Method for reducing manganese content in ammonium polyvanadate prepared from calcified vanadium liquid

Abstract

The invention discloses a method for reducing the manganese content in ammonium polyvanadate prepared from a calcified vanadium liquid, after ammonium polyvanadate slurry is obtained through acidic ammonium salt vanadium precipitation, the method sequentially comprises the following washing steps: S1, rough washing: conveying the ammonium polyvanadate slurry obtained through vanadium precipitation to a belt type vacuum filter, and carrying out primary washing to obtain a primary filter cake; s2, pulping: transferring the primary filter cake into a pulping tank, adding a washing solution, and mechanically stirring and pulping to form a uniform suspension; and S3, fine washing: carrying out secondary washing on the suspension by using a plate-and-frame filter press to obtain an ammonium polyvanadate filter cake. The problem of deep removal of the manganese impurities in the APV is solved in a targeted manner by adopting a combined process of rough washing by the belt filter, pulping dispersion and fine washing by the plate-and-frame filter press, and the method has the advantages of high pertinence and easiness in implementation.

Description

Technical Field

[0001] This invention relates to the field of vanadium extraction and purification technology in hydrometallurgy, and particularly to a method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution. Background Technology

[0002] Ammonium polyvanadate (APV) is a key intermediate in the production of high-purity vanadium pentoxide (V₂O₅), vanadium trioxide (V₂O₃), and various vanadium alloys. Its purity directly determines the grade and value of downstream products. Calcination roasting-acid leaching-ammonium salt precipitation is currently one of the mainstream processes for treating vanadium-bearing coal shale or vanadium slag. However, manganese, which coexists in the ore, partially enters the vanadium solution during roasting and leaching, becoming one of the main metallic impurities.

[0003] In the process of vanadium precipitation by acidic ammonium salts, manganese (usually in the form of Mn) 2+ Although it does not form ammonium salt precipitates with vanadium (in its physical form), it can be mixed into APV products through the following pathways: 1. Surface adsorption: Mn 2+ Adsorbed by the surface of negatively charged APV precipitate particles; 2. Mother liquor entrainment: During the filtration process, high concentrations of Mn are present. 2+ The mother liquor is trapped in the gaps between the APV precipitate and inside the filter cake.

[0004] Traditional APV production processes typically employ a single plate and frame filter press for filtration and washing. While plate and frame filter presses offer high filtration pressure and produce relatively dry filter cakes, their washing method has inherent drawbacks: the washing liquid tends to form "channels" within the filter cake, preferentially flowing through channels with lower resistance, making it difficult to effectively displace and diffuse the mother liquor trapped within the filter cake, especially between particles. This results in low manganese impurity removal rates, with APV products often containing manganese content of 200-500 ppm or even higher, failing to meet the requirements for preparing high-purity V₂O₅ (such as for use in vanadium battery electrolytes).

[0005] In the existing technology, the methods for reducing the impurity content of APV are mostly focused on optimizing the purification of the pre-precipitation solution (such as solvent extraction, ion exchange) or the post-treatment of APV (such as pulping purification, resolution purification).

[0006] For example, Chinese patent application number 201910476311.8 discloses a method for preparing high-purity ammonium polyvanadate. The main method involves adding ferrous sulfate and silicon precipitant to remove impurities before precipitating ammonium polyvanadate, and then using aminophosphate resin and imine diacetic acid chelating resin for two adsorption processes to obtain a pure solution after impurity removal for vanadium precipitation to prepare high-purity ammonium polyvanadate. However, the process is long, reagent consumption is high, and the cost is high.

[0007] For example, Chinese patent application number 202411031283.6 describes a method for purifying ammonium vanadate by pulping with hydrochloric acid and sulfuric acid solutions respectively, thereby improving the purity of ammonium vanadate and preparing high-purity vanadium pentoxide. However, this method suffers from problems such as high reagent consumption and high cost.

[0008] For example, Chinese patent application number 202210945743.0 discloses a method for re-dissolving ammonium polyvanadate with ammonium carbonate or ammonium bicarbonate and then precipitating ammonium metavanadate to separate impurity elements and thus prepare high-purity vanadium pentoxide products. However, the process is long and the cost is high.

[0009] Therefore, developing an efficient, economical, and easily industrially implementable APV deep washing technology is of great significance for improving the quality and added value of vanadium products. Summary of the Invention

[0010] This invention addresses the problem of deep removal of manganese impurities from APV by employing a combined process of "coarse washing with belt filter + pulping and dispersion + fine washing with plate and frame filter press". It has the advantages of being highly targeted and easy to implement.

[0011] According to one aspect of the present invention, a method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution is provided, which includes the following washing steps sequentially after obtaining ammonium polyvanadate slurry by vanadium precipitation with acidic ammonium salt: S1: Coarse washing: The ammonium polyvanadate slurry obtained from vanadium precipitation is conveyed to a belt vacuum filter and washed once to obtain a filter cake. S2: Pulping: Transfer the primary filter cake to a pulping tank, add washing liquid and mechanically stir and pulp to form a uniform suspension; S3: Fine washing: The suspension is washed a second time using a plate and frame filter press to obtain ammonium polyvanadate filter cake.

[0012] According to one embodiment of the present invention, the washing method of the first wash is countercurrent washing, and the washing water of the first wash includes secondary washing liquid and / or industrial water generated in subsequent steps.

[0013] According to one embodiment of the present invention, the washing pressure for the secondary washing is 0.4~1.2 MPa, and industrial water is used for washing until the effluent is nearly neutral and its conductivity is significantly reduced.

[0014] According to one embodiment of the present invention, the washing liquid includes one of deionized water, softened water, or an ammonium salt solution with a concentration of 0.1-5%.

[0015] According to one embodiment of the present invention, the acidic ammonium salt includes one or more of ammonium sulfate, ammonium chloride, or ammonium nitrate.

[0016] According to one embodiment of the present invention, the solid-liquid mass ratio of mechanical stirring and pulping is 1:1 to 10.

[0017] According to one embodiment of the present invention, the solid-liquid mass ratio of mechanical stirring and pulping is 1:2~5.

[0018] According to one embodiment of the present invention, the mechanical stirring and pulping time is 10-20 minutes.

[0019] According to one embodiment of the present invention, the manganese content in the ammonium polyvanadate filter cake is less than 50 ppm.

[0020] According to one embodiment of the present invention, the moisture content of the primary filter cake is 25-35%.

[0021] According to an embodiment of the present invention, a method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution uses a combined process of "coarse washing with belt filter + pulping and dispersion + fine washing with plate and frame filter press" to specifically address the problem of deep removal of manganese impurities in APV, which has the advantages of being highly targeted and easy to implement. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some implementation examples of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A process flow diagram of a method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to an exemplary embodiment of the present invention is shown. Detailed Implementation

[0024] The following detailed description of the embodiments is intended to exemplify the principles of the present invention, but should not be construed as limiting the scope of the invention. The present invention can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

[0025] These embodiments are provided to make this disclosure thorough and complete, and to fully express the scope of the invention to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values ​​set forth in these embodiments should be interpreted as merely exemplary and not as limiting.

[0026] It should be noted that, in the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationships, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0027] It should also be noted that, in the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention depending on the specific circumstances. When a specific device is described as being located between a first device and a second device, an intermediary device may or may not be present between the specific device and the first or second device.

[0028] All terms used in this invention have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.

[0029] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0030] like Figure 1 As shown, this invention provides a method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution. After obtaining ammonium polyvanadate slurry through vanadium precipitation with acidic ammonium salts, the method includes the following washing steps in sequence: S1: Coarse washing: The ammonium polyvanadate slurry obtained from vanadium precipitation is conveyed to a belt vacuum filter and washed once to obtain a filter cake. S2: Pulping: Transfer the primary filter cake to a pulping tank, add washing liquid and mechanically stir and pulp to form a uniform suspension; S3: Fine washing: The suspension is washed a second time using a plate and frame filter press to obtain ammonium polyvanadate filter cake.

[0031] In the method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to an embodiment of the present invention, the problem of deep removal of manganese impurities in APV is specifically solved by adopting a combined process of "coarse washing with belt filter + pulping and dispersion + fine washing with plate and frame filter press". This method has the advantages of being highly targeted and easy to implement.

[0032] In some specific embodiments, the washing method of the first wash is countercurrent washing, and the washing water of the first wash includes secondary washing liquid and / or industrial water generated in subsequent steps.

[0033] In this application, industrial water includes one of municipal tap water, distilled water, deionized water, and purified water. Purified water can be obtained by treating municipal tap water through activated carbon filtration and ion exchange resin.

[0034] In step S1, taking advantage of the continuous operation, high washing efficiency, and countercurrent washing capability of the belt vacuum filter, the ammonium polyvanadate (APV) slurry is first rapidly dehydrated, and about 70-80% of the entrained mother liquor and most of the manganese impurities adsorbed on the surface are washed away with a small amount of washing water (such as the dilute washing water in the subsequent process). This step can quickly remove most of the impurity load.

[0035] In step S2, the APV filter cake from the belt vacuum filter is fed into a slurry tank equipped with a stirring device, and fresh washing water (e.g., deionized water) is added for vigorous slurrying. The key to this step is to completely break up and disperse the compacted filter cake, allowing the mother liquor containing a high concentration of manganese, which was originally trapped inside the filter cake, to be fully released into the washing water. At the same time, it allows the manganese ions adsorbed on the surface of the APV particles to have a longer diffusion path and desorption time, achieving a re-equilibrium of the solid and liquid phases.

[0036] Based on the above embodiments, the washing pressure for the second washing is 0.4~1.2 MPa, and industrial water is used for washing until the pH value of the effluent is close to neutral (e.g., pH value is 6-8).

[0037] In some specific embodiments, the washing solution includes one of deionized water, softened water, or an ammonium salt solution with a concentration (mass concentration) of 0.1-5%.

[0038] In step S3, the homogeneous slurry after beating is pumped into a plate and frame filter press for filtration. During this stage, due to the homogeneity of the slurry, the high-pressure filtration advantage of the plate and frame filter press is fully utilized, resulting in a uniformly structured filter cake. When washing with clean water or deionized water, the washing liquid can evenly pass through the entire filter cake layer, efficiently displacing the manganese-containing liquid in the beating slurry and achieving deep purification.

[0039] Based on the above embodiments, the acidic ammonium salt includes one or more of ammonium sulfate, ammonium chloride, or ammonium nitrate.

[0040] In some specific embodiments, the solid-liquid mass ratio of mechanical stirring and pulping is 1:1 to 10.

[0041] Based on the above embodiments, the solid-liquid mass ratio of mechanical stirring and pulping is 1:2~5.

[0042] In some specific embodiments, the mechanical stirring and pulping time is 10-20 minutes.

[0043] Based on the above embodiments, the manganese content in the ammonium polyvanadate filter cake is less than 50 ppm.

[0044] Based on the above embodiments, the moisture content of the primary filter cake is 25-35%.

[0045] The present application will be further described below through specific embodiments.

[0046] Example 1 Coarse washing: The slurry is pumped into a belt vacuum filter. Countercurrent washing is used, with secondary wash water from the subsequent plate and frame filter press as the washing liquid. The filtration speed is controlled to obtain a primary filter cake with a moisture content of approximately 30%.

[0047] Pulping: Put the filter cake into the pulping tank, add deionized water with a mass of 2 times the filter cake (solid-liquid ratio 1:2), and stir and pulp for 10 minutes.

[0048] Fine washing: The pulped material is pumped into a plate and frame filter press, compacted, and then washed with deionized water at a pressure of 0.8 MPa until the pH of the effluent is 6.5. The material is then discharged to obtain a pure APV filter cake.

[0049] Results: Sampling and analysis of the final APV product showed that the manganese content was reduced to 45 ppm.

[0050] Example 2 Steps: Basically the same as in Example 1, except for the pulping conditions: the pulping solution is changed to a 1% ammonium sulfate solution, the solid-liquid ratio is 1:3, and the pulping time is 15 minutes.

[0051] Result: The manganese content in the final APV product was reduced to 38 ppm. Using a dilute ammonium salt solution helped suppress the small amount of dissolution loss of APV.

[0052] Comparative Example 1 (Traditional single-stage plate and frame filter press washing) Procedure: The same APV slurry was directly filtered and washed in one go using a plate and frame filter press. Washing was performed using clean water equivalent to the total water volume used in Example 1.

[0053] Results: Obvious channeling was visible during the washing process. After washing, the sample analysis showed that the manganese content in the APV product was 280 ppm, indicating a limited removal effect.

[0054] Comparative Example 2 (only belt filter washing was used, without pulping step) Steps: The APV slurry is subjected to three-stage countercurrent washing on a belt filter with an additional washing stage and a total water consumption equivalent to that in Example 1.

[0055] Results: Since the filter cake could not be completely broken down and reorganized on the belt conveyor, it was difficult to completely remove internal impurities. The final product had a manganese content of 120 ppm, which was better than Comparative Example 1, but much higher than the embodiment of the present invention.

[0056] Comparative Example 3 (using only pulping and plate and frame filter press, without belt washing) Steps: The APV slurry is first thickened by ordinary concentration, and the underflow is directly pumped into the pulping tank. The subsequent steps are the same as in Example 1.

[0057] Results: Due to the high liquid content and large impurity load of the material entering the pulping tank, the pulping effect was affected, and the throughput decreased. The final product had a manganese content of 80 ppm, which was better than Comparative Examples 1 and 2, but still not as good as the complete three-stage process of this invention.

[0058] Conclusion: The comparison between the examples and the comparative examples fully demonstrates that the three-stage enhanced washing process of "belt coarse washing - pulping and dispersion - plate and frame fine washing" provided by the present invention has a significant advantage in synergistic effect in the deep removal of manganese impurities in APV, with remarkable technical effects and extremely high industrial application value.

[0059] After implementation, this invention has at least the following beneficial effects: 1. Significantly reduced manganese content: Through the synergistic effect of three-stage washing, especially the key step of "pulping", the mass transfer barrier of traditional single-stage pressure filtration washing is completely broken, which greatly improves the manganese removal rate. The manganese content in APV products can be stably reduced to below 50ppm. 2. High washing efficiency and relatively optimized water consumption: The belt conveyor has high efficiency in coarse washing, and the fine washing after pulping has a much higher washing efficiency than washing the original compacted filter cake due to the uniformity of the filter cake. The overall water consumption may be lower than that of multiple plate and frame washings to achieve the same effect. 3. Improved product purity and significant economic benefits: High-purity APV lays the foundation for the production of high-end V2O5 products, significantly improving the market competitiveness and economic benefits of the products. 4. Smooth process integration and easy industrialization: All equipment used are conventional solid-liquid separation equipment, with reasonable combination, making it easy to carry out technical transformation and implementation on existing production lines.

[0060] This invention can reduce the manganese content of ammonium polyvanadate products prepared by calcium-based vanadium liquid ammonium salt precipitation, thereby improving product quality. It can be promoted and applied to production lines to enhance product quality and broaden the application fields of the products. Moreover, the production line can meet the conditions required for technical implementation through some process adjustments and equipment upgrades, and has good prospects for industrial application. It can be further promoted to other vanadium extraction enterprises at home and abroad.

[0061] The above are exemplary embodiments disclosed in this invention. The order of the disclosed embodiments is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. However, it should be noted that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the disclosed embodiments of this invention (including the claims) is limited to these examples. Various changes and modifications can be made without departing from the scope defined by the claims. The functions, steps, and / or actions of the methods according to the disclosed embodiments described herein do not need to be performed in any particular order. Furthermore, although the elements disclosed in the embodiments of this invention may be described or claimed individually, they may be understood as multiple unless explicitly limited to a singular.

[0062] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention (including the claims) is limited to these examples. Within the framework of the invention, technical features of the above embodiments or different embodiments can be combined, and many other variations of the different aspects of the invention as described above exist, which are not provided in the details for the sake of brevity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the invention should be included within the protection scope of the invention.

Claims

1. A method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution, characterized in that, After obtaining ammonium polyvanadate slurry by vanadium precipitation with acidic ammonium salts, the following washing steps are performed sequentially: S1: Coarse washing: The ammonium polyvanadate slurry obtained from vanadium precipitation is conveyed to a belt vacuum filter and washed once to obtain a filter cake. S2: Pulping: The primary filter cake is transferred to a pulping tank, washing liquid is added and mechanically stirred and pulped to form a uniform suspension; S3: Fine washing: The suspension is washed a second time using a plate and frame filter press to obtain ammonium polyvanadate filter cake.

2. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The washing method of the first wash is countercurrent washing, and the washing water of the first wash includes secondary washing liquid and / or industrial water generated in subsequent steps.

3. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The secondary washing is performed at a pressure of 0.4~1.2 MPa, using industrial water, until the effluent is nearly neutral and its conductivity is significantly reduced.

4. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, wherein the washing solution comprises one of deionized water, softened water, or an ammonium salt solution with a concentration of 0.1-5%.

5. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The acidic ammonium salt includes one or more of ammonium sulfate, ammonium chloride, or ammonium nitrate.

6. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The solid-liquid mass ratio of the mechanically stirred pulp is 1:1~10.

7. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 6, characterized in that, The solid-liquid mass ratio of the mechanically stirred pulp is 1:2~5.

8. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The mechanical stirring and pulping time is 10-20 minutes.

9. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The manganese content in the ammonium polyvanadate filter cake is less than 50 ppm.

10. The method for reducing the manganese content in ammonium polyvanadate prepared from vanadium calcification solution according to claim 1, characterized in that, The moisture content of the primary filter cake is 25-35%.

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