CN113073169A - Method for making steel by using dephosphorized steel slag - Google Patents
Method for making steel by using dephosphorized steel slag Download PDFInfo
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- CN113073169A CN113073169A CN202110318811.6A CN202110318811A CN113073169A CN 113073169 A CN113073169 A CN 113073169A CN 202110318811 A CN202110318811 A CN 202110318811A CN 113073169 A CN113073169 A CN 113073169A
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- slag
- steel
- steel slag
- dephosphorized
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- 239000002893 slag Substances 0.000 title claims abstract description 147
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 128
- 239000010959 steel Substances 0.000 title claims abstract description 128
- 238000000034 method Methods 0.000 title claims abstract description 40
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 39
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 37
- 239000011574 phosphorus Substances 0.000 claims abstract description 37
- 238000009628 steelmaking Methods 0.000 claims abstract description 29
- 239000000463 material Substances 0.000 claims abstract description 28
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 57
- 238000007664 blowing Methods 0.000 claims description 39
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 37
- 229910052760 oxygen Inorganic materials 0.000 claims description 37
- 239000001301 oxygen Substances 0.000 claims description 37
- 229910052757 nitrogen Inorganic materials 0.000 claims description 23
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 19
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 15
- 238000010079 rubber tapping Methods 0.000 claims description 15
- 229910001873 dinitrogen Inorganic materials 0.000 claims description 11
- 229910002804 graphite Inorganic materials 0.000 claims description 10
- 239000010439 graphite Substances 0.000 claims description 10
- 229910052742 iron Inorganic materials 0.000 claims description 8
- 239000000126 substance Substances 0.000 claims description 7
- 229910052799 carbon Inorganic materials 0.000 claims description 5
- 230000000694 effects Effects 0.000 abstract description 11
- 238000003723 Smelting Methods 0.000 abstract description 10
- 238000004064 recycling Methods 0.000 abstract description 10
- 230000014759 maintenance of location Effects 0.000 abstract description 6
- 238000009825 accumulation Methods 0.000 abstract description 5
- 229910052751 metal Inorganic materials 0.000 description 18
- 239000002184 metal Substances 0.000 description 18
- 239000007789 gas Substances 0.000 description 9
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 235000011941 Tilia x europaea Nutrition 0.000 description 7
- 239000003795 chemical substances by application Substances 0.000 description 7
- 239000004571 lime Substances 0.000 description 7
- 239000011419 magnesium lime Substances 0.000 description 7
- 239000002131 composite material Substances 0.000 description 6
- 239000011572 manganese Substances 0.000 description 5
- 229910052681 coesite Inorganic materials 0.000 description 4
- 229910052906 cristobalite Inorganic materials 0.000 description 4
- 239000000377 silicon dioxide Substances 0.000 description 4
- 229910052682 stishovite Inorganic materials 0.000 description 4
- 229910052717 sulfur Inorganic materials 0.000 description 4
- 229910052905 tridymite Inorganic materials 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- 239000002253 acid Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 3
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Inorganic materials O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 description 3
- 229910052748 manganese Inorganic materials 0.000 description 3
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 3
- 230000002378 acidificating effect Effects 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000007770 graphite material Substances 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 1
- 241001062472 Stokellia anisodon Species 0.000 description 1
- RHZUVFJBSILHOK-UHFFFAOYSA-N anthracen-1-ylmethanolate Chemical compound C1=CC=C2C=C3C(C[O-])=CC=CC3=CC2=C1 RHZUVFJBSILHOK-UHFFFAOYSA-N 0.000 description 1
- 239000003830 anthracite Substances 0.000 description 1
- 238000009614 chemical analysis method Methods 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000006477 desulfuration reaction Methods 0.000 description 1
- 230000023556 desulfurization Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- SZVJSHCCFOBDDC-UHFFFAOYSA-N iron(II,III) oxide Inorganic materials O=[Fe]O[Fe]O[Fe]=O SZVJSHCCFOBDDC-UHFFFAOYSA-N 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000005272 metallurgy Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- GFNGCDBZVSLSFT-UHFFFAOYSA-N titanium vanadium Chemical compound [Ti].[V] GFNGCDBZVSLSFT-UHFFFAOYSA-N 0.000 description 1
Classifications
-
- 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
- C21C5/36—Processes yielding slags of special composition
-
- 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
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/064—Dephosphorising; Desulfurising
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacturing & Machinery (AREA)
- Carbon Steel Or Casting Steel Manufacturing (AREA)
Abstract
The invention provides a method for making steel by using dephosphorized steel slag, which comprises the following steps: dephosphorizing the steel slag to obtain dephosphorized steel slag; and (4) steel making is carried out by adopting the dephosphorized steel slag. The invention provides a steelmaking method for dephosphorizing and recycling converter steel slag, aiming at the problems of reduction of converter dephosphorization efficiency and increase of auxiliary material consumption caused by continuous accumulation of phosphorus in the steel slag due to the adoption of slag retention operation of a converter. The invention further reduces the consumption of auxiliary materials on the basis of the existing slag remaining operation, improves the dephosphorization efficiency of the converter, can simultaneously relieve the problem of insufficient heat source in semisteel smelting, reduces the TFe content of the final slag, and has the obvious effects of reducing cost and reducing emission.
Description
Technical Field
The invention belongs to the technical field of metallurgy, and particularly relates to a method for making steel by using dephosphorized steel slag, in particular to a steelmaking method for dephosphorizing and recycling converter steel slag for semisteel smelting.
Background
In order to reduce the consumption of auxiliary materials for converter smelting, most converter steelmaking enterprises adopt 'slag retention' operation, and the phosphorus content in steel slag is higher and higher along with the continuous accumulation of the number of slag retention furnaces, so that the dephosphorization efficiency of the converter is reduced. Meanwhile, the Pan steel is smelted by adopting vanadium-titanium magnetite, the main raw material for converter steelmaking is semisteel after vanadium extraction by a special converter, the mass percentage of carbon in the semisteel obtained after desulfurization and vanadium extraction of vanadium-containing molten iron is 3.4-4.0%, and the contents of silicon and manganese heating slagging elements in the semisteel are traces, so that the semisteel smelting has the characteristics of late slagging time, poor dephosphorization effect, insufficient heat and the like. How to make better use of steel slag has become a focus of attention for those skilled in the art.
Disclosure of Invention
In view of the above, the present invention provides a method for making steel by using dephosphorized steel slag, which can remove phosphorus in molten steel, reduce consumption of auxiliary materials for steel making, and reduce discharge amount of steel slag.
The invention provides a method for making steel by using dephosphorized steel slag, which comprises the following steps:
dephosphorizing the steel slag to obtain dephosphorized steel slag;
and (4) steel making is carried out by adopting the dephosphorized steel slag.
Preferably, the method for dephosphorizing the steel slag comprises the following steps:
mixing steel slag and graphite substances, and blowing nitrogen gas from the top and blowing nitrogen gas from the bottom.
Preferably, the phosphorus content of the steel slag is higher than 1.0 wt%.
Preferably, the carbon content in the graphite substance is more than or equal to 90 wt%.
Preferably, the adding amount of the graphite substances is 1-2.5 kg/tSteel slag。
Preferably, the gas supply intensity of the top-blown nitrogen is 2-3 m3/t·min。
Preferably, the air supply intensity of the bottom blowing nitrogen is 0.05-0.15 m3/t·min。
Preferably, the method for steelmaking by using the dephosphorized steel slag comprises the following steps:
mixing the dephosphorized steel slag with semisteel or molten iron, blowing oxygen by an oxygen gun, controlling the alkalinity of the slag, blowing nitrogen from the bottom, pouring phosphorus-rich slag, carrying out secondary slagging and tapping.
Preferably, the alkalinity of the slag is 1.5-2.0.
Preferably, the tapping temperature is 1610-1630 ℃.
The converter steel slag is dephosphorized firstly, and then the dephosphorized steel slag is utilized for steelmaking, so that molten steel phosphorus is removed, the consumption of steelmaking auxiliary materials is reduced, and the discharge amount of the steel slag is reduced. The invention can obviously reduce the consumption of auxiliary materials for steelmaking, improve the dephosphorization effect, reduce the discharge amount of steel slag and has good popularization and application prospects. The invention provides a steelmaking method for dephosphorizing and recycling converter steel slag, aiming at the problems of reduction of converter dephosphorization efficiency and increase of auxiliary material consumption caused by continuous accumulation of phosphorus in the steel slag due to the adoption of slag retention operation of a converter. The invention further reduces the consumption of auxiliary materials on the basis of the existing slag remaining operation, improves the dephosphorization efficiency of the converter, can simultaneously relieve the problem of insufficient heat source in semisteel smelting, reduces the TFe content of the final slag, and has the obvious effects of reducing cost and reducing emission.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other examples, which may be modified or appreciated by those of ordinary skill in the art based on the examples given herein, are intended to be within the scope of the present invention. It should be understood that the embodiments of the present invention are only for illustrating the technical effects of the present invention, and are not intended to limit the scope of the present invention. In the examples, the methods used were all conventional methods unless otherwise specified.
The invention provides a method for making steel by using dephosphorized steel slag, which comprises the following steps:
dephosphorizing the steel slag to obtain dephosphorized steel slag;
and (4) steel making is carried out by adopting the dephosphorized steel slag.
In the present invention, the method of dephosphorizing the steel slag preferably comprises:
mixing steel slag and graphite substances, and blowing nitrogen gas from the top and blowing nitrogen gas from the bottom.
In the invention, the steel slag is preferably converter steel slag; the steel slag is the slag remained in the converter during smelting.
In the present invention, the phosphorus content in the steel slag is preferably higher than 1.0 wt%, more preferably 1.2 to 1.6 wt%, more preferably 1.3 to 1.5 wt%, and most preferably 1.4 wt%.
In the present invention, the steel slag preferably comprises the following components:
CaO：35～45wt％，
SiO2：10～15wt％，
MgO：8～12wt％，
FeO：15～25wt％，
Fe2O3：5～15％，
MnO：1～5％，
P：1.0～1.8wt％，
S：0.6～1.2wt％，
Al2O3：0.5～2.5wt％。
in the invention, the mass content of CaO is preferably 38-42%, and more preferably 40%; the SiO2The mass content of (A) is preferably 11-14%, more preferably 12-13%; the mass content of MgO is preferably 9-11%, and more preferably 10%; the mass content of the FeO is preferably 18-22%, and more preferably 20%; said Fe2O3The mass content of (b) is preferably 8-12%, more preferably 10%; the MnO is preferably 2-4% in mass content, and more preferably 3%; the mass content of the P is preferably 1.2-1.6%, more preferably 1.3-1.5%, and most preferably 1.4%; the mass content of S is preferably 0.8-1%, and more preferably 0.9%; the Al is2O3The content (b) is preferably 1 to 2% by mass, more preferably 1.2 to 1.8% by mass, more preferably 1.4 to 1.6% by mass, and most preferably 1.5% by mass.
In the invention, the carbon content in the graphite material is preferably not less than 90%, more preferably 91-95%, more preferably 92-94%, and most preferably 93%; the graphite material is preferably selected from one or more of graphite, anthracite and coke.
In the invention, the adding amount of the graphite substance is preferably 1-2.5 kg/tSteel slagMore preferably 1.5 to 2kg/tSteel slagMost preferably 1.6 to 1.8kg/tSteel slag。
In the invention, in the dephosphorization process of the steel slag, the top-blown nitrogen is preferably blown by a top-blown oxygen lance. In thatIn the invention, the preferable gas supply strength of top-blown nitrogen in the dephosphorization process of the steel slag is 2-3 m3T.min, more preferably 2.2 to 2.8m3T.min, most preferably 2.4 to 2.6m3T.min; the preferred lance position of the oxygen lance is 0.5-1 m, more preferably 0.6-0.8 m, and most preferably 0.7 m; the time for top-blowing nitrogen is preferably 2 to 4min, more preferably 2.5 to 3.5min, and most preferably 3 min.
In the invention, the preferable air supply intensity of bottom blowing nitrogen in the dephosphorization process of the steel slag is 0.05-0.15 m3T.min, more preferably 0.08 to 0.12m3T min, most preferably 0.1m3/t·min。
In the present invention, the method for dephosphorizing steel slag more preferably comprises the following steps:
after the converter adopts slag remaining operation, when the phosphorus mass content in the steel slag is higher than 1.0 percent, the slag is completely remained after tapping, graphite substances (the carbon content is more than or equal to 90 weight percent) are added into the converter, 1-2.5 kg of steel per ton, nitrogen is blown into the converter by a top-blowing oxygen lance, and the gas supply intensity is 2-3 m3T.min, the position of the oxygen lance is between 0.5 and 1.0 m; bottom blowing nitrogen with the gas supply intensity of 0.05-0.15 m3And (4) t.min, controlling the time of top blowing nitrogen gas to be 2-4 min, and remaining the slag after nitrogen blowing in the furnace for dephosphorization in next furnace for steelmaking.
In the present invention, the method for steelmaking using the dephosphorized steel slag preferably comprises:
mixing the dephosphorized steel slag with semisteel or molten iron, blowing oxygen by an oxygen gun, controlling the alkalinity of the slag, blowing nitrogen from the bottom, pouring phosphorus-rich slag, carrying out secondary slagging and tapping.
In the present invention, the composition of the semisteel preferably includes:
2.5-4 wt% of C;
less than or equal to 0.02 wt% of Si;
mn less than or equal to 0.02 wt%;
0.04-0.09 wt% of P;
0.01 to 0.06 wt% S;
0.02 to 0.06 wt% of V;
the balance being Fe.
In the invention, the mass content of C is preferably 3-3.5%, and more preferably 3%; the mass content of the Si is preferably 0.01-0.02%, and more preferably 0.015%; the mass content of Mn is preferably 0.01-0.02%, and more preferably 0.015%; the mass content of P is preferably 0.05-0.08%, more preferably 0.07-0.08%, and most preferably 0.08%; the mass content of S is preferably 0.02-0.055%, more preferably 0.04-0.055%, and most preferably 0.055%; the mass content of V is preferably 0.03-0.05%, and more preferably 0.04%.
In the invention, the temperature of the semisteel is preferably 1280-1360 ℃, more preferably 1300-1240 ℃, more preferably 1310-1330 ℃, more preferably 1320-1325 ℃, and most preferably 1321 ℃.
In the present invention, the molten iron preferably has the following components:
4-5.5 wt% of C;
0.25 to 0.70 wt% of Si;
0.15 to 0.5 wt% Mn;
0.05 to 0.12 wt% of P;
0.01 to 0.04 wt% S;
the balance being Fe.
In the invention, the mass content of C is preferably 4.5-5%, more preferably 4.55-4.8%, more preferably 4.55-4.6%, and most preferably 4.55%; the mass content of Si is preferably 0.3-0.6%, more preferably 0.35-0.5%, more preferably 0.35-0.4%, and most preferably 0.35%; the mass content of Mn is preferably 0.2-0.4%, more preferably 0.25-0.3%, and most preferably 0.25%; the mass content of the P is preferably 0.06-0.1%, more preferably 0.08-0.09%, and most preferably 0.08%; the mass content of S is preferably 0.015 to 0.03%, more preferably 0.015 to 0.02%, and most preferably 0.015%.
In the invention, the temperature of the molten iron is preferably 1300-1380 ℃, more preferably 1320-1360 ℃, more preferably 1330-1340 ℃, and most preferably 1333 ℃.
In the invention, the consumption of the dephosphorized steel slag is preferably 5-7% of the semi-steel mass, and more preferably 6%; the consumption of the dephosphorized steel slag is preferably 5-7% of the mass of the molten iron, and more preferably 6%.
In the invention, the oxygen supply intensity of oxygen lance oxygen blowing in the steelmaking process is preferably 2-3 m3T.min, more preferably 2.2 to 2.8m3T.min, most preferably 2.4 to 2.6m3/t·min。
In the invention, the alkalinity of the slag is preferably 1.5-2.0, and more preferably 1.6-1.8.
In the invention, the gas supply intensity of bottom-blown nitrogen in the steelmaking process is preferably 0.05-0.15 m3T.min, more preferably 0.08 to 0.12m3T min, most preferably 0.1m3/t·min。
In the invention, the phosphorus-rich slag is poured preferably at 1350-1450 ℃, more preferably 1380-1420 ℃, and most preferably 1400 ℃.
In the invention, an oxygen lance is used for supplying oxygen in the secondary slagging process, nitrogen is blown from the bottom, and active lime, high-magnesium lime and a slagging agent are added while blowing.
In the invention, the oxygen supply intensity of the oxygen lance in the secondary slagging process is preferably 3.0-4.0 m3T.min, more preferably 3.2 to 3.8m3T.min, most preferably 3.4 to 3.6m3T.min; the strength of bottom-blown nitrogen is preferably 0.02-0.05 m3T.min, more preferably 0.03 to 0.04m3/t·min。
In the invention, the adding amount of the active lime is preferably 5-10 kg/tMolten metalMore preferably 6 to 8kg/tMolten metal(ii) a The addition amount of the high-magnesium lime is preferably 5-10 kg/tMolten metalMore preferably 6 to 8kg/tMolten metal(ii) a The preferable addition amount of the slagging agent is 5-10 kg/tMolten metalMore preferably 6 to 8kg/tMolten metal. In the invention, the slagging agent is preferably an acidic composite slagging agent which is a common auxiliary material for semisteel steelmaking, and the main component of the slagging agent is SiO2。
In the present invention, the tapping temperature is preferably 1610 to 1630 ℃, more preferably 1615 to 1625 ℃, and most preferably 1620 DEG C
In the invention, after tapping, the slag is preferably left in the furnace for continuous recycling.
In the present invention, the method for steelmaking using dephosphorized steel slag more preferably comprises:
keeping the steel slag in the furnace after dephosphorization is finished, adding semisteel or molten iron into the furnace, and blowing oxygen by using an oxygen lance, wherein the oxygen supply intensity of the oxygen lance is 2.0-3.0 m3T.min, controlling the alkalinity of the slag to be 1.5-2.0, blowing nitrogen at the bottom, and controlling the gas supply intensity to be 0.05-0.15 m3The phosphorus-rich slag is poured when the temperature is 1350-1450 ℃; secondary slagging is carried out after deslagging, and the oxygen supply intensity of the secondary slagging oxygen lance is 3.0-4.0 m3The air supply intensity of bottom blowing nitrogen is 0.02-0.05 m3At the time of blowing, 5-10 kg/t of active lime is added into the furnaceMolten metal5-10 kg/t of high-magnesium limeMolten metalAnd 5-10 kg/t of acidic composite slagging agentMolten metalAnd tapping when the final temperature reaches 1610-1630 ℃, and keeping the slag in the furnace for continuous recycling after tapping.
The converter steel slag is dephosphorized firstly, and then the dephosphorized steel slag is utilized for steelmaking, so that molten steel phosphorus is removed, the consumption of steelmaking auxiliary materials is reduced, and the discharge amount of the steel slag is reduced. The invention can obviously reduce the consumption of auxiliary materials for steelmaking, improve the dephosphorization effect, reduce the discharge amount of steel slag and has good popularization and application prospects. The invention provides a steelmaking method for dephosphorizing and recycling converter steel slag, aiming at the problems of reduction of converter dephosphorization efficiency and increase of auxiliary material consumption caused by continuous accumulation of phosphorus in the steel slag due to the adoption of slag retention operation of a converter. The invention further reduces the consumption of auxiliary materials on the basis of the existing slag remaining operation, improves the dephosphorization efficiency of the converter, can simultaneously relieve the problem of insufficient heat source in semisteel smelting, reduces the TFe content of the final slag, and has the obvious effects of reducing cost and reducing emission.
The steel slag used in the following examples of the invention comprises the following components: CaO: 40 wt% of SiO2：12wt％，MgO：10wt％，FeO：20wt％，Fe2O3：10wt％，MnO：2wt％，P：1.4wt％，S：0.9wt％，Al2O3: 1.5 wt%; the semisteel comprises the following components: c: 3.5 wt%, Si: 0.02 wt%, Mn: 0.0.2 wt%, V: 0.04 wt%, P: 0.09 wt%, S: 0.036 wt%, the balance being Fe.
Example 1
Smelting 120t converter in a certain plant by using semisteel slag, when the phosphorus content of the end-point steel slag is 1.1 wt%, completely remaining slag after tapping, adding 2kg of graphite ton steel into the converter, blowing nitrogen into the converter by using a top-blowing oxygen lance, and ensuring that the gas supply strength is 2.5m3T.min, the position of the oxygen lance is between 0.5 and 1.0 m; bottom blowing nitrogen with the gas supply intensity of 0.08m3T.min, the time of top blowing nitrogen is 3min, the slag after nitrogen blowing is left in the furnace, the mass of the slag is 6 percent of the semi-steel quality, semi-steel (the phosphorus content is 0.09wt percent) is added into the furnace, oxygen is blown by an oxygen gun, and the oxygen supply intensity of the oxygen gun is 2.5m3T min, controlling the alkalinity of the slag to be 1.6; bottom blowing nitrogen with the gas supply intensity of 0.08m3T min, pouring out the phosphorus-rich slag when the temperature is 1400 ℃; secondary slagging is carried out after deslagging, and the oxygen supply intensity of the secondary slagging oxygen lance is 3.5m3T.min, bottom blowing nitrogen gas supply intensity of 0.05m3At the same time of blowing, 6kg/t of active lime is added into the furnaceMolten metal6kg/t of high-magnesium limeMolten metalAnd acid composite slag former (the main component is SiO)2)5kg/tMolten metalAnd tapping when the end point temperature reaches 1620 ℃, and remaining the slag in the furnace for continuous recycling after tapping.
Detecting the phosphorus content in the steel slag, the phosphorus content in the molten steel and the TFe content in the final slag by adopting a chemical analysis method, and after dephosphorizing the steel slag by adopting the method in the embodiment 1, reducing the phosphorus content of the steel slag from 1.1 wt% to 0.7 wt%, wherein the dephosphorizing rate of the steel slag reaches 36.3%; and simultaneously, the molten steel is dephosphorized by using the steel slag with increased phosphorus capacity after dephosphorization, the phosphorus content in the molten steel is 0.03 wt% during the first deslagging, the dephosphorization rate reaches 66.7%, the phosphorus content in the final molten steel is 0.009 wt% after the second slagging, the dephosphorization rate reaches 90%, the consumption of auxiliary materials (the sum of active lime, high-magnesium lime and a composite slagging agent which are slagging materials and are required to be consumed for smelting each ton of steel in a converter) of steel is only 16kg, and the content of TFe (slag) of the final slag is only 15 wt%.
Comparative example 1
A 120t converter of a certain factory adopts semisteel slag to smelt, when the phosphorus content of the end-point steel slag is 1.1 wt%, the dephosphorization operation is not carried out on the steel slag,after slag is left, semi-steel (the phosphorus content is 0.09wt percent) is directly added into the furnace, the mass of the steel slag is 6 percent of the semi-steel content, oxygen is blown by an oxygen lance, and the oxygen supply intensity of the oxygen lance is 3.5m3T.min, bottom blowing nitrogen, air supply intensity of 0.05m3At the time of blowing, 10kg/t of active lime is added into the furnaceMolten metal10kg/t of high-magnesium limeMolten metalAnd acid composite slag former (the main component is SiO)2)8kg/tMolten metalPouring out the phosphorus-rich slag when the temperature is 1400 ℃; secondary slagging is carried out after deslagging, and the oxygen supply intensity of the secondary slagging oxygen lance is 3.5m3T.min, bottom blowing nitrogen gas supply intensity of 0.05m3At the time of blowing, 8kg/t of active lime is added into the furnaceMolten metal10kg/t of high-magnesium limeMolten metalAnd acid composite slag former (the main component is SiO)2)8kg/tMolten metalAnd tapping when the end point temperature reaches 1620 ℃, and remaining the slag in the furnace for continuous recycling after tapping.
The phosphorus content and the TFe were determined as in example 1.
The method provided by the comparative example 1 has high phosphorus content of the steel slag, insufficient dephosphorization capability of reutilization, poor dephosphorization effect due to excessively short melting time of the materials added at the early stage, phosphorus content of the molten steel during the first deslagging is 0.075 wt%, dephosphorization rate is only 16.7%, phosphorus content of the final molten steel after the second slagging is 0.020 wt%, dephosphorization rate reaches 77.8%, consumption of auxiliary materials per ton of steel reaches 46kg, and TFe content of the final slag reaches 18%.
After the dephosphorization is carried out on the steel slag, the phosphorus content of the steel slag is obviously reduced, and the phosphorus content of the steel slag is improved, so that the steel slag has good dephosphorization effect again. Meanwhile, through optimizing other process parameters, the dephosphorization rate of the molten steel reaches 66.7% under the condition of not adding auxiliary materials after blowing. According to the method provided by the invention, a small amount of auxiliary materials are added during secondary slagging, so that the whole dephosphorization rate is 90%. The consumption of the auxiliary material per ton of steel is only 16kg, the TFe content of the final slag is only 15 percent, and the low-cost recycling of the dephosphorized steel slag is realized. In contrast, in comparative example 1, since the steel slag is not dephosphorized, and the molten steel is dephosphorized again by using the steel slag with high phosphorus content, even if the auxiliary material is added by blowing, the early-stage dephosphorization rate is only 16.7%, the whole-process dephosphorization rate is only 77.8%, the auxiliary material consumption per ton of steel reaches 46kg, and the final slag TFe content reaches 18%. Thus, the present invention has significant technical and cost advantages.
According to the embodiments, the converter steel slag is dephosphorized, and then the dephosphorized steel slag is used for steelmaking, so that molten steel phosphorus is removed, the consumption of steelmaking auxiliary materials is reduced, and the discharge amount of the steel slag is reduced. The invention can obviously reduce the consumption of auxiliary materials for steelmaking, improve the dephosphorization effect, reduce the discharge amount of steel slag and has good popularization and application prospects. The invention provides a steelmaking method for dephosphorizing and recycling converter steel slag, aiming at the problems of reduction of converter dephosphorization efficiency and increase of auxiliary material consumption caused by continuous accumulation of phosphorus in the steel slag due to the adoption of slag retention operation of a converter. The invention further reduces the consumption of auxiliary materials on the basis of the existing slag remaining operation, improves the dephosphorization efficiency of the converter, can simultaneously relieve the problem of insufficient heat source in semisteel smelting, reduces the TFe content of the final slag, and has the obvious effects of reducing cost and reducing emission.
While only the preferred embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
Claims (10)
1. A method for making steel by using dephosphorized steel slag comprises the following steps:
dephosphorizing the steel slag to obtain dephosphorized steel slag;
and (4) steel making is carried out by adopting the dephosphorized steel slag.
2. The method of claim 1, wherein dephosphorizing the steel slag comprises:
mixing steel slag and graphite substances, and blowing nitrogen gas from the top and blowing nitrogen gas from the bottom.
3. A method according to claim 2, characterized in that the phosphorus content of the steel slag is higher than 1.0 wt.%.
4. The method according to claim 2, wherein the carbon content in the graphitic material is 90 wt% or more.
5. The method according to claim 2, wherein the amount of the graphite-based material added is 1 to 2.5kg/tSteel slag。
6. The method according to claim 2, wherein the top-blown nitrogen gas is supplied at an intensity of 2 to 3m3/t·min。
7. The method according to claim 2, wherein the intensity of the bottom-blown nitrogen gas is 0.05 to 0.15m3/t·min。
8. The method of claim 1, wherein the method of steelmaking using dephosphorized steel slag comprises:
mixing the dephosphorized steel slag with semisteel or molten iron, blowing oxygen by an oxygen gun, controlling the alkalinity of the slag, blowing nitrogen from the bottom, pouring phosphorus-rich slag, carrying out secondary slagging and tapping.
9. The method of claim 8, wherein the slag has an alkalinity of 1.5 to 2.0.
10. The method of claim 8, wherein the tapping temperature is 1610 to 1630 ℃.
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