A steelmaking method for rapidly slagging a converter under high iron consumption and reducing comprehensive lime consumption

Abstract

The invention discloses a steelmaking method for reducing comprehensive lime consumption by rapidly slagging a converter under high iron consumption, which belongs to the technical field of converter steelmaking and solves the technical problem of realizing converter slag-less smelting and improving the cleanliness level of molten steel under high iron consumption conditions. The steelmaking method of the invention comprises the following steps: S1, slag splashing and furnace protection; S2, adding limestone and sintered ore as bottom material; S3, adding molten iron and scrap steel into the converter; S4, adding lime, sintered ore and magnesium balls in batches when blowing 0min≤BT≤6min; S5, adding sintered ore to control the temperature of molten steel when blowing 6min<BT≤10min; S6, adding sintered ore to control the temperature of molten steel when blowing 10min<BT; S7, performing high oxygen pressure and low lance position oxygen lance operation for 40 to 60 seconds; S8, pouring the furnace to tap steel, and blocking slag at the end of tapping steel. By using the method of the present invention, the slag basicity is between 1.8 and 2.3 after 6 minutes of converter blowing, the dephosphorization rate is between 40 and 60%, and the dephosphorization effect in the early stage of the converter is remarkable.

Description

Technical Field

[0001] The invention belongs to the technical field of converter steelmaking, and in particular relates to a steelmaking method for rapidly slagging a converter under high iron consumption and reducing comprehensive lime consumption. Background Art

[0002] Like other substances, the cleanliness of steel is also an important indicator of steel. Improving the purity of steel and improving its performance are important technical directions for the development of steel production. Further reducing the production cost of pure steel and improving the stability and efficiency of pure steel production are the historical trends in the development of steelmaking technology.

[0003] Clean steel does not refer to a specific type of steel, but represents the process level that can be achieved by controlling the cleanliness of molten steel in the actual production process. It reflects the specific production process and manufacturing level of clean steel. The traditional steelmaking process is a low-efficiency, high-energy consumption, and high-pollution production system. For example, the slag-steel reaction efficiency is low, the slag volume is large; the production rhythm is slow, the auxiliary time is long, the heat loss of steelmaking is large; the molten steel is severely oxidized, etc., all of which lead to a sharp increase in inclusions in the steel, reduced efficiency, and increased costs.

[0004] Therefore, how to improve the slag-steel reaction efficiency, reduce the slag volume, reduce heat loss in the steelmaking process, and prevent overoxidation of molten steel are important issues facing clean steel production. Summary of the invention

[0005] In view of the above analysis, the present invention provides a steelmaking method for rapidly slagging a converter under high iron consumption and reducing comprehensive lime consumption, so as to solve the technical problem of how to use surplus heat to achieve converter slag-less smelting and improve the cleanliness level of molten steel under high iron consumption conditions with a small amount of scrap steel added and a surplus molten iron temperature. The present invention can solve at least one of the following technical problems: (1) Under high iron consumption conditions, a large amount of lime is added, and the slagging speed of the converter is slow; (2) Under high iron consumption conditions, the decarburization speed is accelerated, which affects the dephosphorization effect at the end of the converter; (3) The degree of carbon-oxygen reaction at the end of the converter is far from equilibrium and is not closer to equilibrium, resulting in serious overoxidation of the molten steel.

[0006] The purpose of the present invention is mainly achieved through the following technical solutions:

[0007] The present invention provides a steelmaking method for rapidly slagging a converter and reducing comprehensive lime consumption under high iron consumption, comprising the following steps:

[0008] S1, leaving the slag after the previous furnace is tapped in the converter to perform slag splashing and furnace protection operation;

[0009] S2. According to the weight of the molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the base material, and the mass percentage of the molten iron is Mn < 1.2%, Si < 1.2%, 0.1% < P < 0.15%, 0.002% < S < 0.035%;

[0010] S3, adding the molten iron and scrap steel in S2 into the converter, the weight ratio of scrap steel to molten iron ≤ 5%; the temperature of the molten iron ≥ 1240°C;

[0011] S4, when blowing 0min≤BT≤6min, according to the Si content in the molten iron added to the converter in S3, lime, sintered ore and magnesium balls are added in batches, wherein the total weight of the sintered ore is equal to the total weight of the sintered ore added in S2, the oxygen flow rate of the oxygen lance is controlled to be the lower limit of the designed oxygen pressure, and the bottom blowing gas supply intensity is 0.05~0.08Nm 3 / t·min;

[0012] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel, control the oxygen flow rate of oxygen lance to exceed the designed oxygen pressure by 5%, and the bottom blowing gas supply intensity is 0.04~0.06Nm 3 / t·min;

[0013] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel, control the oxygen flow rate of oxygen lance to exceed the designed oxygen pressure by 10%, and the bottom blowing gas supply intensity is 0.04~0.06Nm 3 / t·min;

[0014] S7, at the end of smelting, high oxygen pressure and low lance position oxygen lance operation is performed for 40 to 60 seconds;

[0015] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0016] Furthermore, in S1, when the tapping temperature of the previous furnace is above 1670°C, or the molten steel is overoxidized, 1 / 2 of the slag of the furnace is retained.

[0017] Further, when the molten iron in S2 has Mn < 0.6% and Si < 0.20%, in S2:

[0018] Limestone addition amount: M 石灰石 =0.0108M 铁水 +0.0694,

[0019] Sintered ore addition amount: M 烧结矿 =0.00815M 铁水 +0.0487;

[0020] When the molten iron Mn in S2 is less than 0.6%, 0.2%≤Si<0.5%, in S2:

[0021] Limestone addition amount: M 石灰石 =(0.0161~0.0267)M 铁水 +(0.1165~0.1969),

[0022] Sintered ore addition amount: M 烧结矿 =(0.01085~0.01355)M 铁水 +(0.06625~0.08255);

[0023] When the molten iron in S2 has Mn<0.6%, 0.5%≤Si≤0.8%, in S2:

[0024] Limestone addition amount: M 石灰石 =(0.0457~0.0571)M 铁水 +(0.548~0.8898),

[0025] Sintered ore addition amount: M 烧结矿 =0.01625M 铁水 +0.1010;

[0026] When the molten iron in S2 has Mn<0.6%, 0.8%<Si≤1.2%, in S2:

[0027] Limestone addition amount: M 石灰石 =(0.0611~0.0663)M 铁水 +(0.2351~0.3047),

[0028] Sintered ore addition amount: M 烧结矿 =0.01375M 铁水 +0.06095;

[0029] Among them, M 石灰石 is the weight of limestone added, M 烧结矿 is the added weight of sintered ore, M 铁水 The weight of molten iron added to the converter.

[0030] Furthermore, when the molten iron in S2 is 0.6%≤Mn<1.2%, Si<0.20%, in S2:

[0031] Limestone addition amount: M 石灰石 =0.0108M 铁水 +0.0694+(0.5~1.0),

[0032] Sintered ore addition amount: M 烧结矿 =0.00815M铁水 +0.0487;

[0033] When the molten iron in S2 is 0.6%≤Mn<1.2%, 0.2%≤Si<0.5%, in S2:

[0034] Limestone addition amount: M 石灰石 =(0.0161~0.0267)M 铁水 +(0.1165~0.1969)+(0.5~1.0),

[0035] Sintered ore addition amount: M 烧结矿 =(0.01085~0.01355)M 铁水 +(0.06625~0.08255);

[0036] When the molten iron in S2 is 0.6%≤Mn<1.2%, 0.5%≤Si≤0.8%, in S2:

[0037] Limestone addition amount: M 石灰石 =(0.0457~0.0571)M 铁水 +(0.548~0.8898)+(0.5~1.0),

[0038] Sintered ore addition amount: M 烧结矿 =0.01625M 铁水 +0.1010;

[0039] When the molten iron in S2 is 0.6%≤Mn<1.2%, 0.8%<Si≤1.2%, in S2:

[0040] Limestone addition amount: M 石灰石 =(0.0611~0.0663)M 铁水 +(0.2351~0.3047)+(0.5~1.0),

[0041] Sintered ore addition amount: M 烧结矿 =0.01375M 铁水 +0.06095;

[0042] Among them, M 石灰石 is the weight of limestone added, M 烧结矿 is the added weight of sintered ore, M 铁水 The weight of molten iron added to the converter.

[0043] Furthermore, in S2, the limestone has a CaO content of 52-55% by mass.

[0044] Furthermore, when the Si content of molten iron in S2 is less than 0.20%, in S4:

[0045] Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694,

[0046] Amount of magnesium ball added: M 镁球 =0.0043M 铁水 +0.0273;

[0047] When the molten iron in S2 is 0.2%≤Si<0.5%, in S4:

[0048] Lime addition amount: M 石灰 =0.0163M 铁水 +0.0974,

[0049] Amount of magnesium ball added: M 镁球 =(0.0066~0.011)M 铁水 +(0.0271~0.0503);

[0050] When the molten iron in S2 is 0.5%≤Si≤0.8%, in S4:

[0051] Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694,

[0052] Amount of magnesium ball added: M 镁球 =(0.0123~0.0133)M 铁水 +(0.0187~0.0249);

[0053] When the molten iron in S2 is 0.8%<Si≤1.2%, in S4:

[0054] Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694,

[0055] Amount of magnesium ball added: M 镁球 =0.0108M 铁水 +0.0694;

[0056] M 石灰 is the weight of lime added, M 镁球 is the weight of magnesium balls added, M 铁水 The weight of molten iron added to the converter.

[0057] Furthermore, the sintered ore has the following mass percentage contents: TFe≥54%, FeO<10%, 9%<CaO<13%, 5.5%<SiO 2 <8%, basicity R=CaO / SiO 2 ≥1.6, S<0.04%.

[0058] Furthermore, in S4, the slag basicity after 6 minutes of converter blowing is between 1.8 and 2.3.

[0059] Furthermore, when the Mn of the molten iron in S2 is less than 0.6%, the oxygen lance position is controlled at 1.8-2.4 m in S4, at 0.9-1.2 m in S5, and at 1.2-1.6 m in S6.

[0060] Furthermore, when the molten iron in S2 is 0.6%≤Mn<1.2%, the oxygen lances in S4, S5 and S6 are operated at a constant lance position of 1.2 to 1.8 meters.

[0061] Compared with the prior art, the present invention has the following beneficial effects:

[0062] (1) The present invention adopts the operation of retaining slag in the converter and splashing slag to protect the converter, which is conducive to the early formation of initial slag, and can improve the efficiency of removing P and S in the early stage of smelting, which is conducive to protecting the furnace lining and saving the amount of lime.

[0063] (2) The present invention not only prevents the splashing of molten iron caused by slag retention, but also reduces the temperature of molten iron by adding limestone and sintered ore as the bed material before adding molten iron to the converter. The limestone in the bed material is decomposed into calcium oxide and combined with the sintered ore to form low-melting-point calcium ferrite slag, which promotes the melting of the early slag of the converter. Compared with the traditional method of adding slag in the early stage of the converter, the formation of the early slag of the converter can be advanced by 3 to 4 minutes by adopting this method.

[0064] (3) The present invention achieves the purpose of forming calcium ferrite slag as soon as possible by adding converter lime and sintered ore at the early stage of blowing. The slag basicity is between 1.8 and 2.3 after 6 minutes of converter blowing, and the dephosphorization rate is between 40 and 60%, and the dephosphorization effect in the early stage of the converter is remarkable.

[0065] (4) The present invention uses FeO and Fe contained in sintered ore to 2 O 3 、SiO 2 , CaO, MgO and Al 2 O 3 It can quickly form slag and establish a slag balance, which is beneficial to early dephosphorization, save lime and protect the furnace lining.

[0066] (5) The final P and S contents of the present invention are within a controllable range, the carbon content of the steel is controlled at above 0.07%, the carbon-oxygen reaction reaches a balance, and the overoxidation of the molten steel is effectively reduced.

[0067] (6) The method provided by the present invention can save more than 30% of the comprehensive lime on average, thus achieving better economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0068] Figure 1 CaO-FeO x binary phase diagram;

[0069] Figure 2 CaO-Fe 2 O 3 Binary phase diagram. DETAILED DESCRIPTION

[0070] The following is a further detailed description of a steelmaking method for rapidly slagging a converter under high iron consumption and reducing comprehensive lime consumption in conjunction with specific embodiments. These embodiments are only for the purpose of explanation, and the present invention is not limited to these embodiments. It should be noted that the component contents in the present invention are all mass percentages.

[0071] A large amount of production practice has shown that in order to achieve low-slag smelting in the converter and improve the cleanliness level of molten steel, the following conditions are required. First, good slag treatment in the early stage of the converter is a prerequisite; secondly, the carbon-oxygen reaction at the end of the converter is closer to equilibrium, which reduces the tendency of molten steel to overoxidation.

[0072] The present invention provides a steelmaking method for rapidly slagging a converter and reducing comprehensive lime consumption under high iron consumption, comprising the following steps:

[0073] S1, leaving the slag after the previous furnace is tapped in the converter to perform slag splashing and furnace protection operation;

[0074] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0075] S3, adding the molten iron and scrap steel described in step S2 into a converter, wherein the weight ratio of scrap steel to molten iron is ≤5%;

[0076] S4, when the blowing time is 0min≤BT≤6min, according to the Si content in the molten iron added to the converter in step S3, lime, sintered ore and magnesium balls are added in batches, the oxygen flow rate of the oxygen lance is controlled to be the lower limit of the designed oxygen pressure, and the bottom blowing gas supply intensity is 0.05~0.08Nm 3 / t·min;

[0077] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel, control the oxygen flow rate of oxygen lance to exceed the designed oxygen pressure by 5%, and the bottom blowing gas supply intensity is 0.04~0.06Nm 3 / t·min;

[0078] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel, control the oxygen flow rate of oxygen lance to exceed the designed oxygen pressure by 10%, and the bottom blowing gas supply intensity is 0.04~0.06Nm 3 / t·min;

[0079] S7. At the end of smelting, high oxygen pressure and low lance position oxygen lance operation is performed for 40 to 60 seconds.

[0080] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0081] It should be noted that in step S1, in the normal production rhythm, all the slag from the previous furnace is left, and then nitrogen is blown to splash the slag to protect the furnace. The splashing slag layer not only protects the furnace, but also, because the terminal slag has high basicity, high temperature, and a certain TFe content, there are low-melting-point substances in the slag layer, such as iron oxide, etc. When adding molten iron, the low-melting-point substances melt into the furnace along with the molten iron, and then in the early stage of blowing, it can effectively ensure the melting of the initial slag and help slag removal.

[0082] For abnormal ladles with low ladle temperature, such as black ladle, high steel tapping temperature above 1670℃, or serious overoxidation of molten steel (high TFe), resulting in poor converter condition, retain 1 / 2 of the slag from the furnace for splashing slag protection.

[0083] For furnaces that need to measure the liquid level after adding iron, or that need to replenish the furnace after steel is tapped, such as when padding small and large surfaces, no slag will be left and no slag splashing will be performed to protect the furnace.

[0084] It should be noted that in step S2, the CaO content of the limestone is about 52-55% by mass percentage; the main components of the sintered ore are as follows: TFe≥54%, FeO<10%, 9%<CaO<13%, 5.5%<SiO 2 <8%, basicity R=CaO / SiO 2 ≥1.6, S<0.04%; in terms of mass percentage of molten iron, Mn<0.6%, Si content<1.2%, 0.1%<P<0.15%, 0.002%<S<0.035%. There is a certain relationship between the amount of limestone and sintered ore added and the Si content in molten iron, specifically:

[0085] When Si<0.20%,

[0086] Limestone addition amount: M 石灰石 =0.0108M 铁水 +0.0694 (1)

[0087] Sintered ore addition amount: M 烧结矿=0.00815M 铁水 +0.0487 (2)

[0088] When 0.2%≤Si<0.5%,

[0089] Limestone addition amount: M 石灰石 =(0.0161~0.0267)M 铁水 +(0.1165~0.1969)(3)

[0090] Sintered ore addition amount:

[0091] M 烧结矿 =(0.01085~0.01355)M 铁水 +(0.06625~0.08255) (4)

[0092] When 0.5%≤Si≤0.8%,

[0093] Limestone addition amount: M 石灰石 =(0.0457~0.0571)M 铁水 +(0.548~0.8898)(5)

[0094] Sintered ore addition amount: M 烧结矿 =0.01625M 铁水 +0.1010(6)

[0095] When 0.8%<Si≤1.2%,

[0096] Limestone addition amount: M 石灰石 =(0.0611~0.0663)M 铁水 +(0.2351~0.3047)(7)

[0097] Sintered ore addition amount: M 烧结矿 =0.01375M 铁水 +0.06095(8)

[0098] M 石灰石 is the weight of limestone added, M 烧结矿 is the added weight of sintered ore, M 铁水 The capacity of the converter is 30 tons to 300 tons to accommodate the weight of molten iron added to the converter.

[0099] When 0.6%≤Mn<1.2% in molten iron, add 0.5-1.0t more limestone as base material on the basis of the above.

[0100] Specifically, in step S3, in the furnace loading of the present invention, the weight ratio of scrap steel to molten iron is ≤5%, which is the specific requirement of the present invention for high iron consumption. The conventional weight ratio of scrap steel to molten iron is about 10%, and in most cases it is above 10%. The molten iron temperature is ≥1240°C.

[0101] It should be noted that in steps S4, S5 and S6, BT is the abbreviation of blow time, which means blowing time.

[0102] In step S4, lime, sintered ore and magnesium balls are added in small batches according to the furnace conditions during blowing. Due to the excess heat under high iron consumption conditions, there is no need to heat and slag through carbon-oxygen reaction, so a high gun position is used for blowing. After the initial slag is melted, the gun position is appropriately lowered to avoid splashing. The gun position is generally controlled at 1.8 to 2.4 m. The oxygen supply design pressure of the oxygen lance of converters of different tonnages is different, such as between 0.60 and 1.3 MPa, and the bottom blowing gas of the converter is nitrogen or argon.

[0103] There is a certain relationship between the amount of lime, sintered ore and magnesium balls added and the Si content in the molten iron. Specifically, when Si < 0.20%,

[0104] Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694 (9)

[0105] Sintered ore addition amount: M' 烧结矿 =0.00815M 铁水 +0.0487 (10)

[0106] Amount of magnesium ball added: M 镁球 =0.0043M 铁水 +0.0273 (11)

[0107] When 0.2%≤Si<0.5%,

[0108] Lime addition amount: M 石灰 =0.0163M 铁水 +0.0974(12)

[0109] Sintered ore addition amount:

[0110] M' 烧结矿 =(0.01085~0.01355)M 铁水 +(0.06625~0.08255) (13)

[0111] Amount of magnesium ball added: M 镁球 =(0.0066~0.011)M 铁水 +(0.0271~0.0503)(14)

[0112] When 0.5%≤Si≤0.8%,

[0113] Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694 (15)

[0114] Sintered ore addition amount: M' 烧结矿 =0.01625M 铁水 +0.1010 (16)

[0115] Amount of magnesium ball added: M 镁球 =(0.0123~0.0133)M 铁水 +(0.0187~0.0249)(17)

[0116] When 0.8%<Si≤1.2%,

[0117] Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694 (18)

[0118] Sintered ore addition amount: M' 烧结矿 =0.01375M 铁水 +0.06095 (19)

[0119] Amount of magnesium ball added: M 镁球 =0.0108M 铁水 +0.0694 (20) M 石灰 is the weight of lime added, M 镁球 is the weight of magnesium balls added, M' 烧结矿 is the added weight of sintered ore, M 铁水 The capacity of the converter is 30 tons to 300 tons to accommodate the weight of molten iron added to the converter.

[0120] When there is no slag left in the previous furnace for slag splashing protection, the lime can be appropriately increased by 0.5 to 1.0 t during the blowing process in step S4 of the current furnace.

[0121] It should be noted that, under the influence of the Si content in the molten iron, the weight M of the limestone added to the base material in step S2 is 石灰石 There is a certain proportional relationship between the total amount of sintered ore added in step S2 and step S4. Specifically, when Si<0.20%, all TFe in the sintered ore added in step S2 and step S4 is converted into Fe. 2 O 3 The ratio of the total amount of CaO in the limestone added in step S2 is about 2.1, that is, [(M 烧结矿+M' 烧结矿 )×54%÷70%】 /

M 石灰石 ×55%

M 石灰石 ×55%

M 石灰石 ×55%

M 石灰石 ×55%

[0122] Figure 1 CaO-FeO x binary phase diagram, Figure 2 CaO-Fe 2 O 3 Binary phase diagram. As can be seen from the figure, CaO and FeO x There are three compounds of calcium ferrite, namely, C 2 F(2CaO·Fe 2 O 3 )、CF(CaO·Fe 2 O 3 ) and CF2(CaO·2Fe 2 O 3 ), the melting temperatures of the three are 1448℃, 1228℃ and 1205℃ respectively.

[0123] In the present invention, by adjusting the ratio of limestone, lime and sintered ore and mixing molten iron, calcium ferrite slag with a relatively low melting point is first generated.

[0124] Limestone reacts with iron oxide as follows:

[0125] 2CaCO 3(s) +Fe 2 O 3(s) =2CaO·Fe 2 O 3(s) +CO 2(g) (twenty one)

[0126] ΔG 0 =269500-276.97T

[0127] CaCO 3(s) +Fe 2 O 3(s) =CaO·Fe 2 O 3(s) +CO 2(g) (twenty two)

[0128] ΔG 0 =131600-142.04T

[0129] According to the calculation of formula (21) and (22), when the temperature is greater than 700°C, ΔG of formula (21) and (22) is less than 0, and calcium ferrite and dicalcium ferrite can be generated. The formation of low melting point slag is conducive to the dissolution of lime, and the generation of high basicity slag in the early stage of the converter is conducive to the dephosphorization of the converter.

[0130] 2CaO (s) +Fe 2 O 3(s) =2CaO·Fe 2 O 3(s) (twenty three)

[0131] ΔG 0 =-53100-2.51T

[0132] CaO (s) +Fe 2 O 3(s) =CaO·Fe 2 O 3(s) (twenty four)

[0133] ΔG 0 =-29700-4.81T

[0134] According to the calculation of formula (23) and (24), when the temperature is greater than 25°C, ΔG of formula (23) and (24) is less than 0, and calcium ferrite and dicalcium ferrite can be generated. The formation of low melting point slag is conducive to the dissolution of lime, and the generation of high basicity slag in the early stage of the converter is conducive to the dephosphorization of the converter.

[0135] It should be noted that CaO and Fe 2 O 3 The mass ratio of calcium ferrite and dicalcium ferrite formed by the complete reaction should be M Fe2O3 / M CaO =1.41~2.85, but due to the presence of SiO in the steelmaking slag system 2 The presence of SiO 2 and CaO to form calcium silicate, and SiO 2 ,CaO,Fe 2 O 3 , FeO, and MgO will form ternary or even quaternary oxide combinations, so in addition to calcium ferrite and dicalcium ferrite, other calcium oxides are also generated in the initial slag. And as the Si content in the molten iron increases, SiO 2 The probability of combining with CaO increases, which increases the consumption of CaO. In order to ensure the basicity, the content of CaO also increases. Therefore, as the Si content in the molten iron increases, M Fe2O3 / M CaO The value of will gradually decrease. When 0.5%≤Si, M Fe2O3 / M CaO <1.0, which is lower than the range of 1.41~2.85, but due to the presence of other phases, especially SiO 2 There are a lot of them. At this time, M Fe2O3 / M CaO The ratio does not reflect the CaO and Fe 2 O 3 The actual situation of the two-phase reaction, coupled with the low melting points of calcium ferrite and dicalcium ferrite, which are much lower than the melting points of other oxide combinations in the slag system, is more conducive to the formation of calcium ferrite and dicalcium ferrite according to the metallurgical physicochemical reaction kinetics. Moreover, there are also some calcium ferrite compounds in the sintered ore, which will promote the further progress of the reaction after melting first.

[0136] In addition, if the amount of bed material added is too large, it will lead to the phenomenon of failure to ignite after blowing. Therefore, the present invention adds half of the calculated amount of sintered ore to the bed material, and in the blowing 0min≤BT≤6min stage, according to the slag situation, the remaining half of the sintered ore is added in batches, that is, the total weight of the sintered ore added in step S2 is equal to the total weight of the sintered ore added in step S4. Moreover, as the blowing oxidation proceeds, the Fe element in the molten iron enters the slag, and lime and magnesium balls need to be added to further maintain the component balance of the slag system.

[0137] P is generally a harmful element in steel. Dephosphorization is an important task in steelmaking. The oxidation dephosphorization reaction occurs at the steel-slag interface, and its chemical reaction equation can be expressed as:

[0138] 2[P]+5(FeO)+4(CaO)=(4CaO·P2 O 5 )+5[Fe] (25)

[0139] 2[P]+5(FeO)+3(CaO)=(3CaO·P 2 O 5 )+5[Fe] (26)

[0140] From the above two equations, it can be seen that high (FeO), high (CaO) (high alkalinity) and large slag volume in the slag are conducive to the dephosphorization reaction. In addition, since the dephosphorization reaction is a strong exothermic reaction, low temperature is also conducive to dephosphorization.

[0141] The simultaneous addition of limestone and sintered ore in the base material promotes the formation of low-temperature liquid calcium ferrite and dicalcium ferrite in the slag system, which satisfies the kinetic conditions of the dephosphorization reaction in the micro-region of the steel slag interface and promotes the dephosphorization reaction. First of all, steelmaking is an oxidative exothermic process. As the reaction proceeds, the furnace temperature gradually rises. The dephosphorization efficiency decreases in the later stages. Therefore, at a relatively low temperature, it is beneficial to form primary slag as soon as possible for dephosphorization. Secondly, sintered ore contains CaO and SiO, which are essential in slag. 2 etc., and the alkalinity R(CaO / SiO 2 )≥1.6, and the presence of some low melting point calcium ferrite compounds, plus the excess heat of high iron consumption, are all favorable conditions for the formation of primary slag. Thirdly, liquid phase reaction is more efficient than solid phase reaction, or liquid-solid reaction. Finally, calcium ferrite and dicalcium ferrite provide a method for simultaneously and co-existing with Ca 2+ , Fe 2 O 5 4- , Fe 2 O 4 4- The state of the ions and the chance of [P] meeting meet the material conditions for the three reactants to combine, which naturally increases the probability of the reaction occurring.

[0142] It should be noted that the comprehensive lime consumption is calculated as M 石灰石 ×55%+M 石灰 .

[0143] Compared with the present invention, the existing converter slag-making materials are added after the converter is blown with molten iron, the lime melts slowly in the early stage of the converter, and the dephosphorization effect in the early stage of the converter is poor. The converter dephosphorization is mainly completed after the lime melts in the later stage to form high-basicity slag. Therefore, the later stage dephosphorization burden is heavy, and the terminal one-time hit rate ratio is low, which leads to serious overoxidation of molten steel at the converter terminal, reducing the metal recovery rate and reducing the converter production efficiency.

[0144] Specifically, after slag is melted in step S4, the gun position should be appropriately lowered in step S5 to avoid splashing, but if the gun position is too low, it is easy to dry out. The gun position is generally controlled at 0.9 to 1.2 meters. At the same time, in order to control the temperature of the molten steel to rise too fast, add an appropriate amount of sintering ore to adjust the temperature of the molten steel.

[0145] Specifically, after the above two steps of blowing, the early dephosphorization task is basically completed. In step S6, the carbon content and temperature of the molten steel must be controlled to meet the requirements of steelmaking. Decarburization and temperature control are the main tasks at this stage. The gun position is generally controlled at 1.2 to 1.6 meters according to the carbon content in the steel, and an appropriate amount of sintered ore is added as needed to control the temperature of the molten steel.

[0146] It should be noted that in step S7, the oxygen lance operation with high oxygen pressure and low lance position is adopted to uniform the composition and temperature and reduce the oxidizability of the slag, such as operating the oxygen lance at 0.82-0.95MPa and 0.8-1.0m lance position.

[0147] It should be noted that when 0.6%≤Mn<1.2% in the molten iron, constant gun position operation is adopted in steps S4, S5 and S6, such as the gun position is 1.2-1.8 meters.

[0148] Compared with the traditional feeding method during the converter blowing period, the operation of laying the bottom material provided by the present invention can form the converter primary slag 3-4 minutes earlier. The lime and sintered ore are added at the same time, so as to achieve the purpose of forming calcium ferrite slag as soon as possible. The slag basicity is between 1.8-2.3 after 6 minutes of converter blowing, and the dephosphorization rate is between 40-60%. The dephosphorization effect in the early stage of the converter is significant. In addition, the method provided by the present invention can save more than 30% of the comprehensive lime on average, and obtain better economic benefits.

[0149] Example 1

[0150] S1. Leave the slag after the last furnace is tapped in the converter to perform slag splashing and furnace protection operation; the amount of slag left is 25kg / t, and the slag composition is CaO 45.34%, SiO 2 18.12%, FeO 10.32%, MnO 1.24%, MgO 6.98%, P 2 O 5 2.24%.

[0151] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0152] The amount of molten iron is 85t, and the chemical composition of the molten iron is C 4.53%, Si 0.25%, Mn 0.22%, P 0.13%, and S0.025%.

[0153] Limestone addition amount:

[0154] M 石灰石 =0.018×85+0.1370=1.667 tons

[0155] Sintered ore addition amount:

[0156] M 烧结矿 =0.011×85+0.07=1.005 tons

[0157] S3, add molten iron and scrap steel; the molten iron temperature is 1247°C, the scrap steel is 3 tons, and the weight ratio of scrap steel to molten iron is 3.53%.

[0158] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The gun position is 2.0m, and the oxygen flow rate of the oxygen gun is controlled to be 18000Nm 3 / h, bottom blowing nitrogen supply intensity is 0.05Nm 3 / t·min;

[0159] Lime addition amount: M 石灰 =0.0163×85+0.0974=1.483 tons

[0160] Sintered ore addition amount: M' 烧结矿 =0.011×85+0.07=1.005 tons

[0161] Amount of magnesium ball added: M 镁球 =0.008×85+0.03=0.71 tons

[0162] The slag basicity is 2.0 at 6 minutes of converter blowing.

[0163] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 0.9m, and the bottom blowing nitrogen supply intensity is 0.04Nm 3 / t·min;

[0164] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.2m, and the bottom blowing nitrogen supply intensity is 0.06Nm 3 / t·min;

[0165] S7, at the end of smelting, high oxygen pressure and low lance position oxygen lance operation was performed for 40 seconds, the oxygen lance oxygen pressure was 0.9MPa, and the oxygen flow rate was 22000Nm 3 / h, the oxygen lance position is 1.0m.

[0166] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0167] The converter end point [P] is 0.015%, which meets the control requirement of [P]≤0.035%, [C] is 0.14%, the steel output is 80.72t, the temperature is 1655℃, the initial dephosphorization rate is 60%, and the total dephosphorization rate is 88%. The slag material consumption is 17.45kg / t of lime, 19.61kg / t of limestone, 9.46kg / t of magnesium balls, and 23.65kg / t of sintered ore.

[0168] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 28.2kg / t, thus greatly saving the consumption of lime.

[0169] Example 2

[0170] S1. All the slag after the last furnace is left in the converter for slag splashing and furnace protection operation; the amount of slag left is 28kg / t, and the slag composition is CaO 44.15%, SiO 2 18.5%, FeO 11.82%, MnO 1.84%, MgO 8.01%, P 2 O 5 2.65%.

[0171] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0172] The amount of molten iron is 93t, and the chemical composition of the molten iron is C 4.34%, Si 0.43%, Mn 0.25%, P 0.13%, and S0.03%.

[0173] Limestone addition amount:

[0174] M 石灰石 =0.0267×93+0.1969=2.68 tons

[0175] Sintered ore addition amount:

[0176] M 烧结矿 =0.01085×93+0.06625=1.075 tons

[0177] S3, add molten iron and scrap steel; the temperature of the molten iron is 1324°C, the scrap steel is 4 tons, and the weight ratio of the scrap steel to the molten iron is 4.3%.

[0178] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The lance position is 2.4m, and the oxygen flow rate of the oxygen lance is controlled to be 18000Nm 3 / h, the bottom blowing argon supply intensity is 0.06Nm 3 / t·min;

[0179] Lime addition amount: M 石灰 =0.0163×93+0.0974=1.613 tons

[0180] Sintered ore addition amount: M' 烧结矿 =0.01085×93+0.06625=1.075 tons

[0181] Amount of magnesium ball added: M 镁球 =0.0082×93+0.0374=0.8 tons

[0182] The slag basicity is 1.8 after 6 minutes of converter blowing.

[0183] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 1.1m, and the bottom blowing argon supply intensity is 0.05Nm 3 / t·min;

[0184] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.6m, and the bottom blowing argon supply intensity is 0.06Nm 3 / t·min;

[0185] S7. At the end of smelting, high oxygen pressure and low lance position oxygen lance operation was performed for 50 seconds. The oxygen pressure of the oxygen lance was 0.9MPa and the oxygen flow rate of the oxygen lance was 22000Nm 3 / h, the oxygen lance position is 0.9m.

[0186] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0187] The converter end point [P] is 0.029%, which meets the control requirement of [P]≤0.035%, [C] is 0.13%, the steel output is 88.92t, the temperature is 1660℃, the initial dephosphorization rate is 40%, and the total dephosphorization rate is 77.7%. The slag material consumption is 17.34kg / t of lime, 28.82kg / t of limestone, 8.6kg / t of magnesium balls, and 23.12kg / t of sintered ore.

[0188] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 33.19kg / t, thus greatly saving the consumption of lime.

[0189] Example 3

[0190] S1. Leave the slag after the last furnace is tapped in the converter to perform slag splashing and furnace protection operation; the amount of slag left is 30kg / t, and the slag composition is CaO 45.65%, SiO 2 14.98%, FeO 13.24%, MnO 1.12%, MgO 8.21%, P 2 O 5 2.12%.

[0191] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0192] The amount of molten iron is 91t, and the chemical composition of the molten iron is C5.12%, Si 0.60%, Mn 0.23%, P 0.12%, and S0.028%.

[0193] Limestone addition amount:

[0194] M 石灰石 =0.05×91+0.55=5.1 tons

[0195] Sintered ore addition amount: M 烧结矿 =0.01625×91+0.1010=1.580 tons;

[0196] S3. Add molten iron and scrap steel; the temperature of the molten iron is 1334°C, the scrap steel is 4 tons, and the weight ratio of the scrap steel to the molten iron is 4.4%.

[0197] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The gun position is 2.0m, and the oxygen flow rate of the oxygen gun is controlled to be 18000Nm 3 / h, bottom blowing nitrogen supply intensity is 0.07Nm 3 / t·min;

[0198] Lime addition amount: M 石灰 =0.0108×91+0.0694=1.052 tons

[0199] Sintered ore addition amount: M' 烧结矿 =0.01625×91+0.1010=1.580 tons

[0200] Amount of magnesium ball added: M 镁球=0.0123×91+0.0187=1.138 tons

[0201] The slag basicity is 2.3 after 6 minutes of converter blowing.

[0202] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 1.2m, and the bottom blowing nitrogen supply intensity is 0.06Nm 3 / t·min;

[0203] S6. After blowing for 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.4m, and the bottom blowing nitrogen supply intensity is 0.06Nm 3 / t·min;

[0204] S7. At the end of smelting, high oxygen pressure and low lance position oxygen lance operation was performed for 60 seconds. The oxygen pressure of the oxygen lance was 0.9MPa and the oxygen flow rate of the oxygen lance was 22000Nm 3 / h, the oxygen lance position is 0.8m.

[0205] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0206] The converter end point [P] is 0.029%, which meets the control requirement of [P]≤0.035%, [C] is 0.07%, the steel output is 89.84t, the temperature is 1669℃, the initial dephosphorization rate is 50%, and the total dephosphorization rate is 76%. The slag material consumption is 11.56kg / t of lime, 56.04kg / t of limestone, 12.51kg / t of magnesium balls, and 34.73kg / t of sintered ore.

[0207] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 42.38kg / t, thus greatly saving the consumption of lime.

[0208] Example 4

[0209] S1. Leave the slag after the last furnace is tapped in the converter to perform slag splashing and furnace protection operation; the amount of slag left is 23kg / t, and the slag composition is CaO 40.5%, SiO 2 17.4%, FeO 13.6%, MnO 1.2%, MgO 8.2%, P 2 O 5 2.5%.

[0210] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0211] The amount of molten iron is 89t, and the chemical composition of the molten iron is C5.3%, Si 0.22%, Mn 0.67%, P 0.10%, and S0.023%.

[0212] Limestone addition amount:

[0213] M 石灰石 =0.0267×89+0.1969+0.5=3.073 tons

[0214] Sintered ore addition amount: M 烧结矿 =0.0119×89+0.0669=1.126 tons;

[0215] S3, add molten iron and scrap steel; the molten iron temperature is 1390°C, the scrap steel is 4.45t, and the weight ratio of scrap steel to molten iron is 5%.

[0216] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The gun position is 1.5m, and the oxygen flow rate of the oxygen gun is controlled to be 18000Nm 3 / h, bottom blowing nitrogen supply intensity is 0.08Nm 3 / t·min;

[0217] Lime addition amount: M 石灰 =0.0163×89+0.0974=1.548 tons

[0218] Sintered ore addition amount: M' 烧结矿 =0.0119×89+0.0669=1.126 tons;

[0219] Amount of magnesium ball added: M 镁球 =0.0085×89+0.0355=0.792 tons

[0220] The slag basicity is 1.95 after 6 minutes of converter blowing.

[0221] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 1.5m, and the bottom blowing nitrogen supply intensity is 0.04Nm 3 / t·min;

[0222] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.5m, and the bottom blowing nitrogen supply intensity is 0.04Nm 3 / t·min;

[0223] S7. At the end of smelting, the oxygen lance was operated at high oxygen pressure and low lance position for 50 seconds. The oxygen pressure of the oxygen lance was 0.95MPa and the oxygen flow rate of the oxygen lance was 22000Nm 3 / h, the oxygen lance position is 0.85m.

[0224] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0225] The converter end point [P] is 0.021%, which meets the control requirement of [P]≤0.035%, [C] is 0.14%, the steel output is 88t, the temperature is 1660℃, the initial dephosphorization rate is 58%, and the total dephosphorization rate is 79%. The slag material consumption is 17.39kg / t of lime, 34.53kg / t of limestone, 8.9kg / t of magnesium balls, and 25.3kg / t of sintered ore.

[0226] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 36.38kg / t, thus greatly saving the consumption of lime.

[0227] Example 5

[0228] S1. Leave the slag after the last furnace is tapped in the converter to perform slag splashing and furnace protection operation; the amount of slag left is 25kg / t, and the slag composition is CaO 42.1%, SiO 2 15.4%, FeO 12.5%, MnO 1.3%, MgO 9.3%, P 2 O 5 2.2%;

[0229] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0230] The amount of molten iron is 97t, and the chemical composition of the molten iron is C 4.9%, Si 0.52%, Mn 0.82%, P 0.11%, S0.022%;

[0231] Limestone addition amount:

[0232] M 石灰石 =0.046×97+0.6+0.6=5.662 tons

[0233] Sintered ore addition amount: M 烧结矿 =0.01625×97+0.1010=1.677 tons;

[0234] S3, add molten iron and scrap steel; the temperature of the molten iron is 1380°C, the scrap steel is 4 tons, and the weight ratio of the scrap steel to the molten iron is 4.12%.

[0235] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The lance position is 1.3m, and the oxygen flow rate of the oxygen lance is controlled to be 18000Nm 3 / h, bottom blowing nitrogen supply intensity is 0.07Nm 3 / t·min;

[0236] Lime addition amount: M 石灰 =0.0108×97+0.0694=1.117 tons

[0237] Sintered ore addition amount: M' 烧结矿 =0.01625×97+0.1010=1.677 tons;

[0238] Amount of magnesium ball added: M 镁球 =0.013×97+0.02=1.281 tons

[0239] The slag basicity is 2.1 at 6 minutes of converter blowing.

[0240] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 1.3m, and the bottom blowing nitrogen supply intensity is 0.05Nm 3 / t·min;

[0241] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.3m, and the bottom blowing nitrogen supply intensity is 0.05Nm 3 / t·min;

[0242] S7, at the end of smelting, high oxygen pressure and low lance position oxygen lance operation was performed for 40 seconds, the oxygen lance oxygen pressure was 0.82MPa, and the oxygen flow rate of the oxygen lance was 22000Nm 3 / h, the oxygen lance position is 0.9m.

[0243] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0244] The converter end point [P] is 0.027%, which meets the control requirement of [P]≤0.035%, [C] is 0.20%, the steel output is 97t, the temperature is 1640℃, the initial dephosphorization rate is 55%, and the total dephosphorization rate is 75.5%. The slag material consumption is lime 11.52kg / t, limestone 58.37kg / t, magnesium balls 13.21kg / t, and sintered ore 34.58kg / t.

[0245] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 43.62kg / t, thus greatly saving the consumption of lime.

[0246] Example 6

[0247] S1. Leave the slag after the last furnace is tapped in the converter to perform slag splashing and furnace protection operation; the amount of slag left is 22kg / t, and the slag composition is CaO 45.2%, SiO 2 17.3%, FeO 10.2%, MnO 1.1%, MgO 7.9%, P 2 O 5 2.1%.

[0248] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0249] The amount of molten iron is 86t, and the chemical composition of the molten iron is C 5.1%, Si 0.16%, Mn 0.22%, P 0.124%, and S0.021%.

[0250] Limestone addition amount: M 石灰石 =0.0108×86+0.0694=0.998 tons

[0251] Sintered ore addition amount: M 烧结矿 =0.00815×86+0.0487=0.750 tons;

[0252] S3, add molten iron and scrap steel; the molten iron temperature is 1334°C, the scrap steel is 3 tons, and the weight ratio of scrap steel to molten iron is 3.5%.

[0253] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The lance position is 1.9m, and the oxygen flow rate of the oxygen lance is controlled to be 18000Nm 3 / h, bottom blowing nitrogen supply intensity is 0.07Nm 3 / t·min;

[0254] Lime addition amount: M 石灰=0.0108×86+0.0694=0.998 tons

[0255] Sintered ore addition amount: M' 烧结矿 =0.00815×86+0.0487=0.750 tons

[0256] Amount of magnesium ball added: M 镁球 =0.0043×86+0.0273=0.397 tons

[0257] The slag basicity is 2.3 after 6 minutes of converter blowing.

[0258] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 1.1m, and the bottom blowing nitrogen supply intensity is 0.06Nm 3 / t·min;

[0259] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.6m, and the bottom blowing nitrogen supply intensity is 0.04Nm 3 / t·min;

[0260] S7, at the end of smelting, high oxygen pressure and low lance position oxygen lance operation was performed for 40 seconds, the oxygen lance oxygen pressure was 0.9MPa, and the oxygen flow rate of the oxygen lance was 22000Nm 3 / h, the oxygen lance position is 1.0m.

[0261] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0262] The converter end point [P] is 0.021%, which meets the control requirement of [P]≤0.035%, [C] is 0.08%, the steel output is 86t, the temperature is 1645℃, the initial dephosphorization rate is 60%, and the total dephosphorization rate is 83%. The slag material consumption is 11.6kg / t of lime, 11.6kg / t of limestone, 4.62kg / t of magnesium balls, and 17.44kg / t of sintered ore.

[0263] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 17.98kg / t, thus greatly saving the consumption of lime.

[0264] Example 7

[0265] S1. Leave the slag after the last furnace is tapped in the converter to perform slag splashing and furnace protection operation; the amount of slag left is 23kg / t, and the slag composition is CaO 41.6%, SiO2 13.7%, FeO 11.6%, MnO 1.34%, MgO 8.21%, P 2 O 5 2.23%.

[0266] S2. According to the weight of molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the bed material;

[0267] The amount of molten iron is 92.5t, and the chemical composition of the molten iron is C 5.2%, Si 0.85%, Mn 0.21%, P 0.114%, and S0.022%.

[0268] Limestone addition amount: M 石灰石 =0.063×92.5+0.24=6.068 tons

[0269] Sintered ore addition amount: M 烧结矿 =0.01375×92.5+0.06095=1.333 tons;

[0270] S3. Add molten iron and scrap steel; the temperature of the molten iron is 1376°C, the scrap steel is 4.5t, and the weight ratio of scrap steel to molten iron is 4.8%.

[0271] S4. When blowing time is 0min≤BT≤6min, lime, sintered ore and magnesium balls are added in batches according to the Si content in the molten iron added to the converter. The lance position is 2.2m, and the oxygen flow rate of the oxygen lance is controlled to be 18000Nm 3 / h, bottom blowing nitrogen supply intensity is 0.07Nm 3 / t·min;

[0272] Lime addition amount: M 石灰 =0.0108×92.5+0.0694=1.068 tons

[0273] Sintered ore addition amount: M' 烧结矿 =0.01375×92.5+0.06095=1.333 tons

[0274] Amount of magnesium ball added: M 镁球 =0.0108×92.5+0.0694=1.068 tons

[0275] The slag basicity is 2.0 at 6 minutes of converter blowing.

[0276] S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 19000Nm 3 / h, the gun position is 0.9m, and the bottom blowing nitrogen supply intensity is 0.06Nm 3 / t·min;

[0277] S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel and control the oxygen flow rate of oxygen lance to 21000Nm 3 / h, the gun position is 1.4m, and the bottom blowing nitrogen supply intensity is 0.04Nm 3 / t·min;

[0278] S7. At the end of smelting, high oxygen pressure and low lance position oxygen lance operation was performed for 60 seconds. The oxygen pressure of the oxygen lance was 0.9MPa and the oxygen flow rate of the oxygen lance was 22000Nm 3 / h, the oxygen lance position is 0.8m.

[0279] S8. Measure temperature, take samples to determine composition, pour the furnace and tap steel, perform deoxidation and alloying operations during tapping, and stop slag at the end of tapping.

[0280] The converter end point [P] is 0.026%, which meets the control requirement of [P]≤0.035%, [C] is 0.08%, the steel output is 92t, the temperature is 1660℃, the initial dephosphorization rate is 54%, and the total dephosphorization rate is 77%. The slag material consumption is lime 11.55kg / t, limestone 71.44kg / t, magnesium balls 11.55kg / t, and sintered ore 28.82kg / t.

[0281] The above method can achieve the reduction of lime under the condition of high iron consumption, which can reduce the comprehensive lime of 55kg / t in the original process to 50.84kg / t, saving the consumption of lime.

[0282] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A steelmaking method for rapidly slagging a converter under high iron consumption and reducing comprehensive lime consumption, characterized in that: The steps include: S1, leaving the slag after the previous furnace is tapped in the converter to perform slag splashing and furnace protection operation; S2. According to the weight of the molten iron to be added to the converter and the Si and Mn contents in the molten iron, limestone and sintered ore are added as the base material, and the mass percentage of the molten iron is Mn < 1.2%, Si < 1.2%, 0.1% < P < 0.15%, 0.002% < S < 0.035%; S3, adding the molten iron and scrap steel described in S2 into a converter, wherein the weight ratio of scrap steel to molten iron is ≤5%, and the temperature of the molten iron is ≥1240°C; S4, when blowing 0min≤BT≤6min, according to the Si content in the molten iron added to the converter in S3, lime, sintered ore and magnesium balls are added in batches, wherein the total weight of the sintered ore is equal to the total weight of the sintered ore added in S2, the oxygen flow rate of the oxygen lance is controlled to be the lower limit of the designed oxygen pressure, and the bottom blowing gas supply intensity is 0.05~0.08Nm 3 / t·min; the slag basicity is between 1.8 and 2.3 after 6 minutes of converter blowing, and the dephosphorization rate is between 40 and 60%; S5. When blowing 6min<BT≤10min, add sintered ore to control the temperature of molten steel, control the oxygen flow rate of oxygen lance to exceed the designed oxygen pressure by 5%, and the bottom blowing gas supply intensity to 0.04~0.06Nm 3 / t·min; S6. When blowing 10min<BT, add sintered ore to control the temperature of molten steel, control the oxygen flow rate of oxygen lance to exceed the designed oxygen pressure by 10%, and the bottom blowing gas supply intensity is 0.04~0.06Nm 3 / t·min; S7, at the end of smelting, high oxygen pressure and low lance position oxygen lance operation is performed for 40 to 60 seconds; S8, temperature measurement, sampling and composition determination, pouring furnace and tapping, deoxidation and alloying operations during tapping, and slag blocking at the end of tapping; When the molten iron in S2 has Mn<0.6% and Si<0.20%, in S2: Limestone addition amount: M 石灰石 =0.0108M 铁水 +0.0694, Sintered ore addition amount: M 烧结矿 =0.00815M 铁水 +0.0487; When the molten iron in S2 has Mn<0.6%, 0.2%≤Si<0.5%, in S2: Limestone addition amount: M 石灰石 =(0.0161~0.0267)M 铁水 +(0.1165~0.1969), Sintered ore addition amount: M 烧结矿 =(0.01085~0.01355)M 铁水 +(0.06625~0.08255); When the molten iron in S2 has Mn<0.6%, 0.5%≤Si≤0.8%, in S2: Limestone addition amount: M 石灰石 =(0.0457~0.0571)M 铁水 +(0.548~0.8898), Sintered ore addition amount: M 烧结矿 =0.01625M 铁水 +0.1010; When the molten iron in S2 has Mn<0.6%, 0.8%<Si≤1.2%, in S2: Limestone addition amount: M 石灰石 =(0.0611~0.0663)M 铁水 +(0.2351~0.3047), Sintered ore addition amount: M 烧结矿 =0.01375M 铁水 +0.06095; When the molten iron in S2 is 0.6%≤Mn<1.2%, Si<0.20%, in S2: Limestone addition amount: M 石灰石 =0.0108M 铁水 +0.0694+(0.5~1.0), Sintered ore addition amount: M 烧结矿 =0.00815M 铁水 +0.0487; When the molten iron in S2 has 0.6%≤Mn<1.2%, 0.2%≤Si<0.5%, in S2: Limestone addition amount: M 石灰石 =(0.0161~0.0267)M 铁水 +(0.1165~0.1969)+(0.5~1.0), Sintered ore addition amount: M 烧结矿 =(0.01085~0.01355)M 铁水 +(0.06625~0.08255); When the molten iron in S2 has 0.6%≤Mn<1.2%, 0.5%≤Si≤0.8%, in S2: Limestone addition amount: M 石灰石 =(0.0457~0.0571)M 铁水 +(0.548~0.8898)+(0.5~1.0), Sintered ore addition amount: M 烧结矿 =0.01625M 铁水 +0.1010; When the molten iron in S2 has 0.6%≤Mn<1.2%, 0.8%<Si≤1.2%, in S2: Limestone addition amount: M 石灰石 =(0.0611~0.0663)M 铁水 +(0.2351~0.3047)+(0.5~1.0), Sintered ore addition amount: M 烧结矿 =0.01375M 铁水 +0.06095; Among them, the M 石灰石 is the weight of limestone added, the M 烧结矿 is the added weight of sintered ore, the M 铁水 is the weight of molten iron added to the converter; When Si in the molten iron in S2 is less than 0.20%, in S4: Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694, Amount of magnesium ball added: M 镁球 =0.0043M 铁水 +0.0273; When the molten iron in S2 is 0.2%≤Si<0.5%, in S4: Lime addition amount: M 石灰 =0.0163M 铁水 +0.0974, Amount of magnesium ball added: M 镁球 =(0.0066~0.011)M 铁水 +(0.0271~0.0503); When the molten iron in S2 is 0.5%≤Si≤0.8%, in S4: Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694, Amount of magnesium ball added: M 镁球 =(0.0123~0.0133)M 铁水 +(0.0187~0.0249); When the molten iron in S2 is 0.8%<Si≤1.2%, in S4: Lime addition amount: M 石灰 =0.0108M 铁水 +0.0694, Amount of magnesium ball added: M 镁球 =0.0108M 铁水 +0.0694; The M 石灰 is the weight of lime added, the M 镁球 is the weight of magnesium balls added, the M 铁水 is the weight of molten iron added to the converter; When the molten iron Mn in S2 is less than 0.6%, in S4, the oxygen lance position is controlled at 1.8-2.4m, in S5, the oxygen lance position is controlled at 0.9-1.2m, and in S6, the oxygen lance position is controlled at 1.2-1.6m; When the molten iron in S2 is 0.6%≤Mn<1.2%, the oxygen lances in S4, S5 and S6 are operated at a constant lance position of 1.2 to 1.8 meters.

2. The steelmaking method according to claim 1, characterized in that: In said S1, when the tapping temperature of the previous furnace is above 1670°C, or the molten steel is overoxidized, 1 / 2 of the slag of the furnace is retained.

3. The steelmaking method according to any one of claims 1-2, characterized in that: In the S2, the limestone has a CaO content of 52-55% by mass.

4. The steelmaking method according to any one of claims 1-2, characterized in that: The sintered ore has the following contents in percentage by mass: TFe≥54%, FeO<10%, 9%<CaO<13%, 5.5%<SiO2<8%, basicity R=CaO / SiO2≥1.6, S<0.04%.

5. The steelmaking method according to claim 1, characterized in that: In S4, the slag basicity is between 1.8 and 2.1 after 6 minutes of converter blowing.

6. The steelmaking method according to claim 1, characterized in that: When the Mn of the molten iron in S2 is less than 0.6%, in S4, the oxygen lance position is controlled at 1.9-2.4m, in S5, the oxygen lance position is controlled at 0.9-1.1m, and in S6, the oxygen lance position is controlled at 1.2-1.6m.

7. The steelmaking method according to claim 1, characterized in that: When the molten iron in S2 is 0.6%≤Mn<1.2%, the oxygen lances in S4, S5 and S6 are operated at a constant lance position of 1.3-1.8 meters.

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