钢铁钒钛

Research on Preparing Technology of Synthetic Rutile by Hydrochloric Acid Leaching

Fu Zibi, Huang Beiwei, Wang Xuefei

2006, 27(2): 1-6.

Abstract(15) PDF(1)

Abstract:
The high grade synthetic rutile was prepared from Panzhihua ilmenite by preoxidation—fore-magnetic separation—acid leaching—filtration and lavation—calcination—after-magnetic separation.The influence of process parameters,such as ore property,leaching time,leaching temperature,hydrochloric acid concentration and the ratio of hydrochloric to ore on the acid leaching results were discussed under a manufacturing equipment of 1 000 t/a.Through the optimized testing and stability experiment,the thinning rate of product was controlled blow 15%,the recovery rate of titanium in total process was beyond 92% and the TiO₂ content of thick synthetic rutile was beyond 92%.The thin synthetic rutile was successfully separated from thick synthetic rutile.

Industrial Experiment of Producing Crude TiCl₄ by Fluid-bed Chlorination of Synthetic Rutile

Chen Deming, Hu Hongfei, Liao Ronghua, Zhu Shengyou

2006, 27(2): 7-11.

Abstract(17) PDF(2)

Abstract:
Titanium tetrachloride was produced in industrial experimental scale by the fluid-bed chlorinating process with the mixture of Panzhihua synthetic rutile (w(TiO₂)=91.04%,w(CaO+MgO)=0.94%) and high titanium slag (w(TiO₂)=88.05%,w(CaO+MgO)=1.85%),in which the ratio of high-grade titanium slag Panzhihua synthetic rutile was 50∶50~0∶100 in weight.The major equipment was the f800 mm fluid-bed reactor in Zunyi Titanium Co.,Ltd.The results show that the fluidizing behavior is good,the deslagging is smooth,the chlorination ratio of TiO₂ is up to 95%,and the quality of the titanium tetrachloride product measures up.

Applied Study on Aging Resistance of Rutile Nano-TiO₂ in HIPS Plastics

Cao Jianjun, Guo Gang, Wu Jianchun, Tu Mingjing

2006, 27(2): 12-16.

Abstract(27) PDF(1)

Abstract:
The polystyrene was filled and modified with rutile nano-TiO₂ as antiaging additives.It was noted that low molecule organic substance was ingrafted onto nano-TiO₂ after surface modification,consequently which upgrading its consistent and disperse property in HIPS resin.After 28 days exposed to xenon arc lamp,the mechanics of HIPS modified by nano-TiO₂ kept for a long time.Furthermore,the ability of resisting color aberration was improved,and that rupture of molecule chain was restrained effectively.According to FTIR analysis,the aging mechanism revealed that the cooperating effect of nano-TiO₂ in company with organic UV-absorbent could restrict aging rate of modified HIPS in effect.Moreover there was little change for absorbing characteristic of carbonyl and hydroxyl group in the 28 days accelerating aging period.

Preparation of Ultrafine Grain Austenitic High-nitrogen Stainless Steel by Spark Plasma Sintering

Zhang Xin, Liu Jing, Li Guangqiang

2006, 27(2): 17-20,47.

Abstract(21) PDF(1)

Abstract:
The SPS(spark plasma sintering) process was used to sinter 304 austenitic stainless steel powder made by milling.The sintering temperature is 900 ℃,and the sintering stress are 30 MPa and 50 MPa respectively.The phase composition and crystallite size of sintered sample were analyzed by XRD,SEM and TEM.The results show that the sintered sample matrix is austenite,and the crystallite size is 100~200 nm approximately.The density of the sample closes to steel,this show the sintering samples attain to high densification.The rigidity of the samples is higher than that of common austenitic stainless steel.The electrochemistry erosion and metallographic testing show that the more compact the better corrosion resistance of samples is.

Study on Super-fine Particle of TiN Added into Molten Pure Iron

Wang Guocheng, Fang Keming, Wang Tieming

2006, 27(2): 21-25.

Abstract(23) PDF(1)

Abstract:
The ingot specimen was obtained by melting industrial pure iron in which TiN particle with 2.7 μm size was added.The existent state and chemical component of nonmetallic inclusions in the metal-phase sample were investigated with SEM and EDS.The characteristic of nonmetallic inclusions extracted from ingot by the electrolytic method in the nonaqueous solution, such as morphology, size and chemical component, were studied with SEM and EDS.Experimental results show that there were high Ti contain in inclusions.There were a lot of white punctate MnS inclusions at some surface of Ti inclusions.Some TiN particle combined automatically with the inclusion in the molten.At last, the thermodynamic stability of TiN particle in molten pure iron was analyzed.

Progress in Modern Ironmaking Process

Zhang Dianwei, Guo Peimin, Zhao Pei

2006, 27(2): 26-32,47.

Abstract(18) PDF(1)

Abstract:
The leading smelting reduction and direct reduction processes were reviewed.The COREX,FINEX and HISMELT processes could eliminate the pollution from coking plant due to coke-needless operation.The industrialized COREX process is owing to the mature technology of shaft furnace gas-based direct reduction.The industrialization of FINEX and HISMELT is more difficult than that of COREX,considering the powder sticking in the fluidized bed and the conflict between secondary combustion and the lining corrosion in the iron bath furnace.The gas-based direct reduction(MIDREX,HYL-III,FINMET,et al) couldn't develop well in China because of the shortage of natural gas.The rotary hearth furnace(RHF) can use the low strength composite pellets.However,high power consumption,low productivity and low quality of the production are its disadvantages.A promising technology of ironmaking with fast reduction speed at low temperature was introduced,which has the advantages of low power consumption,environment-friendly,high productivity,low reduction temperature.

Study on Physical Modeling of Four-strand Tundish for Bloom Continuous Caster

Chen Yuanqing, Wen Guanghua, Zhu Mingmei, Tang Ping, Yang Subo, Zhang Longchao, Jie Mingke

2006, 27(2): 33-37.

Abstract(16) PDF(1)

Abstract:
Water model test was taken to install proper flow control devices for a near T type four-strand bloom casting tundish.Two schemes,"V type baffles + dams" and "turbo stopper + dams",were optimized by orthogonal experiments under isothermal and non-isothermal conditions.The results show there are short circuit flow and large dead volume in the tundish without control devices."V type baffles + dams" case 1 can obviously improve the flow field,which makes dead volume decrease,plug volume increase and temperature distribution uniform."Turbo stopper + dams" can improve the flow field to a certain extent,but short circuit flow and large dead region still exist and flow field and temperature distribution are quite asymmetric.

Numerical Simulation on Flow Field and Heat Transfer of Five-strand Unsymmetrical Configuration Tundish

Liu Dafang, Shi Zhe, Zhan Shuhua, Peng Shiheng, Chou Shengtao

2006, 27(2): 38-42,51.

Abstract(25) PDF(1)

Abstract:
In order to improve the billet quality by optimizing fluid flow,uniforming the molten steel temperature of each nozzle and prolonging the average residence time of near nozzles,the unsymmetrical configuration tundish in works and two optimal designs were studied by means of numerical simulation.The fluid flow,heat transfer and residence time in the tundish were calculated.The results show that fluid flow and temperature distribution were unsuitable in the original tundish without flow control devices.The fluid flow and temperature distribution were optimized in the tundish with optimal configuration.The optimum configuration was settled by the calculation results.

Numerical Simulation on Stamping of Laser Tailor Welded Blank

Qiu Xiaogang, Chen Wenlong

2006, 27(2): 43-47.

Abstract(12) PDF(1)

Abstract:
The stamping process of the tailor-welded blank was simulated by DYNAFORM software.The finite element model of a boxy part was founded,and the formability of tailor-welded blank with different thickness and material was studied.Meanwhile,the influence of weld seam on forming of the part was discussed.The results show that the weld seam model founded by real properties can describe the plastic deformation and strain distribution exactly in the forming process.

Metallurgical Effect of Ladle Furnace in Production Process of Pipeline Steel

Zhang Caijun, Cai Kaike, Yuan Weixia

2006, 27(2): 48-51.

Abstract(25) PDF(1)

Abstract:
The effect of desulfurizing,purifying and modifying inclusion at ladle furnace for pipeline steel was investigated.The results show the average desulfurization percentage was 55%,the removal percentage of total oxygen and micro inclusion were 43.3% and 44.4% respectively.The effects of desulfurizing and purifying were satisfactory.After the addition of calcium silicon alloy,the cluster alumina were modified into spherical calcium aluminate with low melting point,at the same time,the liner MnS inclusion were eliminated,and so improve the resistance against hydrogen induced cracking(HIC).When the addition of calcium-silicon wire was 0.7 kg/t,the inclusion modification was insufficient,so the addition should be increased appropriately.

Discussing on Technique of High Efficient and Long Lifetime for 4^# BF at PZH Steel

Diao Risheng, Ni Guoquan, Wang Ge

2006, 27(2): 52-56.

Abstract(15) PDF(1)

Abstract:
The first campaign of 4^# BF(blast furnace) at PZH Steel lasted for 5 296 days without intermediate relined,the unit yield of iron was 9 367.2 t/m³ and highest yearly average productivity exceeded 2.3 t/(m³·d).The high efficient and long production life of BF was related to furnace burden,operation,daily upkeep and so on.The operation factors effecting the availability coefficient and long production life of 4^# BF at PZH Steel were discussed.It was concluded that beneficiated burden material,long-term steady operation and regular performance,timely maintenance of furnace and cooling equipment during the post-medium campaign were the important experience for ensure high efficient and long lifetime of blast furnace.

Microstructure of X60 Steel after Heavy-deformation

Zong Yun, Zhao Liping, Ma Yonglin, Wang Baofeng

2006, 27(2): 57-62,68.

Abstract(23) PDF(1)

Abstract:

Single-pass deformation and double-pass hot compression test of X60 steel were tested respectively on the f130 trial two-rollers mill and the Gleeble-1500 thermo-mechanical simulator.The results show the microstructure of deformed sample consists of main polygon ferrite and a little pearlite.There are a lot of dispersed Nb(C,N) precipitates in the ferrite,among the boundaries and on the dislocations.The diameter of the precipitate is about 10 nm or so,which distributed with the form of point-liner or irregular.

Discussing on Rupture Reason of Welded Rail during Transportation

Li Dadong

2006, 27(2): 63-68.

Abstract(26) PDF(1)

Abstract:
Using optical microscope and SEM metallographic techniques to inspect cracking fractures of U75V rail flash welding joint,it was found there was a lot of high-carbon martensite in center areas of rail head and base,the microstructure was normal in other areas.For the rail flash welding process,it is made sure when the surface temperature of joint drop down to 400 ℃,the temperature of center areas of rail head and base is still higher than transformation temperature,so the martensite is changed by forced water cooling after normalizing heat treatment,this change causes the rupture.This rupture could be refrained from altering the water cooling site rearward.

2006 Vol. 27, No. 2