Table of Content

20 June 2013, Volume 13 Issue 3

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流动与传递

Structural Design and Optimization of Submerged Nozzle in Rectangular Molten Steel Casting Mould

ZHANG Cai-jun SUN Xue-yu SHI Jing-pei LIU Tao ZHU Li-guang

. 2013, 13(3):  361-367. 

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A rectangular continuous casting machine in a company is taken as the research subject. Combined with numerical simulation and physical simulation, the liquid steel flow behaviors and temperature distribution in the mold are systematically analyzed. The liquid steel flow field and heat flux distribution are calculated respectively at different outlet rake angles, immersion depths and casting speeds. The corresponding technological parameters are optimized as well. It is demonstrated that the best structure of submerged nozzle for 150 mm×330 mm rectangular cast bloom is the side opening for a runway shape with 30 mm inner diameter and 25° side opening angle.

Characteristics of Chaotic Dynamic Structure Catastrophe of Instantaneous Pressure Signals in a Kenics Static Mixer

YU Yan-fang XIONG Qiang MENG Hui-bo WANG Feng WU Jian-hua

. 2013, 13(3):  368-373. 

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In order to find out the dynamic structural catastrophe of chaotic flow in the vertical upward flow of Kenics static mixer (KSM), the dynamic structure exponents of pressure fluctuation signals in different segments at both left and right sides of the catastrophe points were analyzed based on dynamic exponent segmentation algorithm in turbulent regime with Re=1756~3512. The dynamic structural exponents were discussed under different flow rates and the largest statistic value of dynamic structure exponents Tmax was used to quantitatively characterize the catastrophe features of the complex flow in the KSM. The results showed that Tmean of pressure fluctuation signals increased with increasing of Re for Re≤2107. Because the tube wall strengthened the restrictive function for fluid turbulence, the dynamic structure differences of the fluid tended to become stable for Re≥2458. The effect of radial secondary flow on the complexity of dynamic structural difference in the vortex center was 2~3 times than that near the wall. The dynamic structure produced by axial cutting split-flow was 8~10 times than that by displacement mixing action. The method of pressure fluctuation signals dynamic exponent could well explore instantaneous catastrophe structure of the flow in KSM.

Experimental Research on the Hydrodynamic Cleaning Reciprocating-spiral Technology in Natural Circulation Evaporators

YU Tian-lan LIU Yang-ping YU Tian-xiang SHI Bing-le CHEN Li FENG Xiu-yan ZHANG Zhi-kun

. 2013, 13(3):  374-377. 

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To solve the problems of severe fouling and high energy consumption of forced circulation in evaporators, a hydrodynamic reciprocating-spiral cleaning technology used for natural circulation evaporator was demonstrated. Its cleaning mechanism consists of a reciprocating spring with small elasticity coefficient and fouling removal spiral inserted in each heating tube. Relying on the pulsation of vapor-liquid flow, the fouling removal spiral generates reciprocating vibration for uniform descaling purpose. Atmospheric evaporation test rig with 6 heating tubes is designed to study the spring and spiral of different structure parameters, in which water and steam flow through heating tubes. The optimized parameters of the spring and spiral and the correlation charts between the reciprocating stroke of fouling removal spiral, circulation velocity and heat transfer temperature difference are obtained. The experimental results show that when the elasticity coefficient of the reciprocating spring is 7.0~8.0 N/mm, and ratio between the pith of fouling removal spiral and inner diameter of the tube 0.676~0.764, and heat transfer temperature difference greater than 18℃ under atmospheric evaporation with the heating tube with the outer diameter of 38 mm, wall thickness 2 mm and tube length 2 m, the circulation velocity is not lower than 0.57 m/s, and the reciprocating stroke of the fouling removal spiral is greater than a pith, which meets the needs of uniform scale removal.

反应与分离

Enrichment of Low Grade Reduced Titanium Slag by H3PO4 Activation Roasting and Acid Leaching

ZHONG Bin-nian XUE Tian-yan HU Guo-ping CHEN Wei-liang WANG Li-na QI Tao

. 2013, 13(3):  378-384. 

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Titanium-containing slag produced by coal-based DR-EAF smelting was used and enriched by H3PO4 activation roasting and acid leaching, the phase components in the slag included anosovite, pyroxene (glass), Taki stone and spinel. The crystalline transformation of the slag during the roasting process was studied at different roasting temperatures and times, and H3PO4 mass content. The effects of acid leaching temperature, sulfuric acid concentration, mass ratio of liquid to solid and leaching time on the leaching rate of main impurities such as Ca, Mg, Al and Si were examined. The optimal conditions obtained were: roasting temperature 1273 K, roasting time 100 min, H3PO4 content 7.1%, acid leaching temperature 110℃, sulfuric acid concentration 5%, mass ratio of liquid to solid 10:1 and leaching time 120 min. Under the optimal conditions, the content of TiO2 in the slag was raised from 52.54% to 68.31%.

Lignocellulosic Dissolution and Component Separation in NaOH-Thiourea-H2O System

ZHANG Li XU Jian-guo ZHANG Long

. 2013, 13(3):  385-390. 

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The dissolution of sawdust in alkaline solvent system NaOH-thiourea-H2O was studied, and the separation of the lignocellulosic ingredients combined with acid precipitation method proposed. The results showed that the main residue after the treatment in alkali solvent was lignin, and the filtrate from acid precipitation of the liquor cellulose. The optimal dissolution conditions were determined by single-factor experiments as follows: the ratio of liquid to solid 30 mL/g, dissolution temperature 70℃, and dissolution time 2.0 h. FT-IR, SEM, XRD and NMR were employed to identify the structure of separated components, the dissolution rate could achieve 60.3%, and cellulose yield after acid precipitation about 39.2%.

Leaching Behavior of Diaspore Bauxite in KOH Sub-molten Salt

MA Qing-xia ZHANG Yi-fei CAO Shao-tao WANG Shao-na

. 2013, 13(3):  391-396. 

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The leaching behavior of diaspore bauxite in KOH sub-molten was investigated. The effects of reaction temperature, mass ratio of alkali to ore, initial KOH solution concentration, reaction time and CaO addition were examined. The results indicate that the recovery rate of Al2O3 can reach 81.4% and mass ratio of Al2O3 to SiO2 of the red mud decreases to 1.06 under the optimum conditions of reaction temperature at 220℃, mass ratio of alkali to ore at 1.5, initial KOH solution concentration of 50%(w) and reaction time for 1h. The XRD analysis shows that Si exists in the form of KAlSiO4 in the red mud. Further study implies that CaO addition is not beneficial to the leaching process. A further step for extraction of K2O and Al2O3 in the red mud achieves good results with 0.61% of K2O, 8.09% of Al2O3 in the final red mud and 90.7% of Al2O3 overall leaching rate.

Macro-kinetic Investigation on the Oxidative Pressure Leaching of Chromite Ore with Sodium Hydroxide Solution in the Presence of Oxygen

ZHANG Hai ZHANG Xiao-fei XU Hong-bin ZHANG Yang WANG Shao-na

. 2013, 13(3):  397-402. 

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The effects of leaching conditions on chromium extraction rate were investigated in the oxidative pressure leaching process of chromite ore with sodium hydroxide solution, including particle size, stirring speed, NaOH-to-ore ratio and temperature. The results showed that the extraction rate of Cr reached above 98% after 300 min at 250℃ with NaOH concentration of 60%(w), oxygen partial pressure of 3.2 MPa, particle size below 50 mm, stirring speed of 650 r/min and mass ratio of NaOH to ore 4.0:1. And the chromium extraction rate increased with the decrease of ore particle size and the increase of stirring speed, mass ratio of NaOH to ore and temperature. The macro-kinetic investigation revealed that the leaching process was controlled by reactant diffusion in the solid product layer and described by 1-2/3X-(1-X)2/3=kt with apparent activation energy of 54.5 kJ/mol and pre-exponential factor of 328.4 min-1.

Mineral Phase Change of High-alumina Fly Ash during Desilication and Extraction of Al2O3 by Alkali Dissolution Process

SUN Zhen-hua BAO Wei-jun TANG Qing; HUI Jun-bo WANG Chen-ye LI Hui-quan;

. 2013, 13(3):  403-408. 

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The high-alumina fly ash solid-phase change in the desilication and dealuminization reactions in alkaline solution was investigated by chemical analysis, XRF, XRD, laser particle sizer, SEM and FT-IR. The results showed that after the desilication and alkali dissolution reactions, the leaching rate of alumina reached up to 85%, Al2O3/SiO2 mass ratio decreased in the tailings, as a result the alumina and silica were selectively separated in the desilication reaction, mullite and corundum phases remained unchanged, meanwhile, amorphous aluminosilicate glass was transformed into sodalite phase Na8Al6Si6O24(OH)2(H2O)2, which adhered the ash particle surface, as a result the particle size increased and the particle surface became coarse. After alkali dissolution reaction, mullite and corundum phases were transformed to NaCaHSiO4 and 1.2Na2O×0.8CaO×Al2O3×2SiO2×H2O phases, the particle size decreased.

Removal of Tin from Tin-bearing Iron Ore with Sulfidation Roasting

LI Lei LIAO Bin WANG Hua HU Jian-hang QIU Zai-jun SANG Xiu-li

. 2013, 13(3):  409-414. 

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Based on the thermodynamic analysis, the removal process of tin from tin-bearing iron ores was studied by chemical and X-ray diffraction analysis. The results showed that raising roasting temperature and prolonging holding time were beneficial to increasing of the tin removal rate in a certain range. However, when the temperature increased above 1473 K, the calcium ferrite was cohesive, causing the unreacted tin-bearing particles being enclosed and tin removal rate being decreased. With increasing of addition of pyrite and anthracite, the tin removal rate increased first and then deceased. The tin content in the tin-bearing iron ore was decreased from 0.35% to 0.05% under the conditions of holding time 60 min, pyrite addition amount 5%(w), anthracite addition amount 5%(w), and N2 flow rate 15 L/h. Tin could be removed effectively from tin-bearing iron ore by sulfidation roasting.

过程与工艺

Phase Structure of Decarburized Product from High-carbon Ferrochrome Powder Added with Calcium Carbonate by Microwave Heating

WANG Long CHEN Jin HAO Jiu-jiu LIN Wan-ming LI Kai DENG Yong-guang

. 2013, 13(3):  415-423. 

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Medium and low-carbon ferrochrome powder containing CaO was obtained by fast solid-phase decarburization of high-carbon ferrochrome powder with CaCO3 by microwave heating. High-carbon ferrochrome powder with calcium carbonate was decarburized at 900, 1000, 1100, 1200℃ for 60 min. The carbon content of decarburized material was measured. The microstructure and phase composition of this new metallurgical material were studied by metallography, electron probe and XRD phase analyzers, the carbon content and phases change during the solid-phase decarburization were also analyzed. The results show that carbon content of high-carbon ferrochrome powder was 5.06%, 2.24%, 1.71% and 1.39% at 900, 1000, 1100 and 1200℃. Compared with original carbon content of 8.16%, it was obviously reduced during the decarburization, carbon-rich carbide phase (Cr,Fe)7C3 changed gradually to metal-rich carbide phase (Cr,Fe)23C6 and ferrochrome ferrite phase CrFe; Coarse grain structure (Cr,Fe)7C3 changed to honeycomb dissolution structure (Cr,Fe)23C6 and granular encroach structure CrFe. Chromium oxides in the decarburized material were mainly Cr2O3, CaCr2O4 and CaCr2O7. Generally, the optimum conditions of solid phase decarburization were decarburization temperature of 1100℃ and 60 min heating.

Experimental Study on Magnetic Separation and Reduction of Stainless Steel EAF Dust

LI Xin-lin LIU Xu-long LI Wen-cai CHEN Fa-tao LI Yi LI Qiu-ju HONG Xin

. 2013, 13(3):  424-429. 

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Based on the analysis of physicochemical properties of stainless steel EAF dust, the possibility of reducing the impurity (Ca, Mg, O) content in the dust by magnetic separation and reduction process was studied. The results show that the production rate of final magnetic material was 37.39%, total Fe grade up to 53.66%, and the content of main impurities, CaO and MgO, 11.61%, after the treatment of magnetic separation-reduction-magnetic separation. Adding a certain amount of Fe and Cu powder, it could be used as raw material of iron based powder metallurgy friction materials. In comprehensive consideration of production rate of magnetic material, TFe grade and decalcification effect, the suitable magnetic field intensity was in the range of 60~90 mT.

Isothermal Kinetic Analysis on Carbothermal Reduction of Ferrum Niobate

YANG Yong LI Jie LI Bao-wei ZHANG Bang-wen HAN Ji-cheng

. 2013, 13(3):  430-435. 

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On the basis of thermodynamic analysis, the intermediate and finial products of carbothermal reduction of ferrum niobate were determined by XRD analysis. Ferrum niobate with carbon was heated from room temperature to 1170, 1230, 1290 and 1320℃ respectively for 40 min at the heating rate of 35℃/min in Ar, and thermogravimetry (TG) and differential scanning calorimetry (DSC) curves were obtained with a thermogravimetric analyzer. The kinetic parameters of carbothermal reduction reaction of ferrum niobate were calculated from TG curves by isothermal kinetics method, and the controlling step of reaction was ascertained. The results showed that the apparent activation energy of carbothermal reduction reaction of ferrum niobate was 482.7 kJ/mol, and the kinetic equation [(1-α)-1/3-1]2=kt (Z-L-T equation), which was controlled by the three-dimensional diffusion. From that the reaction rate was controlled by product layer diffusion except in the initial stage of reaction, namely, the controlling step of carbothermal reduction reaction of ferrum niobate was the internal diffusion of CO gas in production layer.

Synthesis of Ammonium Alum from Lipoic Acid Plant Wastewater by Crystallization

HUANG Yan-hua WANG Jian-hao YAO Zhi-yuan SONG Guo-qiang ZENG Gui-feng ZHOU Yong-sheng GU Yue WANG Che-li

. 2013, 13(3):  436-441. 

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Aluminum-containing wastewater was used to synthesize ammonium alum by crystallization. The effects of time, NH4+/Al3+ molar ratio, SO42-/Al3+ molar ratio, temperature and stirring speed on the aluminum alum formation and aluminum ion removal rate were studied. The synthesized and commercial ammonium alum products were characterized, they had almost identical crystal structure, morphology and chemical composition. The optimum conditions of efficient crystallization process were recommended: operation time of 8 h, NH4+/Al3+ of 1.40, SO42-/Al3+ of 2.90, temperature of 5~15℃ and stirring speed of 35~55 r/min. The synthesis reaction kinetics experiments were performed. The results show that Al3+ diffusion in the boundary layer is the rate controlling step in the crystallization process. The relationship between Al3+ concentration (C) and time (t) is expressed by C=(C0-Ci)e-kt+Ci. The effect of stirring speed on the particle size distribution of ammonium alum crystals was investigated. When the stirring speed is lower, ammonium alum average particle size is larger and size distribution wider. With increasing of stirring speed, the particle size and distribution range are decreased.

Preparation of Calcium Vanadate by Calcification of Potassium Orthovanadate

ZHAO Chu ZHENG Shi-li WANG Shao-na DU Hao YANG Na

. 2013, 13(3):  442-446. 

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A method to recycle the potassium in the potassium orthovanadate salt produced in sub-molten salt treatment of vanadium slag was proposed, and calcium oxide taken as an effective reagent to provide calcium ion, replacing the potassium in the salt. Potassium vanadate calcification conditions were systematically investigated, and the optimal operation parameters influencing the calcification efficiency obtained. By controlling the KOH concentration at 140 g/L, CaO excessive coefficient 1.2, and reaction temperature 90℃, 95.9% of potassium vanadate was calcified in 2 h, leading to formation of Ca10V6O25 precipitate, which could be used in production of steel alloying material ferrovanadium directly. And the potassium could be recycled in the form of potassium hydroxide, which was the major component for the vanadium slag decomposition using sub-molten salt media.

Kinetic Mechanism for Pyrolysis Process of Cotton Stalk by Double Extrapolation Method

WANG Xin-yun WAN Xin-jun CHEN Ming-qiang WANG Jun

. 2013, 13(3):  447-450. 

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The pyrolysis process of cotton stalk was studied in nitrogen atmosphere by using the thermogravimetric analysis. The kinetic mechanism of the process was determined and corresponding kinetic parameters were calculated by double extrapolation method. Thermogravimetric analysis results show that the pyrolysis process can be divided into three stages: evolution of water (<150℃), devolatilization (200~400℃) and carbonization (>400℃). The kinetic analysis results show that Jander equation G(a)=[1-(1-a)1/3]2 and Z-L-T equation G(a)=[1/(1-a)1/3-1]2 are the most probable mechanism functions when the degree of conversion a is in the ranges of 0.15~0.4 and 0.7~0.9 respectively, which indicates that the primary pyrolysis process is three-dimensional diffusion.

系统与集成

Prediction of Blast Furnace Gas Output in a Steel Complex Based on PNN-HP-ENN-LSSVM Model

LI Hong-juan WANG Jian-jun WANG Hua MENG Hua

. 2013, 13(3):  451-457. 

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Aimed at the difficult problem of accurate prediction on blast furnace gas output in an integrated iron and steel works with mechanism models available, by analyzing the gas output using probabilistic neural network (PNN) for classification according to various conditions and characteristics of probabilistic neural network, HP filter, Elman neural network (ENN) and least squares support vector machine (LSSVM), a PNN-HP-ENN-LSSVM model was established. The simulation results using the practical gas consumption data in an iron and steel complex showed that for 80 sites in 1# blast furnace, 60 sites in 2# blast furnace, the classification accuracies of 95%, and 93% were tested respectively. Then a forecasting model was founded based on the classification results to predict gas output, the average relative errors of 1.0% and 1.1% were obtained, the PNN-HP-ENN-LSSVM model was more suitable for blast furnace gas output prediction than other methods. And the Wilcoxon symbol rank test also proved the validity of the combined classification method.

生化工程专栏

Preparation of Growth Hormone-releasing Peptide-6 Loaded PLGA Microspheres by Premix Membrane Emulsification

HE Fan QI Feng WU Jie SU Zhi-guo

. 2013, 13(3):  458-465. 

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Poly(lactic-co-glycolic acid) (PLGA) microspheres were prepared by premix membrane emulsification. The final optimum conditions for their particle size and size distribution were obtained: transmembrane pressure 5 kPa, concentration of poly(vinyl alcohol) in water phase 19 g/L and volume ratio of oil phase to water phase 1:10. The mean particle size of microspheres prepared under the optimal conditions was about 24 mm with Span value below 0.7. Furthermore, growth hormone-releasing peptide-6 loaded PLGA microspheres were prepared. The encapsulation efficiency of GHRP-6 loaded microspheres reached 85% under the concentration of Arlacel 83 2.5 g/L and concentration of NaCl in external water phase 10 g/L. Primary emulsion method had significant effect on both encapsulation efficiency and in vitro release profile. The microspheres prepared by ultrasonication showed compact interior structure with high encapsulation efficiency but slow as well as incomplete drug release; in comparison, the microspheres prepared by homogenization exhibited loose structure with decreased encapsulation efficiency and constant drug release.

Preparation of Uniform-sized Porous PELA Microspheres and Their Pore Size Control

ZHANG Hui-xia WEI Yi WANG Yu-xia RUAN Yan-ye MA Guang-hui

. 2013, 13(3):  466-473. 

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Uniform-sized poly(ethylene glycol-co-lactide) (PELA) microspheres were prepared by a combined method of solvent evaporation and Shirasu porous glass membrane emulsification at room temperature with dichloromethane as oil phase. The results show that the suitable conditions to prepare the larger pore size and uniform-sized PELA microspheres are: stirring speed 250 r/min, PELA concentration in oil phase 50 g/L, volume ratio of water/dichloromethane/PVA solution 1:2.5:25, and molecular weight ratio of monomethoxy-poly(ethylene glycol) to poly(lactide acid) 1:14. The average pore size of final microspheres is 15 nm, belonging to the mesoporous material, which can be used as drug carrier to adsorb protein or peptide drugs.

Preparation and Characterization of Self-assembled Thermo-sensitive Micelles Encapsulated with Methotrexate

SUN Fei-long WANG Yu-xia CHENG Gang WEI Yi MA Guang-hui

. 2013, 13(3):  474-480. 

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Thermo-sensitive micelles encapsulated with methotrexate (MTX) were prepared using poly(isopropylacrylamide- co-acrylamide)-b-poly(n-butyl meth acrylate) block copolymers by dialysis method. The effects of trans-membrane times, frequency of replacing dialysis medium, dialysis duration and pre-added water content on their size distribution, and the effects of mass ratio of MTX to block copolymer, temperature and dialysis medium on their encapsulation efficiency were investigated. The lower critical solution temperature (LCST) of micelles was determined. Their size distribution and shape were observed. The results showed that under the optimized conditions of mass ratio of drug/block copolymer 1:10, dialysis medium pH 6.8 phosphate buffer solution, and frequency of replacing dialysis medium each 1 h for the first 12 h, twice for the later 12 h each day at 4℃ for 3 d, the average size of micelles was 190±15 nm with polydispersity index 0.16, and drug encapsulation efficiency 15.0%. The final micelles were spherical with a core-shell structure and their LCST was around 41℃.

Preparation and Characterization of Hollow Polyurethane Nanofiber and Its Application in in-situ Encapsulation of Enzyme

JI Xiao-yuan WANG Ping; SU Zhi-guo MA Guang-hui ZHANG Song-ping

. 2013, 13(3):  481-487. 

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Hollow polyurethane (PU) nanofiber was prepared by co-axial electrospinning with glycerol containing certain content of water and PU dissolved in organic solvent as internal and external phase electrospinning solutions, respectively. The effects of the solution composition and flow rate, and diameter of co-axial spinneret on the morphology, mechanical strength and surface wetability of the nanofiber were investigated. The results showed that uniform hollow PU nanofiber was successfully fabricated by co-axial electrospinning glycerol containing 5%(j) water and N,N-dimethylacetamide solution of 30%(w) PU as internal and external phase electrospinning solution under the conditions of the solution flow rates of 0.07 and 0.5 mL/h, voltage 17 kV, distance between spinneret and collector 25 cm, temperature 25℃, and humility 10%. Hollow PU nanofiber prepared under above conditions had membrane tensile strength of 3.9 MPa and elongation at break of 332.8%, and contact angle with water of 100.2o. By dissolving definite amount of horseradish peroxidase (HRP) in the internal phase electrospinning solution, the enzyme was in-situ encapsulated inside the hollow channel of PU nanofiber. The kinetic biocatalytic activity of encapsulated HRP showed that an activity recovery rate of 80% was obtained, and similar Michaelis-Menten constant, Km, was observed for the free and encapsulated HRP. Thermal stability of HRP showed that the half-life of HRP at 60℃ was prolonged about 17 times after encapsulation.

Preparation of Instant Soluble Maca Powder and Its Capability

LIANG Chen WANG Qing-ting ZHOU Hui WANG Li-wei ZHAO Bing

. 2013, 13(3):  488-493. 

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Maca dried plates were used as raw material. Based on the effects of different extraction methods, dry methods and drying auxiliary drying agents on the product yield and nutrition composition, ultrasonic extraction and malt dextrin as spray drying auxiliary drying agent were utilized to prepare instant soluble maca powder. The optimal conditions were obtained as follows: ultrasonic power 600 W, ratio of solid to liquid 1 g/25 mL, ultrasonic temperature 50℃, duty ratio 1:1 and ultrasonic time 40 min, under the conditions, the extraction rate of total soluble solid was 52.0%. Under the drying conditions of mass ratio of maca soluble solid to drying auxiliary drying agent 1:1, soluble solid content in the feed liquid 0.1 g/mL, hot air temperature 220℃, feed temperature 56℃, feed flux 17.46 mL/min, and hot air flux 5 m3/min, the yield of instant soluble maca powder was 58.7%, the granularity of powder 2.1 mm, and the solution time 2.4 s. Auxiliary drying agents could inhibit the hygroscopicity of maca powder.

Pretreatment of Refractory Gold Ore by a Moderate Thermophilic Consortium in Stirred Tank Reactor

WU Jun-zi ZENG Wei-min WANG Yu-guang ZHANG Li-juan WAN Li-li ZHOU Hong-bo

. 2013, 13(3):  494-499. 

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A moderate thermophilic consortium was enriched from acid mine drainage and coal mine wastewater samples collected in China. After adaptation to gradually increased pulp density of arsenic-bearing refractory gold ore and concentration of arsenic by serial sub-culturing for about two years, its tolerance ability was up to 200 and 8 g/L, respectively. After that, the consortium was employed to treat arsenic-bearing refractory gold ore to evaluate its ability and potential for industrial application. The results indicated that the maximum cell density was 2′109 mL-1 (the 14th day) during the whole process and arsenic extraction rate reached up to 59.93% in 22 d. Microbial diversity monitored by restriction fragment length polymorphism suggested that the consortium mainly consisted of four species, Sulfobacillus sp., Acidithiobacillus caldus, Ferroplasma thermophilum and Pseudomonas sp.

Desalination of Glutamate Fermentation Wastewater by Electrodialysis

YANG Wen-long WANG Qian YANG Peng-bo CONG Wei

. 2013, 13(3):  500-504. 

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Electrodialysis was used to desalinate inorganic salts from a glutamic acid fermentation wastewater, and activated carbon to pretreat the wastewater. The electrodialysis performance of wastewater before and after pretreatment was examined. The results show that when the wastewater was pretreated at 60℃ for 30 min at the initial activated carbon concentrations of 100 and 200 g/L respectively, the decolorization rate of wastewater was 61% and 75%. In the electrodialysis process of wastewater pretreated without and with 100 and 200 g/L of activated carbon, the removal rate of lactic acid was sequentially reduced, glutamic acid removal rate was 24%, 35% and 39%, sulfate ions removal rate 77%, 80% and 84%, and ammonium ions removal rate 89%, 86% and 84%, the resistance of membrane stacks increased as well. When sulfate ion removal rate was 85%, energy consumption was 4.88, 3.93 and 3.64 kW×h/kg, respectively.

材料工程专栏

Preparation of Benzofuran-Indene Resin by Coke-oven C9 Polymerization with Chloroaluminate Ionic Liquid as Catalyst

LUO Guo-hua XU Xin

. 2013, 13(3):  505-511. 

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The polymerization reaction of activity components in coke-oven C9 by chloroaluminate ionic liquid as catalyst was examined. And the polymerization reaction mechanism and the influences of impurities, such as phenolic and basic nitrogen compounds in coke-oven C9 fraction, on the polymerization catalytic activity of [Et3NH]Cl-2AlCl3 catalyst were studied by the pyridine and acetonitrile adsorbed FT-IR. The polymerization reaction conditions of initial temperature and dosage of the catalyst were also investigated. The results show that the phenolic and basic nitrogen compounds are poisonous substances which lead to reducing the ionic liquid catalytic activity, therefore, they must be removed. The Br?nsted acid of [Et3NH]Cl-2AlCl3 exhibits a high catalytic activity used in the polymerization reaction of benzofuran with indene. Under the reaction conditions of ionic liquid addition 1.0%(w), air pressure, and initial reaction temperature 45℃, the reaction is completed in 10 s, and the conversation rates of benzofuran and indene are almost up to 100%, and high quality benzofuran-indene resin with softening temperature over 130℃ and color number 2# is obtained.

Reactivity and Post-reaction Properties of Coke and Their Measurement

GUO Rui WANG Qi ZHAO Xue-fei SUN Jia-fu

. 2013, 13(3):  512-518. 

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Based on the analysis of imperfection of coke reactivity index (CRI) and coke strength after reaction (CSR) in stimulation of coke thermal properties in blast furnace, CRI and post-reaction thermal properties (PRTP) and their detection methods are developed, including coke solution loss reaction starting temperature, solution loss rate and post-reaction strength in a given solution loss extent, post-heat treatment index and post-heat treatment strength. By analyzing the CRI, CSR and CR-PRTP of seven blast furnace coke samples, the results indicate that the cokes are quite different in the reaction starting temperature, at most, the gap between them is 44℃. The CSR of coke D is 74.1%, but the higher CSR is duo to the lower CRI, so it is more profitable for post-reaction strength in a given solution loss extent to evaluate the ability of coke to resist solution loss degradation. Compared with post-reaction strength in a given solution loss extent, post-heat treatment strength of coke A is decreased by 7.1%. The analysis and comparison indicate that it is available to evaluate the thermal properties of coke with CR-PRTP.

Preparation and Characterization of Heat Insulating Coating for Thermal Batteries

YANG Song-feng LI Yun-wei ZHU Yong-ping

. 2013, 13(3):  519-524. 

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Zirconia spheres were prepared as heat insulating filling by hydrothermal method, for increasing the heat-shielding performance, naphthalene nuclei were introduced into novolac epoxy resin which was used as matrix. Four samples with different contents of zirconia spheres were prepared to test their mechanical and heat-shielding properties. The experimental results indicate that the zirconia spheres are hollow spheres with around 500 nm diameter and coarse surface. The decomposition temperature of novolac epoxy resin is around 370℃. The suitable addition of zirconia hollow spheres in heat insulating coating for thermal batteries is 50%~60%(w). With 50%(w) zirconia hollow spheres, at room temperature, the tensile strength of heat insulating coating is 21.6 MPa, its shear strength 11.4 MPa, and thermal conductivity 0.05 W/(m×K), and at 300℃, its shear strength is 3.1 MPa, and thermal conductivity 0.04 W/(m×K).

Synthesis of Gold Nanoparticles in [Bmim]FeCl4 and Their Catalytic Properties

ZHANG Shu-heng ZHANG Xiang-ping SHEN Peng CHEN Fei-xiong

. 2013, 13(3):  525-530. 

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Au nanoparticles were synthesized by reducing chloroauric acid with oleylamine in 1-butyl-3-methylimidazolium tetrachloroferrate ([Bmim]FeCl4). Their morphology was investigated by TEM, and their catalytic properties on the reduction of 4-nitrophenol by NaBH4 were studied. The results reveal that the size and shape of particles are mostly determined by the molar ratio of [Bmim]FeCl4 to oleylamine. Au nanoparticles change from branched shape to flake one while the ratio increases from 0.5 to 2. Branched nanoparticles show improved catalytic activity compared with flake-shaped nanoparticles.

Synthesis of SnO2 Powder Doped with Rare Earth Elements by Hydro-thermal Method and Its Gas Sensing Properties towards Ethanol

SONG Jin-ling GUO Guan-ming ZHOU Zhang-cai MOU Lian-wei CAI Ying ZHANG Yin

. 2013, 13(3):  531-535. 

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SnO2 and rare earth-doped SnO2 powders were prepared by hydro-thermal method. Their structures and gas sensing properties were characterized by XRD and gas sensing instrument, respectively. The results show that the prepared SnO2 powder exhibits tetragonal rutile structure and rare earth ions doping do not change its crystalline structure without formation of new phases. Its gas sensing results show that SnO2:La exhibits better sensitivity towards ethanol. The gas sensing mechanism is analyzed. In addition, the corresponding sensitivity of SnO2:La increases with increasing of ethanol concentration and fluctuates with rising of temperature. The sensitivity of SnO2:La towards 1.00′10-4 ethanol obtains 101.1 at 250℃, which is the best. The response time and recovery time are about 5 s under the condition.

Effect of Laser Power on Microstructure and Wear Resistance of Fe-based Remelted Hot Sprayed-welding Layer

HONG Yong-chang SHAN Jun-zhan

. 2013, 13(3):  536-540. 

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Microstructure change of Fe-based hot spray-welding layers remelted by different laser power under same process conditions was studied by optical microscope and XRD. The results show that the microstructure of Fe-based hot sprayed-welding layer is coarse. After laser remelting at different laser powers, the microstructure of hot sprayed-welding layers is refined to some extent. By comparison, the quicker the laser power, the finer the microstructure of remelted sprayed-welding layers. The microstructure of Fe-based remelted hot sprayed-welding layer is composed of matrix phase of g-(Fe,Ni) solid solution and precipitate phases of Cr7C3, Cr23C6 and Cr2B, etc. Hardness and wear resistance of hot sprayed-welding layers are improved greatly after laser remelting at different laser powers, and the higher the laser power, the more prefect the remelted sprayed-welding layers become. The hardness and wear resistance are increased almost by 16% and 55% respectively compared with unremelted hot sprayed-welding layer.