Converter double-slag dephosphorization control method based on flue gas analysis technology

Abstract

The application discloses a converter double-slag dephosphorization control method based on flue gas analysis technology and relates to the technical field of steelmaking. The technical points of the application are as follows: S1, charging dephosphorization molten iron, material mainly composed of scrap steel into the converter; S2, starting the blowing operation of the main blowing stage of the converter, adding lime and pellets in batches during the blowing, adjusting the oxygen lance position in real time according to the CO content change trend in the flue gas, and pouring out the phosphorus-rich slag when the CO content in the flue gas exceeds 35%; S3, after the slag pouring is finished, continuing the blowing operation of the main blowing stage and adding lime, light burning and magnesium balls, adjusting the oxygen lance position in real time according to the CO content in the flue gas, and adding pellets in batches after the decarburization enters the stable period; S4, after the main blowing is finished, lowering the auxiliary lance for measuring the molten steel temperature and carbon content, starting the blowing operation of the secondary blowing stage and adding pellets, again lowering the auxiliary lance for temperature measurement and sampling after the blowing is finished, pouring out the slag and tapping the molten steel, and finishing the converter smelting.

Description

Technical Field

[0001] The present invention relates to the technical field of steelmaking, and in particular to a converter double-slag dephosphorization control method based on flue gas analysis technology. Background Art

[0002] Phosphorus is a harmful element for most grades of steel. It can easily cause steel materials to become "cold brittle," leading to sudden fracture during service and significant damage. In a typical long-process steel production process, the converter, as the primary step in molten steel dephosphorization, determines the phosphorus content in the final steel. From a thermodynamic perspective alone, the optimal conditions for converter dephosphorization are high basicity, high oxidizing properties, and low temperatures. The development of converter dephosphorization processes, such as the double-slag dephosphorization process, the MURC dephosphorization process, and the duplex dephosphorization process, focuses on achieving optimal dephosphorization reaction conditions. The double-slag dephosphorization process has been widely used in China due to its advantages such as the lack of a dephosphorization furnace, simple process, low heat loss, and good dephosphorization effect. In the early stages of converter blowing, the furnace temperature is relatively low, and rapid dephosphorization can be achieved by rapidly increasing the slag basicity and oxidizing properties.

[0003] Patent CN113621756A discloses a control method for improving the dephosphorization effect in the early stage of converter steelmaking, which can significantly improve the dephosphorization effect by controlling the charging and gun position in the early stage of blowing. However, in the middle and late stages of the converter, decarburization heating is the main process, and the molten bath temperature increases and the oxidizability of the slag decreases, which is not conducive to the dephosphorization of molten steel. Instead, a general rephosphorization phenomenon occurs. Therefore, after rapid dephosphorization in the early stage of blowing, adding a slag pouring operation (i.e., the core step of double slag dephosphorization) can reduce the rephosphorization of phosphorus-rich slag to the molten steel in the middle and late stages. However, due to the large changes in the initial conditions such as molten iron and scrap steel in each heat, it is difficult to achieve the best dephosphorization conditions and obtain a stable dephosphorization effect with a fixed gun position and charging mode. Only by dynamically adjusting the gun position and charging mode according to the real-time changes of the continuous chemical reaction in the furnace can a more stable dephosphorization effect be obtained. Obviously, judging the reaction situation in the furnace based on experience only by the changes in the furnace mouth flame and the sound in the furnace is not accurate and reliable enough and cannot meet the production requirements of current industrial intelligence.

[0004] Patent CN201510573795.X discloses a method for determining the timing of double-slag lance removal in a converter. When the flue gas analysis indicates a CO concentration between 22% and 28%, and the converter bath temperature is between 1330°C and 1360°C, the lance is removed and double-slag removal is performed, achieving excellent dephosphorization results. However, this method only considers the success rate of slag removal and does not factor in the impact of parameters such as the initial dephosphorization time and slag removal volume, resulting in certain limitations in parameter selection.

[0005] Patent CN202110246617.1 discloses a method and device for dynamic control of the entire converter blowing process. Through furnace mouth flame and flue gas analysis technology, the gun position is dynamically adjusted to solve the splashing and back-drying problems during the blowing process. However, the above two process methods are based on flue gas analysis technology and only provide solutions for a single parameter of the double slag dephosphorization technology and abnormal control of the converter blowing process. They do not achieve efficient dephosphorization, in-furnace reaction detection throughout the converter blowing process, and dynamic adjustment of the smelting process, which has certain limitations.

[0006] Patent CN202011250909.4 discloses a converter dephosphorization control method. This invention also controls dephosphorization based on process flue gas analysis data, primarily by dynamically adjusting the amount of pellets added and bottom blowing, achieving a phosphorus content of ≤0.008% at tapping. This differs significantly from the proposed method, which primarily relies on dynamic oxygen lance adjustment.

[0007] In view of this, this patent is applied for. Summary of the Invention

[0008] The purpose of the present invention is to solve the above problems and provide a converter double slag dephosphorization control method based on flue gas analysis technology to overcome the problem that the existing converter dephosphorization technology cannot fully monitor the reaction in the furnace, dynamically adjust the gun position and accurately add material.

[0009] In order to achieve the above object, the technical solution of the present invention is as follows: a converter double slag dephosphorization control method based on flue gas analysis technology, comprising the following steps:

[0010] S1. Load desulfurized hot metal and scrap steel into the converter; wherein the Si content in the desulfurized hot metal is 0.2%-0.8% and the temperature of the desulfurized hot metal is 1250-1450°C;

[0011] S2. The converter begins the main blowing phase, during which lime and pellets are added in batches. After one minute of oxygen blowing, the oxygen lance position is adjusted in real time according to the CO content in the flue gas to maintain the CO content within the range of 10%-30%. When the CO content in the flue gas exceeds 35%, the furnace is shaken to pour out the phosphorus-rich slag.

[0012] S3. After the slag is discharged, the main blowing stage of the refining process is continued, and lime, light burning, and magnesium balls are added. The oxygen lance position is adjusted in real time according to the CO content in the flue gas, and pellets are added in batches after the decarbonization enters a stable period.

[0013] S4. After the main blowing is completed, the auxiliary gun is lowered to measure the temperature and carbon content of the molten steel, and the blowing operation of the second blowing stage is started and pellets are added. After the blowing is completed, the auxiliary gun is lowered again to measure the temperature and take samples, and then the slag is poured and the steel is tapped. The converter smelting is completed. After the blowing is completed, the remaining slag is 3-8t.

[0014] The principle behind this approach is that optimal conditions for dephosphorization are high alkalinity, high oxidizing properties, and low temperatures. Lime can adjust slag alkalinity, while pellets can increase the FeO content in the slag (indicating its oxidizing properties) to a certain extent and reduce the melt bath temperature. Of course, in practice, the dynamics of dephosphorization must also be considered. High alkalinity and low temperature reduce slag fluidity, hindering the dephosphorization reaction. While a high FeO content in the slag promotes phosphorus oxidation, it also reduces the relative content of Ca₂SiO₄, a phase that absorbs and fixes phosphorus, hindering the fixation of dephosphorization products. Converter flue gas analysis reflects the actual reaction conditions within the furnace during each stage of blowing. First, in the early stages of blowing, the oxygen lances are positioned high and the melt bath temperature is low. The oxygen injected by the lances and the FeO in the slag preferentially react with elements such as Si, Mn, and P in the molten iron, releasing heat. When the oxygen source is abundant, a certain amount of CO is also generated. Therefore, the CO content in the flue gas during the early stages of blowing reflects whether high oxidizing conditions are present within the furnace. When the CO content in the flue gas is low in the early stages of blowing, a "soft blow" can be performed by raising the oxygen lance position to generate more FeO and promote the dephosphorization reaction. When the CO content is too high, a "hard blow" can be performed by lowering the lance position to promote carbon oxidation and temperature increase, increasing slag fluidity and facilitating mass transfer between the slag and steel for the dephosphorization reaction. 2. A high degree of slag foaming during slag pouring facilitates the pouring of more phosphorus-rich slag. Slag with suitable viscosity and moderate carbon-oxygen reaction to generate CO are essential for the formation of foamed slag. As Si, Mn, and P in the molten steel react and the bath temperature continues to rise, carbon oxidation becomes active, and the CO content in the flue gas rises rapidly. Ongoing analysis and research has found that when the CO content reaches 35%, the slag foaming is high, resulting in efficient pouring and large slag pouring volumes. 3. During the mid-to-late stages of blowing (from the decarburization plateau to the end of the second blow), the CO content in the flue gas can reflect the intensity of the carbon-oxygen reaction within the furnace. A higher CO content indicates a more intense carbon-oxygen reaction, resulting in a lower FeO content in the slag, hindering the dephosphorization reaction and potentially causing rephosphorization of the molten steel. A lower CO content indicates a weaker carbon-oxygen reaction, resulting in a relatively high FeO content in the slag, ensuring effective dephosphorization. However, a lower carbon-oxygen reaction intensity is detrimental to molten pool temperature rise and the mixing of the various components of the molten steel. Experimental research has found that optimal dephosphorization results are achieved when the CO concentration ranges from 50-60% during the decarburization plateau. When this range is exceeded, the carbon-oxygen reaction intensity can be adjusted by adjusting the oxygen lance position to achieve the desired CO concentration.

[0015] Preferably, in S2, the amount of lime added is calculated by the following formula: 石灰 =42.9×P Si -1.8×M 留渣量 Among them, M 石灰 is the amount of lime added kg / t, P Si is the silicon content of molten iron, M 留渣量 is the weight t of the slag retained in the converter from the previous furnace.

[0016] More preferably, when the calculated M 石灰 ≤0, no lime added; when the calculated M 石灰 When ≥15kg / t, the amount of lime added is 15kg / t.

[0017] Preferably, in S2, the amount of pellets added is calculated by the following formula: 球团1 =24.7×P Si +0.082×(T 铁水 +M 铁水 )-190; among them, M 球团1 is the amount of pellets added during the desiliconization and dephosphorization period (kg / t), P Si is the silicon content of molten iron, T 铁水 is the temperature of molten iron; M 铁水 It is the unit consumption of molten iron in kg / t.

[0018] More preferably, when the calculated M 球团1 ≤0, without pellets; when the calculated M 球团1 When the content is ≥10kg / t, the amount of pellets added is 10kg / t.

[0019] Preferably, in S2, when the CO content in the detected flue gas is lower than 10%, the basic gun position is raised by 5-10 cm; when the CO content is higher than 30%, the basic gun position is lowered by 5-10 cm; after blowing oxygen for 3 minutes and 30 seconds, the gun position is no longer dynamically adjusted until the slag discharge requirements are met.

[0020] Preferably, in S3, when the CO content in the flue gas is ≥60%, the basic gun position is raised by 5-20 cm; when the CO content in the flue gas is <50%, the basic gun position is lowered by 5-20 cm.

[0021] Preferably, in S3, the amount of pellets added is calculated by the following formula: 球团2 =49.4×P Si +0.165×(T 铁水 +M 铁水 )-380; among them, M 球团2 is the amount of pellets added during the desiliconization and dephosphorization period (kg / t), P Si is the silicon content of molten iron, T 铁水 is the temperature of molten iron; M 铁水 It is the unit consumption of molten iron in kg / t.

[0022] More preferably, when the calculated M 球团2 ≤0, no pellets were added to S3.

[0023] Preferably, in S4, the minimum amount of pellets added is 2 kg / t; when the blowing model predicts that the end temperature is higher than 1630°C, 2 kg / t of pellets are additionally added for every 10°C increase.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. The present invention dynamically adjusts the oxygen lance position in the initial blowing stage and the decarburization stable stage to control the CO concentration in the flue gas, thereby achieving efficient dephosphorization in the early blowing stage and reducing the rephosphorization of molten steel in the high-speed decarburization stage.

[0026] 2. The present invention determines the optimal timing for slag pouring (phosphorus-rich slag) based on the CO content in the flue gas, and pours out the early phosphorus-rich slag. This time point corresponds to the maximum dephosphorization in the early stage and no rephosphorization of the molten steel has occurred. At this time, the carbon-oxygen reaction has just begun, the slag is moderately foamed, and it is easy to pour out in large quantities.

[0027] 3. The present invention formulates lime and pellet addition plans based on the dephosphorization requirements at different stages. To ensure rapid dephosphorization in the early blowing stage, it is necessary to provide appropriate slag basicity, oxidizing properties, and reaction temperature. During the high-speed decarburization period, it is necessary to increase the slag oxidizing properties and control the bath temperature to reduce phosphorus reversion in the molten steel. During the secondary blowing stage, it is necessary to increase the slag oxidizing properties and fluidity to prevent rapid temperature rise and phosphorus reversion in the molten steel. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the present invention, the technical invention of the present invention will be further described in detail below in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0030] Example 1

[0031] The technical method of the present invention was used to perform double-slag dephosphorization blowing in a 120-ton converter. The incoming hot metal contained 0.32% Si, 5 tons of slag was retained from the previous furnace, the hot metal temperature was 1367°C, and the hot metal consumption was 883 kg / ton. After the blows were started, 567 kg of lime and 288 kg of pellets were added. One minute after the oxygen blow, the flue gas CO concentration reached 6%. At this point, the base lance position was raised by 5 cm, and 15 seconds later, the CO concentration exceeded 10%. At 3 minutes and 8 seconds after the oxygen blow, the flue gas CO concentration exceeded 30%. At this point, the lance position was lowered by 10 cm, but the CO concentration did not rise further. After 4 minutes and 21 seconds of oxygen blow, the flue gas CO concentration rose rapidly and exceeded 35%. At this point, the lance was raised and the furnace was shaken to dump the slag. The slag was moderately foamed, the slag was quickly dumped, and the amount of slag discharged was large. During the dumping process, molten steel samples were taken for phosphorus content, and compared with the phosphorus content of the hot metal. The early dephosphorization rate was high, reaching 82%. After slag pouring, the lance was lowered and blowing continued according to the converter's secondary expert model, with the addition of auxiliary materials such as lime, light-burned dolomite, and magnesium balls. The total oxygen blowing time reached 6 minutes and 16 seconds, and decarburization entered a stable period, with the CO concentration stabilizing at around 66%. At this point, the base lance position was raised by 15 cm, and the CO concentration rapidly dropped to around 55%. During this process, 847 kg of pellets were added in three batches. When the oxygen blowing reached 85% of the total, the auxiliary lance was lowered to measure temperature and determine carbon content. Based on the measurement results, the secondary expert model predicted a tapping temperature of 1628°C. 240 kg of pellets were added during the secondary blowing phase. After the blowing, the actual measured molten steel temperature was 1621°C, and the phosphorus content was 0.0058%.

[0032] Example 2

[0033] The technical method of the present invention was used to perform double-slag dephosphorization blowing in a 120-ton converter. The incoming molten iron contained 0.52% Si, 4 tons of slag was retained from the previous furnace, the molten iron temperature was 1336°C, and the molten iron consumption was 889 kg / ton. After the blows were started, 1800 kg of lime and 635 kg of pellets were added. After one minute of oxygen blowing, the flue gas CO concentration reached 14%. At 2 minutes and 40 seconds into the oxygen blow, the flue gas CO concentration exceeded 30%. At this point, the lance was lowered 10 cm, but the CO concentration did not rise further. After 3 minutes and 46 seconds of oxygen blowing, the flue gas CO concentration rose rapidly and exceeded 35%. At this point, the lance was raised and the furnace was shaken to dump the slag. The slag was moderately foamed, allowing for rapid slag dumping and a large amount of slag to be dumped. During the dumping process, molten steel samples were taken for phosphorus content, and compared with the molten iron phosphorus content, revealing a high early dephosphorization rate of 84%. After slag pouring, the lance was lowered and blowing continued according to the converter's secondary expert model, with the addition of auxiliary materials such as lime, light-burned dolomite, and magnesium balls. The total oxygen blowing time reached 7 minutes and 4 seconds, and decarburization entered a stable period. The CO concentration stabilized at around 57%. The base lance position remained unchanged. During this process, 1,538 kg of pellets were added in four batches. When the oxygen blowing reached 85% of the total, the auxiliary lance was lowered to measure temperature and determine carbon content. Based on the measurement results, the secondary expert model predicted a tapping temperature of 1,645°C. 600 kg of pellets were added during the secondary blowing phase. After the blowing, the actual measured molten steel temperature was 1,625°C, and the phosphorus content was 0.0042%.

[0034] Comparative Example 1

[0035] A conventional double-slag dephosphorization process was used in a 120t converter. The comparative test involved a 0.37% Si content in the incoming hot metal, 6t of slag from the previous furnace, a hot metal temperature of 1342°C, and a hot metal consumption of 880kg / t. After the start of the blowdown, 500kg of lime was added, but no pellets were added. After one minute of oxygen blowing, the flue gas CO concentration was 0%. After 3 minutes and 12 seconds of oxygen blowing, the CO concentration exceeded 10%, and after 4 minutes and 6 seconds of oxygen blowing, the CO concentration reached 22%. At this point, the lance was raised and the furnace was shaken for slag removal. The slag layer was thin, with low foaming, making slag removal difficult and the amount discharged small. During the slag removal process, molten steel samples were taken for phosphorus content, and compared with the hot metal phosphorus content. The dephosphorization rate was low in the early stages, reaching 33%. After slag pouring, the blasting lance continued according to the converter's secondary expert model, adding auxiliary materials such as lime, light-burned dolomite, and magnesium balls. The total oxygen blowing time reached 6 minutes and 47 seconds, and decarburization entered a plateau. The CO concentration stabilized at around 66%. The base lance position remained unchanged, and 728 kg of pellets were added in two batches. When the oxygen blowing reached 85% of the total, the auxiliary lance was lowered to measure temperature and determine carbon content. Based on the measurement results, the secondary expert model predicted a tapping temperature of 1641°C. No pellets were added during the secondary blowing phase. After the blowing phase, the actual measured molten steel temperature was 1638°C, and the phosphorus content was 0.014%. The phosphorus content of the tapped steel exceeded the target steel grade requirement by 0.006%, resulting in a failed steel.

[0036] Comparative Example 2

[0037] A conventional double-slag dephosphorization process was used in a 120t converter. The comparative test showed a Si content of 0.61% in the incoming hot metal, 3t of slag from the previous furnace, a hot metal temperature of 1378°C, and a hot metal consumption of 876kg / t. After the start of the blowdown, 2500kg of lime and 1800kg of pellets were added. One minute after the oxygen injection, the flue gas CO concentration reached 18%. At 3 minutes and 22 seconds, the CO concentration exceeded 35%, leading to severe slag foaming and overflow from the furnace mouth. A forced lance was raised and the furnace mouth purged. A slag suppressant was added and the furnace was allowed to stand for one minute before the slag was shaken and drained. During the slag draining process, molten steel samples were taken for phosphorus analysis and compared with the hot metal. Suspected rephosphorization was observed in the molten steel, resulting in a dephosphorization rate of only 42%. After slag pouring, the lance was lowered and blowing continued according to the converter's secondary expert model. Auxiliary materials, including lime, light-burned dolomite, and magnesium balls, were added. The total oxygen blowing time reached 7 minutes and 22 seconds, and decarburization entered a plateau. The CO concentration stabilized at around 46%. The base lance position remained unchanged, and 328 kg of pellets were added during this process. When the oxygen blowing rate reached 85% of the total, the auxiliary lance was lowered to measure temperature and determine carbon content. Based on these measurements, the secondary expert model predicted a tapping temperature of 1610°C. No pellets were added during the secondary blowing phase. After the blowing phase, the actual molten steel temperature was 1602°C, with a phosphorus content of 0.008%. The tapping temperature was low, and the phosphorus content exceeded the target steel grade requirement by 0.006%, resulting in a failed steel grade.

[0038] Conclusion: Comparison of the Examples and Comparative Examples demonstrates that the present invention utilizes flue gas analysis technology to achieve real-time monitoring of reactions within the converter throughout the entire process. Based on this, extensive testing and research has led to the development of a dynamic lance position control scheme that optimizes dephosphorization effectiveness, achieving excellent dephosphorization results and consistently achieving a phosphorus content of ≤0.006% in molten steel from a medium- and high-carbon converter. Based on the remaining slag and the addition of molten iron and scrap steel, the present invention utilizes thermodynamic calculations combined with experimental data fitting analysis to determine the precise amounts of lime and pelletizing additives, resulting in more precise process control and ease of automation.

[0039] The above specific embodiments are merely explanations of the present invention and are not limitations of the present invention. After reading this specification, those skilled in the art may make non-creative modifications to the embodiments as needed. However, as long as they are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A converter double slag dephosphorization control method based on flue gas analysis technology, characterized in that: The following steps are involved: S1. Load desulfurized hot metal and scrap steel into the converter; the Si content in the desulfurized hot metal is 0.2%-0.8%, and the temperature of the desulfurized hot metal is 1250-1450℃; S2. The converter begins the main blowing phase of the blowing operation. During the blowing phase, lime and pellets are added in batches. After blowing oxygen for one minute, the oxygen lance position is adjusted in real time according to the trend of CO content in the flue gas to maintain the CO content within the range of 10%-30%. When the CO content in the flue gas exceeds 35%, the furnace is shaken to pour out the phosphorus-rich slag. When the CO content in the detected flue gas is lower than 10%, the basic gun position is raised by 5-10cm; when the CO content is higher than 30%, the basic gun position is lowered by 5-10cm; after blowing oxygen for 3 minutes and 30 seconds, the gun position is no longer dynamically adjusted until the slag discharge requirements are met; S3. After the slag is discharged, the main blowing stage of the refining operation is continued, and lime, light burning, and magnesium balls are added. The oxygen lance position is adjusted in real time according to the CO content in the flue gas. After the decarbonization enters the stable period, pellets are added in batches; wherein: When the CO content in the flue gas is ≥60%, adjust the basic gun position up by 5-20cm; when the CO content in the flue gas is <50%, adjust the basic gun position down by 5-20cm; S4. After the main blowing is completed, the auxiliary gun is lowered to measure the temperature and carbon content of the molten steel, and the blowing operation of the second blowing stage is started and pellets are added. After the blowing is completed, the auxiliary gun is lowered again to measure the temperature and take samples, and then the slag is poured and the steel is tapped. The converter smelting is completed. After the blowing is completed, the remaining slag is 3-8t.

2. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 1, characterized in that: In S2, the amount of lime added is calculated by the following formula: 石灰 =42.9×P Si -1.8×M 留渣量 ; Among them, M 石灰 is the amount of lime added kg / t, P Si M is the silicon content of molten iron, 留渣量 is the weight t of the slag retained in the converter from the previous furnace.

3. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 1, characterized in that: In S2, the amount of pellets added is calculated by the following formula: M 球团1 =24.7×P Si +0.082×(T 铁水 +M 铁水 )-190; Among them, M 球团1 is the amount of pellets added during the desiliconization and dephosphorization period (kg / t), P Si T is the silicon content of molten iron, 铁水 is the temperature of molten iron; M 铁水 It is the unit consumption of molten iron in kg / t.

4. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 2, characterized in that: When the calculated M 石灰 ≤0, no lime added; when the calculated M 石灰 When ≥15kg / t, the amount of lime added is 15kg / t.

5. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 3, characterized in that: When the calculated M 球团1 ≤0, without pellets; when the calculated M 球团1 When the content is ≥10kg / t, the amount of pellets added is 10kg / t.

6. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 1, characterized in that: In S3, the amount of pellets added is calculated by the following formula: M 球团2 =49.4×P Si +0.165×(T 铁水 +M 铁水 )-380; among them, M 球团2 is the amount of pellets added during the desiliconization and dephosphorization period (kg / t), P Si T is the silicon content of molten iron, 铁水 is the temperature of molten iron; M 铁水 It is the unit consumption of molten iron in kg / t.

7. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 6, characterized in that: When the calculated M 球团2 ≤0, no pellets were added to S3.

8. The converter double slag dephosphorization control method based on flue gas analysis technology according to claim 1, characterized in that: In S4, the minimum amount of pellets added is 2 kg / t; when the blowing model predicts that the end temperature is higher than 1630℃, an additional 2 kg / t of pellets is added for every 10℃ increase.