A synergic process for steelmaking and vanadium extraction

Abstract

The present application belongs to the technical field of steel metallurgy and comprehensive utilization of resources, and particularly relates to a collaborative process for steelmaking and vanadium extraction. The collaborative process comprises the following steps: (S1) after desulfurization treatment of vanadium-containing molten iron, the molten iron is introduced into a converter, oxygen is blown, a cooling agent and a slag forming agent are added, qualified molten steel is obtained, and vanadium-rich calciumized slag is discharged; (S2) the vanadium-rich calciumized slag is ground to obtain slag powder, the slag powder is introduced into water, under stirring, carbon dioxide is introduced for pre-carbonation, then a composite ammonium salt is added, leaching is performed, solid-liquid separation is performed, and a filter residue and a leaching solution are obtained; the composite ammonium salt is a mixture of an ammonium carbonate salt and an ammonium chloride; (S3) the leaching solution is adjusted in pH for acid precipitation, a precipitate is separated out and filtered, the filter cake is calcined, and vanadium pentoxide is obtained. The vanadium extraction process of the present application is seamlessly embedded in the steelmaking process, and a collaborative new process using clean calciumization vanadium extraction technology is adopted to realize efficient, low-cost and green steelmaking and vanadium extraction, and the recovery rate and purity of vanadium are improved.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel metallurgy and comprehensive resource utilization technology, specifically relating to a synergistic process for steelmaking and vanadium extraction. Background Technology

[0002] Vanadium is widely used in steel, aerospace, and chemical industries. The main processes for extracting vanadium from vanadium-containing molten iron are ladle extraction and converter extraction. Currently, the mainstream process for extracting vanadium from vanadium-containing molten iron in my country is the converter method, which is further divided into two types: the duplex method and the single-slag method. In the duplex method, the vanadium extraction converter and the steelmaking converter are set up independently, and the semi-steel obtained after vanadium extraction is then smelted in the steelmaking converter. The duplex method first involves oxygen blowing into the molten iron in the converter to extract vanadium, generating vanadium slag containing approximately 9-12% V₂O₅. The obtained vanadium slag requires further processing: after cooling and grinding, it is mixed with sodium salts (such as NaCl, Na₂SO₄, Na₂CO₃, etc.) and subjected to high-temperature sodium roasting at 900-1250℃ to convert vanadium into soluble sodium vanadate; the roasted slag is then leached with water and filtered to obtain a vanadium-containing solution; ammonium salts are added to the solution to precipitate vanadium, yielding ammonium vanadate; finally, the ammonium vanadate is roasted to obtain the V₂O₅ product; the semi-steel after vanadium extraction is then transferred to the steelmaking furnace for steelmaking. The dual-process method is currently the most mature and widely used model. However, it has the following drawbacks: 1. Lengthy process and complex equipment: It involves multiple processes such as vanadium extraction, steelmaking, sodium roasting, leaching, vanadium precipitation, and roasting, resulting in large equipment investment and high system failure rate; 2. The vanadium extraction process is time-consuming and has significant iron loss; 3. The vanadium slag requires secondary high-temperature sodium roasting, which consumes a huge amount of energy; 4. The sodium roasting process generates a large amount (approximately 80-100 t / t V2O5) of wastewater containing high concentrations of sodium and ammonium salts after vanadium precipitation, which is difficult to recycle completely and causes water pollution when discharged; the tailings contain harmful sodium salts and soluble hexavalent chromium and other heavy metals, making comprehensive utilization difficult, and stockpiling them occupies land and causes secondary pollution; 5. Low resource utilization rate: The tailings after vanadium extraction are not effectively utilized. The single-slag method completes the entire process of vanadium extraction and steelmaking in the same converter, which is shorter, but the vanadium recovery rate is low, making it unsuitable for large-scale production, and therefore it has not been widely promoted. The main contradiction in the single-slag process lies in thermodynamics. For vanadium extraction, the temperature needs to be controlled at 1350-1400℃ to remove vanadium and retain carbon, while steelmaking requires a temperature of around 1600℃. These different temperature requirements make it difficult to achieve the desired results for both vanadium extraction and steelmaking. Furthermore, in the single-slag process, the slag-forming agents for vanadium extraction and steelmaking are difficult to reconcile. Vanadium extraction requires high-basicity slag to fix vanadium and form calcium vanadate, while steelmaking requires moderate basicity to ensure effective desulfurization, dephosphorization, and slag fluidity.

[0003] CN104178594A discloses a method for vanadium extraction and steelmaking in a single converter. Vanadium-containing molten iron enters the converter, vanadium-containing solid waste is added, and pure oxygen blowing is used for vanadium extraction and steelmaking. During the blowing process, a composite slag-forming agent is added to form slag. The vanadium-containing slag is poured out of the furnace mouth. The vanadium-containing slag is used for vanadium extraction, while the semi-steel remaining in the converter is further blown to prepare primary steel. However, the resulting vanadium slag has a low V₂O₅ content, a low vanadium yield, and a high P₂O₅ impurity content, making purification difficult.

[0004] Therefore, developing a vanadium extraction process that can be deeply integrated with the steelmaking process, has a short process flow, low energy consumption, is clean and environmentally friendly, and has a high resource utilization rate is a technical problem that the industry urgently needs to solve. Summary of the Invention

[0005] The technical problem this invention aims to solve is as follows: Addressing the issues of long process flow, high energy consumption, heavy pollution, high iron loss, and low resource utilization in the two-step process of vanadium-containing molten iron steelmaking and vanadium extraction, this invention provides a synergistic process for steelmaking and vanadium extraction. The vanadium extraction process is seamlessly integrated into the steelmaking process, employing a novel synergistic process using clean calcification vanadium extraction technology. This achieves high efficiency, low cost, and greening of vanadium extraction from steelmaking, while improving vanadium recovery rate and purity. Specifically, this invention achieves the above objectives through the following technical solutions:

[0006] A synergistic process for steelmaking and vanadium extraction includes the following steps:

[0007] (S1) After desulfurization treatment, vanadium-containing molten iron enters the converter, is smelted with oxygen, and coolant and slag-forming agent are added to obtain molten steel and discharge vanadium-rich calcified slag.

[0008] (S2) The vanadium-rich calcified slag is ground to obtain slag powder. The slag powder is put into water and carbon dioxide is introduced under stirring conditions for precarbonation. Then, a composite ammonium salt is added, leaching is performed, and solid-liquid separation is carried out to obtain filter residue and leachate. The composite ammonium salt is a mixture of ammonium carbonate and ammonium chloride.

[0009] (S3) The pH of the leachate was adjusted for acid precipitation, the precipitate was filtered, and the filter cake was roasted to obtain vanadium pentoxide.

[0010] The collaborative process described in this invention is a collaborative process method.

[0011] Furthermore, in step (S1), the desulfurization treatment method is well known in the art, such as KR stirring desulfurization treatment, which treats the molten iron to a sulfur content below 0.01 wt%. Oxygen blowing is top-blown oxygen supply, with a supply pressure of 0.6-1.2 MPa and an oxygen flow rate of 180-240 Nm³. 3 / (t·h), oxygen supply time 10-15min. Preferably, during oxygen blowing, inert gas is also supplied from the bottom, with the inert gas flow rate being 10-20% of the oxygen supply flow rate. The inert gas is selected from nitrogen or argon. The purpose of supplying inert gas from the bottom is to enhance the stirring of the molten iron, increase the kinetic conditions, and promote the oxidation reaction to reach equilibrium quickly.

[0012] Further, in step (S1), the coolant is selected from at least one of pig iron blocks, scrap steel, vanadium slag, and iron balls; even further, the amount of coolant added is 12-17 wt% of the mass of vanadium-containing molten iron; preferably, the coolant is a mixture of iron balls and scrap steel in a mass ratio of 10-15:30-50.

[0013] Further, in step (S1), the slagging agent is a compound of calcium oxide, magnesium oxide, and manganese oxide in a mass ratio of 60-80:10-15:5-8. The particle size of the slagging agent is not particularly limited, for example, 5-50 mm. The amount of slagging agent used is 6-10 wt% of the mass of the vanadium-containing molten iron. Preferably, the slagging agent is added in batches: 50-65 wt% of the total slagging agent is added in the initial blowing stage (0-3 min); 30-40 wt% of the total slagging agent is added in the middle blowing stage (3-8 min); and the remaining slagging agent is added at the end of the blowing stage (1-2 min before the end of blowing). The coolant needs to be added all at once in the initial stage, while the compound slagging agent is added in batches. The heat release of the converter blowing is mainly concentrated in the early stage; adding all the coolant at once minimizes temperature fluctuations throughout the blowing process and avoids excessively high temperatures that could lead to converter erosion. By adding the composite slag-forming agent in batches, the alkalinity of the system is maintained within an optimal range, allowing as much vanadium in the molten iron as possible to be converted into calcium vanadate and enter the steel slag. If all the slag-forming agent is added at the beginning, the initial alkalinity will be too high, making slag formation difficult; adding it in batches also ensures desulfurization and dephosphorization effects. This invention uses a composite slag-forming agent with specific components and proportions, where the components work synergistically to balance slag fluidity and desulfurization and dephosphorization effects.

[0014] Furthermore, in step (S1), at the end of the oxygen blowing process, the final temperature is controlled at 1550-1650℃.

[0015] Further, in step (S2), the particle size of the fine powder is 100-300 mesh, for example, 200 mesh. A suitable particle size can increase the yield of vanadium. If the particle size is too large, the solid-liquid mass transfer efficiency is low, the reaction is incomplete, and even extending the reaction time will not further improve the yield. The solid-liquid ratio of the slag powder added to the water is 1:5-10, and the stirring speed is 200-400 rpm.

[0016] Further, in step (S2), the carbon dioxide flow rate is such that the system pressure is 0.5-1.0 MPa, and the precarbonation time is 8-12 h; the ammonium carbonate salt is selected from at least one of ammonium carbonate and ammonium bicarbonate. Even further, the mass ratio of ammonium carbonate salt to ammonium chloride is 20-30:1-2.

[0017] Adding ammonium carbonate leaches vanadium from calcium vanadate in the form of soluble ammonium vanadate. Taking ammonium carbonate as an example, the reaction formula is as follows:

[0018] Ca3(VO4)2 + 3(NH4)2CO3 →2(NH4)3VO4+ 3CaCO3↓

[0019] Ca(VO3)2 + (NH4)2CO3 →2NH4VO3+ CaCO3↓

[0020] The inventors unexpectedly discovered that adding a small amount of ammonium chloride along with ammonium carbonate significantly increased the yield of vanadium. This is likely because ammonium chloride reacts with calcium silicate and calcium carbonate to form soluble calcium chloride and ammonia gas. The combined effect of these two processes disrupts the surface coating structure of vanadium-containing minerals, promoting vanadium release and thus increasing the vanadium yield. A possible reaction formula is as follows:

[0021] 3CaO·SiO2+ 6NH4Cl→3CaCl2+ 6NH3↑ + SiO2 + 3H2O

[0022] 2NH4Cl+CaCO3→CaCl2+ 2NH3↑ + CO2↑ + H2O

[0023] Furthermore, in step (S2), the amount of composite ammonium salt added is 10-15 wt% of the mass of vanadium-rich calcified slag.

[0024] Furthermore, in step (S2), the leaching is a two-stage leaching process. First, the leaching is carried out by stirring at 20-30℃ for 5-10 hours, and then the temperature is raised to 40-80℃ and kept at that temperature for 5-10 hours.

[0025] The vanadium-rich calcified slag contains 2-3 wt% vanadium (V₂O₅), with low V content and high Ca content. This vanadium is dispersed in various mineral phases, mainly encapsulated in calcium silicate and calcium ferrite, making it difficult to process. This type of vanadium-rich calcified slag is unsuitable for roasting and acid leaching, as these processes are time-consuming, generate polluting gases, have low vanadium yields, and are not industrially economical. This invention creatively proposes a pre-carbonation process under a carbon dioxide atmosphere. During this process, the calcium oxide in the vanadium-rich calcified slag is converted into calcium carbonate. Calcium carbonate has a lower density than calcium oxide, resulting in a certain degree of volume expansion. This expands the dense slag phase, creating a porous structure, which is beneficial for subsequent vanadium leaching and its conversion into soluble ammonium vanadate. This invention, through pre-carbonation with carbon dioxide, significantly improves the vanadium yield and eliminates the need for sodium roasting and acid leaching, resulting in lower costs and easier industrialization.

[0026] Further, in step (S3), the pH is adjusted to 2-3 using dilute hydrochloric acid or dilute sulfuric acid, causing vanadium to precipitate as ammonium polyvanadate. After washing the precipitate with water and drying it, it is calcined at 450-600℃ for 1-3 hours to obtain an orange-yellow flaky product, which is V2O5.

[0027] In step (S2), the filter residue is mostly calcium carbonate, which can be prepared into a slurry for flue gas desulfurization; in step (S3), the roasting flue gas is absorbed by water to obtain ammonia water, which can be used to prepare ammonium carbonate / ammonium bicarbonate for recycling.

[0028] Compared with the prior art, the present invention achieves the following beneficial effects:

[0029] I. High Steelmaking Efficiency: The process of this invention eliminates a dedicated vanadium extraction step of approximately 30 minutes and the semi-steel transfer process, significantly shortening the steelmaking cycle and improving production efficiency. Simultaneously, it avoids temperature drops and molten iron loss during semi-steel transfer, reducing losses by 50-80 kg / t. 钢 Iron loss.

[0030] II. Simplified Process Flow: Vanadium extraction eliminates the need for high-temperature sodium roasting and associated environmental protection facilities, resulting in a shorter process flow and fewer pieces of equipment, significantly reducing fixed asset investment and equipment maintenance costs. Furthermore, the energy-intensive sodium roasting step of vanadium slag is completely eliminated, and subsequent leaching is carried out at low temperatures, reducing overall energy consumption by more than 40%.

[0031] III. The process of this invention is green and environmentally friendly: The process of this invention does not generate toxic gases such as Cl2 and SO2; the process is mainly a closed-loop circulation of ammonium salt solution, with no high-salt wastewater discharge; the vanadium extraction tailings are mainly harmless calcium carbonate products, which can be completely consumed as a desulfurizing agent, with no solid waste stockpiling; the ammonia gas generated from vanadium precipitation and roasting is effectively recovered and returned to the leaching process, realizing the internal circulation of nitrogen elements within the system.

[0032] Fourth, this invention employs a specific multi-stage vanadium extraction process for vanadium-rich calcified slag. First, pre-carbonation is carried out under a carbon dioxide atmosphere, and then ammonium carbonate is added to convert vanadium into soluble ammonium vanadate, which significantly improves the vanadium yield. Detailed Implementation

[0033] The following will further illustrate the above-described embodiments of the present invention with reference to specific examples. However, those skilled in the art will understand that the following examples are only for illustrating the present invention, and all technologies based on the above content of the present invention fall within the scope of the present invention.

[0034] The vanadium-containing molten iron used in this invention has the following contents: V content 0.2wt%, C content 4.26wt%, Si content 0.21wt%, Mn content 0.26wt%, P content 0.06wt%, and S content 0.05%.

[0035] Calcium oxide, magnesium oxide, and manganese oxide are used as slag-forming agents with a particle size of approximately 30 mm.

[0036] Example 1

[0037] (S1) After 100 tons of molten iron is desulfurized using the KR method, the sulfur content is 0.008wt%. It is then added to a top-and-bottom blowing converter, with oxygen supplied at a flow rate of 200 Nm³. 3 / (t·h), bottom blowing is nitrogen, nitrogen flow rate is 20Nm 3 At a temperature of / (t·h), 15 tons of iron balls and scrap steel were added as coolant in a mass ratio of 1:3, along with 4 tons of composite slagging agent. After 5 minutes of blowing, 3.2 tons of composite slagging agent were added, and after 12 minutes of blowing, 0.8 tons of composite slagging agent were added. The composite slagging agent is a mixture of calcium oxide, magnesium oxide, and manganese oxide (with a particle size of approximately 30mm) in a mass ratio of 10:1.5:1. After 15 minutes of blowing, the final temperature was controlled at 1650℃. Qualified molten steel was discharged for further refining. The molten steel contained 0.03wt% V, 0.08wt% C, ≤0.01wt% P, and ≤0.005wt% S. Vanadium-rich calcified slag was discharged, containing 2.83wt% V₂O₅, 18.61wt% TFe, 41.68wt% CaO, and 10.38wt% SiO₂.

[0038] (S2) Grind the vanadium-rich calcium slag to 200 mesh, take 10 kg of finely ground slag, add it to water at a solid-liquid ratio of 1:10, and under stirring at 200 rpm, introduce CO2 gas to make the system pressure 0.5 MPa for pre-carbonation. The pre-carbonation time is 10 h. Stop introducing CO2, then add 1 kg of composite ammonium salt, which is a mixture of ammonium carbonate and ammonium chloride at a mass ratio of 20:1. Maintain stirring speed of 200 rpm and leach at room temperature of 25℃ for 8 h. Then raise the temperature to 60℃ and continue leaching for 8 h. After cooling, separate the solid and liquid to obtain leachate and filter residue. The filter residue is mainly calcium carbonate, which can be used for flue gas desulfurization in power plants with a desulfurization efficiency of over 90%.

[0039] (S3) The pH of the leachate was adjusted to 2.6 with dilute sulfuric acid, resulting in the precipitation of a red precipitate. After filtration, an ammonium polyvanadate filter cake was obtained. This cake was then calcined at 550℃ for 3 hours to obtain an orange-yellow powder, which is the product V2O5. The calcination flue gas was absorbed by water to obtain ammonia water, which can be used to manufacture ammonium carbonate.

[0040] Example 2

[0041] The conditions are the same as in Example 1, except that in step (S1), the composite slag-forming agent is a mixture of calcium oxide, magnesium oxide and manganese oxide in a mass ratio of 12:3:1.

[0042] Example 3

[0043] The conditions are the same as in Example 1, except that in step (S1), the composite slag-forming agent is a mixture of calcium oxide and magnesium oxide in a mass ratio of 10:1.5.

[0044] Example 4

[0045] The conditions are the same as in Example 1, except that in step (S1), the slag-forming agent is entirely calcium oxide.

[0046] Example 5

[0047] The conditions are the same as in Example 1, except that in step (S2), CO2 gas is introduced to make the system pressure 0.8 MPa for precarbonation, and the precarbonation time is 8 hours.

[0048] Example 6

[0049] The conditions are the same as in Example 1, except that in step (S2), the amount of compound ammonium salt used is 1 kg, and the compound ammonium salt is a mixture of ammonium carbonate and ammonium chloride in a mass ratio of 15:1.

[0050] Example 7

[0051] The conditions are the same as in Example 1, except that in step (S2), CO2 gas is introduced to make the system pressure 0.3 MPa for precarbonation, and the precarbonation time is 12 hours.

[0052] Comparative Example 1

[0053] Other conditions are the same as in Example 1, except that step (S2) is changed to: grinding the vanadium-rich calcified slag to 200 mesh, taking 10 kg of the finely ground slag, adding it to water at a solid-liquid ratio of 1:10, stirring at 200 rpm, introducing CO2 gas to make the system pressure 0.5 MPa, adding 1 kg of composite ammonium salt (ammonium carbonate and ammonium chloride in a mass ratio of 20:1), maintaining a stirring speed of 200 rpm, leaching at 25°C for 16 hours, stopping the introduction of CO2, then raising the temperature to 60°C and continuing leaching for 8 hours, cooling and separating the solid and liquid to obtain leachate and filter residue. That is, the first stage of leaching at room temperature and the introduction of carbon dioxide gas are carried out simultaneously.

[0054] Comparative Example 2

[0055] Other conditions are the same as in Example 1, except that step (S2) is changed to: grinding the vanadium-rich calcified slag to 200 mesh, taking 10 kg of finely ground slag, adding it to water at a solid-liquid ratio of 1:10, and adding 1 kg of composite ammonium salt under stirring at 200 rpm. The composite ammonium salt is a mixture of ammonium carbonate and ammonium chloride at a mass ratio of 20:1. The stirring speed is maintained at 200 rpm, and the mixture is leached at room temperature of 25°C for 16 hours. Then the temperature is raised to 60°C and leached for another 8 hours. After cooling, the solid and liquid are separated to obtain leachate and filter residue.

[0056] Comparative Example 3

[0057] The other conditions are the same as in Example 1, except that in step (S2), all the complex ammonium salts are ammonium carbonate and no ammonium chloride is added.

[0058] The vanadium yield and V2O5 of the above-described embodiments and comparative examples were tested, and the results are shown in Table 1 below.

[0059] The yield (V) is calculated using the following formula:

[0060]

[0061] Table 1. Vanadium extraction effect test results

[0062]

[0063] As can be seen, the process of this invention can efficiently extract vanadium from molten iron with high yield, eliminating the need for a separate process for extracting vanadium from vanadium-containing molten iron as is conventional. The vanadium yield is consistently above 89%, with the preferred embodiment reaching over 93%. This invention is environmentally friendly, with minimal Fe loss, and is a synergistic process for vanadium extraction in steelmaking, suitable for industrial production.

Claims

1. A synergistic process for steelmaking and vanadium extraction, characterized in that, Includes the following steps: (S1) After desulfurization treatment, vanadium-containing molten iron enters the converter, is smelted with oxygen, and coolant and slag-forming agent are added to obtain molten steel and discharge vanadium-rich calcified slag. (S2) The vanadium-rich calcified slag is ground to obtain slag powder. The slag powder is put into water and carbon dioxide is introduced under stirring conditions for precarbonation. Then, a composite ammonium salt is added, leaching is performed, and solid-liquid separation is carried out to obtain filter residue and leachate. The composite ammonium salt is a mixture of ammonium carbonate and ammonium chloride. (S3) The pH of the leachate was adjusted for acid precipitation, the precipitate was filtered, and the filter cake was roasted to obtain vanadium pentoxide.

2. The collaborative process according to claim 1, characterized in that, In step (S1), the desulfurization treatment reduces the sulfur content of the molten iron to below 0.01 wt%; the oxygen supply is top-blown, with a supply pressure of 0.6-1.2 MPa and an oxygen flow rate of 180-240 Nm³. 3 / (t·h), oxygen supply time 10-15min; preferably, while supplying oxygen for blowing, inert gas is also supplied from the bottom, the inert gas flow rate is 10-20% of the oxygen supply flow rate, and the inert gas is selected from nitrogen or argon.

3. The collaborative process according to claim 1, characterized in that, In step (S1), the coolant is selected from at least one of pig iron blocks, scrap steel, vanadium slag, and iron balls; further, the amount of coolant added is 12-17 wt% of the mass of vanadium-containing molten iron; preferably, the coolant is a mixture of iron balls and scrap steel in a mass ratio of 10-15:30-50.

4. The collaborative process according to claim 1, characterized in that, In step (S1), the slag-forming agent is a compound of calcium oxide, magnesium oxide and manganese oxide in a mass ratio of 60-80:10-15:5-8; preferably, the amount of slag-forming agent is 6-10 wt% of the mass of vanadium-containing molten iron.

5. The collaborative process according to claim 1, characterized in that, The slagging agent is added in batches. In the early stage of blowing (0-3 min), 50-65 wt% of the total slagging agent is added; in the middle stage of blowing (3-8 min), 30-40 wt% of the total slagging agent is added; and in the end of blowing (1-2 min before the end of blowing), the remaining slagging agent is added.

6. The collaborative process according to claim 1, characterized in that, In step (S1), at the end of the oxygen blowing process, the final temperature is controlled at 1550-1650℃.

7. The collaborative process according to claim 1, characterized in that, In step (S2), the fine powder is ground to a particle size of 100-300 mesh; the solid-liquid ratio of the slag powder added to the water is 1:5-10, and the stirring speed is 200-400 rpm.

8. The collaborative process according to claim 1, characterized in that, In step (S2), the carbon dioxide flow rate is increased to make the system pressure 0.5-1.0 MPa, the ammonium carbonate salt is selected from at least one of ammonium carbonate and ammonium bicarbonate, and the precarbonation time is 8-12 h.

9. The collaborative process according to claim 1, characterized in that, The mass ratio of ammonium carbonate to ammonium chloride is 20-30:1-2; further, in step (S2), the amount of composite ammonium salt added is 10-15 wt% of the mass of vanadium-rich calcified slag.

10. The collaborative process according to claim 1, characterized in that, In step (S2), the leaching is a two-stage leaching process. First, the leaching is carried out by stirring at 20-30℃ for 5-10 hours, and then the temperature is raised to 40-80℃ and kept at that temperature for 5-10 hours. Further, in step (S3), the pH is adjusted to 2-3 using dilute hydrochloric acid or dilute sulfuric acid, so that vanadium forms a precipitate as ammonium polyvanadate. After the precipitate is washed with water and dried, it is calcined at 450-600℃ for 1-3 hours to obtain an orange-yellow flaky product, which is V2O5.

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