Method and device for recovering vanadium electrolyte from vanadium-containing waste felt

Abstract

The present invention provides a method for recovering vanadium electrolyte from vanadium-containing waste felt, comprising the following steps: (1) introducing carbon felt into a chamber of a treatment device, injecting dilute sulfuric acid into the chamber, and heating; (2) impacting the carbon felt, so that most of the vanadium electrolyte in the carbon felt quickly diffuses into the dilute sulfuric acid solution, obtaining a vanadium-rich acid solution, and discharging it from the treatment device; (3) introducing pure water into the chamber of the treatment device, impacting the carbon felt, obtaining a dilute vanadium acid solution, discharging it, and using it as the dilute sulfuric acid described in step (1); (4) detecting the concentration of the vanadium-rich acid solution discharged in step (2), adding a calculated amount of vanadium pentoxide and sulfuric acid, and obtaining a vanadium electrolyte through a reduction reaction. The method and device of the present invention can fully recover vanadium ions in vanadium-containing waste felt without waste liquid discharge, which is both economical and environmentally friendly.

Description

Technical Field

[0001] The present invention relates to the field of industrial devices, in particular to an article recycling device and an article recycling method. Background Art

[0002] All-vanadium redox flow batteries are mainly used in energy storage equipment for renewable energy power generation systems, peak-shaving and valley-filling devices for power grids, and uninterruptible power supplies and emergency power supply systems. Vanadium batteries have the advantages of high energy conversion efficiency, power and capacity can be adjusted separately, long service life, high safety and environmental friendliness.

[0003] Carbon felt is widely used in vanadium battery electrodes due to its excellent conductivity and high specific surface area. It is the main place for electrochemical reactions of electrolytes in vanadium batteries. With the rise of the vanadium battery industry, its research and development enthusiasm is increasing, and a large amount of waste felt containing vanadium electrolytes has also been produced, mainly from the dismantling of scrapped battery stacks. Carbon felt has the characteristics of high porosity and low density, and its adsorption rate for vanadium electrolyte can reach 8-14g / g (that is, 1g of dry carbon felt can adsorb 8-14g of vanadium electrolyte). Discarded vanadium-containing carbon felt cannot be treated as general solid waste due to the corrosiveness of sulfuric acid and the hazard of vanadium elements. Its treatment method is an urgent problem faced by manufacturers. It is foreseeable that this problem will become more prominent after the vanadium battery industry develops to general large-scale production.

[0004] From an environmental protection perspective, recycling the vanadium electrolyte in vanadium-containing waste felt can reduce the harmfulness of the waste felt, help solve the problem of waste felt treatment, reduce environmental pollution, and extract high-value vanadium electrolyte to increase economic benefits.

[0005] At present, there is no specific treatment method for vanadium-containing carbon felt. Existing vanadium battery companies generally treat vanadium-containing carbon felt by centrally stacking and temporarily storing it, and then washing it with water to separate the waste liquid adsorbed by the carbon felt. This has the disadvantages of serious water waste, incomplete washing, and low efficiency. At the same time, a large amount of vanadium-containing wastewater needs to be treated for a second time. Or it is handed over to insurance companies for treatment, which has lower economic benefits and cannot recycle vanadium resources, resulting in great waste. Summary of the invention

[0006] The present invention provides a method for recovering vanadium electrolyte from vanadium-containing carbon felt, comprising the following steps:

[0007] (1) introducing the carbon felt into a chamber of a treatment device, injecting dilute sulfuric acid into the chamber, and heating;

[0008] (2) impacting the carbon felt so that most of the vanadium electrolyte in the carbon felt quickly diffuses into the dilute sulfuric acid solution to obtain vanadium-rich acid solution, which is discharged from the treatment device;

[0009] (3) introducing pure water into the chamber of the treatment device to impact the carbon felt to obtain a dilute vanadic acid solution, which is released and used as the dilute sulfuric acid described in step (1);

[0010] (4) detecting the concentration of the vanadium-rich acid solution released in step (2), adding a calculated amount of vanadium pentoxide and sulfuric acid, and obtaining a vanadium electrolyte through a reduction reaction.

[0011] The present invention also proposes a processing device for recovering vanadium electrolyte from vanadium-containing waste felt, the device comprising the following components: a cavity, the cavity forming a chamber; an extrusion assembly, which can repeatedly extrude the carbon felt in the chamber; a liquid inlet and a liquid outlet, respectively located at the upper part and the bottom part of the cavity; a feeding port, which is used to feed the carbon felt into the chamber. Typically, the extrusion assembly comprises: a static screen plate, horizontally arranged at the lower part of the chamber; a dynamic screen plate (3), movably arranged above the static screen plate; a transmission rod, the lower end of which is connected to the dynamic screen plate, and the upper end of which is driven by a motor and can reciprocate relative to the static screen plate.

[0012] The device and method for recovering vanadium electrolyte from vanadium-containing waste felt proposed in the present invention, compared with the existing vanadium battery enterprise centralized storage, water washing precipitation or handling by a qualified third-party environmental protection company, can not only reduce the harmfulness of vanadium-containing waste felt, but also save vanadium resources and increase economic benefits, and does not produce waste acid and wastewater, effectively solving the problem of handling vanadium-containing waste felt. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 is a schematic diagram of an apparatus for recovering vanadium electrolyte from vanadium-containing waste felt according to the present invention;

[0015] Figure 2 It is a comparison chart of battery performance tests measured between the original electrolyte in Example 1 of the present invention and the regenerated electrolyte obtained in Example 1.

[0016] Figure 1 Middle: 1-transmission rod, 2-chamber, 3-moving screen plate, 4-feeding port, 5-static screen plate, 6-filter, 7-drain port, 8-liquid inlet. DETAILED DESCRIPTION

[0017] In a first aspect of the present invention, a method for recovering vanadium electrolyte from vanadium-containing carbon felt is provided, comprising the following steps:

[0018] (1) introducing the carbon felt into a chamber of a treatment device, injecting dilute sulfuric acid into the chamber, and heating;

[0019] (2) impacting the carbon felt so that most of the vanadium electrolyte in the carbon felt quickly diffuses into the dilute sulfuric acid solution to obtain vanadium-rich acid solution, which is discharged from the treatment device;

[0020] (3) introducing pure water into the chamber of the treatment device to impact the carbon felt to obtain a dilute vanadic acid solution, which is released and used as the dilute sulfuric acid described in step (1);

[0021] (4) detecting the concentration of the vanadium-rich acid solution released in step (2), adding a calculated amount of vanadium pentoxide and sulfuric acid, and obtaining a vanadium electrolyte through a reduction reaction.

[0022] Through the above technical scheme, the carbon felt is subjected to two rounds of treatment in the chamber of the treatment device. The first round is treated with a dilute sulfuric acid solution to remove most of the vanadium battery liquid in the carbon felt. Then the second round is treated with clean water to basically remove the vanadium ions in the carbon felt, and the clean water becomes a dilute sulfuric acid liquid, which is used as the treatment liquid for the first round. The vanadium-rich acid liquid obtained by the first treatment is supplemented with vanadium pentoxide and sulfuric acid and reduced, and used as a vanadium electrolyte. In this way, no waste liquid is discharged during the treatment process, and the vanadium ions and sulfuric acid solution in the carbon felt are fully recovered to achieve resource recycling.

[0023] In a preferred embodiment of the present invention, during the treatment process, the carbon felt placed in the chamber is repeatedly squeezed to fully release the substances adsorbed in the carbon felt. Preferably, when the treatment liquid is discharged, the carbon felt is in a squeezed state to allow the liquid to be discharged as much as possible.

[0024] In step (1), it is best to maintain the treatment liquid (dilute vanadic acid solution) at a relatively high temperature, because there is vanadium in a crystalline state in the carbon felt, and heating is conducive to the dissolution of the vanadium element. The preferred temperature is 50-90°C, and more preferably 70-90°C. To this end, the heated dilute vanadic acid solution can be directly injected into the treatment device, or the treatment liquid can be heated after the dilute vanadic acid solution is injected. The latter method requires that a heating device, such as a heating jacket, a heating tube, etc., be provided in the treatment device.

[0025] As a preferred embodiment, the dilute sulfuric acid obtained in step (3) is recycled to step (1), and the concentration of the sulfuric acid is adjusted to the concentration of sulfuric acid in the target vanadium electrolyte. For example, if it is desired to prepare a vanadium electrolyte having a sulfuric acid concentration of 4.2 mol / L from the vanadium-rich acid solution for recovering vanadium ions, then the dilute vanadium acid solution obtained in step (3) is adjusted to a sulfuric acid concentration of 4.2 mol / L.

[0026] In step (4), the volume, vanadium ion concentration, and sulfate concentration of the obtained vanadium-rich acid solution are measured. A certain amount of vanadium pentoxide and sulfuric acid are added according to the measured parameters, and a vanadium electrolyte is obtained through a reduction reaction. The vanadium ion concentration of the vanadium-rich acid solution can be measured by conventional titration or ultraviolet spectrophotometry, and the sulfate concentration can be measured by weight. The reduction device can be an electrolytic cell or a vanadium battery, and electrolytic reduction or the addition of a reducing agent can be used. The electrolysis time or the amount of reducing agent added is determined by the desired finished electrolyte parameters and the parameters of the vanadium-rich acid solution.

[0027] In step (3), whether the treatment time is sufficient can be determined by detecting whether the pH value of the treatment liquid changes. When the pH value reaches the minimum value, the treatment liquid can be released.

[0028] The second aspect of the present invention provides a device for recovering vanadium electrolyte from waste vanadium battery carbon felt. Figure 1 is a schematic diagram of an embodiment of a processing device according to the present invention. Figure 1 In the embodiment, the treatment device comprises: a cavity 2 forming a chamber, an extrusion assembly that can repeatedly extrude the carbon felt in the chamber, a liquid inlet 8 and a liquid outlet 7 respectively located at the upper and lower parts of the cavity, and a feeding port 4 for feeding carbon felt into the chamber. The extrusion assembly of this embodiment comprises: a static screen plate 5, horizontally arranged at the lower part of the chamber; a moving screen plate 3, movably arranged above the static screen plate 5; a transmission rod 1, the lower end of which is connected to the moving screen plate 3, and the upper end is driven by a motor and can reciprocate relative to the static screen plate. The filter 6 is installed near the liquid outlet 7. As a preferred embodiment, the treatment device also includes a heating jacket, a temperature sensor and a pH meter. The liquid inlet 8 is used to introduce dilute sulfuric acid or pure water into the chamber, and the liquid outlet 7 is used to discharge these treatment liquids. The filter 6 can filter solid substances in the treatment liquid. The feeding port 4 is arranged on the side wall of the cavity, and the vanadium-containing carbon felt enters the chamber from the feeding port 4, between the moving screen plate 3 and the static screen plate 5. The moving screen plate 3 moves up and down under the drive of the motor, squeezing the carbon felt and causing the vanadium ions in the carbon felt to dissolve quickly. The heating jacket heats the treatment liquid in the treatment device to a predetermined temperature, which can dissolve solid vanadium.

[0029] The interior of the treatment device cavity is made of high temperature and corrosion resistant polymer materials such as polytetrafluoroethylene. Its shape can be cylindrical, cubic or tower.

[0030] Embodiment 1:

[0031] According to the patent concept, the processing is designed as follows: Figure 1 The tower carbon felt treatment device shown in the figure. The waste felt containing vanadium to be treated is about 4.8kg, and the dry felt density is measured to be 0.1022g / cm3, and the liquid absorption rate is 8.15g / g; the vanadium ion concentration of the original electrolyte parameters is 1.6mol / L, and the sulfate ion concentration is 4.2mol / L electrolyte.

[0032] Acid leaching and compression process: put an appropriate amount of vanadium-containing carbon felt into the chamber of the above-mentioned treatment device, introduce 200 liters of 4.2 mol / L sulfuric acid solution as the acid leaching solution, heat it to 75°C, acid-leach the vanadium-containing waste felt to be treated, repeatedly compress it for 2 hours, and then release it to obtain 218L of vanadium-rich acid solution, which is transported to the electrolytic reduction device through a filter;

[0033] Water immersion compression process: 200 liters of ultrapure water is introduced to immerse the above waste felt in water, and the waste felt is repeatedly compressed until the pH value of the solution does not change, thereby obtaining a dilute vanadic acid solution, which is then transported to a dilute sulfuric acid storage tank through a filter;

[0034] Detection and preparation process: The vanadium ion concentration of the vanadium-rich acid solution was measured to be 0.24 mol / L, the sulfate concentration was 4.2 mol / L, and the vanadium recovery rate was about 92.4%. According to the detection results and material balance, vanadium pentoxide was added for electrolytic reduction to obtain a vanadium electrolyte with a vanadium ion concentration of 1.6 M and a sulfate ion concentration of 4.2 M.

[0035] The original electrolyte and the regenerated electrolyte obtained in Example 1 were taken to measure the battery performance. The results are shown in Figure 2 As shown. Figure 2 It can be seen that the current efficiency of the regenerated electrolyte is not much different from that of the original electrolyte, and the energy efficiency of the regenerated electrolyte is slightly improved, which means that the regenerated electrolyte meets the requirements for reuse.

Claims

1. A device for recovering vanadium electrolyte from vanadium-containing carbon felt, characterized in that: include: a cavity (2), the cavity forming a chamber; A static screen plate (5) is horizontally arranged at the lower part of the chamber; A movable screen plate (3) movably arranged above the static screen plate (5); A transmission rod (1), the lower end of which is connected to the moving screen plate (3), and the upper end of which is driven by a motor to drive the moving screen plate to reciprocate relative to the static screen plate; A liquid inlet (8) and a liquid outlet (7) are respectively located at the upper part and the bottom part of the cavity; The feeding port (4) is used to feed carbon felt into the chamber.

2. The device according to claim 1, characterized in that It also includes a filter (6) installed near the drain port (7).

3. The device according to claim 1, characterized in that Also includes a heating jacket and temperature sensor.

4. The device according to claim 1, characterized in that Also included is a pH meter, which is disposed in the chamber.

5. The device according to claim 2, characterized in that The feeding port is arranged on the side wall of the cavity.

Images