A phosphorus pig iron stabilizer for aluminum electrolysis, its preparation method and application

Abstract

This application discloses a phosphorus pig iron stabilizer for aluminum electrolysis. The stabilizer has a core-shell structure, comprising an improver as the core, a desulfurizing agent as the first outer shell coated on the improver, and a carbonizing agent as the second outer shell coated on the first outer shell. The improver includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide. The phosphorus pig iron stabilizer disclosed in this application can effectively solve the elemental imbalance problem during the reuse of phosphorus pig iron and improve various problems caused by elemental imbalance.

Description

Technical Field

[0001] This application relates to the field of aluminum electrolysis technology, and in particular to a phosphorus pig iron stabilizer for aluminum electrolysis, its preparation method and application. Background Technology

[0002] Phosphorus pig iron is a special type of pig iron, mainly used in the anode assembly process of aluminum electrolysis. It uses a casting process to firmly connect the anode carbon block to the steel claws. During repeated use, phosphorus pig iron experiences an imbalance in its elemental composition, primarily manifested as the loss of elements such as carbon, silicon, and manganese, and the enrichment of elements such as phosphorus and sulfur. This imbalance can lead to a series of serious consequences, such as cracking and breakage of the iron rings formed after casting, weak bonding between the iron rings and steel claws, abnormally high iron-carbon voltage drop, unbalanced anode current distribution in the electrolytic cell, decreased anode assembly quality, and fluctuations in electrolytic cell operation.

[0003] Currently, technologies for improving pig iron phosphate typically only address the issues of carbon increase and desulfurization, but cannot effectively solve the problem of imbalances in other elements. Summary of the Invention

[0004] This application provides a phosphorus pig iron stabilizer for aluminum electrolysis, its preparation method, and its application, which solves one of the technical problems of elemental imbalance in phosphorus pig iron during repeated use.

[0005] A first aspect of this application provides a phosphorus pig iron stabilizer for aluminum electrolysis. The phosphorus pig iron stabilizer for aluminum electrolysis has a core-shell structure, which includes an improver as the core, a desulfurizer as the first shell coated on the improver, and a carbonizer as the second shell coated on the first shell. The improver includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide.

[0006] Optionally, the desulfurizing agent includes one or more of limestone, high-carbon ferromanganese, light magnesium oxide, calcium-silicon manganese, and calcium-silicon.

[0007] Optionally, the carbon raiser includes carbonaceous carbon raisers and / or graphitic carbon raisers. The carbonaceous carbon raiser includes one or more of calcined petroleum coke carbon raisers, pitch coke carbon raisers, metallurgical coke carbon raisers, and calcined anthracite carbon raisers. The graphitic carbon raiser includes one or more of graphitized carbon raisers, natural graphite, and waste cathode carbon blocks.

[0008] Optionally, the particle size of the phosphorus pig iron stabilizer for aluminum electrolysis is 1 mm to 6 mm, the particle size of the core is 0.1 mm to 0.63 mm, the thickness of the first shell is 0.18 mm to 1.11 mm, and the thickness of the second shell is 0.22 mm to 1.26 mm.

[0009] Optionally, the improver in the core is in particulate form, and the particle size D50 of the improver is 200 μm to 500 μm; and / or, The desulfurizing agent in the first outer shell is in granular form, and the particle size D50 of the desulfurizing agent is 200 μm to 1000 μm; and / or, The carbon raiser in the second shell is in granular form, and the particle size D50 of the carbon raiser powder is 200 μm to 1500 μm.

[0010] Optionally, the mass ratio of the carbon raiser, the desulfurizer and the improver in the phosphorus pig iron stabilizer for aluminum electrolysis is (1.5~7):(2~6):(0.2~2).

[0011] A second aspect of this application provides a method for preparing a phosphorus pig iron stabilizer for aluminum electrolysis according to any embodiment of the first aspect, comprising the following steps: The method provides an improver powder, a desulfurizer powder, and a carbon raiser powder; the improver powder is shaped to form the core; the desulfurizer powder is coated on the surface of the core to form the first shell; and the carbon raiser powder is coated on the surface of the first shell to form the second shell; wherein the improver includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide.

[0012] Optionally, the particle size D50 of the improver powder is 200 μm to 500 μm, and / or, The particle size D50 of the desulfurizing agent powder is 200 μm to 1000 μm, and / or, The particle size D50 of the carbon raiser powder is 200 μm to 1500 μm.

[0013] Optionally, the coating method includes fluidized bed coating or disc granulation.

[0014] A third aspect of this application provides the application of a phosphorus pig iron stabilizer for aluminum electrolysis prepared according to any embodiment of the first aspect or the preparation method described in any embodiment of the second aspect in the casting of aluminum electrolysis anodes.

[0015] Optionally, the aluminum electrolytic anode casting includes a molten iron smelting process and a molten iron transfer process. The aluminum electrolytic pig iron stabilizer is added to the molten iron in the molten iron smelting process and / or the molten iron transfer process for inoculation. The weight ratio of the aluminum electrolytic pig iron stabilizer to the molten iron is 1:(20~68).

[0016] Optionally, the incubation temperature is 1350℃~1550℃, and the incubation time is 10 min~30 min.

[0017] Compared with the prior art, the technical solution provided in this application has the following beneficial effects: The phosphorus pig iron stabilizer for aluminum electrolysis disclosed in this application has a core-shell structure. This structure uses an improver as the core, a desulfurizer coated on the improver as the first outer shell, and a carbon raiser coated on the desulfurizer as the second outer shell. The desulfurizer reduces the sulfur content in the phosphorus pig iron, while the carbon raiser increases the carbon content. The improver includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide. This core-shell structure of the phosphorus pig iron stabilizer for aluminum electrolysis allows for the stepwise release of elements. When used as a stabilizer for pig iron phosphate, the carbon-reinforcing agent, which acts as the second outer shell in the core-shell structure, first melts to establish a carbon matrix, creating a reducing environment for the desulfurization reaction of the desulfurizing agent and preventing the oxidation loss of other elements. After carbon homogenization, the desulfurizing agent is released, which stabilizes sulfur, preventing further diffusion and reaction with the modifier. Finally, the modifier is released, supplementing various functional elements to further optimize pig iron phosphate, especially improving the imbalance of manganese and silicon, ensuring the activation of grain refinement in the later stage of iron crystallization, thereby improving the microstructure uniformity of pig iron phosphate, reducing the iron-carbon pressure drop, and optimizing the desulfurization properties. The pig iron phosphate stabilizer for aluminum electrolysis in this application can effectively solve the elemental imbalance problem in the reuse of pig iron phosphate and improve various problems caused by elemental imbalance. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and disclosure, and together with the description serve to explain the principles of this application and disclosure.

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the structure of a phosphorus pig iron stabilizer for aluminum electrolysis according to some embodiments of this application; Figure 2 This application discloses a method for preparing a phosphorus pig iron stabilizer for aluminum electrolysis, based on some embodiments thereof. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0022] In this application, except where expressly stated, any matters or issues not mentioned are directly applicable to those known in the art without any modification. Furthermore, any implementation described in this application can be freely combined with one or more other implementations described in this application, and the resulting technical solutions or concepts shall be considered part of the original disclosure or original record of this application, and should not be regarded as new content not disclosed or anticipated in this application, unless those skilled in the art consider the combination to be clearly unreasonable.

[0023] Any method steps, processes, and operations described in this application should not be construed as necessarily requiring them to be performed in a particular order as discussed or shown, unless explicitly specified. It should also be understood that additional or alternative steps may be used unless otherwise stated.

[0024] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0025] Any specific numerical values ​​disclosed herein (including the endpoints of numerical ranges) are not limited to their exact values, but should be understood to also include values ​​close to the exact value, such as all possible values ​​within ±5% of the exact value. Furthermore, with respect to the disclosed numerical ranges, one or more new numerical ranges can be obtained by arbitrarily combining the endpoint values ​​of the range, the endpoint values ​​with specific point values ​​within the range, and the specific point values ​​themselves; these new numerical ranges should also be considered as specifically disclosed herein.

[0026] Unless otherwise stated, the terms used herein have the same meaning as commonly understood by those skilled in the art, and if a term is defined herein and its definition differs from the common understanding in the art, the definition herein shall prevail.

[0027] In the aluminum electrolysis industry, the repeated use of pig iron for anode casting leads to an imbalance in elemental composition (burn-off of carbon, silicon, and manganese, and enrichment of phosphorus and sulfur). Sulfur enrichment easily forms intergranular segregation of iron sulfide (FeS), significantly reducing the toughness of the iron rings formed after casting. Under casting cooling or thermal shock in the electrolytic cell, the iron rings are prone to cracking or even breakage, leading to the detachment of the anode carbon block. The burn-off of elements such as carbon and silicon reduces the fluidity of the molten pig iron, resulting in porosity and / or shrinkage cavities on the surface of the iron rings formed after casting. This results in insufficient bonding strength between the anode carbon block and the steel claws, causing the steel claws to loosen easily during aluminum electrolysis cell operation. Phosphorus enrichment leads to uneven distribution of phosphorus in the pig iron, increasing the contact resistance at the interface between the cast iron rings and the anode carbon block, thus significantly increasing energy loss during aluminum electrolysis. Imbalances in elemental composition can lead to uneven surfaces and internal defects in the iron rings formed after casting pig iron. This results in an imbalanced anode current distribution, with excessively high local current densities, easily triggering "claw melting" (steel claw erosion). Further imbalances cause uncontrolled shrinkage of the pig iron, leading to gaps between the cast iron rings and the anode carbon blocks. This makes the anode prone to disintegration or complete detachment during aluminum electrolysis. Anode detachment or abnormal current distribution further disrupts the thermal balance and magnetic field stability of the aluminum electrolysis cell, reducing current efficiency and increasing cell control difficulty. Ultimately, this leads to increased energy consumption per ton of aluminum, more frequent anode replacements, and soaring equipment maintenance costs.

[0028] First aspect Please see Figure 1 One embodiment of this application provides a phosphorus pig iron stabilizer for aluminum electrolysis. The phosphorus pig iron stabilizer for aluminum electrolysis has a core-shell structure. The core-shell structure includes an improver as a core 1, a desulfurizing agent as a first outer shell 2 coated on the improver, and a carbonizing agent as a second outer shell 3 coated on the first outer shell 2. The improver includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide.

[0029] The phosphorus pig iron stabilizer for aluminum electrolysis in this application embodiment has a core-shell structure. This core-shell structure has an improver as the core (1), a desulfurizer coated on the improver as a first outer shell (2), and a carbon raiser coated on the desulfurizer as a second outer shell (3). The desulfurizer reduces the sulfur content in the phosphorus pig iron, and the carbon raiser increases the carbon content. The improver includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide. The core-shell structure allows for the stepwise release of elements. As a stabilizer for pig iron phosphate, the carbon-reinforcing agent in this core-shell structure first melts to establish a carbon matrix, creating a reducing environment for the desulfurization reaction of the desulfurizing agent and preventing the oxidation loss of other elements. After carbon homogenization, the desulfurizing agent is released, which stabilizes sulfur, preventing further diffusion and reaction with the modifier. Finally, the modifier is released to supplement various functional elements and further optimize pig iron phosphate, especially improving the imbalance of manganese and silicon elements. This ensures the activation of grain refinement during the later stages of iron crystallization, thereby improving the microstructure uniformity of pig iron phosphate, reducing the iron-carbon pressure drop, and optimizing the desulfurization properties. The pig iron phosphate stabilizer for aluminum electrolysis in this application can effectively solve the elemental imbalance problem during the reuse of pig iron phosphate and improve various problems caused by elemental imbalance.

[0030] Compared to traditional calcium-containing desulfurizers such as calcium oxide and limestone, high-carbon ferromanganese is stable, efficient, cost-effective, and has an alloying effect, effectively preventing "sulfur reversion" and assisting in deoxidation. Light magnesium oxide reacts rapidly, generating MnS to improve the fluidity of molten iron, and the byproduct magnesium sulfate is recyclable, making it environmentally friendly. It can also optimize slag. Silicon-calcium-manganese particles can be efficiently composited, resulting in more thorough desulfurization and shorter stabilization time. The silicon content in the alloy can lower the melting point and improve the fluidity of molten steel. Silicon-calcium particles provide stronger desulfurization, high alloy purity, and strong deoxidation, effectively purifying molten iron.

[0031] Rare earth elements have a strong affinity for oxygen and sulfur, enabling deep desulfurization and deoxidation, and eliminating oxygen sources that cause element burn-off. Compared to other rare earth elements, lanthanum oxide can also form stable lanthanum phosphate, inhibiting harmful phase transitions; cerium oxide has a strong oxygen storage capacity, continuously providing active oxidative desulfurization and deoxidation effects; yttrium oxide can refine grains, significantly improving the thermal stability and thermal shock resistance of materials; praseodymium oxide and neodymium oxide can both participate in reactions to form stable compounds, strengthening alloying and improving the overall performance of materials.

[0032] In some embodiments, the desulfurizing agent includes one or more of limestone, high-carbon ferromanganese, light magnesium oxide, calcium-silicon manganese, and calcium-silicon.

[0033] In some embodiments, the carbon raiser includes a carbonaceous carbon raiser and / or a graphitic carbon raiser.

[0034] Without limitation, carbonaceous recarburizing agents include one or more of calcined petroleum coke recarburizing agents, pitch coke recarburizing agents, metallurgical coke recarburizing agents, and calcined anthracite recarburizing agents.

[0035] Without limitation, graphitic recarburizers include one or more of graphitized recarburizers, natural graphite, and waste cathode carbon blocks.

[0036] It should be noted that waste cathode carbon blocks refer to waste cathode carbon blocks generated in the aluminum electrolysis industry.

[0037] In some embodiments, the particle size of the phosphorus pig iron stabilizer for aluminum electrolysis is 1 mm to 6 mm, the particle size of the core 1 is 0.1 mm to 0.63 mm, the thickness of the first outer shell 2 is 0.18 mm to 1.11 mm, and the thickness of the second outer shell 3 is 0.22 mm to 1.26 mm. The particle size of the phosphorus pig iron stabilizer for aluminum electrolysis affects its release rate in molten iron. The particle size of the core 1, the thickness of the first outer shell 2, and the thickness of the second outer shell 3 can regulate the release sequence and the diffusion paths of various elements. Within the above-mentioned ranges, the particle size of the core 1, the thickness of the first outer shell 2, and the thickness of the second outer shell 3 can better exert their respective functions, stabilize the performance of the phosphorus pig iron stabilizer for aluminum electrolysis, and achieve better synergistic effects.

[0038] It should be noted that the shape of the core 1 is not limited and can be spherical, square, triangular, or any irregular shape. The particle size of the core 1 refers to the length of the core 1 in the direction of its smallest dimension. When the core 1 is spherical, the particle size of the core 1 refers to the diameter of the spherical core 1; when the core 1 is square, the particle size of the core 1 refers to the side length of the square; if the core 1 is a cube, the particle size of the core 1 is the side length of the cube; if the core 1 is a cuboid, the particle size of the core 1 is the shortest side length of the cuboid; when the core 1 is triangular, the particle size of the core 1 refers to the perpendicular distance from the plane of the triangle to the opposite parallel plane; when the core 1 is any irregular shape, the particle size of the core 1 refers to the minimum parallel plate spacing that can completely enclose the core 1, i.e., the minimum reading obtained by caliper measurement. The particle size of the core 1, the thickness of the first outer shell 2, and the thickness of the second outer shell 3 can all be obtained by caliper measurement.

[0039] Understandably, the particle size of the phosphorus pig iron stabilizer for aluminum electrolysis can be 1 mm, 1.88 mm, 2 mm, 2.30 mm, 2.81 mm, 3 mm, 3.47 mm, 4 mm, 4.76 mm, 5 mm, 6 mm, and any value between them or any range between any two values.

[0040] Understandably, the particle size of kernel 1 can be 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.35 mm, 0.45 mm, 0.55 mm, 0.58 mm, 0.61 mm, 0.62 mm, 0.63 mm, or any value between them or any range between any two values.

[0041] Understandably, the thickness of the first outer shell 2 can be 0.18 mm, 0.40 mm, 0.61 mm, 0.75 mm, 0.89 mm, 0.96 mm, 1.02 mm, 1.04 mm, 1.06 mm, 1.08 mm, 1.10 mm, 1.11 mm, or any value between them or a range between any two values.

[0042] Understandably, the thickness of the second outer shell 3 can be 0.22mm, 0.23mm, 0.25mm, 0.27mm, 0.29mm, 0.35mm, 0.53mm, 0.96mm, 1.10mm, 1.15mm, 1.20mm, 1.26mm, or any value between them or a range between any two values.

[0043] In some embodiments, the improver powder used in the core is granular, with a particle size D50 of 200 μm to 500 μm. The core is composed of improver powder particles, and the phosphorus pig iron stabilizer prepared with the improver powder particle size D50 within this range exhibits better stabilizing effect. If the improver powder particle size D50 is too small, the improver melts too quickly, resulting in severe burn-off of related elements, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron. If the improver powder particle size D50 is too large, the improver melts late, and related elements coarsen, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron.

[0044] In some embodiments, the desulfurizing agent in the first shell is granular, and the particle size D50 of the desulfurizing agent powder is 200 μm to 1000 μm. The first shell is composed of desulfurizing agent powder particles, and the phosphorus pig iron stabilizer for aluminum electrolysis prepared with a particle size D50 within this range has a better stabilizing effect. If the particle size D50 of the desulfurizing agent powder is too small, the desulfurizing agent melts too quickly, and the relevant elements are severely burned, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and thus affecting the function of the phosphorus pig iron. If the particle size D50 of the desulfurizing agent powder is too large, the desulfurizing agent melts late, and the relevant elements are coarsened, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and thus affecting the function of the phosphorus pig iron.

[0045] In some embodiments, the carbon raiser in the second shell is granular, and the particle size D50 of the carbon raiser powder is 200 μm to 1500 μm. The second shell is composed of carbon raiser particles, and the phosphorus pig iron stabilizer for aluminum electrolysis prepared with a carbon raiser powder particle size D50 within this range has a better stabilizing effect. If the particle size D50 of the carbon raiser powder is too small, the carbon raiser melts too quickly, and related elements are severely burned, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and thus affecting the function of the phosphorus pig iron. If the particle size D50 of the carbon raiser powder is too large, the carbon raiser melts late, and related elements coarsen, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and thus affecting the function of the phosphorus pig iron.

[0046] In some embodiments, the mass ratio of carbon raiser, desulfurizer, and improver in the phosphorus pig iron stabilizer for aluminum electrolysis is (1.5~7):(2~6):(0.2~2). Within this range, the mass ratio of carbon raiser, desulfurizer, and improver in the phosphorus pig iron stabilizer for aluminum electrolysis can further regulate the release timing and diffusion paths of various elements, achieving better synergistic effects.

[0047] Understandably, the mass ratio of carbon raiser, desulfurizer, and improver in the phosphorus pig iron stabilizer for aluminum electrolysis can be 1.5:2:0.2, 1.5:6:0.2, 1.5:2:2, 1.5:6:2, 7:2:0.2, 7:6:2, 7:2:0.2, 7:2:2, 7:6:0.2, 2:2:1, 4:2.8:1, 6:3:1, 7:2:1, 5:4:1, and any ratio or range between these ratios. In some optional embodiments, the mass ratio of carbon raiser, desulfurizer, and improver in the phosphorus pig iron stabilizer for aluminum electrolysis is (2~7):(1.4~4):1.

[0048] Second aspect like Figure 2 As shown, one embodiment of this application provides a method for preparing a phosphorus pig iron stabilizer for aluminum electrolysis according to any embodiment of the first aspect described above, comprising the following steps: S1 provides additive powder, desulfurizer powder and carbon raiser powder; S2, The modifier powder is shaped to form the core 1; S3, coating the desulfurizing agent powder onto the surface of the core 1 to form the first outer shell 2; and S4, the carbon raiser powder is coated on the surface of the first outer shell 2 to form the second outer shell 3; The modifiers include one or more of the following: ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide.

[0049] In some embodiments, the particle size D50 of the modifier powder is 200 μm to 500 μm. A phosphorus pig iron stabilizer for aluminum electrolysis prepared with a particle size D50 within this range exhibits better stabilizing effects. If the particle size D50 of the modifier powder is too small, the modifier melts too quickly, resulting in severe burn-off of relevant elements, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron. If the particle size D50 of the modifier powder is too large, the modifier melts late, and relevant elements coarsen, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron.

[0050] In some embodiments, the particle size D50 of the desulfurizing agent powder is 200 μm to 1000 μm. A phosphorus pig iron stabilizer for aluminum electrolysis prepared with a particle size D50 within this range exhibits better stabilizing effects. If the particle size D50 of the desulfurizing agent powder is too small, the desulfurizing agent melts too quickly, resulting in severe burn-off of relevant elements, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron. If the particle size D50 of the desulfurizing agent powder is too large, the desulfurizing agent melts late, and relevant elements coarsen, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron.

[0051] In some embodiments, the particle size D50 of the carbon raiser powder is 200 μm to 1500 μm. A phosphorus pig iron stabilizer prepared with a carbon raiser powder particle size D50 within this range exhibits better stabilizing effects. If the particle size D50 of the carbon raiser powder is too small, the carbon raiser melts too quickly, resulting in severe burn-off of related elements, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron. If the particle size D50 of the carbon raiser powder is too large, the carbon raiser melts late, and related elements coarsen, affecting the stabilizing effect of the phosphorus pig iron stabilizer for aluminum electrolysis, and consequently affecting the function of the phosphorus pig iron.

[0052] In some embodiments, a binder needs to be added when molding the modifier powder. For example, the binder may include one or more of epoxy resin, polyurethane, and silane coupling agents. The amount of binder used can be conventional, intended to bind the modifier powder together without it becoming loose; for example, based on the total weight of the modifier powder that needs to be bound, the amount of binder can be 0.8% to 1.2%.

[0053] The molding process in step S2 can be at least one of pressing, extrusion rounding, disc granulation, spray granulation or 3D printing; optionally, the molding process is to rearrange and bind the powder particles together under the action of a binder, for example, the molding process is disc granulation.

[0054] In some implementations, the coating method includes fluidized bed coating or disc granulation.

[0055] Fluidized bed coating refers to the process of suspending the particles to be coated in a fluidized state using an upward airflow, and then atomizing and spraying a coating liquid (a liquid formed by desulfurizing agent powder or carbon raiser powder and binder) into the fluidized bed. The droplets contact the surface of the particles to be coated, spread, and dry to form a uniform coating layer. The binder used in the fluidized bed coating method is the same as described above and will not be repeated here. The amount of binder used in the fluidized bed coating method is the conventional amount, the purpose of which is to bind the desulfurizing agent powder or carbon raiser powder together and prevent it from falling apart. For example, based on the total weight of the desulfurizing agent powder or carbon raiser powder that needs to be bound, the amount of binder can be 0.8% to 1.2%.

[0056] Disc granulation refers to placing the particles to be coated (core) and powdered coating material (desulfurizer powder or carbon raiser powder) in an inclined rotating disc (or drum). By spraying in an adhesive or utilizing the wettability of the powder itself, the powder gradually coats the core surface, forming coated particles. The adhesive used in disc granulation is the same as described above and will not be repeated here. The amount of adhesive used in disc granulation is conventional, intended to bind the desulfurizer powder or carbon raiser powder together without loosening. For example, based on the total weight of the desulfurizer powder or carbon raiser powder requiring bonding, the amount of adhesive can be 0.8% to 1.2%.

[0057] The preparation method of the phosphorus pig iron stabilizer for aluminum electrolysis is based on the above-mentioned phosphorus pig iron stabilizer for aluminum electrolysis. Its specific characteristics can be referred to the above embodiments. Since the preparation method of the phosphorus pig iron stabilizer for aluminum electrolysis adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0058] Third aspect One embodiment of this application provides the application of the phosphorus pig iron stabilizer for aluminum electrolysis provided by any embodiment of the first aspect above, or the phosphorus pig iron stabilizer for aluminum electrolysis prepared by any preparation method provided by any embodiment of the second aspect above, in the casting of aluminum electrolysis anodes.

[0059] In some embodiments, the casting of aluminum electrolytic anodes includes a molten iron smelting process and a molten iron transfer process. A phosphorus pig iron stabilizer for aluminum electrolysis is added to the phosphorus pig iron in the molten iron smelting process and / or the molten iron transfer process for inoculation. The weight ratio of the phosphorus pig iron stabilizer for aluminum electrolysis to the phosphorus pig iron is 1:(20~68).

[0060] In some implementations, the inoculation temperature is 1350℃~1550℃, and the inoculation time is 10 min~30 min. If the inoculation temperature is too low, the carbon raiser will not melt completely, affecting the performance of the pig iron. If the inoculation temperature is too high, carbon will burn off, and rare earth oxides will volatilize severely, failing to provide a stabilizing effect. If the inoculation time is too short, the various elements will not have enough time to be released, failing to provide a stabilizing effect. If the inoculation time is too long, carbon will burn off severely, and the desulfurizer will react prematurely, reacting with rare earth oxides and affecting the performance of the pig iron.

[0061] Understandably, the incubation temperature is 1350 ℃, 1400 ℃, 1450 ℃, 1500 ℃, 1550 ℃, and any value between them or any range between any two values.

[0062] Understandably, the incubation time is 10 min, 15 min, 20 min, 25 min, 30 min, and any value between them or any range between any two values.

[0063] The application of this aluminum electrolysis iron-phosphorus stabilizer in aluminum electrolysis anode casting is based on the preparation method of the above-mentioned aluminum electrolysis iron-phosphorus stabilizer or the aluminum electrolysis iron-phosphorus stabilizer obtained by the above-mentioned preparation method. Its specific characteristics can be referred to the above embodiments. Since the application of this aluminum electrolysis iron-phosphorus stabilizer in aluminum electrolysis anode casting adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0064] Example To better understand this application, the following description, in conjunction with embodiments, further illustrates this application. However, the scope of protection claimed in this application is not limited to the scope of the embodiments.

[0065] In the following examples, unless otherwise specified, all experimental instruments, raw materials, and quantities involved are commercially available products or can be prepared by known methods. Experimental methods not specifying particular conditions in the examples were performed under conventional conditions, such as those described in literature, books, or methods recommended by the manufacturer.

[0066] Unless otherwise specified, the specific parameters used in each step of the material preparation process in each embodiment and comparative example are the same.

[0067] Example 1 (1) Weigh the raw materials graphitization recarburizer, limestone particles, ferrosilicon particles, calcium-silicon manganese particles, yttrium oxide and cerium oxide according to Table 1.

[0068] (2) Dry each raw material to a moisture content ≤0.5%. Check and start the disc (φ600mm disc) granulation equipment. Set the parameters: atomization pressure: 0.2MPa; tilt angle: 47°; rotation speed: 20 r / min; spray speed: 8mL / min; powder speed: 12 g / min; hot air temperature: 60℃. Start the spraying and powdering device. Quantitatively sprinkle ferrosilicon particles, calcium-manganese silicon particles, yttrium oxide, and cerium oxide, while simultaneously spraying the adhesive epoxy resin to wet the surfaces of the ferrosilicon particles, calcium-manganese silicon particles, yttrium oxide, and cerium oxide, allowing the ferrosilicon particles, calcium-manganese silicon particles, yttrium oxide, and cerium oxide to quickly adhere and form a spherical improver core 1 with a diameter of 0.62mm. After the material feeding is completed, continue running for 15 min.

[0069] (3) Modify equipment parameters: rotation speed: 19 r / min; spray speed: 10 mL / min; powder speed: 14.5 g / min; hot air temperature: 65℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle limestone particles while spraying adhesive epoxy resin, coating the limestone particles on the surface of the improver core 1. After the material is fed, continue running for 25 min to obtain the precursor of phosphorus pig iron stabilizer for aluminum electrolysis with limestone particles as the first shell 2. The thickness of the first shell 2 is 0.61 mm.

[0070] (4) Modify the equipment parameters: rotation speed: 18 r / min; spray speed: 12 mL / min; powder speed: 13 g / min; hot air temperature: 70℃. Repeat the "spray-powder" cycle operation for 30 min. Quantitatively sprinkle the graphitized recarburizing agent while spraying the adhesive epoxy resin, allowing the graphitized recarburizing agent to quickly adhere to the surface of the phosphorus pig iron stabilizer precursor to form a thin layer, i.e., the second shell 3. The thickness of the second shell 3 is 0.23 mm. After the material is fed, continue running for 30 min to obtain the phosphorus pig iron stabilizer for aluminum electrolysis with a particle size of 2.30 mm.

[0071] (5) The prepared phosphorus pig iron stabilizer for aluminum electrolysis is added to the phosphorus pig iron molten iron in the phosphorus pig iron smelting furnace at 1400 ℃, and after incubation for 12 min, it is poured out at 1380 ℃. The weight ratio of phosphorus pig iron stabilizer for aluminum electrolysis to phosphorus pig iron is 1:50.

[0072] Table 1

[0073] Example 2 (1) Weigh the raw materials, including calcined petroleum coke carbonizer, high-carbon ferromanganese particles, ferrosilicon particles, calcium silicon particles and cerium oxide, according to Table 1.

[0074] (2) Dry all raw materials to a moisture content ≤0.5%. Check and start the disc (φ600mm disc) granulation equipment. Set the parameters: atomization pressure: 0.2MPa; tilt angle: 47°; rotation speed: 20 r / min; spray speed: 8mL / min; powder speed: 12 g / min; hot air temperature: 60℃. Start the spraying and powdering device. Quantitatively sprinkle ferrosilicon particles, calcium silicate particles, and cerium oxide, while simultaneously spraying epoxy resin as an adhesive to wet the surfaces of the ferrosilicon particles, calcium silicate particles, and cerium oxide, allowing the ferrosilicon particles, calcium silicate particles, and cerium oxide to quickly adhere and form a spherical improver core 1 with a diameter of 0.58mm. After the material feeding is completed, continue running for 15 min.

[0075] (3) Modify equipment parameters: rotation speed: 19 r / min; spray speed: 10 mL / min; powder speed: 14.5 g / min; hot air temperature: 65℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle high carbon manganese iron particles while spraying adhesive epoxy resin, coating the high carbon manganese iron particles on the surface of the improver core 1. After the material is fed, continue to run for 25 min to obtain the aluminum electrolysis phosphorus pig iron stabilizer precursor coated with high carbon manganese iron particles as the first shell 2. The thickness of the first shell 2 is 0.40 mm.

[0076] (4) Modify equipment parameters: rotation speed: 18 r / min; spray speed: 13 mL / min; powder speed: 13 g / min; hot air temperature: 70℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle the calcined petroleum coke recarburizer while spraying the adhesive epoxy resin, so that the calcined petroleum coke recarburizer quickly adheres to the surface of the phosphorus pig iron stabilizer precursor to form a thin layer, namely the second shell 3. The thickness of the second shell 3 is 0.25 mm. After the material is fed, continue to run for 30 min to obtain the phosphorus pig iron stabilizer for aluminum electrolysis with a particle size of 1.88 mm.

[0077] (5) Add the prepared phosphorus pig iron stabilizer to the phosphorus pig iron molten iron in the phosphorus pig iron smelting furnace at 1500 ℃, incubate for 10 min and then pour out at 1400 ℃. The weight ratio of phosphorus pig iron stabilizer to phosphorus pig iron for aluminum electrolysis is 1:33.

[0078] The specific operation methods and process parameters of the disc granulation method in steps (3) and (4) are known to those skilled in the art and can be operated under conventional conditions.

[0079] Table 2

[0080] Example 3 (1) Weigh the raw material waste cathode carbon block particles, high carbon manganese iron particles, silicon iron particles and silicon calcium manganese particles according to Table 1.

[0081] (2) Dry all raw materials to a moisture content ≤0.5%. Check and start the disc (φ600mm disc) granulation equipment. Set the parameters: atomization pressure: 0.2MPa; tilt angle: 47°; rotation speed: 20 r / min; spray speed: 10mL / min; powder speed: 18 g / min; hot air temperature: 60℃. Start the spraying and powdering device. Quantitatively sprinkle ferrosilicon particles and calcium silicate particles, while simultaneously spraying epoxy resin binder to wet the surface of the ferrosilicon particles and calcium silicate particles, allowing the ferrosilicon particles and calcium silicate particles to quickly adhere and form a spherical improver core 1 with a diameter of 0.63mm. After the material feeding is completed, continue running for 15 min.

[0082] (3) Modify equipment parameters: rotation speed: 19 r / min; spray speed: 12 mL / min; powder speed: 16.5 g / min; hot air temperature: 65℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle high carbon manganese iron particles while spraying adhesive epoxy resin, coating the high carbon manganese iron particles on the surface of the improver core 1. After the material is fed, continue to run for 25 min to obtain the aluminum electrolysis phosphorus pig iron stabilizer precursor coated with high carbon manganese iron particles as the first shell 2. The thickness of the first shell 2 is 0.89 mm.

[0083] (4) Modify equipment parameters: rotation speed: 18 r / min; spray speed: 17 mL / min; powder speed: 19 g / min; hot air temperature: 70℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle the waste cathode carbon blocks while spraying the adhesive epoxy resin, so that the waste cathode carbon blocks can quickly adhere to the surface of the phosphorus pig iron stabilizer precursor to form a thin layer, namely the second shell 3. The thickness of the second shell 3 is 0.53 mm. After the material is fed, continue to run for 30 min to obtain the phosphorus pig iron stabilizer for aluminum electrolysis with a particle size of 3.47 mm.

[0084] (5) Add the prepared phosphorus pig iron stabilizer to the phosphorus pig iron molten iron in the phosphorus pig iron smelting furnace at 1380 ℃, incubate for 15 min and then pour out at 1350 ℃. The weight ratio of phosphorus pig iron stabilizer to phosphorus pig iron for aluminum electrolysis is 1:40.

[0085] The specific operation methods and process parameters of the disc granulation method in steps (3) and (4) are known to those skilled in the art and can be operated under conventional conditions.

[0086] Table 3

[0087] Example 4 (1) Weigh the raw materials metallurgical coke carbonizer particles, limestone particles, light magnesium oxide particles and ferrosilicon particles according to Table 1.

[0088] (2) Dry all raw materials to a moisture content ≤0.5%. Check and start the disc (φ600mm disc) granulation equipment. Set the parameters: atomization pressure: 0.2MPa; tilt angle: 47°; rotation speed: 20 r / min; spray speed: 12mL / min; powder speed: 15g / min; hot air temperature: 60℃. Start the spraying and powdering device. Quantitatively sprinkle ferrosilicon particles and light magnesium oxide particles, while simultaneously spraying epoxy resin binder to wet the surface of the ferrosilicon particles and light magnesium oxide particles, allowing the ferrosilicon particles and light magnesium oxide particles to quickly adhere and form a spherical improver core 1 with a diameter of 0.62mm. After the material feeding is completed, continue running for 15 min.

[0089] (3) Modify equipment parameters: rotation speed: 19 r / min; spray speed: 15 mL / min; powder speed: 20.5 g / min; hot air temperature: 65℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle limestone particles while spraying adhesive epoxy resin, coating the limestone particles on the surface of the improver core 1. After the material is fed, continue running for 25 min to obtain the precursor of phosphorus pig iron stabilizer for aluminum electrolysis with limestone particles as the first shell 2. The thickness of the first shell 2 is 1.11 mm.

[0090] (4) Modify the equipment parameters: rotation speed: 18 r / min; spray speed: 15 mL / min; powder speed: 16 g / min; hot air temperature: 70℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle metallurgical coke recarburizing agent particles while spraying adhesive epoxy resin, so that the metallurgical coke recarburizing agent particles quickly adhere to the surface of the phosphorus pig iron stabilizer precursor to form a thin layer, namely the second shell 3. The thickness of the second shell 3 is 0.96 mm. After the material is fed, continue to run for 30 min to obtain phosphorus pig iron stabilizer for aluminum electrolysis with a particle size of 4.76 mm.

[0091] (5) The prepared phosphorus pig iron stabilizer for aluminum electrolysis is added to the molten phosphorus pig iron in the phosphorus pig iron smelting furnace at 1450 °C, and after incubation for 20 min, it is poured out at 1400 °C. The weight ratio of phosphorus pig iron stabilizer for aluminum electrolysis to phosphorus pig iron is 1:25.

[0092] Table 4

[0093] Example 5 (1) Weigh the graphitized carbon raiser particles, high carbon manganese iron particles, ferrosilicon particles, calcium silicon particles and neodymium oxide according to Table 1.

[0094] (2) Dry all raw materials to a moisture content ≤0.5%. Check and start the disc (φ600mm disc) granulation equipment. Set the parameters: atomization pressure: 0.2MPa; tilt angle: 47°; rotation speed: 20 r / min; spray speed: 8mL / min; powder speed: 12g / min; hot air temperature: 60℃. Start the spraying and powdering device. Quantitatively sprinkle ferrosilicon particles, calcium silicate particles, and neodymium oxide, while simultaneously spraying epoxy resin as an adhesive to wet the surfaces of the ferrosilicon particles, calcium silicate particles, and neodymium oxide, allowing the ferrosilicon particles, calcium silicate particles, and neodymium oxide to quickly adhere and form a spherical improver core 1 with a diameter of 0.61mm. After the material feeding is completed, continue running for 15 min.

[0095] (3) Modify equipment parameters: rotation speed: 19 r / min; spray speed: 10 mL / min; powder speed: 14.5 g / min; hot air temperature: 65℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle high carbon manganese iron particles while spraying adhesive epoxy resin, coating the high carbon manganese iron particles on the surface of the improver core 1. After the material is fed, continue to run for 25 min to obtain the aluminum electrolysis phosphorus pig iron stabilizer precursor coated with high carbon manganese iron particles as the first shell 2. The thickness of the first shell 2 is 0.75 mm.

[0096] (4) Modify equipment parameters: rotation speed: 18 r / min; spray speed: 13 mL / min; powder speed: 13 g / min; hot air temperature: 70℃. Repeat the "spray-powder" cycle operation, quantitatively sprinkle graphitized recarburizing agent particles while spraying adhesive epoxy resin, so that the graphitized recarburizing agent particles quickly adhere to the surface of the phosphorus pig iron stabilizer precursor to form a thin layer, namely the second shell 3. The thickness of the second shell 3 is 0.35 mm. After the material is fed, continue to run for 30 min to obtain phosphorus pig iron stabilizer for aluminum electrolysis with a particle size of 2.81 mm.

[0097] (5) The prepared phosphorus pig iron stabilizer for aluminum electrolysis is added to the phosphorus pig iron molten iron in the phosphorus pig iron smelting furnace at 1400 ℃, and after incubation for 10 min, it is poured out at 1350 ℃. The weight ratio of phosphorus pig iron stabilizer for aluminum electrolysis to phosphorus pig iron is 1:20.

[0098] Table 5

[0099] Comparative Example 1 The difference from Example 1 is that the graphitized carbon raiser, limestone particles, ferrosilicon particles, calcium-manganese silicon particles, yttrium oxide and cerium oxide shown in Table 1 are mixed evenly to prepare the phosphorus pig iron stabilizer for aluminum electrolysis.

[0100] Test case 1. The particle size of the core 1 of the spherical improver, the thickness of the first shell 2, the thickness of the second shell 3, and the particle size of the phosphorus pig iron stabilizer for aluminum electrolysis were measured using vernier calipers. The results are shown in Table 6.

[0101] 2. The main element content of pig iron phosphorus before and after the addition of phosphorus pig iron stabilizer for aluminum electrolysis was measured in accordance with GB / T 223.86-2009, GB / T 223.85-2009, GB / T 223.59-2008, GB / T 223.63-2022, and GB / T 223.5-2008. The results are shown in Table 6.

[0102] 3. The iron-carbon voltage drop of pig iron before and after the addition of the stabilizer for aluminum electrolysis was tested according to the laboratory precision measurement method - using a high-precision millivoltmeter to measure the voltage drop at the iron-carbon contact interface. The results are shown in Table 6.

[0103] 4. The compressive desorption properties of pig iron before and after the addition of aluminum electrolysis pig iron stabilizer were tested by applying axial pressure to the cast and cooled pig iron using a special pressure device and recording the load value at the time of fracture. The results are shown in Table 6.

[0104] Table 6

[0105] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

[0106] Although preferred embodiments have been described in this specification, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this specification.

[0107] Obviously, those skilled in the art can make various modifications and variations to this specification without departing from its spirit and scope. Therefore, if such modifications and variations fall within the scope of the claims and their equivalents, this specification is also intended to include such modifications and variations.

Claims

1. A phosphorus-based pig iron stabilizer for aluminum electrolysis, characterized in that, The phosphorus pig iron stabilizer for aluminum electrolysis has a core-shell structure, which includes an improver as the core, a desulfurizer as the first outer shell coated on the improver, and a carbon raiser as the second outer shell coated on the first outer shell. The improving agent includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide.

2. The phosphorus pig iron stabilizer for aluminum electrolysis according to claim 1, characterized in that, The desulfurizing agent includes one or more of limestone, high-carbon ferromanganese, light magnesium oxide, calcium-silicon manganese, and calcium-silicon.

3. The phosphorus pig iron stabilizer for aluminum electrolysis according to claim 1, characterized in that, The carbon raiser includes carbonaceous carbon raisers and / or graphitic carbon raisers. The carbonaceous recarburizing agent includes one or more of the following: calcined petroleum coke recarburizing agent, pitch coke recarburizing agent, metallurgical coke recarburizing agent, and calcined anthracite recarburizing agent. The graphitic carbon raiser includes one or more of graphitized carbon raisers, natural graphite, and waste cathode carbon blocks.

4. The phosphorus pig iron stabilizer for aluminum electrolysis according to claim 1, characterized in that, The particle size of the phosphorus pig iron stabilizer for aluminum electrolysis is 1 mm to 6 mm, the particle size of the core is 0.1 mm to 0.63 mm, the thickness of the first outer shell is 0.18 mm to 1.11 mm, and the thickness of the second outer shell is 0.22 mm to 1.26 mm.

5. The phosphorus pig iron stabilizer for aluminum electrolysis according to claim 4, characterized in that, The improver in the core is in particulate form, and the particle size D50 of the improver is 200μm~500μm; and / or, The desulfurizing agent in the first shell is in granular form, and the particle size D50 of the desulfurizing agent is 200 μm to 1000 μm; And / or, The carbon raiser in the second shell is in granular form, and the particle size D50 of the carbon raiser powder is 200 μm to 1500 μm.

6. The phosphorus pig iron stabilizer for aluminum electrolysis according to any one of claims 1 to 5, characterized in that, The mass ratio of the carbon raiser, the desulfurizer and the improver in the phosphorus pig iron stabilizer for aluminum electrolysis is (1.5~7):(2~6):(0.2~2).

7. A method for preparing a phosphorus pig iron stabilizer for aluminum electrolysis according to any one of claims 1 to 6, characterized in that, Includes the following steps: We provide additive powders for improving performance, desulfurizing agents, and carbon raising agents. The improver powder is subjected to molding treatment to form the core; The desulfurizing agent powder is coated onto the surface of the core to form the first outer shell; as well as The carbon raiser powder is coated onto the surface of the first outer shell to form the second outer shell; The improving agent includes one or more of ferrosilicon, calcium silicon, lanthanum oxide, cerium oxide, yttrium oxide, praseodymium oxide, and neodymium oxide.

8. The preparation method according to claim 7, characterized in that, The particle size D50 of the improver powder is 200 μm to 500 μm, and / or, The particle size D50 of the desulfurizing agent powder is 200 μm to 1000 μm, and / or, The particle size D50 of the carbon raiser powder is 200 μm to 1500 μm.

9. The application of the phosphorus pig iron stabilizer for aluminum electrolysis according to any one of claims 1 to 6, or the phosphorus pig iron stabilizer for aluminum electrolysis prepared by the preparation method according to claim 7 or 8, in the casting of aluminum electrolysis anodes.

10. The application according to claim 9, characterized in that, The aluminum electrolytic anode casting includes a molten iron smelting process and a molten iron transfer process. The aluminum electrolytic iron phosphorus stabilizer is added to the molten iron phosphorus in the molten iron smelting process and / or the molten iron transfer process for inoculation. The weight ratio of the aluminum electrolytic iron phosphorus stabilizer to the molten iron phosphorus is 1:(20~68).

11. The application according to claim 10, characterized in that, The incubation temperature is 1350℃~1550℃, and the incubation time is 10 min~30 min.

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