CN101831525B - Dephosphorization method for molten iron - Google Patents
Dephosphorization method for molten iron Download PDFInfo
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- CN101831525B CN101831525B CN2010101834708A CN201010183470A CN101831525B CN 101831525 B CN101831525 B CN 101831525B CN 2010101834708 A CN2010101834708 A CN 2010101834708A CN 201010183470 A CN201010183470 A CN 201010183470A CN 101831525 B CN101831525 B CN 101831525B
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- dephosphorization
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Abstract
The invention provides a dephosphorization method for molten iron, which mainly aims at the dephosphorization of the molten iron of a large converter. The method comprises the following steps of: (1) supplying oxygen to the surface of the molten iron from the top through an oxygen lance, wherein the oxygen supply strength is changed in a range of 0.8 to 1.1 Nm<3>/t/min; (2) adding slag forming materials mainly comprising lime, light burned dolomite and ore into the molten iron through a hopper arranged above the converter to perform slag formation, wherein the binary alkalinity (CaO/SiO2) of the formed slag is 1.95-2.0; and (3) supplying stirring gas to the interior of the molten iron through a gas supply system at the bottom of the converter, wherein the gas supply strength is 0.25 to 0.40Nm<3>/t/min. The method promotes slag formation and oxygen supply by using low melting point of the low-alkalinity slag, easy slag forming property due to low temperature of the molten iron and large amount of the ore, prolongs the blowing time by using low oxygen supply strength, realizes full mix between slag and metal by using high bottom blowing strength, realizes dephosphorization, and has the advantages of good dephosphorization effect, low lime using amount, low consumption of accessories for dephosphorization and little slag discharge.
Description
Technical field
The present invention relates to a kind of dephosphorization method for molten iron, particularly relate to a kind of dephosphorization method for molten iron that utilizes large-scale top and bottom combined blown converter.
Background technology
In recent years, steel products are strict day by day to the requirement of phosphorus content.In order to satisfy the requirement of iron and steel quality, need efficiently remove the phosphorus in the molten iron as much as possible in the hot metal pretreatment stage.Dephosphorization of molten iron generally transports in container (like the torpedo jar) or the converter at molten iron and carries out.Transport container in utilization and carry out in the dephosphorization of molten iron process, because it is little to transport the container upper space, for fear of splash; Refining slag is selected high basicity and the low top slag of all iron content for use; This just defines the preceding necessary desiliconization of dephosphorization, has caused increase (for example, the TETSU-TO-HAGANE of lime consumption; 69 (1983), p.1818).In addition, the problem that existing of high basicity slag slag is difficult has limited the performance of top slag dephosphorizing capacity.Converter has the advantage that heat size is learnt well than big and dephosphorization power, and for traditional process of bessemerizing, steel scrap, molten iron and slag making are loaded into converter with auxiliary material; The top blast dioxygen oxidation is removed Si, P and the C etc. in the molten iron then; But because blowing liquid steel temperature in latter stage is high, be unfavorable for the removal of phosphorus, therefore need to use large quantities of lime; Increase basicity of slag and improve the dephosphorization effect, the use of superfluous lime can cause the slag quantity discharged to increase.
On the other hand,, must reduce the waste sludge discharge amount in the steelmaking process, reduce the use of fluorine-containing things such as fluorite from the viewpoint of environment protection.One Chinese patent application numbers 97116979.9 discloses " pre-dephosporizing method for molten iron ", and this method is utilized converter and used synthetic slag to carry out the preparatory dephosphorization of molten iron.Used synthetic slag consists of CaO (50-70%)-ferriferous oxide (15-35%)-CaF
2(5-15%) or CaO (55-70%)-ferriferous oxide (15-30%)-CaF
2(4-10%)-Na
2CO
3(4-9%), through this invention, the dephosphorization of molten iron rate can reach 85-90%.The synthetic slag dephosphorization is adopted in this invention, and production cost is high, and CaO content is high in the synthetic slag, and the slag slag is difficult, adopts CaF
2Change slag and Na
2CO
3Change slag, and CaF
2And Na
2CO
3Large usage quantity, bigger CaF
2And Na
2CO
3Consumption is very serious to the corrosion meeting of refractory materials in the converter stove, and Na
2CO
3Interpolation possibly cause slag to overflow.One Chinese patent application numbers 200680041842 discloses " the dephosphorization treatment method of molten iron "; This method is carried out dephosphorization of molten iron through oxygen, lime base dephosphorizing agent and solid oxygen source together are blown into through two different airing systems in the converter, do not contain CaF in the lime base dephosphorizing agent
2, adopt that phosphorus content can drop to 0.012-0.02% from 0.105-0.124% in this method molten iron, and lime consumption is in the 3.3-9.6kg/t scope.But; This method solid oxygen source is mainly agglomerate, steel scale of steel rolling, iron dust containing, iron ore, iron sand etc., and these solid oxygen sources need be processed into granularity less than 1mm, need drying; And increase blowing device; Therefore this method is produced investment greatly, and maintenance of the equipment requires high, is difficult in most steel mills and applies.
Molten iron phosphorus is generally removed through oxidizing reaction, and its simple reaction formula is suc as formula shown in (1).
2[P]+5[O]+3CaO＝3CaO·P
2O
5 (1)
Thermodynamics shows that low temperature has the absolute advantage condition of dephosphorization, and the molten steel molten iron temperature is low relatively, at molten iron temperature, makes the bits of good fluidity, guarantees the supply of slag, golden interface oxygen, and slag, gold mix fully, can obtain good dephosphorization effect.
Summary of the invention
The purpose of this invention is to provide a kind of dephosphorization method for molten iron; Utilize sophisticated top and bottom combined blown converter blowing technology; Adopt dephosphorization raw material commonly used to make the bits of good fluidity, guarantee the supply of slag, golden interface oxygen, slag, gold mix fully; Lime consumption is few, when protecting carbon, can obtain good dephosphorization effect.This method is not used fluorite simultaneously, has both reduced erosion and the environmental pollution of fluorite to furnace lining, improves the life-span of converter again greatly.
Technical scheme of the present invention is: adopt top and bottom combined blown converter, it is characterized in that: 1. adopt lime, light dolomite and ore to make dephosphorizing agent, lime, light dolomite consumption are according to target binary basicity of slag (CaO/SiO
2) be 1.95～2.0, MgO content be 4～7% with addition of, the ore consumption is 25～30Kg/t steel; 2. oxygen lance blow head exports Mach number: 1.5-2.0, top oxygen supply intensity: 0.8-1.1Nm
3/ t/min; 3. bottom gas-feeding intensity: 0.25-0.40Nm
3/ t/min.
Effective CaO content >=92% in the lime, effective CaO content >=48% in the light dolomite, effectively MgO content >=35%.Ore is agglomerate or pellet, and the agglomerate particle diameter is less than 50mm.
The oxygen rifle adopts the operation of permanent rifle position constant current amount, rifle position >=2.8m.
Lime, light dolomite are opened at the oxygen rifle and are blown the disposable adding in back, and ore adds in the 10%-60% of total oxygen-supplying amount in batches.
Bottom gas-feeding is nitrogen, argon gas or carbonic acid gas.
The present invention adopts dephosphorization of molten iron commonly used to use auxiliary material, and promptly lime, light dolomite, ore do not use fluorite.Under the prerequisite of big ore addition, less lime consumption, stir the thorough mixing of realizing between slag, gold through strengthening bottom blowing intensity, improve dephosphorization efficient, reduce steelmaking process waste sludge discharge amount.This method is not used fluorite, contains a certain amount of MgO in the slag, has both reduced erosion and the environmental pollution of fluorite to furnace lining, improves the life-span of converter again greatly.Adopt dephosphorization method for molten iron of the present invention, behind the dephosphorization according to weight percent, carbon content>=3.50%, phosphorus content≤0.025%.
Technical scheme of the present invention adopts following steps to carry out:
1. the present invention is applicable to that the converter of dephosphorization of molten iron is a mammoth conveter, converter capacity >=200t;
2. adopt special-purpose dephosphorization oxygen rifle, oxygen lance blow head outlet Mach number: 1.5-2.0 supplies with oxygen through the oxygen rifle from the converter top to the molten iron surface, adopts the operation of permanent rifle position constant current amount, rifle position>=2.8m, and oxygen supply intensity is at 0.8-1.1Nm
3Change in/t/min the scope;
3. the hopper that is provided with through the converter top adds the dephosphorizing agent that is the main body with lime, light dolomite, ore and carries out slag making in molten iron.Lime, light dolomite consumption are 1.95～2.0 according to target binary basicity of slag (CaO/SiO2), MgO content be 4～7% with addition of.Effective CaO content >=92% in the lime, effective CaO content >=48% in the light dolomite, effectively MgO content >=35%.Lime, light dolomite are opened at the oxygen rifle and are blown the disposable adding in back.Ore has refrigerant, dissolving agent, oxygen source effect concurrently in the slag former, and ore adds in the 10%-60% of total oxygen-supplying amount in batches, and the ore consumption is 25～30Kg/t steel.Used ore is agglomerate or pellet, and particle diameter is less than 50mm.
4. in top blowing oxygen, stir gas through the converter bottom gas supply system to the molten steel internal feed, gas is stirred in the converter bottom blowing can be in nitrogen, argon gas or the carbonic acid gas any one, air supply intensity is 0.25-0.40Nm
3/ t/min.
Technique effect of the present invention:
1. utilized sophisticated top and bottom combined blown converter blowing technology, thermodynamics, the dynamic conditions of dephosphorization of molten iron are not fully exerted.
2. adopt dephosphorization raw material commonly used, lime, light dolomite, ore are made low basicity slag, and slagging is fast under the coldcondition.
3. adopt to add a large amount of ores, can the promotion slag, can also promote dephosphorization to slag, the oxygen supply of golden interface.
4. do not use the fluorite slag making, reduce the erosion of fluorite, be beneficial to and improve converter work-ing life furnace lining.
5. adopt light dolomite in the slag former, guaranteeing to protect furnace lining under the fast condition of slagging, improve converter work-ing life.
6. basicity of slag is low, and lime consumption is few, and cost is low, and the slag quantity discharged is few.
Embodiment
For smelting main points of the present invention and implementation result thereof clearly are described, the embodiment and the implementation result of 210 tons of converter smeltings is provided.
According to large-scale top and bottom combined blown converter dephosphorization method for molten iron provided by the present invention; To 210 tons of top and bottom combined blown converters pack into steel scrap and molten iron, the molten iron condition is seen table 1, adopts the special-purpose dephosphorization oxygen rifle among the present invention to blow; Oxygen lance position 2.8-3.0m in the blowing, oxygen supply intensity are 0.8-1.1Nm
3/ t/min, concrete oxygen lance position and oxygen supply intensity change as shown in table 1.After the oxygen rifle is opened and is blown, with lime, light dolomite is disposable puts in the converter, total oxygen-supplying amount 15%, 30%, 45%, 60% in add pellet in four batches.Bottom blown gas adopts nitrogen in the converting process, and air supply intensity is seen table 1.To reach target oxygen consuming time when blowing, closes oxygen, carries the oxygen rifle.After the finishing blowing, metal ingredient is seen table 1.
Table 1
Can find out from embodiment, adopt converter dephosphorization method for molten iron of the present invention, can realize at an easy rate that phosphorus content is less than 0.025% in the molten iron, carbon content is greater than 3.50%; This method is not used fluorite, contains a certain amount of MgO in the slag, has both reduced erosion and the environmental pollution of fluorite to furnace lining; Improve the life-span of converter again greatly, this has created favourable condition for realizing converter less-slag decarburization steel-making, and dephosphorization is few with the quantity of slag; Slag emission is few, and dephosphorization effect is stable, and application value is widely arranged.
Claims (5)
1. a dephosphorization method for molten iron adopts top and bottom combined blown converter, and it is characterized in that: 1. adopt lime, light dolomite and ore to make dephosphorizing agent, lime, light dolomite consumption are according to target binary basicity of slag (CaO/SiO
2) be 1.95～2.0, MgO content be 4～7% with addition of, the ore consumption is 25～30Kg/t steel; 2. oxygen lance blow head exports Mach number: 1.5-2.0, top oxygen supply intensity: 0.8-1.1Nm
3/ t/min; 3. bottom gas-feeding intensity: 0.25-0.40Nm
3/ t/min.
2. a kind of dephosphorization method for molten iron as claimed in claim 1; It is characterized in that: effective CaO content >=92% in the lime, effective CaO content >=48% in the light dolomite, effectively MgO content >=35%; Ore is agglomerate or pellet, and the agglomerate particle diameter is less than 50mm.
3. a kind of dephosphorization method for molten iron as claimed in claim 1 is characterized in that: the oxygen rifle adopts the operation of permanent rifle position constant current amount, rifle position >=2.8m.
4. a kind of dephosphorization method for molten iron as claimed in claim 1 is characterized in that: lime, light dolomite are opened at the oxygen rifle and are blown the disposable adding in back, and ore adds in the 10%-60% of total oxygen-supplying amount in batches.
5. a kind of dephosphorization method for molten iron as claimed in claim 1 is characterized in that: bottom gas-feeding is nitrogen, argon gas or carbonic acid gas.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010101834708A CN101831525B (en) | 2010-05-19 | 2010-05-19 | Dephosphorization method for molten iron |
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|---|---|---|---|
| CN2010101834708A CN101831525B (en) | 2010-05-19 | 2010-05-19 | Dephosphorization method for molten iron |
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| CN101831525A CN101831525A (en) | 2010-09-15 |
| CN101831525B true CN101831525B (en) | 2012-01-25 |
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|---|---|---|---|---|
| CN102242239B (en) * | 2011-07-28 | 2013-04-17 | 首钢总公司 | Molten iron pre-dephosphorization method by utilizing top and bottom combined blown converter |
| CN108396103B (en) * | 2017-02-05 | 2020-01-07 | 鞍钢股份有限公司 | Method for removing slag by using ladle powder injection instead of molten steel |
| CN112877496A (en) * | 2021-01-14 | 2021-06-01 | 安徽工业大学 | Method for realizing efficient dephosphorization in dephosphorization period by controlling phase of slagging process |
| CN115096071B (en) * | 2022-05-13 | 2023-05-26 | 北京科技大学 | Method for reducing consumption of steel-making lime of electric arc furnace by recycling tailings |
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| JP2001131623A (en) * | 1999-11-04 | 2001-05-15 | Nippon Steel Corp | Dephosphorizing method of molten iron |
| CN101314805B (en) * | 2007-05-31 | 2010-10-13 | 上海梅山钢铁股份有限公司 | High-efficiency dephosphorization smelting method for medium phosphor hot metal revolving furnace |
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Effective date of registration: 20140404 Address after: 100041 Shijingshan Road, Beijing, No. 68, No. Patentee after: Capital Iron & Steel General Company Address before: 100041 Shijingshan Road, Beijing, No. 68, No. Patentee before: Capital Iron & Steel General Company Patentee before: Hebei Shougang Qian'an Steel Co., Ltd. |
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Address after: 100041 Shijingshan Road, Shijingshan District, Shijingshan District, Beijing Patentee after: Shougang Group Co. Ltd. Address before: 100041 Shijingshan Road, Shijingshan District, Shijingshan District, Beijing Patentee before: Capital Iron & Steel General Company |