CN112877496A - Method for realizing efficient dephosphorization in dephosphorization period by controlling phase of slagging process - Google Patents
Method for realizing efficient dephosphorization in dephosphorization period by controlling phase of slagging process Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 84
- 239000007790 solid phase Substances 0.000 claims abstract description 27
- 239000012071 phase Substances 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 12
- 239000007791 liquid phase Substances 0.000 claims abstract description 6
- 239000002893 slag Substances 0.000 claims description 105
- 229910000831 Steel Inorganic materials 0.000 claims description 89
- 239000010959 steel Substances 0.000 claims description 89
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 76
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 61
- 229910052760 oxygen Inorganic materials 0.000 claims description 61
- 239000001301 oxygen Substances 0.000 claims description 61
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 57
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 57
- 239000004571 lime Substances 0.000 claims description 57
- 229910052742 iron Inorganic materials 0.000 claims description 37
- 238000007664 blowing Methods 0.000 claims description 34
- 238000003723 Smelting Methods 0.000 claims description 29
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 claims description 26
- 229910000514 dolomite Inorganic materials 0.000 claims description 6
- 239000010459 dolomite Substances 0.000 claims description 6
- 239000007788 liquid Substances 0.000 claims description 6
- 238000010079 rubber tapping Methods 0.000 claims description 6
- 239000002184 metal Substances 0.000 claims description 3
- 229910052751 metal Inorganic materials 0.000 claims description 3
- 238000005262 decarbonization Methods 0.000 claims description 2
- 239000002994 raw material Substances 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 abstract description 7
- 229910052681 coesite Inorganic materials 0.000 abstract description 4
- 229910052906 cristobalite Inorganic materials 0.000 abstract description 4
- 239000000377 silicon dioxide Substances 0.000 abstract description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 abstract description 4
- 229910052682 stishovite Inorganic materials 0.000 abstract description 4
- 229910052905 tridymite Inorganic materials 0.000 abstract description 4
- 238000009628 steelmaking Methods 0.000 abstract description 3
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 12
- 229910052698 phosphorus Inorganic materials 0.000 description 12
- 239000011574 phosphorus Substances 0.000 description 12
- 230000000694 effects Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 4
- 238000005261 decarburization Methods 0.000 description 4
- 230000014759 maintenance of location Effects 0.000 description 4
- 230000007613 environmental effect Effects 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229910001341 Crude steel Inorganic materials 0.000 description 1
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 1
- -1 and simultaneously Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000004886 process control Methods 0.000 description 1
- 230000033764 rhythmic process Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/36—Processes yielding slags of special composition
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention discloses a method for realizing efficient dephosphorization in a dephosphorization period by controlling a phase of a slagging process, and belongs to the technical field of converter steelmaking. The invention controls the liquid phase (mainly FeO and Ca) in the slagging process3Fe2O5) And a solid phase (mainly 2 CaO. SiO)2，2CaO·SiO2‑3CaO·P2O5) The type and size of (A), and the solid-liquid phase ratio at different times, 2 CaO. SiO2The size of solid phase is less than or equal to 5 mu m, 2CaO SiO2‑3CaO·P2O5The size of the solid phase is less than or equal to 50 mu m. The control method of the invention effectively improves the dephosphorization efficiency in the dephosphorization period, ensures that the dephosphorization time is less than or equal to 5min and the dephosphorization rate is more than or equal to 75 percent, and effectively reduces the addition amount of raw and auxiliary materials and the production cost.
Description
Technical Field
The invention relates to the technical field of converter steelmaking, in particular to a method for realizing efficient dephosphorization in a dephosphorization period by controlling a slagging process phase.
Background
Phosphorus is generally considered to be a harmful element in steel, and causes a series of problems such as "cold shortness" and a sharp decrease in low-temperature toughness of steel. Thus, one of the major efforts in steel making is to remove phosphorus in an economical and efficient manner. In 2018, the yield of crude steel in China is about 9 hundred million tons, the slag generated for dephosphorization is about 9000 million tons (average about 100kg/t steel), more than 4500 million tons of lime is consumed, and the dephosphorization slag is difficult to recycle, so that the problems of resource waste and environmental pollution are caused.
In recent years, with increasingly intense competition among iron and steel enterprises and increasingly important national environmental protection, in order to reduce the production cost and reduce the environmental pollution, the iron and steel enterprises at home and abroad start to adopt a 'double-slag + slag-remaining' smelting process to produce successively, and the process not only can reduce the consumption of raw and auxiliary materials and reduce the production cost, but also can reduce the discharge of slag quantity, and has the advantages of economy and environmental protection. The process divides the traditional converter smelting into two stages, wherein the first stage mainly carries out dephosphorization, slag dumping is carried out after the dephosphorization is finished, then the second stage smelting is carried out, steel is tapped after the smelting is finished, and decarburization slag is recycled to be used in the next furnace, and the key for realizing efficient dephosphorization in the dephosphorization period is the smooth key of the process.
In order to solve the problem of efficient dephosphorization in the dephosphorization period, Chinese patent CN103243192A discloses a converter smelting method for rapidly and efficiently dephosphorizing low-alkalinity dephosphorization slag, which realizes dephosphorization mainly by low lance position, high oxygen supply strength and batch addition of iron ore, but has the following problems (1) that the dephosphorization rate in the dephosphorization period is not high; (2) because of the adoption of low-lance-position large-flow operation, the iron content in the slag is high, and the production cost is increased. Chinese patent CN102618689A discloses a 'process technology method for producing ultra-low phosphorus molten steel by a converter with high efficiency and low cost', the method mainly improves the dephosphorization rate by prolonging the blowing time in the early stage, but the method can reduce the production efficiency.
Therefore, the dephosphorization rate of the existing patent is improved mainly by adjusting an oxygen lance or prolonging the blowing time, and the defects of low dephosphorization efficiency, influence on the production rhythm and the like exist, and further improvement is needed.
Disclosure of Invention
1. Technical problem to be solved by the invention
The invention aims to solve the problem of low dephosphorization rate in the dephosphorization period of the conventional double-slag and residual slag smelting process of a converter, and provides a method for realizing efficient dephosphorization in the dephosphorization period by controlling phases of a slagging process.
2. Technical scheme
In order to achieve the purpose, the technical scheme provided by the invention is as follows:
the invention relates to a method for realizing efficient dephosphorization in a dephosphorization period by controlling a phase of a slagging process, which comprises the following steps:
step a, controlling the amount of slag left in the upper furnace to be 50-80 kg/ton steel;
step b, adding the metal main material, wherein the raw materials comprise 80-91% of molten iron and the balance of scrap steel in percentage by weight;
c, adding iron oxide before blowing in the converter, wherein the adding amount is 20-45kg/t steel;
d, blowing and dephosphorizing by using a converter, wherein the oxygen supply amount in the dephosphorizing period is 22-28% of the total oxygen supply amount of the smelting furnace, the low-lance-position operation is adopted, and the oxygen supply intensity is controlled to be 3.0-3.5 Nm3Per ton of steel/min; the added amount of lime in the dephosphorization period of the converter is w [ Si ] in molten iron in the converter]When the content is less than or equal to 0.4 percent, no lime is added; 0.4% < w [ Si ] in the molten iron]When the lime content is less than or equal to 0.7%, the lime is added in an amount of 3-5 kg per ton of steel; 0.7% < w [ Si ] in the molten iron]In the process, the adding amount of lime is 6-10 kg per ton of steel;
e, pouring slag after the dephosphorization period is finished, and controlling the slag pouring amount to be more than or equal to 60 percent;
f, blowing and decarbonizing the converter, wherein the oxygen supply amount in the decarbonizing period of the converter is the total supply of the smelting furnaceOxygen amount is 72-78%, and oxygen supply intensity is controlled to be 3.0-3.5 Nm3Per ton of steel/min; the adding amount of lime is 10-20 kg/ton steel, and the adding amount of light-burned dolomite is 5-10 kg/ton steel; the binary alkalinity of the converter decarbonization slag is 3.0-4.0; the MgO mass fraction in the furnace slag is 7.0-10.0%;
and g, tapping after the converter blowing is finished, and carrying out slag splashing furnace protection after slag is left.
Preferably, when the total oxygen supply amount of converter blowing dephosphorization is 0-10%, the lime addition amount is controlled to be 10-30%, and the solid phase proportion in the slag is 0-20%; when the oxygen supply amount is 11-17%, the lime addition amount is controlled to be 30-40%, and the solid phase proportion in the slag is 21-32%; when the oxygen supply is more than 17%, the adding amount of lime is controlled to be 40-60%, and the solid phase proportion in the slag is more than 32%.
Preferably, the binary alkalinity of the slag in the converter blowing dephosphorization period is 1.2-1.8, and the slagging process is liquid phase → solid phase; the temperature of the molten pool is 1330-1400 ℃.
Preferably, the liquid phase in the slag in the converter blowing dephosphorization period is mainly FeO and Ca3Fe2O5The solid phase is mainly 2 CaO. SiO2，2CaO·SiO2-3CaO·P2O5。
Preferably, 2 CaO. SiO in the slag in the converter blowing dephosphorization stage2The size of solid phase is less than or equal to 5 mu m, 2CaO SiO2-3CaO·P2O5The size of the solid phase is less than or equal to 50 mu m.
Preferably, the iron oxide in the step c is iron scale, ore or sinter, and the FeO content is more than or equal to 90%.
Preferably, in the blowing dephosphorization period of the converter in the step d, the low lance position is H0+H0*(0.05～0.18)，H0Is the height of the liquid level of the steel in the converter.
3. Advantageous effects
Compared with the prior art, the technical scheme provided by the invention has the following remarkable effects:
(1) the method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process controls each process in the dephosphorization period in the 'double-slag + residual slag' smelting process, controls the type, proportion and size of the phase of the slagging medium in the dephosphorization process by controlling the oxygen supply amount, oxygen supply strength and lime addition amount in the dephosphorization period, effectively improves the dephosphorization efficiency in the dephosphorization period, ensures that the dephosphorization time is less than or equal to 5min and the dephosphorization rate is more than or equal to 75 percent;
(2) the invention relates to a method for realizing efficient dephosphorization in a dephosphorization period by controlling a phase of a slagging process, wherein in the dephosphorization period, a low lance position is adopted for supplying oxygen, and simultaneously, lime with corresponding amount is added according to different silicon contents in molten iron; in addition, during the whole process of adding lime in the dephosphorization period, the adding amount of the lime is controlled according to the injected oxygen supply amount, so that the 2 CaO. SiO in the whole process2Gradually forming, and simultaneously controlling the size of a solid phase in the slag, so that phosphorus in the molten iron can conveniently enter the solid phase, and a good dephosphorization effect is achieved;
(3) the method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process is used for further controlling the generation of solid phase in the slag, controlling the binary alkalinity of the slag in the converter blowing dephosphorization period to be 1.2-1.8, and simultaneously further controlling the temperature of a molten pool to be 1330-1400 ℃, thereby being beneficial to controlling the 2 CaO. SiO. in the slag2，2CaO·SiO2-3CaO·P2O5The generation of the solid phase and the size of the solid phase in the slag are further controlled, so that the dephosphorization time can be effectively shortened, and the dephosphorization effect is improved;
(4) according to the method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process, the lance position is always controlled in the dephosphorization period to be at the low lance position, the whole molten pool can be stirred in the process of injecting oxygen, and the content of FeO in slag can be quickly reduced; at the same time, due to the existence of disturbance, the blown oxygen supply intensity is controlled to a certain degree, so that the generated 2 CaO. SiO2The amount is large, and the size is small, so that the dephosphorization effect is improved.
Drawings
FIG. 1 shows the slag morphology at an oxygen supply of 9% in example 1 of the present invention.
Detailed Description
For a further understanding of the invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings and examples.
Example 1
The method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process is carried out on a 150-ton converter, the experimental process is a smelting process of 'double slag and residual slag', and the method comprises the following specific steps:
(a) after the last furnace finishes converting, controlling the remaining slag and the remaining slag to be 54kg/t steel, and splashing the slag to solidify the slag;
(b) adding scrap steel into the converter, adding molten iron, and controlling the mass percent of the scrap steel: molten iron 90.2% and scrap steel 9.8%, see table 1 specifically;
(c) adding 25kg/t of steel ore before blowing in the converter, wherein the content of FeO is more than or equal to 90 percent;
(d) dephosphorization is carried out by blowing in a converter, the adding amount of lime in the dephosphorization period of the converter is determined according to the condition of molten iron entering the converter, and the adding amount of the lime is 0kg/t steel because w [ Si ] in the molten iron is less than or equal to 0.4 percent, and the specific adding amount is shown in table 2;
the oxygen supply amount in the dephosphorization period is 24 percent of the total oxygen supply amount of the smelting furnace, the liquid level of the molten pool is 1.5m, the lance position is controlled to be 1.65m, and the oxygen supply intensity is controlled to be 3.2Nm3Per ton of steel, controlling the alkalinity in slag to be 1.29;
(e) pouring slag after the dephosphorization period is finished, and controlling the slag pouring amount to be 65%; the slag and molten iron conditions in the dephosphorization stage are shown in Table 3;
(f) the oxygen supply amount in the converter decarburization period is 76 percent of the total oxygen supply amount of the smelting furnace, and the oxygen supply intensity is controlled to be 3.5Nm3The adding amount of lime is controlled to be 18.3kg per ton of steel, and the adding amount of light-burned dolomite is controlled to be 7.5kg per ton of steel; the converter smelting indexes are shown in a table 4;
(g) tapping after the converter blowing is finished, and carrying out slag splashing furnace protection after slag is left.
TABLE 1 converter smelting metal charge conditions
TABLE 2 technological parameters of converter blowing desiliconization and dephosphorization period
TABLE 3 dephosphorization period slag and molten iron conditions
TABLE 4 converter smelting index
It is to be noted that, in this example, the appearance of the slag was observed when the amount of oxygen supplied during the dephosphorization was 9%, and it is seen from FIG. 1 that 2 CaO. SiO was produced2The size of solid phase is less than or equal to 5 mu m, 2CaO SiO2-3CaO·P2O5The size of the solid phase is less than or equal to 50 mu m.
Compared with the process of 'double slag and slag retention' in the comparative example, the process has the advantages that the dephosphorization time is shortened, the lime consumption of the converter, the steel material consumption and the end-point molten steel phosphorus content are reduced, and the dephosphorization rate in the dephosphorization period is greatly improved, wherein the dephosphorization time is shortened by 1min, the lime consumption is reduced by 9 kg/t steel, the dephosphorization rate in the dephosphorization period is improved from 57.69% to 76.15% and is improved by 18.46%, the end-point phosphorus content is reduced by 0.013%, and the steel material consumption is reduced by 4kg/t steel.
Example 2
The method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process is carried out on a 150-ton converter, the experimental process is a smelting process of 'double slag and residual slag', and the method comprises the following specific steps:
(a) after the last furnace finishes converting, controlling the slag remained and remaining slag to be 72kg/t steel, and splashing the slag to solidify the slag;
(b) adding scrap steel into the converter, adding molten iron, and controlling the mass percent of the scrap steel: 85.3 percent of molten iron and 14.7 percent of scrap steel, which are shown in Table 1 specifically;
(c) adding 34kg/t of steel scale before blowing in the converter, wherein the content of FeO is more than or equal to 90 percent;
(d) dephosphorization is carried out by blowing in a converter, the adding amount of lime in the dephosphorization period of the converter is determined according to the condition of molten iron entering the converter, and the adding amount of the lime is 0kg/t steel because w [ Si ] in the molten iron is less than or equal to 0.4 percent, and the specific adding amount is shown in table 2;
the oxygen supply amount in the dephosphorization period is 26 percent of the total oxygen supply amount of the smelting furnace, the liquid level of the molten pool is 1.5m, the lance position is controlled to be 1.69m, and the oxygen supply intensity is controlled to be 3.1Nm3Per ton of steel, controlling the alkalinity in slag to be 1.35;
(e) pouring slag after the dephosphorization period is finished, and controlling the slag pouring amount to be 63%; the slag and molten iron conditions in the dephosphorization stage are shown in Table 3;
(f) the oxygen supply amount in the converter decarburization period is 74 percent of the total oxygen supply amount of the smelting heat, and the oxygen supply intensity is controlled to be 3.5Nm3The adding amount of lime is controlled to be 19.4 kg/ton steel, and the adding amount of light-burned dolomite is controlled to be 7.9 kg/ton steel; the converter smelting indexes are shown in a table 4;
(g) tapping after the converter blowing is finished, and carrying out slag splashing furnace protection after slag is left.
Compared with the process of 'double slag and slag retention' in the comparative example, the process has the advantages that the dephosphorization time is shortened, the lime consumption of the converter, the steel material consumption and the end-point molten steel phosphorus content are reduced, and the dephosphorization rate in the dephosphorization period is greatly improved, wherein the dephosphorization time is shortened by 0.7min, the lime consumption is reduced by 7.9 kg/t steel, the dephosphorization rate in the dephosphorization period is improved from 57.69% to 80.67% and is improved by 22.98%, the end-point phosphorus content is reduced by 0.014%, and the steel material consumption is reduced by 4kg/t steel.
Example 3
The method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process is carried out on a 150-ton converter, the experimental process is a smelting process of 'double slag and residual slag', and the method comprises the following specific steps:
(a) after the last furnace finishes converting, controlling the slag to be 68kg/t steel, and splashing the slag to solidify the slag;
(b) adding scrap steel into the converter, adding molten iron, and controlling the mass percent of the scrap steel: 89.8% of molten iron and 10.2% of scrap steel, and the concrete contents are shown in Table 1;
(c) adding 36kg/t steel sinter before blowing in the converter, wherein the content of FeO is more than or equal to 90 percent;
(d) dephosphorization is carried out by blowing in a converter, the adding amount of lime in the dephosphorization period of the converter is determined according to the condition of molten iron entering the converter, and the adding amount of the lime is preferably 3.5kg/t steel because 0.4 < w [ Si ] in the molten iron of the embodiment is less than or equal to 0.7 percent, and the specific adding amount is shown in Table 2;
the oxygen supply amount in the dephosphorization period is 24 percent of the total oxygen supply amount of the smelting furnace, the liquid level of the molten pool is 1.5m, the lance position is controlled to be 1.70m, and the oxygen supply intensity is controlled to be 3.1Nm3Per ton of steel, controlling the alkalinity in slag to be 1.69;
it is worth to be noted that, the amount of lime added in the dephosphorization period of the embodiment is controlled, and when the oxygen supply amount reaches 9%, the amount of lime added is 1.0kg/t steel; when the oxygen supply amount reaches 15% from 9%, the addition amount of lime is 1.4kg/t steel; when the oxygen supply amount reaches 24 percent from 15 percent, the lime addition amount is 1.1kg/t steel. Researches show that in the whole dephosphorization period, lime is added continuously in stages, and the low lance position, the binary alkalinity, the temperature and the oxygen supply intensity are controlled simultaneously, so that the generated 2CaO & SiO2The amount is gradually increased, and the size is small, thereby improving the dephosphorization effect. If the amount of lime added at each stage is too large, the generated 2 CaO. SiO2The particle size is large, and the dephosphorization effect is reduced.
In addition, researches show that in the process of adding lime in the whole dephosphorization period, when the total oxygen supply amount is 0-10%, the adding amount of the lime is controlled to be 10-30%, and the solid phase proportion in the slag is 0-20%; when the oxygen supply amount is 11-17%, the lime addition amount is controlled to be 30-40%, and the solid phase proportion in the slag is 21-32%; when the oxygen supply is more than 17%, the adding amount of lime is controlled to be 40-60%, the solid phase proportion in the slag is more than 32%, and the obtained dephosphorization effect is better.
(e) Pouring slag after the dephosphorization period is finished, and controlling the slag pouring amount to be 70%; the slag and molten iron conditions in the dephosphorization stage are shown in Table 3;
(f) blowing and decarbonizing in a converter, wherein the oxygen supply amount in the decarbonizing period of the converter is the total number of smelting furnacesThe oxygen supply amount is 76%, and the oxygen supply intensity is controlled to be 3.5Nm3The adding amount of lime is controlled to be 18.0kg per ton of steel, and the adding amount of light-burned dolomite is controlled to be 6.8kg per ton of steel; the converter smelting indexes are shown in a table 4;
(g) tapping after the converter blowing is finished, and carrying out slag splashing furnace protection after slag is left.
Compared with the process of 'double slag and slag retention' in the comparative example, the process has the advantages that the dephosphorization time is shortened, the lime consumption of the converter, the steel material consumption and the end-point molten steel phosphorus content are reduced, and the dephosphorization rate in the dephosphorization period is greatly improved, wherein the dephosphorization time is shortened by 1min, the lime consumption is reduced by 5.8 kg/t steel, the dephosphorization rate in the dephosphorization period is improved from 57.69% to 75.00%, by 17.31%, the end-point phosphorus content is reduced by 0.014%, and the steel material consumption is reduced by 3kg/t steel.
Example 4
The method for realizing efficient dephosphorization in the dephosphorization period by controlling the phase of the slagging process is carried out on a 150-ton converter, the experimental process is a smelting process of 'double slag and residual slag', and the method comprises the following specific steps:
(a) after the last furnace finishes converting, controlling the slag remaining and the slag remaining to be 76kg/t steel, and splashing the slag to solidify the slag;
(b) adding scrap steel into the converter, adding molten iron, and controlling the mass percent of the scrap steel: 80.5 percent of molten iron and 19.5 percent of scrap steel, and is shown in Table 1 specifically;
(c) 42kg/t of steel ore is added before the converter is opened, and the content of FeO is more than or equal to 90 percent;
(d) dephosphorization is carried out by blowing in a converter, the adding amount of lime in the dephosphorization period of the converter is determined according to the condition of molten iron entering the converter, and the adding amount of the lime is preferably 8.4kg/t steel because w [ Si ] in the molten iron of the embodiment is more than 0.7 percent, and the specific adding amount is shown in Table 2;
the oxygen supply amount in the dephosphorization period is 23 percent of the total oxygen supply amount of the smelting furnace, the liquid level of the molten pool is 1.5m, the lance position is controlled to be 1.75m, and the oxygen supply intensity is controlled to be 3.1Nm3Per ton of steel, controlling the alkalinity in slag to be 1.58;
it is worth to be noted that, the amount of lime added in the dephosphorization period of the embodiment is controlled, and when the oxygen supply amount reaches 9%, the amount of lime added is 3.2kg/t steel; when the oxygen supply amount reaches 15% from 9%, the addition amount of lime is 4.0kg/t steel; when the oxygen supply amount reaches 24 percent from 15 percent, the lime addition amount is 1.2kg/t steel.
(e) Pouring slag after the dephosphorization period is finished, and controlling the slag pouring amount to be 68%; the slag and molten iron conditions in the dephosphorization stage are shown in Table 3;
(f) the oxygen supply amount in the converter decarburization period is 77% of the total oxygen supply amount of the smelting furnace, and the oxygen supply intensity is controlled to be 3.5Nm3The adding amount of lime is controlled to be 17.2kg per ton of steel, and the adding amount of light-burned dolomite is controlled to be 6.5kg per ton of steel; the converter smelting indexes are shown in a table 4;
(g) tapping after the converter blowing is finished, and carrying out slag splashing furnace protection after slag is left.
Compared with the process of 'double slag and slag retention' in the comparative example, the process has the advantages that the dephosphorization time is shortened, the lime consumption of the converter, the steel material consumption and the end-point molten steel phosphorus content are reduced, and the dephosphorization rate in the dephosphorization period is greatly improved, wherein the dephosphorization time is shortened by 1.2min, the lime consumption is reduced by 1.7 kg/t steel, the dephosphorization rate in the dephosphorization period is improved from 57.69% to 78.46% and is improved by 18.46%, the end-point phosphorus content is reduced by 0.012%, and the steel material consumption is reduced by 4kg/t steel.
The present invention and its embodiments have been described above schematically, without limitation, and what is shown in the drawings is only one of the embodiments of the present invention, and the actual structure is not limited thereto. Therefore, if the person skilled in the art receives the teaching, without departing from the spirit of the invention, the person skilled in the art shall not inventively design the similar structural modes and embodiments to the technical solution, but shall fall within the scope of the invention.
Claims (7)
1. A method for realizing efficient dephosphorization in a dephosphorization period by controlling a phase of a slagging process is characterized by comprising the following steps:
step a, controlling the amount of slag left in the upper furnace to be 50-80 kg/ton steel;
step b, adding the metal main material, wherein the raw materials comprise 80-91% of molten iron and the balance of scrap steel in percentage by weight;
c, adding iron oxide before blowing in the converter, wherein the adding amount is 20-45kg/t steel;
d, blowing and dephosphorizing by using a converter, wherein the oxygen supply amount in the dephosphorizing period is 22-28% of the total oxygen supply amount of the smelting furnace, the low-lance-position operation is adopted, and the oxygen supply intensity is controlled to be 3.0-3.5 Nm3Per ton of steel/min; the added amount of lime in the dephosphorization period of the converter is w [ Si ] in molten iron in the converter]When the content is less than or equal to 0.4 percent, no lime is added; 0.4% < w [ Si ] in the molten iron]When the lime content is less than or equal to 0.7%, the lime is added in an amount of 3-5 kg per ton of steel; 0.7% < w [ Si ] in the molten iron]In the process, the adding amount of lime is 6-10 kg per ton of steel;
e, pouring slag after the dephosphorization period is finished, and controlling the slag pouring amount to be more than or equal to 60 percent;
f, blowing and decarbonizing in the converter, wherein the oxygen supply amount in the decarbonizing period of the converter is 72-78% of the total oxygen supply amount of the smelting heat, and the oxygen supply intensity is controlled to be 3.0-3.5 Nm3Per ton of steel/min; the adding amount of lime is 10-20 kg/ton steel, and the adding amount of light-burned dolomite is 5-10 kg/ton steel; the binary alkalinity of the converter decarbonization slag is 3.0-4.0; the MgO mass fraction in the furnace slag is 7.0-10.0%;
and g, tapping after the converter blowing is finished, and carrying out slag splashing furnace protection after slag is left.
2. Method for efficient dephosphorization during dephosphorization by controlling the slagging process phase according to claim 1, characterized in that: when the oxygen supply amount for converter blowing dephosphorization is 0-10%, the lime addition amount is controlled to be 10-30%, and the solid phase proportion in the slag is 0-20%; when the oxygen supply amount is 11-17%, the lime addition amount is controlled to be 30-40%, and the solid phase proportion in the slag is 21-32%; when the oxygen supply is more than 17%, the adding amount of lime is controlled to be 40-60%, and the solid phase proportion in the slag is more than 32%.
3. Method for efficient dephosphorization during dephosphorization by controlling the slagging process phase according to claim 2, characterized in that: the binary alkalinity of the converter slag in the blowing dephosphorization period is 1.2-1.8, and the slagging process is liquid phase → solid phase; the temperature of the molten pool is 1330-1400 ℃.
4. The method of claim 3A method for realizing efficient dephosphorization in a dephosphorization period by controlling a phase of a slagging process is characterized by comprising the following steps: the liquid phase in the slag of the converter blowing dephosphorization period is mainly FeO and Ca3Fe2O5The solid phase is mainly 2 CaO. SiO2，2CaO·SiO2-3CaO·P2O5。
5. Method for efficient dephosphorization during dephosphorization by controlling the slagging process phase according to claim 4, characterized in that: 2CaO SiO in slag in converter blowing dephosphorization period2The size of solid phase is less than or equal to 5 mu m, 2CaO SiO2-3CaO·P2O5The size of the solid phase is less than or equal to 50 mu m.
6. Method for efficient dephosphorization during dephosphorization by controlling the slagging process phase according to claim 1, characterized in that: in the step c, the iron oxide is iron scale, ore or sinter, and the FeO content is more than or equal to 90 percent.
7. A method of efficient dephosphorization by dephosphorization phase control in the slagging process according to claim 1, wherein: in the blowing dephosphorization period of the transfer furnace in the step d, the low lance position is H0+H0*(0.05～0.18)，H0Is the height of the liquid level of the steel in the converter.
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| CN116656902A (en) * | 2023-05-31 | 2023-08-29 | 安徽工业大学 | Method for improving dephosphorization capability of converter in earlier stage of converting |
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