Method and system for recycling phosphorus pig iron from electrolytic aluminum anode group

Abstract

The invention relates to the technical field of phosphorus pig iron recycling, in particular to a method and system for recycling phosphorus pig iron from an electrolytic aluminum anode set. The method comprises the following steps: sequentially carrying out first magnetic separation and crushing treatment on a phosphorus pig iron ring to obtain a first phosphorus pig iron block with an anode carbon block; the first phosphorus pig iron block with the anode carbon block is sequentially subjected to second magnetic separation and shot blasting treatment, and a second phosphorus pig iron block is obtained; performing third magnetic separation on the second phosphorus pig iron block to obtain a third phosphorus pig iron block; melting the third phosphorus pig iron block to obtain a phosphorus pig iron melt; and the phosphorus pig iron melt is subjected to casting molding, and the phosphorus pig iron ring is obtained. According to the method, through multi-cascade control of interface stripping, magnetic purification and thermodynamic migration, step-by-step removal of the sulfur element is achieved, sulfur is prevented from being enriched in the melting stage of the phosphorus pig iron, the final increase amount of the sulfur content is effectively reduced to be 5% or below, and therefore the enrichment degree of the sulfur element in the phosphorus pig iron can be effectively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of phosphorus pig iron recovery and utilization, and in particular to a method and system for recovering phosphorus pig iron from an electrolytic aluminum anode group. Background Art

[0002] The anode group is an important equipment structure in the current molten salt electrolytic aluminum production process. The anode group is generally composed of a guide rod, a steel claw, and an anode carbon block. The guide rod and the steel claw are connected as a whole by explosion welding or aluminum-steel direct welding, and the steel claw and the anode carbon block are connected as a whole by casting phosphorus pig iron. Since the anode carbon block has a service life of only about 30 days, except for the carbon anode that is naturally consumed, the guide rod, steel claw, and cast phosphorus pig iron that are connected as a whole can be recycled. At present, the phosphorus pig iron used for anode group casting needs to have the following characteristics: (1) good conductivity and low shrinkage; (2) in order to facilitate the cast phosphorus pig iron to be removed from the steel claw, the phosphorus pig iron must have a certain room temperature brittleness; (3) certain strength properties. The current recycling process for phosphorus pig iron in electrolytic aluminum anode groups is as follows: first, a press is used to press the brittle phosphorus pig iron off the anode steel claws. Then, a rotating drum is used to remove the residual anode carbon blocks adhering to the surface of the phosphorus pig iron through the friction and collision forces generated by the rolling of the phosphorus pig iron blocks against each other. Finally, the processed phosphorus pig iron is directly added to the smelting furnace for remelting to achieve the recycling of the phosphorus pig iron.

[0003] During the remelting process of phosphorus pig iron, additives such as recarburizers and desulfurizers are generally required to temper the composition. Sulfur is a strongly inhibitory element to the graphitization process of phosphorus pig iron. It also increases the shrinkage and contact pressure drop of the phosphorus pig iron matrix and reduces the fluidity of the phosphorus pig iron melt. It also causes the cast phosphorus pig iron product to become hot brittle. In severe cases, hot brittleness can even cause the cast phosphorus pig iron to crack. Therefore, sulfur is a harmful element in the production of finished phosphorus pig iron. At present, the technologies for removing sulfur from phosphorus pig iron include: (1) designing a desulfurizer for waste phosphorus pig iron and a method for desulfurization and carbon increase, smelting the recovered waste phosphorus pig iron, and then using a desulfurizer for desulfurization; (2) designing a pretreatment method for phosphorus pig iron rings, which utilizes the difference in the expansion and contraction of phosphorus pig iron and the characteristics of the phosphorus pig iron rings themselves. Under the action of liquid nitrogen, the phosphorus pig iron rings can produce larger cracks, and these cracks will generate a high pressure-removing force, so as to achieve low-pressure pressing of phosphorus pig iron; (3) designing a phosphorus pig iron ring recycling system, connecting the iron ring pressing machine, the cleaning drum and the subsequent furnace to form a continuous production line, and removing sulfur impurities on the surface of phosphorus pig iron through the pressing action of the iron ring pressing machine and the rolling removal of the cleaning drum, with high work efficiency.

[0004] However, the above-mentioned desulfurization technologies either reduce the existing sulfur content of phosphorus pig iron or simply treat the phosphorus pig iron and directly put it into the circulation process, which cannot solve the problem of continuous enrichment of sulfur in phosphorus pig iron. Summary of the Invention

[0005] The present application provides a method and system for recycling phosphorus pig iron from an electrolytic aluminum anode group to solve the following technical problem: how to reduce the enrichment level of sulfur in phosphorus pig iron.

[0006] In a first aspect, embodiments of the present application provide a method for recycling phosphorus pig iron from an electrolytic aluminum anode group, wherein the phosphorus pig iron is in the form of a phosphorus pig iron ring, and an anode carbon block is attached to the surface of the phosphorus pig iron ring, wherein the anode carbon block contains sulfur. The method comprises:

[0007] The phosphorus pig iron ring is subjected to a first magnetic separation and crushing process in sequence to obtain a first phosphorus pig iron block having an anode carbon block;

[0008] subjecting the first phosphorus pig iron block having the anode carbon block to a second magnetic separation and a shot blasting treatment in sequence to remove the anode carbon block on the surface of the phosphorus pig iron block, thereby obtaining a second phosphorus pig iron block;

[0009] subjecting the second phosphorus pig iron block to a third magnetic separation to obtain a third phosphorus pig iron block;

[0010] melting the third phosphorus pig iron block to obtain a phosphorus pig iron melt;

[0011] The phosphorus pig iron melt is cast into a shape to obtain a phosphorus pig iron ring.

[0012] Optionally, the step of sequentially subjecting the first phosphorus pig iron block having the anode carbon block to a second magnetic separation and shot blasting to remove the anode carbon block on the surface of the phosphorus pig iron block to obtain a second phosphorus pig iron block comprises the following steps:

[0013] subjecting the first phosphorus pig iron block with the anode carbon block to a second magnetic separation to obtain a magnetically separated phosphorus pig iron block;

[0014] Shot blasting the magnetically separated phosphorus pig iron using grinding balls as grinding media under preset pressure conditions to remove anode carbon blocks on the surface of the magnetically separated phosphorus pig iron block to obtain a second phosphorus pig iron block;

[0015] Wherein, the preset pressure is 4MPa to 6.5MPa.

[0016] Optionally, the diameter of the grinding balls is 0.8 mm to 1.2 mm.

[0017] Optionally, the shot blasting treatment time is 20 minutes to 25 minutes.

[0018] Optionally, the target size of the crushing process is ≤100 mm.

[0019] Optionally, the magnetic field strengths of the first magnetic separation, the second magnetic separation, and the third magnetic separation are all 1.4T to 1.6T.

[0020] Optionally, melting the third phosphorus pig iron block to obtain a phosphorus pig iron melt comprises the following steps:

[0021] preheating the third phosphorus pig iron block to obtain a preheated phosphorus pig iron block;

[0022] The preset phosphorus pig iron solution is melted to obtain a phosphorus pig iron melt.

[0023] Optionally, the preheating temperature is 300° C. to 450° C., and the preheating time is 30 min to 40 min.

[0024] Optionally, the superheat degree of the casting molding is 150°C to 250°C.

[0025] In a second aspect, an embodiment of the present application provides a system for recycling phosphorus pig iron from an electrolytic aluminum anode group. The system is adapted to the method described in the first aspect, and the system includes:

[0026] The pre-processing unit includes a press, a crusher, a shot blasting machine, and a plurality of magnetic separation devices. The discharge port of the press is connected to the feed port of the crusher, and the discharge port of the crusher is connected to the feed port of the shot blasting machine. The magnetic separation devices are respectively arranged between the press and the crusher, between the crusher and the shot blasting machine, and at the discharge port of the shot blasting machine.

[0027] The melting part includes a melting furnace and a pouring mold. The discharge port of the shot blasting machine is connected to the feed port of the melting furnace, and the pouring mold is arranged at the liquid outlet of the melting furnace.

[0028] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0029] The present application provides a method for recycling phosphorus pig iron from an electrolytic aluminum anode group. The method first cuts the phosphorus pig iron ring into smaller phosphorus pig iron blocks by crushing, thereby increasing the specific surface area of ​​the phosphorus pig iron ring with the anode carbon block attached. Subsequently, the surface of the phosphorus pig iron can be impacted by high-speed shot blasting to peel off the anode carbon block on the surface of the phosphorus pig iron, directly reducing the attachment of the sulfur-containing carrier (anode carbon block), thereby cutting off the direct source of sulfur before the phosphorus pig iron melts. In addition, magnetic separation is interspersed with crushing and shot blasting. Based on the strong magnetism of phosphorus pig iron and the non-magnetic nature of anode carbon block, phosphorus pig iron and anode carbon block can be separated to avoid secondary contamination of anode carbon block, thereby reducing the sulfur content of phosphorus pig iron before melting. Finally, the sulfur remaining in the phosphorus pig iron is converted into a gaseous state by melting to achieve separation of phosphorus pig iron melt and sulfur, thereby further reducing the sulfur content of the phosphorus pig iron and avoiding sulfur enrichment. Therefore, this method can systematically remove the sulfur-containing anode carbon blocks on the surface and inside of the phosphorus pig iron through the synergistic effect of mechanical stripping and magnetic separation, and combine with the purification effect of melting to significantly reduce the sulfur enrichment in the phosphorus pig iron, thereby effectively reducing the enrichment level of sulfur in the phosphorus pig iron. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] 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.

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 A schematic flow chart of a method for recovering phosphorus pig iron from an electrolytic aluminum anode group provided in an embodiment of the present application;

[0033] Figure 2 A schematic diagram of a phase analysis process for a method for recovering phosphorus pig iron from an electrolytic aluminum anode group provided in an embodiment of the present application;

[0034] Figure 3 A schematic diagram of the logical structure of a system for recycling phosphorus pig iron from an electrolytic aluminum anode group provided in an embodiment of the present application;

[0035] Among them, 1-press off machine, 2-crusher, 3-shot blasting machine, 4-magnetic separation device, 5-melting furnace, 6-pouring mold. DETAILED DESCRIPTION

[0036] To make the purpose, technical solutions, and advantages of the embodiments of this application more clear, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the drawings in the embodiments of this application. Obviously, the described embodiments are part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0037] The range descriptions described in this application, such as numerical ranges, ratio ranges, etc., include all possible sub-ranges and single numerical values ​​within the range. For example, the range description of "1 to 6" or "1~6" covers all sub-ranges from 1 to 6 (such as 1 to 3, 2 to 5, etc.) and single numbers (such as 1, 2, 3, 4, 5, 6). Unless otherwise specified, the terms "including" and "including" used in this article mean "including but not limited to"; relational terms such as "first" and "second" are only used to distinguish different entities or operations, and do not imply an actual sequence or association relationship; "and / or" means that multiple situations can exist alone or simultaneously; expressions such as "at least one", "multiple", and "at least one" refer to any combination of corresponding objects, including a combination of single or multiple objects. The proportional relationships involved in the text, such as mass ratios, molar ratios, etc., should be understood as the corresponding relationship between the first and second terms of the proportional formula in the order of description. The raw materials, reagents, instruments and equipment used in this article can be purchased on the market or prepared by existing methods.

[0038] It should be noted that during the molten recycling of phosphorus pig iron, the initial sulfur content of the newly melted phosphorus pig iron is generally less than 0.2%, meeting the sulfur content requirements for phosphorus pig iron used in electrolytic aluminum casting. During the recycling process, the residual anode carbon blocks attached to the surface of the phosphorus pig iron enter the phosphorus pig iron melt as the phosphorus pig iron melts. Since the anode carbon blocks retain a large amount of sulfur during use, this sulfur accumulates in the phosphorus pig iron melt, increasing the sulfur content of the recycled phosphorus pig iron. The maximum sulfur content can reach approximately 1.5%. Even if desulfurization is used on this high-sulfur phosphorus pig iron, the large amount of desulfurizer added will affect the content of other active ingredients in the phosphorus pig iron. Furthermore, the desulfurization effect of conventional desulfurizers is poor, making it difficult to effectively reduce the sulfur content in the phosphorus pig iron. High sulfur content in phosphorus pig iron not only affects the properties of the phosphorus pig iron matrix but also affects its application, significantly harming normal electrolytic aluminum production.

[0039] Therefore, how to effectively reduce the enrichment of sulfur in the recycling stage of phosphorus pig iron is a technical problem that needs to be solved in the anode assembly process of the electrolytic aluminum industry.

[0040] Figure 1A schematic flow chart of a method for recycling phosphorus pig iron from an electrolytic aluminum anode group provided in an embodiment of the present application is shown as an example;

[0041] like Figure 1 As shown, an embodiment of the present application provides a method for recycling phosphorus pig iron from an electrolytic aluminum anode group, wherein the phosphorus pig iron exists in the form of a phosphorus pig iron ring, and an anode carbon block is attached to the surface of the phosphorus pig iron ring, and the anode carbon block contains sulfur. The method includes:

[0042] S1. The phosphorus pig iron ring is sequentially subjected to a first magnetic separation and crushing process to obtain a first phosphorus pig iron block having an anode carbon block;

[0043] S2. The first phosphorus pig iron block having an anode carbon block is sequentially subjected to a second magnetic separation and shot blasting to remove the anode carbon block on the surface of the phosphorus pig iron block to obtain a second phosphorus pig iron block;

[0044] S3. The second phosphorus pig iron block is subjected to a third magnetic separation to obtain a third phosphorus pig iron block;

[0045] S4. The third phosphorus pig iron block is melted to obtain a phosphorus pig iron melt;

[0046] S5. Casting the phosphorus pig iron melt to obtain a phosphorus pig iron ring.

[0047] It should be noted that the first magnetic separation, the second magnetic separation and the third magnetic separation can not only realize the screening and separation of phosphorus pig iron, but also serve as a power source for the phosphorus pig iron at each stage, so that the phosphorus pig iron can smoothly enter each processing stage.

[0048] It should be noted that, before the casting and molding, the phosphorus pig iron melt can be subjected to furnace analysis and tempering treatment, and the content of elements other than carbon in the phosphorus pig iron can be made to meet the furnace discharge requirements by tempering agents of various alloys and non-metallic elements; then, a recarburizer is added to the phosphorus pig iron melt after the tempering treatment to replenish the carbon content of the phosphorus pig iron. The recarburizer is added 20 to 25 minutes before casting and molding.

[0049] It should be noted that before the first magnetic separation process, since the phosphorus pig iron ring is generally attached to the anode steel claw, the phosphorus pig iron ring and the anode steel claw can be separated by a press-off machine.

[0050] It should be noted that the present invention provides a method for recovering phosphorus pig iron from an electrolytic aluminum anode assembly. This method systematically reduces the concentration of sulfur through the synergistic effects of multi-stage physical stripping, magnetic separation, and high-temperature melting purification. The specific principles are as follows:

[0051] 1. Physical stripping and surface purification in stages:

[0052] (1) The key role of crushing:

[0053] 1) Surface Area Control: The original phosphorus pig iron rings (large and dense) are crushed into small particles (first phosphorus pig iron blocks). This crushing process significantly increases the specific surface area of ​​the phosphorus pig iron. This process not only exposes more of the interface covered by the anode carbon block but also maximizes the contact probability between the grinding balls (steel shots) and the sulfur-containing anode carbon blocks during the subsequent shot blasting process.

[0054] 2) Crack induction effect: The mechanical stress generated by the crushing will form microcracks at the interface between the phosphorus pig iron and the anode carbon block to weaken the physical bonding between the two, which creates a "weak point" for the subsequent stripping process of shot blasting.

[0055] (2) Dynamic mechanism of shot blasting:

[0056] 1) Kinetic energy impact stripping: The high-speed projectile grinding ball (steel shot) transfers kinetic energy and impacts the surface of phosphorus pig iron, preferentially crushing and stripping the anode carbon block with lower hardness (Mohs hardness is generally 1.5-2), while the phosphorus pig iron (hardness is generally 4-5) is retained due to its higher mechanical strength.

[0057] 2) Surface roughening effect: Shot blasting can not only remove carbon blocks, but also etch the surface of phosphorus pig iron at the micron level to form a rough texture, further weakening the adhesion between the residual anode carbon blocks and the phosphorus pig iron matrix, providing a cleaner material surface for subsequent magnetic separation.

[0058] 2. Gradient purification design of multi-stage magnetic separation:

[0059] (1) Progressive separation of three magnetic separations:

[0060] 1) First magnetic separation (before crushing): Magnetic separation can preliminarily screen out the free anode carbon chips mixed with the phosphorus pig iron rings after pressing, preventing the anode carbon particles from being embedded in the phosphorus pig iron matrix during the subsequent crushing process, thereby reducing the risk of "sulfur encapsulation".

[0061] 2) Second magnetic separation (after shot blasting): For the anode carbon block fragments that fall off during shot blasting, the high magnetic properties of the phosphorus pig iron block (saturation magnetization intensity > 1.5T) and the significant difference between the non-magnetic anode carbon slag can be used to quickly separate the phosphorus pig iron and the anode carbon block through a strong magnetic field, thereby preventing the secondary attachment of the anode carbon block.

[0062] 3) The third magnetic separation (before melting): The third magnetic separation method can achieve further separation of phosphorus pig iron and anode carbon blocks through a strong magnetic field. At the same time, it can also separate phosphorus pig iron and fine sulfur-containing dust, preventing sulfur from re-entering the phosphorus pig iron melt through the Fe-S eutectic phase during melting.

[0063] (2) Sorting frequency control: Through the reasonable distribution of different magnetic separations, non-magnetic impurities (anode carbon blocks) are fully separated from the magnetic flow channel, thereby improving the purity of phosphorus pig iron.

[0064] 3. Thermodynamic purification mechanism of melting process:

[0065] (1) Sulfur oxidation and release:

[0066] During the melting stage, the sulfur element remaining in the phosphorus pig iron may exist in the form of FeS, and the FeS in the melting furnace will react with the dissolved oxygen: FeS+O2→FeO+SO2↑, generating a large amount of SO2 gas. The generated SO2 gas can be discharged in a direction through the exhaust system of the melting furnace, reducing the re-dissolution of gaseous sulfur in the phosphorus pig iron melt.

[0067] (2) Slag adsorption and interface distribution:

[0068] Alkaline flux can be added to the melting furnace to form slag, which can promote the entry of sulfur into the slag phase in the form of CaS, thereby further achieving the removal of sulfur from phosphorus pig iron.

[0069] By adjusting the slag-metal interfacial tension (such as adding Al2O3 to adjust the slag viscosity), the enrichment of sulfur in the slag phase is enhanced and finally removed with the slag.

[0070] 4. Synergistic effect and sulfur migration path blocking:

[0071] (1) Double truncation of sulfur input pathway:

[0072] 1) Physical input blocking: The combined process of crushing-shot blasting-magnetic separation can remove a large amount of anode carbon blocks (the initial carrier of sulfur), eliminating the external input of sulfur from the source.

[0073] 2) Chemical migration inhibition: During the melting stage, the residual sulfur is converted from the iron-based solid solution (Fe-S) of the phosphorus pig iron to the gas phase (SO2) or slag phase (CaS) through oxidation slagging, thereby preventing it from solid solution enrichment in the regenerated phosphorus pig iron ring.

[0074] (2) Sulfur balance control for recycling:

[0075] After the entire process is processed, the regenerated phosphorus pig iron can meet the usage requirements of the electrolytic aluminum process and avoid the sulfur accumulation effect caused by multiple recycling uses.

[0076] In summary, the embodiments of the present application provide a method for recycling phosphorus pig iron from an electrolytic aluminum anode group. This method achieves step-by-step removal of sulfur elements through multi-stage cascade control of "interface stripping-magnetic purification-thermodynamic migration", providing an industrially feasible technical path for the efficient recycling of phosphorus pig iron in the electrolytic aluminum industry.

[0077] Figure 2 Schematic diagram of a phase analysis process for recovering phosphorus pig iron from an electrolytic aluminum anode group provided in an embodiment of the present application

[0078] In some optional embodiments, such as Figure 2 As shown, the first phosphorus pig iron block with the anode carbon block is subjected to a second magnetic separation and shot blasting treatment in sequence to remove the anode carbon block on the surface of the phosphorus pig iron block to obtain a second phosphorus pig iron block, comprising the steps of:

[0079] S201. The first phosphorus pig iron block having an anode carbon block is subjected to a second magnetic separation to obtain a magnetically separated phosphorus pig iron block;

[0080] S202. The magnetically separated phosphorus pig iron is shot blasted with grinding balls as a grinding medium under preset pressure conditions to remove the anode carbon block on the surface of the magnetically separated phosphorus pig iron block to obtain a second phosphorus pig iron block;

[0081] Wherein, the preset pressure is 4MPa to 6.5MPa.

[0082] In these embodiments, the non-magnetic anode carbon blocks and the strongly magnetic first phosphorus pig iron are first separated by a second magnetic separation process to obtain pure magnetically separated phosphorus pig iron blocks. Furthermore, shot blasting with grinding balls at a preset pressure of 4 MPa to 6.5 MPa can preferentially break up and peel off the lower-hardness anode carbon blocks through the impact of the grinding balls, while retaining the higher-hardness phosphorus pig iron. This optimizes the interface distribution of the phosphorus pig iron and reduces the interfacial bonding strength between the residual anode carbon blocks and the phosphorus pig iron on the surface of the phosphorus pig iron, facilitating subsequent processing in the melting stage.

[0083] The preset pressure may be 4 MPa, 4.5 MPa, 5.0 MPa, 5.5 MPa, 6.0 MPa or 6.5 MPa.

[0084] In some optional embodiments, the diameter of the grinding balls is 0.8 mm to 1.2 mm.

[0085] In these embodiments, the grinding balls with a diameter of 0.8 mm to 1.2 mm can play a good impact role, preferentially crushing and peeling the anode carbon blocks with lower hardness while retaining the phosphorus pig iron with higher hardness, thereby reducing the residual sulfur element on the surface of the phosphorus pig iron.

[0086] The diameter of the grinding balls may be 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm or 1.2 mm.

[0087] In some optional embodiments, the shot blasting treatment lasts for 20 to 25 minutes.

[0088] In these embodiments, the shot blasting treatment lasting 20 to 25 minutes can ensure that the grinding balls have sufficient impact time, so that the anode carbon blocks and the phosphorus pig iron can be effectively separated, thereby reducing the residual sulfur element on the surface of the phosphorus pig iron.

[0089] The shot blasting time can be 20 min, 21 min, 22 min, 23 min, 24 min or 25 min.

[0090] In some optional embodiments, the target size of the crushing process is ≤100 mm.

[0091] In these embodiments, the crushing process with a target size of ≤100 mm can effectively break up the sharp corners of the phosphorus pig iron ring, significantly increasing the specific surface area of ​​the phosphorus pig iron, thereby exposing more of the interface covered by the anode carbon block. In addition, the phosphorus pig iron blocks obtained by this crushing process are less likely to be removed from the attached anode carbon block.

[0092] In some optional embodiments, the magnetic field strengths of the first magnetic separation, the second magnetic separation, and the third magnetic separation are all 1.4T to 1.6T.

[0093] In these embodiments, the first magnetic separation, the second magnetic separation and the third magnetic separation at 1.4T to 1.6T can not only separate the non-magnetic anode carbon blocks from the magnetic flow channel, but also enable the strongly magnetic phosphorus pig iron to have sufficient kinetic energy during the magnetic separation process, so that the phosphorus pig iron has sufficient power to enter the subsequent processing flow.

[0094] The magnetic field strengths of the first magnetic separation, the second magnetic separation, and the third magnetic separation may all be 1.4T, 1.45T, 1.50T, 1.55T, or 1.60T.

[0095] It should be noted that the magnetic field strength of the first magnetic separation, the second magnetic separation and the third magnetic separation can also ensure that the amount of phosphorus pig iron processed each time is within a reasonable range, avoiding the extension of the melting time due to too little phosphorus pig iron, and avoiding the entrainment of unnecessary impurities due to too much phosphorus pig iron.

[0096] In some optional embodiments, melting the third phosphorus pig iron block to obtain a phosphorus pig iron melt comprises the steps of:

[0097] S401. The third phosphorus pig iron block is preheated to obtain a preheated phosphorus pig iron block;

[0098] S402. Melt the preset phosphorus pig iron solution to obtain a phosphorus pig iron melt.

[0099] In these embodiments, the third phosphorus pig iron block is preheated before melting to remove moisture and combustible impurities from the third phosphorus pig iron, thereby ensuring the purity of the phosphorus pig iron melt in the subsequent melting stage.

[0100] In some optional embodiments, the preheating temperature is 300° C. to 450° C., and the preheating time is 30 min to 40 min.

[0101] In these embodiments, a preheating temperature of 300°C to 450°C for 30 to 40 minutes can sufficiently preheat the third phosphorus pig iron and remove moisture and flammable impurities from the third phosphorus pig iron. Furthermore, this preheating can reduce the required heating requirements for melting-related equipment, preventing cracking or damage to the melting equipment due to significant temperature differences.

[0102] The preheating temperature may be 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, 360°C, 370°C, 380°C, 390°C, 400°C, 410°C, 420°C, 430°C, 440°C or 450°C.

[0103] The preheating time can be 30 min, 31 min, 32 min, 33 min, 34 min, 35 min, 36 min, 37 min, 38 min, 39 min or 40 min.

[0104] In some optional embodiments, the superheat degree of the casting is 150°C to 250°C.

[0105] In these embodiments, the casting molding with a superheat of 150° C. to 250° C. can allow the phosphorus pig iron melt to be quickly cooled and molded to form a recycled phosphorus pig iron product with uniformly distributed components.

[0106] The superheat degree of the casting can be 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C or 250°C.

[0107] Figure 3 The following is a schematic diagram showing the logical structure of a system for recycling phosphorus pig iron from an electrolytic aluminum anode group provided by an embodiment of the present application;

[0108] Based on a general inventive concept, such as Figure 3 As shown, an embodiment of the present application provides a system for recycling phosphorus pig iron from an electrolytic aluminum anode group, the system being adapted to the method, and the system comprising:

[0109] The pre-processing unit includes a depressor 1, a crusher 2, a shot blasting machine 3, and multiple magnetic separation devices 4. The discharge port of the depressor 1 is connected to the feed port of the crusher 2, and the discharge port of the crusher 2 is connected to the feed port of the shot blasting machine 3. The magnetic separation devices 4 are respectively arranged between the depressor 1 and the crusher 2, between the crusher 2 and the shot blasting machine 3, and at the discharge port of the shot blasting machine 3.

[0110] The melting part includes a melting furnace 5 and a pouring mold 6 . The discharge port of the shot blasting machine 3 is connected to the feed port of the melting furnace 5 , and the pouring mold 6 is arranged at the liquid outlet of the melting furnace 5 .

[0111] The system is implemented based on the above method. The specific steps of the method can refer to the above embodiments. Since the system adopts part or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be described one by one here.

[0112] It should be noted that the melting furnace 5 can be divided into a preheating area and a melting area according to needs. The preheating area can effectively remove moisture and flammable impurities from the third phosphorus pig iron block to improve the purity of the preheated phosphorus pig iron block; while the melting area can promote the conversion of the preheated phosphorus pig iron block into phosphorus pig iron melt to facilitate the adjustment of the composition of the phosphorus pig iron melt in the melting stage.

[0113] The present application is further described below with reference to specific examples. Experimental methods in the following examples where specific conditions are not specified are generally measured in accordance with national / industry standards. If there are no corresponding national / industry standards, the methods are carried out in accordance with commonly used international standards, conventional conditions, or conditions recommended by the manufacturer.

[0114] Example 1

[0115] like Figure 2 As shown, a method for recycling phosphorus pig iron from an electrolytic aluminum anode group, wherein the phosphorus pig iron exists in the form of phosphorus pig iron rings, and an anode carbon block is attached to the surface of the phosphorus pig iron ring, and the anode carbon block contains sulfur. The method comprises:

[0116] S1. The phosphorus pig iron rings are sequentially subjected to a first magnetic separation and crushing process to obtain a first phosphorus pig iron block having an anode carbon block;

[0117] S201. The first phosphorus pig iron block having an anode carbon block is subjected to a second magnetic separation to obtain a magnetically separated phosphorus pig iron block;

[0118] S202. The magnetically separated phosphorus pig iron is shot blasted with grinding balls as a grinding medium under preset pressure conditions to remove the anode carbon blocks on the surface of the magnetically separated phosphorus pig iron block to obtain a second phosphorus pig iron block;

[0119] S3. The second phosphorus pig iron block is subjected to a third magnetic separation to obtain a third phosphorus pig iron block;

[0120] S401. The third phosphorus pig iron block is preheated to obtain a preheated phosphorus pig iron block;

[0121] S402. The preset phosphorus pig iron solution is melted to obtain a phosphorus pig iron melt;

[0122] S5. Casting the phosphorus pig iron melt to obtain a phosphorus pig iron ring.

[0123] The preset pressure of the shot blasting process is 4 MPa. The diameter of the grinding balls is 0.8 mm. The shot blasting time is 25 minutes.

[0124] The target size of the crushing process is ≤100mm.

[0125] The magnetic field strength of the first magnetic separation, the second magnetic separation and the third magnetic separation is 1.5T.

[0126] The preheating temperature is 300°C and the preheating time is 30 minutes.

[0127] The superheat degree of casting is 150℃.

[0128] like Figure 3 As shown, a system for recycling phosphorus pig iron from an electrolytic aluminum anode group and a method for system adaptation, the system comprising:

[0129] The pre-processing section includes a press 1, a crusher 2, a shot blasting machine 3, and multiple magnetic separation devices 4. The discharge port of the press 1 is connected to the feed port of the crusher 2, and the discharge port of the crusher 2 is connected to the feed port of the shot blasting machine 3. The magnetic separation devices 4 are respectively arranged between the press 1 and the crusher 2, between the crusher 2 and the shot blasting machine 3, and at the discharge port of the shot blasting machine 3.

[0130] The melting part includes a melting furnace 5 and a pouring mold 6 . The discharge port of the shot blasting machine 3 is connected to the feed port of the melting furnace 5 , and the pouring mold 6 is arranged at the liquid outlet of the melting furnace 5 .

[0131] Example 2

[0132] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0133] The preset pressure is 4.5MPa.

[0134] The diameter of the grinding balls is 1.0 mm.

[0135] The shot blasting time is 24 minutes.

[0136] The target size of the crushing process is ≤100mm.

[0137] The magnetic field strength of the first magnetic separation, the second magnetic separation and the third magnetic separation is 1.4T.

[0138] The preheating temperature is 340°C and the preheating time is 33 minutes.

[0139] The superheat degree of casting is 175℃.

[0140] Example 3

[0141] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0142] The preset pressure for shot blasting is 3.8 MPa.

[0143] Example 4

[0144] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0145] The shot blasting time is 15 minutes.

[0146] Example 5

[0147] Compared with Example 1, this embodiment has the following differences, and the rest are the same:

[0148] The preset pressure is 6.5MPa.

[0149] The diameter of the grinding balls is 0.9 mm.

[0150] The shot blasting time is 20 minutes.

[0151] The target size of the crushing process is ≤100mm.

[0152] The magnetic field strength of the first magnetic separation, the second magnetic separation and the third magnetic separation is 1.6T.

[0153] The preheating temperature is 450°C and the preheating time is 40 minutes.

[0154] The superheat degree of casting is 250℃.

[0155] Comparative Example 1

[0156] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0157] The phosphorus pig iron ring is directly placed in the drum, and the residual anode carbon blocks adhering to the surface of the phosphorus pig iron ring are removed by relying on the friction and collision force generated by the mutual rolling of the phosphorus pig iron blocks loaded therein.

[0158] Then the phosphorus pig iron rings from which the anode carbon blocks have been removed are directly loaded into a melting furnace for melting, so as to realize the remelting and recycling of the phosphorus pig iron rings.

[0159] Comparative Example 2

[0160] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0161] The molten phosphorus pig iron is fully melted and desulfurized at 1400-1450°C. A common blowing method is used to blow a mixed powder of CaO, CaF2 and SiO2 into the molten iron for desulfurization, thereby obtaining a phosphorus pig iron molten iron with a low sulfur content for recycling.

[0162] Comparative Example 3

[0163] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0164] The shot blasting air pressure is 3.8MPa.

[0165] Comparative Example 4

[0166] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0167] The preset pressure is 7.5MPa.

[0168] Comparative Example 5

[0169] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0170] The shot blasting time is 15 minutes.

[0171] Comparative Example 6

[0172] Compared with Example 1, the differences of this comparative example are as follows, and the rest are the same:

[0173] The target size of the crushing process is greater than 100 mm and less than or equal to 130 mm.

[0174] Related experiments and effect data:

[0175] The actual sulfur content of the phosphorus pig iron melt before casting and the initial sulfur content of the added phosphorus pig iron rings or recycled phosphorus pig iron were calculated for each of the examples and comparative examples. The increase in sulfur content of the recovered phosphorus pig iron was calculated, where increase in sulfur content = (actual sulfur content - initial sulfur content) / initial sulfur content. The results are shown in Table 1.

[0176] Table 1 Changes in sulfur content of phosphorus pig iron in various embodiments and comparative examples

[0177]

[0178] As can be seen from Table 1, the embodiment of the present application provides a method for recovering phosphorus pig iron from an electrolytic aluminum anode group. This method achieves step-by-step removal of sulfur through a multi-stage cascade control of "interface stripping - magnetic purification - thermodynamic migration", thereby avoiding sulfur enrichment in the phosphorus pig iron during the melting stage, and effectively reducing the increase in the final sulfur content to below 5%, thereby effectively reducing the degree of sulfur enrichment in the phosphorus pig iron.

[0179] Compared with Example 1, Comparative Example 1 uses the traditional roller treatment method for treatment, which cannot effectively remove the anode carbon blocks attached to the surface of the phosphorus pig iron ring, which causes the sulfur content of the phosphorus pig iron melt after melting to continue to increase.

[0180] Compared with Example 1, although Comparative Example 2 also uses desulfurization treatment on the basis of traditional drum treatment, it is difficult to effectively remove the surface anode carbon blocks of the phosphorus pig iron ring and the bound sulfur content of the phosphorus pig iron during the desulfurization treatment stage, resulting in a continuous increase in the sulfur content of the phosphorus pig iron melt after final melting.

[0181] Compared to Example 1, the preset blasting air pressure in Comparative Example 3 was lower, resulting in insufficient impact force from the grinding balls during the blasting process. This affected the removal of the anode carbon blocks from the surface of the phosphorus pig iron rings and led to a continuous increase in the sulfur content of the final melted phosphorus pig iron. Furthermore, Comparative Example 4 used a higher preset pressure, which provided sufficient impact force for the grinding balls. While this improved the removal of the anode carbon blocks from the surface of the phosphorus pig iron rings, the high impact force resulted in loss of the phosphorus pig iron, with noticeable impact pits visible on the treated phosphorus pig iron surface.

[0182] Compared to Example 1, Comparative Examples 5 and 6, respectively, used shorter shot blasting times and larger phosphorus pig iron blocks after treatment. This resulted in insufficient removal of the anode carbon blocks from the phosphorus pig iron rings. These residual anode carbon blocks interfered with the melting process, increasing the sulfur content of the final molten phosphorus pig iron melt. Furthermore, Comparative Example 8 used a longer shot blasting time, resulting in direct interaction between the grinding balls and the phosphorus pig iron after the anode carbon blocks had been removed, leading to phosphorus pig iron loss.

[0183] In summary, the embodiments of the present application provide a method for recycling phosphorus pig iron from an electrolytic aluminum anode group. This method achieves step-by-step removal of sulfur through multi-stage cascade control of "interface stripping-magnetic purification-thermodynamic migration", thereby avoiding sulfur enrichment in the phosphorus pig iron during the melting stage, and effectively reducing the increase in the final sulfur content to below 5%, thereby effectively reducing the degree of sulfur enrichment in the phosphorus pig iron.

[0184] In addition, the embodiment of the present application provides a method for recycling phosphorus pig iron from an electrolytic aluminum anode group. This method can effectively avoid the enrichment of sulfur in the phosphorus pig iron recovery and utilization stage, eliminate the many hazards caused by excessive sulfur in the phosphorus pig iron, and ensure that the recovered phosphorus pig iron meets the usage level of electrolytic aluminum. In addition, the application operation of this method is simple and easy to master.

[0185] In addition, the embodiment of the present application provides a method for recycling and utilizing phosphorus pig iron from an electrolytic aluminum anode group. This method can solve the common problem of continuous enrichment of sulfur in phosphorus pig iron used for casting electrolytic aluminum anodes, while also eliminating the many hazards caused by excessive sulfur to electrolytic aluminum. It can greatly reduce the material waste in the desulfurization link of the recycled phosphorus pig iron smelting and the impact of impurities generated by desulfurization on the environment.

[0186] The foregoing is merely a detailed description of the present invention, intended to enable those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein, but rather is intended to conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for recycling phosphorus pig iron from an electrolytic aluminum anode group, wherein the phosphorus pig iron is in the form of a phosphorus pig iron ring, and an anode carbon block is attached to the surface of the phosphorus pig iron ring, wherein the anode carbon block contains sulfur. The method comprises: The phosphorus pig iron ring is subjected to a first magnetic separation and crushing process in sequence to obtain a first phosphorus pig iron block having an anode carbon block; subjecting the first phosphorus pig iron block having the anode carbon block to a second magnetic separation and a shot blasting treatment in sequence to remove the anode carbon block on the surface of the phosphorus pig iron block, thereby obtaining a second phosphorus pig iron block; subjecting the second phosphorus pig iron block to a third magnetic separation to obtain a third phosphorus pig iron block; melting the third phosphorus pig iron block to obtain a phosphorus pig iron melt; The phosphorus pig iron melt is cast into a shape to obtain a phosphorus pig iron ring.

2. The method according to claim 1, characterized in that The method of sequentially subjecting the first phosphorus pig iron block having the anode carbon block to a second magnetic separation and a shot blasting treatment to remove the anode carbon block on the surface of the phosphorus pig iron block to obtain a second phosphorus pig iron block comprises the following steps: subjecting the first phosphorus pig iron block with the anode carbon block to a second magnetic separation to obtain a magnetically separated phosphorus pig iron block; Shot blasting the magnetically separated phosphorus pig iron using grinding balls as grinding media under preset pressure conditions to remove anode carbon blocks on the surface of the magnetically separated phosphorus pig iron block to obtain a second phosphorus pig iron block; Wherein, the preset pressure is 4MPa to 6.5MPa.

3. The method according to claim 2, characterized in that The diameter of the grinding balls is 0.8 mm to 1.2 mm.

4. The method according to claim 1 or 2, characterized in that The shot blasting treatment time is 20 minutes to 25 minutes.

5. The method according to claim 1, wherein The target size of the crushing process is ≤100 mm.

6. The method according to claim 1, characterized in that The magnetic field strengths of the first magnetic separation, the second magnetic separation, and the third magnetic separation are all 1.4T to 1.6T.

7. The method according to claim 1, characterized in that The step of melting the third phosphorus pig iron block to obtain a phosphorus pig iron melt comprises the following steps: preheating the third phosphorus pig iron block to obtain a preheated phosphorus pig iron block; The preset phosphorus pig iron solution is melted to obtain a phosphorus pig iron melt.

8. The method according to claim 7, characterized in that The preheating temperature is 300° C. to 450° C., and the preheating time is 30 min to 40 min.

9. The method according to claim 1, characterized in that The superheat degree of the casting molding is 150°C to 250°C.

10. A system for recycling phosphorus pig iron from an electrolytic aluminum anode group, the system being adapted to the method according to any one of claims 1 to 9, the system comprising: The pre-processing unit includes a press, a crusher, a shot blasting machine, and a plurality of magnetic separation devices. The discharge port of the press is connected to the feed port of the crusher, and the discharge port of the crusher is connected to the feed port of the shot blasting machine. The magnetic separation devices are respectively arranged between the press and the crusher, between the crusher and the shot blasting machine, and at the discharge port of the shot blasting machine. The melting part includes a melting furnace and a pouring mold. The discharge port of the shot blasting machine is connected to the feed port of the melting furnace, and the pouring mold is arranged at the liquid outlet of the melting furnace.

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