Dynamic alkalinity adjusting method considering furnace hearth change in front-middle-rear service cycles of electric furnace

Abstract

The invention relates to a dynamic alkalinity adjusting method considering furnace hearth changes in front-middle-rear service cycles of an electric furnace, and belongs to the technical field of electric furnace steelmaking processes. According to the method, the distribution mode and the adding amount of lime are adjusted in a segmented mode, then the alkalinity of the electric furnace final slag in the front-middle-rear service cycle of the electric furnace is regulated and controlled, side oxygen lance soft blowing and submerged arc electrode temperature rising are combined, the slag forming capacity of the electric furnace in different service stages is improved, the stability of the electric furnace terminal molten steel dephosphorization rate is improved and is 89.0% or above, and the dephosphorization effect is good. The steel-slag phosphorus distribution ratio at the end point of the electric furnace is high and ranges from 2.1 to 2.6, meanwhile, the electric furnace slag has good fluidity in the whole service cycle, and the requirement for smooth slag flowing of the electric furnace can be met.

Description

Technical Field

[0001] The invention relates to the technical field of electric furnace steelmaking technology, and in particular to a basicity dynamic adjustment method considering furnace changes during the pre-, mid- and post-service periods of an electric furnace. Background Art

[0002] Electric arc furnace steelmaking mainly uses electric energy to generate a high-temperature arc between the electrode and the solid ferrous raw material, and mainly melts the solid charge in the molten pool through thermal radiation. The arc temperature is as high as 4000-6000℃. The temperature of the molten steel exceeds 2130℃. The main steel material for electric arc furnace steelmaking is scrap steel. Compared with the "long process" process, the coking, sintering and blast furnace ironmaking links are eliminated, and the energy consumption per ton of steel is only half of the long process steelmaking process, about 350kgce / t; the CO2 emission per ton of steel is only between 0.5 and 0.7t, the exhaust gas emission is reduced by 95%, the solid waste emission is reduced by 65%, and the wastewater emission is reduced by 33%, forming a "scrap steel-electric furnace short process" steelmaking method that corresponds to the "blast furnace-converter long process" with low energy consumption, multiple varieties, resource recycling, and environmental friendliness.

[0003] Dephosphorization is the eternal theme of steelmaking. The rapid development of the manufacturing industry and the fierce competition in the market have forced major steel production enterprises to continuously improve product quality and production efficiency. Various products have higher and higher requirements for harmful elements of phosphorus in steel, especially for phosphorus. Most steel grades require a phosphorus content of less than 0.020%, and some require a phosphorus content of less than 0.010%. Lime is the main dephosphorization agent used in the steelmaking dephosphorization production process. It forms dicalcium silicate 2CaO·SiO2 (C2S) at steelmaking temperature and combines with tricalcium phosphate 3CaO·P2O5 (C3P) in the slag to form a stable phosphorus-containing solid solution 2CaO·SiO2-3CaO·P2O5 (C2S-C3P), so that the phosphorus in the molten iron enters the slag and exists stably, thereby achieving the purpose of dephosphorization of the molten iron. Since the electric furnace needs to heat up quickly in the early stage to promote the melting of scrap steel, the temperature in the furnace has exceeded 1500℃ when the scrap steel in the electric furnace is in a molten clear state. Judging from the thermodynamic conditions of hot metal dephosphorization, the increase in temperature is not conducive to hot metal dephosphorization. How to balance the melting of scrap steel in the early stage of the electric furnace and the rapid dephosphorization of molten steel has been a problem that has troubled steel companies for a long time. As the service time of the electric furnace increases, the volume of the furnace chamber will change significantly with the service cycle of the electric furnace, which will cause the height of the molten steel in the electric furnace to change, directly affecting the oxygen blowing, slag making and slag-steel interface dephosphorization reaction of the electric furnace. How to regulate the composition of the electric furnace slag and improve the slag-forming ability of the electric furnace slag, ensure smooth slag flow during the electric furnace smelting process, and stabilize the dephosphorization rate of the molten steel at the end of the electric furnace is the focus of current electric furnace steelmaking dephosphorization. Summary of the invention

[0004] The object of the present invention is to overcome the deficiencies of the prior art and to provide a method for dynamically adjusting the basicity of an electric furnace taking into account changes in the furnace during the pre-, mid- and post-service cycles.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a method for dynamically adjusting basicity of an electric furnace in consideration of changes in the furnace during the pre-, mid- and post-service periods, comprising the following steps:

[0007] (1) After the previous furnace is tapped, 10% to 30% of the molten steel remains in the furnace, and all the final slag is left for dephosphorization in the early stage of the next furnace;

[0008] (2) Place 30 to 45 tons of scrap steel at the bottom of the electric furnace, determine the service stage of the electric furnace according to the age of the electric furnace, and divide the service stage of the electric furnace into early, middle and late stages; and add lime in the following manner:

[0009] Add 6-12kg / ton of steel lime to the electric furnace that is judged to be in the early stage of service, add 12-20kg / ton of steel lime to the electric furnace that is judged to be in the middle stage of service, and add 20-30kg / ton of steel lime to the electric furnace that is judged to be in the late stage of service;

[0010] (3) During the melting process of scrap steel in an electric furnace, smelting is carried out by soft blowing of the side oxygen lance and heating of the submerged arc electrode.

[0011] The present invention retains all the liquid electric furnace final slag with a relatively high temperature (>1600°C) of the previous furnace in the furnace as a dephosphorizing agent for the next batch, and fully utilizes the heat of the electric furnace final slag itself to preheat the lime and other auxiliary materials added subsequently. By adjusting the distribution method and addition amount of lime in sections during the pre-middle-end service cycle of the electric furnace, and then regulating the basicity of the electric furnace final slag, the dephosphorization rate of the entire stage is improved and stabilized. This method can promote the rapid slag formation of lime in the early stage, thereby adapting to the change in slag composition caused by the change in the volume of the electric furnace chamber caused by the erosion of the furnace lining. At the same time, electric furnace slag with good fluidity is formed in the three stages of the pre-middle-end service of the electric furnace, and the stability of the dephosphorization rate of the molten steel at the end of the electric furnace is guaranteed, and it is ensured that there is no obvious slag drying phenomenon in the electric furnace during the smelting cycle. This method can simultaneously meet the requirements of stable dephosphorization rate of molten steel and smooth slag discharge of electric furnace slag during the service stage of the electric furnace.

[0012] The furnace age refers to the number of times the electric furnace has been used.

[0013] Preferably, in the step (2), the amount of lime added for the bottom of the electric furnace determined to be in the early stage of the service stage is 4 to 8 kg / ton of steel lime, and the amount of lime added for the silo of the electric furnace determined to be in the early stage of the service stage is 2 to 4 kg / ton of steel lime.

[0014] In the early stage of the service life of the electric furnace, since the furnace chamber is small and the molten pool height is high, in order to adjust the slag fluidity, 4-8kg / ton of steel lime is spread on the bottom and 2-4kg / ton of steel lime is added to the silo to ensure good slag formation and stable dephosphorization rate of molten steel in the early stage of the service life of the electric furnace.

[0015] Preferably, in the step (2), the amount of lime added for bottom paving in the electric furnace judged to be in the middle stage of service is 8-12 kg / ton of steel lime, and the amount of lime added for silo in the electric furnace judged to be in the middle stage of service is 4-8 kg / ton of steel lime.

[0016] In the middle of the service life of the electric furnace, since the furnace chamber is larger than the previous period and the molten pool height is lowered, in order to promote smooth slag flow in the electric furnace smelting process, 8-12kg / ton of steel lime is laid on the bottom and 4-8kg / ton of steel lime is added to the silo to ensure good slag formation and stable dephosphorization rate of molten steel in the middle of the service life of the electric furnace.

[0017] Preferably, in the step (2), the amount of lime added for the bottom of the electric furnace determined to be in the later stage of service is 16-22 kg / ton of steel lime, and the amount of lime added for the silo of the electric furnace determined to be in the later stage of service is 4-8 kg / ton of steel lime.

[0018] In the later period of the service life of the electric furnace, since the furnace chamber is significantly expanded compared with the previous period and the molten pool height is significantly reduced, in order to promote smooth slag flow in the electric furnace smelting process, 16-22kg / ton of steel lime is laid on the bottom and 4-8kg / ton of steel lime is added to the silo to ensure good slag formation and stable dephosphorization rate of molten steel in the later period of the service life of the electric furnace.

[0019] Preferably, step (2) of the method further comprises determining the basicity of the final slag during the pre-, mid- and post-service period of the electric furnace.

[0020] Preferably, the method is determined by:

[0021]

[0022] In the above formulas [1]-[3], (%P2O5) is the mass fraction of phosphorus pentoxide in the final slag of the electric furnace, (%CaO) is the mass fraction of calcium oxide in the final slag of the electric furnace, (%SiO2) is the mass fraction of silicon dioxide in the final slag of the electric furnace, (%MgO) is the mass fraction of magnesium oxide in the final slag of the electric furnace, and (%T.Fe) is the mass fraction of total iron in the final slag of the electric furnace.

[0023] Preferably, the step (2) specifically comprises: controlling the basicity of the electric furnace in the early service stage within the range of 2.70 to 3.15, controlling the basicity of the electric furnace in the middle service stage within the range of 3.35 to 4.25, and controlling the basicity of the electric furnace in the late service stage within the range of 4.40 to 5.30.

[0024] Controlling the basicity in the early, middle and late stages of the electric furnace service cycle within the range of 2.70-3.15, 3.35-4.25 and 4.40-5.30 can ensure good slag formation and stable dephosphorization rate of molten steel in the early stage of the electric furnace service cycle.

[0025] Preferably, the method for determining the service stage of the electric furnace according to the age of the electric furnace in step (2) is: determining the age of the electric furnace from 1 to 200 as the early stage of the service cycle of the electric furnace, from 201 to 500 as the middle stage of the service cycle of the electric furnace, and from 501 to 800 as the late stage of the service cycle of the electric furnace.

[0026] The "furnace age" mentioned in the present invention refers to the number of furnaces, that is, the number of times the electric furnace has been used.

[0027] Preferably, in step (3), the side oxygen lance blows oxygen weakly for 35 to 75 m 3 / t, single oxygen lance flow rate 500-3500Nm 3 The blowing time is 3 to 6 minutes; the power consumption of submerged arc electrode heating per ton of steel is 30 to 120 kW / t.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The present invention adopts a suitable electric furnace distribution method, implements segmented adjustment of the distribution method and addition amount of lime, and then regulates the basicity of the electric furnace final slag in the front-middle-end service cycle of the electric furnace, combines the side oxygen gun soft blowing and the submerged arc electrode heating, and improves the slag forming ability of the electric furnace in different service stages. The experimental results show that the electric furnace has no obvious slag drying phenomenon in a smelting cycle; the dephosphorization rate of molten steel at the end of the electric furnace is relatively stable, all above 89.0%, and the phosphorus distribution ratio between steel and slag at the end of the electric furnace is relatively high, within the range of 2.1 to 2.6. At the same time, the electric furnace slag has good fluidity throughout the service cycle, which can meet the requirements of smooth slag flow of the electric furnace. DETAILED DESCRIPTION

[0030] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0031] This embodiment provides a method for dynamically adjusting the basicity of an electric furnace in consideration of changes in the furnace during the pre-, mid- and post-service periods, including the following steps:

[0032] (1) After the previous furnace is tapped, 10% to 30% of the molten steel remains in the furnace, and all the oxygen slag is left for dephosphorization in the early stage of the next furnace;

[0033] (2) 30 to 45 tons of scrap steel are placed at the bottom of the electric furnace, and the service stage of the electric furnace is determined according to the furnace age. The method is as follows: the furnace age of 1-200 is determined as the early stage of the service cycle of the electric furnace, 201-500 is determined as the middle stage of the service cycle of the electric furnace, and 501-800 is determined as the late stage of the service cycle of the electric furnace;

[0034] Add 6-12kg / ton of steel lime to the electric furnace whose service stage is determined to be in the early stage, specifically: the amount of lime added for the bottom of the electric furnace determined to be in the early stage is 4-8kg / ton of steel lime, and the amount of lime added for the silo of the electric furnace determined to be in the early stage is 2-4kg / ton of steel lime; control the basicity of the electric furnace whose service stage is in the early stage within the range of 2.70-3.15;

[0035] Add 12-20 kg / ton of steel lime to the electric furnace whose service stage is determined to be in the middle stage. Specifically, the amount of lime added for the bottom of the electric furnace determined to be in the middle stage is 8-12 kg / ton of steel lime, and the amount of lime added for the silo of the electric furnace determined to be in the middle stage is 4-8 kg / ton of steel lime; the basicity of the electric furnace in the middle stage is controlled within the range of 3.35-4.25;

[0036] 20-30 kg / ton of steel lime is added to the electric furnace whose service stage is determined to be in the late stage. Specifically, the amount of lime added for the bottom of the electric furnace determined to be in the late stage is 16-22 kg / ton of steel lime, and the amount of lime added for the silo of the electric furnace determined to be in the late stage is 4-8 kg / ton of steel lime; the basicity of the electric furnace in the late stage is controlled within the range of 4.40-5.30;

[0037] The method of determination is:

[0038]

[0039] In the above formulas [1]-[3], (%P2O5) is the mass fraction of phosphorus pentoxide in the final slag of the electric furnace, (%CaO) is the mass fraction of calcium oxide in the final slag of the electric furnace, (%SiO2) is the mass fraction of silicon dioxide in the final slag of the electric furnace, (%MgO) is the mass fraction of magnesium oxide in the final slag of the electric furnace, and (%T.Fe) is the mass fraction of total iron in the final slag of the electric furnace.

[0040] (3) During the melting and cleaning period of each furnace, 35 to 75 m3 of oxygen is blown softly through the side oxygen lance. 3 / t, of which the flow rate of a single oxygen lance is 500-3500Nm3 , and the submerged arc electrode heats up, with the power consumption per ton of steel being 30 to 120 kW / t.

[0041] Key technical points of the method of the present invention:

[0042] Key point 1: In step (1), the previous furnace of liquid oxygen does not leave slag. Due to its own high temperature (>1600°C), it can better preheat the scrap steel and lime and other auxiliary materials added subsequently. This provides additional heat input for the scrap steel melting in the electric furnace, reducing the submerged arc electrode heating time required for scrap steel melting.

[0043] Key point 2: In step (2), scrap steel is placed at the bottom of the electric furnace. By placing scrap steel at the bottom of the electric furnace, on the one hand, the scrap steel is preheated by the oxygen slag left over from the previous furnace, reducing the heat input required for melting the scrap steel. On the other hand, molten iron is added to the top to strengthen the stirring of the molten pool, improve the kinetic conditions for melting the scrap steel, promote rapid melting of the scrap steel in the early stage, and shorten the time required for the electric furnace to reach the scrap steel molten clear state.

[0044] Key point 3: In step (2), the change of the furnace volume during the service cycle of the electric furnace is combined, and the distribution method and addition amount of lime are adjusted in stages during the service cycle of the electric furnace, thereby adjusting the basicity of the final slag of the electric furnace, ensuring the smooth slag flow of the electric furnace during the entire smelting cycle and stabilizing the dephosphorization rate of the molten steel at the end of the electric furnace.

[0045] Key point 4: In step (3), the kinetic conditions of lime melting in the electric furnace are improved by combining soft blowing of the side oxygen lance and heating of the submerged arc electrode. At the same time, heat is input into the molten pool through the submerged arc electrode, and the temperature of the electric furnace molten pool is rapidly increased on the basis of the residual heat of the slag in the electric furnace, thereby accelerating the rapid slag formation of lime in the early stage.

[0046] The reason why the present invention adopts the above method is that: when the number of furnaces in service of the electric furnace is less than 200 (early stage), the furnace chamber is small and the height of the molten pool is high. The T.Fe content in the electric furnace slag is low. In order to ensure smooth slag flow during the electric furnace smelting process, the slag alkalinity should be controlled not to be too high. When the number of furnaces in service of the electric furnace is 201 to 500, the furnace chamber of the electric furnace is larger than that in the early stage, and the height of the molten pool is reduced. In order to ensure smooth slag flow of the electric furnace and improve the terminal dephosphorization rate of the electric furnace, the amount of lime added can be appropriately increased to increase the alkalinity of the electric furnace slag. When the number of furnaces in service of the electric furnace is 501 to 800, it is the late stage of the service cycle of the electric furnace. The furnace chamber of the electric furnace is significantly larger than that in the early stage, and the height of the molten pool is significantly reduced. At this time, the T.Fe content in the electric furnace slag is usually above 22%. At this time, the fluidity of the electric furnace slag can be guaranteed by disordered additional operations. The focus of attention is turned to how to further improve the terminal dephosphorization rate of the electric furnace. Therefore, the amount of lime added can be further increased to continue to increase the alkalinity of the electric furnace slag.

[0047] For each furnace smelting process, when the furnace blowing time is less than 3 minutes, the lime slag is not sufficient, the silicon and phosphorus in the molten iron compete for desiliconization, and the dephosphorization reaction has not yet begun. When the furnace blowing time is more than 20 minutes, the molten iron temperature is too high, which is not conducive to the dephosphorization reaction. At the same time, excessive oxygen blowing will increase the FeO content in the dephosphorization slag, resulting in higher iron loss.

[0048] The present invention has found through a large number of studies that in the electric furnace steelmaking process, the amount of bottom lime and the ratio of molten iron to scrap steel will change significantly in the early, middle and late stages of the electric furnace service.

[0049] In the early and middle batches of the electric furnace, the furnace is small and the molten pool height is high. In order to quickly achieve the melting of scrap steel in the electric furnace, the molten iron / scrap steel ratio is high, and the amount of lime added mainly depends on the silicon content of the molten iron. Since the melting time of scrap steel in the electric furnace is short, the lime does not have time to melt completely. At this time, it is necessary to increase the FeO content in the melting slag to reduce the viscosity of the melting slag to ensure the smooth slag flow operation of the electric furnace.

[0050] In the later batches of EAF smelting, due to lining erosion, the furnace chamber becomes significantly larger than the early and middle stages. At this time, the molten pool depth is low, and the lower molten iron / scrap ratio can also quickly achieve the melting of EAF scrap steel. At this time, the amount of lime added mainly depends on the silicon content in the molten iron and the silicon content in the scrap steel. The FeO content in the slag of the later batches of EAF smelting is high, which can achieve better lime slag formation, which also reduces the difficulty of EAF slag flow operation.

[0051] Embodiment The operation and regulation are performed according to the lime addition amount and distribution method of the electric furnace in the early, middle and late stages of service as determined by the present invention. In the comparative example, except for the lime addition amount and distribution method of the electric furnace in the early, middle and late stages of service, the other operations are the same as those of the embodiment. The details are shown in Table 1:

[0052] Table 1: Distribution method of the embodiment and comparative example, chemical composition of the final slag of the electric furnace, predicted and calculated values ​​of phosphorus distribution ratio, dephosphorization rate of molten steel, furnace age and smelting cycle determination results

[0053]

[0054] As can be seen from Table 1 above, in the embodiment, the lime addition amount and the distribution method in the early, middle and late stages of the electric furnace service determined by the present invention are operated and regulated, and the dephosphorization rate of the molten steel at the end of the electric furnace is relatively stable, all above 89.0%, and the phosphorus distribution ratio between steel and slag at the end of the electric furnace is relatively high, within the range of 2.1 to 2.6. At the same time, the electric furnace slag has good fluidity throughout the service cycle, which can meet the requirements of smooth slag flow of the electric furnace, and the electric furnace has no obvious slag drying phenomenon during the entire service cycle. This method can simultaneously meet the requirements of stable dephosphorization rate of molten steel at the end of electric furnace steelmaking and smooth slag discharge of electric furnace slag.

[0055] In Comparative Example 1, 13.2 kg / ton of steel lime was added to the 122nd furnace in service (determined to be the early stage of service of the electric furnace), and the slag basicity was 3.54. The results showed that lime slag was difficult, the electric furnace slag had high viscosity, the electric furnace slag flow was difficult, and the molten steel dephosphorization rate was low, at 82.25%, lower than 89.00%.

[0056] In Comparative Example 2, 8.89 kg / ton of steel lime was added to the 316th furnace in service (determined to be in the middle of service of the furnace), and the slag basicity was 3.20. The results showed that the lime slag was good and the furnace was discharged smoothly, but because the amount of lime added was small, the dephosphorization rate of the molten steel was low, at 84.78%, lower than 89.00%.

[0057] In Comparative Example 3, 33.78 kg / ton of steel lime was added to the 663rd furnace in service (determined to be in the late service period of the furnace), and the slag basicity was 5.40. The results showed that lime slag was difficult, and the surface of the furnace slag had obvious black blocks. Due to the large amount of undissolved lime being discharged, the dephosphorization rate of molten steel was low, at 87.19%, lower than 89.00%.

[0058] The present invention leaves part of the molten steel in the electric furnace after the steel is tapped at the end of the previous electric furnace, and leaves all the final slag of the electric furnace for the early dephosphorization of the next furnace, spreads scrap steel at the bottom of the electric furnace, and adjusts the distribution method and addition amount of lime in sections during the service period of the electric furnace before, during and after the service period, thereby regulating the basicity of the final slag of the electric furnace; at the same time, during the melting process of the scrap steel in the electric furnace, the early lime is promoted to form slag quickly through soft blowing of the side oxygen gun and heating of the submerged arc electrode, thereby adapting to the change in slag composition caused by the change in the volume of the electric furnace chamber caused by the erosion of the furnace lining. In this way, electric furnace slag with good fluidity is formed in the three stages of the service period before, during and after the electric furnace, and the stability of the dephosphorization rate of the molten steel at the end of the electric furnace is guaranteed, and it is ensured that there is no obvious slag drying phenomenon in the electric furnace during the smelting cycle. The method can simultaneously meet the requirements of stable dephosphorization rate of molten steel and smooth slag discharge of electric furnace slag during the service period of the electric furnace.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for dynamically adjusting basicity of an electric furnace taking into account changes in the furnace during the pre-, mid- and post-service periods, characterized in that: The following steps are involved: (1) After the previous furnace is tapped, 10% to 30% of the molten steel remains in the furnace, and all the final slag is left for dephosphorization in the early stage of the next furnace; (2) Place 30 to 45 tons of scrap steel at the bottom of the electric furnace, determine the service stage of the electric furnace according to the age of the electric furnace, and divide the service stage of the electric furnace into early, middle and late stages; and add lime in the following manner: In the early stage of the electric furnace service, add 6-12kg / ton of steel lime. Add 12-20kg / ton of steel lime to the electric furnace that is judged to be in the middle stage of service. Add 20-30kg / ton of steel lime to the electric furnace that is judged to be in the late stage of service; (3) During the melting process of scrap steel in an electric furnace, smelting is carried out by soft blowing of the side oxygen lance and heating of the submerged arc electrode.

2. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: In the step (2), the amount of lime added for the bottom of the electric furnace determined to be in the early stage of the service of the electric furnace is 4 to 8 kg / ton of lime, and the amount of lime added for the silo of the electric furnace determined to be in the early stage of the service of the electric furnace is 2 to 4 kg / ton of lime.

3. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: In the step (2), the amount of lime added for bottom paving in the electric furnace determined to be in the middle stage of service is 8-12 kg / ton of steel lime, and the amount of lime added for silo in the electric furnace determined to be in the middle stage of service is 4-8 kg / ton of steel lime.

4. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: In the step (2), the amount of lime added for the bottom of the electric furnace determined to be in the late stage of service is 16-22 kg / ton of steel lime, and the amount of lime added for the silo of the electric furnace determined to be in the late stage of service is 4-8 kg / ton of steel lime.

5. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: The method step (2) also includes determining the basicity of the final slag in the pre-, mid- and post-service cycle of the electric furnace. Preferably, the method is determined by: In the above formulas [1]-[3], (%P2O5) is the mass fraction of phosphorus pentoxide in the final slag of the electric furnace, (%CaO) is the mass fraction of calcium oxide in the final slag of the electric furnace, (%SiO2) is the mass fraction of silicon dioxide in the final slag of the electric furnace, (%MgO) is the mass fraction of magnesium oxide in the final slag of the electric furnace, and (%T.Fe) is the mass fraction of total iron in the final slag of the electric furnace.

6. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: The step (2) specifically includes: controlling the basicity of the electric furnace in the early service stage within the range of 2.70 to 3.15, controlling the basicity of the electric furnace in the middle service stage within the range of 3.35 to 4.25, and controlling the basicity of the electric furnace in the late service stage within the range of 4.40 to 5.

30.

7. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: The method for determining the service stage of the electric furnace according to the age of the electric furnace in step (2) is as follows: determining an age of 1-200 as the early stage of the service cycle of the electric furnace, 201-500 as the middle stage of the service cycle of the electric furnace, and 501-800 as the late stage of the service cycle of the electric furnace.

8. The method for dynamic adjustment of alkalinity according to claim 1, characterized in that: In step (3), the side oxygen lance blows oxygen weakly for 35 to 75 m 3 / t, single oxygen lance flow rate 500-3500Nm 3 The blowing time is 3 to 6 minutes; the power consumption of submerged arc electrode heating per ton of steel is 30 to 120 kW / t.

Images