A method for baking an electric furnace without power supply

Abstract

The present invention provides a method for baking a furnace without electricity to an electric furnace, uses a high proportion of hot-charged molten iron and a small amount of scrap steel as raw materials for the furnace, utilizes the physical heat of molten iron and the chemical heat generated in the oxygen blowing smelting process as a heat source to bake the furnace, adopts the method of early molten iron baking furnace + late molten steel baking furnace, controls the parameters of each step, makes the furnace wall refractory material and the furnace bottom ramming material evenly heat up and sinter, avoids the radiation damage of the high-temperature electric arc to the newly built refractory material and the extremely high electrode consumption during the baking furnace stage. The baking furnace time of the method of the present invention is within 3 to 3.5 hours, and the furnace age can be stabilized at 595-620 furnaces. And the baking furnace method provided by the present invention can be baked after continuously completing the feeding, and there is no need to open the furnace cover multiple times to add materials during the smelting process, thereby avoiding the escape of molten pool heat and high-temperature flue gas, which is safer and more environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of electric furnace smelting, and particularly relates to a furnace baking method without powering the electric furnace. Background Art

[0002] After the electric furnace lining is repaired, the furnace needs to be baked to fully sinter the lining refractory materials and the ramming material at the bottom of the furnace, ensuring the service life of the furnace refractory materials. Existing electric furnace baking processes primarily use all-scrap steel baking methods. This involves using scrap steel as the raw material, adding scrap steel twice or more, and then using electrodes and oxygen lances to provide heat to melt the scrap steel for baking. Alternatively, a method involves first adding some scrap steel, melting it, and then adding hot iron. This process then uses both scrap steel and iron as the raw materials for power and oxygen supply.

[0003] For example, in the prior art, the patent No. CN102559994A published on July 11, 2012 discloses a method for heating molten iron in an electric furnace. The method comprises the following steps: pre-laying a layer of ramming material on the newly built furnace bottom; laying a layer of light material, such as wood material and iron sheet, on the ramming material; adding scrap steel to the furnace, which accounts for 20%-35% of the furnace capacity; energizing the electrodes to ignite the arc, and slowly increasing the power from 30-40MW to 60MW. -70MW, melt scrap steel; open the oxygen lance on the furnace wall and add molten iron into the furnace to 30%-60% of the furnace capacity; add more scrap steel into the furnace to 20%-35% of the furnace capacity, continue to power on and blow oxygen to melt all the scrap steel; add 0.03-0.05t of lime slag material per ton of steel, and carry out the normal steel smelting process; use thermocouples to measure the molten steel temperature. When the molten steel temperature reaches 1600-1650℃, stop the power and oxygen supply, and carry out the furnace drying operation for 15-30 minutes; after the furnace drying is completed, if the temperature and composition of the molten steel meet the required range, the steel can be tapped.

[0004] The above furnace baking methods in the prior art all require the use of electrodes to provide heat to melt the scrap steel for furnace baking. The electrode-powered melting of scrap steel belongs to the "point heat source" heating method, and the maximum arc temperature can reach 3000-4000 ° C. Before the molten pool is formed in the early stage of the furnace baking, the submerged arc operation conditions are not met, the electrode consumption is high, and the exposed ultra-high temperature arc frequently radiates on the furnace lining, which can easily cause great damage to the unsintered refractory material. The electrode-powered furnace baking cannot evenly melt the scrap steel, and the early furnace bottom ramming material cannot be evenly sintered.

[0005] In addition, existing furnace baking methods all require 40% or even higher proportions of scrap steel as raw materials. Since scrap steel has a low bulk density and occupies a large space, the second batch or more of materials must be added to the furnace after the first batch of scrap steel has been melted. Frequent opening of the furnace cover to add materials during smelting will cause a large amount of heat and smoke to escape, which is not conducive to environmental protection and poses a safety risk. Summary of the Invention

[0006] The object of the present invention is to provide a furnace baking method without powering the electric furnace, using a high proportion of hot-charged molten iron and a small amount of scrap steel as the raw materials for the furnace, and utilizing the physical heat of the molten iron and the chemical heat generated during the oxygen blowing smelting process as heat sources to bake the furnace, thereby avoiding the high-temperature radiation damage of the electric arc to the newly built refractory materials in the early stage of the furnace baking, and making the furnace wall refractory materials and the furnace bottom ramming material uniformly heated and sintered, thereby ensuring better sintering quality of the refractory materials. In addition, the furnace baking method provided by the present invention can be carried out after continuous feeding, and the furnace cover does not need to be opened during smelting, which is environmentally friendly and safe. The furnace baking time of this method is within 3 to 3.5 hours, and the furnace life can be stabilized at 595-620 furnaces.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for baking an electric furnace without power supply, the method comprising the following steps:

[0009] 1) Before baking the furnace, add 5-6 tons of light and thin scrap steel to the bottom of the furnace;

[0010] 2) Adjust the furnace wall oxygen gun to the "protection gear" and the oxygen supply intensity to 150±5Nm 3 / h;

[0011] 3) Pour hot molten iron into the furnace;

[0012] 4) After the scrap steel and molten iron are added, the furnace cover is closed and the furnace body is kept in a horizontal position. The furnace body is heated by the physical heat of the high-temperature molten iron in the furnace. During this period, the bottom blowing of the electric furnace must be kept closed and the oxygen lance on the furnace wall is kept in the "protection gear";

[0013] 5) Then adjust the two furnace wall oxygen guns to "low gear" and the oxygen supply intensity is 500-600Nm 3 / h to supply oxygen to the molten pool and open the furnace door oxygen gun 500-580Nm 3 / h to cut and melt the unmelted scrap steel in the furnace, and add lime to make slag after the slag shell on the surface of the molten iron in the furnace is melted;

[0014] 6) Wait until the total oxygen supply reaches 1800-2000 Nm 3 The molten pool temperature reaches 1520-1530℃, lime is added at 14-16kg / t steel, and the oxygen lance on the furnace wall is adjusted to "medium" with an oxygen supply intensity of 950-1050Nm 3 / h, after the lime is melted, the carbon gun is turned on to spray carbon powder to turn the slag into foamy slag, and the dephosphorization and temperature increase operations begin;

[0015] 7) Thereafter, every additional 450 to 550 Nm 3 The oxygen supply is 9-11 kg / t steel and lime is added. During smelting, carbon powder is sprayed according to the slag state to keep the slag in a good foaming state and to discharge the slag naturally.

[0016] 8) Wait until the oxygen supply reaches 3400-3600 Nm 3 Measure the temperature and take samples at the same time. If the temperature is lower than 1580℃, continue to supply oxygen. When the temperature reaches 1580℃, open the bottom blowing at 1 gear 25-30NL / min, and continue to blow at "medium gear" 950-1050Nm 3 / h oxygen supply intensity is used to supply oxygen to the molten pool to raise the molten pool temperature to 1620-1640℃, and then the furnace wall oxygen gun is adjusted to the "protection gear" to continue baking the furnace.

[0017] 9) Then gradually increase the furnace wall oxygen gun from the "protection" gear to the "high oxygen" gear 1350 ~ 1450Nm 3 / h to supply oxygen to the molten pool, and through the oxygen supply, the molten pool temperature is raised again. During the smelting process, lime is added at a rate of 8-10 kg / t steel to keep the slag completely melted and in a foamed state. The oxygen supply reaches 4200-4400 Nm 3 Temperature measurement and sampling are carried out at the same time. When the temperature reaches 1630-1650℃ and the P content and C content of the molten steel are qualified, 48-50t of steel can be added to complete the new furnace baking operation.

[0018] In step 1), the electric arc furnace that needs to be baked is equipped with two furnace wall oxygen lances and one furnace door oxygen lance.

[0019] In step 1), 5 to 6 tons of thin scrap steel is added to the bottom of the furnace using a basket, mainly to cushion the impact of molten iron and prevent the molten iron from flushing out pits on the bottom of the new furnace during the iron addition process.

[0020] In step 2), after placing the buffer material at the bottom of the furnace, adjust the furnace wall oxygen gun to the "protection gear" and the oxygen supply intensity to 150±5Nm 3 / h, to prevent the oxygen gun hole from being blocked due to splashing of molten iron during the iron addition process.

[0021] In step 3), the amount of molten iron entering the furnace must reach 55-58 tons, and the proportion of hot-charged molten iron used in the total steel material must be greater than 90%. In addition, the temperature of the molten iron entering the furnace must be ≥1250°C, the Si content must be ≥0.36%, and the P content must be ≤0.14%. Insufficient molten iron ratio, too low temperature, and too low silicon content will all lead to insufficient heat energy during the smelting process, requiring an increased oxygen supply, resulting in severe overoxidation of the molten steel. Highly oxidizing slag will aggravate the erosion of the new furnace lining, seriously affecting the furnace start-up effect. To improve the efficiency of the furnace, the hot-charged molten iron can be added once through the iron ladle.

[0022] In step 4), the furnace body is pre-baked with molten iron at about 1200°C in the furnace to uniformly sinter the furnace wall and the ramming material at the bottom of the furnace. The 40-50min molten iron baking time can effectively ensure that the refractory material of the furnace wall is firmly sintered and the sintered layer of the ramming material at the bottom of the furnace is gradually thickened.

[0023] It is strictly forbidden to supply oxygen to the molten pool during the use of molten iron to heat the furnace, so as to prevent the furnace lining from being washed away by oxygen and the molten pool during pre-sintering, resulting in a large amount of local refractory material falling off and erosion, causing furnace opening failure; keeping the bottom blowing of the electric furnace closed in the early stage can prevent the bottom ramming material from being washed away by the bottom blowing gas before sintering is completed.

[0024] In step 5), the amount of lime added is 10-12 kg / t steel.

[0025] In step 5), after the molten iron is pre-baked in the furnace, the oxygen supply intensity is increased and slag is added to create conditions for subsequent molten pool heating and decarburization.

[0026] The total oxygen supply reaches 1800~2000Nm 3 When the molten pool temperature reaches about 1520-1530℃, lime is added at a rate of 14-16kg / t steel, and the oxygen lance on the furnace wall is adjusted to the "medium" position with an oxygen supply intensity of 950-1050Nm 3 / h, after the lime is melted, the carbon gun is turned on to spray carbon powder into the furnace at a powder spraying rate of 12 to 15 kg / min, turning the slag into foam slag, and starting the dephosphorization and temperature increase operations.

[0027] In step 6), the powder is sprayed into the furnace at a rate of 12 to 15 kg / min.

[0028] In steps 6) and 7), the molten pool has reached a relatively high temperature. The oxygen supply intensity is further increased to strengthen the decarburization and dephosphorization of the molten pool. 3 Supplying oxygen in the amount of 9-11 kg / t steel and adding lime, and taking away the heat by natural slag discharge, can keep the molten pool temperature at 1550-1560℃, providing good reaction conditions for decarburization and dephosphorization, ensuring that the molten steel composition meets the standards before the furnace is baked, and avoiding the difficulty of dephosphorization operation caused by excessively high temperature in the later stage.

[0029] In step 8), the oven is continued for 20 to 25 minutes.

[0030] In step 8), when the temperature reaches 1580 ° C or above, the bottom blowing is turned on at 25-30 NL / min. At this time, the furnace bottom has completed sintering, and the bottom blowing gas will not damage the furnace bottom ramming material. After turning on the bottom blowing gas, oxygen is continued to be supplied to evenly heat the molten pool composition and temperature. The temperature is raised to 1620-1640 ° C and the furnace is continued to be baked for 20-25 minutes to strengthen the sintering of the furnace bottom ramming material, thereby further improving the service life of the furnace body refractory material.

[0031] In step 9), after the molten steel is dried, the "high oxygen" gear of 1350-1450 Nm can be used normally. 3 / h to supply oxygen to the molten pool, which can quickly increase the molten pool temperature and meet the conditions for tapping.

[0032] There are the following difficulties in using molten iron to dry the furnace without power:

[0033] 1. The main raw material of the furnace is changed from scrap steel to hot-charged molten iron. Adding a large amount of molten iron can easily cause serious erosion of the newly laid ramming material at the bottom of the furnace, affecting the sintering effect of the ramming material at the bottom of the furnace;

[0034] 2. Molten iron serves as both the raw material and the main heat source for the furnace. A reasonable ratio of materials to the furnace materials must be controlled to achieve a balance between supply and demand for the furnace materials and energy. Adding too little molten iron will result in insufficient heat, requiring the use of molten steel to increase the temperature of the molten pool. This can cause severe overoxidation of the molten pool, generating a large amount of highly oxidized slag that can aggravate the erosion of the newly built furnace lining, affecting the furnace start-up effect and even leading to furnace start-up failure. Adding too much molten iron will result in excess heat in the molten pool, requiring continued slag making and slag removal after the furnace is baked to remove the excess heat, resulting in extended baking time, waste of slag-making agents, and reduced molten steel yield.

[0035] 3. When using molten iron to bake the furnace, a large amount of oxygen needs to be supplied to the molten pool to complete decarburization and impurity removal, and the molten pool temperature is increased through carbon-oxygen reaction. Therefore, supplying oxygen to the molten pool is the most important task in the baking process. In the smelting and baking process, improper control of oxygen supply or oxygen supply timing will cause the furnace body refractory to be violently eroded by the oxygen jet before it is effectively sintered, resulting in damage to the refractory. In addition, under the material ratio of high molten iron ratio, the molten pool temperature will rise too quickly in the later stage and it will be difficult to control. A large increase in the molten pool temperature cannot guarantee the sintering quality of the refractory.

[0036] 4. After the molten pool temperature rises in the middle and late stages of the furnace drying, the main material in the furnace is molten iron, and the carbon-oxygen reaction is intense. In addition to the molten pool temperature rising too quickly, the slag in the molten pool is also very likely to "dry out", resulting in the inability of the flux in the molten pool to melt effectively, causing molten steel splashing, severe wall sticking, and molten steel rephosphorization, affecting the smooth progress of the furnace drying process;

[0037] To address the difficulties associated with using molten iron to bake a furnace without power, the present invention addresses the issue of iron scouring by specifying the baking charge ratio and the charging method. Furthermore, within the charge ratio range, the pre-baking time of the molten iron is controlled, and a specific oxygen supply and slag-making method is employed to achieve a balance between supply and demand of the molten iron's thermal energy during baking and smelting.

[0038] In the oxygen supply and furnace drying stage, in order to prevent the slag in the molten pool from "drying out", low-level oxygen supply is first used. On the one hand, low-intensity oxygen supply can increase the iron oxide content in the slag layer, providing conditions for the effective melting of the slag in the subsequent smelting process. On the other hand, weak oxygen supply to the molten pool in the early stage reduces the scouring of the refractory material by the jet, which is beneficial to ensuring the sintering quality of the refractory material. When the molten pool is fully formed, the ferrous oxide content in the molten pool slag continues to increase, providing conditions for continued slagging and rapid slagging at the subsequent medium-level oxygen supply intensity. At this time, turning on the medium-level oxygen intensity to supply oxygen to the molten pool and adding materials to slag can ensure rapid melting of the slag and prevent the "slag" from drying out. Gradually increase the oxygen supply intensity to increase the molten pool temperature from a lower temperature to a higher temperature, and gradually carry out furnace sintering. When the molten pool temperature rises to about 1550℃, in order to prevent the subsequent molten pool from reacting violently and the temperature from rising rapidly, a small amount of lime is added in multiple batches to make slag and discharge the slag, so that the slag takes away part of the heat of the molten pool and the temperature of the molten pool is slowly increased. At the same time, at this molten pool temperature, there are excellent dephosphorization conditions. Multiple batches of slag making and discharging can effectively remove impurity elements in the molten steel, providing a guarantee for the qualified composition of the molten steel.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] The method of the present invention enables the furnace to be opened without power. By using an initial hot metal heating method followed by a later hot steel heating method, the furnace wall refractory and the ramming material at the furnace bottom are uniformly heated and sintered, avoiding radiation damage to the newly built refractory material and extremely high electrode consumption caused by the high-temperature arc during the heating phase. Furthermore, the furnace heating method provided by the present invention can be performed after continuous feeding, eliminating the need to open the furnace cover multiple times to add material during smelting, thus preventing the escape of heat from the molten pool and high-temperature flue gases, making it safer and more environmentally friendly. DETAILED DESCRIPTION

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions.

[0043] Example 1

[0044] A method for baking an electric furnace without power supply, comprising the following steps:

[0045] The furnace used was a 50-ton electric arc furnace equipped with two wall oxygen lances and one door oxygen lance. The main components of the molten iron were C: 4.2%, Si: 0.42%, Mn: 0.35%, S: 0.025%, P: 0.125%, and the temperature was 1250°C.

[0046] The specific operation steps of electric furnace baking are as follows:

[0047] 1) After unscrewing the furnace cover, add 5.2t of light and thin scrap steel into the basket and spread the scrap steel flat on the bottom of the furnace;

[0048] 2) Then turn the furnace wall oxygen intensity to the "protection" position, with a flow rate of 150Nm 3 / h.

[0049] 3) Use the crane to pour in 55t of hot molten iron, then rotate the furnace cover and level the furnace body.

[0050] 4) After the scrap steel and molten iron are added, the furnace cover is closed and the furnace body is dried for 40 minutes using the physical heat of the molten iron in the furnace. During this period, the bottom blowing of the electric furnace must be kept closed and the furnace wall oxygen gun is maintained in the "protection" position.

[0051] 5) After 40 minutes of drying, adjust the two furnace wall oxygen guns from the "protection" gear to the "low gear" and the oxygen supply intensity to 570Nm 3 / h, supply oxygen to the molten pool and open the furnace door oxygen gun 550Nm 3 / h Oxygen is blown into the scrap steel at the furnace door to assist melting. After the slag shell on the surface of the molten iron is melted, 500kg of lime is added to make slag to prevent splashing of the molten pool liquid surface.

[0052] 6) The total oxygen supply reaches 1820Nm 3 Add 700kg of lime and adjust the oxygen lance on the furnace wall from "low gear" to 570Nm 3 / h adjusted to "mid-range" 1020Nm 3 / h, use a carbon powder gun to spray carbon powder into the furnace at a spraying rate of 12kg / min for 8 minutes to make the slag into foam slag.

[0053] 7) When the oxygen supply reaches 2320Nm 3 480kg of lime was added at the same time, and during the smelting period, carbon powder was sprayed into the furnace at a rate of 12kg / min for 4 minutes using a carbon powder gun. 3 Continue to add 490kg of lime and spray powder to make the slag foamy.

[0054] 8) Oxygen supply reaches 3450Nm 3 The temperature of the molten steel was measured and it was 1586℃. The bottom blowing was turned on at level 1 and 26Nm. 3 / h to uniformly supply the molten steel temperature and composition. Continue to supply oxygen to the molten pool at the "medium" oxygen supply intensity, continue to supply oxygen to raise the temperature to 1624℃, adjust the oxygen lance to the protection gear, and use the molten steel temperature in the furnace to dry the furnace for 25 minutes.

[0055] 9) Gradually increase the furnace wall oxygen gun from the "protection" gear to the "high oxygen" gear 1400Nm 3 / h to supply oxygen to the molten pool, and the oxygen supply reaches 3760Nm 3 Add 450kg of lime to make the slag in a good foaming state. When the oxygen supply reaches 4300Nm 3 Temperature measurement and sampling were carried out at the same time. The temperature of the molten steel reached 1646℃, the P content of the molten steel was 0.016%, and the C content was 0.06%. Then the furnace wall oxygen gun was adjusted to the "protection" position, the furnace door gun was closed, and the steel was discharged. It took a total of 195 minutes from feeding to completing the new furnace start-up, and the furnace life reached 612 furnaces.

[0056] Example 2

[0057] A method for baking an electric furnace without power supply, comprising the following steps:

[0058] The furnace used was a 50-ton electric arc furnace equipped with two wall oxygen lances and one door oxygen lance. The main components of the molten iron were C: 4.2%, Si: 0.458%, Mn: 0.354%, S: 0.025%, P: 0.127%, and the temperature was 1284°C.

[0059] The specific operation steps of electric furnace baking are as follows:

[0060] 1) After unscrewing the furnace cover, add 5.4t of light and thin scrap steel into the basket and spread the scrap steel flat on the bottom of the furnace;

[0061] 2) Then turn the furnace wall oxygen intensity to the "protection" position, with a flow rate of 150Nm 3 / h;

[0062] 3) Use the crane to pour in 56.6t of hot iron, then rotate the furnace cover and shake the furnace body level;

[0063] 4) Use the physical heat of the molten iron in the furnace to bake the furnace body for 45 minutes. During this period, the bottom blowing of the electric furnace must be kept closed and the oxygen gun on the furnace wall must be maintained in the "protection" position.

[0064] 5) After 45 minutes of drying, adjust the two furnace wall oxygen guns from the "protection" gear to the "low gear" and the oxygen supply intensity to 560Nm 3 / h, supply oxygen to the molten pool and open the furnace door oxygen gun 580Nm 3 / h Oxygen is blown into the scrap steel at the furnace door to assist melting. After the slag shell on the surface of the molten iron is melted, 550kg of lime is added to make slag to prevent splashing of the molten pool liquid surface.

[0065] 6) The total oxygen supply reaches 1920Nm 3 Add 760kg of lime and adjust the oxygen lance on the furnace wall from "low gear" to 560Nm 3 / h adjusted to "mid-range" 1050Nm 3 / h, use a carbon powder gun to spray carbon powder into the furnace at a spraying rate of 12kg / min for 8 minutes to make the slag into foam slag.

[0066] 7) When the oxygen supply reaches 2450Nm 3 500kg of lime was added at the same time, and during the smelting period, carbon powder was sprayed into the furnace at a rate of 12kg / min using a carbon powder gun for 5 minutes. 3 Continue to add 490kg of lime and spray powder to make the slag foamy;

[0067] 8) Oxygen supply reaches 3500Nm 3 The temperature of the molten steel was measured and it was 1583℃. The bottom blowing was turned on at level 1 and 26Nm. 3 / h to uniformly supply the molten steel temperature and composition. Continue to supply oxygen to the molten pool at the "medium" oxygen supply intensity, raise the temperature to 1624℃, adjust the oxygen lance to the protection gear, and use the molten steel temperature in the furnace to dry the furnace for 24 minutes.

[0068] 9) Gradually increase the furnace wall oxygen gun from the "protection" gear to the "high oxygen" gear 1400Nm 3 / h to supply oxygen to the molten pool, and the oxygen supply reaches 3800Nm 3 Add 450kg of lime to make the slag in a good foaming state. When the oxygen supply reaches 4300Nm 3 Temperature measurement and sampling were carried out at the same time. The temperature of the molten steel reached 1646℃, the P content of the molten steel was 0.016%, and the C content was 0.06%. Then the furnace wall oxygen gun was adjusted to the "protection" position, the furnace door gun was closed, and the steel was discharged. It took a total of 206 minutes from feeding to completing the new furnace start-up. The entire furnace life reached 603 furnaces.

[0069] Example 3

[0070] A method for baking an electric furnace without power supply, comprising the following steps:

[0071] A 50-ton electric arc furnace was used, equipped with two wall oxygen lances and one door oxygen lance. The main components of the molten iron were C: 4.5%, Si: 0.442%, Mn: 0.365%, S: 0.025%, P: 0.128%, and the molten iron temperature was 1302°C.

[0072] The specific steps for opening the electric furnace are as follows:

[0073] 1) After unscrewing the furnace cover, add 5.9t of light and thin scrap steel into the basket and spread the scrap steel flat on the bottom of the furnace;

[0074] 2) Then turn the furnace wall oxygen intensity to the "protection" position, with a flow rate of 150Nm 3 / h;

[0075] 3) Use the crane to pour in 57.8t of hot iron, rotate the furnace cover, and level the furnace body;

[0076] 4) Use the heat of molten iron to bake the furnace body for 50 minutes. During this period, the bottom blowing of the electric furnace must be kept closed and the furnace wall oxygen gun must be kept in the "protection" position;

[0077] 5) After 50 minutes of drying, adjust the furnace wall oxygen gun from the "protection" gear to the "low gear" and the oxygen supply intensity to 560Nm 3 / h, supply oxygen to the molten pool and open the furnace door oxygen gun 580Nm 3 / h to blow oxygen to assist melting, and after the slag shell on the surface of the molten pool is melted, add 600kg of lime to make slag;

[0078] 6) The total oxygen supply reaches 1980Nm 3 Add 800kg of lime and adjust the oxygen gun on the furnace wall from "low gear" to "medium gear" 1050Nm 3 / h, use a carbon powder gun to spray carbon powder into the furnace at a spraying rate of 12kg / min for 9 minutes to make the slag into foam slag.

[0079] 7) When the oxygen supply reaches 2510Nm 3 510kg of lime was added at the same time. During the smelting period, carbon powder was sprayed into the furnace at a rate of 12kg / min using a carbon powder gun for 6 minutes. When the oxygen supply reached 3020Nm 3 Continue to add 500kg of lime and spray powder to make the slag foamy.

[0080] 8) Oxygen supply reaches 3580Nm 3 The temperature of the molten steel was measured and it was 1586℃. The bottom blowing of the electric furnace was turned on at level 1 and 30Nm. 3 / h, uniform the temperature and composition of the molten pool, and continue to supply oxygen to the molten pool at the "medium" oxygen supply intensity, continue to supply oxygen to raise the temperature to 1626℃, adjust the oxygen lance to the protection gear, and use the molten steel temperature in the furnace to dry the furnace for 25 minutes.

[0081] 9) Then gradually increase the furnace wall oxygen gun from the "protection" gear to the "high oxygen" gear 1400Nm 3 / h to supply oxygen to the molten pool, and add 460kg of lime during the oxygen supply process. When the oxygen supply reaches 4380Nm 3Temperature measurement and sampling were carried out at the same time. The temperature of the molten steel reached 1642℃, the P content of the molten steel was 0.021%, and the C content was 0.09%. Then the furnace wall oxygen gun was adjusted to the "protection" position, the furnace door gun was closed, and the steel was discharged. It took a total of 192 minutes from feeding to completing the new furnace start-up, and furnace body 596 was offline.

[0082] Comparative Example 1

[0083] A method for baking an electric furnace without power supply, comprising the following steps:

[0084] The electric arc furnace has a nominal capacity of 50 tons and is equipped with two wall oxygen lances and one door oxygen lance. The raw materials for the furnace are 9.4 tons of light and thin scrap steel and 51.6 tons of hot-charged molten iron. The molten iron ratio is only 84.5% The main components of the molten iron are C: 4.5%, Si: 0.46%, Mn: 0.33%, S: 0.025%, P: 0.127%, and the molten iron temperature is 1267℃.

[0085] The furnace baking method of this comparative example was carried out according to the steps described in Example 1. There were no abnormalities in the early stage of the furnace baking. However, it was difficult to heat the molten pool in the later stage of the furnace baking. The molten pool temperature was maintained at around 1540°C after about 168 minutes of furnace baking. The molten pool temperature increased slowly with continued oxygen supply, and the molten pool began to show a tendency to overoxidize. A large amount of deoxidizing material was required to be added to the molten pool to deoxidize the slag before continued strong oxygen supply and heating. After the temperature was raised to 1624°C, sampling revealed that the molten steel had a P content of 0.012% and a C content of 0.02%. The molten steel was severely overoxidized. The overoxidized molten steel was not suitable for further heating after the furnace baking, so the steel had to be released in advance, ending the furnace baking. Due to the insufficient proportion of molten iron, the high-temperature molten steel was not strengthened in the later stage of the furnace baking, and the furnace body refractory materials could not be further sintered, resulting in rapid erosion during the use of the refractory materials. The life of the furnace body refractory materials was only 347 furnaces.

[0086] Comparative Example 2

[0087] A method for baking an electric furnace without power supply, comprising the following steps:

[0088] The electric arc furnace has a nominal capacity of 50 tons and is equipped with two furnace wall oxygen lances and one furnace door oxygen lance. The raw materials for the furnace are 5.3 tons of light and thin scrap steel and 56.6 tons of hot-charged molten iron. The iron-to-water ratio is 91.4%. The main components of the molten iron are C: 4.5%, Si: 0.44%, Mn: 0.35%, S: 0.027%, P: 0.136%, and the molten iron temperature is 1286℃.

[0089] The comparative example of the furnace baking method is to bake the furnace for 42 minutes after the materials are added according to the steps described in Example 1 and then use the heat of molten iron to bake the furnace for 42 minutes in order to achieve rapid furnace baking. Adjust the two furnace wall oxygen lances from "protection" to "medium" 1000Nm 3 / h oxygen supply intensity oxygen After the molten pool is formed, Adjust the furnace wall oxygen intensity from "medium" to "high oxygen" 1400Nm 3 / hThe oxygen supply intensity was set to supply oxygen to the molten pool to heat it up, and the remaining steps were completed according to the steps described in Example 1. After the furnace was baked, it was found that large areas of pits appeared in the refractory materials around the oxygen lance and in the impact area of ​​the strong oxygen jet, which seriously affected the baking effect. After the middle of the furnace service, it was necessary to frequently spray the furnace charge and fill the furnace, resulting in a lot of time waste, and the entire furnace life was only 389 furnaces.

[0090] Comparative Example 3

[0091] A method for baking an electric furnace without power supply, comprising the following steps:

[0092] The electric arc furnace, with a nominal capacity of 50 tons, was equipped with two wall oxygen lances, two side oxygen lances, and one door oxygen lance. The main components of the molten iron were C: 4.5%, Si: 0.472%, Mn: 0.309%, S: 0.024%, P: 0.137%, and the molten iron temperature was 1278°C. The scrap charge was 4.9 tons, and the molten iron charge was 55.8 tons.

[0093] The furnace baking method of this comparative example is operated according to the operating method of Example 2. After the molten iron pre-baking furnace is completed, the furnace wall oxygen lance is opened to supply oxygen to the furnace. In order to accelerate the dephosphorization rate and uniform the molten pool, the operator After the molten pool is formed, the temperature is only When the temperature is about 1540℃, open the bottom blowing of the electric furnace at level 1, 30Nm 3 / h Subsequently, the furnace was baked according to the operating method of Example 2. After the furnace was baked and the steel was put in, it was found that the sintering quality of the furnace bottom was inconsistent. Obvious pits appeared in the 1# and 2# bottom blowing areas, affecting the uniformity of the sintering at the furnace bottom. When the furnace body was used for about 300 furnaces, the pressure in the 2# bottom blowing gas pipeline gradually decreased and an alarm signal appeared. In order to ensure safe production, the 2# bottom blowing had to be turned off. After the furnace campaign was completed, when the furnace body was dug and repaired, it was found that steel had been leaking from the refractory material near the bottom blowing, posing a huge safety hazard to production.

[0094] Comparative Example 4

[0095] A method for baking an electric furnace without power supply, comprising the following steps:

[0096] The electric arc furnace, with a nominal capacity of 50 tons, is equipped with two wall oxygen lances, two side oxygen lances, and one door oxygen lance. The main components of the molten iron are C: 4.5%, Si: 0.48%, Mn: 0.32%, S: 0.024%, P: 0.135%, and the molten iron temperature is 1270°C. The scrap loading is 5.3 tons, and the molten iron loading is 56.2 tons.

[0097] The furnace baking method of this comparative example is operated according to the operating method of Example 2. After completing the molten iron pre-baking furnace, Open the oxygen gun "medium" oxygen supply intensity is 1000Nm 3 / h to supply oxygen and slag to the molten pool. When the molten pool temperature reaches 1556℃, Subsequent failure to increase by 500Nm 3 About oxygen supply, add 450 ~ 550kg of lime, increase the lime dosage to 1000kg is put into the molten pool,The large amount of lime newly added to the furnace cannot be melted quickly under this oxygen supply intensity, resulting in lime "clumps" that cannot cover the steel liquid surface, and the slag in the molten pool does not have the conditions for foaming, and the slag cannot flow out naturally. In order to melt the "clumps" of lime, oxygen is continued to be supplied to the molten pool, and a hand oxygen gun is used to blow the clumps of lime. After the slag is completely melted, the temperature of the molten pool is measured, and the molten pool temperature has reached 1614℃. The molten pool temperature is too high, which makes the subsequent dephosphorization operation difficult. In order to make the molten steel composition meet the standards and prevent the molten pool slag from "drying out" again, the subsequent 300k Lime was added to the molten pool in batches. After the lime was completely melted, powder spraying and slag removal were performed. Continuous slag replacement lowered the molten pool temperature, allowing the dephosphorization reaction to proceed continuously. After the third batch of lime melted, the molten pool temperature was measured and sampled, revealing a temperature of 1589°C, a phosphorus content of 0.034%, and a carbon content of 0.49%. Two more batches of lime were added, and the molten steel temperature was sampled, revealing a temperature of 1608°C, a phosphorus content of 0.018%, and a carbon content of 0.08%. The molten steel composition was acceptable, and the temperature was raised to 1625°C before steel was discharged, completing the furnace bakeout. Due to improper lime addition during the mid-smelting process, the molten pool missed the optimal dephosphorization window, and the molten pool temperature was not effectively controlled. This necessitated multiple additional batches of slag replacement and dephosphorization at high temperatures, wasting slag making and furnace bakeout time. Furthermore, the molten pool carbon content was insufficient, preventing subsequent enhanced sintering of the furnace. The bakeout took a total of 232 minutes, and the refractory life of the furnace was only 424 furnaces.

[0098] The underlined data do not meet the requirements of the present invention.

[0099] The above embodiments are described to facilitate understanding and use of the invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for baking an electric furnace without power supply, characterized in that: The oven baking method comprises the following steps: 1) Before baking the furnace, add 5-6 tons of light and thin scrap steel to the bottom of the furnace; 2) Adjust the furnace wall oxygen gun to "protection gear" and the oxygen supply intensity to 150±5Nm 3 / h; 3) Pour hot molten iron into the furnace; 4) After the scrap steel and molten iron are added, close the furnace cover and keep the furnace body in a horizontal position. Use the physical heat of the high-temperature molten iron in the furnace to dry the furnace body. During this period, the bottom blowing of the electric furnace must be kept closed and the furnace wall oxygen lance must be kept in the "protection gear"; 5) Then adjust the two furnace wall oxygen guns to "low gear" and the oxygen supply intensity is 500-600Nm 3 / h to supply oxygen to the molten pool and open the furnace door oxygen gun 500-580Nm 3 / h to cut and melt the unmelted scrap steel in the furnace, and add lime to make slag after the slag shell on the surface of the molten iron in the furnace is melted; 6) Wait until the total oxygen supply reaches 1800-2000 Nm 3 The molten pool temperature reaches 1520-1530℃, lime is added at 14-16kg / t steel, and the oxygen lance on the furnace wall is adjusted to "medium" with an oxygen supply intensity of 950-1050Nm 3 / h, after the lime is melted, the carbon gun is turned on to spray carbon powder to turn the slag into foamy slag, and the dephosphorization and temperature increase operations are started; 7) Thereafter, every additional 450 to 550 Nm 3 The oxygen supply is 9-11 kg / t steel and lime is added. During smelting, carbon powder is sprayed according to the slag state to keep the slag in a good foaming state and to discharge the slag naturally. 8) Wait until the oxygen supply reaches 3400-3600 Nm 3 Measure the temperature and take samples at the same time. If the temperature is lower than 1580℃, continue to supply oxygen. When the temperature reaches 1580℃, open the bottom blowing at 1 gear 25-30NL / min, and continue to blow at "medium gear" 950-1050Nm 3 / h oxygen supply intensity to the molten pool to raise the molten pool temperature to 1620-1640℃, then adjust the furnace wall oxygen gun to "protection gear" to continue to dry the furnace; 9) Then gradually increase the furnace wall oxygen gun from the "protection" gear to the "high oxygen" gear 1350 ~ 1450Nm 3 / h to supply oxygen to the molten pool, and through the oxygen supply, the molten pool temperature is raised again. During the smelting process, lime is added at a rate of 8-10 kg / t steel to keep the slag completely melted and in a foamed state. The oxygen supply reaches 4200-4400 Nm 3 Temperature measurement and sampling are carried out at the same time. When the temperature reaches 1630-1650℃ and the P content and C content of the molten steel are qualified, 48-50t of steel can be added to complete the new furnace baking operation.

2. The oven baking method according to claim 1, characterized in that: In step 1), the electric arc furnace that needs to be baked is equipped with two furnace wall oxygen lances and one furnace door oxygen lance.

3. The oven baking method according to claim 1, characterized in that: In step 1), 5 to 6 tons of thin scrap steel is added to the bottom of the furnace using a basket.

4. The oven baking method according to claim 1 or 3, characterized in that: In step 3), the proportion of hot-charged molten iron to the total steel material is greater than 90%.

5. The oven baking method according to claim 1 or 4, characterized in that: In step 3), the temperature of the hot-charged molten iron is ≥1250° C., the Si content is ≥0.36%, and the P content is ≤0.14%.

6. The oven baking method according to claim 1, characterized in that: In step 4), the oven is baked for 40 to 50 minutes.

7. The oven baking method according to claim 1, characterized in that: In step 5), the amount of lime added is 10-12 kg / t steel.

8. The oven baking method according to claim 1, characterized in that: In step 6), the powder is sprayed into the furnace at a rate of 12 to 15 kg / min.

9. The oven baking method according to claim 1, characterized in that: In step 8), the oven is continued for 20 to 25 minutes.