Molten iron charging operation method based on oxygen top-blown converter

Abstract

The invention belongs to the technical field of steel smelting, and particularly relates to a molten iron charging operation method based on an oxygen top-blown converter. Comprising the following steps: dividing a molten iron charging operation process into a preliminary reaction period, a rapid combustion period, a stable charging period and a rapid charging period according to a time sequence, and carrying out balanced control on the charging quantity and charging time of molten iron according to the flue gas condition of a furnace mouth in each period. According to the method, by analyzing and summarizing the relationship among the smoke and fire phenomena at the furnace mouth, the operation time of the molten iron and the charging amount of the molten iron, the charging process of the molten iron is divided into four stages, and regulation and control are performed according to the characteristics of each stage, so that the smoke and fire phenomena at the furnace mouth are effectively controlled, the waiting period is shortened, the operation efficiency is improved, and the production cost is reduced. And the operation time is shortened.

Description

Technical Field

[0001] The invention belongs to the technical field of steel smelting, and in particular relates to a molten iron feeding operation method based on an oxygen top-blown converter. Background Art

[0002] In the ferrous metal smelting industry, the oxygen lance top-blown converter smelting operation method is the traditional process for molten steel smelting. In the smelting production process, in order to reduce the smelting cost, it is necessary to load a certain amount of mixed scrap steel raw materials into the furnace and then pour molten iron into the furnace. This is one of the important production links in the converter smelting process. The mixed scrap steel added to the furnace includes raw materials such as steel slag, heavy scrap steel, steel bar briquettes, metal chip cakes, light crushed material cakes and light and thin metal loose scraps. These metal scraps are mixed with some flammable and explosive non-metallic impurities such as dust, filamentous fibers, paint, and lubricating oil. After entering the furnace, some impurities begin to burn under the scorching heat of the high-temperature flame in the furnace, and will not be completely burned in a short time. In the process of pouring molten iron into the furnace, those impurities that have not been completely burned quickly merge with the high-temperature molten iron above 1300℃ and explode, causing the temperature in the furnace to rise rapidly, forming a deflagration phenomenon. A large amount of smoke and dust suddenly appeared and quickly sprayed out from the furnace mouth, exceeding the maximum exhaust air volume of the dust removal system. Some smoke and fire rushed out of the furnace mouth, causing serious pollution to the environment in front of the furnace. In order to control the smoke and fire at the furnace mouth, the operation of molten iron entering the furnace was forced to stop, and the smoke outside the furnace was allowed to After relief, dumping is performed again. The whole operation process takes about 5 minutes. Taking a 120-ton top-blown converter as an example, the designed smelting cycle is 38 minutes. The operation process of molten iron entering the furnace accounts for 15.6% of the total smelting time of a single furnace. The length of time for molten iron to enter the furnace plays an important role in improving the efficiency of converter smelting operations and reducing smelting costs. At present, the operation process of molten iron entering the furnace is time-consuming and inefficient, and it will also cause environmental pollution in front of the furnace. The connection between the upper and lower processes is tight, and the facilities around the furnace mouth and the casting crane body are severely baked, which has become a restrictive link in converter smelting production. The current operation method of molten iron entering the furnace has the following problems:

[0003] 1. It is easy to cause pollution to the surrounding environment

[0004] During the process of molten iron feeding into the furnace, the contradiction between the amount of high-temperature molten iron entering the furnace and the light, flammable and explosive impurities in the furnace was not properly controlled, causing a large amount of smoke and dust to suddenly rush out of the furnace mouth, instantly exceeding the maximum air volume of the dust removal system. The overflowed smoke and dust drifted to the top of the factory building with the airflow, diffused into the surrounding environment, and caused air pollution at the production site.

[0005] 2. It is easy to burn equipment and facilities, shortening the service life of equipment and facilities;

[0006] The flames rushing out of the furnace mouth will completely engulf the equipment frame around the furnace mouth and the surrounding area of ​​the casting crane trolley. Although it only lasts for 2-3 minutes each time, over a long period of time, the surrounding frames are in a high temperature environment and burn holes appear. The strength of the casting crane body that is often in fire will also be reduced to varying degrees. Equipment and facilities are used in abnormal environments and may be taken offline prematurely in serious cases, shortening the online life of the equipment and facilities.

[0007] 3. Cause tension in the connection between upper and lower processes

[0008] During the iron adding process, the serious smoke and fire explosion at the furnace mouth forced the entire operation process to stop and wait for several long times. Due to the violent fire and smoke at the furnace mouth, the iron adding operation will be forced to be interrupted, and it is necessary to wait for 1-2 minutes until the flame and smoke are smaller before adding iron again. This causes the iron adding operation to be repeatedly interrupted several times. It takes about 5 minutes to complete an iron adding operation. For a 150-ton oxygen top-blown converter, when the amount of iron added to each furnace is calculated as 130 tons, the average adding speed is 0.44 tons / minute. The normal blowing cycle of a furnace of molten steel is generally designed to be 38 minutes. The time for adding iron alone accounts for 13.2% of the entire furnace smelting time. The low efficiency of the iron adding operation has a great impact on the continued production of each process, and it is impossible to ensure the efficient connection of the steelmaking process, which often causes tension in the connection of production processes.

[0009] 4. Fire hazards exist:

[0010] The top of the casting crane trolley and the end beam are equipped with wire rope drums and electrical equipment with a large amount of grease on the surface. When the high-temperature smoke and flames rush to the top of the casting machine trolley, the grease and electrical circuits are baked by the high-temperature flames, which can easily cause grease and electrical equipment fires, posing a fire safety hazard. Summary of the invention

[0011] The object of the present invention is to provide a method for feeding molten iron into an oxygen top-blown converter to solve the problems existing in the prior art.

[0012] The technical solution adopted by the present invention to solve its technical problem is:

[0013] A method for feeding molten iron into an oxygen top-blown converter comprises dividing the molten iron feeding process into a preliminary reaction period, a rapid combustion period, a stable feeding period and a rapid feeding period in chronological order, and performing balanced control of the amount of molten iron fed into the furnace and the time of feeding into the furnace according to the smoke conditions at the furnace mouth in each period.

[0014] Furthermore, the operation time of the initial reaction period is controlled within 18-22 seconds, and the amount of molten iron fed into the furnace is controlled within 3-4% of the total mass of the molten iron.

[0015] Furthermore, the operation time of the rapid combustion period is controlled within 28-32 seconds, and the amount of molten iron fed into the furnace is controlled within 22-24% of the total mass of the molten iron.

[0016] Furthermore, the operation time of the stable furnace-feeding period is controlled within 32-38 seconds, and the amount of molten iron fed into the furnace is controlled within 48-54% of the total mass of the molten iron.

[0017] Furthermore, the operation time of the rapid furnace-entry period is controlled within 5 seconds, and the amount of molten iron entering the furnace is controlled within 19-21% of the total mass of the molten iron.

[0018] The present invention has the following beneficial effects:

[0019] 1. The present invention analyzes and summarizes the relationship between the smoke and fire phenomena at the furnace mouth and the operation time of molten iron and the amount of molten iron entering the furnace, divides the molten iron entering the furnace process into four stages, and regulates and controls according to the characteristics of each stage, thereby effectively controlling the occurrence of smoke and fire phenomena at the furnace mouth, thereby reducing the waiting period, improving the operation efficiency, and shortening the operation time.

[0020] 2. Effectively prevent violent fire from occurring at the furnace mouth, avoid the furnace mouth equipment and overhead crane equipment from being engulfed in fire, avoid high-temperature damage to the equipment, ensure the safe operation of equipment and facilities, and eliminate fire hazards.

[0021] 3. The smoke is controlled within the dust removal hood, which solves the problem of severe smoke at the furnace mouth. The smoke problem in front of the furnace is completely solved, the air environment in front of the furnace is improved, and environmental pollution is eliminated.

[0022] 4. By rationally optimizing the operation process, the time for adding molten iron was reduced from 300 seconds to less than 100 seconds, and the average time for adding molten iron to each furnace was reduced by nearly 200 seconds, which improved the operation efficiency and reduced the impact on the smelting operation. It provided sufficient time for the smelting operation process and eliminated the adverse effects of the molten iron addition operation on the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a comparison diagram of the molten iron feeding operation curves of Example 1 of the present invention and Comparative Example 1. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and drawings. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0025] Comparative Example 1:

[0026] Taking a 150-ton oxygen top-blown converter as an example, the total amount of molten iron added to each furnace is calculated as 130 tons, and scrap steel is added before the molten iron enters the furnace. Currently, the molten iron entering the furnace is roughly divided into the following six stages:

[0027] (1) The first stage: The operation time is 10 seconds, 40 tons of molten iron is put into the furnace, an average of 4 tons / second, and the amount of molten iron dumped per unit time is the largest. The light and flammable materials on the surface of the scrap steel in the furnace react violently, and violent fire and smoke appear at the furnace mouth;

[0028] (2) The second stage: the operation time is 60 seconds, 0 tons of molten iron is put into the furnace, and the average is 0 tons / second. The operation of molten iron feeding into the furnace is stopped, and the smoke and fire are waiting to decrease. The waiting period is in progress.

[0029] (3) The third stage: The operation time is 10 seconds, 30 tons of molten iron is put into the furnace, an average of 3 tons / second. The amount of molten iron dumped per unit time is large. The low-melting-point metal impurities (such as galvanized layer, zinc, aluminum, lead, tin, etc.) in the furnace or the flammable oil and grease inside the semi-open container begin to react violently under the action of high-temperature molten iron, and severe flames and smoke appear at the furnace mouth. The furnace mouth again emits severe flames and smoke;

[0030] (4) The fourth stage: the operation time is 110 seconds, 0 tons of molten iron is put into the furnace, and the average is 0 tons / second. At this time, the low-melting-point metal impurities vaporize, evaporate, and burn for a long time. The operation of molten iron feeding into the furnace is stopped and the waiting period begins;

[0031] (5) The fifth stage: The operation time is 100 seconds, 30 tons of molten iron is put into the furnace, an average of 3 tons / second. After the low-melting-point metal is burned and vaporized, and the smoke and fire at the furnace mouth are relieved, the remaining molten iron in the ladle is poured into the converter. At this time, the bottom of the ladle is turned upside down, the auxiliary hook of the crane is lifted to a high position, and the load is large. The speed of molten iron entering the furnace is increased within a safe control range;

[0032] (6) The sixth stage: The operation time is 10 seconds, 30 tons of molten iron is put into the furnace, an average of 3 tons / second. The molten iron feeding operation is about to be completed. When the auxiliary hook crane is lifted to the high position, the remaining molten iron is poured into the converter at the fastest speed, and the molten iron feeding operation is completed.

[0033] like Figure 1 As shown in the figure, the operation curve of molten iron entering the furnace is drawn with the operation time as the horizontal axis and the remaining molten iron mass in the ladle as the vertical axis, as shown in the figure Figure 1 Shown by the dashed line.

[0034] Embodiment 1:

[0035] This embodiment takes a 150-ton oxygen top-blown converter as an example. The total amount of molten iron added to each furnace is calculated as 130 tons, and scrap steel is added before the molten iron enters the furnace.

[0036] A method for feeding molten iron into an oxygen top-blown converter comprises dividing the molten iron feeding process into a preliminary reaction period, a rapid combustion period, a stable feeding period and a rapid feeding period in chronological order, and performing balanced control of the amount of molten iron fed into the furnace and the time of feeding into the furnace according to the smoke conditions at the furnace mouth in each period.

[0037] (1) Initial reaction period: The operation time is controlled within 20 seconds, the amount of molten iron added to the furnace is 5 tons, and the average molten iron addition rate is about 0.25 tons / second. At this time, the amount of molten iron poured per unit time is small, the purpose is to first burn off the light flammable and explosive impurities on the surface of the scrap steel, thereby controlling the burning rate of light flammable materials in the furnace, controlling the fire and smoke at the furnace mouth, and making the smoke generation volume lower than the dust removal air volume. In this way, the flammable materials and dust inside the scrap steel will undergo stable and continuous combustion under the action of high-temperature molten iron at 1300℃, without any deflagration or explosion.

[0038] (2) Rapid combustion period: The operation time is controlled within 30 seconds, the amount of molten iron added to the furnace is 30 tons, and the average speed of adding molten iron is about 1 ton / second. During this stage, low-melting-point metal impurities (such as galvanized layer, zinc, aluminum, lead, tin, etc.) in the scrap steel or flammable oils and fats in the semi-open container begin to burn under the action of high-temperature molten iron. When adding molten iron, slowly increase the speed of molten iron entering the furnace. During the process of pouring molten iron, if there is a sign of sudden smoke at the furnace mouth, reduce the speed of molten iron entering the furnace in time, so as to reasonably control the amount of smoke and fire at the furnace mouth and avoid violent fire and smoke at the furnace mouth.

[0039] (3) Stable furnace loading period: The operation time is controlled within 35 seconds, the amount of molten iron loaded into the furnace is 70 tons, and the average molten iron loading speed is about 2 tons / second. During this stage, after the flammable and explosive impurities in the scrap steel are burned out, the molten iron is poured into the furnace in large quantities as quickly as possible, provided that the load of the furnace mouth and the auxiliary hook allows, to improve the efficiency of molten iron loading.

[0040] (4) Rapid furnace entry period: The operation time is controlled within 5 seconds, the amount of molten iron entering the furnace is 25 tons, and the average molten iron addition rate is about 5 tons / second. At this stage, the bottom of the molten iron ladle has exceeded the horizontal position of the trunnion, and then it is lifted by the auxiliary hook to quickly enter the furnace with the remaining molten iron, thus completing the molten iron furnace entry operation.

[0041] like Figure 1 As shown in the figure, the operation curve of molten iron feeding into the furnace is drawn with the operation time as the horizontal axis and the remaining molten iron mass in the ladle as the vertical axis. Figure 1 The solid line in is the molten iron feeding operation curve diagram of this embodiment.

[0042] Compared with Comparative Example 1, this embodiment controls the fire and smoke at the furnace mouth by controlling the operating time of each operating stage and the amount of molten iron entering the furnace. That is to say, in the early stage of entering the furnace, the amount of smoke generated at the furnace mouth is controlled by prolonging the reaction and combustion time of impurities and reducing the amount of molten iron entering the furnace, so that the smoke can be effectively sucked away by the dust removal device instead of being sprayed out from the furnace mouth, thereby reducing the waiting period and the total iron adding time is shortened from 300 seconds to 90 seconds, thereby greatly improving the operating efficiency and shortening the operating time.

[0043] Embodiment 2:

[0044] This embodiment provides a method for feeding molten iron into an oxygen top-blown converter. The method is basically the same as that in Embodiment 1, except that:

[0045] (1) Initial reaction period: The operation time is controlled at 18 seconds, the amount of molten iron added to the furnace is 3.9 tons, and the average molten iron addition rate is about 0.2 tons / second.

[0046] (2) Rapid combustion period: The operation time is controlled at 28 seconds, the amount of molten iron added to the furnace is 28.6 tons, and the average molten iron addition rate is about 1 ton / second.

[0047] (3) Stable furnace feeding period: The operation time is controlled at 32 seconds, the amount of molten iron fed into the furnace is 70.2 tons, and the average molten iron addition rate is about 2.2 tons / second.

[0048] (4) Rapid furnace entry period: The operation time is controlled within 5 seconds, the amount of molten iron entering the furnace is 24.7 tons, and the average molten iron addition rate is about 5.46 tons / second.

[0049] Compared with Example 1, the total iron adding time in this embodiment is 83 seconds, which is suitable for the case where the amount of scrap steel added is small. The less scrap steel added, the less impurities there are, and the corresponding furnace entry time can be appropriately shortened.

[0050] Embodiment 3:

[0051] This embodiment provides a method for feeding molten iron into a top-blown oxygen converter. The method is basically the same as that in Embodiment 1. The difference is that this embodiment takes a 120-ton top-blown oxygen converter as an example, and the total amount of molten iron added to each furnace is calculated as 104 tons:

[0052] (1) Initial reaction period: The operation time is controlled at 22 seconds, the amount of molten iron added to the furnace is 4.16 tons, and the average molten iron addition rate is about 0.19 tons / second.

[0053] (2) Rapid combustion period: The operation time is controlled at 32 seconds, the amount of molten iron entering the furnace is 24.96 tons, and the average molten iron addition rate is about 0.78 tons / second.

[0054] (3) Stable furnace feeding period: The operation time is controlled at 38 seconds, the amount of molten iron fed into the furnace is 55.12 tons, and the average molten iron addition rate is about 1.45 tons / second.

[0055] (4) Rapid furnace entry period: The operation time is controlled within 5 seconds, the amount of molten iron entering the furnace is 19.76 tons, and the average molten iron addition rate is about 3.95 tons / second.

[0056] Compared with Example 1, the total iron adding time in this embodiment is 97 seconds, which is suitable for the situation where the amount of scrap steel added is relatively large. The more scrap steel is added, the more impurities there are, and the corresponding furnace entry time needs to be appropriately extended.

[0057] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should all fall within the scope of protection of the present invention.

[0058] The techniques, shapes, and structural parts not described in detail in the present invention are all well-known techniques.

Claims

1. A method for feeding molten iron into a top-blown oxygen converter, characterized in that: This includes dividing the process of molten iron entering the furnace into the initial reaction period, the rapid combustion period, the stable entry period and the rapid entry period in chronological order, and in each period, balancing the amount of molten iron entering the furnace and the time of entering the furnace according to the flue gas conditions at the furnace mouth.

2. The method for charging molten iron into a top-blown oxygen converter according to claim 1, characterized in that: The operation time of the initial reaction period is controlled at 18-22 seconds, and the amount of molten iron fed into the furnace is controlled at 3-4% of the total mass of the molten iron.

3. The method for charging molten iron into a top-blown oxygen converter according to claim 1, characterized in that: The operation time of the rapid combustion period is controlled at 28-32 seconds, and the amount of molten iron fed into the furnace is controlled at 22-24% of the total mass of the molten iron.

4. The method for charging molten iron into a top-blown oxygen converter according to claim 1, characterized in that: The operation time of the stable furnace-feeding period is controlled at 32-38 seconds, and the amount of molten iron fed into the furnace is controlled at 48-54% of the total mass of the molten iron.

5. The method for charging molten iron into a top-blown oxygen converter according to claim 1, characterized in that: The operation time of the rapid furnace-entering period is controlled within 5 seconds, and the amount of molten iron entering the furnace is controlled within 19-21% of the total mass of the molten iron.

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