Smelting method for increasing tapping quantity by adding iron-containing material in early stage of converter double-slag method

Abstract

The invention relates to a smelting method for increasing the tapping amount by adding an iron-containing material in the early stage of a converter double-slag method, and belongs to the technical field of converter steelmaking. According to the smelting method, 50%-60% of slag of the previous converter is left in the converter; according to the components and the weight of molten iron to be added, limestone and an iron-containing material are added to serve as backing materials to be laid at the bottom of the furnace, and the needed iron-containing material accounts for 20%-30% of the total amount; molten iron is added, waste steel is added, an oxygen lance is put down for ignition for blowing, and after blowing is completed for 30 s after oxygen climbing is completed, lime and 50%-60% of the total amount of needed iron-containing materials are added; blowing and deslagging; the deslagging amount is controlled to be more than 50%; and after deslagging is finished, the gun is lowered for blowing again. According to the invention, the TFe content in the earlier-stage slag can be reduced from 30-40% to 20-25%, so that the influence of earlier-stage deslagging of a double-slag method on the loss of molten steel is reduced; and the tapping amount is increased by 10-15 kg / t on the original basis.

Description

Technical Field

[0001] The invention relates to the technical field of converter steelmaking, and in particular to a smelting method for increasing the output of steel by adding iron-containing materials in the early stage of a converter double-slag method. Background Art

[0002] With the continuous development of the steel industry, cost reduction and efficiency improvement have become the development direction, especially in the field of converter steelmaking technology. The converter double slag method is a commonly used process in steelmaking methods. Especially in the smelting of high-silicon hot metal, it can significantly reduce the consumption of slag materials, reduce the splashing rate of high-silicon hot metal furnaces, stabilize production, and reduce energy waste by quickly slagging and desiliconizing in the early stage of smelting and then pouring out the silicon slag.

[0003] The double slag method is widely used by steel companies as an economical and efficient steelmaking method for smelting high-silicon molten iron. However, this method has problems such as difficulty in adding iron-containing materials and difficulty in separating slag and steel in the process before slag pouring. The early slag pouring is likely to bring out a large amount of molten steel, and splashing and slag overflow are likely to occur during the smelting process, resulting in a large loss of molten steel during the smelting process, thereby reducing the output of steel at the end of converter smelting.

[0004] Therefore, a method is needed that, based on the double-slag steelmaking method, adds iron-containing materials in the early stage of smelting to increase the final steel output, while fully promoting slag separation, reducing molten steel loss during the smelting process, and reducing lime consumption in the production process. Summary of the invention

[0005] In view of the above analysis, the present invention aims to provide a smelting method for adding iron-containing materials in the early stage of the converter double-slag method to increase the steel output, so as to solve the problem that the existing iron-containing materials are difficult to add and the steel output is low.

[0006] On the one hand, the present invention provides a smelting method for increasing the output of steel by adding iron-containing materials in the early stage of a converter double-slag process, comprising the following steps:

[0007] S1: Leave 50% to 60% of the slag from the previous furnace in the converter;

[0008] S2: According to the composition and weight of the molten iron to be added, limestone and iron-containing materials are added as base materials and spread on the bottom of the furnace. The required iron-containing materials are 20%-30% of the total amount; the composition of the molten iron is Si>0.60%, Mn<0.50%, 0.08%<P<0.12%, 0.002%<S<0.035% by mass percentage;

[0009] S3: Add molten iron and scrap steel, the iron-to-water ratio is controlled at 0.875-0.906, and the molten iron temperature is required to be ≥1300℃.

[0010] S4: Lower the oxygen lance to ignite and start blowing. After 30 s of blowing at the end of the oxygen ramping-up stage, add lime and 50%-60% of the total required iron-containing materials.

[0011] S5: Blow for about 240 s. When the CO recovery amount in the flue gas recovery system reaches 3%-5%, raise the lance to prepare for slag tapping.

[0012] S6: During the slag tapping operation, set the bottom blowing flow rate of the converter to 0.055 - 0.075 Nm 3 / (t·min). First, tilt the furnace towards the tapping direction to -40° to -50°, and then tilt the furnace forward to tap the slag. Control the slag tapping amount to be more than 50%.

[0013] S7: After the slag tapping is completed, lower the lance again to blow. Within 8 min of the total blowing time, supplement the remaining iron-containing materials, lime, raw dolomite, and magnesium balls.

[0014] Furthermore, in step S1, the basicity R of the slag at the end of the previous furnace is required to be > 2.6, the C content of the molten steel at the end of the previous furnace is > 0.08%, and the end temperature T < 1650 °C.

[0015] Furthermore, the iron-containing materials are required to have a mass percentage of H2O < 1.5%, 50% < TFe < 55%, SiO2 < 8%, and CaO > 18%.

[0016] Furthermore, in step S2, when 0.60% < Si ≤ 0.70% and S < 0.035% in the hot metal, the total amount of iron-containing materials required is M 含铁料 = 34.5 + 70×[w(Si) - 0.60] kg / t;

[0017] When 0.70% < Si ≤ 0.80% and S < 0.035% in the hot metal, the total amount of iron-containing materials required is M 含铁料 = 41.5 + 54×[w(Si) - 0.70] kg / t;

[0018] When 0.80% < Si ≤ 0.90% and S < 0.035% in the hot metal, the total amount of iron-containing materials required is M 含铁料 = 46.9 + 48×[w(Si) - 0.80] kg / t;

[0019] where M 含铁料 is the addition amount of the iron-containing materials, w(Si) is the mass fraction of Si in the hot metal, and t is the weight of the hot metal charged.

[0020] Furthermore, in step S2, by mass percentage, the limestone has a CaO content of 52 - 55% and SiO2 < 1.6%. The addition amount is M 石灰石 = 6.9 + 11.5×[w(Si) - 0.60] kg / t;

[0021] where M 石灰石 is the addition amount of limestone.

[0022] Further, in step S4, by mass percentage, the lime contains 90%-92% of CaO, SiO2 < 1.2%, and the addition amount is M 石灰 = 5.51 + 11.5×[w(Si) - 0.60] kg / t;

[0023] where M 石灰 is the addition amount of lime.

[0024] Further, in step S6, the furnace is tilted for temperature measurement and sampling, and the tilting temperature is required to be controlled at 1350 - 1420 °C.

[0025] Even further, when in step S2, the molten iron has 0.60% < Si ≤ 0.70% and S < 0.035%, the lime dosage in step S7 is M 石灰 = 11.56 + 36.1×[w(Si) - 0.60] kg / t;

[0026] When in step S2, the molten iron has 0.70% < Si ≤ 0.80% and S < 0.035%, the lime dosage in step S7 is M 石灰 = 15.17 + 20.8×[w(Si) - 0.70] kg / t;

[0027] When in step S2, the molten iron has 0.80% < Si ≤ 0.90% and S < 0.035%, the lime dosage in step S7 is M 石灰 = 17.25 + 20.6×[w(Si) - 0.80] kg / t;

[0028] The addition amount of raw dolomite is M 生白云石 = 13.8 + 22.9×[w(Si) - 0.60] kg / t, and the addition amount of magnesium balls is M 镁球 = 5.5 - 6.8×[w(Si) - 0.60] kg / t.

[0029] Further, in step S4, the lance position is controlled at 1.4 - 1.55 m, and in step S5, the lance position is controlled at 1.25 - 1.4 m.

[0030] Further, in the said step S7, it is required that the basicity R of the end slag > 2.6, and the mass percentage of MgO in the slag > 8%.

[0031] Compared with the prior art, the present invention can at least achieve one of the following beneficial effects:

[0032] 1. The present invention uses a method of leaving slag in the converter and pre-laying the bottom material, which is beneficial to the rapid slagging and desiliconization in the early stage of smelting. On the one hand, it saves the amount of lime, and on the other hand, it uses the residual heat in the furnace after slag splashing to melt the slag in advance. This method can maintain the temperature and increase the amount of iron-containing material added in the later stage;

[0033] 2. The present invention increases the bottom blowing flow rate of the converter and stirs the molten pool in the early stage of double slag pouring, and shakes the furnace body back and forth to promote the reaction of steel slag, so as to achieve the effect of full separation of steel slag. Compared with conventional double slag steelmaking, the TFe content in the early stage of the present invention can be reduced from 30% to 40% to 20%-25%, reducing the impact of the early stage of double slag pouring on the loss of molten steel;

[0034] 3. The present invention can significantly increase the steel output of the converter by adding a large amount of iron-containing material before slag pouring in the double slag method. The present invention can increase the steel output by 10-15kg / t on the original basis, thereby obtaining better economic benefits;

[0035] 4. The present invention adds more than 70% of the iron-containing material into the furnace before the early slag pouring, which can reduce the amount of slag-making material added after the slag pouring, stabilize the reaction in the furnace, reduce the probability of splashing and slag overflow, and reduce iron loss during the smelting process.

[0036] In the present invention, the above-mentioned technical solutions can also be combined with each other to achieve more preferred combination solutions. Other features and advantages of the present invention will be described in the subsequent description, and some advantages can become obvious from the description, or can be understood by practicing the present invention. The purpose and other advantages of the present invention can be achieved and obtained through the contents particularly pointed out in the description. DETAILED DESCRIPTION

[0037] The double-slag method is a steelmaking method for smelting high-silicon molten iron. However, this method has problems such as difficulty in adding iron-containing materials and difficulty in separating slag and steel in the process before slag pouring. The early slag pouring is likely to bring out a large amount of molten steel, and splashing and slag overflow are likely to occur during the smelting process, resulting in a large loss of molten steel during the smelting process, thereby reducing the amount of steel discharged at the end of the converter smelting.

[0038] Therefore, the present invention provides a smelting method for increasing the output of steel by adding iron-containing materials in the early stage of the converter double slag process, comprising the following steps:

[0039] S1: Leave 50% to 60% of the slag from the previous furnace in the converter;

[0040] S2: According to the composition and weight of the molten iron to be added, limestone and iron-containing materials are added as base materials and spread on the bottom of the furnace. The required iron-containing materials are 20%-30% of the total amount;

[0041] S3: Add molten iron and scrap steel, the molten iron ratio is controlled at 0.875-0.906, the molten iron temperature is required to be ≥1300℃, and the molten iron content by mass percentage is Si>0.60%, Mn<0.50%, 0.08%<P<0.12%, 0.002%<S<0.035%;

[0042] S4: The oxygen lance is ignited for blowing. After 30 seconds of oxygen ramping and blowing, lime and 50%-60% of the total amount of required iron-containing materials are added;

[0043] S5: After blowing for about 240 seconds, when the flame reaction and CO recovery reach 3%-5%, the gun is raised to prepare for slag dumping;

[0044] S6: During the slag pouring operation, set the converter bottom blowing flow rate to 0.055-0.075Nm 3 / (t·min), first shake the furnace to -40°~-50° in the direction of steel tapping, then shake the furnace forward to dump slag, and control the amount of slag dumping to more than 50%;

[0045] S7: After the slag is poured, the lance is lowered for blowing again. Within the total blowing time of 8 minutes, the remaining iron-containing materials and lime, limestone, raw dolomite and magnesium balls are added in small quantities and in multiple batches according to the temperature in the furnace and the slag-forming conditions.

[0046] Compared with the prior art, the present invention, on the one hand, by formulating the timing and weight of adding iron-containing materials in the early stage of smelting, and by increasing the bottom blowing flow rate of the converter and shaking the furnace, promotes the full reaction of the slag, accelerates the separation of slag and steel, increases the addition of iron-containing materials, and reduces iron losses in the smelting process; on the other hand, the present invention can reduce the amount of slag-making materials used in the smelting process, ultimately achieving the purpose of reducing costs and increasing steel output.

[0047] Specifically, in step S1, the final slag of the previous furnace is required to have a basicity R>2.6, and the final molten steel C content of the previous furnace is required to be>0.08%, and the final temperature T<1650°C.

[0048] It should be noted that if the final slag of the previous furnace is left in the converter for slag splashing protection, if the amount of slag left exceeds 60%, the amount of iron-containing material added will be affected and splashing will be easily caused; if it is less than 50%, the effect of slag splashing protection is poor. In step S1, the slag basicity R>2.6, the C content of molten steel>0.08%, and the final temperature T<1650℃ can be controlled to prevent the previous furnace molten steel from being seriously overoxidized, resulting in an increase in the amount of slag material added in this furnace.

[0049] Specifically, the iron-containing material is required to be H2O<1.5%, 50% by mass percentage. <TFe<55%,SiO2<8%,CaO> 18%.

[0050] It should be noted that, through the method of converter slag retention in step S1 and pre-laying bottom materials in step S2 of the present invention, it is beneficial to quickly form slag and desiliconize in the early stage of smelting. On the one hand, the consumption of lime is saved. On the other hand, the waste heat in the furnace after slag splashing is used to melt the slag materials in advance, and this method can retain the temperature to increase the addition amount of iron-containing materials in the later stage. In the present invention, controlling the H2O content can reduce the absorption of heat in the furnace by the iron-containing materials; controlling the content of SiO2 and increasing the content of CaO can reduce the addition amount of lime.

[0051] Specifically, in step S2, when the molten iron has 0.60% < Si ≤ 0.70% and S < 0.035%, the total amount of iron-containing materials required is M 含铁料 = 34.5 + 70×[w(Si) - 0.60] kg / t;

[0052] When the molten iron has 0.70% < Si ≤ 0.80% and S < 0.035%, the total amount of iron-containing materials required is M 含铁料 = 41.5 + 54×[w(Si) - 0.70] kg / t;

[0053] When the molten iron has 0.80% < Si ≤ 0.90% and S < 0.035%, the total amount of iron-containing materials required is M 含铁料 = 46.9 + 48×[w(Si) - 0.80] kg / t;

[0054] Where M 含铁料 is the addition amount of iron-containing materials, w(Si) is the mass fraction of Si in the molten iron, and t is the weight of the molten iron charged.

[0055] Specifically, in step S2, for limestone, calculated by mass percentage, the CaO content is 52 - 55%, SiO2 < 1.6%, and the addition amount is M 石灰石 = 6.9 + 11.5×[w(Si) - 0.60] kg / t;

[0056] Where M 石灰石 is the addition amount of limestone.

[0057] Specifically, in step S3, the molten iron is charged and scrap steel is added, and the ratio of molten iron is controlled at 0.875 - 0.906, and it is required that the temperature of the molten iron ≥ 1300°C.

[0058] It should be noted that the present invention needs to control the ratio of molten iron and the temperature of the molten iron to ensure that the heat in the furnace can meet the addition of iron-containing materials to ensure the final addition amount of iron-containing materials.

[0059] Specifically, in step S4, for lime, calculated by mass percentage, the CaO content is 90% - 92%, SiO2 < 1.2%, and the addition amount is M 石灰 = 5.51 + 11.5×[w(Si) - 0.60] kg / t;

[0060] where M 石灰 is the addition amount of lime.

[0061] Specifically, in step S4, the lance position is controlled at 1.4 - 1.55 m, and in step S5, the lance position is controlled at 1.25 - 1.4 m.

[0062] In step S6, the heat is tapped and samples are taken, and the tapping temperature is required to be controlled at 1350 - 1420 °C.

[0063] It should be noted that the purpose of this method is to promote the stirring of the molten bath by increasing the bottom blowing flow rate of the converter. The front and back tilting of the furnace can stir the molten steel and slag to fully react, promote the rapid separation of the steel slag, and reduce the loss caused by the amount of molten steel carried out during the early slag tapping process.

[0064] Specifically, when in step S2, 0.60% < Si ≤ 0.70% and S < 0.035% in the hot metal, the lime dosage in step S7 is M 石灰 = 11.56 + 36.1×[w(Si) - 0.60] kg / t;

[0065] When in step S2, 0.70% < Si ≤ 0.80% and S < 0.035% in the hot metal, the lime dosage in step S7 is M 石灰 = 15.17 + 20.8×[w(Si) - 0.70] kg / t;

[0066] When in step S2, 0.80% < Si ≤ 0.90% and S < 0.035% in the hot metal, the lime dosage in step S7 is M 石灰 = 17.25 + 20.6×[w(Si) - 0.80] kg / t.

[0067] The dosage of calcined dolomite is M 生白云石 = 13.8 + 22.9×[w(Si) - 0.60] kg / t, and the dosage of magnesium balls is M 镁球 = 5.5 - 6.8×[w(Si) - 0.60] kg / t

[0068] Specifically, in the said step S7, it is required that the basicity R of the final slag > 2.6, and the mass percentage content of MgO in the slag > 8%.

[0069] To describe the present invention more clearly, it is further illustrated by the following examples and comparative examples.

[0070] Example 1

[0071] A smelting method for increasing the steel output by adding iron-containing materials in the early stage of the converter double slag method, comprising the following steps:

[0072] It is implemented on a 150t top and bottom blown converter. The slag basicity of the previous furnace is 2.74. 50% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0073] The main components of the molten iron added to this furnace are Si=0.90%, Mn=0.27%, P=0.112%, S=0.032% by mass, and the weight of the molten iron is 144t;

[0074] After the slag splashing furnace protection operation is completed, limestone and iron-containing materials are added as bottom materials and spread on the bottom of the furnace according to the composition and weight of the molten iron to be added. The iron-containing material is 28% of the required total amount; the iron-containing material is required to be calculated by mass percentage as H2O=1.1%, TFe=53.8%, SiO2=7.6%, CaO=22.7%; the limestone is calculated by mass percentage as CaO=52.85%, SiO2=1.45%;

[0075] By calculating the amount of limestone added: M 石灰石 ={6.9+11.5×[0.90-0.60]}×144t=1.49t;

[0076] The amount of iron-containing material added is M 含铁料 ={46.9+48×[0.90-0.80]}×144t×28%=2.1t

[0077] Add molten iron, add 16t of scrap steel, control the iron-to-water ratio at 0.90, and the molten iron temperature = 1304℃;

[0078] The oxygen lance is ignited for blowing. After the oxygen ramp is completed and blowing is completed for 30 seconds, 54% of the total amount of lime and iron-containing materials required is added for further slagging and decarburization. The oxygen lance position is controlled at 1.4-1.55m.

[0079] By calculating the amount of lime added as M 石灰 ={5.51+11.5×[0.90-0.60]}×144t=1.29t;

[0080] The amount of iron-containing material added is M 含铁料 ={46.9+48×[0.90-0.80]}×144t×54%=4.0t;

[0081] After blowing for 256 seconds, when the CO recovery rate reaches 4.09% according to the flame reaction, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.25-1.4m;

[0082] During the slag pouring operation, set the converter bottom blowing flow rate to 0.055-0.075Nm 3 / (t·min), first shake the furnace to -48° in the direction of steel tapping, then shake the furnace forward to pour slag, the slag pouring amount is 55%, measure the temperature and take samples, the TFe content in the early slag is 23.2%, the basicity is 1.69, and the temperature is 1389℃;

[0083] After the slag is poured, the lance is lowered for blowing again. Within the total blowing time of 8 minutes, the remaining iron-containing materials, lime, raw dolomite and magnesium balls are added in batches according to the furnace conditions;

[0084] By calculating the amount of lime added: M 石灰 ={17.25+20.6×[0.90-0.80]}×144t=2.78t;

[0085] The remaining iron-containing material addition amount is M 含铁料 ={46.9+48×[0.90-0.80]}×144t×18%=1.3t;

[0086] The amount of raw dolomite is M 生白云石 ={13.8+22.9×[0.90-0.60]}×144t=2.98t, the amount of magnesium ball is M 镁球 ={5.5-6.8×[0.90-0.60]}×144t=0.5t;

[0087] The dosage of limestone, raw dolomite and magnesium balls is adjusted according to the smelting conditions, and the final slag basicity R>2.6 and MgO>8% are required to ensure effective dephosphorization at the final point and maintain the stability of the furnace condition;

[0088] The end point temperature of smelting is 1659°C; the end point slag basicity is 2.67, the TFe content in the end point slag is 14.8%, and the end point P of smelting is 0.021%.

[0089] Example 2

[0090] A smelting method for increasing the output of steel by adding iron-containing materials in the early stage of a converter double-slag process comprises the following steps:

[0091] It is implemented on a 150t top and bottom blown converter. The slag basicity of the previous furnace is 2.72. 55% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0092] The main components of the molten iron added to this furnace are Si=0.64%, Mn=0.22%, P=0.113%, S=0.026% by mass, and the weight of the molten iron is 144.5t;

[0093] After the slag splashing furnace protection operation is completed, limestone and iron-containing materials are added as bottom materials and spread on the bottom of the furnace according to the composition and weight of the molten iron to be added. The iron-containing material is 22% of the required total amount; the iron-containing material is required to be calculated by mass percentage as H2O=1.1%, TFe=53.8%, SiO2=7.6%, CaO=22.7%; the limestone is calculated by mass percentage as CaO=52.85%, SiO2=1.45%;

[0094] By calculating the amount of limestone added as M 石灰石 ={6.9+11.5×[0.64-0.60]}×144.5t=1.06t

[0095] The amount of iron-containing material added is M 含铁料 ={34.5+70×[0.64-0.60]}×144.5t×22%=5.4t×22%=1.19t;

[0096] Add molten iron, add 15t of scrap steel, control the iron-to-water ratio at 0.906, and the molten iron temperature = 1324℃;

[0097] The oxygen lance is ignited for blowing. After the oxygen ramp is completed and blowing is completed for 30 seconds, 55% of the total amount of lime and iron-containing materials required is added for further slagging and decarburization. The oxygen lance position is controlled at 1.4-1.55m.

[0098] By calculating the amount of lime added: M 石灰 ={5.51+11.5×[0.64-0.60]}×144.5t=0.86t;

[0099] The amount of iron-containing material added is M 含铁料 ={34.5+70×[0.64-0.60]}×144.5t×55%=5.4t×55%=2.97t;

[0100] After blowing for 248 seconds, when the CO recovery rate reaches 3.58% according to the flame reaction, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.25-1.4m;

[0101] During the slag pouring operation, set the converter bottom blowing flow rate to 0.055-0.075Nm 3 / (t·min), first shake the furnace to -45° in the direction of steel tapping, then shake the furnace forward to pour slag, the slag pouring amount is 50%, measure the temperature and take samples, the TFe content in the early slag is 21.5%, the basicity is 1.48, and the temperature is 1390℃;

[0102] After the slag is poured, the lance is lowered for blowing again. Within the total blowing time of 8 minutes, the remaining iron-containing materials and lime, limestone, raw dolomite and magnesium balls are added in batches according to the furnace conditions;

[0103] By calculating the amount of lime added: M 石灰 ={11.56+36.1×[0.64-0.60]}×144.5t=1.88t;

[0104] The remaining iron-containing material addition amount is M 含铁料 ={34.5+70×[0.64-0.60]}×144.5t×23%=1.24t;

[0105] The amount of raw dolomite is M 生白云石 ={13.8+22.9×[0.64-0.60]}×144.5t=2.13t, the amount of magnesium ball is M 镁球 ={5.5-6.8×[0.64-0.60]}×144.5t=0.76t;

[0106] The dosage of limestone, raw dolomite and magnesium balls is adjusted according to the smelting conditions, and the final slag basicity R>2.6 and MgO>8% are required to ensure effective dephosphorization at the final point and maintain the stability of the furnace condition;

[0107] The end point temperature of smelting is 1664°C; the end point slag basicity is 2.59, the TFe content in the end point slag is 14.1%, and the end point P of smelting is 0.020%.

[0108] Example 3

[0109] A smelting method for increasing the output of steel by adding iron-containing materials in the early stage of a converter double slag method comprises the following steps:

[0110] It is implemented on a 150t top and bottom double-blown converter. The slag basicity of the previous furnace is 2.64. 50% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0111] The main components of the molten iron added to this furnace are Si=0.70%, Mn=0.24%, P=0.108%, S=0.028% by mass, and the weight of the molten iron is 144t;

[0112] After the slag splashing furnace protection operation is completed, limestone and iron-containing materials are added as bottom materials and spread on the bottom of the furnace according to the composition and weight of the molten iron to be added. The iron-containing material is 25% of the required total amount; the iron-containing material is required to be calculated by mass percentage as H2O=1.1%, TFe=53.8%, SiO2=7.6%, CaO=22.7%; the limestone is calculated by mass percentage as CaO=52.85%, SiO2=1.45%;

[0113] By calculating the amount of limestone added as M 石灰石 ={6.9+11.5×[0.70-0.60]}×144t=1.16t;

[0114] The amount of iron-containing material added is M 含铁料 ={34.5+70×[0.70-0.60]}×144t×25%=5.98t×25%=1.49t;

[0115] Add molten iron, add 16t of scrap steel, control the iron-to-water ratio at 0.90, and the molten iron temperature = 1304℃;

[0116] The oxygen lance is ignited for blowing. After the oxygen ramp is completed and blowing is completed for 30 seconds, 50% of the total amount of lime and iron-containing materials required is added for further slagging and decarburization. The oxygen lance position is controlled at 1.4-1.55m.

[0117] By calculating the amount of lime added as M 石灰 ={5.51+11.5×[0.70-0.60]}×144t=0.96t;

[0118] The amount of iron-containing material added is M 含铁料 ={34.5+70×[0.70-0.60]}×144t×50%=5.98t×50%=3.0t,

[0119] After blowing for 237 seconds, when the CO recovery rate reaches 3.12% according to the flame reaction, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.25-1.4m;

[0120] During the slag pouring operation, set the converter bottom blowing flow rate to 0.055-0.075Nm 3 / (t·min), first shake the furnace to -50° in the direction of steel tapping, then shake the furnace forward to pour slag, the slag pouring amount is 55%, measure the temperature and take samples, the TFe content in the early slag is 22.3%, the basicity is 1.38, and the temperature is 1395℃;

[0121] After the slag is poured, the lance is lowered for blowing again. Within the total blowing time of 8 minutes, the remaining iron-containing materials and lime, limestone, raw dolomite and magnesium balls are added in batches according to the furnace conditions;

[0122] By calculating the amount of lime added: M 石灰 ={11.56+36.1×[0.70-0.60]}×144t=2.18t;

[0123] The remaining iron-containing material addition amount is M 含铁料 ={34.5+70×[0.70-0.60]}×144t×25%=1.50t,

[0124] The amount of raw dolomite is M 生白云石 ={13.8+22.9×[0.70-0.60]}×144t=2.31t, the amount of magnesium ball is M 镁球={5.5-6.8×[0.70-0.60]}×144t=0.69t;

[0125] The dosage of limestone, raw dolomite and magnesium balls is adjusted according to the smelting conditions, and the final slag basicity R>2.6 and MgO>8% are required to ensure effective dephosphorization at the end point and maintain the stability of the furnace condition.

[0126] The end point temperature of smelting is 1655°C; the end point slag basicity is 2.63, the TFe content in the end point slag is 14.4%, and the end point P of smelting is 0.020%.

[0127] Example 4

[0128] A smelting method for increasing the output of steel by adding iron-containing materials in the early stage of a converter double slag method comprises the following steps:

[0129] It is implemented on a 150t top and bottom blown converter. The slag basicity of the previous furnace is 2.81. 50% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0130] The main components of the molten iron added to this furnace are Si=0.80%, Mn=0.25%, P=0.111%, S=0.020% by mass, and the weight of the molten iron is 142t;

[0131] After the slag splashing furnace protection operation is completed, limestone and iron-containing materials are added as bottom materials and spread on the bottom of the furnace according to the composition and weight of the molten iron to be added. The iron-containing material is 30% of the required total amount; the iron-containing material is required to be calculated by mass percentage as H2O=1.1%, TFe=53.8%, SiO2=7.6%, CaO=22.7%; the limestone is calculated by mass percentage as CaO=52.85%, SiO2=1.45%;

[0132] By calculating the amount of limestone added as M 石灰石 ={6.9+11.5×[0.80-0.60]}×144t=1.3t

[0133] The amount of iron-containing material added is M 含铁料 ={41.5+54×[0.80-0.70]}×142t×30%=6.66t×30%=2.0t;

[0134] Add molten iron, add 18t of scrap steel, control the iron-to-water ratio at 0.89, and the molten iron temperature = 1320℃;

[0135] The oxygen lance is ignited for blowing. After the oxygen ramp is completed and blowing is completed for 30 seconds, 57% of the total amount of lime and iron-containing materials required are added for further slagging and decarburization. The oxygen lance position is controlled at 1.4-1.55m.

[0136] By calculating the amount of lime added as M 石灰 ={5.51+11.5×[0.80-0.60]}×144t=1.11t;

[0137] The amount of iron-containing material added is M 含铁料 ={41.5+54×[0.80-0.70]}×142t×57%=3.8t,

[0138] After blowing for 262 seconds, when the CO recovery rate reaches 4.43% according to the flame reaction, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.25-1.4m;

[0139] During the slag pouring operation, set the converter bottom blowing flow rate to 0.055-0.075Nm 3 / (t·min), first shake the furnace to -50° in the direction of steel tapping, then shake the furnace forward to dump slag, the slag dumping amount is 55%, measure the temperature and take samples, the TFe content in the early slag is 24.2%, the basicity is 1.34, and the temperature is 1401℃;

[0140] After the slag is poured, the lance is lowered for blowing again. Within the total blowing time of 8 minutes, the remaining iron-containing materials, lime, raw dolomite and magnesium balls are added in batches according to the furnace conditions;

[0141] By calculating the amount of lime added as M 石灰 ={15.17+20.8×[0.80-0.70]}×142t=2.45t;

[0142] The amount of iron-containing material added is M 含铁料 ={41.5+54×[0.80-0.70]}×142t×13%=0.87t;

[0143] The amount of raw dolomite is M 生白云石 ={13.8+22.9×[0.80-0.60]}×142t=2.61t, the amount of magnesium ball is M 镁球 ={5.5-6.8×[0.80-0.60]}×142t=0.58t;

[0144] The dosage of limestone, raw dolomite and magnesium balls is adjusted according to the smelting conditions, and the final slag basicity R>2.6 and MgO>8% are required to ensure effective dephosphorization at the final point and maintain the stability of the furnace condition;

[0145] The end point temperature of smelting is 1652°C; the end point slag basicity is 2.79, the TFe content in the end point slag is 13.8%, and the end point P of smelting is 0.018%.

[0146] Comparative Example 1

[0147] Comparative Example 1 is a smelting process of an existing double slag method, comprising the following steps:

[0148] It is implemented on a 150t top and bottom blown converter. The slag basicity of the previous furnace is 2.74. 80% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0149] The main components of the molten iron added to this furnace are Si=0.62%, Mn=0.22%, P=0.110%, S=0.030% by mass percentage;

[0150] 143.5t of molten iron and 17t of scrap steel were added, and the temperature of the molten iron was 1325℃;

[0151] The oxygen lance is ignited for blowing. After blowing for 60 seconds, 0.42t of lime, 0.55t of limestone and 1.2t of iron-containing material (30% of the total amount added) are added.

[0152] After blowing for 186 seconds, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.25-1.4m;

[0153] During the slag pouring operation, the converter bottom blowing flow rate is 0.025-0.035Nm 3 / (t·min), shake the furnace to pour slag in front of the furnace, the slag pouring amount is 60%, measure the temperature and take samples, the TFe content in the early slag is 38.98%, and the basicity is 1.42;

[0154] After the slag is poured, the gun is blown again. Within 10 minutes of the total blowing time, 2.85 tons of iron-containing materials (70% of the total amount added), 3.42 tons of lime, 1.24 tons of limestone, and 0.82 tons of magnesium balls are added in batches;

[0155] The end point temperature of smelting is 1660°C; the end point slag basicity is 2.62, the TFe content in the end point slag is 13.2%, and the end point P of smelting is 0.031%.

[0156] Comparative Example 2

[0157] The smelting process of Comparative Example 2 comprises the following steps:

[0158] It is implemented on a 150t top and bottom blown converter. The slag basicity of the previous furnace is 2.61. 20% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0159] The main components of the molten iron added to this furnace are Si=0.71%, Mn=0.23%, P=0.100%, S=0.024% by mass percentage;

[0160] Add 145t of molten iron and 15t of scrap steel, the temperature of the molten iron is 1305℃;

[0161] The oxygen lance is ignited for blowing. After blowing for 60 seconds, 1.14 tons of lime, 0.85 tons of limestone, and 2.2 tons of iron-containing materials (50% of the total amount added) are added.

[0162] After blowing for 256 seconds, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.35-1.50m;

[0163] During the slag pouring operation, the converter bottom blowing flow rate is 0.025-0.035Nm 3 / (t·min), shake the furnace to pour slag in front of the furnace, the slag pouring amount is 50%, measure the temperature and take samples, the TFe content in the early slag is 35.7%, and the basicity is 1.17;

[0164] After the slag is poured, the lance is blown again. Within 10 minutes of the total blowing time, 2.2 tons of iron-containing materials (50% of the total amount added), 3.38 tons of lime, 1.93 tons of limestone, and 3.1 tons of raw dolomite are added in batches;

[0165] The end point temperature of smelting is 1664°C; the end point slag basicity is 2.65, the TFe content in the end point slag is 12.8%, and the end point P of smelting is 0.034%.

[0166] Comparative Example 3

[0167] The smelting process of Comparative Example 3 comprises the following steps:

[0168] It is implemented on a 150t top and bottom blown converter. The slag basicity of the previous furnace is 2.79. 80% of the slag from the previous furnace is left in the furnace to perform slag splashing and furnace protection operation.

[0169] The main components of the molten iron added to this furnace are Si=0.79%, Mn=0.22%, P=0.103%, S=0.034% by mass percentage;

[0170] Add 145t of molten iron and 15t of scrap steel, the temperature of the molten iron is 1320℃;

[0171] The oxygen lance is ignited for blowing. After blowing for 50 seconds, 0.33t of lime, 1.27t of raw dolomite and 1.0t of iron-containing material (40% of the total amount added) are added.

[0172] After blowing for 216 seconds, the lance is raised to prepare for slag dumping, and the oxygen lance position is controlled at 1.35-1.45m;

[0173] During the slag pouring operation, the converter bottom blowing flow rate is 0.025-0.035Nm 3 / (t·min), shake the furnace to pour slag in front of the furnace, the slag pouring amount is 60%, measure the temperature and take samples, the TFe content in the early slag is 37.25%, and the basicity is 1.31;

[0174] After the slag is poured, the lance is blown again. Within 10 minutes of the total blowing time, 1.47 tons of iron-containing materials (60% of the total amount added), 2.45 tons of lime, 1.61 tons of limestone, and 3.20 tons of raw dolomite are added in batches;

[0175] The end point temperature of smelting is 1644°C; the end point slag basicity is 2.58, the TFe content in the end point slag is 13.9%, and the end point P of smelting is 0.018%.

[0176] Performance Testing

[0177] The TFe content in the early slag, the amount of iron-containing material added and the amount of steel produced in the above Examples 1-4 and Comparative Examples 1-3 were statistically analyzed, and the specific results are shown in Table 1.

[0178] Table 1 Test results

[0179]

[0180] It can be seen from Examples 1-4 of the present invention and Comparative Examples 1-3 and Table 1 that by adopting the smelting process provided by the embodiments of the present invention, the TFe content in the early slag can be reduced from 30% to 40% to 20% to 25%, thereby reducing the influence of the early slag pouring of the double slag method on the loss of molten steel. Adding more than 70% of the iron-containing material into the furnace before the early slag pouring can reduce the amount of slag-making material added after the slag pouring and stabilize the reaction in the furnace. The present invention can increase the steel output by 10-15 kg / t on the original basis and obtain better economic benefits.

[0181] 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 smelting method for increasing the output of steel by adding iron-containing materials in the early stage of the converter double slag process, characterized in that: The steps include: S1: Leave 50% to 60% of the slag from the previous furnace in the converter; S2: According to the composition and weight of the molten iron to be added, limestone and iron-containing materials are added as base materials and spread on the bottom of the furnace. The required iron-containing materials are 20%-30% of the total amount; the composition of the molten iron is Si>0.60%, Mn<0.50%, 0.08%<P<0.12%, 0.002%<S<0.035% by mass percentage; S3: Add molten iron and scrap steel, the iron-to-water ratio is controlled at 0.875-0.906, and the molten iron temperature is required to be ≥1300℃. S4: The oxygen lance is ignited for blowing. After 30 seconds of oxygen ramping and blowing, lime and 50%-60% of the total amount of required iron-containing materials are added; S5: After blowing for about 240 seconds, when the CO recovery in the flue gas recovery system reaches 3%-5%, the gun is raised to prepare for slag dumping; S6: During the slag pouring operation, set the converter bottom blowing flow rate to 0.055-0.075Nm 3 / (t·min), first shake the furnace to -40°~-50° in the direction of steel tapping, then shake the furnace forward to dump slag, and control the amount of slag dumping to more than 50%; S7: After the slag is poured, the gun is lowered for blowing again. Within the total blowing time of 8 minutes, the remaining iron-containing materials, lime, raw dolomite and magnesium balls are added.

2. The smelting method according to claim 1, characterized in that: In step S1, the final slag of the previous furnace is required to have a basicity R>2.6, and the final molten steel C content of the previous furnace is required to be>0.08%, and the final temperature T<1650°C.

3. The smelting method according to claim 1, characterized in that: The iron-containing material is required to be H2O<1.5%, 50% by mass percentage. <TFe<55%,SiO2<8%,CaO> 18%.

4. The smelting method according to claim 1, characterized in that: In step S2, when the molten iron has 0.60% < Si ≤ 0.70% and S < 0.035%, the total amount of iron-containing materials required is M 含铁料 = 34.5 + 70×[w(Si) - 0.60] kg / t; When the silicon content of hot metal is 0.70% < Si ≤ 0.80% and sulfur content S < 0.035%, the total amount of iron-containing materials required is M 含铁料 = 41.5 + 54×[w(Si) - 0.70] kg / t; When the molten iron has 0.80% < Si ≤ 0.90% and S < 0.035%, the total amount of iron-containing materials required is M 含铁料 = 46.9 + 48×[w(Si) - 0.80] kg / t; Among them, M 含铁料 is the amount of iron-containing material added, w(Si) is the mass fraction of Si in molten iron, and t is the weight of molten iron added.

5. The smelting method according to claim 1, characterized in that: In step S2, the limestone has a CaO content of 52-55% and SiO2 <1.6% by mass, and the added amount is M 石灰石 =6.9+11.5×[w(Si)-0.60]kg / t; Among them, M 石灰石 is the amount of limestone added.

6. The smelting method according to claim 1, characterized in that: In step S4, the lime is added in an amount of M based on the mass percentage, with a CaO content of 90%-92% and SiO2 <1.2%. 石灰 =5.51+11.5×[w(Si)-0.60]kg / t; Among them, M 石灰 is the amount of lime added.

7. The smelting method according to claim 1, characterized in that: In step S6, the furnace temperature is measured and sampled, and the furnace temperature is required to be controlled at 1350-1420°C.

8. The smelting method according to claim 1, characterized in that: When in step S2, 0.60% < Si ≤ 0.70% in hot metal and S < 0.035%, the lime dosage in step S7 is M 石灰 = 11.56 + 36.1×[w(Si) - 0.60] kg / t; When in step S2, 0.70% < Si ≤ 0.80% in the molten iron and S < 0.035%, the amount of lime used in step S7 is M 石灰 = 15.17 + 20.8×[w(Si) - 0.70] kg / t; When in step S2, 0.80% < Si ≤ 0.90% in the hot metal and S < 0.035%, the amount of lime used in step S7 is M 石灰 = 17.25 + 20.6 × [w(Si) - 0.80] kg / t; The amount of raw dolomite is M 生白云石 =13.8+22.9×[w(Si)-0.60]kg / t, the amount of magnesium ball is M 镁球 =5.5-6.8×[w(Si)-0.60]kg / t.

9. The smelting method according to claim 1, characterized in that: In step S4, the oxygen lance position is controlled at 1.4-1.55 m, and in step S5, the oxygen lance position is controlled at 1.25-1.4 m.

10. The smelting method according to claim 1, characterized in that: In step S7, it is required that the final slag basicity R>2.6 and the mass percentage of MgO in the slag>8%.

Images