钢铁钒钛

Sulfuric Acid Dissolution of Panzhihua Ilmenite Under Simultaneous Milling

Li Gaolan, Du Changshan, Lü Li, Wu Guilan, Liang Bin, Wu Pan, Li Chun, Zheng Qi

2012, 33(4): 1-6.

Abstract(23) PDF(1)

Abstract:
The feasibility of rapid leaching of Panzhihua ilmenite in sulfuric acid through combined milling under industrially employed acid/ore mass ratio was investigated.The effects of the stirring speed of attritor,milling ball/ore mass ratio,reaction temperature and sulfuric acid concentration on the dissolution were examined.The results show that with the simultaneous milling and dissolution the 1 h Ti leaching rate was 64% higher than that without milling under the otherwise same conditions due to lattice deformation and noticeably refined particles resulted from the milling.Optimized leaching conditions were obtained as follows: stirring speed at 700 r/min,ball/ore ratio at 5∶ 1,acid/ore ratio at 1∶ 1.6,sulfuric acid concentration at 70% and temperature at 120 ℃.Under these conditions,a titanium leaching rate of 81% was reached in 60 min and the stability of the titanyl sulfate solution thus obtained was higher than 550 mL.Therefore,direct digestion of ilmenite in 70% of sulphuric acid solution is feasible,which can fully reuse the hydrolyzed waste sulfuric acid discharged in the sulfate pigment production.

Study on Roasting of Pangang Converter Vanadium Slag with Soda in Laboratory

Li Qianwen, Liu Fengqiang, Deng Xiaobo, Hu Li

2012, 33(4): 7-11.

Abstract(29) PDF(1)

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Under laboratory conditions,the main effect factors of soluble vanadium recovery from converter vanadium slag was investigated.The main factors included soda-vanadium-ratio,slag-residue-ratio,maximum roasting temperature,keep time at maximum roasting temperature.The results showed that in the conditions of 3.4 soda-vanadium-ratio,2∶ 3 slag-residue-ratio,820 ℃ roasting temperature,120 min roasting time,the soluble vanadium recovery rates up to 90% was obtained,the TV content in the dry water leached residue was down to 0.6%,the leaching solution was clear.

Research on New Antibacterial Flame Retardant TiO₂/Mg（OH）₂ Composite Material

Li Xue, Li Yanping, Yang Pengfei, Meng Bo, Liu Yunyi

2012, 33(4): 12-17.

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A new TiO₂/Mg(OH)2 multifunctional composite material was prepared by ammonia bubbling process.Nitrogen and iron codoped TiO₂ powder were obtained by the hydrothermal method using titanium tetrabutoxide as precursor and ammonium nitrate and Iron(Ⅲ) nitrate nonahydrate as nitrogen and iron source.The composite material was characterized by XRD,FE-SEM,FT-IR and TG.The results indicate that at 75 ℃,the particle size distribute uniformly(D₅₀=0.69 μm) with ammonia feeding time for 1h.SEM analysis shows that the flake-like hexagonal product is of good dispersibility.XRD analysis indicates that it's I₍₀₀₁₎/I₍₁₀₁₎=0.71.TG-DTA analysis indicates that the water loss was 24.9% of the total weight between 322 ℃ and 396 ℃ with the highest endothermic temperature at 376.2 ℃.The quality of samples could satisfy the demand of flame retardants.The photodegradation rate of the Rhodamine b is 56.3%.

Effect of Phase and Morphology of the TiO₂ Nanotube Array on Its Photocatalytic Activity

Tian Ang, Xue Xiangxin, Liu Chuangwei, Ru Hongqiang

2012, 33(4): 18-23.

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TiO₂ nanotube array（TNT） coatings were anodized on the titanium surface,and the effect of the phase and morphology of the TiO₂ on the photocatalytic activity was researched.The studies indicate that the photodegradation of organic contaminant by TNT depends on the hydroxyl radical which is synthesized by the photogenerated holes and oxidizer in the solutions,through depredating the contaminant by oxidizing the genes of organic compounds.By enlarging specific surface of aligned nanotube,the number of photoinduced electron in elemental area could increase,which results in improved degradation efficiency of organic contaminant.The less fluorine ion residues on the nanotube array,the higher percent of photodegradation.That’s because under UV irradiation,the negatively charged fluorine ion tends to react with positively charged photo-holes.In addition,due to the fluorine ion residues,Ti³⁺ appears in the nanotube,resulting in reduction of the electrons.Under conditions of low temperature annealing,the morphology of nanotube is not significantly altered.The main effect which can influence the property of semiconductor is phase conversion.Dominated with anatase structure,the TNT facilitates the separation and transmission of photogenerated electrons and holes,thus improving photocatalytic properties.

Influence of Iron Coating on Chroma of Titanium Dioxide

Wu Jianchun

2012, 33(4): 24-27.

Abstract(19) PDF(1)

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Complexional titanium dioxide was prepared by surface treatment technology using TiO₂ and FeCl₃ as raw materials.Chroma was used to characterize the samples.In the experiment,the factors which affect the color of the sample,including coating quantity,coating temperature,aging time,and calcining temperature and time were systematically investigated.Resultsshow that the optimal technological parameters of synthesizing complexional titanium dioxide are as follows: coating temperature at 85 ℃,feeding time for 45min,aging time for 30 min,iron coating quantity of 5%,and calcining temperature at 600~700 ℃.

Study on Direct Reduction of Carbon-containing Pellet Made of Vanadium-bearing Titaniferous Magnetite

Cao Mingming, Zhang Jianliang, Xing Xiangdong, Wen Yongcai, Wang Chunlong

2012, 33(4): 28-33.

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On the basis of RHF technology,high-temperature calcination experiments were carried out in the laboratory to directly reduce carbon-containing pellet made of vanadium bearing titaniferous magnetite.Through XRD analysis,the effects of carbon proportion（w_C/w_O）,reduction temperature and reduction time on metallization rate of pellet and content of carbon residue are discussed in this paper.The results show that: with the increase in reduction temperature,the metallization rate constantly increases while content of carbon residue decreases,and as the temperature rises,the metallization rate increases rapidly before 1 350 ℃ and reaches 90% or above at 1 350 ℃,and then levels off;with the increase in reduction time,the metallization rate of pellet firstly increases and then decreases and the carbon residue is gradually reduced,and when the reduction time is at 30 min,the metallization rate reaches the maximum（91.37%）;with the increase in carbon proportion（w_C/w_O）,the reduction of pellet is accelerated and metallization rate is improved,and when w_C/w_O is at 1.3,it reaches the maximum（94.28%）.

Experimental Study on Sticking Prevention in Fludized Bed Reduction of Iron Ore Powder

Zhou Yong, Zhang Tao, Tang Hailong

2012, 33(4): 34-39.

Abstract(29) PDF(3)

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The sticking of iron ore powder restricts the reduction of iron ore in fludized bed.The effects of sticking prevention by adding inert material into fludized bed,and the relationship between defluidization and composition and size of iron ore,reduction temperature and atmosphere,metallization rate,and kinds and quantity of inert material etc.are probed into through experiment in this paper.Then the mechanism of sticking is discussed.MgO is the best additive for sticking prevention with an adding amount below 5%;CaO comes second with the adding amount of 5%¹0%.Small amount of coke powder,dolomite,and CaCO3 has little effect on sticking prevention.The lower melting point,the smaller size,and the higher metallization rate and temperature the iron ore powder has,the easier it becomes defluidized.

Design of Flow Control Devices for Seven-strand Tundish Based on Numerical Simulation

Xu Hailun, Ma Chunwu, Li Zhi, Sun Tiehan, Han Zhanguang

2012, 33(4): 40-46.

Abstract(21) PDF(1)

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Fluid flow behavior of molten steel in tundish is a key factor which can influence solidification of the subsequent casting blank.Therefore,it is very necessary to design suitable flow control devices for tundish.The present research is based on the seven-strand "T" shaped tundish.According to the characteristics of "T" shaped tundish and the geometry size of seven-strand tundish,four kinds of flow control devices were designed.Velocity field,temperature field and effect of inclusion removal with different flow control devices were analyzed by using numerical simulation method.The results show that with flow control device "C",the uniformity of flow between strands is better than others,and the maximum temperature difference in tundish and between strands is 9 ℃ and 0.4 ℃ respectively,which shows relatively satisfied temperature uniformity.Also,the removal rate of inclusion reaches 89.12%.Thus,flow control device "C" is a suitable scheme for on-site use.

Industrial Test of Slagging Process in Large-sized Combined Blowing BOF

Cai Wei, Yang Libin, Wang Dong, Yu Wentao, Zheng Congjie, Tong Puqiao

2012, 33(4): 47-50.

Abstract(22) PDF(1)

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By analyzing the composition of liquid steel and the composition and petrographical characteristics of slag,the variation of slag composition during oxygen blowing,and the slagging processes and dephosphorization with the two slagging methods(scheme A and B) applied to the 210 t combined blowing BOF were investigated.A comparison between test results of the two slagging methods showed that scheme B was better than scheme A: first,the slag melted more rapidly at early smelting stage and the dephosphorization rate at early and medium smelting stages was 12.6% higher;second,the slag fluidity was better and mineral phase with high melting point was found less;third,the slag composition fluctuated more smoothly;fourth,the consumption of lime decreased by 11.5 kg/t,the L_p increased by 5.42,and the average dephosphorization rate of BOF increased by 2.7%.

Experimental Studies on Low Phosphorus Steel Produced from Top and Bottom Combined Blown Converter

Liao Peng, Qin Zhe, Hou Zewang, Zhang Xingzhong, Qiu Shengtao

2012, 33(4): 51-55.

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This paper studies the low phosphorus steel smelting process in the top and bottom combined blown converter.After dephosphorization pretreatment of hot metal and then deslagging in semisteel procedure,the same converter was used to smelt ultralow phosphorus steel with the remaining part of slag.The results show that with phosphorus content of 0.13% in the hot metal,basicities of semisteel and the final slag is controlled at around 2.0 and 3.6 respectively,total iron at 18% or so,deslagging volume of semisteel at 40% to 60%,the dephosphorization rate of semisteel peaks at 65% with an average of 50%,and dephosphorization rate of the final steel peaks at 98% with an average of 94.6%;phosphorus content in the final steel can be controlled under 0.007% with the minimum of 0.003%,satisfying the requirements of low phosphorus steel.

Study on Technologies of Reducing Ferrous Materials Consumption throughout Steelmaking Process

Li Jianquan, Ge Wensun

2012, 33(4): 56-61.

Abstract(26) PDF(1)

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In consideration of equipments and production process in the vanadium recovery ＆ steelmaking plant of Pangang,the influencing factors of ferrous materials consumption in steel production process have been analyzed.On this basis,the processes of desulphurization and V-extraction are optimized to reduce the iron loss during desulphurization and V-extraction.Converter steelmaking processes are optimized as well to reduce the content of TFe in slag.Furthermore,the management of continuous casting process is strengthened to increase the sequence casting heats in a single tundish and optimize the cutting process.With these countermeasures,the ferrous materials consumption in steel production is reduced by 4.79 kg/t.

Theoretical Research on the Effects of Oxygen Enrichment and Pulverized Coal Injection on Performance of Tuyere Raceway Zone in Blast Furnace

Ma Shiwei, Qiu Guibao, Lü Xuewei, Deng Qingyu, Wang Hua

2012, 33(4): 62-67.

Abstract(27) PDF(1)

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The effects of both the oxygen enrichment and pulverized coal injection(PCI) on the performance of tuyere raceway zone in 4^# blast furnace of Pangang,especially on the theoretical combustion temperature and composition of the gas,have been investigated by using the thermodynamics software FactSage.The results indicate that,under current operation conditions,the PCI of the 4^# blast furnace in Pangang can be increased to 185 kg/t.However,the PCI will reach the threshold at 245 kg/t.And both the oxygen enrichment and PCI can increase the temperature in raceway zone,but the effect of PCI is more significant compared with oxygen enrichment.The influences of both the oxygen enrichment and PCI on the composition of the gas are also different.

Study on Technologies of Dephosphorization during Semisteel Smelting in Converter

Zeng Jianhua, He Wei, Chen Yong

2012, 33(4): 68-72.

Abstract(22) PDF(1)

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To address the problems occurring during semisteel smelting in converter in Pangang,such as slow slagging,low rate of dephosphorization,and high rate of rephosphorization after converter smelting,corresponding measures have been taken to optimize slagging process,oxygen supply,bottom argon supply,and end-point control.With these countermeasures,the dephosphorization rate has been significantly increased.The production practice shows that the average dephosphorization rate is above 90% with single-slag process.In addition,the final phosphorus content can be controlled below 0.007%,and the rephosphorization rate after converter smelting can be controlled below 0.003%,satisfying the requirement for [P] controlled below 0.010% for steel products.

Effect of Titanium on the Precipitation Behavior of Inclusions in Niobium Microalloyed Steel

Zhao Baohua, Ke Changming, Zhong Xiandai, Xie Jun, Zhu Chengyi, Zheng Jianxin

2012, 33(4): 73-80.

Abstract(22) PDF(1)

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Experiments were conducted in a high frequency vacuum induction furnace to smelt titanium and niobium microalloyed steel with different titanium addition at 1 550 ℃ under Ar atmosphere,and then the samples underwent heat treatment.The effect of titanium additive amount on composition,microstructure,typical inclusions and macro mechanical property of the titanium and niobium microalloyed steel were analyzed.The results show oxygen content in the steel microalloyed with titanium and niobium decreases to about 20×10-6 after Al is employed to deoxidize and the utilization rate of titanium exceeds 80%.Inclusions in the steel were mainly sphere shaped or approximate to sphere shaped Al₂O₃,SiO₂,and TiO_x based complex inclusions.Cube shaped(Ti,Nb)(C,N) complex inclusions and NbC,TiC inclusions in the steel precipitate around the spherical oxide inclusions.A lot of fine(Ti,Nb)(C,N) precipitations after heat treatment can be seen with confocal laser scanning microscope.After heat treatment,with the increase of titanium content in the steel,inclusions with the size less than 1 μm increase significantly,while the inclusions with the size larger than 1 μm tend to decrease.Heated and held at 1 200 ℃,the austenite grain of the samples became smaller with the increase of titanium addition in the steel.Thus the microstructure was obviously refined in steel,which led to improvement of macro hardness of the steel.

Development of 80 mm Thick Q460 Grade TMCP Plate with High Toughness for Engineering Machinery

Li Defa, Wang Shisen, Xing Shuqing, Xiong Tao

2012, 33(4): 81-85.

Abstract(28) PDF(1)

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Based on low carbon and Cr-Mo with powerful carbide added,the 80mm thick Q460 grade plate for engineering machinery use was successfully trial-produced by TMCP process.Ultrafine grain and precipitated phase and bainite were fully taken advantage of to increase strength.By means of metallographic examination and inspection of mechanical properties,the results showed that the studied steel was composed of uniform ferrite and bainite,and had good mechanical properties including tensile property and low temperature impact toughness;A_KV under-60 ℃ was more than 180 J,and the impact fracture exhibited plastic deformation;SEM analysis showed that the area of dimple fracture was about 55%,and small inclusion in dimple was circular oxide.The result of TEM showed that high density dislocation existed in crystalline grain,and a large number of dispersed fine second-phase particles were separated out along dislocation line in the steel.

Investigation on the Influencing Factors of Carbon and Sulfur Segregations and Rational Process Parameters of 82B Hard Wire Steel

Wang Hongbin, Tang Haiyan, Li Jingshe, Wang Qingguo

2012, 33(4): 86-91.

Abstract(21) PDF(1)

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The behavior of carbon and sulfur segregations of 82B hard wire steel produced under different continuous casting conditions has been systematically analyzed based on field tests and laboratory analysis.The results show three factors including superheat,casting speed and F-EMS which influence segregation of billets work differently with the variations of inner parts and segregation elements.For the central segregations of carbon and sulfur,the effect of casting speed dominates over the other factors.Under high casting speed,proper increase of secondary cooling intensity could effectively decrease carbon and sulfur segregations of billet,especially for the central part of the billet.The hydraulic simulation of tundish shows the optimal casting speed should be 1.8 m/min.

Analysis on the Cause of Splitting during Tensile Test of High Strength Steel EH36 for Ship Plate

Shuai Yong, Chen Yuanqing, Fu Jun, Qiu Shengtao, Liao Peng

2012, 33(4): 92-95,100.

Abstract(21) PDF(1)

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Serious spitting phenomenon occurred in the center of the plate during tensile test of high strength steel EH36 for ship plate use.Metallographic examination and scanning electron microscope have been taken to observe the fracture and section of specimen.And then the causes of splitting have been identified and corresponding control methods have been proposed.The study results show that the direct reasons for splitting include banded structure and lamellar MnS inclusion in the center of the steel plate,while the fundamental reason is the central segregation of carbon,sulphur and manganese during continuous casting process.

Study on Surface Linear Defects of Non-oriented Electrical Steel Strip

Qi Haifeng, Tang Guangbo, Wang Xiaochun, Li Jiguang

2012, 33(4): 96-100.

Abstract(48) PDF(2)

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The surface "dark line" and longitudinal hair crack in W600 non-oriented electrical steel strip are observed by SEM.The cause of surface "dark line" defects found in the after coated strip is that foreign substances are embedded into the scratches of strip surface caused by the graphite bottom roll build-ups in the soaking furnace（SF） section of the continuous annealing line and then covered by the coating in the coating process;the cause of surface longitudinal hair crack defects found in both of the cold rolled strip and after coated strip is that the complex aluminate inclusions in the slab are broken due to deformation and then extruded out from the inside layer during hot and cold rolling processes.In order to eliminate the "black line",the graphite bottom rolls should be changed or cleaned at regular intervals,and sections for feeding wet H₂+N₂+H₂O gas should be reduced from the original 6 to 4 and the furnace temperature in these four sections should be controlled under 880 ℃.In order to eliminate the longitudinal crack,inclusions in steel should be strictly controlled in refining and continuous casting processes to ensure the liquid level fluctuation in crystallizer kept at ±3 mm~± 5 mm.

Research on Banded Microstructure of Steel for Oil Casing Pipe

Shen Yongge, Chen Liansheng, Song Jinying, Tian Yaqiang

2012, 33(4): 101-106.

Abstract(17) PDF(1)

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Center segregation in strand for J55 oil casing pipe is analyzed and the influences of heating temperature, finish rolling temperature, deformation rate in noncrystallization area, cooling rate after finish rolling and coiling temperature etc.on the reduction or elimination of banded microstructure are researched by means of sulfur print, hot acid erosion, OPA, SEM and EDS.The result shows that it is the segregation of Mn that directly leads to the formation of banded microstructure in hot rolled strip, and the problem can be reduced or eliminated by increasing finish rolling temperature, deformation rate in noncrystallization area, cooling rate after finish rolling and coiling temperature and lowering coiling temperature, etc.

2012, 33(4): 107-108.

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2012 Vol. 33, No. 4