Low-expansion segmented conductive energy-saving cathode carbon block group structure

Abstract

The invention relates to a low-expansion segmented conductive energy-saving cathode carbon block group structure which comprises a cathode carbon block, a dovetail groove is formed in the bottom surface of the cathode carbon block, a conductive material is laid in the dovetail groove after the cathode carbon block is inverted, then a cathode steel bar is placed in the dovetail groove, and middle paste is fixedly bound on the outer side of the inner end face of the cathode steel bar. Edge paste is bound and fixed between the inner side of the outer end face of the cathode carbon block and the two sides of the cathode steel bar, high-conductivity materials are arranged on the two sides of the cathode steel bar between the middle paste and the edge paste, and the conductivity of the edge paste is smaller than that of the high-conductivity materials. Compared with the prior art, the method has the advantages and effects that the effect of reducing the cathode voltage drop is achieved, meanwhile, the use amount of the phosphorus pig iron with the high expansion rate is greatly reduced, the fracture risk of a cathode carbon block caused by overlarge thermal shock and thermal expansion stress is effectively reduced, horizontal current in molten aluminum is greatly reduced, side horizontal current is effectively restrained, and the service life of the cathode carbon block is prolonged. The magnetic fluid stability of the electrolytic bath is improved. The method has the advantages of simple structure, convenience in construction and low cost.

Description

Technical Field

[0001] The present invention relates to a cathode carbon block group structure, and in particular to a low-expansion segmented conductive energy-saving cathode carbon block group structure used in the aluminum electrolysis industry to reduce the cathode voltage drop of an electrolytic cell and solve the problem of easy breakage of cathode carbon blocks. Background Art

[0002] There are two types of cathode carbon block structures in the aluminum electrolysis industry. Figure 1-3 As shown, the first method places the cathode steel rod 2 in a dovetail groove 3 on the bottom surface of the cathode carbon block 1, with the middle paste 4 and the side paste 5 fixed to the cathode steel rod 2. The second method places the cathode steel rod 2 in a dovetail groove 3 on the bottom surface of the cathode carbon block 1, with the middle paste 4 fixed to the outside of the inner end surface of the cathode steel rod 2, while the remaining portion is cast with phosphorus pig iron 6. This method requires a large amount of phosphorus pig iron and an insulating layer 7 on the outside of the phosphorus pig iron 6. Only one conductive material is provided between the top of the cathode steel rod 2 and the cathode carbon block 1. Therefore, although the cathode carbon block cast phosphorus pig iron assembly method can reduce the cathode voltage drop of the electrolytic cell by 40-60mV compared to the traditional paste assembly method, phosphorus pig iron is harder than the paste and has a higher linear expansion coefficient. The phosphorus pig iron casting method places high demands on the casting process and cathode carbon block heating equipment. The cathode carbon blocks are subject to significant thermal shock stress during the casting process, which can easily cause cracks. Furthermore, during electrolytic cell operation, the cast cathode carbon blocks also present a significant risk of fracture due to thermal expansion of the lining and uneven sodium penetration. While phosphorus pig iron casting significantly reduces cathode voltage drop, it also significantly increases the risk to safe electrolytic cell operation.

[0003] The electrical conductivity of phosphorus pig iron is better than that of ordinary steel bar paste, which can significantly reduce the cathode voltage drop. However, the low voltage drop will inevitably lead to current concentration in the large surfaces of the aluminum liquid on both sides of the electrolytic cell, thereby increasing the horizontal current in the aluminum liquid and worsening the magnetic fluid stability of the electrolytic cell. In turn, this will weaken the effect of the phosphorus pig iron casting cathode in reducing the cell voltage to a certain extent. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a low-expansion segmented conductive energy-saving cathode carbon block group structure, the purpose of which is to adopt a segmented assembly and conductive method in the assembly of the cathode carbon block and the cathode steel rod, reduce or eliminate the casting of phosphorus pig iron, effectively reduce the risk of fracture of the cathode carbon block due to thermal shock and excessive thermal expansion stress, and greatly reduce the horizontal current in the aluminum liquid, thereby improving the magnetic fluid stability of the electrolytic cell.

[0005] In order to achieve the object of the present invention, the technical solution of the present invention is: A low-expansion segmented conductive energy-saving cathode carbon block group structure includes a cathode carbon block, a dovetail groove is opened on the bottom surface of the cathode carbon block 1, the cathode carbon block is inverted and 2-3 conductive materials are laid in the dovetail groove, and then a cathode steel rod is placed in the dovetail groove, the middle paste is fastened to the outside of the inner end surface of the cathode steel rod, the side paste is fastened between the inner side of the outer end surface of the cathode carbon block and the two sides of the cathode steel rod, and the two sides of the cathode steel rod between the middle paste and the side paste are filled with 1-2 high-conductivity materials, and the conductivity of the edge paste is lower than that of the high-conductivity material.

[0006] The high conductivity material is phosphorus pig iron and / or paste.

[0007] The phosphorus pig iron is cast on both sides between the cathode carbon block and the cathode steel rod, and the paste is fixed on both sides between the cathode steel rod 2 and the cathode carbon block.

[0008] The length of the edge paste extending toward the middle paste is 100-1000mm.

[0009] The cathode steel bar is provided with a vertical slit running through the width from the top downward, with a slit width of 5-20 mm and a depth of 10-200 mm. The vertical slit is filled with electrical insulating material or common conductive paste.

[0010] The vertical seam is 80-995 mm away from the end face of the cathode carbon block.

[0011] The vertical seam is arranged on the cathode steel rod with edge paste.

[0012] The position of the vertical seam on the cathode steel rod is flush with the inner end surface of the edge paste.

[0013] The outer end surface of the edge paste is flush with the outer end surface of the cathode carbon block.

[0014] The conductive material laid is a solidifying paste at the power output end, and the other parts are made of solidifying paste and / or cast phosphorus pig iron.

[0015] Advantages and effects of the present invention: Compared with the prior art, the present invention eliminates the insulating material layer 7 at the edge of the cathode carbon block assembly and uses an edge paste 5 with lower conductivity than high-conductivity materials. Furthermore, the edge paste 5 is much longer than the insulating material layer 7. This significantly reduces the amount of phosphorus pig iron used while also reducing cathode voltage drop. This effectively reduces the risk of fracture of the cathode carbon block due to thermal shock and excessive thermal expansion stress, significantly reduces horizontal current in the aluminum liquid, effectively suppresses horizontal current at the edge, and improves the stability of the electrolytic cell's magnetic fluid. The present invention offers the advantages of a simple structure, easy construction, and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is the main view of the cathode carbon block assembly using the traditional paste assembly method.

[0017] Figure 2 for Figure 1 side view.

[0018] Figure 3 This is the front view of the cathode carbon block assembly using the traditional phosphorus pig iron casting assembly method.

[0019] Figure 4 This is a front view of embodiment 1 of the present invention.

[0020] Figure 5 This is a front view of embodiment 2 of the present invention.

[0021] Figure 6 This is a front view of embodiment 3 of the present invention.

[0022] Figure 7 This is a front view of embodiment 4 of the present invention.

[0023] In the figure: 1. Cathode carbon block; 2. Cathode steel rod; 3. Dovetail groove; 4. Middle paste; 5. Edge paste; 6. Phosphorus pig iron; 7. Insulation layer; 8. Paste; 9. Vertical seam. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to the examples. The following examples are only a few specific embodiments of the present invention, but the design concept of the present invention is not limited thereto, and any non-substantial improvements to the present invention made using this concept should fall within the scope of protection of the present invention.

[0025] Example 1

[0026] like Figure 4 As shown, the present invention provides a low-expansion segmented conductive energy-saving cathode carbon block assembly structure, comprising a cathode carbon block 1, a dovetail groove 3 provided on the bottom surface of the cathode carbon block 1, and two types of conductive materials laid in the dovetail groove 3 after the cathode carbon block 1 is inverted. The laid conductive materials are made of a fixed paste at the power output end, and cast phosphorus pig iron in other parts. The cathode steel bar 2 is then placed in the dovetail groove 3, and the middle paste 4 is fixed to the outside of the inner end face of the cathode steel bar 2. The edge paste 5 is fixed between the inner side of the outer end face of the cathode carbon block 1 and the two sides of the cathode steel bar 2. Phosphorus pig iron 6 is cast on both sides of the cathode steel bar 2 between the middle paste 4 and the edge paste 5. The conductivity of the edge paste 5 is less than that of the phosphorus pig iron 6. The edge paste 5 extends 500 mm in the direction of the middle paste 4. The outer end face of the edge paste 5 is flush with the end face of the cathode carbon block 1. Compared with the traditional phosphorus pig iron casting method, the amount of phosphorus pig iron used is reduced by more than 20%, which can effectively reduce the expansion stress of the cathode carbon block and improve the safety factor.

[0027] Example 2

[0028] like Figure 5As shown, the present invention discloses a low-expansion, segmented, conductive, and energy-saving cathode carbon block assembly structure, comprising a cathode carbon block 1. A dovetail groove 3 is defined on the bottom surface of the cathode carbon block 1. The cathode carbon block 1 is inverted, and two types of conductive materials are laid in the dovetail groove 3. The conductive materials are secured with a paste at the power output end, and with a high-conductivity paste 8 at other locations. A cathode steel bar 2 is then placed in the dovetail groove 3. A middle paste 4 is secured to the outside of the inner end face of the cathode steel bar 2. A side paste 5 is secured between the inner side of the outer end face of the cathode carbon block 1 and both sides of the cathode steel bar 2. High-conductivity paste 8 is secured to both sides of the cathode steel bar 2 between the middle paste 4 and the side paste 5. The conductivity of the side paste 5 is less than that of the paste 8. The side paste 5 extends 1000 mm toward the middle paste 4. The outer end face of the side paste 5 is flush with the end face of the cathode carbon block 1. The significant difference in conductivity between high-performance conductive paste 8 and edge paste 5 is exploited to enhance the conductive effect of the central region of the cathode steel bar 2. Compared to traditional phosphorus pig iron casting methods, this method eliminates the high-expansion phosphorus pig iron and instead uses a low-expansion, high-conductivity paste 8. This effectively reduces the risk of cathode carbon block fracture due to excessive expansion stress. While achieving low cathode voltage drop operation, it also reduces the horizontal current in the aluminum liquid by over 30%, creating favorable conditions for low-voltage operation of the electrolytic cell.

[0029] Example 3

[0030] like Figure 6 As shown, the present invention provides a low-expansion segmented conductive energy-saving cathode carbon block group structure, including a cathode carbon block 1, a dovetail groove 3 is provided on the bottom surface of the cathode carbon block 1, and the cathode carbon block 1 is inverted and three kinds of conductive materials are laid in the dovetail groove 3. The laid conductive materials are fixed with paste at the power output end, cast phosphorus pig iron is used on the side of the paste 4 near the middle of the dovetail groove 3, and the other parts are fixed with high-conductivity paste 8. The cathode steel bar 2 is then placed in the dovetail groove 3. The middle paste 4 is fastened to the outside of the inner end of the cathode steel bar 2. The side paste 5 is fastened between the inner side of the outer end of the cathode carbon block 1 and the sides of the cathode steel bar 2. A section of high-conductivity paste 8 is fastened to both sides of the cathode steel bar 2 between the middle paste 4 and the side paste 5. The paste 8 fastened to both sides of the cathode steel bar 2 is the same length as the paste fastened to the top of the cathode steel bar 2. A section of phosphorus pig iron 6 is cast on both sides of the cathode steel bar 2 between the middle paste 4 and the paste 8. The phosphorus pig iron 6 cast on both sides of the cathode steel bar 2 is the same length as the phosphorus pig iron 6 cast on the top of the cathode steel bar 2. The phosphorus pig iron and paste completely fill both sides of the cathode steel bar 2 between the middle paste 4 and the side paste 5. The conductivity of the side paste 5 is less than that of the paste 8 and the phosphorus pig iron 6. The side paste 5 extends 100 mm toward the middle paste 4. The outer end of the side paste 5 is flush with the end face of the cathode carbon block 1. Compared with the traditional phosphorus pig iron casting method, the amount of phosphorus pig iron used is reduced by more than 50%, which can effectively reduce the expansion stress of the cathode carbon block and improve the safety factor.

[0031] Example 4

[0032] like Figure 7 As shown, in Example 2, the cathode steel rod 2 has a vertical slit 9 extending downward from the top surface, running the width of the rod downward. The slit is 20 mm wide and 200 mm deep, and is filled with an electrically insulating material. The slit 9 is located on the cathode steel rod 2 with the edge paste 5 and is 800 mm from the end face of the cathode carbon block 1. Other features are the same as in Example 2. This structure eliminates the high-expansion phosphorus pig iron, effectively reducing the risk of fracture in the cathode carbon block due to excessive expansion stress.

[0033] Example 5

[0034] In Example 2, the cathode steel bar 2 has a vertical slit 9 extending downward from the top surface, running the width of the bar downward. The slit is 5 mm wide and 100 mm deep. This slit is filled with conventional conductive paste. The slit 9 is flush with the inner end of the edge paste 5 on the cathode steel bar 2 and is 995 mm from the end face of the cathode carbon block 1. Other features are the same as in Example 2. This structure eliminates the high-expansion phosphorus pig iron, effectively reducing the risk of fracture in the cathode carbon block due to excessive expansion stress.

[0035] Example 6

[0036] The vertical seam width and depth of Example 4 are 10 mm, and the rest are the same as Example 4. This structure eliminates the phosphorus pig iron with a high expansion rate, which can effectively reduce the risk of fracture of the cathode carbon block due to excessive expansion stress.

[0037] The present invention employs segmented filling with materials of varying conductivity between the cathode steel rod 2 and the cathode carbon block 1, enhancing the conductive effect of the central region of the cathode steel rod 2. This reduces the horizontal current in the aluminum melt by over 30%, effectively improving the stability of the electrolytic cell. Furthermore, the use of phosphorus pig iron (PFI) or its structure is reduced or eliminated, preventing the harmful effects of its high expansion.

Claims

1. A low-expansion segmented conductive energy-saving cathode carbon block group structure, comprising a cathode carbon block (1), characterized in that: A dovetail groove (3) is provided on the bottom surface of the cathode carbon block (1), and after the cathode carbon block (1) is inverted, 2-3 kinds of conductive materials are laid in the dovetail groove (3), and then the cathode steel rod (2) is placed in the dovetail groove (3), and the middle paste (4) is fastened on the outer side of the inner end surface of the cathode steel rod (2), and the side paste (5) is fastened between the inner side of the outer end surface of the cathode carbon block (1) and the two sides of the cathode steel rod (2), and the two sides of the cathode steel rod (2) between the middle paste (4) and the side paste (5) are filled with 1-2 kinds of high conductivity materials, and the conductivity of the side paste (5) is lower than that of the high conductivity material.

2. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 1, characterized in that: The high conductivity material is phosphorus pig iron (6) and / or paste (8).

3. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 2, characterized in that: The phosphorus pig iron (6) is cast on both sides between the cathode carbon block (1) and the cathode steel rod (2), and the paste (8) is fixed on both sides between the cathode steel rod (2) and the cathode carbon block (1).

4. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 1, characterized in that: The edge paste (5) extends in a direction toward the middle paste (4) by a length of 100-1000 mm.

5. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to any one of claims 1 to 4, characterized in that: The cathode steel bar (2) is provided with a vertical slit (9) extending downward from the top surface thereof in the width direction, with a slit width of 5-20 mm and a depth of 10-200 mm. The vertical slit (9) is filled with an electrical insulating material or a common conductive paste.

6. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 5, characterized in that: The vertical seam (9) is 80-995 mm away from the end face of the cathode carbon block (1).

7. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 5, characterized in that: The vertical seam (9) is provided on the cathode steel rod (2) with the edge paste (5).

8. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 7, characterized in that: The position of the vertical seam (9) on the cathode steel rod (2) is flush with the inner end surface of the edge paste (5).

9. A low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 1, 4, 7 or 8, characterized in that: The outer end surface of the edge paste (5) is flush with the outer end surface of the cathode carbon block (1).

10. The low-expansion segmented conductive energy-saving cathode carbon block assembly structure according to claim 1, characterized in that: The conductive material laid is a paving paste at the power output end, and the other parts are paving paste and / or cast phosphorus pig iron.

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