The Chinese Journal of Process Engineering

Experimental Study on Fluidization and Reduction of Ultrafine Iron Oxide Powder in an Agitation Fluidized Bed

SONG Yi-feng ZHU Qing-shan

. 2011, 11(3): 361-367.

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The fluidization and reduction of iron oxide powder with averaged particle size of 239 nm in a 50 mm I.D. agitation fluidized bed were studied. The results showed that the powder in the agitation fluidized bed could be completely fluidized in the form of agglomerate bubbling fluidization. The minimum fluidization velocity was 0.025 m/s and the maximum expansion ratio could reach 2.0. And the reduction of the powder under hydrogen atmosphere at 500℃ was examined. The reduction process followed the order of Fe2O3?Fe3O4?Fe. The particle size of Fe was smaller than that of Fe2O3 and sintering happened among some particles. It might be the sintering and sticking effects resulting from metallic iron that led to the defluidization. Compared with conventional fluidized bed, the fluidization time could be increased from 3 to 15 min and the metallization rate of the products when defluidization occurred could be increased remarkably from 15% to 76% with agitation.

Simulation of Burden Trajectory in a Bell-less Top Blast Furnace

QIU Jia-yong GAO Zheng-kai ZHANG Jian-liang GUO Hong-wei WANG Chun-long KONG De-en

. 2011, 11(3): 368-375.

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An equation of motion trajectory of blast furnace burden can be established by analyzing the movement and the acting force conditions of burden in a bell-less top blast furnace. Consequently, the previous model can be improved. The accuracy of simulation model has been proven by the experimental data of a domestic 3200 m3 blast furnace charging before blowing in. The results indicate that the calculated values coincide with measured data of the radius of impact point of burden preferably. Along the chute length, the Coriolis force per unit mass increasing continuously. When the chute inclination angle is 41o, the Coriolis force per unit mass of coke approximately is 2.2~5.5 m/s2 while that of ore is about 2.1~4.6 m/s2, which accounts for 22%~56% and 21%~47% of acceleration of gravity respectively. When the flow velocity of gas is 0 m/s, the gas drag coefficient at coke is 1.83~1.88 while that at ore is 3.32~3.40, and the resistance acting on unit mass of burden is about 2.4~4.9 m/s2, which accounts for 1/4~1/2 of gravity per unit mass.

Prediction Model of Transition Velocity from Bubbling to Turbulent Fluidization in a Square Gas-Solid Fluidized Bed

ZENG Tao LIU Zhong-bin HUANG Wei-xing

. 2011, 11(3): 376-379.

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The relationship between transition velocity and static bed heights as well as axial levels were studied from bubbling to turbulent fluidization in a 368 mm′368 mm square fluidized bed, based on the pressure gradient fluctuation by measurement differential pressures transducer of FCC. The results show that the transition velocities increase with decreasing the location of observation or increasing the static bed heights. And the transition of regime from bubbling fluidization to turbulent fluidization is a process gradually happened from the upper to the lower bed section and is not instantaneous behavior concurrence simultaneity in the entire bed. Based on this, the prediction model is built that the introduction of the average particle concentration of bed cross-section is used to reflect the variation of gas-solid interaction along the bed height, and a new prediction correlation by simulating parameters of experimental data, which is in good agreement with experiment results.

Subcritical Extraction of Lipids from Wet Microalgae Paste of Nannochlorsis sp.

CHEN Min CHEN Xiao-lin LIU Tian-zhong; ZHANG Wei; WANG Jun-feng CHEN Lin CHEN Yu PENG Xiao-wei GAO Li-li

. 2011, 11(3): 380-385.

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The extraction of lipids from wet microalgae paste of Nannochlorsis sp. with subcritical extraction method of ethanol, ethanol-hexane co-solvents, and ethanol-hexane co-solvent added with sulfuric acid was investigated. The results showed that at the same extraction recovery rate of lipid of about 85%, subcritical ethanol-hexane co-solvent extraction only required 10 mL/g solvent to dry algal biomass, compared with 30 mL/g by subcritical ethanol extraction. The addition of drops of sulfuric acid to subcritical ethanol-hexane co-solvent extraction could further modify the extraction rate of lipids. The optimum extraction conditions of wet algal paste of Nannochlorsis sp. were suggested as follows: ratio of hexane to ethanol 3:1(j), ratio of solvent to algal biomass 7 mL/g, sulfuric acid to biomass 6%(w), 1.5 MPa of pressure and 30 min extraction at 90℃, at which the recovery rate of lipid oil from wet algal paste could reach 90%. Triglyceride was the main component of the extracted lipid oil. Relatively, more triglycerides (about 86%) in extracted lipid by subcritical ethanol-hexane co-solvent added with sulfuric acid were obtained. The fatty acids profile of triglycerides revealed that C16:0 (35.5%), C18:1 (24.56%) and C16:1 (22.08%) were dominant.

Solubility and Reaction Crystallization of Ursolic Acid in Ethanol-Water System

TNAG Feng-xiang ZHU Zhong-min ZHENG Lei GUO Zhong-li GUO Yang-hao

. 2011, 11(3): 386-390.

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The solubility of ursolic acid in ethanol-water system was measured in the pH value range of 7~10 and ethanol concentration range of 60%~90%(w) under room temperatures (20 and 30℃) using a dynamic method. It was found that increasing pH value and ethanol concentration resulted in the enhancement of solubility. The ursolic acid solubility increased sharply with pH value only at higher pH range (9~10), and just in this pH range, the increase of ethanol concentration could significantly raise the solubility. Ursolic acid solubility was more sensitive to pH value than ethanol concentration at room temperatures and hence reaction crystallization by adding acid was suitable to ursolic acid recovery. Based on the variation trend of solubility with pH value and ethanol concentration, empirical equations were used to correlate the relationship between solubility and pH and ethanol concentration with a high relative coefficient of 0.998. In addition, the reaction crystallization metastable zones of ursolic acid in ethanol-water system were determined using laser monitoring technique. The metastable zone width (DpH) decreased, then increased with increasing saturation concentration of ursolic acid and seemed to increase with the increase of temperature. When 80% ursolic acid from loquat leaves was dissolved in 90%(w) ethanol-water at pH 10, a bench-scale reaction crystallization process was carried out at appropriate acid concentration and acid-adding rate, and 98% ursolic acid was obtained with a overall yield of 78%. The ursolic acid crystals were rod-like and white glossy particles.

Formation Mechanism of Splashed Slag Layer in Nickel Converter during Slag Splashing Process

MA De-gang CHEN Wei-qing

. 2011, 11(3): 391-395.

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The chemical composition, melting temperature, viscosity, microstructure of splashed slag layer, and its formation mechanism were investigated in used bricks during nickel blowing converter slag splashing process. The results show that at the very beginning of splashing the transition layer formed with main phase of iron oxides on the surface of brick. By further bonding of the slag and brick, the sticking layer formed and phases were hortonolite and magnetite. The content of MgO in the sticking layer was increased at 11.01%, and the melting temperature rose up to 1424℃. During the next blowing circle, the iron oxides in the transition layer diffused and reacted with the magnesia-chrome lining, resulting in the layer of Fe-spinal and Mg-Fe solution. Meanwhile content of Fe2O3 in sticking layer was obviously increased from 1.33% to 18.43% and melting temperature increased to 1598℃. The wearing rate of bricks per heat was decreased by nearly half and the lining life increased greatly.

Treatment of Tungsten(VI) in Aqueous Solution with Polymer-enhanced Ultrafiltration

ZENG Jian-xian SUN Xia-hui ZHOU Hu HE Qin-cheng LI Shu

. 2011, 11(3): 396-400.

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Polymer-enhanced ultrafiltration process was investigated for treatment of tungsten(VI) in aqueous solution. Polyquaternium-6 (PQ6) was added as a water soluble polymer to bind selectively tungsten(VI). The possibility of pre-treating PQ6 was tested by using the diafiltration method. The results showed that PQ6 rejection coefficient increased gradually with increasing of diafiltration volume, and then reached 1. The loss rate of PQ6 was 12.7%, and membrane flux (J) increased slightly in this pre-treatment process. The effects of polyelectrolyte/metal mass ratio (r) and pH value on tungsten(VI) rejection coefficient (RW) and J were studied. When r increased from 1 to 3, RW increased linearly. When r was above 3, RW was close to 1. The binding capacity of PQ6 with tungsten(VI) was 3.0 mg/mg. When pH value increased from 3 to 9, RW values obtained at different pH values were almost equal. J decreased slightly with increasing of r, and did not vary with pH value. The concentration experiment was carried out at r=3 and pH=7. The results showed that when volume concentration factor reached 16, J only declined 15.2%, and RW was about equal to 1. Tungsten(VI) concentration in the retentate increased from 20 to 317.5 mg/L, whereas its concentration in the permeate was always about 0.04 mg/L, i.e., tungsten(VI) was concentrated efficiently.

Kinetics of Chromium Ion Removal from Wastewater with Continuous Foam Separation

LI Zhi-zhou

. 2011, 11(3): 401-404.

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Cr(VI) was separated from wastewater using the ferrous coprecipitation continuous foam separation method. The effects of pH value, molar ratio of Fe2+ to Cr(VI), concentration of sodium dodecyl benzene solfonate (SDBS), gas flow and separation time were studied. The results showed that under the optimal operating conditions of the molar ratio of Fe2+ to Cr(VI) 5:1, wastewater pH value 9.0, gas flow 450 mL/min, concentration of SDBS 60 mg/L, and separation time 30 min, Cr(VI) removal rate was 98.72%. According to the similar physical behavior of foam separation and chemical reaction processes, the equivalent chemical reaction constant was introduced, and the macroscopic kinetics of using coprecipitation foam to remove Cr(VI) from water was also studied. The result indicated that the coprecipitation foam separation process could be regarded as a first order reaction, and its equivalent rate constant was 0.541.

Simulation of Flow Sheet and Optimization of Operational Parameters on Atmospheric and Vacuum Distillation Units for Crude Oil

YAO Yue-hua CHEN Yan-jie ZHANG Xiang-ping REN Bao-zeng WANG Jing-heng TIAN Xiao

. 2011, 11(3): 405-413.

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Based on process simulations of prefractionator, atmospheric distillation unit (CDU), and vacuum distillation unit (VDU) for crude oil using Aspen Plus software, some key parameters including temperature and flow rate of each distillation unit, and distillation range of the side products of VDU were obtained, and the results calculated from Aspen Plus were in consistent with the data collected from the factory. Flow rate profiles of vapor and liquid and temperature profiles of three distillation units were analyzed, and related parameters were optimized using sensitivity analysis tools in Aspen Plus. The diesel yield of CDU was increased by 0.22% and duty of CDU reduced 6.3%, the light oil yield of VDU increased by 0.18% and duty of VDU reduced 11.2% after optimization.

Preparation and Composition Control of Multi-metal-doped Iron Phosphate by Acidolysis of Steel Slag

WU Zhao-jun JIANG Bei-feng CAO Fa-bin LIU Wei-ming WU Xing-rong LI Liao-sha

. 2011, 11(3): 414-421.

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Dissolving steel slag in sulfuric acid and reacting the filtrate with phosphoric acid through adjusting pH value, a multi-metal-doped iron phosphate is prepared by recovery of multiple metals from steel slag. The precipitation behaviors of target metal ions, such as Fe, Mn, Cr, Al, Mg and Ti, existing in the reaction system with appearance of PO43- polyanion are discussed. The results indicate that the precursors precipitated at pH=3.0~4.0 exhibit amorphous particles of about 50 nm, with molar ratio of total metals to phosphorous nearly to 1. Roasted at 700℃ for 5 h in air, the precursors crystallize into homogeneous powder of about 200 nm, and are identified by XRD as single-phase multi-doped iron phosphate with a hexagonal structure. Further increase of pH value to 5.0 and 6.0 causes an excessive precipitation of nonferrous metal elements in the product, leading to a departure from stoichiometric ratio and presence of undesirable phases. The inexpensive metals-doped iron phosphate precursor for synthesis of lithium iron phosphate can be prepared from the steel slag.

Absorption Kinetics of CO2 in Aqueous Solutions of Secondary and Tertiary Alkanolamines

LI Wei-bin DONG Li-hu CHEN Jian

. 2011, 11(3): 422-428.

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The absorption rates of CO2 into aqueous solutions were measured with a wetted wall column. A secondary alkanolamine diethanolamine and two tertiary alkanolamines, triethanolamine and N,N-diethylethanolamine, were used in the experiments at various concentrations and temperatures. Their intrinsic reaction rate constants with CO2 are 7.71′1015exp(-8755.2/T) m3/(kmol×s), 9.63′1020exp(-13262.4/T) m3/(kmol×s) and 1.19′1028exp(-18231.3/T) m3/(kmol×s), respectively. It is determined that the absorption mechanisms of alkanolamines with CO2 are zwitterion mechanism in secondary alkanolamines and modified base-catalyzed hydration mechanism in tertiary alkanolamines.

Reduction Kinetics of Carbon-containing Pellets Made of Dust and Sludge under Weak Oxidizing Atmosphere

WEI Ru-fei LI Jia-xin LI Jie-min LONG Hong-ming WANG Ping GAO Gang LIN Gao-peng

. 2011, 11(3): 429-435.

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Reduction experiment of carbon-containing pellets made of dust and sludge under weak oxidizing atmosphere in the temperature range from 1348 to 1573 K was conducted. By studying its kinetics and analyzing reduction mechanism, it is found that the restriction step of the reduction rate of pellets is interfacial reaction or local reaction, and the activation energy 111.66 kJ/mol, and the reduction rate of pellets can be expressed by Mckewan equation 1-(1-R)1/3=kt. In addition, temperature is an important factor influencing reaction rate, dezincification and metallization rates increase with temperature rising. Dezincification and metallization rates attain the maximum 97.83% and 79.92% respectively at 1573 K, compared with the minimum 75.25% and 60.17% at 1348 K.

Proton Leakage through Anion-exchange Membranes in Bipolar Membrane Electrodialysis Process

ZHANG Li-ye; CONG Wei

. 2011, 11(3): 436-441.

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Proton (H+) leakage through anion-exchange membranes in bipolar membrane electrodialysis (BMED) process with three sodium salts was investigated. The results indicated that the proton leakage occurred during the whole BMED process with NaCl and Na2SO4 and caused the decrease of 3.02 in pH value of salt solution for Na2SO4 while the proton leakage and hydroxyl leakage successively occurred during the process with C6O7H5Na3. The proton leakage increased in the following sequence of Na2SO4>NaCl>C6O7H5Na3. As a result, compared with C6O7H5Na3, the average current efficiency of acid and base regeneration for Na2SO4 decreased 61.6% and 51.8%, but the energy consumption increased 67.8% and 36.2%, respectively. Based on the results, it was assumed that the unequal transport velocity between cations and anions was responsible for the proton leakage. The key to decrease the proton leakage was to accelerate the migration of anions.

Reaction Mechanism of Desilification Process of High Aluminum Fly Ash by Alkali Solution

DU Zi-chuan TANG Qing; BAO Wei-jun LI Shao-peng CAI Wei-quan

. 2011, 11(3): 442-447.

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The main mineral components and their contents in high aluminum fly ash, and the effects of reaction time and reaction temperature on the phase, morphology and surface chemical composition of fly ash before and after desilification were analyzed with several analytical instruments combined with thermodynamic stability analysis, and the reaction mechanism of desilification process discussed. The results show that the contents of Al2O3, SiO2 and Ga are 42.20%, 42.28% and 0.0062% separately, content of amorphous SiO2 is more than half of the total SiO2, desilification process by alkali dissolution can extract amorphous SiO2 in fly ash, and reaction temperature has an great influence on desilification, the extraction efficiency of SiO2 and Al2O3 amounts to 42.5% and 1.83% respectively under the conditions of 130℃ and 2 h. The desilification reaction at the temperature below 130℃ is between glass phase and NaOH, increasing temperature accelerates the dissolution of amorphous SiO2 and Al2O3 in glass phase. When temperature is above 130℃, increasing temperature causes the dissolution of mullite and corundum, but aggravates the formation of sodalite.

Effect of Liquid Nitrogen Addition on Synthesis of Poly(p-phenylene terephthalamide)

LU Yan-yan ZHANG Tao; QIAN Wei-zhong LUO Guo-hua TUO Xin-lin; WEI Fei

. 2011, 11(3): 448-451.

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A method to enhance the heat removal in the synthesis system of poly(p-phenylene terephthalamide) (PPTA) by adding liquid nitrogen was proposed. The phase transition of liquid nitrogen is effective to control the maximal temperature of the system below 2.5℃. The decreasing rate of temperature in the initial polymerization stage (2~11 min) is 1.3℃/min. Compared with the indirect heat removal by water-ice bath, this absorbs reaction heat in large amount and quickly, which is crucial to the temperature control for this highly exothermic reaction, especially for the scale up. In addition, the phase transition of liquid nitrogen provides the turbulent mixing of the reactants in the system, which improve the mass transfer and favors the increase in the quality of the product, evidenced by thermogravimetry, XRD and Raman spectroscopy. The viscosity of final product is up to 6.9 dL/g, suggesting its high quality.

Analysis of Land Utilization, Energy Consumption, Environmental Effect and Water Consumption in Production of Fuel Ethanol with Biomass

KONG De-zhu WANG Yu-chun SUN Jian YUAN Xiao-fan WANG Xiao-dong XIAO Jie ZHAO Bing

. 2011, 11(3): 452-460.

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By introducing the distribution ratio of feedstock, corn stalk, cassava and sorghum are analyzed in the four aspects of land utilization ratio, energy consumption, environmental gas emission and water consumption, and the reliable data obtained. The results show that corn stalk has the most promising prospect as the feedstock for production of fuel ethanol, its land utilization ratio is up to 563.40 GJ/ha (ethanol energy), whereas energy consumption is only 22.68 MJ/GJ (ethanol energy), its environmental impact is the most minimal among the three and water consumption is only 8 m3/GJ (ethanol energy). When viewed as a whole, sweet sorghum is better than cassava. But its water consumption is too large to be utilized for a long-term development.

Preparation of Highly Uniform Single and Double Emulsions with Microfluidic Chips Modified by Region-selective UV Irradiation

DING Rui; GAO Fei SU Zhi-guo WANG Ping; MA Guang-hui ZHANG Song-ping

. 2011, 11(3): 461-467.

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A novel region-selective hydrophilic modification approach by UV irradiation was used to change the surface property in PDMS-based microfluidic chip. The surface properties of microchannels before and after modification were characterized by contact angle measurement and atomic force microscope. Thereafter, microfluidic chip region-selectively modified by this method was applied to prepare highly uniform single and double emulsions. The results demonstrated that in the un-exposed region, original hydrophobic PDMS surface tended to be very coarse and hydrophobic with contact angle 101o after photoinitiator solution treatment. But in the UV-exposed region, poly(acrylic acid) was coated on the surface, leading to a hydrophilic surface with contact angle 62o. In addition, those hydrophilic and hydrophobic features were able to maintain at least for 30 d. Using the modified microfluidic chips, three kinds of highly uniform O/W single droplets, soybean oil, trimethylolpropane triacrylate and fluorocarbon oil, were prepared with coefficient variation (CV) below 3%. Uniform W/O/W double emulsions were also successfully prepared with CV of the outer and inner diameters at 3.5% and 2.9%, respectively.

Flocculation Process during Extraction of Water-soluble Polysaccharides from Spirulina

WANG Feng GU Zhi-guo YIN Xiao-yan

. 2011, 11(3): 468-474.

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A large quantity of small negatively charged particles exists in the hot water extraction from Spirulina. According to the mechanism of electrostatic neutralization, the cationic flocculants were applied in the treatment of the hot water extraction. The desirable flocculation rate, decoloration rate, protein removal rate and retention rate of total sugar obtained with the addition of PFS were 80.32%, 75.48%, 50.30%, 85.40% respectively. The variation of pH value of extract, time and temperature of operation did not influence the flocculation. Furthermore, the solution collected after flocculation was treated with alcohol, and the precipitate redissolved in water. The total sugar of total solid in the redissolved solution was 86.0%. Zeta potential of particles in the extract revealed that PFS could neutralize the surface potential of particles under acidic and neutral conditions, reduce the surface potential significantly under alkaline condition. The morphology displayed that the agglomeration of small particles in extract was promoted by the addition of PFS and the settleability of particles was improved.

Preparation and Controlled Release Properties of Emamectin Benzoate with Microcystis as Carrier

WU Ya-kun REN Tian-rui YAN Yun-feng WU Qing-hai WANG Quan-xi XU Wen-ping

. 2011, 11(3): 475-480.

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Emamectin benzoate (EB) delivery formulation was prepared using microcystis (MC) as carrier and carbopol resin as matrix. The chemical composition and morphology of MC were investigated. Furthermore, the kinetics of MC adsorption to EB and the formulation release were carried out. MC particles with an average size of 3.5 mm exist with many micropores and abundant functional groups on their surface which presented the considerable binding ability with the maximum sorption capacities of EB on MC 70.78 mg/g, and 1.1×109 EB molecules per capsule in ethanol/water (1:1, j) at 30℃. The cumulative release quantities of granules without coating film agent are 52.9% and 65.3% during 24 and 72 h respectively. These results suggest that MC may have potential for EB controlled release formulation.

Preparation of Molecularly Imprinted Nanoparticles for Erythromycin and Their Adsorption Characteristics

KOU Xing GENG Li-yuan LEI Jian-du MA Guang-hui SU Zhi-guo

. 2011, 11(3): 481-486.

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Uniform molecularly imprinted polymer (MIP) nanoparticles for erythromycin (EM) were prepared by precipitation polymerization using EM as template molecule, methacrylic acid (MAA) as functional monomer and ethylene glycol dimethacrylate (EGDMA) as cross-linker. The synthesis conditions of MIP nanoparticles were optimized and the optimum molar ratio of template molecule to functional monomer was obtained as 1:3. The MIP nanoparticles were characterized. Moreover, the actual maximum apparent adsorption capacity of MIP nanoparticles obtained from the binding experiments was 202.12 mg/g, the adsorption kinetics of MIP nanoparticles showed that the adsorption of MIP nanoparticles in adsorption solution would be equilibrium after 200 min. The MIP nanoparticles for EM possessed highly selective adsorption capacity.

Auto-fluorescent Mechanism of Chitosan Microspheres Crosslinked with Glutaraldehyde

SONG Chun-yan WANG Lian-yan; WU You-bin; ZHANG Jing MA Guang-hui ZHANG Xu

. 2011, 11(3): 487-491.

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A compound containing ?C==N?C==C? was synthesized by 2-methyl-2-crotonaldehyde and 2-amino-2-methyl propane. Its structure was confirmed by infrared spectroscopy and liquid chromatography-mass spectroscopy. And the results showed that a relatively pure compound was obtained. Furthermore, its fluorescent property was analyzed by fluorescence spectroscopy and laser scanning confocal microscope, which showed the same fluorescent property with chitosan microspheres. Therefore, the conjugating structure of ?C==N?C==C? was mainly attributed to auto-fluorescence of chitosan microspheres crosslinked with glutaraldehyde.

pH Value Feedback Controlling of Carbon and Nitrogen Source Feeding in Lysine Fermentation

TIAN Yuan ZHANG Yong SONG An-dong CONG Wei

. 2011, 11(3): 492-496.

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pH value was used as an indicator to feedback control the feeding of glucose, ammonia and ammonium sulfate in lysine fed-batch fermentation. Fed-batch fermentation was operated under different concentrations of carbon and nitrogen sources, such that mass consumption ratio of glucose, ammonia and ammonia sulfate reached 15.7:1:1.64. The mixed solution according to aforementioned ratio was mixed into fermentation broth so as to regulate the pH value, simultaneously achieving automatic refuel of carbon and nitrogen sources. The results showed that the fluctuation of glucose concentration was maintained between 8 and 16 g/L, and ammonium between 1.5 and 3.4 g/L by using pH feedback controlling method. Compared with intermittent feeding and constant substrate concentration feeding, this method resulted in an increase in the concentration of lysine by 3.6% and 17.2% respectively, in lysine productivity by 9.5% and 28.8% and in the conversion rate from glucose to lysine by 4.9% and 18.6%.

Preparation of Cu-based Catalysts for Methanol Synthesis in a Fluidized Bed Reactor and Their Performance

WANG Guo-gao ZUO Yi-zan HAN Ming-han WANG Jin-fu

. 2011, 11(3): 497-502.

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Five Cu-based catalysts were prepared by sodium carbonate coprecipitation with different promoter contents. These catalysts were evaluated and characterized by SEM, XRD, particle size distribution and attrition jet index (AJI). It was found that the incorporation of ZrO2 gave the catalyst higher attrition resistance AJI value reached 0.056, the catalyst showed relative good activity and stability, CO conversion rate was about 40% and no remarkable deactivation was seen after 260℃ reaction for 50 h. Al2O3 drastically decreased catalytic activity by reacting with copper and zinc compounds in catalyst, CO conversion rate was only 10%, the enhancement of attrition resistance was much less, with an AJI value 0.103. The catalyst with Cu, Zn, Zr as main components was suitable for methanol synthesis in a fluidized bed reactor due to its high activity, long time stability and good attrition resistance.

Preparation and Evolution Process of Dandelion-like Hierarchical Boehmite Particles

HAN Qiang WU Xiao-feng LIAO Yu-chao LI Dan YUE Ren-liang LIU Hai-di CHEN Yun-fa

. 2011, 11(3): 503-508.

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Hierarchical boehmite particles with dandelion-like morphology was synthesized in the hydrothermal condition using aluminum nitrate as Al3+ source, urea as precipitator and citric acid as structure directing agent, which was further transformed to g-Al2O3 product with the same morphology after simple heating post-treatment under 700℃ for 4 h. The crystal phase, morphology and microstructure of the samples were characterized. It is shown that the as-synthesized boehmite particles are 1 mm in diameter containing a solid interior with 500 nm in diameter and incompact outer shell formed by rod-shaped particles. The interesting dandelion-like structure evolution was further investigated by comparative experiments and a reasonable evolution mechanism was proposed, in which the boehmite samples tend to form spherical particles in the presence of citric acid, and rod-shaped particles can be produced when the citric acid is insufficient. The dandelion-like hierarchical boehmite particles are formed by rod-shaped particles adsorbed on the surface of the spherical particles.

Effect of Silicon Sources on the Shapes and Luminescent Properties of Zn2SiO4:Mn Phosphors Synthesized by Hydrothermal Method

XU Hai-ting XU Guang-qing ZHENG Zhi-xiang WU Yu-cheng

. 2011, 11(3): 509-513.

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Zn2SiO4:Mn phosphors were synthesized by hydrothermal method in stainless-steel autoclaves using both crystalline and amorphous SiO2 as silicon sources. The phase structures, morphologies, light absorption, and photoluminescence properties of the products were characterized. The results show that Zn2SiO4:Mn phosphor can be obtained by using the different silicon sources. With crystalline SiO2, monocrystalline Zn2SiO4:Mn can be obtained, and the shape of the products is hexagonal prism with the average length of 5~8 mm and diameter of about 0.8 mm. However, the products are polycrystalline Zn2SiO4 with the amorphous SiO2 as silicon sources. The average length of the particles is about 500 and 100 nm in diameter. Both of the two samples have strong absorption band with the wavelength from 200 nm to 250 nm, and the sample using crystalline SiO2 has an absorption band between 250 nm and 350 nm. Zn2SiO4:Mn phosphors using different silicon sources show a strong green emission with the wavelength at about 520 nm under 215 nm and 250 nm excitation, and the luminescent intensity of the sample using crystalline SiO2 is higher than that of the other one.

Photocatalytic Property of TiO2 Catalyst Doped with Cerium

ZHANG Hao QIAN Fu-ping

. 2011, 11(3): 514-518.

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Titanium dioxide sol was synthesized by sol-gel method with adulteration of Ce(NO3)3×6H2O. The samples were characterized by XRD, DTA and UV-Vis. The results show that the average diameter of Ce-TiO2 particles is 17.3 nm when the Ce-doped 1.5%(mol), is calcined at 500℃. From the UV-Vis spectra the absorption edge of Ce-doped titania has a red shift and the absorption intensities are increased. The degradation rate of formaldehyde reaches 38.75% when the dosage of photocatalyst is optimally 10 g/L and 240 min illumination is provided with an 80 W fluorescent lamp.

Preparation of Cold Ramming Paste for Aluminum Electrolysis Cell with Phenol-Formaldehyde Resin as Binder

TIAN Lin; ZHOU Yang-min XIE Gang HOU Yan-qing FANG Ning YANG Ni

. 2011, 11(3): 519-523.

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Cold ramming paste with the ramming temperature range of (20±5)℃ for aluminum electrolysis cell was prepared with phenol-formaldehyde (PF) resin as binder, electro-calcined anthracite and graphite as aggregate, which has good properties such as low electrical resistivity of 58.25 mW×m and high compressive strength (28.05 MPa). It is much better than that of some domestic factories, but a little better than foreign products through property tests. And the analytical results by IR and TG-DSC for the change of functional groups of PF resin at different carbonization temperatures, of mass and heat when heated show that the higher the carbonization temperature is and then the resin functional groups disappear more completely, finally PF resin can be condensed into higher degree of polymerization of aromatic ring. TG-DSC profile of cold ramming paste is very complex and can be divided into four stages.

Effect of Hydrophilic Chain Length on the Coal-Water Slurry Properties of Alkylphenol Polyoxyethylene Ether

SU Yi WANG Shi-bing ZHU Shu-quan

. 2011, 11(3): 524-528.

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The slurrying ability of alkylphenol polyoxyethylene (APEO), a coal water slurry (CWS) dispersant, was studied by viscosity analysis of CWS prepared with coal from five sources in the absence of stabilizer. The effect of EO number of APEO addictive on the dispersibility of CWS was examined. The results show that the slurrying ability of APEO changes with the polyoxyethylene adduct number (EO number) obviously. The minimum apparent viscosity of prepared CWS is observed when the hydrophilic-lipophilic balance value of APEO is 18.5±0.4, i.e., when the EO number of APEO lies in the range from 60 to 100. Slurrying ability decreases beyond this EO number range and the optimal EO number increases with the length of alkyl chain in different APEO. APEO with a short alkyl chain shows a small optimum EO number, and vice versa. The optimal EO number has been determined to be 60, 60, 70, 80, 90 and 100 for APEO with different alkyl carbon number values of 7, 9, 12, 14, 16 and 18, respectively.

Electrochemical Performance of the Amorphous Nickel Hydroxide Electrode Material Compounded with Carbon Nanotubes

LIU Chang-jiu XING Chun-xiao LI Pei-pei

. 2011, 11(3): 529-532.

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Amorphous nickel hydroxide powder as electrochemical active substance was prepared by microemulsion method. The powder was compounded with carbon nanotubes (CNTs) to be nickel electrode material, then its electrochemical properties tested. The results showed that the addition of CNTs not only effectively reduced the charge transfer resistance of nickel electrode, but also increased the proton diffusion coefficient. The sample containing 0.5%(w) CNTs showed good performances at a high charge-discharge rate, it had the specific discharge capacity 336.5 mA×h/g and the discharge middle voltage at 1.251 V at 1 C rate. The discharge capacity retention rate was 96.74% after 30 times cycles.

Advances in Analysis and Assessment of Energy Consumption in Steel Plants

ZHANG Wen-juan WANG Bao LIU Qing CANG Da-qiang YANG Zhen-guo LI An-gui ZHAI Liao-kuo

. 2011, 11(3): 533-540.

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Influential factors, such as development of process technology, evolution of manufacturing process structure, application of waste heat and energy recovery technology, on energy consumption in steel plants are summarized. Moreover, evolution of analysis and evaluation methods are reviewed, which indicates that analysis of energy consumption (AEC) based on mass flow system focuses on improvement of mass flow condition and each procedure process, while AEC based on energy flow system concentrates on matching of energy supply and demand, matching of energy-level between different energy subsystems. Meanwhile, the research scope on energy consumption has been extended to the upstream and downstream link of steel manufacturing process with life cycle analysis, which contributes to system energy saving. The advantages and disadvantages of current evaluation benchmark of energy consumption, including theoretical minimum value, actual minimum value, optimum value and world (region) best practice value, as well as field of their applications are discussed. Based on these, combined with reliability of general system, energy reliability assessment and its further research in steel plants are presented, which is used to explore the energy saving potential of raw material condition, product structure, maintenance system and operating level for precise control of energy consumption.

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