Preparation method of vanadium pentoxide and vanadium pentoxide

Abstract

The invention discloses a preparation method of vanadium pentoxide. The preparation method comprises the following steps: mixing ammonium polyvanadate and ammonium metavanadate to obtain a mixture; preheating the mixture at a first temperature; and calcining the preheated mixture at a second temperature, wherein the first temperature is lower than the second temperature. According to the scheme provided by the invention, on the basis of a reaction mechanism of preparing vanadium pentoxide from vanadium oxide, the ammonium polyvanadate and the ammonium metavanadate are mixed to prepare the vanadium pentoxide, the mixture of the ammonium polyvanadate and the ammonium metavanadate is looser, the contact surface between the mixture and air can be increased, and the ammonia removal effect and the oxidation effect are improved. The advantages of ammonium polyvanadate and ammonium metavanadate are combined, so that the impurity content of the product is improved, the operation process is simplified, the flow is short, the operation is simplified, and the requirement on equipment is reduced.

Description

Technical Field

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

[0002] In recent years, the method of producing high-purity vanadium pentoxide mainly includes using single ammonium polyvanadate and ammonium metavanadate as raw materials for calcination to prepare vanadium pentoxide. Among them, the use of ammonium polyvanadate to produce vanadium pentoxide, because the ammonium polyvanadate particles are fine and relatively uniform, the materials are relatively close, the high-valent vanadium is easily reduced to low-valent vanadium during the calcination process, and the contact with air is insufficient, the low-valent vanadium content in the product is high, and the apparent color is dark. The use of ammonium metavanadate to produce vanadium pentoxide has poor chromium removal ability by weak alkaline ammonium salt precipitation, high residual vanadium content in the supernatant, and low vanadium yield. The current sodium roasting wastewater treatment mostly adopts the direction of reduction and neutralization, which needs to be carried out under acidity, resulting in problems such as high chromium content in the product and difficulty in 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 vanadium pentoxide, comprising the following steps: mixing ammonium polyvanadate and ammonium metavanadate to obtain a mixture; preheating the mixture at a first temperature; The preheated mixture is calcined at a second temperature, wherein the first temperature is lower than the second temperature.

[0004] In some embodiments, the mass ratio of the ammonium polyvanadate to the ammonium metavanadate is 0.5-2.

[0005] In some embodiments, preheating the mixture at a first temperature further comprises: The mixture was preheated between 160°C and 350°C for 1 to 1.5 hours.

[0006] In some embodiments, calcining the preheated mixture at a second temperature further comprises: The mixture was calcined between 350°C and 600°C for 1.5-2 hours.

[0007] In some embodiments, ammonium polyvanadate and ammonium metavanadate are mixed to obtain a mixture, further comprising: Obtaining a vanadium solution and adjusting the pH value of the vanadium solution to 5 to 7 using sulfuric acid; Heat and stir and adjust the pH value to 1.8-2.5; Continue heating and add a precipitant when the temperature is 85-95°C. After precipitation for 30-60 minutes, separate the solid and liquid to obtain ammonium polyvanadate.

[0008] In some embodiments, the amount of precipitant added is calculated by mass ratio, precipitant: vanadium ions in the vanadium solution = 0.8 to 1.5.

[0009] In some embodiments, ammonium polyvanadate and ammonium metavanadate are mixed to obtain a mixture, further comprising: Obtain vanadium solution and add aluminum salt to remove silicon; Solid-liquid separation, take the supernatant and adjust the pH value to 8.5-9.5; A precipitant is added, and after precipitation for 60 to 120 minutes, solid-liquid separation is performed to obtain ammonium metavanadate.

[0010] In some embodiments, the amount of precipitant added is calculated by mass ratio, precipitant: vanadium ions in the vanadium solution = 4 to 5.

[0011] In some embodiments, the precipitating agent is ammonium sulfate or ammonium chloride.

[0012] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a vanadium pentoxide, wherein the vanadium pentoxide 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 is based on the reaction mechanism of preparing vanadium pentoxide from vanadium oxide, and vanadium pentoxide is prepared by mixing ammonium polyvanadate and ammonium metavanadate. The mixture of ammonium polyvanadate and ammonium metavanadate is more loose, which can increase the contact surface between the mixture and the air, and improve the deammoniation effect and oxidation effect. In addition, the advantages of ammonium polyvanadate and ammonium metavanadate are combined to improve the impurity content of the product, and the operation process of the method is simplified, the flow is short, the operation is simplified, and the requirements for equipment are reduced. 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 vanadium pentoxide provided in an 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 vanadium pentoxide, such as Figure 1 As shown, it may include the steps of: mixing ammonium polyvanadate and ammonium metavanadate to obtain a mixture; preheating the mixture at a first temperature; The preheated mixture is calcined at a second temperature, wherein the first temperature is lower than the second temperature.

[0019] The scheme proposed by the present invention is based on the reaction mechanism of preparing vanadium pentoxide from vanadium oxide, and uses ammonium polyvanadate and ammonium metavanadate to mix and prepare vanadium pentoxide. The mixture of ammonium polyvanadate and ammonium metavanadate is more loose, which can increase the contact surface between the mixture and the air, and improve the deammoniation effect and oxidation effect. In addition, the advantages of ammonium polyvanadate and ammonium metavanadate are combined to improve the impurity content of the product. In addition, the operation process of the method is simplified, the flow is short, the operation is simplified, and the requirements for equipment are reduced.

[0020] In some embodiments, the mass ratio of the ammonium polyvanadate to the ammonium metavanadate is 0.5-2.

[0021] In some embodiments, preheating the mixture at a first temperature further comprises: The mixture was preheated between 160°C and 350°C for 1 to 1.5 hours.

[0022] In some embodiments, calcining the preheated mixture at a second temperature further comprises: The mixture was calcined between 350°C and 600°C for 1.5-2 hours.

[0023] Specifically, powdered ammonium polyvanadate and ammonium metavanadate are mixed, the mass ratio of ammonium polyvanadate to ammonium metavanadate can be 0.5-2, and the mixture is placed in a rotary kiln with a negative pressure of -6 to -30Pa and heated in an oxidizing atmosphere. Then it is cooled, and the heating process includes a preheating section and a calcining section, and the heating temperature of the preheating section is 160°C to 350°C. The preheating decomposes and removes the moisture and ammonia in the mixture quickly, creating conditions for the oxidation reaction. The heating temperature of the calcining section is 350°C to 600°C, so that the reduced material is fully oxidized to a high-valent oxide; ensure the oxidation effect and apparent quality. The heating time of the preheating section can be 1-1.5 hours, preferably 1-1.2 hours; the heating time of the calcining section is 1.5-2 hours, preferably 1.6-1.8 hours. Controlling the heating time of the preheating section and the calcining section within the above range can further improve the deamination effect and oxidation effect of vanadium pentoxide, and reduce the sulfur content in the product. Finally, the material is naturally cooled in air atmosphere before leaving the kiln, and vanadium pentoxide is obtained after the temperature is ≤50℃. After the above process, the deamination decomposition reaction and oxidation reaction are sufficient, which can greatly reduce the content of chromium, sodium, sulfur, iron and tetravalent vanadium in the product.

[0024] In some embodiments, ammonium polyvanadate and ammonium metavanadate are mixed to obtain a mixture, further comprising: Obtaining a vanadium solution and adjusting the pH value of the vanadium solution to 5 to 7 using sulfuric acid; Heat and stir and adjust the pH value to 1.8-2.5; Continue heating and add a precipitant when the temperature is 85-95°C. After precipitation for 30-60 minutes, separate the solid and liquid to obtain ammonium polyvanadate.

[0025] In some embodiments, the amount of precipitant added is calculated by mass ratio, precipitant: vanadium ions in the vanadium solution = 0.8 to 1.5.

[0026] Specifically, the present invention adopts sodium vanadium extraction leachate to prepare ammonium polyvanadate, wherein the ammonium polyvanadate precipitation pH value is 1.8-2.5, the precipitation temperature is 85-95°C, the precipitant is one of ammonium sulfate and ammonium chloride, the amount of the precipitant added is 0.8-1.4 (calculated by mass ratio: ammonium sulfate: vanadium concentration = 0.8-1.5), the precipitation time is 30-60 minutes, and after precipitation, drying is carried out at 60-120°C to make the moisture content ≤0.1%.

[0027] In some embodiments, ammonium polyvanadate and ammonium metavanadate are mixed to obtain a mixture, further comprising: Obtain vanadium solution and add aluminum salt to remove silicon; Solid-liquid separation, take the supernatant and adjust the pH value to 8.5-9.5; A precipitant is added, and after precipitation for 60 to 120 minutes, solid-liquid separation is performed to obtain ammonium metavanadate.

[0028] In some embodiments, the amount of precipitant added is calculated by mass ratio, precipitant: vanadium ions in the vanadium solution = 4 to 5.

[0029] In some embodiments, the precipitating agent is ammonium sulfate or ammonium chloride.

[0030] Specifically, the present invention adopts sodium vanadium extraction leachate to prepare ammonium metavanadate, firstly performs pretreatment, i.e., aluminum salt desiliconization, and then precipitates under the conditions of pH 8.5-9.5 and room temperature, the precipitant is one of ammonium sulfate and ammonium chloride, the amount of the precipitant added is 4-5 (calculated by mass ratio: ammonium sulfate: vanadium concentration = 4-5), the precipitation time is 60-120min, and after precipitation, it is dried at 60-120°C to make the moisture content ≤0.1%.

[0031] Example 1 Take 1L of sodium leaching solution (vanadium concentration is 41.2g / L), add sulfuric acid to adjust the pH value to 5-7, put it on the heater for heating and stirring, continue to add sulfuric acid when the temperature is ≥60℃, adjust the pH value to about 1.8 for precipitation, add 33g of ammonium sulfate when the temperature is greater than 85℃, continue to heat to 95℃, continuously detect the pH value, add sulfuric acid appropriately, keep warm for 30min, use a circulating water pump vacuum pump for solid-liquid separation and washing, put it into a drying oven (108℃) for drying after washing to obtain ammonium polyvanadate.

[0032] Take 1L of sodium leaching solution for pretreatment, heat and stir, add 6g of aluminum sulfate to remove silicon from aluminum salt when the temperature reaches 60℃, keep warm for 30min, and separate solid and liquid after settling for 24h. Stir the supernatant (vanadium concentration 39.8g / L, Si concentration 0.018g / L, Cr concentration 3.1g / L) and add 160g of ammonium sulfate. After reacting for 80min, use a circulating water pump vacuum pump for solid-liquid separation and washing. After washing, put it into a drying oven (108℃) for drying to obtain ammonium metavanadate.

[0033] Finally, pour 20 g of dried ammonium polyvanadate (containing 49.8% vanadium, 0.064% chromium, 0.078% sulfur, 0.439% sodium, and 0.016% iron) and 40 g of ammonium metavanadate (containing 42.5% vanadium, 0.156% chromium, 0.008% sulfur, 0.02% sodium, and 0.008% iron) into the crucible and mix thoroughly. Then put the crucible into a muffle furnace and set different temperatures for calcination. The furnace door is opened by 2 to 5 cm to form an oxidizing atmosphere in the furnace for heating in the preheating and calcination stages. The temperature of the preheating section is 160°C to 350°C, the temperature of the calcining section is 350°C to less than 600°C, and the temperature increases with the passage of time. The residence time of the preheating period is controlled to be 1 hour by controlling the temperature increasing speed, and the residence time of the calcining section is controlled to be 1.5 hours. After the calcination is completed, the muffle furnace is closed, and the crucible is taken out and naturally cooled, so as to realize the preparation of a powdered vanadium pentoxide product. The vanadium pentoxide contains 99.21% vanadium, 0.097% chromium, 0.379% sodium, 0.033% sulfur, 0.01% iron, and 0.4% tetravalent vanadium (the chromium content of vanadium pentoxide prepared from ammonium metavanadate is reduced by 19%, the sodium content of vanadium pentoxide prepared from ammonium metavanadate is reduced by 13.6%, the sulfur content is reduced by 58.12%, and the tetravalent vanadium is reduced by 71.4%), and the apparent quality is excellent.

[0034] Example 2 Take 1L of sodium leaching solution (vanadium concentration is 41.2g / L), add sulfuric acid to adjust the pH value to 5-7, put it on the heater for heating and stirring, continue to add sulfuric acid when the temperature is ≥60℃, adjust the pH value to about 2, add 50g of ammonium sulfate when the temperature is greater than 85℃, continue to heat to 95℃, continuously detect the pH value, add sulfuric acid appropriately, keep warm for 30min, use a circulating water pump vacuum pump for solid-liquid separation and washing, put it into a drying oven (108℃) for drying after washing to obtain ammonium polyvanadate.

[0035] Take 1L of sodium leaching solution for pretreatment, heat and stir, add 8g of aluminum sulfate when the temperature reaches 60℃, keep warm for 30min, and separate the solid and liquid after settling for 24h. Stir the supernatant (vanadium concentration 39.8g / L, Si concentration 0.018g / L, Cr concentration 3.1g / L) and add 180g of ammonium sulfate. After reacting for 80min, use a circulating water pump vacuum pump for solid-liquid separation and washing. After washing, put it into a drying oven (108℃) for drying to obtain ammonium metavanadate.

[0036] Pour 30 g of dried ammonium polyvanadate (containing 49.88% vanadium, 0.066% chromium, 0.075% sulfur, 0.427% sodium, and 0.013% iron) and 30 g of ammonium metavanadate (containing 42.5% vanadium, 0.146% chromium, 0.007% sulfur, 0.025% sodium, and 0.009% iron) into a crucible and mix thoroughly. Then put the crucible into a muffle furnace and set different temperatures for calcination. The furnace door is opened by 2 to 5 cm to form an oxidizing atmosphere in the furnace for preheating and calcination. The temperature of the preheating section is 160° C. to less than 350° C., the temperature of the calcining section is 350° C. to less than 600° C., and the temperature increases with the passage of time. The residence time of the preheating period is controlled to be 1 hour by controlling the temperature increasing speed, and the residence time of the calcining section is controlled to be 1.5 hours. After the calcination is completed, the muffle furnace is closed, and the crucible is taken out and naturally cooled, thereby realizing the preparation of a powdered vanadium pentoxide product. The vanadium pentoxide contains 99.28% vanadium, 0.092% chromium, 0.229% sodium, 0.043% sulfur, 0.015% iron, and 0.63% tetravalent vanadium, and has excellent apparent quality (the chromium content of vanadium pentoxide prepared from ammonium metavanadate is reduced by 23.3%, and the sodium content of vanadium pentoxide prepared from ammonium metavanadate is reduced by 47.8%, the sulfur content is reduced by 45.4%, and the tetravalent vanadium is reduced by 55%).

[0037] Example 3 Take 1L of sodium leaching solution (vanadium concentration is 41.2g / L), add sulfuric acid to adjust the pH value to 5-7, put it on the heater for heating and stirring, continue to add sulfuric acid when the temperature is ≥60℃, adjust the pH value to about 2.5, add 60g of ammonium sulfate when the temperature is greater than 85℃, continue to heat to 95℃, continuously detect the pH value, add sulfuric acid appropriately, keep warm for 30min, use a circulating water pump vacuum pump for solid-liquid separation and washing, put it into a drying oven (108℃) for drying after washing to obtain ammonium polyvanadate.

[0038] Take 1L of sodium leaching solution for pretreatment, heat and stir, add 10g of aluminum sulfate when the temperature reaches 60℃, keep warm for 30min, and separate the solid and liquid after settling for 24h. Stir the supernatant (vanadium concentration 39.8g / L, Si concentration 0.018g / L, Cr concentration 3.1g / L) and add 200g of ammonium sulfate. After reacting for 80min, use a circulating water pump vacuum pump for solid-liquid separation and washing, and put it into a drying oven (108℃) for drying to obtain ammonium metavanadate.

[0039] Pour 40 g of dried ammonium polyvanadate (containing 49.93% vanadium, 0.068% chromium, 0.079% sulfur, 0.428% sodium, and 0.014% iron) and 20 g of ammonium metavanadate (containing 42.8% vanadium, 0.143% chromium, 0.009% sulfur, 0.022% sodium, and 0.009% iron) into a crucible and mix well. Then put the crucible into a muffle furnace and set different temperatures for calcination. The furnace door is opened by 2 to 5 cm to form an oxidizing atmosphere in the furnace for preheating and calcination. The temperature of the preheating section is 160°C to below 350°C, the temperature of the calcining section is 350°C to below 600°C, and the temperature increases with the passage of time. The residence time of the preheating period is controlled to be 1 hour by controlling the temperature increasing speed, and the residence time of the calcining section is controlled to be 1.5 hours. After the calcination is completed, the muffle furnace is closed, and the crucible is taken out and naturally cooled, thereby realizing the preparation of a powdered vanadium pentoxide product. The vanadium pentoxide contains 99.31% vanadium, 0.082% chromium, 0.296% sodium, 0.054% sulfur, 0.012% iron, and 0.75% tetravalent vanadium, and has excellent apparent quality (compared with the vanadium pentoxide prepared from ammonium metavanadate, the chromium content is reduced by 31.6%, and the sodium content, sodium content, sulfur content, and tetravalent vanadium content are reduced by 32.5%, 31.4%, and 46.4% respectively).

[0040] The scheme proposed by the present invention is based on the reaction mechanism of preparing vanadium pentoxide from vanadium oxide, and uses ammonium polyvanadate and ammonium metavanadate to mix and prepare vanadium pentoxide. The mixture of ammonium polyvanadate and ammonium metavanadate is more loose, which can increase the contact surface between the mixture and the air, and improve the deammoniation effect and oxidation effect. In addition, the advantages of ammonium polyvanadate and ammonium metavanadate are combined to improve the impurity content of the product. In addition, the operation process of the method is simplified, the flow is short, the operation is simplified, and the requirements for equipment are reduced.

[0041] Based on the same inventive concept, according to another aspect of the present invention, an embodiment of the present invention further provides a vanadium pentoxide, wherein the vanadium pentoxide is prepared by the method described in any one of the above embodiments.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] 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 vanadium pentoxide, characterized in that: The following steps are involved: mixing ammonium polyvanadate and ammonium metavanadate to obtain a mixture; preheating the mixture at a first temperature; The preheated mixture is calcined at a second temperature, wherein the first temperature is lower than the second temperature.

2. The method according to claim 1, characterized in that The mass ratio of the ammonium polyvanadate to the ammonium metavanadate is 0.5-2.

3. The method according to claim 1, characterized in that Preheating the mixture at a first temperature further comprises: The mixture was preheated between 160°C and 350°C for 1 to 1.5 hours.

4. The method according to claim 1, characterized in that calcining the preheated mixture at a second temperature, further comprising: The mixture was calcined between 350°C and 600°C for 1.5-2 hours.

5. The method according to claim 1, characterized in that The mixture is obtained by mixing ammonium polyvanadate and ammonium metavanadate, further comprising: Obtaining a vanadium solution and adjusting the pH value of the vanadium solution to 5 to 7 using sulfuric acid; Heat and stir and adjust the pH value to 1.8-2.5; Continue heating and add a precipitant when the temperature is 85-95°C. After precipitation for 30-60 minutes, separate the solid and liquid to obtain ammonium polyvanadate.

6. The method according to claim 5, characterized in that Calculated by mass ratio, the amount of precipitant added is, precipitant: vanadium ions in vanadium solution = 0.8~1.

5.

7. The method according to claim 1, characterized in that The mixture is obtained by mixing ammonium polyvanadate and ammonium metavanadate, further comprising: Obtain vanadium solution and add aluminum salt to remove silicon; Solid-liquid separation, take the supernatant and adjust the pH value to 8.5-9.5; A precipitant is added, and after precipitation for 60 to 120 minutes, solid-liquid separation is performed to obtain ammonium metavanadate.

8. The method according to claim 7, characterized in that Calculated by mass ratio, the amount of precipitant added is, precipitant: vanadium ions in vanadium solution = 4 to 5.

9. The method according to claim 5 or 7, characterized in that The precipitant is ammonium sulfate or ammonium chloride.

10. A vanadium pentoxide, characterized in that: The vanadium pentoxide is prepared based on the method according to any one of claims 1 to 9.

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