Method for directly preparing all-vanadium redox flow battery electrolyte from vanadium slag

Abstract

The invention discloses a method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag, which comprises the following steps of: co-roasting the vanadium slag and an oxalate additive to obtain clinker, leaching by using an oxalic acid solution, reducing pentavalent vanadium ions and removing impurity cations by using reducibility and complexation of oxalic acid, circularly roasting the vanadium slag by using filter residues, and recycling the vanadium slag to obtain the all-vanadium redox flow battery electrolyte. The filtrate can be directly used as the electrolyte of the all-vanadium redox flow battery after being subjected to simple concentration adjustment treatment. According to the method, the existing process and equipment for preparing the all-vanadium redox flow battery electrolyte are simplified, an electrolysis route is abandoned, side reactions are avoided, the vanadium slag is utilized at a high value while the electrolyte is prepared, the cost for preparing the all-vanadium redox flow battery electrolyte is reduced, the problems of high energy consumption, heavy pollution and the like of a traditional preparation process are solved, the process flow is short, and the method is suitable for industrial production. The method is simple, efficient, environment-friendly, energy-saving, emission-reducing and wide in application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of all-vanadium liquid flow batteries, and in particular relates to a method for directly preparing an all-vanadium liquid flow battery electrolyte from vanadium slag. Background Art

[0002] In order to meet the needs of large-scale energy storage systems, all-vanadium flow batteries have become a promising candidate. Compared with lithium-ion batteries, they have the advantages of energy and power decoupling, excellent scalability, flexible operation, long cycle life, high safety and environmental protection. In all-vanadium flow batteries, the electrolyte is the working solution that carries redox active substances. Its performance and cost determine the performance and cost of all-vanadium flow batteries. The electrolyte originally used in all-vanadium flow batteries was prepared by dissolving vanadyl sulfate in sulfuric acid solution. Due to the high price of vanadyl sulfate crystals, the cost of preparing the electrolyte is too high. Therefore, it is necessary to find a more economical method for preparing the electrolyte. Using vanadium pentoxide instead of vanadyl sulfate to prepare vanadium electrolyte can reduce the vanadium source cost of the electrolyte, but it is necessary to electrolyze the vanadium pentoxide solution to obtain a low-valent vanadium ion solution in the future. The steps are cumbersome and consume electricity.

[0003] At present, the production process of all-vanadium liquid flow battery electrolyte is complex and the energy consumption is high, which limits the development of the all-vanadium liquid flow battery industry. There is an urgent need for a convenient and economical way to prepare the electrolyte. Summary of the invention

[0004] The purpose of the present invention is to provide a method for directly preparing an electrolyte for an all-vanadium flow battery from vanadium slag in view of the shortcomings of the current preparation technology and process for the electrolyte of an all-vanadium flow battery. The method adopts oxalate roasting, oxalic acid solution leaching and recycling oxalate for roasting vanadium slag, simplifies the existing process for preparing an electrolyte for an all-vanadium flow battery, realizes the high-value utilization of vanadium slag, reduces the cost of preparing an electrolyte for an all-vanadium flow battery, solves the problem of high energy consumption in the traditional preparation process, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0005] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0006] Figure 1 A schematic flow chart of a method for directly preparing an all-vanadium liquid flow battery electrolyte from vanadium slag provided by the present invention.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution adopted in the present invention is: A method for directly preparing an all-vanadium liquid flow battery electrolyte from vanadium slag is provided, comprising the following steps: S1, mixing vanadium slag of a certain particle size with an oxalate additive of a certain particle size in a certain mass ratio, and roasting at a certain temperature for a certain time to obtain oxalate roasted clinker; S2, leaching the oxalate roasted clinker with an oxalic acid solution of a certain concentration under certain conditions, and then separating the solid and the liquid to obtain a primary filtrate and a primary residue containing low-valent (III, IV) vanadium ions; S3, the unreacted oxalate in the primary filtrate combines with the cations in the solution and precipitates, the impurity cations are removed, and the oxalate residue and the secondary filtrate are obtained after filtration, and the residue is used for the recycling of vanadium slag for roasting; S4. The secondary filtrate can be directly used as the electrolyte of the all-vanadium liquid flow battery, or it can be used as the electrolyte of the all-vanadium liquid flow battery after simple treatment.

[0008] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S1, the certain mass ratio refers to the mass ratio of vanadium slag to oxalate additive is 10:(0.1~5).

[0009] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S1, the certain temperature refers to 200-800°C.

[0010] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag in step S1 is characterized in that: in step S1, the certain time is 10 to 180 minutes.

[0011] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S2, the certain concentration of oxalic acid solution refers to an oxalic acid solution with a concentration of 10 to 200 g / L.

[0012] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S2, the certain conditions refer to a leaching temperature of 10 to 80°C, a leaching time of 0 to 120 min, and a leaching liquid-to-solid ratio of 1 to 20 mL / g.

[0013] Furthermore, the method for directly preparing an all-vanadium liquid flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S1, the vanadium slag of a certain particle size refers to a vanadium slag particle size not exceeding 0.3 mm, and the oxalate additive of a certain particle size refers to an oxalate additive particle size not exceeding 0.50 mm.

[0014] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that the simple treatment described in step S4 refers to adjusting the concentration and adding special additives.

[0015] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that the oxalate additive in the oxalate additive in step S1 is at least one of oxalates such as sodium oxalate, oxalic acid, calcium oxalate, potassium oxalate, and ammonium oxalate.

[0016] Furthermore, the method for extracting vanadium by oxalate roasting of vanadium slag described in step S1 is characterized in that: in step S1, the main components of the vanadium slag are: V2O5 3.2% ~ 27.6%, SiO2 9.6 ~ 34.5%, Fe2O3 26.1 ~ 39.8%, MnO 4.3% ~ 6.8%, MgO 1.2% ~ 3.6%, CaO 6.3% ~ 12.1%.

[0017] The beneficial effects of the present invention are: The present invention adopts a method of roasting oxalate, leaching oxalic acid solution and recycling oxalate for roasting vanadium slag, and utilizes the reducing property of oxalic acid to controllably reduce pentavalent vanadium to trivalent or tetravalent vanadium, thereby meeting the demand for all-vanadium liquid flow battery electrolyte. The method simplifies the existing process for preparing all-vanadium liquid flow battery electrolyte, realizes the high-value utilization of vanadium slag, reduces the cost of preparing all-vanadium liquid flow battery electrolyte, solves the problem of high energy consumption in traditional preparation process, and has broad application prospects. DETAILED DESCRIPTION

[0018] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0019] A method for directly preparing an all-vanadium liquid flow battery electrolyte from vanadium slag is provided, comprising the following steps: S1, mixing vanadium slag of a certain particle size with an oxalate additive of a certain particle size in a certain mass ratio, and roasting at a certain temperature for a certain time to obtain oxalate roasted clinker; S2, leaching the oxalate roasted clinker with an oxalic acid solution of a certain concentration under certain conditions, and then separating the solid and the liquid to obtain a primary filtrate and a primary residue containing low-valent (III, IV) vanadium ions; S3, the unreacted oxalate in the primary filtrate combines with the cations in the solution and precipitates, the impurity cations are removed, and the oxalate residue and the secondary filtrate are obtained after filtration, and the residue is used for the recycling of vanadium slag for roasting; S4. The secondary filtrate can be directly used as the electrolyte of the all-vanadium liquid flow battery, or it can be used as the electrolyte of the all-vanadium liquid flow battery after simple treatment.

[0020] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S1, the certain mass ratio refers to the mass ratio of vanadium slag to oxalate additive is 10:(0.1~5).

[0021] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S1, the certain temperature refers to 200-800°C.

[0022] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag in step S1 is characterized in that: in step S1, the certain time is 10 to 180 minutes.

[0023] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S2, the certain concentration of oxalic acid solution refers to an oxalic acid solution with a concentration of 10 to 200 g / L.

[0024] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S2, the certain conditions refer to a leaching temperature of 10 to 80°C, a leaching time of 0 to 120 min, and a leaching liquid-to-solid ratio of 1 to 20 mL / g.

[0025] Furthermore, the method for directly preparing an all-vanadium liquid flow battery electrolyte from vanadium slag described in step S1 is characterized in that: in step S1, the vanadium slag of a certain particle size refers to a vanadium slag particle size not exceeding 0.3 mm, and the oxalate additive of a certain particle size refers to an oxalate additive particle size not exceeding 0.50 mm.

[0026] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that the simple treatment described in step S4 refers to adjusting the concentration and adding special additives.

[0027] Furthermore, the method for directly preparing an all-vanadium redox flow battery electrolyte from vanadium slag described in step S1 is characterized in that the oxalate additive in the oxalate additive in step S1 is at least one of oxalates such as sodium oxalate, oxalic acid, calcium oxalate, potassium oxalate, and ammonium oxalate.

[0028] Furthermore, the method for extracting vanadium by oxalate roasting of vanadium slag described in step S1 is characterized in that: in step S1, the main components of the vanadium slag are: V2O5 3.2% ~ 27.6%, SiO2 9.6 ~ 34.5%, Fe2O3 26.1 ~ 39.8%, MnO 4.3% ~ 6.8%, MgO 1.2% ~ 3.6%, CaO 6.3% ~ 12.1%. Example

[0029] Take 200 grams of vanadium slag powder, weigh 60 grams of sodium oxalate according to the mass ratio of vanadium slag to sodium oxalate of 1:0.3, mix them evenly and heat them to 600℃ in a muffle furnace at 5℃ / min, roast them for 90 minutes, cool them to room temperature to get clinker, and grind the clinker to 100-120 mesh. Take 20 grams of clinker, add oxalic acid as the leaching agent at a liquid-solid ratio of 15:1 and an oxalic acid concentration of 50g / L, stir and leach at 60℃ for 60min, filter, and get a primary filtrate and a primary residue. The primary filtrate is crystallized and filtered to get a secondary filtrate and oxalate. The secondary filtrate is vacuum dried and concentrated to get an all-vanadium redox flow battery electrolyte. The vanadium ion concentration in the electrolyte is 1.52mol / L, and the comprehensive valence is 3.82, which meets the requirements of the all-vanadium redox flow battery electrolyte. Example

[0030] Take 200 grams of vanadium slag powder, weigh 60 grams of sodium oxalate according to the mass ratio of vanadium slag to sodium oxalate of 1:0.3, mix them evenly and heat them to 700℃ in a muffle furnace at 5℃ / min, roast them for 90 minutes, cool them to room temperature to get clinker, and grind the clinker to 100-120 mesh. Take 20 grams of clinker, add oxalic acid as the leaching agent at a liquid-solid ratio of 15:1 and an oxalic acid concentration of 130g / L, stir and leach at 60℃ for 60min, filter, and get a primary filtrate and a primary residue. The primary filtrate is crystallized and filtered to get a secondary filtrate and oxalate. The secondary filtrate is vacuum dried and concentrated to get an all-vanadium redox flow battery electrolyte. The vanadium ion concentration in the electrolyte is 1.64mol / L, and the comprehensive valence is 3.65, which meets the requirements of the all-vanadium redox flow battery electrolyte. Example

[0031] Take 200 grams of vanadium slag powder, weigh 60 grams of sodium oxalate according to the mass ratio of vanadium slag to sodium oxalate of 1:0.3, mix them evenly and heat them to 800℃ in a muffle furnace at 5℃ / min, roast them for 90min, cool them to room temperature to get clinker, and grind the clinker to 100-120 mesh. Take 20 grams of clinker, add oxalic acid as the leaching agent at a liquid-solid ratio of 15:1 and an oxalic acid concentration of 200g / L, stir and leach at 60℃ for 60min, filter, and get a primary filtrate and a primary residue. The primary filtrate is crystallized and filtered to get a secondary filtrate and oxalate. The secondary filtrate is vacuum dried and concentrated to get an all-vanadium redox flow battery electrolyte. The vanadium ion concentration in the electrolyte is 1.74mol / L, and the comprehensive valence is 3.13, which meets the requirements of the all-vanadium redox flow battery electrolyte. Example

[0032] Take 200 grams of vanadium slag powder, weigh 60 grams of potassium oxalate according to the mass ratio of vanadium slag to potassium oxalate of 1:0.3, mix them evenly and heat them to 600℃ in a muffle furnace at 5℃ / min, roast them for 90 minutes, cool them to room temperature to get clinker, and grind the clinker to 100-120 mesh. Take 20 grams of clinker, add oxalic acid as the leaching agent at a liquid-solid ratio of 15:1 and an oxalic acid concentration of 90g / L, stir and leach at 60℃ for 60 minutes, filter, and get a primary filtrate and a primary residue. The primary filtrate is crystallized and filtered to get a secondary filtrate and oxalate. The secondary filtrate is vacuum dried and concentrated to get an all-vanadium redox flow battery electrolyte. The vanadium ion concentration in the electrolyte is 1.62mol / L, and the comprehensive valence is 3.85, which meets the requirements of the all-vanadium redox flow battery electrolyte. Example

[0033] Take 200 grams of vanadium slag powder, weigh 60 grams of potassium oxalate according to the mass ratio of vanadium slag to potassium oxalate of 1:0.3, mix them evenly and heat them to 700℃ in a muffle furnace at 5℃ / min, roast them for 90 minutes, cool them to room temperature to get clinker, and grind the clinker to 100-120 mesh. Take 20 grams of clinker, add oxalic acid as the leaching agent at a liquid-solid ratio of 15:1 and an oxalic acid concentration of 130g / L, stir and leach at 60℃ for 60min, filter, and get a primary filtrate and a primary residue. The primary filtrate is crystallized and filtered to get a secondary filtrate and oxalate. The secondary filtrate is vacuum dried and concentrated to get an all-vanadium redox flow battery electrolyte. The vanadium ion concentration in the electrolyte is 1.57mol / L, and the comprehensive valence is 3.67, which meets the requirements of the all-vanadium redox flow battery electrolyte. Example

[0034] Take 200 grams of vanadium slag powder, weigh 60 grams of potassium oxalate according to the mass ratio of vanadium slag to potassium oxalate of 1:0.3, mix them evenly and heat them to 800℃ in a muffle furnace at 5℃ / min, roast them for 90 minutes, cool them to room temperature to get clinker, and grind the clinker to 100-120 mesh. Take 20 grams of clinker, add oxalic acid as the leaching agent at a liquid-solid ratio of 15:1 and an oxalic acid concentration of 180g / L, stir and leach at 60℃ for 60min, filter, and get a primary filtrate and a primary residue. The primary filtrate is crystallized and filtered to get a secondary filtrate and oxalate. The secondary filtrate is vacuum dried and concentrated to get an all-vanadium redox flow battery electrolyte. The vanadium ion concentration in the electrolyte is 1.68mol / L, and the comprehensive valence is 3.17, which meets the requirements of the all-vanadium redox flow battery electrolyte.

Claims

1. A method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag, characterized in that: The following steps are involved: S1, mixing vanadium slag of a certain particle size with an oxalate additive of a certain particle size in a certain mass ratio, and roasting at a certain temperature for a certain time to obtain oxalate roasted clinker; S2, leaching the oxalate roasted clinker with an oxalic acid solution of a certain concentration under certain conditions, and then separating the solid and the liquid to obtain a primary filtrate and a primary residue containing low-valent (III, IV) vanadium ions; S3, the unreacted oxalate in the primary filtrate combines with the cations in the solution and precipitates, the impurity cations are removed, and the oxalate residue and the secondary filtrate are obtained after filtration, and the residue is used for recycling the vanadium slag for roasting; S4. The secondary filtrate can be directly used as the electrolyte of the all-vanadium liquid flow battery, or it can be used as the electrolyte of the all-vanadium liquid flow battery after simple treatment.

2. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S1, the certain mass ratio refers to the mass ratio of vanadium slag to oxalate additive being 10:(0.1-5).

3. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S1, the certain temperature is 200-800°C.

4. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S1, the certain time refers to 10 to 180 minutes.

5. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S2, the certain concentration of oxalic acid solution refers to an oxalic acid solution with a concentration of 10 to 200 g / L.

6. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S2, the certain conditions refer to a leaching temperature of 10 to 80°C, a leaching time of 0 to 120 min, and a leaching liquid-to-solid ratio of 1 to 20 mL / g.

7. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S1, the vanadium slag of a certain particle size refers to the vanadium slag having a particle size not exceeding 0.3 mm, and the oxalate additive of a certain particle size refers to the oxalate additive having a particle size not exceeding 0.50 mm.

8. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S4, the simple treatment refers to adjusting the concentration and adding special additives.

9. The method for directly preparing an electrolyte for an all-vanadium redox flow battery from vanadium slag according to claim 1, characterized in that: In step S1, the oxalate additive in the oxalate additive is at least one of oxalates such as sodium oxalate, oxalic acid, calcium oxalate, potassium oxalate, and ammonium oxalate.

10. The method for extracting vanadium by roasting vanadium slag with oxalate according to claim 1, characterized in that: In step S1, the main components of the vanadium slag are: V2O5 3.2%-27.6%, SiO2 9.6-34.5%, Fe2O3 26.1-39.8%, MnO 4.3%-6.8%, MgO 1.2%-3.6%, and CaO 6.3%-12.1%.

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