Converter smelting method for inhibiting splashing of high-manganese molten iron and reducing content of ferrous oxide in final slag

Abstract

The invention belongs to the technical field of ferrous metallurgy, and particularly discloses a converter smelting method for inhibiting high-manganese molten iron from splashing and reducing the content of ferrous oxide in final slag, which mainly reduces the distance between a gun head and a liquid level to the greatest extent by adjusting the gun position of a converter and adopting a'low-high-low 'operation mode; the oxidation reaction of the oxygen lance to the manganese element is reduced by adopting low oxygen supply intensity, and the heating rate of a molten pool is reduced; adjusting oxygen lance parameters to reduce the central included angle, reduce the impact area, improve the impact depth and increase the Mach number; the total amount of ferrous oxide is provided by adopting an oxygen lance for oxygen supply, sufficient pellets with the iron content of 60% or above are added to supply oxygen at the same time, demanganization and temperature suppression operation is carried out through a series of optimization, meanwhile, rising of the temperature of a molten pool is delayed, carbon-oxygen reaction is inhibited, and the effect of inhibiting splashing is achieved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, and particularly relates to a converter smelting method for inhibiting high-manganese molten iron splashing and reducing the content of ferrous oxide in final slag. BACKGROUND

[0002] In the process of the steel industry moving towards high-quality development, the converter smelting technology becomes the core process of modern steelmaking due to the advantages of high efficiency, energy saving and strong adaptability. With the downward mode of the steel industry, steel plants are taking the lowest cost as the dominant factor of production and operation, so the high-quality and cost-effective coal and ore matching is obviously not suitable for the current market, and thus becomes the key to blast furnace ironmaking. At the same time, the high-quality and cost-effective coal and ore matching brings great production difficulties to the steelmaking plant in the next process. For example, high-silicon, high-manganese, high-phosphorus and high-sulfur molten iron are successively produced, and in order to maximize the benefits, the steelmaking process has to undertake such molten iron for production. Among them, the special chemical composition and reaction characteristics of high-manganese molten iron cause the frequent splashing in the converter smelting process, the final slag is too dilute, and the content of ferrous oxide (FeO) is high, which seriously restricts the smelting efficiency and product quality.

[0003] During the converter smelting of high-manganese molten iron, the intense oxidation reaction is the core inducement of splashing. The oxidation reaction rate of manganese element is extremely fast, and a large amount of heat energy is rapidly released in the high-temperature environment, causing the temperature in the molten pool to rise sharply to above 1420℃, and the carbon-oxygen reaction and silicon-manganese oxidation reaction are superimposed, and a large amount of foaming slag is brought out of the furnace by the intense carbon-oxygen reaction. According to industry data, the metal loss rate caused by splashing during the smelting of high-manganese molten iron can reach 1%-3%, which not only significantly increases the production cost, but also may shorten the service life of key components such as oxygen lance and furnace lining due to the erosion of splashing to the equipment, and even threatens the personal safety of on-site operators.

[0004] The problems of too dilute final slag and high content of ferrous oxide are caused by the unique metallurgical reaction mechanism of high-manganese molten iron. The MnO generated by the oxidation of manganese and the SiO2 generated by the oxidation of silicon can form a low-melting-point (1285℃) manganese silicate slag system at a relatively low temperature, which is much lower than the melting point of the traditional slag system. Although this low-melting-point characteristic speeds up the slag formation, it leads to the loss of control of the fluidity of the slag, and it is difficult to form a dense slag layer that effectively covers the molten pool. At the same time, the strong reducing property of manganese makes the iron element more easily oxidized at high temperature, resulting in a significant increase in the content of FeO in the final slag, which can reach 20%-25% in some working conditions. High content of FeO not only intensifies the oxidation loss of alloying elements in steel, reduces the alloy recovery rate, but also significantly enhances the oxidizing property of the slag, accelerates the erosion of the furnace lining, and shortens the replacement cycle of the converter refractory material by 10%-15%.

[0005] At present, although various solutions have been tried in the industry, they all have limitations. The traditional double-slag method adjusts the slag system through multiple slagging, but the secondary blowing process is prone to splashing accidents due to violent reaction; adding Ba-based slagging agent can improve the viscosity of the slag, but greatly increases the smelting cost; the scheme of optimizing the oxygen supply system is difficult to balance the oxygen supply intensity and the stability of the molten pool at the same time. The existence of these technical bottlenecks makes it an urgent need to develop an innovative technology to systematically solve the problem of high-manganese hot metal converter smelting in order to realize cost reduction and efficiency improvement and green and low-carbon development of the steel industry. SUMMARY

[0006] The purpose of the present application is to provide a converter smelting method for inhibiting high-manganese hot metal splashing and reducing the content of ferrous oxide in final slag, to solve the problems of easy splashing of high-manganese hot metal in the converter smelting process, high ferrous oxide in final slag, and thin final slag.

[0007] To achieve the above-mentioned purpose, the basic scheme provided by the present application is as follows: a converter smelting method for inhibiting high-manganese hot metal splashing and reducing the content of ferrous oxide in final slag, comprising the following steps: a. Smelting early stage: within 30 seconds after the start of converter blowing, the oxygen lance is lowered to a position 1200 mm away from the hot metal liquid surface, and the hot metal ratio is controlled between 78% and 83%; b. Manganese removal and temperature suppression stage: blowing is carried out at a low oxygen supply intensity of 2.3m 3 / t·h to 2.5m 3 / t·h, and at the same time, a pellet with an iron oxide content of not less than 60% is added for slagging, the pellet is added at a rate of 1t / min; c. Oxygen supply parameter optimization stage: optimize the oxygen lance parameters, adjust the oxygen lance throat diameter to 39.5mm, adjust the Mach number to 2.05, and adjust the central angle to 12°; d. End point control stage: when lowering the lance at the end point, the oxygen lance is lowered to a position 800 mm away from the hot metal liquid surface, and the lowering time is not less than 120 seconds, so that the final slag is sticky.

[0008] Further, in the step a, the hot metal treated by the converter satisfies the following conditions: the hot metal temperature is 1280℃ to 1350℃, the hot metal silicon content is 0.30% to 0.50%, and the hot metal manganese content is 0.55% to 0.90%; the hot metal charging amount is controlled at 105t to 115t.

[0009] Further, in the step a, the highest lance position of the oxygen lance during the entire smelting process of the converter is not higher than the opening blowing lance position.

[0010] Further, in the step b, the amount of the pellet added is adjusted according to the manganese content of the hot metal, and the specific adjustment is as follows: When the manganese content of the molten iron is 0.55%, the quantity of the pellet is 1000kg; When the manganese content of the molten iron is 0.65%, the quantity of the pellet is 1280kg; When the manganese content of the molten iron is 0.75%, the quantity of the pellet is 1580kg; When the manganese content of the molten iron is 0.85%, the quantity of the pellet is 2000kg.

[0011] Further, in the step c, the oxygen supply intensity is 2.3m 3 / t·h to 2.5m 3 / t·h, the corresponding relationship between the lance position and the maximum impact area and impact depth is as follows: When the lance position is 1.0m, the impact area is 0.4616m 2 , and the impact depth is 1.020; When the lance position is 1.2m, the impact area is 0.6049m 2 , and the impact depth is 0.928; When the lance position is 1.4m, the impact area is 0.7675m 2 , and the impact depth is 0.857; When the lance position is 1.6m, the impact area is 0.9494m 2 , and the impact depth is 0.799.

[0012] Further, in the step d, the end-point lance-lowering operation is performed 9 minutes after the smelting starts.

[0013] Further, in the method, the slag material uses types include lime, magnesite and pellet.

[0014] Compared with the prior art, the application has the following advantages: 1. In the manganese removal and temperature suppression stage, the oxygen supply intensity is 2.3m 3 / t·h to 2.5m 3 / t·h for blowing, which can slow down the oxidation of manganese in the molten iron, slow down the temperature rising speed, prolong the manganese oxidation time, and slow down the carbon-oxygen reaction.

[0015] 2. The process difficulty is how to remove manganese without rising temperature, and the main operation scheme is "using the pellet with the iron oxide content of more than 60% to make slag, and slowly adding the pellet at the rate of 1t / min after the smelting ignition is normal", which can supplement the ferrous oxide and oxygen content at the same time, not only supplement the oxygen content but also utilize the cold effect of the pellet to slow down the temperature rising of the molten pool, so as to achieve the purpose of removing manganese without rising temperature.

[0016] 3. Optimizing oxygen lance parameters aims to reduce the impact area of ​​the oxygen jet, increase the impact depth of the oxygen jet, and maintain sufficient impact depth under low oxygen flow rate.

[0017] 4. The final lance lowering operation starts at 9 minutes to ensure that the lance position does not exceed the opening lance position throughout the smelting process, keeping the slag activity in the furnace moderate and reducing phenomena such as splashing and slag overflow. This reduces the amount of slag accumulated in the furnace pit and lowers the ferrous oxide content in the final slag. Attached Figure Description

[0018] Figure 1 A gun position diagram during the smelting process when smelting using the method described in this invention; Figure 2 This is a schematic diagram showing the amount of slag in the furnace pit when an enterprise uses the method described in this invention for smelting from January to May 2025. Figure 3 This is a graph showing the distribution of ferrous oxide content in the final slag when an enterprise uses the method described in this invention for smelting from January to May 2025. Detailed Implementation

[0019] The present invention will be further described in detail below through specific embodiments: like Figure 1 The following steps are shown: A converter smelting method for suppressing splashing of high-manganese molten iron and reducing the ferrous oxide content in the final slag: a. Pre-smelting stage: Within 30 seconds of the start of converter blowing, lower the oxygen lance to a position 1200mm from the molten iron surface, and maintain the iron-to-liquid ratio between 78% and 83%; the molten iron used in the converter should meet the following conditions: molten iron temperature between 1280℃ and 1350℃, silicon content between 0.30% and 0.50%, and manganese content between 0.55% and 0.90%; the molten iron charge should be controlled between 105t and 115t; throughout the entire smelting process, the highest position of the oxygen lance should not be higher than the starting blowing position; b. Demanganese removal and temperature suppression stage: using 2.3m 3 / t·h to 2.5m 3 The smelting process involves blowing at a low oxygen supply intensity of / t·h, while simultaneously adding iron oxide pellets with a content of not less than 60% for slagging. The pellets are added slowly at a rate of 1t / min. The amount of pellets added is adjusted according to the manganese content of the molten iron, as follows: When the manganese content of molten iron is 0.55%, the amount of pellets added is 1000 kg; When the manganese content in molten iron is 0.65%, the amount of pellets added is 1280 kg; When the manganese content in molten iron is 0.75%, the amount of pellets added is 1580 kg; When the manganese content of molten iron is 0.85%, the amount of pellets added is 2000 kg.

[0020] c. Oxygen supply parameter optimization stage: Optimize the oxygen lance parameters, adjusting the throat diameter to 39.5mm, Mach number to 2.05, and center angle to 12°; at 2.3m 3 / t·h to 2.5m 3 Under an oxygen supply intensity of / t·h, the relationship between the oxygen lance position and the maximum impact area and impact depth is as follows: When the gun position is 1.0m, the impact area is 0.4616m². 2 The impact depth was 1.020. When the gun position is 1.2m, the impact area is 0.6049m². 2 The impact depth was 0.928. When the gun position is 1.4m, the impact area is 0.7675m². 2 The impact depth was 0.857. When the gun position is 1.6m, the impact area is 0.9494m². 2 The impact depth was 0.799.

[0021] d. End-point control stage: When lowering the oxygen lance at the end point, lower the oxygen lance position to 800mm from the molten iron surface and maintain the lowering time for no less than 120 seconds to make the final slag sticky; the end-point lowering operation is carried out 9 minutes after the start of smelting; the types of slag materials used include lime, magnesite and pellets.

[0022] Depend on Figure 2 It can be seen that when the manganese content of molten iron is controlled at 0.55-0.5%, the overflow and splashing of converter slag are significantly alleviated. There was no splashing in March 2025, and the amount of slag in the furnace pit decreased from 28.71 kg / t to 24.05 kg / t from January 2025 to May 2025.

[0023] from Figure 3 It can be seen that the applicant collected 2,437 valid data points from January to May 2025. The average ferrous oxide content of the final slag in 921 data points from January to February was 17.51%, while the average ferrous oxide content of the final slag in 1,516 data points from March onwards decreased to 14.01%.

[0024] In summary, the smelting method described in this invention can effectively solve the problems of easy splashing of high-manganese molten iron and high ferrous oxide content and sparse final slag during converter smelting. By reducing splashing and lowering the ferrous oxide content in the final slag, the blowdown loss in converter smelting is further reduced, and the converter metal recovery rate is improved. At the same time, the sticky final slag can effectively improve the slag splashing protection effect, reduce the furnace lining maintenance time, and further improve the converter operating rate.

[0025] The above-mentioned are only embodiments of the present application, and the common knowledge of specific structures and characteristics in the scheme is not described too much. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope claimed in this application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A converter smelting method for suppressing splashing of high manganese iron molten metal and reducing the content of ferrous oxide in final slag, characterized by, The method comprises the following steps: a. Pre-smelting stage: within 30 seconds after the start of converter blowing, the oxygen lance is lowered to a position 1200 mm away from the molten iron liquid surface, and the molten iron ratio is controlled between 78% and 83%; b. The manganese removal temperature suppression stage: the oxygen blowing is carried out at a low oxygen supply intensity of 2.3m 3 / t·h to 2.5m 3 / t·h, and at the same time, the balling is carried out by adding the pellets with an iron oxide content not less than 60%, which are slowly added at a rate of 1t / min. c. Oxygen supply parameter optimization stage: optimize the oxygen lance parameters, adjust the oxygen lance throat diameter to 39.5 mm, adjust the Mach number to 2.05, and adjust the central angle to 12°; d. End point control stage: when the end point is lowered, the oxygen lance is lowered to a position 800 mm away from the molten iron liquid surface, and the lowering time is not less than 120 seconds to make the final slag sticky.

2. The method of claim 1, wherein the method is characterized by, In the step a, the molten iron treated by the converter satisfies the following conditions: the molten iron temperature is 1280-1350℃, the molten iron silicon content is 0.30%-0.50%, and the molten iron manganese content is 0.55%-0.90%; the molten iron charging amount is controlled at 105-115 t.

3. The method of claim 1, wherein the method is characterized by, In the step a, during the whole smelting process, the highest lance position of the oxygen lance is not higher than the blowing lance position.

4. The method of claim 1, wherein the method is characterized by, In the step b, the adding amount of the pellet is adjusted according to the molten iron manganese content, and the specific adjustment is as follows: When the molten iron manganese content is 0.55%, the adding amount of the pellet is 1000 kg; When the molten iron manganese content is 0.65%, the adding amount of the pellet is 1280 kg; When the molten iron manganese content is 0.75%, the adding amount of the pellet is 1580 kg; When the molten iron manganese content is 0.85%, the adding amount of the pellet is 2000 kg.

5. The method of claim 1 wherein the method is characterized by, The step c is carried out at 2.3 m 3 / t·h to 2.5 m 3 The corresponding relationship between the lance position and the maximum impact area and impact depth at the oxygen supply intensity of 2.5 m3 / t·h is as follows: When the gun position is 1.0 m, the impact area is 0.4616 m 2 , and the impact depth is 1.

020. When the gun position is 1.2 m, the impact area is 0.6049 m 2 , and the impact depth is 0.

928. When the gun position is 1.4 m, the impact area is 0.7675 m 2 , and the impact depth is 0.

857. When the gun position is 1.6 m, the impact area is 0.9494 m 2 , and the impact depth is 0.

799.

6. The method of converting smelting as claimed in claim 1, wherein, In the step d, the end point lowering operation is performed 9 minutes after the start of smelting.

7. The method of claim 1 wherein the method further comprises the step of: adding a fluxing agent to the molten iron in the vessel. In the method, the types of slag materials include lime, magnesite and pellets.

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