A device for pulse-enhanced electro-deposition recovery of gallium

Abstract

The utility model belongs to metal electrolytic deposition field discloses a kind of device of pulse reinforced electrodepositing gallium, including pulse power supply, electrolytic cell and electrolyte storage tank, the pulse power supply is connected with cathode and anode by wire, the cathode and anode are placed in electrolytic cell, cathode average current density is 500~2000 A / m 2 , duty ratio 30%~80%, frequency 1~100 Hz, electrolyte is from electrolyte storage tank by electrolyte inlet pipeline and circulating pump into electrolytic cell, and flows back electrolyte storage tank by electrolyte outlet pipeline.The above-mentioned device of pulse reinforced electrodepositing gallium gallium recovery efficiency is high and energy consumption is low.

Description

Technical Field

[0001] This invention belongs to the field of metal electrolytic deposition, and particularly relates to a device for pulse-enhanced electrodeposition to recover gallium. Background Technology

[0002] Gallium (Ga) is an important rare and dispersed metal. Gallium and its compounds (gallium arsenide, gallium nitride, etc.) possess excellent optoelectronic and chemical properties and are widely used in many high-tech fields such as chip semiconductor materials and solar cells. Electrowinning is a necessary step in recovering metallic gallium from aqueous solutions. However, because the theoretical deposition potential of gallium is more negative than that of hydrogen, severe hydrogen evolution side reactions usually accompany gallium electrowinning.

[0003] Mass transfer is a crucial step in electrodeposition. During electrodeposition, metal ions primarily reach the cathode surface for reaction via diffusion and convection. Because gallium has a highly negative deposition potential, a large current density is required to increase the reaction overpotential. This can easily lead to rapid ion depletion in the diffusion layer at the cathode surface, i.e., concentration polarization. Consequently, this results in severe hydrogen evolution side reactions, low current efficiency, and high energy consumption. Traditional electrodeposition process enhancement methods often focus on convective mass transfer in the electrolyte, neglecting the vital diffusion mass transfer.

[0004] For example, CN117646255A discloses an apparatus and method for recovering gallium by activated electrowinning using a steel wool cathode. The apparatus includes a temperature-controlled tank, wires, a power supply, an electrolytic cell, a thermocouple, an anode, an electrolyte, a cathode, and a temperature-controlled medium. The electrolytic cell is placed inside the temperature-controlled tank, which is filled with a temperature-controlled medium. The electrolytic cell is filled with electrolyte. The thermocouple, anode, and cathode are placed in the electrolyte. The anode and cathode are connected to the power supply via wires. The cathode is a steel wool cathode. The power supply used in this apparatus and method is a conventional power supply with low current efficiency. Utility Model Content

[0005] The technical problem to be solved by this utility model is to overcome the deficiencies and defects mentioned in the background art above, and to provide a device for gallium recovery by pulse-enhanced electrowinning with high gallium recovery efficiency and low energy consumption.

[0006] To solve the above-mentioned technical problems, the technical solution proposed by this utility model is as follows: a device for pulse-enhanced electrowinning to recover gallium, comprising a pulse power supply, an electrolytic cell, and an electrolyte storage tank. The pulse power supply is connected to a cathode and an anode via wires. The cathode and anode are placed in the electrolytic cell, and the average current density of the cathode is 500~2000 A / m. 2 The duty cycle is 30%~80%, the frequency is 1~100 Hz, and the electrolyte enters the electrolytic cell from the electrolyte storage tank through the electrolyte inlet pipe and the circulation pump, and flows back to the electrolyte storage tank through the electrolyte outlet pipe.

[0007] In one embodiment, a temperature control component is provided outside the electrolyte storage tank. The temperature control component includes a controller, a thermocouple, and a temperature-controlled water jacket. The thermocouple is placed in the electrolyte storage tank, and the temperature-controlled water jacket is fitted outside the electrolyte tank. The controller controls the temperature of the temperature-controlled water jacket based on the temperature monitored by the thermocouple in real time.

[0008] In one embodiment, both the cathode and the anode are made of SUS316.

[0009] In one embodiment, the anode has a porous structure or a mesh structure.

[0010] In one embodiment, the electrolyte flows from the electrolyte storage tank into the electrolytic cell via a circulation pump at a velocity of 10~100 mm / s.

[0011] In one embodiment, the initial gallium concentration in the electrolyte of the electrolytic cell is 40-80 g / L, pH>14, and the gallium concentration at the end of electrolysis is less than 1 g / L.

[0012] In one embodiment, during the electrowinning process, the electrolyte temperature is controlled at 20~25°C by a temperature control component.

[0013] Compared with the prior art, the beneficial effects of this utility model are as follows: In the above-mentioned pulse-enhanced electrowinning gallium recovery device, the power supply used is a pulse power supply, which can provide a stable unidirectional square wave pulse current and control the average cathode current density at 500~2000 A / m2, duty cycle at 30%~80%, and frequency at 1~100 Hz. Using the pulse-enhanced electrowinning gallium recovery device of this application, the gallium recovery rate reaches 90.61%, the current efficiency reaches 71.98%, and the specific energy consumption is 8541.67 kWh / t. Through the relaxation of the unidirectional pulse current, gallium ions diffuse and transfer to the cathode surface during the current off-current period, maintaining a high concentration of the diffusion layer on the cathode surface, thereby suppressing concentration polarization. If the current density is low, gallium deposition is controlled by electrochemical polarization, while if the current density is too high, it is controlled by concentration polarization. When the duty cycle is low, the cathode gallium is prone to back-dissolution, and the production capacity is relatively low, while a high duty cycle cannot effectively suppress concentration polarization. At lower frequencies, the current conduction time is longer, and concentration polarization cannot be effectively suppressed. Conversely, at higher frequencies, the electric double layer on the electrode surface is charged and discharged frequently, which also leads to low current efficiency. Under the aforementioned suitable pulse current parameters, a high gallium recovery rate and low energy consumption can be ensured. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of a device for recovering gallium by pulse-enhanced electrowinning according to one embodiment. Detailed Implementation

[0016] To facilitate understanding of this utility model, the following description will be provided in more comprehensive and detailed manner with reference to the accompanying drawings and preferred embodiments. However, the scope of protection of this utility model is not limited to the following specific embodiments.

[0017] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of protection of this invention.

[0018] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0019] Please see Figure 1 An apparatus for recovering gallium by pulse-enhanced electrowinning according to one embodiment includes an electrolyte storage tank 2, an electrolyte inlet pipe 3, a wire 4, a temperature-controlled water jacket 6, a circulation pump 7, an anode 8, a cathode 9, an electrolytic cell 10, an electrolyte outlet pipe 11, and a pulse power supply 12. The pulse power supply 12 is connected to the cathode 9 and the anode 8 via the wire 4, and the cathode 9 and the anode 8 are placed in the electrolytic cell 10. The electrolyte enters the electrolytic cell 10 from the electrolyte storage tank 2 through the electrolyte inlet pipe 3 and the circulation pump 7, and flows back to the electrolyte storage tank 2 through the electrolyte outlet pipe 11. The cathode 9 has an average current density of 500~2000 A / m2, a duty cycle of 30%~80%, and a frequency of 1~100 Hz. In this application, by relaxing the unidirectional pulse current, gallium ions are diffused to the surface of the cathode 9 during the current off-current period, maintaining a high concentration of the diffusion layer on the surface of the cathode 9, thereby suppressing concentration polarization. At low current densities, gallium deposition is controlled by electrochemical polarization, while at high current densities it is controlled by concentration polarization. At low duty cycles, gallium in the cathode is prone to back-dissolved, resulting in relatively low yield. Concentration polarization cannot be effectively suppressed at high duty cycles. At low frequencies, the current conduction time is long, and concentration polarization cannot be effectively suppressed. At high frequencies, frequent charging and discharging of the electrode surface double layer also leads to low current efficiency.

[0020] Preferably, a temperature control component is provided outside the electrolyte storage tank 2. The temperature control component includes a controller 5, a temperature-controlled water jacket 6 fitted outside the electrolyte storage tank 2, and a thermocouple 1. The thermocouple 1 is placed inside the electrolyte storage tank 2. The controller 5 monitors the temperature in real time through the thermocouple 1 to control the temperature of the temperature-controlled water jacket 6, thereby controlling the temperature of the electrolyte. Specifically, the temperature control component has both heating and cooling functions. During the electrowinning process, the electrolyte temperature should be controlled at 20~25℃, which is below the melting point of gallium (29.76℃). If the electrolyte temperature is higher than the melting point of gallium, gallium will precipitate in liquid form. Liquid gallium cannot stably adhere to the cathode surface and will gradually fall to the bottom of the tank and dissolve back into the electrolyte, resulting in a decrease in current efficiency and recovery rate. If the electrolyte temperature is too low, the ion diffusion coefficient will decrease, which is not conducive to the mass transfer process and will lead to an increase in the voltage and energy consumption of the electrolytic cell 10.

[0021] Preferably, in one embodiment, both the cathode 9 and the anode 8 are made of SUS316. Gallium readily forms alloys with some metals, and SUS316, as a cathode, effectively prevents the corrosion of gallium and is easily separated from it. As an anode, SUS316 has lower cost, better oxygen evolution reaction catalytic performance, and resistance to alkaline solution corrosion. Preferably, the anode 8 has a porous or mesh structure. This structure can effectively optimize the flow field distribution of the electrolyte in the electrolytic cell, effectively eliminate dead zones between the plates, enhance the convective mass transfer of the electrolyte, and thus further suppress concentration polarization.

[0022] Preferably, in one embodiment, when the electrolyte is transported from the electrolyte storage tank 2 to the electrolytic cell 10 through the electrolyte inlet pipe 3 and the circulation pump 7, the flow rate of the electrolyte is controlled at 10~100 mm / s. The circulating flow of the electrolyte can improve the convective mass transfer of gallium ions and reduce the thickness of the diffusion layer, so that ions can be replenished to the surface of the cathode 9 in a timely manner during the pulse current turn-off, further eliminating concentration polarization and improving current efficiency.

[0023] Preferably, the electrolyte composition is as follows: initial gallium concentration of 40-80 g / L, pH > 14, and final gallium concentration below 1 g / L. According to the Nerest equation, increasing the gallium ion concentration helps reduce the reaction overpotential, making the electrodeposition reaction easier to occur; however, the difficulty of the upstream enrichment process must also be considered. Within the above concentration range, a higher initial gallium concentration is better. Furthermore, gallium has high solubility in strongly alkaline solutions; therefore, to prevent gallium hydrolysis and precipitation, the solution needs to be maintained at a strong alkalinity.

[0024] To better understand the specific functions and operation of the pulse-enhanced electrowinning gallium recovery apparatus of this embodiment, this embodiment also provides a method for recovering gallium using the above-described apparatus, specifically including the following steps:

[0025] (1) Place the electrolyte with an initial gallium concentration of 60 g / L and pH>14 in the electrolyte storage tank 2, and install the pipes and lines. Turn on the circulation pump and temperature control device to stabilize the electrolyte temperature at about 25°C. Then use the circulation pump 7 to transport the electrolyte to the electrolytic cell 10 at a flow rate of 100 mm / s.

[0026] (2) Set the current parameter to an average current density of 1000 A / m 2 With a duty cycle of 50% and a frequency of 10 Hz, pulse power supply 12 is turned on for electrowinning. Gallium is reduced and deposited on cathode 9, and the average cell voltage is 4.72 V.

[0027] (3) After the reaction is completed, the electrolyte is discharged and the cathode 9 is taken out. The metal gallium deposited on the surface of the cathode 9 is melted and peeled off by water at 40°C. The surface of the cathode plate is polished with 800 Cw sandpaper and then enters the next production cycle.

[0028] The aforementioned pulse-enhanced electrowinning device for gallium recovery utilizes the relaxation of pulsed current to allow gallium ions to diffuse and transfer to the bottom cathode surface during current off-peak periods. This maintains a high concentration of the diffusion layer on the cathode surface, suppressing concentration polarization and allowing electrowinning to operate at higher current densities. Simultaneously, a porous structure or mesh anode improves the electrolyte flow field distribution and enhances convective mass transfer. This effectively increases current efficiency and reduces energy consumption. During electrolysis, the electrolyte temperature is controlled below the gallium melting point, causing metallic gallium to precipitate in solid form, effectively preventing its detachment and back-dissolution, further improving the gallium recovery rate.

Claims

1. An apparatus for recovering gallium by pulse-enhanced electrowinning, characterized in that, The system includes a pulse power supply, an electrolytic cell, and an electrolyte storage tank. The pulse power supply is connected to the cathode and anode via wires. The cathode and anode are placed in the electrolytic cell, and the average current density of the cathode is 500~2000 A / m. 2 The duty cycle is 30%~80%, the frequency is 1~100 Hz, and the electrolyte enters the electrolytic cell from the electrolyte storage tank through the electrolyte inlet pipe and the circulation pump, and flows back to the electrolyte storage tank through the electrolyte outlet pipe. An external temperature control component is provided for the electrolyte storage tank. The temperature control component includes a controller, a thermocouple, and a temperature control water jacket. The thermocouple is placed in the electrolyte storage tank, and the temperature control water jacket is fitted outside the electrolyte tank. The controller controls the temperature of the temperature control water jacket based on the real-time temperature monitoring of the thermocouple.

2. The apparatus for recovering gallium by pulse-enhanced electrowinning according to claim 1, characterized in that, Both the cathode and anode are made of SUS316.

3. The apparatus for recovering gallium by pulse-enhanced electrowinning according to claim 1, characterized in that, The anode has a porous or mesh structure.

4. The apparatus for recovering gallium by pulse-enhanced electrowinning according to claim 1, characterized in that, The electrolyte flows from the electrolyte storage tank into the electrolytic cell via a circulation pump at a velocity of 10~100 mm / s.

5. The apparatus for recovering gallium by pulse-enhanced electrowinning according to claim 1, characterized in that, In the initial state of the electrolyte in the electrolytic cell, the initial gallium concentration is 40~80 g / L, pH>14, and the gallium concentration at the end of electrolysis is less than 1 g / L.

6. The apparatus for recovering gallium by pulse-enhanced electrowinning according to claim 1, characterized in that, During the electrowinning process, the electrolyte temperature is controlled at 20~25℃ by a temperature control component.

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