CN102965463B - Efficient dephosphorization process for converter - Google Patents

Abstract

The invention relates to an efficient dephosphorization process for a converter, and belongs to the technical field of converter steelmaking. In the process, end slag of the converter is not poured out and is used for the next dephosphorization in the converter; in order to improve the smelting effect in the stage of dephosphorization in circulation of the converter, the lance position and the oxygen supply in the stage of dephosphorization and a slagging technological means are controlled to realize the efficient dephosphorization by using the end slag of the converter, so that the lime consumption can be reduced, the dephosphorization effect of the converter is improved, and compared with those of the conventional process, the lime consumption can be saved by 40 to 60 percent, the consumption of caustic calcined dolomite is saved by 40 to 46 percent, and the mass fraction of phosphorous in terminal molten steel of the converter is less than 0.006 percent.

Description

A kind of technique of converter high efficiency dephosphorating

Technical field

The invention belongs to converter steeling technology field, a kind of technique of converter high efficiency dephosphorating is particularly provided.

Background technology

For traditional converter process, after every stove is smelted tapping, slag is all poured out.While carrying out next stove smelting, rejoin the various furnace charges such as lime, this operator scheme lime consumption amount is large, cost is high.Thereby, utilize the slag of converter smelting endpoint to continue dephosphorization, be to solve the large best method of traditional converter operation lime consumption amount.

In traditional converter is produced, in order to reach dephosphorization effect, blowing starts backward converter and adds the slag making such as lime, does not substantially contain P in the slag charge adding ₂o ₅.And while adopting converter terminal slag to stay to carry out dephosphorization in stove, in slag, there is the P of 1.5% left and right ₂o ₅, compare with traditional technology, due to the P in molten steel and slag ₂o ₅concentration gradient difference, if adopt the blowing technology identical with traditional technology, dephosphorization speed is slower, is difficult to the dephosphorization effect that reaches identical with traditional technology.

Summary of the invention

The object of the invention is to be applied to for converter terminal slag the situation in dephosphorization stage, a kind of technique of converter high efficiency dephosphorating is provided, realize and utilize converter terminal slag high efficiency dephosphorating, can save lime consumption amount, improve converter dephosphorization effect.

Technical solution of the present invention is:

A kind of technique of converter high efficiency dephosphorating, the two slag melting technique of converter comprises and adds steel scrap, molten iron → bessemerize dephosphorization → slag of falling dephosphorization → bessemerize decarburization → converter tapping simultaneously to stay slag, it is characterized in that: described converter is 210 tons of converters, the oxygen supply of converter dephosphorization stage, residue adjustment red-tape operati step are as follows:

(1) the converter dephosphorization stage adopts low rifle bit manipulation, and top blow oxygen lance rifle position is controlled according to the following formula: H=3.23 × h ^-2+ 1.3, wherein: H is rifle position, m; H is pool depth, m; Top blast oxygen top blown stirring intensity is: 3.0-3.5Nm ³/ min/t steel, dephosphorization duration of blast is controlled at 4-5 minute;

(2) when dephosphorization blowing starts rear 2-3min, add agglomerate, the mass percent of controlling FeO in slag is 9%-15%;

(3) controlling dephosphorization slag dual alkalinity is 1.2-1.8;

(4) pour out the 50%-60% of dephosphorization slag, carry out decarburization stages operating.

The technique of a kind of converter high efficiency dephosphorating of the present invention, owing to bessemerizing P2O5 massfraction in terminal slag generally in 1.5% left and right, tapping temperature is more than 1600 ℃.Aspect technology controlling and process, bessemerize phosphorus content in slag and the molten steel of terminal relatively stable, slag has not substantially possessed dephosphorizing capacity, but dephosphorisation reaction belongs to thermo-negative reaction, if temperature reduces, converter terminal slag can possess dephosphorizing capacity again.Compared with converter terminal, bessemerizing before beginning, the phosphorus content in molten iron is higher, temperature is lower, converter terminal slag, in the time that the dephosphorization stage is used, can have dephosphorization effect again, and therefore converter tapping finishes rear terminal slag and stays in stove and can again bring into play dephosphorization effect.

In view of the thermodynamics feature of converter terminal slag, in order effectively to utilize converter terminal slag dephosphorization, object of the present invention is just to provide the control main points of technological process medium power, thermodynamical coordinate, utilizes converter terminal slag high efficiency dephosphorating to realize.

The key of traditional theory research dephosphorization is: lower bath temperature, higher basicity of slag, high oxidisability etc.In process of production, in order to realize dephosphorization effect, realize the control of phosphorus content from the following aspects control: (1) is controlled slag and contained high FeO content, realizes the oxidation of phosphorus; (2) improve basicity of slag, (3) cold melt.

When adopting converter terminal slag to be applied to the dephosphorization stage when dephosphorization, due to P in slag ₂o ₅content is higher, in order to reach dephosphorization object, should provide good dynamic conditions, strengthens the stirring in molten bath.So, the low rifle of this process using top blow oxygen lance position, high oxygen supply intensity blowing technology, the more conventional low 100～200mm of rifle potential drop in early stage that bessemerizes of dephosphorization stage oxygen lance position, oxygen supply intensity remains on 3.0-3.5Nm ³more than/min/t, to promote [P] that dissolve in molten iron to the transmission of slag/iron interface to melting bath stirring by strengthening top blowing oxygen air-flow, make up in the front slag of blowing and had 1.5% P ₂o ₅the slower problem of mass transfer that the concentration gradient that content causes causes.

Can cause that for low rifle position, the blowing of high oxygen supply speed in slag, FeO content reduces, along with FeO content in slag reduces, the indirect oxidation effect of molten steel weakens, the mobility of slag also can be affected, in order to make up this problem, this technique dephosphorization stage has improved iron ore add-on and has added batch, to guarantee strengthening melting bath stirring simultaneously, in slag, there is enough FeO content (9%-15%), to obtain good thermodynamics dephosphorization effect.

Technique effect of the present invention: adopt the high efficiency dephosphorating technique of these research and development, the dephosphorization stage finishes, dephosphorization rate average out to>=55%, at stayed slag P ₂o ₅in the above situation of content 1.5%, exceed the conventional dephosphorization rate of bessemerizing early stage.Because dephosphorization stage dephosphorization efficiency is high, dephosphorization finishes P in slag ₂o ₅mass percent can reach 2%-2.7%, in decarburization stage endpoint molten steel the massfraction of phosphorus can be removed to≤0.0060%, this absolutely proves that this technique has good dephosphorization effect, can meet most steel grade phosphorus content control requirements except minority ultra-low phosphoretic steel kind (as antiacid pipe line steel).

Embodiment

The present invention is applicable to 210 ton large-scale converters, and main technique comprises following content:

(1) after converter tapping finishes, not deslagging, slag is stayed in tile stove, for next stove blowing stage dephosphorization;

(2) the converter dephosphorization stage adopts low rifle bit manipulation, and top blow oxygen lance rifle position is controlled according to the following formula: H=3.23 × h ^-2+ 1.3, wherein: H is rifle position, m; H is pool depth, m; In actual production process, the factors such as the design variable of rifle position and oxygen rifle, oxygen rifle gaseous tension, converter shape are relevant, according to the eigenwert of the oxygen rifle of different converters and the each correlation parameter of converter, after recurrence, while obtaining adopting common process converter steelmaking, the pass of rifle position and pool depth is: H=3.23 × h ^-2+ 1.5.In this technique, take low rifle bit manipulation, to strengthen the stirring of oxygen rifle top-blown gas to molten bath, on the basis of great many of experiments, while obtaining low rifle position dephosphorization, rifle position should be according to H=3.23 × h ^-2+ 1.3 control, and meanwhile, coordinate top blowing oxygen gas agitating intensity to be: 3.0-3.5Nm ³/ min/t steel, dephosphorization duration of blast is controlled at 4-5 minute;

(3) when dephosphorization blowing starts rear 2-3min, add agglomerate, the mass percent of controlling FeO in slag is 9%-15%; The main purpose that increases the FeO content in slag is: in the time that the mass percent of FeO in slag reaches 9%-15%, the oxidisability of slag is strong, can reach dephosphorization under oxidizing atmosphereLin Fenpeibi requirement;

(4) control of slag dual alkalinity is 1.2-1.8, and the dephosphorization stage, the dynamic conditions of molten steel was fine owing to having adopted low rifle bit manipulation, does not need by adding large quantities of lime, improves basicity and carrys out dephosphorization, has not only saved raw material, has also increased the mobility of slag;

(5) pour out the 50%-60% of dephosphorization slag, carry out decarburization stages operating.

Following table 1 to table 8 has been listed key parameter example when the present invention produces low-phosphorus molten steel on 210 tons of top and bottom combined blown converters.But protection scope of the present invention is not limited in following examples.

Table 1210 ton combined blown converter Top Blown Process key parameter

Heat	Converter rifle position, m	Top blast stirring intensity, Nm 3/min/t	Dephosphorization duration of blast, min
				1	2.4	3.3	4.2
2	2.2	3.3	4.5
				3	2.3	3.5	4.6

A table 2210 ton converter agglomerate adds technology key parameter

Table 3210 ton converter terminal molten steel composition level of control

Table 4210 ton converter smelting slag charge consumes level of control

Claims (1)

1. the technique of a converter high efficiency dephosphorating, the two slag melting technique of converter comprises and adds steel scrap, molten iron → bessemerize dephosphorization → slag of falling dephosphorization → bessemerize decarburization → converter tapping simultaneously to stay slag, it is characterized in that: described converter is 210 tons of converters, the oxygen supply of converter dephosphorization stage, residue adjustment red-tape operati step are as follows:

(1) the converter dephosphorization stage adopts low rifle bit manipulation, and top blow oxygen lance rifle position is controlled according to the following formula: H=3.23 × h ^-2+ 1.3, wherein: H is rifle position, m; H is pool depth, m; Top blast oxygen top blown stirring intensity is: 3.0-3.5Nm ³/ min/t steel, dephosphorization duration of blast is controlled at 4-5 minute;

(2) when dephosphorization blowing starts rear 2-3min, add agglomerate, the mass percent of controlling FeO in slag is 9%-15%;

(3) controlling dephosphorization slag dual alkalinity is 1.2-1.8;

(4) pour out the 50%-60% of dephosphorization slag, carry out decarburization stages operating.