CN103276151A - Method for deoxidizing low-silicon steel by using silicon alloy - Google Patents

Abstract

The invention relates to the technical field of steelmaking, in particular to a method for deoxidizing low-silicon steel by adopting silicon alloy, which is characterized in that in a production process route of converter-RH vacuum refining-slab continuous casting, silicon alloy is respectively added as a deoxidizer in the tapping process and the RH treatment process of a converter, and excess oxygen in ultra-low carbon steel in a converter area and excess oxygen after RH decarburization are removed, and the method comprises the following specific implementation steps of: 1) in the converter process, boiling tapping is needed, and ferrosilicon is added for deoxidation in the tapping process; 2) in the RH treatment process, ferrosilicon is adopted for pre-deoxidation; 3) and after RH decarburization is finished, adding aluminum for final deoxidation, wherein the critical oxygen content can be calculated according to 0.045%, and carrying out component adjustment. Compared with the prior art, the invention has the beneficial effects that: the excess oxygen is removed by silicon alloy (ferrosilicon), the silicon content of the molten steel can be controlled below 0.030 percent, and the Al in the casting blank is reduced under the condition of realizing the same deoxidation effect₂O₃The amount of the impurities is mixed, and the cost of the deoxidized alloy is reduced.

Description

A kind of low-silicon steel adopts the method for silicon alloy deoxidation

Technical field

The present invention relates to steelmaking technical field, relate in particular to the method that a kind of low-silicon steel adopts the silicon alloy deoxidation.

Background technology

At ultra low-carbon steels such as cold-rolled IF steels, silicon steel when converter is produced, for the oxygen level of the dark decarburization that guarantees RH requires and strict phosphorus content requirement, the control of smelting endpoint carbon content is lower, and the tapping back generally needs to adopt the mode of feeding aluminum steel to control between oxygen level to 450 ~ 650ppm at the argon station.

Oxygen in the converter smelting endpoint steel is the main source of oxide inclusion, no matter is to produce ultra low-carbon steel or soft steel generally all adopts aluminium alloy to carry out the adjustment of oxygen level, causes Al in the slag ₂O ₃Higher, the cleanliness factor of steel reduces, thereby causes Al in the strand ₂O ₃Be mingled with relatively and increase, make the cold-rolling deep-punching surface of steel plate occur inclusion defect easily.

Each steel mill mainly adopts the oxygen level that reduces converter smelting endpoint to reduce reductor consumption both at home and abroad at present.Advanced person's such as Nippon Steel, Baosteel steel mill adopts modes such as dephosphorization, desiliconization and desophorization for hot metal or converter duplex smelting to guarantee the accurate control of ultra low-carbon steel phosphorus content, thereby under the situation of converter high-carbon tapping, can access low-phosphorus molten steel, therefore can significantly reduce the oxygen level in the molten steel, generally control below 600ppm, the converter operation needn't be adjusted oxygen level substantially when therefore producing ultra low-carbon steel.

And to adopting the steel mill of traditional technology low phosphorus steel by smelting, have low-carbon (LC) only and just can reach deep dephosphorization, even therefore bottom blowing effect preferably, oxygen level in the terminal point steel is still higher, generally be higher than 700ppm, at enterprise present situation, can only take measures to improve the cleanliness factor of molten steel from deoxidization technique.

Adopt carbon deoxidation, magnesium deoxidation substitution of Al deoxidation technology in some steel mills the application of producing to be arranged.Carbon is a kind of reductor of aluminium deoxidation as an alternative, and deoxidation products is CO gas, can not retain in molten steel, and shortcoming is that reaction is violent, causes big splash easily, and therefore the use in converter is restricted.The magnesium deoxidation is also because reaction is fierce, and deoxidation efficient instability, uses also to be in research and trial period.Because ultra low-carbon steel requires lower silicon (≤0.030%), use the silicon alloy deoxidation to cause molten steel to increase silicon easily, therefore the someone attempts using silicon alloy to be the report of the reductor of converter steelmaking so far.

Summary of the invention

The purpose of this invention is to provide the method that a kind of low-silicon steel adopts the silicon alloy deoxidation, silicon alloy is used for low-silicon steel carries out deoxidation, its deoxidation products is SiO ₂, the removal of floating easily of refining treatment process, purify hot metal, and the silicon alloy cost is lower than aluminium alloy, adopts its deoxidation can reduce reductor consumption.

For achieving the above object, technical scheme of the present invention is:

A kind of low-silicon steel adopts the method for silicon alloy deoxidation, in the production process route of converter-RH vacuum refinement-sheet billet continuous casting, in converter tapping process and RH treating processes, add silicon alloy respectively as reductor, the excess oxygen that excess oxygen in the ultra low-carbon steel of removal converter zone and RH decarburization finish, its specific implementation step is as follows:

1) the converter operation tapping of need seething with excitement, tapping process add ferrosilicon and carry out deoxidation, do not add other reductors, and the ferrosilicon add-on is adjusted according to smelting endpoint molten steel oxygen level [%O], and its add-on calculation formula is as follows:

---formula 1;

2) in the RH treating processes, according to initial oxygen content, guaranteeing the enough situations of decarburization oxygen, also adopt ferrosilicon to carry out pre-deoxidation in treating processes, add-on by formula 1 is calculated;

3) after the RH decarburization finishes, at first add the lime grain by 2 ~ 5kg/t steel, isolate ladle top slag, more than the circulation 3min, add aluminium and carry out final deoxygenation, critical dissolved oxygen content can calculate by 0.045%, and carries out the composition adjustment.

The operation of need skimming behind the described converter tapping prevents that refining from returning silicon, further reduces the finished product silicone content.

The equilibrium equation of above-mentioned silicon deoxygenation is as follows:

According to the balanced reaction equation of silicon deoxidation, separately with the ferrosilicon deoxidation time, its product is pure SiO ₂Or during by its saturated slag,

, when producing the IF steel, when temperature is 1650 ℃ in jar, brings equilibrium equation into and can derive:

$\left[O\right]=\sqrt{\frac{1}{16595.87\×\left[\mathrm{Si}\right]}}$

From formula as can be seen, the square root of dissolves silicon is inversely proportional in equilibrium oxygen in the molten steel and the molten steel, the IF steel requires finished silicon less than 0.030%, bringing formula into can calculate, oxygen level in the molten steel is 0.0448%, illustrates as long as how many ferrosilicon deoxidations no matter the oxygen level in the assurance molten steel greater than 0.0448%, add, silicone content in the molten steel can not be set at 0.05% with critical dissolved oxygen content in the actual production greater than 0.030% yet.

According to converter terminal oxygen level, critical dissolved oxygen content, and supposition ferrosilicon 100% participates in the efficiency calculation deoxidation ferrosilicon amount of deoxidation, can guarantee that the silicone content in the molten steel does not exceed standard in the actual production.

Compared with prior art, the invention has the beneficial effects as follows: adopt silicon alloy (ferrosilicon) to remove excess oxygen, the molten steel silicone content can be controlled in below 0.030%, is realizing reducing Al in the strand under the identical deoxidation effect situation ₂O ₃Be mingled with quantity, reduce the deoxygenated alloy cost simultaneously.

Embodiment

The invention will be further described below in conjunction with specific embodiment:

A kind of low-silicon steel of the present invention adopts the method for silicon alloy deoxidation, be in the production process route of converter-RH vacuum refinement-sheet billet continuous casting, in converter tapping process and RH treating processes, add silicon alloy respectively as reductor, the excess oxygen that excess oxygen in the ultra low-carbon steel of removal converter zone and RH decarburization finish, its specific implementation step is as follows:

1) the converter operation tapping of need seething with excitement, tapping process add ferrosilicon and carry out deoxidation, do not add other reductors, and the ferrosilicon add-on is adjusted according to smelting endpoint molten steel oxygen level [%O], and its add-on calculation formula is as follows:

---formula 1;

2) in the RH treating processes, according to initial oxygen content, guaranteeing the enough situations of decarburization oxygen, also adopt ferrosilicon to carry out pre-deoxidation in treating processes, add-on by formula 1 is calculated;

3) after the RH decarburization finishes, at first add the lime grain by 2 ~ 5kg/t steel, isolate ladle top slag, more than the circulation 3min, add aluminium and carry out final deoxygenation, critical dissolved oxygen content can calculate by 0.045%, and carries out the composition adjustment.

Handle IF steel (St14) with 180 tons of converters and RH-TB refining furnace, finished silicon content requirement≤0.030% is example:

The ferrosilicon add-on that each specific embodiment calculates sees Table 1, and wherein ferrosilicon is siliceous 75%, and recovery rate is 70%.

Table 1:

Adopt ferrosilicon deoxidation and the technological effect contrast of adopting the deoxidation of AlMnFe alloy to see Table 2 among the embodiment 1.

Table 2

Project	The ferro-silicon deoxidization technique	AlMnFe alloy deoxidization technique
			Principal constituent content, %	75	55
The smelting endpoint oxygen level, %	0.085	0.087
			Tap, t	181	178
Convertor deacidification agent add-on, kg	120	105
			Oxygen level in jar, %	0.054	0.048
RH reductor add-on, kg	15	0
			RH granule lime add-on, kg	400	0
Silicone content in the converter jar, %	0.015	0.013
			RH takes out of silicone content, %	0.021	0.022
Finished silicon content, %	0.023	0.022

Claims (2)

1. a low-silicon steel adopts the method for silicon alloy deoxidation, it is characterized in that, in the production process route of converter-RH vacuum refinement-sheet billet continuous casting, in converter tapping process and RH treating processes, add silicon alloy respectively as reductor, the excess oxygen that excess oxygen in the ultra low-carbon steel of removal converter zone and RH decarburization finish, its specific implementation step is as follows:

1) the converter operation tapping of need seething with excitement, tapping process add ferrosilicon and carry out deoxidation, do not add other reductors, and the ferrosilicon add-on is adjusted according to smelting endpoint molten steel oxygen level [%O], and its add-on calculation formula is as follows:

---formula 1;

2) in the RH treating processes, according to initial oxygen content, guaranteeing the enough situations of decarburization oxygen, also adopt ferrosilicon to carry out pre-deoxidation in treating processes, add-on by formula 1 is calculated;

3) after the RH decarburization finishes, at first add the lime grain by 2 ~ 5kg/t steel, isolate ladle top slag, more than the circulation 3min, add aluminium and carry out final deoxygenation, critical dissolved oxygen content can calculate by 0.045%, and carries out the composition adjustment.

2. a kind of low-silicon steel according to claim 1 adopts the method for silicon alloy deoxidation, it is characterized in that, the operation of need skimming behind the described converter tapping prevents that refining from returning silicon, further reduces the finished product silicone content.