Method for efficiently separating vanadium and iron in iron vanadate slag

Abstract

The invention belongs to the technical field of wet vanadium extraction, and particularly relates to a method for efficiently separating vanadium and iron in iron vanadate slag. The method comprises the following steps: quickly adding the iron vanadate slag into an alkaline solution with the temperature of 30-100 DEG C for stirring and leaching, controlling the temperature of reaction slurry, reacting for 2-20 minutes, immediately adding ferrite for magnetizing reaction to obtain black slurry, performing magnetic suction sedimentation on the slurry for the sedimentation time of less than 20 minutes until the sedimentation liquid level is clear, performing magnetic suction filtration and separation on a lower-layer precipitation phase, and filtering and separating the lower-layer precipitation phase to obtain the iron vanadate slag. The filtering time is less than 15 minutes, filtrate and supernate are mixed into vanadium-containing alkali liquor, the recovery rate of vanadium reaches 95% or above, the vanadium-containing alkali liquor can be directly used as a raw material for preparing high-purity vanadium pentoxide, and a filter cake is washed with water and then used as a raw material for ironmaking.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrometallurgical separation, and relates to a method for efficiently separating vanadium and iron in iron vanadate slag. BACKGROUND

[0002] At present, the industrial vanadium extraction process mainly adopts the chemical precipitation method, including hydrolysis vanadium precipitation, ammonium salt vanadium precipitation, calcium salt vanadium precipitation and iron salt vanadium precipitation. Among them, the ammonium salt vanadium precipitation is the best vanadium precipitation process at present. However, due to the complex raw material system, especially the fact that the acid leaching solution often contains a large amount of iron elements, the iron salt vanadium precipitation is often widely used as a preliminary enrichment method for vanadium. The iron vanadate slag, as an intermediate product for recovering vanadium by iron salt, has the problems of large slag quantity, low vanadium content and low value, and therefore, it is of great economic significance to further purify and recover vanadium from the iron vanadate slag.

[0003] Patent No. CN110273072B discloses a method for separating and recovering vanadium and iron from iron vanadate. The method comprises the following steps: slushing the iron vanadate and a reducing agent, adjusting the pH of the slurry to 0.8-3, performing a reduction reaction, separating, and obtaining a leaching solution; adjusting the pH of the leaching solution to 3-4, performing an iron precipitation reaction, and performing solid-liquid separation to obtain a vanadium-containing filtrate and iron hydroxide; adjusting the pH of the vanadium-containing filtrate to 5-7, performing a vanadium precipitation reaction, and performing solid-liquid separation to obtain a vanadium precipitate; and drying and calcining the vanadium precipitate to obtain vanadium pentoxide. By adopting the process route of reducing agent reduction-acidic impurity removal-alkaline iron precipitation-alkaline vanadium precipitation, the vanadium and iron in the iron vanadate are separated and recovered. However, the method has a long process flow, needs to be adjusted for pH multiple times and needs to be subjected to solid-liquid separation multiple times, and the steps are complicated, and the recovery rate of vanadium is low.

[0004] CN104630485A discloses a method for extracting vanadium from iron vanadate mud. The method comprises the following steps: mixing the iron vanadate mud with water and alkali, reacting and dissolving out to obtain a mixed slurry; filtering and separating the mixed slurry to obtain tailings and a vanadium-containing aqueous solution; performing calcium precipitation on the vanadium-containing solution, and performing solid-liquid separation to obtain vanadium precipitation supernatant and calcium vanadate. However, the method has many steps, vanadium still exists in the form of a mixture, and iron is not recovered, which causes resource waste.

[0005] As can be seen from the above, the acid leaching method has a long process flow and complicated operation for recovering vanadium and iron from the iron vanadate slag. According to the chemical property difference between iron and vanadium elements, the vanadium can be leached by the alkali leaching method to be separated from the iron slag. However, after alkali dissolution, the iron is formed into amorphous iron hydroxide colloidal precipitate, which seriously affects the solid-liquid separation effect of the alkali leaching slurry, thereby limiting the recovery and effective application of vanadium in the iron vanadate slag. Therefore, how to improve the separation effect of the alkali leaching slurry of the iron vanadate slag is a key problem to be solved and is a key factor for improving the recovery and application efficiency of vanadium in the iron vanadate slag. SUMMARY

[0006] In view of the above deficiencies of the prior art, the purpose of the present application is to provide a method for efficiently separating vanadium and iron in iron vanadate slag.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0008] The present application provides a method for efficiently separating vanadium and iron in iron vanadate slag, which comprises the following steps:

[0009] The iron vanadate slag is quickly added to an alkaline solution at a temperature of 30-100℃ for stirring leaching, the temperature of the reaction slurry is controlled, the reaction is carried out for 2-20 min, ferrous salt is immediately added for magnetization reaction, a black slurry is obtained, the slurry is subjected to magnetic attraction and sedimentation, the sedimentation time is less than 20 min, the liquid surface is clear after sedimentation, the lower precipitate phase is separated by magnetic attraction and filtration, the filtration time is less than 15 min, the filtrate and supernatant are mixed to obtain a vanadium-containing alkaline solution, the recovery rate of vanadium reaches 95% or more, the vanadium-containing alkaline solution can be directly used as a raw material for preparing high-purity vanadium pentoxide, and the filter cake is washed with water and used as a raw material for iron smelting.

[0010] In the present application, ferrous salt is added during the alkali dissolution process, and the efficient separation of iron and vanadium is realized by generating magnetic magnetite. Since vanadium is an amphoteric element, it is easily dissolved in alkali, and during the alkali leaching process, it is transferred from the iron vanadate slag to the alkali solution. At the same time, iron dissociates and reacts with hydroxide to form iron hydroxide precipitate. Since the solubility of iron hydroxide is very low, the precipitate is amorphous colloidal precipitate, which leads to difficult separation and makes it difficult to effectively recover vanadium. Considering that when the vanadium in the iron vanadate slag is dissociated into the solution during the alkali dissolution process, the trivalent iron is exposed to form an active trivalent iron ion intermediate, at this time, by adding ferrous iron, the active trivalent iron reacts with ferrous iron to form magnetic magnetite. This is because the Gibbs free energy of the reaction of ferrous iron to form magnetite is much lower than that of the reaction to form iron hydroxide at a temperature of 30-100℃. Therefore, after the reaction generates magnetic magnetite, the efficient separation of the iron slag and the vanadium-containing alkali solution can be realized by magnetic attraction separation. Thus, the problem of difficult filtration of the alkali leaching slurry caused by simple alkali leaching for vanadium extraction is solved, the separation efficiency of vanadium and iron is effectively improved, and the recovery rate of vanadium is improved.

[0011] Further, the concentration of the liquid alkali is 2%-15%.

[0012] Further, the ferrous salt is one or a combination of ferrous sulfate and ferrous chloride;

[0013] Further, the molar ratio of iron in the ferrous salt to iron in the iron vanadate slag is 0.1-1:1.

[0014] Further, the molar ratio of the ferrous salt to the iron in the iron vanadate slag is 0.4-2:1.

[0015] Further, the magnetization reaction time is 30-120 min.

[0016] Compared with the prior art, the method has the following characteristics and advantages:

[0017] The method has the advantages of realizing efficient solid-liquid separation of vanadium-containing alkali liquor and magnetite slag, solving the problem of difficult filtration of alkali liquor slurry caused by simple alkali leaching of vanadium, realizing effective recovery of vanadium, and improving the application value of iron vanadate slag. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is an effect diagram of magnetite adsorption of alkali liquor slurry obtained after magnetization reaction by the embodiment 1 of the method.

[0019] Figure 2 is an effect diagram of magnetite adsorption of alkali liquor slurry obtained by the comparative example 1 not according to the steps of the method.

[0020] Figure 3 is a hysteresis loop comparison diagram of iron slag obtained by the embodiment 2 of the method and iron slag not obtained according to the steps of the method. DETAILED DESCRIPTION

[0021] The method will be further described in detail below with reference to specific embodiments, so that those skilled in the art can implement the method according to the description. However, the following embodiments are only simple examples of the method, and do not represent or limit the protection scope of the method, and the protection scope of the method is subject to the claims.

[0022] Embodiment 1

[0023] A method for efficiently separating vanadium and iron in iron vanadate slag, comprising the following steps:

[0024] Iron vanadate slag with a vanadium content of 17% is added to a liquid alkali solution with a temperature of 80 ℃ and a concentration of 10%, and the alkali leaching reaction is performed for 2 min, then ferrous sulfate is added for magnetization reaction, the molar ratio of iron in the ferrous sulfate to iron in the iron vanadate slag is 0.5:1, the magnetization reaction time is 60 min, after the reaction is completed, the alkali liquor slurry is subjected to magnetic adsorption and sedimentation, and when the sedimentation time is 8 min, clear layering can be achieved, the lower layer of the sediment is separated by magnetic adsorption and filtration, when the thickness of the filter cake is 1 cm, the filtration time is 7.5 min, the filter liquor is mixed with the supernatant to obtain vanadium-containing alkali liquor, the recovery rate of vanadium is 97.7%, the vanadium-containing alkali liquor can be directly used to prepare high-purity vanadium pentoxide, and the filter cake is magnetite slag which can be used as a raw material for iron smelting after being washed.

[0025] Embodiment 2

[0026] A method for efficiently separating vanadium and iron in iron vanadate slag, comprising the following steps:

[0027] Iron vanadate slag with a vanadium content of 25% is added to a liquid alkali solution with a temperature of 60°C and a concentration of 8%, and the alkali leaching reaction is performed for 5 min. Ferrous sulfate is added for magnetization reaction, wherein the molar ratio of iron in ferrous sulfate to iron in iron vanadate slag is 1:1, and the magnetization reaction time is 60 min. After the reaction is completed, the alkali slurry is subjected to magnetic absorption sedimentation, and clear layering can be achieved after 11.5 min of sedimentation time. The lower layer of the precipitate phase is separated by magnetic absorption filtration. When the filter cake thickness is 1 cm, the filtration time is 9 min. The filtrate and supernatant are mixed to form a vanadium-containing alkali solution, and the vanadium recovery rate is 97.2%. The vanadium-containing alkali solution can be directly used to prepare high-purity vanadium pentoxide, and the filter cake is magnetite slag which can be used as a raw material for iron smelting after water washing.

[0028] Example 3

[0029] A method for efficiently separating vanadium and iron in iron vanadate slag, comprising the following steps:

[0030] Iron vanadate slag with a vanadium content of 25% is added to a liquid alkali solution with a temperature of 30°C and a concentration of 12%, and the alkali leaching reaction is performed for 10 min. Ferrous chloride is added for magnetization reaction, wherein the molar ratio of iron in ferrous chloride to iron in iron vanadate slag is 1:1, and the magnetization reaction time is 60 min. After the reaction is completed, the alkali slurry is subjected to magnetic absorption sedimentation, and clear layering can be achieved after 14.5 min of sedimentation time. The lower layer of the precipitate phase is separated by magnetic absorption filtration. When the filter cake thickness is 1 cm, the filtration time is 12.5 min. The filtrate and supernatant are mixed to form a vanadium-containing alkali solution, and the vanadium recovery rate is 96.8%. The vanadium-containing alkali solution can be directly used to prepare high-purity vanadium pentoxide, and the filter cake is magnetite slag which can be used as a raw material for iron smelting after water washing.

[0031] Comparative Example 1

[0032] Compared with Example 1, the difference is that no ferrous sulfate is added, and the remaining steps and parameters are the same. The precipitate has no magnetism, and the supernatant is still turbid after 45 min of sedimentation, which cannot be effectively settled. The precipitate has no magnetism, and the method of magnetic absorption filtration separation cannot be used to achieve solid-liquid separation of the alkali slurry. When the filter cake thickness is 1 cm, the filtration time is 1 h 5 min, and it is difficult to wash. The vanadium recovery rate is only 89.6%.

[0033] Comparative Example 2

[0034] Compared with Example 3, the difference is that the alkali leaching reaction time is 60 min, the rest of the steps and parameters are the same, the precipitation is weakly magnetic, the supernatant is slightly turbid after 45 min of sedimentation, the sedimentation speed is slow, the effect of magnetic separation of the precipitation is poor, the filter cake thickness is 1 cm, the filtration time is 55 min, and it is difficult to wash, and the vanadium recovery rate is only 91.6%.

[0035] The applicant declares that the detailed method of the present application is illustrated by the above examples, but the present application is not limited to the above detailed method, that is, it does not mean that the present application must rely on the above detailed method to be implemented. It should be understood by those skilled in the art that the equivalent replacement of each raw material of the product of the present application and the addition of auxiliary ingredients, the selection of specific methods, etc. all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method for efficiently separating vanadium and iron in ferrovanadium slag, characterized by comprising the following steps: The vanadate iron slag is quickly added to an alkaline solution at a temperature of 30-100°C for stirring and leaching. The temperature of the reaction slurry is controlled to be 0.5-1.0°C, and the reaction is carried out for 2-20 minutes. Ferrous salt is immediately added for magnetization reaction to obtain a black slurry. The slurry is subjected to magnetic sedimentation. The sedimentation time is less than 20 minutes, and the sedimentation liquid surface is clear. The lower precipitate phase is separated by magnetic filtration. The filtration time is less than 15 minutes. The filtrate is mixed with the supernatant to obtain a vanadium-containing alkaline solution. The vanadium recovery rate reaches more than 95%. The vanadium-containing alkaline solution can be directly used as a raw material for preparing high-purity vanadium pentoxide. The filter cake is used as a raw material for ironmaking after washing with water.

2. The method for efficiently separating vanadium and iron in vanadate iron slag according to claim 1, wherein: The vanadium content in the vanadium-containing iron slag is greater than 10%.

3. The method for efficiently separating vanadium and iron in vanadate iron slag according to claim 1, wherein: The concentration of the liquid caustic soda is 2% to 15%.

4. The method for efficiently separating vanadium and iron in vanadate iron slag according to claim 1, wherein: The ferrous salt is ferrous sulfate, ferrous chloride or a combination of the two.

5. The method for efficiently separating vanadium and iron in vanadate iron slag according to claim 1, characterized in that: The molar ratio of the ferrous salt to the iron in the vanadate iron slag is 0.4 to 2:

1.

6. The method for efficiently separating vanadium and iron in ferrovanadate slag according to claim 1, characterized in that: The magnetization reaction time is 30-120 min.

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