Soaked carbon anode carbon block and preparation method thereof

Abstract

The invention provides an anode carbon block soaked with carbon. An adhesive for the anode carbon block soaked with the carbon comprises the following raw material components in parts by weight: 50-55 parts of coal pitch, 25-30 parts of borax, 10-15 parts of kaolin, 30-35 parts of industrial phosphoric acid, 40-45 parts of carbon tetrachloride and 50-55 parts of water. The preparation method of the soaked carbon anode carbon block comprises the following steps: measuring the surface temperature of an anode cooked block by using an infrared temperature measuring gun, slowly putting the anode cooked block into a soaking pool, keeping for 30-60 seconds, keeping for 25-35 seconds in the air, and then putting the anode cooked block into a drying oven for drying, thereby obtaining the soaked carbon anode carbon block. The service life of the anode carbon block obtained through the preparation method of the soaked carbon anode carbon block is prolonged, the pole changing period of the anode carbon block is increased to 36 days or above from 34 days, the anode carbon consumption is reduced, and the electrolytic bath process is stabilized.

Description

Technical Field

[0001] This invention relates to the field of anode carbon block impregnation coating material preparation technology, and particularly to an impregnation carbon anode carbon block composition and a method for preparing the impregnation carbon anode carbon block. Background Technology

[0002] The electrolytic aluminum industry has entered a phase of resource-saving and environmentally friendly green industrial development. The commonly used 400KA series electrolytic cells now employ anode carbon blocks with dimensions of 1550mm × 660mm × 700mm. Anode carbon blocks refer to carbon blocks produced using petroleum coke or pitch coke as aggregates and coal tar pitch as a binder. The macroscopic structure of petroleum coke or pitch coke is honeycomb-like or fibrous, with numerous pores of varying sizes and uneven distribution on its surface and interior. During the roasting process, the coal tar pitch, due to its own decomposition, condensation, and carbonization to form pitch coke, also creates many pores of varying sizes. The presence of these pores affects the physical and chemical properties of the prebaked anode, impacting its mechanical strength, elastic modulus, thermal conductivity, and electrical conductivity. Prebaked anodes with higher porosity oxidize faster at certain temperatures, exhibit reduced corrosion resistance, and are more easily permeated by gases or liquids, resulting in prebaked anodes with poorer performance.

[0003] Under the premise of unchanged effective area of ​​the electrolytic cell chamber, the poor oxidation resistance of the anode carbon block and its rapid oxidation consumption directly restrict the service life of the anode carbon block. The electrolytic aluminum industry generally suffers from high costs, low efficiency, and high labor intensity for workers. Specifically, the disadvantages of the anode carbon block with dimensions of 1550mm×660mm×700mm (length×width×height) in the commonly used 400KA series electrolytic cells are: due to the poor oxidation resistance of the anode carbon block in the electrolytic cell chamber, the carbon block begins to oxidize and turn red within 2 to 3 days. The rapid consumption of the carbon block and the large amount of slag shedding in the electrolytic cell result in high cell temperature, affecting aluminum production. The rapid oxidation consumption of the anode carbon block shortens the anode service life, which is generally around 34-35 days. The high frequency of anode replacement leads to high labor intensity for electrolytic workers, and the high frequency of replacement significantly impacts process control such as the thermal balance of the electrolytic cell. The heavy weight of the residual anode produced in electrolytic aluminum production and the high anode carbon consumption directly affect the production cost of electrolytic aluminum. Summary of the Invention

[0004] The purpose of this invention is to overcome the defects of the prior art and provide a binder raw material composition for impregnating carbon anode blocks. The anode blocks prepared by this impregnation preparation method are prepared by mixing, grinding and sieving coal tar pitch, borax and kaolin in a crusher and adding the residue. The service life of the anode blocks obtained by this impregnation preparation method is extended, the anode replacement cycle is increased from 34 days to more than 36 days, the anode carbon consumption is reduced and the electrolytic cell process is stabilized.

[0005] To achieve the above objectives, the present invention provides an adhesive for impregnating carbon anode blocks, the adhesive comprising, by weight: 50-55 parts coal tar pitch, 25-30 parts borax, 10-15 parts kaolin, 30-35 parts industrial phosphoric acid, 40-45 parts carbon tetrachloride, and 50-55 parts water.

[0006] The adhesive is used as an antioxidant adhesive for the carbon anode blocks of electrolytic aluminum; the coal tar pitch is high-temperature coal tar pitch with a softening temperature of 100℃~110℃; the kaolin contains Al2O3≥55% and Fe2O3≤1%; the borax is industrial disodium tetraborate decahydrate; and the industrial phosphoric acid contains H3PO4>85%.

[0007] The method for preparing the antioxidant adhesive for electrolytic aluminum carbon anode blocks involves mixing and grinding coal tar pitch, borax, and kaolin in a crusher, sieving them through a 100-110 mesh sieve, and then placing them in a mixer. Half of the industrial phosphoric acid and water are added and mixed to dissolve the mixture, while simultaneously heating it to 110°C and stirring until fully dissolved. After aging for 2-4 hours, the aged slurry is mixed with carbon tetrachloride, the remaining industrial phosphoric acid, and water, and stirred for 20-30 minutes to obtain the adhesive.

[0008] The viscosity of the impregnating agent can be controlled between 0.1 and 2 Pa·s by adjusting the heating and stirring time according to actual usage needs.

[0009] The function of this antioxidant adhesive is to seal the pores on the surface of the substrate, reducing the contact area between the carbon anode substrate and oxygen at high temperatures. The introduction of alumina itself acts as an insulator, providing strong antioxidant effects. The addition of borax ensures that the coefficients of thermal expansion of the coating and the substrate are not significantly different, thus easing thermal stress and improving bonding strength. Industrial phosphoric acid is added primarily to act as a binder; carbon tetrachloride is added to fully dissolve the coal tar pitch.

[0010] To achieve the above objectives, the present invention also provides a method for preparing impregnated carbon anode blocks, specifically comprising the following steps:

[0011] Step 1: Hoist the cleaned anode blocks (carbon anode blocks) from the carbonization furnace to the soaking line;

[0012] Step 2: Use an infrared thermometer to measure the surface temperature of the anode block, and control the surface temperature of the anode carbon block to be maintained between 110℃ and 130℃; the hot block can better absorb the adhesive that penetrates into the carbon block during the soaking process.

[0013] Step 3: Slowly place the anolyte into the soaking tank and hold for 30-60 seconds before lifting it out. The length of time the anolyte is soaked in the adhesive directly affects how much adhesive the carbon block absorbs. To enhance the oxidation resistance of the carbon block, the service life of the carbon block can be appropriately extended, and the soaking time of the carbon block in the adhesive liquid can be extended as much as possible.

[0014] Step 4: After leaving the carbon block in the air for 25-35 seconds, immerse it again in the adhesive for 8-12 seconds and then lift it up. Because the carbon block itself is at a high temperature during the first immersion, a layer of gas will form around the carbon block and the adhesive during the immersion process to prevent the adhesive from penetrating. Therefore, immersing the carbon block in the adhesive again allows the carbon block to fully absorb the adhesive liquid, thereby enhancing the oxidation resistance of the carbon block and extending its service life.

[0015] Step 5: After the bottom of the anodic curing block stops dripping adhesive liquid after soaking, store the anodic curing block in the air-drying area. When the carbon block is lifted from the soaking tank, a large amount of adhesive liquid will be lifted along with the carbon block. In order to avoid wasting adhesive liquid and save costs, wait until the bottom of the carbon block stops dripping adhesive liquid before transporting the carbon block to the storage area.

[0016] Step Six: The anode carbon blocks must be left to stand for 24 hours before use. Because the surface of the soaked anode carbon blocks or the inside of the carbon bowl will be damp or contain residual adhesive liquid, directly delivering them to the anode assembly workshop could affect operations and potentially cause a "fire." For safety, the soaked anode carbon blocks must be stored for 24 hours to allow the adhesive on the surface to dry before being delivered to the anode assembly workshop. This invention achieves the goals of increasing electrolytic aluminum production, reducing consumption, and improving efficiency. The soaking method for anode carbon blocks in this invention is highly portable and practical.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. This invention increases the output of electrolytic aluminum water, reduces anode consumption, and lowers the labor intensity of workers changing electrodes by soaking 400KA anode carbon blocks. The soaking method of anode carbon blocks in this invention has high portability and strong practicality.

[0019] 2. Under the premise that all configurations such as the electrolytic cell busbar and cell chamber remain unchanged, this invention, combined with the actual space configuration of the electrolytic cell, significantly improves the oxidation resistance of the anode carbon blocks and significantly reduces slag shedding. This increases the aluminum production of a single electrolytic cell. Combined with the actual space configuration of the electrolytic cell, the service life of the anode carbon blocks increases from 34-35 days to 36 days, significantly reducing the labor intensity of electrolysis workers, reducing process fluctuations such as electrolytic cell thermal balance caused by electrode replacement, and lowering anode carbon consumption in aluminum plants.

[0020] 3. Soaking the anode carbon blocks in a specific binder solution aims to improve their oxidation resistance in the electrolytic cell. Soaking increases the oxidation resistance of the anode carbon blocks in the electrolytic cell from 2-3 days to 3-5 days before they begin to show signs of oxidation, reducing the amount of slag falling off the carbon blocks and alleviating the labor intensity of electrolysis workers. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of this invention clearer, the following detailed description, in conjunction with embodiments, is provided to enable those skilled in the art to fully understand the technical content of this invention. It should be understood that the following embodiments are for further illustration of this invention and should not be construed as limiting the scope of protection of this invention. Non-essential improvements and adjustments made by those skilled in the art based on the above description of this invention are all within the scope of protection of this invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make appropriate selections within the range based on the description herein, and are not intended to be limited to the specific values ​​in the examples below.

[0022] This invention provides a method for preparing impregnated carbon anode blocks. The specific impregnation steps are as follows: ① The cleaned anode blocks are hoisted to the impregnation area. ② The surface temperature of the anode blocks is measured using an infrared thermometer. The surface temperature of the anode blocks should be maintained between 110℃ and 130℃. A hot block can better absorb the adhesive and penetrate into the carbon block during impregnation. ③ The blocks are impregnated in the impregnation tank for 30-60 seconds and then hoisted. The length of time the carbon blocks are impregnated in the adhesive directly affects the amount of adhesive absorbed. To enhance the oxidation resistance of the carbon blocks and extend their service life, the impregnation time in the adhesive liquid should be extended as much as possible. ④ After about 30 seconds, the carbon blocks are impregnated again in the adhesive liquid for 10 seconds and then hoisted. Because the carbon blocks are at a high temperature during the first impregnation, a layer of gas will form around the carbon blocks and adhesive during the impregnation process, preventing the adhesive from penetrating. Therefore, impregnating the carbon blocks again in the adhesive liquid allows them to fully absorb the adhesive liquid, thereby enhancing their oxidation resistance and extending their service life. ⑤ Once the bottom of the carbon block stops dripping adhesive liquid after soaking, it can be stored in the storage area. When lifting the carbon block from the soaking tank, a large amount of adhesive liquid will be lifted along with it. To avoid wasting adhesive liquid and save costs, wait until the bottom of the carbon block stops dripping adhesive liquid before transporting it to the storage area. ⑥ After 24 hours, it can be delivered to the downstream workshop for use. Because the surface of the soaked anode carbon block or the inside of the carbon bowl will be relatively damp or have residual adhesive liquid, if it is delivered directly to the anode assembly workshop, the damp carbon block may affect the operation of the anode assembly workshop and may cause a "fire". For safety, the soaked anode carbon block must be stored for 24 hours to allow the adhesive on the surface of the carbon block to dry before being delivered to the anode assembly workshop for use.

[0023] The production line used in this invention is simple: (1) One soaking tank: 14m*2.7m*1.5m in length*width*height; (2) Sufficient adhesive (prepare according to actual conditions); (3) One infrared thermometer; (4) Safety goggles, work gloves and other work protection supplies; (5) The temperature of the production site can be at room temperature. Through the above invention, the purpose of increasing production, reducing consumption and improving efficiency of electrolytic aluminum is achieved. The soaking mode of the anode carbon block in this invention has high portability and strong practicality. Increase the service life of the anode carbon block: extend the anode replacement cycle from 34-35 days to 36 days, reduce anode carbon consumption and stabilize the electrolytic cell process.

[0024] Example 1

[0025] The method for preparing impregnated carbon anode blocks provided in this embodiment includes a binder component comprising 55 parts coal tar pitch, 30 parts borax, 15 parts kaolin, 35 parts industrial phosphoric acid, 45 parts carbon tetrachloride, and 55 parts water per kg.

[0026] The preparation method of this adhesive involves mixing and grinding coal tar pitch, borax, and kaolin in a crusher, sieving the mixture through a 110-mesh sieve, and then placing it into a mixer. Half of the industrial phosphoric acid and water are added and mixed to dissolve the mixture, while simultaneously heating to 110°C and stirring until fully dissolved. After aging for 3 hours, the aged slurry is mixed with carbon tetrachloride, the remaining industrial phosphoric acid, and water, and stirred for 30 minutes to obtain the adhesive. The specific soaking steps are as follows:

[0027] (1) The cleaned carbon anode blocks are hoisted from the carbonization furnace to the soaking line;

[0028] (2) Use an infrared thermometer to measure the surface temperature of the anode carbon block and keep it between 115℃ and 120℃;

[0029] (3) Slowly place the anode carbon block into the soaking tank and hold for 55 seconds before lifting it out;

[0030] (4) After being left in the air for 35 seconds, the anode carbon block is soaked in the adhesive again for 12 seconds and then lifted.

[0031] (5) After the anode carbon block has finished soaking and no more adhesive liquid is dripping from the bottom, store it in an air-drying area;

[0032] (6) The anode carbon block should be used after being placed for 24 hours.

[0033] With all configurations of the electrolytic cell, including the busbar and tank, remaining unchanged, and considering the actual space configuration of the electrolytic cell, soaking the anode carbon blocks improved their oxidation resistance to a certain extent, reduced slag shedding within the electrolytic cell, lowered the cell temperature, and increased the aluminum output per unit. The service life of the anode carbon blocks increased from 34-35 days to 36 days, reducing the labor intensity of electrolysis workers, minimizing fluctuations in the electrolytic cell process caused by electrode replacement, and lowering the anode consumption of the aluminum plant.

[0034] Example 2

[0035] The method for preparing impregnated carbon anode blocks provided in this embodiment includes the following binder components, by weight: 52 parts coal tar pitch, 28 parts borax, 12 parts kaolin, 30 parts industrial phosphoric acid, 43 parts carbon tetrachloride, and 54 parts water.

[0036] The preparation method of this adhesive involves mixing and grinding coal tar pitch, borax, and kaolin in a crusher, sieving the mixture through a 100-mesh sieve, and then placing it into a mixer. Half of the industrial phosphoric acid and water are added and mixed to dissolve the mixture, while simultaneously heating to 110°C and stirring until fully dissolved. After aging for 2 hours, the aged slurry is mixed with carbon tetrachloride, the remaining industrial phosphoric acid, and water, and stirred for 28 minutes to obtain the adhesive. The specific soaking steps are as follows:

[0037] (1) The cleaned carbon anode blocks are hoisted from the carbonization furnace to the soaking line;

[0038] (2) Use an infrared thermometer to measure the surface temperature of the anode carbon block and keep it between 112℃ and 125℃;

[0039] (3) Slowly place the anode carbon block into the soaking tank and hold for 50 seconds before lifting it out;

[0040] (4) After being left in the air for 30 seconds, the anode carbon block is immersed in the adhesive again for 0 seconds and then lifted.

[0041] (5) After the anode carbon block has finished soaking and no more adhesive liquid is dripping from the bottom, store it in an air-drying area;

[0042] (6) The anode carbon block should be used after being placed for 24 hours.

[0043] Example 3

[0044] The method for preparing impregnated carbon anode blocks provided in this embodiment includes the following binder components by weight: 50 parts coal tar pitch, 25 parts borax, 10 parts kaolin, 35 parts industrial phosphoric acid, 40 parts carbon tetrachloride, and 52 parts water.

[0045] The preparation method of this adhesive involves mixing and grinding coal tar pitch, borax, and kaolin in a crusher, sieving the mixture through a 100-mesh sieve, and then placing it into a mixer. Half of the industrial phosphoric acid and water are added and mixed to dissolve the mixture, while simultaneously heating to 110°C and stirring until fully dissolved. After aging for 2.5 hours, the aged slurry is then mixed with carbon tetrachloride, the remaining industrial phosphoric acid, and water, and stirred for 30 minutes to obtain the adhesive. The specific soaking steps are as follows:

[0046] (1) The cleaned carbon anode blocks are hoisted from the carbonization furnace to the soaking line;

[0047] (2) Use an infrared thermometer to measure the surface temperature of the anode carbon block and keep it between 110℃ and 120℃;

[0048] (3) Slowly place the anode carbon block into the soaking tank and hold for 50 seconds before lifting it out;

[0049] (4) After leaving it in the air for 25 seconds, immerse the anode carbon block in the adhesive again for 10 seconds and then lift it up;

[0050] (5) After the anode carbon block has finished soaking and no more adhesive liquid is dripping from the bottom, store it in an air-drying area;

[0051] (6) The anode carbon block should be used after being placed for 24 hours.

[0052] Specific practical application cases are recorded as follows: Case 1: On April 19th, the first batch of 48 soaked carbon blocks (one cycle) were delivered to the anode assembly workshop for casting. They were then used in an electrolytic cell in the electrolysis workshop starting April 23rd. This experiment continued until May 29th when the anode was removed from the cell, a usage period of 36 days, longer than that of ordinary anodes. No abnormalities occurred during use. The average residual anode thickness after removal was 19.5 cm.

[0053] Case Study 2: On June 15th, a second batch of 96 soaked carbon blocks (two cycles) were delivered to the electrolytic cell for use, and they were removed from the cell on August 28th. Each cycle lasted 36 days, one day longer than the 35 days for ordinary blocks. During this period, the increased oxidation resistance of the carbon blocks and the extended lifespan resulted in lower carbon consumption in the electrolytic cell. Furthermore, the reduced carbon residue in this electrolytic cell compared to other cells during this period led to a lower cell temperature compared to other electrolytic cells.

[0054] Case Study 3: On September 23rd, the third batch of 56 electrolytic cells across two cycles began large-scale use. During this period, the 56 electrolytic cells operated smoothly. The usage cycle was 36 days, one day longer than the standard usage cycle. The average thickness of the residual electrode was 18.5 cm. Compared to the standard cells, the experimental cells showed a significant reduction in slag shedding.

[0055] Immersion experiments extended the anode replacement cycle from 34-35 days to 36 days, reduced anode carbon consumption, stabilized the electrolytic cell process, improved the oxidation resistance of carbon blocks, reduced the amount of slag falling off the carbon blocks in the electrolytic cell, lowered the electrolytic cell temperature, and increased the aluminum production of a single electrolytic cell.

[0056] It should be noted that the above preferred embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A type of impregnated carbon anode block, characterized in that, The binder raw material components of the impregnated carbon anode carbon block include: 50-55 parts coal tar pitch, 25-30 parts borax, 10-15 parts kaolin, 30-35 parts industrial phosphoric acid, 40-45 parts carbon tetrachloride, and 50-55 parts water.

2. The soaked carbon anode block according to claim 1, characterized in that: The coal tar pitch is a high-temperature coal tar pitch with a softening temperature of 100℃~110℃.

3. The soaked carbon anode block according to claim 2, characterized in that: The kaolin contains ≥55% Al2O3 and ≤1% Fe2O3.

4. The impregnated carbon anode block according to claim 3, characterized in that: The borax mentioned is industrial disodium tetraborate decahydrate.

5. The soaked carbon anode block according to claim 4, characterized in that: The industrial phosphoric acid contains >85% H3PO4.

6. The impregnated carbon anode block according to claim 1, characterized in that: The binder for the electrolytic aluminum carbon anode carbon block is made by mixing and grinding coal tar pitch, borax, and kaolin in a crusher, sieving the mixture through a 100-110 mesh sieve, and then placing it into a mixer. Half of the industrial phosphoric acid and water are added and mixed to dissolve the mixture. The mixture is heated to 110°C and stirred until fully dissolved. After aging for 2-4 hours, the mixture is allowed to mature.

7. The impregnated carbon anode block according to claim 6, characterized in that: The aged slurry, carbon tetrachloride, remaining industrial phosphoric acid, and water are then mixed and stirred for 20-30 minutes to obtain the adhesive.

8. A method for preparing an impregnated carbon anode block according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step 1: Hoist the cleaned anode blocks from the carbonization furnace to the soaking line; Step 2: Measure the surface temperature of the anode block using an infrared thermometer. Step 3: Slowly place the anode block into the soaking tank and hold for 30-60 seconds before lifting it out; Step 4: After leaving it in the air for 25-35 seconds, soak it again; Step 5: After the bottom of the anolyte block stops dripping adhesive liquid after soaking, store the anolyte block in an air-drying area. Step 6: The anode block is placed for 24 hours before use.

9. The method for preparing the impregnated carbon anode block according to claim 8, characterized in that: The surface temperature described in step two is controlled between 110℃ and 130℃.

10. The method for preparing the impregnated carbon anode block according to claim 9, characterized in that: After soaking in the adhesive again for 8-12 seconds as described in step four, lift it up.

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