A method for adjusting current efficiency of aluminum electrolysis cell

Abstract

The present application relates to the technical field of aluminum electrolysis, and more specifically, to a method for adjusting the current efficiency of an aluminum electrolytic cell, the method comprising: testing the current efficiency of each electrolytic cell, grading each electrolytic cell according to the current efficiency, and calculating the first average current efficiency of each electrolytic cell and the second average current efficiency of all electrolytic cells; testing the flow velocity field of each electrolytic cell, analyzing the aluminum liquid interface flow velocity at different positions, and determining the average aluminum liquid interface flow velocity of each electrolytic cell; and adjusting the current efficiency of each electrolytic cell according to the electrolytic cell grading, the first average current efficiency, the second average current efficiency, and the average aluminum liquid interface flow velocity. The technical solution provided by the present application can adjust the factors affecting the flow velocity of the aluminum electrolytic cell and improve the current efficiency of the electrolytic cell.

Description

Technical Field

[0001] The present application relates to the technical field of aluminum electrolysis, and in particular to a method for adjusting the current efficiency of an aluminum electrolysis cell. Background Art

[0002] With the advancement of aluminum electrolysis technology, electrolytic cells are gradually becoming larger, which has reduced fixed investment to a certain extent. Larger electrolytic cells place higher demands on the flow field design of the electrolytic cell. On the one hand, the molten aluminum flow rate cannot be too high. A high molten aluminum flow rate increases the deformation of the molten aluminum interface, reduces the stability of the electrolytic cell, and increases the difficulty of operation at low voltage. On the other hand, a high molten aluminum flow rate increases the secondary reaction rate of the molten aluminum, reduces the current efficiency, and affects the economic and technical indicators of the electrolytic cell. If the molten aluminum flow rate is too low, the electrolyte flow rate is poor, the diffusion of alumina is affected, and the uneven alumina distribution affects the current efficiency and economic and technical indicators of the electrolytic cell. Maintaining an appropriate molten aluminum flow rate in the electrolytic cell is conducive to achieving better economic and technical indicators. Therefore, in actual production, the design and management of the electrolytic cell vary, and the appropriate flow rate must be matched to the actual operating conditions of the electrolytic cell.

[0003] Based on this, those skilled in the art are in urgent need of a method for adjusting the current efficiency of an aluminum electrolysis cell, which can adjust the factors affecting the flow rate of the aluminum electrolysis cell and improve the current efficiency of the electrolysis cell. Summary of the Invention

[0004] The embodiments of the present application provide a method for adjusting the current efficiency of an aluminum electrolysis cell, which can adjust factors affecting the flow rate of the aluminum electrolysis cell and improve the current efficiency of the electrolysis cell.

[0005] Other features and advantages of the present application will become apparent from the following detailed description, or may be learned in part by practice of the present application.

[0006] According to one aspect of an embodiment of the present application, a method for adjusting the current efficiency of an aluminum electrolytic cell is provided, the method comprising: testing the current efficiency of each electrolytic cell, grading each electrolytic cell according to each current efficiency, and calculating a first average current efficiency of each electrolytic cell and a second average current efficiency of all electrolytic cells; testing the flow velocity field of each electrolytic cell, analyzing the aluminum liquid interface flow velocity at different positions, and determining the average aluminum liquid interface flow velocity of each electrolytic cell; and adjusting the current efficiency of each electrolytic cell according to the grading of the electrolytic cell, the first average current efficiency, the second average current efficiency, and the average aluminum liquid interface flow velocity.

[0007] In some embodiments of the present application, testing the current efficiency of each electrolytic cell includes: testing the current efficiency of each electrolytic cell by a gas analysis method.

[0008] In some embodiments of the present application, the grading of each electrolytic cell according to each current efficiency includes: grading each electrolytic cell according to each current efficiency, the current efficiency range of each grade is greater than or equal to m% and less than (m+1)%, where m is an integer.

[0009] In some embodiments of the present application, the testing of the flow velocity field of each electrolytic cell includes: determining the flow velocity test points of each electrolytic cell, and testing the aluminum liquid flow and aluminum liquid interface flow velocity at each flow velocity test point by an iron rod dissolution method.

[0010] In some embodiments of the present application, the current efficiency of each electrolytic cell is adjusted according to the electrolytic cell grading, the first average current efficiency, the second average current efficiency, and the average aluminum liquid interface flow rate, including: if the difference between the first average current efficiency between the electrolytic cells in each gradation is less than 1%, no adjustment is made.

[0011] In some embodiments of the present application, the current efficiency of each electrolytic cell is adjusted according to the electrolytic cell grading, each first average current efficiency, the second average current efficiency, and each average aluminum liquid interface flow velocity, including: determining the correlation between each first average current efficiency and each average aluminum liquid interface flow velocity; if each first average current efficiency increases with the increase of each average aluminum liquid interface flow velocity, then reducing the aluminum liquid interface level of the electrolytic cell whose current efficiency is lower than the second average current efficiency to adjust the current efficiency of each electrolytic cell; if each first average current efficiency decreases with the increase of each average aluminum liquid interface flow velocity, then reducing the aluminum liquid interface flow velocity of the electrolytic cell whose current efficiency is lower than the second average current efficiency to adjust the current efficiency of each electrolytic cell.

[0012] In some embodiments of the present application, reducing the level of the aluminum liquid interface of the electrolytic cell having a current efficiency lower than the second average current efficiency includes: reducing the level of the aluminum liquid interface of the electrolytic cell having a current efficiency lower than the second average current efficiency, wherein the single reduction does not exceed 1 cm.

[0013] In some embodiments of the present application, reducing the aluminum liquid interface flow velocity of the electrolytic cell having a current efficiency lower than the second average current efficiency includes: reducing the aluminum liquid interface flow velocity of the electrolytic cell having a current efficiency lower than the second average current efficiency by placing a bluff body.

[0014] In some embodiments of the present application, the bulk density of the bluff body is greater than 3 g / cm 3 The main component of the bluff body is at least one of α-alumina and cryolite.

[0015] In some embodiments of the present application, after adjusting the current efficiency of each electrolytic cell, the method further includes: retesting the current efficiency of each electrolytic cell to ensure that the current efficiency of each electrolytic cell does not decrease after adjustment.

[0016] Based on the above solution, this application has at least the following advantages or improvements:

[0017] In the technical solutions provided in some embodiments of the present application, each electrolytic cell can be graded according to its current efficiency, and the first average current efficiency of each electrolytic cell and the second average current efficiency of all electrolytic cells can be calculated; the flow velocity field of each electrolytic cell can be tested, the aluminum liquid interface flow velocity at different positions can be analyzed, the average aluminum liquid interface flow velocity of each electrolytic cell can be determined, and the current efficiency of each electrolytic cell can be adjusted. The present application can select the current efficiency and average aluminum liquid interface flow velocity of an electrolytic cell with stable cell conditions, analyze the correlation between the current efficiency and the average aluminum liquid interface flow velocity, and improve the current efficiency of the electrolytic cell by adjusting the factors affecting the flow velocity of the aluminum electrolytic cell. The present application is easy to apply, has little impact on the on-site operation of the electrolytic cell, has low technical application cost, can improve the stability of the electrolytic cell, effectively increase the current efficiency, reduce the operating voltage of the electrolytic cell, and improve the economic and technical indicators of the electrolytic cell.

[0018] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0020] Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0021] In the attached figure:

[0022] Figure 1 A simplified flow chart of a method for adjusting the current efficiency of an aluminum electrolysis cell according to one embodiment of the present application is shown. DETAILED DESCRIPTION

[0023] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in many forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that this application will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art.

[0024] In addition, described feature, structure or characteristic can be combined in one or more embodiments in any suitable manner.In the following description, many specific details are provided so as to provide a full understanding of the embodiments of the present application. However, it will be appreciated by those skilled in the art that the technical scheme of the present application can be put into practice without one or more of the specific details, or other methods, components, devices, steps etc. can be adopted. In other cases, known methods, devices, implementations or operations are not shown or described in detail to avoid blurring the various aspects of the application.

[0025] It should be noted that the term "plurality" used in this document refers to two or more. "And / or" describes a relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A alone, A and B together, or B alone. The character " / " generally indicates an "or" relationship between the associated objects.

[0026] See also Figure 1 .

[0027] Figure 1 A simplified flow chart of a method for adjusting the current efficiency of an aluminum electrolysis cell according to an embodiment of the present application is shown. Figure 1 As shown, the method may include steps S101-S103:

[0028] Step S101 , testing the current efficiency of each electrolytic cell, classifying each electrolytic cell according to the current efficiency, and calculating the first average current efficiency of each electrolytic cell and the second average current efficiency of all electrolytic cells.

[0029] Step S102: testing the flow velocity field of each electrolytic cell, analyzing the aluminum liquid interface flow velocity at different positions, and determining the average aluminum liquid interface flow velocity of each electrolytic cell.

[0030] Step S103, adjusting the current efficiency of each electrolytic cell according to the electrolytic cell classification, each first average current efficiency, each second average current efficiency, and each average aluminum liquid interface flow velocity.

[0031] In the present application, each electrolytic cell can be graded according to its current efficiency, and the first average current efficiency of each electrolytic cell and the second average current efficiency of all electrolytic cells can be calculated; the flow velocity field of each electrolytic cell can be tested, the aluminum liquid interface flow velocity at different positions can be analyzed, the average aluminum liquid interface flow velocity of each electrolytic cell can be determined, and the current efficiency of each electrolytic cell can be adjusted. The present application can select the current efficiency and average aluminum liquid interface flow velocity of the electrolytic cell with stable cell conditions, analyze the correlation between the current efficiency and the average aluminum liquid interface flow velocity, and improve the current efficiency of the electrolytic cell by adjusting the factors affecting the flow velocity of the aluminum electrolytic cell. The present application is easy to apply, has little impact on the on-site operation of the electrolytic cell, has low technical application cost, can improve the stability of the electrolytic cell, effectively improve the current efficiency, reduce the operating voltage of the electrolytic cell, and improve the economic and technical indicators of the electrolytic cell.

[0032] In the present application, the method for testing the current efficiency of each electrolytic cell may include: testing the current efficiency of each electrolytic cell by gas analysis. In the present application, the aluminum liquid interface flow velocity at different positions is analyzed to determine the average aluminum liquid interface flow velocity v of the corresponding electrolytic cell. i .

[0033] In the present application, the method of grading each electrolytic cell according to each current efficiency may include: grading each electrolytic cell according to each current efficiency, and the current efficiency range of each grade may be greater than or equal to m% and less than (m+1)%, where m is an integer.

[0034] In the present application, an electrolytic cell operation team, work area or series can be determined, and electrolytic cells with stable and normal conditions can be selected. The current efficiency η of each electrolytic cell can be tested, and the current efficiency η of each electrolytic cell can be divided into grades according to the test value of the electrolytic cell efficiency. The current efficiency range of each grade is m%≤η<(m+1)%, and m is an integer. The first average efficiency η of each electrolytic cell is calculated. i and the second average current efficiency η of all electrolytic cells 平均 .

[0035] In the present application, the method for testing the flow velocity field of each electrolytic cell may include: determining the flow velocity test point of each electrolytic cell, and testing the aluminum liquid flow and aluminum liquid interface flow velocity at each flow velocity test point by an iron rod dissolution method.

[0036] In this application, the flow rate test points can be the large surface processing surface, the end processing surface, and the center seam cutting point.

[0037] In the present application, the method of adjusting the current efficiency of each electrolytic cell according to the electrolytic cell grading, each first average current efficiency, the second average current efficiency, and each average aluminum liquid interface flow rate may include: if the difference between the first average current efficiencies between the electrolytic cells in each gradation is less than 1%, no adjustment is made.

[0038] In this application, if each electrolytic cell can only be divided into one level, no adjustment is made. If each electrolytic cell can only be divided into two levels, and the difference between the first average current efficiencies of the two levels is no more than 1%, no adjustment is made.

[0039] In the present application, the method for adjusting the current efficiency of each electrolytic cell according to the electrolytic cell grading, each first average current efficiency, the second average current efficiency, and each average aluminum liquid interface flow velocity may include: determining the correlation between each first average current efficiency and each average aluminum liquid interface flow velocity; if each first average current efficiency increases with the increase of each average aluminum liquid interface flow velocity, then reducing the aluminum liquid interface level of the electrolytic cell whose current efficiency is lower than the second average current efficiency to adjust the current efficiency of each electrolytic cell; if each first average current efficiency decreases with the increase of each average aluminum liquid interface flow velocity, then reducing the aluminum liquid interface flow velocity of the electrolytic cell whose current efficiency is lower than the second average current efficiency to adjust the current efficiency of each electrolytic cell.

[0040] In this application, η can be analyzed i With v i If η i With v i The correlation is not strong, no adjustment is made; if η i Follow v i As the current increases, the efficiency decreases below η 平均 Aluminum level in the electrolytic cell; if η i Follow v i Increases and decreases, when the current efficiency of each unit is lower than η 平均 Place flow blocks at the 10% test points with the largest interface flow velocity in the electrolytic cell to reduce the average interface flow velocity of the aluminum liquid.

[0041] In the present application, the height of the aluminum liquid interface of the electrolytic cell having a current efficiency lower than the second average current efficiency is reduced, wherein the single reduction amplitude does not exceed 1 cm.

[0042] In the present application, the method for reducing the aluminum liquid interface flow velocity of the electrolytic cell having a current efficiency lower than the second average current efficiency may include: reducing the aluminum liquid interface flow velocity of the electrolytic cell having a current efficiency lower than the second average current efficiency by placing a bluff body.

[0043] In this application, the bulk density of the bluff body is greater than 3g / cm 3 The main component of the bluff body is at least one of α-alumina and cryolite. In addition, the bluff body may also contain components such as calcium fluoride, magnesium fluoride, lithium fluoride, potassium fluoride, and sodium fluoride.

[0044] In the present application, the bluff body is fully preheated before entering the slot, and after entering the slot, it is ensured that the bluff body is placed in the designated position; after entering the slot, the position and shape of the bluff body are checked every time the pole is changed. If the volume of the bluff body becomes significantly smaller, the bluff body is replaced; if the position changes, it is returned to its original position in time.

[0045] In the present application, after adjusting the current efficiency of each electrolytic cell, the method further includes: retesting the current efficiency of each electrolytic cell to ensure that the current efficiency of each electrolytic cell does not decrease after adjustment.

[0046] In order to enable those skilled in the art to have a deeper understanding of the present application, the present application will be described below with reference to specific embodiments.

[0047] Example 1

[0048] Select an electrolytic cell in a certain electrolytic cell operation team whose cell condition is stable and normal, test the current efficiency η of each electrolytic cell, divide the electrolytic cell into grades according to the electrolytic cell efficiency test value, and calculate the first average current efficiency η of each electrolytic cell according to the current efficiency range of each grade m%≤η<(m+1)%, where m is an integer. i and the second average current efficiency η of all electrolytic cells 平均 The results are shown in Table 1. The electrolytic cell current efficiency was between 90% and 91%, with an average of 90.53%, without the adjustment method.

[0049] Table 1 Current efficiency of a certain electrolytic cell operation team

[0050]

[0051]

[0052] Example 2

[0053] Select an electrolytic cell in a certain electrolytic cell operation team whose cell condition is stable and normal, test the current efficiency η of each electrolytic cell, divide the electrolytic cell into grades according to the electrolytic cell efficiency test value, and calculate the first average current efficiency η of each electrolytic cell according to the current efficiency range of each grade m%≤η<(m+1)%, where m is an integer. i and the second average current efficiency η of all electrolytic cells 平均 .

[0054] Test the flow field of each electrolytic cell mentioned above, analyze the aluminum liquid interface flow velocity at different positions, and obtain the average aluminum liquid interface flow velocity v of the corresponding electrolytic cell. i ; The results are shown in Table 2. Analysis η i With v i The correlation, η i With v i The correlation is not strong, so this method is not used for adjustment.

[0055] Table 2 Current efficiency and aluminum liquid interface velocity of a certain electrolytic cell operation team

[0056]

[0057]

[0058] Example 3

[0059] Select an electrolytic cell in a certain electrolytic cell operation area where the cell condition is stable and normal, test the current efficiency η of each electrolytic cell, divide the electrolytic cell into grades according to the electrolytic cell efficiency test value, and calculate the first average current efficiency η of each electrolytic cell according to the current efficiency range of each grade m%≤η<(m+1)%, where m is an integer. i and the second average current efficiency η of all electrolytic cells 平均。

[0060] Test the flow field of each electrolytic cell mentioned above, analyze the aluminum liquid interface flow velocity at different positions, and obtain the average aluminum liquid interface flow velocity v of the corresponding electrolytic cell. i ; The results are shown in Table 3.

[0061] Table 3 Current efficiency of electrolytic cell and aluminum liquid interface velocity in a certain electrolytic cell operation area

[0062]

[0063]

[0064] Analysis η i With v i The correlation, η i Follow v i Increases and decreases, when the current efficiency of each unit is lower than η 平均 Place flow blocks at the 10% test points with the largest interface flow velocity in the electrolytic cell to reduce the average interface flow velocity of the aluminum liquid.

[0065] Table 4 shows the aluminum interface velocity for a 3002 electrolytic cell. Placing flow blocks at the 10% test points (A2, A3, A16, A17, and A18, A19) with the highest interface velocity reduced both the average and maximum aluminum interface velocity. As shown in Table 5, the cell's current efficiency increased from 88.50% to 90.08%. Re-installing the flow blocks resulted in little change in current efficiency. Therefore, placing the flow blocks only once is recommended.

[0066] Table 4 Aluminum liquid interface velocity before adjustment of 3002 electrolytic cell / cm / s

[0067]

[0068]

[0069] Table 5 Aluminum liquid interface velocity after adjustment of 3002 electrolytic cell / cm / s

[0070]

[0071]

[0072] After using the same adjustment method, the current efficiency of 3024, 3001, and 3023 all increased by more than 0.5%, achieving good results. The efficiency of 3025 increased by 0.2% after adjustment. The current efficiency of the remaining electrolyzers with below-average efficiency did not change significantly after adjustment, so no adjustment is recommended.

[0073] Example 4

[0074] Select an electrolytic cell in a certain electrolytic cell operation area where the cell condition is stable and normal, test the current efficiency η of each electrolytic cell, divide the electrolytic cell into grades according to the electrolytic cell efficiency test value, and calculate the first average current efficiency η of each electrolytic cell according to the current efficiency range of each grade m%≤η<(m+1)%, where m is an integer. i and the second average current efficiency η of all electrolytic cells 平均。

[0075] Test the flow field of each electrolytic cell mentioned above, analyze the aluminum liquid interface flow velocity at different positions, and obtain the average aluminum liquid interface flow velocity v of the corresponding electrolytic cell. i ; The results are shown in Table 6.

[0076] Table 6 Current efficiency of electrolytic cell and aluminum liquid interface velocity in a certain electrolytic cell operation area

[0077]

[0078]

[0079] Analysis η i With v i The correlation, η i Follow v i As the current increases, the efficiency decreases below η 平均 The aluminum level of the electrolytic cell was lowered by 1 cm at a time, and the current efficiency and aluminum liquid interface flow rate were measured after each reduction.

[0080] Table 7 shows the aluminum interface flow rate for a 4001 electrolytic cell. Lowering the aluminum level by 1 cm increased both the average and maximum aluminum interface flow rates. As shown in Table 8, the cell's current efficiency increased from 90.49% to 91.04%. Lowering the aluminum level again resulted in little change in current efficiency. Therefore, adjusting the aluminum level only once is recommended.

[0081] Table 7 Aluminum liquid interface velocity before aluminum level adjustment in 4001 electrolytic cell (cm / s)

[0082]

[0083]

[0084] Table 8 Aluminum liquid interface velocity after 4001 electrolytic cell aluminum level adjustment (cm / s)

[0085]

[0086]

[0087] After using the same adjustment method, the current efficiency of 4016, 4015, 4002, 4017, and 4003 all increased by more than 0.5%, achieving good results. The efficiency of 4004, 4014, and 4027 increased by 0.2% after adjustment. The current efficiency of the remaining electrolyzers with below-average efficiency did not change significantly after adjustment, so no adjustment is recommended.

[0088] Those skilled in the art will readily conceive of other embodiments of the present application after considering the specification and practicing the embodiments disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present application that follow the general principles of this application and include common knowledge or customary techniques in the art that are not disclosed herein.

[0089] It should be understood that the present application is not limited to the exact structures described above and shown in the drawings, and that various modifications and changes may be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A method for adjusting the current efficiency of an aluminum electrolysis cell, characterized in that: The method comprises: Testing the current efficiency of each electrolytic cell, classifying each electrolytic cell according to the current efficiency, and calculating the first average current efficiency of each electrolytic cell and the second average current efficiency of all electrolytic cells; Test the flow velocity field of each electrolytic cell, analyze the aluminum liquid interface flow velocity at different positions, and determine the average aluminum liquid interface flow velocity of each electrolytic cell; Adjusting the current efficiency of each electrolytic cell according to the electrolytic cell classification, the first average current efficiency, the second average current efficiency, and the average aluminum liquid interface flow rate; The step of grading the electrolytic cells according to their current efficiencies comprises: Each electrolytic cell is divided into grades according to its current efficiency, and the current efficiency range of each grade is greater than or equal to m% and less than (m+1)%, where m is an integer; The adjusting the current efficiency of each electrolytic cell according to the electrolytic cell classification, each first average current efficiency, each second average current efficiency, and each average aluminum liquid interface flow velocity includes: Determining the correlation between each first average current efficiency and each average aluminum liquid interface flow velocity; If the first average current efficiency increases with the increase of the average aluminum liquid interface flow rate, then the aluminum liquid interface level of the electrolytic cell having a current efficiency lower than the second average current efficiency is reduced to adjust the current efficiency of each electrolytic cell; If the first average current efficiencies decrease as the average aluminum liquid interface flow velocities increase, the aluminum liquid interface flow velocities of the electrolytic cells having current efficiencies lower than the second average current efficiency are reduced to adjust the current efficiency of each electrolytic cell.

2. The method according to claim 1, characterized in that The current efficiency of each electrolytic cell is tested, comprising: The current efficiency of each electrolytic cell was tested by gas analysis.

3. The method according to claim 1, characterized in that The test of the flow velocity field of each electrolytic cell comprises: Determine the flow rate test points of each electrolytic cell, and test the aluminum liquid flow and aluminum liquid interface flow rate at each flow rate test point by the iron rod dissolution method.

4. The method according to claim 1, wherein The adjusting the current efficiency of each electrolytic cell according to the electrolytic cell classification, each first average current efficiency, each second average current efficiency, and each average aluminum liquid interface flow velocity includes: If the difference between the first average current efficiencies of the electrolytic cells in each gear is less than 1%, no adjustment is performed.

5. The method according to claim 1, wherein The step of reducing the aluminum liquid interface level of the electrolytic cell having a current efficiency lower than the second average current efficiency comprises: The height of the aluminum liquid interface of the electrolytic cell having a current efficiency lower than the second average current efficiency is reduced, wherein the single reduction does not exceed 1 cm.

6. The method according to claim 1, characterized in that The reducing the aluminum liquid interface flow velocity of the electrolytic cell having a current efficiency lower than the second average current efficiency comprises: The aluminum liquid interface flow velocity of the electrolytic cell having a current efficiency lower than the second average current efficiency is reduced by placing a bluff body.

7. The method according to claim 6, characterized in that The bulk density of the bluff body is greater than 3 g / cm 3 The main component of the bluff body is at least one of α-alumina and cryolite.

8. The method according to claim 1, characterized in that After adjusting the current efficiency of each electrolytic cell, the method further includes: The current efficiency of each electrolytic cell was tested again to ensure that the current efficiency of each electrolytic cell did not decrease after adjustment.

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