Method for mounting and constructing cathode of magnesium electrolytic cell

Abstract

The invention discloses a construction method for mounting a cathode of a magnesium electrolytic cell, which comprises the following steps of: mounting steel bars for temporarily supporting the cathode at the bottom of a cathode channel of the wall of the electrolytic cell in advance, and when the cathode is mounted, horizontally hoisting the cathode into the electrolytic cell, enabling the flexible aluminum tail end of the cathode to pass through a corresponding slot of the cathode channel, and supporting the neck of the cathode on the steel bars. After the position of the cathode is fixed, a steel plate used for temporarily fixing the cathode needs to be spot-welded to the cathode, and a clamp and a spacer block used when the cathode is installed are removed; and after inspection, correction and other work are completed, the steel bars used for temporarily supporting the cathode are dismantled. According to the invention, the cathode is temporarily supported by the pre-mounted steel bar, and after the steel bar is leveled on the electrolytic cell, the supporting plate is welded below the steel bar so as to assist in supporting the weight of the cathode during mounting, so that the mounting is convenient for subsequent dismounting, the overall construction progress is accelerated, and the construction safety quality is ensured in practical application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnesium electrolytic cell construction, in particular to a magnesium electrolytic cell cathode installation construction method. BACKGROUND

[0002] Electrolytic magnesium smelting is the most important method for producing metal magnesium, and the magnesium electrolytic cell is the core equipment of electrolytic magnesium smelting. A plurality of cathode assemblies are installed in the magnesium electrolytic cell, and the process is complex. Taking the 100,000-ton metal magnesium device project of Qinghai Salt Lake as an example, there are 68 426KA electrolytic cells designed, and cathode assemblies need to be installed in all 68 electrolytic cells. Each electrolytic cell needs to install 21 cathode assemblies. In the face of the situation of many cathode assemblies, complex process, high construction precision requirement, and tight construction period, it is urgent to improve the cathode installation method of the magnesium electrolytic cell. SUMMARY

[0003] The technical problem to be solved by the present application is to provide a magnesium electrolytic cell cathode installation construction method to improve construction efficiency and quality.

[0004] To solve the above technical problems, the technical scheme adopted by the present application is: a magnesium electrolytic cell cathode installation construction method, comprising: Step one, install the refractory material under the cathode; Step two, install a strip steel for temporarily supporting the cathode at the bottom of the cathode passage of the outer wall of the electrolytic cell, Step three, first install the center cathode, the center line of the center cathode coincides with the center line of the electrolytic cell, and after the position of the center cathode is determined, fill the space between the neck of the cathode, the back cathode and the brick with mortar; Step four, after the installation of the center cathode is completed, start installing the standard cathode, the right end cathode and the left end cathode. When installing, insert a spacer block between the cathodes to maintain an accurate distance between the cathodes; In steps three and four, after the cathode is hoisted horizontally into the electrolytic cell, the flexible aluminum end of the cathode passes through the corresponding slot of the cathode passage, and the neck of the cathode is supported on the strip steel; Step five, check and correct the distance between the front cathode and the rear cathode, and cover the gap between the back cathodes with a steel plate; Step six, spot weld the steel plate used as a temporary fixing cathode to the cathode, and remove the clamps and spacer blocks used during the installation of the cathode; Step seven, check and correct the gap between the cathode necks; install the outer formwork and completely fill the remaining joints between the cathode necks and the frame with rammed material. When the refractory material installation is completed, and when the electrolytic cell can receive the anode assembly, remove the strip steel used for temporarily supporting the cathode.

[0005] As a preferred embodiment, in step two, the strip steel is fixed on the additional plate of the electrolytic cell wall by bolts and nuts, and when the strip steel is leveled on the electrolytic cell, the support plate is welded under the strip steel.

[0006] As a preferred embodiment, in step two, the upper part of the strip steel is 1550±2mm away from the top of the electrolytic cell shell.

[0007] As a preferred embodiment, in step two, the top of the strip steel is 20mm above the neck of the cathode passage.

[0008] As a preferred embodiment, in steps three and four, when the cathode is installed, the neck of the cathode is placed behind the strip steel, and a gasket is added between the neck of the cathode and the strip steel to make the cathode in a horizontal position.

[0009] As a preferred embodiment, in step four, when the standard cathode is used, a plastic plate is laid between the standard cathode and the refractory cast transition at the bottom of the standard cathode.

[0010] As a preferred embodiment, in step five, for the center cathode and the standard cathodes on both sides of the center cathode, the distance between the front cathodes is 5.0mm, and the distance between the back cathodes is 5.5mm.

[0011] As a preferred embodiment, in step five, for the cathodes other than the center cathode, the distance between the front cathodes is 3.0mm, and the distance between the back cathodes is 3.5mm.

[0012] As a preferred embodiment, in step five, the steel plate used to cover the gap between the back cathodes is only welded on one of the cathodes.

[0013] As a preferred embodiment, in step seven, the distance between the neck of the cathode and the top of the neck ring at the slot of the cathode passage, the distance between the two sides, and the distance between the bottoms are F1, F2, and F3 respectively; if F1>15mm, F2>5mm, and F3>5mm, no action is needed; if 15≥F1≥13mm, F2≤5mm, and F3≤5mm, a 2mm thick compressed fiber material is installed; if F1<13mm, F2<3mm, and F3<3mm, the neck ring is cut off in whole or in part.

[0014] The present application temporarily supports the cathode by the pre-installed strip steel, the strip steel is fixed on the additional plate by bolts and nuts, and when the strip steel is leveled on the electrolytic cell, the support plate is welded under the strip steel, so as to assist in supporting the weight of the cathode during installation, which facilitates the subsequent removal of the installation, speeds up the overall construction progress, and ensures the construction safety quality in practical application. BRIEF DESCRIPTION OF DRAWINGS

[0015] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of the application and together with the description, serve to explain the application. It should be understood that various embodiments of the application can be practiced without many of the specific details set forth herein.

[0016] Figure 1 is a schematic view of the installation position of the cathode of the electrolytic cell described in the present application; Figure 2 is a schematic view of the structure of the cathode assembly in different forms; Figure 3 is a schematic view of the overall arrangement of the cathode assembly in the electrolytic cell; Figure 4 is a schematic view of the installation of the strip steel; Figure 5 is a sectional view of the installation of the strip steel; Figure 6 is a schematic view of the measurement position of the distance of the cathode; Figure 7 is a schematic view of the correction of the gap between the necks of the cathodes.

[0017] In the drawings, 1 is the shell of the electrolytic cell, 2 is the cathode, 3 is the anode, 4 is the refractory material, 5 is the cathode passage, 6 is the strip steel, 7 is the attached plate, 8 is the support plate, 9 is the front cathode, 10 is the back cathode, and 11 is the neck ring.

[0018] D1 is the central cathode, A1 and A2 are the standard cathodes, C1 is the left end cathode, and B2 is the right end cathode, DETAILED DESCRIPTION

[0019] In order to enable a person skilled in the art to better understand the present application, the present application will be further clearly and completely explained below in combination with the reference drawings and in combination with the embodiments. It should be noted that the features in the embodiments and the examples in the present application can be combined with each other without conflict.

[0020] A typical embodiment of the present application provides a construction method for the installation of the cathode of a magnesium electrolytic cell, which comprises the following steps one to seven.

[0021] Step one, install the refractory material 4 at the lower part of the cathode 2; Step two, install the strip steel 6 for temporarily supporting the cathode 3 at the bottom of the cathode passage 5 of the wall of the electrolytic cell, Step three, first install the central cathode D1, the center line of the central cathode D1 is consistent with the center line of the electrolytic cell, and after the position of the central cathode D1 is determined, fill the space between the cathode neck, the back cathode 10 and the brick with mortar; Step four, after the installation of the central cathode D1 is completed, install the standard cathodes (A1 and A2), the right end cathode B2 and the left end cathode C1, and during the installation, insert the partition block between the cathodes to keep the accurate distance between the cathodes; In steps three and four, after the cathode is hoisted horizontally into the cell, the flexible aluminum end of the cathode is passed through the corresponding slot in the cathode channel, and the cathode neck is supported on the strip steel; In step five, the distance between the front cathode 9 and the rear cathode is checked and corrected, and the gap between the back cathode 10 is covered with a steel plate; In step six, the steel plate used as a temporary fixing cathode is spot-welded to the cathode, and the fixture and spacer used during installation of the cathode are removed; In step seven, the gap between the cathode neck is checked and corrected, the outer formwork is installed and the remaining joint between the cathode neck and the frame is completely filled with rammed material. When the refractory material is installed and when the electrolytic cell can receive the anode assembly, the steel strip used for temporary support of the cathode is removed.

[0022] In order to enable those skilled in the art to better understand the present application, a relatively specific embodiment is provided below to further clearly and completely describe the technical solutions claimed by the present application.

[0023] The 426KA electrolytic cell involved in the present embodiment (as shown in Figure 1 , the total weight after masonry is nearly 380 tons. Among them, the electrolytic cell shell 1 is about 23 tons, the cell cover is about 3 tons, the cathode is about 53 tons, the anode is about 122 tons, and the refractory material is about 175 tons, a total of 68 electrolytic cells need to be installed.

[0024] The cathode assembly needs to be installed in all 68 electrolytic cells, and a plurality of different forms of cathode assemblies are involved in each electrolytic cell, as shown in Figure 2 , including 1 center cathode D1, 1 left end cathode C1, 1 right end cathode B2, 9 standard cathodes A1; 9 standard cathodes A2. The overall arrangement of the cathode assembly in the electrolytic cell is shown in Figure 3 .

[0025] Undercathode refractory installation Before the cathode is installed, the longitudinal wall size should be checked to ensure that the refractory material has been cured, and the longitudinal wall below the cathode is considered to be completed when the elevation is -1555mm, which is the cathode foundation. The longitudinal wall below the cathode should be set according to the following requirements: the first layer of longitudinal wall is composed of refractory bricks with an elevation of -1555mm. The second layer is composed of alumina refractory material with an elevation of -1555mm. Then 1 type of magnesia with an elevation of -1555mm is used to cast the wall with rammed material, which is compacted to the correct position using a vibrator, and finally it should be manually smoothed. Then lay an insulating layer, first lay a layer of spinel, then lay a layer of cast refractory material with an elevation of -1555mm.

[0026] During installation of standard cathode Al and standard cathode A2, a layer of 5 mm thick PVC plate should be laid on top of the fused brick. The 4th layer through the electrolysis chamber consists of spinel and fused cast refractory to an elevation of -1555 mm. The next section of wall consisting of fused cast refractory should be built to an elevation of -750 mm. Then the two cathode exit ends are installed.

[0027] Bar steel installation Before starting installation of cathodes on the cell, install strip steel for temporary support of the cathodes at the bottom of the cathode passage in the cell wall, with the top of the strip steel 6 about 20 mm above the neck of the cathode passage 5. Adjust the strip steel so that the upper part of the strip steel is 1550 ± 2 mm from the top of the cell shell 1. Check the flatness of the strip steel and the distance h of the strip steel from the cathode opening in the cell, with a minimum distance of 820 mm. If the value is low, then the strip steel needs to be adjusted. The two strip steels are fixed to the attachment plate 7 with bolts and nuts. When the strip steel is leveled on the cell, support plates 8 are welded under the strip steel to assist in supporting the weight of the cathodes during installation. Figure 5

[0028] Plastic sheet installation Corresponding to 18 standard electrodes, 18 plastic plates (660 x 100 x 5 mm) are needed for each cell, which are placed between the cathodes and the brickwork. The cathodes are placed on the plastic plates, with the central cathode Dl not on the plastic plate but directly on the central wall, and the end cathodes also not on the plastic plate but partly against the side wall. When a shim is needed, a steel plate is placed between the plastic plate and the cathode (steel plate dimensions: 660 x 100 x Y, where "Y" = 1, 2 or 4).

[0029] Cathode handling The cathodes must be lifted horizontally with equal length steel wires from the lifting eyes in the upper part of each cathode, and the cathodes are lifted into the cell with the flexible aluminium end through the slot in the cathode passage 5 in the cell wall. The flexible aluminium is hooked onto the cathode lifting eyes on the main DC busbar bundle and bolted.

[0030] Center cathode D1 installation ​Cathode installation in the cell First install the center cathode D1, which will be the reference for the distance measurements. The cathode is placed on the strip steel for temporary support and shims are added as needed to bring it to the horizontal position. When the center cathode D1 is in the correct position, the center line must coincide with the center line of the cell. The cathode must be perpendicular on both sides, and if it is not, the difference must be evenly distributed on both sides. When the cathode is installed, the back end must be raised about 30 mm, then a layer of aluminum mortar is added under the neck and back of the cathode, and then the cathode is returned to its final horizontal position. It is checked that the cathode neck is placed on the strip steel outside the shell, and that the entire space between the cathode neck, the back cathode 10 and the brickwork is filled with mortar.

[0031] Standard cathode installation Before installing the standard cathodes A1, A2 and the end cathodes (left end cathode C1, right end cathode B2), the distance between the cathodes must be measured, and the measurement points on the cathodes are marked according to the figure below. After the center cathode D1 is installed, one of the two cathodes closest to the center cathode D1 is installed first. When installing, the appropriate spacers (2 per space) are inserted between the cathodes in order to maintain the correct distance between the cathodes. During installation, clamps are used to secure the cathodes in their position. When tightening the clamps on the cathodes, a piece of wood is used to protect the cathode surface from damage.

[0032] Outside the cell shell 1, the flexible aluminum end of the cathode 2 is passed through the corresponding slot in the cathode channel, and the cathode neck is supported on the strip steel 6.

[0033] Check front and back cathode distance When all the cathodes are installed and secured, the distance between the front cathodes 9 and the back cathodes 10 is checked (see figure Figure 6 ). For cathodes other than the center cathode D1, the distance a between the front cathodes 9 and the distance b between the back cathodes 10 must be at least 3.0 mm. Smaller spacings usually require cutting (oxygen) or sanding. After the necessary cutting or sanding has been done, the distance between the front cathodes 9 and the back cathodes 10 is measured, and shims can be used to adjust this distance, with an average of 3.0 mm between the front cathodes 9 and 3.5 mm between the back cathodes 10.

[0034] For the center cathode D1 and the standard cathodes on both sides, the distance between the front cathodes 9 is 5.0 mm and the distance between the back cathodes 10 is 5.5 mm.

[0035] The inspection results must show that no two consecutive distances between the cathodes in each group are less than 3.0 mm. The minimum distance after the gasket is 2.7 mm. The gasket dimensions are dx40x830 mm, where "d" is 0.61, 1.21, 1.52, 1.9, 3.7, 6.35 and 9.53 mm. The gaskets are fixed with welds on the cathode side.

[0036] Correct cathode neck gap At cold state, the gap tolerance of the cathode neck is as shown in Figure 7 The distance between the cathode neck and the top of the neck ring 11 at the slot of the cathode channel 5, the distance between the two sides and the distance between the bottom are Fl, F2 and F3 respectively; if Fl > 15 mm, F2 > 5 mm, F3 > 5 mm, no action is needed; if 15 > Fl > 13 mm, F2 < 5 mm, F3 < 5 mm, a 2 mm thick compressed fiber material is installed; if Fl < 13 mm, F2 < 3 mm, F3 < 3 mm, the neck ring is cut off in whole or in part.

[0037] If the compressed fiber material needs to be installed, the required size of the material is: Fl is 80x80xmm; F2 is 805x80x2 mm; F3 is 80x80x2 mm; the material type needs to have the best electrical insulation performance and can withstand a temperature of 500°C or higher.

[0038] Back cathode 10 gap coverage The gap between the back cathodes 10 is covered with a steel plate at the back (close to the brickwork), which can only be welded to one side, i.e. only to one of the two cathodes. The upper part of the steel plate needs to be 100 mm lower than the top of the back cathodes 10.

[0039] Cathode neck seal and bar steel removal When all the cathodes are installed and adjusted, steel plates with a size of 8x50x100 mm are welded to the cathodes, one in front of and one at the back of each two cathodes, for fixing the position of the adjusted cathodes. The hole in the center cathode D1 cannot be covered by the steel plate. The clamps and spacers are moved to the next electrolytic cell.

[0040] When the cathodes are installed, the installation of the refractory material can continue. At this time, the accuracy of the cathode positioning and location is checked. The steel plates must be welded to the top end of the cathode body, so that they do not move when tamping. Before tamping starts, the position of the steel plates and the ceramic fiber blanket must be checked. Tamping must be dry and water cannot be used. During tamping, it must be careful and accurate. Excess tamping material is scraped off from the top of each chamber.

[0041] The cathode necks are externally sealed by installing an external shell and completely filling the remaining 3 joints between the neck and frame with rammed mass. The strips of steel are removed after the refractory has been installed and after the cell can receive the anode assembly.

[0042] The scope of the protection sought and protected by this patent is not limited to the specific embodiments described herein, but is instead defined by the appended claims; the patent seeks and obtains protection only for those claims. The patent seeks and obtains protection for any other alternative(s) falling within the spirit and scope of the patent as will be apparent to those skilled in the art.

Claims

1. A method of installing a magnesium cell cathode, characterized by, The method comprises the following steps: Step 1: installing refractory material under the cathode; Step 2: installing steel bars for temporarily supporting the cathode at the bottom of the cathode passage of the cell wall; Step 3: firstly installing the center cathode, the center line of which is consistent with the center line of the cell, and filling the space between the neck of the center cathode, the back cathode and the brickwork with mortar after the position of the center cathode is determined; Step 4: after the installation of the center cathode, installing the standard cathode, the right end cathode and the left end cathode, and inserting the spacer between the cathodes to keep the accurate distance between the cathodes during the installation; In step 3 and step 4, after the cathode is hoisted horizontally into the cell, the flexible aluminum end of the cathode is inserted through the corresponding slot of the cathode passage, and the neck of the cathode is supported on the steel bar; Step 5: checking and correcting the distance between the front cathode and the back cathode, and covering the gap between the back cathodes with the steel bar; Step 6: spot welding the steel plate used for temporarily fixing the cathode to the cathode, and removing the clamp and the spacer used during the installation of the cathode; Step 7: checking and correcting the gap between the necks of the cathodes, installing the outer formwork and completely filling the remaining joint between the necks of the cathodes and the frame with rammed material, and removing the steel bar used for temporarily supporting the cathode after the refractory material is installed and the cell can receive the anode assembly.

2. The method of claim 1, wherein: In step 2, the steel bar is fixed to the attachment plate of the cell wall by bolts and nuts, and the support plate is welded below the steel bar after the steel bar is leveled on the cell.

3. The method according to claim 1 or 2, characterized in that: In step 2, the distance between the upper part of the steel bar and the top of the cell shell is 1550±2mm.

4. The method of claim 3, wherein: In step 2, the top of the steel bar is 20mm above the neck of the cathode passage.

5. The method of claim 4, wherein: In step 3 and step 4, during the installation of the cathode, a gasket is added between the neck of the cathode and the steel bar after the neck of the cathode is placed on the steel bar, so that the cathode is in a horizontal position.

6. The method of claim 1 or 5, wherein: In step 4, a plastic plate is laid between the standard cathode and the refractory material cast transition at the bottom of the standard cathode.

7. The method of claim 6, wherein: In step 5, for the center cathode and the standard cathodes on both sides of the center cathode, the distance between the front cathodes is 5.0mm, and the distance between the back cathodes is 5.5mm.

8. The method of claim 7, wherein: In step 5, for the cathodes other than the center cathode, the distance between the front cathodes is 3.0mm, and the distance between the back cathodes is 3.5mm.

9. The method of claim 8, wherein: In step 5, the steel plate used for covering the gap between the back cathodes is welded only on one of the cathodes.

10. The method of claim 1 or 9, wherein: In step 7, the distance between the neck of the cathode and the top of the neck ring at the slot of the cathode passage, the distance between the two sides and the distance between the bottoms are F1, F2 and F3 respectively; if F1>15mm, F2>5mm, F3>5mm, no action is needed; if 15≥F1≥13mm, F2≤5mm, F3≤5mm, a 2mm thick compressed fiber material is installed; If F1<13mm, F2<3mm, F3<3mm, all or part of the neck ring is cut off.

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