Preparation method of 6N-grade high-purity gallium oxide

Abstract

The invention discloses a preparation method of 6N-grade high-purity gallium oxide. The method comprises the following steps: directionally crystallizing and purifying a raw material metal gallium to obtain high-purity gallium; dissolving high-purity gallium in nitric acid, evaporating and concentrating, and crystallizing at low temperature to obtain gallium nitrate crystals; the preparation method comprises the following steps: dissolving gallium nitrate crystals in ultrapure water, and sequentially carrying out ammonia water neutralization and aging reaction to obtain a gallium oxide precursor solution; and filtering, washing, drying and calcining the gallium oxide precursor solution in sequence to obtain the gallium oxide photocatalyst. According to the method, directional crystallization and gallium nitrate recrystallization are effectively combined, so that the product purity is greatly improved, and the stability and continuity of product production are effectively ensured; according to the method, electrolysis and replacement with high-purity gallium at the grade of 5N or above are not needed, stable preparation of the 6N-grade gallium oxide can be achieved only through the 3-4N-grade metal gallium, and the problems that in the prior art, high-purity gallium is high in cost, and stable and continuous production is difficult are effectively solved.

Description

Technical Field

[0001] The invention relates to a method for preparing high-purity gallium oxide, in particular to a method for preparing 6N-grade high-purity gallium oxide, and belongs to the technical field of gallium oxide purification. Background Art

[0002] High-purity gallium oxide can be used to prepare GGG single crystals. As a material for bubble memory, this material has the advantages of high storage density, non-volatility, good reliability and easy miniaturization, and has a wide market in the fields of aerospace and intelligent robots. At the same time, this material is also used as an insulating layer for Ga-based semiconductor materials, ultraviolet filters, and O 2 Chemical detectors.

[0003] In the prior art, the preparation methods of high-purity gallium oxide are generally chemical deposition, electrolytic refining, zone melting, vacuum distillation, directional crystallization and combined methods. Among them, high-purity gallium oxide with a purity of 5N or above is mostly purified by electrolytic refining. Chinese patent (CN117069139A) discloses a method for preparing high-purity gallium oxide by acid electrolysis, comprising the following steps: (1) acid washing crude gallium to obtain pretreated crude gallium; (2) placing the pretreated crude gallium obtained in step (1) as an anode in an electrolytic cell containing an acidic electrolyte for electrochemical dissolution to obtain a gallium-containing solution; (3) replacing the gallium-containing solution obtained in step (2) with high-purity gallium to remove impurities, and performing liquid-solid separation to obtain a gallium-containing purified solution; (4) neutralizing the gallium-containing purified solution obtained in step (3) with ammonia water to precipitate gallium to obtain gallium hydroxide precipitate; (5) drying and roasting the gallium hydroxide precipitate obtained in step (4) to obtain 6N high-purity gallium oxide.

[0004] However, on the one hand, this method requires the dissolution of crude gallium by electrolysis, which consumes too much energy. On the other hand, it also requires the use of 5~6N high-purity gallium to replace the crude gallium, which further greatly increases the preparation cost. In addition, the process is complicated and has extremely high requirements for the operating environment, equipment and raw materials, making it difficult to achieve large-scale production of 6N high-purity gallium. Summary of the invention

[0005] In view of the problems existing in the prior art, the first object of the present invention is to provide a method for preparing 6N grade high-purity gallium oxide. The method is based on the synergistic effect between the various steps. The raw metal gallium is purified by directional crystallization, and then further purified by recrystallization of gallium nitrate. It is then converted into gallium hydroxide by a neutralization reaction of ammonia water. Finally, the residual nitrate and ammonium are completely gasified and removed by high-temperature calcination to obtain 6N grade high-purity gallium oxide.

[0006] In order to achieve the above technical objectives, the present invention provides a method for preparing 6N grade high-purity gallium oxide, characterized in that it comprises: 1) The raw metal gallium is purified by directional crystallization to obtain high-purity gallium; 2) Dissolve high-purity gallium in nitric acid, evaporate and concentrate it, and then crystallize it at low temperature to obtain gallium nitrate crystals; 3) Dissolving gallium nitrate crystals in ultrapure water, and then subjecting the mixture to neutralization with ammonia and aging reactions to obtain a gallium oxide precursor solution; 4) The gallium oxide precursor solution is filtered, washed, dried and calcined in sequence to obtain.

[0007] The method provided by the present invention does not require electrolysis throughout the process, and only utilizes the crystallization or recrystallization reaction between the raw materials to achieve product purification. Therefore, the process between each step must be strictly executed in accordance with the above requirements. The replacement or deletion of any step will lead to a decrease in the purity of the intermediate product, thereby affecting the purity of the final product.

[0008] As a preferred solution, the raw metal gallium is 3~4N grade refined gallium.

[0009] As a preferred solution, the purity of the high-purity gallium is higher than that of raw metal gallium, which is 4~5N level.

[0010] As a preferred solution, the crystallization temperature of the directional crystallization is 5-10°C.

[0011] As a preferred solution, the number of directional crystallization is 5 to 10 times.

[0012] As a preferred solution, the purity of the nitric acid is UP grade, and its concentration is 65-70%.

[0013] As a preferred solution, the mass ratio of the metal gallium to nitric acid is 1:4-4.5.

[0014] As a preferred solution, at 80-100° C., a nitric acid solution containing high-purity gallium is evaporated until transparent crystals appear on the surface.

[0015] As a preferred solution, the conditions for the low-temperature crystallization are: temperature of 6-10°C and time of 3-5h.

[0016] As a preferred solution, the purity of the ammonia water is UP grade, and its concentration is 25-28%.

[0017] As a preferred solution, the pH of the neutralization reaction is 7-8.

[0018] As a preferred solution, the gallium nitrate is dissolved in ultrapure water with a gallium ion concentration of 20-60 g / L.

[0019] As a preferred solution, the conditions of the aging reaction are: temperature of 80-100°C and time of 24-48h. After the neutralization reaction, the system generates gallium hydroxide, which needs to be aged to be converted into gallium oxyhydroxide powder before subsequent calcination. This is because, on the one hand, it is difficult to remove the residual ammonium nitrate in the gallium hydroxide colloid by washing, resulting in a decrease in the purity of the subsequent product. On the other hand, gallium hydroxide is in a colloidal state, and direct calcination will form agglomerated gallium oxide blocks, and powdered gallium oxide cannot be obtained.

[0020] As a preferred solution, the filtering method is suction filtration, and the filter cloth material used is high-purity polytetrafluoroethylene.

[0021] As a preferred solution, the drying method is one of vacuum drying, oven drying and freeze drying.

[0022] As a preferred solution, when the drying method is oven drying, the process is: drying the powder obtained after filtering and washing at 100-120°C to constant weight.

[0023] As a preferred solution, the powder obtained after drying is placed in a high-purity alumina crucible in a sealed state and calcined at 700-850° C. for 4-8 hours.

[0024] Compared with the prior art, the beneficial technical effects of the technical solution of the present invention are: 1) The preparation method provided by the present invention is based on the synergistic effect between the various steps. The raw material metal gallium is purified by directional crystallization, and then further purified by recrystallization of gallium nitrate, and then converted into gallium hydroxide by neutralization reaction of ammonia water. Finally, the residual nitrate and ammonium are completely gasified and removed by high-temperature calcination to obtain 6N grade high-purity gallium oxide.

[0025] 2) In the technical solution provided by the present invention, the focus is on effectively combining directional crystallization with gallium nitrate recrystallization, which greatly improves the purity of the product while effectively ensuring the stability and continuity of product production; in the present invention, there is no need for electrolysis and replacement with high-purity gallium of grade 5N or above, and the stable preparation of 6N grade gallium oxide can be achieved only by 3~4N grade metallic gallium, which effectively solves the problem of high cost and difficulty in stable and continuous production of high-purity gallium in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a graph showing the GD-MS test results of 6N grade gallium oxide obtained in Example 2 of the present invention. DETAILED DESCRIPTION

[0027] In order to facilitate the understanding of the present invention, the present invention will be described in more comprehensive and detailed manner in conjunction with the accompanying drawings and preferred embodiments of the specification. It should be noted that the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0028] Example 1 Take 4N gallium metal and carry out directional crystallization in a crystallization furnace, adjust the crystallization temperature to 6°C, repeat crystallization for 7 times, add gallium metal to a beaker, add up-grade nitric acid until the gallium metal is completely dissolved, heat and evaporate the gallium-containing solution until transparent crystals appear on the surface of the solution, end heating, and cool the gallium nitrate solution to crystallize at 6°C for 3 hours. After solid-liquid separation, solid gallium nitrate crystals are added back to the beaker, pure water is added and stirred until the gallium nitrate is completely dissolved. The solution is diluted to a gallium ion concentration of 25 g / L, and up-grade ammonia water is added under stirring to adjust the pH to 7. After sealing the beaker, age at 85°C for 24 hours. After aging, filter and wash, remove the liquid, and dry the remaining powder at 105°C to constant weight. The powder is taken out and added to an alumina crucible washed with pure water, and then sealed and calcined at 700°C for 4 hours to finally obtain 6N gallium oxide.

[0029] Example 2 Take 3N gallium metal and carry out directional crystallization in a crystallization furnace, adjust the crystallization temperature to 5°C, repeat crystallization for 10 times, add gallium metal to a beaker, add up-grade nitric acid until gallium metal is completely dissolved, heat and evaporate the gallium-containing solution until transparent crystals appear on the surface of the solution, end heating, and cool the gallium nitrate solution to crystallize at 10°C for 5 hours. After solid-liquid separation, solid gallium nitrate crystals are added back to the beaker, pure water is added and stirred until gallium nitrate is completely dissolved, and the solution is diluted to a gallium ion concentration of 50 g / L. Up-grade ammonia water is added under stirring to adjust the pH to 8, and the beaker is sealed and aged at 95°C for 48 hours. After aging, it is filtered and washed, and the remaining powder after removing the liquid is dried at 110°C to constant weight. The powder is taken out and added to an alumina crucible washed with pure water, and then sealed and calcined at 850°C for 4 hours to finally obtain 6N gallium oxide.

[0030] Comparative Example 1 3N gallium metal was taken for directional crystallization in a crystallization furnace, the crystallization temperature was adjusted to 5°C, and after repeated crystallization for 10 times, the gallium metal was added to a beaker, and up-grade sulfuric acid diluted with pure water to 20% was added until the gallium metal was completely dissolved. The gallium-containing solution was heated and evaporated until transparent crystals appeared on the surface of the solution, and the heating was terminated. The gallium sulfate solution was cooled and crystallized at 10°C for 5 hours. After solid-liquid separation, the solid gallium sulfate crystals were added back to the beaker, and pure water was added and stirred until the gallium sulfate was completely dissolved. The solution was diluted to a gallium ion concentration of 80 g / L, and up-grade ammonia water was added under stirring to adjust the pH to 8. After the beaker was sealed, it was aged at 95°C for 48 hours. After the aging was completed, it was filtered and washed. After removing the liquid, the remaining powder was dried at 110°C to constant weight. The powder was taken out and added to an alumina crucible washed with pure water. After sealing, it was calcined at 850°C for 4 hours. The S content in the final gallium oxide reached 200 ppm. After calcination at 1000°C for 4 hours, the S content still did not decrease, and 6N gallium oxide could not be obtained.

Claims

1. A method for preparing 6N grade high-purity gallium oxide, characterized in that: include: 1) The raw metal gallium is purified by directional crystallization to obtain high-purity gallium; 2) Dissolve high-purity gallium in nitric acid, evaporate and concentrate it, and then crystallize it at low temperature to obtain gallium nitrate crystals; 3) Dissolving gallium nitrate crystals in ultrapure water, and then subjecting the mixture to neutralization with ammonia and aging reactions to obtain a gallium oxide precursor solution; 4) The gallium oxide precursor solution is filtered, washed, dried and calcined in sequence to obtain.

2. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The raw metal gallium is 3~4N grade refined gallium; the purity of the high-purity gallium is higher than that of the raw metal gallium, which is 4~5N grade.

3. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The crystallization temperature of the directional crystallization is 5-10° C.; the number of directional crystallizations is 5-10 times.

4. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The purity of the nitric acid is UP grade, and its concentration is 65-70%; the mass ratio of the metal gallium to the nitric acid is 1:4-4.

5.

5. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The evaporation concentration process is as follows: at 80-100° C., a nitric acid solution containing high-purity gallium is evaporated until transparent crystals appear on the surface; the low-temperature crystallization conditions are as follows: a temperature of 6-10° C. and a time of 3-5 hours.

6. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The purity of the ammonia water is UP grade, and its concentration is 25-28%; the pH of the neutralization reaction is 7-8.

7. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The gallium nitrate is dissolved in ultrapure water, with a gallium ion concentration of 20-60 g / L; the aging reaction conditions are: temperature of 80-100° C., and time of 24-48 h.

8. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The filtering method is suction filtration, and the filter cloth material used is high-purity polytetrafluoroethylene.

9. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The drying method is one of vacuum drying, oven drying and freeze drying; when the drying method is oven drying, the process is: drying the powder obtained after filtering and washing at 100-120° C. to constant weight.

10. The method for preparing 6N grade high purity gallium oxide according to claim 1, characterized in that: The calcination process is as follows: in a sealed state, the dried powder is placed in a high-purity alumina crucible and calcined at 700-850° C. for 4-8 hours.

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