Method for recovering vanadium from waste petroleum catalyst

Abstract

The invention relates to the technical field of vanadium metallurgy, and discloses a method for recovering vanadium from a waste petroleum catalyst, which comprises the following steps: mixing the waste petroleum catalyst with an alkaline solution, stirring and leaching, and filtering and separating to obtain aluminum-containing residue and vanadium-containing leachate; acid is added into the vanadium-containing leaching solution to adjust the pH value, insoluble substances are filtered out, and a purified leaching solution is obtained; an oxidizing agent is added into the purified leachate for oxidation, then a vanadium precipitation agent is added, stirring and filtering are carried out, and vanadium-containing precipitates are obtained; and washing, drying and calcining the vanadium-containing precipitate to obtain vanadium pentoxide. According to the method, vanadium is leached as much as possible and aluminum is left in residues as much as possible by adjusting the concentration, dosage and leaching time of an alkaline solution, a purified leaching solution is obtained, then acid is added for adjustment, and finally a V2O5 product is obtained in an oxidizing roasting mode. The vanadium element in the waste petroleum catalyst can be effectively recovered, and the effects of saving resources and reducing environmental pollution are achieved.

Description

Technical Field

[0001] The invention relates to the technical field of vanadium metallurgy, and in particular to a method for recovering vanadium from waste petroleum catalysts. Background Art

[0002] Vanadium is an important strategic metal resource and is widely used in the fields of steel and alloys. In recent years, with the development of industrial technology, vanadium has gradually been used in the fields of flow batteries, fine chemicals, industrial catalysis, etc. The main sources of vanadium resources are vanadium-containing ores such as vanadium-titanium magnetite and stone coal. However, with the expansion of vanadium's application areas and the increase in demand, the amount of vanadium mined has continued to increase, resulting in a decrease in the stock of vanadium-containing ores. Therefore, it is necessary to explore methods for extracting vanadium from other vanadium-containing raw materials.

[0003] Some industrial waste catalysts are rich in vanadium, such as waste petroleum catalysts and SCR (selective catalytic reduction) waste catalysts. Extracting vanadium from them can not only effectively utilize vanadium resources, but also reduce environmental pollution. Among them, petroleum industry catalysts are mainly based on alumina as a carrier. During the hydrodesulfurization process of crude oil, the vanadium is deposited on the catalyst in the form of vanadium sulfide (V3S4). When the vanadium content reaches a certain level, the catalyst fails, and the waste petroleum catalyst formed can be used as a raw material for vanadium extraction. The recovery of vanadium from waste petroleum catalysts involves two methods: pyrolysis and hydrolysis. However, the existing method consumes a lot of energy and generates harmful gas SO2. The technology for extracting vanadium from waste petroleum catalysts needs to be optimized.

[0004] Therefore, there exists a need in the art for improved methods of recovering vanadium from spent petroleum catalysts. Summary of the invention

[0005] In view of this, the purpose of the embodiment of the present invention is to provide a method for recovering vanadium from waste petroleum catalysts. The present invention can effectively recover the vanadium element in the waste petroleum catalysts, thereby saving resources and reducing environmental pollution.

[0006] Based on the above purpose, an embodiment of the present invention provides a method for recovering vanadium from a waste petroleum catalyst, comprising: S1: mixing the waste petroleum catalyst with an alkaline solution, stirring and leaching, and filtering and separating to obtain aluminum-containing residue and vanadium-containing leaching solution; S2 adding acid to the vanadium-containing leaching solution to adjust the pH, filtering to remove insoluble matter, and obtaining a purified leaching solution; S3: adding an oxidant to the purified leaching solution for oxidation, then adding a vanadium precipitating agent, stirring, and filtering to obtain a vanadium-containing precipitate; S4 washes, dries and calcines the vanadium-containing precipitate to obtain vanadium pentoxide.

[0007] In some embodiments, in S1, the alkaline solution is any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide solutions, or a mixed solution of any two to three of them.

[0008] In some embodiments, the OH in the alkaline solution - The concentration is 0.2~2mol / L.

[0009] In some embodiments, in S1, the liquid-to-solid ratio of the alkaline solution to the waste petroleum catalyst is 5-20 mL / g.

[0010] In some embodiments, in S1, the stirring leaching time is 0.5 to 1 hour.

[0011] In some embodiments, in S2, the added acid is any one or more of sulfuric acid, hydrochloric acid, and nitric acid.

[0012] In some embodiments, in S2, the pH of the solution is adjusted to 8-9.

[0013] In some embodiments, in S3, the added oxidant is any one or more of hydrogen peroxide, peracetic acid, and sodium hypochlorite.

[0014] In some embodiments, in S3, the vanadium precipitating agent is any one or more of ammonium sulfate, ammonium chloride, ammonium nitrate, and ammonium acetate.

[0015] In some embodiments, in S4, the calcination temperature is 500-600° C., and the calcination time is 2-3 hours.

[0016] The present invention has at least the following beneficial technical effects: Waste petroleum catalysts often use alumina as a carrier. If the aluminum content in the leachate is too high, it will affect the vanadium precipitation process and cause the purity of the vanadium-containing precipitation to decrease. Therefore, the present invention first adjusts the concentration, dosage and leaching time of the alkaline solution to make the vanadium leached as much as possible and the aluminum remain in the residue as much as possible to obtain a purified leachate. Then, acid is added to adjust the pH to remove the remaining aluminum and a small amount of other impurities in the purified leachate. In the case of low vanadium valence in the purified leachate, an oxidant is used to oxidize it and ammonium salt vanadium is precipitated under weak alkaline conditions. This is because when the pH is 8-9, +5 valence vanadium is converted into V4O 12 4- VO3 - Exists in the form of NH 4+ Combined to form NH4VO3 precipitate, while molybdenum is MoO4 2- The vanadium element in the waste petroleum catalyst can be effectively recovered, thereby saving resources and reducing environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] 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.

[0018] Figure 1 The present invention provides a flow chart of an embodiment of a method for recovering vanadium from waste petroleum catalysts. DETAILED DESCRIPTION

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

[0020] The terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions; the terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects rather than to describe a specific order. "Multiple" means two or more, unless otherwise clearly and specifically defined.

[0021] In addition, reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0022] The petroleum industry is an important industry in the world, and crude oil hydrodesulfurization is a key link in the oil refining process. In this process, vanadium will be deposited on the catalyst with alumina as the carrier in the form of vanadium sulfide, and with use, the vanadium content gradually increases, causing the catalyst to fail. The large-scale and continuous nature of the petroleum industry ensures a stable supply of waste petroleum catalysts as raw materials for vanadium extraction. In addition, vanadium extraction from waste petroleum catalysts is a way to recycle resources and reduce the emission of solid waste. If waste petroleum catalysts are not treated for vanadium extraction and are directly discarded, a large amount of land will be occupied, and the heavy metals and other harmful substances in them may pollute the environment such as soil and water.

[0023] The present invention provides a method for recovering vanadium from waste petroleum catalysts, which specifically comprises the following steps: S1 Leaching and aluminum removal: Mix the waste petroleum catalyst with an alkaline solution, stir and leach, filter and separate the aluminum-containing residue, and obtain a leachate containing vanadium and a small amount of impurity ions (e.g., molybdenum); S2 purification and impurity removal: adding acid to the solution to adjust the pH, filtering to remove insoluble matter, and obtaining a purified leachate; S3 vanadium precipitation: adding an oxidant to the purified leaching solution to oxidize the vanadium in the solution to +5 valence, then adding a vanadium precipitation agent, stirring, filtering to obtain a vanadium-containing precipitate; S4 calcination: washing, drying and calcining the vanadium-containing precipitate to obtain vanadium pentoxide.

[0024] Furthermore, in S1, under appropriate alkaline conditions, vanadium sulfide in the waste petroleum catalyst can be leached out before alumina, and the vanadium continues to remain in a low-valent state after leaching. After selective leaching, the solid residue is mainly unreacted alumina and other insoluble impurities. After filtration, the vanadium-containing leachate and the solid residue are separated. When the purified leachate is used in the vanadium precipitation process, the vanadium precipitation reaction can be carried out more effectively due to the reduction of aluminum content and other impurities.

[0025] Furthermore, the alkaline solution in S1 can be sodium hydroxide, potassium hydroxide, calcium hydroxide solution or a mixed solution containing 2 to 3 of these solutes, wherein OH - The concentration is 0.2-2 mol / L. In some embodiments, in S1, the liquid-to-solid ratio of the alkaline solution to the catalyst solid is 5-20 mL / g. Further, in S1, the stirring leaching time is 0.5-1 h. Preferably, the stirring leaching time is 1 h.

[0026] In S2, as the acid is added, the pH of the solution decreases, and the aluminate ions combine with the hydrogen ions to form aluminum hydroxide precipitates. Aluminum hydroxide is an amphoteric hydroxide, and its solubility is low within a certain range. When adjusted to a suitable value, the aluminum hydroxide precipitate will precipitate from the solution, thereby achieving the purpose of removing aluminum. Further, in S2, the added acid can be one or more of sulfuric acid, hydrochloric acid, and nitric acid. Further, in S2, the pH of the solution is adjusted to 8~9. By adding acid to adjust the operation of removing aluminum, the aluminum content in the leachate can be reduced to a very low level. This is extremely important for the subsequent vanadium precipitation process, because the low aluminum content can effectively avoid the formation of aluminum-vanadium mixed precipitation during vanadium precipitation and improve the purity of the vanadium-containing precipitation.

[0027] Furthermore, in S3, the added oxidant is one or more of hydrogen peroxide, peracetic acid, and sodium hypochlorite. When the oxidant is added to the purified leachate, the oxidant will take away electrons from the vanadium ions, increasing their valence. For example, using hydrogen peroxide as an oxidant, under the pH conditions of the present invention, the reaction formula for oxidizing vanadium from +4 valence to +5 valence is: 2VO3 2-+H2O2==2VO3 - + 2OH - .

[0028] Furthermore, in S3, the vanadium precipitant used is one or more of ammonium sulfate, ammonium chloride, ammonium nitrate, and ammonium acetate. In the solution, ammonium ions react with oxidized +5-valent vanadium ions to obtain ammonium metavanadate. Sodium metavanadate is a poorly soluble precipitate at a pH of 8-9. MoO4 2- It exists in the solution in the form of ions, thus achieving the separation of vanadium and molybdenum.

[0029] Furthermore, stirring can be further performed during the precipitation process, and stirring plays an important role in the vanadium precipitation process. By stirring, the vanadium precipitation agent and the vanadium-containing solution can be fully mixed, increasing the contact opportunity between the reactants, thereby accelerating the precipitation reaction.

[0030] Stirring can also prevent uneven precipitation due to excessive local concentration. If there is not enough stirring, local precipitation may be too fast while other areas may not be completely precipitated, affecting the efficiency and quality of vanadium precipitation.

[0031] Furthermore, after washing the vanadium-containing precipitate, it contains a certain amount of water. The drying process mainly evaporates the water by heating, thereby reducing the water content in the precipitate to facilitate subsequent calcination.

[0032] Ammonium metavanadate undergoes thermal decomposition during the calcination process. At high temperatures, the ammonium ions in the ammonium metavanadate decompose to produce ammonia gas and release water molecules at the same time. The resulting ammonium polyvanadate is further decomposed and oxidized to produce vanadium pentoxide.

[0033] In S4, the calcination temperature is 500-600°C. For the calcination of ammonium metavanadate, this temperature range can ensure its full decomposition. The calcination time is usually determined according to the amount of materials and the performance of the calcination equipment, and the general calcination time is 2-3 hours. Commonly used calcination equipment includes muffle furnace, rotary kiln, etc. In the calcination process of the present invention, it is necessary to ensure that the amount of oxygen is sufficient to promote the formation of vanadium pentoxide, for example, keep the air circulation or continuously inject oxygen during the calcination process. The present invention will be further explained below in conjunction with specific embodiments.

[0034] The waste petroleum catalyst of the present invention is taken from a certain oil refinery and has been pre-treated by deoiling and crushing. The particle size of the waste petroleum catalyst after crushing is less than 500 μm, and the content of main elements is shown in Table 1.

[0035] Table 1 Element content in waste petroleum catalyst

[0036] Example 1 Take a certain amount of waste petroleum catalyst, add 1 mol / L NaOH solution at a liquid-solid ratio of 10mL / g for leaching, stir and leach for 30 minutes, separate insoluble impurities, and obtain a leachate. Add sulfuric acid to the leachate to adjust the pH to 9, filter and separate insoluble impurities, and obtain a purified leachate. Add sufficient hydrogen peroxide to the purified leachate, and then add sufficient ammonium sulfate to precipitate vanadium. After the vanadium precipitation is completed, separate the vanadium-containing precipitate. Calcine the precipitate at 500℃ for 3h to obtain V2O5.

[0037] The vanadium pentoxide obtained in this example was tested and the purity of V2O5 was found to be 99.1%.

[0038] Example 2 Take a certain amount of waste petroleum catalyst, add 0.5 mol / L NaOH solution at a liquid-solid ratio of 20mL / g for leaching, stir and leach for 45min, separate insoluble impurities, and obtain leachate. Add sulfuric acid to the leachate to adjust the pH to 8.5, filter and separate insoluble impurities, and obtain purified leachate. Add sufficient hydrogen peroxide to the purified leachate, and then add sufficient ammonium chloride to precipitate vanadium. After the precipitation of vanadium is completed, separate the vanadium-containing precipitate. Calcine the precipitate at 600℃ for 2h to obtain V2O5.

[0039] The vanadium pentoxide obtained in this example was tested and the purity of V2O5 was found to be 99.3%.

[0040] Example 3 Take a certain amount of waste petroleum catalyst, add 2 mol / L NaOH solution at a liquid-solid ratio of 5mL / g for leaching, stir and leach for 45min, separate insoluble impurities, and obtain leachate. Add sulfuric acid to the leachate to adjust the pH to 8, filter and separate insoluble impurities, and obtain purified leachate. Add sufficient sodium hypochlorite to the purified leachate, and then add sufficient ammonium acetate to precipitate vanadium. After the precipitation of vanadium is completed, separate the vanadium-containing precipitate. Calcine the precipitate at 550℃ for 2.5h to obtain V2O5.

[0041] The vanadium pentoxide obtained in this example was tested and the purity of V2O5 was found to be 99.0%.

[0042] Example 4 Take a certain amount of waste petroleum catalyst, add 0.2 mol / L NaOH solution at a liquid-solid ratio of 10mL / g for leaching, stir and leach for 1h, separate insoluble impurities, and obtain leachate. Add sulfuric acid to the leachate to adjust the pH to 9, filter and separate insoluble impurities, and obtain purified leachate. Add sufficient hydrogen peroxide to the purified leachate, and then add sufficient ammonium sulfate to precipitate vanadium. After the precipitation of vanadium is completed, separate the vanadium-containing precipitate. Calcine the precipitate at 550℃ for 2.5h to obtain V2O5.

[0043] The vanadium pentoxide obtained in this example was tested and the purity of V2O5 was found to be 98.6%.

[0044] In summary, the present invention first adjusts the concentration, dosage and leaching time of the alkaline solution to make vanadium leached as much as possible and aluminum remain in the residue as much as possible to obtain a purified leachate. Then, acid is added to adjust the pH to remove the remaining aluminum and a small amount of other impurities in the purified leachate. In the case where the vanadium valence state of the purified leachate is low, an oxidant is used to oxidize it and ammonium salt precipitation of vanadium is carried out under weak alkaline conditions. This is because when the pH is 8-9, +5 valence vanadium is converted into V4O 12 4- VO3 - Exists in the form of NH 4+ Combined to form NH4VO3 precipitate, while molybdenum is MoO4 2- The vanadium element in the waste petroleum catalyst can be effectively recovered, thereby saving resources and reducing environmental pollution.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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 recovering vanadium from waste petroleum catalysts, characterized in that: include: S1: mixing the waste petroleum catalyst with an alkaline solution, stirring and leaching, and filtering and separating to obtain aluminum-containing residue and vanadium-containing leaching solution; S2 adding acid to the vanadium-containing leachate to adjust the pH, filtering to remove insoluble matter, and obtaining a purified leachate; S3: adding an oxidant to the purified leachate for oxidation, then adding a vanadium precipitating agent, stirring, and filtering to obtain a vanadium-containing precipitate; S4: washing, drying and calcining the vanadium-containing precipitate to obtain vanadium pentoxide.

2. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S1, the alkaline solution is any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide solutions, or a mixed solution of any two to three of them.

3. The method for recovering vanadium from waste petroleum catalyst according to claim 2, characterized in that: The OH in the alkaline solution - The concentration is 0.2~2 mol / L.

4. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S1, the liquid-to-solid ratio of the alkaline solution to the waste petroleum catalyst is 5-20 mL / g.

5. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S1, the stirring leaching time is 0.5~1h.

6. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S2, the added acid is any one or more of sulfuric acid, hydrochloric acid, and nitric acid.

7. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S2, the pH of the solution is adjusted to 8-9.

8. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S3, the added oxidant is any one or more of hydrogen peroxide, peracetic acid, and sodium hypochlorite.

9. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S3, the vanadium precipitating agent is any one or more of ammonium sulfate, ammonium chloride, ammonium nitrate, and ammonium acetate.

10. The method for recovering vanadium from waste petroleum catalyst according to claim 1, characterized in that: In S4, the calcination temperature is 500-600°C, and the calcination time is 2-3 hours.

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