A cathode assembly structure for balancing the flow rate of aluminum liquid in an aluminum electrolytic cell

Abstract

The present invention discloses a cathode assembly structure for balancing the flow rate of molten aluminum in an aluminum electrolytic cell, which includes a cathode carbon block with a steel bar groove opened along the length direction inside. Two cathode steel bars are respectively arranged opposite to each other at a predetermined distance interval in the steel bar groove, and the ends extend out of the cathode carbon block. The longitudinal sections of the two cathode steel bars are of variable cross-sections and different sizes. The front section of the cathode steel bar is rectangular, the middle section is trapezoidal, and the part extending out of the cathode carbon block at the end is rectangular; a steel bar paste is arranged between the cathode steel bar and the cathode carbon block, an insulator I is arranged near the end of the middle section close to the cathode carbon block, and insulators II and III are arranged on both sides of the middle section near the current output end of the steel bar. By changing the shape of the steel bar and adding insulators near the current output end of the steel bar, the present invention realizes a substantial reduction in the horizontal current, and the cathode carbon blocks of the electrolytic cell are assembled in different ways to obtain a better energy consumption reduction effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of cathode assembly of aluminum electrolytic cells, and particularly relates to a cathode assembly structure for balancing the flow rate of aluminum liquid in an aluminum electrolytic cell by balancing the cathode voltage drop of the aluminum electrolytic cell and reducing the level current. Background Art

[0002] The national ladder electrolysis policy has put forward relatively high energy conservation and consumption reduction requirements for the aluminum electrolysis industry. By 2025, the energy consumption per ton of aluminum in aluminum electrolytic cells should be reduced to 13300 kWh / t-Al, which has brought great challenges to aluminum electrolysis enterprises. The energy consumption of aluminum electrolysis depends on voltage and current efficiency. The current efficiency is limited by the electrolyte system and management level, and the improvement amplitude is limited. At present, the reduction of energy consumption in aluminum electrolytic cells mainly focuses on reducing voltage.

[0003] At present, the main way to reduce voltage is to reduce the interpolar distance voltage drop and the cathode voltage drop. The core of reducing the interpolar distance voltage drop is to reduce the horizontal current, and the methods include obliquely inserting paste, variable cross-section steel bars, slotted steel bars, flow-blocking blocks, curved or convex cathode, etc. The core of reducing the cathode voltage drop lies in reducing the resistivity, and the methods are as follows: using high-graphite carbon blocks to reduce the resistance of cathode carbon blocks, using phosphor cast iron to reduce the contact voltage drop of steel bars, and using high-conductive steel bars or copper-steel bars to reduce the voltage drop of steel bars. Since reducing the cathode and horizontal current are easily in an inverse relationship, that is, reducing the cathode voltage drop easily brings an increase in the horizontal current, and reducing the horizontal current easily brings an increase in the cathode voltage drop. In many cases, the final effect of reducing voltage by these methods is not good. Although copper-steel bars and high-conductive steel bars can both reduce the horizontal current and the cathode voltage drop, copper-steel bars are expensive and difficult to be comprehensively promoted in the aluminum industry, and the reduction amplitude of high-conductive steel bars is limited and the actual effect is poor. At present, many aluminum factories in China adopt the all-graphitized cathode technology, matching copper-steel bars or phosphor cast iron pouring technology, reducing the cathode voltage drop to 150 - 200 mV, resulting in insufficient self-heating of the cathode and poor thermal balance matching of the electrolytic cell. Although the cathode voltage drop is greatly reduced, the actual voltage reduction amplitude is limited. Summary of the Invention

[0004] Based on the above, the present invention proposes a cathode assembly structure for balancing the flow rate of aluminum liquid in an aluminum electrolytic cell, which maintains the cathode voltage drop within a suitable range and greatly reduces the horizontal current. At the same time, considering the congenital difference between the A and B sides of the electrolytic cell, and the characteristic that the flow rate of the B side is significantly greater than that of the A side of the electrolytic cell, it realizes the differential distribution of the cathode voltage drop and the horizontal current on the A and B sides of the electrolytic cell, evenly distributes the flow rate of aluminum liquid in the electrolytic cell, and achieves better effects of reducing voltage and reducing energy consumption.

[0005] The technical solution adopted by the present invention is a cathode assembly structure for balancing the flow rate of molten aluminum in an aluminum electrolytic cell, which includes a cathode carbon block, a cathode steel bar, and a steel bar paste. The cathode steel bar includes a cathode steel plate A and a cathode steel bar B. A steel bar groove is formed in the cathode carbon block along the length direction. The cathode steel bar A and the cathode steel bar B are respectively arranged opposite to each other at a predetermined distance interval in the steel bar groove, and the ends extend out of the cathode carbon block. The longitudinal sections of the cathode steel bar A and the cathode steel bar B are of variable cross-sections and are different in size. A steel bar paste is arranged between the front sections of the cathode steel bar A and the cathode steel bar B and the cathode carbon block, and an insulator 1 is arranged between the middle sections of the cathode steel bar A and the cathode steel bar B near the end of the cathode carbon block and the cathode carbon block.

[0006] Preferably, the front sections of the longitudinal sections of the cathode steel bar A and the cathode steel bar B are rectangular, the middle sections are trapezoidal, and the parts of the end sections extending out of the cathode carbon block are rectangular. The length of the front section of the cathode steel bar A is LA1, the length of the middle section is LA2, the height of the front section is LA3, and the height of the end section is LA4. The length of the front section of the cathode steel bar B is LB1, the length of the middle section is LB2, the height of the front section is LB3, and the height of the end section is LB4. Among them, LB1:LB2 is 1:3 - 1:0.5, LB1 is 0 - 10 cm longer than LA1, LB3 is Y cm, LB3 is 1 - 5 cm higher than LB4, and LB4 is 0 - 2 cm higher than LA4.

[0007] Preferably, insulators 2 and 3 are respectively arranged on both sides of the middle sections of the cathode steel bar A and the cathode steel bar B near the power output end of the steel bar. The length of the insulator 2 is LA5, and the length of the insulator 3 is LB5. The length of LB5 is 0 - 10 cm, and LB5 is 2 - 5 cm longer than LA5.

[0008] Preferably, the cathode carbon block is a non-standard cathode carbon block, with a graphite content of 35% - 45%, a roasting temperature of 1050 - 1100 °C, and a resistivity of 22 - 30 μΩm.

[0009] Preferably, the steel bar paste is a high-conductivity steel bar paste, and the resistivity of the cathode assembly block is < 65 μΩm.

[0010] Preferably, the insulator 1, the insulator 2, and the insulator 3 are air, carbon nitride powder, anti-seepage material, or casting material.

[0011] Compared with the prior art, the beneficial effects of the present invention are:

[0012] 1) In the present invention, the cathode carbon block of the electrolytic cell is assembled at the cathode in different ways using the cathode steel bar A and the cathode steel bar B, which promotes the reduction of the horizontal current amplitude on the A side to be less than that on the B side, better matching the characteristics that the flow rate of the A side of the electrolytic cell is larger and the molten aluminum fluctuates more than that of the B side by nature, evenly distributing the molten aluminum fluctuations on both sides A and B of the electrolytic cell, and achieving a better energy consumption reduction effect;

[0013] 2) The present invention controls the cathode voltage drop between 220 - 260 mV, avoiding the problems of thermal imbalance at the bottom of the electrolytic cell and increased horizontal current caused by a small cathode voltage drop, and can better match the thermal balance of the electrolytic cell;

[0014] 3) By changing the shape of the cathode steel bar and adding insulating materials near the power output end of the cathode steel bar, the present invention increases the resistance at the end near the power output, driving the current towards the middle, and can significantly reduce the horizontal current; BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a schematic structural diagram of the present invention;

[0016] Figure 2 is a top view of the present invention;

[0017] In the figure: 1, cathode carbon block; 2, cathode steel bar; 3, steel bar paste; 4, insulating material 1; 5, insulating material 2; 6, insulating material 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention will be further explained below in conjunction with the drawings of the specification for better understanding by those skilled in the art.

[0019] Example 1

[0020] As Figure 1-2 shown, a cathode assembly structure for balancing the flow rate of aluminum liquid in an aluminum electrolytic cell includes a cathode carbon block 1, a cathode steel bar 2, a steel bar paste 3, an insulating material 1 4, an insulating material 2 5, and an insulating material 3 6. The cathode steel bar 2 includes a cathode steel bar A and a cathode steel bar B. A steel bar groove is provided along the length direction in the cathode carbon block 1. The cathode steel bar A and the cathode steel bar B are respectively arranged opposite to each other at a predetermined distance interval in the steel bar groove and extend out of the cathode carbon block 1 at the end. The longitudinal sections of the cathode steel bar A and the cathode steel bar B are of variable cross-sections and are different in size. The front sections of the longitudinal sections of the cathode steel bar A and the cathode steel bar B are rectangular, the middle sections are trapezoidal, and the parts extending out of the cathode carbon block 1 at the end are rectangular. Among them, a steel bar paste 3 is provided between the front sections of the cathode steel bar A and the cathode steel bar B and the cathode carbon block 1, and an insulating material 1 4 is provided between the middle sections of the cathode steel bar A and the cathode steel bar B near the end of the cathode carbon block 1 and the cathode carbon block 1. Insulating materials 2 5 and 6 are respectively provided on both sides of the middle sections of the cathode steel bar A and the cathode steel bar B near the power output end of the steel bar; the insulating material 1 4, the insulating material 2 5, and the insulating material 3 6 are air, carbon silicon nitride powder, anti-seepage material, or casting material.

[0021] The length of the front section of the cathode steel bar A is LA1, the length of the middle section is LA2, the height of the front section is LA3, and the height of the last section is LA4. The length of the front section of the cathode steel bar B is LB1, the length of the middle section is LB2, the height of the front section is LB3, and the height of the last section is LB4. Among them, LB1:LB2 is 1:3 - 1:0.5, LB1 is 0 - 10 cm longer than LA1, LB3 is Y cm, LB3 is 1 - 5 cm higher than LB4, and LB4 is 0 - 2 cm higher than LA4. The layout length of the second insulator 5 is LA5, and the layout length of the third insulator 6 is LB5. The length of LB5 is 0 - 10 cm, and LB5 is 2 - 5 cm longer than LA5.

[0022] Specifically, the graphite content of the cathode carbon block 1 is 40%, the roasting temperature is 1050, and the resistivity is 26 μΩm; the high-conductivity steel bar paste, and the resistivity of the cathode assembly block is <60 μΩm; the first insulator 4 is air; the second insulator 5 and the third insulator 6 are silicon carbonitride powder. For the cathode steel bar B, LB1 = 90 cm, LB2 = 90 cm, LB3 = 23 cm, LB4 = 21 cm. For the cathode steel bar A, LA1 = 80 cm, LA2 = 100 cm, LA3 = 23 cm, LA4 = 20 cm. LB5 is 8 cm, and LA5 is 6 cm. After the cathode assembly is completed, the cathode voltage drop on the electrolytic cell under the anode current density of 7500 A / m 2 is 240 mV, and the horizontal current in the aluminum liquid is 1000 A / m 2 or less. By adopting this cathode assembly structure, a voltage of 3.85 V can be achieved on the electrolytic cell.

[0023] By changing the shape of the cathode steel bar, adding insulators near the power output end of the cathode steel bar, increasing the resistance near the power output end, driving the current towards the middle, the present invention realizes a significant reduction in the horizontal current. The cathode carbon block 1 of the electrolytic cell is assembled with the cathode steel bar A and the cathode steel bar B in different ways, so that the reduction amplitude of the horizontal current on the A side is less than that on the B side, better matching the characteristics that the flow rate of the A side of the electrolytic cell is larger and the aluminum liquid fluctuates more than that of the B side by nature, evenly distributing the aluminum liquid fluctuation of the AB of the electrolytic cell, obtaining a better energy consumption reduction effect, controlling the cathode voltage drop between 220 - 260 mV, avoiding the problems of thermal imbalance at the bottom of the electrolytic cell and the increase in horizontal current caused by a small cathode voltage drop, and being able to better match the thermal balance of the electrolytic cell.

[0024] The above is only the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A cathode assembly structure for balancing the flow rate of aluminum liquid in an aluminum electrolysis cell, comprising a cathode carbon block (1), a cathode steel bar (2), and steel bar paste (3), characterized in that, The cathode steel bar (2) includes a cathode steel bar A and a cathode steel bar B. The front section of the longitudinal section of the cathode steel bar A and the cathode steel bar B is rectangular, the middle section is trapezoidal, and the part of the end section extending out of the cathode carbon block (1) is rectangular. The length of the front section of the cathode steel bar A is LA1, the length of the middle section is LA2, the height of the front section is LA3, and the height of the end section is LA4. The length of the front section of the cathode steel bar B is LB1, the length of the middle section is LB2, the height of the front section is LB3, and the height of the end section is LB4. LB1:LB2 is 1:3 - 1:0.5, LB1 is 0 - 10 cm longer than LA1, LB3 is 1 - 5 cm higher than LB4, and LB4 is 0 - 2 cm higher than LA4. The cathode carbon block (1) is a non-standard cathode carbon block with a graphite content of 35% - 45%, a roasting temperature of 1050 - 1100 °C, and a resistivity of 22 - 30 μΩm. A steel bar groove is provided along the length direction inside the cathode carbon block (1). The cathode steel bar A and the cathode steel bar B are relatively arranged in the steel bar groove at a predetermined distance respectively, and the ends extend out of the cathode carbon block (1). The longitudinal sections of the cathode steel bar A and the cathode steel bar B are of variable cross-section and different in size. A steel bar paste (3) is provided between the front sections of the cathode steel bar A and the cathode steel bar B and the cathode carbon block (1). An insulator one (4) is provided between the middle sections of the cathode steel bar A and the cathode steel bar B near the end of the cathode carbon block (1) and the cathode carbon block (1).

2. The cathode assembly structure for balancing the aluminum liquid flow rate in an aluminum electrolysis cell according to claim 1, wherein Insulators two (5) and three (6) are respectively provided on both sides of the middle sections of the cathode steel bar A and the cathode steel bar B near the power output end of the steel bar. The length of the arrangement of the insulator two (5) is LA5, and the length of the arrangement of the insulator three (6) is LB5. The length of LB5 is 0 - 10 cm, and LB5 is 2 - 5 cm longer than LA5.

3. The cathode assembly structure for balancing the aluminum liquid flow rate in an aluminum electrolysis cell according to claim 1, characterized in that, The steel bar paste (3) is a high-conductivity steel bar paste, and the resistivity of the cathode assembly block is < 65 μΩm.

4. A cathode assembly structure for balancing the aluminum liquid flow rate in an aluminum electrolysis cell according to claim 1, characterized in that The insulator one (4), the insulator two (5), and the insulator three (6) are air, carbon nitride powder, anti-seepage material, or casting material.

Images