CN102296149A - Fluorine-free high efficiency desulphurization refining slag system for low carbon aluminum killed steel - Google Patents
Fluorine-free high efficiency desulphurization refining slag system for low carbon aluminum killed steel Download PDFInfo
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- CN102296149A CN102296149A CN201110219164XA CN201110219164A CN102296149A CN 102296149 A CN102296149 A CN 102296149A CN 201110219164X A CN201110219164X A CN 201110219164XA CN 201110219164 A CN201110219164 A CN 201110219164A CN 102296149 A CN102296149 A CN 102296149A
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Abstract
The invention discloses a fluorine-free high efficiency desulphurization refining slag system for low carbon aluminum killed steel. Basic slag of the refining slag system is CaO-SiO2-Al2O3, and the components for the basic slag comprises, by weight, 57.41 to 61.8% of CaO, 5 to 10% of SiO2 and 29.5 to 36% of Al; alkalinity R of the refining slag system is 5.8 to 11.5, the Mannesmann index MI of the refining slag system is 0.2 to 0.4, C/A is 1.6 to 2.1, the saturation index of CaO is 0.9 to 1.0, the slag factor of the system is no more than 0.5, and a melting point of the system is no more than 1550 DEG C. According to the invention, slag amount decreases, and production cost is reduced; meanwhile, the content of sulfur in LF refining end-point liquid steel is stably controlled to be less than 20 ppm, a desulfurization rate reaches above 80%, and production cost is effectively reduced.
Description
Technical field
The present invention be more particularly directed to a kind of floride-free high-efficiency desulfurization refining slag system that is used for carbon aluminium-killed steel (LCAK steel), belong to steelmaking technical field.
Background technology
As everyone knows, for most steel grades, the element sulphur in the steel is the detrimental impurity element.S element in the steel causes " hot-short " easily, influences the performance of steel, therefore needs the S element in the steel to be removed, to improve the performance of steel as far as possible.Some high-quality steel grades such as anti-hydrogen induced cracking (HIC) pipe line steel, ocean platform all require to have extremely low sulphur content in the steel with steel and high-end steels for pressure vessel use etc.For anti-hydrogen induced cracking steel, the sulphur content in the steel is high more, and the ability of anti-hydrogen induced cracking is weak more.Therefore, the sulphur content general requirement in the anti-hydrogen induced cracking steel is less than 10ppm, under the stricter situation even require less than 5ppm.
For aluminium killed steel, refining slag system commonly used at present is CaO-SiO
2-Al
2O
3-MgO slag system in order to reduce the fusing point of slag, improves the flowability of slag, needs extra about 5% the CaF that adds usually
2CaF
2Use can produce following adverse influence: 1) slag CaF
2Existence can accelerate the erosion of ladle furnace lining, shorten the work-ing life of ladle; 2) CaF
2The fluorine that at high temperature evaporates is discharged in the atmosphere, causes environmental pollution; 3) fluorine is to the deleterious material of HUMAN HEALTH, CaF
2The use meeting workers'health is produced very adverse influence.Therefore, need reduce as far as possible or forbid CaF
2Use.
Summary of the invention
The objective of the invention is to propose a kind of floride-free high-efficiency desulfurization refining slag system that is used for carbon aluminium-killed steel, it need not to add CaF
2, promptly can be controlled at below the 20ppm the sulphur content in the LF refining endpoint molten steel is stable, thereby overcome in the prior art not enough.
For achieving the above object, the present invention has adopted following technical scheme:
A kind of floride-free high-efficiency desulfurization refining slag system that is used for carbon aluminium-killed steel is characterized in that the basic slag of this refining slag system is CaO-SiO
2-Al
2O
3, the weight percent content of each component is respectively in this basis slag: 57.4～61.8%CaO, 5～10%SiO
2, 29.5～36%Al
2O
3
Further, the basicity R of this refining slag system is 5.8～11.5, and Mannesmann index M I is 0.2～0.4, and C/A is 1.6～2.1, and the saturation index of CaO is 0.9～1.0, the slag factor≤0.5, fusing point≤1550 ℃.
Preferably, this refining slag system comprises component and weight percent thereof are respectively: 51.7～55.6%CaO, 4～10%SiO
2, 26.5～32.3%Al
2O
3, MgO≤8%, (FeO+MnO)≤1.5% and impurity, and in this refining slag system the content of basic slag near 90wt%.
Below technical scheme of the present invention and principle thereof are done more specifically explanation.
To Al killed steel, the desulphurization reaction in the ladle refining process between slag and molten steel is:
(CaO)+2/3[Al]+[S]＝(CaS)+1/3(Al
2O
3) (1)
People such as the little Cang Kang heir of former NKK have defined the slag factor (S.P.=Slag Parameter) and have been:
Can obtain balance sulfur partition ratio L by (2) and (3) formula
SWith slag factor pass be:
By formula (2) as can be seen, reduce Al in the slag
2O
3Activity and the activity that improves CaO in the slag help improving the reaction equilibrium constant of reaction (1), promote the carrying out of desulphurization reaction.Should select CaO activity height, Al for use when therefore, designing the high-efficiency desulfurization slag
2O
3The slag system that activity is low.
By formula (4) as can be seen, reduce the balance sulfur partition ratio that the slag factor helps improving slag.Therefore, the desulfurization slag should be selected the less slag system of the slag factor.
The balance sulfur partition ratio L of slag
SSulfur capacity C with slag
SRelevant, the free list that concerns of the two is shown:
By formula (5) as can be seen, improve slag sulfur capacity, reduce Al in the slag
2O
3Activity and the content that improves sour molten aluminium in the molten steel balance sulfur partition ratio that all helps improving slag.Therefore, the high-efficiency desulfurization slag should be selected the slag system of high sulfur capacity.The sulfur capacity of slag depends primarily on the composition of slag.
The ladle refining desulfurization is mainly finished by the reaction between the slag gold, and the flowability of slag has significant effects to sweetening effectiveness, and flowability is good more, and sweetening effectiveness is good more.The flowability of slag is relevant with temperature, and in general temperature is high more, and the flowability of slag is good more.Under the unalterable prerequisite of technological temperature, improve the flowability of slag, can only realize by the fusing point that reduces slag.Therefore, the high-efficiency desulfurization slag should be selected low-melting slag system.
Elementary heat mechanics and kinetic theory based on above-mentioned desulfurization, the present invention provides a kind of high basicity, low-melting floride-free high-efficiency desulfurization refining slag system for carbon aluminium-killed steel, under the condition that does not increase activity time and technology difficulty, sulphur content in the LF refining endpoint molten steel can be stablized and be controlled at below the 20ppm, desulfurization degree reaches more than 80%, and technology is simple, and production cost is low, and is workable.
Floride-free high-efficiency desulfurization refining slag system of the present invention is:
1. the refining slag system of being invented is low-melting CaO-SiO
2-Al
2O
3-MgO slag system contains inevitable FeO, MnO, P simultaneously in the slag
2O
5And other impurity, do not contain CaF in the slag
2
2. based on the thermodynamic argument of above-mentioned desulfurization, high-efficiency desulfurization slag system provided by the invention has following feature: the basicity R of slag is 5.8～11.5, Mannesmann index M I is 0.2～0.4, C/A is 1.6～2.1 in the slag, the saturation index of CaO is 0.9～1.0 in the slag, the requirement of the dark desulfurization of LF refining can be satisfied in the slag factor≤0.5 on the thermodynamics.Basicity of slag R is defined as: R=(CaO%)/(SiO
2%); Mannesmann index M I is defined as: MI=(CaO%)/[(SiO
2%) (Al
2O
3%)]; C/A=(CaO%)/(Al
2O
3%); The saturation index of CaO is defined as: (CaO%)/(CaO%)
Sat, i.e. the actual CaO content and the ratio of saturated CaO content in the slag.
3. based on the kinetic theory of above-mentioned desulfurization, high-efficiency desulfurization slag system provided by the invention is not adding CaF
2Situation under, the fusing point of slag≤1550 ℃, slag has good flowability under the steel-making temperature, can satisfy the kinetics requirement of desulfurization.
4. the basic slag system of the refining slag system of being invented is CaO-SiO
2-Al
2O
3Slag system, the slag composition that satisfies above-mentioned the 2nd and the 3rd feature is: with CaO, SiO in the slag
2And Al
2O
3Mass percent normalization method after mass percent be: 57.4～61.8%CaO, 5～10%SiO
2, 29.5～36%Al
2O
3
5. the total mass percentage ratio of above-mentioned basic slag system in slag is about 90%, and then Shi Ji slag composition is: 51.7～55.6%CaO, 4～10%SiO
2, 26.5～32.3%Al
2O
3,≤8%MgO ,≤1.5% (FeO+MnO), and other unavoidable impurities.
6. the content of sour molten aluminium is 0.03% in the supposition molten steel, and according to the calculation result of KTH model, the sulfur capacity of above-mentioned slag under 1600 ℃ of temperature is 0.0028～0.0045, and the theoretical sulfur partition ratio of slag is 350～1560.The slag of being invented has higher sulfur capacity and sulfur partition ratio, can satisfy the requirement of the dark desulfurization of LF refining.
Use refining slag provided by the invention to carry out commerical test at husky steel steelworks, obtained excellent desulfurizing effect, the converter terminal sulphur content is being lower than under the prerequisite of 150ppm, and the refining terminal point can be controlled at below the 20ppm sulphur content in the molten steel is stable, and desulfurization degree is up to more than 80%.As a comparison, use traditional fluorine-containing refining slag, be lower than in the converter terminal sulphur content under the prerequisite of 60ppm, the sulphur content in the refining endpoint molten steel can only be reduced to about 25ppm, and desulfurization degree is lower than 60%.Refining slag provided by the invention can also reduce the quantity of slag except improving sweetening effectiveness, the quantity of slag of 15～17kg/t of traditional slag is reduced to 10～12kg/t, reduces the consumption of lime and fluorite, has reduced production cost.
Description of drawings
Fig. 1 is a basic slag system ingredient of the present invention scope graphic representation;
Fig. 2 is the change curve of the embodiment of the invention 1 and embodiment 2 molten steel sulphur content in refining process.
Embodiment
Below in conjunction with an accompanying drawing and a preferred embodiment technical scheme of the present invention is described in detail.
Embodiment 1
Adopt refining slag provided by the invention, on the SPA-H steel grade, experimentize, 180 tons of ladles.
1) bessemerizes terminal point [S]=0.0155%, [O]=990ppm, temperature T=1636 ℃.The strict pushing off the slag of converter tapping adds the 400kg aluminum shot in the tapping process, 610kg lime, and tapping finishes to add the 30kg aluminum shot on the top of the slag.
Disposable adding lime 445kg when 2) LF arrives at a station, the internalization slag finished in about 5 minutes.Change and get LF1 molten steel sample, [S]=0.0054% in the molten steel, [Als]=0.0529% after slag finishes.The ladle bottom blowing gas flow is 800N1/min*2 during the change slag, and heating phase bottom blown gas flow is 350Nl/min*2.After the refining 15 minutes, [S]=0.0024% in the molten steel, [Als]=0.041%.When refining finishes, molten steel [S]=0.001%, [Als]=0.041%, temperature T=1580 ℃.Refining time is 40min, and the desulfurization degree of refining process is 81.5%, and the desulfurization degree that finishes from the refining of tapping then is 93.5% (consulting Fig. 2).Slag composition when the LF refining finishes is 50.5%CaO, 5.9%SiO
2, 31.9%Al
2O
3, 7%MgO, 0.77%T.Fe, 0.2%MnO, 0.7%S.CaO-SiO in the finishing slag
2-Al
2O
3Mass percent after the normalization method: 57.2%CaO, 6.7%SiO
2, 36.1%Al
2O
3, slag composition (is consulted dash area among Fig. 1) in scope of design.The quantity of slag of refining terminal point is about 10kg/t.
The comparative example 2
The fluorine-containing traditional refining slag that adopts certain factory to use experimentizes 180 tons of ladles on the X70 steel grade.
Bessemerize terminal point [S]=0.0058%.The strict pushing off the slag of converter tapping adds aluminum shot and carries out deoxidation in the tapping process.LF arrives at a station, and changes and gets LF1 molten steel sample, [S]=0.0033% in the molten steel after slag finishes.After about 20 minutes of the refining, [S]=0.0021% in the molten steel.When refining finishes, molten steel [S]=0.0025%.Refining time is 45min, and the desulfurization degree of refining process is 24.2%, and the desulfurization degree that finishes from the refining of tapping then is 56.9% (consulting Fig. 2).Slag composition when the LF refining finishes is 55.0%CaO, 9.1%SiO
2, 18.3%Al
2O
3, 4.9%MgO, 5%CaF
2, 0.74%T.Fe, 0.23%MnO, 0.239%S.The quantity of slag of refining terminal point is about 15kg/t.
Claims (3)
1. a floride-free high-efficiency desulfurization refining slag system that is used for carbon aluminium-killed steel is characterized in that the basic slag of this refining slag system is CaO-SiO
2-Al
2O
3, the weight percent content of each component is respectively in this basis slag: 57.4～61.8%CaO, 5～10%SiO
2, 29.5～36%Al
2O
3
2. the floride-free high-efficiency desulfurization refining slag system that is used for carbon aluminium-killed steel according to claim 1, it is characterized in that, the basicity R of this refining slag system is 5.8～11.5, Mannesmann index M I is 0.2～0.4, C/A is 1.6～2.1, the saturation index of CaO is 0.9～1.0, the slag factor≤0.5, fusing point≤1550 ℃.
3. the floride-free high-efficiency desulfurization refining slag system that is used for carbon aluminium-killed steel according to claim 1 and 2 is characterized in that component and weight percent thereof that this refining slag system comprises are respectively: 51.7～55.6%CaO, 4～10%SiO
2, 26.5～32.3%Al
2O
3, MgO≤8%, (FeO+MnO)≤1.5% and impurity, and in this refining slag system the content of basic slag near 90wt%.
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102943150A (en) * | 2012-11-26 | 2013-02-27 | 湖南华菱湘潭钢铁有限公司 | Refined slag control method |
| CN103014241A (en) * | 2012-03-16 | 2013-04-03 | 新疆八一钢铁股份有限公司 | Control method of smelting slag of SPHD steel for LF (Ladle Furnace) furnace |
| CN103882183A (en) * | 2013-12-31 | 2014-06-25 | 马钢(集团)控股有限公司 | Desulfurization refining slag for steelmaking process and addition method thereof |
| CN110106311A (en) * | 2019-05-16 | 2019-08-09 | 中天钢铁集团有限公司 | It is a kind of to reduce the refining slag control technique corroded resistance to material |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103014241A (en) * | 2012-03-16 | 2013-04-03 | 新疆八一钢铁股份有限公司 | Control method of smelting slag of SPHD steel for LF (Ladle Furnace) furnace |
| CN102943150A (en) * | 2012-11-26 | 2013-02-27 | 湖南华菱湘潭钢铁有限公司 | Refined slag control method |
| CN102943150B (en) * | 2012-11-26 | 2015-03-04 | 湖南华菱湘潭钢铁有限公司 | Refined slag control method |
| CN103882183A (en) * | 2013-12-31 | 2014-06-25 | 马钢(集团)控股有限公司 | Desulfurization refining slag for steelmaking process and addition method thereof |
| CN110106311A (en) * | 2019-05-16 | 2019-08-09 | 中天钢铁集团有限公司 | It is a kind of to reduce the refining slag control technique corroded resistance to material |
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Application publication date: 20111228 |