钢铁钒钛

New Technology of Producing Titanium Slag by Reducing Ilmenite at Low Temperature

Zhao Pei, Guo Peimin

2005, 26(2): 1-4.

Abstract(30) PDF(1)

Abstract:
A new technology of producing high titanium slag by reducing ilmenite rapidly at low temperature was developed. Solid state ilmenite could be reduced rapidly to iron at around 600℃ when ilmenite and the reductant were ground to around 10 μm, then the titanium slag and iron powder could be obtained by magnetic separation after cooling the reduced hot product. This technology has a series of advantage, such as low reduction temperature, low power consumption and friendly environment. An efficient ball mill was developed, which can grind ilmenite to 2~10 μm with power consumption less than 100 kWh/t ore and promise production rate of 5~10 t/h.

Technical Analysis on Selective Separation and Enrichment of Ti-bearing Blast Furance Slag Based on Phase Diagrams

Guo Peimin, Zhao Pei

2005, 26(2): 5-10.

Abstract(20) PDF(2)

Abstract:
Technical and economical feasibilities on selective separation and enrichment of titanium containing BF slag were conducted. For the route of selective separation and enrichment with calcium oxide, perovskite separates out more sufficiently when slag composition is adjusted to the region CaSiO₃-Ca₃Si₂O₇-CaTiO₃. Gravity separation method is not suitable due to slight difference of phases' densities. Additionally, post-treatment of enrichment slag is very difficult and expensive. For the route of selective separation and enrichment with sodium oxide, it is very difficult for one-step route to produce quite pure enriched slag. Central Iron and Steel Research Institute invented two-step route, which could produce high quality enriched slag, utilize silicon resource and use sodium resource repeatedly. Therefore a high effective and green process comes into being for utilizing titanium slag comprehensively.

Study on Enhanced Leaching of Mechanically Activated Ilmenite

Zhang Xueqing, Li Chun, Liang Bin

2005, 26(2): 11-15.

Abstract(19) PDF(1)

Abstract:
Mechanical activation of rock-type Panzhihua ilmenite was investigated with a tumbling ball mill at 70:1 ratio of ball:ore mass. XRD analysis demonstrated the crystallite size of ilmenite decreased with the increasing of milling time, and remained practically unchanged beyond 4h of milling. The dissolution kinetic experiments at various temperatures showed the apparent activation energy of the ore reduced from 55.7 kJ/mol in initial leaching stage to 23.7 kJ/mol with the extending of milling time. It was found that the apparent Arrhenius energy is closely related to the crystallite size. The digestion of activated ilmenite at a sulfuric acid of 30%~50% concentration was also studied. With increasing of the activation time, the effect of acid concentration on leaching dropped, this indicates that the dissolution of ilmenite under low acid concentration and low leaching temperature is feasible.

Quality Controlling Techniques in Ultra-thin Hot Strip Production Line of Tangshan Iron and Steel Co. Ltd

Feng Yunli, Chen Huahui, Chen Libin

2005, 26(2): 16-19,24.

Abstract(37) PDF(2)

Abstract:
The advanced techniques of ultra-thin hot strip production line at Tanggang were introduced, which include H² mould,dynamic soft reduction,dynamic PC control,semi-endless rolling,ferrite rolling etc. The production survey shows that the stresses in the shell in H² mould are less than in general funnel mould, so there are less cracks in the shell. Optimized roller line device and dynamic soft reduction ensure the internal quality of billet. Semi-endless rolling solves the problem of the strips polling and swing. Dynamic PC control and working bending roll guarantees the stability of the strip's quality. The three-point descaling, especially about the intermediate cooling system between roughing mill and finishing mill, can not only improve the strip surface quality but also support the rolling in ferrite area.

Theoretical Calculation for Equilibrium Solubility and Compositional Coefficient of V(C,N) in V-bearing Microalloyed Steel

Yong Qilong, Liu Zhengdong, Sun Xinjun, Cao Jianchun, Cha Xiaoqin, Zhang Yong

2005, 26(2): 20-24.

Abstract(29) PDF(1)

Abstract:
According to the thermal-mechanical theory and the solubility formulae of VN and VC in austenite, the theoretical calculating methods for the solubility of V, C and N in austenite and the compositional coefficient of V(C,N) were proposed. The calculations for the typical V-bearing steels were carried out, and the calculating results were discussed.

Microstructural Evolution and Precipitation of V(C,N) in a Low-carbon V-bearing Steel

Xu Man, Sun Xinjun, Liu Qingyou, Dong Han, Yong Qilong, Huang Jinliang

2005, 26(2): 25-30.

Abstract(31) PDF(1)

Abstract:
The microstructural evolution and micro-hardness change in a low-carbon vanadium steel ((0.058)%C-0.92%Mn-0.51%V) during isothermal holding after austenite region deformation were investigated with thermo-mechanical test, and the precipitation of V(C,N) was studied through TEM. The experimental results show that the single-phase ferrite matrix microstructure could be obtained by isothermal holding at 650℃, 700℃ and 750℃ after austenite region deformation while the pearlite could be eliminated. During the isothermal holding process, the ferrite nucleated primarily along the anstenite grain boundaries, and then within the austenite grains. Two precipitation modes of V(C,N) were observed in the tested steel:inter-phase precipitation and random precipitation. The inter-phase precipitation of V(C,N) can eliminate the enrichment of carbon in austenite, which is the pre-requisite for the formation of single phase ferrite.

Simulation and Validation on Flow Field in Thin Slab Continuous Casting Mold

Zhang Guifang, Shen Houfa, Wang Lei, Liu Baicheng

2005, 26(2): 31-34,53.

Abstract(34) PDF(1)

Abstract:
By using the finite difference method, the flow field in thin slab continuous casting mold was simulated according to the flow characteristics of liquid steel. The three-dimensional flow field model was set up. The effects of complex nuzzle structure on the flow field in the mold was simulated. The simulated flow field was validated by means of hydraulic model. The results show that the simulated flow field could report the fluid flow in mold with complex nuzzle structure.

Laboratory Study on Producing Titanium White by Acid Dissolved Titanium Slag

Zhang Shuli

2005, 26(2): 35-38,53.

Abstract(15) PDF(1)

Abstract:
According to the difference of acid dissolved titanium slag and ilmenite, the laboratory experiments of preparing titanium white from acid dissolved titanium slag were carried out. The acid dissolved titanium slag came from respectively smelting Panzhihua ilmenite and Yunnan ilmenite. The process parameters of digestion and hydrolysis were defined by the laboratory experiments, and the results showed the process of producing titanium dioxide by acid dissolved titanium slag was feasible. The digestion rate of water quenching slag was higher than that of without water quenching slag under same conditions. The optimal hydrolysis process parameters are:the TiO₂ concentration in hydrolysis process should be more than 200 g/L, the add quantity of nucleator should be 1.3%~1.5%, and the Ti³⁺ concentration in hydrolysis solution should be 1~3 g/L.

Study on Mechano-chemical Effect for Steel Slag

Lu Lei, Wen Jinbao, Yao Qiang

2005, 26(2): 39-43.

Abstract(17) PDF(1)

Abstract:
The steel slag was activated by mechano-chemical method. It was described by a series of analysis and testing means, such as particle size testing, density testing, XRD, HRTEM and DSC-TG. The results showed that the steel slag granule was diminished speedily and the crystal structure changed evidently to amorphism after mechanical finishing, so make the latent activation of steel slag to be activated.

Structural Optimization of BF Cast Steel Cooling Stave Based on Orthogonal Experimental Design Method

Deng Kai, Cheng Huier

2005, 26(2): 44-48.

Abstract(27) PDF(1)

Abstract:
Finite element analysis and orthogonal experimental design methods are two major mathematical tools in engineering analysis, the optimal thermal and stress performance of cooling stave can be accurately achieved by using both of the mathematical methods. The orthogonal experimental design method was employed to determine the group of cooling staves which have different structural parameters. The steady-state highest temperature and thermal stress of cooling staves was numerically simulated and analyzed by engineering software ANSYS. The optimal structural parameters of cooling stave were obtained by using MATLAB multi-objective optimize method. The calculation results showed that the highest temperature of optimized cooling stave was (7.88)% lower than the original one and the highest thermal stress of optimized cooling stave was 6.14% lower than the original one.

Discussion on Economic-type Modification Schemefor CVC Cold-rolling Mill

Zhou Qingtian

2005, 26(2): 49-53.

Abstract(26) PDF(1)

Abstract:
Against the shortcomings of roll shape curve being complication for CVC rolling mill, a set of economic-type mill modification scheme to replace CVC rolling mill with new type OWBC HCW rolling mill was put forward. By means of axial moving of work roll, hydraulic bending-roll and roll shape optimisation, the modified rolling mill could easily control sheet shape, uniform the contact pressure between rolls and reduce the roll consume since elimination the harmful contact zone of work roll and backing roll, which are greater than rolling plate width. The scheme has the advantages of low modification cost and short modification cycle, and very adapts to the rolling mill type modification of medium and small-sized cold-rolling enterprises.

Study on Weatherability of Rutile Nano-TiO₂ in Heavy-duty Coating

Song Qinggong, Yan Jiazhen, Hu Chi, Huang Wanxia

2005, 26(2): 54-57.

Abstract(24) PDF(1)

Abstract:
The weatherability of heavy-duty coating modified by rutile nano-TiO₂ was tested. In the conditions of different nano-TiO₂ ratio and different aging time, the examination results of heavy-duty coating modified by ultra-fines demonstrate that the compound nano-coatings can prevent the resin from oxidizing efficiently, prolong the coating's service age, and so improve the weatherability of coating. The modifying capability of ultra-fines is proportional to its amount in the coating. The absorption spectra of ultra-fine titanium dioxide powders confirme that nano-TiO₂ can absorb 95% of the ultraviolet light in UV spectrum.

In-situ Synthesis VC Particulates to Reinforce Iron Matrix Composite

Cheng Fengjun, Wang Yisan, Lai Li, Shi Jianguo, Wang Jing, Ding Yichao, Yang Tinggui

2005, 26(2): 58-61.

Abstract(24) PDF(1)

Abstract:
The microstructure and the phases in composite were examined by means of SEM and XRD. It was confirmed that graphite had a function to accelerate the decompose of σ-FeV in lower temperature, and the courses were explained. The effects of sintering temperature on the distribution and size of VC were discussed. The carburising reaction of V to form VC take place under solid phase sintering at 850℃, and the in-situ synthesis VC particulate is fine, so the size is smaller than 0.5 μm.

Effect of In-situ Synthesis TiC Particle on Microstructures and Properties of Fe-based Alloy

Wang Ning, Gao Fubao, Li Shijie, Cao Xiaoming

2005, 26(2): 62-66,70.

Abstract(26) PDF(1)

Abstract:
The composites reinforced by TiC particle were prepared through in-situ reaction by means of adding C and Ti element to Fe-Al-B alloys. The phases transformation and the change of microstructure and chemical constitution of each phase were analyzed through X-ray diffraction (XRD) analysis, scanning electronic microscope (SEM) and energy spectrometer. The results showed that the grain of alloy was refined and the corrosion resistance of alloy to molten zinc was improved greatly after in-situ formation TiC in alloy matrix.

Wang Yuansun

2005, 26(2): 67-70.

Abstract(17) PDF(1)

Abstract:

2005 Vol. 26, No. 2