Method for filling and sealing screw holes of carbon anode plate for fluorine production by medium-temperature electrolysis

Abstract

The application discloses a method for filling and sealing screw holes of carbon anode plates for fluorine production by medium-temperature electrolysis, which fills conductive glue between screw holes of the carbon anode plates and bolts, and then coats sealing glue at the screw holes, so that the filling and sealing of the screw holes of the carbon anode plates for fluorine production by medium-temperature electrolysis are completed, the special performance of the material around the screw holes of the carbon anode plates is successfully improved, the polarization times during the operation of the carbon anode plates are reduced, the corrosion of electrolyte seepage into the expanded hole to the screw rod is effectively prevented, and the service life of the carbon anode plates is greatly prolonged.

Description

Technical Field

[0001] This invention relates to an improved method for carbon anode plates, and more particularly to a method for filling and sealing screw holes in carbon anode plates used in medium-temperature electrolytic fluorine production, belonging to the field of electrolytic fluorine production technology. Background Technology

[0002] The carbon anode plates in existing medium-temperature electrolytic cells use a screw connection method, which results in numerous polarization cycles and a short lifespan. After the electrolytic cell is removed, corrosion of the copper screw and breakage of the carbon anode plates along the direction of the copper screw are frequently observed. Analysis revealed that neither the copper screw nor the carbon anode plate is an elastic material. Conventional connection methods between the copper screw and the carbon anode plate cannot guarantee a perfect fit, leaving numerous gaps between the threads. The poor sealing at the connection point resulted in electrolyte seeping into the copper screw through these gaps during electrolytic cell operation, corroding the copper screw. Thermal expansion further enlarged the gaps, increasing the contact resistance between the carbon anode plate and the copper screw, leading to frequent anodic polarization. The anodic reaction at the corrosion sites generated a large amount of electrolytic gas in the gaps. This increased resistance significantly raised the temperature at the connection point, causing irregular melting of the corroded threads. This trapped gas cavities within the gaps, which continued to expand at the rising temperature, ultimately causing the carbon anode plate to crack along this direction. Summary of the Invention

[0003] To address the technical problems of high polarization frequency and short lifespan of carbon anode plates used in existing medium-temperature electrolytic cells, the present invention aims to provide a method for filling and sealing the screw holes of carbon anode plates used in medium-temperature electrolytic fluorine production. This method utilizes conductive and heat-resistant conductive adhesive and heat-resistant and fluorine-resistant sealant to fill and seal the gaps at the contact points between the screw holes and bolts. This improves the sealing performance of the screw holes while further reducing the overall resistance of the carbon anode, thereby lowering the carbon anode temperature and preventing cracking at the screw holes. This has a positive effect on reducing the frequency of polarization of the carbon anode plate and can significantly extend its service life.

[0004] To achieve the above-mentioned technical objectives, the present invention provides a method for filling and sealing the screw holes of a carbon anode plate used in medium-temperature electrolytic fluorine production, the method comprising the following steps:

[0005] 1) A screw hole is made at the center of the formed carbon anode plate;

[0006] 2) After filling the screw hole with conductive adhesive, immediately screw the bolt into the screw hole;

[0007] 3) After cleaning up any excess conductive adhesive that overflows from the bolt hole after screwing in the bolt, cure the conductive adhesive by heating.

[0008] 4) Apply sealant to the contact area between the screw holes and bolts on the carbon anode plate until there are no gaps and the conductive adhesive is exposed;

[0009] 5) After cleaning up any excess sealant, cure the sealant by heating.

[0010] When uncured conductive adhesive and uncured sealant do not rapidly miscible, and their curing conditions are similar, the curing step of the conductive adhesive can be omitted. The sealant can be applied first, and then cured. Alternative solutions include the following steps:

[0011] 1) A screw hole is made at the center of the formed carbon anode plate;

[0012] 2) After filling the screw hole with conductive adhesive, immediately screw the bolt into the screw hole;

[0013] 3) After cleaning up the excess conductive adhesive that overflows from the screw hole after screwing in the bolt, apply sealant to the contact area between the screw hole and the bolt on the carbon anode plate until there are no gaps and the conductive adhesive is exposed.

[0014] 4) After cleaning up the excess conductive sealant, use heat to cure the conductive adhesive and sealant.

[0015] This invention uses conductive adhesive to fill the contact area between the screw hole and the bolt on the carbon anode plate and then uses sealant for surface sealing. Firstly, the conductive adhesive has adhesive properties, which, after curing, better secures the bolt within the screw hole. Secondly, the conductive adhesive, being liquid before curing, has good fluidity, allowing it to fully fill the space between the bolt and the screw hole. After curing, it ensures complete adhesion, preventing gaps and improving the seal between the bolt and the screw hole, thus preventing electrolyte seepage and corrosion of the bolt. Thirdly, the conductive adhesive becomes conductive after curing, reducing the contact resistance between the bolt and the carbon anode plate, as well as the overall resistance of the carbon anode. This lowers the temperature at the contact point between the carbon anode and the bolt, preventing irregular melting of the bolt threads and preventing cracking of the screw hole due to thermal expansion of the carbon anode plate. Since the conductive adhesive has relatively poor corrosion and fluorine resistance, further coating its surface with sealant effectively solves this problem. The sealant further seals any small gaps caused by the shrinkage of the conductive adhesive during curing at the contact point between the screw hole and the bolt, while simultaneously forming a protective layer on the conductive adhesive surface. After the contact points between the screw holes and bolts of the carbon anode plate are filled with conductive adhesive and sealed with sealant, it has a positive effect on reducing the frequency of polarization of the carbon anode plate and can significantly extend the service life of the carbon anode plate.

[0016] As a preferred embodiment, the screw hole has a gradient diameter from its bottom to its top. Specifically, the diameter from the bottom of the screw hole to a depth of 30-40 mm is 1-2 mm larger than the bolt diameter, and the diameter from the bottom of the screw hole to the top of the screw hole is 10-12 mm larger than the bolt diameter. Generally, the bolt and screw hole diameters match perfectly. However, to ensure sufficient filling of the conductive adhesive between the bolt and the screw hole, and to facilitate sealing with the sealant, the screw hole can be appropriately enlarged. Enlarging the bottom of the screw hole primarily facilitates the filling of the conductive adhesive, while enlarging the top of the screw hole primarily facilitates the sealing with the sealant, achieving better filling and sealing effects.

[0017] As a preferred embodiment, the conductive adhesive is a high-temperature resistant conductive adhesive that cures at room temperature or medium temperature. As another preferred embodiment, the conductive adhesive includes at least one of the following: Double Bond DB2014, Double Bond DB5018, Pinyiheng PH8011, and Pinyiheng PH8018. The preferred conductive adhesive contains a matrix resin and conductive fillers, such as carbon powder or copper powder, which have good high-temperature resistance. After curing or drying, the conductive adhesive exhibits conductivity, enabling a conductive connection between the screw and the screw hole of the carbon anode plate, thus reducing the overall resistance of the carbon anode plate.

[0018] As a preferred embodiment, the amount of conductive adhesive filling the screw hole is 10-20% of the screw hole volume. If the amount of conductive adhesive filling is too low, the sealing effect cannot be achieved; if the amount filling is too high, the excess conductive adhesive will overflow and will be detrimental to the subsequent sealing process.

[0019] As a preferred embodiment, the sealant is a medium-to-high temperature resistant and corrosion-resistant sealant. As a preferred embodiment, the sealant includes at least one of Pinyiheng 7370, Pinyiheng 7450, and Pinyiheng 7570. The preferred sealant has good corrosion resistance (fluorine resistance) and can protect the conductive adhesive.

[0020] This invention provides an optimized and improved method for carbon anode plates, specifically a method for filling and sealing the screw holes of carbon anode plates used in medium-temperature electrolytic fluorine production. More specifically, by injecting conductive adhesive between the screw holes and bolts of the carbon anode plate, and then applying corrosion-resistant sealant to the screw openings, the screw holes of the carbon anode plate used in medium-temperature electrolytic fluorine production are filled and sealed. This improves the bonding strength and fixing effect between the carbon anode plate and the bolts. At the same time, while improving the sealing performance of the screw holes, it reduces the overall resistance of the carbon anode, thereby lowering the carbon anode temperature and preventing cracking at the screw holes. This has a positive effect on reducing the frequency of polarization of the carbon anode plate and can significantly extend the service life of the carbon anode plate.

[0021] The method for filling and sealing the screw holes of a carbon anode plate for medium-temperature electrolytic fluorine production of the present invention includes the following steps:

[0022] 1) A screw hole is made at the center of the upper surface of the medium-temperature electrolytic fluorine production carbon anode plate;

[0023] 2) Pour an appropriate amount of conductive glue into the drilled screw hole, and then immediately screw the copper bolt into the carbon anode plate at a uniform speed.

[0024] 3) Clean up any excess conductive adhesive. Place the plugged carbon anode plate into the heating device with the screw holes facing upwards. Set the appropriate temperature and time according to the type and properties of the conductive adhesive to cure it and complete the filling of the screw holes in the carbon anode plate.

[0025] 4) Cover the screw holes of the carbon anode plate with the contact area with the bolts (i.e., the exposed part that has been filled with cured conductive adhesive) with corrosion-resistant sealant until there are no gaps at the screw holes and the conductive adhesive is exposed.

[0026] 5) Clean off any excess sealant. Place the bolted carbon anode plate into the heating equipment with the screw holes facing upwards. Set the appropriate temperature and time according to the type and properties of the sealant to cure it and complete the sealing of the screw holes of the carbon anode plate.

[0027] Compared with existing technologies, the beneficial technical effects of the present invention are as follows:

[0028] This invention provides a method for filling and sealing the screw holes of a carbon anode plate used in medium-temperature electrolytic fluorine production. The method involves injecting room-temperature curing conductive adhesive between the screw holes and the screw rod of the carbon anode plate, followed by applying corrosion-resistant sealant to the screw opening. This successfully improves the special properties of the material surrounding the screw holes, reduces the polarization frequency of the carbon anode plate during operation, effectively prevents electrolyte from penetrating into the enlarged holes and corroding the screw rod, thereby significantly extending the service life of the carbon anode plate. Attached Figure Description

[0029] Figure 1 This is a comparison of the screw holes of a conventional carbon anode plate (top) and a carbon anode plate for medium-temperature electrolytic fluorine production (bottom) after filling and sealing.

[0030] Figure 2 This is a main sectional view of a carbon anode plate for medium-temperature electrolytic fluorine production after filling and sealing.

[0031] Figure 3 A side sectional view of a carbon anode plate for medium-temperature electrolytic fluorine production after filling and sealing.

[0032] Figure 4 A top view of a carbon anode plate for medium-temperature electrolytic fluorine production after filling and sealing.

[0033] Among them, 1 is the carbon anode plate, 2 is the copper bolt, 3 is the sealant, and 4 is the conductive adhesive. Detailed Implementation

[0034] The following specific embodiments are intended to further illustrate the present invention in conjunction with the accompanying drawings, and are not intended to limit the scope of protection of the claims.

[0035] Example 1

[0036] 1) Two screw holes are drilled at the center of the upper surface of the medium-temperature electrolytic fluorine production carbon anode plate. Based on the 20mm diameter of the copper bolts used, the hole diameter is enlarged to 21mm, the hole depth is 450mm, and the hole spacing is 120mm. The hole diameter is appropriately enlarged to 21mm to facilitate the wetting of the conductive adhesive, considering its flowability. After drilling the two screw holes, an enlarged hole is added at the top of the screw holes, with a depth of 40mm and a diameter of 30mm. This limits the overflow of the conductive adhesive while facilitating the placement and fixation of the sealant. See details... Figures 2-4 The enlarged hole at the bottom of the screw hole is mainly for filling the conductive adhesive (4), while the enlarged hole at the top of the screw hole is mainly for facilitating the placement and fixation of the sealant (3).

[0037] 2) Pour conductive adhesive (Double Key DB2014) into each drilled screw hole, about 15% of the total volume of the screw hole, and then immediately screw the copper bolt into the carbon anode plate at a uniform speed.

[0038] 3) Clean up any excess conductive adhesive, place the plugged carbon anode plate into the heating equipment with the screw holes facing upwards, and cure at 80°C for 3 hours to complete the filling of the screw holes in the carbon anode plate.

[0039] 4) Cover the contact area between the screw hole and the copper bolt on the carbon anode plate (i.e., the exposed part that has been filled with cured conductive adhesive) with corrosion-resistant sealant (Pinyiheng 7370) until there are no gaps at the screw hole and the conductive adhesive is exposed.

[0040] 5) Clean off any excess sealant. After curing at room temperature for 2 hours, place the bolted carbon anode plate into the heating equipment with the screw holes facing upwards. Maintain the curing temperature at 80°C for 2 hours. Remove the plate from the equipment and allow it to cool slowly and naturally to complete the sealing of the screw holes in the carbon anode plate.

[0041] The carbon anode plate of Example 1, which has undergone conductive adhesive filling and sealant sealing of the screw holes (see the actual product for details). Figure 1 The lower image shows an effective seal between the copper bolt and the screw hole, compared to a conventional carbon anode plate that has not been filled or sealed. Figure 1(As shown in the upper middle figure, there is a noticeable gap between the copper bolt and the screw hole) This method was applied to actual machine operation. Medium-temperature electrolysis for fluorine production was performed in two separate electrolytic cells at a current of 7000A, i.e., operating at 90℃ with an electrolyte ratio of KF:HF = 1:2. Conventional carbon anode plates experienced polarization on average after one month of operation, and an irreversible voltage drop occurred after three months. Upon shutdown, the carbon anode plates were observed to be broken. In contrast, the carbon anode plates that were filled and sealed only experienced an irreversible voltage drop after five months of operation, requiring shutdown, and only one polarization event occurred during this period. This demonstrates that the method of filling and sealing the screw holes of carbon anode plates for medium-temperature electrolysis for fluorine production, as described in this invention, can effectively reduce the number of polarization events during carbon anode plate operation, extend the service life of the carbon anode plates, and significantly reduce the cost of fluorine electrolysis.

Claims

1. A method for filling and sealing screw holes in a carbon anode plate used in medium-temperature electrolytic fluorine production, characterized in that: Includes the following steps: 1) A screw hole is made at the center of the formed carbon anode plate; the screw hole has a gradient diameter from the bottom to the top of the screw hole, wherein the diameter from the bottom of the screw hole to the depth of 30-40mm is 1-2mm larger than the diameter of the bolt, and the diameter from the depth of 30-40mm to the top of the screw hole is 10-12mm larger than the diameter of the bolt. 2) After filling the screw hole with conductive adhesive, immediately screw the bolt into the screw hole; the conductive adhesive includes at least one of Double Bond DB2014, Double Bond DB5018, Pinyiheng PH8011, and Pinyiheng PH8018; 3) After cleaning up any excess conductive adhesive that overflows from the bolt hole after screwing in the bolt, cure the conductive adhesive by heating. 4) Apply sealant to the contact area between the screw holes and bolts on the carbon anode plate until there are no gaps and the conductive adhesive is exposed; the sealant includes at least one of Pinyiheng 7370, Pinyiheng 7450 and Pinyiheng 7570; 5) After cleaning off any excess sealant, cure the sealant by heating. or, Includes the following steps: 1) A screw hole is made at the center of the formed carbon anode plate; the screw hole has a gradient diameter from the bottom to the top of the screw hole, wherein the diameter from the bottom of the screw hole to the depth of 30-40mm is 1-2mm larger than the diameter of the bolt, and the diameter from the depth of 30-40mm to the top of the screw hole is 10-12mm larger than the diameter of the bolt. 2) After filling the screw hole with conductive adhesive, immediately screw the bolt into the screw hole; the conductive adhesive includes at least one of Double Bond DB2014, Double Bond DB5018, Pinyiheng PH8011, and Pinyiheng PH8018; 3) After cleaning up the excess conductive adhesive that overflows from the bolt hole after screwing in the bolt, apply sealant to the contact area between the bolt hole and the bolt on the carbon anode plate until there are no gaps and the conductive adhesive is exposed; the sealant includes at least one of Pinyiheng 7370, Pinyiheng 7450 and Pinyiheng 7570; 4) After cleaning off any excess sealant, heat the conductive adhesive and sealant to cure them.

2. The method for filling and sealing screw holes in a carbon anode plate for medium-temperature electrolytic fluorine production according to claim 1, characterized in that: The conductive adhesive is a high-temperature resistant conductive adhesive that cures at room temperature or medium temperature.

3. The method for filling and sealing screw holes in a carbon anode plate for medium-temperature electrolytic fluorine production according to claim 1, characterized in that: The amount of conductive adhesive filling the screw hole is 10-20% of the screw hole volume.

4. The method for filling and sealing screw holes in a carbon anode plate for medium-temperature electrolytic fluorine production according to claim 1, characterized in that: The sealant is a medium-high temperature resistant and corrosion resistant sealant.

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