Application and preparation device and method of high-purity solid gallium metal electrode

Abstract

The invention discloses an application and preparation device and method of a high-purity solid gallium metal electrode, and belongs to the technical field of production of scattered metal gallium. According to the method, high-purity solid gallium serves as an electrode for electrolytic refining of gallium, electrolysis is conducted at the specific temperature and current density, and the high current efficiency of 90% or above is achieved. Meanwhile, a plastic split type mold is used as an electrode shaping groove to prepare a solid gallium electrode, gallium is melted, poured into the electrode shaping groove, cooled in low-temperature equipment to be shaped, and taken out to obtain the electrode higher than the solid gallium electrode. When the solid gallium electrode is used for electrolytic refining of gallium, the electrolytic efficiency is high, electrolysis can be achieved at the room temperature, energy consumption and electrolyte volatilization are reduced, meanwhile, the solid gallium electrode prepared through the method is simple in preparation process, batch production can be achieved, other metal elements are not contained, and the solid gallium electrode is suitable for large-scale production. And the purity of the product after electrolytic refining is guaranteed.

Description

Technical Field

[0001] This invention belongs to the field of rare dispersed metal gallium production technology, and relates to the application, preparation device and method of a metal gallium electrode, which is applicable to the further purification of industrial gallium or crude gallium by electrolytic refining method. Background Technology

[0002] Gallium is a crucial raw material for producing semiconductors such as GaAs (gallium arsenide), GaP (gallium phosphide), GaSb (gallium antimonide), and GaN (gallium nitride). Gallium has a melting point of 29.78°C and exhibits thermal expansion and contraction upon solidification. It also possesses a high degree of supercooling, requiring very low temperatures to solidify. Gallium is classified by purity into 99.99% (4N), 99.999% (5N), 99.9999% (6N), 99.99999% (7N), and 99.999999% (8N). High-purity gallium is produced through a combination of one or more methods, including chemical extraction, electrolytic refining, vacuum distillation, and crystallization. In the electrolytic refining method, crude gallium is used as the anode, high-purity gallium as the cathode, and sodium hydroxide solution as the electrolyte. Under the application of an external current, the anode undergoes oxidation and dissolution, while the cathode undergoes reduction and deposition, ultimately yielding high-purity gallium.

[0003] In actual industrial production, stainless steel and platinum sheets are often used as electrode materials. These electrodes have strong adsorption and catalytic capabilities for hydrogen (H2). During electrolysis, a large amount of hydrogen gas is generated, accelerating electrolyte evaporation and reducing current efficiency. The current efficiency using stainless steel SU316 as an electrode is approximately 58.74%. Furthermore, electrode materials containing non-target products can alloy with gallium, leading to the introduction of impurities. Therefore, developing high-efficiency cathode materials that inhibit gallium evolution and suppress hydrogen evolution is crucial. Solid gallium, similar to zinc and tin, has a high hydrogen evolution overpotential and does not alloy, making it advantageous as an electrode. Patent CN101413135A mentions an electrolytic gallium electrode lead made of metallic gallium to address the corrosion problems of other metal leads. The electrode lead is used in an electrolyte at 50°C, requiring an external cooling device, which increases the complexity of the electrolysis apparatus and the energy consumption of the electrolysis process. Patent CN102011142A proposes a gallium electrolytic refining method using gallium sheets and electrodes made of platinum wire leads with a protective layer, but does not specify the electrode preparation method. In the solution provided by this patent, the platinum wire is also easily corroded by gallium and the electrolyte, producing impurities, and the use of precious metals increases production costs. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides an application, preparation apparatus, and method for a high-purity solid-state gallium metal electrode. The solid-state gallium electrode used has high purity, high current efficiency, and a simple preparation process, enabling excellent performance for mass production.

[0005] This invention provides an application of a high-purity solid gallium electrode in an electrolysis process, wherein the electrode has a purity of not less than 99.99%, operates at a temperature of 5℃ to 25℃, and a current density of 60 mA / cm². 2 ~100mA / cm 2 The electrolyte is a solution containing 1M~5M sodium hydroxide and 10g / L~80g / L sodium gallate. When the electrolysis time is 5h~10h, the current efficiency is over 90%.

[0006] A second aspect of the present invention provides an apparatus for preparing the high-purity solid gallium electrode, comprising a split mold;

[0007] The split mold is provided with an electrode fixing groove and two lead wire grooves;

[0008] The split mold consists of two symmetrical parts that form an electrode fixing groove; two lead wire grooves are located in the two parts that make up the split mold.

[0009] The specifications of the split mold are adapted to the specifications of the target electrode.

[0010] The material of the split mold includes one of polytetrafluoroethylene, polypropylene, polyethylene, polyvinyl chloride, and polystyrene.

[0011] When the electrode solidifies, it expands in volume, and the split mold makes it easy to remove the electrode.

[0012] A third aspect of the present invention provides a method for preparing the high-purity solid-state gallium electrode, which is implemented using the aforementioned apparatus and includes the following steps:

[0013] After melting gallium, pour it into an electrode solidification tank, scrape off the surface oxide layer, cool it in a low-temperature device to a liquid gallium solidification state, and then remove it to obtain a gallium electrode.

[0014] Gallium metal is added to the device by either adding it with a dropper or by direct pouring.

[0015] The purity of the gallium metal is not lower than that of the gallium in the target electrode;

[0016] The low-temperature equipment is a low-temperature blower incubator or a refrigerator;

[0017] The cooling temperature of liquid gallium solid-state is -50℃ to 0℃;

[0018] The cooling time for liquid gallium is the time required for gallium to completely solidify.

[0019] The innovation of this invention lies in:

[0020] 1. Regarding the device principle, in an alkaline environment, the gallium evolution reaction at the cathode is often accompanied by a strong hydrogen evolution reaction, resulting in low current efficiency. Therefore, it is necessary to find a metallic material with a high hydrogen evolution overpotential to suppress the hydrogen evolution reaction. Solid-state gallium has a high hydrogen evolution overpotential, similar in performance to aluminum, and has the potential to serve as a cathode for the electrolytic refining of gallium in alkaline solutions. Furthermore, a device capable of fabricating qualified gallium electrodes is needed.

[0021] 2. In terms of process, firstly, since gallium readily reacts with other metals to form alloys, this invention uses a device made of materials such as polytetrafluoroethylene (PTFE) to prepare solid-state gallium electrodes. This avoids alloying with other metals during electrode fabrication and alloying gallium deposited during electrolysis with the cathode, solving the problems of difficult electrode removal due to gallium alloying and deposition. Secondly, this invention controls the solid-state cooling temperature range to -50℃ to 0℃, reducing electrode brittleness and improving electrode toughness, thus preparing electrodes capable of performing electrochemical experiments normally. Finally, this invention prevents impurities from entering the electrode during operation, improving electrode purity and the purity of gallium electrolytically extracted.

[0022] 3. In terms of final performance, the high-purity solid gallium metal electrode of this invention does increase the hydrogen evolution overpotential and suppress the hydrogen evolution reaction, resulting in a significant improvement in current efficiency. The current efficiency is above 90%, which is much higher than other metal electrodes, and it can be used to prepare high-purity gallium and high-purity gallium electrodes.

[0023] Compared with the prior art, the advantages of this application are:

[0024] This invention proposes an application, preparation apparatus, and method for a gallium metal electrode, wherein the gallium metal electrode is used with GaO2. - The / Ga reaction exhibits a low potential, a high hydrogen evolution potential, and a current efficiency exceeding 90%. Furthermore, since gallium has a melting point of 29.76°C, the solid-state gallium electrode provided by this invention can be used at room temperature, reducing energy consumption and electrolyte evaporation. The solid-state gallium electrode provided by this invention does not contain other metallic elements, ensuring the purity of the product after electrolytic refining. Attached Figure Description

[0025] Figure 1 A diagram of the apparatus for fabricating gallium metal electrodes;

[0026] Among them, 1-split mold I, 2-split mold II, 3-electrode lead groove.

[0027] Figure 2 This is a photograph of the gallium metal electrode with a purity of 4N prepared in Example 1 of the present invention.

[0028] Figure 3 The hydrogen evolution electrode potential curves of the gallium metal electrode prepared for Example 1 in a gallium-free alkaline electrolyte; wherein, (a) the hydrogen evolution electrode potential curves of the gallium metal electrode at different temperatures, and (b) the hydrogen evolution electrode potential curves of the gallium metal electrode at different alkaline concentrations.

[0029] Figure 4 Gallium deposition electrode potential curves of the gallium electrode prepared for Example 1 in gallium-containing alkaline electrolyte; wherein, (a) gallium deposition electrode potential curves of the gallium electrode at different temperatures, and (b) gallium deposition electrode potential curves of the gallium electrode at different alkaline concentrations.

[0030] Figure 5 This is a schematic diagram showing the current efficiency of different cathode materials. Detailed Implementation

[0031] This invention provides an application of a high-purity solid gallium electrode in an electrolysis process. Solid metallic gallium with a purity greater than 99.99% is used as the electrode, and a mixed solution containing 1M~5M sodium hydroxide and 10g / L~80g / L sodium gallate is used as the electrolyte. The electrolysis is carried out at 5℃~25℃ and a current density of 60mA / cm². 2 ~100mA / cm 2 Under certain conditions, electrolysis for 5-10 hours yields metallic gallium with an electrolysis efficiency exceeding 90%.

[0032] This invention also provides an apparatus for fabricating the solid-state gallium metal electrode, comprising a split mold I and a split mold II, which are combined to form an electrode solidification groove; wherein electrode lead grooves are symmetrically arranged on the split mold I and the split mold II. The split mold I and the split mold II in this invention are made of one of polytetrafluoroethylene, polypropylene, polyethylene, polyvinyl chloride, and polystyrene. During electrode solidification, the volume expands, and the split mold facilitates the removal of the electrode.

[0033] The third aspect of the present invention provides a method for preparing the high-purity solid gallium metal electrode, comprising the following steps: melting gallium metal with a gallium purity not lower than that of the target electrode gallium purity, adding it by means of a dropper or directly pouring it into an electrode solidification tank, scraping off the surface oxide layer, placing it in a low-temperature device, and condensing it in an environment not higher than 0°C until the gallium is completely solidified to achieve solidification, and then taking it out to obtain the high-purity solid gallium metal electrode.

[0034] The apparatus for fabricating solid gallium metal electrodes provided by this invention can be adjusted according to the requirements of the target electrode to obtain gallium metal electrodes of different shapes and sizes.

[0035] The purity of the high-purity solid-state gallium electrode prepared by this invention depends on the purity of the product. For example, to produce 4N industrial gallium, at least 4N gallium is required to prepare the electrode. To produce 5N gallium, at least 5N gallium is required. To produce 6N high-purity gallium, at least 6N high-purity gallium is required. To produce 7N high-purity gallium, at least 7N high-purity gallium is required.

[0036] The plastic dropper used in the preparation of solid gallium electrolysis in this invention is a commercially available dropper made of PP or PE material.

[0037] The low-temperature equipment used in the cooling process of this invention can be a low-temperature blower incubator, a refrigerator, or an environment with a low temperature.

[0038] The solidification temperature of liquid gallium is -50℃ to 0℃. Generally, the lower the cooling temperature, the shorter the solidification time, and the higher the purity of the gallium metal, the longer the solidification time.

[0039] Those skilled in the art can obtain other similar device diagrams without any creative effort.

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] Example 1:

[0042] This embodiment provides an apparatus for fabricating the solid-state gallium metal electrode, including an electrode molding tank, such as... Figure 1 As shown, it is formed by combining split mold I 1 and split mold II 2, with electrode lead grooves 3 symmetrically arranged on split mold I and split mold II. The material of the split mold in this embodiment is polytetrafluoroethylene.

[0043] The preparation method of the solid gallium metal electrode with a purity of 4N in this embodiment includes the following steps: melting 4N gallium at 30°C, using a plastic dropper to draw an appropriate amount of liquid gallium, and dripping it into a mold (150mm on each side). The liquid gallium fills the electrode solidification groove and electrode lead groove 3. The gallium oxide film on the surface is scraped off. The mixture is cooled in a low-temperature forced-air incubator at a cooling temperature of -10°C for 12 hours until the liquid gallium is completely solidified. The apparatus is then removed, and the split mold I 1 and split mold II 2 are separated to obtain a solid gallium metal electrode with a purity of 4N. Figure 2 As shown.

[0044] This embodiment provides an application of a 4N pure solid gallium metal electrode in an electrolysis process. Using 4N pure solid gallium metal as the electrode, hydrogen evolution electrode potential curves were measured at different temperatures (10℃~25℃) and different alkali concentrations (1M~5M) in a gallium-free alkaline electrolyte (sodium gallate concentration of 0 g / L). Figure 3As shown, the gallium deposition electrode potential curves at different temperatures (10℃~25℃) and different alkali concentrations (1M~5M) were measured in a gallium-containing alkaline electrolyte (sodium gallate concentration of 40 g / L). Figure 4 As shown in the figure. A comparison of the hydrogen evolution potential and gallium evolution potential obtained by electrolysis of the electrode prepared in this embodiment in different electrolytes shows that the solid-state gallium electrode prepared in this embodiment suppresses the hydrogen evolution reaction and increases the hydrogen evolution overpotential. Specifically, a mixed solution containing 3M sodium hydroxide and 40 g / L sodium gallate was used as the electrolyte, and the electrolyte was prepared at 25°C and a current density of 60 mA / cm². 2 Under certain conditions, electrolysis for 10 hours yielded metallic gallium with an electrolysis efficiency of 94.56%. Figure 5 As shown.

[0045] Example 2:

[0046] In this embodiment, the apparatus used to prepare the solid gallium metal electrode with a purity of 5N is the same as that in Embodiment 1, except that: the material of the split mold I and the split mold II is polypropylene; the electrode molding groove is 250mm long and 400mm wide.

[0047] The method for preparing a solid gallium metal electrode with a purity of 5N in this embodiment includes the following steps: melting 5N gallium at 45°C, using a plastic dropper to draw an appropriate amount of liquid gallium and drop it into a mold (250mm long and 400mm wide), the liquid gallium fills the electrode solidification groove and electrode lead groove 3, scraping off the gallium oxide film on the surface, cooling in a low-temperature forced-air incubator at a cooling temperature of -15°C, maintaining the temperature for 10 hours, the liquid gallium completely solidifies, removing the device, separating the split mold I 1 and the split mold II 2, and obtaining a solid gallium metal electrode with a purity of 5N.

[0048] This embodiment provides an application of a 5N pure solid gallium metal electrode in an electrolysis process. The electrode is 5N pure solid gallium metal, and the electrolyte is a mixed solution containing 3M sodium hydroxide and 40g / L sodium gallate. The electrolysis is carried out at 25°C and a current density of 60mA / cm². 2 Under certain conditions, electrolysis for 10 hours yielded metallic gallium with an electrolysis efficiency of 93.78%. Figure 5 As shown.

[0049] Example 3:

[0050] In this embodiment, the apparatus used to prepare the solid gallium metal electrode with a purity of 6N is the same as that in Embodiment 1, except that the material of the split mold I 1 and the split mold II 2 is polyethylene; and the side length of the electrode solidification groove is 300mm.

[0051] The preparation method of the solid gallium metal electrode with a purity of 6N in this embodiment includes the following steps: melting 6N gallium at 55°C, using a plastic dropper to draw an appropriate amount of liquid gallium and drop it into the electrode solidification tank, the liquid gallium covering the electrode solidification tank and the electrode lead groove 3, scraping off the gallium oxide film on the surface, cooling in a low-temperature forced-air incubator at a cooling temperature of -25°C, maintaining the temperature for 8 hours, the liquid gallium completely solidifies, removing the device, separating the split mold I 1 and the split mold II 2, and obtaining the solid gallium metal electrode with a purity of 6N.

[0052] This embodiment provides an application of a 6N pure solid gallium metal electrode in an electrolysis process. The electrode is 6N pure solid gallium metal, and the electrolyte is a mixed solution containing 3M sodium hydroxide and 40g / L sodium gallate. The electrolysis is carried out at 25°C and a current density of 60mA / cm². 2 Under certain conditions, electrolysis for 10 hours yielded metallic gallium with an electrolysis efficiency of 95.04%. Figure 5 As shown.

[0053] Example 4:

[0054] In this embodiment, the apparatus used to prepare the solid gallium metal electrode with a purity of 7N is the same as that in Embodiment 1, except that the material of the split mold I 1 and the split mold II 2 is polyvinyl chloride; the electrode molding groove is 200mm long and 300mm wide.

[0055] The preparation method of the solid gallium metal electrode with a purity of 7N in this embodiment includes the following steps: melting 7N gallium at 35°C, using a plastic dropper to draw an appropriate amount of liquid gallium and drop it into the electrode solidification tank, the liquid gallium covering the electrode solidification tank and the electrode lead groove 3, scraping off the gallium oxide film on the surface, cooling in a low-temperature forced-air incubator at a cooling temperature of -45°C, maintaining the temperature for 5 hours, the liquid gallium completely solidifies, removing the device, separating the split mold I 1 and the split mold II 2, and obtaining the solid gallium metal electrode with a purity of 7N.

[0056] This embodiment provides an application of a 7N pure solid gallium metal electrode in an electrolysis process. The electrode is 7N pure solid gallium metal, and the electrolyte is a mixed solution containing 3M sodium hydroxide and 40g / L sodium gallate. The electrolysis is carried out at 25°C and a current density of 60mA / cm². 2 Under certain conditions, electrolysis for 10 hours yielded metallic gallium with an electrolysis efficiency of 94.47%. Figure 5 As shown.

[0057] Example 5:

[0058] In this embodiment, the apparatus used to prepare the solid gallium metal electrode with a purity of 4N is the same as that in Embodiment 1, except that the material of the split mold I 1 and the split mold II 2 is polystyrene; and the side length of the electrode solidification groove is 300mm.

[0059] The preparation method of the solid gallium metal electrode with a purity of 4N in this embodiment includes the following steps: melting 4N gallium at 65°C, using a plastic dropper to draw an appropriate amount of liquid gallium and drop it into the electrode solidification tank, the liquid gallium covering the electrode solidification tank and the electrode lead groove 3, scraping off the gallium oxide film on the surface, cooling in a low-temperature forced-air incubator at a cooling temperature of -50°C, maintaining the temperature for 2 hours, the liquid gallium completely solidifies, removing the device, separating the split mold I 1 and the split mold II 2, and obtaining the solid gallium metal electrode with a purity of 4N.

[0060] This embodiment provides an application of a 4N pure solid gallium metal electrode in an electrolysis process. The electrode is 4N pure solid gallium metal, and the electrolyte is a mixed solution containing 3M sodium hydroxide and 40g / L sodium gallate. The electrolysis is carried out at 25°C and a current density of 60mA / cm². 2 Under certain conditions, electrolysis for 10 hours yielded metallic gallium with an electrolysis efficiency of 94.77%. Figure 5 As shown.

[0061] The above-described embodiments are merely preferred embodiments of the present invention. It should be noted that those skilled in the art can make other improvements without departing from the principle of the present invention, and these improvements should be considered within the scope of protection of the present invention.

Claims

1. An application of a high-purity solid gallium metal electrode in an electrolysis process, characterized in that, The purity of the solid gallium electrode is not less than 99.99%. The application process is as follows: a mixed solution containing sodium gallate is used as the electrolyte. The solid gallium electrode is inserted into the electrolyte and electrolyzed at 5℃~25℃ and a set current density to obtain refined gallium. The electrolyte contains sodium gallate at a concentration of 10 g / L to 80 g / L. The electrolysis efficiency reaches over 90%.

2. The application of a high-purity solid gallium metal electrode according to claim 1 in the electrolysis process, characterized in that, The current density is 60 mA / cm². 2 ~100mA / cm 2 The electrolysis time is 5h~10h.

3. The application of a high-purity solid gallium metal electrode according to claim 1 in the electrolysis process, characterized in that, The electrolyte contains 1M to 5M sodium hydroxide.

4. An apparatus for preparing a high-purity solid-state gallium metal electrode according to claim 1 or 2, characterized in that, Including split molds; The split mold is provided with an electrode fixing groove and two lead wire grooves; The split mold consists of two symmetrical parts that form an electrode molding groove; two lead wire grooves are located in the two parts that make up the split mold. The material of the split mold includes one of polytetrafluoroethylene, polypropylene, polyethylene, polyvinyl chloride, and polystyrene.

5. The apparatus for preparing a high-purity solid-state gallium metal electrode according to claim 4, characterized in that, The specifications of the split mold are adapted to the specifications of the target electrode.

6. A method for preparing a high-purity solid gallium metal electrode according to claim 1 or 2, characterized in that, After melting gallium, pour it into an electrode solidification tank, scrape off the surface oxide layer, cool it to liquid gallium solidification in a low-temperature device, and then remove it to obtain a gallium electrode. The cooling temperature of liquid gallium solid-state is -50℃ to 0℃.

7. The method for preparing a high-purity solid gallium metal electrode according to claim 6, characterized in that, The cooling time for liquid gallium is the time required for gallium to completely solidify.

8. The method for preparing a high-purity solid gallium metal electrode according to claim 6, characterized in that, Gallium metal is added to the device by means of a dropper or by direct pouring.

9. The method for preparing a high-purity solid gallium metal electrode according to claim 6, characterized in that, The purity of the gallium metal is not lower than that of the gallium in the target electrode.

10. The method for preparing a high-purity solid gallium metal electrode according to claim 6, characterized in that, The low-temperature equipment refers to a low-temperature blower incubator and a refrigerator.

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