CN102876851B - Method for improving calcium yield of RH vacuum furnace - Google Patents
Method for improving calcium yield of RH vacuum furnace Download PDFInfo
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- CN102876851B CN102876851B CN201210377188.2A CN201210377188A CN102876851B CN 102876851 B CN102876851 B CN 102876851B CN 201210377188 A CN201210377188 A CN 201210377188A CN 102876851 B CN102876851 B CN 102876851B
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Abstract
A method for improving the calcium yield of an RH vacuum furnace includes the steps: molten iron treatment; converter smelting; refining in an LF furnace; RH vacuum treatment; and tapping and casting to form a billet. By the method, the calcium yield of the RH vacuum furnace is stably improved from 3-5% to 8-12%, and the number of continuous molten iron casting and rolling furnaces of the RH vacuum furnace is increased from 2.7 to 9, so that consumption of raw materials is reduced, the operating rate of a unit is increased, and production cost is reduced. The method is wide in applicable range, namely, the method can be used for all steel types of continuous casting and rolling RH production for sheet billets.
Description
Technical field
The present invention relates to the smelting process of molten steel, refer to particularly the method for calcium recovery rate in a kind of RH of raising vacuum oven.
Background technology
The relation of casting properties, tissue, characteristic and the non-metallic inclusion of continuous casting steel is very close.Therefore, in steelmaking process, not only to control the chemical composition of molten steel well, but also will control the non-metallic inclusion in steel, with so that guarantee the purity of molten steel.In order to improve steel performance, as used " calcium processing " to reduce the formation of manganese sulfide inclusion in steel, thereby the sulfide inclusion of avoiding forming strip improves the anisotropy of steel; Process by calcium " hot-short " etc. that molten steel carried out desulfurization and reduced steel, conventionally all use the method that molten steel is carried out to " calcium processing " to change slag inclusion thing form in steel.
Aluminium is widely adopted in steelmaking process as strong reductor, but with form a large amount of aluminium sesquioxides after aluminium deoxidation in steel.Because aluminium sesquioxide is difficult to remove totally, thereby be easy to stick to the interruption that causes nozzle clogging casting cycle on the wall of the mouth of a river in the time of casting from steel.In order to address this problem, conventional method is that molten steel is carried out to calcium processing, by adding certain calcium in steel, dystectic aluminium sesquioxide is combined with calcium oxide and forms the calcium aluminate of low melting point, thereby greatly improve the casting properties of molten steel.
Calcium metallurgical technology has been applied very generally in modern steelmaking process in a word, but improper if calcium processing is controlled, and not only can not reach the metallurgical effect of expection, can worsen on the contrary the casting properties of steel.If calcium treatment technology was controlled not at that time, not only nozzle clogging is brought to impact, and covering slag performance to melting in continuous cast mold and the behavior of solidifying of molten steel also can make a big impact, the CaO pulvis of using as desulfurization is subject to the time of tide, if being sprayed into a large amount of CaO, molten steel carries out desulfurization processing, can cause that in steel, [H] content significantly raises, if add rhythm of production anxiety, after calcium is processed, later stage stirs and calm deficiency of time, inclusion floating is insufficient, after continuous casting is opened and is watered, covering slag performance can sharply worsen, cannot keep its lubricated and heat transmission function normally, the now serious variation of the heat-transfer effect in crystallizer, can not reach the metallurgical effect of expection, produce a series of product quality problems and bleed-out accident even.
Because the density of calcium is little compared with solubleness low, in steel, the vapour pressure of calcium is large, boiling point is low, high volatile volatile and chemically reactive, make the calcium amount that adds in steel large, but recovery rate is but very low, and affected by the factors such as the quantity of slag in deoxidation of molten steel situation, ladle, in the large production of reality, to stablize the calcium contents difficulty of controlling in steel larger.At present industry is large produce in the conventional Xiang Gangzhong method that adds calcium have two kinds: the one, dust; The 2nd, feed silk.The pulvis preparation of the technology of dusting, carry, moistureproof conditional request is higher, facility investment is larger, cost is high, and dusting, it is large easily to cause increasing in steel hydrogen, nitrogen pick-up, temperature drop, not only can reach the effect of dusting and greatly overcome the shortcoming of dusting and feed silk, therefore " calcium processing " hello silk technology has obtained rapid popularization in the eighties.
In continuous casting and rolling technique of sheet bar, because a lot of steel grades are to S, P, O, N, H, C element requires very low, need to pass through the processing of RH vacuum oven, for " slag inclusion thing sex change in steel " and " desulfurization " and " solving the castability of continuous caster " problem, all need in processing, RH vacuum oven carry out " calcium processing ", but in RH Zinc Vacuum Furnace Slag, FeO+MnO is unstable, usually causing RH vacuum oven calcium to process recovery rate is only 3-5% and unstable, the non-constant of calcium treatment effect, make smelting cost high, steel quality is poor, cause continuous casting of molten steel that RH in continuous casting and rolling technique of sheet bar produces to connect to water stove number often very low, usually only have 2～3 stoves.The major cause that produces this phenomenon is that after RH vacuum oven is processed, slag fluidity is bad, reacts insufficient between slag, and the oxygen in oxygen and molten steel in slag is in nonequilibrium state, in slag FeO+MnO in utmost point unsteady state, time low when high.And the calcium line amount of squeezing in steel by production engineering specifications in calcium treating processes is certain, therefore, in the time that FeO+MnO content is high, it is on the low side that calcium is processed recovery rate.In the time that FeO+MnO content is low, it is higher that calcium is processed recovery rate.And the molten aluminium content of acid in molten steel is high, in cast, cotton-shapedly be mixed in the enrichment of mouth of a river place and cause nozzle clogging, because thinslab casting slab thickness is 50mm thick (it is thick that conventional continuous caster slab thickness is generally 200mm) only, therefore in its continuous casting water-coating port than little many of water-coating port in conventional continuous casting, purity and castability to molten steel are had relatively high expectations, and require higher to RH vacuum oven calcium treatment effect.Calcium process recovery rate on the low side or higher all can not make dystectic aluminium sesquioxide be combined with calcium oxide formation low melting point calcium aluminate, finally cause water-coating port or ladle nozzle dross (note: thinslab casting is generally middle water-coating port dross in continuous casting, conventional continuous caster is generally ladle nozzle dross, solve under normal circumstances many than conventional continuous caster nozzle clogging problem hard of thinslab casting nozzle clogging, because of in thinslab casting in water-coating port dross, its ladle nozzle does not have dross), it is unstable that RH vacuum oven calcium is processed recovery rate, and the low restricted link that has become sheet billet continuous casting and rolling production line production RH steel.
For solution calcium processing recovery rate is low and instability problem, there is the special used device of use that calcium alloy rod is inserted into ladle bottom, improve the recovery rate of calcium, the deficiency of its existence is that not only cost is too high, and in solution slag, FeO+MnO problem is very micro-;
For stove number waters in the company of improving RH steel continuous caster, some factory has adopted " processing of converter+LF+RH+ calcium " and " processing of converter+RH+LF+calcium ", " processing of converter+LF+RH+ LF+ calcium " technique, have certain effect though stove number is watered in the company of continuous caster, before finally all can't resolve RH steel calcium and processing, oxidisability problem and RH steel calcium are processed the low and instability problem of recovery rate in slag.
Summary of the invention
The object of the invention is in order to solve CSP RH vacuum oven calcium processing recovery rate is only 3-5% and unstable, and improve continuous casting and even water the problem that stove number is low, provide a kind of RH vacuum oven calcium to process recovery rate and be at least 8% and stable, connect the method for watering calcium recovery rate in the raising RH vacuum oven that stove number at least reaches 9 stoves.
Realize the measure of above-mentioned purpose:
Improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time is not less than 1 minute, and adopts positive pressure operation, and pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 3～10 minutes;
After c, change slag finish, add lime according to 3.3～5.0 kgs/tonne of steel, add refining slag according to 0.67～2.0 kg/tonne of steel, and according to 6.0～7.0 kgs/tonne of steel control quantity of slag, the oxygen level in control molten steel is at 350～450PPm;
4) carry out RH vacuum-treat, and add lime according to 2.0～3.0 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.1～0.5 kg/tonne of steel at slag surface uniform, then according to 4.0～6.0 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity and be not less than 5 meter per seconds; Control FeO+MnO≤5.5 (wt%) in slag; Carry out conventional soft blow;
6) tap and pour into base.
It is characterized in that: in the time that slag produces crust phenomenon, adopt and add iron calcium line to carry out broken shell, iron calcium line adds according to 0.70～1.4 meter of/ton of steel control.
The present invention compared with prior art, RH vacuum oven calcium is processed recovery rate by the stable 8-12% that brings up to of 3-5%, RH vacuum oven continuous casting of molten steel tandem rolling stove number is brought up at least 9 stoves by 2.7 stoves, thereby reduce the usage quantity of this raw material, improve unit operation rate, reduce production costs, and the present invention is applied widely, can be used for all steel grades that CSP RH produces.
Embodiment
Below the present invention is described in detail:
Embodiment 1
Improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time 1.5 minutes, and adopt positive pressure operation, pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 3 minutes;
After c, change slag finish, add lime according to 3.3 kgs/tonne of steel, add refining slag according to 0.67 kg/tonne of steel, and according to 6.5 kgs/tonne of steel control quantity of slag, the oxygen level in control molten steel is at 380PPm;
4) carry out RH vacuum-treat, and add lime according to 2.0 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.4 kg/tonne of steel at slag surface uniform, then according to 4.0 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity at 5 meter per seconds; In slag, FeO+MnO is 5.0 (wt%); Carry out conventional soft blow;
6) tap and pour into base.
After testing, in RH vacuum oven, calcium recovery rate is 8.3% to the present embodiment, and even watering stove number is 9 stoves.
Embodiment 2
Improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time 2 minutes, and adopt positive pressure operation, pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 4.5 minutes;
After c, change slag finish, add lime according to 3.8 kgs/tonne of steel, add refining slag according to 0.95 kg/tonne of steel, and according to 6.0 kgs/tonne of steel control quantity of slag, the oxygen level in control molten steel is at 390PPm;
4) carry out RH vacuum-treat, and add lime according to 2.3 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.45 kg/tonne of steel at slag surface uniform, then according to 5.0 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity at 5.5 meter per seconds; In slag, FeO+MnO is 4.5 (wt%); Carry out conventional soft blow;
6) tap and pour into base.
After testing, in RH vacuum oven, calcium recovery rate is 8.8% to the present embodiment, and even watering stove number is 10 stoves.
Embodiment 3
Improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time 2.5 minutes, and adopt positive pressure operation, pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 6 minutes;
After c, change slag finish, add lime according to 4.2 kgs/tonne of steel, add refining slags according to 1.35 kgs/tonne of steel, and according to 7.0 kgs/tonne of steel control quantity of slag, the oxygen level in control molten steel is at 400PPm;
4) carry out RH vacuum-treat, and add lime according to 2.6 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.2 kg/tonne of steel at slag surface uniform, then according to 5.5 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity at 6.5 meter per seconds; In slag, FeO+MnO is 4.8 (wt%); Carry out conventional soft blow;
6) tap and pour into base.
After testing, in RH vacuum oven, calcium recovery rate is 9.5% to the present embodiment, and even watering stove number is 11 stoves.
Embodiment 4
Improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time 3 minutes, and adopt positive pressure operation, pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 8 minutes;
After c, change slag finish, add lime according to 4.6 kgs/tonne of steel, add refining slags according to 1.6 kgs/tonne of steel, and according to 6.6 kgs/tonne of steel control quantity of slag, the oxygen level in control molten steel is at 420PPm;
4) carry out RH vacuum-treat, and add lime according to 2.8 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.3 kg/tonne of steel at slag surface uniform, then according to 6 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity at 6.8 meter per seconds; In slag, FeO+MnO is 4.3 (wt%); Carry out conventional soft blow;
6) tap and pour into base.
After testing, in RH vacuum oven, calcium recovery rate is 10% to the present embodiment, and even watering stove number is 11 stoves.
Embodiment 5
Improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time 2.5 minutes, and adopt positive pressure operation, pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 10 minutes;
After c, change slag finish, add lime according to 5 kgs/tonne of steel, add refining slags according to 2 kgs/tonne of steel, and according to 7 kgs/tonne of steel control quantity of slag, the oxygen level in control molten steel is at 410PPm;
4) carry out RH vacuum-treat, and add lime according to 3 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.4 kg/tonne of steel at slag surface uniform, then according to 5.7 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity at 6 meter per seconds; In slag, FeO+MnO is 4.6 (wt%); Carry out conventional soft blow;
6) tap and pour into base.
After testing, in RH vacuum oven, calcium recovery rate is 11.5% to the present embodiment, and even watering stove number is 12 stoves.
If in the time that slag produces crust phenomenon, can add iron calcium line to carry out broken shell according to 0.70～1.4 meter of/ton of steel.
Above-described embodiment only exemplifies for the best, and is not the restriction to embodiments of the present invention.
Claims (2)
1. improve a method for calcium recovery rate in RH vacuum oven, its step:
1) carry out molten iron processing;
2) carry out converter smelting;
3) in LF stove, carry out refining:
A, carry out Argon, argon blowing time is not less than 1 minute, and adopts positive pressure operation, and pressure is higher than environmental stress;
B, change slag, change the slag time to be controlled at 3～10 minutes;
After c, change slag finish, add lime according to 3.3～5.0 kgs/tonne of steel, add refining slag according to 0.67～2.0 kg/tonne of steel, and according to 6.0～7.0 kgs/tonne of steel control quantity of slag, the O content in control molten steel is at 350～450PPm;
4) carry out RH vacuum-treat, and add lime according to 2.0～3.0 kgs/tonne of steel, and according to being routinely added to refining agent or sweetening agent;
5) be sprinkled into aluminum shot according to 0.1～0.5 kg/tonne of steel at slag surface uniform, then according to 4.0～6.0 meters of/ton of steel feeding silicon-calcium wires, and control wire-feeding velocity and be not less than 5 meter per seconds; Control FeO+MnO≤5.5 (wt%) in slag; Carry out conventional soft blow;
6) tap and pour into base.
2. a kind of method that improves calcium recovery rate in RH vacuum oven as claimed in claim 1, is characterized in that: in the time that slag produces crust phenomenon, adopt and add iron calcium line to carry out broken shell, iron calcium line adds according to 0.70～1.4 meter of/ton of steel control.
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| CN103695597A (en) * | 2013-12-11 | 2014-04-02 | 首钢总公司 | Molten steel calcium treatment process adopting pure calcium line |
| CN107541580B (en) * | 2017-08-25 | 2019-06-25 | 武汉钢铁有限公司 | The inclusion control method of Hot Rolling Automobile steel is smelted in CSP producing line |
| CN111575446B (en) * | 2020-06-25 | 2022-02-25 | 江苏省沙钢钢铁研究院有限公司 | RH vacuum furnace calcium treatment process method |
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| CN101462155A (en) * | 2007-12-21 | 2009-06-24 | 首钢总公司 | Method for producing ultra-low carbon wire by small square billet continuous casting |
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Effective date of registration: 20170711 Address after: 430083 Qingshan District, Hubei, Wuhan factory before the door No. 2 Patentee after: Wuhan iron and Steel Company Limited Address before: 430080 Wuhan, Hubei Friendship Road, No. 999, Wuchang Patentee before: Wuhan Iron & Steel (Group) Corp. |
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