Steelmaking

Technology integration and production practice of high efficiency and low cost clean steel production platform

2012, 28(4): 1-6. doi:

Asbtract ( 453 )

Related Articles | Metrics

Seven technologies are integrated and applied to establish the high efficiency and lowcost constructional long clean steel making platform in No.2 steel making and rolling plant of Tangshan Steel. By application of total molten iron slagging off, high efficient converter blowing and steadily and orderly casting, the quality fraction of hitting rate of carbon, sulphur, and phosphorus comes up to above 93 %and the proportion of effective casting time is higher than96 %. By fully capping the steel ladles and transferring the hot billets with defined weight and splitting rolling the tapping temperature of the hot metal is lowered to 1 635 ℃ and ratio of slab with initial temperature in the reheating furnace up above 800 ℃and ratio of hot charging are as high as 90 % and the yield of the rolled bar steel reaches 97.05 %and the energy consumption in each process is greatly reduced. Very favorable technical and economical efficiencies have been achieved in production of the long steel products for construction purpose by building up the platform.

Water model study and application of BOF lining erosion and slag splashingin refining low carbon steel

2012, 28(4): 7-9,12. doi:

Asbtract ( 433 )

Related Articles | Metrics

The law of lining erosion and proper remaining slag and lance position of slag splash in the bath of BOF slag splashing are studied by way of water model simulation in refining the low carbon steel. Results show that the most serious washing erosion occurs in the portion of the bath and the erosion of the lining turns to be more and more serious with the rise of the lance position and the erosion depth in the upper portion of the bath is weakened and erosion at the bottom of the converter remains intact. In Shougang Qian'an Iron and Steel Co., Ltd., the proper remaining slag amount is 10 t and the slag splashing lance position is 1.35 m. Since optimization the BOF campaign life rises to 8 000 heats from the original 5 500 heats.

Practice of converter slag blocking technology in Meishan Iron & Steel Corporation

2012, 28(4): 10-12. doi:

Asbtract ( 436 )

Related Articles | Metrics

LF refining slag optimization of low carbon cold heading steel

2012, 28(4): 13-15,1. doi:

Asbtract ( 433 )

Related Articles | Metrics

The chemical compositions of ladle slag for cold heading steel are optimized through plantscale experiments. Experimental results show the suitable chemical compositions are w(CaO)=50 %~55 %, w(Al2O3)=30 %~35 %,w(CaF2)=5 %~10 %,w(SiO2)<5 %,w(MgO)<5 %,w(FeO)<1 %. In the process of LF refining the quality fraction of sulfur can be reduced from 389×10-6 to 50×10-6and the quality fraction of total oxygen can be cut down from 54.0×10-6 to 21.1×10-6. The quality fraction of sulfur in inclusions after calcium treatment is less than 1.9 % given that the quality fraction of sulfur in steel is less than 50×10-6. The consumption of slagmaking materials decreases by 6.5kg/t and the cost decreases more than 10 Yuan/t after the optimized ladle slag is applied in mass production of low carbon cold heading steel.

Measures of preventing slag adhesion on insert pipe of RH

2012, 28(4): 16-19. doi:

Asbtract ( 395 )

Related Articles | Metrics

The factors influencing the continuous treatment ability of RH for IF steels, such as slag buildup on the immersion tube, an unreasonable production process and the low life span of refractory are analyzed. The measures such as ladle slag modification, control on the carbon content and oxygen activity of molten steel before RH vacuum treatment, designing a device for cleaning slag from RH insert pipe, and improvement of the refractory materials are proposed. The test results show that with these countermeasures the cleaning time of RH immersion tube is reduced by more than one hour as well.The average continuously treated for RH equipment are increased more than 3.71heats and the highest continuously treated heats are increased from 8 heats to 15 heats and the operating rate of RH equipment is increased to 66.43 % from 22.64 %.

Production practice of controlling silicon content in the cold rolled SPHC steel

2012, 28(4): 20-22,4. doi:

Asbtract ( 468 )

Related Articles | Metrics

The problem of over limited silicon content in SPHC lowcarbon lowsilicon Alkilled steel is discussed on the basis of the studies on kinetics, thermodynamics and practical production. The results show that the key points of silicon content control are using low SiO2 raw materials, ensuring low sulfur molten steel before refining, controlling the quantity of the slag in tapping (no more than 3 kg/t), choosing suitable aluminum content in the converter tapping as well as in each stage of LF treatment, controlling accurately argon blowing rate and controlling the hot steel slag recovery amount within the limit of less than 8 kg/t. In the practical steelmaking in the No.1 Steelmaking Plant of Tangshan Iron & Steel Group Co., Ltd, the qualified rate of SPHC silicon steel comes up to 100 % and thus very desirable results have been achieved.

New development of dynamic soft reduction technology for slab continuous casting and its application in Han Steel

2012, 28(4): 23-26,3. doi:

Asbtract ( 437 )

Related Articles | Metrics

Application of the dynamic soft reduction for slab and its latest development has been introduced. The basic principles of the "pressure feedback" based soft reduction technology and the design features of segment have been described. The soft reduction technology and application of SMS Cyberlink segment and Danieli Optimum segment have been recounted. The principle and application of the "pressure feed back"based dynamic soft reduction system developed independently by Han Steel has been introduced in detail.

Process analysis and practice of clean IF steel production

2012, 28(4): 27-31,6. doi:

Asbtract ( 474 )

Related Articles | Metrics

Taking the processing route of IF steel production, namely "hot metal injection desulphurization→slag blocking in the tapping stage→RH-TB vacuum refining→ medium and heavy plate continuous casting" in the No.4 Work Shop of the General Steelmaking Plant of Angang as the object of studies the present paper discusses in detail 3 key processing points of converter refining, RH vacuum refining and continuous casting and analyzes total oxygen content in liquid steel, temperature control in RH, protection casting and control of consistency in the continuous casting and puts forward measures for improvement in the cleanliness of IF steel. As the results very satisfactory results have been achieved in the aspects of improvement in the cleanliness of the IF steel, reduction of the inclusions in steel and increase in the qualified product rate.

Quality analysis and process optimization for ER70S-6 steel wire rod

2012, 28(4): 32-35. doi:

Asbtract ( 444 )

Related Articles | Metrics

In view of the problems affecting the drawability of ER70S-6 steel wire rod such as high fracture rate, high strength and hardness of the wire rod and serious wearing of the molding tool the present paper analyzes the wire rod, compares the wire rod of the plant with that produced in the other plants and then it is determined that the primary causes to bad quality of the wire rod are high content residual elements in steel, bad quality of slab surface and macro quality as well as rolling defects. The residual element compositions and smelting and rolling processes of ER70S-6 steel are optimized. As the results the tensile strength and hardness of the wire rod are lowered, surface quality raised and drawing property of the rod improved.

Practice and analysis on hot metal desulfurization method by scouring pot with soda ash

2012, 28(4): 36-39. doi:

Asbtract ( 444 )

Related Articles | Metrics

The present paper introduces tests on the hot metal desulfurization by scouring the pot with hot metal using the soda ash as the desulfurization agent. The effects of hot metal temperature, consumption of soda and oxygen blow on the desulphurization are investigated and at the same time the desulphurization effect between Na2CO3 and Na2O are compared with each other. Experiment results show that temperature range of （1 350±20） ℃and soda ash consumption of 15 kg/t are proper processing parameters for hot metal desulphurization. In comparison with Na2O in possession of higher desulphurization ability and lower dephosphorization ability Na2CO3 strikes a good balance between dephosporization ability and desulphurization ability. Although oxygen blow on the surface of the hot metal can prevent against temperature drop of the hot metal, yet the desulphurization ability is prominently reduced because of increase of oxygen potential in the hot metal and slag. Changes of chromium, vanadium and carbon contents in the hot metal in the process of dephosphorization by Na2CO3 are also studied. Results show that change of chromium in the hot metal can hardly be seen and almost all vanadium is oxidized and solved in the slag and w(C) is probably reduced by 0.2 %.

Exploration of carbon dioxide injection as coolantof converter steelmaking technology

2012, 28(4): 40-42,5. doi:

Asbtract ( 448 )

Related Articles | Metrics

The temperature of converter rises quickly at the oxidation period and in this juncture some coolant should be put into the converter to control the temperature of converter at a proper level. In the new technology CO2 is blown into bath of the converter as coolant to replace the solid coolants such as iron ore, iron scale and so on. By theoretical analysis it is known that CO2 as coolant possesses the equal cooling ability in comparison with iron ore and at the same time by use of CO2 the temperature and compositions of the liquid steel in the converter can be easily controlled and the equipments and process for converter steelmaking can be simplified. On the other hand the reactant of CO2 as coolant is CO which can raise the quality of converter gas and reduce the composite energy consumption of the converter steelmaking.

Research on the technology of low phosphorus steel production in the 300 t converter

2012, 28(4): 43-46. doi:

Asbtract ( 423 )

Related Articles | Metrics

Through production data analysis the law of dephosphorization reaction in the process of converter steelmaking in Masteel is investigated and the factors affecting the LP in the 300 t converter are analyzed as well. Results show that LP is greatly affected by carbon content and temperature in the bath, oxidability and basicity of converter slag and bath stirring. Technological measures for refining the low phosphor steel in the large scale converter is drawn up. In the practical application very good results have been achieved. The endpoint slag basicity is raised to 3.9 from original 3.6 and endpoint slag w(T.Fe) is lowered to 2.31% and the endpoint LP is raised to 109 from 87 and end point liquid steel w(P) is redced to 0.006 6 % from 0.009 2 %，thus smooth production of low phosphor steel by 300 t converter is realized.

Research on pollution free hot metal deoxidization method by externally applied electric field

2012, 28(4): 47-50. doi:

Asbtract ( 491 )

Related Articles | Metrics

A new pollution free deoxidization method with applied voltage between metal and slag has been studied. This pollution free deoxidization research has been carried out in a 500 kg multifunction furnace by applying stable DC voltage between CaO-Al2O3-MgO slag and metal. Results show that under the condition of 2~5 V and 10~20 A externally applied DC electric field the quality fraction of the soluble oxygen can be deoxidized effectively to about 40×10-6from initial 800×10-6 in 30 minutes. By application of this method liquid steel can be deeply deoxidized without any contamination and thus a new process route for production of super clean steel can be developed and a very broad prospect of application presents ahead.

Optimization of kinetics condition in converter smelting moderate phosphor bearing hot metal

2012, 28(4): 51-53. doi:

Asbtract ( 476 )

Related Articles | Metrics

In Meishan Steelmaking Plant such a few factors affecting the kinetics conditions of converter as oxygen lance nozzle parameters, bottom blow life depending slag splash process and bottom blow rate parameters are optimized and thus synchronization of top blow and bottom blow is realized in the top-bottom combined blown process and the chemical reaction rate in the bath is promoted. As the results the end point carbon-oxygen equilibrium in the converter are steadily kept in the range of less than 0.003 0 and all indicators for the converter are raised to a better level.

Study on affecting factors of CSP thin slab surface longitudinal crack

2012, 28(4): 54-58. doi:

Asbtract ( 386 )

Related Articles | Metrics

In combination with the CSP producing practice in domestic steel the factors leading to occurrence of slab surface longitudinal cracks are analyzed by statistical data. The statistical results show that the longitudinal cracks can be lessened by reducing the sulphur and nitrogen content, increasing w(Mn)/w(S) in the limit of over 62 and controlling the w(N)·w(AlS) in less than 0.015×10-6and the cracks can also be cut to the lowest level by lowering the fluctuation rate and scope of the drawing speed and controlling the drawing speed in 4 m/min; and since the crack occurrence rate rises with the increase of the heat transfer intensity of the mold it is strongly recommended that mild cooling should be adopted for the heat transfer of the mold; and the properties of mold flux need to be optimized because the thickness of liquid slag layer and the slag consumption are insufficient; and slag entrapment occurs because the lower portion of the flow field of the mold is over strong and the heat carrying over from the upper branch is not sufficient, thus the mold flux is not properly molten. By taking proper counter measures the surface quality of the CSP slab is already greatly improved and the occurrence rate of the cracks is lowered to 0.59 %.

Effects of steel making process scheme on service life of 180 t ladle lining

2012, 28(4): 59-61,7. doi:

Asbtract ( 379 )

Related Articles | Metrics

The present paper analyzes the effects of tapping temperature, feature of the ladle slag, refining rate and refining time, slagging materials and production organization on the lining life of the 180 t ladle of the Hot Rolling plate Co., Ltd of Tianjin Tiantie metallurgical Group. It is of great guiding significance for improvement in the lining life of ladle and reduction of the consumption of the refractory materials.

Application of nanometer materials in the heatinsulating layer of 100 t ladle

2012, 28(4): 62-65. doi:

Asbtract ( 453 )

Related Articles | Metrics

The present paper introduces the process test on using the new type manometer materials as the heat insulating layer at the 100 t ladle of the No.1 Steelmaking and Rolling Mill of Anyang Iron and Steel Group Ltd. Production practice shows that this new ladle heat insulating material is of good temperature holding property and by application of this material the heat emission of ladle can be reduced, the electric consumption lowered, the hot metal temperature in the tundish well maintained and thus very good process and economic efficiencies achieved.

Studies on inhibiting disintegration of AOD stainless steel slag

2012, 28(4): 66-68,7. doi:

Asbtract ( 470 )

Related Articles | Metrics

In light of the serious disintegration and dust flying of the AOD stainless steel slag in the process of cooling by studying the mechanism of disintegration of the slag in cooling and adopting the technique of inhibiting slag disintegration and dust flying with addition of borate into the slag as modifier, namely adding 0.6 %～1.0 % quality fraction of borate modifier in the process of tapping the slag to reduce the viscosity and melting temperature of the stainless steel slag and promote the fusion of fCaO in slag so as to react with SiO2and form the β-C2S. By this way transformation of α′-C2S in the slag into γ-C2S can be prevented and the slag disintegration and dust flying can be effectively inhibited in the process of cooling the AOD stainless steel slag and then the pollution problem can be solved and the environment conditions greatly improved as well.

Progress status of steelmaking and continuouscasting technologies for boron steel

2012, 28(4): 69-73. doi:

Asbtract ( 602 )

Related Articles | Metrics

The classification and application of boron steel are summarized and the progress of research on the boron steel in the process of steelmaking and continuous casting are analyzed. Refinement of austenite grain by adding titanium and boron at Sumitomo Metal and segregation of boron in cast are investigated at Arcelormittal, and new process of boron steel production is investigated by northeastern university. The key control technologies in the process of refining and continuous casting at Sumitomo Metal, Nippon Steel Corp and POSCO and the process of producing boron steel at Baosteel, Wusteel, Pansteel and Ansteel are described. The investigation and trend of development of boron steel are pointed out at last.

Basic research of stainless steel slag property and risk assessmenton resource reclamation

2012, 28(4): 74-77. doi:

Asbtract ( 438 )

Related Articles | Metrics

Basic properties of stainless steel slag out of different production processes including contents, mineralogy and leaching characteristics of elements are researched by chemical analysis，XRD，SEM and solid wasteextraction procedure for leaching toxicity． Results indicate that the main mineral of the stainless steel slag is Ca2SiO4 in which the basicity of EAF slag is the lowest and has a higher metal content．The property of LF slag，AOD slag，LD slag is similar，have high basicity and is easy to be disintegrated into powder．The leaching amount of chromium in EAF slag is far more than the others．Taking security of beneficial reuse into account，such stainless steel slag should be safely disposed because of the leaching risk．

Table of Content