Smelting methods to reduce the total iron content in the final slag of a top-and-bottom blown converter

Abstract

This invention discloses a smelting method for reducing the total iron content in the final slag of a top-and-bottom combined blowing converter. The method involves: measuring the total slag concentration (TSC) during the later stages of blowing, and calculating the secondary oxygen blowing amount (V) required to reach the blowing endpoint based on the TSC measurement results. sce If V sce >1000Nm 3 Furthermore, after TSC measurement, the top and bottom lances have supplied oxygen V into the furnace. f <V sce -1000Nm 3 Then the flow rate ratio r between bottom oxygen supply and top oxygen supply should be controlled between 0.1 and 0.5; if 300 Nm 3 ≤V sce ≤1000Nm 3 or V f ≥V sce -1000Nm 3 The flow rate ratio r between bottom and top oxygen supply is controlled between 0.3 and 0.9, and the bottom oxygen supply pressure is controlled between 0.4 MPa and 0.9 MPa. This method establishes a mathematical model for the top and bottom oxygen supply flow rate ratio and the endpoint control scheme, and derives an independent dynamic control scheme for the top and bottom oxygen supply flow rates and the top and bottom stopping of blowing at the blowing endpoint.

Description

Technical Field

[0001] This invention relates to the field of iron and steel smelting, and in particular to a smelting method for reducing the total iron content in the final slag of a top-and-bottom combined blowing converter. Background Technology

[0002] The total iron content in the final slag reflects the level of converter smelting technology and the quality of the product. It not only affects the cleanliness of molten steel and the consumption of steelmaking materials, but also plays a dominant role in controlling the C, Mn, and P components of molten steel at the final blowing stage. Reducing the total iron content in the final slag helps to reduce oxide inclusions in molten steel, inhibit refractory material loss in the converter, and reduce deoxidizer consumption. Therefore, reducing the total iron content in the final slag is an indispensable path to improving the process level, reducing production costs, and increasing production efficiency in the converter process.

[0003] The top-and-bottom blowing converter process enhances molten pool agitation through bottom blowing, bringing the chemical reactions within the molten pool closer to equilibrium and promoting uniform composition and temperature. Especially for strongly agitated top-blown converters with bottom-blown oxygen and bottom-injection powder functions, this can significantly reduce the carbon-oxygen product of the molten steel at the blowing endpoint and the oxidizability of the final slag, improving product quality. However, endpoint control in bottom-blown oxygen and bottom-injection converters typically involves simultaneously stopping oxygen supply from both the top and bottom, followed by bottom-blown inert gas agitation. This primarily relies on argon gas agitation to strengthen the gold-slag interface reaction, reducing the total iron content of the final slag by reducing FeO in the slag through C, P, and other easily oxidized elements in the molten pool. However, after the oxygen supply stops, the molten pool temperature rises, and the increased oxidizability accelerates the erosion of the furnace bottom refractory material by the molten steel under argon gas agitation. Furthermore, to obtain even lower total iron content in the final slag, it is necessary to further extend the argon gas agitation time or increase the gas flow rate, at the cost of accelerated wear on the furnace bottom refractory material and a shortened furnace bottom life. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a smelting method for reducing the formation of FeO in the slag at the end of the blowing process and accelerating the consumption of FeO in the slag, thereby reducing the total iron content in the final slag of the top and bottom combined blowing converter.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: to measure TSC in the later stage of blowing, and to calculate the secondary oxygen blowing amount V required to reach the end of blowing based on the TSC measurement results. sce ;

[0006] 1.1) If V sce >1000Nm 3 After TSC measurement, the top and bottom lances have supplied oxygen V into the furnace. f <V sce -1000Nm 3 The flow rate ratio r between bottom oxygen supply and top oxygen supply should be controlled between 0.1 and 0.5.

[0007] When Vf ≥V sce -1000Nm 3 The flow rate ratio r between bottom oxygen supply and top oxygen supply should be controlled between 0.3 and 0.9.

[0008] 1.2) If 300 Nm 3 ≤V sce ≤1000Nm 3 The flow rate ratio r between bottom oxygen supply and top oxygen supply should be controlled between 0.3 and 0.9.

[0009] 2.1) If V sce >1000Nm 3 The oxygen supply V from the top of the TSC test to the end of the blowing process. t and the duration of oxygen supply from the top T t Calculated using equations (2) and (3) respectively:

[0010] V t =F t *(1000-t b *F b / 60) / (F b +F t )+F T *(V sce -1000) / (F B +F T (2);

[0011] T t =60*((1000-t) b *F b / 60) / (F b +F t )+(V sce -1000) / (F B +F T )) (3);

[0012] 2.2) If 300 ≤ Vsce ≤ 1000 Nm 3 The oxygen supply V from the top of the TSC measurement to the end of the blowing process. t and the duration of oxygen supply from the top T t Calculated using equations (4) and (5) respectively;

[0013] V t =F t *(V sce -t b *F b / 60) / (F b +F t (4);

[0014] Tt =60*(V sce -t b *F b / 60) / (F b +F t (5);

[0015] 2.3) Bottom oxygen supply V from TSC measurement to the end of blowing b and bottom oxygen supply duration T b Calculate using equations (6) and (7) respectively:

[0016] V b =V sce -V t (6);

[0017] T b =T t +t b (7);

[0018] In the above formula, V t Oxygen supply to the top, Nm 3 When V f <V sce -1000Nm 3 The oxygen supply flow rate at the top is denoted as F. T Nm 3 / min, bottom oxygen supply flow rate is recorded as F B Nm 3 / min; when V f ≥V sce -1000Nm 3 The oxygen supply flow rate at the top is denoted as F. t Nm 3 / min, bottom oxygen supply flow rate is recorded as F b Nm 3 / min;t b The time difference between bottom oxygen supply and top oxygen supply, in seconds; T t Oxygen supply duration at the top, in seconds; V b The bottom oxygen supply (Nm) after TSC measurement 3 ;T b The duration of oxygen supply to the bottom after TSC measurement is s.

[0019] Furthermore, in 1.1), when V f <V sce -1000Nm 3 At that time, the oxygen supply flow rate at the bottom is F B Controlled at 65 Nm 3 / min~280Nm 3 / min, pressure controlled between 0.4 MPa and 0.9 MPa, top oxygen supply flow rate F T Controlled at 550 Nm 3 / min~650Nm 3 / min, pressure controlled at 16Mpa~18Mpa;

[0020] When V f ≥V sce -1000Nm 3 At that time, the bottom oxygen supply pressure is controlled at 0.4 MPa to 0.9 MPa, and the top oxygen supply flow rate F t Controlled at 300 Nm 3 / min~600Nm 3 / min, pressure controlled between 10Mpa and 17Mpa.

[0021] Furthermore, in section 1.2), the bottom oxygen supply pressure is controlled between 0.4 MPa and 0.9 MPa, and the top oxygen supply flow rate F t Controlled at 300 Nm 3 / min~600Nm 3 / min, pressure controlled between 10Mpa and 17Mpa.

[0022] Furthermore, in section 1.2), when the bottom oxygen supply flow rate is 65 Nm³... 3 / min≤F b <200Nm 3 / min, the difference t between bottom oxygen supply time and top oxygen supply time b The value ranges from 60 to 90 seconds.

[0023] When the bottom oxygen supply flow rate is 200 Nm 3 / min≤F b ≤280Nm 3 / min, the difference t between bottom oxygen supply time and top oxygen supply time b The relationship between the r value and the r value is satisfied by the following equation (1):

[0024] t b =a*e (-r / b) +c (1);

[0025] In the formula: a, b and c are all constants; the value of a ranges from 9000 to 20000, the value of b ranges from 0.07 to 0.08, and the value of c is 2.5.

[0026] The beneficial effects of adopting the above technical solution are as follows:

[0027] 1. This invention can dynamically adjust based on the TSC measurement results at the end of the blowing process, and establishes a mathematical model for the top and bottom oxygen supply flow ratio and the endpoint control scheme. Based on different bottom and top oxygen supply flow ratios, it quantitatively derives the top and bottom oxygen supply flow and the independent dynamic control scheme for the top and bottom stopping of blowing at the end of the blowing process.

[0028] 2. In the final stage of blowing, this invention reduces the total iron content in the final slag by reducing the oxidation reaction of the slag through top oxygen supply and increasing the proportion of bottom oxygen supply to enhance the reduction reaction of FeO at the gold-slag interface. Taking advantage of the greater stirring intensity and more complete reaction in the furnace by bottom blowing oxygen, the top oxygen flow rate of the converter is reduced in the final stage of blowing to reduce the supply of FeO to the slag by the bottom oxygen lance. At the same time, the bottom oxygen flow rate and proportion are relatively increased in the final stage of blowing. Bottom blowing oxygen stirring promotes the reduction reaction of FeO at the gold-slag interface, improves the oxygen efficiency of decarburization and phosphorus removal, consumes FeO in the slag, and further reduces the total iron content in the final slag.

[0029] 3. This invention increases the ratio of bottom to top oxygen supply flow rates at the end of the blowing process, promoting the dephosphorization reaction between FeO and P at the gold slag interface. Therefore, while ensuring dephosphorization efficiency, it can reduce converter ash consumption and save costs. Furthermore, compared to the endpoint control scheme of simultaneously stopping top and bottom oxygen blowing and then using bottom-blowing argon stirring, this invention employs independent dynamic stopping control of top and bottom blowing, eliminating the argon stirring step. This shortens the process flow, reduces argon consumption, and avoids increased furnace bottom wear caused by stirring, thus helping to extend furnace bottom life. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to specific embodiments.

[0031] The design concept of this smelting method for reducing the total iron content in the final slag of a top-and-bottom combined blowing converter is as follows: At the end of the blowing process, the oxidation reaction of the slag is weakened by reducing the top oxygen supply intensity, as shown in reaction formula (Ⅰ), thereby reducing the formation of FeO in the slag. Simultaneously, the FeO reduction reaction at the gold-slag interface is enhanced by bottom oxygen supply stirring, as shown in reaction formula (Ⅱ), or by other elements in the molten pool reducing FeO, thus accelerating the consumption of FeO in the slag. Based on the above idea of ​​reducing FeO formation in the slag at the end of the blowing process while simultaneously accelerating FeO consumption, a new method for reducing the total iron content in the final slag by adjusting the oxygen supply intensity of the top-and-bottom combined blowing converter is proposed.

[0032] 2[Fe] + O₂ = 2FeO (Ⅰ)

[0033] FeO + [C] = CO(II).

[0034] This smelting method for reducing the total iron content in the final slag of a top-and-bottom combined blowing converter is best achieved using a 260-ton combined blowing converter with oxygen injection capability at the bottom. The oxygen supply intensity is dynamically adjusted based on TSC (Total Stress Calorie) measurements at the end of the blowing process. The top and bottom oxygen supply shutdowns are independently controlled at the end of the blowing process, and the inert gas stirring step after oxygen shutdown is eliminated, thus reducing the total iron content in the final slag and increasing metal yield. Specifically, the ratio of bottom to top oxygen flow rates is adjusted in the later stages of blowing, and the timing for stopping top and bottom oxygen supply is calculated based on the oxygen flow rates to formulate an endpoint control plan. The bottom and top oxygen flow rates are selected based on the secondary oxygen blowing volume, which is calculated by the secondary system based on TSC measurement results.

[0035] The process for reducing the final slag total iron in a top-and-bottom combined blowing converter is as follows: 1) Bottom oxygen supply flow rate F B Controlled at 65 Nm 3 / min~280Nm 3 The oxygen flow rate is controlled at 0.4 MPa to 0.9 MPa per minute. The total oxygen concentration (TSC) is measured during the later stages of the blowing process, and the required secondary oxygen flow rate (V) to reach the blowing endpoint is calculated based on the TSC results. sce ; and according to V sce The value is selected as the flow ratio of bottom oxygen supply to top oxygen supply. After TSC measurement, the bottom oxygen supply time to the blowing end is greater than or equal to the top oxygen supply time.

[0036] 1.1) If V sce >1000Nm 3 Then it shall be controlled as follows:

[0037] 1.1.1) After TSC measurement, the top and bottom lances have supplied oxygen V into the furnace. f <V sce -1000Nm 3 Therefore, the flow rate ratio r between bottom oxygen supply and top oxygen supply should be controlled between 0.1 and 0.5. Top oxygen supply flow rate F T Controlled at 550 Nm 3 / min~650Nm 3 / min, pressure controlled at 16Mpa~18Mpa.

[0038] 1.1.2) When V f ≥V sce -1000Nm 3 The flow rate ratio (r) between bottom and top oxygen supply should be controlled between 0.3 and 0.9. The top oxygen supply flow rate (F) t Controlled at 300 Nm 3 / min~600Nm 3 / min, pressure controlled between 10MPa and 17MPa.

[0039] 1.2) If 300 Nm3 ≤V sce ≤1000Nm 3 Then it shall be controlled as follows:

[0040] The flow rate ratio (r) between bottom and top oxygen supply is controlled between 0.3 and 0.9, and the bottom oxygen supply pressure is controlled between 0.4 MPa and 0.9 MPa. The top oxygen supply flow rate (F) is... t Controlled at 300 Nm 3 / min~600Nm 3 / min, pressure controlled between 10MPa and 17MPa.

[0041] 1.2.1) When the bottom oxygen supply flow rate is 65 Nm³ 3 / min≤F b <200Nm 3 / min, the difference t between bottom oxygen supply time and top oxygen supply time b The value ranges from 60s to 90s.

[0042] 1.2.2) When the bottom oxygen supply flow rate is 200 Nm³ 3 / min≤F b ≤280Nm 3 / min, the difference t between bottom oxygen supply time and top oxygen supply time b The ratio r of the oxygen supply flow rate at the bottom to that at the top satisfies the following equation (1):

[0043] t b =a*e (-r / b) +c (1)

[0044] In the formula: a, b, and c are all constants; a ranges from 9000 to 20000, b ranges from 0.07 to 0.08, and c is 2.5; e is the natural constant, with a value of 2.71828; the value of r is taken from step 1.1.2) when V f ≥V sce -1000Nm 3 The value of r at that time.

[0045] 2) Based on the oxygen flow rate of the top lance and bottom lance, and the difference between the oxygen supply time of the bottom lance and the oxygen supply time of the top lance, calculate the oxygen supply amount of the top lance, the oxygen supply amount of the bottom lance, and the oxygen supply time of the top lance and the oxygen supply time of the bottom lance from the TSC measurement to the end of the blowing process, i.e. the timing of stopping the oxygen blowing of the top lance and bottom lance.

[0046] 2.1) If V sce >1000Nm 3 The oxygen supply V from the top of the TSC measurement to the end of the blowing process. t and the duration of oxygen supply from the top T t Calculated using equations (2) and (3) respectively:

[0047] V t =F t *(1000-t b *F b / 60) / (F b +F t )+F T *(V sce -1000) / (F B +F T (2);

[0048] T t =60*((1000-t) b *F b / 60) / (F b +F t )+(V sce -1000) / (F B +F T )) (3).

[0049] 2.2) If 300 Nm 3 ≤V sce ≤1000Nm 3 The oxygen supply V from the top of the TSC measurement to the end of the blowing process. t and the duration of oxygen supply from the top T t Calculated using equations (4) and (5) respectively;

[0050] V t =F t *(V sce -t b *F b / 60) / (F b +F t (4);

[0051] T t =60*(V sce -t b *F b / 60) / (F b +F t (5).

[0052] 2.3) Bottom oxygen supply V from TSC measurement to the end of blowing b and bottom oxygen supply duration T b Calculate using equations (6) and (7) respectively:

[0053] V b =V sce -V t (6);

[0054] T b =Tt +t b (7);

[0055] In the above formula, V t Oxygen supply at the top, in Nm³ 3 When V f <V sce -1000Nm 3 The oxygen supply flow rate at the top is denoted as F. T Unit Nm 3 / min, bottom oxygen supply flow rate is recorded as F B Unit Nm 3 / min. When V f ≥V sce -1000Nm 3 The oxygen supply flow rate at the top is denoted as F. t Unit Nm 3 / min, bottom oxygen supply flow rate is recorded as F b Unit Nm 3 / min. t b T represents the difference between bottom oxygen supply time and top oxygen supply time, in seconds. t Oxygen supply duration at the top, in seconds; V b The oxygen supply at the bottom from the TSC measurement to the end of the blowing process is expressed in Nm³. 3 ;T b The time for bottom oxygen supply from the TSC measurement to the end of the blowing process is measured in seconds.

[0056] 3) During the oxygen blowing process, the position of the oxygen lance supplied from the top is controlled at 3m to 4.5m, and there are 2 to 6 bottom lances at the bottom of the furnace. The basicity of the final slag of the converter is controlled at 2.8 to 3.5.

[0057] Example 1: The smelting method for reducing the total iron content of the final slag in a top-and-bottom combined blowing converter is described in detail below.

[0058] The basicity of the converter smelting slag is 3.0. The secondary oxygen blowing volume V is calculated after the TSC is measured in the later stage of blowing. sce 1500 Nm 3 There are 6 oxygen lances at the bottom of the furnace, with a total oxygen supply flow rate of 280 Nm³. 3 The oxygen supply rate is 0.90 MPa, and the oxygen supply pressure is 0.90 MPa. After TSC measurement, the oxygen supply from the top and bottom to the furnace is less than 500 Nm³. 3 Therefore, the oxygen lance position is 4.0m, and the oxygen supply flow rate from the top is 650Nm³. 3 / min, pressure 18MPa, bottom to top oxygen supply flow ratio r is 0.43; after TSC measurement, the oxygen supply from the top and bottom to the furnace exceeded 500Nm³. 3 The oxygen supply flow rate of the top oxygen lance is 450 Nm³. 3 / min, pressure 14MPa, the oxygen supply flow rate ratio r between the bottom and top is 0.62. Constants a and b are taken as 9000 and 0.075 respectively. t is calculated using equation (1). b =5s. F T =650Nm 3 / min、F B =F b =280Nm 3 / min、F t =500Nm 3 The oxygen supply V from the top oxygen lance at the end of the blowing process after TSC measurement is calculated using equations (2) and (3). t 952 Nm 3 Oxygen supply duration T t The oxygen supply V from the bottom oxygen lance is calculated using equations (6) and (7). b 548 Nm 3 Oxygen supply duration T b The time was 118s. The total iron content of the final slag was determined to be 13.4%.

[0059] Example 2: The specific smelting method for reducing the total iron content of the final slag in the top and bottom blown converter is as follows.

[0060] The basicity of the converter smelting slag is 3.0. The secondary oxygen blowing volume V is calculated after the TSC is measured in the later stage of blowing. sce 1400 Nm 3 There are 6 oxygen lances at the bottom of the furnace, with an oxygen supply flow rate of 240 Nm³. 3 The oxygen supply rate is 0.76 MPa per minute. After TSC measurement, the oxygen supply from the top and bottom to the furnace is less than 400 Nm³. 3 Therefore, the oxygen lance position is 4.0m, and the oxygen supply flow rate from the top is 550Nm³. 3 / min, pressure 16MPa, bottom to top oxygen supply flow ratio r is 0.44; after TSC measurement, the oxygen supply from the top and bottom to the furnace exceeded 400Nm³. 3 The oxygen supply flow rate of the top oxygen lance is 300 Nm³. 3 / min, pressure 10MPa, the oxygen supply flow rate ratio r between the bottom and top is 0.80. Constants a are taken as 12000 and b as 0.072. t is calculated from equation (1). b =3s. F T =550Nm 3 / min、F B =F b =240Nm 3 / min、F t =300Nm 3 The oxygen supply V from the top oxygen lance at the end of the blowing process after TSC measurement is calculated using equations (2) and (3). t 828 Nm 3Oxygen supply duration T t The oxygen supply V from the bottom oxygen lance is calculated using equations (6) and (7) and is 140s. b 572 Nm 3 Oxygen supply duration T b The time was 143 s. The total iron content of the final slag was determined to be 10.9%.

[0061] Example 3: The specific smelting method for reducing the total iron content of the final slag in the top and bottom blown converter is as follows.

[0062] The basicity of the converter smelting slag is 3.0. The secondary oxygen blowing volume V is calculated after the TSC is measured in the later stage of blowing. sce 1600 Nm 3 There are two oxygen lances at the bottom of the furnace, with an oxygen supply flow rate of 80 Nm³. 3 The oxygen supply rate is 0.55 MPa per minute. After TSC measurement, the oxygen supply from the top and bottom to the furnace is less than 600 Nm³. 3 Therefore, the oxygen lance position is 4.0m, and the oxygen supply flow rate from the top is 550Nm³. 3 / min, pressure 16MPa, bottom to top oxygen supply flow ratio r is 0.15; after TSC measurement, the oxygen supply from the top and bottom to the furnace exceeded 600Nm³. 3 The oxygen supply flow rate of the top oxygen lance is 450 Nm³. 3 The oxygen supply flow rate is 14 MPa / min, and the bottom-to-top oxygen supply flow rate ratio (r) is 0.18. The difference in oxygen supply time between the bottom and top is t. b Value: 90s. F T =550Nm 3 / min、F B =F b =80Nm 3 / min、F t =450Nm 3 The oxygen supply V from the top oxygen lance at the end of the blowing process after TSC measurement is calculated using equations (2) and (3). t 1271 Nm 3 Oxygen supply duration T t The oxygen supply V from the bottom oxygen lance is calculated using equations (6) and (7) and is 157s. b 329 Nm 3 Oxygen supply duration T b The time was 247s. The total iron content of the final slag was determined to be 15.3%.

[0063] Example 4: The specific smelting method for reducing the total iron content of the final slag in the top and bottom blown converter is as follows.

[0064] The basicity of the converter smelting slag is 3.5. The secondary oxygen blowing volume V is calculated after the TSC measurement in the later stage of blowing. sce 800 Nm 3There are 6 oxygen lances at the bottom of the furnace, with an oxygen supply flow rate of 200 Nm³. 3 The oxygen supply rate is 300 Nm / min, and the oxygen supply pressure is 0.65 MPa. The oxygen lance position at the top of the converter is 4.5 m, and the oxygen supply flow rate is 300 Nm³ / min. 3 / min, pressure is 10MPa. The oxygen supply flow rate ratio r between the bottom and top is 0.67. The constant a is taken as 9000 and b is taken as 0.07. t is calculated from equation (1). b =3s. The oxygen supply from the top oxygen lance at the end of the blowing process, calculated using equations (4) and (5), is 473 Nm³. 3 The oxygen supply time was 95s; the oxygen supply amount of the bottom oxygen lance was calculated to be 326 by formulas (6) and (7), and the oxygen supply time was 98s. The total iron content of the final slag was determined to be 13.4%.

[0065] Example 5: The specific smelting method for reducing the total iron content of the final slag in a top-and-bottom combined blowing converter is as follows.

[0066] The basicity of the converter smelting slag is 3.0. The secondary oxygen blowing volume V is calculated after the TSC is measured in the later stage of blowing. sce 500 Nm 3 There are 6 oxygen lances at the bottom of the furnace, with an oxygen supply flow rate of 260 Nm³. 3 The oxygen supply rate is 580 Nm / min, and the oxygen supply pressure is 0.84 MPa. The oxygen lance position at the top of the converter is 4.0 m, and the oxygen supply flow rate is 580 Nm³ / min. 3 / min, pressure is 16MPa. The oxygen supply flow rate ratio r between the bottom and top is 0.45. Constants a is taken as 20000 and b is taken as 0.077. t is calculated from equation (1). b =62s. The oxygen supply from the top oxygen lance at the end of the blowing process, calculated using equations (4) and (5), is 160 Nm³. 3 The oxygen supply time is 17s; the oxygen supply of the bottom oxygen gun is calculated to be 344Nm³ using equations (6) and (7). 3 The oxygen supply time was 79 seconds. The total iron content of the final slag was determined to be 11.7%.

[0067] Example 6: The specific smelting method for reducing the total iron content of the final slag in a top-and-bottom combined blowing converter is as follows.

[0068] The basicity of the converter smelting slag is 2.8. The secondary oxygen blowing volume (V) is calculated after TSC measurement during the later stage of blowing. sce 800 Nm 3 There are 6 oxygen lances at the bottom of the furnace, with an oxygen supply flow rate of 280 Nm³. 3 The oxygen supply rate is 600 Nm / min, and the oxygen supply pressure is 0.90 MPa. The oxygen lance position at the top of the converter is 3.0 m, and the oxygen supply flow rate is 600 Nm³ / min. 3 / min, pressure is 10MPa. The oxygen supply flow rate ratio r between the bottom and top is 0.47. The constant a is taken as 19000 and b is taken as 0.08. t is calculated from equation (1). b=58s. The oxygen supply from the top oxygen lance at the end of the blowing process, calculated using equations (4) and (5), is 156 Nm³. 3 The oxygen supply time is 16s; the oxygen supply capacity of the bottom oxygen gun is calculated to be 344Nm³ using equations (6) and (7). 3 The oxygen supply time was 74 seconds. The total iron content of the final slag was determined to be 13.1%.

[0069] Example 7: The specific smelting method for reducing the total iron content of the final slag in a top-and-bottom combined blowing converter is as follows.

[0070] The basicity of the converter slag is 3.2. The secondary oxygen blowing volume V is calculated after the TSC is measured in the later stage of blowing. sce 300 Nm 3 There are 6 oxygen lances at the bottom of the furnace, with an oxygen supply flow rate of 240 Nm³. 3 The oxygen supply flow rate is 460 Nm / min, and the oxygen supply pressure is 0.76 MPa. The oxygen lance position at the top of the converter is 4.0 m, and the oxygen supply flow rate is 460 Nm³ / min. 3 / min, pressure is 12MPa. The oxygen supply flow rate ratio r between the bottom and top is 0.52. The constant a is taken as 12000 and b is taken as 0.072. t is calculated from equation (1). b =11s. The oxygen supply from the top oxygen lance at the end of the blowing process, calculated using equations (4) and (5), is 168 Nm³. 3 The oxygen supply time is 22s; the oxygen supply of the bottom oxygen gun is calculated to be 132Nm³ using equations (6) and (7). 3 The oxygen supply time was 33 seconds. The total iron content of the final slag was determined to be 9.7%.

[0071] Example 8: The specific smelting method for reducing the total iron content of the final slag in the top and bottom blown converter is as follows.

[0072] The basicity of the converter slag is 3.2. The secondary oxygen blowing volume V is calculated after the TSC is measured in the later stage of blowing. sce 800 Nm 3 Five oxygen lances are installed at the bottom of the furnace, with an oxygen supply flow rate of 180 Nm³. 3 The oxygen supply flow rate is 500 Nm / min, and the oxygen supply pressure is 0.68 MPa. The oxygen lance position at the top of the converter is 4.5 m, and the oxygen supply flow rate is 500 Nm / min. 3 The oxygen supply flow rate is 10 MPa per minute. The bottom-to-top oxygen supply flow rate ratio (r) is 0.36. The difference in oxygen supply time between the bottom and top is t. b The value was taken over 60 seconds. The oxygen supply from the top oxygen lance at the end of the blowing process, measured by TSC, was 456 Nm³. 3 The oxygen supply time is 55 seconds; the oxygen supply capacity of the bottom oxygen lance is 344 Nm³. 3 The oxygen supply time was 115 seconds. The total iron content of the final slag was determined to be 14.6%.

[0073] The steel composition and temperature at the smelting endpoints of Examples 1-8 met expectations. Examples 2 and 7 showed the most significant reductions in total iron content in the final slag, at 10.9% and 9.7% respectively; the average reduction in total iron content in the final slag after using this method was 4.36%. In summary, this method can effectively reduce the total iron content in the final slag of top-and-bottom blown converters.

Claims

1. A smelting method for reducing the total iron of top and bottom combined blown converter final slag, characterized by, The method process is: measuring TSC in the later stage of blowing, and calculating the required secondary oxygen blowing amount V to the blowing end point according to the TSC measurement result sce ; 1.1) if V sce > 1000 Nm 3 ; when the TSC is determined after the top lance and the bottom lance have supplied the amount of oxygen V f < V sce - 1000 Nm 3 , the flow rate ratio r value of the bottom oxygen supply to the top oxygen supply is controlled to be 0.1 to 0.5; When V f ≥ V sce -1000 Nm 3 The flow ratio r of bottom oxygen supply to top oxygen supply is controlled at 0.3-0.

9. 1.2) if 300 Nm 3 ≤ V sce ≤ 1000 Nm 3 then the flow ratio r value of bottom oxygen supply to top oxygen supply is controlled at 0.3-0.9; 2.1) if V sce > 1000 Nm 3 , TSC t and the length of top oxygen supply T t after TSC determination until the end of the blowing are calculated by equations (2), (3), respectively: V t =F t *(1000-t b *F b / 60) / (F b +F t )+F T *(V sce -1000) / (F B +F T ) (2); T t =60*((1000-t b *F b / 60) / (F b +F t )+(V sce -1000) / (F B +F T )) (3); 2.2) if 300≤Vsce≤1000 Nm 3 , the top oxygen supply amount V after TSC determination to the end of blowing t and the top oxygen supply time T t are calculated by equations (4), (5), respectively. V t =F t *(V sce -t b *F b / 60) / (F b +F t ) (4); T t =60*(V sce -t b *F b / 60) / (F b +F t ) (5); 2.3) The amount of bottom oxygen supply V after the TSC test until the end of the blowing b and the length of time of bottom oxygen supply T b are calculated by equations (6) and (7), respectively. V b =V sce -V t (6); T b =T t +t b (7); In the above formula, V t is the top oxygen supply amount, Nm 3 ; when V f < V sce -1000 Nm 3 , the top oxygen supply flow is recorded as F T , Nm 3 / min, and the bottom oxygen supply flow is recorded as F B , Nm 3 / min; when V f ≥ V sce -1000 Nm 3 , the top oxygen supply flow is recorded as F t , Nm 3 / min, and the bottom oxygen supply flow is recorded as F b , Nm 3 / min; t b is the difference between the bottom oxygen supply time and the top oxygen supply time, s; T t is the top oxygen supply time, s; V b is the bottom oxygen supply amount after TSC determination, Nm 3 ; and T b is the bottom oxygen supply time after TSC determination, s.

2. The smelting method of reducing the total iron of the final slag of a top and bottom combined blown converter according to claim 1, characterized in that: In the 1.1), when V f <V sce -1000 Nm 3 / min, the bottom oxygen supply flow F B is controlled at 65 Nm 3 / min~280 Nm 3 / min, the pressure is controlled at 0.4 MPa~0.9 MPa, the top oxygen supply flow F T is controlled at 550 Nm 3 / min~650 Nm 3 / min, and the pressure is controlled at 16 MPa~18 MPa; When V f ≥ V sce -1000 Nm 3 / min, the bottom oxygen supply pressure is controlled at 0.4 MPa-0.9 MPa, the top oxygen supply flow F t is controlled at 300 Nm 3 / min-600 Nm 3 / min, and the pressure is controlled at 10 MPa-17 MPa.

3. The smelting method of reducing the total iron of the final slag of a top and bottom combined blown converter according to claim 1, characterized in that: In the 1.2), the bottom oxygen supply pressure is controlled at 0.4 MPa to 0.9 MPa, and the top oxygen supply flow rate F t is controlled at 300 Nm 3 / min to 600 Nm 3 / min, and the pressure is controlled at 10 MPa to 17 MPa.

4. The steelmaking process for reducing the total iron content of the final slag of a top and bottom combined blown converter according to claim 1, 2 or 3, characterized in that: In section 1.2), when the bottom oxygen supply flow rate is 65 Nm³, 3 / min≤F b <200Nm 3 / min, the difference t between bottom oxygen supply time and top oxygen supply time b The value ranges from 60 to 90 seconds. When the bottom oxygen supply flow rate is 200 Nm 3 / min≤F b ≤280 Nm 3 / min, the bottom oxygen supply time and the top oxygen supply time difference t b and the r value satisfy the following formula (1) relationship: t b =a*e (-r / b) +c (1); In the formula: a, b and c are constants; a is in the range of 9000-20000, b is in the range of 0.07-0.08, and c is 2.5; e is a natural constant. In the formula: a, b and c are constants; a is in the range of 9000-20000, b is in the range of 0.07-0.08, and c is 2.5; e is