Preparation device for preparing battery-grade zinc sulfate based on electrolytic method

Abstract

The invention discloses a preparation device for preparing battery-grade zinc sulfate based on an electrolytic method, and particularly relates to the field of preparation devices. Comprising a dissolving tank; the feeding hopper is communicated with the dissolving tank; the water inlet pipe is communicated with the dissolving tank; the filtering cabin is arranged in the dissolving tank; the electrolysis tank is communicated with the filtering cabin; the ion exchange membrane is arranged in the electrolysis tank; the cathode plate and the anode plate are arranged on the two sides of the ion exchange membrane; the power supply is arranged at the top of the electrolysis tank, and two ends of the power supply are respectively connected with the cathode plate and the anode plate through wires; the vacuum crystallizer is communicated with the cathode area; the centrifugal machine is communicated with the vacuum crystallizer; the fluidized bed is arranged at an outlet of the centrifugal machine. By adopting the technical scheme of the invention, the problems of high cost and no environmental protection when the battery-grade zinc sulfate is prepared from the feed-grade zinc sulfate in the traditional technology are solved, the preparation cost of the battery-grade zinc sulfate is reduced, and the method is green and environment-friendly.

Description

Technical Field

[0001] The present invention relates to the field of preparation devices, in particular to a preparation device for preparing battery-grade zinc sulfate based on an electrolysis method. Background Art

[0002] With the increasing popularity of electric vehicles and various digital 3C products, the demand for secondary batteries has increased significantly. The development of secondary batteries with high capacity, fast charge and discharge speed, excellent safety, abundant raw material resources, environmental friendliness, and strong adaptability is particularly important. Demand for zinc sulfate, a raw material for zinc-manganese secondary battery electrolytes, is increasing rapidly, but the purity of the raw material must be high.

[0003] Currently, my country's zinc sulfate production is primarily feed-grade. Most products contain 35% or more zinc, ≤0.001% arsenic, ≤0.001% lead, and ≤0.0005% cadmium, meeting the national standard for zinc sulfate as a feed additive (94.7, GB / T25865-2010). However, elements like Fe and Mn struggle to meet the battery-grade zinc sulfate standards required by major battery manufacturers (99.9%, tentatively based on the industry standard for battery-grade nickel sulfate, HG / T5919-2021, due to the lack of corresponding national or industry standards).

[0004] Traditional methods for purifying zinc sulfate primarily include recrystallization, chemical precipitation, and solvent extraction / ion exchange. Recrystallization removes impurities through multiple dissolution-crystallization cycles. Chemical precipitation uses sodium sulfide and zinc powder to precipitate impurity metals, which are then filtered to produce high-purity zinc sulfate. Solvent extraction uses a corresponding extractant to extract or strip zinc sulfate or other substances from the solution. Ion exchange utilizes ion exchange membranes to selectively remove impurities from dissolved zinc sulfate.

[0005] The traditional recrystallization method has high energy consumption and low efficiency in removing trace impurities (such as Fe, Mn, and Cd), making it difficult to achieve battery-grade purity (≥99.9%). The chemical precipitation method requires the addition of chemical reagents, which easily introduces secondary contamination (such as sulfide residues). The solvent extraction / ion exchange method has high selectivity, but is expensive (such as the difficulty in regenerating the extractant) and difficult to scale up. Therefore, it is urgent to obtain a method for preparing battery-grade zinc sulfate from feed-grade zinc sulfate with good impurity removal effect, environmental protection, and low cost. Summary of the Invention

[0006] The present invention aims to provide a preparation device for battery-grade zinc sulfate based on an electrolytic method, which solves the problems of high cost and environmental pollution when traditional technology uses feed-grade zinc sulfate to prepare battery-grade zinc sulfate.

[0007] In order to achieve the above object, the technical solution of the present invention is as follows: a preparation device for preparing battery-grade zinc sulfate based on electrolysis, comprising:

[0008] Dissolving tank;

[0009] A feeding hopper, the feeding hopper being connected to the top of the dissolving tank;

[0010] a water inlet pipe, the water inlet pipe being in communication with a side wall of the dissolving tank;

[0011] A filtration cabin, wherein the filtration cabin is arranged in the dissolution tank;

[0012] an electrolysis box, the electrolysis box being in communication with the filtration cabin;

[0013] An ion exchange membrane is disposed in the electrolytic box, and the ion exchange membrane divides the interior of the electrolytic box into an anode region and a cathode region;

[0014] A cathode plate and an anode plate, wherein the cathode plate is disposed in the cathode region and the anode plate is disposed in the anode region;

[0015] A power supply is provided on the top of the electrolytic box, and both ends of the power supply are connected to the cathode plate and the anode plate wires respectively;

[0016] a vacuum crystallizer, the vacuum crystallizer being in communication with the cathode region and being located outside the electrolytic box;

[0017] a centrifuge, the centrifuge being in communication with the vacuum crystallizer;

[0018] A fluidized bed is provided at the outlet of the centrifuge.

[0019] The principle and effect of the technical solution: After the feed-grade zinc sulfate is initially purified by sedimentation, filtration, replacement and other means, the zinc ions are enriched near the cathode area by electrolysis. At the same time, in this process, the anode area will gather other impurity cations, and the ion exchange membrane can only pass zinc ions, effectively preventing the passage of other impurity cations. After the zinc sulfate is enriched in the cathode area, it can be subjected to subsequent evaporation and crystallization processes to obtain zinc sulfate with a purity greater than 99.9%, which is fully suitable for the preparation of new energy battery electrodes and electrolyte materials. In addition, when the liquid dissolved in the dissolution tank flows upward and is transferred to the filter cabin, it will partially settle the oversized particles and undissolved raw materials under the action of gravity.

[0020] Furthermore, a first circulation pipe is connected between the anode area and the dissolution tank, and a first magnetic circulation pump is installed on the first circulation pipe.

[0021] This arrangement allows the solution in the anode region and the insoluble matter produced by electrolysis to be returned to the dissolution tank and filtered. This fully recovers the Zn and prevents clogging of the anode region and ion exchange membrane by electrolysis byproducts. This circulation line, as well as the subsequent circulation lines, operates in a unidirectional manner.

[0022] Furthermore, the filter cabin is provided with a fiber layer, a nano zinc mesh layer, a porous ceramic layer, an activated carbon layer and a filter membrane in sequence from top to bottom.

[0023] Through the above settings, the fiber layer can filter out large particles of insoluble matter such as silicate and silicon dioxide in the raw materials, while the nano zinc mesh layer is responsible for replacing metal ions such as Fe, Co, and Cu. The reaction is:

[0024] 2Fe 3+ 3Zn→2Fe+3Zn 2+ ;

[0025] Co 2+ Zn→Co+Zn 2+ ;

[0026] Cu 2+ Zn→Cu+Zn 2+ ;

[0027] The displaced metal particles and even smaller insoluble substances will be adsorbed by porous ceramics, activated carbon, etc.

[0028] Furthermore, the bottom of the electrolytic box is connected to a second circulation pipe, the two ends of the second circulation pipe are respectively located in the cathode area and the anode area, and a second magnetic circulation pump is installed on the second circulation pipe.

[0029] Through the above arrangement, the second circulation pipe can transfer the zinc sulfate enriched in the cathode area to the anode area to realize multiple electrolysis cycles, thereby further improving the purity of the zinc sulfate.

[0030] Furthermore, an electric stirrer is installed in the dissolving tank.

[0031] Furthermore, an electric heating tube is embedded on the inner wall of the dissolving tank.

[0032] With the above arrangement, heating is utilized to assist in the dissolution of the raw materials.

[0033] Furthermore, the shell of the electrolytic box is made of corrosion-resistant titanium alloy material and the lining is made of polytetrafluoroethylene. A water circulation cooling system is provided between the shell and the lining of the electrolytic box.

[0034] Compared with the existing technology, this solution has the following beneficial effects:

[0035] 1. This solution provides a preparation device for battery-grade zinc sulfate based on electrolysis. Battery-grade zinc sulfate is prepared using feed-grade zinc sulfate as raw material, achieving product value-added, that is, feed-grade zinc sulfate (about 5,000 yuan / ton) vs. battery-grade product (about 15,000 yuan / ton).

[0036] 2. During the preparation of the battery-grade zinc sulfate of this scheme, pulse electrolysis is used to accurately separate impurity ions (such as Fe 2+ / Zn 2+ At the same time, in this process, it can effectively avoid the secondary pollution caused by impurities, and the current efficiency is ≥92% (zinc direct recovery rate>98%). At the same time, it is simple to operate and has low energy consumption.

[0037] 3. Compared with the traditional crystallization method, the energy consumption of this solution is ≤1200kWh / t.

[0038] 4. In this scheme, the electrolytic waste liquid is neutralized and precipitated to recover heavy metals, realizing closed-loop circulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 Schematic diagram of the structure of the preparation device for preparing battery-grade zinc sulfate based on electrolysis according to the present invention;

[0040] Figure 2 is the X-ray diffraction (XRD) result of the sample before processing in this embodiment;

[0041] Figure 3 is the X-ray diffraction (XRD) result of the processed sample in this example;

[0042] Figure 4 1 is a scanning electron microscope image of the sample before and after processing in this embodiment.

[0043] The figure marks in the drawings of the specification include: dissolution tank 1, feeding hopper 2, water inlet pipe 3, electric stirrer 4, electric heating tube 5, first magnetic circulation pump 6, filter cabin 7, electrolysis box 8, power supply 9, anode area 10, cathode area 11, anode plate 12, cathode plate 13, ion exchange membrane 14, second magnetic circulation pump 15, water circulation cooling system 16, vacuum crystallizer 17, centrifuge 18, fluidized bed 19, pH monitoring regulator 2020. DETAILED DESCRIPTION

[0044] The present invention will be further described in detail below through specific embodiments:

[0045] Example

[0046] like Figures 1 to 4 As shown, a preparation device for preparing battery-grade zinc sulfate based on electrolysis comprises:

[0047] The dissolving tank 1 , in this embodiment, is provided with an electric stirrer 4 , and an electric heating tube 5 is embedded on the inner wall of the dissolving tank 1 .

[0048] The feeding hopper 2 is communicated with the top of the dissolving tank 1 .

[0049] The water inlet pipe 3 is connected to the side wall of the dissolving tank 1 and a control valve is installed on the water inlet pipe 3.

[0050] The filter chamber 7 is arranged in the dissolving tank 1. In this embodiment, the filter chamber 7 is provided with a fiber layer, a nano zinc mesh layer, a porous ceramic layer, an activated carbon layer and a filter membrane from top to bottom. The fiber layer can filter out the insoluble matter in the zinc sulfate solution, such as silicate, silicon dioxide, and part of the aluminum and copper compound precipitates (Al2O3) formed by electrolysis in the anode area 10. 3+ +3H2O→Al(OH)3+3H + ), and then combined with the nano zinc mesh to replace part of the Fe, Co, and Cu ions in the solution to obtain corresponding metal precipitates and Zn ions, and then the precipitate in the zinc sulfate solution is filtered again through the porous ceramic layer, the activated carbon layer and the 0.1μm filter membrane, and then the filtered solution enters the electrolytic box 8.

[0051] The electrolytic box 8 is connected to the filter cabin 7. In this embodiment, the shell of the electrolytic box 8 is made of corrosion-resistant titanium alloy material and the lining is made of polytetrafluoroethylene. A water circulation cooling system 16 is provided between the shell and the lining of the electrolytic box 8. The water circulation cooling system 16 is used to cool the electrolyte to a temperature of 30-50°C to avoid side reactions caused by high temperature. The aluminum that has been precipitated at high temperature is dissolved again and enters the cathode area 11 (Al(OH)3→AlO2-+H2O+H + The bottom of the electrolytic box 8 is also connected to a second circulation pipe, the two ends of which are respectively located in the cathode area 11 and the anode area 10, and a second magnetic circulation pump 15 is installed on the second circulation pipe.

[0052] The ion exchange membrane 14 of this embodiment adopts Nafion proton membrane. The ion exchange membrane 14 is arranged in the middle of the electrolytic box 8. With the help of the ion exchange membrane 14, the interior of the electrolytic box 8 is divided into an anode area 10 located on the left side of the ion exchange membrane 14 and a cathode area 11 located on the right side of the ion exchange membrane 14.

[0053] The cathode plate 13 and the anode plate 12 are arranged in the cathode area 11 and the anode plate 12 is arranged in the anode area 10. In this embodiment, the cathode plate 13 is made of titanium and the anode plate 12 is made of titanium-based IrO2 coated electrode.

[0054] Power supply 9, in this embodiment, the power supply 9 adopts pulsed DC power supply 9 (100-200A / m2 , low current can reduce dendrite formation), the power supply 9 is set on the top of the electrolytic box 8, and the two ends of the power supply 9 are respectively connected to the cathode plate 13 and the anode plate 12 wires;

[0055] The vacuum crystallizer 17 is connected to the cathode area 11 and is located outside the electrolytic box 8;

[0056] Centrifuge 18. In this embodiment, the centrifuge 18 is a horizontal screw centrifuge 18. The centrifuge 18 is connected to the vacuum crystallizer 17.

[0057] The fluidized bed 19 is arranged at the outlet of the centrifuge 18 .

[0058] A first circulation pipe is connected between the anode area 10 and the dissolution tank 1 , and a first magnetic circulation pump 6 is installed on the first circulation pipe.

[0059] The working process of this embodiment is as follows:

[0060] Zinc sulfate is added from hopper 2 to dissolution tank 1. The control valve is then opened and deionized water is injected into dissolution tank 1 through water inlet pipe 3. Once the zinc sulfate and deionized water reach the desired levels, electric stirrer 4 and electric heating tube 5 are activated. After the feed-grade zinc sulfate is added to dissolution tank 1, it is thoroughly mixed and dissolved with the deionized water, aided by the heating provided by electric stirrer 4 and electric heating tube 5. In this solution, dissolution tank 1 is equipped with a pH monitoring and adjustment device that uses sulfuric acid to adjust the pH to 5-6. This suppresses the hydrolysis of some metal ions while allowing some aluminum and copper ions in the solution to precipitate.

[0061] After the dissolved solution enters the filter cabin 7, the fiber layer can first filter out the insoluble matter in the zinc sulfate solution system, such as silicate, silicon dioxide, and some aluminum and copper compound precipitates formed in the dissolution cabin. The nano zinc mesh can replace some Fe, Co, and Cu ions in the solution to obtain corresponding metal precipitates and Zn ions. The precipitate in the zinc sulfate solution can be further filtered out through the porous ceramic layer, activated carbon layer and 0.1μm filter membrane, and the filtered solution then enters the electrolytic box 8.

[0062] After the solution enters the electrolytic tank 8, under the control of multiple voltage levels, manganese ions, magnesium ions, calcium ions, and aluminum ions are enriched near the anode plate 12. Under the action of the ion exchange membrane 14, the zinc sulfate solution passes through the ion exchange membrane 14. At the same time, the zinc sulfate solution enriched with manganese ions, magnesium ions, calcium ions, and aluminum ions returns to the dissolution tank 1 again under the action of the first magnetic circulation pump 6, forming a reflux cycle. The zinc sulfate in the cathode plate 13 area will return to the anode for electrolysis under the action of the second magnetic circulation pump 15, and further purification will be carried out to achieve the second cycle of purification. The high-purity zinc sulfate solution after electrolytic purification will enter the subsequent vacuum crystallizer 17.

[0063] After entering the vacuum crystallizer 17, the purified zinc sulfate solution is subjected to controlled evaporation temperature (60-70°C) and stirring speed to produce high-purity zinc sulfate crystals. In the centrifuge 18, the crystals are separated by centrifugation, and the remaining liquid is returned to the vacuum crystallizer 17 for further crystallization. The purified crystals are further dried in the fluidized bed 19 to remove the water of crystallization, resulting in high-purity battery-grade zinc sulfate solids.

[0064] Depend on Figure 2 and Figure 3 It can be seen that the samples before processing are mainly zinc sulfate hexahydrate and zinc sulfate heptahydrate, which contain a small amount of cobalt sulfate. The zinc sulfate after processing is anhydrous zinc sulfate, which is due to the complete evaporation of crystal water after drying. Figure 4 It can be seen that the particle size of the samples before and after processing is less than 100 μm (the particle size requirement of feed-grade zinc sulfate heptahydrate is 800 μm test sieve pass rate ≥ 95%), and the particle size uniformity after processing is higher. Figure 4 As shown in the figure, (a) and (b) are samples before processing, and (c) and (d) are samples after processing. The surface of the sample before processing is relatively flat, while the surface of the sample after processing is rougher. When used as a battery electrode material, it has a larger specific surface area, which is more conducive to charge transfer.

[0065] As shown in Table 1 below, ICP analysis of the sample's elemental composition, excluding oxygen, reveals that the Zn content of the pre-processed sample was 65.12%. After conversion to zinc sulfate heptahydrate, the Zn content was 22.07%, and the zinc sulfate purity was 97.04%, meeting the national standard for feed-grade zinc sulfate, GB / T 25865-2010. The processed zinc sulfate sample had a Zn content of 67.07%, which, after conversion, indicates a zinc sulfate content of approximately 99.94%, meeting the standard for battery-grade zinc sulfate (≥99.9).

[0066] Table 1

[0067]

[0068] The above is only the embodiment of the present application, and the common knowledge of the specific structure and / or characteristics in the scheme is not described in detail. It should be pointed out that for those skilled in the art, without departing from the structure of the present application, a number of modifications and improvements can also be made, which should also be considered as the protection scope of the present application, which will not affect the effect and practicality of the patent. The protection scope claimed in the present application should be subject to the content of its claims, and the specific implementation mode and the like recorded in the specification can be used to explain the content of the claims.

Claims

1. A device for preparing battery-grade zinc sulfate based on electrolysis, characterized in that: include: Dissolving tank; A feeding hopper, the feeding hopper being connected to the top of the dissolving tank; a water inlet pipe, the water inlet pipe being in communication with a side wall of the dissolving tank; A filtration cabin, wherein the filtration cabin is arranged in the dissolution tank; an electrolysis box, the electrolysis box being in communication with the filtration cabin; An ion exchange membrane is disposed in the electrolytic box, and the ion exchange membrane divides the interior of the electrolytic box into an anode region and a cathode region; A cathode plate and an anode plate, wherein the cathode plate is disposed in the cathode region and the anode plate is disposed in the anode region; A power supply is provided on the top of the electrolytic box, and both ends of the power supply are connected to the cathode plate and the anode plate wires respectively; a vacuum crystallizer, the vacuum crystallizer being in communication with the cathode region and being located outside the electrolytic box; a centrifuge, the centrifuge being in communication with the vacuum crystallizer; A fluidized bed is provided at the outlet of the centrifuge.

2. The device for preparing battery-grade zinc sulfate based on electrolysis according to claim 1, characterized in that: A first circulation pipe is connected between the anode area and the dissolution tank, and a first magnetic circulation pump is installed on the first circulation pipe.

3. The device for preparing battery-grade zinc sulfate based on electrolysis according to claim 1, characterized in that: The filter cabin is provided with a fiber layer, a nano zinc mesh layer, a porous ceramic layer, an activated carbon layer and a filter membrane in sequence from top to bottom.

4. The device for preparing battery-grade zinc sulfate based on electrolysis according to claim 1, characterized in that: The bottom of the electrolytic box is also connected to a second circulation pipe, the two ends of the second circulation pipe are respectively located in the cathode area and the anode area, and a second magnetic circulation pump is installed on the second circulation pipe.

5. The device for preparing battery-grade zinc sulfate based on electrolysis according to claim 1, characterized in that: An electric stirrer is installed in the dissolving tank.

6. The device for preparing battery-grade zinc sulfate based on electrolysis according to claim 5, characterized in that: An electric heating pipe is also embedded on the inner wall of the dissolving tank.

7. The device for preparing battery-grade zinc sulfate based on electrolysis according to any one of claims 1 to 6, characterized in that: The shell of the electrolytic box is made of corrosion-resistant titanium alloy material, and the lining is made of polytetrafluoroethylene. A water circulation cooling system is provided between the shell and the lining of the electrolytic box.

Images