Preparation method of ammonium polyvanadate and ammonium polyvanadate

Abstract

According to the scheme provided by the invention, fine particle APV (ammonium polyvanadate) generated by the previous batch of vanadium precipitation is used as a first tank of seed crystal for the current batch of vanadium precipitation, so that the high-concentration vanadium precipitation operation is simplified, and the quality of the precipitated APV meets the product quality requirement. And meanwhile, fine particle APV generated in the vanadium precipitation and filter pressing links of the batch is recovered in time and continuously returned to the vanadium precipitation mother tank which is in production of the batch to participate in normal vanadium precipitation, so that the particles grow up, the purpose of recovering the fine particle APV is achieved, and the generation amount of the fine particle APV is further reduced.

Description

Technical Field

[0001] The invention relates to the field of ammonium polyvanadate, and in particular to a preparation method of ammonium polyvanadate and ammonium polyvanadate. Background Art

[0002] After sodium calcination of vanadium slag, leaching and impurity removal are performed to obtain a clear and transparent vanadium-containing leachate. The vanadium-containing leachate is added with sulfuric acid to adjust the pH value of the solution to 6.5~7.0, and then ammonium sulfate is added. After mixing evenly, it is transported to the vanadium precipitation tank for heating, stirring, and then concentrated sulfuric acid is added to adjust the pH value for vanadium precipitation. The obtained ammonium polyvanadate (APV) is then separated from the solid and liquid, washed and filtered to obtain APV with a water content of ≤30%. Due to the need to reduce production costs and the environmental protection needs to reduce the amount of wastewater generated per ton of V2O5, the vanadium concentration of the vanadium-containing leachate has exceeded 50g / L on the basis of vanadium yield and vanadium product quality assurance, and sometimes exceeds 70g / L. Although the vanadium precipitation problem of vanadium-containing leachate ≤100g / L can be solved after adopting a continuous vanadium precipitation process, the first tank operation of each batch of continuous vanadium precipitation is crucial. It is necessary to manually adjust various parameters according to the material properties of this batch of vanadium-containing leachate before the vanadium precipitation operation of this batch can be carried out. In addition, the recovery and utilization of fine particles of APV produced in the APV vanadium precipitation and filtration process has always been a difficult point, which not only affects the vanadium yield but also affects the subsequent vanadium precipitation wastewater treatment. Summary of the invention

[0003] In view of this, in order to overcome at least one aspect of the above problems, an embodiment of the present invention provides a method for preparing ammonium polyvanadate comprising the following steps: The vanadium-containing leaching solution is transported to an acid adding tank for acid addition, and after the pH value of the liquid in the acid adding tank reaches a first preset value, the liquid in the acid adding tank is transported to an ammonium adding tank for ammonium addition; Determine whether there is ammonium polyvanadate slurry remaining from the previous batch of vanadium precipitation in the settling tank; If present, the ammonium polyvanadate slurry in the settling tank is transported to the vanadium precipitation mother tank, and after the liquid level in the ammonium addition tank reaches the first set value, the liquid in the ammonium addition tank is transported to the vanadium precipitation mother tank, and the liquid is heated, stirred, and acidified in the vanadium precipitation mother tank; After the liquid level in the vanadium precipitation mother tank reaches a second set value, the liquid in the vanadium precipitation mother tank is respectively transported to a plurality of vanadium precipitation sub-tanks; The liquid is continuously heated, stirred and acidified in the vanadium precipitation sub-tank. After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than a first preset time, the stirring, heating and acidification are stopped and the liquid is allowed to stand for a second preset time, and the upper layer of liquid is transported to the sedimentation tank, and the lower layer of slurry is subjected to solid-liquid separation to obtain ammonium polyvanadate and filtrate; The filtrate is transported to a sedimentation tank, and the upper layer liquid and the filtrate are precipitated in the sedimentation tank to obtain ammonium polyvanadate slurry. The ammonium polyvanadate slurry obtained in this batch is continuously returned to the vanadium precipitation mother tank being produced in this batch.

[0004] In some embodiments, the vanadium-containing leaching solution is transported to an acid adding tank for acid addition, and after the pH value of the liquid in the acid adding tank reaches a first preset value, the liquid in the acid adding tank is transported to an ammonium adding tank for ammonium addition, further comprising: After the vanadium-containing leaching solution submerges the disperser for acid addition in the acid addition tank, starting the agitator in the acid addition tank and using two sets of blades of the agitator to stir the vanadium-containing leaching solution; When the pH value of the liquid in the acid adding tank is 6.5-7.0 and the liquid level reaches the set liquid level, the liquid in the acid adding tank is transported to the ammonium adding tank.

[0005] In some embodiments, the liquid in the acid addition tank is transported to the ammonium addition tank for ammonium addition, further comprising: When the liquid in the ammonium adding tank submerges the lower blade of the stirrer in the ammonium adding tank, starting the stirrer to start stirring and starting to add ammonium salt; The amount of ammonium salt added is obtained by multiplying the flow rate of the liquid transported from the acid adding tank to the ammonium adding tank by the vanadium concentration of the liquid and then by the ammonium adding coefficient.

[0006] In some embodiments, the ammonium polyvanadate slurry in the settling tank is transported to the vanadium precipitation mother tank, and after the liquid level in the ammonium addition tank reaches a first set value, the liquid in the ammonium addition tank is transported to the vanadium precipitation mother tank, and the liquid is heated, stirred, and acid-treated in the vanadium precipitation mother tank, further comprising: When the ammonium polyvanadate slurry submerges the lower blade of the stirrer in the vanadium precipitation mother tank, the stirrer is started to stir, and steam is provided to the vanadium precipitation mother tank by a steam ring pipe to heat the liquid in the vanadium precipitation mother tank; After the ammonium polyvanadate slurry submerges the disperser for adding acid in the vanadium precipitation mother tank, the conveying of the ammonium polyvanadate slurry is stopped, and the ammonium polyvanadate slurry is continued to be heated to boiling and kept boiling; The liquid in the ammonium adding tank is transported to the vanadium precipitation mother tank, and compressed air is provided to the vanadium precipitation mother tank by a compressed air ring pipe to enhance the stirring effect; Acid is added to the vanadium precipitation mother tank to maintain the pH value at 2.0-2.3.

[0007] In some embodiments, the liquid is continuously heated, stirred, and acidified in the vanadium precipitation sub-tank. After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than a first preset time, the stirring, heating, and acidification are stopped, and the liquid is allowed to stand for a second preset time, and the upper layer liquid is transported to the sedimentation tank, and the lower layer slurry is subjected to solid-liquid separation to obtain ammonium polyvanadate and filtrate, further comprising: After the liquid in the precipitation sub-tank submerges the disperser for adding acid in the precipitation sub-tank, start the agitator for stirring, and use the steam loop to provide steam to the precipitation sub-tank for heating and maintaining a boiling state, and use the disperser to add acid to the precipitation sub-tank to maintain the pH value at 2.0-2.3; After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than the first preset time, the stirring, heating, acid addition and standing for a second preset time are stopped, and the upper layer of liquid in the vanadium precipitation sub-tank is transported to the sedimentation tank by using a side flow valve. After the upper layer of liquid is discharged, the lower layer of slurry is transported to the filter press washing equipment by using a bottom flow valve for solid-liquid separation and washing to obtain ammonium polyvanadate and filtrate.

[0008] In some embodiments, the filtrate is transported to a settling tank, and the supernatant and the filtrate are precipitated in the settling tank to obtain ammonium polyvanadate slurry, further comprising: The distribution tube in the settling tank is used to guide the upper liquid and the filtrate to obtain ammonium polyvanadate slurry and supernatant, wherein the ammonium polyvanadate slurry is settled at the bottom of the settling tank, and the supernatant enters the overflow weir in the settling tank through overflow and then enters the wastewater pool.

[0009] In some embodiments, it also includes: After the vanadium precipitation of the current batch of vanadium-containing leaching solution is completed, all the liquids in the acid adding tank and the ammonium adding tank are transported to the vanadium precipitation mother tank.

[0010] In some embodiments, it also includes: The supernatant is used to clean the vanadium precipitation mother tank and a plurality of vanadium precipitation child tanks.

[0011] In some embodiments, after the liquid level in the vanadium precipitation mother tank reaches a second set value, the liquid in the vanadium precipitation mother tank is respectively transported to a plurality of vanadium precipitation sub-tanks, further comprising: If the liquid level in the current vanadium precipitation sub-tank meets the preset requirements, the liquid in the vanadium precipitation mother tank is stopped from being transported to the current vanadium precipitation sub-tank, and the liquid in the vanadium precipitation mother tank is transported to the next vanadium precipitation sub-tank.

[0012] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides an ammonium polyvanadate, and the ammonium polyvanadate is prepared by the method described in any one of the above embodiments.

[0013] The present invention has one of the following beneficial technical effects: the scheme proposed by the present invention uses the fine-particle APV (ammonium polyvanadate) produced in the previous batch of vanadium precipitation as the first tank seed of this batch of vanadium precipitation. This operation simplifies the high-concentration vanadium precipitation operation and the quality of the precipitated APV meets the product quality requirements. At the same time, the fine-particle APV produced in the vanadium precipitation and filter pressing links of this batch is promptly recovered and returned to the vanadium precipitation mother tank as a seed together with the normal vanadium precipitation, which further reduces the amount of fine-particle APV produced and the problem of treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] 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.

[0015] Figure 1 A schematic flow chart of a method for preparing ammonium polyvanadate provided in an embodiment of the present invention; Figure 2 A flowchart of a method for preparing ammonium polyvanadate provided by an embodiment of the present invention; Figure 3 A schematic diagram of the preparation process of ammonium polyvanadate provided in an embodiment of the present invention; Figure 4 The figure is a quality diagram of the APV prepared according to the scheme provided in the embodiment of the present invention. DETAILED DESCRIPTION

[0016] 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.

[0017] 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.

[0018] According to one aspect of the present invention, an embodiment of the present invention provides a method for preparing ammonium polyvanadate, such as Figure 1 As shown, it may include the steps of: S1, transporting the vanadium-containing leaching solution to an acid adding tank for acid addition, and after the pH value of the liquid in the acid adding tank reaches a first preset value, transporting the liquid in the acid adding tank to an ammonium adding tank for ammonium addition; S2. Determine whether there is ammonium polyvanadate slurry remaining after the previous batch of vanadium precipitation in the settling tank; S3, if present, transporting the ammonium polyvanadate slurry in the settling tank to the vanadium precipitation mother tank, and after the liquid level in the ammonium addition tank reaches the first set value, transporting the liquid in the ammonium addition tank to the vanadium precipitation mother tank, and heating, stirring, and acid treatment the liquid in the vanadium precipitation mother tank; S4, after the liquid level in the vanadium precipitation mother tank reaches a second set value, the liquid in the vanadium precipitation mother tank is respectively transported to a plurality of vanadium precipitation sub-tanks; S5, continuing to heat, stir, and add acid to the liquid in the vanadium precipitation sub-tank, and after the boiling time of the liquid in the vanadium precipitation sub-tank is greater than a first preset time, stopping stirring, heating, and adding acid, and standing for a second preset time, transferring the upper layer liquid to the sedimentation tank, and performing solid-liquid separation on the lower layer slurry to obtain ammonium polyvanadate and filtrate; S6. The filtrate is transported to a sedimentation tank, and the upper layer liquid and the filtrate are precipitated in the sedimentation tank to obtain ammonium polyvanadate slurry. The ammonium polyvanadate slurry obtained in this batch is continuously returned to the vanadium precipitation mother tank being produced in this batch.

[0019] The solution proposed in the present invention uses the fine-particle APV (ammonium polyvanadate) produced in the previous batch of vanadium precipitation as the first tank seed of this batch of vanadium precipitation. This operation simplifies the high-concentration vanadium precipitation operation and the quality of the precipitated APV meets the product quality requirements. At the same time, the fine-particle APV produced in the vanadium precipitation and filtration process of this batch is promptly recovered and returned to the vanadium precipitation mother tank as a seed together with the normal vanadium precipitation, which further reduces the amount of fine-particle APV produced and the problem of treatment.

[0020] In some embodiments, the vanadium-containing leaching solution is transported to an acid adding tank for acid addition, and after the pH value of the liquid in the acid adding tank reaches a first preset value, the liquid in the acid adding tank is transported to an ammonium adding tank for ammonium addition, further comprising: After the vanadium-containing leaching solution submerges the disperser for acid addition in the acid addition tank, starting the agitator in the acid addition tank and using two sets of blades of the agitator to stir the vanadium-containing leaching solution; When the pH value of the liquid in the acid adding tank is 6.5-7.0 and the liquid level reaches the set liquid level, the liquid in the acid adding tank is transported to the ammonium adding tank.

[0021] Specifically, Figure 2 and Figure 3As shown, when acid is added in the acid adding tank 8, the vanadium-containing leaching solution valve 2 is opened, and the vanadium-containing leaching solution enters the acid adding tank 8. When the solution in the acid adding tank 8 submerges the disperser 6 for adding concentrated sulfuric acid, the stirrer 4 is started, and the acid valve 213 and the acid valve 11 are opened respectively, and the concentrated sulfuric acid enters the acid adding tank 8. The stirrer 4 has two sets of blades (the upper and lower sets of blades are for strengthening stirring), the lower blade is longer than the upper blade, and the lower blade is located below the disperser 6. In operation, there is a certain distance (about 50mm) between the lower blade and the disperser 6. A liquid level meter 3 is installed on the tank body of the acid adding tank 8 to measure the liquid level in the tank, and is interlocked with the vanadium-containing leaching solution valve 2, the stirrer 4, the acid valve 11, the pump 9, and the liquid outlet valve 10. A pH meter 7 is installed on the tank body of the acid adding tank 8 to measure the pH value of the solution in the acid adding tank, and is interlocked with the acid valve 11, and the pH is 6.5~7.0. When the vanadium leaching solution in the acid adding tank 8 reaches the set liquid level and the pH value of the solution in the tank is 6.5-7.0, the liquid outlet valve 10 is opened and the pump 9 is started to transport the vanadium leaching solution in the acid adding tank 8 to the ammonium adding tank 22.

[0022] In some embodiments, the liquid in the acid addition tank is transported to the ammonium addition tank for ammonium addition, further comprising: When the liquid in the ammonium adding tank submerges the lower blade of the stirrer in the ammonium adding tank, starting the stirrer to start stirring and starting to add ammonium salt; The amount of ammonium salt added is obtained by multiplying the flow rate of the liquid transported from the acid adding tank to the ammonium adding tank by the vanadium concentration of the liquid and then by the ammonium adding coefficient.

[0023] Specifically, Figure 2 and Figure 3 As shown, when the vanadium-containing leaching solution delivered by pump 19 submerges the lower blade of stirrer 219, stirrer 219 is started, and screw 21 is started to evenly deliver ammonium salt to ammonium adding tank 22. The amount of ammonium salt added is carried out according to the set ammonium adding coefficient, which is related to the flow rate of flowmeter 1 and the vanadium concentration of vanadium-containing leaching solution. The calculation formula is: ammonium salt addition amount = flow rate of vanadium-containing leaching solution × vanadium concentration of vanadium-containing leaching solution × ammonium adding coefficient. The amount of ammonium salt added is adjusted by the operating frequency of screw 21. A liquid level gauge 218 (to detect the liquid level in the tank) is installed on the top of ammonium adding tank 22. When the liquid level of ammonium adding tank 22 reaches the set value, open the liquid outlet valve 24, start pump 23, and deliver the liquid in ammonium adding tank 22 to vanadium precipitation mother tank 34.

[0024] In some embodiments, the ammonium polyvanadate slurry in the settling tank is transported to the vanadium precipitation mother tank, and after the liquid level in the ammonium addition tank reaches a first set value, the liquid in the ammonium addition tank is transported to the vanadium precipitation mother tank, and the liquid is heated, stirred, and acid-treated in the vanadium precipitation mother tank, further comprising: When the ammonium polyvanadate slurry submerges the lower blade of the stirrer in the vanadium precipitation mother tank, the stirrer is started to stir, and steam is provided to the vanadium precipitation mother tank by a steam ring pipe to heat the liquid in the vanadium precipitation mother tank; After the ammonium polyvanadate slurry submerges the disperser for adding acid in the vanadium precipitation mother tank, the conveying of the ammonium polyvanadate slurry is stopped, and the ammonium polyvanadate slurry is continued to be heated to boiling and kept boiling; The liquid in the ammonium adding tank is transported to the vanadium precipitation mother tank, and compressed air is provided to the vanadium precipitation mother tank by a compressed air ring pipe to enhance the stirring effect; Acid is added to the vanadium precipitation mother tank to maintain the pH value at 2.0-2.3.

[0025] Specifically, Figure 2 and Figure 3 As shown, before the vanadium-containing leaching solution in the ammonium addition tank 22 is transported to the vanadium precipitation mother tank 34, the pump 4 55 is started to transport the fine-grained APV slurry produced by the solution of the previous batch of vanadium precipitation after settling in the settling tank 54 to the vanadium precipitation mother tank 34 as the crystal seed for this vanadium precipitation. A bracket 33 is installed at the connection between the bottom of the vanadium precipitation mother tank 34 and the cylinder body, and a steam ring pipe 36 and a compressed air ring pipe 37 are placed on the bracket 33. The steam ring pipe 36 and the compressed air ring pipe 37 are both opened with evenly distributed small holes with a diameter of 5mm, and the small holes are all 45° downward and facing the center of the circle of the vanadium precipitation mother tank. In the vertical direction, about 50mm above the steam ring pipe 36 is the lower blade of the agitator 3 26, and about 50mm above the lower blade is the disperser 2 30 for secondary acid addition. A pH meter 2 31 is installed at the lower part of the cylinder body of the vanadium precipitation mother tank 34 to detect the pH value of the material in the tank. A thermometer 32 is installed at the bottom of the cylinder of the vanadium precipitation mother tank 34 to detect the temperature of the material in the tank. The pH meter 31 and the thermometer 32 are both located below the acid disperser 30 in the vanadium precipitation mother tank 34 in the vertical direction. A liquid level meter 325 is installed on the top of the vanadium precipitation mother tank 34 to measure the liquid level in the tank.

[0026] When the fine-grained APV slurry submerges the lower blades of the agitator 3 26, first start the agitator 3 26, then open the steam valve 1 28 to supply steam to the steam ring pipe 1 36 to heat the slurry in the vanadium precipitation mother tank 34. When the APV slurry submerges the disperser 2 30, stop the pump 4 55, continue to heat the slurry in the vanadium precipitation mother tank 34 to boiling (≥92°C), start the pump 2 23 to transport the vanadium-containing leaching solution to which the ammonium salt has been added to the vanadium precipitation mother tank 34, and at the same time open the compressed air valve 29 to supply compressed air to the compressed air ring pipe 37 to strengthen the stirring effect of the slurry in the tank, open the acid valve 3 15 and the acid valve 4 16 to add acid to the slurry in the vanadium precipitation mother tank 34, and keep the pH value of the slurry in the tank at 2.0~2.3 and keep it in a boiling state. When the liquid level in the vanadium precipitation mother tank 34 is about 500mm away from the upper edge of the tank body, open the discharge valve 1 38 and start the pump 3 35 to transport the material in the vanadium precipitation mother tank 34 to the vanadium precipitation sub-tank 47. The opening of each valve is controlled, and the reaction time of the vanadium-containing leaching solution in the vanadium precipitation mother tank 34 is ≥30min.

[0027] In some embodiments, the liquid is continuously heated, stirred, and acidified in the vanadium precipitation sub-tank. After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than a first preset time, the stirring, heating, and acidification are stopped, and the liquid is allowed to stand for a second preset time, and the upper layer liquid is transported to the sedimentation tank, and the lower layer slurry is subjected to solid-liquid separation to obtain ammonium polyvanadate and filtrate, further comprising: After the liquid in the precipitation sub-tank submerges the disperser for adding acid in the precipitation sub-tank, start the agitator for stirring, and use the steam loop to provide steam to the precipitation sub-tank for heating and maintaining a boiling state, and use the disperser to add acid to the precipitation sub-tank to maintain the pH value at 2.0-2.3; After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than the first preset time, the stirring, heating, acid addition and standing for a second preset time are stopped, and the upper layer of liquid in the vanadium precipitation sub-tank is transported to the sedimentation tank by using a side flow valve. After the upper layer of liquid is discharged, the lower layer of slurry is transported to the filter press washing equipment by using a bottom flow valve for solid-liquid separation and washing to obtain ammonium polyvanadate and filtrate.

[0028] In some embodiments, after the liquid level in the vanadium precipitation mother tank reaches a second set value, the liquid in the vanadium precipitation mother tank is respectively transported to a plurality of vanadium precipitation sub-tanks, further comprising: If the liquid level in the current vanadium precipitation sub-tank meets the preset requirements, the liquid in the vanadium precipitation mother tank is stopped from being transported to the current vanadium precipitation sub-tank, and the liquid in the vanadium precipitation mother tank is transported to the next vanadium precipitation sub-tank.

[0029] Specifically, Figure 2 and Figure 3As shown, compared with the vanadium precipitation mother tank 34, the vanadium precipitation sub-tank 47 has the same facilities except that there is no compressed air ring pipe and a flow meter port is added. A side flow pipeline is installed in the middle and lower part of the cylinder of the vanadium precipitation sub-tank 47, and a side flow valve 50 is installed on the pipeline to discharge the supernatant after vanadium precipitation; the specific position of the side flow pipeline on the vanadium precipitation sub-tank 47 is determined according to the position of the ammonium polyvanadate (APV) slurry produced by the vanadium concentration of the vanadium-containing leaching solution after 40 minutes of standing, and is generally 200mm above the slurry surface (mainly to avoid the vortex formed during the discharge process from sweeping away the sediment (APV) and causing vanadium loss). The vanadium precipitation sub-tank 47 and the vanadium precipitation mother tank 34 are connected in series; there are multiple vanadium precipitation sub-tanks 47, which are connected in parallel; the number of vanadium precipitation sub-tanks 47 is set to meet the material standing time in the vanadium precipitation sub-tank 47 and the buffer time of the subsequent material in the continuous vanadium precipitation process.

[0030] After the material in the precipitation tank 47 floods the disperser 3 43, start the agitator 4 40, open the steam valve 2 42, open the acid valve 5 17, and keep the pH value of the material in the precipitation tank 47 at 2.0~2.3 and keep it in a boiling state. When the liquid level in the precipitation tank 47 is about 500mm away from the upper edge of the tank body, stop conveying the slurry into the precipitation tank and convey it to the next precipitation tank. After stopping conveying the material to the precipitation tank 47, the material in the precipitation tank 47 continues to be stirred, the pH value is 2.0~2.3, and the boiling state for ≥10min, stop the agitator 4 40, close the steam valve 2 42, let the material in the tank stand for ≥40min, open the side flow valve 1 50, and discharge the upper layer of liquid in the precipitation tank 47 into the distribution cylinder 52. After the upper layer of liquid is drained from the sedimentation tank 47, the side flow valve 50 is closed, the bottom flow valve 48 is opened, and the slurry in the sedimentation tank 47 is transported to the filter press washing equipment for solid-liquid separation and washing. The filter cake obtained is APV, and the filtrate (APV with fine particles) is discharged into the distribution cylinder 52.

[0031] In some embodiments, the filtrate is transported to a sedimentation tank, the upper layer liquid and the filtrate are precipitated in the sedimentation tank to obtain ammonium polyvanadate slurry, and the ammonium polyvanadate slurry obtained in this batch is continuously returned to the vanadium precipitation mother tank being produced in this batch, further comprising: The distribution tube in the settling tank is used to guide the upper liquid and the filtrate to obtain ammonium polyvanadate slurry and supernatant, wherein the ammonium polyvanadate slurry is settled at the bottom of the settling tank, and the supernatant enters the overflow weir in the settling tank through overflow and then enters the wastewater pool.

[0032] Specifically, Figure 2 and Figure 3 As shown, after the upper layer liquid in the sedimentation tank 47 and the filtrate of the APV slurry after filtration and washing are guided by the distribution tube 52 in the sedimentation tank 54, a large amount of fine particles of APV settle at the bottom of the sedimentation tank 54, and the clear liquid overflows into the overflow weir 53 and then enters the wastewater pool.

[0033] During the vanadium precipitation process, when the liquid in the sedimentation tank 54 overflows, the discharge valve 2 56 is opened and the pump 4 55 is started to transport the fine-grained APV slurry at the bottom of the sedimentation tank 54 to the vanadium precipitation mother tank 34. The fine-grained APV participates in the normal vanadium precipitation of the vanadium-containing leaching solution, and its particle size further grows to become APV of normal particle size, so that the fine-grained APV is further recycled and utilized, and the vanadium yield is improved. In this way, the fine-grained APV produced in this batch continues to return to the vanadium precipitation mother tank being produced in this batch after settling in the sedimentation tank, participates in normal vanadium precipitation, and its particles grow, so as to achieve the purpose of recycling fine-grained APV.

[0034] In some embodiments, it also includes: After the vanadium precipitation of the current batch of vanadium-containing leaching solution is completed, all the liquids in the acid adding tank and the ammonium adding tank are transported to the vanadium precipitation mother tank.

[0035] In some embodiments, it also includes: The supernatant is used to clean the vanadium precipitation mother tank and a plurality of vanadium precipitation child tanks.

[0036] Specifically, Figure 2 and Figure 3 As shown, when the vanadium precipitation of the batch of vanadium-containing leachate is completed, the vanadium-containing leachate in the acid adding tank 8 and the ammonium adding tank 22 is all transported to the vanadium precipitation mother tank 34 according to the process, and the relevant equipment and facilities are shut down. When there is no vanadium-containing leachate transported to the vanadium precipitation mother tank 34 at the front end, the pump 4 55 is stopped and the discharge valve 2 56 is closed.

[0037] When the batch precipitation is completed, the materials in the vanadium precipitation mother tank 34 and each vanadium precipitation sub-tank 47 are discharged, the side flow valve 2 57 is opened, and the pump 5 58 is started to transport the supernatant in the sedimentation tank 54 to the vanadium precipitation mother tank 34 and each vanadium precipitation sub-tank 47 for cleaning the remaining materials in the tank, thereby saving the amount of wastewater generated.

[0038] Before each tank is operated, start the degassing tower system, open the corresponding degassing valve, pump the gas generated in the tank into the degassing tower, and discharge it after being treated and qualified.

[0039] In some embodiments, the acid adding tank has a cylinder diameter of 2m, a height of 2.4m, an elliptical arc bottom (height 0.4m), a stirrer speed of 62r / min, and a tank empty height of ≥0.5m under stirring. The ammonium adding tank has the same size as the acid adding tank, and the stirrer speed is also 62r / min. The vanadium precipitation mother tank has a cylinder diameter of 3m, a height of 4.3m, an elliptical arc bottom (height 0.5m), a stirrer speed of 62r / min, and a tank empty height of ≥0.5m under stirring. The vanadium precipitation sub-tank has the same size and shape as the vanadium precipitation mother tank, and the stirrer speed is also 62r / min. A production line can have one vanadium precipitation mother tank and four vanadium precipitation sub-tanks (in parallel). The vanadium precipitation mother tank is continuously fed with vanadium-containing leaching solution for vanadium precipitation. The APV slurry in the tank is continuously transported from the bottom of the vanadium precipitation mother tank to the vanadium precipitation sub-tank. When the vanadium precipitation of this batch of vanadium-containing leaching solution is completed or the production plan for the shift is completed, the vanadium precipitation operation is ended according to the process. After application, the quality of the obtained APV meets the production requirements. Its APV composition can be seen in Figure 4 After applying the scheme proposed by the present invention, after the material in the vanadium precipitation tank is allowed to stand for 40 minutes, the upper liquid is taken from the vanadium precipitation tank for testing, and the vanadium concentration of the upper liquid is ≤0.33g / L, which meets the production control index (the vanadium concentration of the upper liquid is ≤0.35g / L), the vanadium precipitation rate is ≥99.34%, and the vanadium yield of the vanadium precipitation process is 98.76% (the vanadium yield before improvement is 98.32%), which increases the vanadium yield of the vanadium precipitation process by 0.44%; and each batch (220m 3 Vanadium-containing leaching solution) Vanadium precipitation saves wastewater generation 5m 3 .

[0040] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides an ammonium polyvanadate, which is prepared by the steps described in any of the above embodiments.

[0041] The above are exemplary embodiments disclosed in the present invention, but it should be noted that various changes and modifications may be made without departing from the scope disclosed in the embodiments of the present invention as defined in the claims. The functions, steps and / or actions of the method claims according to the disclosed embodiments described herein do not need to be performed in any particular order. In addition, although the elements disclosed in the embodiments of the present invention may be described or required in individual form, they may also be understood as multiple unless explicitly limited to the singular.

[0042] It should be understood that, as used herein, the singular forms "a", "an" are intended to include the plural forms as well, unless the context clearly supports an exception. It should also be understood that, as used herein, "and / or" refers to any and all possible combinations including one or more of the associated listed items.

[0043] The serial numbers of the embodiments disclosed in the above embodiments of the present invention are only for description and do not represent the advantages or disadvantages of the embodiments.

[0044] A person skilled in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the disclosure of the embodiments of the present invention (including the claims) is limited to these examples; under the concept of the embodiments of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and there are many other changes in different aspects of the above embodiments of the present invention, which are not provided in detail for the sake of simplicity. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the embodiments of the present invention should be included in the protection scope of the embodiments of the present invention.

Claims

1. A method for preparing ammonium polyvanadate, characterized in that: include: The vanadium-containing leaching solution is transported to an acid adding tank for acid addition, and after the pH value of the liquid in the acid adding tank reaches a first preset value, the liquid in the acid adding tank is transported to an ammonium adding tank for ammonium addition; Determine whether there is ammonium polyvanadate slurry remaining from the previous batch of vanadium precipitation in the settling tank; If present, the ammonium polyvanadate slurry in the settling tank is transported to the vanadium precipitation mother tank, and after the liquid level in the ammonium addition tank reaches the first set value, the liquid in the ammonium addition tank is transported to the vanadium precipitation mother tank, and the liquid is heated, stirred, and acidified in the vanadium precipitation mother tank; After the liquid level in the vanadium precipitation mother tank reaches a second set value, the liquid in the vanadium precipitation mother tank is respectively transported to a plurality of vanadium precipitation sub-tanks; The liquid is continuously heated, stirred and acidified in the vanadium precipitation sub-tank. After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than a first preset time, the stirring, heating and acidification are stopped and the liquid is allowed to stand for a second preset time, and the upper layer of liquid is transported to the sedimentation tank, and the lower layer of slurry is subjected to solid-liquid separation to obtain ammonium polyvanadate and filtrate; The filtrate is transported to a sedimentation tank, and the upper layer liquid and the filtrate are precipitated in the sedimentation tank to obtain ammonium polyvanadate slurry. The ammonium polyvanadate slurry obtained in this batch is continuously returned to the vanadium precipitation mother tank being produced in this batch.

2. The method according to claim 1, characterized in that The vanadium-containing leaching solution is transported to an acid adding tank for acid addition, and after the pH value of the liquid in the acid adding tank reaches a first preset value, the liquid in the acid adding tank is transported to an ammonium adding tank for ammonium addition, further comprising: After the vanadium-containing leaching solution submerges the disperser for acid addition in the acid addition tank, starting the agitator in the acid addition tank and using two sets of blades of the agitator to stir the vanadium-containing leaching solution; When the pH value of the liquid in the acid adding tank is 6.5-7.0 and the liquid level reaches the set liquid level, the liquid in the acid adding tank is transported to the ammonium adding tank.

3. The method according to claim 1, characterized in that The liquid in the acid adding tank is transported to the ammonium adding tank for ammonium addition, further comprising: When the liquid in the ammonium adding tank submerges the lower blade of the stirrer in the ammonium adding tank, starting the stirrer to start stirring and starting to add ammonium salt; The amount of ammonium salt added is obtained by multiplying the flow rate of the liquid transported from the acid adding tank to the ammonium adding tank by the vanadium concentration of the liquid and then by the ammonium adding coefficient.

4. The method according to claim 1, characterized in that The ammonium polyvanadate slurry in the settling tank is transported to the vanadium precipitation mother tank, and after the liquid level in the ammonium adding tank reaches a first set value, the liquid in the ammonium adding tank is transported to the vanadium precipitation mother tank, and the liquid is heated, stirred, and acid-treated in the vanadium precipitation mother tank, further comprising: When the ammonium polyvanadate slurry submerges the lower blade of the stirrer in the vanadium precipitation mother tank, the stirrer is started to stir, and steam is provided to the vanadium precipitation mother tank by a steam ring pipe to heat the liquid in the vanadium precipitation mother tank; After the ammonium polyvanadate slurry submerges the disperser for adding acid in the vanadium precipitation mother tank, the conveying of the ammonium polyvanadate slurry is stopped, and the ammonium polyvanadate slurry is continued to be heated to boiling and kept boiling; The liquid in the ammonium adding tank is transported to the vanadium precipitation mother tank, and compressed air is provided to the vanadium precipitation mother tank by a compressed air ring pipe to enhance the stirring effect; Acid is added to the vanadium precipitation mother tank to maintain the pH value at 2.0-2.

3.

5. The method according to claim 1, characterized in that The liquid is continuously heated, stirred, and acidified in the vanadium precipitation sub-tank. After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than a first preset time, stirring, heating, and acidification are stopped, and the liquid is allowed to stand for a second preset time, and the upper layer liquid is transported to the sedimentation tank, and the lower layer slurry is subjected to solid-liquid separation to obtain ammonium polyvanadate and filtrate, further comprising: After the liquid in the precipitation sub-tank submerges the disperser for adding acid in the precipitation sub-tank, start the agitator for stirring, and use the steam loop to provide steam to the precipitation sub-tank for heating and maintaining a boiling state, and use the disperser to add acid to the precipitation sub-tank to maintain the pH value at 2.0-2.3; After the boiling time of the liquid in the vanadium precipitation sub-tank is greater than the first preset time, the stirring, heating, acid addition and standing for a second preset time are stopped, and the upper layer of liquid in the vanadium precipitation sub-tank is transported to the sedimentation tank by using a side flow valve. After the upper layer of liquid is discharged, the lower layer of slurry is transported to the filter press washing equipment by using a bottom flow valve for solid-liquid separation and washing to obtain ammonium polyvanadate and filtrate.

6. The method according to claim 1, characterized in that The filtrate is transported to a settling tank, and the upper layer liquid and the filtrate are precipitated in the settling tank to obtain ammonium polyvanadate slurry, further comprising: The distribution tube in the settling tank is used to guide the upper liquid and the filtrate to obtain ammonium polyvanadate slurry and supernatant, wherein the ammonium polyvanadate slurry is settled at the bottom of the settling tank, and the supernatant enters the overflow weir in the settling tank through overflow and then enters the wastewater pool.

7. The method according to claim 6, characterized in that Also includes: If the vanadium precipitation of the current batch of vanadium-containing leaching solution is completed, all the liquids in the acid adding tank and the ammonium adding tank are transported to the vanadium precipitation mother tank.

8. The method according to claim 7, characterized in that Also includes: The supernatant is used to clean the vanadium precipitation mother tank and a plurality of vanadium precipitation child tanks.

9. The method according to claim 1, characterized in that After the liquid level in the vanadium precipitation mother tank reaches a second set value, the liquid in the vanadium precipitation mother tank is respectively transported to a plurality of vanadium precipitation sub-tanks, further comprising: If the liquid level in the current vanadium precipitation sub-tank meets the preset requirements, the liquid in the vanadium precipitation mother tank is stopped from being transported to the current vanadium precipitation sub-tank, and the liquid in the vanadium precipitation mother tank is transported to the next vanadium precipitation sub-tank.

10. An ammonium polyvanadate, characterized in that: The ammonium polyvanadate is prepared by the method according to any one of claims 1 to 9.

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