CN100351399C - Method for pig iron melt dephosphorize - Google Patents
Method for pig iron melt dephosphorize Download PDFInfo
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- CN100351399C CN100351399C CNB011162422A CN01116242A CN100351399C CN 100351399 C CN100351399 C CN 100351399C CN B011162422 A CNB011162422 A CN B011162422A CN 01116242 A CN01116242 A CN 01116242A CN 100351399 C CN100351399 C CN 100351399C
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Abstract
The present invention relates to a method for enhancing the dephosphorizing efficiency and reducing the quantity of generated furnace slag without using halide during the process of dephosphorizing pig iron melt, wherein a top blown and bottom blown converter type reactor is adopted, and lime and iron oxide and/or oxygen gas are added into pig iron melt. The alkalinity of furnace slag is regulated, and before treatment, the CaO to O ratio of a melting agent is controlled according to the Si concentration (Si; %) in pig iron melt to make lambda satisfy the following formulas (1) and (2); CaO/O=2.3*Si+lambda... (1), and lambda=-0.4... +0.4... (2).
Description
The present invention relates to the method for pig iron melt dephosphorization, this method can improve dephosphorisation reaction efficient when carrying out the dephosphorization treatment of pig iron melt, reduces the slag amount that produces, and does not use halogenide.
The dephosphorizing technology of pig iron melt is widely known by the people.Adopting under the situation of torpedo type car as transport container, used as reactor, because the volume of its upper space (headroom) is little, the consumption rate height of lime when carrying out dephosphorization by increasing basicity and reducing wherein total iron content, uses through with the formation of avoiding slag (for example carrying out pig iron melt that desiliconization handles in advance, Tetsu To Hagane, Vol 69,1983, after the p1818).In such cases,, but still exist consumption rate height to cause the big problem of dephosphorization slag amount owing to lime although carried out the desiliconization processing in advance.In addition, because high basicity has suppressed the formation of slag, and must use a large amount of halogenide such as Calcium Fluoride (Fluorspan) and calcium chloride, so this brings another problem, i.e. slag amount increase and refractory materials are by strong erosion.
Do not use halogenide to attempt to improving reaction efficiency in the pig iron melt dephosphorizing process already.
For example, among the Japanese unexamined publication H2-11712 a kind of dephosphorizing agent is disclosed, by ferric oxide, CaO and SiO
2Mixing back fusion or sintering makes.And in Japanese unexamined publication S56-93806 a kind of dephosphorizing agent is disclosed, by basicity (CaO/SiO
2) be 1.8～2.3 2CaO-SiO
2The powdered material sintering is made.Because fusion or the required cost height of sintering be not so these technology drop into practical application as yet.
Disclose among the Japanese unexamined publication H8-157921 a kind of in converter, at basicity=1.2～2.0, Al
2O
2=2～16%, and the pig iron melt dephosphorizing method under total Fe=7～30% condition.In such cases, because this reaction only betides the top slag in converter, thereby exists a problem, promptly owing to reduce the basicity of top slag and add a large amount of neutral oxide Al
2O
3Dephosphorizing capacity will be worsened.
Simultaneously, at Tetsu To Hagane, Vol 76,1990, No.11, and the CaO/O that discloses flux after the p 1801 determines dephosphorisation reaction efficient, and the ratio of CaO/O is low more, lime dephosphorization efficient is high more.Yet, unexposedly in this paper do not use halogenide and improve the condition of pig iron melt dephosphorisation reaction efficient.
The invention provides a kind of method of pig iron melt dephosphorization, this method not using raising dephosphorisation reaction efficient under the halid situation, reduces the slag amount that produces by solving the defective in the above-mentioned routine techniques.Defective in the above-mentioned routine techniques is: the consumption rate height of lime, and thereby must use a large amount of halogenide to form the slag of high basicity, and total Fe treatment capacity is low, as disclosed by CaO and SiO among Japanese unexamined publication H2-11712 and the S56-93806
2Mix and carry out fusion or the required cost height of sintering when the back prepares dephosphorizing agent by fusion or sintering, and disclosedly among the Japanese unexamined publication H8-157921 form the method for carrying out the pig iron melt dephosphorization by control top slag dephosphorizing capacity is greatly worsened, and at Tetsu To Hagane, Vol 76,1990, No.11 fails to be disclosed in the condition that improves pig iron melt dephosphorisation reaction efficient under the halid situation of not using after the p 1801.
The present invention will be described in more detail below.
(1) a kind of dephosphorizing method uses lime and ferric oxide and/or oxygen, adopts top blast and bottom-blown converter type reactor, it is characterized in that, the basicity of slag is adjusted to 1～2.5, and before processing, with following formula (1) and (2) concentration ([Si] according to [Si] in the pig iron melt; %) the CaO/O of control flux;
CaO/O＝2.3×[Si]+λ …(1)
λ＝-0.4～+0.4 …(2)
Herein, CaO represents the consumption rate (kg/t) of lime, and outside the CaO that provides divided by lime and Wingdale form, this lime also is included in the CaO component concentration (by weight) in the recirculation slag.O represents the consumption rate (kg/t) of total oxygen, and by weight, it is with FeO and Fe in ferric oxide, the recirculation slag
2O
3Contained total oxygen demand in oxygen that form exists and the oxygen that provides with the oxygen form.The lower limit set of CaO/O ratio be 0.2 and the upper limit be set at 2.0.
According to the pig iron melt dephosphorizing method of above-mentioned (1), it is characterized in that (2) adjusting parameter α is 600～1300, wherein parameter alpha is limited by following formula (3), and it is by top blowing oxygen gas velocity (F; Nm
3/ hour/ton), the uniform mixing time (τ that bottom blowing is stirred; Second), the dark (Lo in pond; Millimeter), and top-blown gas forms the degree of depth (L in pond, chamber on the surface of molten pig; Millimeter) forms;
α＝(F/60)×τ×Lo/L …(3)
Herein, the uniform mixing time that bottom blowing is stirred (τ, second) calculate by following formula (4) and (5);
τ＝(10/60)×{[(D/10)
2/(Lo/10)]
2×ε}
0.337 …(4)
ε＝371/1000×Q×T×{ln(1+7×H/10330)+0.06×(1-298/T)}
…(5)
Herein, D represents pond diameter (millimeter), and Lo is pond dark (millimeter), and Q is the flow velocity (Nm that stirs gas
3/ second/ton), T is the temperature (K) of pig iron melt, and H is the spray penetration of the stirring gas identical with Lo.Note, consider that in the decarburizing reaction under the oxygen situation is arranged, Q is set at the twice of feed gas flow velocity, and consider that the decomposition under the LPG situation, Q are set at four times of feed gas flow velocity.
In addition, L (millimeter) (6) and (7) calculating according to the following equation;
L＝Lh×exp(-0.78h/Lh) …(6)
Lh＝63[F×W/(n×d)]
2/3 …(7)
Herein, W represents the weight (ton) of molten steel, and F is the flow velocity (Nm of top blowing oxygen
3/ hour/ton), n is the spray tip number, d is spray tip diameter (millimeter), and h is that lance head is to the ironing surface distance of fusion (millimeter).
(3) according to the pig iron melt dephosphorizing method of above-mentioned (1) or (2), it is characterized in that, only use lime and ferric oxide and/or oxygen, perhaps with the SiO of one or more types as dephosphorizing agent
2, Al
2O
3And the MgO mixture uses with lime and ferric oxide and/or oxygen, and do not use halogenide.
Herein, halogenide refers to the compound with F and Cl by Calcium Fluoride (Fluorspan) and calcium chloride representative.When reusing the decarburization slag, the dephosphorization slag, when secondary refining slag and desiliconization slag, lime comprises wherein contained any CaO component.In addition, ferric oxide, SiO
2, Al
2O
3, or MgO comprises the every kind of respective components that is included in respectively in the recirculation slag.
(4) according to each pig iron melt dephosphorizing method in above-mentioned (1)～(3), it is characterized in that, in the decarburization slag with CaO instead of part or whole lime.
Fig. 1 is that [Si] is under 0.15～0.35% situation, by the λ of test-results acquisition and the graph of a relation between the dephosphorization efficient.
Fig. 2 is that [Si] is under 0.5～0.65% situation, by the λ of test-results acquisition and the graph of a relation between the splash frequency.
Fig. 3 is by the α of test-results acquisition and the graph of a relation between the dephosphorization efficient.
The present invention has disclosed a brand-new fact, if namely to process in the front pig iron melt [Si] concentration and The relation of CaO/O is suitably controlled, even when then basicity is in fixed range, also can realize dephosphorization.
Usually, when [Si] concentration before processing in pig iron melt is low, because slag amount descends, need Improve the dephosphorizing capacity of slag. Therefore, need to high alkalinity (%CaO)/(%SiO2) lower operation, and Owing to suppressed slag formation, cause using this significant problem of calcirm-fluoride, and because non-slag lime Precipitation cause available material to be restricted. On the other hand, as [Si] when concentration is higher, also have one Individual problem namely causes having the tendency of splash owing to slag is excessive.
Yet the inventor finds, if control the activity of interface oxygen according to [Si] before processing, deposits At certain condition, also can realize dephosphorization even basicity value is low to moderate at 0.8～1.9 o'clock, and splash does not take place. Also In other words, if [Si] before processing is lower, by improving the interface oxygen activity in the situation that need not to improve basicity Under can promote dephosphorizing, and if [Si] before processing when higher, even because slag abundance interface oxygen Also can realize dephosphorization during activity decreased. And owing to carry out above-mentioned adjusting, the decarbonization on the interface is subjected to pressing down System, thereby splash does not take place.
The parameter that represents the interface oxygen activity is CaO/O, and above-mentioned formula (1) is in careful experimental result Find on the basis.
CaO＝2.3×[Si]+λ …(1)
λ＝-0.4～+0.4 …(2)
Figure 1 shows that as [Si] be in 0.15～0.35% situation, the relation between λ and the dephosphorization efficient. Work as λ Surpass at 0.4 o'clock, dephosphorization efficient is because oxygen activity low reduction the too, and when λ less than-0.4 the time, even oxygen work Property is higher, and dephosphorization efficient also can be owing to the specific consumption of lime low reduction the too. Figure 2 shows that [Si] is 0.5 in～0.65% situation, the relation between λ and the splash frequency. When λ less than-0.4 the time, because oxygen activity Too high and cause splash tendency to increase and operating difficulties. In such cases, even λ surpasses at 0.4 o'clock, take off Phosphorus efficient can not reduce yet. But uneconomical because the specific consumption of lime significantly increases.
Herein, dephosphorization efficient (K) is limited by following formula (8);
K＝ln([P]
1/[P]
2)/W
CaO …(8)
[P]
1The phosphorus concentration in the fusant in previous existence, [P] are processed in representative2The phosphorus concentration in the pig iron melt after processing, and WCaOIt is the specific consumption (kg/t) of the lime proofreaied and correct of the usefulness [Si] that calculates such as following formula (9);
W
CaO＝W
Lime-([Si]
1-0.2)×20 …(9)
[Si]
1The Si concentration in the fusant in previous existence is processed in representative, and WLimeIt is the specific consumption of lime (kg/t).
Relate to the present invention of above-mentioned (2) and be described in further detail in preferred embodiment by those of its derivation.
Relate to the present invention of above-mentioned (2) item, describe the condition of more suitably controlling the interface oxygen activity in detail. Specific condition is that parameter alpha is adjusted in 600～1300, and wherein parameter alpha is limited by following formula (3), it By top blowing oxygen gas velocity (F; Nm3/ hour/ton), the mixing time (τ that bottom blowing is stirred; Second), the pond is dark (Lo; Millimeter), and top-blown gas forms the degree of depth (L in pond, chamber on the surface of molten iron; Millimeter) group Become;
α＝(F/60)×τ×Lo/L …(3)
α is F/ (L/Lo) and the ratio of 1/ τ, and F/ (L/Lo) is the parameter that characterizes iron oxide production rate on the interface. 1/ τ Be the parameter that characterizes carbon slip in the pig iron melt, and the control index of it and interface oxygen activity is corresponding. By figure 3 as seen, when α less than 600 the time, make the dephosphorization Efficiency Decreasing owing to the interface oxygen activity reduces. Surpass 1300 and work as α The time, owing to the too high splash that is easy to take place that becomes of interface oxygen activity.
Relate to the present invention of above-mentioned (3) item, describe the suitable composition of Dephosphorising agent in detail. According to the present invention, Because basicity is 0.8～1.9, no matter [Si] in the pig iron melt, slag forms well, owing to can make apparatus There is the slag of high liquid fraction to carry out refining, thereby do not need to use halide, and can only use as Dephosphorising agent Lime and iron oxide and/or oxygen. The perhaps SiO of one or more type2，Al
2O
3And the mixture of MgO. Herein, SiO2，Al
2O
3And total mixing ratio of MgO should be above 15%, in order to do not make taking off of dephosphorization slag The phosphorus ability reduces. If use halide increases owing to be dissolved into the solubility of the MgO in the slag, and leads Cause the refractory corrosion aggravation.
Relating to the present invention of above-mentioned (4) item, is to replace part or all of lime with CaO in the decarburization slag. The decarburization slag is higher than the temperature of pig iron melt in the dephosphorization treatment process owing to its fusing point, thereby generally is difficult to melt Melt. And, high and when melting, produce suddenly the FeO reduction and cause being easy to take place splash owing to total Fe amount. According to the present invention, the decarburization slag is easy to melting, and because no matter basicity can be controlled in 0.8～1.9 and the pig iron [Si] in the melt therefore is easy to form slag. Owing to can under the condition that splash does not take place, carry out the dephosphorization place Therefore reason can use the decarburization slag.
Embodiment
Embodiment uses and is of a size of 300 tons top blown converter.Pond diameter D is 6.0m, and the dark Lo in pond is 1.9m.Contain 4.3% C by injection, 0.15～0.65% Si, 0.31% Mn, waste material and the pig iron melt of 0.105% P and 0.032% S carry out the dephosphorization refining, and its temperature is about 1350 ℃.In the dephosphorization treatment process, oxygen is with 0.8～2.5Nm
3/ minute/ton speed blow about 5～10 minutes by top-blown spray gun, and add the unslaked lime of about 10～15kg/t and the iron ore of about 0～20kg/t.Do not add halogenide such as Calcium Fluoride (Fluorspan) etc.The pig iron melt of handling contains 4.0% the C of having an appointment, about 0.01% Si and about 0.015% P, and its temperature is about 1370 ℃.The diameter of top-blown spray gun is 65 millimeters, and has 6 standard orifices, and by the diameter of control spray gun and the distance between lance head and the molten pig surface L/Lo is changed in 0.05～0.5.Carry out bottom blowing by two-tube air port injection of oxygen and LPG, so that with 0.05～0.2Nm
3/ minute/ton speed cooling, and the mixed uniformly time between 30～70 seconds, change.
To use diameter be 65 millimeters and have the top-blown spray gun in 6 holes, contain 0.25%[Si before will handling] pig iron melt at 35000Nm
3/ hour the top blowing oxygen gas velocity under, and spray 3600Nm through the two-tube air port of bottom blowing
3/ hour oxygen and 100Nm
3Stir under the condition of/hour LPG.In such cases, Q is 0.00603Nm
3/ second/ton, and the distance between lance head and the molten pig surface is 3750 millimeters.Consequently, the uniform mixing time τ that bottom blowing is stirred is 40 seconds, and the chamber tank depth L that is formed on the molten pig surface by top-blown gas is 124 centimetres, and parameter alpha is 1017.
Blow oxygen about 7 minutes by top-blown spray gun, and add the unslaked lime of 14.5kg/t and the iron ore of 15kg/t.At this moment, CaO/O be 0.66 and λ be+0.086.Consequently, by handling about 7 minutes, [P] in the pig iron melt reduces to 0.018% by 0.110%, and dephosphorization efficient is 0.134 and good.
To use diameter be 65 millimeters and have the top-blown spray gun in 6 holes, contain 0.44%[Si before will handling] pig iron melt at 30000Nm
3/ hour the top blowing oxygen gas velocity under, and spray 3600Nm through the two-tube air port of bottom blowing
3/ hour oxygen and 100Nm
3Stir under the condition of/hour LPG.In such cases, Q is 0.00603Nm
3/ second/ton, and the distance between lance head and the molten pig surface is 3250 millimeters.Consequently, the uniform mixing time τ that bottom blowing is stirred is 40 seconds, and the chamber tank depth L that is formed on the molten pig surface by top-blown gas is 123 centimetres, and parameter alpha is 882.
Blow oxygen about 7 minutes by top-blown spray gun, and add the unslaked lime of 18.15kg/t, but do not add iron ore.At this moment, CaO/O be 0.935 and λ be-0.078.Consequently, by handling about 7 minutes, [P] in the pig iron melt reduces to 0.019% by 0.108%, and dephosphorization efficient is 0.130 and good.
Comparative example 1
To use diameter be 65 millimeters and have the top-blown spray gun in 6 holes, contain 0.21%[Si before will handling] pig iron melt at 35000Nm
3/ hour the top blowing oxygen gas velocity under, and spray 3600Nm through the two-tube air port of bottom blowing
3/ hour oxygen and 100Nm
3Stir under the condition of/hour LPG.In such cases, Q is 0.00603Nm
3/ second/ton, and the distance between lance head and the molten pig surface is 3750 millimeters.Consequently, the uniform mixing time τ that bottom blowing is stirred is 40 seconds, and the chamber tank depth L that is formed on the molten pig surface by top-blown gas is 124 centimetres, and parameter alpha is 1017.
Blow oxygen about 6 minutes by top-blown spray gun, and add the unslaked lime of 17.5kg/t and the iron ore of 12.8kg/t.At this moment, CaO/O be 0.989 and λ be+0.506.Consequently, by handling about 6 minutes, [P] in the pig iron melt only reduces to 0.042% by 0.110%, and dephosphorization efficient is 0.056 and lower.
Comparative example 2
To use diameter be 65 millimeters and have the top-blown spray gun in 6 holes, contain 0.49%[Si before will handling] pig iron melt at 30000Nm
3/ hour the top blowing oxygen gas velocity under, and spray 3600Nm through the two-tube air port of bottom blowing
3/ hour oxygen and 100Nm
3Stir under the condition of/hour LPG.In such cases, Q is 0.00603Nm
3/ second/ton.And the distance between lance head and the molten pig surface is 3250 millimeters.Consequently, the uniform mixing time τ that bottom blowing is stirred is 40 seconds, and the chamber tank depth L that is formed on the molten pig surface by top-blown gas is 123 centimetres, and parameter alpha is 882.
Blow oxygen about 8 minutes by top-blown spray gun, and add the unslaked lime of 15.5kg/t, but do not add iron ore.At this moment, CaO/O be 0.594 and λ be-0.533.Consequently, frequent generation splash in treating processes, and by handling about 8 minutes, [P] in the pig iron melt only reduces to 0.052% by 0.107%, and dephosphorization efficient is 0.068, and is very low.
Claims (3)
1, a kind of dephosphorizing method of pig iron melt uses lime and ferric oxide and/or oxygen, adopts top blast and bottom-blown converter type reactor, it is characterized in that, adjusting parameter α is 600～1300, and wherein parameter alpha is limited by following formula (1), and it is by top blowing oxygen gas velocity (F; Nm
3/ hour/ton), the uniform mixing time (τ that bottom blowing is stirred; Second), the dark (Lo in pond; Millimeter), and top-blown gas forms the degree of depth (L in pond, chamber on the surface of molten pig; Millimeter) forms; And the basicity of slag is adjusted to 1～2.5, and before processing, with following formula (2) and (3) according to [Si] concentration ([Si] in the pig iron melt; %) the CaO/O of control flux;
α＝(F/60)×τ×Lo/L …(1)
CaO/O＝2.3×[Si]+λ …(2)
λ＝-0.4～+0.4 …(3)。
2, according to the pig iron melt dephosphorizing method of claim 1, it is characterized in that, only use lime and ferric oxide and/or oxygen, perhaps with the SiO of one or more types as dephosphorizing agent
2, Al
2O
3Use with lime and ferric oxide and/or oxygen with the mixture of MgO, and do not use halogenide.
3, according to the pig iron melt dephosphorizing method of claim 1 or 2, it is characterized in that, in the decarburization slag, use CaO instead of part or whole lime.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB011162422A CN100351399C (en) | 2001-02-07 | 2001-02-07 | Method for pig iron melt dephosphorize |
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|---|---|---|---|
| CNB011162422A CN100351399C (en) | 2001-02-07 | 2001-02-07 | Method for pig iron melt dephosphorize |
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| CN100351399C true CN100351399C (en) | 2007-11-28 |
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| KR101251093B1 (en) * | 2006-02-28 | 2013-04-04 | 제이에프이 스틸 가부시키가이샤 | Method of dephosphorization of molten iron |
| WO2018128135A1 (en) * | 2017-01-06 | 2018-07-12 | 新日鐵住金株式会社 | Dephosphorization apparatus and method for dephosphorizing hot metal using dephosphorization apparatus |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1003941B (en) * | 1985-04-26 | 1989-04-19 | 沃斯特-阿尔派因股分公司 | Process for the production of steel from sponge iron and plant for carrying out the process |
| CN1005276B (en) * | 1984-09-22 | 1989-09-27 | 赛森钢股份公司 | Process for refining molten metals |
| WO2000068442A1 (en) * | 1999-05-07 | 2000-11-16 | Sidmar N.V. | Method of decarburisation and dephosphorisation of a molten metal |
-
2001
- 2001-02-07 CN CNB011162422A patent/CN100351399C/en not_active Expired - Fee Related
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1005276B (en) * | 1984-09-22 | 1989-09-27 | 赛森钢股份公司 | Process for refining molten metals |
| CN1003941B (en) * | 1985-04-26 | 1989-04-19 | 沃斯特-阿尔派因股分公司 | Process for the production of steel from sponge iron and plant for carrying out the process |
| WO2000068442A1 (en) * | 1999-05-07 | 2000-11-16 | Sidmar N.V. | Method of decarburisation and dephosphorisation of a molten metal |
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