钢铁钒钛

Kinetics Study on Solid-phase Catalytic Reduction of Highly Impure Ilmenite by Thermal Analysis

Liu Yunlong, Guo Peimin, Pang Jianming, Zhao Pei

2013, 34(6): 1-5. doi: 10.7513/j.issn.1004-7638.2013.06.001

Abstract(36) PDF(1)

Abstract:
In order to reduce the highly impure ilmenite by carbon at solid phase,the mechanism of the catalytic reduction of ilmenite by thermogravimetric analysis has been studied. The results show that impurities hinder the process of ilmenite reduction. Low reduction rate occurs during the catalyst-free reduction process while a higher reduction rate and a faster reduction velocity can be achieved by adding a small amount of catalyst. The different anionic groups of catalysts have different effects on the reaction. In the case of the same molar concentration of sodium ion,the catalyst having the best catalytic effect is Na₂B₄O₇,successively followed by NaF,NaCl and Na₂SiO₃. In the temperature range of 860~1 100℃,the main rate-controlling step for ilmenite reduction is the interfacial chemical reaction. The apparent activation energy of the catalyst-free reaction is 260.976 kJ/mol; the reduction adding the catalyst of Na₂B₄O₇ has the lowest apparent activation energy of 226.182 kJ/mol.

Research on Sintering Phenomenon During Calcination of Vanadium Slag

Wang Chunqiong, Liu Wuhan, Liu Huiqian, Zhu Fuping, Zhang Lin, Sun Yuzhong

2013, 34(6): 6-11. doi: 10.7513/j.issn.1004-7638.2013.06.002

Abstract(54) PDF(3)

Abstract:
Sintering of roasting materials during calcination of vanadium slag may lead to low leaching ratio or even interruption of production processes. Reasons for material sintering and various influencing factors were studied. The research results show that the solid low melting point materials transform into liquid phase when the roasting temperature is higher than the melting point of the product,and larger diameter spherical sintered materials generate with revolving of rotary kiln. Roasting temperature and magnetic materials in the mixture are main factors for sintering. The length of firing zone is extended when the temperature is above 900℃,so low melting point materials have enough time to generate more liquid phase,result in sintering. With high magnetic material content in the mixture,temperature may be up to 1 000℃ locally due to superposition of the roasting temperature and the temperature rising during exothermic oxidation in the roasting process,and as a result the materials are severely sintered.

Research on Roasting Shaft Furnace for Vanadium Extraction from Stone Coal

Feng Junsheng, Dong Hui, Li Peng, Wang Aihua, Zhang Jingfan, Hu Jia

2013, 34(6): 12-16. doi: 10.7513/j.issn.1004-7638.2013.06.003

Abstract(26) PDF(2)

Abstract:
Based on analyses on traditional stone coal roasting equipments,a roasting shaft furnace equipped with internal vertical air channels(IVAC) and drying bed for vanadium extraction from the stone coal was developed. Through comparison with the roasting shaft furnace for vanadium titaniferous magnetite,the unique structure characteristics of the roasting shaft furnace for stone coal was elaborated,and structural and operating parameters of the latter was given. Furthermore,the first roasting shaft furnace for stone coal in China was established on this basis. The practice shows that the roasting shaft furnace is a reliable and economical roasting equipment for vanadium extraction from stone coal. It has many advantages, including controllability of temperature and atmosphere in furnace,high utilization coefficient,low energy consumption per unit product,and high vanadium recovery rate. This paper aims at introducing a new furnace type for vanadium extraction from stone coal and promoting the development of vanadium industry.

Effect of Premixing Process on Acidolysis of Ilmenite Concentrate

Wu Jianchun, Wang Bin, Chen Xinhong

2013, 34(6): 17-20. doi: 10.7513/j.issn.1004-7638.2013.06.004

Abstract(26) PDF(3)

Abstract:
To reduce the insolvable solid-phase object emerged during acidolysis of sulfate process route for titanium pigment production,the structures and compositions of the object are analyzed. It can be concluded through laboratory experiments that insufficient mixing of sulfuric acid and ilmenite concentrates and incomplete acidolysis reaction are main reasons for forming the solid-phase object which is difficult to be leached during acidolysis. Through taking the premixing process for acidolysis in a certain titanium pigment plant as an example,the factors that affect the premixing effects are further analyzed and solutions are proposed. By adjusting the preparation of sulfuric acid and reducing the temperature of sulfuric acid,the problems including low leaching rate and large volume of residual solid-phase object are completely solved with the leaching rate reaching 96% and the volume of solid-phase object on the wall of acidolysis pot reducing from 30 m³ to less than 3 m³.

Experimental Study on Preparation of Ti-Al Master Alloy by Aluminothermic Reduction of TiO₂

Li Jun, Yang Shaoli, Wu Enhui, Hou Jing, Huang Ping

2013, 34(6): 21-24. doi: 10.7513/j.issn.1004-7638.2013.06.005

Abstract(27) PDF(1)

Abstract:
Taking titanium pigment as raw material,experiments were conducted to prepare Ti-Al master alloy by aluminothermic reduction. Through single factor experiments,the optimum result was obtained with aluminum adding coefficient of 1.7,unit thermal effect of 2850 kJ/kg and lime adding coefficient of 0.9. Under this process condition,good smelting results and high yield of alloy were achieved. Analyzed by XRD diffraction,the phase compositions of the Ti-Al master alloy mainly consisted of Ti_3.3Al.

“One Step” Aluminothermic Reduction Process for Preparation of High-purity Vanadium-aluminium Master Alloy with Water-cooled Copper Crucible

Peng Yumin, Wang Heng

2013, 34(6): 25-28,44. doi: 10.7513/j.issn.1004-7638.2013.06.006

Abstract(27) PDF(1)

Abstract:
In order to achieve the goal of lowcost production of high-purity V-Al master alloy,the feasibility of employing water-cooled copper crucible to prepare the alloy by"one step"aluminothermic reduction process is probed into. After several rounds of experiments,compared with the traditional refractory furnace in raw material preparation,production process,reaction and chemical compositions of the alloy produced,the water-cooled copper crucible can realize lower impurity content in alloy,higher yield of vanadium and more stable reaction. It can basically meet the requirement of lowcost production. Furthermore,the reasons for those results are discussed in detail.

Effect of Different Binder Addition on Strength of Carbon-containing Pelletized Blast Furnace Dusts

Jia Jihua, Han Hongliang, Duan Dongping, Feng Gensheng

2013, 34(6): 29-32. doi: 10.7513/j.issn.1004-7638.2013.06.007

Abstract(42) PDF(1)

Abstract:
According to physical and chemical characteristics of blast furnace dusts,an experimental study on different binder for the carbon-containing pelletized dusts was carried out. The experiment results show that different binder has different mechanism for binding pellets,which leads to different binding effect on green pellets,dry pellets and finished pellets. According to using effects of the binders,it can be concluded that the best choice is the composite binder,followed by the inorganic binder of sodium silicate. This study can provide theoretical and technical basis for efficient utilization of blast furnace dusts.

Study on Melting Rate of Metalized Pellets of Vanadium-bearing Titaniferous Magnetite

Xing Xiangdong, Zhang Jianliang, Xu Chenliang, Wang Zhenyang, Liu Xingle

2013, 34(6): 33-38. doi: 10.7513/j.issn.1004-7638.2013.06.008

Abstract(36) PDF(1)

Abstract:
The effect of influencing factors including melting temperature,alkalinity,slag to iron ratio and metalizing rate on the melting rate of metalized pellet of vanadium-bearing titaniferous magnetite was studied. The results indicate that the melting rate increases with the increase of melting temperature, metalizing rate and slag to iron ratio,and there is a kind of linear relationship between metalizing rate and melting time under certain conditions. When the alkalinity approaches 1.1,the melting time is the shortest,which means the melting rate is comparatively fast. However,when the alkalinity is either too high or low,the melting time increases.

Experimental Study on Magnetite Separation of Iron and Titanium from Metallized Pellet of Vanadium-bearing Titaniferous Iron Ore Concentrate

Huang Ping, Wu Enhui, Yang Shaoli, Hou Jing, Li Jun

2013, 34(6): 39-44. doi: 10.7513/j.issn.1004-7638.2013.06.009

Abstract(41) PDF(2)

Abstract:
The metallized pellet of vanadium-bearing titaniferous iron ore concentrate containing iron,vanadium,titanium and other elements is the product of coal-based direct reduction of the concentrate in rotary hearth furnace. By using laboratory wet magnetic separator,a new technology of magnetite separation of iron and titanium from metallized pellet was introduced,and its feasibility was also studied by experiments. The effects of current intensity,particle size and ore to liquid ratio on the recovery rate of iron and titanium were examined through orthogonal experiment. The experimental results show that the recovery rates of iron and titanium are 90% and 45% respectively with the current intensity of 2.5 A,particle size of 74 μm and ore to liquid ratio of 1:7.

Water Modeling Experiment of Removing Inclusions from Molten Steel by Bubble Adhering

Yang Hulin, He Ping, Zhai Yuchun

2013, 34(6): 45-49. doi: 10.7513/j.issn.1004-7638.2013.06.010

Abstract(10) PDF(1)

Abstract:
In order to make clear how non-metallic inclusions were removed from molten steel through bubble adhesion,water modeling was carried out to monitor the process with high-speed video and image processing software. The mechanism of inclusion removal by bubble adhering was analyzed,and the influencing factors including bubble diameter,inclusion diameter,and inclusion contact angle were also investigated. The results show that it is an effective way to remove inclusions with bubble adhering. The adhering process can be divided into 3 sub-processes:first,the bubbles get close to the inclusion particles; second,the bubbles collide with the particles and attach to them; finally,the particles float up with the bubbles in dynamic stability. When the bottom blowing flow rate is constant,it is effective to decrease the bubble size to improve the efficiency of remove inclusions by adhering to bubbles.

Study on Mineral Phases of Blast Furnace Slag with Medium Titanium Content

Liu Lina, Han Xiuli, Li Zhimin, Liu Lei

2013, 34(6): 50-53. doi: 10.7513/j.issn.1004-7638.2013.06.011

Abstract(30) PDF(2)

Abstract:
Microstructures,mineral compositions,shapes and sizes of the blast furnace slag with medium titanium content were systematically studied by polarizing microscope and scanning electron microscopy. The results show that the slag consists of granular poikilitic and porphyritic microstructures,and its mineral compositions are mainly composed of melilite,followed by spinel,perovskite,titanium diopside,and a small amount of metallic iron,titanium nitride,titanium carbide and their solid solution. Titanium exists mainly in the form of perovskite,followed by titanium diopside. The perovskite,spinel,titanium nitride,titanium carbide and their solid solution in slag have great influence on the viscosity of slag.

Experiment Research on Deep Desulphurization of Non-oriented Electrical Steel

Liao Jianjun, Qin Zhe, Qiu Shengtao, Lai Chaobin

2013, 34(6): 54-59. doi: 10.7513/j.issn.1004-7638.2013.06.012

Abstract(6) PDF(1)

Abstract:
In order to satisfy the requirements of consumers on sulfur content in non-oriented electrical steel,taking(CaO-CaF 2) based flux as desulfurizer,industrial experiments on deep desulphurization of non-oriented electrical steel were carried out during RH process. The results show that as the compositions of refining slag are appropriately controlled with w_CaO of 43%~51%,w_Al₂O₃ of 25%~31%,w_MgO of 4%~6%,w_SiO₂ of 9%~12%,and w_{(FeO + MnO)} of 3%~6%,and the desulfurizer added are at 6~8 kg/t,the average sulfur content in liquid steel can be reduced from 32 × 10^-6 to 18 × 10^-6 with the average and highest desulphurization degrees of 43.3% and 47.1% respectively. Calculated with KTH model,the average sulfide capacity in final slag is 0.0031,and the average equilibrium distribution ratio of sulphur in the final slag increases from 14 to 52 at the end of refining in RH.

Formation Pattern of Inclusions in Ti-deoxidized Steel and Their Effect on Microstructures

Shang Deli, Lv Chunfeng, Kang Lei

2013, 34(6): 60-64. doi: 10.7513/j.issn.1004-7638.2013.06.013

Abstract(16) PDF(3)

Abstract:
The change pattern of oxygen content and inclusions in liquid steel during deoxidizing was investigated through experiments,and the relationship between inclusions and microstructures was also analyzed. The results show that the oxygen content stabilizes around 0.001%(mass fraction) after deoxidizing,and the inclusion size reaches the average minimum value of 1.27μm after deoxidizing for 4 minutes when acicular ferrite distributes uniformly in the steel.

Study on Tanggang FTSC Tundish with Gas Curtain

Xu Haifang, Jia Jihua, Ma Xinguang, Wang Aidong, Fu Qiuhua, Ma Dong, Wu Yuangang

2013, 34(6): 65-71. doi: 10.7513/j.issn.1004-7638.2013.06.014

Abstract(10) PDF(1)

Abstract:
Taking Tanggang FTSC tudish as the prototype,tundish schemes with gas curtain installed in different position are designed. The research on flow fields of steel in the tundish and inclusion movement in different scheme shows that the gas flow rate and gas blowing position have noticeable effect on the flow fields and the inclusion movement. The parameters including T_av,V_dead,V_plug,and V_mix are obtained through RTD curve. It is believed that reasonably designed gas curtain can improve the flow fields of steel in the tundish,and the increase of residence time of steel in the tundish is favorable to the removal of the inclusions.

Influence of Various Manufacturing Techniques on Seismic Performance of High Strength Rebars

Yang Xiongfei, Sheng Guangmin, Lv Yukun, Cheng Xingde

2013, 34(6): 72-78. doi: 10.7513/j.issn.1004-7638.2013.06.015

Abstract(6) PDF(1)

Abstract:
Comprehensive seisimic performance of grade 400 MPa rebars manufactured by V-N microalloying,QST and fine-grained process routines was experimentally evaluated according to increasingly accepted earthquake resistant evaluation index based on high strain low cycle fatigue behavior. Vanadium microalloyed rebar shows clear advantage over QST and fine-grained processed rebar in terms of high strain low cycle fatigue life and cyclic toughness,weldability,strain aging sensibility and FATT as well. TEM photos reveal formation of dislocation cells with thicker wall and high density dislocation during cyclic loading which results in deformation energy dissipation due to the existence of fine dispersed V(C,N) particles,consequently facilitated uniform plastic deformation and leads to highest cyclic toughness value of V microalloying rebar.

Influence of Strands' Brittle Zones on Surface Cracks of Hypo-peritectic Steel

Zeng Yanan, Sun Yanhui, Ai Xi, Ma Zhifei, Liu Ruining, Liu Yong

2013, 34(6): 79-84. doi: 10.7513/j.issn.1004-7638.2013.06.016

Abstract(18) PDF(1)

Abstract:
In view of large amounts of cracks formed in the hypo-peritectic HSLA steel during solidification,the cracks on the surface of strands were analyzed by optical microscope,SEM and EDS,and the precipitates were studied by thermodynamic calculation. Furthermore,hot ductility was studied by Gleeble-1500. The results showed that steel matrix was deteriorated by inclusions(Fe,Mn,Si,Al)(S,O) in cracks,and transverse cracking sensitivity was increased by Ti-Al-(C,N) inclusions. The longitude cracks tend to appear in the high-temperature brittle zone with a longitude cracking sensitive range of 1 454~1 478℃,and the minimum value of Z was 37.59%; the transverse cracks tend to appear in the low-temperature brittle zone with a longitude cracking sensitive range of 900~750℃,and the minimum value of Z was 45.24%. Precipitating at 896℃,the ferrite led to strain concentration on the grain boundary,resulting in crack formation.

Experimental Study on High Collapse-Resistant Oil Casing SEW-110T

Wang Jun, Bi Zongyue, Zhang Feng, Wei Feng, Bai He, He Shilei

2013, 34(6): 85-90. doi: 10.7513/j.issn.1004-7638.2013.06.017

Abstract(2) PDF(1)

Abstract:
High collapse-resistance oil casing SEW-110T was designed and developed on the basis of sufficient understanding of the casing's operating conditions in oil field. The performances of SEW-110T were evaluated by tests of mechanical property,tensile strength,hydrostatic pressure and external pressure etc. The results show that the base metal and weld zone of SEW-110T have high strength as well as good toughness and ductility, and therefore SEW-110T shows good mechanical properties, tensile strength,and resistance to internal pressure and external pressure.

Experimental Study on Improving Strength and Toughness of Non-quenched and Tempered Casing Tube N80

Xie Degang, Wang Changshun, Chen Yong, Chen Kedong, Guo Haiming

2013, 34(6): 91-95. doi: 10.7513/j.issn.1004-7638.2013.06.018

Abstract(9) PDF(1)

Abstract:
Experimental study was carried out for improving strength and toughness of non-quenched and tempered casing tube N80. The results show that strength and impact toughness can be improved by adopting appropriate controlled cooling process after rolling or increasing cumulative deformation in the austenitic non-recrystallization zone,and better performance can be achieved with the combination of these two methods. The commercial production proves that the strength and impact toughness of the products so produced can be noticeably enhanced.

Effect of Cooling Rate on Microstructures and Properties of Welding Heat Affected Zones in X80 Pipeline Steel

Guo Lin, Huo Xiangdong, Li Liejun, Li Jianfeng, Dong Feng, Tian Zhenzhuo

2013, 34(6): 96-100. doi: 10.7513/j.issn.1004-7638.2013.06.019

Abstract(14) PDF(1)

Abstract:
The effects of cooling rate on microstructures and mechanical properties of welding heat affected zones in X80 pipeline steel were studied by thermal simulation test. After thermal simulation,the microstructures of X80 pipeline steel were observed by optical microscope,and the mechanical properties were tested with mechanical property testing technologies. The results show that the microstructures of X80 pipeline steel after thermal cycle are bainite and ferrite. With the increase of cooling rate,the bainite turns to granular and lath shape,and the ferrite to polygon and acicular shape. Acicular martensite appears as the cooling rate exceeds 50℃/s. The hardness of coarse grain area on welding heat affected zone does not show any significant decrease under different cooling rate.

Effect of Tempering Temperature on Microstructures and Properties of 9NiCrMo Steel

Tian Jingyun, Hong Bo, Shen Junchang

2013, 34(6): 101-105. doi: 10.7513/j.issn.1004-7638.2013.06.020

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Abstract:
Through testing,SEM and TEM observation and XRD analysis for common mechanical properties of 9NiCrMo steel under different tempering temperature,the effect of tempering temperature on mechanical properties and microstructures of the steel was studied. The steel shows relatively high strength and good lowtemperature toughness. As the tempering temperature increases,the yield strength and tensile strength peak near 550℃ and 570℃ respectively. Fine M₂C carbides precipitated play an important role in strengthening. Secondary martensitic precipitation is also a factor that cause the increase in strength. Good lowtemperature toughness can mainly be attributed to the appearance of very tiny secondary martensite lath,ferrite,and appropriate amount of reverted austenite.

Effect of Element Ni on Atmospheric Corrosion Behavior of High-strength Weathering Steel

Wang Junshan, Shi Peiyang, Liu Fenglian, Jiang Maofa

2013, 34(6): 106-109. doi: 10.7513/j.issn.1004-7638.2013.06.021

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According to characteristics of high-strength weathering steel for railway use,variation of resistance to atmospheric corrosion of the steel was studied by adjusting the content of nickel. The results reveal that with low content of nickel and chromium,there are cracks existing between the base metal and the inner rusty scale. As the content of nickel rises,the rusty scale becomes thinner and more compact. At the initial stage of sun exposure,the rusty scale is mainly composed of γ-FeOOH,and along with the time extending,α-FeOOH gradually forms. Moreover,the higher nickel content,the higher α-FeOOH to γ-FeOOH ratio.

Analysis on Scale on the Surface of Hot Rolled Strip and Furnace Roller

Jia Zhifang, Zhang Guijie, Hu Dehong

2013, 34(6): 110-114. doi: 10.7513/j.issn.1004-7638.2013.06.022

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Abstract:
By using instruments including metalloscope,scanning electron microscope,Xray diffractometer(XRD) and energy spectrometer,scale on the surface of hot-rolled strip steel produced by 1 810 mm hot-rolling mill and furnace roller was analyzed on layering phenomenon,microstructure,microtopography,composition,and internal atomic or molecular structure etc. The results show that there is a relatively large difference in scale microstructures of the hot rolled strip and the furnace roller. Microstructures of the roller scale are consistent with those of common scale while ferric oxide layer is absent in strip surface. The outer surface of the strip scale is more compact and the inner surface has more holes,smaller cracks and smaller grain size compared with those of the roller scale.

2013, 34(6): 115-116.

Abstract(21) PDF(1)

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2013 Vol. 34, No. 6