CN114921815A - Method for replacing magnesium electrolytic cell anode without stopping cell - Google Patents

Abstract

The invention belongs to the technical field of metallurgy, and particularly relates to a method for replacing an anode of a magnesium electrolytic cell without stopping the cell. The method comprises the following steps: before replacing the anode, pretreating a new anode and the electrolytic cell; and B, step B: d, disconnecting direct current and replacing the anode; step C: detecting the voltage drop of the anode; the purpose is as follows: the service life of the electrolytic cell is prolonged, the current efficiency is improved, and the production cost of magnesium electrolysis is reduced.

Description

A kind of method for changing the anode of magnesium electrolytic cell without stopping

technical field

The invention belongs to the technical field of metallurgy, and in particular relates to a method for replacing the anode of a magnesium electrolytic cell without a bath.

Background technique

Magnesium electrolysis is an important method for preparing magnesium metal. The multi-pole magnesium electrolysis technology is used by more and more enterprises as a supporting process in the production of sponge titanium. Saving energy and reducing consumption, prolonging the service life of the tank, and improving the production capacity of a single tank have always been issues that enterprises need to solve urgently. The life cycle of electrolytic cell anodes is generally 24 months, but in actual production, the average life of graphite anodes is only 18 months.

The graphite anode is prone to breakage and fracture under the action of high-temperature electrolysis (the breaking position is near the molten salt level). When the graphite anode is gradually thinned or broken due to breakage, the voltage will rise, the temperature will rise, and the current efficiency will drop. Because the material and environment of a group of graphite anodes in the same electrolytic cell are not exactly the same, and the speed of breakage and fracture is not completely the same, once 1-2 of the anodes break or lose their electrolytic effect, the cell has to be stopped for rest.

SUMMARY OF THE INVENTION

In order to solve the problems of aging, damage and fracture of the anode in the above-mentioned multi-pole magnesium electrolytic cell structure, the present invention provides a method for replacing the anode of the magnesium electrolytic cell without changing the cell. Helps reduce the production cost of magnesium electrolysis.

The technical scheme adopted in the present invention is as follows:

Step A: Before replacing the anode, pre-treat the new anode and the electrolytic cell; Step B: Switch off the direct current to replace the anode; Step C: Check the voltage drop of the anode.

Further, the step A specifically includes:

1) More than three days in advance, the ceramic rods on the anode are bonded, and after the ceramic rods are bonded, the anodes are baked;

2) Install DC cut-off devices at the anode aluminum busbar and cathode aluminum busbar more than 4 hours in advance;

3) Warm up the electrolytic cell to 690-720°C in advance;

4) The height of the liquid magnesium in the electrolytic cell is reduced by means of extraction, and the height of the liquid magnesium after extraction is 0-40mm.

Wherein, in the process of extracting the liquid magnesium in the solution tank, a magnesium scraping rake is used to scrape the liquid magnesium to the magnesium extraction port as much as possible, and magnesium chloride is not supplemented after the liquid magnesium is extracted.

Further, the step B specifically includes:

1) Separately cut off the direct current to the electrolytic cell where the anode needs to be replaced by the direct current cut-off device;

2) Disconnect the soft connection between the damaged anodes of the electrolytic cell;

3) Lift out the broken anode of the upper part of the electrolytic cell from the electrolytic cell through the overhead crane;

4) The operator wears protective equipment to remove the adhesive on the side wall of the electrolysis chamber at the anode;

5) Lower the electrolyte level to about 200mm below the anode fracture surface;

6) Use a crowbar to separate the two broken anodes immersed in the electrolyte, fasten the broken anodes close to the partition wall with a steel sleeve, and use a crane to lift the anodes out of the electrolytic cell;

7) After the broken anode is lifted out of the electrolytic cell, the operator uses the slag scraper and the slag grab box to clean up the slag on the top of the cathode bed that has been lifted out of the anode;

8) After cleaning the slag, use a crane to hoist a complete anode to be installed to the anode port that has been cleaned, slowly install the anode into the anode installation place, and drop the anode to the cover of the electrolysis chamber to expose 1 When /3, use the anode clamp to fix the anode on the electrolysis chamber cover, and tighten the bolts on the anode clamp to prevent the anode from sliding down;

9) Repeat the steps described in claims 6 and 7 to lift out another anode of the broken anode, and clean up the slag;

10) Preliminarily pair the silver-plated copper foil, cooling water jacket, iron splint and another complete anode to be installed;

11) Repeat the steps described in claim 8, hoist the assembled anodes to the anode installation port that has been cleaned up, and slowly descend, when the two anodes will overlap the descending height positions, merge the two anodes and install them. Bolt and tighten;

12) Loosen the anode clamp, install the tightened anode to the predetermined position, check the installation size, and seal the anode after confirming that the size is correct;

13) Use the anode soft connection to connect the anode of the electrolytic cell to the anode aluminum busbar to complete the replacement of the new anode.

To sum up, due to the adoption of the above-mentioned technical solutions, the beneficial effects of the present invention are:

After the anode of the electrolytic cell is broken, different from the solution of stopping the tank for reconditioning adopted in the prior art, this technical solution can restore the normal operation of the anode in a short period of time without the reconditioning of the electrolytic cell by replacing the anode on-line, preventing the electrolytic cell from resting. The continuous hot cell balances the electrode potential of the electrolytic cell, restores the normal circulation of electrolyte, magnesium and chlorine gas during electrolysis, and solves the problem of electrode potential balance, thermal balance, electrolyte, magnesium, and chlorine gas after the anode of the electrolytic cell is broken. Efficiency continues to decrease, leading to the problem of the final dead cell of the electrolytic cell. After the implementation of this technical solution, the electrolytic cell can be restored to the normal operating state from the state of the dying cell, prolong the service life of the electrolytic cell, improve the current efficiency, and reduce the production cost of magnesium electrolysis.

Description of drawings

FIG. 1 is a flow chart of a method for continuously replacing the anode of a magnesium electrolytic cell provided by the present invention.

FIG. 2 is a histogram of cumulative current efficiency around the electrolytic cell after the method is adopted in Example 2 of the present invention.

Detailed ways

In order to make the purposes, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only It is a part of the embodiments of the present application, but not all of the embodiments. The components of the embodiments of the present application generally described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations. Thus, the following detailed description of the embodiments of the application provided in the accompanying drawings is not intended to limit the scope of the application as claimed, but is merely representative of selected embodiments of the application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

In the description of the embodiments of the present application, it should be noted that the terms "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. The orientation or positional relationship is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship that the product of the invention is usually placed in use, only for the convenience of describing the application and simplifying the description, rather than indicating or implying that The device or element must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as a limitation of the present application. Furthermore, the terms "first", "second", "third", etc. are only used to differentiate the description and should not be construed as indicating or implying relative importance.

The invention provides a method for replacing the anode of a magnesium electrolytic cell without a bath. When the anode of the magnesium electrolytic cell is damaged or broken, the anode can be replaced without a break in the cell, so as to prolong the life of the electrolytic cell and improve the current efficiency. It helps to reduce the production cost of magnesium electrolysis, and has strong due prospects.

The present invention will be described in detail below in conjunction with FIG. 1 .

Example 1:

A method for continuously replacing the anode of a magnesium electrolytic cell, comprising the following steps:

Step 1: The ceramic rods on the anode were bonded three days in advance.

Step 2: After the ceramic rod is bonded, bake the anode.

Step 3: Before anode replacement, install DC cut-off devices at the anode aluminum busbar and cathode aluminum busbar 4 hours in advance, and wait for the command after the installation is complete.

Step 4: The temperature of the electrolytic cell is increased 4 hours in advance, and the temperature of the electrolytic cell reaches 690-720°C.

Step 5: The liquid magnesium in the electrolytic cell is removed by extraction, and the magnesium scraping rake is used to scrape the liquid magnesium to the magnesium extraction port as much as possible during the extraction process, and magnesium chloride is not supplemented after the liquid magnesium is extracted.

Step 6: After the magnesium extraction operation is completed, remove the sealing material around the damaged anode of the electrolytic cell.

Step 7: Use the direct current cut-off device to cut off the direct current flowing into the electrolytic cell where the anode needs to be replaced.

Step 8: The electrolytic cell is damaged anode The anode is disconnected from the anode soft connection.

Step 9: Lift the broken anode of the upper part of the electrolytic cell out of the electrolytic cell through the overhead crane.

Step 10: The operator wears protective equipment to remove the adhesive on the side wall of the electrolysis chamber at the anode. The protective clothing is characterized by high temperature resistance and insulation.

Step 11: Lower the electrolyte level to about 200mm below the fracture surface of the anode.

Step 12: Use a crowbar to separate the two broken anodes immersed in the electrolyte, secure the broken anode near the partition wall with a steel sleeve, and use a crane to lift the anode out of the electrolytic cell.

Step 13: After the broken anode is lifted out of the electrolytic cell, the operator uses the slag scraper and the slag box to clean up the slag on the upper part of the cathode bed at the anode.

Step 14: After cleaning the slag, use a crane to hoist a complete anode that has been dried and installed to the cleaned anode port, and slowly install the anode into the anode installation place (pay attention to electrolyte splashing), the anode When 1/3 is exposed on the electrolysis chamber cover, use the anode clamp to fix the anode on the electrolysis chamber cover, and tighten the bolts on the anode clamp to prevent the anode from sliding down.

Step 15: Repeat the steps described in steps 11 and 12 to lift out the other broken anode, and clean the slag.

Step 16: Preliminarily pair the silver-plated copper foil, cooling water jacket, iron splint and another complete anode to be installed (the anode bolts do not need to be tightened).

Step 17: Repeat the steps described in Step 13, hoist the assembled anode to the cleaned anode installation port, and slowly lower it (pay attention to electrolyte splashing). When the two anodes overlap the lowering height, use Use tools such as a crowbar to combine the 2 anodes, install the bolts and tighten.

Step 18: Loosen the anode clamp, install the tightened anode to the predetermined position, check the installation size, and seal the anode after confirming that the size is correct.

Step 19: Use the anode soft connection to connect the anode of the electrolytic cell to the anode aluminum busbar.

Step 20: Detect the anode voltage drop.

In this example: the company's multi-polar magnesium electrolytic cell is used, 1 of the 6 groups of anodes is intact, and one anode of each of the remaining 5 groups is broken, the tank is seriously hot, the temperature is kept above 690 ℃, the voltage is 11.2V, and the current efficiency is 29.48% , using the method of the electrolytic cell anode provided by the present invention, after replacing a group of anodes in the electrolytic cell, the hot cell phenomenon disappears, the temperature is maintained at 660 ℃ ~ 670 ℃, the voltage is 10.2V, and after the anode replacement technical scheme is completed, 8 continuous operation month, the cumulative current efficiency reached 50.01%.

Embodiment 2:

Step 1: Before anode replacement, install DC cut-off devices at the anode aluminum busbar and cathode aluminum busbar 4 hours in advance, and wait for the command after the installation is complete.

Step 2: The temperature of the electrolytic cell was increased 2 hours in advance, and the temperature of the electrolytic cell reached 680°C.

Step 3: Remove the liquid magnesium in the electrolytic cell by extraction, and use a magnesium scraping rake to scrape the liquid magnesium to the magnesium extraction port as much as possible during the extraction process.

Step 4: After the liquid magnesium is extracted, magnesium chloride is added to increase the pressure of the submerged tank, and the electrolyte level is adjusted so that it rises to 50mm above the "zero point" of the electrolytic cell.

Step 5: Use the direct current cut-off device to cut off the direct current flowing into the electrolytic cell where the anode needs to be replaced.

Step 6: Damaged Anode Electrolyzer The anode is disconnected from the anode soft connection and removed.

Step 7: Turn off the DC cut-off device, restore the DC power, and run the production trial.

Step 8: Detect the voltage drop and current distribution of the remaining anodes.

Step 9: When the current efficiency of the current cell continues to decrease, the anode is replaced.

Step 10: The ceramic rods on the anode were bonded 5 days in advance.

Step 11: After the ceramic rods are bonded, they are baked on a refining furnace or electrolytic cell for 5 days.

Step 12: The temperature of the electrolytic cell is increased 4 hours in advance, and the temperature of the electrolytic cell reaches 690-720°C.

Step 13: remove the liquid magnesium in the electrolytic cell by means of extraction, use a magnesium scraping rake to scrape the liquid magnesium to the magnesium extraction port as much as possible during the extraction process, and do not replenish magnesium chloride after the liquid magnesium is extracted.

Step 14: After the magnesium extraction operation is completed, remove the sealing material around the damaged anode of the electrolytic cell.

Step 15: Use the direct current cut-off device to cut off the direct current flowing into the electrolytic cell where the anode needs to be replaced.

Step 16: Lift the broken anode of the upper part of the electrolytic cell out of the electrolytic cell through the overhead crane.

Step 17: The operator wears protective equipment to remove the adhesive on the side wall of the electrolysis chamber at the anode. The protective clothing is characterized by high temperature resistance and insulation.

Step 18: Lower the electrolyte level to about 200mm below the fracture surface of the anode.

Step 19: Use a crowbar to separate the two broken anodes immersed in the electrolyte, secure the broken anode near the partition wall with a steel sleeve, and use a crane to lift the anode out of the electrolytic cell.

Step 20: After the broken anode is lifted out of the electrolytic cell, the operator uses the slag scraper and the slag grab box to clean up the slag on the upper part of the cathode bed where the anode has been lifted out.

Step 21: After cleaning the slag, use the crane to hoist a complete anode that has been dried and installed to the cleaned anode port, and slowly install the anode into the anode installation place (pay attention to electrolyte splashing), the anode When 1/3 is exposed on the electrolysis chamber cover, use the anode clamp to fix the anode on the electrolysis chamber cover, and tighten the bolts on the anode clamp to prevent the anode from sliding down.

Step 22: Repeat the steps described in Steps 11 and 12 to lift out the other broken anode, and clean the slag.

Step 23: Preliminarily pair the silver-plated copper foil, cooling water jacket, iron splint and another complete anode to be installed (the anode bolts do not need to be tightened).

Step 24: Repeat the steps described in Step 13, hoist the assembled anode to the anode installation port that has been cleaned, and lower it slowly (pay attention to the splash of electrolyte). Use tools such as a crowbar to combine the 2 anodes, install the bolts and tighten.

Step 25: Loosen the anode clamp, install the tightened anode to the predetermined position, check the installation size, and seal the anode after confirming that the size is correct.

Step 26: Use the anode soft connection to connect the anode of the electrolytic cell to the anode aluminum busbar.

Step 27: Detect the anode voltage drop.

Step 28: Electrolyte replacement.

In this example: the multi-polar magnesium electrolytic cell of our company is selected. The operating time of this electrolytic cell is 15 months, 4 groups of 6 groups of anodes are in good condition, and the remaining 2 groups are broken, and the temperature is kept above 690 ℃. The voltage is 12.1V, and the current efficiency is 45.45%. Referring to Figure 2, using the method of the electrolytic cell anode provided by the present invention, after the two groups of anodes of the electrolytic cell are replaced, the hot cell phenomenon disappears, the temperature is maintained at 660 ° C ~ 670 ° C, and the voltage is 10.9V , After the anode replacement technical scheme is completed, it continues to run for 5 weeks, and the cumulative current efficiency is increased from 45.45% to 69.84%.

The above-mentioned embodiments only represent specific implementations of the present application, and the descriptions thereof are relatively specific and detailed, but should not be construed as limiting the protection scope of the present application. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the technical solution of the present application, several modifications and improvements can be made, which all belong to the protection scope of the present application.

Claims (4)

1. A method for replacing the anode of a magnesium electrolytic cell without stopping the cell is characterized by comprising the following steps:

step A: before replacing the anode, pretreating a new anode and the electrolytic cell; and B, step B: d, disconnecting direct current and replacing the anode; step C: and detecting the voltage drop of the anode.

2. The method for replacing the anode of the magnesium electrolytic cell without stopping the cell as claimed in claim 1, wherein the step A comprises:

1) more than three days in advance, completing the bonding of the ceramic rods on the anodes, and baking the anodes after the bonding of the ceramic rods is completed;

2) more than 4 hours ahead of schedule, installing direct current cut-off devices at the anode aluminum bus and the cathode aluminum bus;

3) raising the temperature of the electrolytic cell to 690-720 ℃ in advance;

4) the height of the liquid magnesium in the electrolytic cell is reduced by an extraction mode, and the height of the extracted liquid magnesium is 0-40 mm.

3. The method for replacing the anode of the magnesium electrolytic cell without stopping the cell as claimed in claim 2, wherein the magnesium scraping rake is adopted to scrape the liquid magnesium to the magnesium-extracting port as much as possible during the extraction of the liquid magnesium in the electrolytic cell, and the magnesium chloride is not supplemented after the liquid magnesium is extracted.

4. The method for replacing the anode of the magnesium electrolytic cell without stopping the cell as claimed in claim 2, wherein the step B specifically comprises:

1) the direct current which is led into the electrolytic tank with the anode needing to be replaced is cut off by a direct current cut-off device;

2) disconnecting the flexible connection between the damaged anodes of the electrolytic cell;

3) hoisting the anode of the upper broken part of the electrolytic bath out of the electrolytic bath by a crown block;

4) an operator wears a protective tool to clean the adhesive on the side wall of the electrolytic chamber at the anode;

5) lowering the electrolyte level to about 200mm below the anode fracture surface;

6) 2 broken anodes soaked in the electrolyte are separated by a crowbar, the broken anodes close to the side of the partition wall are firmly sleeved by a steel bar sleeve, and the anodes are lifted out of the electrolytic cell by an overhead crane;

7) after a broken anode is lifted out of the electrolytic bath, an operator cleans up slag blocks lifted out of the upper part of the anode and the cathode bed by using a slag grabbing raking box;

8) cleaning the slag blocks, hoisting a whole anode to be installed after drying to the cleaned anode opening by using a crane, slowly loading the anode into the anode installation position, fixing the anode on the electrolytic chamber cover by using an anode clamp when the anode descends to the electrolytic chamber cover to expose 1/3, and screwing a bolt on the anode clamp to prevent the anode from sliding downwards;

9) repeating the steps of claims 6 and 7 to lift out another anode with the broken anode and clean the slag;

10) preliminarily assembling the silver-plated copper foil, the cooling water jacket, the iron clamping plate and the other integral anode to be installed;

11) repeating the steps described in claim 8, hoisting the assembled anodes to the cleaned anode mounting openings, slowly descending, combining the 2 anodes when the descending height positions of the 2 anodes coincide, mounting bolts and fastening;

12) loosening the anode clamp, installing the fastened anode to a preset position, checking the installation size, and sealing the anode after confirming that the size is correct;

13) and connecting the anode of the electrolytic cell with an anode aluminum bus by using anode flexible connection to finish the replacement of a new anode.

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