Preparation method of ammonium polyvanadate and ammonium polyvanadate

Abstract

The invention discloses a preparation method of ammonium polyvanadate and the ammonium polyvanadate. The method comprises the following steps: carrying out calcium salt roasting and acid leaching on the vanadium slag to obtain a calcified acid leaching vanadium solution; removing lead from the calcified vanadium acid leaching solution to obtain a purified solution; adjusting the pH value of the purified liquid and adding ammonium sulfate; heating, introducing compressed air and ozone, and stirring; and after the compressed air and the ozone are introduced into a preset volume, stopping heating, stirring and standing to obtain ammonium polyvanadate. According to the scheme provided by the invention, ozonation is adopted, so that the vanadium precipitation yield after lead removal can be improved, meanwhile, the subsequent vanadium product quality is not influenced, other impurities are not introduced after oxidation is completed, the vanadium oxide wastewater circulation is not influenced, and the cost of the oxidation process is low.

Description

Technical Field

[0001] This invention relates to the field of ammonium polyvanadate, and more specifically to a method for preparing ammonium polyvanadate and the ammonium polyvanadate itself. Background Technology

[0002] Currently, vanadium slag is obtained from blast furnace ironmaking and converter vanadium extraction using iron concentrate. Sodium vanadium extraction and calcification processes are widely used in production for vanadium slag extraction. The calcification process for vanadium extraction from vanadium slag mainly includes calcium salt roasting, acid leaching, impurity removal, vanadium precipitation, and melting / reduction. Among these, roasting and acid leaching are the key steps affecting the overall vanadium oxide yield.

[0003] To maximize vanadium leaching from roasted clinker, a primary acid leaching of the clinker followed by a secondary deep acid leaching of the tailings is currently employed. The deep leaching process uses a relatively low pH (approximately 1.0). However, the Pb content in the precipitated vanadium leaching (APV) obtained so far is only 0.02%. While adding lead-removing agents or lead precipitation inhibitors has yielded APV products with lead content <0.01%, the residual vanadium in the supernatant of the vanadium precipitation solution has increased from 0.2-0.3 g / L to approximately 0.3-0.4 g / L, resulting in a vanadium precipitation rate decrease of 0.5-1%. Summary of the Invention

[0004] In view of this, in order to overcome at least one aspect of the above problems, embodiments of the present invention provide a method for preparing ammonium polyvanadate, comprising the following steps: Calcium salt roasting and acid leaching of vanadium slag yield calcified acid leaching vanadium solution; The lead-removing process of the calcified vanadium leaching solution yields a purified solution. Adjust the pH of the purified solution and add ammonium sulfate; The mixture is heated and then stirred after being introduced with compressed air and ozone. After the compressed air and ozone are introduced into a preset volume, heating is stopped, stirring is stopped, and the mixture is allowed to stand to obtain ammonium polyvanadate.

[0005] In some embodiments, the lead removal process of the calcified vanadium leaching solution to obtain a purified solution further includes: Add a lead removal agent or a lead precipitation inhibitor to the calcified acid leaching vanadium solution, filter the solution, and let it stand to obtain a purified solution.

[0006] In some embodiments, adjusting the pH of the purified solution and adding ammonium sulfate further includes: Adjust the pH of the purified solution to 1.5~2.5.

[0007] In some embodiments, adjusting the pH of the purified solution and adding ammonium sulfate further includes: The ammonium sulfate is added based on a mass ratio of 0.5 to 1:1 between the ammonium sulfate and the vanadium in the purified solution.

[0008] In some embodiments, the pressure of the compressed air is from 1 atmosphere to 10 atmospheres.

[0009] In some embodiments, the volume ratio of the compressed air to the ozone is 95:5 to 100:1.

[0010] In some embodiments, the heating and subsequent stirring treatment with compressed air and ozone further includes: The purified liquid is heated to 90~100℃.

[0011] In some embodiments, the method further includes: The compressed air and ozone are introduced when the temperature is above 80°C for 10-30 minutes.

[0012] In some embodiments, the heating method is steam heating or electric heating.

[0013] Based on the same inventive concept, according to another aspect of the present invention, embodiments of the present invention also provide an ammonium polyvanadate, which is prepared by the method described in any of the above embodiments.

[0014] The present invention has one of the following beneficial technical effects: the solution proposed in this invention can improve the yield of vanadium precipitation after lead removal by using ozone oxidation, while not affecting the quality of subsequent vanadium products. At the same time, no other impurities are introduced after oxidation, and the vanadium oxidation wastewater is not affected. Moreover, the oxidation process has low cost. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other embodiments can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic flowchart illustrating a method for preparing ammonium polyvanadate according to an embodiment of the present invention. Detailed Implementation

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be further described in detail below with reference to specific examples and the accompanying drawings.

[0018] It should be noted that all uses of "first" and "second" in the embodiments of the present invention are for the purpose of distinguishing two entities or parameters with the same name but different names. It is clear that "first" and "second" are only for the convenience of expression and should not be construed as limiting the embodiments of the present invention. Subsequent embodiments will not explain this in detail.

[0019] According to one aspect of the present invention, embodiments of the present invention provide a method for preparing ammonium polyvanadate, such as... Figure 1 As shown, it may include the following steps: S1, vanadium slag is roasted with calcium salts and acid leached to obtain calcified acid leaching vanadium solution; S2, lead removal is performed on the calcified acid leaching vanadium solution to obtain a purified solution; S3, Adjust the pH value of the purified solution and add ammonium sulfate; S4, heated and then mixed with compressed air and ozone; S5, after the compressed air and ozone are introduced into a preset volume, heating and stirring are stopped and the mixture is allowed to stand to obtain ammonium polyvanadate.

[0020] Specifically, a lead-removing agent or a lead precipitation inhibitor is added to the vanadium leaching solution. The solution is filtered and allowed to stand to obtain a purified solution. The purified solution is then transferred to an acid mixing tank for acid preparation according to specific acidity requirements. After acid preparation, the vanadium leaching solution is transferred to an ammonium mixing tank for ammonium preparation according to specific requirements. After ammonium preparation, the vanadium leaching solution is transferred to a heating tank. During heating, a certain amount of compressed air and ozone mixture is introduced to stir and heat the solution. The oxygen in the compressed air oxidizes a small amount of tetravalent vanadium in the vanadium leaching solution to pentavalent vanadium under acidic heating conditions. Upon completion of heating, after ensuring a certain amount of compressed air is introduced, the compressed air and stirring are turned off, and the solution is kept at a constant temperature to ensure the normal growth of ammonium polyvanadate crystals in the vanadium leaching solution. Thus, the proposed solution, by using ozone oxidation, can improve the vanadium precipitation yield after lead removal without affecting the quality of subsequent vanadium products. Furthermore, the oxidation process does not introduce other impurities, does not affect the recycling of vanadium oxidation wastewater, and has low cost.

[0021] In some embodiments, the lead removal process of the calcified vanadium leaching solution to obtain a purified solution further includes: Add a lead removal agent or a lead precipitation inhibitor to the calcified acid leaching vanadium solution, filter the solution, and let it stand to obtain a purified solution.

[0022] Specifically, to address the issue of lead impurities affecting the quality of vanadium products, a deep lead removal treatment is performed on the calcified acid leaching vanadium solution during the vanadium precipitation pretreatment stage: granular lead removal agent or lead precipitation inhibitor is added to the calcified acid leaching vanadium solution to cause selective precipitation of lead ions in the solution; after the reaction is complete, the lead precipitate is removed by filtration, and the filtered solution is allowed to stand and clarify, resulting in a purified solution with significantly reduced lead content. For example, if the Pb content in the calcified acid leaching vanadium solution is 0.012 g / L, the Pb content after purification is 0.004 g / L.

[0023] The addition of a lead-removing agent causes the vanadium in the solution to undergo the following reaction: 5S 2- + 34H + + H2V 10 O 28 4- =10VO 2+ +18H2O+5S↓ In some embodiments, adjusting the pH of the purified solution and adding ammonium sulfate further includes: Adjust the pH of the purified solution to 1.5~2.5.

[0024] In some embodiments, adjusting the pH of the purified solution and adding ammonium sulfate further includes: The ammonium sulfate is added based on a mass ratio of 0.5 to 1:1 between the ammonium sulfate and the vanadium in the purified solution.

[0025] Specifically, the purified solution is transferred to an acid mixing tank, and the pH value of the solution is adjusted to 1.5~2.5 by adding acid hydrolysants such as sulfuric acid. This acidity range provides a suitable acidic environment for the formation of ammonium polyvanadate crystals, while inhibiting the hydrolysis and precipitation of impurity ions. After the acid mixing is completed, the solution is transferred to an ammonium mixing tank, and ammonium sulfate is added at a mass ratio of 0.5~1:1 to vanadium in the purified solution to ensure sufficient ammonium ion concentration in the solution, providing the necessary reactants for the vanadium precipitation reaction, while avoiding excessive ammonium salt that could lead to waste or affect product purity.

[0026] Among them, due to the low concentration of tetravalent vanadium in the solution, the main reaction during the precipitation of vanadium by acidic ammonium salt is as follows:

[0027] In some embodiments, the pressure of the compressed air is from 1 atmosphere to 10 atmospheres.

[0028] In some embodiments, the volume ratio of the compressed air to the ozone is 95:5 to 100:1.

[0029] In some embodiments, the heating and subsequent stirring treatment with compressed air and ozone further includes: The purified liquid is heated to 90~100℃.

[0030] In some embodiments, the method further includes: The compressed air and ozone are introduced when the temperature is above 80°C for 10-30 minutes.

[0031] In some embodiments, the heating method is steam heating or electric heating.

[0032] Specifically, the solution with adjusted acidity and ammonium salt ratio is transferred to a heating tank and heated using either steam or electric heating. When the solution temperature rises above 80°C, a mixture of compressed air and ozone is introduced, wherein the volume ratio of compressed air to ozone is controlled at 95:5 to 100:1, and the pressure of the compressed air is maintained at 1 to 10 atmospheres. The mixed gas is continuously introduced for 10-30 minutes, and stirring is carried out simultaneously during the gas introduction process: on the one hand, the oxygen in the compressed air efficiently oxidizes a small amount of tetravalent vanadium in the solution to pentavalent vanadium under acidic heating conditions, thereby increasing the total amount of precipitable vanadium; on the other hand, ozone can help enhance the oxidation effect, and the introduction of the mixed gas enhances the turbulence of the solution, avoiding uneven local reaction and solving the problem of low vanadium precipitation efficiency in traditional purification liquids. Continue heating to 90~100℃ and maintain this temperature until the heating process is complete to ensure that the oxidation reaction proceeds fully.

[0033] After heating, a certain amount of compressed air is continuously introduced for a period of time to ensure the stability of the oxidation state of the system. Then, the compressed air and stirring device are turned off, and the system is kept at a constant temperature of 90-100℃ for static incubation. During this process, pentavalent vanadium in the solution reacts fully with ammonium ions to form ammonium polyvanadate crystals. Constant temperature incubation ensures normal crystal growth, improving crystal purity and particle uniformity. Simultaneously, this process, through optimized oxidation efficiency and precise control of reaction conditions, effectively avoids vanadium loss while improving the quality of vanadium products (low lead, high purity), ensuring that the vanadium yield does not decrease, and does not affect the recycling of vanadium oxide wastewater.

[0034] Among them, acidic ammonium salt precipitation is used to precipitate pentavalent vanadium, while tetravalent vanadium is difficult to precipitate with ammonium salts. Other precipitation methods can be used, but the conditions for acidic ammonium salt precipitation are difficult to recover, which leads to a decrease in the precipitation rate.

[0035] Therefore, ozone is used to oxidize tetravalent vanadium to pentavalent vanadium:

[0036] As can be seen from the above formula, using ozone to oxidize tetravalent vanadium to pentavalent vanadium does not introduce new impurities and does not affect wastewater recycling.

[0037] Comparative Example 1 Take 0.5 L of vanadium leaching solution with a V content of 23.55 g / L, adjust the pH of the solution to 2.0, add 11.78 g of ammonium sulfate, stir, heat to 95℃ for 60 min, maintain the temperature and stir for 60 min, turn off the stirring and let it cool naturally for 120 min, filter, wash the filter cake with 50 ml of distilled water, collect the supernatant + wash water 0.52 L, and measure the TV of the supernatant to be 0.22 g / L. The vanadium precipitation rate is calculated as 1 - (C) / L. 上层液 *V 上层液 ) / (C 上层液 *V 上层液 The lead content was 99.03%; the APV (Advanced Permeable Volume) was obtained, and the dried lead content was 0.026%. Comparative Example 2 Take 0.5L of purified liquid, with a V content of 23.55 g / L. Adjust the pH of the purified liquid to 1.8, add 11.78g of ammonium sulfate, stir, heat from room temperature to 95℃ for 60 minutes, maintain the temperature and stir for 60 minutes, and add 0.02mol of sodium persulfate every 120 minutes while controlling the flow rate. Allow to cool naturally and stand for 120 minutes, filter, wash the filter cake with 50ml of distilled water, and collect the supernatant and wash water to obtain a total of 0.50L of vanadium-precipitated supernatant. Measure the TV of the supernatant to be 0.23g / L. The vanadium precipitation rate is calculated as 1 - (C) / L. 上层液 *V 上层液 ) / (C 上层液 *V 上层液 = 99.02%; sodium ion concentration in the upper vanadium precipitation solution was 0.04 mol / L; APV was obtained, and the lead content after drying was 0.005%; after adding calcium oxide to neutralize the upper vanadium precipitation solution, the sodium ion concentration in the recycled water was 0.04 mol / L. Neutralized recycled water is used for clinker leaching. Sodium ions enter the calcified acid leaching vanadium solution. After lead removal, a purified solution is obtained with a sodium ion concentration of 0.04 mol / L. 0.4 L of the purified solution is taken, and the pH is adjusted to 1.8. 10 g of ammonium sulfate is added, and the solution is stirred. Starting at room temperature, the solution is heated to 95°C for 60 minutes, and kept at this temperature with stirring for 60 minutes. During this process, 0.02 mol of sodium persulfate is added every 120 minutes, controlled by a flow meter. The solution is allowed to cool naturally and stand for 120 minutes, then filtered. The filter cake is washed with 50 ml of distilled water. The supernatant and wash water are collected to obtain a total of 0.40 L of vanadium-precipitated supernatant. The TV of the supernatant is measured to be 0.23 g / L. The vanadium precipitation rate is calculated as 1 - (C...). 上层液 *V 上层液 ) / (C 上层液 *V 上层液 The lead content was 99.02%, and the APV was obtained. The lead content after drying was 0.005%. The sodium ion concentration in the upper liquid was 0.08 mol / L. It can be seen that the use of sodium persulfate will lead to the accumulation of sodium ions in the wastewater system until the water circulation system can no longer operate.

[0038] Example 1 Take 0.5L of the purified liquid, in which the vanadium content is 23.55 g / L. Adjust the pH of the purified liquid to 1.5, add 5.89g of ammonium sulfate, i.e., the mass ratio of ammonium sulfate to vanadium in the purified liquid is 0.5:1. Stir, heat to 95℃ for 60 minutes from room temperature, and maintain the temperature while stirring for 60 minutes. During this process, control the flow meter to introduce 0.6L of ozone and 11.4L of compressed air at 1 atmosphere for 10 minutes, i.e., the volume ratio of compressed air to ozone is 95:5. Stop stirring and stop introducing ozone, let it cool naturally and stand for 120 minutes, filter, wash the filter cake with 50ml of distilled water, collect the supernatant and wash water to obtain a total of 0.51L of vanadium-precipitated supernatant. Measure the TV of the supernatant to be 0.25g / L. The vanadium precipitation rate is calculated as 1 - (C) / L. 上层液 *V 上层液 ) / (C 上层液 *V 上层液 =98.91%; APV was obtained, the lead content after drying was 0.005%, the vanadium precipitation supernatant was free of impurities, and it can continue to be recycled as neutralization water for clinker leaching.

[0039] Example 2 Take 0.5L of purified liquid, with a vanadium content of 23.55 g / L. Adjust the pH of the purified liquid to 1.8, add 7.78g of ammonium sulfate (i.e., the mass ratio of ammonium sulfate to vanadium in the purified liquid is 0.67:1), and stir. Heat to 95℃ for 60 minutes from room temperature, and maintain this temperature while stirring for another 60 minutes. During this process, control the flow meter to introduce 0.6L of ozone and 30L of compressed air at 5 atmospheres for 20 minutes (i.e., the volume ratio of compressed air to ozone is 50:1). Stop stirring and ozone introduction, allow to cool naturally and stand for 120 minutes, filter, wash the filter cake with 50ml of distilled water, and collect the supernatant and wash water to obtain a total of 0.51L of vanadium-precipitated supernatant. The TV of the supernatant is 0.28g / L. The vanadium precipitation rate is calculated as 1 - (C...). 上层液 *V 上层液 ) / (C 上层液 *V 上层液 =98.79%; APV was obtained, the lead content after drying was 0.005%, the vanadium precipitation supernatant was free of impurities, and it can continue to be recycled as neutralization water for clinker leaching.

[0040] Example 3 Take 0.5L of purified liquid, with a vanadium content of 23.55 g / L. Adjust the pH of the purified liquid to 1.8, add 11.78g of ammonium sulfate (the mass ratio of ammonium sulfate to vanadium in the purified liquid is 1:1), stir, heat to 95℃ for 60 minutes from room temperature, and maintain the temperature while stirring for 60 minutes. During this process, control the flow meter to introduce 0.6L of ozone and 60L of compressed air at 10 atmospheres for 30 minutes, i.e., the volume ratio of compressed air to ozone is 100:1. Stop stirring and stop introducing ozone, allow to cool naturally and stand for 120 minutes, filter, wash the filter cake with 50ml of distilled water, collect the supernatant and wash water to obtain a total of 0.50L of vanadium-precipitated supernatant, and measure the TV of the supernatant to be 0.24g / L. The vanadium precipitation rate is calculated as 1 - (C) / L. 上层液 *V 上层液 ) / (C 上层液 *V 上层液 =98.98%; APV was obtained, the lead content after drying was 0.005%, the vanadium precipitation supernatant was free of impurities, and it can continue to be recycled as neutralization water for clinker leaching.

[0041] Example 4 Take 0.5L of purified liquid, with a V content of 23.55 g / L. Adjust the pH of the purified liquid to 1.8, add 11.78g of ammonium sulfate, stir, and heat from room temperature to 95℃ for 60 minutes. Maintain this temperature and stir for 60 minutes. During this process, control the flow meter to introduce 2.0L of ozone every 120 minutes. Turn off the stirring and stop the ozone introduction. Allow to cool naturally and stand for 120 minutes. Filter, wash the filter cake with 50ml of distilled water, and collect the supernatant and wash water to obtain a total of 0.50L of vanadium-precipitated supernatant. Measure the TV of the supernatant to be 0.23g / L. The vanadium precipitation rate is calculated as 1 - (C) / L. 上层液 *V 上层液 ) / (C 上层液 *V 上层液 =99.02%; APV was obtained, the lead content after drying was 0.005%, the vanadium precipitation supernatant was free of impurities, and it can continue to be recycled as neutralization water for clinker leaching.

[0042] The proposed solution uses ozone oxidation to improve the yield of vanadium precipitation after lead removal, without affecting the quality of subsequent vanadium products. Furthermore, the oxidation process does not introduce other impurities, does not affect the recycling of vanadium oxide wastewater, and has low cost.

[0043] Based on the same inventive concept, according to another aspect of the present invention, embodiments of the present invention also provide an ammonium polyvanadate, which is prepared by the steps described in any of the above embodiments.

[0044] The above are exemplary embodiments disclosed in this invention. However, it should be noted that various changes and modifications can be made without departing from the scope of the embodiments of this invention as 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 number.

[0045] It should be understood that, as used herein, the singular form “a” is intended to include the plural form 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 of one or more of the associated listed items.

[0046] The embodiment numbers disclosed in the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0047] 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 different aspects of the invention 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 preparing ammonium polyvanadate, characterized in that, Includes the following steps: Calcium salt roasting and acid leaching of vanadium slag yield calcified acid leaching vanadium solution; The lead-removing process of the calcified vanadium leaching solution yields a purified solution. Adjust the pH of the purified solution and add ammonium sulfate; The mixture is heated and then stirred after being introduced with compressed air and ozone. After the compressed air and ozone are introduced into a preset volume, heating is stopped, stirring is stopped, and the mixture is allowed to stand to obtain ammonium polyvanadate.

2. The method as described in claim 1, characterized in that, The purified solution obtained by removing lead from the calcified acid leaching vanadium solution further comprises: Add a lead removal agent or a lead precipitation inhibitor to the calcified acid leaching vanadium solution, filter the solution, and let it stand to obtain a purified solution.

3. The method as described in claim 1, characterized in that, Adjusting the pH of the purified solution and adding ammonium sulfate further includes: Adjust the pH of the purified solution to 1.5~2.

5.

4. The method as described in claim 1, characterized in that, Adjusting the pH of the purified solution and adding ammonium sulfate further includes: The ammonium sulfate is added based on a mass ratio of 0.5 to 1:1 between the ammonium sulfate and the vanadium in the purified solution.

5. The method as described in claim 1, characterized in that, The pressure of the compressed air is between 1 atmosphere and 10 atmospheres.

6. The method as described in claim 1, characterized in that, The volume ratio of the compressed air to the ozone is 95:5 to 100:

1.

7. The method as described in claim 1, characterized in that, The process, involving heating and the introduction of compressed air and ozone followed by stirring, further includes: The purified liquid is heated to 90~100℃.

8. The method as described in claim 7, characterized in that, Also includes: The compressed air and ozone are introduced when the temperature is above 80°C for 10-30 minutes.

9. The method as described in claim 1, characterized in that, The heating method is either steam heating or electric heating.

10. An ammonium polyvanadate, characterized in that, The ammonium polyvanadate is prepared using the method described in any one of claims 1-9.

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