Table of Content

05 June 2012, Volume 28 Issue 3

Previous Issue    Next Issue

生产实践

High efficiency low cost platform for clean steel production practice

2012, 28(3):  1-6,10.  doi:

Asbtract ( 467 )  

Related Articles | Metrics

According to the theory of “metallurgical process engineering”, the present paper described analysis on the function of the high efficiency and low cost production, platform for clean steel and ironsteelHR interface technology of the main processes of Jingtang Iron and Steel Plant. The Plant has been running very smoothly as a whole for two years since being put into commissioning and the purpose of process optimization realized as well. Total DeS, DeSi, DeP ratio steadily maintains on above 80 % and in the meanwhile the material flow rate is also accelerated and the target of 90 heats per day realized, energy loss reduced, tapping temperature lowered markedly and all kinds of material consumption reduced dramatically. In comparison with the normal level the consumption of the auxiliary material is reduced by 30 %.

Thick A633GrD structural steel development practices

2012, 28(3):  7-10.  doi:

Asbtract ( 828 )  

Related Articles | Metrics

To broaden the steel variety of the company and meet customer requirements of the engineering and manufacturing sector, Nanyang Hanye Special Steel Co., Ltd. has successfully developed and produced the 150 mm thick A633GrD lowalloy high strength structural steel in batch by way of ingot mold casting, 3 800 mm mill rolling and normalizing (heat treatment) process. The yield strength of the newly developed steel is controlled within the limit of 340～370 MPa, tensile strength in 495～520 MPa, elongation rate in 25 % to 35 % and impact energy in the 122～167 J, therefore all indicators are in conformity with the requirements of A633GrD development.

Production of low sulfur steel by hot metal desulfurization with compound injection

2012, 28(3):  11-15.  doi:

Asbtract ( 411 )  

Related Articles | Metrics

In view of the characteristics of the compound injection desulfurization technology the origin of the sulfur pickup during the tapping of converter is analyzed and finally determined that the primary cause to the phenomenon is carryover of sulfur into the molten steel from the hot metal, desulfurization slag and other raw materials. By means of implementation of a series technological measures such as strictly controlling the sulfur content of the raw materials, raising the grade of the starting materials, properly selecting the spray rate, rationally controlling the ratio of desulfurizers, the pressure of the injection pot and pressure of the auxiliary blowing gas, appropriately readjusting immersion depth of spraying gun into the hot metal, optimizing the deslagging process, adjusting the angle of the deslagging board as well as the installation height of the porous fire bricks, standardizing the technological conditions of desulfurization and converter refining and initiating an overall process control the phenomenon of sulfur pickup can be effectively controlled and the target of tapping low sulfur steel can be realized. In the end the quality fraction of sulfur pickup of the converter is controlled in the range of 25×10^-6, and the tapping sulfur content is steadily controlled in less than 40×10^-6.

Numerical simulation and application of the oxygen lance jet of 100 t converter

2012, 28(3):  16-18.  doi:

Asbtract ( 388 )  

Related Articles | Metrics

A threephase and threedimensional mathematical model has been established using a CFD software and then numerical simulation of the 100 t converter in Shougang Shuicheng Iron & Steel Group Co., Ltd. carried out with the model. The simulation results show that because of the impact of new lance jet both the impact area and penetration depth in the bath are increased. And the new lance in possession of good mixed ability can promote the mass transfer and heat transfer of liquid steel and accelerate smelting rhythm. To test the simulation results the new lance is used to the BOF steelmaking of Shougang Shuicheng Iron & Steel Group Co., Ltd. Results show the lance is of stronger stirring ability and faster decarburization rate, and moreover the oxygen consumption per ton steel, oxygen supply time and oxygen supply intensity can meet the production demand of steelmaking.

Production practices of increasing service life of ladle in CSP continuous casting of WISCO

2012, 28(3):  19-22,3.  doi:

Asbtract ( 376 )  

Related Articles | Metrics

In light of problem of ladle bottom spalling and the serious ladle wall erosion occurring in the process of the ladle turnover period in the CSP continuous casting a series of counter measures have been implemented such as optimization of the refractory configuration of the ladle bottom, improvement in the bath brick work and optimization of the pouring method of the ladle bottom. As the results the service life of the ladle has been continuously prolonged from the less than 90 heats in the initial stage of commissioning of the ladle to the 140 heats at the present time. The target of reduction of production cost and improvement in the efficiency has been realized and the safeties of ladle turn over ensured as well.

Inclusion composition change of Q345 steel in secondary refining

2012, 28(3):  23-26.  doi:

Asbtract ( 430 )  

Related Articles | Metrics

Industrial scale experiments are carried out to investigate chemical composition change of the inclusions of Q345 steel during ladle furnace refining and RH degassing. The experimental results show that most of alumina inclusions are transformed into CaO-Al₂O₃-MgO inclusions with lower melting point through the reaction between liquid steel and ladle slag with high basicity and low FeO content. The effect of calcium addition on the chemical compositions of the inclusions is also investigated after RH degassing. The results show that the average chemical compositions of inclusions in steel will remain at the low melting point zone（≤1 500 ℃）after ladle refining and RH treatment and addition calcium 0.12 kg in every tonnage steel under the condition that the slag composition is controlled at w(CaO)＝50 %～55 %，w(CaF₂)＝5 %～8 %，w(Al₂O₃)＝25 %～30 %，w(SiO₂)＝5 %～8 %，w(MgO)＝5 %～10 %，w(FeO) < 1 %.

Analysis on effect of RHMFB processing on inclusion

2012, 28(3):  27-32.  doi:

Asbtract ( 407 )  

Related Articles | Metrics

The experiments are carried out on refining the ultralow carbon IF steel by RHMFB processing route in the new Converter Refining Steelmaking Plant of Lianyuan Iron & Steel Group Corporation and the effects of oxygen and carbon contents as well as temperature in steel, time of vacuum cycle and chemical compositions of the refining flux on the quantity and size distribution of inclusions in steel are analyzed and studied. The technological parameters of RH refining are optimized as well. As the results the ultralow carbon IF steel produced in the plant conforms to the technological specifications of w(C)≤30×10^-6,w(N)≤30×10^-6,w(O)≤20×10^-6 and the chemical compositions and quality of the steel are consistent.

Study and application of nozzle clogging control technology during billet continuous casting

2012, 28(3):  33-36.  doi:

Asbtract ( 832 )  

Related Articles | Metrics

The obstructive materials clogging the nozzle are identified primarily to be Al₂O₃ and CaAl₁₂O₁₉. Hot metal oxidation, calcium treatment technology, refining white slag and casting are also studied. The average single tundish casting number increases to 9 heats by taking a series of technological measures such as decrease of hot metal oxidizability （＜580×10^-6）, control on the amount of slag tapping from converter to ladle (<80 mm), implementation of slagwash and modification in tapping, increase in aluminum and ferrous deoxidizer consumption in converter refining, reduction of amount of acidsoluble aluminum loss, implementation of “soft bubbling” refining (slightly fluctuation of the slag surface) in the end of refining, acceleration of feeding speed of Si-Ca cladded wire to 40~42 m/s and increase of feeding amount of the wire to 0.44~0.55 kg/t and strictly execution of protection casting control technology.

Analysis and control on mold level fluctuation

2012, 28(3):  37-41.  doi:

Asbtract ( 395 )  

Related Articles | Metrics

The origin of mold level fluctuation is studied by water model experiments in the Hanbao Steelmaking Plant. Results show that the fluctuation of the mold level tends to grow up with increase of the drawing speed, argon blow rate and slab section whereas the extent of the mold level fluctuation goes down with increase of submerging depth and outlet angle of the submerged nozzle. Therefore the fluctuation of the mold level can be lessened and the quality of CC slab improved accordingly only if proper drawing speed is chosen, consistent casting speed is well kept, shape of the submerged nozzle and the submerging depth of the nozzle are optimized, the argon blow rate is properly maintained and the operating instruction is strictly implemented. Since implementation of the above mentioned optimization measures the fluctuation of the mold level gradually turns back to the limit of less than 3 mm and the defect ratio of the hot rolled strip such as bulgy edge and inclusion defect steps down month after month. The defect ratio is already controlled within the limit of less than 0.1 % in April 2011 from 0.41 % in November 2010.

Practices of improving the quality of extra thick steel plate

2012, 28(3):  42-44.  doi:

Asbtract ( 335 )  

Related Articles | Metrics

The cleanliness of the liquid steel and quality of the slab are effectively raised by way of optimization of the LF refining slag series, the argon bubbling schedule of VD and LF furnace and the processing parameters of continuous casting. Since optimization the aim of w(P)≤0.015 %，w(S)≤0.003 %，w(O)≤4×10^-6，w(H)≤1.3×10^-6，w(N)≤40×10^-6 in the hot metal has already been achieved. Both the central segregation and porosity of the slab arrive at grade 1.0of category C and the average qualified ratio of ultrasonic flaw detection of the steel plate rises by 3.15 %and the highest qualified ratio of ultrasonic flaw detection attains 99.51 %.

试验研究

Research on the effects of preheating on thermal behavior of the ladle

2012, 28(3):  45-49.  doi:

Asbtract ( 792 )  

Related Articles | Metrics

In light of the practical situation of Steelmaking Plant H the temperature field of the new ladle is studied by the finite element analysis method. Then the full process from preheating to the turnover of the ladle is numerically simulated using the numerical simulation software ANSYS and the effects of ladle preheating on the thermal conditions and hot metal temperature are emphatically analyzed and verified as well. Results show that although as a whole the ladle turns to become a hot ladle and the temperature of the ladle wall tends to be in a state of heat saturation after being preheated for 25 hours, yet there is still room for the ladle bottom to store certain heat (temperature rise) and the temperature of the hot metal in the ladle probably drops by about 10 ℃ after the turnover of the ladle. However after the ladle is preheated for 55 hours the ladle tends to be heat saturated and the temperature drop of the hot metal in the ladle is less than 1 ℃ after the turnover of the ladle. Therefore the ideal preheating time for the ladle is 55 hours and it can be used as the reference for the similar steelmaking plant in establishing a proper baking regime and steel tapping temperature schedule.

GA-PSO-BP neural network based prediction model for LF end point temperature

2012, 28(3):  50-52.  doi:

Asbtract ( 752 )  

Related Articles | Metrics

In view of the characteristics of the LF (ladle furnace) metallurgical process and the disadvantages of traditional hot metal temperature prediction methods a new BP neural network model for prediction of the LF end point temperature is developed. The genetic algorithm（GA）and particle swarm optimization（PSO）are properly combined to optimize the weight and bias value and improve the prediction model precision of BP neural network. The hybrid model can not only overcome the difficulties of the traditional prediction model of its prediction inaccuracy, but also compensate the insufficiency of the traditional BP algorithm. The hybrid algorithm combines the advantages of both and improves the convergence performance of the prediction model. Simulation results show that by use of this model not only the prediction precision and speed can be improved but also heats of the refined hot metal with prediction deviation of less than 5 ℃ reaches 88 %.

Prediction of molten steel temperature in BOF→LF→CC route

2012, 28(3):  53-56,6.  doi:

Asbtract ( 394 )  

Related Articles | Metrics

In view of the technological characteristics of CC process flow and production data in steelmaking BP neural network based model is established for prediction of the liquid steel in the BOF→LF→CC route. Variables and data of the model are sieved out by correlation analysis and fivenumber summary method respectively and the BP neural network is improved by LM algorithm and the model is rehearsed and tested by the production data. A programme for the liquid steel temperature prediction model is developed by Java and the programme is already in used in a specific steelmaking plant. Results show that the hit rate of molten steel temperature prediction in each zone by the model can meet actual requirements of production basically.

Study on the inclusion removal by gas curtain in slab continuous casting tundish

2012, 28(3):  57-60,6.  doi:

Asbtract ( 428 )  

Related Articles | Metrics

The relationships among the inclusion upward float rate, diameter of argon bubbles and diameter and density of inclusion particles with or without establishment of the gas curtain in the tundish in the process of argon bubbling are analyzed. The results show that the influence of the diameter of the gas bubbles on the upward float rate of the inclusions is apparent, whereas the effect of density of the inclusions on the float rate is of little significance. Results of industrial experiments show that tundish bottom gas bubbling is very useful for large size inclusion removal in the liquid steel, but it’s not so apparent for removal of the medium and small size inclusions.

Study on flowability and heat transfer characteristics of eight-strand tundish

2012, 28(3):  61-65.  doi:

Asbtract ( 798 )  

Related Articles | Metrics

A block type eight strand tundish is designed and built in a specific steelmaking plant. The experimental plan for the flow control device of the tundish including the flow field, temperature field and flowability has been studied by means of orthogonal experiment method and numerical simulation and thereupon a set of new flow control device is designed and built. Experimental results show that the flow field of the liquid steel in the tundish without any flow control device installed is not so desirable and the difference of the flowability for each strand is quite great and the difference of temperature between each strand also very apparent. Since installation of the optimized flow control device the flow pattern of each strand tends to be consistent and the temperature difference between each strand is clearly reduced and the removal rate of the inclusions is also greatly improved. The practical metallurgical effect is quite conspicuous and the maximum temperature difference between each strand in production of steel Q235 is merely 4 ℃ and the continuously casting time reaches 26 h and in the period the flow control device is in a very good conditions.

Optimization of viscosity and crystallization temperature forhighstrength lowalloy steel mold flux

2012, 28(3):  66-69.  doi:

Asbtract ( 348 )  

Related Articles | Metrics

The viscosity and crystallization temperature of mold flux have a greater impact on the quality of continuous casting billet. The viscosity and crystallization temperature of the three different mold fluxes of Masteel are studied by rotating cylinder method, viscositytemperature curve method and SEM. The results show that viscosity and crystallization temperature of Masteel’s mould fluxes used in production of steel Q420B are lowest among the three mold fluxes: η=0.298 Pa·s，T=1 175 ℃. To reduce the slag entrapment and improve the quality of steel, the viscosity of the flux is increased to about 0.35 Pa·s and the basicity is also appropriately adjusted to increase the crystallization temperature. Since optimization the slag entrapment and crack have been properly controlled in production.

Study on heat flow distribution on the thin slab continuous casting mold

2012, 28(3):  70-73.  doi:

Asbtract ( 418 )  

Related Articles | Metrics

The temperature distribution on the CSP mould copper plate of Wuhan Iron & Steel Corporation is measured with the mold temperature monitoring software. On the basis of the onsite measured temperature data by the thermal couple and the cooling parameters of the continuous caster the heat flux values of different drawing speed are calculated in casting steel SPHC with different sections and then a twodimension mold heat flux distribution model is built. Results show that heat flux and temperature distribution in the width direction of the CSP mould are quite inhomogeneous, showing an obvious double peak pattern since they are affected by jet flow of submerged entry nozzle. Under the similar working conditions the distribution of copper plate temperature is similar to that of heat flux in the width direction. The nearer to the meniscus the more serious the fluctuation of the heat flux density and temperature becomes. The maximum heat flux density at the meniscus reaches approximately 4.6 MW/m².

综 述

Overview and trend of steel slag recycling and reuse

2012, 28(3):  74-77.  doi:

Asbtract ( 914 )  

Related Articles | Metrics

The present paper systemically discusses the advantages and disadvantages of methods tackling the steel slag and then analyzes and compares the current status of research on the steel slag recycling and reutilization at home and abroad, namely in China the research work starts from preparation of the cement and ceramic material out of the slag at the initial stage to the recycling and reclamation of certain rare metal and sequestration of the carbon dioxide in the later stage, whereas extensive and thorough studies on the feasibility of extraction and sequestration of the carbon dioxide out of the slag has been conducted theoretically and practically abroad. It can be predicted that it would be the practical new trend for controlling the gas emission with steel slag in near future.