CN101775458B - Method for controlling foreign impurities in first molten steel of rotating furnace after overhaul - Google Patents

Abstract

The invention relates to a method for controlling foreign impurities in the first molten steel of a rotating furnace after an overhaul. The method comprises the following steps of: repairing the large area of a hearth of the rotating furnace with coke and dolomite bulk materials, sintering the coke and dolomite bulk materials at the hearth temperature of between 1,350 and 1,400 DEG C for 65 to 70 minutes and filling 100 percent of molten iron into the hearth; smelting the mixture in the rotating furnace under conditions of blowing an oxygen gas into the rotating furnace from the top for 15 to 16 minutes at the intensity of 3.0 NM3/minute.t; blowing an argon gas into the rotating furnace from the bottom at the intensity of between 0.03 and 0.04 NM3/min.t when the oxygen gas is blown into the rotating furnace from the top; blowing the argon gas into the rotating furnace from the bottom in an increasing amount at the intensity of between 0.04 and 0.06 NM3/min.t for 2 to 3 minutes after the oxygen supply from the top is finished; blowing the argon gas into the rotating furnace in a decreasing amount for 2 to 3 minutes at the argon supply intensity of between 0.01 and 0.03 NM3/min.t; and retaining slag and discharging steels. The method solves the problem that refractory materials and mixed slag in a furnace hearth pollute the final molten steel product and provides technical conditions for smelting first excellent steel after the rotating furnace is repaired without new flow and new equipment.

Description

The big method of repairing foreign impurity in the first stove molten steel of back of control converter

Technical field

The present invention relates to the control method of inclusion in the smelting process molten steel, specifically belong to the big control of repairing foreign impurity in the first stove molten steel of back of converter.

Background technology

The converter fettling is to prolong indispensable measure of furnace life in the STEELMAKING PRODUCTION; For a long time; The difficult problem that steelwork converter production faces is, first stove is not arranged variety steel behind the big fettling, with the pollution to molten steel such as control mending material; Promptly fetter the organization of production ability of converter-continuous casting flow process variety steel, also do not improved the pollution of foreign impurity in the first stove molten steel behind the converter fettling.

Document [Way LD.Cleanness; Castability; And surface quality of formable sheet steels.MaterialsScience and Technology.2001; 17 (10): 1175] but summarized the influence of the large-scale oxide inclusion that forms in the molten steel to carbon aluminium-killed steel and ultra low carbon IF steel cleanness castibility, surface quality, proposed control smelting equipment, tundish foreign impurity source, added the purification of molten steel agent and make the measure of inclusion floating in the slag; Document [.30t converter-ladle argon-blown such as Shang Deli-continuous casting is produced the nonmetal inclusion in the A level deck of boat steel. special steel .2007, and 28 (6): [51]

introduced the measure that Anshan iron and steel plant reduces A level deck of boat steel large-sized inclusions; Document [Shi Hongzhi etc. Application and Development ladle slag reduction treatment technology improves the purity of steel. Baotou Iron & Steel Inst journal .1999,18 (B09): 341] reported to be that the ladle slag reduction that raising molten steel purity carries out is handled; Document [Yang Wenyuan etc. the degree of cleaning research of small vessel steel. steel-making .2006,22 (3): 17] reported the degree of cleaning level of small vessel steel-making.

Chinese patent [application number: 01131296,20051116] provides a kind of agent for purifying molten steel and Si-Ca-Ba-Mg complex deoxidization agent producing process, to improve the steel inclusion form; Chinese patent [application number: 02123885,2005-03-23] reported a kind of refining agent of forming by calcium carbide powder, deactivating magnesium powder, aluminium powder and ferrosilicon powder, be used for the soft steel deoxidizing purification; Chinese patent [application number: 200710064890] discloses a kind of hot metal pretreatment and has added converter and add the LF stove and add the method that vacuum-treat adds continuous casting whole process control nonmetallic inclusionsin steel.

In the foreign patent, SUMITOMO CHEMICAL metal [Japan.No.JP8281392] has been reported the method for the tiny external nonmetal inclusion of a kind of direct solenoid stirring and segregation; Nippon Steel [Japan.No.JP10005949] has proposed a kind of method of discharging in mold inner control foreign impurity come-up with electromagnetic force.

The inclusion that reduces or control in the steel can adopt different methods, do from the different links of Production Flow Chart.The characteristics of above-mentioned document and patent mainly are the control of steelmaking process whole process; Or adopt reductor, scavenging agent improvement to be mingled with form; Or the employing ladle slag is reduced, induction stirring; Its method steps, steel grade, effect and special emphasis are different, do not smelt variety steel and how to control under this condition the technology of foreign impurity report in the molten steel but relate to behind the converter fettling first stove as yet.

All the time, steel mill is because the cleanliness factor that variety steel requires is high, and tight to being mingled with content control in the molten steel, first stove forbids smelting variety steel behind the big fettling of converter, has limited the organization of production ability and the maneuvering ability of converter-continuous casting flow process variety steel.

Summary of the invention

The objective of the invention is to overcome above-mentioned deficiency, foreign impurity method in the first stove smelting endpoint molten steel is provided behind the big fettling of a kind of control converter, improve the efficient and the maneuvering ability of variety steel organization of production.

Realize the technical measures of above-mentioned purpose:

The big method of repairing foreign impurity in the first stove molten steel of back of control converter, its step:

1) converter adopt the tar rhombspar loose the shape material to its burner hearth in before and after big face repair, the mending material consumption is 25～32kg/ ton steel, and under 1350～1400 ℃ fire box temperature condition sintering after 65～70 minutes, 100% the molten iron of packing into;

2) carry out converter smelting: the top blast oxygen supply time is 15～16 minutes, and oxygen supply intensity is 3.0NM ³/ min.t; Bottom Argon during top blowing oxygen, supplying argon intensity is 0.03～0.04NM ³/ min.t;

3) after converter top-blow oxygen finished, the bottom was with 0.04～0.06NM ³The confession argon intensity of/min.t is carried out the increment Argon, and argon blowing time is 2～3 minutes;

4) the increment Argon is carried out the decrement Argon after finishing, and supplying argon intensity is 0.01～0.03NM ³/ min.t, argon blowing time is 2～3 minutes;

5) carry out the pushing off the slag tapping after the decrement Argon finishes.

It is: the confession argon intensity of decrement Argon process is 0.01～0.017NM ³/ min.t.

The present invention compared with prior art has following useful effect:

1) can expand the function of cleaning molten steel in the converter, improve refractory materials and molten bath and mixed the pollution of slag the terminal point molten steel; With ratio before improving, external oxide inclusion total amount has on average reduced by 60% in the terminal point molten steel, and back operation does not have the bad waste product of steel, and the steel grade performance meets the technical qualification of delivery.

2) smelting the fine quality steel for first stove behind the converter fettling provides technical qualification, need not newly-increased flow process and equipment, and the efficient and the maneuvering ability effect that steel mill are improved converter-continuous casting variety steel organization of production are very big.

Description of drawings

Fig. 1 is the comparison that the first stove smelting endpoint adopts external oxide inclusion total amount [MeO] (weight percent) in present method and the Comparative Examples steel behind the big fettling of converter.Among the figure, mark ● be present method, zero is Comparative Examples.

Embodiment

Be described in detail below:

Embodiment 1

Adopt the big repairing of converter back first stove to smelt ship steel totally two stoves, its control repair material gets into the method in the molten steel:

1) converter adopt the tar rhombspar loose the shape material to its burner hearth in before and after big face repair; The mending material consumption is a 30/32kg/ ton steel; And under 1350～1370 ℃/1380～1400 ℃ fire box temperature condition sintering after 65/66 minute, 100% the molten iron of packing into is smelted;

2) carry out converter smelting, top blast oxygen supply 15 minutes, oxygen supply intensity is 3.0NM ³/ min.t, bottom Argon during the top blowing oxygen supplies argon intensity 0.03～0.04NM ³/ min.t;

3) after converter top-blow oxygen finished, the bottom was with 0.04NM ³The confession argon intensity of/min.t is carried out the increment Argon, argon blowing time 2 minutes;

4) the increment Argon is carried out the decrement Argon after finishing, and supplying argon intensity is 0.01NM ³/ min.t, argon blowing time 2 minutes;

5) carry out the pushing off the slag tapping after the decrement Argon finishes.

Through detecting, during smelting endpoint, basicity of slag is 3.0～3.5,1650～1680 ℃ of molten steel temperatures, and oxide inclusion in the steel [MeO] total amount is 0.0080～0.0090% (weight percent); In mending material, add the barium carbonate BaCO that accounts for mending material gross weight 5% in advance ₃Make tracer agent, detect [BaO] content in the steel＜0.00001% (weight percent) through converter smelting endpoint and the sampling of ladle argon-blown station;

Molten steel waters into slab through ladle argon-blown with continuous casting, rolls into the thick ship plate of 4mm/10mm in hot rolling, and back operation stocking does not have the bad waste product of steel, and the delivery performance meets the ship steel technical qualification.

Embodiment 2

Adopt the big repairing of converter back first stove to smelt the anti-Hou Gang of vehicle totally two stoves, its control repair material gets into the method in the molten steel:

1) converter adopt the tar rhombspar loose the shape material to its burner hearth in before and after big face repair; The mending material consumption is a 25/30kg/ ton steel; And under 1360～137 ℃/1380～1390 ℃ fire box temperature condition sintering after 65～70 minutes, 100% the molten iron of packing into is smelted;

2) carry out converter smelting, top blast oxygen supply 15 minutes, oxygen supply intensity is 3.0NM ³/ min.t, bottom Argon during the top blowing oxygen supplies argon intensity 0.03～0.04NM ³/ min.t;

3) after converter top-blow oxygen finished, the bottom was with 0.05NM ³The confession argon intensity of/min.t is carried out the increment Argon, argon blowing time 2.5 minutes;

4) the increment Argon is carried out the decrement Argon after finishing, and supplying argon intensity is 0.016NM ³/ min.t, argon blowing time 2.5 minutes;

5) carry out the pushing off the slag tapping after the decrement Argon finishes.

Through detecting, during smelting endpoint, basicity of slag is 3.2～3.8,1659～1673 ℃ of molten steel temperatures, and oxide inclusion in the steel [MeO] total amount is 0.0085～0.0090% (weight percent); In mending material, add the barium carbonate BaCO that accounts for mending material gross weight 5.8% in advance ₃Make tracer agent, detect [BaO] content in the steel＜0.00001% (weight percent) through converter smelting endpoint and the sampling of ladle argon-blown station;

Molten steel waters into slab through ladle argon-blown with continuous casting, and rolls into the thick steel plate of anti-marquis of 2.3mm/8.0mm in hot rolling, and back operation stocking does not have the bad waste product of steel, and the delivery performance meets the anti-Hou Gang technical qualification of vehicle.

Embodiment 3

Adopt big repairings of converter back first stove to smelt automobile with deep drawing steel totally three stoves, the method in its control repair material entering molten steel:

1) converter adopt the tar rhombspar loose the shape material to its burner hearth in before and after big face repair; The mending material consumption is a 28/29/30kg/ ton steel; And under 1380～1390 ℃/1380～1390 ℃/1385～1400 ℃ fire box temperature condition sintering after 65/68/70 minute, 100% the molten iron of packing into is smelted;

2) carry out converter smelting, top blast oxygen supply 16 minutes, oxygen supply intensity is 3.0NM ³/ min.t, bottom Argon during the top blowing oxygen supplies argon intensity 0.03～0.04NM ³/ min.t;

3) after converter top-blow oxygen finished, the bottom was with 0.06NM ³The confession argon intensity of/min.t is carried out the increment Argon, argon blowing time 3 minutes;

4) the increment Argon is carried out the decrement Argon after finishing, and supplying argon intensity is 0.017NM ³/ min.t, argon blowing time 3 minutes;

5) carry out the pushing off the slag tapping after the decrement Argon finishes.

Through detecting; During smelting endpoint, basicity of slag is 3.3～4.2,1650～1670 ℃ of molten steel temperatures; Oxide inclusion in the steel [MeO] total amount is 0.009～0.001% (weight percent), in mending material, adds the barium carbonate BaCO that accounts for mending material gross weight 6.25% in advance ₃Make tracer agent, detect [BaO] content in the steel＜0.00001% (weight percent) through converter smelting endpoint and the sampling of ladle argon-blown station;

Molten steel waters into slab through ladle argon-blown with continuous casting, and uses steel through hot rolling and the thick automobile deep-draw of the cold rolling 1.5mm/1.5mm/2.0mm of rolling into, and back operation stocking does not have the bad waste product of steel, and the delivery performance meets cold-rolling deep-punching sheet steel technical qualification.

Claims (1)

1. control the big method of repairing foreign impurity in the first stove molten steel of back of converter, its step:

1) converter adopt the tar rhombspar loose the shape material to its burner hearth in before and after big face repair, the mending material consumption is 25～32kg/ ton steel, and under 1350～1400 ℃ fire box temperature condition sintering after 65～70 minutes, 100% the molten iron of packing into;

2) carry out converter smelting: the top blast oxygen supply time is 15～16 minutes, and oxygen supply intensity is 3.0Nm ³/ mint; Bottom Argon during top blowing oxygen, supplying argon intensity is 0.04Nm ³/ mint;

3) after converter top-blow oxygen finished, the bottom was with 0.04～0.06Nm ³The confession argon intensity of/mint is carried out the increment Argon, and argon blowing time is 2～3 minutes;

4) the increment Argon is carried out the decrement Argon after finishing, and supplying argon intensity is 0.01～0.03Nm ³/ mint, argon blowing time is 2～3 minutes;

5) carry out the pushing off the slag tapping after the decrement Argon finishes.

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