Method for reducing the consumption of lime in the smelting of stainless steel from nickel-iron matte using aod

Abstract

The application discloses a method for reducing lime consumption in smelting stainless steel from ferro-nickel water, and belongs to the technical field of stainless steel smelting. The method mainly comprises nine steps of iron adding, desiliconizing period, main decarburization period, secondary decarburization period, side gun decarburization first stage, side gun decarburization second stage, side gun decarburization third stage, reduction stage and adjustment stage. The method can significantly reduce lime consumption, indirectly reduce ferrosilicon and fluorite consumption, and reduce production cost by stabilizing the alkalinity and silicon content in the desiliconizing period, improving the carbon content at the end of the main decarburization period and the secondary decarburization period, and reducing the oxygen supply intensity in the secondary decarburization period and the oxidation of Cr elements in the oxidation process.

Description

Technical Field

[0001] This invention belongs to the field of stainless steel smelting technology, specifically relating to a method for reducing lime consumption in the smelting of stainless steel using AOD (Alkali Oxide Discharge). Background Technology

[0002] Stainless steel smelting is a typical resource- and energy-intensive process. The AOD (argon-oxygen decarburization) furnace, as the core equipment in stainless steel refining, achieves decarburization and chromium retention through mixed oxygen and argon blowing. Simultaneously, a large amount of lime (CaO) and other auxiliary materials are added for slag formation, desulfurization, dephosphorization, and slag basicity control. The AOD furnace has a natural cost advantage in smelting stainless steel using ferronickel in a submerged arc furnace, significantly reducing heat loss during production. However, the AOD furnace smelting of stainless steel always involves conjugated reactions between Cr and C elements. To reduce Cr oxidation, it is necessary to increase the molten pool temperature and maintain it in a relatively stable state, reduce the partial pressure of CO gas, and improve the thermodynamic and kinetic conditions for C-O transfer. This is achieved by blowing inert gases (Ar, N2) into the molten steel to reduce the partial pressure of CO and maintain the molten pool at a high and uniform temperature, thus achieving "decarburization and chromium retention" (as shown in reaction formulas ①, ②, ③, and ④), thereby smelting stainless steel.

[0003] [C] + [O] = CO↑ ①

[0004] 2[Cr] + 3[O] = (Cr₂O₃) ②

[0005] 3[C]+(Cr2O3 )=2[Cr]+3CO↑ ③

[0006] [Fe] + [O] = (FeO) ④

[0007] The following problems exist with lime consumption in traditional AOD processes: 1) The contradiction between the demand for high-basicity slag and excessive lime addition: Stainless steel smelting requires desulfurization through high-basicity slag (CaO / SiO2>1.8), but the silicon content in ferronickel fluctuates significantly (usually 0.5%~2.5%); to neutralize the SiO2 generated by silicon oxidation and maintain the slag basicity, a large amount of lime needs to be added. 2) The challenge of ferronickel characteristics to slag stability: Although the high nickel and low phosphorus characteristics of ferronickel are beneficial to the control of stainless steel composition, the fluctuation of its silicon and carbon content easily causes instability of SiO2 and FeO in the slag during the initial blowing stage. In order to inhibit Cr oxidation and stabilize the slag phase, traditional processes usually adopt a strong slag-forming mode of "high lime", further increasing lime consumption. To reduce lime consumption, the industry has tried various solutions, but the specific effects are inconsistent. The AOD furnace itself cannot eliminate the conjugated reaction between oxygen and Cr and C elements. It can only reduce Cr oxidation through conventional methods such as increasing the molten pool temperature and reducing CO partial pressure. Essentially, it cannot further reduce Cr oxidation, and under stable reducing alkalinity conditions, lime consumption is difficult to further reduce. Therefore, how to further reduce lime consumption in the AOD smelting process for stainless steel has become an urgent technical problem to be solved in this field. Summary of the Invention

[0008] The purpose of this invention is to provide a method for reducing lime consumption in the smelting of stainless steel using AOD (Alternating Oxygen Demand). By rationally optimizing the parameters of the oxygen lance and side lance in the AOD furnace, the carbon content target at the end of the main decarburization period and the secondary decarburization period is improved. The temperature and composition of each step are precisely controlled to meet the requirements. The steps work synergistically and complement each other, which greatly reduces the consumption of lime and other raw materials, and reduces the production cost of stainless steel by 25.6 yuan / ton.

[0009] To achieve the above-mentioned technical objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for reducing lime consumption in the smelting of stainless steel using ferronickel and aluminum ore using oxidative drying (AOD) includes the following steps:

[0011] 1) Adding molten nickel-iron to the AOD furnace: Add the molten nickel-iron from the submerged arc furnace into the AOD furnace;

[0012] 2) Desiliconization period: Control the temperature of the molten pool during the desiliconization period, adjust the position of the oxygen lance and set the oxygen / nitrogen flow rate of the AOD furnace oxygen lance and the oxygen / nitrogen flow rate of the side lance respectively for blowing. During the blowing, lime, high silicon ferrochrome, medium nickel pig iron, and scrap steel are added to the molten pool in sequence and ferrosilicon is added. Blow until the target silicon content is reached. After desiliconization is completed, the slag is poured off and the slag basicity is controlled at 1.0-1.1.

[0013] 3) Main decarburization period: After the slag is poured out, lime, low silicon high chromium alloy and water-quenched nickel iron are added to control the temperature of the molten pool during the main decarburization period, adjust the position of the oxygen lance, set the oxygen / nitrogen gas ratio in the oxygen lance and the side lance, and blow until the carbon content at the end of the main decarburization period is reached and the target basicity at the end of the main decarburization period is controlled to be greater than 2.5.

[0014] 4) Secondary decarburization period: Add lime, set the oxygen / nitrogen ratio in the oxygen lance and side lance, and blow until the carbon content at the end of the secondary decarburization period is reached;

[0015] 5) First stage of decarburization by side lance: using only side lances for blowing, adjusting the ratio of oxygen / nitrogen in the side lance gas, and blowing until the carbon content of the molten pool reaches the first target carbon content;

[0016] 6) Second stage of decarburization by side lance: using only side lances for blowing, adjusting the ratio of oxygen / nitrogen in the side lance gas, and blowing until the carbon content of the molten pool reaches the second target carbon content;

[0017] 7) Third stage of decarburization by side lance: using only side lances for blowing, adjusting the ratio of oxygen / nitrogen in the side lance gas, and blowing until the carbon content of the molten pool reaches the target carbon content;

[0018] 8) Reduction period: Control the temperature of the molten pool during the reduction period, add ferrosilicon, silicomanganese and fluorite in sequence, adjust the side gun gas to argon, adjust the gas intensity for blowing, pour off the slag after blowing, and control the basicity of the reduction slag within the target reduction basicity range.

[0019] 9) Adjustment period: After analyzing the composition of the reduced sample, lime and fluorite are added for fine adjustment according to the steel content requirements. At the same time, side blowing is carried out. After the blowing is completed, steel can be tapped according to the steelmaking procedure.

[0020] Preferably, a single-hole oxygen lance is arranged on the top of the AOD furnace, and six side lances are arranged on the rear wall of the furnace body at a distance of 460mm from the bottom, with an included angle of 24° between the side lances and a 120° fan-shaped distribution.

[0021] Preferably, the temperature of the molten nickel-iron in step 1) is 1250-1350℃.

[0022] Preferably, in step 2), the temperature during the desilication period of the molten pool is 1500-1550℃; the oxygen / nitrogen flow rate of the oxygen lance is set to 140 / 0 Nm. 3 / min, gun position 2.45m; side gun oxygen / nitrogen flow rate set to 100 / 20 Nm 3 / min; the target silicon content in the molten pool is 0.15%-0.30%.

[0023] Preferably, in step 3), the molten pool temperature during the main decarburization period is 1670-1700℃; the oxygen lance position is 2.55m, and the oxygen / nitrogen flow rate of the oxygen lance is set to 160 / 0 Nm³. 3 / min, side gun oxygen / nitrogen flow rate set to 100 / 20 Nm 3 / min; the carbon content at the end of the main decarbonization period was 0.7%.

[0024] Preferably, in step 4), the oxygen / nitrogen flow rate of the oxygen lance is set to 70 / 70 Nm. 3 / min, side gun oxygen / nitrogen flow rate set to 40 / 60 Nm 3 / min; the carbon content at the end of the second decarbonization period was 0.5%.

[0025] Preferably, the oxygen / nitrogen flow rate of the side gun in the first stage of the side gun decarburization is 55 / 60 Nm. 3 / min, the first target carbon content is 0.20%-0.30%; the second stage of side-gun decarburization has an oxygen / nitrogen flow rate of 40 / 85 Nm. 3 / min, the second target carbon content is 0.10%-0.15%; the third stage of side-gun decarbonization has an oxygen / nitrogen flow rate of 30 / 95 Nm. 3 / min, with a target carbon content of 0.03%-0.05%.

[0026] Preferably, in step 8), the side-gun gas intensity is 70 Nm. 3 / min, target reducing basicity is 2.0-2.2; melting pool temperature during reduction period is 1680-1710℃.

[0027] Preferably, in step 9), the side-blowing gas is argon with a flow rate of 50 Nm³. 3 The steel can be tapped after blowing for 3-5 minutes at a speed of 0.5 min.

[0028] Preferably, in step 3), the Si content in the low-silicon high-chromium alloy is ≤0.8%.

[0029] All stainless steels used in this invention are 304 stainless steel.

[0030] The beneficial effects of this invention are as follows: Based on the existing AOD calculation model, this invention stabilizes the alkalinity, molten pool silicon content, and temperature during the desilication period, increases the carbon content at the end of the main decarburization period and the secondary decarburization period, reduces the oxygen supply intensity during the secondary decarburization period, reduces the overall oxidation of Cr element during the oxidation period, controls the silicon reduction consumption at 4.5-5.0 kg / t, significantly improves the purity of molten steel, and greatly reduces lime consumption to 12.7 t / furnace, indirectly affecting the reduction of ferrosilicon and fluorite consumption, significantly reducing production costs. According to comprehensive calculations, the production cost per ton of steel can be reduced by 25.6 yuan, resulting in significant economic benefits. Detailed Implementation

[0031] The technical solution of the present invention will be further described below with reference to specific embodiments, but it is not limited thereto.

[0032] Example 1

[0033] A method for reducing lime consumption in the smelting of stainless steel using AOD (Alkali Oxide Discharge) to produce 304 stainless steel is described below:

[0034] 1) Iron addition: After the molten nickel-iron furnace treatment is completed, it is hoisted by overhead crane and added to the AOD furnace. The added weight is 78.2t, and the initial temperature is 1321℃. The composition of the molten nickel-iron is as follows:

[0035]

[0036] The AOD furnace has a single-hole oxygen lance arranged on the top of the furnace and six side lances arranged on the rear wall of the furnace body at a distance of 460mm from the bottom. The side lances are arranged at an angle of 24° and in a 120° fan shape.

[0037] 2) Desilication period:

[0038] After the iron mixing process is completed, 7.6t of lime is added during the blowing process, followed by 33.8t of high-silicon ferrochrome, 15.0t of medium-nickel pig iron, and 5.6t of self-circulating scrap steel. Based on the AOD calculation model, 2.2t of ferrosilicon is added. The oxygen lance is positioned at 2.45m, and the oxygen / nitrogen gas ratio is 140 / 0 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 100 / 20Nm 3 / min, after the desilication period, the slag was dumped, the calculated basicity of the slag was 1.08, the desilication end temperature was 1509℃, and the Si content in the molten pool was 0.18%;

[0039] 3) Main decarbonization period:

[0040] After slag removal, add 4 tons of lime according to the AOD calculation model, along with 6.7 tons of low-silicon, high-chromium hydroxide and 1.0 tons of water-quenched nickel-iron. Position the oxygen lance at 2.55 meters and maintain the oxygen lance gas ratio (oxygen / nitrogen) at 160 / 0 Nm³. 3 / min, side gun gas ratio (oxygen / nitrogen) 100 / 20 Nm 3 / min, the carbon content target at the end of the main decarburization period is 0.7%, and the basicity is greater than 2.5 to prevent the carbon content from being controlled too low and causing premature oxidation of Cr. At this time, the molten pool temperature during the main decarburization period is 1680℃.

[0041] 4) Secondary decarbonization period:

[0042] Entering the secondary decarbonization period, add 1 t of lime, position the oxygen lance at 2.40 m, and set the oxygen lance gas ratio (oxygen / nitrogen) to 70 / 70 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 40 / 60 Nm 3 / min, blowing to the end of the second decarburization period with a carbon content of 0.50%.

[0043] 5) First stage of decarburization of the side gun:

[0044] Entering the first stage of side-lance refining, only side-lance blowing is used, with a side-lance gas ratio (oxygen / nitrogen) of 60 / 70 Nm. 3 The oxygen blowing rate was 1695℃. After the oxygen blowing was completed, the temperature was measured and a sample was taken. The process sample analysis showed that the C content was 0.29% and the Cr content was 17.70%.

[0045] 6) Second stage of side lance decarburization: Entering the second stage of side lance decarburization, only side lance blowing is used, and the side lance gas ratio (oxygen / nitrogen) is 40 / 85 Nm. 3 / min, until the carbon content of the molten pool is reduced to 0.13%.

[0046] 7) Side-lance decarburization stage 3: Entering the third stage of side-lance decarburization, only side-lance blowing is used, and the side-lance gas ratio (oxygen / nitrogen) is 30 / 95 Nm. 3 / min, blowing until the endpoint enters the reduction period, the carbon content of the final molten pool is 0.03%-0.05%.

[0047] 8) Reduction Period: Entering the reduction period, add 0.9t of ferrosilicon, 1.8t of silicomanganese, and 1.2t of fluorite sequentially. The target alkalinity is 2.0-2.2. The side-gun gas ratio (oxygen / argon) is 0 / 70 Nm. 3 After blowing for 7 minutes at a rate of / min, the residue was poured off, and the temperature was measured and sampled. The measured temperature was 1663℃. The reduced composition of the sample is as follows:

[0048]

[0049] 9) Adjustment Period: After the analysis of the reduced sample is completed, the adjustment period begins. Add 0.1t of lime and 0.1t of fluorite. The side gun gas ratio (oxygen / argon) is 0 / 50 Nm. 3 The steel was tapped after blowing for 3 minutes at a rate of 12.7 tons per minute. The total amount of lime used in this AOD furnace process was 12.7 tons.

[0050] Example 2

[0051] A method for reducing lime consumption in the smelting of stainless steel using AOD (Alkali Oxide Discharge) to produce 304 stainless steel is described below:

[0052] 1) Iron addition: After the molten nickel-iron furnace treatment is completed, it is hoisted by overhead crane and added to the AOD furnace. The added weight is 77.0t, and the initial temperature is 1288℃. The composition of the molten nickel-iron is as follows:

[0053]

[0054] The AOD furnace has a single-hole oxygen lance arranged on the top of the furnace and six side lances arranged on the rear wall of the furnace body at a distance of 460mm from the bottom. The side lances are arranged at an angle of 24° and in a 120° fan shape.

[0055] 2) Desilication period:

[0056] After the iron mixing process is completed, 7.6t of lime is added during the blowing process, followed by 35.8t of high-silicon ferrochrome, 10.0t of medium-nickel pig iron, and 5.6t of self-circulating scrap steel. Based on the AOD calculation model, 1.9t of ferrosilicon is added. The oxygen lance is positioned at 2.45m, and the oxygen lance gas ratio (oxygen / nitrogen) is 140 / 0 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 100 / 20Nm 3 / min, after the desilication period, the slag was dumped, the calculated basicity of the slag was 1.09, the desilication end temperature was 1511℃, and the Si content in the molten pool was 0.20%;

[0057] 3) Main decarbonization period:

[0058] After slag removal, add 4 tons of lime according to the AOD calculation model, along with 4.3 tons of low-silicon, high-chromium and 4.7 tons of medium-nickel pig iron. Position the oxygen lance at 2.55m, and maintain the oxygen lance gas ratio (oxygen / nitrogen) at 160 / 0 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 100 / 20 Nm 3 / min, the carbon content target at the end of the main decarburization period is 0.7%, and the basicity is greater than 2.5 to prevent the carbon content from being controlled too low and causing premature oxidation of Cr. At this time, the molten pool temperature during the main decarburization period is 1680℃.

[0059] 4) Secondary decarbonization period:

[0060] Entering the secondary decarbonization period, add 1 t of lime, position the oxygen lance at 2.40 m, and set the oxygen lance gas ratio (oxygen / nitrogen) to 70 / 70 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 40 / 60 Nm 3 / min, blowing to the end of the second decarburization period with a carbon content of 0.50%.

[0061] 5) First stage of decarburization of the side gun:

[0062] Entering the first stage of side-lance refining, only side-lance blowing is used, with a side-lance gas ratio (oxygen / nitrogen) of 60 / 70 Nm. 3 The oxygen blowing rate was 1699℃. After the oxygen blowing was completed, the temperature was measured and a sample was taken. The process sample analysis showed that the C content was 0.236% and the Cr content was 17.69%.

[0063] 6) Second stage of side lance decarburization: Entering the second stage of side lance decarburization, only side lance blowing is used, and the side lance gas ratio (oxygen / nitrogen) is 40 / 85 Nm.3 / min, until the carbon content of the molten pool is reduced to 0.13%.

[0064] 7) Side-lance decarburization stage 3: Entering the third stage of side-lance decarburization, only side-lance blowing is used, and the side-lance gas ratio (oxygen / nitrogen) is 30 / 95 Nm. 3 / min, blowing until the endpoint enters the reduction period, the carbon content of the final molten pool is 0.03%-0.05%.

[0065] 8) Reduction Period: Entering the reduction period, add 0.75t of ferrosilicon, 1.8t of ferromanganese silicon, and 1.0t of fluorite sequentially. The target alkalinity is 2.0-2.2. The side-gun gas ratio (oxygen / argon) is 0 / 70 Nm. 3 After blowing for 7 minutes at a rate of / min, the residue was poured off, and the temperature was measured and sampled at 1688℃. The reduced composition of the sample is as follows:

[0066]

[0067] 9) Adjustment Period: After the analysis of the reduced sample is completed, the adjustment period begins. Add 0.3t of lime and 0.1t of fluorite. The side gun gas ratio (oxygen / argon) is 0 / 50 Nm. 3 The steel was tapped after blowing for 3 minutes at a rate of 12.9 tons per minute. The total amount of lime used in this AOD furnace process was 12.9 tons.

[0068] Example 3

[0069] A conventional process for smelting stainless steel using an AOD furnace with molten nickel to produce 304 stainless steel involves the following steps:

[0070] 1) Adding molten iron: After the molten nickel-iron furnace treatment is completed, it is hoisted by overhead crane and added to the AOD furnace. The added weight is 77.6t, and the initial temperature is 1305℃. The composition of the molten nickel-iron is as follows:

[0071]

[0072] The AOD furnace has a single-hole oxygen lance arranged on the top of the furnace and six side lances arranged on the rear wall of the furnace body at a distance of 460mm from the bottom. The side lances are arranged at an angle of 24° and in a 120° fan shape.

[0073] 2) Desilication period:

[0074] After the iron mixing process is completed, 7.8t of lime is added during the blowing process, followed by 37.0t of high-silicon ferrochrome and 18.5t of medium-nickel pig iron. Based on the AOD calculation model, 3.0t of ferrosilicon is added. The oxygen lance is positioned at 2.45m, and the oxygen lance gas ratio (oxygen / nitrogen) is 140 / 0 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 100 / 20 Nm 3 / min, slag was dumped after the desilication period, the calculated basicity of the slag was 1.10, the desilication end temperature was 1549℃, and the Si content in the molten pool was 0.31%;

[0075] 3) Main decarbonization period:

[0076] After slag removal, add 5 tons of lime according to the AOD calculation model, along with 5.5 tons of low-silicon, high-chromium hydroxide and 7.5 tons of water-quenched nickel-iron. Position the oxygen lance at 2.55 meters and maintain the oxygen lance gas ratio (oxygen / nitrogen) at 160 / 0 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 100 / 20 Nm 3 / min, with a target carbon content of 0.5% at the end of the main decarbonization period and an alkalinity greater than 2.5.

[0077] 4) Secondary decarbonization period:

[0078] Entering the secondary decarbonization period, add 1 t of lime, position the oxygen lance at 2.40 m, and set the oxygen lance gas ratio (oxygen / nitrogen) to 120 / 20 Nm. 3 / min, side gun gas ratio (oxygen / nitrogen) 60 / 60 Nm 3 / min, carbon content at the end of the second decarbonization period was 0.30%.

[0079] 5) First stage of decarburization of the side gun:

[0080] Entering the first stage of side-lance refining, only side-lance blowing is used, with 0.8t of lime added, and the side-lance gas ratio (oxygen / nitrogen) is 60 / 70 Nm. 3 The oxygen blowing rate was 1710℃. After the oxygen blowing was completed, the temperature was measured and a sample was taken. The process sample analysis showed that the C content was 0.18% and the Cr content was 16.90%.

[0081] 6) Second stage of side gun decarburization:

[0082] Entering the second stage of side-lance refining, only side-lance blowing is used, with a side-lance gas ratio (oxygen / nitrogen) of 40 / 85 Nm. 3 / min, until the carbon content of the molten pool is reduced to 0.13%.

[0083] 7) Third stage of side gun decarburization:

[0084] Entering the third stage of side-lance refining, only side-lance blowing is used, with a side-lance gas ratio (oxygen / nitrogen) of 30 / 95 Nm. 3 / min, blowing to the end point and entering the reduction period.

[0085] 8) Recovery period:

[0086] Entering the reduction phase, 1.4t of ferrosilicon, 1.9t of silicomanganese, and 1.4t of fluorite were added sequentially, with a target alkalinity of 1.8-2.0. The side-gun gas ratio (oxygen / argon) was 0 / 70 Nm.3 After blowing for 7 minutes, the residue was poured out, and the temperature was measured and sampled. The measured temperature was 1691℃. The reducing composition is as follows:

[0087]

[0088] 9) Adjustment period:

[0089] After the analysis of the reduced sample is completed, the adjustment period begins. Add 1.0t of lime, 0.25t of fluorite, 0.2t of silicon manganese, and 0.5t of low-carbon ferrochrome. The side-gun gas ratio (oxygen / argon) is 0 / 50 Nm. 3 The steel was tapped after blowing for 5 minutes at a rate of 15.6 tons per minute. The total amount of lime used in this AOD furnace process was 15.6 tons.

[0090] It should be noted that the above embodiments are merely some preferred embodiments of the present invention, and not all embodiments. Obviously, based on the above embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

Claims

1. A method for reducing lime consumption in the smelting of stainless steel using AOD (Alkali Oxide Discharge), characterized in that, It includes the following steps: 1) Adding molten nickel-iron to the AOD furnace: Add the molten nickel-iron from the submerged arc furnace into the AOD furnace; 2) Desiliconization period: Control the temperature of the molten pool during the desiliconization period, adjust the position of the oxygen lance and set the oxygen / nitrogen flow rate of the AOD furnace oxygen lance and the oxygen / nitrogen flow rate of the side lance respectively for blowing. During the blowing, lime, high silicon ferrochrome, medium nickel pig iron, and scrap steel are added to the molten pool in sequence and ferrosilicon is added. Blow until the target silicon content is reached. After desiliconization is completed, the slag is poured off and the slag basicity is controlled at 1.0-1.

1. 3) Main decarburization period: After the slag is poured out, lime, low silicon high chromium alloy and water-quenched nickel iron are added to control the temperature of the molten pool during the main decarburization period, adjust the position of the oxygen lance, set the oxygen / nitrogen gas ratio in the oxygen lance and the side lance, and blow until the carbon content at the end of the main decarburization period is reached and the target basicity at the end of the main decarburization period is controlled to be greater than 2.

5. 4) Secondary decarburization period: Add lime, set the oxygen / nitrogen ratio in the oxygen lance and side lance, and blow until the carbon content at the end of the secondary decarburization period is reached; 5) First stage of decarburization by side lance: using only side lances for blowing, adjusting the ratio of oxygen / nitrogen in the side lance gas, and blowing until the carbon content of the molten pool reaches the first target carbon content; 6) Second stage of decarburization by side lance: using only side lances for blowing, adjusting the ratio of oxygen / nitrogen in the side lance gas, and blowing until the carbon content of the molten pool reaches the second target carbon content; 7) Third stage of decarburization by side lance: using only side lances for blowing, adjusting the ratio of oxygen / nitrogen in the side lance gas, and blowing until the carbon content of the molten pool reaches the target carbon content; 8) Reduction period: Control the temperature of the molten pool during the reduction period, add ferrosilicon, silicomanganese and fluorite in sequence, adjust the side gun gas to argon, adjust the gas intensity for blowing, pour off the slag after blowing, and control the basicity of the reduction slag within the target reduction basicity range. 9) Adjustment period: After analyzing the composition of the reduced sample, lime and fluorite are added for fine adjustment according to the steel content requirements. At the same time, side blowing is carried out. After the blowing is completed, steel is tapped according to the steelmaking procedure. The AOD furnace has a single-hole oxygen lance arranged on the top of the furnace and six side lances arranged on the rear wall of the furnace body at a distance of 460mm from the bottom. The side lances are arranged at an angle of 24° and in a 120° fan-shaped distribution. In step 2), the temperature during the desiliconization period of the molten pool is 1500-1550℃; the oxygen / nitrogen flow rate of the oxygen lance is set to 140 / 0 Nm. 3 / min, gun position 2.45m; side gun oxygen / nitrogen flow rate set to 100 / 20 Nm 3 / min; the target silicon content in the molten pool is 0.15%-0.30%; In step 3), the molten pool temperature during the main decarburization period is 1670-1700℃; the oxygen lance position is 2.55m, and the oxygen / nitrogen flow rate of the oxygen lance is set to 160 / 0 Nm³. 3 / min, side gun oxygen / nitrogen flow rate set to 100 / 20 Nm 3 / min; the carbon content at the end of the main decarbonization period was 0.7%; In step 4), the oxygen / nitrogen flow rate of the oxygen lance is set to 70 / 70 Nm. 3 / min, side gun oxygen / nitrogen flow rate set to 40 / 60 Nm 3 / min; the carbon content at the end of the second decarbonization period was 0.5%; The oxygen / nitrogen flow rate of the side gun in the first stage of decarburization is 55 / 60 Nm. 3 / min, the first target carbon content is 0.20%-0.30%; the second stage of side-gun decarburization has an oxygen / nitrogen flow rate of 40 / 85 Nm. 3 / min, the second target carbon content is 0.10%-0.15%; the third stage of side-gun decarbonization has an oxygen / nitrogen flow rate of 30 / 95 Nm. 3 / min, with a target carbon content of 0.03%-0.05%; In step 8), the side gun gas intensity is 70 Nm. 3 / min, target reducing basicity is 2.0-2.2; melt pool temperature during reduction period is 1680-1710℃; In step 9), the side-blowing gas is argon with a flow rate of 50 Nm³. 3 The steel can be tapped after blowing for 3-5 minutes at a speed of 0.5 min; the stainless steel is 304 stainless steel.

2. The method for reducing lime consumption in the smelting of stainless steel using AOD according to claim 1, characterized in that, In step 1), the temperature of the molten nickel-iron is 1250-1350℃.

3. The method for reducing lime consumption in the smelting of stainless steel using AOD according to claim 1, characterized in that, In step 3), the Si content in the low-silicon high-chromium alloy is ≤0.8%.

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