A method for producing vanadium concentrate and sodium oxalate in a bayer process

Abstract

The application relates to a method for producing vanadium concentrate and sodium oxalate from a Bayer process, comprising the following steps: providing a seed mother liquor in a Bayer production process, evaporating and concentrating the seed mother liquor to obtain a concentrated mother liquor; after cooling the concentrated mother liquor, adding vanadium salt seeds to the concentrated mother liquor for vanadium salt crystallization; performing solid-liquid separation on the concentrated mother liquor to obtain vanadium concentrate and a separated liquor; after heating the separated liquor to a predetermined temperature, increasing the caustic alkali concentration of the separated liquor; cooling the separated liquor with the increased caustic alkali concentration to perform sodium oxalate crystallization, and obtaining rich sodium oxalate crystals, wherein the caustic alkali concentration of the separated liquor is increased by at least one of the following two ways: evaporation and concentration or caustic alkali addition. The application can obtain high-grade vanadium concentrate and rich sodium oxalate crystals.

Description

Technical Field

[0001] This application relates to the aluminum industry, and more particularly to the recovery of vanadium and sodium oxalate in alumina production. Background Technology

[0002] During alumina production, impurities such as organic matter and vanadium in bauxite gradually accumulate within the system. When these impurities reach a certain concentration, they can adversely affect the production system. The enrichment of sodium oxalate and vanadium can lead to a decrease in decomposition rate, finer product particle size, and severe equipment scaling, all of which can disrupt normal production.

[0003] For the removal of sodium oxalate from the system, known methods include crystallization, solution combustion, seed washing, and precipitation. For the removal of vanadium impurities from the system, known methods include crystallization, adsorption extraction, and precipitation. For the Bayer process sodium aluminate solution system with high concentrations of both sodium oxalate and vanadium, it is necessary to remove both impurities simultaneously. Existing technologies that can simultaneously remove both impurities from the solution include precipitation and crystallization. Precipitation involves adding calcium oxide to the mother liquor, causing sodium oxalate and vanadium salts to precipitate and separate from the solution. The drawback of this method is that the addition of calcium oxide also causes sodium aluminate to precipitate, resulting in a significant loss of aluminum. Crystallization utilizes the characteristic that the equilibrium concentrations of sodium oxalate and vanadium salts in the solution decrease with increasing caustic alkali concentration and decreasing solution temperature. By increasing the caustic alkali concentration, decreasing the solution temperature, and adding inducing seed crystals, sodium oxalate and vanadium salts in the solution are crystallized out. When using the crystallization method, in order to avoid or reduce the loss of alumina, the Bayer process mother liquor is generally used as the target for impurity removal.

[0004] However, the simultaneous precipitation of both impurities inevitably results in the discharge of a large amount of complex-complex desalination filter cake. Given current environmental pressures, filter cake disposal presents a significant challenge for enterprises. Furthermore, both sodium oxalate and vanadium have industrial recovery value. Sodium oxalate, through acid treatment, can be used as a raw material for precipitating rare earth elements; vanadium, as an expensive metal, is often referred to as the "MSG of modern industry," and is an essential material for the development of modern industry and national defense technology. However, in sodium aluminate solutions with high concentrations of both sodium oxalate and vanadium, if the differences in the crystallization behavior of sodium oxalate and vanadium salts are not considered, and a simple one-step crystallization method is adopted, the purity of sodium oxalate and the grade of vanadium concentrate in the desalination filter cake will inevitably be low. This will increase the difficulty of recovering sodium oxalate and vanadium from the desalination filter cake, reduce the recovery rate, and significantly diminish the added value of the filter cake. Summary of the Invention

[0005] This application provides a method for producing vanadium concentrate and sodium oxalate from the Bayer process, in order to solve the technical problem of low grade sodium oxalate and vanadium salts during crystallization in the Bayer process.

[0006] This application provides a method for producing vanadium concentrate and sodium oxalate from the Bayer process, the method comprising the following steps:

[0007] Provide seed mother liquor from the Bayer process, and evaporate and concentrate the seed mother liquor to obtain concentrated mother liquor;

[0008] After the concentrated mother liquor is cooled, vanadium salt seed crystals are added to it to crystallize vanadium salts.

[0009] The concentrated mother liquor is subjected to solid-liquid separation to obtain vanadium concentrate and separation liquid;

[0010] After heating the separated liquid to a predetermined temperature, the concentration of caustic alkali in the separated liquid is increased;

[0011] The separated solution, after increasing the concentration of caustic alkali, was cooled and subjected to sodium oxalate crystallization to obtain sodium oxalate-rich crystals.

[0012] The increase in the caustic alkali concentration of the separated liquid is achieved by at least one of two methods: evaporation concentration or the addition of caustic alkali.

[0013] In some embodiments of this application, the concentration of vanadium in the seed mother liquor is not less than 0.3 g / L.

[0014] In some embodiments of this application, the concentration of sodium oxalate in the seed mother liquor is not less than 3.0 g / L.

[0015] In some embodiments of this application, the concentration of caustic alkali in the concentrated mother liquor is not higher than 210 g / L.

[0016] In some embodiments of this application, the concentrated mother liquor is cooled to 30-45°C.

[0017] In some embodiments of this application, the vanadium salt crystallization takes 3-5 hours.

[0018] In some embodiments of this application, the predetermined temperature is 80-100°C.

[0019] In some embodiments of this application, the caustic alkali concentration of the separating liquid is increased to 230-250 g / L.

[0020] In some embodiments of this application, the separation liquid after the concentration of caustic alkali is increased is cooled down to 35-60°C.

[0021] In some embodiments of this application, the sodium oxalate crystallization time is 8-15 hours.

[0022] The technical solutions provided in this application have the following advantages compared with the prior art:

[0023] The method for producing vanadium concentrate and sodium oxalate from the Bayer process provided in this application utilizes the different solubilities of vanadium salt and sodium oxalate at different caustic alkali concentrations. By controlling the concentration of the caustic alkali, vanadium salt and sodium oxalate are crystallized separately at different caustic alkali concentrations, resulting in high-grade vanadium concentrate and sodium oxalate-rich crystals. Specifically, the vanadium concentrate contains more than 20% V₂O₅ and less than 5% sodium oxalate; the sodium oxalate-rich crystals contain more than 60% sodium oxalate and less than 3% V₂O₅. Attached Figure Description

[0024] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic flow diagram of a method for producing vanadium concentrate and sodium oxalate from the Bayer process, provided as an embodiment of this application. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0028] Unless otherwise specified, the terminology used herein should be understood as having the meaning as commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any conflict, this specification shall prevail.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] The existing Bayer process has technical problems in the crystallization removal of sodium oxalate and vanadium salt, resulting in products with low grade.

[0031] The technical solution provided in this application is to solve the above-mentioned technical problems, and the general idea is as follows:

[0032] This application provides a method for producing vanadium concentrate and sodium oxalate from the Bayer process, the method comprising the following steps:

[0033] S1: Provide seed mother liquor in the Bayer process, and evaporate and concentrate the seed mother liquor to obtain concentrated mother liquor;

[0034] S2: After the concentrated mother liquor is cooled, vanadium salt seed crystals are added to it to crystallize vanadium salt;

[0035] S3: Perform solid-liquid separation on the concentrated mother liquor to obtain vanadium concentrate and separation liquid;

[0036] S4: After heating the separated liquid to a predetermined temperature, increase the caustic alkali concentration of the separated liquid;

[0037] S5: Cool the separated liquid after increasing the concentration of caustic alkali, and crystallize sodium oxalate to obtain sodium oxalate-rich crystals.

[0038] The increase in the caustic alkali concentration of the separated liquid is achieved by at least one of two methods: evaporation concentration or the addition of caustic alkali.

[0039] Those skilled in the art will understand that the purpose of evaporating and concentrating the seed mother liquor in step S1 is to increase the concentration of vanadium and caustic alkali, which is beneficial for vanadium salt crystallization.

[0040] Those skilled in the art will understand that, in step S2, vanadium salt crystallization can be carried out in a crystallization tank.

[0041] Those skilled in the art will understand that, in step S3, the solid-liquid separation of the concentrated mother liquor can be performed through the following steps:

[0042] S31: Pump the liquid in the crystallization tank into the settling tank;

[0043] S32: Plate and frame filter press is performed in the settling tank to obtain vanadium concentrate and separation liquid.

[0044] Sometimes overflow occurs in the settling tank. This overflow can be combined with the separated liquid for subsequent steps.

[0045] Those skilled in the art will understand that the evaporation and concentration or the addition of caustic alkali can be carried out in a mixing tank.

[0046] Those skilled in the art will understand that a conventional method of adding caustic alkali is to add caustic soda flakes.

[0047] Those skilled in the art will understand that the sodium oxalate crystallization can be carried out in a crystallization tank. It should be noted that, in this application, vanadium salt crystallization and sodium oxalate crystallization generally do not share the same crystallization tank.

[0048] In this application, after the separation liquid undergoes sodium oxalate crystallization, the solid and liquid are separated by plate and frame filtration, and the collected sodium oxalate-rich crystals are generally dark brown and spherical. The separated filtrate can be returned to the Bayer process for alumina production.

[0049] This application utilizes the different solubilities of vanadium salt and sodium oxalate at different caustic alkali concentrations. By controlling the concentration of the caustic alkali, vanadium salt and sodium oxalate can be crystallized separately at different caustic alkali concentrations, thereby obtaining high-grade vanadium concentrate and sodium oxalate-rich crystals. The vanadium concentrate contains more than 20% V2O5 and less than 5% sodium oxalate. The sodium oxalate-rich crystals contain more than 60% sodium oxalate and less than 3% V2O5.

[0050] In the process of vanadium salt crystallization, this application can also simultaneously remove impurities such as fluorine and phosphorus. After the separated filtrate is returned to the Bayer process for alumina production, the concentration of harmful impurities in the production process is reduced, the alumina production process is optimized, and the product quality of alumina can be effectively improved.

[0051] In some embodiments of this application, the concentration of vanadium in the seed mother liquor is not less than 0.3 g / L.

[0052] The beneficial effect of having a vanadium concentration of not less than 0.3 g / L is that it facilitates the precipitation of vanadium salts.

[0053] In some embodiments of this application, the concentration of sodium oxalate in the seed mother liquor is not less than 3.0 g / L.

[0054] The beneficial effect of having a sodium oxalate concentration of not less than 3.0 g / L is that it facilitates the precipitation of sodium oxalate.

[0055] In some embodiments of this application, the concentration of caustic alkali in the concentrated mother liquor is not higher than 210 g / L.

[0056] Limiting the concentration of caustic alkali in the concentrated mother liquor to the above range has the beneficial effect of minimizing the precipitation of sodium oxalate while precipitating vanadium salt.

[0057] In some embodiments of this application, the concentrated mother liquor is cooled to 30-45°C.

[0058] In some embodiments of this application, the vanadium salt crystallization takes 3-5 hours.

[0059] In actual production, vanadium salts are generally completely precipitated within 3-5 hours.

[0060] In some embodiments of this application, the predetermined temperature is 80-100°C.

[0061] In some embodiments of this application, the caustic alkali concentration of the separating liquid is increased to 230-250 g / L.

[0062] The caustic alkali at the above concentration can effectively precipitate sodium oxalate, and after the sodium oxalate-rich crystals are collected, the separated filtrate can be directly returned to the Bayer process for alumina production.

[0063] In some embodiments of this application, the separation liquid after the concentration of caustic alkali is increased is cooled down to 35-60°C.

[0064] In some embodiments of this application, the sodium oxalate crystallization time is 8-15 hours.

[0065] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0066] Example 1

[0067] The Bayer process seed mother liquor is provided, which is then evaporated and concentrated to obtain a concentrated mother liquor. The concentrated mother liquor contains a caustic alkali concentration of 182 g / L and a vanadium concentration of 0.46 g / L.

[0068] After heat exchange, the concentrated mother liquor is cooled to 30°C and sent to the first crystallization tank for crystallization for 3 hours. Then it is sent to the first settling tank. The vanadium concentration in the overflow of the first settling tank is 0.22 g / L. The vanadium concentrate obtained by bottom filtration of the first settling tank has a V2O5 content of 24.1% and a sodium oxalate content of 3.9%.

[0069] The solutions obtained from the overflow and underflow filtration of the settling tank are combined to obtain a separated liquid. The separated liquid is heated to 100°C, and caustic soda flakes are added to increase the caustic soda concentration in the separated liquid to 250 g / L. At this time, the sodium oxalate concentration in the separated liquid is 5.3 g / L. The separated liquid after adding caustic soda flakes is cooled to 60°C, and the separated liquid is crystallized in the second crystallization tank for 15 hours. Then it is sent to the second settling tank. The sodium oxalate concentration in the overflow of the second settling tank is 2.0 g / L. The sodium oxalate-rich crystals obtained from the underflow filtration of the second settling tank have a sodium oxalate content of 77% and a V2O5 content of 1.5%.

[0070] Example 2

[0071] The Bayer process seed liquor is provided, and after evaporation and concentration, a concentrated mother liquor is obtained. The concentration of caustic alkali in the concentrated mother liquor is 208 g / L, and the concentration of vanadium is 0.61 g / L.

[0072] After heat exchange, the concentrated mother liquor is cooled to 45°C and sent to the first crystallization tank for crystallization for 5 hours. Then it is sent to the first settling tank. The vanadium concentration in the overflow of the first settling tank is 0.23 g / L. The vanadium concentrate obtained by bottom filtration of the first settling tank has a V2O5 content of 21.6% and a sodium oxalate content of 1.8%.

[0073] The solutions obtained from the overflow and underflow filtration of the settling tank are combined to obtain a separated liquid. The separated liquid is heated to 100°C, and caustic soda flakes are added to increase the caustic soda concentration in the separated liquid to 250 g / L. At this time, the sodium oxalate concentration in the separated liquid is 5.0 g / L. The separated liquid after adding caustic soda flakes is cooled to 35°C, and the separated liquid is crystallized in the second crystallization tank for 10 hours. Then it is sent to the second settling tank. The sodium oxalate concentration in the overflow of the second settling tank is 1.7 g / L, and the sodium oxalate-rich crystals obtained from the underflow filtration of the second settling tank have a sodium oxalate content of 77% and a V2O5 content of 2.8%.

[0074] Example 3

[0075] The Bayer process seed mother liquor is provided, which is then evaporated and concentrated to obtain a concentrated mother liquor. The concentrated mother liquor contains a caustic alkali concentration of 192 g / L and a vanadium concentration of 0.6 g / L.

[0076] After heat exchange, the concentrated mother liquor is cooled to 45°C and sent to the first crystallization tank for crystallization for 5 hours. Then it is sent to the first settling tank. The vanadium concentration in the overflow of the first settling tank is 0.25 g / L. The vanadium concentrate obtained by bottom filtration of the first settling tank has a V2O5 content of 22.3% and a sodium oxalate content of 1.3%.

[0077] The solutions obtained from the overflow and underflow filtration of the settling tank are combined to obtain a separated liquid. The separated liquid is heated to 80°C, and caustic soda flakes are added to increase the caustic soda concentration in the separated liquid to 230 g / L. At this time, the sodium oxalate concentration in the separated liquid is 6 g / L. The separated liquid after adding caustic soda flakes is cooled to 45°C, and the separated liquid is crystallized in the second crystallization tank for 15 hours. Then it is sent to the second settling tank. The sodium oxalate concentration in the overflow of the second settling tank is 1.8 g / L, and the sodium oxalate-rich crystals obtained from the underflow filtration of the second settling tank have a sodium oxalate content of 72% and a V2O5 content of 2.3%.

[0078] Example 4

[0079] The Bayer process seed mother liquor is provided, which is then evaporated and concentrated to obtain a concentrated mother liquor. The concentrated mother liquor contains a caustic alkali concentration of 206 g / L and a vanadium concentration of 0.58 g / L.

[0080] After heat exchange, the concentrated mother liquor is cooled to 30°C and sent to the first crystallization tank for crystallization for 3 hours. Then it is sent to the first settling tank. The vanadium concentration in the overflow of the first settling tank is 0.22 g / L. The vanadium concentrate obtained by bottom filtration of the first settling tank has a V2O5 content of 20.8% and a sodium oxalate content of 4.9%.

[0081] The solutions obtained from the overflow and underflow filtration of the settling tank are combined to obtain a separated liquid. The separated liquid is heated to 80°C, and caustic soda flakes are added to increase the caustic soda concentration in the separated liquid to 240 g / L. At this time, the sodium oxalate concentration in the separated liquid is 5.4 g / L. The separated liquid after adding caustic soda flakes is cooled to 35°C, and the separated liquid is crystallized in the second crystallization tank for 8 hours. Then it is sent to the second settling tank. The sodium oxalate concentration in the overflow of the second settling tank is 2.0 g / L. The sodium oxalate-rich crystals obtained from the underflow filtration of the second settling tank have a sodium oxalate content of 68% and a V2O5 content of 2.1%.

[0082] Example 5

[0083] The Bayer process seed liquor is provided, which is then evaporated and concentrated to obtain a concentrated mother liquor. The concentrated mother liquor contains a caustic alkali concentration of 194 g / L and a vanadium concentration of 0.64 g / L.

[0084] After heat exchange, the concentrated mother liquor is cooled to 45°C and sent to the first crystallization tank for crystallization for 5 hours. Then it is sent to the first settling tank. The vanadium concentration in the overflow of the first settling tank is 0.29 g / L. The vanadium concentrate obtained by bottom filtration of the first settling tank has a V2O5 content of 21.5% and a sodium oxalate content of 3.8%.

[0085] The solutions obtained from the overflow and underflow filtration of the settling tank are combined to obtain a separated liquid. The separated liquid is evaporated and concentrated until the caustic alkali concentration is 232 g / L, at which point the sodium oxalate concentration in the separated liquid is 4.7 g / L. The evaporated and concentrated separated liquid is cooled to 40°C and crystallized in the second crystallization tank for 8 hours. Then it is sent to the second settling tank. The sodium oxalate concentration in the overflow of the second settling tank is 2.7 g / L. The sodium oxalate-rich crystals obtained from the underflow filtration of the second settling tank have a sodium oxalate content of 61% and a V2O5 content of 1.8%.

[0086] Example 6

[0087] The Bayer process seed mother liquor is provided, which is then evaporated and concentrated to obtain a concentrated mother liquor. The concentrated mother liquor contains a caustic alkali concentration of 197 g / L and a vanadium concentration of 0.62 g / L.

[0088] After heat exchange, the concentrated mother liquor is cooled to 35°C and sent to the first crystallization tank for crystallization for 3 hours. Then it is sent to the first settling tank. The vanadium concentration in the overflow of the first settling tank is 0.20 g / L. The vanadium concentrate obtained by bottom filtration of the first settling tank has a V2O5 content of 21.2% and a sodium oxalate content of 3.1%.

[0089] The solutions obtained from the overflow and underflow filtration of the settling tank are combined to obtain a separated liquid. The separated liquid is evaporated and concentrated until the caustic alkali concentration is 249 g / L, at which point the sodium oxalate concentration in the separated liquid is 5.3 g / L. The evaporated and concentrated separated liquid is cooled to 50°C and crystallized in the second crystallization tank for 8 hours. Then it is sent to the second settling tank. The sodium oxalate concentration in the overflow of the second settling tank is 3.1 g / L. The sodium oxalate-rich crystals obtained from the underflow filtration of the second settling tank have a sodium oxalate content of 66% and a V2O5 content of 1.5%.

[0090] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed 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 single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0091] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, the terms "comprising," "including," etc., mean "including but not limited to." Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. For associations involving three or more related objects described using "and / or", it indicates that any one of the three related objects can exist alone, or at least two of them can 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 "more than one" means two or more. "At least one", "at least one of the following", or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or multiple.

[0092] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A process for producing vanadium concentrate and sodium oxalate from a Bayer process, characterized by, The method for producing vanadium concentrate and sodium oxalate from a Bayer process flow comprises the following steps: providing a seed mother liquor in a Bayer process production flow, and evaporating and concentrating the seed mother liquor to obtain a concentrated mother liquor; after cooling the concentrated mother liquor, adding vanadium salt seeds to the concentrated mother liquor to crystallize vanadium salt; performing solid-liquid separation on the concentrated mother liquor to obtain vanadium concentrate and a separated liquor; after heating the separated liquor to a predetermined temperature, increasing the caustic alkali concentration of the separated liquor to 230-250 g / L; cooling the separated liquor with increased caustic alkali concentration to 35-60 ℃ to crystallize sodium oxalate, and obtaining rich sodium oxalate crystals, wherein the caustic alkali concentration of the separated liquor is increased by at least one of evaporation and concentration or by adding caustic alkali; in the seed mother liquor, the concentration of vanadium is not less than 0.3 g / L, and the concentration of sodium oxalate is not less than 3.0 g / L; in the concentrated mother liquor, the concentration of caustic alkali is not higher than 210 g / L; and the concentrated mother liquor is cooled to 30-45 ℃; the V2O5 content in the vanadium concentrate is higher than 20%, and the sodium oxalate content is lower than 5%; and in the rich sodium oxalate crystals, the sodium oxalate content is higher than 60%, and the V2O5 content is lower than 3%; the duration of vanadium salt crystallization is 3-5 h, and the duration of sodium oxalate crystallization is 8-15 h.

2. The process for producing vanadium concentrate and sodium oxalate from the Bayer process according to claim 1, characterized in that, the predetermined temperature is 80-100 ℃.

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