Table of Content

20 December 2010, Volume 10 Issue 6

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反应与分离

Study on Treatment of Oily Wastewater by Loop Flotation Column

YAN Chao-yu LIU Yan-sheng CAO Rui JIANG Jing-jing

. 2010, 10(6):  1010-1114. 

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The effects of gas velocity, liquid flux, and packing installed in the upper gas-liquid separation region on recovery efficiency of oil were experimentally studied in a loop flotation column. The loop flotation column was composed of an outer cylinder with inner diameter 100 mm and height 932 mm, and a inner concentric draft tube with inner diameter 59 mm and height 780 mm. Air and diesel oily wastewater were used as the media in the experiments. The results show that the recovery efficiency of oil firstly increases and then decreases with increasing the gas velocity. However, the recovery efficiency always decreases with increasing the liquid flux. Compared with the conventional cylindrical flotation column, the loop flotation column can obviously enhance the recovery efficiency of oil. The optimal operation gas velocity and liquid flux determined by the experiments are 0.015~0.02 m/s and 20 L/H, respectively. The maximum recovery efficiency of oil can reach 57.3% under the condition of packing installed in the upper region of the flotation column. Based on the experimental data, an empirical model was established which considered the effects of bubble characteristics, liquid physical properties, gas and liquid flux, and oil droplet back-mixing on the removal efficiency of oil which agreed well with the experimental data.

综述

Research Advances in Phase Change Materials for Thermal Energy Storage

YE Feng QU Jiang-lan ZHONG Jun-yu WANG Cai-xia YANG Jun DING Yu-long

. 2010, 10(6):  1031-1041. 

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The research advances in thermal energy storage using phase change materials (PCMs) with focus on the state-of-the-art development of materials are reviewed. After a brief discussion on the classification of PCMs according to the phase change temperature, currently widely used PCMs are summarized. Their properties, preparation, applications and technical barriers are presented. Finally, an outlook for the future development of PCMs is given, indicating that the assembly of PCMs, phase change heat exchanger, and the concept of thermal management will be the main trend in development of high efficient thermal storage systems.

流动与传递

Comparison of Turbulent Models on 3-D Flow in the SEN of Slab Continuous Casting Controlled by Slide Gate

ZHANG Xiao-wei; JIN Xiao-li WANG Yin; DENG Kang; REN Zhong-ming;

. 2010, 10(6):  1041-1047. 

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The fluid flow in the SEN and its outflow characteristics at nozzle port, after introduction of slide gate system to control molten steel flow rate, are investigated by mathematical simulation using standard k-ε model, RSM and experimental measurement by ultrasonic Doppler velocimeter (UDV), and the adaptability of turbulence models is also examined. The research results indicate that due to the throttling action of slide gate, a secondary flow, with 80 mm length in vertical direction, appears under the slide gate, and a separated flow, located at 100 mm under the slide gate, forms with the length of 50 mm. At nozzle port, a swirl flow is generated with the swirling direction from the clogging side via nozzle bottom to the opening side of slide gate. The swirling direction of fluid at the nozzle port calculated by standard k-ε model is contrary to the measurement result by UDV, but the calculated result obtained by RSM is close to the UDV data. Based on molecular dynamic theory, isotropy hypothesis and history effect, theoretical deficiencies of the standard k-ε model are discussed.

综述

Research Progress in Preparation Techniques of High-efficiency Phosphor Powder for White Light Emitting Diode

ZHANG Xing HU Peng CAO Yue-bin ZHANG Hai-bao LI Jin-lin XU Rui-fen YUAN Fang-li

. 2010, 10(6):  1042-1048. 

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The key to achieve the high performance white LED is the preparation of YAG powder with high degree of sphericity, even structure, excellent optical property and controlled emission spectrum. The main research results for luminescent materials used in fabrication of white light emitting diode presently at home and abroad are reviewed, and both advantages and disadvantages of current main methods used for production of YAG are discussed in detail. The main problems on the development of such phosphors are summarized briefly and the prospect of the phosphors is presented. It is suggested that both the improvement of uniformity of lanthanon and the effective control of shape of the particles are effective solutions to the poor CRI and low luminescent efficiency of LED, and plasma technique is an active approach to solve these problems possibly.

流动与传递

Liquid Phase Axial Diffusion Coefficients of Gas-Liquid Concurrent Flow in Different Types of Bubbling Column

AN Gang SUN Bo AN Yi-hong ZHANG Yan CHEN Jian-kan

. 2010, 10(6):  1048-1053. 

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The axial back-mixing flow in air-water system was experimentally investigated by using a pulse tracer method in bubbling column, sieve plate bubbling column and reciprocating plate column with the same size, respectively. The effects of flow velocities of water and air on liquid phase axial diffusion coefficients of the bubbling and sieve plate bubbling columns were measured, and the effects of flow velocities of water and air and the sieve vibration intensity on liquid phase axial diffusion coefficients of reciprocating plate column. The results show that the liquid-phase axial-dispersion coefficient in the bubble column is proportional to the flow velocity of liquid to the power of 0.696~1.158, the liquid-phase axial-dispersion coefficient in the sieve plate bubble column can be expressed as EZ=0.798uG0.77uL1.252, and the liquid-phase axial-dispersion coefficient in the sieve plate bubble column is proportional to the flow velocity of liquid to the power of 0.8354~1.2740.

过程与工艺

Effect of F- on Physico-chemical Properties of Mold Slag Used for High-Al Steel

YU Xiong WEN Guang-hua TANG Ping WANG Huan

. 2010, 10(6):  1053-1057. 

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In order to avoid or alleviate the reaction between Al in liquid steel and SiO2 in slag during the continuous casting of high-Al steel, a new mold slag with low content of SiO2 and high content of Al2O3 was designed. F- was used to adjust the physico-chemical properties of mold slag. The influence of F- content on melting point and viscosity property of slag, and heat flux through slag film in high-Al steel slag was studied by experiment. The results show that the melting point decreased by 4.5℃, and viscosity decreased by 0.004 Pa×s with F- increasing by 1% each time in the range from 5.8% to 8.8%. With the increase of F- content, heat flux through slag film increased, and the characterization time decreased. As for the slag with the F- content of 5.8% and 8.8%, the minimum incubation time of them was both 6 s, but the minimum crystallization time was deduced from 46 s to 30 s. Under this experiment condition, it developed in accordance with one dimension style, based on the analysis of crystallization kinetics.

流动与传递

CFD Simulation of the Flow Field and Cavern Formation of Pseudoplastic Fluid with a 6-blended-blade Impeller

LUAN De-yu ZHOU Shen-jie; CHEN Song-ying CHU Shu-po

. 2010, 10(6):  1054-1059. 

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Computational fluid dynamics method was applied to study the 3D flow field and cavern formation in the agitation of xanthan gum, a pseudoplastic fluid with yield stress, with a 6-bent-blades impeller. The power number, flow number, pumping efficiency and cavern size as a function of Reynolds number were examined, respectively. The results show that in the laminar regime, the power number was inversely proportional to Reynolds number, and flow number and pumping efficiency increased as Reynolds number increased, but they decreased as the mass concentration of solution increased. The cavern simulated by Herschel-Bulkley model was cylinder in shape. The predicted size of cavern was in good agreement with that calculated using Elson's model at Dc

Temperature Field Simulation of Intermediate Frequency Electro-magnetic Sealing in Hot Dip Galvanizing Process

HE Wen-li MA Yong-lin CAI Miao XING Shu-qing

. 2010, 10(6):  1060-1065. 

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The temperature distribution of liquid zinc was simulated in the course of intermediate frequency electromagnetic sealing through ANSYS software. Liquid zinc temperature was calculated when frequency was 900, 1200 and 1500 Hz, and current density 4′106, 6′106 and 8′106 A/m2 respectively by using electromagnetism-heat coupling method. The relations among liquid zinc temperature, frequency, current density and conduction time were analyzed. The results showed that the temperature of molten zinc increased due to the heat produced by eddy current. Besides, the temperature of molten zinc was quite inhomogeneous in the course of intermediate frequency electromagnetic sealing. The reduction of current density and frequency could decrease the difference between the maximum and minimum temperatures of molten zinc, and decrease the rise of molten zinc temperature. However, the demand of sealing liquid zinc should be considered for successful sealing of zinc in the intermediate frequency electromagnetic field.

Mathematical Simulation on Flow Behavior of Immersion Side-blowing in Iron-bath Smelting Reduction Furnace

YIN De-you CHENG Wei-ling XIE Jin-yin FENG Kong-fang WANG Bo ZHANG Jie-yu ZHENG Shao-bo HONG Xin

. 2010, 10(6):  1066-1070. 

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The CFD software Fluent 6.3 was used to simulate the flow behavior in an iron-bath smelting reduction furnace with the side-blown immersion technique. The VOF and standard turbulence models were applied to simulate three-phase flow of the gas, slag and molten iron bath. The effects of location, submerged depth and angle of side nozzles on the flow field in the furnace were studied. The results show that when the location of side nozzles is lower, the gas contents in the slag and liquid iron are higher, and the stirring of bath is more violent. When the submerged depth of side nozzle increases, the stirring of bath is more violent and more slag splashed to the top space. When the submerged depth of side nozzle decreases, the outlet of nozzle is closer to the furnace wall and the stress near the wall increase. When the angles of side nozzle are 30° and 50°, the slag droplets in the top space increase, the stirring of slag is more intense. When the nozzle angle is 30°, the furnace wall is less eroded.

Macro-mixing of Tubular Reactor with Helical Internals Constructed with Pins

ZHANG Li XIE Gui-lan LIU Yun-yi WU Jian-hua

. 2010, 10(6):  1071-1075. 

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Helical internals constructed with pins were inserted into a tubular reactor. The residence time distributions in the reactor were measured experimentally by applying pulse response method, and the macro-mixing characteristics of the fluid in the reactor were investigated. The enhancement mechanism for mixing by this kind of internal was analyzed. The results show that the fluid flow pattern in the reactor with helical internals constructed with pins is more approach plug flow. The Peclet number of axial diffusion model, Pe, of the reactor with helical internals constructed with pins is 1.02~1.28 times as much as that of the reactor only with helical internals, and 1.35~1.77 times as much as that of the reactor without internals. The internal can significantly increase the secondary flow. Therefore, the macro-mixing is enhanced.

反应与分离

Distribution Behaviors of Vanadium between Hot Metal and FeO-SiO2-MnO(-TiO2) Slag System and Influential Factors

DONG Jin-ming ZHAO Fei ZHANG Yan-ling QIU Sheng-tao GAN Yong

. 2010, 10(6):  1076-1083. 

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Distribution behavior of vanadium between hot metal and slag system of FeO-SiO2-MnO(-TiO2) was experimentally studied, together with the influential factors such as temperature, slag compositions, ratio of slag to hot metal, and initial [Si] or/and [Ti] content of hot metal. The results showed that in the ternary slag system of FeO-SiO2-MnO, the extraction rate of V from the hot metal, distribution ratio of V between slag and metal phases, and vanadium capacity of slag decreased with increasing of temperature, while the loss of C in hot metal caused by oxidizing reactions increased; the lower the ratio of slag to hot metal, the lower the extraction rate of V; while in the two cases of higher and lower ratio of slag to hot metal, the extraction rates of V reached their maximum values in the slag composition scope of MnO at 13%~25% and SiO2 at 12%~24%. In the quaternary slag system of FeO-SiO2-MnO-TiO2, with increasing of TiO2 content in slag, the extraction rate of V, distribution ratio of V between slag and metal, and vanadium capacity of slag decreased, while the activity coefficient of V2O3 in slag increased. Under laboratory conditions, the effects of influential factors on the extraction rate of V from hot metal decreased in the following order: final slag compositions > temperature > initial [Si] or/and [Ti] content.

Adsorption Behavior and Mechanism of Uranium(Ⅵ) on Modified Wheat Straw

WANG Xiao XIA Liang-shu ZHENG Wei-na TAN Kai-xuan

. 2010, 10(6):  1084-1090. 

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The effects of modification agents, pH value, adsorption time, adsorbent dosage, solution initial concentration and temperature on biosorption capacity were investigated with static experiments, and the adsorption process was analyzed in thermodynamics and kinetics. The results showed that the adsorption rate of uranium(VI) on wheat straw increased about 52% after modifying by NaOH. At 303 K and pH 3.0, the saturated adsorption Qmax was up to 1.20 mg/g for approximately 120 min. The equilibrium data fit well with the Freundlich isotherm, and the adsorption reaction was endothermic and spontaneous. The pseudo-second-order equation provided the best correlation for the adsorption process. The mechanism of uranium(VI) adsorption matched the coordination complexation.

Absorption of Carbon Dioxide into Aqueous Solutions of Alkanolamines in a Packed Column

GAO Han GUO Ya-ping CHU Lian-feng GUO Ya-jun;

. 2010, 10(6):  1091-1097. 

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The removal efficiency of carbon dioxide into the aqueous solutions of N-methyldiethanolamine (MDEA) containing monoethanolamine (MEA), piperazine (PZ), diethylenetriamine (DETA) and triethylenetetramine (TETA) as activators in a packed absorption column was investigated. The results indicated that the order of activity capacity of different amines was TETA>DETA> PZ>MEA. The outlet concentration of CO2 could be decreased to 0.05%(mol) and the removal efficiency could be increased to 98.62% by using TETA as activator. A higher concentration of activator and a lower gas flow rate was more favorable to raising removal efficiency of CO2. The variation of absorption rate with absorption time and concentration of activator by carrying out absorption and regeneration synchronously was studied in details.

Decolorization of KN-B, K-2BP and KN-R Dyes onto Macroporous Anion Resin (D201)

QIAN Yong HUANG Tian-yin WANG Dong-tian CHEN Hong-ying GONG Jing

. 2010, 10(6):  1098-1103. 

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The adsorption behavior of reactive black 5 (KN-B), reactive red 24 (K-2BP) and reactive blue 19 (KN-R) dyes onto a macroporous strong basic anion exchange resin (D201) was investigated. It was found that their decolorization rates onto D201 all increased with the increase of temperature, doses of D201 and NaCl concentration and with the decrease of initial pH value and initial reactive dye concentration. Under pH=7 and 298 K, the adsorption isotherms indicated that the equilibrium data successfully fitted to Freundlich and Langmuir adsorption isotherms, the maximum adsorption capacity for KN-B, K-2BP and KN-R is 129.38, 94.79 and 133.28 mg/g, respectively. The adsorptions are physical and spontaneous processes. Pseudo first-order, pseudo second-order and intra-particle diffusion theoretical models were applied to correlate the kinetic experimental data. Pseudo first-order kinetic model was more accordant with the experimental data than pseudo second-order kinetic model. The order of adsorbing decolorization effect of the reactive dyes onto D201 from high to low was KN-R>KN-B>K-2BP.

Study on Desulfurization of Coal by Oxidizing Leaching with Ferric Sulfate

WU Fu-zhong JIN Hui-xin JIAO Dong-wei

. 2010, 10(6):  1104-1109. 

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In order to remove sulfur of the coal mined from Guizhou Province, aqueous ferric sulfate oxidizing leaching method was used. The effects of ferric sulfate concentration, leaching temperature, leaching time and liquid/solid ratio on the desulfurization efficiency were investigated. The results indicated that 48.44% sulfur was removed under the conditions of leaching temperature at 100℃, leaching time 8 h, ferric sulfate concentration 1 mol/L and liquid/solid ratio 10:1. Difference between original and desulfurized coal samples was also investigated. The results showed that active components of the coal sample were not destroyed when sulfur was removed. Moreover, the caloric value and quality of the coal sample were improved after desulfurization.

Experimental Study on Pre-reduction of Fine Dust from Stainless Steel Making

LI Yuan-chao; YU Xiao; WANG Qiang LI Qiu-ju HONG Xin

. 2010, 10(6):  1115-1118. 

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Pre-reduction of fine dust from stainless steel making was studied in a new designed moving bed reactor with inclined tube and intermittent vibrators. In experiments, mixed gas of H2 and CO was used to simulate the exhaust gas from the end reforming, for the purpose to examine the influences of different factors on the process of pre-reduction of fine dust from stainless steel making. The results show that gas-solid ratio 0.85 L/g, component of reducing gas CO 0~40%(j), and intermittent-vibration ratio 1:2 were the optimal conditions, and the maximal reduction rate of 73.6% was reached.

过程与工艺

Basic Research on Preparation of High Titanium Ferroalloy with Low Oxygen Content by Thermit Reduction

DOU Zhi-he ZHANG Ting-an ZHANG Han-bo ZHANG Zhi-qi NIU Li-ping HE Ji-cheng

. 2010, 10(6):  1119-1125. 

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Rutile, ilmenite and Al powder (or Al-Mg alloy) were used to prepare high titanium ferroalloy. The adiabatic temperatures of different reaction systems and the Gibbs free energy changes of relative reactions on TiO2-Al system and TiO2-Mg systems were calculated. The reaction kinetics of the systems was studied by DTA. The high titanium ferroalloy was characterized by XRD, SEM and electron microprobe. The results indicate that the adiabatic temperatures of all reaction systems are higher than 1800 K so all the reactions can be kept spontaneously. The content of oxygen and inclusions in the alloy can be controlled to lower level when Al-Mg alloy is used to reduce TiO2. The apparent activation energy is 164.497 kJ/mol and reaction order 0.414 when Al reduces TiO2. The apparent activation energy is 383.235 kJ/mol and reaction order 0.591 when Mg reduces TiO2. The high titanium ferroalloy consists of Al2O3, TiO2, Ti2O, Fe2TiO4, and Ti9Fe3 (Ti0.7Fe0.3)O3 complex phases. The oxygen content in the ferroalloy is up to 12.20%.

Study on Interaction of Ce3+ and Bovine Serum Albumin

WU Jin-xiu LI Mei SONG Yu-min LIU Zhao-gang HU Yan-hong WANG Mi-tang

. 2010, 10(6):  1126-1131. 

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In physiological condition, the binding reaction of Ce3+ and Ce2(CO3)3 with bovine serum albumin (BSA) was studied by fluorescence and UV spectra. The fluorescent mechanism of Ce3+ and Ce2(CO3)3 with BSA was examined, and the combination constant (KA) and thermodynamic parameters (DH, DG and DS) of Ce3+, Ce2(CO3)3 and BSA at different temperatures calculated, and the reaction type of Ce3+ and Ce2(CO3)3 with BSA determined. From the result of DH<0, ΔS>0, It can be judged that Ce3+, Ce2(CO3)3 and BSA had mainly electrostatic attraction. The results showed that Ce3+ and Ce2(CO3)3 reacted with BSA to form new compound systems under nCe3+:nBSA=1.8:1 and nCe2(CO3)3:nBSA=2.6:1. The quenching belonged to static fluorescence quenching caused by non-radiation energy transfer.

Kinetics of Moisture Removal for Coal Preheating and Moisture Control

XIE Yi-min LIU Zhou-en; TIAN Ya-jun WANG Yin; WU Rong-cheng LIU Yun-yi MA Xiao-xun

. 2010, 10(6):  1132-1137. 

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Under the conditions of simulated operations in the fluidized and pneumatic sections in an experimental apparatus, moisture removal behavior of coal particles was studied through investigation of variables including hot gas temperature, hot gas velocity and coal particle size. It was found that about 5 was needed to reduce the moisture of coal larger than 3 mm to 6%~9%(w) under the fluidized conditions when gas temperature was 503~543 K and gas velocity 3.0~4.5 m/s. By contrast, under the pneumatic conditions, the time for moisture removal of coal less than 3 mm was 5~7 s when gas temperature was 423~523 K and gas velocity 7~10 m/s. Analysis identified that the moisture removal kinetics could be described with the Page model in both of the simulated fluidized and pneumatic conditions.

Extraction Process of Copper from Chalcopyrite Concentrate by Low-temperature Chlorination-Selective Oxidation

FU Nian-xin Iwasaki Iwao Tamagawa Takeo Kobayashi Mikio

. 2010, 10(6):  1138-1142. 

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Extraction process of copper from chalcopyrite concentrate by low-temperature chlorination and selective oxidation in fluidized-bed reactors was studied. The exhaust chlorine and S2Cl2 from the lower reactor are expended for chlorinating the concentrate in the upper one in the two-stage chlorination. The full-chlorinated products with lower sulfur contents are obtained at about 250 and 270℃ for the upper reactor and the lower one, respectively, and within 0.015% of Cl2 concentration in the effluent gases of the lower one. The chlorinated products are thermally cured only under a nitrogen atmosphere in a supplemental reactor, thus their sulfur contents are further reduced. The chlorinated products with lower sulfur contents can be oxidized at 350~360℃ in a stable fluidizing operation. The exhaust chlorine from the oxidation can be removed by chlorinating the concentrate with it in an upper reactor. The dilute hydrochloric acid is effective for leaching the oxidized products. In the range of pH 0.30~1.86 of the leaching solution, Cu is fully solubilized, while Fe dissolution is held to less than 5%. The concentration of Cu, Fe and SO42- in the solution increases linearly with the solid to liquid ratio. When the solid to liquid ratio reaches 0.5 g/mL, the Cu concentration reaches in excess of 115 g/L, while the Fe/Cu ratio remains below 0.03 and the SO42- concentration is also very low. This can meet the requirement of the Cu electrowinning step. The changes of the precious metals and minor impurities contained in the concentrate with the process were also briefly investigated.

Investigation on Preparation of Anhydrous Magnesium Chloride by Ammonia Complexation Method

YAN Yan LU Xu-chen WANG Ti-zhuang XIA Chao-yang OU Teng-jiao

. 2010, 10(6):  1143-1147. 

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High-purity anhydrous magnesium chloride was prepared from magnesite by ammonia complexation method. By examination of temperature, reaction time, initial concentration on the key steps of this preparation process, the following results were obtained: (1) Magnesite would be calcined into highly active magnesia at 750℃ for 2 h. (2) The optimal temperature of chlorination of active magnesia was between 130 and 150℃, and the apparent activity energy of this chlorination reaction 40.7 kJ/mol. (3) Initial concentration and temperature had remarkable effects on crystal-size distribution of magnesium chloride hexammoniate, and the optimal reaction crystallization temperature was about 15℃. In addition, magnesium chloride hexammoniate was white octahedral crystals. (4) The thermal decomposition process could be divided into three steps of 55~97, 97~182, 182~297℃ according to its TG curves, and 2 ammonia molecules of one magnesium chloride hexammoniate were released in each step.

Preparation of Copper Arsenate from Bio-oxidation Wastewater of Gold Extraction

LI Qian TIAN Yan-wen LUO SANG Cui-cheng

. 2010, 10(6):  1148-1152. 

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Based on former experimental research, the thermodynamics and process parameters for production of copper arsenate from leaching solution after separating arsenic and iron from bio-oxidation wastewater were investigated. The thermodynamics of copper arsenate preparation was analyzed by depicting the potential-pH diagram of Cu-As-H2O system. The effects of pH value, reaction temperature and stirring speed on the recovery rate of arsenic were investigated. The results showed that the optimum conditions were pH value of 4.0, temperature of 50℃ and stirring speed of 500 r/min. Under these conditions, the structural formula of copper arsenate was Cu5H2(AsO4)4 and the arsenic recovery rate over 95.10%.

Effect of Mechanical Force on Structure and Reaction Characteristics of Panzhihua Ilmenite

LEI Ying LI Yu PENG Jin-hui ZHANG Li-bo GUO Sheng-hui XIA Hong-ying

. 2010, 10(6):  1158-1162. 

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Ball milling activation of Panzhihua ilmenite was conducted on its characteristics of reduction reaction. The results show that ball milling can reduce the ilmenite grain size, and increase the stains of lattices and disorder of structure, and activity of ilmenite. The starting reduction temperature of ilmenite and graphite is reduced to 600~700℃ after milling for 4~8 h. At 912℃ of solid state reaction, the weight loss of samples milled for 8, 4, 2, 1 and 0 h is 10.99%, 7.21%, 3.95%, 3.31% and 0.90%, respectively.

Simulation on the Effects of Continuous Casting Process Parameters on Slab Shell Thickness of 316 Stainless Steel in Mould

XING Shu-qing BAI Liang MA Yong-lin LI Hui-qin FENG Dian-chen

. 2010, 10(6):  1163-1167. 

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In order to study the influences of casting speed and superheat on solidification and heat transfer in the continuous casting process, the growing process of 316 stainless slab thickness was simulated by finite element software ANSYS. Using two-dimensional model, the changes of slab shell outlet temperature, slab shell thickness and slab surface temperature were calculated when casting speed was 0.4, 0.5, 0.6 m/min and superheat 30, 40, 50℃ respectively. Meanwhile, the rules of slab shell growth and thickness change were discussed. The results showed that the outlet temperature rised by 83℃, average value of outlet thickness decreased 3.2 mm and surface temperature rised when casting speed changed from 0.4 to 0.6 m/min, and outlet temperature rised by 20℃, average value of outlet thickness decreased 1.35 mm and surface temperature rised by 20℃ when superheat increased from 30 to 50℃.

系统与集成

Process Simulation and Economic Analysis on Supercritical Methanol Production Technology of Biodiesel

ZENG Hong LI Hong-ming FANG Bai-shan

. 2010, 10(6):  1168-1174. 

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Based on the scale-up of laboratory experiment, the Superpro Designer? emluator was applied to simulate the whole process of supercritical methanol production technology for 50000 t/a biodiesel production, coupled with costing and economic evaluation on the flowsheet. Simulation results indicate that the process design is reasonable with main process data complying with experimental results. The economic analysis shows that high temperature and high pressure equipment shares larger proportion of equipment purchase cost, and raw materials cost is more than 70% of operating cost, this technology has good feasibility as the after-tax profit is about 27.04 million yuan per year with the project total investment of approximately 72.72 million yuan.

生化工程专栏

Enzymatic Synthesis of S-bzl-g-Glutamyl-L-Cysteine with g-Glutamyltranspeptidase Immobilized onto Ordered Mesoporous TiO2

XIAO Yi-fan; YAO Zhong WANG Hao-qi; HU Guo-mei;

. 2010, 10(6):  1175-1190. 

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g-Glutamyltranspeptidase (GGT) was adsorbed from B. subtilis NX-2 onto ordered mesoporous TiO2 (OM-TiO2). The immobilized GGT was characterized with circular dichroism spectrum and active site titration method. The secondary structure and number of active sites of GGT were little affected after immobilization. The immobilized GGT appeared some decline in the affinity of GGT toward donor substrate and catalytic constants. However, the affinity of immobilized GGT toward S-bzl-GGC was much higher than that of free GGT. Thermal and pH stability of GGT were significantly increased via immobilization. Residual activity of immobilized GGT still exceeded 74% of its initial value after reusing for 10 batches. At the conditions of Gln 5 mmol/L, S-bzl-cys 15 mmol/L, immobilized GGT 0.062 U/mL and pH 9.0, a maximal product yield of 1.2 mmol/L was obtained after incubation at 40℃ for 5 h.

Effects of Imidazole- and Pyridine-based Ionic Liquids on Catalysis Performance of Immobilized Penicillin Acylase

ZHOU Hua-cong LI Wei GAO Hong-shuai JIA Lian-wei XU Peng LIU Hui-zhou

. 2010, 10(6):  1181-1186. 

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In order to investigate the effect of cations of ionic liquids on catalysis performance of immobilized penicillin G acylase (ImPGA). Four kinds of imidazole- and pyridine-based ionic liquids through two-step strategy, [C4mim]BF4, [C7mim]BF4, [C4pyr]BF4 and [C7pyr]BF4 were synthesized and characterized. The hydrolysis of penicillin G potassium catalyzed by ImPGA was conducted in these ionic liquids. Enzyme activity, stability and kinetics of ImPGA were studied. Substrate inhibition of ImPGA under different substrate concentrations was also detected. The results showed that the activity of ImPGA decreased in the order of [C7pyr]BF4>[C4pyr]BF4>[C7mim]BF4. ImPGA lost its activity in [C4mim]BF4 because of high hydrophilicity of the media. Enzyme activity of ImPGA could be maintained after incubation in ionic liquids at 37℃ for 30 min in the former three ionic liquids. Two kinetic parameters, Km and Vmax, of the reaction decreased followed the order [C7pyr]BF4>[C4pyr]BF4>[C7mim]BF4. Enzyme activity was not inhibited by substrate at the concentration of 75.17~85.91 mmol/L.

Recovery of Free Lipase in the Aqueous Phase of Enzymatic Production of Biodiesel by Foam Separation

FAN Ming LI Qiang ZHAO Xue-bing DU Wei LIU Can-ming LIU De-hua

. 2010, 10(6):  1187-1192. 

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In order to recycle the enzyme for enzymatic production of biodiesel, free lipase in the aqueous phase was recovered and enriched by foam separation. Orthogonal experiments were employed to investigate the effects of air flow rate, initial enzyme concentration and pH value on enrichment ratio, recovery of protein and recovery of enzyme activity. The experimental results showed that the recoveries of protein and enzyme activity reached about 100% with the enrichment ratio of 3.67 when air flow rate, initial enzyme concentration and pH value of feed solution were 10 L/(L×h), 0.2 g/L and 7.0, respectively. Initial enzyme concentration had very significant influence on enrichment ratio. The enzyme activity was well kept during foam separation process. The presence of methanol dramatically increased the foam formation and corresponding enzyme recovery rate; glycerol decreased the enrichment ratio; and biodiesel destroyed the stability of foam. Biodiesel concentration should be lower than 0.01% to obtain stable foam formation.

材料工程专栏

Synthesis and Characterization of Copolymer of Carboxylate and Sulfonate Dispersant

WANG Li-dong REN Tian-rui YAN Yun-feng YU Song-rui XU Wen-ping

. 2010, 10(6):  1193-1199. 

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The dispersants of acrylic acid (AA)-styrene sulfonic sodium (SSS)-maleic anhydride (MA) copolymer were synthesized and their dispersion effect on inorganic BaSO4 powder and organic pesticide imidacloprid were studied in detail. The morphology, crystal structure and size distribution of BaSO4 suspended particles were characterized. The results showed that the copolymer had an excellent dispersion efficiency when the mass ratio of AA, SSS and MA is 20:4.5:2.0, reaction temperature 70℃, 7.5% of mass fraction of initiator in total monomers, and reaction time 1.5 h. The optimized copolymer dispersant (M17) was obtained, and its suspension rate to BaSO4 and water dispersible granules with 70% imidacloprid was 98.78% and 70%, respectively, which is equal to Rhodia T36.

Adsorption Characteristics of Fluoride with Granulated Fe-Al-Ce Nano-adsorbent

CHEN Lin WANG Ting-jie; JIN Yong ZHANG Yu;

. 2010, 10(6):  1200-1205. 

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The Fe-Al-Ce trimetal oxide nano-adsorbent was coated onto glass beads in a fluidized bed by spraying, and the resulting granules were used in a packed bed for fluoride removal from drinking water. The adsorption characteristics of fluoride with the adsorbent granules were studied. For the initial fluoride concentration at 10 mg/L, the fluoride adsorption rate obeyed the pseudo-first order kinetic model. The adsorption isotherm data well fitted to the Langmuir isotherm, and the maximum adsorption capacity was 5.9 mg/g. The adsorption capacity of the granules decreased with the increase of initial pH value, and the solution pH value changed to neutral regardless of the initial solution being acidic or basic. The degree of the effect of competitive ions on the adsorption capacity was in the following order: NO3-"Cl-

Composition Dependence of Corrosion Resistance of Mo-ZrO2 Cermet

JIE Chang LIU Gong-yuan ZHANG Jie-yu XU Ji-fang YUAN Fei ZHOU Guo-zhi

. 2010, 10(6):  1206-1211. 

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At 1600℃, Mo and ZrO2 powders were sintered into Mo-ZrO2 cermet samples with Mo molar fractions of 60%, 50% and 40%, respectively. Three samples were then corroded by molten IF steel and CaO-Al2O3-MgO synthetic slag for 2 h in argon protective atmosphere at 1550℃. SEM was operated to examine the change of their fracture morphology caused by corrosion. After corrosion by molten steel, EDS was conducted to detect elemental composition of samples in the edge and the points which were 0.25, 0.5 and 1 mm from edge area. The results show that the sample with the Mo molar fraction of 40% obtains the best corrosion resistance to molten steel, and the corrosion resistance of cermet to molten steel declines with the increase of Mo content. By contrast, the sample with the Mo molar fraction of 60% has the best corrosion resistance to molten slag and the corrosion resistance of cermet to molten slag declines with the reduction of Mo content.

Cationic Modification on the Surface of Fly Ash Fibres Used in Papermaking

GENG Jie CHEN Jian-ding MA Xin-sheng

. 2010, 10(6):  1212-1216. 

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Quaternary ammonium type cationic starch with low degree of substitution was used to modify the surface of fly ash fibres (FAFs) which was pretreated by hydrochloric acid first. The optimization of acid pretreatment condition, and cationic modification and the effects of surface zeta potential on the dispersion of FAFs in water were examined. The results showed that the cationic FAFs with the maximum surface Zeta potential of 19.00 mV could be obtained under the conditions of 30 min pretreatment with 0.3 mol/L HCl and 40 min cationic modification with cationic starch at the water concentration of 0.06% in 40 min stirring time under normal temperature. SEM analysis showed good coating status of FAFs. The dispersion and settling experiments proved that the higher the surface Zeta potential was, the longer the settling time would be and the better the dispersion would turn, when Zeta potential increased to 17.20 mV, the anti-flocculation was improved obviously.

Synthesis of Cationic Decoloring Agent of Dicyandiamide-Formaldehyde Polymer and Its Application in Dyeing Wastewater

ZHANG Wen-yi LIU Ming-yuan LUO Xin FAN Pei-cheng LI Qiu-yan TIAN Shao-min

. 2010, 10(6):  1217-1221. 

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A cationic organic decoloring agent for dyeing wastewater was synthesized by using dicyandiamide and formaldehyde. The effects of dosage of dicyandiamide, formaldehyde and aluminium sulphate, reaction temperature and reaction time were considered. The results showed that the optimum conditions were as flows: molar ratio of dicyandiamide to formaldehyde to aluminium sulphate was 1:2.58:0.35, reaction temperature 80℃, and reaction time 3 h. The decoloring agent synthesized under these conditions was used to decolorise three typical dyes in wastewater, Disperse Red 167, BSE blue and Disperse Blue 79, and the decolorization efficiency could be over 98%. The mechanism of decolorization was analyzed in charge neutralization, compressing the thickness of the electric double layer, bridging adsorption and network-bashing. The synthesized agent was also used in decoloring of mixed dyeing wastewater in Mahang Wastewater Treatment Plant. When pH value and decolorant dosage was 8 and 17.5 mL/L respectively, the decolorization efficiency was 96.7%, and the chroma decresed from 360 to 10 times, the effluent met the national discharge standard GB 8978.1A-1996.

Thermo-mechanical Control Process of Novel High Strength Pipeline Steel and Its Microstructure and Properties

PANG Wei JIANG Min LIU Wei-dong YANG Bo ZHEN Qiang LI Chong-he

. 2010, 10(6):  1222-1226. 

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In order to meet the requirements of pipe steel used in the oil industry with higher strength, toughness and corrosion resistance, the chemical composition of a novel high strength pipeline steel was designed. By using the Gleeble-3500 thermomechanical simmulator, the parameters of thermo-mechanical control process, including heating temperature, final rolling temperature, final cooling temperature and cooling rate, were tested by the orthogonal experiments with four factors and three levels, then the optimum parameters obtained were used in the rolling experiments conducted in the prototype rolling line. The microstructure and mechanical properties of the steel were studied. The results showed that the microstructure of the specimen rolled under the optimum parameters mainly consisted of the granular bainite, acicular ferrite and lower bainite. The mechanical properties reached the expected standard of novel pipeline steel when it was heated at 1180℃, rolled at 810℃, and finally cooled at 400℃ at the cooling rate of 35℃/s.

Preparation of Goethite Nanorods and Their Application in Catalytic Degradation of Methyl Orange

ZHANG Li-qing LIU Xin-feng; ZHOU Hua-feng XIE Ying; LI Hong-liang;

. 2010, 10(6):  1227-1230. 

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The a-FeOOH nanorods with good dispersion were prepared by air oxidation synthetic method. The catalyst samples were characterized by N2 adsorption-desorption, XRD, and SEM. Methyl orange was treated with water-curing treatment in the presence of hydrogen peroxide and goethite. All kinds of influential factors were investigated. The results show that methyl orange can be more efficiently degraded in acid media. The catalysis degradation rate increases with the concentration of H2O2, but, with 5.47 mol/L initial concentration of H2O2, the efficiency is declined. UV-Vis spectra in the treatment show that the degradation of methyl orange in the water bath has attained good effects.