CN100523229C

CN100523229C - LF furnace refining slag used for aluminum-controlled steel

Info

Publication number: CN100523229C
Application number: CNB2007100926823A
Authority: CN
Inventors: 刘清才; 董凌燕; 胡兵; 鹿存房; 杨剑; 温良英; 陈登福
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2007-09-07
Filing date: 2007-09-07
Publication date: 2009-08-05
Anticipated expiration: 2027-09-07
Also published as: CN101121953A

Abstract

The invention discloses a refined slag of LF furnace used in aluminum steel, which is confected by bauxite, lime, dolomite, limestone and wollastonite. The weight percent of the chemical components of the invention is 60.23 to 67.54 CaO, 1.90 to 3.86 SiO2, 10.58 to 17.57 A12O3, 1.84 to 5.57 Mg, 0.09 to 0.23 H2O and 0.036 to 0.042 S and the rest is loss. Through adjusting to the weight of the ingredients of the refined slag, the invention provides the refined slag that can meet requirements of manufacturing aluminum steel in melting performance, foaming performance, viscosity, alkalinity, reduction performance, surface tension and conductivity and can manufacture the refined slag of refined steel liquid with good quality.

Description

LF furnace refining slag used for aluminum-controlled steel

Technical field

The present invention relates to LF furnace refining slag used for aluminum-controlled steel, be specifically related to the refining slag that is used for the LF stove of optimization design, make its metallurgical performance satisfy control aluminum steel smelting requirements.

Background technology

External refining is extensively adopted by the most Steel Plant in the world as the important production process in the modern steelmaking process, along with the development of progress of Production Technology of Clean Steel and continuous casting technology, and the requirement that reduces production costs, furnace outer refining process and equipment are popularized rapidly.Advanced developed countries such as Japan, Europe, the U.S., the external refining ratio reaches more than 90%, and wherein vacuum refinement is than surpassing 50%.External refining is as the important component part of abbreviated system, plays a part very importantly in whole flow process, and the kind of refining furnace is a lot, as LF, ASKEA, SKF etc., in China and Japan based on LF.Progress of science and technology is impelled its very fast development over the past two decades, and external refining has been proposed strict more requirement.

It is with a long history that the LF stove is used the synthetic slag refining techniques, as far back as the thirties in 20th century just the someone propose to use the slag refined molten steel, and obtained certain effect by practice.50～sixties, the synthetic slag refining has obtained using widely and developing in USSR (Union of Soviet Socialist Republics), and synthetic slag was divided into CaO 50～60%, SiO substantially at that time ₂≤ 3.0%, Al ₂O ₃≤ 30～40%, FeO≤0.5%, development mainly comprises following series: CaO-CaF so far ₂Slag system; CaO-Al ₂O ₃Slag system; CaO-Al ₂O ₃-CaF ₂Slag system.

The refining of LF stove is one of gordian technique of present domestic top grade variety steel production, the LF furnace refining slag then be realize the every refining function of LF stove must obligato integral part, an advanced person's LF stove, if there is not corresponding refining slag to match, its refining function may not brought into play.Research and production practice both at home and abroad show, give full play to the effect of LF stove, for different steel grade classifications, preferably have corresponding refining slag system to match, as controlling aluminum steel to Al in the slag ₂O ₃Content requirement is opposition mutually.Along with the rolling shapes quantity that the LF stove is produced is more and more, production scale is increasing, but because existing LF furnace refining slag prescription is single, not only seriously limited LF stove the giving full play to of advantage function in the production of senior control aluminum steel, and the needs, particularly the control aluminum steel kind that the inclusion rank is had relatively high expectations that the control aluminum steel is produced can not have been satisfied.Therefore,, LF stove control aluminum steel refining slag is optimized research, has become and satisfied domestic variety steel production needs, give full play to the effect of LF stove, produce a more urgent task of fine quality steel according to domestic and international research situation and domestic production reality.

Summary of the invention

Single at existing LF furnace refining slag prescription, can not satisfy the deficiency of the needs of control aluminum steel production, the purpose of this invention is to provide the LF furnace refining slag used for aluminum-controlled steel that a kind of melting properties, lathering property, viscosity, basicity, reducing property and surface tension etc. all can satisfy the production requirement of control aluminum steel.

The object of the present invention is achieved like this: LF furnace refining slag used for aluminum-controlled steel is characterized in that: by bauxitic clay, lime, rhombspar, Wingdale and wollastonite preparation, the weight % of its Chemical Composition is CaO 60.23～67.54, SiO ₂1.90～3.86, Al ₂O ₃10.58～17.57, MgO 1.84～5.57, H ₂O 0.09～0.23, and S 0.036～0.042, and all the other are scaling loss (being loss).

Described control aluminum steel with the Chemical Composition weight % of refining slag screening formulation is: CaO 60.28, SiO ₂2.17, Al ₂O ₃16.03 MgO 5.57, H ₂O 0.087, and S 0.040, and loss 15.823.

The present invention regulates and control by the composition to refining slag, and the metallurgical performance of refining slag is improved.Compared to existing technology, its major advantage is:

(1) basicity of slag increases substantially, and has improved the refining effect of LF stove;

(2) increase MgO content in the slag, improved ladle life;

(3) performances such as the fusing point of slag, foam performance, viscosity, basicity, surface tension, sweetening power all are in the scope of LF refining production requirement, and every performance index have reached best cooperation, can satisfy the needs that the control aluminum steel is produced.

Specific embodiment

According to principle of design of the present invention, LF furnace refining slag used for aluminum-containing steel, by bauxitic clay, lime, rhombspar, Wingdale and wollastonite preparation, be combined as a plurality of component prescriptions (the weight % of Chemical Composition) as the condition of table 1 by heterogeneity, be not difficult to calculate required raw-material weight; Again the above-mentioned starting material that take by weighing are in proportion melted evenly the back naturally cooling of coming out of the stove in the hot stove in ore deposit; Broken processing pack is stand-by.

Table 1 control aluminum steel LF refining slag prescription (%)

Annotate: the P of minute quantity, Fe in the slag ₂O ₃, Na ₂O ignores.

Wherein, carry out smelting trial according to prescription shown in the table 2, test-results is shown in table 3～table 6.

Table 2 control aluminum steel refining slag prescription

Table 3 control aluminum steel A ₂M ₃Number slag composition variation/% in the LF refining process

Table 4 control aluminum steel A ₂M ₃Number slag LF refining process molten steel [S] and [Alt] variation/%

Annotate: desulfurization degree η _sBe that the sample [S] that enters the station deducts the percentage ratio of finished product sample [S] divided by the sample that enters the station [S]

Table 5 control aluminum steel A ₂M ₃Number slag LF refining process molten steel gas [N], [H] and complete [O] variation/ppm

Table 6 control aluminum steel A ₂M ₃Be mingled with inspection thing electrolysis after number slag LF refining and XRD detects and rating result

Annotate: the grading standard is ASTM

After the LF slag of test was pressed the operational provisions adding, according to voltage, electric arc sound and field observation, its starting the arc was very fast, the beginning submerged arc time, arc stability, submerged arc were effective all about 2 minutes, and the slag burn-off rate is fast, the top of the slag is active, and the top of the slag is not found conglomeration or caking phenomenon.

LF slag composition when heating up and set off that heat is respectively tested in contrast changes, and during departures, slag still has higher basicity, and sulphur content increases considerably in the slag, illustrates that sweetening effectiveness is fine.

The increasing amount of MgO illustrates that less than 0.3% it is not very serious that the LF slag that designs corrodes cylinder-packing.From control aluminum steel test-results table 5, to A ₂M ₃Slag, after the LF refining in the molten steel [O] be about 50ppm; From the sweetening effectiveness table 4 of control aluminum steel test heat, all about 50%, desulfurization rate is big for desulfurization degree, and after general lower electrode heated up 10 minutes, most of sulphur just can be removed, and final [S] of molten steel is all less than 0.016%.

From table 6, what the nonmetal inclusion total amount of control aluminum steel was the highest after LF handled is 0.007%.From the rating result of inclusion, the rank great majority that are mingled with of test heat are about A2, C1, are mingled with rank and reach the production requirement of control aluminum steel.

Composite score is analyzed, the A of preparation ₂M ₃Number slag satisfies the smelting requirements of control aluminum steel fully, and has obtained the higher refined molten steel of quality.All the other prescriptions can satisfy the smelting requirements that contains aluminum steel equally by the comprehensive test analysis.

1. the present invention by suitably reducing the bauxitic clay consumption, with the content of remaining aluminium in the control steel;

2. suitably increase CaO content in the slag, improve the purifying reaction ability of slag;

3. use rhombspar, magnesite, suitably improve MgO content in the slag, alleviate of the erosion of LF slag, but the MgO too high levels will have influence on the viscosity, melting properties etc. of slag in the slag, therefore will control MgO content in the slag ladle lining;

4. consider that slag absorbs the ability, the particularly absorption that low-melting calcium-aluminate is mingled with of non-metallic inclusion;

5. in the slag with addition of the aluminum shot of appropriate amount, the reducing power with the control slag guarantees that slag has good sweetening power;

6. consider from environmental protection, do additive without fluorochemical, muriate etc.;

7. when submerged arc slag designs, for avoiding the pollution of slag, make whipping agent, but select lower-cost lime carbonate etc. for use without carbon and carbide to molten steel.

Claims

1, LF furnace refining slag used for aluminum-controlled steel is characterized in that: by bauxitic clay, lime, rhombspar, Wingdale and wollastonite preparation, the weight % of its Chemical Composition is: CaO 60.23～67.54, SiO ₂1.90～3.86, Al ₂O ₃10.58～17.57, MgO 1.84～5.57, H ₂O 0.09～0.23, and S 0.036～0.042, and all the other are scaling loss loss.

2, according to the described LF furnace refining slag used for aluminum-controlled steel of claim 1, it is characterized in that: the weight % of Chemical Composition is: CaO60.28, SiO ₂2.17, Al ₂O ₃16.03 MgO 5.57, H ₂O 0.087, and loss 15.823, and S 0.040.