CN116790838A - Method for smelting low-manganese steel by adopting limestone in converter - Google Patents
Method for smelting low-manganese steel by adopting limestone in converter Download PDFInfo
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- CN116790838A CN116790838A CN202310759495.5A CN202310759495A CN116790838A CN 116790838 A CN116790838 A CN 116790838A CN 202310759495 A CN202310759495 A CN 202310759495A CN 116790838 A CN116790838 A CN 116790838A
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- converter
- slag
- limestone
- steel
- manganese
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- 235000019738 Limestone Nutrition 0.000 title claims abstract description 39
- 239000006028 limestone Substances 0.000 title claims abstract description 39
- 229910000617 Mangalloy Inorganic materials 0.000 title claims abstract description 27
- 238000000034 method Methods 0.000 title claims abstract description 27
- 238000003723 Smelting Methods 0.000 title claims abstract description 23
- 239000011572 manganese Substances 0.000 claims abstract description 48
- 239000002893 slag Substances 0.000 claims abstract description 39
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 32
- 239000010959 steel Substances 0.000 claims abstract description 32
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 29
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 20
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 20
- 239000004571 lime Substances 0.000 claims abstract description 20
- 230000001590 oxidative effect Effects 0.000 claims abstract description 13
- 230000008569 process Effects 0.000 claims abstract description 8
- 238000003756 stirring Methods 0.000 claims abstract description 8
- 239000002245 particle Substances 0.000 claims abstract description 5
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 51
- 229910052742 iron Inorganic materials 0.000 claims description 25
- 238000007599 discharging Methods 0.000 claims description 11
- 238000007664 blowing Methods 0.000 claims description 9
- 238000000354 decomposition reaction Methods 0.000 claims description 8
- 239000010459 dolomite Substances 0.000 claims description 6
- 229910000514 dolomite Inorganic materials 0.000 claims description 6
- 239000002994 raw material Substances 0.000 claims description 4
- 230000009467 reduction Effects 0.000 claims description 4
- 238000013019 agitation Methods 0.000 claims description 3
- 238000010079 rubber tapping Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 claims 1
- 238000007254 oxidation reaction Methods 0.000 abstract description 10
- 238000006243 chemical reaction Methods 0.000 abstract description 9
- 230000003647 oxidation Effects 0.000 abstract description 7
- 238000005187 foaming Methods 0.000 abstract description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 abstract 1
- 239000007789 gas Substances 0.000 abstract 1
- 238000002844 melting Methods 0.000 abstract 1
- 230000008018 melting Effects 0.000 abstract 1
- 239000001301 oxygen Substances 0.000 abstract 1
- 229910052760 oxygen Inorganic materials 0.000 abstract 1
- 230000000052 comparative effect Effects 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 5
- 238000009628 steelmaking Methods 0.000 description 4
- 230000007423 decrease Effects 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 230000006698 induction Effects 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 238000005275 alloying Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000002826 coolant Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 229910001004 magnetic alloy Inorganic materials 0.000 description 1
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- 239000002436 steel type Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
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- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention discloses a method for smelting low manganese steel by adopting limestone in a converter, which reduces the temperature, improves the oxidizing capacity of slag and reduces the alkalinity according to the chemical reaction of manganese between slag steel in the converter and the balance distribution principle between slag and steel, and can promote the oxidation of manganese in molten steel; the limestone enters the converter and then is calcined to generate a large amount of CO 2 The temperature in the converter is higher, and the gas expands for tens of times rapidly, so that the foaming degree of slag in the converter is improved rapidly, and the surface area of the reaction between lime and slag is increased; CO produced 2 Can generate microscopic stirring to the local molten pool around the limestone particles, and improve the reaction dynamics condition of the molten pool. The method fully utilizes the oxygen of manganese element in the converterThe thermodynamic condition of melting and the reaction characteristic of limestone at high temperature in a converter, the temperature, the oxidizing property and the stirring intensity of the molten steel smelting process are controlled by adopting limestone, the manganese element in the steel is removed to the greatest extent, and the manganese content of the low manganese steel is controlled below 0.02 percent.
Description
Technical Field
The invention belongs to the technical field of steelmaking, and relates to a smelting method of low-manganese steel, in particular to a method for smelting low-manganese steel by adopting limestone in a converter.
Background
Manganese is one of the most common elements in steel materials, and in general steel, manganese is a beneficial element, which can improve the strength of steel, reduce brittleness, and reduce sulfur hazard. However, in some steel grades, manganese is no longer a beneficial alloying element, but rather the lower the mass fraction of manganese in the steel, the better. In these steel types, as the mass fraction of manganese increases, the electrical conductivity of the steel decreases sharply, the electrical resistivity increases correspondingly, the temperature coefficient of resistance decreases, the coercive force of the steel increases, and the saturation magnetic induction, the residual magnetic induction and the magnetic permeability decrease, so that manganese is a detrimental element to the soft magnetic alloy, and it is desirable to control the element content in the steel to a low level. In conventional steelmaking processes, it is very difficult to obtain low levels of manganese, especially less than or equal to 0.02%, in the molten steel.
Disclosure of Invention
In order to overcome the defects in the prior art, the invention fully utilizes the thermodynamic conditions of oxidizing manganese in the converter, adopts limestone to control the temperature and the oxidizing property of the molten steel smelting process, removes the manganese in the steel to the greatest extent, and stably controls the manganese content of the low manganese steel to be below 0.02 percent.
Principle of manganese oxidation in steel: from the chemical reaction of manganese between slag steels in a converter and the equilibrium distribution constants between slag-steels, it can be derived that:
oxidation reaction of manganese: mn++ (FeO) = (MnO) + [ Fe ]
Equilibrium constant of manganese between slag steels:
from the above equation, it can be derived that:
from the above L Mn It can be seen that lowering the temperature (increasing K), increasing the oxidizing power of slag, and lowering the gamma MnO (lowering the alkalinity) promotes the oxidation of manganese in the molten steel. In the steelmaking process, manganese is secondary to silicon, and is largely oxidized at the beginning of smelting, but when the temperature is high in the later period of smelting, K is reduced, and the oxidation of manganese tends to be balanced. Meanwhile, the (FeO) amount in the slag is reduced due to the strong oxidization of carbon, so that the reduction of MnO can occur, and a certain residual manganese exists in the molten steel.
At present, the main purpose of the converter using limestone for slagging is that a large amount of heat is consumed in the calcination process after the limestone enters the converter, so that the consumption of coolants such as iron ores, scrap steel and the like can be reduced. In addition, the cost of the limestone is far lower than that of active lime, so that the raw material cost can be saved, and the economic benefit is increased. However, the smelting of low-manganese steel by fully utilizing the principle of oxidizing manganese element in steel and matching with the beneficial effect of limestone slagging has not been studied yet.
A method for smelting low manganese steel by adopting limestone in a converter comprises the following technical scheme:
(1) when smelting low manganese steel, the mass content of Mn element in the raw material molten iron is less than or equal to 0.15 percent.
(2) Before iron charging, 8-15kg/t of lime and 10-15kg/t of ore (or sintered return ore) are added into the converter for padding; when the low-manganese steel is produced, the previous heat is also carried out according to the process, and steel containers such as a converter and the like are cleaned, so that the demanganization rate is improved.
(3) When low manganese steel is produced, the furnace body is turned to 180 degrees when the previous furnace is used for deslagging, residues in the furnace are discharged, and the slag-retaining operation is not allowed.
(4) Controlling the dolomite in the earlier stage of converter smelting to be less than or equal to 10kg/t, blowing for 1-5min in the earlier stage of converter smelting, and adding 1/3 of the total amount of lime in 4-5 batches; when the double-slag discharging time point of the converter is controlled to be 5+/-1 min in converting, the oxidability is improved, the fluidity of slag is ensured, slag is discharged as much as possible, and the slag pouring amount is controlled to be more than 2/3; the total amount of lime comprises lime added before iron charging.
(5) 2min before the double slag discharging time of the converter, according to the temperature condition of molten iron and the Mn content required by the end point of low manganese steel, 5-20kg/t of limestone is added into the converter in batches, and the operations of reducing temperature, improving oxidizing property and increasing stirring intensity are performed to remove Mn element in the molten iron.
(6) Blowing for 5+/-1 min to discharge slag, measuring the temperature during the 1 st slag discharge, and taking a steel sample and detecting the slag sample; and observing by special people during slag discharge, and discharging slag as much as possible under the condition of ensuring no tapping.
Further, the cooling in the step (5) is the reduction of the temperature of molten iron caused by the endothermic decomposition of limestone; the oxidation is improved by CO generated by the endothermic decomposition of limestone 2 Is an oxidizing gas and reacts with Mn element in molten iron in an oxidizing way; the stirring strength is increased by CO generated by the endothermic decomposition of limestone 2 Microscopic agitation of the localized bath around the limestone particles.
Further, the method controls the manganese content of the low manganese steel to be below 0.02%.
The principle of limestone slagging and demanganization used in the converter is as follows:
the high-temperature calcination reaction of limestone in the converter is as follows: caCO (CaCO) 3 →CaO+CO 2 ；
The limestone endothermic decomposition can cause the temperature of molten iron near limestone particles to be reduced, and also can reduce the rate of increasing the temperature of molten iron in the converter, prolong the low-temperature time of the molten iron and be beneficial to early and rapid demanganization of the converter.
CO generated by endothermic decomposition of limestone in the initial stage of converter steelmaking blowing 2 Is oxidizing gas, can perform oxidation reaction with Mn element in molten iron, and reduces the manganese content in molten steel.
CO 2 +[Mn]→CO+MnO
The limestone enters the converter and then is calcined to generate a large amount of CO 2 The gas has higher temperature in the converter, and the gas expands for tens of times rapidly, so that the foaming degree of slag in the converter is improved rapidly, and the slag in the converter is provided withThe surface area of the reaction of lime and slag is increased. CO produced 2 Can generate microscopic stirring to the local molten pool around the limestone particles, and improve the reaction dynamics condition of the molten pool.
Compared with the prior art, the invention has the beneficial effects that:
the thermodynamic conditions of oxidation of manganese element in the converter and the reaction characteristics of limestone at high temperature in the converter are fully utilized, the temperature, the oxidability and the stirring intensity of the molten steel smelting process are controlled by adopting the limestone, the manganese element in the steel is removed to the greatest extent, and the manganese content of the low manganese steel is controlled below 0.02 percent.
Detailed Description
The invention is further illustrated below in connection with specific examples, but is not limited in any way. For the sake of brevity, the raw materials in the following examples are all commercially available products unless otherwise specified, and the methods used are all conventional methods unless otherwise specified.
Example 1
A method for smelting low manganese steel by adopting limestone in a converter fully utilizes thermodynamic conditions of oxidation of manganese element in the converter, adopts limestone to control temperature, oxidability and stirring intensity in the molten steel smelting process, and removes manganese element in steel to the greatest extent, and stably controls manganese content of the low manganese steel to be below 0.02%; the method comprises the following technical scheme:
(1) when smelting low manganese steel, the mass content of molten iron [ Mn ] is 0.12%;
(2) before iron charging, adding lime 2t and ore 2.5t into a converter according to the proportion of lime 12kg/t and ore 15kg/t, wherein the tapping amount is 170 t; the previous heat is also carried out according to the process, so that the demanganization rate is improved;
(3) when the previous furnace is used for deslagging, the furnace body is turned to 180 degrees, residues in the furnace are cleaned, and no residue is left;
(4) the addition amount of the early dolomite is 1.4t according to the proportion of 8kg/t, the blowing is carried out for 1-5min, and 4 tons of lime are added for four times;
(5) converting for 2.5min in a converter, and adding 2.5 tons of limestone in two batches according to the proportion of 15 kg/t;
(6) the double-slag discharging time of the converter is 4.5min, the slag pouring amount is about 2/3, and special people observe the double-slag discharging time to discharge slag as much as possible.
According to the control of the technical proposal, the manganese content at the end point of the converter is 0.0097 percent; the other component contents are shown in Table 1.
TABLE 1 other component contents of Low manganese Steel smelted in EXAMPLE 1
| C％ | Si％ | Mn％ | P％ | S％ |
| 0.016 | 0.003 | 0.0097 | 0.0021 | 0.004 |
Example 2
A method for smelting low manganese steel by adopting limestone in a converter comprises the following technical scheme:
(1) 0.15% of molten iron [ Mn ] by mass;
(2) before iron charging, lime 2.0t and sintered return ore 2.3t are added into the converter for padding;
(3) when the previous furnace is used for deslagging, the furnace body is turned to 180 degrees, residues in the furnace are cleaned, and no residue is left;
(4) the adding amount of the early dolomite is 1.5t, and 4 tons of lime are added for three times in blowing for 1-5 min;
(5) blowing in a converter for 3.5min, and adding 2 tons of limestone twice;
(6) the double-slag discharging time of the converter is 5min, the slag pouring amount is about 2/3, and special people observe the double-slag discharging time to discharge slag as much as possible.
According to the control of the technical proposal, the manganese content at the end point of the converter is 0.012 percent; the other component contents are shown in Table 2.
TABLE 2 other component contents of low manganese steel smelted in EXAMPLE 2
| C％ | Si％ | Mn％ | P％ | S％ |
| 0.018 | 0.002 | 0.012 | 0.0016 | 0.0032 |
Comparative example 1
1) 0.12% of molten iron [ Mn ] by mass;
2) The adding amount of the early dolomite is 3t, and 5 tons of lime are added for four times in 1-5min of blowing;
3) Blowing for 7min, and adding 1 ton of lime;
the manganese content at the end point of the converter in comparative example 1 is 0.068%; the other component contents are shown in Table 3.
TABLE 3 other component contents of low manganese steel smelted in comparative example 1
| C％ | Si％ | Mn％ | P％ | S％ |
| 0.039 | 0.001 | 0.068 | 0.0092 | 0.0089 |
Comparative example 2
1) 0.15% of molten iron [ Mn ] by mass;
2) Adding the early dolomite for 4t, converting for 1-5min, and adding 6 tons of lime three times;
3) Converting for 8min by a converter, and adding lime for 2 tons twice;
the converter endpoint manganese content of comparative example 1 was 0.093%; the other component contents are shown in Table 4.
TABLE 4 other component contents of low manganese steel smelted in comparative example 2
| C％ | Si％ | Mn％ | P％ | S％ |
| 0.053 | 0.001 | 0.093 | 0.0089 | 0.0093 |
Many possible variations and modifications of the disclosed technology can be made by anyone skilled in the art without departing from the scope of the technology, or the technology can be modified to be equivalent. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims (6)
1. A method for smelting low manganese steel by adopting limestone in a converter is characterized by comprising the following technical scheme:
(1) when smelting low manganese steel, the mass content of Mn element in raw material molten iron is less than or equal to 0.15 percent;
(2) before iron charging, 8-15kg/t of lime and 10-15kg/t of ore or sintered return ore are added into the converter for padding; the previous heat is also carried out according to the process;
(3) when the previous furnace is used for deslagging, the furnace body is turned to 180 degrees, residues in the furnace are cleaned, and the operation of residue remaining is not allowed;
(4) controlling the dolomite in the earlier stage of converter smelting to be less than or equal to 10kg/t, blowing for 1-5min in the earlier stage of converter smelting, and adding 1/3 of the total amount of lime in 4-5 batches; controlling the slag discharging time point of the double slag of the converter to be 5+/-1 min; discharging slag as much as possible, and controlling the slag pouring quantity to be more than 2/3;
(5) 2 minutes before the double slag discharging time of the converter, according to the temperature condition of molten iron and the Mn element content required by the end point of low manganese steel, limestone is added into the converter in batches of 5-20kg/t, and the operations of reducing temperature, improving oxidizing property and increasing stirring intensity are performed to remove Mn element in the molten iron;
(6) measuring the temperature during the 1 st slag discharge, and taking a steel sample and a slag sample for detection; and observing by special people during slag discharge, and discharging more slag under the condition of ensuring no tapping.
2. The method of claim 1, wherein the total amount of lime in step (4) comprises lime added prior to iron charging.
3. The method of claim 1, wherein the temperature reduction in step (5) is a reduction in the temperature of molten iron caused by endothermic decomposition of limestone.
4. The method of claim 1, wherein the oxidizing enhancement in step (5) is CO from endothermic decomposition of limestone 2 Is an oxidizing gas and reacts with Mn element in molten iron.
5. The method of claim 1, wherein the increasing agitation intensity in step (5) is CO produced by endothermic decomposition of limestone 2 Microscopic agitation of the localized bath around the limestone particles.
6. The method of claim 1, wherein the method controls the manganese content of the low manganese steel to be less than 0.02%.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310759495.5A CN116790838A (en) | 2023-06-26 | 2023-06-26 | Method for smelting low-manganese steel by adopting limestone in converter |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310759495.5A CN116790838A (en) | 2023-06-26 | 2023-06-26 | Method for smelting low-manganese steel by adopting limestone in converter |
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| Publication Number | Publication Date |
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| CN116790838A true CN116790838A (en) | 2023-09-22 |
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| CN202310759495.5A Pending CN116790838A (en) | 2023-06-26 | 2023-06-26 | Method for smelting low-manganese steel by adopting limestone in converter |
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- 2023-06-26 CN CN202310759495.5A patent/CN116790838A/en active Pending
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