A high-silicon and low-sulfur hot metal discharge process

Abstract

The present invention discloses a high-silicon and low-sulfur molten iron discharge process, and relates to the technical field of blast furnace smelting. The present invention at least includes the following steps: S1: In the process of blast furnace iron tapping, extract the real-time parameters of blast furnace iron tapping: the blast furnace molten iron is discharged from the iron mouth, passes through the main ditch, and then separated by the slag skimmer, the molten iron flows into the iron ditch, and the slag flows into the slag ditch. By real-time online detection of the molten iron composition, the silicon content Si and sulfur content S in the molten iron and the molten iron temperature PT are obtained, and the data takes 1 data value every 5 minutes; S2: Select a number of sulfuric acid slag powders, which are by-products of the chemical system, and grind them to control the particle size to be less than 1mm and account for more than 80%, and process the sulfuric acid slag powder according to the method of preparing sulfur powder. The present invention is convenient and quick to operate by reducing silicon and increasing sulfur in the main ditch in front of the furnace, and the method adopted is low in cost. Compared with the steelmaking system, the cost loss caused by reducing silicon in the steelmaking link is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of blast furnace smelting, and in particular to a high-silicon and low-sulfur molten iron discharge process. Background Art

[0002] During the blast furnace smelting process, it is inevitable to produce high-silicon molten iron. Generally, the silicon content of molten iron is greater than 0.65%, and the silicon content of molten iron is at a relatively high level. The silicon content of molten iron is usually accompanied by a low sulfur content. When the sulfur content of molten iron is less than 15%, it is usually called low sulfur content of molten iron.

[0003] There is a corresponding relationship between the silicon content and the sulfur content in blast furnace iron. Under the same smelting conditions, high silicon content will inevitably lead to low sulfur content. In the blast furnace production process, the silicon and sulfur are pursued at an appropriate level. During the start-up, shutdown or abnormal blast furnace conditions, high silicon iron water is inevitable, especially during the start-up and shutdown of the blast furnace, which is in a high silicon and low sulfur iron water state for several days. During the abnormal blast furnace conditions, in order to avoid accidents such as low furnace temperature causing furnace cooling, it is necessary to increase the furnace temperature, which results in high silicon and low sulfur in the blast furnace iron water.

[0004] Under existing technical conditions, high silicon and low sulfur in molten iron will inevitably lead to poor fluidity of molten iron. When encountering molten iron with high silicon and low sulfur, it usually causes the molten iron in front of the furnace to stick together, increasing the difficulty of discharging molten iron. The molten iron is sticky enough, a large amount of graphite carbon is precipitated, and the graphite carbon powder will cause it to float, seriously affecting the environment of the blast furnace iron-making area and the health of the operators. There is currently no feasible solution to the problem of graphite carbon floating caused by high silicon molten iron.

[0005] Under the existing technical conditions, when high-silicon molten iron flows from the molten iron tank into the ladle, a large amount of molten iron adheres to the refractory materials on both sides of the molten iron tank. As the amount of adhesion increases, it is very easy to cause the molten iron tank to be overfilled and overflow, causing accidents. In such a situation, the operators in front of the furnace need to use a wooden stick to clean the adhesive in the molten iron tank area. The adhesive is cleaned off with a wooden stick. This operation requires opening the insulation cover of the molten iron tank. The personnel face high-temperature molten iron and the labor intensity is extremely high, and the risk is high.

[0006] Therefore, a new solution to the above problems needs to be proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a high-silicon and low-sulfur molten iron discharge process to solve the technical problems raised in the existing background technology.

[0008] To achieve the above object, the present invention provides the following technical solution: a high-silicon, low-sulfur molten iron discharge process, comprising at least the following steps:

[0009] S1: During the blast furnace tapping process, extract the real-time parameters of blast furnace tapping: molten iron from the blast furnace is discharged from the iron mouth, passes through the main ditch, and then separated by the slag skimmer. The molten iron flows into the iron ditch, and the slag flows into the slag ditch. Through real-time online detection of the molten iron composition, the silicon content Si and sulfur content S in the molten iron, and the molten iron temperature PT are obtained. This data takes 1 data value every 5 minutes;

[0010] S2: Select a number of sulfuric acid slag powders which are byproducts of the chemical system, grind them to control the particle size to less than 1 mm, accounting for more than 80%, process the sulfuric acid slag powder according to the method of preparing sulfur powder, so that the sulfur content in the sulfuric acid slag is controlled at 3%-5%, and classify the sulfuric acid slag powder according to the weight of 50g, 100g, 200g, 500g, 1000g and 2000g, and plastic seal them to form sulfuric acid slag bags with independent weight packaging;

[0011] S3: During the blast furnace iron-making process, the three parameters of molten iron silicon content, sulfur content and molten iron temperature are detected online in real time, and the corresponding treatment process is given according to different parameter responses.

[0012] Preferably, when the silicon content of the molten iron is detected to be greater than 1.25% in S3, a metal pipe with a diameter of 30-50 mm is used to introduce oxygen to the inside of the molten iron liquid surface on the side of the molten iron ditch at the rear end of the skimmer, and the oxygen valve is slowly opened to blow oxygen and reduce the silicon in the molten iron in the iron ditch. The oxygen flow rate is based on controlling the molten iron to have no splashing. When the oxygen increases to the point where molten iron splashes, the oxygen amount is reduced. As oxygen is blown into the molten iron, the silicon content of the molten iron gradually decreases. When the online detection data shows that the silicon content of the molten iron is less than 1.0%, other parameters are not adjusted, and the silicon content is maintained at less than 1.0%. At this time, the probability of molten iron overflowing with graphite carbon is greatly reduced, and the bonding phenomenon is basically eliminated.

[0013] Preferably, when oxygen blowing fails to reduce the silicon content of the molten iron to below 1.0%, simultaneous detection shows that the sulfur content of the molten iron is less than 0.012%, and sulfuric acid slag powder is added to the main channel.

[0014] Preferably, adding sulfate slag powder to the main ditch comprises at least the following steps:

[0015] In the initial stage, add 50g of sulfuric acid slag bag per minute according to the minimum amount. The adding point must be the landing point of the main trench where the molten iron flows out from the iron mouth in a parabolic shape. When adding, use a long metal pipe to support the sulfuric acid slag bag to the landing point. The plastic bag melts instantly when it encounters high temperature slag iron, and the sulfuric acid slag powder enters the main trench and mixes with the slag iron;

[0016] As the amount added increases, the sulfur content in the molten iron increases;

[0017] 5 minutes after adding, check the sulfur content of the molten iron in the iron ditch. When the sulfur content of the molten iron is still less than 0.015%, add a 100g bag of sulfuric acid slag in the next 5 minutes. 5 minutes after adding, check the sulfur content of the molten iron. If the sulfur content of the molten iron is increased to more than 0.015%, continue to add a 200g bag of sulfuric acid slag in the next cycle until the sulfur content of the molten iron is greater than 0.015%.

[0018] Preferably, during the process of adding sulfuric acid slag, part of the iron elements in the sulfuric acid slag will be reduced to molten iron and enter the iron ditch under the high temperature of the main ditch, and part of the oxides will generate slag and flow into the slag ditch. At this time, it is necessary to pay attention to whether the flow rate inside the slag ditch and the molten iron is within the target flow rate to avoid excessive flow overflowing the slag ditch and the iron ditch.

[0019] Preferably, when the two conditions that the silicon content of the molten iron in S3 is greater than 1.25% and the sulfur content of the molten iron is less than 0.15% are met at the same time, during the process of adding sulfuric acid slag, oxygen blowing is carried out simultaneously through the rear eye of the skimmer near the iron groove side. As the amount of sulfuric acid slag powder added increases, heat is lost inside the main groove and the temperature of the molten iron will decrease. The oxygen blowing of the skimmer can reduce the silicon content and increase the temperature of the molten iron at the same time.

[0020] Preferably, when the silicon content of the molten iron in S3 is less than 1.25% and the sulfur content of the molten iron is less than 0.010%, the fluidity of the molten iron in this state is also poor, and the iron ditch adhesion is also very serious. In this state, oxygen blowing is required on the side of the iron ditch behind the skimmer, and only a sulfuric acid slag bag needs to be added to the slag and iron falling point in the main ditch until the sulfur content of the molten iron is greater than 0.015%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention reduces silicon and increases sulfur in the main channel in front of the furnace, which is convenient and quick to operate, and the method adopted has low cost. Compared with the steelmaking system, the cost loss caused by reducing silicon in the steelmaking process is reduced. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0024] A high-silicon, low-sulfur molten iron discharge process comprises at least the following steps:

[0025] S1: During the blast furnace tapping process, extract the real-time parameters of blast furnace tapping: molten iron from the blast furnace is discharged from the iron mouth, passes through the main ditch, and then separated by the slag skimmer. The molten iron flows into the iron ditch, and the slag flows into the slag ditch. Through real-time online detection of the molten iron composition, the silicon content Si and sulfur content S in the molten iron, and the molten iron temperature PT are obtained. This data takes 1 data value every 5 minutes;

[0026] S2: Select a number of sulfuric acid slag powders which are byproducts of the chemical system, grind them to control the particle size to less than 1 mm, accounting for more than 80%, process the sulfuric acid slag powder according to the method of preparing sulfur powder, so that the sulfur content in the sulfuric acid slag is controlled at 3%-5%, and classify the sulfuric acid slag powder according to the weight of 50g, 100g, 200g, 500g, 1000g and 2000g, and plastic seal them to form sulfuric acid slag bags with independent weight packaging;

[0027] S3: During the blast furnace iron-making process, the three parameters of molten iron silicon content, sulfur content and molten iron temperature are detected online in real time, and the corresponding treatment process is given according to different parameter responses.

[0028] When the silicon content of molten iron detected in S3 is greater than 1.25%, a metal pipe with a diameter of 30-50mm is used to introduce oxygen to the inside of the molten iron liquid surface on the side of the molten iron ditch at the rear end of the skimmer, and the oxygen valve is slowly opened to blow oxygen and reduce silicon in the molten iron in the ditch. The oxygen flow rate is based on controlling the molten iron to prevent splashing. When the oxygen increases to the point where molten iron splashes, the oxygen amount is reduced. As oxygen is blown into the molten iron, the silicon content of the molten iron gradually decreases. Through online detection data, when the silicon content of the molten iron is less than 1.0%, other parameters do not need to be adjusted, and the silicon content is maintained at less than 1.0%. At this time, the probability of molten iron overflowing with graphite carbon is greatly reduced, and the bonding phenomenon is basically eliminated.

[0029] When oxygen blowing cannot reduce the silicon content of the molten iron to below 1.0%, synchronous detection shows that the sulfur content of the molten iron is less than 0.012%, and sulfuric acid slag powder is added to the main groove.

[0030] Adding sulfuric acid slag powder to the main ditch comprises at least the following steps:

[0031] In the initial stage, add 50g of sulfuric acid slag bag per minute according to the minimum amount. The adding point must be at the landing point where the molten iron flows out of the iron mouth in a parabolic curve in the main groove (the slag and iron flow separately at this landing point, and the reaction effect after adding sulfuric acid slag is the best). When adding, use a long metal pipe to support the sulfuric acid slag bag to the landing point. The plastic bag melts instantly when it encounters high temperature slag and iron, and the sulfuric acid slag powder enters the main groove and mixes with the slag and iron;

[0032] As the amount added increases, the sulfur content in the molten iron increases;

[0033] 5 minutes after adding, check the sulfur content of the molten iron in the iron ditch. When the sulfur content of the molten iron is still less than 0.015%, add a 100g bag of sulfuric acid slag in the next 5 minutes. 5 minutes after adding, check the sulfur content of the molten iron. If the sulfur content of the molten iron is increased to more than 0.015%, continue to add a 200g bag of sulfuric acid slag in the next cycle until the sulfur content of the molten iron is greater than 0.015%.

[0034] During the process of adding sulfuric acid slag, part of the iron elements in the sulfuric acid slag will be reduced to molten iron and enter the iron ditch under the high temperature of the main ditch, and part of the oxides will generate slag and flow into the slag ditch. At this time, it is necessary to pay attention to whether the flow inside the slag ditch and molten iron is within the target flow to avoid excessive flow overflowing the slag ditch and the iron ditch.

[0035] When the two conditions that the silicon content of molten iron in S3 is greater than 1.25% and the sulfur content of molten iron is less than 0.15% are met at the same time, during the process of adding sulfuric acid slag, oxygen is blown synchronously through the slag skimmer near the iron groove side. As the amount of sulfuric acid slag powder added increases, heat is lost inside the main groove and the molten iron temperature will decrease. The oxygen blowing of the slag skimmer can reduce the silicon content and increase the molten iron temperature at the same time.

[0036] When the silicon content of molten iron in S3 is less than 1.25% and the sulfur content of molten iron is less than 0.010%, the fluidity of molten iron in this state is also poor, and the iron ditch adhesion is also very serious. In this state, oxygen blowing is required on the side of the iron ditch behind the skimmer. It is only necessary to add a bag of sulfuric acid slag at the slag and iron falling point in the main ditch until the sulfur content of molten iron is greater than 0.015%.

[0037] The sulfate slag powder mainly comprises: Fe2O3: 20%-50%, SiO2: 15%-65%, Al2O3: 10%, CaO: 5%, MgO: 2%-5%, and S: 3%-5%.

[0038] During the process of adding sulfuric acid slag, the detected molten iron temperature value needs to be guaranteed to be within the normal range and cannot be lower than the lower limit of the molten iron temperature control target (usually the high silicon content in molten iron will inevitably correspond to a high molten iron temperature).

[0039] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A high-silicon, low-sulfur molten iron discharge process, characterized in that: At least the following steps are included: S1: In the process of blast furnace iron tapping, extract the real-time parameters of blast furnace iron tapping: blast furnace molten iron is discharged from the iron mouth, passes through the main ditch, and then separated by the slag skimmer. The molten iron flows into the iron ditch, and the slag flows into the slag ditch. Through real-time online detection of molten iron composition, the silicon content Si and sulfur content S in the molten iron and the molten iron temperature PT are obtained. The data takes one data value every 5 minutes; S2: Select a number of sulfuric acid slag powders which are byproducts of the chemical system, grind them to control the particle size to less than 1 mm, accounting for more than 80%, process the sulfuric acid slag powder according to the method of preparing sulfur powder, so that the sulfur content in the sulfuric acid slag is controlled at 3%-5%, and classify the sulfuric acid slag powder according to the weight of 50g, 100g, 200g, 500g, 1000g and 2000g, and plastic seal them to form sulfuric acid slag bags with independent weight packaging; S3: During the blast furnace iron-making process, the three parameters of molten iron silicon content, sulfur content and molten iron temperature are detected online in real time, and the corresponding treatment process is given according to different parameter responses; When the silicon content of the molten iron is detected to be greater than 1.25% in the S3, a metal pipe with a diameter of 30-50 mm is used to introduce oxygen to the inside of the molten iron liquid surface at the rear end of the skimmer near the side of the molten iron ditch, and the oxygen valve is slowly opened to blow oxygen to reduce silicon in the molten iron in the ditch. The oxygen flow rate is based on controlling the molten iron to have no splashing. When the oxygen is increased to the point where there is splashing of molten iron, the oxygen amount is reduced. As oxygen is blown into the molten iron, the silicon content of the molten iron is gradually reduced. When the silicon content of the molten iron is less than 1.0% through online detection data, other parameters are not adjusted, and the silicon content is maintained at less than 1.0%. At this time, the probability of molten iron overflowing with graphite carbon is greatly reduced, and the bonding phenomenon is basically eliminated; When oxygen blowing fails to reduce the silicon content of the molten iron to below 1.0%, simultaneous detection shows that the sulfur content of the molten iron is less than 0.012%, and sulfuric acid slag powder is added to the main groove; The adding of sulphuric acid slag powder into the main channel comprises at least the following steps: In the initial stage, add 50g of sulfuric acid slag bag per minute according to the minimum amount. The adding point must be the landing point of the main trench where the molten iron flows out from the iron mouth in a parabolic shape. When adding, use a long metal pipe to support the sulfuric acid slag bag to the landing point. The plastic bag melts instantly when it encounters high temperature slag iron, and the sulfuric acid slag powder enters the main trench and mixes with the slag iron; As the amount added increases, the sulfur content in the molten iron increases; 5 minutes after adding, check the sulfur content of the molten iron in the iron ditch. When the sulfur content of the molten iron is still less than 0.015%, add a 100g bag of sulfuric acid slag in the next 5 minutes. 5 minutes after adding, check the sulfur content of the molten iron. If the sulfur content of the molten iron is increased to more than 0.015%, continue to add a 200g bag of sulfuric acid slag in the next cycle until the sulfur content of the molten iron is greater than 0.015%.

2. A high-silicon, low-sulfur molten iron discharge process according to claim 1, characterized in that: During the process of adding sulfuric acid slag, part of the iron elements in the sulfuric acid slag will be reduced to molten iron and enter the iron ditch under the high temperature of the main ditch, and part of the oxides will generate slag and flow into the slag ditch. At this time, it is necessary to pay attention to whether the flow inside the slag ditch and molten iron is within the target flow to avoid excessive flow overflowing the slag ditch and the iron ditch.

3. A high-silicon, low-sulfur molten iron discharge process according to claim 1, characterized in that: When the two conditions that the silicon content of the molten iron in S3 is greater than 1.25% and the sulfur content of the molten iron is less than 0.15% are met at the same time, during the process of adding sulfuric acid slag, oxygen is blown synchronously through the slag skimmer near the iron groove side. As the amount of sulfuric acid slag powder added increases, heat is lost inside the main groove, and the molten iron temperature will decrease. The oxygen blowing of the slag skimmer can reduce the silicon content and increase the molten iron temperature at the same time.

4. A high-silicon, low-sulfur molten iron discharge process according to claim 1, characterized in that: When the silicon content of the molten iron in S3 is less than 1.25% and the sulfur content of the molten iron is less than 0.010%, the fluidity of the molten iron in this state is also poor, and the iron groove adhesion is also very serious. In this state, oxygen blowing is required on the side of the iron groove behind the skimmer. It is only necessary to add a sulfuric acid slag bag at the slag and iron landing point in the main groove until the sulfur content of the molten iron is greater than 0.015%.