Method for smelting nickel-containing molten steel in converter and nickel-containing molten steel

Abstract

The present application discloses a method for smelting nickel-containing molten steel in a converter and the nickel-containing molten steel. The method comprises: adding a nickel-containing alloy or nickel element to molten iron, supplying oxygen to the molten iron using an oxygen lance, and adding a calcium-containing flux in batches, wherein the oxygen lance is positioned at 150-240 cm and the oxygen flow rate is 700-900 Nm 3 / min, under the condition of oxygen supply as the first oxygen step, the oxygen gun position is controlled to 200-240cm, and the oxygen flow rate is 800-900Nm 3 / min; Under the condition of oxygen supply as the second oxygen step, the oxygen gun position is controlled to be 180-195cm, and the oxygen flow rate is 750-870Nm 3 / min; Under the condition of oxygen supply as the third oxygen step, the oxygen gun position is controlled to be 180-195cm, and the oxygen flow rate is 730-780Nm 3 / min; Under the condition of oxygen supply as the fourth oxygen step, the oxygen gun position is controlled to 180-190cm, and the oxygen flow rate is 730-870Nm 3 / min so that the final phosphorus content of the converter is <0.004%.

Description

Technical Field

[0001] The present application belongs to the technical field of steelmaking, and specifically relates to a method for smelting nickel-containing molten steel in a converter and the nickel-containing molten steel. Background Art

[0002] Conventional steelmaking processes include converter smelting, refining, continuous casting, etc. Existing converter smelting methods generally include duplex method, double slag method and single slag method.

[0003] Generally speaking, the production of low-phosphorus low-temperature pressure vessel steel mainly adopts the duplex method or double slag method, but its energy loss and iron loss are large, the smelting time is long, and the cost is relatively high; the single slag method only produces slag once from smelting to steelmaking, and the slag is used throughout. The single slag method in related technologies cannot effectively perform slag desulfurization and dephosphorization operations, and is generally used for the smelting of high-alloy steel and return materials. Summary of the Invention

[0004] In view of this, the present application provides a method for smelting nickel-containing molten steel in a converter and nickel-containing molten steel, aiming to provide a method for smelting steel in a converter with low phosphorus content, low energy loss and short smelting cycle.

[0005] In a first aspect, the present application provides a method for smelting nickel-containing molten steel in a converter, comprising:

[0006] Add nickel alloy or nickel element to the molten iron, use oxygen lance to supply oxygen to the molten iron, add calcium flux in batches, the oxygen lance position is 150-240cm, the oxygen flow rate is 700-900Nm 3 / min;

[0007] Under the condition of oxygen supply as the first oxygen step, the oxygen gun position is controlled to be 200-240cm and the oxygen flow rate is 800-900Nm 3 / min;

[0008] When oxygen is supplied as the second oxygen step, the oxygen lance position is controlled to be 180-195cm and the oxygen flow rate is 750-870Nm 3 / min;

[0009] When oxygen is supplied as the third oxygen step, the oxygen gun position is controlled to be 180-195cm and the oxygen flow rate is 730-780Nm 3 / min;

[0010] Under the condition of oxygen supply as the fourth oxygen step, the oxygen gun position is controlled to be 180-190cm and the oxygen flow rate is 730-870Nm 3 / min.

[0011] According to an embodiment of one aspect of the present application, the molten iron contains, in mass percentage: Si, 0.3%-0.5%, C, 4.0%-4.5%, Mn<0.35%, P≤0.090%, S≤0.002%, and the remainder is iron and unavoidable impurity elements; optionally, the temperature of the molten iron is ≥1290°C.

[0012] According to an embodiment of one aspect of the present application, between the second oxygen step and the third oxygen step, the method further includes: maintaining the oxygen flow rate in the second oxygen step and lowering the gun position in the second oxygen step.

[0013] According to an embodiment of one aspect of the present application, the first oxygen step is less than 8%.

[0014] According to an embodiment of one aspect of the present application, the second oxygen step is 8%-35%.

[0015] According to an embodiment of one aspect of the present application, the third oxygen step is 35%-65%.

[0016] According to an embodiment of one aspect of the present application, the fourth oxygen step is greater than 65%.

[0017] According to an embodiment of one aspect of the present application, calcium-containing flux is added in batches under the condition that the oxygen concentration is 8%-65%.

[0018] According to an embodiment of one aspect of the present application, in the second oxygen step, the gun position is 180-195 cm, and the oxygen flow rate is 750-870 Nm 3 / min, adding calcium-containing flux in batches, wherein the calcium-containing flux includes the first batch of flux, the second batch of flux, the third batch of flux, the fourth batch of flux and the fifth batch of flux, which are used for slagging, dephosphorization and desulfurization in the molten pool respectively;

[0019] In the above steps, the first batch of flux is mainly used to provide heat for converter smelting, protect the furnace lining, and quickly form slag; the second batch of flux is mainly used to provide appropriate binary alkalinity for smelting to provide conditions for dephosphorization and desulfurization, and at the same time prevent the need to add a certain amount of cold material when too much exothermic agent is added in the first batch; the third batch of flux is mainly used to increase the alkalinity, increase the fluidity of the steel slag, and protect the furnace lining; the fourth batch of flux is mainly used to increase the alkalinity, further increase the fluidity of the steel slag, and prevent the phenomenon that too much lime causes the slag to be unable to be melted and the slag is relatively dry; the fifth batch of flux is mainly used to increase the alkalinity and speed up the slag making speed.

[0020] In the third oxygen step, the gun position is 180-195 cm, and the oxygen flow rate is 730-780 Nm 3 / min, the sixth to eighth batches of flux are added in batches to facilitate dephosphorization and slag formation.

[0021] According to an embodiment of one aspect of the present application, the method further includes:

[0022] The added weight of each component flux is obtained based on the total weight of the molten iron, the target content and yield of each element in the molten steel from the converter, the binary basicity of the final slag, and the endpoint temperature. The components of the flux include: iron oxide scale, composite slag-reducing agent, light-burned dolomite, lime, ferrosilicon and light-burned magnesium balls, and at least two of the above fluxes are added to each batch.

[0023] According to an embodiment of one aspect of the present application, the method satisfies at least one of the following conditions:

[0024] The first flux comprises: 40% to 60% of the composite slag-forming agent based on the total weight of the composite slag-forming agent; 15% to 18% of the lime based on the total weight of the lime; 100% of the ferrosilicon based on the total weight of the ferrosilicon; and 75% to 85% of the light-burned magnesium balls based on the total weight of the light-burned magnesium balls;

[0025] The second batch of flux contains: 18% to 22% of iron oxide scale based on the total weight of the iron oxide scale; and 10% to 14% of lime based on the total weight of the lime;

[0026] The third batch of flux comprises: 18% to 22% of iron oxide scale based on the total weight of the iron oxide scale; 40% to 60% of light-burned dolomite based on the total weight of the light-burned dolomite; 12% to 16% of lime based on the total weight of the lime; and 15% to 25% of light-burned magnesium balls based on the total weight of the light-burned magnesium balls;

[0027] The fourth batch of flux comprises: 40% to 60% of light-burned dolomite based on the total weight of the light-burned dolomite; and 6% to 11% of lime based on the total weight of the lime;

[0028] The fifth flux comprises: 18%-22% of iron oxide scale based on the total weight of the iron oxide scale; 40%-60% of the composite slag-forming agent based on the total weight of the composite slag-forming agent; and 6%-11% of lime based on the total weight of the lime.

[0029] The sixth batch of flux contains: 18% to 22% of iron oxide scale based on the total weight of the iron oxide scale; and 6% to 15% of lime based on the total weight of the lime.

[0030] The seventh batch of flux contains: 8% to 12% of iron oxide scale based on the total weight of the iron oxide scale; and 6% to 15% of lime based on the total weight of the lime.

[0031] The eighth batch of flux contains: 8% to 12% of iron oxide scale based on the total weight of the iron oxide scale; and 6% to 15% of lime based on the total weight of the lime.

[0032] According to an embodiment of one aspect of the present application, the method satisfies at least one of the following conditions:

[0033] Iron oxide scale includes, by mass percentage: Fe2O3, 84%-90%; SiO2, 3%-8%, and the balance is unavoidable impurity elements;

[0034] The composite slag-reducing agent comprises, by mass percentage, Al2O3, 12%-15%; Fe2O3, 28%-38%; FeO, 28%-38%; SiO2, 1%-5%; the remainder being unavoidable impurity elements;

[0035] The light-burned dolomite comprises, by mass percentage: MgO, 40%-50%; CaO, 50%-60%, and the balance being unavoidable impurity elements;

[0036] Lime comprises, by mass percentage: CaO, 90%-95%, the remainder being unavoidable impurity elements;

[0037] Ferrosilicon comprises the following elements by mass percentage: Si, 70%-80%; Fe, 20%-28%; Al, 1%-2%; the remainder being unavoidable impurity elements;

[0038] The light-burned magnesium balls include, by mass percentage, MgO, 60%-70%; CaO, 1.5%-4.5%; SiO2, 1%-7%; and the remainder being impurity elements.

[0039] In a second aspect, the present application provides a nickel-containing molten steel produced by the method of the first aspect.

[0040] Compared with the prior art, this application has at least the following beneficial effects:

[0041] The method provided in this application controls the position of the oxygen gun and the oxygen flow rate according to the oxygen amount of the supplied oxygen in the total oxygen amount; wherein the gun position is 150-240cm; the oxygen flow rate is 700-900Nm 3 / min; the synergistic effect of controlling the lance position and the oxygen flow rate of the oxygen supply is used to make the binary basicity of the final slag reach 4.5 to 6.0. The synergistic effect from multiple aspects provides good thermodynamic conditions for dephosphorization, and ultimately makes the phosphorus content of the converter end point <0.004%. The solution of the present application produces molten steel with a low phosphorus content through the combined effect of controlling the lance position of the oxygen lance, the oxygen flow rate and the batch addition of calcium-containing flux, and also reduces the energy loss and iron loss in the converter smelting process, and shortens the smelting cycle to a certain extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the drawings without creative work.

[0043] Figure 1 A schematic flow chart of the method for smelting nickel-containing molten steel in a converter according to the present application is shown. DETAILED DESCRIPTION

[0044] In order to make the application purpose, technical solution and beneficial technical effects of this application clearer, the application is further described in detail below with reference to the embodiments. It should be understood that the embodiments described in this specification are only for explaining this application and are not intended to limit this application.

[0045] For simplicity, this application only explicitly discloses certain numerical ranges. However, any lower limit may be combined with any upper limit to form an unspecified range; and any lower limit may be combined with other lower limits to form an unspecified range, and similarly, any upper limit may be combined with any other upper limit to form an unspecified range. In addition, although not explicitly stated, each point or individual value between the endpoints of a range is included in the range. Thus, each point or individual value may serve as its own lower limit or upper limit and be combined with any other point or individual value, or with other lower limits or upper limits, to form an unspecified range.

[0046] In the description of this application, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number, and “a variety” in “one or more” means two or more.

[0047] The above disclosure of the present application is not intended to describe every disclosed embodiment or every implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided through a series of examples, which can be used in various combinations. In each example, the enumeration is intended only as a representative group and should not be construed as exhaustive.

[0048] Conventional steelmaking processes include converter smelting, refining, continuous casting, etc. Existing converter smelting methods generally include duplex method, double slag method and single slag method.

[0049] Currently, the duplex and double-slag processes are the primary converter methods for producing low-phosphorus steel. The duplex process uses one converter for dephosphorization of the molten iron and another for decarburization and temperature raising. The two converters operate in tandem to effectively improve steel quality and shorten the smelting cycle. However, the duplex process requires two converters, which can lead to significant heat losses. The double-slag process involves at least two slag-making stages: dephosphorization when the molten steel temperature is low, followed by slag removal when the slag phosphorus content is high, and then slag-making again. This method is time-consuming and unstable, prone to significant temperature losses. To ensure effective dephosphorization, high lance position operation is generally employed. However, this results in high FeO content in the slag, significant iron losses, and highly unstable dephosphorization efficiency. Furthermore, the double-slag smelting process is challenging in achieving rapid slag-making and slag-dumping during the dephosphorization phase. Currently, the addition of CaF2 is commonly used, but this process can cause significant CaF2 pollution.

[0050] The existing single-slag converter process struggles to meet the requirements for low-phosphorus steel production. Research by the inventors has led to a method that utilizes high lance positions and oxygen flow control based on different oxygen steps, along with the coordinated addition of multiple fluxes, to achieve a high binary basicity in the final slag. Furthermore, a combined bottom-blowing mode with argon or nitrogen is employed. This approach reduces energy consumption and iron loss while ensuring low-phosphorus steel production requirements, while also shortening the smelting cycle to a certain extent.

[0051] Method for smelting nickel-containing molten steel in converter

[0052] In a first aspect, the present application provides a method for smelting nickel-containing molten steel in a converter, such as Figure 1 ,include:

[0053] S100. Add nickel alloy or nickel element to the molten iron, use oxygen lance to supply oxygen to the molten iron, and add calcium flux in batches. The oxygen lance position is 150-240cm, and the oxygen flow rate is 700-900Nm 3 / min,

[0054] S200. Under the condition of oxygen supply as the first oxygen step, control the oxygen gun position to 200-240cm and the oxygen flow rate to 800-900Nm 3 / min;

[0055] S300. Under the condition of oxygen supply as the second oxygen step, control the oxygen gun position to 180-195cm and the oxygen flow rate to 750-870Nm 3 / min;

[0056] S400. Under the condition of oxygen supply as the third oxygen step, control the oxygen gun position to 180-195cm and the oxygen flow rate to 730-780Nm 3 / min;

[0057] S500. Under the condition of oxygen supply as the fourth oxygen step, control the oxygen gun position to 180-190cm and the oxygen flow rate to 730-870Nm 3 / min. Use the auxiliary gun for temperature measurement, carbon determination, oxygen determination and sampling. At this time, the oxygen gun position is 150-180cm, and the oxygen flow rate is 850-870Nm 3 / min. According to the embodiment of the present application, the oxygen step means the ratio of the amount of oxygen supplied up to a certain moment to the total amount of oxygen supplied for the entire converter smelting, that is, the oxygen step at this moment. The entire oxygen supply process may include the first oxygen step, the second oxygen step, the third oxygen step, the fourth oxygen step, the fifth oxygen step, and so on. The total amount of oxygen supplied for the entire converter smelting can be obtained based on the material balance and the heat balance according to the static calculation model. For a converter with a molten steel weight of 210t per furnace, the total oxygen supply during smelting can be 10,000-13,500Nm 3 , can also be 10500-12500Nm 3 , oxygen flow rate is 700-900Nm 3 Generally speaking, scrap steel and nickel plates are added in the early stages of smelting. Based on the target nickel content (Ni: 8.7-9.6 wt%) at the end of converter smelting and the weight of the entire converter molten steel, the nickel plates are added using a furnace dismantling machine or forklift. The nickel plates are added after the scrap steel and molten iron have been added.

[0058] According to the embodiment of the present application, during the oxygen supply process using an oxygen lance in converter smelting, the lance position is controlled to be 150-240cm, so that slag can be better formed when flux is added. The overall lance position adopts a high-low-high-low change. The high lance position in the early stage is mainly helpful for slag formation and provides better thermodynamic and kinetic conditions for dephosphorization; after the oxidation of silicon and manganese is completed, in order to increase the heat, the lance position is appropriately lowered. This stage is the decarburization period; in the middle stage of decarburization, the carbon-oxygen reaction is intense. In order to prevent the slag from drying out, a high lance position is used. This stage is also conducive to dephosphorization; in the later stage, in order to strengthen stirring, the lance position is further lowered. It also has the function of controlling temperature. Changing the lance position can achieve better dephosphorization and decarburization; the oxygen flow rate is 700-900Nm 3 / min, providing good thermodynamic and kinetic conditions for dephosphorization and desulfurization reactions. For example, in the initial converter smelting stage, the oxygen flow rate is 866Nm 3 / min, because the gun position is higher, the appropriate flow rate can provide suitable conditions for the oxidation of carbon, silicon and manganese. When the flux is added, the dissolution and slag formation of the flux can be accelerated to avoid the steel slag becoming sticky and difficult to slag.

[0059] At the end of converter smelting, the lowest gun position operation is adopted to uniformize the composition of molten steel.

[0060] Generally speaking, the height of the converter is 10094mm, the depth of the molten pool is 1665mm, and the gun position of the oxygen gun refers to the distance between the end of the oxygen gun nozzle and the static liquid surface of the molten pool. The gun position is controlled at 150cm-240cm.

[0061] According to the proportion of oxygen supplied to the total oxygen volume, the oxygen gun position and oxygen flow rate are controlled; the gun position is 150-240cm; the oxygen flow rate is 700-900Nm 3 / min; the synergistic effect of controlling the gun position and the oxygen flow rate of the oxygen supply is to achieve a binary basicity of the final slag of 4.5 to 6.0. The synergistic effect from multiple aspects provides good thermodynamic conditions for dephosphorization, ultimately making the phosphorus content of the converter end point <0.004%, and reducing the energy loss and iron loss during the converter smelting process, and shortening the smelting cycle to a certain extent. In some embodiments, in S100, the molten iron contains, by mass percentage: Si, 0.3%-0.5%, C, 4.0%-4.5%, Mn <0.35%, P ≤ 0.090%, S ≤ 0.002%, and the balance is iron and unavoidable impurity elements; optionally, the temperature of the molten iron is ≥ 1290°C.

[0062] According to the embodiments of the present application, the molten iron with the above composition can be effectively dephosphorized using the method of the present application. Generally speaking, after the molten steel is tapped, the slag is removed, the taphole is blocked, the molten iron and scrap steel are added, and oxygen supply and blowing begin. The molten iron temperature before slag removal is ≥1330°C, and the molten iron temperature after slag removal is ≥1290°C. By controlling the molten iron temperature after slag removal, the appropriate physical and chemical heat is provided for subsequent converter smelting.

[0063] In some embodiments, between the second oxygen step and the third oxygen step, the method further includes: maintaining the oxygen flow rate in the second oxygen step and lowering the gun position in the second oxygen step.

[0064] In some embodiments, in S200 , the first oxygen step is less than 8%.

[0065] In some embodiments, in S300 , the second oxygen step is 8%-35%.

[0066] In some embodiments, in S400 , the third oxygen step is 35%-65%.

[0067] In some embodiments, in S500 , the fourth oxygen step is >65%.

[0068] In some embodiments, the calcium-containing flux is added in batches under the condition that the oxygen step is 8%-65%.

[0069] The method of the present application obtains the added weight of each component flux according to the total weight of molten iron, the target content of each element in the molten steel in the converter smelting and the yield of each element, the binary basicity of the final slag and the endpoint temperature, wherein the components of the flux include: iron oxide scale, composite slag-reducing agent, light-burned dolomite, lime, ferrosilicon and light-burned magnesium balls, and at least two of the above fluxes are added to each batch; finally, according to the oxygen step, gun position and oxygen flow rate, the flux component and timing of addition are controlled to realize converter smelting of molten steel, effectively reduce the phosphorus content in the molten steel, and at the same time effectively improve the yield of metal elements, saving energy.

[0070] In some embodiments, in S300, in the second oxygen step, the gun position is 180-195 cm, and the oxygen flow rate is 750-870 Nm 3 / min, calcium-containing flux is added in batches; the first batch of flux is mainly used to provide heat for converter smelting, protect the furnace lining, and quickly make slag; the second batch of flux is mainly used to provide appropriate binary alkalinity for smelting to provide conditions for dephosphorization and desulfurization, and at the same time to prevent the need to add a certain amount of cold material when too much exothermic agent is added in the first batch; the third batch of flux is mainly used to increase the alkalinity, increase the fluidity of the slag, and protect the furnace lining; the fourth batch of flux is mainly used to increase the alkalinity, further increase the fluidity of the slag, and prevent the phenomenon that too much lime causes the slag to be unable to be melted and the slag is relatively dry; the fifth batch of flux is mainly used to increase the alkalinity and speed up the slag making speed.

[0071] According to the embodiments of the present application, the first batch of flux to the eighth batch of flux, in the entire reaction process, mainly play the role of providing heat, improving the efficiency of dephosphorization and desulfurization, rapid slag formation, reducing oxygen consumption, improving the fluidity of steel slag, and extending the life of the converter. The mixing effect of the flux cooperates with the high-low-high-low change of the oxygen lance position. When the lance position is high, it is helpful to slag and provide better thermodynamic and kinetic conditions for dephosphorization; when the lance position is low, decarburization reaction mainly occurs. As the reaction proceeds, in the middle stage of decarburization, the carbon-oxygen reaction is intense. In order to prevent the slag from drying out, the lance position needs to be raised, which is also beneficial to dephosphorization; in the later stage of converter smelting, the lance position needs to be lowered to strengthen stirring, so the lance position shows a high-low-high-low change in the entire smelting process.

[0072] In S400, when oxygen supply is the third oxygen step, the gun position is 180-195cm, and the oxygen flow rate is 730-780Nm 3 At a flow rate of 100 / min, the sixth to eighth batches of flux are added in batches. These batches consist of iron oxide scale and lime. Optionally, the oxygen level can be increased by 8%-12% before the final batch of iron oxide scale and lime is added. The sixth, seventh, and eighth batches of flux are added to further increase basicity for dephosphorization and slag formation.

[0073] In some embodiments, when oxygen is supplied as the fourth oxygen step, the gun position is 180-190 cm, and the oxygen flow rate is 730-780 Nm 3 / min, iron oxide scale and lime are added in batches. In some embodiments, the oxygen level is increased by 8%-12% before the last batch of iron oxide scale and lime is added.

[0074] In some embodiments, the smelting endpoint temperature is less than 1635° C., which has a positive effect of protecting the furnace lining and ensuring the quality of molten steel.

[0075] In some embodiments, after slagging, the components of the final slag include, in mass percentage, CaO, 45% to 55%, MgO, 6% to 10%, SiO2, 8% to 12%, P2O5, 1% to 3%; Al2O3, 1% to 2.5%, FeO, 14% to 20%, and the remainder is inevitable impurities produced during the steelmaking process.

[0076] After using the method of the present application, steel can be tapped according to the control requirements. During the tapping process, a certain amount of dephosphorization agent and lime are added for slag washing. After tapping, some lime is added for thick slag treatment. After tapping, the converter is splashed to protect the furnace. The intensity of the nitrogen in the splashing is controlled to 3.5-3.7Nm 3 / (min·t), the slag splashing gun position is controlled at 60-150cm, and the slag splashing time is ≥2.5min; after the slag splashing is completed, the furnace is shaken to hang the large surface and the residue is poured out; after the steel is tapped, the ladle is lifted to the slag removal station for slag removal operation, and alloying is carried out after the slag is removed. After entering the refining furnace, the composition is fine-tuned, slag is made to remove inclusions and the temperature is increased. After the composition is adjusted and the required temperature of the molten steel is reached, continuous casting is carried out.

[0077] According to the method of the present application, the entire converter smelting process adopts a high-low-high-low gun position; a constant high gun position of 190-240 cm is used during the first two slag making periods, and when the oxidation of Si and Mn is completed, the gun position is lowered to between 180-195 cm to facilitate decarburization. A high gun position of 185-195 cm is used in the later stage of the decarburization reaction, and the gun position is lowered to 150-180 cm in the later stage of the entire converter smelting, thereby effectively achieving decarburization and dephosphorization.

[0078] In some embodiments, the method further includes: obtaining the added weight of each component flux according to the total weight of the molten iron, the target content of each element in the molten steel from the converter and the yield of each element, the binary basicity of the final slag and the endpoint temperature, wherein the components of the flux include: iron oxide scale, composite slag-reducing agent, light-burned dolomite, lime, ferrosilicon and light-burned magnesium balls, and at least two of the above fluxes are added to each batch.

[0079] According to the embodiment of the present application, the weight of the flux can be calculated before the converter smelting, or can be calculated in real time during the converter smelting process. Before adding the flux, the weight of the flux can be obtained.

[0080] In some embodiments, the method satisfies at least one of the following conditions:

[0081] The first flux comprises: 40% to 60% of the composite slag-forming agent based on the total weight of the composite slag-forming agent; 15% to 18% of the lime based on the total weight of the lime; 100% of the ferrosilicon based on the total weight of the ferrosilicon; and 75% to 85% of the light-burned magnesium balls based on the total weight of the light-burned magnesium balls;

[0082] The second batch of flux contains: 18% to 22% of iron oxide scale based on the total weight of the iron oxide scale; and 10% to 14% of lime based on the total weight of the lime;

[0083] The third batch of flux comprises: 18% to 22% of iron oxide scale based on the total weight of the iron oxide scale; 40% to 60% of light-burned dolomite based on the total weight of the light-burned dolomite; 12% to 16% of lime based on the total weight of the lime; and 15% to 25% of light-burned magnesium balls based on the total weight of the light-burned magnesium balls;

[0084] The fourth batch of flux comprises: 40% to 60% of light-burned dolomite based on the total weight of the light-burned dolomite; and 6% to 11% of lime based on the total weight of the lime;

[0085] The fifth flux comprises: 18%-22% of iron oxide scale based on the total weight of the iron oxide scale; 40%-60% of the composite slag-forming agent based on the total weight of the composite slag-forming agent; and 6%-11% of lime based on the total weight of the lime.

[0086] The sixth batch of flux contains: 18% to 22% of iron oxide scale based on the total weight of the iron oxide scale; and 6% to 15% of lime based on the total weight of the lime.

[0087] The seventh batch of flux contains: 8% to 12% of iron oxide scale based on the total weight of the iron oxide scale; and 6% to 15% of lime based on the total weight of the lime.

[0088] The eighth batch of flux contains: 8% to 12% of iron oxide scale based on the total weight of the iron oxide scale; and 6% to 15% of lime based on the total weight of the lime.

[0089] According to the embodiments of the present application, ferrosilicon plays the role of providing heat, light-burned magnesium balls mainly play the role of protecting the furnace lining, and the role of lime is mainly for dephosphorization. The dephosphorization reaction occurs at the slag-steel interface. Lime is beneficial to increase the alkalinity and increase the calcium oxide content in the slag, which is beneficial to the dephosphorization and desulfurization reactions; the composite slag-forming agent and iron oxide scale have roughly the same function and are mainly used to adjust the composition of steel slag, which is beneficial to rapid slag formation and improved dephosphorization efficiency. At the same time, iron oxide scale and composite slag-forming agent will increase the (FeO) content in the slag. The melting point of iron oxide is relatively low, and the melting point of composite CaO·FeO is also relatively low, which can reduce the melting point of the entire slag system, thereby reducing the viscosity of the slag and improving the fluidity of the slag; light-burned dolomite and light-burned magnesium balls can increase the MgO content in the slag and play the role of protecting the furnace lining.

[0090] In some embodiments, the method satisfies at least one of the following conditions:

[0091] Iron oxide scale includes, by mass percentage: Fe2O3, 84%-90%; SiO2, 3%-8%, and the balance is unavoidable impurity elements;

[0092] The composite slag-reducing agent comprises, by mass percentage, Al2O3, 12%-15%; Fe2O3, 28%-38%; FeO, 28%-38%; SiO2, 1%-5%; the remainder being unavoidable impurity elements;

[0093] The light-burned dolomite comprises, by mass percentage: MgO, 40%-50%; CaO, 50%-60%, and the balance being unavoidable impurity elements;

[0094] Lime comprises, by mass percentage: CaO, 90%-95%, the remainder being unavoidable impurity elements;

[0095] Ferrosilicon comprises the following elements by mass percentage: Si, 70%-80%; Fe, 20%-28%; Al, 1%-2%; the remainder being unavoidable impurity elements;

[0096] The light-burned magnesium balls include, by mass percentage, MgO, 60%-70%; CaO, 1.5%-4.5%; SiO2, 1%-7%, and the balance being inevitable impurity elements.

[0097] According to the embodiments of the present application, the total weight of each component of the flux, such as iron oxide scale, can be calculated based on material balance and heat balance, and is 5-10 kg / t; the composite slag agent can be obtained based on the charging system of each steel plant, and is 2-4 kg / t; the light-burned dolomite can be calculated based on the binary alkalinity and MgO content in the slag, and the ratio of the effective components of CaO and MgO in the light-burned dolomite, and is 10-16 kg / t; the lime can be calculated based on the binary alkalinity and the ratio of the effective component of CaO in the lime, and is 45-55 kg / t; the ferrosilicon can be calculated based on material balance and heat balance, and is 5-15 kg / t; and the light-burned magnesium balls can be calculated based on the MgO content in the slag and the ratio of the effective component of MgO in the light-burned magnesium balls, and is 5-8 kg / t; by the total weight of these components in the converter smelting process, they are reasonably added in batches, and are combined according to the oxygen step, gun position and oxygen flow rate, and the appropriate time is selected for addition, so as to achieve better desulfurization, decarburization and dephosphorization effects, and also have the positive effect of reducing energy loss and protecting the converter lining.

[0098] In the related art, the chemical equation for converter dephosphorization is:

[0099] 2[P]+5(FeO)+3(CaO)=(3CaO·P2O5)+5[Fe]

[0100] The inventors have found, through thermodynamic and kinetic derivation studies, that low temperatures and higher FeO and CaO contents in the slag are more conducive to dephosphorization. The method of this application employs the method of adding lime and other components multiple times, and describes in detail the mixing and addition of lime and other components, the corresponding changes in lance position, and the bottom blowing flow rate. Controlling the final slag basicity between 4.0 and 7.0, combined with changes in lance position, enables better dephosphorization, resulting in a furnace end-point phosphorus content of <0.004%.

[0101] Furthermore, the method of the present application achieves a binary basicity of the final slag of 4.0 to 7.0, preferably 4.5 to 6.0, at the end of converter smelting. This binary basicity range promotes dephosphorization. The single-slag method of the present application provides favorable thermodynamic conditions for dephosphorization from multiple synergistic effects, ultimately achieving a converter endpoint phosphorus content of <0.004%, reducing energy loss and iron loss during converter smelting and shortening the smelting cycle to a certain extent.

[0102] In some embodiments, the oxygen supply is provided at a seventh oxygen step, and a secondary lance TSC is used for detection to achieve carbon determination, temperature measurement, sampling, and oxygen determination. In some embodiments, the seventh oxygen step is 85%-100%, preferably 90%.

[0103] In some embodiments, the method further comprises: using a secondary lance to perform carbon determination, temperature measurement, sampling, and oxygen determination, wherein the oxygen lance position is 150-180 cm and the oxygen flow rate is 850-870 Nm 3 / min.

[0104] In some embodiments, when the amount of oxygen supplied accounts for the fifth oxygen step of the total oxygen supply, the auxiliary lance is started, at which time the oxygen lance position is 150-180 cm, and the oxygen flow rate is 850-870 Nm 3 The fifth oxygen step may be an oxygen step with an oxygen content of 89% to 90%.

[0105] Use the auxiliary gun TSC probe to determine carbon, measure temperature and take samples. The auxiliary gun is used when the oxygen step is 89%-90%. The gun position of the oxygen gun is 150-180cm, and the oxygen flow rate is 750-870Nm 3 / min, carbon determination, temperature measurement, sampling and oxygen determination are carried out.

[0106] According to the embodiment of the present application, the auxiliary gun TSC probe is used to determine carbon, measure temperature and take samples, and then some slag-making material is added for adjustment based on the carbon determination and the measured temperature. Smelting is tracked according to the auxiliary gun detection results until the gun is started when the smelting process requirements are met. After the blowing is completed, the auxiliary gun TSO probe is used to determine carbon, measure temperature, take samples and determine oxygen.

[0107] Specific steps for measuring the auxiliary gun:

[0108]

[0109] In some embodiments, the converter smelting process further includes bottom blowing. The bottom blowing gas is an inert gas or nitrogen, preferably Ar. Bottom blowing rapidly mixes the molten steel with the flux and accelerates slag formation.

[0110] In a second aspect, the present application provides a nickel-containing molten steel produced by the method of the first aspect.

[0111] According to an embodiment of the present application, the chemical composition of the converter steel produced by the present application can be C, 0.01% to 0.025%; Si, 0.1% to 0.2%; Mn, 0.45% to 0.55%; P, ≤0.004%; S, ≤0.006%; Al, 0.015% to 0.035%; Ni, 9.0% to 9.4%; N, ≤0.003%; the balance being Fe and unavoidable inclusion elements. This converter steel has a low phosphorus content and shortens the smelting cycle to a certain extent.

[0112] Example

[0113] The following examples describe the present disclosure in more detail and are intended to be illustrative only, as various modifications and variations within the scope of the present disclosure will be apparent to those skilled in the art. Unless otherwise indicated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and used directly without further processing, and all instruments used in the examples are commercially available.

[0114] Example 1

[0115] The present application provides a method for smelting nickel-containing molten steel in a converter, comprising:

[0116] S100. Use oxygen lance to supply oxygen to molten iron, add calcium-containing flux in batches, the oxygen lance position is 150-240cm, and the oxygen flow rate is 700-900Nm 3 / min, where

[0117] S200. Under the condition of oxygen supply as the first oxygen step, control the oxygen gun position to 200-240cm and the oxygen flow rate to 800-900Nm 3 / min;

[0118] S300. Under the condition of oxygen supply as the second oxygen step, control the oxygen gun position to 180-195cm and the oxygen flow rate to 750-870Nm 3 / min; among them, flux is added in batches. The first batch of flux is mainly used to provide heat for converter smelting, splash slag to protect the furnace, protect the furnace lining, and quickly make slag; the second batch of flux is mainly used to provide appropriate binary alkalinity for smelting to provide conditions for dephosphorization and desulfurization, and at the same time prevent the need to add a certain amount of cold material when too much exothermic agent is added in the first batch; the third batch of flux is mainly used to increase the alkalinity, increase the fluidity of the slag, protect the furnace lining, and appropriately reduce the temperature of the molten steel; the fourth batch of flux is mainly used to increase the alkalinity, further increase the fluidity of the slag, and prevent the phenomenon that too much lime causes the slag to be unable to be melted and the slag is relatively dry; the fifth batch of flux is mainly used to increase the alkalinity, speed up the slag making speed, and appropriately reduce the temperature.

[0119] S400. Under the condition of oxygen supply as the third oxygen step, control the oxygen gun position to 180-195cm and the oxygen flow rate to 730-780Nm 3 / min; several sixth fluxes are added in batches. The sixth to eighth fluxes consist of scale and lime. Optionally, the oxygen level is increased by 8%-12% before the last batch of scale and lime is added. The sixth, seventh, and eighth fluxes are added to further increase the basicity for dephosphorization and slag formation.

[0120] S500. Under the condition of oxygen supply as the fourth oxygen step, control the oxygen gun position to 180-190cm and the oxygen flow rate to 730-870Nm 3 / min; use the auxiliary gun for carbon determination, temperature measurement, sampling and oxygen determination. At this time, the oxygen gun position is 150-180cm, and the oxygen flow rate is 850-870Nm 3 / min.

[0121] The specific parameters are shown in Table 1.

[0122] Table 1

[0123]

[0124] Example 2

[0125] The difference between the embodiment of the present application and embodiment 1 is that the specific parameters are shown in Table 2.

[0126] Table 2

[0127]

[0128] Example 3

[0129] The difference between the embodiment of the present application and embodiment 1 is that the specific parameters are shown in Table 3.

[0130] Table 3

[0131]

[0132]

[0133] Comparative Example 1

[0134] The difference between the comparative example of the present application and Example 1 is that lime is added less times. The specific parameters are shown in Table 4.

[0135] Table 4

[0136]

[0137]

[0138] Comparative Example 2

[0139] The difference between the comparative example of the present application and Example 1 is that a high gun position is not adopted. The specific parameters are shown in Table 5.

[0140] Table 5

[0141]

[0142]

[0143] Test section

[0144] 1) Phosphorus content detection: The phosphorus content in the converter molten steel was detected using a Vario Macro Cube elemental analyzer from German Elemental Analysis Systems. The test results are shown in Table 6.

[0145] 2) Sulfur and carbon content detection: The sulfur and carbon contents in the converter molten steel were detected using a LECO CS744 high-frequency infrared carbon-sulfur analyzer from the United States. The test results are shown in Table 6.

[0146] 3) Energy usage calculation:

[0147]

[0148] 4) Iron loss calculation or detection:

[0149]

[0150] Table 6

[0151]

[0152]

[0153] As can be seen from the above table, the phosphorus content at the converter end point of Examples 1, 2 and 3 is low and the time is short, the iron loss is low and the thermal efficiency is high. The phosphorus content at the converter end point of Comparative Examples 1 and 2 is high and the time is long, the iron loss is high and the thermal efficiency is low.

[0154] This application improves upon the single-slag method, achieving an extremely low phosphorus content in the converter steel (<0.004% at the converter endpoint) while significantly shortening the smelting cycle. This demonstrates that the method can achieve stable production of low-phosphorus steel while also shortening the smelting cycle. Furthermore, compared to traditional double-slag and duplex methods, it avoids the complex process and significant heat loss associated with using two converters.

[0155] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present application, and such modifications or substitutions should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for smelting nickel-containing molten steel in a converter, comprising: Add nickel alloy or nickel element to the molten iron and use an oxygen lance to supply oxygen to the molten iron. The oxygen lance position is 150-240cm and the oxygen flow rate is 700-900Nm 3 / min; according to the total weight of the molten iron, the target content and yield of each element in the molten steel from the converter, the binary basicity of the final slag, and the endpoint temperature, the added weight of each component flux is obtained, the nickel content is 8.7-9.6 wt%, the binary basicity of the final slag after the converter smelting is 4.5-6.0, and the smelting endpoint temperature is less than 1635°C; the components of the flux include: iron oxide scale, composite slag-forming agent, light-burned dolomite, lime, ferrosilicon and light-burned magnesium balls, wherein, Under the condition that the oxygen supply is the first oxygen step, the oxygen gun position is controlled to be 200-240cm and the oxygen flow rate is 800-900 Nm 3 / min; the first oxygen step is <8%; Under the condition that the oxygen supply is the second oxygen step, the oxygen gun position is controlled to be 180-195cm, and the oxygen flow rate is 750-870Nm 3 / min; the second oxygen step is 8%-35%; calcium-containing flux is added in batches, and the calcium-containing flux includes the first batch of flux, the second batch of flux, the third batch of flux, the fourth batch of flux and the fifth batch of flux in sequence; the first batch of flux comprises: based on the total weight of the composite slagging agent, 40%-60% of the composite slagging agent; based on the total weight of the lime, 15%-18% of the lime; based on the total weight of the ferrosilicon, 100% of the ferrosilicon; and based on the total weight of the light-burned magnesium balls, 75%-85% of the light-burned magnesium balls; the second batch of flux comprises: based on the total weight of the iron oxide scale, 18%-22% of the iron oxide scale; and based on the total weight of the lime, 10%-14% of the lime; the third batch of flux comprises: based on the total weight of the oxygen-containing flux Based on the total weight of the calcined iron scale, 18%-22% of the calcined iron scale; based on the total weight of the calcined dolomite, 40%-60% of the calcined dolomite; based on the total weight of the lime, 12%-16% of the lime; and based on the total weight of the calcined magnesium balls, 15%-25% of the calcined magnesium balls; the fourth batch of flux comprises: based on the total weight of the calcined dolomite, 40%-60% of the calcined dolomite; and based on the total weight of the lime, 6%-11% of the lime; the fifth batch of flux comprises: based on the total weight of the calcined iron scale, 18%-22% of the calcined iron scale; based on the total weight of the composite slagging agent, 40%-60% of the composite slagging agent; and based on the total weight of the lime, 6%-11% of the lime; Under the condition that the oxygen supply is the third oxygen step, the oxygen gun position is controlled to be 180-195cm, and the oxygen flow rate is 730-780Nm 3 / min; the third oxygen step is 35%-65%; the sixth to eighth batches of flux are added in batches; the sixth batch of flux contains: 18%-22% of iron oxide scale based on the total weight of iron oxide scale; and 6%-15% of the lime based on the total weight of lime; the seventh batch of flux contains: 8%-12% of iron oxide scale based on the total weight of iron oxide scale; and 6%-15% of the lime based on the total weight of lime; the eighth batch of flux contains: 8%-12% of iron oxide scale based on the total weight of iron oxide scale; and 6%-15% of the lime based on the total weight of lime; Under the condition that the oxygen supply is the fourth oxygen step, the oxygen gun position is controlled to be 180-190cm and the oxygen flow rate is 730-870Nm 3 / min; the fourth oxygen step>65%.

2. The method according to claim 1, characterized in that The molten iron contains, by mass percentage, the following elements: Si, 0.3%-0.5%, C, 4.0%-4.5%, Mn <0.35%, P≤0.090%, S≤0.002%, and the remainder being iron and unavoidable impurity elements.

3. The method according to claim 1, characterized in that The temperature of the molten iron is ≥1290°C.

4. The method according to claim 1, wherein The method satisfies at least one of the following conditions: The iron oxide scale comprises, by mass percentage: Fe2O3, 84%-90%; SiO2, 3%-8%, and the balance being unavoidable impurity elements; The composite slag-forming agent comprises, by mass percentage, Al2O3, 12%-15%; Fe2O3, 28%-38%; FeO, 28%-38%; SiO2, 1%-5%; the remainder being unavoidable impurity elements; The light-burned dolomite comprises, by mass percentage: MgO, 40%-50%; CaO, 50%-60%, and the balance being inevitable impurity elements; The lime comprises, by mass percentage, 90%-95% of CaO, with the remainder being unavoidable impurity elements; The ferrosilicon comprises the following elements by mass percentage: Si, 70%-80%; Fe, 20%-28%; Al, 1%-2%; the remainder being unavoidable impurity elements; The light-burned magnesium balls include, by mass percentage, MgO, 60%-70%; CaO, 1.5%-4.5%; SiO2, 1%-7%, and the remainder being inevitable impurity elements.

5. A nickel-containing molten steel, produced by smelting the method according to any one of claims 1 to 4.

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