CN114806231A

CN114806231A - Pre-baked anode anti-oxidation coating for reducing energy consumption of aluminum electrolysis cell and preparation and application methods thereof

Info

Publication number: CN114806231A
Application number: CN202210223533.0A
Authority: CN
Inventors: 洪波; 王博一
Original assignee: Hunan Bopuli Material Technology Co ltd; Guizhou Innovative Light Metal Process Equipment Engineering Technology Research Center Co ltd
Current assignee: Hunan Bopuli Material Technology Co ltd; Guizhou Innovative Light Metal Process Equipment Engineering Technology Research Center Co ltd
Priority date: 2022-03-09
Filing date: 2022-03-09
Publication date: 2022-07-29
Anticipated expiration: 2042-03-09
Also published as: CN114806231B

Abstract

The invention discloses a prebaked anode anti-oxidation coating for reducing energy consumption of an aluminum electrolytic cell and preparation and application methods thereof, belonging to the field of novel energy-saving and consumption-reducing materials for electrolytic aluminum. The prepared coating comprises 45-50% of alumina, 2-3% of alkali metal grain boundary fusing agent, 25-30% of reinforcing agent, 0.3-0.8% of coupling agent, 0.001% of crystal form control agent and 16.2-27.7% of solvent; wherein the alkali metal crystal boundary fusing agent consists of anorthite powder, albite and sodium fluosilicate; the reinforcing agent is silica sol; the coupling agent is a silane coupling agent; the crystal form control agent consists of ytterbium oxide and erbium oxide; the solvent is water. The coating has strong adhesive force, can finish densification sintering at the temperature of 400-; meanwhile, the service life of the anode can be prolonged by one day, and the field workload is reduced.

Description

Pre-baked anode anti-oxidation coating for reducing energy consumption of aluminum electrolysis cell and preparation and application methods thereof

Technical Field

The invention relates to an anti-oxidation coating for a prebaked anode for reducing energy consumption of an aluminum electrolytic cell, and a preparation method and an application method thereof, belonging to the technical field of chemical coatings.

Background

In a cryolite-alumina dissolved salt electrolysis pre-baking tank, the quality of a carbon anode directly influences the electrolysis and the product quality, and when the quality of the carbon anode does not meet the requirement, excessive carbon slag can be generated in an aluminum electrolyte solution; according to incomplete statistics, 5-15 kg of carbon slag is discharged when one ton of raw aluminum is produced. The generation of carbon residue causes adverse effects such as an increase in the voltage drop of the electrolyte, a generation of hot cells, an increase in the electric power loss in the electrolytic production of aluminum, and the like. In particular, the generation of hot cells not only causes unnecessary consumption of electric energy, but also damages the cathode of the electrolytic cell, which affects the service life of the electrolytic cell. When the content of carbon residue in the aluminum electrolyte solution reaches 1 wt%, the conductivity of the electrolyte is reduced by about 11%.

Based on the reason of the generation of the carbon residue, the generation of the carbon residue is mainly reduced in the prior art from the following ways:

firstly, a high-quality carbon anode is adopted. The carbon anode is generally made of petroleum coke, pitch coke and the like through the processes of crushing, calcining, proportioning, kneading and the like, and if the carbon anode is made of high-quality petroleum coke and the like, the exposition of carbon slag is reduced, and the current efficiency can be improved. However, in practice, as the yield of electrolytic aluminum increases year by year and the amount of high-quality petroleum coke decreases, the carbon anode has to adopt petroleum coke doped relatively more, various impurity compounds enter the carbon anode along with the petroleum coke, part of the impurity compounds are volatilized by roasting, and the rest of the impurity compounds become ash and are left in the carbon anode and released in an electrolytic bath in the electrolytic process to induce the carbon anode to slag;

and (II) selecting high-quality cathode carbon blocks. Like the carbon anode, the quality of the cathode carbon block is improved, so that the stripping of the carbon block can be reduced, and the generation of carbon slag is reduced, but because the carbon block is not the main reason for the generation of the carbon slag, the carbon slag generated in the actual aluminum electrolysis process can still not be ignored by selecting the mode;

and (III) controlling the low-temperature operation of the electrolysis process. Since the secondary reaction of aluminum is also a cause of carbon residue generation, the secondary reaction loss of aluminum can be reduced by maintaining low voltage, low alumina concentration, low molecular weight wall, low temperature and high polar distance during the electrolysis process, thereby reducing the generation of carbon residue. However, this also affects the amount of aluminium and the reduction of carbon residue is relatively low;

and fourthly, coating an anti-oxidation coating outside the carbon anode. The anti-oxidation coating is an anticorrosive coating, and can form a compact and high-strength sintered body around the anode, so that the loss of the carbon anode is reduced. The currently known anti-oxidation coating has various formulas, such as an electrolytic aluminum pre-baked anode anti-oxidation coating disclosed in patent No. CN2017100417494 and a preparation method thereof, and such as an aluminum electrolytic cell pre-baked anode anti-oxidation coating disclosed in patent No. CN 2018103644691. Due to different specific choices of the formula, the effects of the raw materials on the aspects of carbon slag generation, electric energy consumption and the like are different, and the energy-saving effect is not achieved.

Disclosure of Invention

Aiming at the defects in the prior art, the invention provides the prebaked anode anti-oxidation coating which has more reasonable formula and better effect and can reduce carbon slag and reduce the energy consumption of the aluminum electrolytic cell, and the preparation and application methods thereof.

The technical scheme adopted by the invention is that the prebaked anode anti-oxidation coating for reducing the energy consumption of the aluminum electrolytic cell comprises the following components in percentage by mass: 45 to 50 percent of alumina, 2 to 3 percent of alkali metal crystal boundary fusing agent, 25 to 30 percent of reinforcing agent, 0.3 to 0.8 percent of coupling agent, 0.001 percent of crystal form control agent and 16.2 to 27.7 percent of water.

Preferably, the alkali metal grain boundary fusing agent comprises 50-62% of anorthite powder, 35-40% of albite and 1-15% of sodium fluosilicate.

Preferably, the reinforcing agent is silica sol with 10% solid content.

Preferably, the coupling agent is silane coupling agent DL171 for surface modification of alumina and reinforcing agent.

Preferably, the crystal form control agent comprises ytterbium oxide with the purity of more than 99% and erbium oxide with the purity of more than 99%, and the weight ratio of the ytterbium oxide to the erbium oxide is 1: 1-2.

A preparation method of prebaked anode anti-oxidation coating for reducing energy consumption of aluminum electrolysis cell comprises the following steps:

step 1: fully dispersing a silane coupling agent by using absolute ethyl alcohol, wherein the mass ratio of the using amount of the silane coupling agent to the using amount of the absolute ethyl alcohol is 1: 1-2;

step 2: uniformly spraying the silane coupling agent treated in the step 1 on the surface of the alumina;

and step 3: feeding the alumina treated in the step 2 into a wet ball mill for ball milling for 1-2.5 hours;

and 4, step 4: carrying out reduced pressure ball milling on the alumina treated in the step 3 for 20-40min under the stirring of 25-55 ℃ so as to fully volatilize the ethanol and fully release the ethanol, thus finishing the modification of the alumina;

and 5: adding an alkali metal grain boundary fusing agent, a reinforcing agent, a coupling agent, a crystal form control agent and water according to a formula ratio, treating in the step 4 to obtain aluminum oxide, fully and uniformly mixing, sending into a hydrothermal reaction kettle, continuously reacting for 10-14h at the temperature of 190 ℃ and under the pressure of 0.5-2MPa, and cooling to obtain the anti-oxidation coating.

The anti-oxidation coating provided by the invention is applied as an anti-oxidation coating of an alumina pre-baked anode for aluminum electrolysis.

In one example, the anti-oxidation coating is sprayed on the side surface and the top surface of the prebaked anode with the surface temperature of 10-60 ℃, and then the prebaked anode is stored in an open environment at normal temperature for more than 8 hours for curing and curing; by controlling the maintenance time to exceed 8 hours, the coating is effectively prevented from bulging after entering the groove.

In one example, after the carbon anode and the anode steel claw are connected by pouring molten phosphorus pig iron to form a prebaked anode, an anti-oxidation coating is sprayed on the side surface and the top surface of the prebaked anode with the surface temperature of 10-60 ℃, after the spraying is finished, the heat brought by the molten phosphorus pig iron is gradually conducted to the outer surface of the prebaked anode, so that the temperature of the outer surface of the prebaked anode is raised by 30-50 ℃, and then the prebaked anode is stored for more than 8 hours to finish curing and aging; the heat that the phosphorus molten pig iron of pouring was conducted when utilizing the connection positive pole steel claw shortens the maintenance time on the one hand, and on the other hand is favorable to the maintenance of inlayer coating and inlayer coating moisture in time to be discharged, can guarantee the drainage of coating positive pole free moisture before the groove of entering, and the coating bulge that the prevention brought because of free moisture does not drain in the coating, the phenomenon of droing takes place.

Preferably, when spraying, the part of the four sides of the carbon anode within 18cm of the lower edge is kept from spraying.

Compared with the prior art, the invention has the beneficial effects that:

(1) by selecting a reasonable formula and a reasonable proportion, the anti-oxidation coating which has a similar expansion coefficient with carbon, strong binding force with carbon materials and certain self-healing and self-healing capabilities at high temperature can be obtained; the coating can form a more compact and uniform sintering layer on the surface of the carbon anode, so that the carbon anode is effectively wrapped and protected, and the generation amount of carbon slag is effectively reduced (compared with the carbon anode which is not coated with the anti-oxidation coating, the generation amount of the carbon slag is reduced by 30-60 percent, and compared with the anti-oxidation coating disclosed by CN2017100417494, the generation amount of the carbon slag is reduced by 10-15 percent); but also effectively reduces the pressure drop of the furnace bottom, the carbon consumption and the power consumption, and greatly reduces the production cost of the electrolytic aluminum industry;

(2) the coating is water-based viscous fluid mutually soluble with water, has stable property, does not cause any harm to human bodies, can finish the densification sintering process at the temperature of 400-420 ℃, forms a compact ceramic-based sealing layer on the surface of the carbon anode, isolates carbon dioxide, oxygen and air, prevents the outer surface of the carbon anode from being oxidized and peeled off, further reduces the content of carbon slag in electrolyte, reduces the resistance of the electrolyte, reduces the power consumption and prolongs the anode change period of 1-2 days;

(3) the invention can reduce the anodic oxidation at the middle seam of the electrolytic cell and prevent the horizontal current caused by the overheating of the middle seam due to the anodic oxidation at the middle seam, thereby improving the current efficiency and reducing the power consumption;

(4) the invention can reduce the influence on the solubility of alumina caused by the floating of the carbon residue on the surface layer of the electrolyte, thereby reducing the precipitation at the bottom of the electrolytic cell, reducing the pressure drop at the bottom of the electrolytic cell and improving the current efficiency;

(5) according to the preparation method, the silane coupling agent is dispersed by ethanol, sprayed on the surface of the alumina, and subjected to ball milling, pressure reduction ball milling and other operations, so that the mixing uniformity of the silane coupling agent and the alumina is effectively improved, the silane coupling agent is effectively promoted to enter micro-gaps of the alumina, and the modification effectiveness of the basic structural component of the alumina is realized.

Drawings

FIG. 1 is a view showing a state in which the oxidation preventive coating of the present invention is applied to a prebaked anode but not in a bath;

FIG. 2 shows the results of a staged oxidation test on untreated carbon blocks and carbon blocks coated with the anti-oxidation coating of the present invention;

FIG. 3 is a graph showing the effect of the present invention in industrial application, specifically, the comparison of the shapes of the untreated carbon anode (a) and the carbon anode (b) coated with the anti-oxidation coating of the present invention after the shutdown;

FIG. 4 is a second diagram illustrating the effect of the present invention;

FIG. 5 shows the results of tests on the coating of the anti-oxidation coating of the present invention in the center seam of the anode, specifically the qualitative effect of anti-oxidation in 24 hours, 8 hours, and 6 hours of coating maintenance.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings and specific embodiments, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. And all parts not described in detail below should be performed as in the prior art.

Example 1

1000kg of prebaked anode anti-oxidation coating for reducing the energy consumption of the aluminum electrolytic cell, wherein the coating comprises the following components in percentage by mass:

the aluminum oxide accounts for 45 percent of the total mass of the coating and accounts for 450 kg;

30kg of alkali metal grain boundary fusing agent accounting for 3 percent of the total mass of the coating; the alkali metal grain boundary fusing agent comprises anorthite powder, albite and sodium fluosilicate, which respectively account for 55%, 35% and 10% of the total mass of the alkali metal grain boundary fusing agent, namely 16.5kg of anorthite powder, 10.5kg of albite and 3kg of sodium fluosilicate;

the reinforcing agent accounts for 30 percent of the total mass of the coating and accounts for 300 kg; the reinforcing agent adopts silica sol with solid content of 10 percent;

7.99kg of coupling agent accounting for 0.799 percent of the total mass of the coating; the coupling agent adopts a DL171 silane coupling agent and is used for surface modification of alumina and a reinforcing agent;

the crystal form control agent accounts for 0.001 percent of the total mass of the coating, accounts for 0.01kg in total, and consists of ytterbium oxide with the purity of more than 99 percent and erbium oxide with the purity of more than 99 percent according to the weight ratio of 1: 1;

and the total weight of water accounts for 21.2 percent of the total weight of the coating, and the total weight is 212 kg.

step 1: fully dispersing a silane coupling agent by using absolute ethyl alcohol, wherein the mass ratio of the using amount of the silane coupling agent to the using amount of the absolute ethyl alcohol is 1: 1;

and step 3: feeding the alumina treated in the step 2 into a wet ball mill for ball milling for 1 hour;

and 4, step 4: performing ball milling on the alumina treated in the step 3 for 30min again in a reduced pressure state to fully release ethanol, and finishing the modification of the alumina;

and 5: adding an alkali metal grain boundary fusing agent, a reinforcing agent, a coupling agent, a crystal form control agent and water into the material obtained by the treatment in the step 4 according to a formula ratio, fully and uniformly mixing, then sending into a hydrothermal reaction kettle, continuously reacting for 12 hours at 180 ℃ under the pressure of 1MPa, and cooling to obtain the anti-oxidation coating.

Example 2

alumina accounting for 50 percent of the total mass of the coating, and accounting for 500 kg;

20kg of alkali metal grain boundary fusing agent accounting for 2 percent of the total mass of the coating; the alkali metal grain boundary fusing agent comprises 11kg of anorthite powder, 5kg of albite and 1kg of sodium fluosilicate, wherein the anorthite powder, the albite and the sodium fluosilicate respectively account for 55%, 40% and 5% of the total mass of the alkali metal grain boundary fusing agent;

the reinforcing agent accounts for 25 percent of the total mass of the coating and accounts for 250 kg; the reinforcing agent adopts silica sol with solid content of 10 percent;

3kg of coupling agent accounting for 0.3 percent of the total mass of the coating; the coupling agent adopts a DL171 silane coupling agent and is used for surface modification of alumina and a reinforcing agent;

the crystal form control agent accounts for 0.001 percent of the total mass of the coating, accounts for 0.01kg in total, and consists of ytterbium oxide with the purity of more than 99 percent and erbium oxide with the purity of more than 99 percent according to the weight ratio of 1: 2;

226.99kg of water accounting for 22.699 percent of the total mass of the coating.

step 1: fully dispersing a silane coupling agent by using absolute ethyl alcohol, wherein the mass ratio of the using amount of the silane coupling agent to the using amount of the absolute ethyl alcohol is 1: 2;

and step 3: feeding the alumina treated in the step 2 into a wet ball mill for ball milling for 2.5 hours;

and 4, step 4: performing ball milling on the alumina treated in the step 3 for 20min under a reduced pressure state to fully release ethanol, and finishing the modification of the alumina;

and 5: adding an alkali metal grain boundary fusing agent, a reinforcing agent, a coupling agent, a crystal form control agent and water into the alumina obtained by the treatment in the step 4 according to a formula ratio, fully and uniformly mixing, then sending into a hydrothermal reaction kettle, continuously reacting for 14h at 190 ℃ under the pressure of 2MPa, and cooling to obtain the anti-oxidation coating.

Example 3

alumina accounting for 47 percent of the total mass of the coating, and accounting for 470 kg;

25kg of alkali metal grain boundary fusing agent accounting for 2.5 percent of the total mass of the coating; the alkali metal grain boundary fusing agent comprises anorthite powder, albite and sodium fluosilicate, which respectively account for 60%, 35% and 5% of the total mass of the alkali metal grain boundary fusing agent, namely 15kg of anorthite powder, 8.75kg of albite and 1.25kg of sodium fluosilicate;

the reinforcing agent accounts for 28 percent of the total mass of the coating and accounts for 280 kg; the reinforcing agent adopts silica sol with solid content of 10 percent;

the coupling agent accounts for 0.5 percent of the total mass of the coating and accounts for 5 kg; the coupling agent adopts a DL171 silane coupling agent and is used for surface modification of alumina and a reinforcing agent;

the crystal form control agent accounts for 0.001 percent of the total mass of the coating, accounts for 0.01kg in total, and consists of ytterbium oxide with the purity of more than 99 percent and erbium oxide with the purity of more than 99 percent according to the weight ratio of 1: 1.5;

219.99kg of water accounting for 21.999 percent of the total mass of the coating.

step 1: fully dispersing a silane coupling agent by using absolute ethyl alcohol, wherein the mass ratio of the using amount of the silane coupling agent to the using amount of the absolute ethyl alcohol is 1: 1.5;

and step 3: feeding the alumina treated in the step 2 into a wet ball mill for ball milling for 2 hours;

and 5: adding an alkali metal grain boundary fusing agent, a reinforcing agent, a coupling agent, a crystal form control agent and water into the alumina obtained by the treatment in the step 4 according to a formula ratio, fully and uniformly mixing, then sending into a hydrothermal reaction kettle, continuously reacting for 13h at 180 ℃ under the pressure of 1MPa, and cooling to obtain the anti-oxidation coating.

Application method

The invention relates to an application of an anti-oxidation coating for a prebaked anode for reducing energy consumption of an aluminum electrolytic cell, which is characterized in that after the anti-oxidation coating is prepared, the anti-oxidation coating is sprayed on the side surface and the top surface of the prebaked anode with the surface temperature of 10-20 ℃, and the spraying is repeated for 3 times, and then the prebaked anode is stored for 24 hours in an open environment at room temperature to finish curing and curing. After the prebaked anode carbon block is taken out of the furnace, the temperature is over thousand ℃, water needs to be sprayed immediately for cooling, the surface temperature can be reduced to about 100 ℃ after the water is dried, and the prebaked anode carbon block can be generally placed in a warehouse for storage and cooling to room temperature. When the prebaked anode carbon block and the steel claw are connected by pouring molten phosphorus pig iron, the surface of the carbon block just after pouring the molten phosphorus pig iron is basically at normal temperature, so that the surface of the carbon block is still at normal temperature or slightly higher than normal temperature during spraying, and the spraying is controlled to be completed within five minutes after the molten phosphorus pig iron is poured; after the spraying is finished, the temperature of the molten iron is transferred to the surface of the carbon block about 2 hours, so that the temperature of the outer surface of the carbon block is raised by 40-50 ℃. The anti-oxidation coating is directly sprayed on the surface of the carbon block which is just poured with the phosphorus molten pig iron, and the temperature of the phosphorus molten pig iron is conducted to the surface of the carbon block, so that the temperature of the sprayed carbon block surface gradually rises by 40-50 ℃, the maintenance time can be effectively shortened, the maintenance of the inner layer coating and the timely discharge of the moisture of the inner layer coating are facilitated, the free moisture of the coating anode before the coating enters the tank is ensured to be drained, the phenomena of coating swelling and dropping caused by the fact that the free moisture is not drained are effectively prevented, the maintenance time is controlled to exceed 8 hours, and the phenomenon of coating swelling after the coating enters the tank is further prevented; and the mode can effectively save energy.

When the anti-oxidation coating is sprayed, the part of the four side surfaces of the carbon anode, which are 18cm away from the lower edge, is kept from being sprayed. The reason is that: the coating can be dissolved into the electrolyte when meeting the electrolyte, the depth of the electrolyte is about 18cm, the polar distance is about 4.5 cm, so the depth of the electrolyte inserted when the anode enters the electrolytic bath is 13.5 cm, and the electrolyte has 4-5 cm fluctuation, so 18cm below the four sides of the carbon anode can be dissolved after the bath even if being sprayed, and therefore 18cm below the carbon anode can not be sprayed.

Testing and Industrial applications

First, laboratory test

(1) Staged oxidation test

Uncoated areas (black annular areas without the coating) and coated areas (white for coating the anti-oxidation coating of the embodiment 1 of the invention) are left at intervals on the outer periphery of the test carbon material, and the test carbon material is calcined for 7 hours at a high temperature of 900 ℃. The specific result is shown in fig. 2, the carbon material in the coating area has no obvious change, and the carbon material in the uncoated area is oxidized, so that the anti-oxidation coating has excellent oxidation resistance, is firmly combined with the carbon material, and the high-temperature quick water-cooling coating does not crack or fall off.

(2) Calculation of weight loss ratio

Taking 12 groups of the same carbon blocks as test samples, coating 9 groups of the carbon blocks with the anti-oxidation coating prepared in the embodiments 1-3 of the invention as test groups, and taking the other three groups of carbon blocks without any coating as a control group; placing the experimental group and the carbon blocks of the control group into an environment of 900 ℃ to calcine for 72 hours, and respectively calculating the weight loss rate of the carbon blocks:

weight loss ratio

Wherein M is ₁ For pre-calcination mass, M ₂ Is the calcined weight; the weight loss rate of the carbon block is as follows:

and (3) taking the minimum Delta M% as judgment data, taking the Delta M% as the minimum weight loss rate in the experimental group or the control group, and judging the detection result: first-grade product: 1.0 percent or more and delta M percent or less than 1.5 percent of special grade product: delta M% < 1.0%. It can be seen that: two samples in example 1, three samples in example 2 and one sample in example 3 all reach the standard of the special best product, while the control group fails to reach the standard of the first grade judgment.

Second, industrial application

After the anti-oxidation coating prepared by the invention is used according to an application method, as shown in figure 3, (a) the upper end of the high anode scrap after the tank is stopped is not immersed in the electrolyte, the coating is intact, the surface of the carbon block has no oxidation consumption and large sectional area, the electrolyte is shrunk and solidified after the tank is stopped, the lower end of the carbon block is seriously exposed and oxidized, the sectional area is small, but the difference between the upper and lower sectional areas is small; (b) the middle is a non-coating electrode, and the surface is not protected by a coating material, so that the surface is uneven and seriously oxidized.

As shown in FIG. 4, the anode scrap is thickened by 13-18mm and the period of pole change is successfully prolonged by more than 1 day by the verification of the coating anode of the invention popularized and used by a plurality of electrolytic aluminum factories.

Thirdly, coating test of the anti-oxidation coating in the anode middle seam

The partial electrolytic cell is forced to stop due to the anodic oxidation and the depolarization of the middle seam, and the safe operation and the current efficiency of the electrolytic cell are seriously influenced. Therefore, the anode center line was tested for oxidation preventing effect. Specifically, the anti-oxidation coating prepared in the embodiment 1 of the invention is coated in the center seam of the anode, and then the maintenance is respectively carried out for 24 hours, 8 hours and 6 hours; the finished coated anodes were then placed in an electrolytic cell and the corresponding results are shown in figure 5. The test result shows that the coating is maintained for more than 24 hours, and the coating anode hardly has coating bulge; very little swelling was seen with 8 hours of curing, and significant swelling was seen with 6 hours of curing.

The tests show that the oxidation coating provided by the invention can better cover the side surface of the center seam of the carbon anode for a long time in the high-temperature environment of the electrolytic cell, so that the erosion of surrounding gas to the carbon anode is reduced, the oxidation and slag removal of the carbon block are relieved, and the center seam anode oxidation is effectively prevented; the coating can meet the requirement of oxidation resistance after being cured for more than 8 hours, and the curing time is optimal for 24 hours.

Fourthly, the actual effect of the anti-oxidation coating applied to the actual prebaked anode

The aluminum electrolysis prebaked anode using the oxidation coating provided by the invention is used as an experimental group, the aluminum electrolysis prebaked anode not using any coating is used as a control group, and the using effects in the production processes of the two are recorded, specifically as follows:

(1) compared with the carbon slag amount of a control group, the carbon slag amount of the experimental group is reduced to 600 tons/year from 1500 tons/year, and the carbon slag amount is reduced by about 60 percent;

(2) compared with the control group, the average working voltage of the experimental group is reduced to 3921mv from 3934mv, and the absolute value is reduced by 13mv (carbon residue in electrolyte is reduced, and electrolyte resistance is reduced);

(3) compared with a control group, the aluminum amount of the experimental group is increased from 2.799 tons/day to 2.846 tons/day, and the absolute value is increased by 0.047 tons/day (the oxidation of a middle seam is reduced, and the current efficiency is increased due to the reduction of horizontal current);

(4) compared with a control group, the current efficiency of the experimental group is improved to 90.56% from 89.07, the absolute value is increased by 1.49%, and the power consumption per ton of aluminum can be reduced by about 200 kilowatt-hour; (the oxidation of the middle seam is reduced, and the current efficiency is improved due to the reduction of horizontal current);

(5) the average effective polar distance is increased from 4.3 cm to 4.8 cm (caused by reduction of carbon slag in electrolyte, improvement of alumina solubility and reduction of furnace bottom precipitation) compared with the control group;

(6) the one-day pole changing period of the anode is prolonged, and the ton aluminum carbon consumption is reduced by 14.7 kilograms;

(7) the electricity price is calculated according to 0.4 yuan/kilowatt hour, 1mv corresponds to 3.3 kilowatt hours, the comprehensive alternating current of the aluminum ingot is subjected to nuclear reaction according to 13500 kilowatt hours/ton aluminum, the anode price is calculated according to 6000 yuan/ton, the selling price of one ton of electrolytic aluminum is calculated according to 19000 yuan/ton, and then the comprehensive benefits of each ton of electrolytic aluminum after the coating technology is applied are as follows:

the voltage is reduced by 13mv, 13mv is 3.3 kilowatt-hour/mv is 42.9 kilowatt-hour;

the aluminum yield per ton of aluminum is increased by 47 kg/2.799-16.8 kg-16.8 x 19 yuan/kg-319.2 yuan;

the current efficiency is improved by 1.49%, and electricity is saved by about 200 kilowatt-hours for each ton of aluminum;

the carbon consumption of aluminum per ton is reduced by 14.7 kg;

therefore, the total benefit is: 42.9 × 0.4+319.2+200 × 0.4+14.7 × 6 ═ 504.56 yuan/day.

The above-described examples are merely illustrative of preferred embodiments of the present invention and do not limit the scope of the present invention. Various modifications and alterations of this invention will become apparent to those skilled in the art without departing from the spirit and principles of this invention, and it is intended to cover such modifications and alterations in the invention as fall within the true spirit and scope of the appended claims.

Claims

1. The pre-baked anode anti-oxidation coating for reducing the energy consumption of the aluminum electrolytic cell is characterized by comprising the following components in percentage by mass: 45 to 50 percent of alumina, 2 to 3 percent of alkali metal crystal boundary fusing agent, 25 to 30 percent of reinforcing agent, 0.3 to 0.8 percent of coupling agent, 0.001 percent of crystal form control agent and 16.2 to 27.7 percent of water.

2. The pre-baked anode anti-oxidation coating for reducing the energy consumption of the aluminum electrolytic cell according to claim 1, wherein the alkali metal grain boundary fusing agent comprises 50-62% of anorthite powder, 35-40% of albite and 1-15% of sodium fluosilicate.

3. The pre-baked anode oxidation resistant coating for reducing energy consumption of aluminum reduction cell as claimed in claim 1, wherein the reinforcing agent is silica sol with 10% solid content.

4. The pre-baked anode anti-oxidation coating for reducing the energy consumption of the aluminum electrolytic cell as recited in claim 1, wherein the coupling agent is DL171 silane coupling agent.

5. The pre-baked anode oxidation resistant coating for reducing the energy consumption of an aluminum electrolysis cell as claimed in claim 1, wherein the crystal form control agent comprises ytterbium oxide with a purity of more than 99% and erbium oxide with a purity of more than 99%, and the weight ratio of the ytterbium oxide to the erbium oxide is 1: 1-2.

6. The preparation method of the prebaked anode anti-oxidation coating for reducing the energy consumption of the aluminum electrolytic cell according to any one of claims 1 to 5, comprising the steps of:

step 1: dispersing a silane coupling agent by using absolute ethyl alcohol, wherein the mass ratio of the using amount of the silane coupling agent to the using amount of the absolute ethyl alcohol is 1: 1-2;

and 2, step: uniformly spraying the silane coupling agent treated in the step 1 on the surface of the alumina;

and step 3: feeding the alumina obtained by the treatment in the step 2 into a wet ball mill for ball milling for 1-2.5 hours;

and 4, step 4: carrying out reduced pressure ball milling on the alumina treated in the step 3 for 20-40min under the stirring of 25-55 ℃;

and 5: adding the alkali metal grain boundary fusing agent, the reinforcing agent, the coupling agent, the crystal form control agent and the water into the alumina obtained by the treatment in the step 4 according to the formula proportion, uniformly mixing, sending into a hydrothermal reaction kettle, continuously reacting for 10-14h at the temperature of 190 ℃ and under the pressure of 0.5-2MPa, and cooling to obtain the anti-oxidation coating.

7. The use of the coating for preventing oxidation of prebaked anode for reducing energy consumption of aluminum reduction cell as claimed in any one of claims 1 to 5, wherein said coating is used for preventing oxidation of prebaked anode for aluminum reduction cell.

8. The use of the anti-oxidation coating for prebaked anode to reduce energy consumption of aluminum reduction cell as claimed in claim 7, wherein the anti-oxidation coating is sprayed on the side and top surfaces of the prebaked anode with a surface temperature of 10-60 ℃, and then stored in an open environment at room temperature for more than 8 hours for curing and aging.

9. The application of the anti-oxidation coating for prebaked anode of claim 7 to reduce the energy consumption of aluminum reduction cell, wherein the carbon anode and the anode steel claw are cast and connected by the phosphorus molten pig iron to form the prebaked anode, and then the anti-oxidation coating is sprayed on the side surface and the top surface of the prebaked anode with the surface temperature of 10-60 ℃, after the spraying is completed, the heat brought by the phosphorus molten pig iron is gradually conducted to the outer surface of the prebaked anode to raise the temperature of the outer surface of the prebaked anode by 30-50 ℃, and then the prebaked anode is stored for more than 8 hours to complete curing and aging.

10. The use of the pre-baked anode anti-oxidation coating for reducing the energy consumption of the aluminum reduction cell as recited in claim 7, wherein the carbon anode is not sprayed within a distance of 18cm from the lower edge of the four side surfaces of the carbon anode during spraying.