUAN Xiu-li WANG Chun-sheng WANG Jian-wen ZHANG Ming
       2013, 13 (2): 186-190.  
    Abstract （987）      PDF （244KB）（171）       Save
    On the basis of the bubble-particle collision efficiency model in the contact zone of cyclone flotation, the effects of physical property parameters, operating parameters and structural parameters on the collision efficiency were investigated. The results show that physical property parameters such as disperse phase size and density, operating parameters such as bubble size and tangential velocity and structural parameters such as equivalent hydrocyclone diameter have great effect on the collision efficiency. In the hydrocyclone flotation process, the collision efficiency increases with the increase of disperse phase size, and decreases with the increase of bubble size and disperse phase (oil droplet) density. When the disperse phase size is less than 0.02 mm, which is mainly dissolved oil, the collision efficiency increases with the decrease of tangential velocity, and increases with the increase of equivalent hydrocyclone diameter. However, when the disperse phase size is over 0.02 mm, the effects of tangential velocity and equivalent hydrocyclone diameter on the collision efficiency are exactly opposite of a bond. What removed by cyclone flotation is mainly non-soluble oil (oil drop diameter >0.02 mm). The densification of hydroclone flotation can improve the bubble-particle collision efficiency, achieving high efficiency separation.
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    NO Reduction Characteristics of Biomass Pyrolysis Products in a Drop-tube Reactor
    YANG Wu WANG Yin; SONG Yang YAO Chang-bin LIU Yue-jin XU Guang-wen
       2013, 13 (2): 191-196.  
    Abstract （904）      PDF （227KB）（284）       Save
    A continuous drop-tube furnace was used to simulate the combustion conditions in the reburning zone of circulating fluidized bed decoupling combustion, and a series of experiments was conducted to study the NO reduction characteristics of pyrolysis products of distilled spirit lees, char, tar and pyrolysis gas, in terms of the specific NO reduction efficiency (hE) defined against the unit-mass flow reductant. The results indicated that with increasing of reaction temperature from 800 to 1050℃, hE of char, tar and pyrolysis gas increased. The optimal residence time for the possibly highest hE was 3.4 s for tar and char reductants. With increasing of NO concentration from 400′10-6(j) to 1000′10-6(j) in the reactant gas, the specific NO reduction efficiency decreased, but the reduced absolute NO amount increased for all the pyrolysis products. Increasing the O2 concentration in the reactant gas caused hE to decrease for char, to increase for pyrolysis gas and a parabola variation with increase first and then decrease for tar. At the O2 concentration of 1.63%(j), hE for tar was highest and reached 60.1%. This study demonstrated that unit-mass flow reactant tar enabled the highest NO reduction in comparison with char and pyrolysis gas.
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    Extraction of Rare Earth Ions by Emulsion Liquid Membrane from Acidic Leaching Solution of Phosphorus-containing Ore
    XIE Zi-nan CHEN Qian-lin ZHAO Li-jun
       2013, 13 (2): 197-201.  
    Abstract （802）      PDF （238KB）（165）       Save
    Lanthanum and cerium ions riched phosphate ore in Zhijin was dissolved by hydrochloric acid, then extracted by emulsion liquid membrane. This liquid membrane system contained di(2-ethylhexyl)-phosphate as carrier, sorbitol anhydride or polyisobutylene succinimide as surfactant, sulfonated kerosene as solvent and hydrochloric acid as strippant. The effects of carrier and surfactant to emulsion on recovery of rare earth ions were studied. Separation and extraction of rare earth ions under different pH values were also examined. The results showed that the optimum concentrations of carrier and surfactant were 12%(j) and 4%(j) respectively, with the increase of pH value in external aqueous phase, the extraction rate of rare earth ions with emulsion liquid membrane increased. When the concentration of rare earth ions was 100 mg/L, and pH=1 in external aqueous phase, their extraction rate was up to 79.93%.
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    New Extraction Process of Vanadium from Stone Coal by Acid Curing
    WAN Hong-qiang NING Shun-ming SHE Zong-hua XING Xue-yong FENG Zhi-min
       2013, 13 (2): 202-206.  
    Abstract （809）      PDF （217KB）（388）       Save
    Using the vanadium-containing stone coal from south China as raw material, the acid curing process of vanadium recovery was studied. The effects of process parameters, such as granularity, water addition, dosage of sulfuric acid, curing temperature, curing time and leaching solution, on the leaching of vanadium were examined, as well as the behavior of H2O in the acid curing process. The optimal conditions were obtained as follows: ore granularity 125 mm, water addition 10%(w), dosage of sulfuric acid 20%(w), curing temperature 140℃, curing time 3 h, leaching time 2 h, and ratio of liquid to solid 1.5 mL/g. Under the optimum conditions, the leaching rate of vanadium was 87.8%. The structure of micas mineral in the ore was destroyed, and SiO2 formed in the curing, which was difficult to digest. The concentration of SiO2 in leaching solution was 0.09 g/L, being beneficial to subsequent processing.
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    Effect of Extracellular Polymeric Substances on Flocculation-Sedimentation during Domestic Wastewater Treatment
    MA Xing-guan JI Wen-juan JIANG Tao XUE Xiang-xin YANG He FU Jin-xiang
       2013, 13 (2): 207-211.  
    Abstract （841）      PDF （216KB）（470）       Save
    The effects of concentrations of protein and polysaccharide, mass ratio of protein to polysaccharide (P/C) and total quantity of EPS on flocculation-sedimentation were studied using an integrated membrane biological reactor (IMBR) during domestic wastewater treatment at room temperature. The relationships between influential factors and turbidity as well as sludge volume index (SVI) were established by binomial nonlinear regression equations, and the corresponding flocculation-sedimentation mechanism was analyzed. The results show that increasing the concentration of EPS worsens the flocculation and sedimentation with the higher nonlinear related coefficient (R2) being 0.683 and 0.785, respectively. With the increase of concentrations of protein and polysaccharide, both turbidity and SVI exhibit ascending tendency, demonstrating the depressed flocculation-sedimentation. The turbidity decreases while SVI displays a relative steady with increasing of P/C. And the polysaccharide has a greater effect on flocculation-sedimentation than protein. Based on the DLVO theory, the functions of EPS and its constitutes were analyzed. It is explained that the flocculation-sedimentation mechanism originates from the competitive result between long range van der Waals force and double-layer repulsion.
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    Treatment of Wastewater Containing Chromium Ion by Intermittent Foam Fractionation
    WANG De-jin SHEN Wen-hao
       2013, 13 (2): 212-216.  
    Abstract （808）      PDF （251KB）（126）       Save
    Using a homemade inner circulating foam fractionation column, simulated wastewater containing Cr ion was treated and compared with a conventional bubble tower in its separation efficiency, and the influential factors pH value, Fe(NO3)3, concentration of sodium dodecyl sulfate (SDS), gas flow and separation time were examined. The results show that the circulating flotation column separation efficiency is higher within 12 to 35 min, Cr ion concentration reaches 0.6 mg/L in the fractionation in 35 min, but 10 mg/L in the conventional bubble column. The optimum operating conditions of inner loop flotation column are obtained, for the initial Cr ion concentration of 20 mg/L in waste water, under pH 5.5, SDS 100 mg/L, Fe(NO3)3 60 mg/L, and gas flow rate of 800 mL/min, the treatment effect is preferable. The bubble entrainment rate is about 10%, and Cr(III) removal rate over 97%.
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    Pyrolysis Kinetics of Activated Sewage Sludge in Preparation of Sewage Sludge-based Activated Carbon
    SHAO Rui-hua FANG Ping
       2013, 13 (2): 217-223.  
    Abstract （856）      PDF （247KB）（345）       Save
    Pyrolysis mechanism of activated sewage sludge in preparation of sewage sludge-based activated carbon was studied by using non-isothermal TG and non-isothermal pyrolysis kinetics. The non-isothermal kinetic parameters and mechanical functions were analyzed by Flynn-Wall-Ozawa and Coats-Redfern equations. Pyrolytic kinetics parameters were studied respectively before and after DTG peak in low-temperature pyrolysis and mesothermal solution stages. The most probable pyrolysis mechanism function of activated sewage sludge was determined by double extrapolation method. The results showed that the kinetic parameters (reaction activation energy E and Arrhenius factor A) before and after DTG peak in low temperature pyrolysis stage are Ea?0=32.53 kJ/mol, lnAb?0=4.37, Ea?0=39.7 kJ/mol, lnAb?0=3.94 (a, sample conversion rate, b, heating rate) respectively, and Ea?0=130.24 kJ/mol, lnAb?0=19.10, Ea?0=150.14 kJ/mol, and lnAb?0=17.13 before and after DTG peak in middle temperature pyrolysis stage. Pyrolysis mechanism of activated sewage sludge meets the four-stage pyrolysis mechanism model, Mampel-Power rules (n=1/3), three-order chemical reaction, two-order chemical reaction and Mampel-Power rules (n=3/2).
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    Preparation of Al- and K-containing Products from Associated Alunite Ore Tailings
    QIN Ming ZHAO Wei XUE Tian-yan YU Zhi-hui ZHAO Hong-xin; LI Jie SONG Jing GUO Qiang RUAN Ren-mang QI Tao
       2013, 13 (2): 224-229.  
    Abstract （851）      PDF （293KB）（413）       Save
    A medium temperature calcination-low concentration acid leaching process was introduced to treat the associated alunite ore tailings. After calcination of the tailings at 700℃ for 3 h, and following leaching at 90℃ for 3 h in 10% sulfuric acid system with the acid/ore ratio of 6 mL/g, the leaching rates of Al and K reached 83% and 93%, respectively. Alum and aluminum sulfate hydrate crystals were obtained through natural and evaporation crystallization. The recovery rate of alum and aluminum sulfate hydrate crystals was up to 65%. This work provides a method to separate aluminum and potassium products preliminarily under the premise of reduction of energy and acid consumption.
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    Dissolution of Al2O3 in VOD Refining Slag
    SU Li-juan LI Guang-qiang LI Wei YUAN Gang LI Peng; CHEN Zhao-ping
       2013, 13 (2): 230-235.  
    Abstract （807）      PDF （330KB）（297）       Save
    The absorption rate of Al2O3 in CaO-SiO2-Al2O3-MgO-CaF2 VOD refining slag is simulated by the dissolution rate of rotating Al2O3 rod in the slag. The effects of various factors on its dissolution rate were examined. The results show that the limiting step of Al2O3 dissolution is its mass transfer to molten slag. The rate increases with increasing of the rotating angular velocity of Al2O3 rod. The dissolution rate in the slag with the basicity of 4 and Al2O3 content 25% increases from 19.2′10-3 to 29.2′10-3 g/(cm2·min) with increasing of the rod rotation angular velocity from 100 to 200 r/min at 1600℃. Increasing the basicity of refining slag reduces the saturation solubility of Al2O3 in the slag. When the basicity of refining slag increases from 3 to 5, the dissolution rate of Al2O3 decreases from 30.7′10-3 to 9.4′10-3 g/(cm2·min) at 1600℃. When the basicity of refining slag is 4, with the initial Al2O3 content in slag increasing from 15% to 35%, the dissolution rate from 36′10-3 down to 25.8′10-3 g/(cm2·min) at 1600℃. Increasing the temperature and decreasing the basicity of slag are beneficial to increase of the Al2O3 absorbability. The dissolution activation energy of Al2O3 in dissolving process is obtained, which increases with the initial Al2O3 content in the refining slag.
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