A method for reducing the potassium content in aluminum electrolyte

Abstract

The present application relates to a method for reducing the potassium content in aluminum electrolyte, which comprises the following steps: collecting solid matter from the fumes generated during the aluminum electrolysis process in an aluminum electrolysis system; treating the solid matter at a predetermined temperature to volatilize KAlF4, obtaining potassium-depleted fluorine-bearing alumina; and returning the potassium-depleted fluorine-bearing alumina to the aluminum electrolysis system. The present application utilizes the characteristics that the melting point of KAlF4 in the solid volatiles contained in the fumes generated during the aluminum electrolysis process is relatively low, and other solid volatiles will transform into KAlF4 at high temperatures, so that the K element in the solid volatiles continuously dissociates in the form of KAlF4, and finally the K element content in the solid matter is reduced. After obtaining the potassium-depleted fluorine-bearing alumina, it is returned to the aluminum electrolysis system to reduce the K element content in the aluminum electrolysis system. The present application can remove the K element in the fluorine-bearing alumina before it is returned to the aluminum electrolysis system, while making full use of the fluorine-bearing alumina for aluminum electrolysis, and reducing the K element content in the aluminum electrolysis system.

Description

Technical Field

[0001] This application relates to the field of the aluminum industry, and particularly to electrolytic aluminum. Background Art

[0002] The cryolite-aluminum oxide molten salt electrolysis method is the mainstream method in the aluminum smelting industry. The cryolite-aluminum oxide molten salt is also called aluminum electrolyte, which is the reaction medium for dissolving aluminum oxide during the aluminum electrolysis process and electrolytically reducing aluminum oxide to metallic aluminum.

[0003] Due to reasons such as the resources for producing aluminum oxide and the preparation process in our country, potassium oxide is contained in domestic aluminum oxide to varying degrees. After potassium oxide in the aluminum oxide enters the aluminum electrolyte, it forms fluorides (usually simply approximated as potassium fluoride) and continuously accumulates until a balanced concentration is finally reached. The content of potassium oxide in the aluminum oxide usually determines the balanced concentration of potassium fluoride in the aluminum electrolyte. The higher the content of potassium oxide in the aluminum oxide, the higher the balanced concentration of potassium fluoride in the aluminum electrolyte. When the potassium fluoride exceeds 3wt%, it will have a significant impact on the electrolysis process. For example, the amount of carbon slag increases, the current efficiency decreases, the energy consumption increases, and even the service life of the electrolytic cell is reduced.

[0004] During the aluminum electrolysis process, a large amount of fumes are generated from the aluminum electrolyte, including a part of solid volatiles, which enter the aluminum electrolysis flue gas purification system. The volatiles leave the electrolyte melt in a gaseous form and decompose and combine when the temperature drops, becoming solid volatiles. Finally, the components in the aluminum electrolysis fumes are relatively complex, mainly including flying Al2O3, and in addition, solid volatiles, mainly including Na5Al3F 14 、AlF3、Na2AlF5、K2NaAl3F 12 、K2NaAlF6、KAlF4, etc. In the alumina adsorption process, these solid volatiles will be adsorbed by the alumina together with HF gas to form fluorine-bearing alumina. In the prior art, the fluorine-bearing alumina then enters the aluminum electrolytic cell through the conveying system. That is, what finally enters the aluminum electrolytic cell is the fluorine-bearing alumina.

[0005] By comparing and analyzing the potassium content in fresh alumina and fluorine-bearing alumina, and calculating it in terms of K2O, it is found that the content of K2O in the fluorine-bearing alumina is higher than that in the fresh alumina, which is caused by the adsorption of solid volatiles. However, there are difficult problems in dealing with these solid volatiles. Since this part of the solid contains a large amount of elements such as Al2O3, F, and Na, if it is not returned to the aluminum electrolysis system, it will increase the single consumption of alumina in the system and even increase the single consumption of fluoride salts in the system; directly returning it to the system cannot effectively solve the problem of high potassium concentration in the electrolyte. Summary of the Invention

[0006] The embodiments of the present application provide a method for reducing the potassium content in aluminum electrolyte to solve the technical problem of difficult treatment of fluorine-bearing alumina with high potassium content.

[0007] The embodiments of the present application provide a method for reducing the potassium content in aluminum electrolyte, and the method for reducing the potassium content in aluminum electrolyte includes the following steps:

[0008] Collect solids from the soot generated during the aluminum electrolysis process in the aluminum electrolysis system;

[0009] Treat the solids at a predetermined temperature to volatilize KAlF4 to obtain potassium-depleted fluorine-bearing alumina;

[0010] Return the potassium-depleted fluorine-bearing alumina to the aluminum electrolysis system.

[0011] In some embodiments of the present application, the treatment of the solids at a predetermined temperature is carried out in a kiln, and the kiln is one of a rotary furnace, a rotary kiln or a fluidized bed furnace.

[0012] In some embodiments of the present application, the lining material of the kiln is at least one of quartz bricks, silica bricks, and high-alumina bricks.

[0013] In some embodiments of the present application, the predetermined temperature is 600 - 1000 °C.

[0014] In some embodiments of the present application, the predetermined temperature is 700 - 900 °C.

[0015] In some embodiments of the present application, the treatment of the solids at a predetermined temperature is carried out for a treatment time of 1 second to 240 minutes.

[0016] In some embodiments of the present application, based on the mass fraction of K2O, the mass fraction of K2O in the potassium-depleted fluorine-bearing alumina is not higher than 0.1%.

[0017] In some embodiments of the present application, the method for reducing the potassium content in aluminum electrolyte further includes the following steps:

[0018] Collect the flue gas generated by the volatilization of KAlF4.

[0019] In some embodiments of the present application, the collection of the flue gas generated by the volatilization of KAlF4 is collected by a bag dust collector.

[0020] In some embodiments of the present application, the temperature of the flue gas is reduced to below 150 °C before entering the bag dust collector.

[0021] The above technical solutions provided by the embodiments of the present application have the following advantages compared with the prior art:

[0022] The method for reducing the potassium content in aluminum electrolyte provided by the embodiments of the present application utilizes the characteristics that the melting point of KAlF4 in the solid volatiles contained in the soot generated during the aluminum electrolysis process is relatively low, and other solid volatiles will transform into KAlF4 at high temperatures. This enables the continuous separation of K elements in the solid volatiles in the form of KAlF4. Eventually, the K element content in the solid matter is reduced. After obtaining potassium-removed fluorine-carrying alumina, it is returned to the aluminum electrolysis system to reduce the K element content in the aluminum electrolysis system. The present application can remove K elements in the fluorine-carrying alumina before it is returned to the aluminum electrolysis system, reducing the K element content in the aluminum electrolysis system while making full use of the fluorine-carrying alumina for aluminum electrolysis. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings herein are incorporated into and constitute a part of this specification, showing embodiments consistent with the present application, and are used together with the specification to explain the principles of the present application.

[0024] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for use in the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is a schematic flow chart of a method for reducing the potassium content in aluminum electrolyte provided by the embodiments of the present application. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present application.

[0027] Unless otherwise specifically stated, the terms used herein should be understood as having the meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as the general understanding of those skilled in the technical field to which the present application belongs. In case of any contradiction, this specification shall prevail.

[0028] Unless otherwise specifically stated, various raw materials, reagents, instruments, and equipment used in the present application can all be obtained through market purchases or can be prepared by existing methods.

[0029] In the existing cryolite-alumina molten salt electrolysis method for producing aluminum, there is a technical problem that it is difficult to handle fluorine-carrying alumina with a high potassium content.

[0030] The technical solution provided by the embodiments of the present application to solve the above technical problems has the following general idea:

[0031] The embodiments of the present application provide a method for reducing the potassium content in aluminum electrolyte. The method for reducing the potassium content in aluminum electrolyte includes the following steps:

[0032] S1: Collect solids from the fumes generated during the aluminum electrolysis process in the aluminum electrolysis system;

[0033] S2: Treat the solids at a predetermined temperature to volatilize KAlF4 and obtain potassium-depleted and fluorine-bearing alumina;

[0034] S3: Return the potassium-depleted and fluorine-bearing alumina to the aluminum electrolysis system.

[0035] Those skilled in the art can understand that the potassium-depleted and fluorine-bearing alumina can be directly returned to the process of producing aluminum by the cryolite-alumina fused salt electrolysis method.

[0036] During the aluminum electrolysis process, a large amount of fumes are generated in the aluminum electrolyte, including a part of solid volatiles, which enter the aluminum electrolysis flue gas purification system. The volatiles leave the electrolyte melt in a gaseous form and decompose and combine when the temperature drops, becoming solid volatiles. Eventually, the components in the aluminum electrolysis fumes are relatively complex, mainly including flying Al2O3, and in addition, solid volatiles, mainly including Na5Al3F 14 , AlF3, Na2AlF5, K2NaAl3F 12 , K2NaAlF6, KAlF4, etc. In the alumina adsorption process, these solid volatiles will be adsorbed by the alumina together with HF gas to form fluorine-bearing alumina. In the prior art, the fluorine-bearing alumina then enters the aluminum electrolysis cell through the conveying system. That is, the final material entering the aluminum electrolysis cell is the fluorine-bearing alumina.

[0037] Among the above solid volatiles, KAlF4 has a relatively lower melting point, which is 575 °C, and the melting points of the other adsorbed solid volatiles all reach above 1000 °C. As the temperature rises, the vapor pressure of KAlF4 increases rapidly, and the volatilization rate of KAlF4 is significantly accelerated at 600 °C and above. The other fluorides and alumina are still in a solid state, which is conducive to achieving selective removal. And at high temperatures, these solid volatiles will also undergo phase transformation reactions with each other. As KAlF4 continuously volatilizes and separates from the solid / liquid mixed phase, the other solid volatiles will continuously transform into KAlF4 and finally volatilize to reduce the K element content in the solids.

[0038] This application utilizes the characteristics that the melting point of KAlF4 in the solid volatiles contained in the soot generated during the aluminum electrolysis process is relatively low, and other solid volatiles will transform into KAlF4 at high temperatures. This enables the continuous separation of K elements in the solid volatiles in the form of KAlF4, ultimately reducing the K element content in the solid matter. After obtaining potassium-depleted and fluorine-loaded alumina, it is returned to the aluminum electrolysis system to reduce the K element content in the aluminum electrolysis system. This application can remove K elements from the fluorine-loaded alumina before it is returned to the aluminum electrolysis system, reducing the K element content in the aluminum electrolysis system while making full use of the fluorine-loaded alumina for aluminum electrolysis.

[0039] In some embodiments of this application, the treatment of the solid matter at a predetermined temperature is carried out in a kiln, and the kiln is one of a rotary furnace, a rotary kiln, or a fluidized bed furnace.

[0040] A rotary furnace, a rotary kiln, or a fluidized bed furnace is conducive to the mass transfer of fluorides in alumina and the volatilization of KAlF4 at high temperatures.

[0041] In some embodiments of this application, the lining material of the kiln is at least one of quartz bricks, silica bricks, and high-alumina bricks.

[0042] The above-mentioned lining materials can withstand the erosion of fluorides and extend the service life of the kiln.

[0043] In some embodiments of this application, the predetermined temperature is 600 - 1000 °C.

[0044] The melting point of KAlF4 is 575 °C, and with the increase in temperature, the vapor pressure of KAlF4 increases rapidly. In the above temperature range, the volatilization rate of KAlF4 significantly accelerates, while other fluorides and alumina remain solid, but a phase transformation reaction of transforming into KAlF4 will occur in the presence of K elements, which is conducive to achieving selective removal.

[0045] In some embodiments of this application, the predetermined temperature is 700 - 900 °C.

[0046] In the above temperature range, the temperature is high enough so that the vapor pressure of KAlF4 is relatively high, the volatilization rate is fast enough, and the phase transformation reaction rate is relatively fast; practice shows that when the predetermined temperature is higher than 900 °C, the removal rate of KAlF4 becomes very slow with the increase in temperature. This may be because the phase transformation reaction rate of KAlF4 transforming into other solid volatiles also accelerates at too high temperatures, which may instead lead to a decrease in the total amount of KAlF4 in the system. In this case, the efficiency improvement brought about by further increasing the temperature is limited.

[0047] In some embodiments of this application, the treatment time for treating the solid matter at a predetermined temperature is from 1 second to 240 minutes.

[0048] When the treatment time of the solid in the fluidized bed is short and the potassium content in the solid is very low, most of the KAlF4 may be removed in just a few seconds in the fluidized bed. The treatment time of the solid in the rotary furnace is long.

[0049] In some embodiments of the present application, based on the mass fraction of K2O, the mass fraction of K2O in the potassium-removed and fluorine-bearing alumina is not higher than 0.1%.

[0050] The potassium content in the potassium-removed and fluorine-bearing alumina being less than 0.1% is the treatment target for potassium removal from the solid in the present application to ensure the efficient and stable operation of aluminum electrolysis production and meet the actual production needs.

[0051] In some embodiments of the present application, the method for reducing the potassium content in the aluminum electrolyte further includes the following steps:

[0052] S31: Collect the flue gas generated by the volatilization of KAlF4.

[0053] Those skilled in the art can understand that KAlF4 can be recycled and reused, for example, sold after purification.

[0054] In some embodiments of the present application, the flue gas generated by the volatilization of KAlF4 is collected by a bag dust collector.

[0055] In some embodiments of the present application, the flue gas enters the bag dust collector after the temperature is reduced to below 150°C.

[0056] Before entering the bag dust collector, the temperature of the flue gas should be reduced to reduce the damage of the high-temperature flue gas to the filter bag and improve the service life of the dust collector.

[0057] In addition, it should be noted that in the present application, the potassium content is all based on the mass fraction of K2O.

[0058] The following further elaborates the present application in combination with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods without specific conditions in the following embodiments are usually determined according to national standards. If there is no corresponding national standard, they are carried out according to general international standards, conventional conditions, or the conditions recommended by the manufacturer.

[0059] Example 1

[0060] In an aluminum electrolysis production line, the potassium content in the fresh alumina raw material is 0.041% (calculated as K2O). Using the fresh alumina as the raw material, aluminum is produced by the cryolite-alumina fused salt electrolysis method, and the solid in the dust generated during the electrolysis process is collected. The potassium content in the solid is 0.097% (calculated as K2O).

[0061] The collected solids are added to a fluidized bed furnace. The treatment temperature is 600 °C, and the residence time of the solids in the reaction zone is 20 minutes. The KAlF4 in the solids is volatilized by high temperature to obtain low-potassium fluorinated alumina. The separated high-temperature flue gas is cooled to below 150 °C and collected by a bag dust collection system. The dust is used to extract KAlF4. The inner lining of the fluidized bed furnace is made of quartz bricks, silica bricks, and high-alumina bricks.

[0062] The potassium content in the obtained low-potassium fluorine-bearing alumina is 0.049% (calculated as K2O), which is directly returned to the aluminum electrolysis system as raw material for aluminum electrolysis. The alumina consumption of the enterprise is 1920 kg / t-Al, and the fluorine-bearing alumina treated by the above method is equivalent to 500 kg / t-Al. Before using the above method, the KF concentration in the electrolyte of the enterprise was 5.1%. After using the potassium-depleted fluorine-bearing alumina for 6 months, the KF concentration in the electrolyte was 3.8%, and the current efficiency increased by 1.1%.

[0063] Example 2

[0064] In a certain aluminum electrolysis production line, the potassium content in the fresh alumina raw material is 0.042% (calculated as K2O). Using the fresh alumina as raw material, aluminum is produced by the cryolite-alumina molten salt electrolysis method. The solids in the dust generated during the electrolysis process are collected. The potassium content in the solids is 0.106% (calculated as K2O).

[0065] The collected solids are added to a converter. The treatment temperature is 700 °C, and the residence time of the solids in the reaction zone is 240 minutes. The KAlF4 in the solids is volatilized by high temperature to obtain low-potassium fluorinated alumina. The separated high-temperature flue gas is cooled to below 150 °C and collected by a bag dust collection system. The dust is used to extract KAlF4. The inner lining of the converter is made of quartz bricks and high-alumina bricks.

[0066] The potassium content in the obtained low-potassium fluorine-bearing alumina is 0.045% (calculated as K2O), which is directly returned to the aluminum electrolysis system as raw material for aluminum electrolysis. The alumina consumption of the enterprise is 1920 kg / t-Al, and the fluorine-bearing alumina treated by the above method is equivalent to 800 kg / t-Al. Before using the above method, the KF concentration in the electrolyte of the enterprise was 5.2%. After using the potassium-depleted fluorine-bearing alumina for 6 months, the KF concentration in the electrolyte was 2.2%, and the current efficiency increased by 1.6%.

[0067] Example 3

[0068] In a certain aluminum electrolysis production line, the potassium content in the fresh alumina raw material is 0.035% (calculated as K2O). Using the fresh alumina as raw material, aluminum is produced by the cryolite-alumina molten salt electrolysis method. The solids in the dust generated during the electrolysis process are collected. The potassium content in the solids is 12.42% (calculated as K2O).

[0069] The collected solids are added to a rotary kiln. The treatment temperature is 800 °C, and the residence time of the solids in the reaction zone is 60 minutes. The KAlF4 in the solids is volatilized by high temperature to obtain low-potassium fluorine-containing alumina. The separated high-temperature flue gas is cooled to below 150 °C and collected by a bag dust collection system. The soot is used to extract potassium- and fluorine-containing compounds. The inner lining material of the rotary kiln is made of high-alumina bricks.

[0070] The potassium content in the obtained low-potassium fluorine-containing alumina is 0.046% (calculated as K2O), which is directly returned to the aluminum electrolysis system as raw material for aluminum electrolysis. The alumina consumption of the enterprise is 1925 kg / t-Al, and the fluorine-containing alumina treated by the above method is equivalent to 8 kg / t-Al. Before using the above method, the KF concentration in the electrolyte of the enterprise was 4.3%. After using the potassium-depleted fluorine-containing alumina for 6 months, the KF concentration in the electrolyte was 1.9%, and the current efficiency increased by 1.5%.

[0071] Example 4

[0072] In an aluminum electrolysis production line, the potassium content in the fresh alumina raw material is 0.037% (calculated as K2O). Using the fresh alumina as raw material, aluminum is produced by the cryolite-alumina molten salt electrolysis method. The solids in the soot generated during the electrolysis process are collected, and the potassium content in the solids is 0.146% (calculated as K2O).

[0073] The collected solids are added to a converter. The treatment temperature is 1000 °C, and the residence time of the solids in the reaction zone is 20 minutes. The KAlF4 in the solids is volatilized by high temperature to obtain low-potassium fluorine-containing alumina. The separated high-temperature flue gas is cooled to below 150 °C and collected by a bag dust collection system. The soot is used to extract potassium- and fluorine-containing compounds. The inner lining material of the converter is made of silica bricks.

[0074] The potassium content in the obtained low-potassium fluorine-containing alumina is 0.046% (calculated as K2O), which is directly returned to the aluminum electrolysis system as raw material for aluminum electrolysis. The alumina consumption of the enterprise is 1925 kg / t-Al, and the fluorine-containing alumina treated by the above method is equivalent to 500 kg / t-Al. Before using the above method, the KF concentration in the electrolyte of the enterprise was 4.6%. After using the potassium-depleted fluorine-containing alumina for 6 months, the KF concentration in the electrolyte was 2.7%, and the current efficiency increased by 1.4%.

[0075] Example 5

[0076] In an aluminum electrolysis production line, the potassium content in the fresh alumina raw material is 0.039% (calculated as K2O). Using the fresh alumina as raw material, aluminum is produced by the cryolite-alumina molten salt electrolysis method. The solids in the soot generated during the electrolysis process are collected, and the potassium content in the solids is 0.42% (calculated as K2O).

[0077] The collected solid matter is added to the fluidized bed furnace. The treatment temperature is 900 °C, and the residence time of the solid matter in the reaction zone is 1 second. The KAlF4 in the solid matter is volatilized by high temperature to obtain low-potassium fluorine-containing alumina. The separated high-temperature flue gas is cooled to below 150 °C and collected by a bag-type dust collection system. The soot is used to extract KAlF4. The inner lining material of the fluidized bed furnace is made of quartz bricks.

[0078] The potassium content in the obtained low-potassium fluorine-containing alumina is 0.099% (calculated as K2O), which is directly returned to the aluminum electrolysis system as raw material for aluminum electrolysis. The alumina consumption of the enterprise is 1925 kg / t-Al, and the fluorine-containing alumina treated by the above method is equivalent to 100 kg / t-Al. Before using the above method, the KF concentration in the electrolyte of the enterprise was 4.8%. After using the potassium-depleted fluorine-containing alumina for 6 months, the KF concentration in the electrolyte was 2.7%, and the current efficiency increased by 1.1%.

[0079] The various embodiments of the present application may exist in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be construed as a rigid limitation on the scope of the present application; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and the individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and the individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, which applies regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0080] In this application, unless otherwise specified, the orientation terms such as "upper" and "lower" specifically refer to the drawing directions in the attached drawings. Additionally, in the description of this application's specification, the terms "include", "comprise", etc. mean "include but not limited to". Moreover, the term "include", "comprise" or any other variant thereof is intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements not only includes those elements but also includes other elements not expressly listed, or also includes elements inherent to such process, method, article or device. Without further limitation, the elements defined by the statement "comprising..." do not preclude the existence of additional identical elements in the process, method, article or device comprising the said elements. In this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. In this document, "and / or" describes the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist simultaneously, or B exists alone. For the association relationship of more than three associated objects described by "and / or", it means that these three associated objects can exist alone for any one of them, or any at least two of them exist simultaneously. For example, for A, and / or B, and / or C, it can mean that any one of A, B, and C exists alone, or any two of them exist simultaneously, or all three of them exist simultaneously. In this document, "at least one" means one or more, and "a plurality" means two or more. "At least one kind", "at least one item (piece) below" or similar expressions refer to any combination of these items, including any combination of single item (piece) or plural items (pieces). For example, "at least one item (piece) among a, b, or c", or, "at least one item (piece) among a, b, and c" can both mean: a, b, c, a - b (i.e., a and b), a - c, b - c, or a - b - c, where a, b, and c can be single or multiple respectively.

[0081] The above description is only the specific implementation manners of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application will not be limited to these embodiments shown herein, but rather will conform to the broadest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for reducing the potassium content in aluminum electrolyte, characterized in that, The method for reducing the potassium content in aluminum electrolyte comprises the following steps: Collect solid matter from the fumes generated during the aluminum electrolysis process in the aluminum electrolysis system; Treat the solid matter at a predetermined temperature to volatilize KAlF4 and obtain potassium-depleted fluorine-bearing alumina; Return the potassium-depleted fluorine-bearing alumina to the aluminum electrolysis system; The predetermined temperature is 600 - 1000 °C.

2. The method for reducing the potassium content in aluminum electrolyte according to claim 1, wherein The treatment of the solid matter at a predetermined temperature to volatilize KAlF4 is carried out in a kiln, and the kiln is one of a rotary furnace, a rotary kiln or a fluidized bed furnace.

3. The method for reducing the potassium content in aluminum electrolyte according to claim 2, wherein The lining material of the kiln is at least one of quartz brick, silica brick and high alumina brick.

4. The method for reducing the potassium content in aluminum electrolyte according to claim 1, characterized in that, The predetermined temperature is 700 - 900 °C.

5. The method for reducing the potassium content in aluminum electrolyte according to claim 1, characterized in that, When treating the solid matter at a predetermined temperature, the treatment time is from 1 second to 240 minutes.

6. The method for reducing the potassium content in aluminum electrolyte according to claim 1, wherein Based on the mass fraction of K2O, the mass fraction of K2O in the potassium-depleted fluorine-bearing alumina is not higher than 0.1%.

7. The method for reducing the potassium content in aluminum electrolyte according to claim 1, wherein The method further comprises the following steps: Collect the flue gas generated by the volatilization of KAlF4.

8. The method for reducing the potassium content in aluminum electrolyte according to claim 7, characterized in that, The flue gas generated by the volatilization of KAlF4 is collected by a bag dust collector.

9. The method for reducing the potassium content in aluminum electrolyte according to claim 8, characterized in that, The temperature of the flue gas is reduced to below 150 °C before entering the bag dust collector.

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