High-efficiency and low-cost molten iron KR stirring desulfurization method

Abstract

The invention discloses a high-efficiency and low-cost molten iron KR stirring desulfurization method, which is characterized in that a desulfurization model is established by determining parameters (desulfurizer consumption, stirring time and stirring head rotating speed) in a KR desulfurization operation process, so that the purpose of high-efficiency and low-cost desulfurization is achieved. The method has the main advantages that by establishing the KR desulfurization model, desulfurization process operation is standardized, and guidance is provided for field production; process parameters can be automatically determined on site only by confirming the initial sulfur content and the target sulfur content of molten iron transmitted from a laboratory, and manual calculation is not needed; and the desulfurization model can effectively avoid the waste of the desulfurizer while ensuring the molten iron desulfurization effect, and realizes high-efficiency and low-cost operation.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology and relates to a high-efficiency and low-cost KR stirring desulfurization method for molten iron. Background Technology

[0002] In recent years, metallurgical enterprises have faced increasing environmental pressures, and the steel industry has entered an era of low profits. Various measures must be taken for optimization and cost reduction. Excessive cost reduction has led to an increase in the sulfur content of raw coal, which in turn has resulted in a corresponding increase in the sulfur content of blast furnace iron. Sulfur in blast furnace iron is harmful to steelmaking, so the desulfurization process is essential in converter steelmaking. This process consumes sulfur and improves the purity of the molten iron. The KR stirring method for molten iron is widely used in steel plants due to its simple operation and high desulfurization rate. The KR stirring method primarily uses lime as a desulfurizing agent, supplemented with a small amount of fluorite as a flux. The reaction equation is as follows:

[0003] 2CaO+[S]+1 / 2[Si]=(CaS)+1 / 2(Ca2SiO4)

[0004] The KR stirring method can reduce the sulfur content of molten iron to an ultra-low sulfur level of "double zero," which can reduce the smelting workload of subsequent processes and reduce consumption indicators. However, the desulfurization efficiency is affected by a variety of factors. For example, if the amount of desulfurizing agent added is insufficient, the target sulfur content of the molten iron will not be achieved. If too much desulfurizing agent is added, it will not only cause waste but also lead to an increase in the temperature drop of the molten iron. If the stirring head speed is too low, the desulfurizing agent cannot make sufficient contact with the molten iron. If the stirring head speed is too high, it will cause splashing. If the stirring time is too short, the reaction time between the desulfurizing agent and the molten iron is insufficient and the expected target cannot be achieved. If the stirring time is too long, it will cause waste of materials and time. Therefore, how to operate efficiently and at low cost is the core of the KR stirring method for desulfurization. Summary of the Invention

[0005] This invention discloses a highly efficient and low-cost method for desulfurization of molten iron by stirring KR.

[0006] The specific technological measures adopted are as follows:

[0007] 1. Establish a desulfurization model by determining the parameters in the KR desulfurization process (desulfurizing agent consumption, stirring time, and stirring head speed).

[0008] The desulfurization process is divided into two categories: shallow desulfurization with a target [S] ≤ 0.010% and deep desulfurization with a target [S] ≤ 0.005%. Desulfurizing agent consumption is divided into 11 intervals based on the sulfur content of the molten iron. Each interval has a target for the deep / shallow desulfurization process based on the target steel grade. The amount of desulfurizing agent added is determined by a combination of theoretical calculations and on-site production experience. Desulfurization stirring time is divided into 6 intervals based on the sulfur content of the molten iron. Each interval has a target for the deep / shallow desulfurization process based on the target steel grade. The stirring time is determined based on on-site production experience and production scheduling. Stirring head speed is divided into 4 intervals based on the stirring head's lifespan. New stirring heads have good refractory material condition and large blade size, with a maximum speed of 85 rpm / min. Later, as the refractory material is corroded by molten iron and slag, the blade size gradually decreases. The speed is increased sequentially according to the stirring head's lifespan to ensure desulfurization efficiency.

[0009] 2. Parameters during KR desulfurization operation

[0010] (1) The amount of desulfurizing agent to be added is determined based on the initial sulfur content of the molten iron and the target sulfur content after desulfurization, as shown in Table 1:

[0011] Table 1. Desulfurizing agent dosage (kg / furnace)

[0012]

[0013] Note: The allowable deviation for the actual amount of desulfurizing agent added is ±20kg;

[0014] (2) The stirring time is determined based on the initial sulfur content of the molten iron and the target sulfur content after desulfurization, as shown in Table 2:

[0015] Table 2 Desulfurization stirring time

[0016]

[0017] (3) The stirring speed is determined based on the initial sulfur content of the molten iron and the target sulfur content after desulfurization, combined with the life of the stirring head, as shown in Table 3.

[0018] Table 3 Desulfurization stirring head rotation speed

[0019]

[0020] The inventive points and analysis of this invention:

[0021] This invention establishes a desulfurization model by determining parameters (desulfurizing agent consumption, stirring time, and stirring head rotation speed) during the KR desulfurization process, thereby achieving efficient and low-cost desulfurization.

[0022] The main advantages of this invention are:

[0023] By establishing a KR desulfurization model, the parameters that desulfurization operators need to consider (KR stirring head speed, stirring time, and desulfurizing agent dosage) are integrated into the system, standardizing the desulfurization process and providing guidance for on-site production. On-site, the system automatically determines process parameters simply by confirming the initial and target sulfur content of the molten iron from the laboratory. Using the start button on the primary screen, the system calculates the required desulfurizing agent according to the model and sets parameters such as stirring head speed and stirring time, eliminating the need for manual calculations. The desulfurization model ensures effective desulfurization of molten iron while effectively avoiding desulfurizing agent waste, achieving efficient and low-cost operation. Detailed Implementation

[0024] Example 1

[0025] (1) Basic information of the heat: Heat number 5344, initial [S] of molten iron = 0.019%, the target steel grade process requires [S] ≤ 0.010% after KR desulfurization, and the stirring head of the current heat is being used for the 65th time;

[0026] (2) As shown in Table 1, 378 kg of desulfurizing agent needs to be added;

[0027] (3) As shown in Table 2, the stirring time should be set to 8 minutes;

[0028] (4) As shown in Table 3, the KR stirring head is set to a speed of 60 rpm / min during the feeding period and a maximum speed of 90 rpm / min during the process.

[0029] After confirming the basic information of the furnace on site, the system started desulfurization according to the model. The actual amount of desulfurizing agent added during the process was 378 kg, the maximum speed was 90 rpm / min, and the stirring time was 8 min. After the desulfurization was completed, the sample analysis showed that [S] = 0.010%, which meets the process requirement of [S] ≤ 0.010%.

[0030] Example 2

[0031] (1) Basic information of the heat: Heat number 5349, initial [S] of molten iron = 0.022%, the target steel grade process requires [S] ≤ 0.005% after KR desulfurization, and the stirring head of the current heat is being used for the 70th time;

[0032] (1) As shown in Table 1, 722 kg of desulfurizing agent needs to be added;

[0033] (3) As shown in Table 2, the stirring time should be set to 11 minutes;

[0034] (4) As shown in Table 3, the KR stirring head is set to a speed of 60 rpm / min during the feeding period and a maximum speed of 90 rpm / min during the process.

[0035] After confirming the basic information of the furnace on site, the system started desulfurization according to the model. The actual amount of desulfurizing agent added during the process was 722 kg, the maximum speed was 90 rpm / min, and the stirring time was 11 min. After the desulfurization was completed, the sample analysis showed that [S] = 0.002%, which meets the process requirement of [S] ≤ 0.005%.

Claims

1. A highly efficient and low-cost method for desulfurizing molten iron by stirring (KR), characterized in that, The aforementioned stirring desulfurization method establishes a desulfurization model by determining the parameters in the KR desulfurization operation process: desulfurizing agent consumption, desulfurization stirring time, and stirring head rotation speed. The desulfurization process is divided into two categories: shallow desulfurization with a target [S] ≤ 0.010% and deep desulfurization with a target [S] ≤ 0.005%. Desulfurizing agent consumption is divided into 11 intervals based on the sulfur content of the molten iron. Each interval has a target for the deep / shallow desulfurization process based on the target steel grade. The amount of desulfurizing agent added is determined by a combination of theoretical calculations and on-site production experience. Desulfurization stirring time is divided into 6 intervals based on the sulfur content of the molten iron. Each interval has a target for the deep / shallow desulfurization process based on the target steel grade. The stirring time is determined based on on-site production experience and production scheduling. Stirring head speed is divided into 4 intervals based on the stirring head's lifespan. New stirring heads have good refractory material condition and large blade size, with a maximum speed of 85 rpm / min. Later, as the refractory material is corroded by molten iron and slag, the blade size gradually decreases. The speed is increased sequentially according to the stirring head's lifespan to ensure desulfurization efficiency.

2. The efficient and low-cost KR stirring desulfurization method for molten iron according to claim 1, characterized in that, The parameters during the KR desulfurization process are as follows: (1) The amount of desulfurizing agent to be added is determined based on the initial sulfur content of the molten iron and the target sulfur content after desulfurization, as shown in Table 1: Table 1. Desulfurizing agent dosage (kg / furnace) Note: The allowable deviation for the actual amount of desulfurizing agent added is ±20kg; (2) The stirring time is determined based on the initial sulfur content of the molten iron and the target sulfur content after desulfurization, as shown in Table 2: Table 2 Desulfurization stirring time (3) The stirring speed is determined based on the initial sulfur content of the molten iron and the target sulfur content after desulfurization, combined with the life of the stirring head, as shown in Table 3. Table 3 Desulfurization stirring head rotation speed 3. The efficient and low-cost KR stirring desulfurization method for molten iron according to claim 1 or 2, characterized in that, (1) Basic information of the heat: Heat number 5344, initial [S] of molten iron = 0.019%, the target steel grade process requires [S] ≤ 0.010% after KR desulfurization, and the stirring head of the current heat is being used for the 65th time; (2) As shown in Table 1, 378 kg of desulfurizing agent needs to be added; (3) As shown in Table 2, the stirring time should be set to 8 minutes; (4) As shown in Table 3, the KR stirring head is set to a speed of 60 rpm / min during the feeding period and a maximum speed of 90 rpm / min during the process. After confirming the basic information of the furnace on site, the system started desulfurization according to the model. The actual amount of desulfurizing agent added during the process was 378 kg, the maximum speed was 90 rpm / min, and the stirring time was 8 min. After the desulfurization was completed, the sample analysis showed that [S] = 0.010%, which meets the process requirement of [S] ≤ 0.010%.

4. The efficient and low-cost KR stirring desulfurization method for molten iron according to claim 1 or 2, characterized in that, (1) Basic information of the heat: Heat number 5349, initial [S] of molten iron = 0.022%, the target steel grade process requires [S] ≤ 0.005% after KR desulfurization, and the stirring head of the current heat is being used for the 70th time; (1) As shown in Table 1, 722 kg of desulfurizing agent needs to be added; (2) As shown in Table 2, the stirring time should be set to 11 min; (4) As shown in Table 3, the KR stirring head is set to a speed of 60 rpm / min during the feeding period and a maximum speed of 90 rpm / min during the process. After confirming the basic information of the furnace on site, the system started desulfurization according to the model. The actual amount of desulfurizing agent added during the process was 722 kg, the maximum speed was 90 rpm / min, and the stirring time was 11 min. After the desulfurization was completed, the sample analysis showed that [S] = 0.002%, which meets the process requirement of [S] ≤ 0.005%.

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