Method for recovering ammonium polyvanadate in vanadium precipitation wastewater

Abstract

The invention discloses a method for recovering ammonium polyvanadate in vanadium precipitation wastewater, which comprises the following steps: carrying out sedimentation treatment on the vanadium precipitation wastewater generated in the process of preparing the ammonium polyvanadate to obtain first slurry containing the ammonium polyvanadate; performing flocculation and cleaning on the first slurry to obtain second slurry containing ammonium polyvanadate; and filtering the second slurry to obtain a filter cake containing ammonium polyvanadate. According to the scheme, the efficiency of recovering ammonium polyvanadate from the vanadium precipitation wastewater is improved, and the quality of the recovered ammonium polyvanadate is improved.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for recovering ammonium polyvanadate in vanadium precipitation wastewater. Background Art

[0002] Amine polyvanadate is the main intermediate product in the production process of vanadium products and is usually extracted from vanadium slag by acidic ammonium salt precipitation.

[0003] In the process of extracting ammonium polyvanadate from vanadium slag by acidic ammonium salt precipitation method, a large amount of vanadium precipitation wastewater is generated, which contains a large amount of fine particles of ammonium polyvanadate. The process of recovering ammonium polyvanadate from vanadium precipitation wastewater is relatively difficult, and there are problems such as low recovery rate, poor quality of recovered ammonium polyvanadate, increased impurities, easy clogging of filter cloth used to filter ammonium polyvanadate, increased wastewater generation and auxiliary material consumption. Summary of the invention

[0004] In view of this, the present invention proposes a method for recovering ammonium polyvanadate from vanadium precipitation wastewater, which solves the problems of low recovery rate, poor quality of recovered ammonium polyvanadate, increased impurities, easy clogging of filter cloth used for filtering ammonium polyvanadate, increased wastewater generation and auxiliary material consumption in the process of recovering ammonium polyvanadate from vanadium precipitation wastewater.

[0005] On the one hand, an embodiment of the present invention provides a method for recovering ammonium polyvanadate in vanadium precipitation wastewater, comprising: The vanadium precipitation wastewater generated in the process of preparing ammonium polyvanadate is subjected to sedimentation treatment to obtain a first slurry containing ammonium polyvanadate; flocculating and washing the first slurry to obtain a second slurry containing ammonium polyvanadate; The second slurry is filtered to obtain a filter cake containing ammonium polyvanadate.

[0006] In some embodiments, flocculating and washing the first slurry to obtain a second slurry containing ammonium polyvanadate comprises: adding a flocculant to the first slurry to obtain a flocculated slurry; The flocculated slurry was washed with water to obtain a second slurry.

[0007] In some embodiments, washing the flocculated slurry with water to obtain a second slurry comprises: adding a certain amount of water to the flocculated slurry, and stirring the flocculated slurry to which the water has been added; In response to the stirring time reaching the first specified time, stopping the stirring and allowing the flocculated slurry to which water has been added to stand; In response to the standing time reaching a second prescribed time, a supernatant is separated from the flocculated slurry to which water has been added to obtain a second slurry.

[0008] In some embodiments, the flocculant comprises anionic polyacrylamide.

[0009] In some embodiments, filtering the second slurry to obtain a filter cake containing ammonium polyvanadate comprises: Adding a skeleton agent and water to the second slurry in sequence to obtain a third slurry; The third slurry is filtered to obtain a filter cake containing ammonium polyvanadate.

[0010] In some embodiments, the framework agent contains sawdust.

[0011] In some embodiments, the third slurry is filtered to obtain a filter cake composed of ammonium polyvanadate, comprising: The third slurry is filtered through a filter bag covered with a filter membrane to obtain a filter cake containing ammonium polyvanadate.

[0012] In some embodiments, before filtering the second slurry to obtain a filter cake composed of ammonium polyvanadate, the method further comprises: A filter membrane covering the surface of the filter bag is formed on the surface of the filter bag close to the slurry by the filter aid.

[0013] In some embodiments, the filter aid contains lignocellulose.

[0014] In some embodiments, the method further comprises: The filter cake containing ammonium polyvanadate is subjected to a ball-forming treatment to obtain material balls; The pellets are melted to obtain vanadium-containing compounds.

[0015] The present invention has at least the following beneficial effects: The present invention provides a method for recovering ammonium polyvanadate in vanadium precipitation wastewater. The method for recovering ammonium polyvanadate in vanadium precipitation wastewater provided by the present invention can obtain a first slurry containing ammonium polyvanadate by subjecting the vanadium precipitation wastewater to sedimentation treatment. The first slurry is subjected to flocculation treatment by a flocculant, so that the ammonium polyvanadate in the first slurry can be quickly precipitated, thereby improving the recovery efficiency. By washing the flocculated slurry obtained after the flocculation treatment, impurities in the flocculated slurry can be removed to obtain a second slurry with higher quality. The second slurry with higher purity can be filtered to obtain a filter cake containing ammonium polyvanadate. Thus, the efficiency of recovering ammonium polyvanadate in vanadium precipitation wastewater is improved, and the quality of the recovered ammonium polyvanadate is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other embodiments can be obtained based on these drawings without paying creative work.

[0017] Figure 1 A flow chart of a method for recovering ammonium polyvanadate from vanadium precipitation wastewater provided in an embodiment of the present invention; Figure 2 A flow chart of a method for recovering ammonium polyvanadate from vanadium precipitation wastewater provided in an embodiment of the present invention; Figure 3 A flow chart of a method for recovering ammonium polyvanadate from vanadium precipitation wastewater provided in an embodiment of the present invention; Figure 4 A schematic structural diagram of a wastewater recovery system for recovering ammonium polyvanadate from vanadium precipitation wastewater provided in an embodiment of the present invention.

[0018] [Description of Reference Numerals] 100: sedimentation unit; 1: rake; 2: material distribution barrel; 3: overflow weir; 4: sedimentation tank; 5: rake teeth; 6: first slurry valve; 7: first pump; 200: flocculation and cleaning unit; 8: first liquid level meter; 9: first agitator; 10: first flocculant valve; 11: first water valve; 12: flow measuring valve; 13: second slurry valve; 14: washing tank; 15: second pump; 300: slurry mixing unit; 16: second liquid level gauge; 17: second agitator; 18: feeding port; 19: second water valve; 20: third slurry valve; 21: slurry mixing tank; 22: third pump; 400: filtration unit; 23: slurry valve; 24: suction filtration tank; 25: steam valve; 26: vacuum valve; 27: drain valve; 500: granulation unit; 28: silo; 29: first conveyor belt; 30: granulator; 31: second conveyor belt. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in combination with specific embodiments and with reference to the accompanying drawings.

[0020] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0021] In the process of extracting ammonium polyvanadate from vanadium slag by acidic ammonium salt precipitation method, a large amount of vanadium precipitation wastewater is generated, which contains a large amount of fine particles of ammonium polyvanadate. The process of recovering ammonium polyvanadate from vanadium precipitation wastewater is relatively difficult, and there are problems such as low recovery rate, poor quality of recovered ammonium polyvanadate, increased impurities, easy clogging of filter cloth used to filter ammonium polyvanadate, increased wastewater generation and auxiliary material consumption.

[0022] In the related art, a method for extracting polyvanadate from vanadium slag by acidic ammonium salt precipitation is as follows: after sodium calcination of vanadium slag, leaching and impurity removal are performed to obtain a clear and transparent vanadium-containing leachate, concentrated sulfuric acid is added to the vanadium-containing leachate to adjust the pH value of the solution to 6.5-7.0, and then a certain amount of ammonium sulfate is added. After uniform mixing, it is transported to a vanadium precipitation tank for heating, stirring, and then concentrated sulfuric acid is added to adjust the pH value to 2.0-2.3 for vanadium precipitation. The obtained ammonium polyvanadate (APV) is then subjected to solid-liquid separation, washing and filter pressing to obtain APV with a water content of ≤30%. The upper layer liquid of the vanadium precipitation tank and the filtrate produced by APV filter pressing and washing are combined and then enter the wastewater pool for the next step of recycling treatment.

[0023] The vanadium precipitation wastewater contains a large amount of fine-particle ammonium polyvanadate. In the process of extracting ammonium polyvanadate from vanadium slag by acidic ammonium salt precipitation method, large-particle ammonium polyvanadate will be extracted, and fine-particle ammonium polyvanadate will remain in the vanadium precipitation wastewater. The particle size of the ammonium polyvanadate remaining in the vanadium precipitation wastewater is generally less than 300 mesh.

[0024] In the related art, a method for recovering ammonium polyvanadate from vanadium precipitation wastewater is to filter the vanadium precipitation wastewater with a filter cloth to obtain ammonium polyvanadate particles. The filter cloth is soaked in alkaline water to achieve the regeneration of the filter cloth. The soaking time for the filter cloth regeneration is 2h-3h, and the amount of wastewater generated after one regeneration is 4m³.

[0025] However, due to the small size of ammonium polyvanadate particles, it is very easy to clog the filter cloth. In a short period of time (after running 2 to 3 times), the filter cloth will be clogged and production cannot continue. The filter cloth has to be regenerated, which causes the equipment to fail to meet the smooth production needs, increases the labor intensity of employees and increases the amount of wastewater generated.

[0026] In the related art, another method for recovering ammonium polyvanadate from vanadium precipitation wastewater is the grabbing method. That is, the ammonium polyvanadate is allowed to settle in the wastewater pool. When the ammonium polyvanadate in the wastewater pool is deposited to a certain material level, the ammonium polyvanadate is grabbed with a grab bucket and then transported to a dissolution tank for re-dissolution. The re-dissolution operation is the same as the normal vanadium precipitation of the vanadium-containing leaching solution to recover vanadium. Although this method can recover ammonium polyvanadate, the recovery rate of ammonium polyvanadate obtained by this method is low, and the quality of the recovered ammonium polyvanadate is poor and the impurities added are increased.

[0027] In addition, the process of re-dissolving ammonium polyvanadate and re-precipitating vanadium to produce ammonium polyvanadate also increases the amount of wastewater generated and the consumption of auxiliary materials (such as ammonium salts, sulfuric acid and other auxiliary materials).

[0028] In view of this, in order to solve at least one of the above technical problems, the present invention provides a method for recovering ammonium polyvanadate in vanadium precipitation wastewater, which improves the recovery rate of ammonium polyvanadate in vanadium precipitation wastewater, improves the quality of recovered ammonium polyvanadate fines, avoids the clogging of filter bags used to filter ammonium polyvanadate fines, and avoids the generation of excess wastewater and the consumption of auxiliary materials.

[0029] The present invention is described in detail below in conjunction with embodiments and drawings.

[0030] A first aspect of the present invention provides a method for recovering ammonium polyvanadate from vanadium precipitation wastewater, such as Figure 1 As shown, the method specifically includes steps S10 to S12.

[0031] S10, subjecting the vanadium precipitation wastewater generated in the process of preparing ammonium polyvanadate to sedimentation treatment to obtain a first slurry containing ammonium polyvanadate.

[0032] Vanadium precipitation wastewater includes the vanadium precipitation upper layer liquid discharged from the vanadium precipitation process steps, and the liquid discharged from the ammonium polyvanadate solid-liquid separation, washing and filter pressing steps.

[0033] It should be noted that, in the embodiments of the present invention, the size of the ammonium polyvanadate contained in the vanadium precipitation wastewater varies according to the size of the filter cloth in the filter pressing step. Usually, the size of the ammonium polyvanadate contained in the vanadium precipitation wastewater is smaller than the size of the filter cloth in the filter pressing step.

[0034] By subjecting the vanadium precipitation wastewater to sedimentation treatment, a first slurry containing ammonium polyvanadate can be obtained.

[0035] S11, flocculating and washing the first slurry to obtain a second slurry containing ammonium polyvanadate.

[0036] By performing flocculation treatment on the first slurry, the ammonium polyvanadate in the first slurry can be quickly precipitated, thereby improving the recovery efficiency.

[0037] The flocculated slurry obtained after the flocculation treatment is washed to remove impurities in the flocculated slurry and obtain a second slurry of higher quality. The washing solution can be a liquid such as water.

[0038] S12, filtering the second slurry to obtain a filter cake containing ammonium polyvanadate.

[0039] The second slurry with higher quality obtained through flocculation and washing is filtered to obtain a filter cake containing ammonium polyvanadate.

[0040] In the embodiment of the present invention, a first slurry containing ammonium polyvanadate can be obtained by subjecting vanadium precipitation wastewater to sedimentation treatment. By subjecting the first slurry to flocculation treatment with a flocculant, the ammonium polyvanadate in the first slurry can be rapidly precipitated, thereby improving the recovery efficiency. By cleaning the flocculated slurry obtained after the flocculation treatment, impurities in the flocculated slurry can be removed to obtain a second slurry of higher quality. By filtering the second slurry with a higher degree of impurity, a filter cake containing ammonium polyvanadate can be obtained. Thus, through the scheme of the present invention, the efficiency of recovering ammonium polyvanadate in vanadium precipitation wastewater is improved, and the quality of the recovered ammonium polyvanadate is improved.

[0041] In some embodiments of the present invention, Figure 1 The specific process of step S10 (subjecting sedimentation treatment to the vanadium precipitation wastewater generated in the process of preparing ammonium polyvanadate to obtain a first slurry containing ammonium polyvanadate) is as follows: inputting the vanadium precipitation wastewater generated in the process of preparing ammonium polyvanadate into a sedimentation tank for sedimentation to obtain a stratified slurry, discharging the supernatant of the upper layer of the stratified slurry into a wastewater tank through an overflow outlet at the top of the sedimentation tank, and transporting the slurry of the lower layer of the stratified slurry to a washing tank.

[0042] In some examples, the slurry settled at the bottom of the wastewater tank can also be transported to the washing tank as needed.

[0043] In some embodiments of the present invention, Figure 1 The step S11 shown, flocculating and washing the first slurry to obtain a second slurry containing ammonium polyvanadate, may include: adding a flocculant to the first slurry to obtain a flocculated slurry; and washing the flocculated slurry with water to obtain a second slurry.

[0044] The flocculant can be anionic polyacrylamide, or flocculants containing carbon, hydrogen or oxygen, etc. This can achieve the flocculation effect without affecting the quality of ammonium polyvanadate.

[0045] By flocculating the first slurry, the ammonium polyvanadate in the first slurry can be quickly precipitated, thereby improving the recovery efficiency. By washing the flocculated slurry obtained after the flocculation treatment with water, impurities in the flocculated slurry can be removed to obtain a second slurry with higher quality.

[0046] In addition, cleaning the flocculated slurry core obtained after flocculation treatment with water can not only improve the quality of ammonium polyvanadate in the second slurry, but also dilute the second slurry to avoid excessive load on the equipment, thereby affecting the service life and reliability of the equipment.

[0047] In some examples, in order to further improve the quality of ammonium polyvanadate in the second slurry, the flocculated slurry obtained after flocculation treatment can be repeatedly washed with water, and after each washing is completed, the quality of ammonium polyvanadate in the second slurry is tested until the quality of ammonium polyvanadate in the second slurry meets the quality requirements and the washing is stopped.

[0048] In some embodiments of the present invention, the flocculated slurry is cleaned by water to obtain a second slurry, comprising: adding a certain amount of water to the flocculated slurry, and stirring the flocculated slurry to which water has been added; in response to the stirring time reaching a first specified time, stopping the stirring, and allowing the flocculated slurry to which water has been added to stand; in response to the standing time reaching a second specified time, separating the supernatant from the flocculated slurry to which water has been added to obtain the second slurry.

[0049] Specifically, the first prescribed time can be determined according to the use requirements, as long as the water and the flocculated slurry are stirred evenly. For example, the first prescribed time can be 10 minutes, 20 minutes or 30 minutes, etc., which is not specifically limited here.

[0050] Specifically, the second specified time can be determined according to the use requirements, as long as the water and the second slurry can be separated. For example, the first specified time can be 10 minutes, 20 minutes or 30 minutes, etc., which is not specifically limited here.

[0051] In some embodiments of the present invention, the flocculant contains a solution containing 0.5% anionic polyacrylamide, thereby further improving the coagulation effect of ammonium polyvanadate without affecting the quality of the ammonium polyvanadate in the second slurry.

[0052] In some embodiments of the present invention, Figure 1 The step S12 shown, filtering the second slurry to obtain a filter cake containing ammonium polyvanadate, may include: adding a skeleton agent and water to the second slurry in sequence to obtain a third slurry; filtering the third slurry to obtain a filter cake containing ammonium polyvanadate.

[0053] Adding a skeleton agent to the second slurry can improve the filtering effect, make the ammonium polyvanadate in the third slurry easier to filter, and improve the recovery effect of the ammonium polyvanadate.

[0054] Adding water to the second slurry with the skeleton agent added can dilute the slurry with the skeleton agent added, so as to avoid excessive load on the equipment operation, thereby affecting the service life and reliability of the equipment.

[0055] Filtering the diluted slurry after adding the skeleton agent greatly improves the filtering effect, greatly reduces the degree of clogging of the filter bag during the filtering process, and improves the recovery effect.

[0056] In some embodiments of the present invention, the framework agent may be a solution containing sawdust.

[0057] Specifically, the skeleton agent can be obtained according to the relationship of 2:1 between unit volume of water and unit mass of sawdust.

[0058] For example, 2L of water can be added to 1kg of sawdust and soaked for a preset time to obtain a skeleton agent. The preset time can be determined according to the use requirements. For example, the preset time can be greater than or equal to 12h. For example, the preset time can be 12h, 13h, 14h or 15h, etc., which is not specifically limited here.

[0059] In some embodiments of the present invention, before filtering the second slurry to obtain a filter cake composed of ammonium polyvanadate, the method further comprises: forming a filter membrane covering the surface of the filter bag on the surface of the filter bag close to the slurry by a filter aid.

[0060] By forming a filter membrane on the surface of the filter bag, the filter bag can be prevented from being blocked by the ammonium polyvanadate during the process of filtering the ammonium polyvanadate.

[0061] In some embodiments of the present invention, the filter aid may be a solution containing lignocellulose.

[0062] Specifically, the filter aid can be obtained according to the relationship of unit volume of water to unit mass of sawdust of 1:0.2.

[0063] For example, first, 0.2 kg of cellulose can be added to 1 m³ of water to prepare cellulose slurry. After soaking for 12 hours, the prepared cellulose slurry is obtained. The cellulose slurry is then filtered with a filter bag. The cellulose in the cellulose slurry is retained on the surface of the filter bag to form a filter membrane. The filtrate can be used as raw water for making cellulose slurry.

[0064] In some examples, during the process of filtering the lignocellulosic slurry with the lignocellulosic slurry filter bag, the filter bag filtration area can be 1m 2 The membrane is prepared by mixing 1m³ of lignocellulosic slurry to obtain a filter membrane with moderate thickness.

[0065] In some embodiments of the present invention, filtering the third slurry to obtain a filter cake composed of ammonium polyvanadate may include: filtering the third slurry through a filter bag covered with a filter membrane to obtain a filter cake containing ammonium polyvanadate. In this way, the filter bag can be prevented from being blocked by the ammonium polyvanadate during the filtering of the ammonium polyvanadate, thereby improving production efficiency.

[0066] In some embodiments of the present invention, the method may further include: pelletizing the filter cake containing ammonium polyvanadate to obtain pellets; and melting the pellets to obtain vanadium-containing compounds.

[0067] The filter cake containing ammonium polyvanadate obtained by filtration can be used to prepare vanadium-containing compounds.

[0068] In some examples, the filter cake containing ammonium polyvanadate can be pelletized by a granulator to obtain a plurality of pellets, and the plurality of pellets are transported to a melting furnace for melting to produce a flaky vanadium-containing compound, such as vanadium pentoxide.

[0069] Since the filter cake obtained in the embodiment of the present invention contains a flocculant, it is very easy to be formed into balls under the extrusion of a ball-making machine. Therefore, the filter cake obtained in the embodiment of the present invention can improve the generation efficiency of the flaky vanadium-containing compound.

[0070] To facilitate understanding, the embodiments of the present invention are described below with reference to specific examples.

[0071] Reference Figure 2~Figure 4 .

[0072] The ammonium polyvanadate in the vanadium precipitation wastewater can be recovered through the wastewater recovery system. Figure 4 As shown, the wastewater recovery system may include: a sedimentation unit 100, a flocculation and cleaning unit 200, a slurry mixing unit 300, a filtration unit 400 and a granulation unit 500. Among them, the sedimentation unit 100 may include a sedimentation tank 4 and a rake 1 connected to the sedimentation tank 4, a material bucket 2, an overflow weir 3, rake teeth 5, a first slurry valve 6, and a first pump 7. The flocculation and cleaning unit 200 includes: a washing tank 14 and a first liquid level meter 8 connected to the washing tank 14, a first agitator 9, a first flocculant valve 10, a first water valve 11, a flow measuring valve 12, a second slurry valve 13, and a second pump 15. The slurry mixing unit 300 may include: a slurry mixing tank 21 and a second liquid level meter 16 connected to the slurry mixing tank 21, a second agitator 17, a feeding port 18, a second water valve 19, a third slurry valve 20, and a third pump 22. The filtering unit 400 may include: a suction filter tank 24 and a filter slurry valve 23, a steam valve 25, a vacuum valve 26, and a drain valve 27 connected to the suction filter tank 24. The granulating unit 500 may include a silo 28, a first conveying belt 29, a granulator 30, and a second conveying belt 31.

[0073] In this example, the cylinder diameter of the sedimentation tank 4 is 12m, the height is 5m, and the bottom is a cone with a height of 1.5m. The structures and dimensions of the washing tank 14 and the mixing tank 21 are consistent, with a cylinder diameter of 3m, a height of 4.3m, and an elliptical arc bottom with a height of 0.5m. The speed of the agitator in the tank is 62r / min, and the empty height in the tank is ≥0.5m under stirring. The side flow port of the washing tank is 1.0m away from the lower edge of the cylinder. The cylinder diameter of the suction filter tank is 2m and the height is 0.8m; the aperture of the filter bag is 300 mesh.

[0074] Reference Figure 2 and Figure 3 A method for recovering ammonium polyvanadate from vanadium precipitation wastewater based on a wastewater recovery system may include steps S21 to S25.

[0075] S21, performing sedimentation treatment on the vanadium precipitation wastewater to obtain a first slurry containing ammonium polyvanadate.

[0076] The upper layer of vanadium precipitation liquid, APV solid-liquid separation and washing liquid are transported to the distribution tube 2 in the sedimentation tank 4, and the fine particles of APV in the upper layer of vanadium precipitation liquid, APV solid-liquid separation and washing liquid are settled in the sedimentation tank 4, and the supernatant enters the wastewater tank through the overflow weir 3 at the upper part of the sedimentation tank 4; the fine particles of APV are settled at the bottom of the sedimentation tank 4. The rake machine 1 rotates to drive the rake teeth 5 to rotate around the center of the sedimentation tank 4 and rake the fine particles of APV at the bottom of the sedimentation tank 4 to the bottom center of the sedimentation tank 4.

[0077] The first slurry valve 6 is opened, the first pump 7 is started, and the slurry with fine particles APV is transported to the washing tank 14. A small amount of fine particles APV that have not settled in the sedimentation tank 4 but settled in the wastewater tank can also be transported to the washing tank 14 as needed.

[0078] The opening and closing of the first slurry valve is an intermittent operation. For example, when the slurry settled in the settling tank 4 reaches a certain volume, the first slurry valve can be opened to discharge the slurry settled in the settling tank 4, and when the slurry discharged to the settling tank 4 is lower than the first volume, the first slurry valve 6 is closed, and the first pump 7 is turned off.

[0079] S22, flocculating and washing the first slurry to obtain a second slurry containing ammonium polyvanadate.

[0080] A first level gauge 8 for detecting the liquid level in the tank is installed on the top of the washing tank 14. In response to the slurry in the washing tank 14 reaching a specified liquid level (for example, the slurry submerges the position corresponding to the lower set of blades of the first agitator 9), the first agitator 9 is started; the slurry is continued to be delivered, and when the liquid level reaches a specified liquid level (for example, a position 5 mm from the upper edge of the washing tank 14), the slurry feeding is stopped; the flocculant valve 10 is opened, and the prepared quantitative flocculant solution is delivered to the washing tank 14, and the stirring is continued for a specified time, and then the stirring is stopped. After standing for a specified time, the side flow valve 12 on the side of the washing tank 14 is opened to discharge the supernatant to the wastewater tank.

[0081] In this example, the amount of flocculant added can be determined according to the volume of the slurry in the washing tank 14. When the flocculant contains a 0.5% aqueous solution of anionic polyacrylamide, 1L of flocculant solution can be added to 1m³ of fine-grained APV slurry. In order to make the stirring more uniform, the stirring time after adding the flocculant can be greater than or equal to 30 minutes. For example, the stirring time can be 30 minutes, 32 minutes, 35 minutes, or 40 minutes. In order to completely settle the ammonium polyvanadate in the slurry, the specified standing time can be greater than or equal to 40 minutes. For example, the stirring time can be 40 minutes, 45 minutes, 50 minutes, or 60 minutes.

[0082] After the supernatant in the washing tank 14 is discharged (for example, whether the supernatant has been discharged can be determined by whether the liquid level in the washing tank 14 drops to the flow measuring valve), the side flow valve 12 is closed, the first agitator 9 is started, and the first water valve 11 is opened. After the liquid level reaches the specified level, the first water valve 11 is closed, and stirring is continued for a specified time, and then stirring is stopped. After standing for a specified time, the side flow valve 12 on the side of the washing tank 14 is opened to discharge the supernatant to the wastewater tank. This step can be repeated according to the quality of washing to improve the quality of APV in the slurry.

[0083] In this example, the side flow outlet of the washing tank is 1.0m away from the lower edge of the cylinder. After the supernatant is discharged from the side flow outlet each time, wash water is added to 0.5m above the side flow outlet. The standing time is ≥20min, and the washing can be repeated 3 times.

[0084] The second slurry valve 13 is opened, and the second pump 15 is started, and the washed fine particles APV at the bottom of the washing tank 14 are transported to the mixing tank 21 .

[0085] The solution of the present invention collects the APV underflow (the underflow of the sedimentation tank and the wastewater tank) of fine particles formed after sedimentation, and then adds washing water (i.e., the water used to wash the APV) and flocculants to wash and quickly settle them, thereby ensuring both the quality of the recovered fine particle APV and the recovery rate.

[0086] S23, adding a skeleton agent and water to the second slurry in sequence to obtain a third slurry.

[0087] A second level gauge 16 for detecting the liquid level in the mixing tank 21 is installed on the top of the mixing tank 21. After the slurry in the mixing tank 21 reaches the specified liquid level and submerges the lower blades of the second agitator 17, the second agitator 17 is started; the slurry is continuously conveyed, and when the liquid level reaches the specified liquid level, the slurry feeding is stopped; the valve of the feed port 18 is opened, a certain amount of skeleton agent is added, and the second water valve 19 is opened to add a certain amount of water according to the situation, and after continuing to stir for a specified time, the third slurry valve 20 is opened, the third pump 22 is started, and the APV slurry is conveyed to the suction filtration tank 24.

[0088] In this example, slurry is transported from the washing tank 14 to the slurry mixing tank 21 , and when the liquid level is 0.5 m away from the upper edge of the slurry mixing tank 21 , the slurry supply is stopped.

[0089] In this example, in order to uniformly mix the skeleton agent, water and the third slurry, the specified stirring time may be greater than or equal to 10 minutes.

[0090] In this example, the skeleton agent was prepared by adding 1 kg of sawdust to 2 L of water.

[0091] The solution of the present invention collects the washed fine particles of APV, adds a skeleton agent and water to mix the mixture, and then transports the mixture to a suction filtration tank for solid-liquid separation to achieve a better solid-liquid separation effect.

[0092] S24, filtering the third slurry through a filter bag covered with a filter membrane to obtain a filter cake containing ammonium polyvanadate.

[0093] Before the APV slurry is transported to the suction filtration tank 24, a filter bag is first installed in the suction filtration tank 24, and then the filter aid slurry valve 23 is opened to transport a certain amount of filter aid slurry into the filter bag, and then the steam valve 25 and the vacuum valve 26 are opened to start the vacuum system. After the filter aid forms a thin filter membrane on the surface of the filter bag, the third pump 22 is started to transport a certain amount of APV slurry to the suction filtration tank 24. The APV slurry is separated into solid and liquid in the suction filtration tank 24 to obtain a filter cake and filtrate with a water content of ≤32%.

[0094] Open the drain valve 27 regularly (or adjust the opening of the drain valve 27) to drain the filtrate into the wastewater tank.

[0095] The solution of the present invention is to spread the filter aid on the surface of the filter bag of the suction filtration tank before the fine particle APV is transported to the suction filtration tank. This can prevent the fine particle APV from clogging the filter bag and causing a large amount of wastewater to be generated during regeneration, and it is also beneficial to the formation of the filter cake and can ensure that the filter cake falls off smoothly.

[0096] In this example, the filter aid is prepared at a ratio of 1m³ water to 0.2kg wood cellulose.

[0097] In this example, the process of filtering lignocellulosic slurry through filter bags is based on the filter bag filtration area of ​​1m 2 It is carried out by proportioning 1m³ of lignocellulosic pulp.

[0098] S25, pelletizing the filter cake containing ammonium polyvanadate to obtain material balls, and melting the material balls to obtain vanadium pentoxide.

[0099] Lift the filter bag in the filtration tank 24, and transport the filter cake formed on the filter bag to the silo 28. The APV filter cake is transported to the granulator 30 for balling through the first conveyor belt 29 at the bottom of the silo 28 to obtain balls with a diameter of 20 mm. The balls are then transported to the melting furnace for melting through the second conveyor belt 31 to generate flaky V2O5 products.

[0100] The filter cake obtained by the scheme of the present invention contains flocculant and is very easy to be formed into balls under the extrusion of a ball-making machine. After the ball enters the melting furnace, the product flake V2O5 is generated.

[0101] The flocculant, skeleton agent and filter aid used in the scheme of the present invention have no influence on the quality of the product flake V2O5 and are used in small amounts.

[0102] The quality of the flake V2O5 obtained through the embodiments of the present invention can be seen in Table 1.

[0103] Table 1

[0104] Through the example of the present invention, the recovery rate of ammonium polyvanadate in vanadium precipitation wastewater can be improved, the impurities in the recovered ammonium polyvanadate can be reduced, the quality of the recovered ammonium polyvanadate can be improved, the clogging of the filter bag used for filtering the fine particles of the ammonium polyvanadate can be avoided, the generation of excess wastewater and the consumption of auxiliary materials can be avoided, and the quality of the flaky vanadium pentoxide prepared by filtering the ammonium polyvanadate can be improved.

[0105] The ammonium polyvanadate recovery technology and system of the present invention can be used for industrial production, which has simple operation, low labor intensity, high degree of automation, low production cost and good product quality, and is conducive to promoting the development of the vanadium industry.

[0106] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0107] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for recovering ammonium polyvanadate from vanadium precipitation wastewater, characterized in that: include: The vanadium precipitation wastewater generated in the process of preparing ammonium polyvanadate is subjected to sedimentation treatment to obtain a first slurry containing ammonium polyvanadate; flocculating and washing the first slurry to obtain a second slurry containing ammonium polyvanadate; The second slurry is filtered to obtain a filter cake containing ammonium polyvanadate.

2. The method according to claim 1, characterized in that The flocculating and washing the first slurry to obtain the second slurry containing ammonium polyvanadate comprises: adding a flocculant to the first slurry to obtain a flocculated slurry; The flocculated slurry is washed with water to obtain the second slurry.

3. The method according to claim 2, characterized in that The step of washing the flocculated slurry with water to obtain the second slurry comprises: Adding a certain amount of water to the flocculated slurry, and stirring the flocculated slurry to which the water has been added; In response to the stirring time reaching a first specified time, stopping the stirring and allowing the flocculated slurry to which water has been added to stand; In response to the standing time reaching a second specified time, a supernatant is separated from the flocculated slurry to which water has been added to obtain the second slurry.

4. The method according to claim 2, characterized in that: The flocculant contains anionic polyacrylamide.

5. The method according to any one of claims 2 to 4, characterized in that: The filtering of the second slurry to obtain a filter cake containing ammonium polyvanadate comprises: Adding a skeleton agent and water to the second slurry in sequence to obtain a third slurry; The third slurry is filtered to obtain a filter cake containing ammonium polyvanadate.

6. The method according to claim 5, characterized in that The skeleton agent contains sawdust.

7. The method according to claim 5, characterized in that The third slurry is filtered to obtain a filter cake composed of ammonium polyvanadate, comprising: The third slurry is filtered through a filter bag covered with a filter membrane to obtain a filter cake containing ammonium polyvanadate.

8. The method according to claim 1, characterized in that: Before filtering the second slurry to obtain a filter cake composed of ammonium polyvanadate, the method further comprises: A filter membrane covering the surface of the filter bag is formed on the surface of the filter bag close to the slurry by the filter aid.

9. The method according to claim 8, characterized in that The filter aid contains lignocellulose.

10. The method according to claim 1, characterized in that In the step of filtering the second slurry to obtain a filter cake containing ammonium polyvanadate, the method further comprises: The filter cake containing ammonium polyvanadate is subjected to a ball-forming treatment to obtain material balls; The pellets are melted to obtain a vanadium-containing compound.

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