210t converter protection method under low iron consumption condition

Abstract

The invention relates to the technical field of steelmaking converter smelting, in particular to a 210t converter protection method under a low iron loss condition, which comprises the following steps: step 1, feeding raw materials into a converter; 2, smelting and furnace protection; and 3, splashing slag to protect the furnace. According to the method, burdening of the waste steel hopper is regulated and controlled firstly, then smelting furnace protection and slag splashing furnace protection are conducted in sequence, heat balance of converter smelting is achieved under the condition of low iron consumption, and the end point C / T double hit rate is increased.

Description

Technical Field

[0001] The present invention relates to the technical field of steelmaking converters, and particularly relates to a method for protecting the lining of a 210t converter under the condition of low iron consumption. Background Art

[0002] Converter steelmaking uses hot metal, scrap steel, and ferroalloys as the main raw materials. Without relying on external energy, the steelmaking process is completed in the converter by the physical heat of the hot metal itself and the heat generated by the chemical reactions between the components of the hot metal. As the key equipment for converter steelmaking, the capacity of the converter is directly related to the production efficiency and quality of steel. According to the different capacity tons, converters can be divided into small converters, medium converters, and large converters. The capacity of small converters is usually below dozens of tons, suitable for small-scale production or experimental purposes; the capacity of medium converters is between dozens of tons and one hundred tons, widely used in small and medium-sized steel mills; while large converters have a higher capacity, reaching hundreds of tons or even higher, and are the core production equipment of large steel enterprises. In recent years, with the continuous development and technological progress of the steel industry, large converters have become the mainstream converters in steel enterprises at home and abroad.

[0003] Scrap steel is an important part of the metal materials in the converter production and smelting process. Increasing the scrap ratio in the converter can reduce the hot metal consumption per ton of steel and alleviate the shortage of raw materials for steelmaking. However, since hot metal is both the main metal material for steelmaking and the main heat source for converter smelting, reducing the hot metal consumption per ton of steel will break the original heat balance of converter smelting production, reduce the hit rate of the end point and the smelting quality, and at the same time cause damage to the furnace lining. Large converters are generally used to smelt high-grade steel grades such as 9Ni steel, Q890D / Q960E high-strength steel, and X60 / X65 / X70 pipeline steel. The smelting production usually requires a large amount of heat, and high-grade steel grades have high requirements for end point control. It is difficult to protect the furnace lining under the condition of low iron consumption. Summary of the Invention

[0004] Aiming at the problem that it is difficult to protect the furnace lining of large converters under the condition of low iron consumption in the prior art, the present invention provides a method for protecting the lining of a 210t converter under the condition of low iron consumption. First, the batching of the scrap steel bucket is regulated, and then smelting furnace lining protection and slag splashing furnace lining protection are carried out in sequence, realizing the heat balance of converter smelting under the condition of low iron consumption and improving the double hit rate of end point C / T.

[0005] The technical solution of the present invention is as follows: A method for protecting the lining of a 210t converter under the condition of low iron consumption, comprising the following steps: Step 1: Feed the raw materials into the furnace and charge the scrap steel bucket. The scrap steel includes iron blocks, steel bar compacts, self-produced scrap steel and purchased scrap steel, heavy scrap and slag steel. By mass percentage, the addition amount of iron blocks is 21% - 43%, the addition amount of steel bar compacts is 7% - 22%, the addition amount of self-produced scrap steel and purchased scrap steel is 28% - 41%, the addition amount of heavy scrap is 7% - 22%, and the addition amount of slag steel is 2% - 4%. At the bottom of the scrap steel bucket, lay some iron blocks, heavy scrap, mixed materials, steel bar compacts, self-produced scrap steel and purchased scrap steel, slag steel and the remaining iron blocks in sequence. The mass of the scrap steel is the total mass of the iron blocks, steel bar compacts, self-produced scrap steel and purchased scrap steel, heavy scrap and slag steel. Step 2: After the raw materials are fed into the furnace, carry out smelting and furnace protection. Control the alkalinity in the early stage of blowing to be 2.0 - 2.5, the end-point temperature to be 1600 - 1630 °C, the TSC to be controlled at 1560 - 1590 °C, the corresponding carbon to be 0.40% - 0.20%, and the end-point oxygen content to be controlled at 300 - 452 ppm. Step 3: After the smelting and furnace protection is completed, carry out slag splashing for furnace protection. Adopt the converter automatic slag splashing model. When the viscosity of the final slag is less than 0.02 Pa·S, use the thin final slag mode; when the viscosity of the final slag is 0.02 - 0.10 Pa·S, use the normal mode; when the viscosity of the final slag is greater than 0.10 Pa·S, use the thick final slag mode; when the thickness of the furnace bottom ≤ 500 mm, use the furnace bottom swelling mode; when the thickness of the furnace bottom ≥ 1000 mm, use the furnace bottom lowering mode.

[0006] Furthermore, in Step 1, the mass of the iron blocks laid at the bottom of the scrap steel bucket is 55% - 70% of the addition amount of the iron blocks, preferably 60%. Laying iron blocks at the bottom of the scrap steel bucket can prevent the steel bar compacts from being squeezed and not moving down when adding scrap steel, resulting in blocked scrap steel. Adding heavy scrap later can prevent the heavy scrap from entering and being wrapped in the slag immediately. The addition amounts of the iron blocks and heavy scrap can be adjusted dynamically according to the molten iron situation. Laying iron blocks at the bottom of the scrap steel bucket first, then adding heavy scrap, and then adding mixed materials and steel bar compacts can reduce the blockage of the furnace mouth and the impact of heavy materials on the large surface in the front, reduce the single-furnace heavy scrap, thereby reducing the number of times of patching the front large surface and improving the converter operation efficiency.

[0007] Furthermore, in step one, when the silicon content of the molten iron is less than 0.2 wt% and / or the temperature of the molten iron is lower than 1350 °C, 5-10 t of pig iron blocks are used to replace the same mass of self-produced scrap steel and purchased scrap steel. After the scrap steel is added to the converter, the converter is tilted to -45° towards the tapping side to make the scrap steel adhered to the slag-dumping surface of the converter fall off, avoiding the risk brought by the adhered scrap steel under the condition of low iron consumption, ensuring that the heat promotes the uniform heating of the converter, melting all the scrap steel, and reducing the production cost of converter steelmaking. On the one hand, the cooling effect of an equal mass of pig iron blocks is about 2 / 3 of the cooling effect of an equal mass of scrap steel. Replacing an equal mass of self-produced scrap steel and purchased scrap steel with an equal mass of pig iron blocks can reduce the heat loss during converter steelmaking. On the other hand, the pig iron blocks contain a certain amount of silicon element, which will be released into the molten iron as the pig iron blocks melt and generate heat in the molten iron, making up for the lack of temperature to a certain extent, improving the end-point hitting rate, and thus reducing the number of after-blowing times to achieve the effect of protecting the furnace.

[0008] Furthermore, in step two, for the molten iron with rich heat, cold materials need to be added in the early stage of blowing. When the total addition amount of cold materials > 5 t, the addition amount of cold materials in the early stage of blowing is 60% of the total addition amount of cold materials, and the cold materials are limestone and lump ore. When the total addition amount of cold materials is 3-5 t, the addition amount of cold materials in the early stage of blowing is 40%-60% of the total addition amount of cold materials, and the cold materials are raw dolomite and sinter. When the total addition amount of cold materials < 3 t, the addition amount of cold materials in the early stage of blowing is 20%-40% of the total addition amount of cold materials, and the cold materials are light-burned dolomite and sinter. Adding cold materials can reduce the temperature to a certain extent to ensure the dephosphorization effect of the slag, improve the quality of molten steel, achieve rapid tapping, and reduce the furnace foaming time.

[0009] Furthermore, in step two, ferrosilicon and a temperature-raising agent are used to increase the temperature of the molten iron. The silicon content of the ferrosilicon is 73%, and the temperature-raising agent is anthracite. In the present invention, 100 kg of ferrosilicon can raise the temperature by 6-8 °C, and 100 kg of the temperature-raising agent can raise the temperature by 3-4 °C. The addition of ferrosilicon and the temperature-raising agent can reduce the situation of insufficient heat in the process.

[0010] Furthermore, in step two, the magnesia content of the final slag is 8%-9%, preferably 8.5%. The present invention improves the magnesia content of the final slag by regulating the magnesia content of the final slag and the addition amount of the slag splashing material; by controlling the end-point oxygen content at 300-450 ppm, the oxygen content of the molten steel is reduced, thereby reducing the erosion degree of the furnace lining.

[0011] Furthermore, in step two, the oxygen supply intensity in the starting stage and the ending stage of feeding of blowing is 3.6-3.8 Nm 3 / (t·min). The present invention increases the oxygen supply intensity in the starting stage and the ending stage of feeding of blowing, which is beneficial to promoting the heating of the molten pool in the early stage of blowing.

[0012] Further, in step three, for the final slag dilution mode, high-low-high-low lance positions are adopted, and the nitrogen flow rate is 1080 Nm 3 / min. The height and residence time of the lance position are in sequence as follows: 2300 mm for 5 s, 800 mm for 75 s, 2000 mm for 20 s, 1700 mm for 30 s, 1400 mm for 30 s, 1200 mm for 40 s, 900 mm for 25 s, 600 mm for 25 s. The slag splashing ends. The final slag dilution mode is applicable to the molten pool situation with low viscosity of the final slag; for the normal mode, high-low lance positions are adopted to penetrate the slag and maintain the furnace bottom and molten pool, and the nitrogen flow rate is 1000 Nm 3 / min. The height and residence time of the lance position are in sequence as follows: 2400 mm for 20 s, 1000 mm for 50 s, 2000 mm for 30 s, 1000 mm for 20 s, 1700 mm for 20 s, 1700 mm for 15 s, 1400 mm for 15 s, 1000 mm for 15 s, 1500 mm for 15 s. The slag splashing ends. The normal mode is applicable to the molten pool situation with moderate viscosity of the final slag; for the final slag thickening mode, high-low lance positions are adopted for slag splashing, and the nitrogen flow rate is 1000 Nm 3 / min. The height and residence time of the lance position are in sequence as follows: 2600 mm for 5 s, 1000 mm for 25 s, 1600 mm for 55 s, 1300 mm for 20 s, 1000 mm for 40 s, 700 mm for 20 s. The slag splashing ends. The final slag thickening mode is applicable to the molten pool situation with high viscosity of the final slag; for the furnace bottom rising mode, high lance positions are adopted for slag splashing to maintain the furnace bottom, and the nitrogen flow rate is 1080 Nm 3 / min. The height and residence time of the lance position are in sequence as follows: 2600 mm for 5 s, 1300 mm for 25 s, 2500 mm for 70 s, 2200 mm for 25 s, 2000 mm for 25 s, 1700 mm for 25 s, 1500 mm for 15 s, 1300 mm for 15 s. The slag splashing ends. The furnace bottom rising mode is applicable to the molten pool situation with a weak furnace bottom; for the furnace bottom lowering mode, low lance positions are adopted for slag splashing to lower the furnace bottom, and the nitrogen flow rate is 1170 Nm 3 / min. The height and residence time of the lance position are in sequence as follows: 2400 mm for 5 s, 700 mm for 20 s, 900 mm for 70 s, 1100 mm for 20 s, 1300 mm for 20 s, 900 mm for 50 s, 600 mm for 40 s. The slag splashing ends. The furnace bottom lowering mode is applicable to the molten pool situation with an excessive furnace bottom thickness.

[0013] Further, in step three, a temperature-raising agent is used for deoxidation; when the end-point temperature > 1620°C, the addition amount of slag splashing seasoning is 1 - 2t. The slag splashing seasoning can be added before slag splashing, and its main function is to adjust the temperature of the slag; when the end-point temperature is 1610°C - 1620°C, the addition amount of slag splashing seasoning is 0.8 - 1.2t, preferably 1t. The addition timing of the slag splashing seasoning can be adjusted according to the temperature of the steel grade; when the end-point temperature < 1610°C, the addition amount of slag splashing seasoning < 1t. The slag splashing seasoning can play a role in proper deoxidation and increase the magnesium oxide content in the slag. In the present invention, the magnesium oxide content w(MgO) of the light-burned magnesia balls is 64.5%, the magnesium oxide content w(MgO) of the raw dolomite is 34.3%, and the magnesium oxide content w(MgO) of the light-burned dolomite is 33%. The present invention selects the slag adjusting agent according to the end-point temperature and controls the addition amount of the slag adjusting agent, realizing precise seasoning, reducing the addition amount of the solvent, and precisely controlling the MgO content of the slag by optimizing the slag charge.

[0014] When the end-point temperature > 1620°C, the slag splashing materials are raw limestone and raw dolomite, and the solvents are one or several of raw limestone, raw dolomite, lump ore, and light-burned magnesia balls; when the end-point temperature is 1610°C - 1620°C, the slag splashing materials are light-burned dolomite or lime, and the solvents are raw limestone and light-burned magnesia balls; when the end-point temperature < 1610°C, the slag splashing material is light-burned magnesia balls, and the solvents are raw limestone and light-burned magnesia balls Further, it also includes daily furnace repair. During the process from step one to step three or after step three ends, the thickness of the furnace lining is monitored in real time. When the thickness of the molten steel and scrap impact area of the converter furnace lining ≤ 600mm, the molten steel and scrap impact area of the converter furnace lining is repaired by splashing with pig iron and / or repairing with raw dolomite blocks; when the thickness of both sides of the molten pool ≤ 500mm, both sides of the molten pool are repaired by manual feeding and / or spraying repair materials; when the thickness of the tapping surface and the furnace bottom ≤ 500mm, the tapping surface and the furnace bottom are repaired with furnace repair materials; during daily furnace repair, the basicity of the final slag of the previous furnace for furnace repair is 2.8 - 3.0, the TFe content is 14% - 16%, preferably 15%, and the magnesium oxide content is 8% - 10%, preferably 7%. The present invention controls the TFe content of the final slag of the previous furnace for furnace repair within 14% - 16%, which can avoid the weakening of the slag splashing layer on the furnace wall caused by too high TFe content (higher than 18%) in the final slag and the difficulty of adhering the furnace repair materials to the furnace wall.

[0015] The beneficial effects of the present invention are as follows: The present invention provides a method for protecting the lining of a 210t converter under the condition of low iron consumption. By sequentially regulating the process parameters of scrap bucket batching, smelting furnace lining protection, and slag splashing furnace lining protection, the converter lining life of the 210t converter throughout the campaign reaches 10,000+ heats. The carbon-oxygen product is stably controlled at an average of below 0.0020, the double hit rate of end-point C / T is controlled at 99.8%, the TFe content of the final slag is reduced to 12.58% under the condition of low iron consumption, which has a qualitative improvement in improving the lining life and stable production, realizes the smelting heat balance, reduces the number of afterblows, and continuous overoxidation at the end of smelting, which can reduce the erosion of the furnace lining and has good popularization value. Detailed implementation mode

[0016] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0017] Example 1 This example is used for the smelting and converter maintenance of conventional hot metal with a silicon content of 0.20%-0.40% and a temperature of 1350-1400°C under the condition of low iron consumption. The iron consumption is 785 kg / t, the hot metal addition amount is 181 t, and the scrap addition amount is 69 t.

[0018] A method for protecting the lining of a 210t converter under the condition of low iron consumption includes the following steps: Step 1: Raw materials are charged into the furnace, and the scrap bucket is batched. The addition amount of iron blocks is 25 t, the addition amount of steel bar briquettes is 10 t, the addition amount of self-produced scrap and purchased scrap is 20 t, the addition amount of heavy scrap is 10 t, and the addition amount of slag steel is 2 t. The bottom of the scrap bucket is sequentially paved with some iron blocks, heavy scrap, general material, steel bar briquettes, self-produced scrap and purchased scrap, slag steel, and the remaining iron blocks in sequence. Among them, the mass of the iron blocks paved at the bottom of the scrap bucket is 14 t, and the remaining iron blocks are arranged at the top and batched together with the slag steel. The hot metal processed in this example is conventional hot metal, and the heat of the hot metal is sufficient, so the heat in the early stage of blowing can be fully utilized by the scrap to balance. The slag retention operation is adopted, the slag pouring angle is 160-165°, and the slag retention amount is 1-2 t to reduce the consumption of fluxes. The alkalinity and a certain amount of TFe in the slag of the previous heat are used to ensure slag melting in the early stage of blowing, so that the molten pool is heated evenly and the situation of sticking scrap is avoided.

[0019] Step 2: After the raw materials are charged into the furnace, smelting and furnace protection are carried out. The alkalinity in the early stage of blowing is controlled at 2.5. Lime and lightly burned magnesia balls are used as slag-making materials. The total addition amount of lime is 28 kg / t, and the total addition amount of lightly burned magnesia balls is 1200 kg / furnace. In the early stage of blowing, cold materials are added according to the above ratio according to the molten iron situation. The lance height at the start of blowing is 2600 mm. When blowing for about 4 minutes, the lance height is reduced to 2100 mm. The oxygen pressure at the start of blowing is 0.85 MPa, and the oxygen supply intensity is 3.6 Nm 3 / (t·min). About 1 min 30 s after the feeding is completed, the oxygen pressure is adjusted to 0.9 MPa, and the oxygen supply intensity is adjusted to 3.8 Nm 3 / (t·min). Under normal molten iron conditions, the molten pool temperature in the early stage of blowing is relatively moderate, and the lance height can be appropriately higher to reduce the explosive splash caused by the intense reaction in the early stage of blowing. According to the process control and the end-point requirements of the steel grade, the process temperature is reduced. The TSC is controlled at 1560 - 1590 °C, the corresponding carbon is 0.40% - 0.20%, the end-point oxygen content is controlled at 302 - 400 ppm, the end-point temperature is 1610 - 1625 °C, the TFe content in the final slag is reduced to 14.89% - 15.45%, the viscosity of the final slag is increased, and the MgO content in the final slag is above 8.5% to achieve rapid tapping and reduce the furnace foaming time. The end-point temperature, end-point oxygen content, TFe content in the final slag, consumption of slag splashing materials, nitrogen consumption, and iron consumption of each heat are shown in Table 1.

[0020] Table 1 Smelting and furnace protection parameters of each heat in Example 1

[0021] Step 3: After the smelting and furnace protection are completed, slag splashing and furnace protection are carried out. Combining with the end-point control, for over-oxidized heats, deoxidizing substances are added to deoxidize the furnace slag. After tapping is completed, 50 - 100 kg of heating agent is added into the furnace for deoxidation. The heating agent is anthracite to reduce the FeO content in the slag and the consumption of slag splashing materials. The normal mode of the converter automatic slag splashing model is selected for slag splashing. In the normal mode, the bottom and molten pool of the furnace are maintained by high and low lance heights to penetrate the slag. The nitrogen flow rate is 1000 Nm 3 / min. The height and residence time of the lance are in the following order: 2400 mm for 20 s, 1000 mm for 50 s, 2000 mm for 30 s, 1000 mm for 20 s, 1700 mm for 20 s, 1700 mm for 15 s, 1400 mm for 15 s, 1000 mm for 15 s, 1500 mm for 15 s, and the slag splashing ends. For conventional molten iron, lightly burned dolomite is used for slag splashing. After the gas is turned on for slag splashing, seasoning is carried out. The slag splashing materials are added in batches. The addition amount of each batch of slag splashing materials is 500 kg, the total addition amount of slag splashing materials is 1 t, and the nitrogen consumption is 20 Nm³ / t.

[0022] Step 4: After the slag splashing for furnace lining protection is completed, routine furnace patching is carried out. Throughout the day, the thickness of the furnace lining is quickly detected and efficiently monitored in real-time online dynamically through a converter furnace lining (fixed type) thickness gauge. The furnace patching method and time are selected according to the measured thickness of the furnace lining, and a temperature measuring gun is used to measure the temperature of the furnace shell to ensure the safety of the furnace lining. During conventional hot metal smelting, the impact area of hot metal and scrap is relatively weak. Pig iron lumps and dolomite lumps are used for splash patching and maintenance of the impact area. Through this furnace patching method, it is fast and has remarkable effects. The basicity of the final slag in the previous furnace before patching is 2.8 - 3.0, the TFe content is 15%, and the magnesia content is 7% - 9%.

[0023] Using the converter furnace lining protection method for 210t under low iron consumption conditions provided in this embodiment can make the raw material charging ratio reasonable, reduce the probability of sticky scrap, stably control the end point temperature at 1610 - 1620°C, reduce the TFe content of the final slag to about 15%, achieve rapid tapping of the final slag, reduce the bubbling furnace time, reduce the erosion of the molten slag on the furnace lining, and bring convenience to daily production.

[0024] Example 2 This embodiment is used for the smelting of hot metal for heat supplement with silicon content < 0.20% and temperature < 1350°C and the maintenance of the converter under low iron consumption conditions. The iron consumption is 782 kg / t, the hot metal addition amount is 180t, and the scrap addition amount is 70t.

[0025] A converter furnace lining protection method for 210t under low iron consumption conditions includes the following steps: Step 1: Charge the raw materials. In the scrap bucket batching, the addition amount of iron lumps is 30t, the addition amount of steel bar compacts is 5t, the addition amount of self-produced scrap and purchased scrap is 28t, the addition amount of heavy scrap is 5t, and the addition amount of slag steel is 2t. To prevent sticky scrap on the furnace lining, the slag splashing on the previous converter is splashed dry and less slag is left. The slag retention amount ≤ 1.5t. After adding the scrap, tilt the furnace to -45° towards the tapping side at an angle of 165° to prevent large pieces of scrap from sticking to the slag pouring side and avoid the appearance of liquid slag. If there is a small amount of liquid slag in the furnace, add 1000 kg of lime, perform ±45° furnace tilting twice before and after, and then carry out the scrap charging operation. The bottom of the scrap bucket is successively paved with some iron lumps, heavy scrap, mixed materials, steel bar compacts, self-produced scrap and purchased scrap, slag steel and the remaining iron lumps in sequence. Among them, the mass of the iron lumps paved at the bottom of the scrap bucket is 18t, and the remaining iron lumps are placed on the top and batch with the slag steel.

[0026] Step 2: After the raw materials are charged into the furnace, smelting and furnace protection are carried out. Ferrosilicon and a heating agent are used for supplementary heating. Among them, the dosage of ferrosilicon ≤ 1000 kg, the dosage of the heating agent ≤ 2500 kg, and the heating agent is anthracite. By means of delayed feeding, the molten bath temperature in the early stage of blowing is increased to about 1350 °C, the feeding is delayed for about 35 s, the basicity in the early stage of blowing is 2.0 - 2.2, the solvent is added at 60%, the total amount of lime added is 26 kg / t, the addition amount of lightly burned magnesia balls is 1000 kg / furnace, and the remaining materials are added supplementarily when the CO content reaches more than 30%. The oxygen pressure at the start of blowing is 0.9 MPa, and the oxygen supply intensity is 3.8 Nm 3 / (t·min). The stirring speed is increased to promote the rapid increase of the molten bath temperature. The lance position at the start of blowing is 2600 mm. When blowing for about 3 minutes, the lance position is lowered by 2000 mm to avoid the sharp increase of the FeO content caused by long-term low temperature, resulting in slag splashing. When the molten bath temperature rises to about 1400 °C, the lance position is increased, the oxygen pressure is adjusted to 0.85 MPa, and the oxygen supply intensity is adjusted to 3.6 Nm 3 / (t·min) to avoid the back-dry splashing caused by the increase of the molten bath temperature and the excessive cracking of the carbon-oxygen reaction. In the later stage of the blowing operation, the lance position is gradually lowered, and rapid stirring is carried out to control the foam splashing and ensure that the scrap steel and materials are completely melted. The final oxygen content is controlled at 398 - 452 ppm, the final temperature is controlled at 1600 - 1610 °C, and the steel is tapped quickly after the final lance is lifted to reduce the temperature drop. The TFe content of the final slag is 14.98% - 15.55%, and the viscosity of the final slag is increased (the MgO content is 8% - 10%). The final temperature, final oxygen content, TFe content of the final slag, dosage of the slag splashing material, nitrogen consumption, and iron consumption of each heat are shown in Table 2.

[0027] Table 2 Smelting and furnace protection parameters of each heat in Example 2

[0028] Step 3: After the smelting and furnace protection are completed, slag splashing and furnace protection are carried out. Combining with the end point control, for the over-oxidized heats, deoxidizing substances are added to the furnace for deoxidation treatment. After the steel tapping is completed, 100 - 200 kg of the heating agent is put into the furnace for deoxidation to reduce the FeO content in the slag. The converter automatic slag splashing model is selected as the final slag thinning or swelling furnace bottom mode. The final slag thinning mode adopts the high-low-high-low lance position, and the nitrogen flow rate is 1080 Nm 3 / min. The height and residence time of the lance position are in sequence as follows: 2300 mm for 5 s, 800 mm for 75 s, 2000 mm for 20 s, 1700 mm for 30 s, 1400 mm for 30 s, 1200 mm for 40 s, 900 mm for 25 s, 600 mm for 25 s, and the slag splashing ends; the swelling furnace bottom mode adopts high lance position slag splashing to maintain the furnace bottom, and the nitrogen flow rate is 1080 Nm 3 / min. The height and residence time of the lance position are, in sequence, 2600 mm for 5 s, 1300 mm for 25 s, 2500 mm for 70 s, 2200 mm for 25 s, 2000 mm for 25 s, 1700 mm for 25 s, 1500 mm for 15 s, 1300 mm for 15 s, and then slag splashing ends. The amount of slag in hot metal with insufficient heat is relatively small, and the final slag is poor. Light-burned magnesia balls are used for slag splashing, and the consumption of slag-splashing materials < 1 t. The slag-splashing effect can be improved by this slag-splashing method.

[0029] Step 4: After slag splashing for furnace protection is completed, routine furnace patching is carried out. When smelting hot metal with low iron consumption and supplementary heat, the temperature of the molten pool is low in the early stage of blowing, there is an abundance of FeO, and the erosion on both sides of the molten pool is relatively serious. Manual feeding and gunning materials are used for furnace patching. When the bottom of the furnace is weak, the furnace is rocked twice at ±50° after slag splashing to form slag on the furnace bottom. The basicity of the final slag in the previous furnace for patching is 2.8 - 3.0, the TFe content is 15%, and the magnesia content is 7% - 9%.

[0030] Using the 210 t converter furnace protection method under low iron consumption conditions provided in this embodiment can make the raw material charging ratio reasonable. Appropriately increasing the amount of iron blocks can supplement a certain amount of heat for the converter. The heat supplement method of ferrosilicon + temperature-raising agent is adopted to stably control the end point temperature at 1600 - 1610 °C. The TFe content of the final slag is about 15%, and the MgO content is 8% - 10%. By tempering the furnace slag for over-oxidized furnace heats, the main measure is to add a temperature-raising agent for deoxidation, which reacts with FeO in the furnace slag to reduce the FeO content in the slag, achieving the purpose of increasing the melting point of the furnace slag, improving the slag-splashing furnace protection effect, enhancing the erosion resistance and scouring resistance of the furnace slag, reducing the number of furnace patching times, and reducing the labor intensity of workers.

[0031] Example 3 This example is used for the smelting and converter maintenance of hot metal with rich heat where the silicon content > 0.40% and the temperature > 1400 °C under low iron consumption. The iron consumption is 782 kg / t, the hot metal addition is 180 t, and the scrap addition is 70 t.

[0032] A 210 t converter furnace protection method under low iron consumption conditions includes the following steps: Step 1: Feed the raw materials into the furnace. Charge the scrap steel bucket. The addition amount of iron blocks is 15t, the addition amount of steel bar briquettes is 15t, the addition amount of self-produced and purchased scrap steel is 23t, the addition amount of heavy scrap is 15t, and the addition amount of slag steel is 2t. The addition amount of iron blocks is controlled at the lower limit to reduce external heat. The slag retention amount is ≤1t, and the slag pouring angle is 165 - 170°. Adopt high scrap ratio smelting to reduce splashing caused by excessive heat in the early stage of blowing and increase the addition amount of heavy scrap briquettes. At the bottom of the scrap steel bucket, lay a part of iron blocks, heavy scrap, general materials, steel bar briquettes, self-produced and purchased scrap steel, slag steel, and the remaining iron blocks in sequence. Among them, the mass of the iron blocks laid at the bottom of the scrap steel bucket is 10t, and the remaining iron blocks are allocated at the top and proportioned with the slag steel.

[0033] Step 2: After the raw materials are fed into the furnace, carry out furnace protection smelting. For smelting such hot metal conditions, use limestone, raw dolomite, and lump ore to replace part of the lime and light burned magnesia balls to balance the excessive heat in the early stage of blowing and reduce the solvent cost at the same time. The alkalinity in the early stage of blowing is 2.0 - 2.5, the total addition amount of cold materials > 5t, and the addition amount of cold materials in the early stage of blowing is 60%. Use limestone and lump ore to balance the temperature; the total addition amount of cold materials is 3 - 5t, and the addition amount of cold materials in the early stage of blowing is 40% - 60%. Use raw dolomite and sinter ore to balance the temperature; the total addition amount of cold materials < 3t, and the addition amount of cold materials in the early stage of blowing is 20% - 40%. Use light burned dolomite and sinter ore to balance the temperature. Before the oxygen supply for smelting reaches 1000m 3 All the materials are put in before blowing. The initial oxygen blowing pressure is 0.85MPa, and the oxygen supply intensity is 3.6Nm 3 / (t·min). The initial lance position is 2600mm. After the feeding is completed, lower the lance to 2200mm, and the oxygen supply intensity is 3.4Nm 3 / (t·min). The oxygen content at the end point is controlled at 302 - 385ppm, the end point temperature is 1620 - 1630°C, the TFe content of the final slag is 12.35% - 15.21%. Due to the large addition amount of raw dolomite in the smelting process, the MgO content of the converter final slag reaches 9% - 12%, and the viscosity of the final slag can reach 0.10Pa·S. The end point temperature, end point oxygen content, TFe content of the final slag, consumption of slag splashing materials, nitrogen consumption, and iron consumption of each heat are shown in Table 3.

[0034] Table 3 Smelting furnace protection parameters of each heat in Example 3

[0035] Step 3: After the furnace protection smelting is completed, carry out slag splashing furnace protection. Combining with the end point control, select the converter automatic slag splashing model as the final slag thickening or bottom lowering mode. For the final slag thickening mode, adopt high - low lance position slag splashing. The nitrogen flow rate is 1000Nm 3 / min. The height and residence time of the lance position are, in sequence, 2600 mm for 5 s, 1000 mm for 25 s, 1600 mm for 55 s, 1300 mm for 20 s, 1000 mm for 40 s, 700 mm for 20 s, and then the slag splashing ends. The bottom lowering mode uses low lance position slag splashing to lower the furnace bottom, and the nitrogen flow rate is 1170 Nm 3 / min. The height and residence time of the lance position are, in sequence, 2400 mm for 5 s, 700 mm for 20 s, 900 mm for 70 s, 1100 mm for 20 s, 1300 mm for 20 s, 900 mm for 50 s, 600 mm for 40 s, and then the slag splashing ends. The final slag of the hot metal with rich heat has a high MgO content. Raw dolomite is used for slag splashing seasoning. For the furnace heats with a high end point temperature, 500 kg of slag conditioning materials can be added before slag splashing, and the cooling effect is good and the slag conditioning effect is remarkable.

[0036] Step 4: After the slag splashing furnace lining protection is completed, daily furnace repair is carried out. When smelting hot metal with rich heat under low iron consumption, the molten pool temperature is high in the early stage of blowing, there is more acidic slag, the furnace lining is eroded more seriously in the early stage of blowing, the end point temperature is high, and the tapping surface is seriously eroded by foaming furnace during tapping. Using furnace repair materials for furnace repair can achieve the best effect. The slag splashing effect of the final slag of the hot metal with rich heat is good, and the furnace repair frequency is relatively low. The basicity of the final slag of the previous furnace for furnace repair is 2.8 - 3.0, the TFe content is 15%, and the magnesia content is 8% - 10%.

[0037] Using the converter furnace lining protection method for 210 t under the low iron consumption conditions provided by this embodiment can make the heat of the hot metal relatively rich, reduce the addition amount of iron blocks to balance the rich temperature of the hot metal, stably control the end point temperature at 1620 - 1630 °C. During the smelting process, the addition amount of raw white is large, the TFe content of the final slag is about 14%, and the MgO content of the converter final slag reaches 9% - 12%, significantly reducing the consumption of slag splashing materials and nitrogen.

[0038] Although the present invention has been described in detail by way of preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention.

Claims

1. A 210t converter protection method under low iron loss conditions, characterized in that: The steps include: Step 1: Raw materials are put into the furnace, and the scrap steel bucket is loaded with materials. The scrap steel includes iron blocks, steel bar briquettes, self-produced scrap steel and purchased scrap steel, heavy scrap and slag steel. In terms of mass percentage, the amount of iron blocks added is 21%-43%, the amount of steel bar briquettes added is 7%-22%, the amount of self-produced scrap steel and purchased scrap steel is 28%-41%, the amount of heavy scrap added is 7%-22%, and the amount of slag steel added is 2%-4%; the bottom of the scrap steel bucket is paved with part of the iron blocks, heavy scrap, general materials, steel bar briquettes, self-produced scrap steel and purchased scrap steel, slag steel and remaining iron blocks in order; Step 2: After the raw materials are put into the furnace, the furnace is smelted and protected. The basicity in the early stage of blowing is controlled to be 2.0-2.5, the terminal temperature is 1600-1630℃, the TSC is controlled at 1560-1590℃, the corresponding carbon is 0.40%-0.20%, and the terminal oxygen content is controlled at 300-452ppm; Step 3: After the smelting and furnace protection is completed, slag splashing is carried out to protect the furnace. The automatic slag splashing model of the converter is adopted. When the final slag viscosity is less than 0.02Pa·S, the "final slag thin mode" is used; when the final slag viscosity is 0.02-0.10Pa·S, the normal mode is used; when the final slag viscosity is greater than 0.10Pa·S, the final slag thick mode is used; when the furnace bottom thickness is ≤500mm, the furnace bottom rising mode is used; when the furnace bottom thickness is ≥1000mm, the furnace bottom lowering mode is used.

2. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 1, the mass of the iron blocks laid on the bottom of the scrap steel bucket is 55%-70% of the amount of iron blocks added.

3. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step one, when the silicon content of the molten iron is less than 0.2wt% and / or the temperature of the molten iron is lower than 1350°C, 5-10t of pig iron blocks are used to replace an equal mass of self-produced scrap steel and purchased scrap steel, and after the scrap steel is added to the converter, the furnace is shaken to -45° toward the steel-outlet side to allow the scrap steel adhering to the slag pouring surface of the converter to fall off.

4. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 2, when the total amount of cold material added is greater than 5t, the amount of cold material added in the early stage of blowing is 60% of the total amount of cold material added, and the cold materials are limestone and lump ore; when the total amount of cold material added is 3-5t, the amount of cold material added in the early stage of blowing is 40%-60% of the total amount of cold material added, and the cold materials are raw dolomite and sintered ore; when the total amount of cold material added is less than 3t, the amount of cold material added in the early stage of blowing is 20%-40% of the total amount of cold material added, and the cold materials are light-burned dolomite and sintered ore.

5. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 2, ferrosilicon and a heating agent are used to increase the temperature of the molten iron.

6. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 2, the magnesium oxide content of the final slag is 8%-9%.

7. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 2, the oxygen supply intensity at the beginning of blowing and the end of feeding is 3.6-3.8Nm 3 / (t·min).

8. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 3, the final slag dilution mode adopts high-low-high-low gun position, and the nitrogen flow rate is 1080Nm 3 / min, the height and residence time of the gun position are in the following order: 2300mm 5s, 800mm 75s, 2000mm 20s, 1700mm 30s, 1400mm 30s, 1200mm 40s, 900mm 25s, 600mm 25s, slag splashing ends; in normal mode, high and low gun positions are used to penetrate the slag to maintain the furnace bottom and molten pool, and the nitrogen flow rate is 1000Nm 3 / min, the gun height and residence time are in the following order: 2400mm 20s, 1000mm 50s, 2000mm 30s, 1000mm 20s, 1700mm 20s, 1700mm 15s, 1400mm 15s, 1000mm 15s, 1500mm 15s, slag splashing ends; the final slag thickening mode adopts high-low gun position slag splashing, and the nitrogen flow rate is 1000Nm 3 / min, the height and residence time of the gun position are in the following order: 2600mm 5s, 1000mm 25s, 1600mm 55s, 1300mm 20s, 1000mm 40s, 700mm 20s, and slag splashing ends; the furnace bottom rising mode uses high gun position slag splashing to maintain the furnace bottom, and the nitrogen flow rate is 1080Nm 3 / min, the height and residence time of the gun position are in the following order: 2600mm 5s, 1300mm 25s, 2500mm 70s, 2200mm25s, 2000mm 25s, 1700mm 25s, 1500mm 15s, 1300mm 15s, and slag splashing ends; the furnace bottom lowering mode adopts low gun position slag splashing and furnace bottom lowering, and the nitrogen flow rate is 1170Nm 3 / min, the gun position height and residence time are in the following order: 2400mm 5s, 700mm 20s, 900mm 70s, 1100mm 20s, 1300mm 20s, 900mm 50s, 600mm 40s, and the slag splashing ends.

9. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: In step 3, a heating agent is used for deoxidation; when the end temperature is greater than 1620°C, the amount of slag splashing seasoning added is 1-2t; when the end temperature is 1610°C-1620°C, the amount of slag splashing seasoning added is 0.8-1.2t; when the end temperature is less than 1610°C, the amount of slag splashing seasoning added is less than 1t; The end point temperature is greater than 1620°C, the slag splashing materials are raw limestone and raw dolomite, and the solvent is one or more of raw limestone, raw dolomite, lump ore and light-burned magnesium balls; the end point temperature is 1610°C-1620°C, the slag splashing materials are light-burned dolomite or lime, and the solvent is raw limestone and light-burned magnesium balls; the end point temperature is less than 1610°C, the slag splashing materials are light-burned magnesium balls, and the solvent is raw limestone and light-burned magnesium balls.

10. A 210t converter protection method under low iron loss conditions as claimed in claim 1, characterized in that: It also includes daily furnace repair. During steps one to three or after step three, the furnace lining thickness is monitored in real time. When the thickness of the molten steel and scrap steel impact zone is ≤600mm, the molten steel and scrap steel impact zone of the converter lining is repaired by pig iron blocks and / or raw dolomite blocks; when the thickness on both sides of the molten pool is ≤500mm, the two sides of the molten pool are repaired by hand-throwing and / or spraying materials; when the thickness of the steel tapping surface and the furnace bottom is ≤500mm, the steel tapping surface and the furnace bottom are repaired by repair materials; in daily furnace repair, the final slag basicity of the previous furnace before the repair is 2.8-3.0, the TFe content is 14%-16%, and the magnesium oxide content is 8%-10%.

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