Phosphorus pig iron and preparation method and application thereof

Abstract

The invention relates to the technical field of electrolytic aluminum materials, in particular to phosphorus pig iron and a preparation method and application thereof. The phosphorus pig iron comprises the following chemical components in parts by mass: 3.10-4.10 parts of C, 0.8-1.2 parts of P, less than or equal to 0.2 part of S and Mn, wherein the mass part of Mn satisfies the following formula: [Mn] = (2.8-3.2) * [S], in the formula, [Mn] represents the mass part of Mn, and [S] represents the mass part of S. According to the phosphorus pig iron, the mass fraction of Mn is controlled in a component optimization mode, particularly through the mass fraction of S, the electrical resistivity of the phosphorus pig iron can be effectively reduced, and therefore the iron-carbon pressure drop of the phosphorus pig iron at different working condition temperatures can be reduced.

Description

Technical Field

[0001] The present application relates to the technical field of electrolytic aluminum materials, and in particular to phosphorus pig iron and a preparation method and application thereof. Background Art

[0002] The voltage drop of electrolytic aluminum anode iron-carbon is generally 70mV~100mV, accounting for about one-third of the voltage drop of the anode group, which has a large energy-saving space. As an important material for connecting the anode steel claw and the anode carbon block, the quality of phosphorus pig iron is the main influencing factor of its conductivity and contact voltage drop. Therefore, the quality of phosphorus pig iron is directly related to the use effect of anode assembly.

[0003] At present, in order to further reduce the iron-carbon voltage drop of electrolytic aluminum anodes, large-scale research has been carried out on the composition of phosphorus pig iron. However, these studies on phosphorus pig iron of electrolytic aluminum anode groups generally have two problems. First, the phosphorus pig iron formulas given are all content ranges of various components, and in actual production, there is no treatment method for the mutual influence between various components. Second, after the newly cast and assembled anode group is used after the pole is replaced, its iron-carbon voltage drop runs at a high level for about 10 days, while the service life of a set of anode groups is only 31 to 35 days. In addition, the value of the iron-carbon voltage drop after stabilization is also in the range of 70mV to 100mV, which makes the useless power consumption of the anode group large.

[0004] At present, the research on phosphorus pig iron includes: (1) Phosphorus pig iron for improving the conductivity of graphite cathode carbon blocks. On the basis of ordinary phosphorus pig iron, five alloying elements such as Ni, Cr, and V are added to improve the fluidity and shrinkage of phosphorus pig iron to improve the overall conductivity of phosphorus pig iron. (2) Phosphorus pig iron for aluminum electrolysis. This phosphorus pig iron provides a phosphorus pig iron formula range through comparative optimization tests on a variety of phosphorus pig irons. The characteristic of this phosphorus pig iron formula is that the fluidity of phosphorus pig iron is enhanced. (3) High-carbon and low-silicon phosphorus pig iron and its application. This study provides a phosphorus pig iron formula range. The characteristic of this phosphorus pig iron formula is that the carbon and silicon content range is increased, and the minimum carbon content is only required to reach 2.5%. (4) Phosphorus pig iron formula and production method for aluminum electrolysis anode assembly. The characteristic of this study is that the fluidity of phosphorus pig iron melt and the later pressure-release effect are improved through the phosphorus pig iron formula. Summary of the invention

[0005] The present application provides a phosphorus pig iron and a preparation method and application thereof to solve the following technical problem: how to reduce the iron-carbon pressure drop of the phosphorus pig iron.

[0006] In a first aspect, the present application provides a phosphorus pig iron, wherein the chemical composition of the phosphorus pig iron satisfies, in parts by mass:

[0007] C: 3.10 parts to 4.10 parts, P: 0.8 parts to 1.2 parts, S≤0.2 parts, and Mn; wherein the mass parts of Mn satisfy: [Mn] = (2.8 to 3.2) × [S], wherein [Mn] represents the mass parts of Mn, and [S] represents the mass parts of S.

[0008] Optionally, the chemical composition also satisfies: Mn≤0.64 parts.

[0009] Optionally, the chemical composition further comprises:

[0010] Si: 1.6 to 2.6 parts and Fe ≥ 90 parts.

[0011] In a second aspect, the present application provides a method for preparing the phosphorus pig iron described in the first aspect, the method comprising:

[0012] Smelting the phosphorus pig iron raw material to obtain molten metal;

[0013] Performing element analysis on the molten metal to obtain first mass fraction data of Mn and second mass fraction data of S;

[0014] Calculating theoretical mass fraction data of Mn according to the second mass fraction data;

[0015] Determining whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data;

[0016] If so, the molten metal is purified to obtain a purified molten metal; wherein the purification treatment includes the addition of manganese or the dilution of manganese.

[0017] Optionally, judging whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data comprises the steps of:

[0018] Determining whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data;

[0019] If the first mass fraction data is equal to the theoretical mass fraction data, it is determined that there is no need to purify the molten metal;

[0020] If the first mass fraction data is greater than or less than the theoretical mass fraction data, it is determined that the molten metal needs to be purified;

[0021] In the case where the molten metal needs to be purified, the type of the purification process is determined according to the first mass fraction data and the theoretical mass fraction data.

[0022] Optionally, when the molten metal needs to be purified, determining the type of purification according to the first mass fraction data and the theoretical mass fraction data comprises the following steps:

[0023] In the case where the molten metal needs to be purified, if the first mass fraction data is less than the theoretical mass fraction data, manganese is added to the molten metal to obtain a purified molten metal; or

[0024] In the case where the molten metal needs to be purified, if the first mass fraction data is greater than the theoretical mass fraction data, the molten metal is diluted with manganese to obtain a purified molten metal.

[0025] Optionally, judging whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data, then comprises:

[0026] The purified molten metal is cast to obtain a phosphorus pig iron product.

[0027] Optionally, the smelting temperature is 1250° C. to 1300° C.; and / or

[0028] The casting temperature is 1200°C to 1250°C.

[0029] Optionally, the casting includes a temperature reduction section, the time of the temperature reduction section is ≤30 min, and the temperature reduction amplitude of the temperature reduction section is ≤50°C.

[0030] In a third aspect, the present application provides an electrolytic aluminum anode group, the anode group comprising the phosphorus pig iron described in the first aspect; the anode group satisfies:

[0031] When the working temperature T of the anode group satisfies: T<200°C and the guide rod current of the anode resistor is 8000A~10000A, the iron-carbon voltage drop of the phosphorus pig iron is 70mV~90mV;

[0032] When the working temperature T of the anode group satisfies: 200°C≤T<300°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 50V-70V;

[0033] When the working temperature T of the anode group satisfies: 300°C≤T<500°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 40V-60V.

[0034] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0035] The embodiment of the present application provides a phosphorus pig iron, in which the mass fraction of carbon is controlled to be 3.10 parts to 4.10 parts, and the content of graphite phase in the phosphorus pig iron can be reduced while the phosphorus pig iron has good conductivity. The phosphorus pig iron with low graphite phase content can effectively reduce the resistivity of the phosphorus pig iron, thereby reducing the iron-carbon pressure drop of the phosphorus pig iron; in addition, the phosphorus pig iron controls the mass fraction of phosphorus to be 0.8 parts to 1.2 parts, so that the phosphorus pig iron has an appropriate amount of phosphorus. The appropriate amount of phosphorus can strengthen the matrix of the phosphorus pig iron and refine the grains of the phosphorus pig iron. At the same time, the appropriate amount of phosphorus can prevent excessive phosphorus from precipitating. Phosphide is used to reduce the resistivity of phosphorus pig iron, thereby reducing the iron-carbon pressure drop of phosphorus pig iron; in addition, the mass portion of sulfur in the phosphorus pig iron is controlled to be less than 0.2 parts, and the mass portions of manganese and sulfur are controlled to satisfy: [Mn] = (2.8-3.2) × [S], which can reduce the amount of manganese sulfide formed by manganese and sulfur, and phosphorus pig iron with low manganese sulfide content can effectively reduce the resistivity of phosphorus pig iron, thereby reducing the iron-carbon pressure drop of phosphorus pig iron; therefore, the phosphorus pig iron can effectively reduce the resistivity of phosphorus pig iron by optimizing its composition, thereby reducing the iron-carbon pressure drop of phosphorus pig iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0037] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0038] Figure 1 A schematic diagram of a phosphorus pig iron product provided in an embodiment of the present application;

[0039] Figure 2 A schematic flow chart of a method for preparing phosphorus pig iron provided in an embodiment of the present application;

[0040] Figure 3 A schematic diagram of a purification process of a method for preparing phosphorus pig iron provided in an embodiment of the present application;

[0041] Figure 4 A detailed schematic diagram of a method for preparing phosphorus pig iron provided in an embodiment of the present application;

[0042] Figure 5 Schematic diagram of the iron-carbon pressure drop detection method of phosphorus pig iron provided in an embodiment of the present application. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0044] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited number (fractional or integer) within the indicated range.

[0045] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" 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. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions, refers to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0046] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0047] It should be noted that, with respect to the prior art (1) recorded in the background technology, the inventors found that the alloy components added to the phosphorus pig iron formula will not only increase the operational complexity of the actual preparation method, thereby increasing the difficulty of controlling the alloy range, but also increase the production cost of the enterprise; with respect to the prior art (2) recorded in the background technology, the inventors found that the effect on the iron-carbon voltage drop is not significant; with respect to the prior art (3) recorded in the background technology, the inventors found that the carbon content used in the phosphorus pig iron formula is relatively low, which will affect the conductivity and mechanical properties of the phosphorus pig iron; with respect to the prior art (4) recorded in the background technology, the inventors found that the research has no obvious effect on reducing the iron-carbon voltage drop of the anode group.

[0048] Therefore, how to further reduce the iron-carbon pressure drop of phosphorus pig iron is a technical problem that needs to be solved urgently.

[0049] It should be noted that the voltage drop that affects the voltage balance of the electrolytic cell is generally composed of four parts: anode group voltage drop, cathode voltage drop, inter-electrode voltage drop and peripheral busbar voltage drop. Among them, the anode group voltage drop includes four parts: fixture voltage drop, aluminum guide rod voltage drop, steel claw voltage drop and iron-carbon contact voltage drop of the anode carbon block. The three types of anode voltage drops, fixture voltage drop, aluminum guide rod voltage drop and steel claw voltage drop, as well as the carbon block resistance, are stable under certain conditions and are not easy to adjust. Therefore, the main factor affecting the change of the anode voltage drop is the iron-carbon contact voltage drop. In addition, studies have shown that the iron-carbon contact voltage drop generated by the resistance between the anode steel claw and the carbon block will account for about half of the entire anode voltage drop, and in modern aluminum electrolysis production, the connection between the anode steel claw and the carbon block is formed by casting phosphorus pig iron in a molten state. Therefore, the performance of phosphorus pig iron directly determines the level of the iron-carbon contact voltage drop between the anode steel claw and the carbon block.

[0050] Figure 1 A schematic diagram of a product of phosphorus pig iron provided in an embodiment of the present application is exemplarily shown;

[0051] like Figure 1 As shown, the embodiment of the present application provides a phosphorus pig iron, and the chemical composition of the phosphorus pig iron satisfies, in parts by mass:

[0052] C: 3.10 parts to 4.10 parts, P: 0.8 parts to 1.2 parts, S≤0.2 parts and Mn; wherein the mass parts of Mn satisfy: [Mn]=(2.8-3.2)×[S], wherein [Mn] represents the mass parts of Mn, and [S] represents the mass parts of S.

[0053] It should be noted that the mass parts of C can be 3.10 parts, 3.20 parts, 3.30 parts, 3.40 parts, 3.50 parts, 3.60 parts, 3.70 parts, 3.80 parts, 3.90 parts, 4.00 parts or 4.10 parts.

[0054] The mass fraction of P may be 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts or 1.2 parts.

[0055] The mass fraction of S may be 0.01 part, 0.02 part, 0.03 part, 0.04 part, 0.05 part, 0.10 part, 0.15 part or 0.20 part.

[0056] The mass fraction of Mn may satisfy: [Mn]=2.8×[S], 2.9×[S], 3.0×[S], 3.1×[S] or 3.2×[S].

[0057] In summary, the phosphorus pig iron provided in the embodiments of the present application, in addition to the above-mentioned component optimization, can further reduce the iron-carbon pressure drop of the phosphorus pig iron by the following methods:

[0058] 1. Microstructure control

[0059] Grain refinement: Appropriate casting and heat treatment processes refine the grains of phosphorus pig iron and increase the number of grain boundaries, thereby improving the conductivity of the material and reducing the iron-carbon pressure drop of phosphorus pig iron;

[0060] Reduce segregation: Phosphorus pig iron is prone to component segregation during solidification, resulting in increased local resistance. By optimizing the casting process, such as using homogenization annealing treatment, the component segregation can be reduced in combination with component optimization, thereby improving the overall conductivity of phosphorus pig iron.

[0061] 2. Anode group design optimization

[0062] Anode arrangement: Reasonable anode arrangement can reduce the uneven distribution of current in the anode group, thereby reducing the iron-carbon pressure drop of phosphorus pig iron.

[0063] Contact resistance: Optimizing the contact mode between the anode and phosphorus pig iron can reduce the contact resistance and is also an effective way to reduce the iron-carbon voltage drop.

[0064] 3. Optimization of electrolysis conditions

[0065] Current density: Properly reducing the current density can reduce the heat generated during the electrolysis process, thereby reducing the iron-carbon pressure drop.

[0066] Electrolyte temperature: Controlling the temperature of the electrolyte within an appropriate range can maintain the stability of the electrolysis process and reduce resistance changes caused by temperature changes.

[0067] In summary, the phosphorus pig iron can be comprehensively designed from multiple aspects such as chemical composition optimization, microstructure control, anode group design optimization and electrolysis condition optimization. Through the optimization of these means, the efficiency and stability of the aluminum electrolysis process can be effectively improved.

[0068] In some optional embodiments, the chemical composition of the phosphorus pig iron also satisfies: Mn≤0.64 parts.

[0069] In these embodiments, the chemical composition of the phosphorus pig iron may also satisfy: Mn≤0.64 parts, which promotes the weight content of Mn in the phosphorus pig iron to be at a lower level, and can reduce the amount of manganese sulfide formed by manganese and sulfur. The phosphorus pig iron with low manganese sulfide content can effectively reduce the resistivity of the phosphorus pig iron, thereby reducing the iron-carbon pressure drop of the phosphorus pig iron.

[0070] In some optional embodiments, the chemical composition of the phosphorus pig iron further satisfies:

[0071] Si: 1.6 to 2.6 parts and Fe ≥ 90 parts;

[0072] In these embodiments, the chemical composition of the phosphorus pig iron can also meet the following requirements: Si: 1.6 to 2.6 parts, so that the phosphorus pig iron has an appropriate amount of silicon. On the one hand, an appropriate amount of silicon can be dissolved in the ferrite of the phosphorus pig iron to improve the strength and hardness of the ferrite, thereby enhancing the overall mechanical properties of the phosphorus pig iron. On the other hand, an appropriate amount of silicon can reduce the diffusion rate of carbon in the phosphorus pig iron, making it easier for carbon to precipitate in the form of graphite during solidification, thereby increasing the amount of graphite phase formed, thereby improving the conductivity of the phosphorus pig iron; in addition, an appropriate amount of silicon can optimize the microstructure of the phosphorus pig iron by refining the grains and reducing segregation, thereby increasing the number of grain boundaries, and a high content of grain boundaries can reduce the scattering probability at the grain boundaries, thereby reducing the resistivity of the phosphorus pig iron, thereby reducing the iron-carbon pressure drop of the phosphorus pig iron; in addition, Fe≥90 parts can promote the phosphorus pig iron to have a sufficient amount of iron element, so as to promote the phosphorus pig iron to have a sufficient amount of grain boundaries, thereby reducing the resistivity of the phosphorus pig iron, thereby reducing the iron-carbon pressure drop of the phosphorus pig iron.

[0073] Figure 2 A schematic flow chart of a method for preparing phosphorus pig iron provided in an embodiment of the present application is shown exemplarily;

[0074] Based on a general inventive concept, such as Figure 2 As shown, the embodiment of the present application provides a method for preparing the phosphorus pig iron, the method comprising:

[0075] S1. Smelting the phosphorus pig iron raw material to obtain a molten metal;

[0076] S2. performing elemental analysis on the molten metal to obtain a first mass fraction data of Mn and a second mass fraction data of S;

[0077] S3. Calculating the theoretical mass fraction data of Mn according to the second mass fraction data;

[0078] S4. Determine whether to purify the molten metal according to the first mass fraction data and the theoretical mass fraction data;

[0079] If so, the molten metal is purified to obtain a purified molten metal; wherein the purification treatment includes the addition of manganese or the dilution of manganese.

[0080] This method is a method for preparing the above-mentioned phosphorus pig iron. The specific composition of the phosphorus pig iron can refer to the above-mentioned embodiment. Since this method adopts part or all of the technical solutions of the above-mentioned embodiment, it at least has all the beneficial effects brought by the technical solutions of the above-mentioned embodiment, which will not be repeated here one by one.

[0081] It should be noted that the elemental analysis can be performed using spectral analysis.

[0082] It should be noted that, in addition to analyzing the mass fraction data of S and Mn in the molten metal, the elemental analysis can also analyze the mass fraction data of C, Si, and P to determine whether the mass fractions of these chemical components are within the range set for phosphorus pig iron.

[0083] It should be noted that the purification treatment can be performed by adding manganese or diluting manganese.

[0084] Figure 3 A schematic diagram of a purification process of a method for preparing phosphorus pig iron provided in an embodiment of the present application is exemplarily shown;

[0085] In some optional embodiments, such as Figure 3 As shown, judging whether to purify the molten metal according to the size of the first mass fraction data and the theoretical mass fraction data comprises the steps of:

[0086] S401. Determine whether to purify the molten metal according to the first mass fraction data and the theoretical mass fraction data;

[0087] If the first mass fraction data is equal to the theoretical mass fraction data, it is determined that there is no need to purify the molten metal;

[0088] If the first mass fraction data is greater than or less than the theoretical mass fraction data, it is determined that the molten metal needs to be purified;

[0089] S402. In the case where the molten metal needs to be purified, the type of purification treatment is determined according to the first mass fraction data and the theoretical mass fraction data;

[0090] In these embodiments, theoretical mass fraction data of manganese is calculated based on the second mass fraction data obtained by sulfur measurement, and the first mass fraction data obtained by manganese measurement is used as the standard. Through the size of the first mass fraction data and the theoretical mass fraction data, it can be determined whether the molten metal needs to be purified and the type of purification treatment, so that the mass fraction of manganese in phosphorus pig iron can be adjusted in real time.

[0091] Figure 4 A detailed schematic diagram of a method for preparing phosphorus pig iron provided in an embodiment of the present application is exemplarily shown;

[0092] In some optional embodiments, when the molten metal needs to be purified, determining the type of purification according to the first mass fraction data and the theoretical mass fraction data comprises the steps of:

[0093] S412. In the case where the molten metal needs to be purified, if the first mass fraction data is less than the theoretical mass fraction data, manganese is added to the molten metal to obtain a purified molten metal; or

[0094] S412. In the case where the molten metal needs to be purified, if the first mass fraction data is greater than the theoretical mass fraction data, diluting the molten metal with manganese to obtain a purified molten metal;

[0095] In these embodiments, when the molten metal needs to be purified, the specific type of purification treatment can be accurately determined based on the first mass fraction data and the theoretical mass fraction data to effectively control the mass fraction of manganese in the phosphorus pig iron.

[0096] It should be noted that the materials used for the addition of manganese and the dilution of manganese can be calculated based on the difference between the first mass fraction data and the theoretical mass fraction data to meet the weight content parameters of the final phosphorus pig iron.

[0097] It should be noted that the raw material used for the manganese supplementation can be pure manganese flakes or a manganese alloy with a high manganese content. When pure manganese flakes are used for manganese supplementation, the purity of the pure manganese flakes is required to be ≥99%.

[0098] It should be noted that the raw material used for diluting manganese can be pure iron or an iron alloy with a high iron content. When pure iron is used for diluting manganese, if pure iron uses cylindrical iron ingots, the length of the cylindrical iron ingot is required to be ≤300mm, and the diameter of the cylindrical iron ingot is required to be ≤40mm. If pure iron uses square iron ingots, the length of the square iron ingot is required to be ≤120mm, the width is ≤120mm and the height is ≤200mm.

[0099] It should be noted that both the addition and dilution of manganese can use a medium frequency furnace to make the added material and the molten metal mix evenly.

[0100] In some optional implementations, judging whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data, then comprises:

[0101] S5. The purified molten metal is cast to obtain a phosphorus pig iron product;

[0102] In these embodiments, the purified molten metal is cast, which can cause the purified molten metal to cool and form, thereby causing the phosphorus pig iron product to be formed.

[0103] In some optional embodiments, the smelting temperature is 1250° C. to 1300° C.; and / or

[0104] The casting temperature is 1200°C to 1250°C;

[0105] In these embodiments, the smelting temperature can be 1250°C to 1300°C, and the number of grain boundaries in the molten metal can be increased during the smelting process to improve the electrical conductivity of the material, thereby reducing the iron-carbon pressure drop of the phosphorus pig iron; in addition, the casting temperature can be 1200°C to 1250°C, which can avoid segregation of the molten metal during the solidification process to reduce the local resistance of the phosphorus pig iron, thereby improving the overall electrical conductivity of the phosphorus pig iron and reducing the iron-carbon pressure drop of the phosphorus pig iron.

[0106] The smelting temperature may be 1250°C, 1260°C, 1270°C, 1280°C, 1290°C or 1300°C.

[0107] The casting temperature may be 1200°C, 1210°C, 1220°C, 1230°C, 1240°C or 1250°C.

[0108] In some optional embodiments, the casting includes a temperature reduction section, the time of the temperature reduction section is ≤30 min, and the temperature reduction amplitude of the temperature reduction section is ≤50° C.;

[0109] In these embodiments, the casting may include a cooling section, and the duration of the cooling section is ≤30 min, and the cooling amplitude of the cooling section is ≤50°C, so as to avoid a large cooling during the transition between the smelting and casting stages, so as to avoid the segregation of the molten metal during the casting process, thereby reducing the local resistance of the phosphorus pig iron, improving the overall conductivity of the phosphorus pig iron, and reducing the iron-carbon pressure drop of the phosphorus pig iron.

[0110] The cooling period may be 10 min, 15 min, 20 min, 25 min or 30 min.

[0111] The cooling range of the cooling section can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C or 50°C.

[0112] Based on a general inventive concept, an embodiment of the present application provides an electrolytic aluminum anode group, the anode group includes the phosphorus pig iron; the anode group satisfies:

[0113] When the working temperature T of the anode group satisfies: T<200°C and the guide rod current of the anode resistor is 8000A~10000A, the iron-carbon voltage drop of the phosphorus pig iron is 70mV~90mV;

[0114] When the working temperature T of the anode group satisfies: 200°C≤T<300°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 50V-70V;

[0115] When the working temperature T of the anode group satisfies: 300°C≤T<500°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 40V-60V;

[0116] In these embodiments, at different operating temperatures of the anode group below 500° C. and a guide rod current of 8000A to 10000A, the iron-carbon voltage drop of the phosphorus pig iron can be controlled in the range of 70mV to 70V, which indicates that the phosphorus pig iron has a lower iron-carbon voltage drop.

[0117] When the working temperature T of the anode group satisfies: T<200°C and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron can be 70mV, 75mV, 80mV, 85mV or 90mV.

[0118] When the working temperature T of the anode group satisfies: 200°C≤T<300°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 50V, 55V, 60V, 65V or 70V.

[0119] When the working temperature T of the anode group satisfies: 300°C≤T<500°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 40V, 45V, 50V, 55V or 60V.

[0120] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions or conditions recommended by the manufacturer.

[0121] Example 1

[0122] like Figure 4 As shown, a method for preparing the phosphorus pig iron comprises:

[0123] S1. Smelting the phosphorus pig iron raw material to obtain a molten metal;

[0124] S2. The molten metal is allowed to stand for 20 to 30 minutes, and then elemental analysis is performed on the molten metal, and the first mass fraction data of Mn is 0.425% and the second mass fraction data of S is 0.16%;

[0125] S3. The theoretical mass fraction data of Mn is calculated according to the second mass fraction data to be 0.45% to 0.51%;

[0126] S401. Determine whether to purify the molten metal according to the first mass fraction data and the theoretical mass fraction data;

[0127] If the first mass fraction data is equal to the theoretical mass fraction data, it is determined that the molten metal does not need to be purified;

[0128] S412. In the case where the molten metal needs to be purified, if the first mass fraction data is less than the theoretical mass fraction data, manganese is added to the molten metal to obtain a purified molten metal; or

[0129] S412. In the case where the molten metal needs to be purified, if the first mass fraction data is greater than the theoretical mass fraction data, the molten metal is diluted with manganese to obtain a purified molten metal;

[0130] S5. Casting the purified molten metal to obtain a phosphorus pig iron product.

[0131] The melting temperature is 1250℃~1300℃;

[0132] The casting temperature was 1250°C.

[0133] The casting includes a cooling stage, the duration of the cooling stage is 22 minutes, and the cooling amplitude of the cooling stage is ≤50°C.

[0134] like Figure 1 As shown, a phosphorus pig iron, in terms of mass fraction, has the chemical composition that satisfies:

[0135] C: 3.11%, P: 1.2%, Si: 1.61%, S: 0.16%, Mn: 0.48% and Fe; wherein, [Mn]:[S] = (2.8-3.2): 1, [Mn] is the mass fraction of Mn, and [S] is the mass fraction of S.

[0136] Example 2

[0137] Based on the contents disclosed in Example 1, the following modifications are further made:

[0138] The first mass fraction data is 0.51%, and the second mass fraction data is 0.17%;

[0139] The theoretical mass fraction data of Mn calculated based on the second mass fraction data is 0.48% to 0.54%.

[0140] If the first mass fraction data is equal to the theoretical mass fraction data, it is determined that the molten metal does not need to be purified.

[0141] The casting temperature is 1200°C.

[0142] The cooling period is 20 minutes.

[0143] In terms of mass fraction, the chemical composition of phosphorus pig iron meets the following requirements:

[0144] C: 3.46%, P: 0.81%, Si: 2.6%, S: 0.17%, Mn: 0.51% and Fe.

[0145] Example 3

[0146] Based on the contents disclosed in Example 1, the following modifications are further made:

[0147] The first mass fraction data is 0.50%, and the second mass fraction data is 0.19%;

[0148] The theoretical mass fraction data of Mn calculated based on the second mass fraction data is 0.53% to 0.61%.

[0149] The casting temperature was 1230°C.

[0150] The cooling period lasts for 26 minutes.

[0151] In terms of mass fraction, the chemical composition of phosphorus pig iron meets the following requirements:

[0152] C: 4.10%, P: 0.96%, Si: 1.91%, S: 0.19%, Mn: 0.58% and Fe.

[0153] Example 4

[0154] Based on the contents disclosed in Example 1, the following modifications are further made:

[0155] The first mass fraction data is 0.52%, and the second mass fraction data is 0.17%;

[0156] The theoretical mass fraction data of Mn calculated based on the second mass fraction data is 0.48% to 0.54%.

[0157] If the first mass fraction data is equal to the theoretical mass fraction data, it is determined that the molten metal does not need to be purified.

[0158] The casting temperature was 1240°C.

[0159] The cooling period is 25 minutes.

[0160] In terms of mass fraction, the chemical composition of phosphorus pig iron meets the following requirements:

[0161] C: 3.86%, P: 0.11%, Si: 2.22%, S: 0.17%, Mn: 0.52% and Fe.

[0162] Example 5

[0163] Based on the contents disclosed in Example 1, the following modifications are further made:

[0164] The first mass fraction data is 0.46%, and the second mass fraction data is 0.18%;

[0165] The theoretical mass fraction data of Mn calculated based on the second mass fraction data is 0.50% to 0.58%.

[0166] The casting temperature was 1218°C.

[0167] The cooling period is 20 minutes.

[0168] In terms of mass fraction, the chemical composition of phosphorus pig iron meets the following requirements:

[0169] C: 3.64%, P: 0.92%, Si: 2.46%, S: 0.18%, Mn: 0.55% and Fe.

[0170] Comparative Example 1

[0171] Based on the contents disclosed in Example 1, the following modifications are further made:

[0172] Without controlling the mass fraction of Mn, the specific process is:

[0173] In terms of mass fraction, the chemical composition of phosphorus pig iron is controlled to meet the following requirements: C: 3.10% to 4.10%, Si: 1.6% to 2.6%, P: 0.8% to 1.2%, Mn: 0.3% to 0.9%, S≤0.2% and Fe.

[0174] According to the method flow of Example 1, the chemical composition of the molten metal is determined to meet the following requirements by mass fraction: C: 3.20%, Si: 2.46%, P: 0.92%, Mn: 0.32%, S: 0.18%, and the rest is Fe and unavoidable impurities.

[0175] The casting temperature was 1320°C.

[0176] The cooling period lasts for 22 minutes.

[0177] Comparative Example 2

[0178] Based on the contents disclosed in Comparative Example 1, the following modifications are further made:

[0179] In terms of mass fraction, the chemical composition of phosphorus pig iron is controlled to meet the following requirements: C: 3.10% to 4.10%, Si: 1.6% to 2.6%, P: 0.8% to 1.2%, Mn: 0.3% to 0.9%, S≤0.2% and Fe.

[0180] According to the method flow of Example 1, the chemical composition of the molten metal is determined to meet the following requirements by mass fraction: C: 3.98%, Si: 2.06%, P: 0.96%, Mn: 0.49%, S: 0.19%, and the rest is Fe and unavoidable impurities.

[0181] The casting temperature was 1350°C.

[0182] The cooling period lasts for 26 minutes.

[0183] Comparative Example 3

[0184] Based on the contents disclosed in Comparative Example 1, the following modifications are further made:

[0185] In terms of mass fraction, the chemical composition of phosphorus pig iron is controlled to meet the following requirements: C: 3.10% to 4.10%, Si: 1.6% to 2.6%, P: 0.8% to 1.2%, Mn: 0.3% to 0.9%, S≤0.2% and Fe.

[0186] According to the method flow of Example 1, the chemical composition of the molten metal is determined to meet the following requirements by mass fraction: C: 4.00%, Si: 2.16%, P: 0.92%, Mn: 0.81%, S: 0.19%, and the rest is Fe and unavoidable impurities.

[0187] The casting temperature is 1300°C.

[0188] The cooling period lasts for 23 minutes.

[0189] Related experiments and effect data:

[0190] 1. The phosphorus pig iron obtained in each embodiment and comparative example is assembled into an anode group. When the guide rod current of the anode resistor is 8000A to 10000A and the working temperature T of the anode group satisfies: T<200℃, 200℃≤T<300℃ or 300℃≤T<500℃, the iron-carbon pressure drop of the phosphorus pig iron is measured. The specific detection process is as follows: Figure 5 As shown, the specific steps are:

[0191] (1) The phosphorus pig iron in the anode group will be Figure 1 The phosphorus pig iron casting ring is cast into a ring as shown, and the anode steel claw head at a height of 3 cm to 5 cm above the phosphorus pig iron casting ring is first grinded with a grinder to remove the oxide scale of the steel claw head, and marked as the first measuring point;

[0192] (2) The upper surface of the anode carbon block within 3 cm to 5 cm from the outside of the phosphorus pig iron casting ring is used as the second measuring point;

[0193] (3) Connect the two poles of the DC voltmeter to the first measuring point and the second measuring point to measure the iron-carbon voltage drop. The results obtained by the test are shown in Table 1.

[0194] Table 1 Iron-carbon pressure drop results obtained in various embodiments and comparative examples

[0195]

[0196] As can be seen from Table 1, the phosphorus pig iron provided in the embodiment of the present application can effectively reduce the resistivity of the phosphorus pig iron by optimizing the composition, especially controlling the mass fraction of Mn by the mass fraction of S, thereby reducing the iron-carbon pressure drop of the phosphorus pig iron at different operating temperatures.

[0197] In addition, the phosphorus pig iron provided in the embodiment of the present application can be comprehensively designed from multiple aspects such as chemical composition optimization, microstructure control, anode group design optimization, and electrolysis condition optimization. By optimizing these means, the efficiency and stability of the aluminum electrolysis process can be effectively improved.

[0198] In addition, an embodiment of the present application provides a phosphorus pig iron, and in addition, an embodiment of the present application provides a method for preparing phosphorus pig iron. This method only requires the addition of manganese or dilution of manganese after the molten metal detection process to effectively control the manganese content, thereby effectively reducing the resistivity of the phosphorus pig iron and reducing the iron-carbon pressure drop of the phosphorus pig iron.

[0199] 2. Practical application test of phosphorus pig iron:

[0200] The anode group assembled in the above-mentioned embodiment 1 is installed in the electrolytic cell for use. After continuous use, it can be found that as the casting proceeds, the temperature of the phosphorus pig iron in the carbon bowl of the carbon anode of the electrolytic cell gradually increases, and the iron-carbon pressure drop of the phosphorus pig iron is reduced to 40mV~60mV within 5 to 6 days, and it can be operated stably subsequently; while the phosphorus pig iron assembled in comparative example 1 needs to be reduced to 60mV~100mV within 9 to 10 days and maintain stable operation; this shows that a kind of phosphorus pig iron provided in the embodiment of the present application can effectively reduce the iron-carbon pressure drop by about 20mV. From this calculation, it can be known that the electrolytic cell can save 20kWh~30kWh of electricity for every ton of aluminum produced, and the iron-carbon pressure drop fluctuation range of the anode group is smaller.

[0201] Therefore, an electrolytic aluminum anode group provided in an embodiment of the present application, when using the phosphorus pig iron provided in an embodiment of the present application, can effectively shorten the operating time of a newly replaced anode group under high iron-carbon pressure drop conditions, and can also maintain a stable iron-carbon pressure drop of the anode group for a long time.

[0202] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A phosphorus pig iron, wherein the chemical composition of the phosphorus pig iron comprises, by weight: C: 3.10 to 4.10 parts, P: 0.8 to 1.2 parts, S ≤ 0.2 parts, and Mn; The mass fraction of Mn satisfies: [Mn]=(2.8-3.2)×[S], wherein [Mn] represents the mass fraction of Mn, and [S] represents the mass fraction of S.

2. The phosphorus pig iron according to claim 1, wherein the chemical composition further satisfies: Mn≤0.64 parts.

3. The phosphorus pig iron according to claim 1, wherein the chemical composition further comprises: Si: 1.6 to 2.6 parts and Fe ≥ 90 parts.

4. A method for preparing the phosphorus pig iron according to any one of claims 1 to 3, the method comprising: Smelting the phosphorus pig iron raw material to obtain molten metal; Performing element analysis on the molten metal to obtain first mass fraction data of Mn and second mass fraction data of S; Calculating theoretical mass fraction data of Mn according to the second mass fraction data; Determining whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data; If so, the molten metal is purified to obtain a purified molten metal; wherein the purification treatment includes the addition of manganese or the dilution of manganese.

5. The method according to claim 4, wherein judging whether to purify the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data comprises the steps of: Determining whether to perform purification treatment on the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data; If the first mass fraction data is equal to the theoretical mass fraction data, it is determined that there is no need to purify the molten metal; If the first mass fraction data is greater than or less than the theoretical mass fraction data, it is determined that the molten metal needs to be purified; In the case where the molten metal needs to be purified, the type of the purification process is determined according to the first mass fraction data and the theoretical mass fraction data.

6. The method according to claim 5, wherein when the molten metal needs to be purified, the type of purification is determined according to the first mass fraction data and the theoretical mass fraction data, comprising the steps of: In the case where the molten metal needs to be purified, if the first mass fraction data is less than the theoretical mass fraction data, manganese is added to the molten metal to obtain a purified molten metal; or In the case where the molten metal needs to be purified, if the first mass fraction data is greater than the theoretical mass fraction data, the molten metal is diluted with manganese to obtain a purified molten metal.

7. The method according to claim 4, wherein judging whether to purify the molten metal according to the magnitude of the first mass fraction data and the theoretical mass fraction data, further comprises: The purified molten metal is cast to obtain a phosphorus pig iron product.

8. The method according to claim 7, wherein the smelting temperature is 1250°C to 1300°C; and / or The casting temperature is 1200°C to 1250°C.

9. The method according to claim 7, wherein the casting comprises a temperature reduction section, the time of the temperature reduction section is ≤30 minutes, and the temperature reduction amplitude of the temperature reduction section is ≤50°C.

10. An anode group for electrolytic aluminum, comprising the phosphorus pig iron according to any one of claims 1 to 3; the anode group satisfies: When the working temperature T of the anode group satisfies: T<200°C and the guide rod current of the anode resistor is 8000A~10000A, the iron-carbon voltage drop of the phosphorus pig iron is 70mV~90mV; When the working temperature T of the anode group satisfies: 200°C≤T<300°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 50V-70V; When the working temperature T of the anode group satisfies: 300°C≤T<500°C, and the guide rod current of the anode resistor is 8000A-10000A, the iron-carbon voltage drop of the phosphorus pig iron is 40V-60V.

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