A method for preparing carbon anode material for aluminum electrolysis

Abstract

The application relates to a preparation method of a carbon anode for aluminum electrolysis, which comprises the following steps: uniformly mixing a first antioxidant and petroleum coke, calcining to obtain calcined coke; wherein the first antioxidant contains element B, and the content of element B in the added first antioxidant is 400-1200 ppm of the mass of the petroleum coke; uniformly mixing the calcined coke and coal pitch according to a mass ratio of 60-100:15, and then performing compression molding to obtain a carbon anode green block; and performing calcination on the carbon anode green block, and then cooling to obtain a finished product of the carbon anode for aluminum electrolysis. The carbon anode for aluminum electrolysis prepared by the application has relatively low air and CO2 reaction activities, and has relatively low resistivity, so that the requirements of the aluminum electrolysis process can be better met.

Description

TECHNICAL FIELD

[0001] The application relates to a preparation method of carbon anode material for aluminum electrolysis, in particular to a preparation method of oxidation-resistant carbon anode material for aluminum electrolysis, and belongs to the technical fields of carbon preparation and aluminum electrolysis. BACKGROUND

[0002] The carbon anode is the most important component of the electrolytic cell, which shoulders two heavy responsibilities of delivering strong current to the high-temperature molten salt electrolytic cell and participating in the aluminum electrolysis electrochemical reaction. In theory, the electrochemical consumption of the carbon anode for producing 1 ton of aluminum will be 334 kg, but the carbon anode gross consumption in the industry will reach 500-550 kg, and the main reason for the huge gap between the theoretical carbon consumption and the actual carbon consumption is that, in addition to the necessary electrochemical consumption, the carbon anode will also react with the air at the top of the carbon anode and the CO2 gas at the bottom, resulting in additional consumption.

[0003] At present, in order to improve the oxidation resistance of the carbon anode and reduce the reactivity of the carbon anode with air and CO2, the methods adopted in the existing patents mainly include the following categories: the first category is to improve the oxidation resistance of the anode by coating a layer of coating on the surface of the anode, such as CN115895302A, CN101386995A, CN101386995A and the like, however, the method of using coating has the disadvantages of long process flow, high cost, introduction of impurities affecting the quality of primary aluminum and the like; the second category is to improve the oxidation resistance of the carbon anode by changing the raw materials in the production process of the anode and improving the physical properties of the aggregate, such as CN103952721A, CN107523846A, CN106191924A and the like; however, the stability of the raw materials needs to be guaranteed; the third category is to improve the oxidation resistance of the anode by adding metal compounds in the mixing process to change the reactivity of the carbon anode with air and CO2, such as CN103266332A, CN103276409A, CN103255438A and the like, however, the method ignores the influence of the additives on the resistivity, causing the reduction of current efficiency. In summary, it is urgent to develop a preparation method of carbon anode material which has strong universality of raw materials, short modification process and no obvious adverse effect on current efficiency. SUMMARY

[0004] In view of the deficiencies of the prior art, the application provides a preparation method of carbon anode material for aluminum electrolysis with strong oxidation resistance.

[0005] In order to solve the above technical problems, the technical scheme of the application is as follows:

[0006] A preparation method of carbon anode for aluminum electrolysis, comprising the following steps:

[0007] S1, mixing the first antioxidant with the petroleum coke uniformly, calcining to obtain calcined coke;

[0008] The first antioxidant contains element B, and the content of element B in the added first antioxidant is 400-1200 ppm of the mass of the petroleum coke.

[0009] S2, mixing the calcined coke with coal pitch uniformly according to a mass ratio of 60-100:15, and pressing to form a carbon anode green block;

[0010] S3, baking the carbon anode green block, and cooling to obtain a finished product of carbon anode for aluminum electrolysis.

[0011] Further, in S1, the content of element B in the added first antioxidant is 450-1150 ppm of the mass of the petroleum coke, more further 500-1050 ppm, and preferably 600-1000 ppm.

[0012] Preferably, the first antioxidant includes one or more of boron carbide, boric acid, boron nitride, trimethoxy boroxin (C3H9B3O6), and pyridine borane (C5H8BN), and more preferably, the first antioxidant is trimethoxy boroxin.

[0013] Further, in S1, the first antioxidant, the second antioxidant, and the petroleum coke are mixed uniformly, and calcined to obtain calcined coke.

[0014] The second antioxidant contains elements Al and Si, and the molar ratio of Al to Si in the second antioxidant is 1.0-2.0:1. The content of element Al in the added second antioxidant is 200-1000 ppm of the mass of the petroleum coke, more further 250-900 ppm, and preferably 400-800 ppm.

[0015] Further, the second antioxidant includes one or more of aluminum silicate, sodium feldspar, potassium feldspar, and calcium feldspar. Preferably, the second antioxidant is aluminum silicate. In this way, by adding the second antioxidant, aluminum silicate complex groups can be introduced, which are embedded in the micro-interlayer or edge of the carbon structure, and can prevent the Boudouard reaction of C and CO2, and reduce the CO2 reactivity of the carbon anode aggregate. In the subsequent kneading process, the functional elements and compounds of these additives can continue to be introduced into the coal pitch, and play a similar role in the coking process of calcination.

[0016] Further, the particle size distribution of the antioxidant is that the mass of particles less than 200 mesh accounts for more than 99.9% of the total mass. The particle size of the antioxidant particles is less than 200 mesh, which is beneficial to the full contact of the antioxidant with the petroleum coke, so that the two fully act in the calcination process.

[0017] Further, the calcined coke is calcined at 1000-1400℃ for 1-4h; preferably, the calcination is carried out in a rotary kiln. Preferably, the calcination is carried out at 900-1300℃ for 1.5-3.5h.

[0018] Further, the calcined coke is classified between S1 and S2 to obtain coarse coke with a particle size of 4-8mm, medium coke with a particle size of 1-4mm, fine coke with a particle size of 0.074-1mm and powder coke with a particle size less than 0.074mm; in S2, the coarse coke accounts for 12-19wt.%, the medium coke accounts for 22-29wt.%, the fine coke accounts for 25-37wt.%, and the powder coke accounts for 20-30wt.% in the calcined coke.

[0019] Further, in S2, the mass ratio of the calcined coke to coal tar pitch is 70-90:15, preferably 75-85:15.

[0020] Further, in S2, the mixing is carried out in a kneader.

[0021] Further, in S2, the calcined coke is uniformly mixed with coal tar pitch and a conductive agent, and then is pressed into a shape; preferably, the pressing is carried out by a molding machine.

[0022] Preferably, the amount of the conductive agent accounts for 0.5-2wt.%, more preferably 1-1.5wt.%, of the mass of the carbon anode green block.

[0023] Preferably, the conductive agent is one or more of graphite powder, carbon nanotube powder and conductive carbon black.

[0024] Preferably, the particle size distribution of the conductive agent is that the mass of particles with a particle size less than 200 mesh accounts for more than 99.9% of the total mass.

[0025] The conductive agent contains macromolecular aromatic hydrocarbons and sp 2 hybrid bonds, which can increase the graphite-like structure and sp 2 hybrid bonds in the aggregate of the carbon anode, improve the conductivity of the aggregate, alleviate the negative impact of the antioxidant on the conductivity, and also promote the coking of the coal tar pitch, thereby reducing the resistivity of the carbon anode.

[0026] Further, in S3, the baking is carried out in a baking furnace, the heating rate is controlled to be 10-20℃ / h, the baking temperature is 900-1300℃, and the holding time is 7-14h.

[0027] Compared with the prior art, the present application has the following advantages:

[0028] (1) In the present application, by mixing and calcining the first antioxidant and petroleum coke, B element is introduced, the recombination and polymerization of the microstructure of petroleum coke during calcination are promoted, the aromaticity and graphitization degree of the calcined coke are improved, thereby the oxidation resistance of the carbon anode aggregate is improved, and finally the oxidation resistance of the carbon anode product is improved. By introducing aluminum-silicate complex groups, the oxidation resistance of the carbon anode product can be further improved.

[0029] (2) The carbon anode for aluminum electrolysis prepared in the present application has low air and CO2 reactivity, and low resistivity, which can better meet the requirements of the aluminum electrolysis process. The air reactivity of the carbon anode can be less than 10%, the CO2 reactivity can be less than 10%, and the resistivity can be 50 μΩ·m.

[0030] (3) In the present application, by controlling the addition amount of the antioxidant, the oxidation resistance of the carbon anode can be effectively improved, and the carbon anode can avoid causing significant adverse effects on the molten aluminum electrolyte or aluminum liquid during service. DETAILED DESCRIPTION

[0031] The present application will be described in detail below with reference to the examples. It should be noted that the examples in the present application and the features in the examples can be combined with each other without conflict.

[0032] Example 1

[0033] The preparation method of the carbon anode for aluminum electrolysis in this embodiment is as follows:

[0034] According to the batching amount of 5.35 kg of the first antioxidant per ton of petroleum coke and 3.00 kg of the second antioxidant per ton of petroleum coke, trimethoxy boroxin (C3H9B3O6) (i.e. the first antioxidant, at this time, the content of element B in the added trimethoxy boroxin is 1000 ppm of the mass of the petroleum coke) and aluminum silicate (Al2SiO5) (i.e. the second antioxidant, at this time, the molar ratio of Al to Si in the added aluminum silicate is 2.0:1, and the content of element Al in the added aluminum silicate is 800 ppm of the mass of the petroleum coke) are added to the petroleum coke produced by a certain domestic factory and mixed thoroughly, and then placed in a rotary kiln for calcination at a temperature of 1200℃ for 2h to obtain antioxidant calcined coke.

[0035] The obtained calcined coke is classified according to particle size into coarse coke (8-4mm), medium coke (4-1mm), fine coke (1-0.074mm), and powder coke (-0.074mm).

[0036] The calcined coke (ratioed according to 15.7wt.% of coarse coke, 25.7wt.% of medium coke, 32.7wt.% of fine coke, and 25.9wt.% of powder coke) and coal pitch are mixed in a mass ratio of 85:15, and 2wt.% of graphite powder of the carbon anode green block is added for mixing, then the mixed material is added to a molding machine to be pressed and molded into a carbon anode green block, and placed in a baking furnace for baking, the heating rate is 15℃ / h, the baking temperature is 1100℃, the holding time is 10h, and the aluminum electrolysis carbon anode is prepared after slow cooling.

[0037] The R value of the prepared calcined coke is 0.61 (R=I D / I G , the ratio of the amorphous carbon peak intensity I D to the graphite carbon peak intensity I G in the Raman spectrum, the smaller the R value, the higher the graphitization degree), the air reactivity of the carbon anode obtained in the example is 9.23%, the CO2 reactivity is 8.86%, the resistivity is 48μΩ·m, and the true density is 2.07g / cm -3 .

[0038] Comparative Example 1

[0039] Example 1 is repeated, the only difference being that trimethoxy boroxin is not added.

[0040] The R value of the prepared calcined coke is 0.73, the air reactivity of the carbon anode obtained in the example is 18.9%, the CO2 reactivity is 9.77%, the resistivity is 51μΩ·m, and the true density is 2.06g / cm -3 .

[0041] It can be seen that the addition of the first antioxidant can introduce B element, promote the recombination and polymerization of the microstructure of petroleum coke in the calcination process, improve the aromaticity and graphitization degree of the calcined coke, and thus improve the oxidation resistance of the carbon anode aggregate.

[0042] Example 2

[0043] Example 1 is repeated, the only difference being that aluminum silicate is not added.

[0044] The air reactivity of the carbon anode obtained in the example is 9.65%, the CO2 reactivity is 18.6%, the resistivity is 47μΩ·m, and the true density is 2.05g / cm -3 .

[0045] Example 3

[0046] Example 1 was repeated, except that no graphite powder was added.

[0047] The carbon anode obtained in this example had an air reactivity of 9.34%, a CO2 reactivity of 8.92%, an electrical resistivity of 55 μΩ.m, and a true density of 2.07 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0048] Comparative Example 2

[0049] Example 1 was repeated, except that no graphite powder was added.

[0050] The calcined coke obtained in this example had an R value of 0.74. The carbon anode obtained in this example had an air reactivity of 21.8%, a CO2 reactivity of 19.2%, an electrical resistivity of 53 μΩ.m, and a true density of 2.04 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0051] Comparative Example 3

[0052] Example 1 was repeated, except that the amounts of trimethoxy boroxin and aluminum silicate were adjusted so that the amount of element B in the trimethoxy boroxin added was 300 ppm of the mass of the petroleum coke, and the molar ratio of Al to Si in the aluminum silicate was 2:1, and the amount of element Al was 100 ppm of the mass of the petroleum coke.

[0053] The carbon anode obtained in this example had an air reactivity of 17.3%, a CO2 reactivity of 16.5%, an electrical resistivity of 46 μΩ.m, and a true density of 2.07 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0054] Example 4

[0055] Example 1 was repeated, except that the amounts of trimethoxy boroxin and aluminum silicate were adjusted so that the amount of element B in the trimethoxy boroxin added was 400 ppm of the mass of the petroleum coke, and the molar ratio of Al to Si in the aluminum silicate was 2:1, and the amount of element Al was 200 ppm of the mass of the petroleum coke.

[0056] The carbon anode obtained in this example had an air reactivity of 14.4%, a CO2 reactivity of 14.1%, an electrical resistivity of 47 μΩ.m, and a true density of 2.07 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0057] Example 5

[0058] Example 1 was repeated, except that the amounts of trimethoxyboroxin and aluminum silicate were adjusted so that the amount of element B in the trimethoxyboroxin added was 600 ppm by mass of the petroleum coke, and the molar ratio of Al to Si in the aluminum silicate was 2:1, and the amount of element Al was 400 ppm by mass of the petroleum coke.

[0059] The carbon anode obtained in this example had an air reactivity of 9.89%, a CO2 reactivity of 9.93%, an electrical resistivity of 48 μΩ·m, and a true density of 2.07 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0060] Example 6

[0061] Example 1 was repeated, except that the amounts of trimethoxyboroxin and aluminum silicate were adjusted so that the amount of element B in the trimethoxyboroxin added was 1200 ppm by mass of the petroleum coke, and the molar ratio of Al to Si in the aluminum silicate was 2:1, and the amount of element Al was 1000 ppm by mass of the petroleum coke.

[0062] The carbon anode obtained in this example had an air reactivity of 9.21%, a CO2 reactivity of 8.85%, an electrical resistivity of 51 μΩ·m, and a true density of 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0063] Comparative Example 4

[0064] Example 1 was repeated, except that the amounts of trimethoxyboroxin and aluminum silicate were adjusted so that the amount of element B in the trimethoxyboroxin added was 1300 ppm by mass of the petroleum coke, and the molar ratio of Al to Si in the aluminum silicate was 2:1, and the amount of element Al was 1100 ppm by mass of the petroleum coke.

[0065] The carbon anode obtained in this example had an air reactivity of 9.20%, a CO2 reactivity of 8.83%, an electrical resistivity of 55 μΩ·m, and a true density of 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0066] Comparative Example 5

[0067] Example 1 was repeated, except that the amount of trimethoxyboroxin was adjusted so that the amount of element B in the trimethoxyboroxin added was 300 ppm by mass of the petroleum coke.

[0068] The carbon anode obtained in the example has air reactivity of 16.4%, CO2 reactivity of 9.53%, resistivity of 47 μΩ·m, and true density of 2.07 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0069] Example 7

[0070] Example 1 is repeated, except that the amount of trimethoxy boroxin added is adjusted so that the content of element B in the trimethoxy boroxin added is 400 ppm of the mass of the petroleum coke.

[0071] The carbon anode obtained in the example has air reactivity of 13.9%, CO2 reactivity of 9.48%, resistivity of 47 μΩ·m, and true density of 2.06 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0072] Example 8

[0073] Example 1 is repeated, except that the amount of trimethoxy boroxin added is adjusted so that the content of element B in the trimethoxy boroxin added is 1200 ppm of the mass of the petroleum coke.

[0074] The carbon anode obtained in the example has air reactivity of 9.22%, CO2 reactivity of 8.86%, resistivity of 49 μΩ·m, and true density of 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0075] Comparative Example 6

[0076] Example 1 is repeated, except that the amount of trimethoxy boroxin added is adjusted so that the content of element B in the trimethoxy boroxin added is 1300 ppm of the mass of the petroleum coke.

[0077] The carbon anode obtained in the example has air reactivity of 9.20%, CO2 reactivity of 8.85%, resistivity of 54 μΩ·m, and true density of 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0078] Comparative Example 7

[0079] Example 1 is repeated, except that the amount of trimethoxy boroxin added is adjusted so that the content of element B in the trimethoxy boroxin added is 1300 ppm of the mass of the petroleum coke.

[0080] The carbon anode obtained in the example has air reactivity of 9.57%, CO2 reactivity of 15.4%, resistivity of 47 μΩ·m, and true density of 2.06 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0081] Example 9

[0082] Example 1 is repeated, except that the addition amount of aluminum silicate is adjusted so that the molar ratio of Al to Si in the added aluminum silicate is 2:1, and the content of element Al is 200 ppm of the mass of petroleum coke.

[0083] The carbon anode obtained in the example has air reactivity of 9.51%, CO2 reactivity of 13.5%, resistivity of 47 μΩ·m, and true density of 2.06 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0084] Example 10

[0085] Example 1 is repeated, except that the addition amount of aluminum silicate is adjusted so that the molar ratio of Al to Si in the added aluminum silicate is 2:1, and the content of element Al is 1000 ppm of the mass of petroleum coke.

[0086] The carbon anode obtained in the example has air reactivity of 9.22%, CO2 reactivity of 8.85%, resistivity of 50 μΩ·m, and true density of 2.05 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0087] Comparative Example 8

[0088] Example 1 is repeated, except that the addition amount of aluminum silicate is adjusted so that the molar ratio of Al to Si in the added aluminum silicate is 2:1, and the content of element Al is 1100 ppm of the mass of petroleum coke.

[0089] The carbon anode obtained in the example has air reactivity of 9.21%, CO2 reactivity of 8.84%, resistivity of 54 μΩ·m, and true density of 2.06 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0090] It can be seen that the addition of the first antioxidant and the second antioxidant helps to obtain carbon anodes with good air reactivity and CO2 reactivity, but the addition amount of the antioxidant is not the higher the better. When the addition amount reaches a certain value, the air reactivity and CO2 reactivity of the carbon anode no longer have obvious improvement, but the content of "impurities" in the carbon anode increases, which increases the risk of contamination of molten aluminum in the aluminum electrolysis process.

[0091] Comparative Example 9

[0092] Example 1 is repeated, except that boron carbide (B4C) is used to replace trimethoxy boroxin, the content of element B in the added boron carbide is 300 ppm of the mass of petroleum coke; and sodium feldspar is used to replace aluminum silicate, the molar ratio of Al and Si in the added sodium feldspar is 1:1, and the content of element Al is 100 ppm of the mass of petroleum coke.

[0093] According to the national non-ferrous metal industry standard YS / T285-2012, the air reactivity of the carbon anode obtained in this example is 17.7%, the CO2 reactivity is 16.8%, the resistivity is 46 μΩ·m, and the true density is 2.06 g / cm -3 .

[0094] Example 11

[0095] Example 1 is repeated, except that boron carbide (B4C) is used to replace trimethoxy boroxin, the content of element B in the added boron carbide is 400 ppm of the mass of petroleum coke; and sodium feldspar is used to replace aluminum silicate, the molar ratio of Al and Si in the added sodium feldspar is 1:1, and the content of element Al is 200 ppm of the mass of petroleum coke.

[0096] According to the national non-ferrous metal industry standard YS / T285-2012, the air reactivity of the carbon anode obtained in this example is 14.6%, the CO2 reactivity is 14.5%, the resistivity is 47 μΩ·m, and the true density is 2.06 g / cm -3 .

[0097] Example 12

[0098] Example 1 is repeated, except that boron carbide (B4C) is used to replace trimethoxy boroxin, the content of element B in the added boron carbide is 600 ppm of the mass of petroleum coke; and sodium feldspar is used to replace aluminum silicate, the molar ratio of Al and Si in the added sodium feldspar is 1:1, and the content of element Al is 400 ppm of the mass of petroleum coke.

[0099] The carbon anode obtained in the example has air reactivity of 9.91%, CO2 reactivity of 9.94%, resistivity of 48 μΩ.m, and true density of 2.07 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0100] Example 13

[0101] The example 1 is repeated, except that boron carbide (B4C) is used to replace trimethoxy boroxin, the content of element B in the added boron carbide is 1000 ppm of the mass of petroleum coke, and sodium feldspar is used to replace aluminum silicate, the molar ratio of Al and Si in the added sodium feldspar is 1:1, and the content of element Al is 800 ppm of the mass of petroleum coke.

[0102] The R value of the calcined coke obtained is 0.62, which is calculated by using the Raman spectrum analysis method, and the carbon anode obtained in the example has air reactivity of 9.28%, CO2 reactivity of 8.94%, resistivity of 48 μΩ.m, and true density of 2.06 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0103] Example 14

[0104] The example 1 is repeated, except that boron carbide (B4C) is used to replace trimethoxy boroxin, the content of element B in the added boron carbide is 1200 ppm of the mass of petroleum coke, and sodium feldspar is used to replace aluminum silicate, the molar ratio of Al and Si in the added sodium feldspar is 1:1, and the content of element Al is 1000 ppm of the mass of petroleum coke.

[0105] The carbon anode obtained in the example has air reactivity of 9.27%, CO2 reactivity of 8.93%, resistivity of 52 μΩ.m, and true density of 2.05 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012. -3 .

[0106] Comparative Example 10

[0107] The example 1 is repeated, except that boron carbide (B4C) is used to replace trimethoxy boroxin, the content of element B in the added boron carbide is 1300 ppm of the mass of petroleum coke, and sodium feldspar is used to replace aluminum silicate, the molar ratio of Al and Si in the added sodium feldspar is 1:1, and the content of element Al is 1100 ppm of the mass of petroleum coke.

[0108] The carbon anode obtained in the example has air reactivity of 9.27%, CO2 reactivity of 9.95%, resistivity of 55 μΩ.m, and true density of 2.05 g / cm3, which are measured according to the national non-ferrous metal industry standard YS / T285-2012.-3 .

[0109] Comparative Example 11

[0110] Example 1 was repeated, except that boric acid (H3BO3) was used instead of trimethoxyboroxin, the content of element B in the added boric acid was 300 ppm of the mass of petroleum coke; and potassium feldspar was used instead of aluminum silicate, the molar ratio of Al and Si in the added potassium feldspar was 1:1, and the content of element Al was 100 ppm of the mass of petroleum coke.

[0111] The air reactivity of the carbon anode obtained in this example was 17.8%, the CO2 reactivity was 17.1%, the resistivity was 47 μΩ·m, and the true density was 2.06 g / cm3, which were measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0112] Example 15

[0113] Example 1 was repeated, except that boric acid (H3BO3) was used instead of trimethoxyboroxin, the content of element B in the added boric acid was 400 ppm of the mass of petroleum coke; and potassium feldspar was used instead of aluminum silicate, the molar ratio of Al and Si in the added potassium feldspar was 1:1, and the content of element Al was 200 ppm of the mass of petroleum coke.

[0114] The air reactivity of the carbon anode obtained in this example was 14.5%, the CO2 reactivity was 14.7%, the resistivity was 47 μΩ·m, and the true density was 2.06 g / cm3, which were measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0115] Example 16

[0116] Example 1 was repeated, except that boric acid (H3BO3) was used instead of trimethoxyboroxin, the content of element B in the added boric acid was 600 ppm of the mass of petroleum coke; and potassium feldspar was used instead of aluminum silicate, the molar ratio of Al and Si in the added potassium feldspar was 1:1, and the content of element Al was 400 ppm of the mass of petroleum coke.

[0117] The air reactivity of the carbon anode obtained in this example was 9.92%, the CO2 reactivity was 9.95%, the resistivity was 48 μΩ·m, and the true density was 2.06 g / cm3, which were measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0118] Example 17

[0119] Example 1 was repeated, except that boric acid (H3BO3) was used instead of trimethoxyboroxin, the content of element B in the added boric acid was 1000 ppm of the mass of petroleum coke; and potassium feldspar was used instead of aluminum silicate, the molar ratio of Al and Si in the added potassium feldspar was 1:1, and the content of element Al was 800 ppm of the mass of petroleum coke.

[0120] The R value of the prepared calcined coke was calculated to be 0.62 by using a Raman spectrum analysis method. The air reactivity of the carbon anode obtained in this example was 9.31%, the CO2 reactivity was 8.99%, the resistivity was 48 μΩ·m, and the true density was 2.06 g / cm3, which were measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0121] Example 18

[0122] Example 1 was repeated, except that boric acid (H3BO3) was used instead of trimethoxyboroxin, the content of element B in the added boric acid was 1200 ppm of the mass of petroleum coke; and potassium feldspar was used instead of aluminum silicate, the molar ratio of Al and Si in the added potassium feldspar was 1:1, and the content of element Al was 1000 ppm of the mass of petroleum coke.

[0123] The air reactivity of the carbon anode obtained in this example was 9.30%, the CO2 reactivity was 8.98%, the resistivity was 52 μΩ·m, and the true density was 2.05 g / cm3, which were measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0124] Comparative Example 12

[0125] Example 1 was repeated, except that boric acid (H3BO3) was used instead of trimethoxyboroxin, the content of element B in the added boric acid was 1300 ppm of the mass of petroleum coke; and potassium feldspar was used instead of aluminum silicate, the molar ratio of Al and Si in the added potassium feldspar was 1:1, and the content of element Al was 1100 ppm of the mass of petroleum coke.

[0126] The air reactivity of the carbon anode obtained in this example was 9.29%, the CO2 reactivity was 8.97%, the resistivity was 56 μΩ·m, and the true density was 2.04 g / cm3, which were measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0127] Comparative Example 13

[0128] Example 1 was repeated, except that boron nitride (BN) was used instead of trimethoxy boroxin, the content of element B in the added boron nitride was 300 ppm of the mass of petroleum coke; and that anorthite was used instead of aluminum silicate, the molar ratio of Al and Si in the added anorthite was 1:1, and the content of element Al was 100 ppm of the mass of petroleum coke.

[0129] The air reactivity of the carbon anode obtained in this example was 17.7%, the CO2 reactivity was 17.2%, the resistivity was 48 μΩ·m, and the true density was 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0130] Example 19

[0131] Example 1 was repeated, except that boron nitride (BN) was used instead of trimethoxy boroxin, the content of element B in the added boron nitride was 400 ppm of the mass of petroleum coke; and that anorthite was used instead of aluminum silicate, the molar ratio of Al and Si in the added anorthite was 1:1, and the content of element Al was 200 ppm of the mass of petroleum coke.

[0132] The air reactivity of the carbon anode obtained in this example was 14.4%, the CO2 reactivity was 14.9%, the resistivity was 48 μΩ·m, and the true density was 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0133] Example 20

[0134] Example 1 was repeated, except that boron nitride (BN) was used instead of trimethoxy boroxin, the content of element B in the added boron nitride was 600 ppm of the mass of petroleum coke; and that anorthite was used instead of aluminum silicate, the molar ratio of Al and Si in the added anorthite was 1:1, and the content of element Al was 400 ppm of the mass of petroleum coke.

[0135] The air reactivity of the carbon anode obtained in this example was 9.95%, the CO2 reactivity was 9.97%, the resistivity was 49 μΩ·m, and the true density was 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0136] Example 21

[0137] Example 1 was repeated, except that boron nitride (BN) was used instead of trimethoxy boroxin, the content of element B in the added boron nitride was 1000 ppm of the mass of petroleum coke; and that anorthite was used instead of aluminum silicate, the molar ratio of Al and Si in the added anorthite was 1:1, and the content of element Al was 800 ppm of the mass of petroleum coke.

[0138] The R value of the calcined coke prepared is 0.61 calculated using the Raman spectroscopy analysis method. The air reactivity of the carbon anode obtained in this example is 9.35%, the CO2 reactivity is 9.02%, the resistivity is 49 μΩ·m, and the true density is 2.05 g / cm3 measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0139] Example 22

[0140] Example 1 is repeated, except that boron nitride (BN) is used to replace trimethoxy boroxin, the content of element B in the added boron nitride is 1200 ppm of the mass of petroleum coke; and anorthite is used to replace aluminum silicate, the molar ratio of Al and Si in the added anorthite is 1:1, and the content of element Al is 1000 ppm of the mass of petroleum coke.

[0141] The air reactivity of the carbon anode obtained in this example is 9.34%, the CO2 reactivity is 9.00%, the resistivity is 53 μΩ·m, and the true density is 2.04 g / cm3 measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0142] Example 23

[0143] Example 1 is repeated, except that boron nitride (BN) is used to replace trimethoxy boroxin, the content of element B in the added boron nitride is 1300 ppm of the mass of petroleum coke; and anorthite is used to replace aluminum silicate, the molar ratio of Al and Si in the added anorthite is 1:1, and the content of element Al is 1100 ppm of the mass of petroleum coke.

[0144] The air reactivity of the carbon anode obtained in this example is 9.33%, the CO2 reactivity is 8.99%, the resistivity is 57 μΩ·m, and the true density is 2.04 g / cm3 measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0145] Comparative Example 14

[0146] Example 1 is repeated, except that aluminum oxide (Al2O3) is used to replace aluminum silicate (Al2SiO5).

[0147] The air reactivity of the carbon anode obtained in this example is 10.5%, the CO2 reactivity is 14.7%, the resistivity is 50 μΩ·m, and the true density is 2.04 g / cm3 measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0148] Comparative Example 15

[0149] Example 1 was repeated, except that aluminum oxide (Al2O3) and silicon dioxide (SiO2) were used to replace aluminum silicate (Al2SiO5), and the molar ratio of aluminum oxide to silicon dioxide was 1:1.

[0150] The carbon anode obtained in this example had an air reactivity of 10.8%, a CO2 reactivity of 18.4%, a resistivity of 49 μΩ·m, and a true density of 2.04 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0151] Comparative Example 16

[0152] Example 1 was repeated, except that aluminum oxide (Al2O3) and silicon dioxide (SiO2) were used to replace aluminum silicate (Al2SiO5), and the molar ratio of aluminum oxide to silicon dioxide was 1:1.

[0153] The carbon anode obtained in this example had an air reactivity of 10.3%, a CO2 reactivity of 14.3%, a resistivity of 51 μΩ·m, and a true density of 2.05 g / cm3, as measured according to the national non-ferrous metal industry standard YS / T 285-2012. -3 .

[0154] It can be seen that the use of conventional aluminum oxide and / or silicon dioxide cannot obtain a carbon anode with good air reactivity and CO2 reactivity.

[0155] The above examples are intended to be illustrative only and should not be used to limit the scope of the present application. Various modifications of the present application, which are apparent to those skilled in the art, are intended to be within the scope of the appended claims.

Claims

1. A method for producing a carbon anode for aluminum electrolysis, characterized by, It comprises the following steps: S1, mixing the first antioxidant, the second antioxidant and the petroleum coke uniformly, calcining to obtain calcined coke; The first antioxidant contains element B, and the content of element B in the added first antioxidant is 600-1200 ppm of the mass of the petroleum coke; the first antioxidant comprises one or more of boron carbide, boric acid, boron nitride, trimethoxy boron oxide hexacyclic ring and pyridine borane; the second antioxidant contains elements Al and Si, and the molar ratio of Al to Si in the second antioxidant is 1.0-2.0:1; the content of element Al in the added second antioxidant is 400-1000 ppm of the mass of the petroleum coke; the second antioxidant is one or more of aluminum silicate, sodium feldspar, potassium feldspar and calcium feldspar; S2, mixing the calcined coke and coal pitch uniformly at a mass ratio of 60-100:15, and then pressing to form a carbon anode green block; S3, baking the carbon anode green block, and then cooling to obtain a finished carbon anode for aluminum electrolysis.

2. The production method according to claim 1, characterized by, In S1, the content of element B in the added first antioxidant is 600-1000 ppm of the mass of the petroleum coke.

3. The preparation method according to claim 1, characterized in that In S1, the content of element Al in the added second antioxidant is 400-800 ppm of the mass of the petroleum coke.

4. The production method according to any one of claims 1 to 3, characterized by, The particle size distribution of the antioxidant is that the mass of particles less than 200 mesh accounts for more than 99.9% of the total mass.

5. The method of any one of claims 1-3, wherein, The calcination is performed at 1000-1400℃ for 1-4h.

6. The production method according to claim 5, characterized by, The calcination is performed in a rotary kiln.

7. The method of any one of claims 1-3, wherein, Between S1 and S2, the calcined coke is classified to obtain coarse coke with a particle size of 4-8mm, medium coke with a particle size of 1-4mm, fine coke with a particle size of 0.074-1mm and powder coke with a particle size less than 0.074mm; in S2, the proportion of the coarse coke in the calcined coke is 12-19wt.%, the proportion of the medium coke is 22-29wt.%, the proportion of the fine coke is 25-37wt.% and the proportion of the powder coke is 20-30wt.%.

8. The method of any one of claims 1-3, wherein, In S2, the mass ratio of the calcined coke to the coal pitch is 70-90:

15.

9. The production method according to claim 8, characterized by, In S2, the mass ratio of the calcined coke to the coal pitch is 75-85:

15.

10. The method of any one of claims 1-3, wherein, In S2, the calcined coke, the coal pitch and the conductive agent are mixed uniformly, and then pressed to form.

11. The method of claim 10, wherein, The amount of the conductive agent accounts for 0.5-2wt.% of the mass of the carbon anode green block.

12. The method of claim 10, wherein, The conductive agent is one or more of graphite powder, carbon nanotube powder and conductive carbon black.

13. The preparation method according to claim 10, characterized in that The particle size distribution of the conductive agent is that the mass of particles less than 200 mesh accounts for more than 99.9% of the total mass.

14. The method of any one of claims 1-3, wherein, In S3, the baking is performed in a baking furnace, the heating rate is controlled to be 10-20℃ / h, the baking temperature is 900-1300℃, and the holding time is 7-14h.