钢铁钒钛

Status and development of titanium dioxide industry in 2018

BI Sheng

2018, 39(6): 1-4.

Abstract(23) PDF(2)

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Study on Single and Cyclic Roasting of Vanadium Slag and Analysis of Thermodynamics and Kinetics

Xiong Kaiwei

2018, 39(6): 5-10. doi: 10.7513/j.issn.1004-7638.2018.06.001

Abstract(28) PDF(1)

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The factors respectively influencing the single and cyclic roasting of vanadium slag during the novel calcification process for vanadium extraction were studied,and the thermodynamics and kinetics were also analyzed.The results show that the morphology of clinker by single calcination with lump and sphere shape is different from that of the cyclic roasting slag having a loose structure.The conversion rate reaches above 90% at the cycle ratio of 0.50 for clinker cycle roasting,and it is 16.20 % for tailing cycle roasting.The conversion rate of single clinker roasting is 82.38 %,indicating that the single roasting is incomplete.The roasting of mixture for tailing and clinker could significantly increase the conversion rate,and the conversion rate is 89.55 % at R₂/R₁=0.67（tailing cycle ratio）.The CaO/V₂O₅ ratio for single roasting is 0.6～0.8,while the CaO/V₂O₅ for cyclic roasting is 0.40 and the residual calcium can be reused.The conversion rate of 4 h is about 85% for the single roasting and 88%～92% for the cyclic roasting.The cyclic roasting temperature is 30 ℃ lower than that of the single roasting,while the conversion rate for cyclic roasting is 5.54～7.18 percent points higher than that of single roasting.The equilibrium constant K at 870 ℃ is 35.17 and 132.44 for single and cycle roasting,respectively.ΔG for single and cycle roasting is respectively-33.84 kJ/mol and-46.48 kJ/mol.ΔS is-0.220 9 kJ/mol and-0.198 1 kJ/mol for single and cycle roasting,respectively.ΔH for single and cycle roasting is 216.88 kJ/mol and 183.92 kJ/mol,respectively.The single and cycle roasting of vanadium slag are both controlled by a zero-grade chemical reaction,with 37.36 kJ/mol and 30.65 kJ/mol of the activation energy E,and 7.32×10¹³ min^-1 and 3.11×10¹³ min^-1 of the pre-exponential factor A,respectively for the single and cycle roasting.

Hydrothermal Synthesis of Bismuth Vanadate Pigments by Sodium Vanadate

Wang Shaona, Du Hao, Li Lanjie, Gao Minglei, Bai Li, Zheng Shili

2018, 39(6): 11-17. doi: 10.7513/j.issn.1004-7638.2018.06.002

Abstract(36) PDF(1)

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In this article,bismuth vanadate（BiVO₄）was hydrothermally synthesized respectively using sodium vanadate produced by sub-molten salt process from vanadium slag and bismuth nitrate pentahydrate（Bi（NO₃）₃·5H₂O）as raw materials.The optimal synthesis conditions for bismuth vanadate pigments were determined at the precursor solution pH of 7,n_Bi/n_V of 1,reaction temperature higher than 100 ℃ and reaction time more than 6 h.The chromaticity and oil absorption of the prepared monoclinic BiVO₄ satisfied the standard requirements,respectively.The experimental results show that bismuth vanadate with qualified chromaticity and oil absorption can also be obtained from sodium orthovanadate,sodium metavanadate or ammonium metavanadate under the same reaction conditions.Therefore,bismuth vanadate can be prepared from sodium vanadate with lower cost,which greatly improves the economy of the product.

Research on Precipitation Process and Dynamics Behaviors of Ammonium Polyvanadate

WU You

2018, 39(6): 18-24. doi: 10.7513/j.issn.1004-7638.2018.06.003

Abstract(41) PDF(2)

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The precipitation process of ammonium polyvanadate was studied in this paper.At the optimum conditions of 32～40 g/L for vanadium concentration in the solution by roasting-leaching process,0.8～1.2 of precipitant addition coefficient,above 65 ℃ of temperature before the acid addition,1.7～2.1 of precipitation pH and about 93 ℃ of boiling temperature for 52～60 min,a precipitation rate of vanadium over 99% can be achieved.Furthermore,the kinetics behaviors for precipitation of ammonium polyvanadate were investigated at the optimum conditions.The precipitation process of ammonium polyvanadate can be described by Avrami crystallization kinetics equation,with the apparent activation energy E_a=35.87 kJ/mol and the pre-exponential factor A=5.42×10²⁰ min^-1,respectively.

Thermodynamic Calculation and Experimental Study on TiC_xN_1-x Prepared by Carbothermal Reduction-nitridation of Ilmenite

Zhu Kuisong, Wen Yaomin, Wang Yungang, Cao Li, Zhou Lanhua, Gou Shuyun, Sun Yan

2018, 39(6): 25-33. doi: 10.7513/j.issn.1004-7638.2018.06.004

Abstract(24) PDF(1)

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In this study,the phase evolution and C content of the products during synthesis of TiC_xN_1-x by carbothermal reduction-nitridation in a vacuum furnace using ilmenite,coke powder and high purity nitrogen as raw materials were investigated via thermodynamic calculations and experiments.The phase evolution during the carbothermal reduction-nitridation process was analyzed by HSC thermodynamic calculation software.Based on the thermodynamic calculations,experiments at different reaction temperatures were carried out.The products were characterized by XRD and SEM-EDS,respectively.The results indicate that the formation of TiN and TiC is respectively controlled by the procedure of Ti₃O₅→TiN and Ti₃O₅→TiC,with the evolution temperature at 1 231 and 1 319 ℃,respectively.The experimental results show that TiC_xN_1-x can be initially generated at 1 200 ℃,moreover,the single phase of TiN and TiC could not be generated during the whole heating process.The C content of TiC_xN_1-x gradually increases with increase of temperature,from 9.8% at 1 200 ℃ to 36.273% at 1 350 ℃.Meanwhile,the mass fraction of N in TiC_xN_1-x decreases from 42.14% to 18.456% with temperature increasing from 1 200 to 1 350 ℃.

Numerical Simulation on Scabbing in Oxidation Reactor for Chloride Process Titanium Dioxide

Li Dongqin, Du Ming, Zhou Airan, Lu Ping

2018, 39(6): 34-40. doi: 10.7513/j.issn.1004-7638.2018.06.005

Abstract(25) PDF(3)

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Combined with the experimental analyses and numerical simulation,the factors influencing the scarring were analyzed based on the current situation of scarring in an oxidation reactor for chloride process titanium dioxide.The results show that the high temperature gas tends to adhere on the cold wall of gap before TiCl₄ feeding,causing scabbing of the oxidation reactor.The ways to prevent scabbing before feeding gap include the enhancement of wall temperature of the reactor and decrease of the gas liquefaction.The fluidization state of mixed fluids is affected by the structure of the oxidation reactor.Increasing the width of feeding gap and optimizing the momentum ratio of TiCl₄ and O₂ can effectively prevent and decrease the scabbing after the feeding gap.The scabbing reduces the inner diameter of the reactor and increases the system pressure dramatically,which leads to shutdown of the furnace and shortens the operation cycle.

Influence of Organic Treatment Agents on the Thermal Stability of Titanium Dioxide

Liu Yong, Hou Tengfei, Wu Xiaoping

2018, 39(6): 41-47. doi: 10.7513/j.issn.1004-7638.2018.06.006

Abstract(44) PDF(3)

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The influence of several kinds of typical organic treatment agents on the thermal stability of titanium dioxide was investigated.The results exhibited that the thermal stability followed the order:polysiloxane＞ 3-aminopropyltriethoxysilane＞trimethylolpropane＞octyltriethoxysilane＞triethanolamine.The mechanism about the effect of molecular structure of organic treatment agents on the thermal stability of titanium dioxide was studied through thermal gravimetric（TG） analysis and Fourier transform infrared spectroscopy（FTIR） characterization.The results showed that both the decomposition temperature and decomposition mode exerted great influence on the thermal stability of titanium dioxide.Silane coupling agents could form silicon dioxide under heating condition,and formed a coating layer on the surface of titanium dioxide,which improved the thermal stability to a certain extent.But the long carbon chain in the coupling agent would reduce the thermal stability.Organic amine could be doped into titanium dioxide upon heating,which deteriorated the thermal stability of titanium dioxide.The decomposition temperature of polysiloxanes was high due to the Si-O-Si backbone with high bond energy,thus their thermal stability was the best among the common organic treatment agents.They still showed good yellowing resistance at 350 ℃.

Effect of Sintering Temperature on Properties of Ti-29Nb-4Mo-13Ta-9Zr Alloy for Biomedical Applications

Wang Huanhuan, He Shiyu, Xu Ying, Cai Yanqing, Wei Ziyan

2018, 39(6): 48-54. doi: 10.7513/j.issn.1004-7638.2018.06.007

Abstract(21) PDF(1)

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In order to improve the comprehensive mechanical properties and corrosion resistance of titanium alloy used as medical implant materials,Ti-29Nb-4Mo-13Ta-9Zr alloy was prepared by powder metallurgy.The effects of sintering temperature on the phase compositions,microstructure,compressive strength,elastic modulus and electrochemical corrosion of the alloy were studied by X-ray diffraction,metallographic microscope,scanning electron microscope,compression test and potentiodynamic polarization curve test.The results indicate that the stable β phase structure in Ti-29Nb-4Mo-13Ta-9Zr alloy can be formed and the density of the alloy gradually increases with increase of the sintering temperature.At 1 350 ℃ of sintering temperature,the compressive strength of the alloy is 780 MPa and the elastic modulus is about 66 GPa,which improves the comprehensive mechanical adaptability of the alloy.Potentiodynamic polarization curves exhibit that Ti-29Nb-4Mo-13Ta-9Zr alloy sintered at 1 350 ℃ has a self-corrosion voltage of-187.09 mV and self-corrosion current of 11.172 μA/cm²,indicating a better corrosion resistance.Thus,Ti-29Nb-4Mo-13Ta-9Zr alloy is a potential material for implant applications.

Preparation and Characterizations of Graphene Oxide/Titanium Dioxide Composite Materials

Lai Qi, Peng Fuchang, Ma Ying, Cui Yan

2018, 39(6): 55-58. doi: 10.7513/j.issn.1004-7638.2018.06.008

Abstract(33) PDF(1)

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Graphene oxide/titanium dioxide（TiO₂-GO） composites were prepared by hydrothermal synthesis method using graphene oxide and industrial titanium liquid as raw materials.The microstructure,functional groups and phases,photocatalytic properties of the composites were analyzed by scanning electron microscope（SEM）,infrared spectroscopy（IR） and X-ray diffraction（XRD）,ultraviolet visible spectroscopy（UV-vis）,respectively.The results show that the addition of graphene oxide changes the shape of titanium dioxide,from spherical particles to porous spherical particles based on lamellar structure.Addition of graphene oxide is beneficial to the formation of anatase titanium dioxide.The photocatalytic properties of the composites increase with increase of the graphene oxide addition in a certain range,indicating that the addition of graphene oxide favors the light absorption.

Effect of Sintering Process on Structure and Electrochemical Performances of Li₃V₂（PO₄）₃/C Cathode Material for Lithium Ion Batteries

Li Nali, Tong Yanwei, Cui Xumei, Zhang Xuefeng

2018, 39(6): 59-64. doi: 10.7513/j.issn.1004-7638.2018.06.009

Abstract(72) PDF(4)

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Lithium vanadium phosphate（Li₃V₂（PO₄）₃） has become a potential and promising lithium ion battery cathode material due to its high energy density,good structural stability,safety performance and low temperature performance.The Li₃V₂（PO₄）₃/C samples were synthesized by carbothermal reduction method from ball-milling mixture of stoichiometric LiOH·H₂O,V₂O₅,NH₄H₂PO₄ and citric acid.The effects of calcination temperature and time on the structure and electrochemical properties of Li₃V₂（PO₄）₃ cathode materials were investigated by XRD and galvanostatic charge/discharge measurement.The optimum calcination process parameters for monoclinic Li₃V₂（PO₄）₃ cathode materials with excellent performances were obtained by several experiments.The results show that the Li₃V₂（PO₄）₃/C sample synthesized at 850 ℃ for 10 h has the most stable structure and the best electrochemical properties,respectively with the discharge capacity of 119 mAh/g for initial cycle and 118.7 mAh/g after 15 cycles,at 0.1 C and 3.0 ～ 4.3 V.The retention rate of discharge capacity is about 99.7%.

Preparation of Vanadium Based Hydrogen Storage Battery Alloy by Intelligent Controlled Self Propagating

Qiao Zhigang, Zhao Junqiang

2018, 39(6): 65-68. doi: 10.7513/j.issn.1004-7638.2018.06.010

Abstract(10) PDF(1)

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In this paper,the self propagating process for preparation of the vanadium based hydrogen storage battery alloy was controlled intelligently,and the comparison between the conventional PID control and the intelligent PID control was carried out.The results show that compared with the sample by conventional PID control,corrosion potential of the alloy by intelligent PID control positively shifts by 105 mV,and the decay rate of discharge capacity after 30 cycles is reduced by 17%.PID intelligent control can effectively improve the electrochemical corrosion resistance and electrochemical stability of the vanadium based hydrogen storage battery alloy.

Study on Preparation of Titanium Dioxide/Graphene Composites

Luo Jinhua, Zhang Shuli

2018, 39(6): 69-75. doi: 10.7513/j.issn.1004-7638.2018.06.011

Abstract(15) PDF(1)

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In this paper, TiO₂/graphene composites were prepared by combination of graphene powder with the calcinated TiO₂ from orthotitanic acid, which was synthesized by acidolysis and neutralization of metatitanic acid followed by spray drying.The structure and morphology of the composites were characterized by SEM and XRD.And for UV-light photocatalytic degradation of methyl orange, the optimized preparation parameters of TiO₂/graphene composites were obtained.With the optimized mass ratio of TiO₂ to graphene（100∶1） for TiO₂/graphene composites, calcination temperature of 500 ℃ and calcination time of 1 h, the photocatalytic degradation rate of methyl orange was as high as 88.33%.

Control Synthesis of TiO₂ Tubular Nanomaterials in a Novel Solvent Thermal System

Liu Jin, Zhao Hui

2018, 39(6): 76-80. doi: 10.7513/j.issn.1004-7638.2018.06.012

Abstract(10) PDF(1)

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TiO₂ tubular nanomaterials were synthesized using a novel solvent thermal system combined with heat treatment.The effect of TiF₄ concentration on morphology of the nanomaterials was investigated.The mass of the tubular structure increased with the increase of TiF₄ concentration.When the concentration of TiF₄ was 0.059 3 mol/L,the morphology of the obtained sample was superior.After the heat treatment,the main item was converted into TiO₂ nano-tubular material,and a conversion efficiency of 4.31% can be obtained for the dye-sensitized solar cell constituted by the sample.

Effects of Plasma Arc Surfacing Current on Microstructure and Wear Resistance of High Vanadium Fe-based Surfacing Coating

He Meng, Teng Yuancheng, Li Xin, Lu Weiyuan

2018, 39(6): 81-87. doi: 10.7513/j.issn.1004-7638.2018.06.013

Abstract(15) PDF(1)

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High vanadium Fe-based surfacing coating was prepared by plasma arc surfacing technology. The effects of plasma arc surfacing current on phase composition, microstructure, hardness and wear resistance of high vanadium composite Fe-based surfacing coating were studied by scanning electron microscope（SEM）, multifunctional stereomicroscope, energy spectrum（EDS）, X-ray diffraction（XRD）, hardness tester and wear tester, respectively. The results show that the surfacing current has a great influence on the microstructure and comprehensive mechanical properties of the coating and the main crystalline phases of the surfacing coating are martensite, VC and M₇C₃-type eutectic carbide. Small spherical VC particles with dispersive distribution in martensite matrix and（Fe, Cr, V）₇C₃ eutectic carbide form a wear-resistant skeleton. The alloy surfacing coating prepared at 160 A of surfacing current has better comprehensive mechanical properties, with 63.3（HRC） of surface hardness and 0.042 7 g of wear capacity for the surfacing coating.

Extrusion Process Optimization of Magnesium Alloy Containing Titanium

Liu Zhiying, Wang Xiaofeng

2018, 39(6): 88-92. doi: 10.7513/j.issn.1004-7638.2018.06.014

Abstract(14) PDF(1)

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In order to optimize the extrusion process of Mg-5Al-1Zn-0.8Ti magnesium alloy containing titanium, the microstructure and mechanical properties of the samples were tested and analyzed under different extrusion temperatures and extrusion speeds. The results show that with the extrusion temperature increasing from 325 ℃ to 425 ℃ and the extrusion speed increasing from 1 to 5 m/min, the average grain size of the samples decreases first and then increases, and the mechanical properties increase first and then decrease. Compared with the sample extruded at 325 ℃, the average grain size reduces by 34%, the tensile strength and yield strength respectively increase by 24% and 29%, while the elongation after fracture decreases by 28%, for the sample extruded at 400 ℃. Meanwhile, compared with the sample extruded at 1 m/min of speed, the average grain size decreases by 26%, the tensile strength and yield strength separately increase by 12% and 14%, while the elongation after fracture decreases by 21%, for the sample extruded at 3 m/min. The optimum extrusion process parameters of Mg-5Al-1Zn-0.8Ti alloy are determined at 400 ℃and 3 m/min of speed.

Effect of Acid-base Modified Steel Slag on Phenol Removal from Organic Wastewater

Wan Meifang

2018, 39(6): 93-98. doi: 10.7513/j.issn.1004-7638.2018.06.015

Abstract(16) PDF(1)

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Phenol-containing waste water has become a major issue in the water treatment industry because of its low biodegradability, intractability, and toxicity. Using steel slag as raw material, acid and alkali modified steel slags are obtained by different methods. Scanning electron microscopy（SEM） and specific surface area（BET） test had been taken to analyze the structure, properties and chemical composition of steel slag before and after modification. The osmotic process was applied to the phenol treatment of organic waste water. The reaction time, steel slag particle size, solution pH, and the like were discussed in detail. The effect of slag dosing amount on the removal of phenol in organic wastewater was investigated. The optimal treatment conditions were determined and the kinetics principle was analyzed. The results showed that for unmodified steel slag the optimal treatment parameters are as follows: particle size in 74～150 μm steel slag dosing amounts 8 g/L, the reaction time 55 minand pH=4, the resulted removal rate of phenol in waste water is 41.2%. For acid and alkali-modified slag the removal rate are 36.08% and 38.67% respectively.

Study on Direct Alloying of Waste SCR Catalysts

Chen Guangyu, Kang Jialong, Liu Junjie, Liu Lixia, Zhang Fang, Peng Jun, An Shengli

2018, 39(6): 99-102. doi: 10.7513/j.issn.1004-7638.2018.06.016

Abstract(13) PDF(1)

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TiO₂ in the waste SCR catalysts was reduced by aluminum, and the SiO₂-TiO₂-CaO-Al₂O₃-CaF₂-Na₂O slag system was selected. As the reduction process progresses, TiO₂ in the slag gradually decreases and Al₂O₃ gradually increases. The product titanium can transfer into the iron liquid to form the iron-titanium alloy, which can realize titanium recovery from the waste SCR catalysts. Calculated by the thermodynamic software Factsage 7.1 Equilb module, the slag compositions after completion of the reaction were 3% of SiO₂, 15% of CaO, 44% of CaF₂, 2% of Na₂O and 35% of Al₂O₃, with 2.5% of titanium content in the steel. In the phase diagram, the A, B, C, and D points were selected on the path of composition change. The viscosity of the slag in the reduction process was calculated by the viscosity module of Factsage 7.1. It is concluded that the slag viscosity is less than 0.03 Pa·s during the reduction process, indicating well liquidity. According to the experiment and analyses, the titanium content in the steel reached 1.67%, 67% of the calculated value. A large amount of TiO₂ in the slag was reduced into the steel, and the direct alloying of titanium from the waste SCR catalysts can be basically achieved.

Effect of Magnetic Field on Reduction of Iron Oxides Containing SiO₂ and CaO

Jin Yongli, Han Futie, Yu Hai, Zhao Zengwu, Zhang Jieyu

2018, 39(6): 103-109. doi: 10.7513/j.issn.1004-7638.2018.06.017

Abstract(23) PDF(1)

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In order to investigate the effects of magnetic field on the reduction of iron oxides, 93% Fe₂O₃-2.5%SiO₂-4.5% CaO system had been taken to carry out a constant magnetic field（CMF） test. The reduction conversion efficiency of Fe₂O₃, the phase composition and micromorphology of the reaction product, and the reaction kinetics were analyzed. The results show the reduction of Fe₂O₃ has been greatly enhanced in a CMF equal to 1.02 T. Compared with the reaction without a magnetic field, with a CMF（B=1.02 T） there is no new phase formed in the gas-solid reaction and the reduction product exhibits a porous structure. The internal diffusion coefficient obtained in a CMF is 1.34 times higher than that without a magnetic field.

The Impact of Basicity on the Green Ball Quality and Cruslring Strength of Pellets

Yan Zhaozhao, Lu Jianguang, Lü Qing, Zhang Shuhui, Liu Xiaojie, Sun Zhe

2018, 39(6): 110-115. doi: 10.7513/j.issn.1004-7638.2018.06.018

Abstract(15) PDF(1)

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In this paper the impact of basicity on the green ball quality and cruslring strength of pellets had been investigated by changing the ratio of A fine powder and B mineral powder. When the basicity is increased, the incidence strength and the compression strength of the green ball gradually decrease, but thermal explosion temperature increases. At the same time hematite crystal grains develops and grows up continuously in the process of roasting,however, the low melting point silicate minerals producing in the pellets increases in volume and aggregate together, which will worsen the connection degree of hematite crystal, at the same time, the ratio of pore in pellets increases, causing the decrease in compressive strength of pelletsgradually.

Effects of MgO and Al₂O₃ on the Formation of Calcium Ferrite

Wang Zhixing, Shi Xuefeng, Hu Changqing, Wang Xiaolei, Yang Jintao

2018, 39(6): 116-121. doi: 10.7513/j.issn.1004-7638.2018.06.019

Abstract(21) PDF(1)

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Calcium ferrite as binder phase of high basicity sinter has greatinfluence in the metallurgical properties of sinter. In this paper the influence of MgO and Al₂O₃ on the formation process was studied. According to the precious study on calcium ferrite, different amounts of MgO and Al₂O₃ were added to the fixed ratio raw materials of CaO and Fe₂O₃·X ray diffraction analysis and metallographic microscope was carried out after sintering, to analyze the effects of MgO and Al₂O₃ on the formation of calcium ferrite. When MgO is n the range of 0.5%～2.5%, with the increasing of MgO content, calcium ferrite first increases and then decreases, and reaches the maximum when MgO is between 1.5%～2.0%. When the content of MgO is 2.0%, the ore pahse structure is ideal. Al₂O₃ can promote the solid solution of Fe₂O₃ in calcium ferrite and the formation of liquid phase in two calcium ferrite, so as to promote the transformation of calcium ferrite into silico-ferrite of calcium and aluminum.

Influence of Slag Containing Titanium on the Corrosion of Refractories Used in Blast Furnace Hearth

Xu Renze, Zhang Jianliang, Zhao Yong'an

2018, 39(6): 122-128. doi: 10.7513/j.issn.1004-7638.2018.06.020

Abstract(28) PDF(1)

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In order to clarify the influence of TiO₂-containing slag on the corrosion of refractories used in blast furnace hearth, the corrosion behavior of blast furnace hearth refractories such as carbon composite brick and corundum brick in CaO-SiO₂-MgO-Al₂O₃-Cr₂O₃-TiO₂ slag was investigated by using finger rotation method. The experimental result indicated that the comprehensive effects of slag penetration, the components of the carbon composite brick dissolution and slag-brick interaction eventually resulted in the corrosion of carbon composite brick. The corrosion of corundum brick was mainly due to the infiltration of slag and the dissolution of brick. According to the XRD results, the surface products of the carbon composite brick after corrosion were C, Al₂O₃, melilite, spinel, calcium-aluminate, Cr₇C₃ and TiC. The surface compositions of the corroded corundum brick were Al₂O₃, SiC, spinel, melilite and TiC. Compared with the corrosion behavior of carbon composite brick and corundum brick in slag containing TiO₂, due to the existence of C and SiC in carbon composite brick, the slag corrosion resistance of the carbon composite brick was better than that of corundum brick.

Study on Mechanism of Gasification Dephosphorization and Influence of Next Heat Smelting Process

Zhou Chaogang, Ai Liqun, Wang Shuhuan, Guo Ruihua, Xue Yuekai, Zhao Dingguo, Li Chenxiao, Hou Mingshan

2018, 39(6): 129-136. doi: 10.7513/j.issn.1004-7638.2018.06.021

Abstract(14) PDF(2)

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In order to solve the problem that BOF slag can not be returned back into BOF due to its high P content,the dephosphorization mechanism of gasification and influencing factors,effect of slag remaining operation and lance controlling on dephosphorization,and morphology of gasification dephosphorization slag were analyzed by FactSage7.2 and SEM+EDS in this paper.The result shows that it is feasible to use C to reduce P of P₂O₅ for slag when temperature exceeding 941 K,and it is beneficial to the gasification dephosphorization reaction by reducing the reaction partial pressure.While taking coke powder as a reducing agent,the best results of gasification dephosphorization were obtained when the carbon equivalent and bottom blowing flow were controlled at 2 times the carbon equivalent and 300 m~3/h,respectively.Gasification dephosphorization rate can reach a maximum value of 42% when bottom blowing flow,carbon equivalent,FeO content are 300 m~3/h、2 times and≥18%.When using slag remaining operation for gasification dephosphorization mode of splashing furnace protection,where higher blowing lance operation at the early stage and gradually lower high and low blowing lance operation at later stage,the phosphorus content of molten steel at the end is relatively low.SEM observation on morphology structure of gasification dephosphorizationslag indicated that P mainly concentrated in enriched Ca and Si areas.

Research on EMS Technology for Continuous Casting 20CrMnTiH（FQ）Bloom

Li Hongguang, Zhang Xiansheng, Chen Tianming, Chen Liang, Yang Wenzhong

2018, 39(6): 137-142. doi: 10.7513/j.issn.1004-7638.2018.06.022

Abstract(14) PDF(3)

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Continuous casting EMS technology for optimizing internal quality of 20CrMnTiH（FQ）gear steel bloom had been researched,based on the equipment of 360 mm×450 mm bloom casting machine conditions.In order to determine the position of F-EMS applied to the end of liquid core,numerical simulation calculation had been carried in terms of the process of solidifying and heat transfer,and measured the effect of stirring magnetic field intensity on bloom internal quality.Based on the research results,the optimal process parameters of combined-EMS had been determined and then achieved the denser and homogeneous b 20CrMnTiH（FQ） gear steel bloom internal quality.

Numerical Simulation of Heat Transfer and Solidification in X80 Slab

Wang Lu, Sun Yanhui, Niu Apeng, Li Yaoguang, Chen Ruimei

2018, 39(6): 143-149. doi: 10.7513/j.issn.1004-7638.2018.06.023

Abstract(7) PDF(1)

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The solidification mathematical model was established by using X80 steel slab.The variationof the temperature and solidification rate of the 230 mm×1 280 mm X80 pipeline steel slab was simulated during the solidification process under different continuous casting process conditions.The effects of superheat,casting speed and cooling water on the solidification process of slab were studied.The results showed that the superheat had little effect on the solidification of the slab.With increasing of the superheat,the surface temperature of the slab increased andliquid pool length increased,while the length of two-phase zone decreased.The casting speed has the greatest effect on slab solidification The surface temperature,liquid pool length and the length of two-phase zone were all increased with the increase of the casting speed.Whenthe water ratio was increased,the surface temperature of the slab and liquid pool length decreased.

Control and Research of Inclusion in Ultra Low Carbon Steel

Liu Junshan, Ni Hongwei, Zhang Hua, Cheng Rijin

2018, 39(6): 150-154,167. doi: 10.7513/j.issn.1004-7638.2018.06.024

Abstract(12) PDF(1)

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In order to solve the problem of large amount of inclusions in ultra-low carbon steel,these measurement such as optimizing the modifier composition,controlling the temperature of RH inlet temperature,adjusting the time interval between adding Al to deoxidize and alloying,and optimizing composition of the slag had been utilized.It was found out that by adjusting the ratio of small particles of lime and aluminum slag,total iron content decreased from 29.5% to 10.9% after the modification.At a reasonable temperature of inlet molten steel the inclusion due to the blowing oxygen during RH process can directly reduced.In RH smelting,when Al and Ti are added without time interval,a large amount of Al-Ti composite inclusions will generate in the molten steel,which will lead to the blockage of the nozzle. Controlling the interval time between adding Al and add Ti alloy more than 150 s can effectively reduce the frequency of nozzle clogging.The percentage of cold rolling inclusion defects had been decreased from 0.33% to 0.15%.

Study on Production Technology and High Heat Input Welding Property of Q345 Grade Ti-oxide Metallurgy Steel

Li Yuqian, Du Qiming, Mei Donggui, Cheng Huimei

2018, 39(6): 155-161. doi: 10.7513/j.issn.1004-7638.2018.06.025

Abstract(12) PDF(2)

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Effects of Ti-oxide metallurgy and TMCP process on the matrix mechanical properties and high heat input welding property of Q345 grade steel plate were studied under industrial conditions.Microstructures and inclusion characteristics were analyzed by OM,SEM and EPMA.High heat input welding simulation and EGW experiments were carried out.Results indicated that the industrially produced steel plates obtained good matrix mechanical properties and high heat input welding property.Fine-sized inclusions containing Ti,Ca and Mg were distributed uniformly in steel,which promoted the formation of acicular ferrite structure in CGHAZ effectively.Impact toughness of the weld joint under 200 kJ/cm was improved significantly.

Mechanism of Hydrogen Evolution Reaction of Ni-Mo-C Alloy Electrode by Electroplating

Qi Haidong, Lu Shuai, Guo Zhao, Zhang Linan, Li Yungang, Yang Haili

2018, 39(6): 162-167. doi: 10.7513/j.issn.1004-7638.2018.06.026

Abstract(12) PDF(1)

Abstract:
Ni-Mo-C alloy electrode material was prepared on pure copper by electroplating.Linear sweep voltammetry（LSV）,cyclic voltammetry curve（CV） and electrochemical impedance spectroscopy（EIS） were used to investigate reaction mechanism of hydrogen evolution in 1 mol/L NaOH solution.The results show that hydrogen evolution reaction（HER） is a two-step reaction including adsorption and desorption of H_ads and HER is irreversible and controlled by the rate of the mass transfer.Carbon can inhibit the adsorption of H_ads,enhance desorption property of electrode for H_ads and improve the HER property.Mo has hydrogen desorption synergistic effect with Ni when potential is high,which will enhance the property of HER.

Effect of Heat Treatments on the Microstructure and Mechanical Properties of GH4169 Superalloy

Chen Jintong, Jiang Haiqing, Pan Huiyi, Xia Haidi, Yang Zirun, Jiang Qiong, Fang Leiqi

2018, 39(6): 168-172. doi: 10.7513/j.issn.1004-7638.2018.06.027

Abstract(38) PDF(1)

Abstract:
In this paper,GH4169 alloy was treated by three different heat treatment processes.The microstructure and mechanical properties of GH4169 superalloy under three different heat treatment processes were observed and studied by OM,SEM,the micro-hardness and impact test.The results show that different heat treatment process lead to different precipitation and distribution of δ phase in GH4169 superalloy.δ phase is short rod like or granular precipitates at grain boundaries after HST treatment,while δ phase can be obtained in the grain boundary and crystal after ST treatment.For DA treatment the grain boundary is smooth and no δ phase precipitation can be observed.After HST and ST treatment,the hardness of GH4169 superalloy did not change,the impact strength obviously increased and the fracture mode was transgranular fracture.After DA treatment,the hardness of GH4169 superalloy decreases down to 60% of as-hot rolled,but the impact strength increased by 4.5 times and the fracture mode showes interguanular fracture.

2018 Vol. 39, No. 6