Table of Content

20 December 2014, Volume 14 Issue 6

Previous Issue    Next Issue

流动与传递

Research on Apparent Viscosity Characteristics of Gas-Solid Dense Phase Fluidized Bed with Falling Spheres Method

LIANG Ke-yan TAO Xiu-xiang HUI Peng-yue

. 2014, 14(6):  901-906. 

Asbtract ( )   PDF (244KB) ( )  

Related Articles | Metrics

Based on falling spheres method the apparent viscosity in gas-solid dense phase fluidized bed was measured under different parameters. The relationships of yield stress and plastic viscosity of fluidized bed layer with influential factors were correlated. The effect of viscosity on separation time was studied, and the mathematical model on the relationship of separation time with the apparent viscosity and the density of fluidized material in the vibration fluidized bed developed. The results showed that under the same gas velocity, with the increase of quartz sand grain size and bed height, the apparent viscosity increased totally. Within a certain range of the fluidizing gas velocity, the apparent viscosity was 0.39~0.51 Pa×s when the quartz sand size was 0.25~0.125 mm and the bed height 190 mm. After the exertion of vibration, the bed layer viscosity decreased obviously, and good effect of fluidization occurred under 15 Hz frequency and 1 mm amplitude. The apparent viscosity was stable at 0.39~0.51 Pa×s.

反应与分离

Sulfuric Acid Leaching of Scandium from Black Tungsten Ore Slag and Depression Leaching of Iron by Carphosiderite Method

DING Chong WANG Xiao-hui HE Chao-ran ZHENG Shi-li XIE Hua ZHANG Ying

. 2014, 14(6):  907-914. 

Asbtract ( )   PDF (919KB) ( )  

Related Articles | Metrics

The leaching of black tungsten slag with sulfuric acid is studied by single factor experiments. Under the optimum leaching conditions of temperature of 90℃, mass ratio of acid to slag of 1.2, concentration of sulfuric acid of 29% and leaching time of 2.5 h, the leaching rate of Sc and Fe is 88% and 97%, respectively. Under the above optimum conditions, the leaching rule of Sc and depressed leaching rate of Fe are explored by adjusting the acidity of slurry. Under the optimum leaching conditions of temperature of 90℃, mass ratio of acid to slag of 1.0, mass ratio of the first stage acid to slag of 0.8, the first stage of 2.0 h and the second stage of 0.5 h, the leaching rate of Fe descends from 98% to 57%, showing its depression effect, with the leaching rate of Sc at 87%.

Pressure Leaching of Chromium-containing Slag from Non-calcium Roasting with Sulfuric Acid

ZHAO Bei-bei WANG Shao-na ZHENG Shi-li YANG De-jun

. 2014, 14(6):  915-922. 

Asbtract ( )   PDF (637KB) ( )  

Related Articles | Metrics

The pressure leaching process of chromium-contained slag from non-calcium roasting with sulfuric acid was studied. The effects of sulfuric acid concentration, reaction temperature, added amount of chromic anhydride, reaction time and particle size on the leaching of chromium were examined. The results show that the main phase components of the slag determined by systematic analysis and characterization are chromite (FeCr2O4), iron magnesium ore [Mg(Fe,Al)2O4], the content of spinel minerals is 73.11%, hematite (a-iron) 12.42%, and sodium nepheline (NaAlSiO4) 10.02%. The optimum leaching conditions of chromium in the slag are obtained as: sulfuric acid concentration 65%, temperature 120℃, added content of chromium anhydride 10% of chromium slag, time 2 h, particle size 75 mm and stirring speed 500 r/min. Under the conditions, the leaching rate reaches 97.93%. The leaching residue is silica-based, with 80.8% SiO2. The pressure leaching of chromium-containing slag from non-calcium roasting with sulfuric acid can be modeled with the shrinking core model. The apparent activation energy is 16.38 kJ/mol. The leaching rate is controlled by external diffusion and interface chemical reaction.

Research on Concentration of Tajik Copper-Tin Oxide Ore

RAN Jin-cheng LIU Quan-jun ZHANG Zhi-guo LI Di-fei

. 2014, 14(6):  923-929. 

Asbtract ( )   PDF (315KB) ( )  

Related Articles | Metrics

Tajik copper-tin oxide ore was studied for the technological problems of fine mineral dissemination and complex intergrowth. The results showed that the grade of copper in original ore was 0.89% and tin 0.87%. The oxidation rate of copper was up to 100% and cassiterite existed mainly in the form of tin. After comparison of multiple experiment trials, the processes of sulfuration-xanthate to recover copper and Falcon shaking table to recover tin were ultimately used. By the closed circuit flow experiments, the grade of copper concentrate obtained was 15.26% with the recovery rate of 85.90%, and the grade of tin concentrate 52.57% with the recovery rate of 71.30%.

Thermodynamic Analysis and Experiment on Pressure Leaching of Zinc Silicate with Sulfuric Acid

HE Shan-ming WANG Ji-kun WANG Jin-liang LI Yang GAN Lei XIONG Hui-hui

. 2014, 14(6):  930-936. 

Asbtract ( )   PDF (338KB) ( )  

Related Articles | Metrics

The ET-pH diagram of Zn-Si-H2O system was calculated and plotted. Thermodynamic analysis on the feasibility of sulfuric acid leaching of zinc silicate and desilication of orthosilicate at high temperature was analyzed. With pressure acid leaching of synthetic zinc silicate, the effects of initial concentration of sulfuric acid, final pH value, iron content, added amount of aluminum sulfate and temperature on acid leaching of zinc silicate and condensation of silicic acid were examined. The experimental results show that increasing of leaching temperature can effectively undermine the stability of silica and advantageously promote the desilication process at high temperature, as the filtering performance of slurry can be improved. The aluminum sulfate can promote the condensation and precipitation of silicone and reduce the concentration of silicate. Silica would advantageously precipitate when the final pH value of the slurry and mass ratios of Si to Fe and Si to Al were properly controlled. The optimum conditions for the pressure leaching of zinc silicate are leaching time 0.5 h at 120℃, ratio of liquid to solid 8 mL/g and H2SO4 concentration of 120 g/L. Under the conditions, the leaching rates of Zn and Si are 98% and 1%, respectively.

Leaching Process of Semi-oxidized Manganese Ore

JIN Sheng-long WANG Yu-hong SU Hai-feng CHENG Chen LEI Zuo-min

. 2014, 14(6):  937-942. 

Asbtract ( )   PDF (589KB) ( )  

Related Articles | Metrics

The leaching process and influential factors of semi-oxidized manganese ore were investigated, and the leaching mechanism was analyzed. The results showed that in the leaching process, the leaching rate of MnCO3 was faster than that of MnO2. There was a competitive consumption relationship of H+ between MnCO3 and MnO2, the former could easily get H+ in leaching, and the decomposition of MnO2 could be advantageous over MnCO3 which was packed in leaching. The leaching rate of total Mn was about 90% under the conditions of 10.0 g ore, 0.6 g sucrose and 5 mol/L sulfuric acid concentration for 60 min at 90℃, but the leaching rate of MnO2 and MnCO3 was steady at 95% and 98%, respectively. There was about 10% Mn could not be leached due to the existence of refractory manganese silicate phase and some wrapped Mn in gangue. 98% of total Mn leaching rate could be achieved by roasting the ore for 30 min at 800℃ before leaching. And 96% could be obtained by adding ammonium fluoride in the leaching process. The leaching rate of ore could be raised by roasting activation or adding fluorine ion to eliminate the package of gangue.

Distillation Mechanism of Ammonia by MgO in MgO-NH4Cl-H2O System

LIU Hai-hao LI Ming-yu JIA Guang-lin

. 2014, 14(6):  943-946. 

Asbtract ( )   PDF (258KB) ( )  

Related Articles | Metrics

The distillation mechanism of ammonia by MgO in MgO-NH4Cl-H2O system was studied, the effect of time on the yield of ammonia and the solid-phase component and hydration of MgO in the system were investigated. The results show that MgO completely turns into Mg(OH)2 within 30 min in the system where the distillation mechanism of ammonia should be distinguished as two stages. The hydration of MgO provides much OH- to promote the ammonia distillation reaction in the first stage, with OH-, MgO and Mg(OH)2 participating in ammonia distillation together. After the hydration is completed, Mg(OH)2 plays the main role in ammonia distillation reaction in the second stage.

过程与工艺

Influential Factors of Alkaline Content in Alumina-removed Residue by Hydrothermal Treatment from Extraction Process of Alumina from Fly Ash with Sub-molten Salt Method

LIU Zhong-kai MA Shu-hua ZHENG Shi-li XIE Hua WANG Shao-na MA Hai-jun

. 2014, 14(6):  947-954. 

Asbtract ( )   PDF (1776KB) ( )  

Related Articles | Metrics

Aluminum-removed residue from in the exaction process of alumina from fly ash by sub-molten salt method was decomposed to recover sodium by dynamic hydrothermal method. The effects of mass ratio Al2O3 to SiO2 (A/S), mass ratio of CaO to SiO2 (C/S) and dissolution processes of aluminum-removed residue on the alkaline content in final silicate residue were examined. The results indicate that the sodium content decreases first and then increases with the increase of A/S, the sodium content in the silicate residue is as low as 1.28% when A/S is 0.11, appropriate A/S can help improve the crystallization degree of Al-substituted tobermorite in the silicate residue. The sodium content in the silicate residue is only 1.31% when C/S is 0.98, the sodium content decreases with the increase of C/S, and the decomposition rate of NaCaHSiO4 decreases at high C/S, which is not beneficial to formation of Al-substituted tobermorite. The aluminum-removed residue with longer dissolution time and residence time is not easy to generate Al-substituted tobermorite in the sodium removal process and causes the increase of sodium content in the final silicate residue.

Synthesis of Sodium Titanyl Oxalate Trihydrate by Leaching of Na8Ti5O14 with Oxalic Acid

DU Zhi-hua YANG Xuan ZHAO Hui QI Tao SONG Ning XIE Gang WANG Shuo GUO Jiu-ji

. 2014, 14(6):  955-960. 

Asbtract ( )   PDF (473KB) ( )  

Related Articles | Metrics

Leachate solution containing titanium and sodium was acquired by leaching of cheaper sodium titanate Na8Ti5O14 with oxalic acid. The product of sodium titanyl oxalate with high purity of 99% was obtained successfully by evaporation crystallization, and characterized by XRD, IR, SEM, etc. The effects of the concentration of oxalic acid, reaction temperature, reaction time and stirring intensity on leaching rate of titanium were investigated, and the optimum process conditions obtained: concentration of oxalic acid 4 mol/L, reaction temperature 80℃, and reaction time 2 h. The temperature leaching kinetics was studied. The experimental results showed that the apparent activation energy was determined as 43.85 kJ/mol, the leaching of titanium followed the shrinking core model with surface reaction control.

Comparison of Kinetic Characteristics of Electrochemical Reduction of CO2 on Au and Ag Electrodes

WANG Xiao-chun LI Lu YANG Dong-wei WANG Qin SHI Jin

. 2014, 14(6):  961-966. 

Asbtract ( )   PDF (354KB) ( )  

Related Articles | Metrics

The electrochemical kinetic characteristics of CO2 reduction are studied in 0.1 mol/L KHCO3 aqueous solution using cyclic voltammetry, Tafel curve, potentiostatic electrolysis and gas chromatogram. The results show that CO2 can be reduced to CO on Au and Ag electrodes. The equilibrium potential, exchange current density, transfer parameter and charge transfer resistance on Au and Ag electrodes obtained are -0.720 and -0.934 V, 0.4014 and 0.3011 mA/cm2, 0.33 and 0.35, and 31.98 and 42.64 W×cm2, respectively, their Faradaic efficiencies reach 82% and 65%, respectively. Au electrode exhibits higher activity than Ag electrode.

Coke Deposition Features in Methylphenyldichlorosilane Synthesis by Gas Phase Condensation

LIU Tong WANG Chao WANG Tie-feng WANG Jin-fu

. 2014, 14(6):  967-972. 

Asbtract ( )   PDF (428KB) ( )  

Related Articles | Metrics

Coke deposition features in methylphenyldichlorosilane (MPDS) synthesis by gas phase condensation from chlorobenzene (PhCl) and methyldichlorosilane (MH) were studied with morphology characterization, element analysis, thermogravimetry and Raman spectroscopy. The deposited coke formed in MPDS synthesis had high graphitization degree, and was insoluble coke. The molar ratio of hydrogen to carbon was 0.35~1.74. Thermogravimetric analysis was carried out in the oxygen atmosphere, the main weight loss temperature range was 650~1100 K. The coke burning process was first order reaction with the apparent activation energy of 117 kJ/mol. The contribution of PhCl to the deposited coke was more significant than that of MH, and the amount of deposited coke formed from PhCl was 3 times as much as that formed from MH. Therefore the preheating temperature of chlorobenzene should be decreased to reduce the deposited coke.

Kinetic Experiment and Modelling of Reduction Reaction of Limonite with Biochar in Microwave Field

LI Jie HAN Lei LI Bao-wei WANG Jie-liang ZU Gang YANG Zhong-yu

. 2014, 14(6):  973-978. 

Asbtract ( )   PDF (398KB) ( )  

Related Articles | Metrics

The changes of weight loss and mineral phase of limonite with biochar before and after microwave roasting were measured at 923 K. Based on the curves of rising temperature and weight loss of reduction roasting by microwave heating, the reaction kinetics parameters of limonite in different temperature periods were calculated by Achar-Brindley-Sharp-Wendworth differentiation method and Coats-Redfern integration method. The results showed that the limonite reduced by biochar changed into magnetite at 923 K, and produced little ferrous silicate (Fe2SiO4) in roasted ore. And the reduction roasting process of limonite with biochar by microwave heating was divided into three temperature stages. The apparent activation energy (E1) was 30.7 and 26.3 kJ/mol in 366~470 K respectively, and the reaction mechanism accorded with reaction order function, belonging to the chemical reaction control. In 470~650 K, the apparent activation energy (E2) was 40.3 and 33.1 kJ/mol respectively, the reaction mechanism accorded with Avrami-Erofeev function, belonging to the chemical reaction control of stochastic coring and afterward growing up. But in 650 ~825 K, the apparent activation energy (E3) was 52.4 and 52.9 kJ/mol respectively, and the reaction mechanism accorded with Zhuralev-Lesokin-Tempelman function, belonging to the three-dimensional diffusion control.

Recovery of Potassium Chloride from Sintering EAF Dust

ZHANG Mei FU Zhi-gang WU Bin LV Na ZENG Le-lin YANG Yun-quan

. 2014, 14(6):  979-983. 

Asbtract ( )   PDF (223KB) ( )  

Related Articles | Metrics

Taking the sintering dust with potassium resource from iron and steel metallurgical process as raw material, a new recovery process of potassium from the dust was proposed, which included water leaching, solid-liquid separation, purification, decolorization, solid-liquid separation, vacuum evaporation and cooling crystallization. By experiment, the optimum evaporation concentration ratio was obtained, under which the high-quality potassium chloride product could be acquired. At the beginning and ending boiling temperatures of 120 and 160℃, respectively, the rotational speed of 50~60 r/min and evaporating concentration ratio of 10.71, the content and recovery yield of potassium chloride from the dust reached 97.24% and 65.25%, respectively. The product could meet the first-class index requirements of GB6549-2011 and its particle size distribution was rather concentrated and homogeneous.

Effects of Low-rank Coal Macerals on Evolution of Oxygen Functional Groups in Pyrolysis of Mixed Coals

GAO Zhi-fang ZHANG Geng ZHENG Ming-dong ZHANG Xiao-yong ZHANG Dai-lin

. 2014, 14(6):  984-988. 

Asbtract ( )   PDF (305KB) ( )  

Related Articles | Metrics

The chemical titration method combined with FT-IR analysis was used to study the effects of low rank coal macerals on the evolution of oxygen functional groups of coals and metastasis by analysis of different proportions, and the interactions of low rank coal vitrinite and inertinite with mixed coal containing functional group. The results showed that the phenol, alcohol, ether, ester C-O oxygen-containing functional groups of mixed coal reached a steady state when the pyrolysis temperature was 600℃, and the oxygen evolution rate increased at 400~600℃, then tended to be stable at about 30%. When the pyrolysis temperature was 700℃, oxygen precipitation was completed. Moreover, the addition of low rank coal macerals into fat coal would reduce the proportion of hydrogen less than the loss of oxygen of mixed coal in pyrolysis process, which was beneficial to improvement of the colloid quality.

Combustion Behavior of Carbon Powder in O2-CO2 Mixture

ZHANG Zhao-liang YAN Hong-yan ZHU Rong ZHOU Guo-zhi

. 2014, 14(6):  989-993. 

Asbtract ( )   PDF (702KB) ( )  

Related Articles | Metrics

The combustion behavior of carbon powder in O2-CO2 mixture was experimentally studied by TG-DTA technique. The results showed that in the non-isothermal combustion process of carbon powder, TG and DTG curves moved to high temperature zone, and the ignition and burnout temperatures increased with increasing of CO2 content. In the isothermal combustion process at 1100℃, TG, DTG and DTA curves also moved to high temperature zone with increasing of CO2 content. When CO2 content is higher than 20%, TG curve showed a platform, and correspondingly DTG and DTA curves appeared a crest and a peak, respectively. Moreover, the higher the CO2 content was, the sooner the platform appeared. The increase of CO2 content obviously reduced the combustion heat. When the CO2 content was less than 80%, CO2 did not participate in the reaction with carbon apparently, the actual thermal effect was associated with O2 content only, being in accordance with the square root relationship.

生化工程专栏

Preparation of Thymalfasin Loaded PLGA Microspheres by Premix Membrane Emulsification as Long-term Effective Formulation

YANG Liu-qing WANG Li-qiu WU Jie QI Feng REN Yu TAO An-jin MA Ya-ping MA Guang-hui

. 2014, 14(6):  994-999. 

Asbtract ( )   PDF (755KB) ( )  

Related Articles | Metrics

Thymalfasin-loaded biodegradable poly(lactic-co-glycolic acid) (PLGA) microspheres were prepared by premix membrane emulsification technique combined with solvent evaporation method. The effects of concentrations of PLGA and Arlacel 83 in oil phase, pH value of external water phase and internal water volume on the drug encapsulation efficiency and size distribution of microcapsules were examined. The results showed that the optimized preparation conditions of thymalfasin loaded PLGA microspheres were molecular weight of PLGA 51 kDa, concentrations of PLGA and Arlacel 83 in oil phase 100 and 10 g/L, inner water volume 0.5 mL, and pH value of outer water phase 3.5. The microspheres prepared under the optimal conditions had narrow size distribution (Span<0.7), high drug encapsulation efficiency (above 80%), low initial burst release (below 20% in initial 24 h) and constant release rate during 30 d.

Synthesis and Drug Release Performance of Hollow PEG@Gd2O3:Tb Hybrid Nanoparticles

HUANG Chang-shui JIU Hong-fang JIA Wan-bao CHANG Jian-xia JIAO Hong-qian

. 2014, 14(6):  1000-1004. 

Asbtract ( )   PDF (327KB) ( )  

Related Articles | Metrics

PEG@Gd2O3:Tb3+ hybrid hollow nanoparticles were synthesized by one-step hydrothermal method, and characterized. The results show that the diameter of hybrid hollow nanoparticles is 200 nm, and the wall thickness 100 nm. They can be regulated by suitable modification. Compared with the calcined hollow Gd2O3:Tb3+, the hybrid hollow nanoparticles exhibit lower release rate due to PEG. The system shows a slow release and complete release after 24 h, the loading amount of doxorubincin in PEG@Gd2O3:Tb3+ hollow spheres is 261.5 mg/g. They may find potential applications in the fields such as drug delivery and biological labeling because of their excellent biocompatibility and luminescence properties.

Relationships between Concentrated H3PO4 Pretreatment Conditions and Substrate Concentration in High Solid Enzymatic Hydrolysis of Pretreated Waste Cotton-based Textiles

CAI Jun-zhuo DONG Zhu-jun QIU Jing-wen SHI Yu SHEN Fei

. 2014, 14(6):  1005-1009. 

Asbtract ( )   PDF (267KB) ( )  

Related Articles | Metrics

In order to seek an efficient utilization way for waste cotton-based textiles, concentrated H3PO4 pretreatment was employed to regenerate cellulose for glucose production by enzymatic hydrolysis. The relationships of pretreatment temperature, time and H3PO4 concentration with substrate concentration for high solid enzymatic hydrolysis were investigated. The results indicated that the positive linear relationships existed in the pretreatment temperature, time and the substrate concentration. Based on glucose conversion of 70.0% as a criterion for high efficient hydrolysis, the potential substrate concentration could be improved from 4.6% to 18.0% as temperature was promoted from 30℃ to 60℃. When pretreatment time was prolonged from 3.0 to 12.0 h, the potential substrate concentration was correspondingly enhanced from 10.8% to 25.1%. However, excessive pretreatment time was not beneficial to the enhancement of potential substrate concentration. H3PO4 concentration could not greatly improve the potential substrate consistency in the range of 77.5%~82.5% except that 17.6% substrate concentration could be achieved at 85%. As a result, the maximum potential substrate concentration of 25.1% was achieved as the waste cotton-based textiles were pretreated at 60℃ with 85.0% H3PO4 for 12.0 h.

Effect of Temperature on Treatment Efficiency of Antibiotic Pharmaceutical Wastewater

CHEN Jian-fa

. 2014, 14(6):  1010-1014. 

Asbtract ( )   PDF (282KB) ( )  

Related Articles | Metrics

The A2O-biological aerated filter-flocculation coupled technology was applied to treat antibiotics-based mixed industrial wastewater, and the effect of temperature on treatment efficiency studied. The results showed that when water temperature was 10.0~36.5℃, the concentrations of CODcr, NH3-N and total phosphorus (TP) were 183~785, 20.7~76.2 and 2.47~33.7 mg/L in influent and the flow rate was 30.0 L/h, the average biomass removal rates of CODcr, NH3-N and TP were 64.6%, 55.7% and 84.4%, respectively. The CODcr, NH3-N and TP in effluent achieved the first grade of comprehensive discharge standard for sewage (GB8978-1996). The change of water temperature had little effect on the removal efficiencies of CODcr, NH3-N, TP and other pollutants. The metabolic rate of microbes was still high even at 10℃. This coupled technology has strong buffering capacity to the change of water temperature, providing a new way to efficiently treat sewage in severe cold areas.

Purification and Enzymatic Properties of Polyvinyl Alcohol Dehydrogenase

LI Min DU GUo-cheng;

. 2014, 14(6):  1015-1019. 

Asbtract ( )   PDF (281KB) ( )  

Related Articles | Metrics

The polyvinyl alcohol (PVA) dehydrogenase (PVADH) was purified using ammonium sulfate precipitation and ion exchange chromatography of Q-Sepharose HP, and its enzymatic properties were studied. The results showed that the molecular weight of this enzyme was estimated to be 134.3 kDa, its optimal reaction temperature was 35℃, and the optimum pH value 7.5. Its activity was generally higher when the substrate was secondary alcohols. The carbonyl compounds were detected from the reaction products of PVADH and PVA, which confirmed the degradation effect of PVADH on PVA.

材料工程专栏

Characterization and Synthesis of Cu-Cu2O-CuO Catalyst from Copper Concentrate and Its Catalytic Performance in Rochow Reaction of Organosilicon Monomers

ZHAI Yan-zhao WANGH Ying-li WANG Guang-na ZHU Yong-xia LIU He-zhi ZHANG Zai-lei MA Li-qiang JI Yong-jun SU Fa-bing

. 2014, 14(6):  1020-1028. 

Asbtract ( )   PDF (1819KB) ( )  

Related Articles | Metrics

Copper powder was obtained from the copper concentrate via the roasting-acid leaching-displacement process, followed by partial oxidation and ball milling, the three-component Cu-based catalyst was prepared, and characterized. The catalytic properties were then investigated by using the Rochow reaction on a lab fixed-bed reactor. The results indicated that the obtained ternary Cu-based catalyst, Cu-Cu2O-CuO, exhibited much improved M2 selectivity (82.0%) and silicon conversion (57.1%) in comparison with displaced Cu powder, which gave a very low M2 selectivity of 34.6% and silicon conversion of 15.7%, respectively. The physical and chemical properties of the contact masses before and after the reaction verified that the enhanced catalytic performance of Cu-Cu2O-CuO catalyst was ascribed to the smaller particle size and much more active phase of CuxSi alloy formed during the reaction, which was consistent with the adsorption oxidation mechanism.

Preparation of Cu Nanoparticles with Thiourea Dioxide by Aqueous Reduction Method

LI Wen-cong PAN Yong-zhang WANG Jun YE Lin-shun JIN La-hua

. 2014, 14(6):  1029-1034. 

Asbtract ( )   PDF (641KB) ( )  

Related Articles | Metrics

Dispersive nanocrystalline copper powder was prepared by two-step aqueous chemical reduction method with copper sulfate as raw material, polyvinylpyrrolidone as dispersant, and glucose and thiourea dioxide as reductive agents. The effects of prereduction, concentration ratio of thiourea dioxide to copper ion, reaction temperature and reaction time on the shape, size and size distribution of nanocrystalline copper powder were examined, and the copper powder was characterized. The results showed that the optimum conditions were obtained as the concentration ratio of thiourea dioxide to copper ion 2:1, reaction temperature 75℃, and reaction time 15 min. Under the conditions, the prepared Cu particles were pure spherical-shaped particles with the diameters of 20~100 nm.

Preparation of Electronic Grade Mangano-Manganic Oxide by Direct Oxidation of Manganese Nitrate Solution

YUAN Ming-liang LI Kang

. 2014, 14(6):  1035-1040. 

Asbtract ( )   PDF (636KB) ( )  

Related Articles | Metrics

High-purity electronic grade Mn3O4 was prepared by a direct oxidation route of manganese nitrate solution as raw material, aqueous ammonia as precipitant and air as oxidant. The effects of preparation conditions, such as feeding rate of aqueous ammonia, pH value, reaction temperature, ethanol addition and air flow rate, on Mn content in the obtained product were examined by orthogonal experiments. The results show that the obtained product is high-purity electronic grade Mn3O4, Mn content reaches the maximum value of 77.53%, and Mn particle size is 10 mm under the conditions of feeding rate 4 mL/min, pH value 11, reaction temperature 80℃, ethanol addition 15 mL and air flow rate 80 L/h. In addition, the product overcomes the disadvantage of high sulfur content in the mangano-manganic oxide which is prepared by manganese sulfate.

Precipitation Behaviors and Strengthening of Carbides in H13 Steel during Quenching

NING An-gang MAO Wen-wen GUO Han-jie CHEN Xi-chun

. 2014, 14(6):  1041-1046. 

Asbtract ( )   PDF (694KB) ( )  

Related Articles | Metrics

Thermodynamic calculation of H13 steel during solidification in solid phase is carried out to define the precipitate temperature of V8C7 (1545.7 K) and Cr23C6 (1055.3 K). After 1373 K quenching of die H13 steel, the microstructure and variation in H13 steel are observed with optical microscope. Through deploying carbon extraction replica technique, using TEM, electron diffraction and EDS, the amount, average size and type of carbides are analyzed, and the contribution of three parts of steel to yield strength is explored. The results show that the microstructure in H13 steel after quenching is changed from pearlite to martensite and residual austenite. The precipitates mainly include V8C7 and Cr23C6. From the center to 1/2 radius of ingot, the average size of carbides determines the strengthening contribution. From 1/2 radius to surface, the volume fraction of carbides determines the strengthening contribution. The overall mechanical properties of H13 steel become excellent as the number of precipitates increases and particle sizes become smaller.

Effect of Coiling Temperature on the Microstructure and Texture Evolution of Non-oriented Silicon Steel

WANG Yong WU Shao-jie CHEN Wei-qing LI Jie

. 2014, 14(6):  1047-1052. 

Asbtract ( )   PDF (510KB) ( )  

Related Articles | Metrics

With industrial test, metallographic microscope, SEM and EBSD techniques, the effect of coiling temperature on the microstructure and texture evolution of hot-rolled, cold-rolled and annealed cold-rolled plates of 50W600 non-oriented silicon steel was studied. The experimental results showed that the main texture types of hot-rolled, cold-rolled and annealed cold-rolled plates undergone an evolution from Goss texture {110} <001> to {111} and {100} fiber texture and finally to {111} fiber texture and a very small amount of {100} fiber texture. Increasing of the coiling temperature from 680℃ to 720℃ promoted the nucleation and growth of recrystallized grains, and thus improved the grain growth of annealed cold-rolled plate from 40.88 to 48.58 mm. The volume fractions of {111} and {100} fiber texture in annealed cold-rolled plate under the coiling temperature of 680℃ were 32.9% and 6.1%, respectively. The volume fractions of {111} and {100} fiber texture in annealed cold-rolled plate changed to 25.1% and 7.9% as the coiling temperature increased from 680℃ to 720℃. Increasing coiling temperature from 680℃ to 720℃, the core loss of annealed cold-rolled plate decreased from 3.94 to 3.85 W/kg, the magnetic ?ux density increased from 1.690 to 1.701 T.

Effect of Solid Solution of Nitrogen Element on Crystal Grain Formation of Austenitic Manganese Steel with High Thermal Conductivity

CHEN Shao-chun ZHU Rong LU Yue-mei WU Yun-bin LIN Xiao-ying LIN Yang

. 2014, 14(6):  1053-1057. 

Asbtract ( )   PDF (386KB) ( )  

Related Articles | Metrics

The effect of solid solution of nitrogen element on crystal grain of developed austenitic manganese steel with high thermal conductivity is studied. The results indicate that the crystal grain of manganese steel in casting is affected by the nitrogen in the interface between crystal and liquid steel as surfactant, and the diffusion of relevant atoms are hindered by nitrogen, so that free energy of critical nucleation will be increased, homogeneous nucleation rate of crystal raised and growing velocity of crystal lowered, and crystal grain will be refined finally in steel casting. The effect degree of nitrogen on crystal grain of steel is affected by nitrogen content. During heat treatment, because of covalent bond between nitrogen and iron and manganese atoms, the diffusion of iron and manganese atoms will be hindered due to the existence of nitrogen at boundary of crystal or the attachment of nitrogen on the face of crystal, so that growing velocity of crystal will be lowered and the crystal grain of steel can be controlled. The new kind of austenitic manganese steel decreases the content of manganese below 8%, the content of carbon to about 1%, and the content of nitrogen about 0.07%, the crystal grain grade of developed steel reaches the class 4, and its mechanical properties meet those required by standard manganese steel Mn13.

Synthesis of Sheet-assembled Flower-like ZnO and Its Gas Sensing Properties to Trimethylamine

SONG Jin-ling REN Wen-qiang ZHANG Yin

. 2014, 14(6):  1058-1062. 

Asbtract ( )   PDF (341KB) ( )  

Related Articles | Metrics

The ZnO material was prepared by low temperature hydrothermal method. The structure and morphology were characterized by XRD and SEM. And the trimethylamine-sensing properties of prepared ZnO were measured by the gas sensing instrument. The results show that the prepared ZnO material exhibits hexagonal wurtzite structure and sheet-assembled flower-like morphology. Moreover, its sensitivity can reach 63.72 towards 1.00×10?4 trimethylamine at 340℃. The sensitivity increases linearly with increasing of the trimethylamine concentration. The response time and recovery time are 4 s and 21 s, respectively. In addition, the material shows excellent selectivity, repetition property and long-term stability.

综述

Research Progress in Vapor-Liquid Equilibrium of Fischer-Tropsch Synthesis System

QUAN Gui-ying TANG Xiao-jin ZHANG Zhan-zhu

. 2014, 14(6):  1063-1071. 

Asbtract ( )   PDF (276KB) ( )  

Related Articles | Metrics

The recent research progress in vapor-liquid equilibrium (VLE) of Fischer-Tropsch synthesis (FTS) system is reviewed and analyzed. And the accuracies of calculation methods are discussed. FTS system can be divided into two sections, hydrocarbon products and small molecule gases. The former can be further divided into light hydrocarbon products with the carbon number lower than 18 and heavy ones greater than 18. The VLE of hydrocarbon products and the dissolution equilibrium of the small molecule gases are reviewed respectively. From the points of accuracy and simplicity of the calculation methods, the VLE of light hydrocarbon products can be described by Raoult's law. Due to diffusion limitation, the VLE of heavy hydrocarbon products can be calculated by the EOS (equation of state) methods, among which PR EOS is widely used with good accuracy. Henry's law and EOS method are all applied in the dissolution equilibrium calculation of small molecule gases. And Henry's law is more suitable to description of the dissolution equilibrium of small molecule gases.

Effects of Structures of Ionic Liquids on Diels-Alder Reactions

MA Zheng ZHANG Bai-song HU Yu-feng DONG Xiao-xia XU Chang-ying LIU Yan-sheng

. 2014, 14(6):  1072-1080. 

Asbtract ( )   PDF (345KB) ( )  

Related Articles | Metrics

The effects of structures of ionic liquids (ILs) on Diels-Alder reactions were reviewed. A lot of research on Diels-Alder reactions carried out in ILs in the world was summarized. The effects of changes in structure of ILs on the rate and endo-selectivity of the reactions were discussed in terms of physical properties of ILs, such as polarity, acidity and viscosity. The impacts of type of hydrogen bond, proton on C(2) position of imidazolium ring, Lewis acidity or Br?nsted acidity of ILs, viscosity of ILs and reaction system were also analyzed in detail. The activation energy, electrophilicity and C?C bond length in transition state were calculated by means of density functional theory. The calculation results showed that the effect of solvent decreased the activation energy and increased the asynchronicity. Related future development lay in the synthesis of functionalized ionic liquids based on ILs physical properties and reaction mechanism to obtain new, efficient and green Diels-Alder reactions and achieve wider application.