Method for alloying nickel-containing pig iron in converter

Abstract

The invention discloses an in-converter alloying method for nickel-containing pig iron, and relates to the technical field of steel smelting. The in-converter alloying method for the nickel-containing pig iron is characterized by comprising the following specific operation: S1, nickel-containing raw iron alloying cost reduction calculation is carried out, specifically, the relative cost reduction is calculated according to nickel-containing pig iron, metal nickel components and the price of the pig iron, and the calculation process is as follows: 0.010% of Ni element is added in molten steel as the standard; according to the in-converter alloying method for the nickel-containing pig iron, a relative cost calculation method is provided according to the sulfur load, an optimal calculation method under the boundary condition is invented on the basis, the method mainly comprises batching, charging and smelting control, the adding amount of the nickel-containing pig iron can reach 270 kg / t steel, the smelting process is stable, and the requirement of the steel grade and the constraint condition of a production line are combined. On the premise that the quality is not affected, nickel element alloying is achieved in the converter by using nickel-containing pig iron under boundary constraint, innovative burdening, charging and smelting processes are matched, and metal nickel resources are saved.

Description

Technical Field

[0001] The invention relates to the technical field of steel smelting, and in particular to a method for alloying nickel-containing pig iron in a converter furnace. Background Art

[0002] Nickel and iron elements can form an infinite solid solution, increase the A4 point, reduce the A3 point, and expand the austenite zone of iron; in stainless steel and stainless heat-resistant steel, nickel is properly matched with chromium, molybdenum and other elements to obtain a series of stainless steel products; nickel can also reduce the critical transition temperature and the diffusion rate of each element in steel, and improve the hardenability of steel; Ni is an element with a certain corrosion resistance to acid, alkali, salt and atmosphere, so low-alloy steel containing nickel has a higher corrosion fatigue resistance; Ni can refine ferrite grains, significantly reduce the low-temperature brittle transition temperature, and significantly improve low-temperature impact toughness; therefore, Ni elements are widely used in materials such as stainless steel, weathering steel, high-strength welding wire and heat-resistant steel. However, due to the scarcity of Ni resources and the high energy consumption and environmental pollution of electrolytic nickel production, the price of metal nickel (electrolytic nickel) is high, and the production cost of Ni-containing steel is relatively high.

[0003] The manufacturing cost of the steel smelting process is directly related to the benefits of steel companies. It is mainly composed of alloys, iron-containing raw materials, flux and energy media, and alloy costs are one of the important components of steelmaking costs. In recent years, the steel industry has encountered severe challenges, with declining demand and prices continuing to fall. Reducing steelmaking processing costs has become the primary task for steel companies to survive, and reducing alloy costs is very important.

[0004] To solve the above problems, the present invention provides a method for alloying nickel-containing pig iron in a converter furnace. Combined with the requirements of steel grades and production line constraints, nickel-containing pig iron is used in the converter furnace under boundary constraints without affecting the quality, and the nickel element is alloyed, and supporting innovative batching, charging and smelting processes are used to save metal nickel resources and reduce costs.

[0005] The Chinese invention patent "A method for smelting ultra-low phosphorus stainless steel mother liquor" (application number: CN202311495898.X) involves the cost-reducing alloying of nickel-containing pig iron, which mainly includes: melting high-phosphorus nickel pig iron in a medium-frequency furnace, with a tapping temperature of 1500℃~1550℃, a power of 14000~16000kwh, and a tapping volume of 30~35 tons; adding high-phosphorus nickel pig iron water into an AOD furnace to smelt ultra-low phosphorus stainless steel mother liquor, with an oxygen flow rate of 4000~4500m3 / h and a nitrogen flow rate of 600~1000m3 / h. During the process, 10% high-phosphorus nickel pig iron is added to the cold-pressed steel. During the smelting process, 2 to 4 tons of lime are added in batches for slag making, and the target basicity is controlled at 4.0 to 5.0; when the oxygen blowing reaches 1000 to 1500m3 and the temperature is at 1550 to 1600℃, stop blowing oxygen, add 500 to 800kg of fluorite to adjust the fluidity of the slag, and blow at a nitrogen flow rate of 1000m3 / h for 5 to 8 minutes before slagging; when the slagging amount is greater than 95%, add 200 to 300kg of ferrosilicon into the high-level silo for deoxidation and reduction, with a target silicon content of 0.2%, blow at a nitrogen flow rate of 1000m3 / h for 5 to 8 minutes, and control the phosphorus return target to be less than 10ppm. The invention mainly heats and melts high-phosphorus nickel pig iron to 1500℃~1550℃ in a medium frequency furnace and then adds it into an AOD furnace, adding some cold nickel pig iron for smelting. The proportion of nickel pig iron directly used in the steelmaking furnace is low (accounting for 10% of the liquid high-temperature metal material), the power consumption is high (the medium frequency furnace is mainly used for electric heating and melting), and the pollution is large. The amount of nickel pig iron added in the present invention can reach 270kg / t steel (accounting for 33% of the liquid iron).

[0006] A novelty search was conducted on Chinese patents, Chinese scientific research papers, foreign patent documents and public publications, and no other prior art that is identical or similar to the invention content was found. Summary of the invention

[0007] 1. Technical issues to be solved

[0008] In view of the deficiencies in the prior art, the present invention provides a method for alloying nickel-containing pig iron in a converter furnace, which solves the problems existing in the prior art.

[0009] (II) Technical solution

[0010] To achieve the above objectives, the present invention is implemented by the following technical scheme: a method for alloying nickel-containing pig iron in a converter furnace, characterized in that the specific operations are as follows:

[0011] S1. Calculate the cost reduction of nickel-containing pig iron alloying. The specific situation is as follows:

[0012] The relative cost reduction is calculated based on nickel-containing pig iron, metallic nickel content and pig iron price. The calculation process is as follows:

[0013] Taking the addition of 0.010% Ni element to molten steel as the standard, the demand for nickel pig iron is calculated according to formula (1), and the unit relative cost reduction is calculated according to formula (3).

[0014]

[0015] When adding 0.010% elemental nickel to molten steel, the corresponding amount of nickel pig iron and metallic nickel is required, kg (furnace consumption);

[0016] WS is the amount of molten steel, t;

[0017] Nickel content in nickel pig iron, %;

[0018] Recovery rate of nickel element in nickel pig iron, %;

[0019] The content of nickel in metallic nickel, %;

[0020] Recovery rate of nickel in metallic nickel, %;

[0021] C 1 When 0.010% nickel is added to molten steel, the relative cost reduction is RMB;

[0022] Pig iron content in nickel pig iron, %;

[0023] C Ni-Fe , nickel pig iron price, yuan / kg;

[0024] C Iron , pig iron price, yuan / kg;

[0025] C Ni-M , nickel metal price, yuan / kg;

[0026] S2. Target composition setting: Set the target composition of nickel alloying in the furnace according to the steel grade composition

[0027]

[0028] S3, control boundary, the details are as follows:

[0029] The calculation of sulfur and chromium boundary control is as follows:

[0030]

[0031] Chromium addition, %;

[0032] Ni aim Nickel target value for alloying with nickel-iron, %;

[0033] Converter chromium recovery rate, %;

[0034] Chromium content of nickel pig iron, %;

[0035] W S Molten steel volume, t;

[0036] Sulfur load of converter inlet, %;

[0037] Sulfur content of nickel pig iron, %;

[0038] Initial sulfur content of molten iron (without desulfurization treatment), %;

[0039] Converter limit sulfur load, %;

[0040] Converter desulfurization rate, %;

[0041] Refining desulfurization rate, %;

[0042] Desulfurization amount of molten iron, %;

[0043] Hot metal desulfurization rate, %;

[0044] ΔS sulfur load difference, %;

[0045] S4. Coordinated adjustment of the target nickel composition in the furnace. The specific operations are as follows:

[0046] In calculation (3), calculate like (finished product target value), the nickel alloy target of step (2) is adjusted for the first time; the adjusted target value is Adjust the target according to the first And calculate ΔS according to formula (6) and formula (8);

[0047] In calculation (3), calculate like (finished product target value), Calculate ΔS according to equation (6) and equation (8).

[0048] 5. Coordinated adjustment of hot metal desulfurization treatment and target nickel composition in the furnace

[0049] In calculation (4), if ΔS < 0, the molten iron does not need to be desulfurized, and the target nickel composition in the furnace is the target corresponding to the conditions in step (4);

[0050] like Desulfurization treatment, the target nickel composition in the furnace is the target corresponding to the conditions in step (4);

[0051] like Hot metal desulfurization and nickel alloy target adjustment, nickel alloy target value As shown in formula (10), the target Ni before adjustment is aim is the corresponding target under the condition of calculation (4):

[0052]

[0053] The target sulfur content of the above molten iron that needs to be desulfurized after desulfurization is:

[0054]

[0055] The target nickel composition in the furnace in formula (11) is the final target corresponding to the conditions of steps (3) and (4).

[0056] 6. Ingredients

[0057] The nickel alloy target is prepared according to step (5). If nickel pig iron is prepared with scrap steel in the same scrap steel tank, the nickel pig iron should be placed in the rear of the scrap steel tank.

[0058]

[0059] Nickel pig iron batching quantity, kg;

[0060] S5, charging. Before adding nickel pig iron, the slag in the furnace should be splashed dry; the order of charging into the furnace is: scrap steel - nickel pig iron - molten iron;

[0061] S6, converter smelting, the details are as follows:

[0062] Gun position control

[0063] The converter oxygen supply adopts the operation mode of staged constant flow and variable gun position. The gun position and oxygen supply intensity are controlled as follows:

[0064] When the oxygen supply is the total amount (0, 8%), the gun position is 1.15×(40~50)×D throat; if the primary dust removal is dry dust removal, the oxygen supply intensity is 1.8~2.5m3 / (min.t); if it is a wet dust removal system, the oxygen supply intensity is 3.2~4.0m3 / (min.t);

[0065] When the oxygen supply is the total amount (8.0%, 30%), the gun position is 1.15×(31~35.5)×D throat; the oxygen supply intensity is 3.2~4.0m3 / (min.t);

[0066] When the oxygen supply is the total amount (30%, 61%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0067] When the oxygen supply is the total amount (61%, 78%), the gun position is 1.15×(40~50)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0068] When the oxygen supply is the total amount (78%, 85%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0069] When the oxygen supply is the total amount (85%, 100%), the gun position is 1.15×(30~35)×D throat; the oxygen supply intensity is 3.5~4.5m3 / (min.t);

[0070] The Dthroat is the diameter of the oxygen lance nozzle throat, mm;

[0071] Adding materials

[0072] When the oxygen supply is the total amount (6, 12%], add the material to (50%, 70];

[0073] When the oxygen supply is the total amount (15, 21%], add the material to (75%, 90];

[0074] When the oxygen supply reaches the total amount (21, 40%), add the remaining slag;

[0075] Bottom blowing intensity. Before oxygen supply 85%, the bottom blowing intensity is 0.04~0.15m3 / (min.t). After oxygen supply (85, 100%], the bottom blowing intensity is 0.08~0.20m3 / (min.t);

[0076] The final temperature of the converter is >1570℃;

[0077] S7. Adjustment of nickel content after steel tapping, the details are as follows:

[0078] After steel is tapped, nickel is adjusted to the target value based on the test results.

[0079] The chemical composition and mass percentage of nickel-containing pig iron are Ni: 7.0-13.0%, C: 0.50-3.50%, Si: 0.20-2.0%, P≤0.130%, S: ≤0.30%, Cr≤2.50%, and the rest are Fe element and unavoidable impurities.

[0080] The amount of nickel-containing pig iron added shall not exceed 270kg / t steel.

[0081] The chemical composition and mass percentage of metal nickel are: Ni>99.5%, P≤0.10%, S:≤0.10%, Al≤0.50%, and the rest are unavoidable impurities;

[0082] The target composition of nickel alloying in the furnace needs to be adjusted according to the boundary conditions of step (3). Preferably, the target composition of nickel alloying in the furnace is at least 0.03% lower than the target composition of the finished product, and nickel pig iron is used as much as possible for nickel alloying in the furnace.

[0083] The relevant parameter settings are based on the production line equipment and technical capabilities, and the range is as follows:

[0084] The converter chromium recovery rate is 10%-50%, and the lower limit is taken when the converter end carbon content is less than 0.05, and the upper limit is taken when the carbon content is greater than 0.15%;

[0085] Converter desulfurization rate, 30%-65%;

[0086] Refining desulfurization rate, 50%-85%;

[0087] Hot metal desulfurization rate: 80%-98%;

[0088] Converter chromium recovery rate, 20%-50%

[0089] If desulfurization is carried out under the corresponding target under the conditions of step (5): when

[0090] If desulfurization is not performed, the batching is performed under the corresponding target under the conditions of step (5):

[0091] The silicon content of the molten iron is not more than 0.80%;

[0092] During the smelting process, no slag is dumped in the early stage;

[0093] The nickel composition adjustment after steel tapping is preferably performed in the refining process according to the target composition of the finished product.

[0094] (III) Beneficial effects

[0095] The present invention provides a method for alloying nickel-containing pig iron in a converter furnace. It has the following beneficial effects:

[0096] The method for alloying nickel-containing pig iron in a converter furnace provides a relative cost calculation method based on the sulfur load, and on this basis invents a preferred calculation method under boundary conditions, which mainly includes batching, charging and smelting control. The amount of nickel-containing pig iron added can reach 270kg / t of steel, and the smelting process is stable. Combined with the steel grade requirements and production line constraints, nickel-containing pig iron is used in the converter furnace under boundary constraints without affecting the quality, and the nickel element is alloyed. Innovative batching, charging and smelting processes are used to save metal nickel resources and significantly reduce costs. DETAILED DESCRIPTION

[0097] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in 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. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0098] The present invention provides a technical solution: a method for alloying nickel-containing pig iron in a converter furnace, characterized in that the specific operations are as follows:

[0099] S1. Calculate the cost reduction of nickel-containing pig iron alloying. The specific situation is as follows:

[0100] The relative cost reduction is calculated based on nickel-containing pig iron, metallic nickel content and pig iron price. The calculation process is as follows:

[0101] Taking the addition of 0.010% Ni element to molten steel as the standard, the demand for nickel pig iron is calculated according to formula (1), and the unit relative cost reduction is calculated according to formula (3).

[0102]

[0103] When adding 0.010% elemental nickel to molten steel, the corresponding amount of nickel pig iron and metallic nickel is required, kg (furnace consumption);

[0104] WS is the amount of molten steel, t;

[0105] Nickel content in nickel pig iron, %;

[0106] Recovery rate of nickel element in nickel pig iron, %;

[0107] The content of nickel in metallic nickel, %;

[0108] Recovery rate of nickel in metallic nickel, %;

[0109] C 1 When 0.010% nickel is added to molten steel, the relative cost reduction is RMB;

[0110] Pig iron content in nickel pig iron, %;

[0111] C Ni-Fe , nickel pig iron price, yuan / kg;

[0112] C Iron , pig iron price, yuan / kg;

[0113] CNi-M , nickel metal price, yuan / kg;

[0114] S2. Target composition setting: Set the target composition of nickel alloying in the furnace according to the steel grade composition

[0115]

[0116] S3, control boundary, the details are as follows:

[0117] The calculation of sulfur and chromium boundary control is as follows:

[0118]

[0119] Chromium addition, %;

[0120] Ni aim Nickel target value for alloying with nickel-iron, %;

[0121] Converter chromium recovery rate, %;

[0122] Chromium content of nickel pig iron, %;

[0123] W S Molten steel volume, t;

[0124] Sulfur load of converter inlet, %;

[0125] Sulfur content of nickel pig iron, %;

[0126] Initial sulfur content of molten iron (without desulfurization treatment), %;

[0127] Converter limit sulfur load, %;

[0128] Converter desulfurization rate, %;

[0129] Refining desulfurization rate, %;

[0130] Desulfurization amount of molten iron, %;

[0131] Hot metal desulfurization rate, %;

[0132] ΔS sulfur load difference, %;

[0133] S4. Coordinated adjustment of the target nickel composition in the furnace. The specific operations are as follows:

[0134] In calculation (3), calculate like (finished product target value), the nickel alloy target of step (2) is adjusted for the first time; the adjusted target value is Adjust the target based on the first And calculate ΔS according to formula (6) and formula (8);

[0135] In calculation (3), calculate like (finished product target value), Calculate ΔS according to equation (6) and equation (8).

[0136] 5. Coordinated adjustment of hot metal desulfurization treatment and target nickel composition in the furnace

[0137] In calculation (4), if ΔS < 0, the molten iron does not need to be desulfurized, and the target nickel composition in the furnace is the target corresponding to the conditions in step (4);

[0138] like Desulfurization treatment, the target nickel composition in the furnace is the target corresponding to the conditions in step (4);

[0139] like Hot metal desulfurization and nickel alloy target adjustment, nickel alloy target value As shown in formula (10), the target Ni before adjustment is aim is the corresponding target under the condition of calculation (4):

[0140]

[0141] The target sulfur content of the above molten iron that needs to be desulfurized after desulfurization is:

[0142]

[0143] The target nickel composition in the furnace in formula (11) is the final target corresponding to the conditions of steps (3) and (4).

[0144] 6. Ingredients

[0145] The nickel alloy target is prepared according to step (5). If nickel pig iron is prepared with scrap steel in the same scrap steel tank, the nickel pig iron should be placed in the rear of the scrap steel tank.

[0146]

[0147] Nickel pig iron batching quantity, kg;

[0148] S5, charging. Before adding nickel pig iron, the slag in the furnace should be splashed dry; the order of charging into the furnace is: scrap steel - nickel pig iron - molten iron;

[0149] S6, converter smelting, the details are as follows:

[0150] Gun position control

[0151] The converter oxygen supply adopts the operation mode of staged constant flow and variable gun position. The gun position and oxygen supply intensity are controlled as follows:

[0152] When the oxygen supply is the total amount (0, 8%), the gun position is 1.15×(40~50)×D throat; if the primary dust removal is dry dust removal, the oxygen supply intensity is 1.8~2.5m3 / (min.t); if it is a wet dust removal system, the oxygen supply intensity is 3.2~4.0m3 / (min.t);

[0153] When the oxygen supply is the total amount (8.0%, 30%), the gun position is 1.15×(31~35.5)×D throat; the oxygen supply intensity is 3.2~4.0m3 / (min.t);

[0154] When the oxygen supply is the total amount (30%, 61%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0155] When the oxygen supply is the total amount (61%, 78%), the gun position is 1.15×(40~50)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0156] When the oxygen supply is the total amount (78%, 85%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0157] When the oxygen supply is the total amount (85%, 100%), the gun position is 1.15×(30~35)×D throat; the oxygen supply intensity is 3.5~4.5m3 / (min.t);

[0158] The Dthroat is the diameter of the oxygen lance nozzle throat, mm;

[0159] Adding materials

[0160] When the oxygen supply is the total amount (6, 12%], add the material to (50%, 70];

[0161] When the oxygen supply is the total amount (15, 21%], add the material to (75%, 90];

[0162] When the oxygen supply reaches the total amount (21, 40%), add the remaining slag;

[0163] Bottom blowing intensity. Before oxygen supply 85%, the bottom blowing intensity is 0.04~0.15m3 / (min.t). After oxygen supply (85, 100%], the bottom blowing intensity is 0.08~0.20m3 / (min.t);

[0164] The final temperature of the converter is >1570℃;

[0165] S7. Adjustment of nickel content after steel tapping, the details are as follows:

[0166] After steel is tapped, nickel is adjusted to the target value based on the test results.

[0167] The chemical composition and mass percentage of nickel-containing pig iron are Ni: 7.0-13.0%, C: 0.50-3.50%, Si: 0.20-2.0%, P≤0.130%, S: ≤0.30%, Cr≤2.50%, and the rest are Fe element and unavoidable impurities.

[0168] The amount of nickel-containing pig iron added shall not exceed 270kg / t steel.

[0169] The chemical composition and mass percentage of metal nickel are: Ni>99.5%, P≤0.10%, S:≤0.10%, Al≤0.50%, and the rest are unavoidable impurities;

[0170] The target composition of nickel alloying in the furnace needs to be adjusted according to the boundary conditions of step (3). Preferably, the target composition of nickel alloying in the furnace is at least 0.03% lower than the target composition of the finished product, and nickel pig iron is used as much as possible for nickel alloying in the furnace.

[0171] The relevant parameter settings are based on the production line equipment and technical capabilities, and the range is as follows:

[0172] The converter chromium recovery rate is 10%-50%, and the lower limit is taken when the converter end carbon content is less than 0.05, and the upper limit is taken when the carbon content is greater than 0.15%;

[0173] Converter desulfurization rate, 30%-65%;

[0174] Refining desulfurization rate, 50%-85%;

[0175] Hot metal desulfurization rate: 80%-98%;

[0176] Converter chromium recovery rate, 20%-50%

[0177] If desulfurization is carried out under the corresponding target under the conditions of step (5): when

[0178] If desulfurization is not performed, the batching is performed under the corresponding target under the conditions of step (5):

[0179] The silicon content of the molten iron is not more than 0.80%;

[0180] During the smelting process, no slag is dumped in the early stage;

[0181] The nickel composition adjustment after steel tapping is preferably performed in the refining process according to the target composition of the finished product.

[0182] Example:

[0183] Example 1

[0184] A method for alloying 150t nickel-containing pig iron in a converter is as follows:

[0185] A method for alloying nickel-containing pig iron in a 150t converter. In this embodiment, the converter is a 150t top and bottom double-blown converter. Taking the smelting of low-temperature steel bars for the construction of LNG storage tanks as an example, the bottom-blown gas for converter smelting is argon, and the target composition of steel is as follows: C: 0.08%, Si: 0.30%, Mn: 1.55%, P≤0.007%, S≤0.005%, Ni: 1.05%, V: 0.08%, Als: 0.028%, Cr≤0.30%, Cu≤0.30%, [H]≤1.5ppm, [N]: 65ppm; the remainder is Fe and unavoidable impurities. The specific operation is as follows:

[0186] 1. Calculation of cost reduction of nickel-containing pig iron alloying

[0187] The relative cost reduction is calculated based on nickel-containing pig iron, metallic nickel content and pig iron price. The calculation process is as follows:

[0188] Taking the addition of 0.010% Ni element to molten steel as the standard, the demand for nickel pig iron is calculated according to formula (1), and the unit relative cost reduction is calculated according to formula (3).

[0189]

[0190] When adding 0.010% elemental nickel to molten steel, the corresponding amount of nickel pig iron and metallic nickel is required, kg (furnace consumption);

[0191] W S is the target molten steel volume, t;

[0192] Nickel content in nickel pig iron, %;

[0193] Recovery rate of nickel element in nickel pig iron, %;

[0194] The content of nickel in metallic nickel, %;

[0195] Recovery rate of nickel in metallic nickel, %;

[0196] C 1 When 0.010% nickel is added to molten steel, the relative cost reduction is RMB;

[0197] Pig iron content in nickel pig iron, %;

[0198] C Ni-Fe , nickel pig iron price, yuan / kg;

[0199] C Iron , pig iron price, yuan / kg;

[0200] C Ni-M , metal nickel price, yuan / kg.

[0201] Test results:

[0202] The chemical composition and mass percentage of nickel-containing pig iron are Ni: 10.60%, C: 2.15%, Si: 0.52%, P0.06%, S: 0.25%, Cr1.8%, and the rest are Fe element and inevitable impurities.

[0203] The chemical composition and mass percentage of metallic nickel are: Ni>99.95%, P 0.001%, S: 0.001%, Al 0.046%, and the rest are unavoidable impurities.

[0204] Table 1 Main parameters of formula (1)-(4)

[0205]

[0206] Table 2 Calculation results of formulas (1)-(4)

[0207]

[0208]

[0209] 2. Target ingredient setting

[0210] Set the target composition of nickel alloying in the furnace according to the steel grade composition Cr aim ≤0.30%, S aim It is 0.0040%.

[0211] 3. Border Control

[0212] The calculation of sulfur and chromium boundary control is as follows:

[0213]

[0214] Chromium addition, %;

[0215] Ni aim Nickel target value for alloying with nickel-iron, %;

[0216] Converter chromium recovery rate, %;

[0217] Chromium content of nickel pig iron, %;

[0218] WS Molten steel volume, t;

[0219] Sulfur load of converter, %;

[0220] Sulfur content of nickel pig iron, %;

[0221] Initial sulfur content of molten iron (without desulfurization treatment), %;

[0222] Converter limit sulfur load, %;

[0223] Converter desulfurization rate;

[0224] Refining desulfurization rate;

[0225] Desulfurization of hot metal, %;

[0226] Hot metal desulfurization rate, %;

[0227] ΔS sulfur load difference, %;

[0228] Table 3 Main parameters of formula (5)-(9)

[0229]

[0230] The calculation results of formulas (5)-(9) of this embodiment are shown in Table 4, and the composition of molten iron is shown in Table 5.

[0231] Table 4 Calculation results of formulas (5)-(9)

[0232]

[0233]

[0234] Table 5 Molten Iron Composition

[0235] Hot metal (undesulfurized) S％ Si% Heat 1 0.017％ 0.48％ Heat 2 0.028％ 0.31％ Heat 3 0.075％ 0.23％

[0236] 4. Coordinated adjustment of nickel target composition in the furnace

[0237] Step (3) Calculation like (finished product target value), the nickel alloy target of step (2) is adjusted for the first time; the adjusted target value is Adjust the target based on the first And calculate ΔS according to formula (6) and formula (8);

[0238] Step (3) Calculation like (finished product target value), Calculate ΔS according to formula (6) and formula (8);

[0239] In this embodiment (finished product target value ≤ 0.30%), ΔS is calculated according to equation (6) and equation (8). The results are shown in Table 4.

[0240] 5. Coordinated adjustment of hot metal desulfurization treatment and target nickel composition in the furnace

[0241] In step (4), if ΔS < 0, the molten iron does not need to be desulfurized, and the target nickel composition in the furnace is the target corresponding to the conditions in step (4);

[0242] like Desulfurization treatment, the target nickel composition in the furnace is the target corresponding to the conditions in step (4);

[0243] like Hot metal desulfurization and nickel alloy target adjustment, nickel alloy target value As shown in formula (10), the target Ni before adjustment is aim is the target corresponding to the condition in step (4):

[0244]

[0245] The target sulfur content of the above molten iron that needs to be desulfurized after desulfurization is:

[0246]

[0247]

[0248] The target nickel composition in the furnace in formula (11) is the final target corresponding to the conditions of steps (3) and (4).

[0249] In this embodiment, ΔS, (Right now ) The calculation results are shown in Table 4. Heat 1 and Heat 2 meet the requirements. Desulfurization treatment, the target nickel composition in the furnace is the target corresponding to the conditions of step (4) (i.e. 1.0%); Heat 3 meets the requirements The molten iron is desulfurized and the nickel alloy target is adjusted. The target Ni before adjustment aim is the target corresponding to the condition in step (4) (i.e. 1.0%), and according to formula (10) we can get:

[0250] That is, the nickel target for Heat 3 is adjusted to 0.892%.

[0251] Table 6 Target sulfur content of hot metal desulfurization (calculated according to formula 11) and desulfurization performance

[0252]

[0253] Desulfurization cost = 15 yuan / ton * 157 tons = 2355 yuan, the minimum cost saving

[0254] =10000*0.892%*828.867=73934.94 yuan, you can add ingredients.

[0255] 6. Ingredients

[0256] The nickel alloy target is prepared according to step (5). If nickel pig iron is prepared with scrap steel in the same scrap steel tank, the nickel pig iron should be placed in the rear of the scrap steel tank.

[0257]

[0258] Nickel pig iron batching quantity, kg;

[0259] Table 7 Target nickel pig iron batching (calculated according to formula 12) and actual performance

[0260]

[0261]

[0262] Desulfurization cost = 15*157 = 2355 yuan, minimum cost saving

[0263] =10000*0.892%*828.867=73934.94 yuan, you can add ingredients.

[0264] 7. Add ingredients

[0265] Before adding nickel pig iron, the slag in the furnace should be splashed dry; the order of adding materials into the furnace is: scrap steel - nickel pig iron - molten iron.

[0266] 8. Converter smelting

[0267] (1) Gun position control

[0268] The converter oxygen supply adopts the operation mode of staged constant flow and variable gun position. The gun position and oxygen supply intensity are controlled as follows:

[0269] When the oxygen supply is the total amount (0, 8%), the gun position is 1.15×(40~50)×D throat; if the primary dust removal is dry dust removal, the oxygen supply intensity is 1.8~2.5m3 / (min.t); if it is a wet dust removal system, the oxygen supply intensity is 3.2~4.0m3 / (min.t);

[0270] When the oxygen supply is the total amount (8.0%, 30%), the gun position is 1.15×(31~35.5)×D throat; the oxygen supply intensity is 3.2~4.0m3 / (min.t);

[0271] When the oxygen supply is the total amount (30%, 61%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0272] When the oxygen supply is the total amount (61%, 78%), the gun position is 1.15×(40~50)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0273] When the oxygen supply is the total amount (78%, 85%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t);

[0274] When the oxygen supply is the total amount (85%, 100%), the gun position is 1.15×(30~35)×D throat; the oxygen supply intensity is 3.5~4.5m3 / (min.t);

[0275] The Dthroat is the diameter of the oxygen lance nozzle throat, mm;

[0276] The diameter of the throat of the oxygen lance nozzle in the embodiment is 39.3 mm, and the primary dust removal is dry dust removal.

[0277] Table 8 Gun position and oxygen supply intensity control

[0278]

[0279]

[0280] (2) Adding materials

[0281] When the oxygen supply is the total amount (6, 12%], add the material to (50%, 70];

[0282] When the oxygen supply is the total amount (15, 21%], add the material to (75%, 90];

[0283] When the oxygen supply reaches the total amount (21, 40%), add the remaining slag.

[0284] Table 9 Feeding Control

[0285]

[0286] (3) Bottom blowing intensity. Bottom blowing intensity before oxygen supply 85% is 0.04~0.15m 3 / (min.t). Oxygen supply (85, 100%], bottom blowing intensity 0.08~0.20m 3 / (min.t).

[0287] Table 10 Bottom blowing control

[0288]

[0289]

[0290] (4) The final temperature of the converter is greater than 1570°C.

[0291] Table 11 Converter end temperature

[0292]

[0293] 9. Adjustment of nickel content after steelmaking

[0294] After steel is tapped, nickel is adjusted to the target value based on the test results.

[0295] Table 12 Composition after steel tapping (before adjustment)

[0296]

[0297] Table 13 Composition after refining

[0298]

[0299]

[0300] The chemical composition and mass percentage of the nickel-containing pig iron in step (1) are Ni: 7.0-13.0%, C: 0.50-3.50%, Si: 0.20-2.0%, P≤0.130%, S:≤0.30%, Cr≤2.50%, and the rest are Fe element and unavoidable impurities.

[0301] The amount of nickel-containing pig iron added in step (1) is not more than 270 kg / t steel.

[0302] The chemical composition and mass percentage of the metal nickel in step (1) are: Ni>99.5%, P≤0.10%, S:≤0.10%, Al≤0.50%, and the rest are unavoidable impurities.

[0303] The target composition of nickel alloying in the furnace in step (2) needs to be adjusted according to the boundary conditions of step (3). Preferably, the target composition of nickel alloying in the furnace is at least 0.03% lower than the target composition of the finished product and nickel pig iron is used as much as possible for nickel alloying in the furnace.

[0304] In step (3), the relevant parameters are set according to the production line equipment and technical capabilities, and the range is as follows:

[0305] The converter chromium recovery rate is 10%-50%, and the lower limit is taken when the converter end carbon content is less than 0.05, and the upper limit is taken when the carbon content is greater than 0.15%;

[0306] Converter desulfurization rate, 30%-65%;

[0307] Refining desulfurization rate, 50%-85%;

[0308] Hot metal desulfurization rate: 80%-98%;

[0309] Converter chromium recovery rate, 20%-50%.

[0310] In step (5), if desulfurization is performed, the target Ni corresponding to the conditions of step (5) is aim Lower: 10000×Ni aim ×C 1 > When the furnace desulfurization cost is increased, the ingredients are batched;

[0311] In step (5), if desulfurization is not performed, the target Ni aim Lower: 10000×Ni aim ×C 1 >0, batching;

[0312] The silicon content of the molten iron in step (7) is not more than 0.80%;

[0313] In step (8), during the smelting process, no slag is dumped in the early stage;

[0314] The nickel composition adjustment after steelmaking in step (9) is preferably carried out in the refining process according to the target composition of the finished product.

[0315] In summary, the method for alloying nickel-containing pig iron in the converter furnace provides a relative cost calculation method based on the sulfur load. On this basis, a preferred calculation method under boundary conditions is invented, which mainly includes batching, charging and smelting control. The amount of nickel-containing pig iron added can reach 270kg / t steel, and the smelting process is stable. Combined with the steel grade requirements and production line constraints, nickel-containing pig iron is used in the converter furnace under boundary constraints without affecting the quality. Nickel alloying is achieved, and supporting innovative batching, charging and smelting processes are used to save metal nickel resources and significantly reduce costs.

[0316] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0317] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for alloying nickel-containing pig iron in a converter furnace, characterized in that: The specific operations are as follows: S1. Calculate the cost reduction of nickel-containing pig iron alloying. The specific situation is as follows: The relative cost reduction is calculated based on nickel-containing pig iron, metallic nickel content and pig iron price. The calculation process is as follows: Taking the increase of 0.010% Ni element in molten steel as the standard, the demand for nickel pig iron is calculated according to formula (1), and the unit relative cost reduction is calculated according to formula (3); When adding 0.010% elemental nickel to molten steel, the corresponding amount of nickel pig iron and metallic nickel is required, kg (furnace consumption); WS is the amount of molten steel, t; Nickel content in nickel pig iron, %; Recovery rate of nickel element in nickel pig iron, %; The content of nickel in metallic nickel, %; Recovery rate of nickel in metallic nickel, %; C 1 When 0.010% nickel is added to molten steel, the relative cost reduction is RMB; Pig iron content in nickel pig iron, %; C Ni-Fe , nickel pig iron price, yuan / kg; C Iron , pig iron price, yuan / kg; C Ni-M , nickel metal price, yuan / kg; S2. Target composition setting: Set the target composition of nickel alloying in the furnace according to the steel grade composition S3, control boundary, the details are as follows: The calculation of sulfur and chromium boundary control is as follows: Chromium addition, %; Ni aim Nickel target value for alloying with nickel-iron, %; Converter chromium recovery rate, %; Chromium content of nickel pig iron, %; W S Molten steel volume, t; Sulfur load of converter inlet, %; Sulfur content of nickel pig iron, %; Initial sulfur content of molten iron (without desulfurization treatment), %; Converter limit sulfur load, %; Converter desulfurization rate, %; Refining desulfurization rate, %; Desulfurization amount of molten iron, %; Hot metal desulfurization rate, %; ΔS sulfur load difference, %; S4. Coordinated adjustment of the target nickel composition in the furnace. The specific operations are as follows: In calculation (3), calculate like (finished product target value), the nickel alloy target of step (2) is adjusted for the first time; the adjusted target value is Adjust the target according to the first And calculate ΔS according to formula (6) and formula (8); In calculation (3), calculate like (finished product target value), Calculate ΔS according to formula (6) and formula (8); Coordinated adjustment of hot metal desulfurization treatment and target nickel composition in the furnace In calculation (4), if ΔS < 0, the molten iron does not need to be desulfurized, and the target nickel composition in the furnace is the target corresponding to the conditions in step (4); like Desulfurization treatment, the target nickel composition in the furnace is the target corresponding to the conditions in step (4); like Hot metal desulfurization and nickel alloy target adjustment, nickel alloy target value As shown in formula (10), the target Ni before adjustment is aim is the corresponding target under the condition of calculation (4): The target sulfur content of the above molten iron that needs to be desulfurized after desulfurization is: The target nickel composition in the furnace in formula (11) is the final target corresponding to the conditions in steps (3) and (4); Ingredients According to the nickel alloy target of step (5), if nickel pig iron is mixed with scrap steel in the same scrap steel tank, the nickel pig iron should be placed in the rear part of the scrap steel tank; Nickel pig iron batching amount, kg; S5, charging. Before adding nickel pig iron, the slag in the furnace should be splashed dry; the order of charging into the furnace is: scrap steel - nickel pig iron - molten iron; S6, converter smelting, the details are as follows: Gun position control The converter oxygen supply adopts the operation mode of staged constant flow and variable gun position. The gun position and oxygen supply intensity are controlled as follows: When the oxygen supply is the total amount (0, 8%), the gun position is 1.15×(40~50)×D throat; if the primary dust removal is dry dust removal, the oxygen supply intensity is 1.8~2.5m3 / (min.t); if it is a wet dust removal system, the oxygen supply intensity is 3.2~4.0m3 / (min.t); When the oxygen supply is the total amount (8.0%, 30%), the gun position is 1.15×(31~35.5)×D throat; the oxygen supply intensity is 3.2~4.0m3 / (min.t); When the oxygen supply is the total amount (30%, 61%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t); When the oxygen supply is the total amount (61%, 78%), the gun position is 1.15×(40~50)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t); When the oxygen supply is the total amount (78%, 85%), the gun position is 1.15×(36~40)×D throat; the oxygen supply intensity is 3.0~3.5m3 / (min.t); When the oxygen supply is the total amount (85%, 100%), the gun position is 1.15×(30~35)×D throat; the oxygen supply intensity is 3.5~4.5m3 / (min.t); The Dthroat is the diameter of the oxygen lance nozzle throat, mm; Adding materials When the oxygen supply is the total amount (6, 12%], add the material to (50%, 70]; When the oxygen supply is the total amount (15, 21%], add the material to (75%, 90]; When the oxygen supply reaches the total amount (21, 40%), add the remaining slag; Bottom blowing intensity: before oxygen supply 85%, the bottom blowing intensity is 0.04~0.15m3 / (min.t); when oxygen supply (85, 100%), the bottom blowing intensity is 0.08~0.20m3 / (min.t); The final temperature of the converter is >1570℃; S7. Adjustment of nickel content after steel tapping, the details are as follows: After steel is tapped, nickel is adjusted to the target value based on the test results; The chemical composition and mass percentage of nickel-containing pig iron are Ni: 7.0-13.0%, C: 0.50-3.50%, Si: 0.20-2.0%, P≤0.130%, S:≤0.30%, Cr≤2.50%, and the rest are Fe element and unavoidable impurities; The amount of nickel-containing pig iron added shall not exceed 270kg / t steel; The chemical composition and mass percentage of metal nickel are: Ni>99.5%, P≤0.10%, S:≤0.10%, Al≤0.50%, and the rest are unavoidable impurities; The target composition of nickel alloying in the furnace needs to be adjusted according to the boundary conditions of step (3). Preferably, the target composition of nickel alloying in the furnace is at least 0.03% lower than the target composition of the finished product, and nickel pig iron is used as much as possible for nickel alloying in the furnace. The relevant parameter settings are based on the production line equipment and technical capabilities, and the range is as follows: The converter chromium recovery rate is 10%-50%, and the lower limit is taken when the converter end carbon content is less than 0.05, and the upper limit is taken when the carbon content is greater than 0.15%; Converter desulfurization rate, 30%-65%; Refining desulfurization rate, 50%-85%; Hot metal desulfurization rate: 80%-98%; Converter chromium recovery rate, 20%-50% If desulfurization is carried out under the corresponding target under the conditions of step (5): when If desulfurization is not performed, the batching is performed under the corresponding target under the conditions of step (5): The silicon content of the molten iron is not more than 0.80%; During the smelting process, no slag is dumped in the early stage; The nickel composition adjustment after steel tapping is preferably performed in the refining process according to the target composition of the finished product.

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