Preparation method of micro-consumption anode material for oxygen-aluminum co-production

Abstract

The present application belongs to the technical field of aluminum electrolysis, and particularly relates to a preparation method of micro-consumption anode material for oxygen-aluminum co-production. The anode material is a composite material composed of a metal phase and a ceramic phase, wherein the metal phase is an AlCoCrFeNi high-entropy alloy, and the content is 25%-95%, and the ceramic phase content is 5%-75%; the ceramic phase is AB2O4, wherein A is one or more of Ni, Co, Sn and Zn in any proportion combination, and B is one or more of Fe, Al, Cr and Sn in any proportion combination; the present application creatively combines high-entropy alloy with ceramic phase as the micro-consumption anode material for oxygen-aluminum co-production; thereby avoiding the failure of the anode material caused by the preferential corrosion of individual elements in the metal phase in the long-term electrolysis process; and meanwhile solving the problem of high impurity content of electrolytic aluminum.

Description

Technical Field

[0001] This invention belongs to the field of aluminum electrolysis technology, and specifically relates to a method for preparing a low-consumption anode material for oxygen-aluminum co-production. Background Technology

[0002] Most current processes for producing non-ferrous aluminum via molten salt electrolysis use carbon anode materials. This not only consumes large amounts of high-quality carbon materials but also generates significant amounts of CO2 greenhouse gases, carcinogenic asphalt fumes, acidic gases such as sulfur dioxide, and strong greenhouse gases such as carbon dioxide. n This causes serious environmental pollution. Moreover, carbon anodes have poor conductivity, low energy efficiency, and extremely high energy consumption, which are the main reasons for the high energy consumption and high cost of current aluminum electrolysis processes. Non-carbon low-consumption anodes, on the other hand, can solve the above problems and are expected to revolutionize molten salt aluminum electrolysis technology.

[0003] Three types of materials have been studied for use as inert anodes in molten salt electrolysis: oxide ceramics, alloys, and cermets. While oxide ceramics possess excellent resistance to electrolyte dissolution corrosion and nascent oxygen permeation, they suffer from low conductivity, high brittleness, poor thermal shock resistance, and difficulty in connecting to metal guide rods. Alloy anodes exhibit high strength and toughness, are suitable for large-scale, irregularly shaped equipment, are easily connected to metal guide rods, and have good conductivity. The main challenges in developing alloy anodes are reducing their corrosion rate, controlling the oxide film thickness, and ensuring their adhesion to the substrate. Ideally, cermets could combine the strong corrosion resistance of metal oxide ceramics with the good conductivity and mechanical properties of metals, overcoming the poor thermal shock resistance and difficulty in connecting to guide rods of metal oxide anodes. Furthermore, they would offer better corrosion resistance and oxidation resistance than metal or alloy anodes. However, because the currently used metal oxide ceramics have not yet achieved an ideal balance between the advantages of both metal and ceramic phases, the prepared cermet materials struggle to fully possess the advantages of both the metallic and ceramic phases simultaneously. In particular, the metallic phase corrodes preferentially, leading to high impurity content in electrolytic aluminum or anode failure. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to overcome the technical defects in the existing technology and provide a method for preparing a low-consumption anode material for oxygen-aluminum co-production.

[0005] The present invention achieves the above-mentioned technical objectives through the following technical means.

[0006] Firstly, a low-consumption anode material for oxygen-aluminum co-production is provided. This material is a composite material consisting of a metallic phase and a ceramic phase. The metallic phase is an AlCoCrFeNi high-entropy alloy with a mass fraction of 25%-95%. The ceramic phase is AB2O4, where A is one or more of Ni, Co, Sn, and Zn in any proportion, and B is one or more of Fe, Al, Cr, and Sn in any proportion. The mass fraction of the ceramic phase is 0-75%, and is not zero; preferably, it is 5%-75%.

[0007] Preferably, the high-entropy alloy comprises Al, Co, Cr, Fe, and Ni metal elements, wherein the molar ratio of Al, Co, Cr, Fe, and Ni metal elements is (0-20):(20-40):(10-25):(10:25):(20-40).

[0008] This invention also provides a method for preparing a low-consumption anode material for oxygen-aluminum co-production, comprising the following steps:

[0009] (1) Slurry preparation: The ceramic phase powder and the metal phase powder are mixed evenly in proportion to obtain a powder mixture. Then, a binder and a certain amount of water are added and stirred evenly to prepare a slurry with a solid content of 30%-70%.

[0010] (2) Granulation: The slurry obtained in step (1) is spray-granulated into granulated powder (with good flowability);

[0011] (3) Press molding: The granulated powder obtained in step (2) is loaded into a mold and pressed to obtain the molded product; the molding pressure is 150-300MPa and the molding temperature is 20-300℃.

[0012] (4) Sintering: The formed product is sintered in a nitrogen or argon atmosphere at 1000-1400℃ for 1-6 hours to obtain a dense product, which is the micro-consumption anode material for oxygen-aluminum co-production.

[0013] Furthermore, the amount of adhesive used in step (1) is 0.5%-3% of the mass of the powder mixture.

[0014] Furthermore, the solid content mentioned in step (1) is 50%-65%.

[0015] Furthermore, the pressing in step (3) is performed using warm isostatic pressing or cold isostatic pressing.

[0016] Furthermore, the oxygen content during the sintering process described in step (4) is controlled at 100-1000 ppm.

[0017] The beneficial effects of this invention are:

[0018] High-entropy alloys exhibit superior fracture resistance, tensile strength, corrosion resistance, and oxidation resistance compared to traditional alloys. However, current research on using high-entropy alloys as anode materials still fails to address the issue of high impurity content in electrolytic aluminum, failing to meet the requirements for industrially pure aluminum. This invention creatively combines a high-entropy alloy with a ceramic phase as a low-consumption anode material for oxygen-aluminum co-production. Furthermore, the combination of high-entropy alloy and ceramic phase is not a simple one; this invention optimizes their respective dosages, ensuring optimal results. Using a high-entropy alloy as the metallic phase in the anode material effectively prevents preferential dissolution of the metallic phase, especially reactive elements, and electrolyte corrosion, thereby improving anode lifespan, reducing anode consumption rate, and lowering the impurity content of the molten aluminum. The impurity content of the molten aluminum obtained by this invention is no higher than 0.4%, meeting the requirements for industrially pure aluminum (99.6%). Attached Figure Description

[0019] Figure 1 The voltage curve of the low-consumption anode electrolysis in Example 1;

[0020] Figure 2 The low-consumption anolyte electrolysis voltage curve is shown in Example 2.

[0021] Figure 3 The low-consumption anolyte electrolysis voltage curve is shown in Example 3.

[0022] Figure 4 The low-consumption anolyte electrolysis voltage curve is shown in Example 4.

[0023] in, Figure 1-4 In this context, 'a' refers to voltage and 'b' refers to temperature. Detailed Implementation

[0024] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0025] Example 1:

[0026] (1) AlCoCrFeNi high-entropy alloy powder and Ni 0.8 Co 0.2 Fe 1.5 Al 0.5 O4 ceramic powder was mixed in a ball mill for 2 hours to obtain a powder mixture. 1.5% polyvinyl alcohol by mass of the powder mixture was added as a binder, and water was added to prepare a uniformly dispersed slurry with a solid content of 60%. The mass fraction of the metal phase was 25%, and the mass fraction of the ceramic phase was 75%. The molar ratio of Al, Co, Cr, Fe, and Ni in the high-entropy alloy powder was 18:25:11:14:32.

[0027] (2) The slurry obtained in step (1) is centrifuged at 250°C to obtain granulated powder with good flowability;

[0028] (3) The granulated powder is loaded into a nitrile rubber mold and cold isostatically pressed at 250 MPa at room temperature to obtain the molded product;

[0029] (4) The formed product (i.e. the finished anode blank) is sintered at 1400℃ for 2 hours in a nitrogen atmosphere to obtain the finished anode.

[0030] The anode obtained therefrom was subjected to a 20A electrolysis experiment in a KF-NaF-AlF3-Al2O3 electrolyte system (see...). Figure 1 ), CR = 1.38, anode current density 0.6 A / cm 2 The voltage remained stable over 24 hours, with an average voltage of 3.28V, and the aluminum produced had an impurity content of 0.33%.

[0031] Example 2:

[0032] (1) AlCoCrFeNi high-entropy alloy powder and Ni 0.9 Zn 0.1 Fe 1.9 Cr 0.1 O4 ceramic powder was mixed in a ball mill for 2 hours to obtain a powder mixture. 0.6% polyvinyl alcohol by mass of the powder mixture was added as a binder, and water was added to prepare a uniformly dispersed slurry with a solid content of 45%. The mass fraction of the metal phase was 40%, and the mass fraction of the ceramic phase was 60%. The molar ratio of Al, Co, Cr, Fe, and Ni in the high-entropy alloy powder was 5:28:20:17:30.

[0033] (2) The slurry obtained in step (1) is centrifuged at 150°C to obtain granulated powder with good flowability;

[0034] (3) The granulated powder is loaded into a nitrile rubber mold and isostatically pressed at 100 MPa at 180°C to obtain the molded product.

[0035] (4) The formed product (i.e. the finished anode blank) is sintered at 1000℃ for 6 hours in a nitrogen atmosphere to obtain the finished anode.

[0036] The anode obtained therefrom was subjected to a 20A electrolysis experiment in a KF-NaF-AlF3-Al2O3 electrolyte system (see...). Figure 2 ), CR = 1.40, anode current density 0.6 A / cm 2 The voltage remained stable for 24 hours, with an average voltage of 3.22V, and the aluminum produced had an impurity content of 0.40%.

[0037] Example 3:

[0038] (1) AlCoCrFeNi high-entropy alloy powder and Ni 0.7 Sn 0.15 Co 0.15 Fe 1.5 Al 0.5 O4 ceramic powder was mixed in a ball mill for 2 hours to obtain a powder mixture. 1.5% polyvinyl alcohol by mass of the powder mixture was added as a binder, and water was added to prepare a uniformly dispersed slurry with a solid content of 38%. The mass fraction of the metal phase was 33%, and the mass fraction of the ceramic phase was 67%. The molar ratio of Al, Co, Cr, Fe, and Ni in the high-entropy alloy powder was 2:25:24:24:25.

[0039] (2) The slurry obtained in step (1) is centrifuged at 200°C to obtain granulated powder with good flowability;

[0040] (3) The granulated powder is loaded into a nitrile rubber mold and isostatically pressed at 150 MPa at 80°C to obtain the molded product.

[0041] (4) The formed product (i.e. the finished anode blank) is sintered at 1200℃ for 4 hours in a nitrogen atmosphere to obtain the finished anode.

[0042] The anode obtained therefrom was subjected to a 20A electrolysis experiment in a KF-NaF-AlF3-Al2O3 electrolyte system (see...). Figure 3 ), CR = 1.38, anode current density 0.6 A / cm 2 The voltage remained stable over 24 hours, with an average voltage of 3.34V, and the aluminum produced had an impurity content of 0.37%.

[0043] Example 4:

[0044] (1) AlCoCrFeNi high-entropy alloy powder and NiFe2O4 ceramic powder were mixed in a ball mill for 2 hours to obtain a powder mixture. 1% polyvinyl alcohol by mass of the powder mixture was added as a binder, and water was added to prepare a uniformly dispersed slurry with a solid content of 55%. The mass fraction of the metal phase was 95%, the mass fraction of the ceramic phase was 5%, and the molar ratio of Al, Co, Cr, Fe, and Ni in the high-entropy alloy powder was 20:20:20:20:20.

[0045] (2) The slurry obtained in step (1) is centrifuged at 180°C to obtain granulated powder with good flowability;

[0046] (3) The granulated powder is loaded into a nitrile rubber mold and isostatically pressed at 200 MPa at 50°C to obtain the molded product.

[0047] (4) The formed product (i.e. the finished anode blank) is sintered at 950°C for 4 hours in a nitrogen atmosphere to obtain the finished anode.

[0048] The anode obtained therefrom was subjected to a 20A electrolysis experiment in a KF-NaF-AlF3-Al2O3 electrolyte system (see...). Figure 4 ), CR = 1.4, anode current density 0.6 A / cm 2 The voltage remained stable over 24 hours, with an average voltage of 3.24V, and the aluminum produced had an impurity content of 0.38%.

[0049] Note: The above embodiments are only used to illustrate the present invention and are not intended to limit the technical solutions described in the present invention. Therefore, although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the present invention. All technical solutions and improvements that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A low-consumption anode material for oxygen-aluminum co-production, characterized in that, The anode material is a composite material consisting of a metallic phase and a ceramic phase, wherein the metallic phase is an AlCoCrFeNi high-entropy alloy with a mass fraction of 25%-95%; the ceramic phase is AB2O4, wherein A is one or more of Ni, Co, Sn, and Zn in any proportion, and B is one or more of Fe, Al, and Cr in any proportion; the mass fraction of the ceramic phase is 5%-75%. The high-entropy alloy includes Al, Co, Cr, Fe, and Ni metal elements, wherein the molar ratio of Al, Co, Cr, Fe, and Ni metal elements is (2-20):(20-28):(11-24):(14-24):(20-32).

2. The method for preparing the micro-consumable anode material for oxygen-aluminum co-production according to claim 1, characterized in that, The steps are as follows: (1) Slurry preparation: The ceramic phase powder and the metal phase powder are mixed evenly in proportion to obtain a powder mixture. Then, a binder and a certain amount of water are added and stirred evenly to prepare a slurry with a solid content of 30%-70%. (2) Granulation: The slurry obtained in step (1) is prepared into granulated powder by spray granulation; (3) Press molding: The granulated powder obtained in step (2) is loaded into a mold and pressed to obtain the molded product; the molding pressure is 150-300 MPa and the molding temperature is 20-300℃; (4) Sintering: The formed product is sintered in a nitrogen or argon inert atmosphere at 1000-1400℃ for 1-6 hours to obtain a dense product.

3. The method for preparing the micro-consumable anode material for oxygen-aluminum co-production according to claim 2, characterized in that, The adhesive mentioned in step (1) is 0.5%-3% of the mass of the powder mixture.

4. The method for producing a microconsumption anode material for co-production of alumina and oxygen according to claim 2, characterized by, The solid content mentioned in step (1) is 50%-65%.

5. The method for preparing the micro-consumable anode material for oxygen-aluminum co-production according to claim 2, characterized in that, The pressing in step (3) is performed by warm isostatic pressing or cold isostatic pressing.

6. The method for preparing the low-consumption anode material for oxygen-aluminum co-production according to claim 2, characterized in that, The oxygen content in the sintering process described in step (4) is controlled at 100-1000 ppm.

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