Method for extracting gallium from gallium arsenide leachate in hydrofluoric acid and nitric acid mixed system

Abstract

The invention provides a method for extracting gallium from gallium arsenide lixivium under a hydrofluoric acid and nitric acid mixed system, and belongs to the technical field of rare metal metallurgy, the method comprises the following steps: adding sodium salt into the gallium arsenide lixivium to obtain fluorine-containing filter residues and fluorine-removed filtrate; adjusting the pH value of the defluorination filtrate to 5.0-5.5 by using liquid caustic soda to obtain gallium-containing filter residues; the fluorine-containing filter residues are subjected to acid pickling, a first acid pickling solution is obtained, and the first acid pickling solution is mixed with the gallium arsenide leaching solution in the step S1; dissolving the gallium-containing filter residues by adopting a strong acid solution to obtain a gallium-containing solution, and adding sodium sulfide to remove arsenic to obtain arsenic-containing filter residues and arsenic-removed filtrate; adjusting the pH value of the arsenic-removed filtrate to be greater than 12 by adopting caustic soda liquid, and filtering to obtain gallium-rich filtrate; and carrying out electro-deposition to obtain gallium metal. According to the method, gallium in a complex leaching solution system is transferred into a single system to be extracted by utilizing the characteristic that gallium hydroxide is an amphoteric hydroxide, so that the loss of gallium in the process of removing arsenic and other impurities is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of rare metal metallurgy, and particularly relates to a method for extracting gallium from a gallium arsenide leaching solution in a hydrogen fluoride and nitric acid mixed system. BACKGROUND

[0002] Gallium (Ga) is one of the important scattered metals, and gallium arsenide (chemical formula GaAs) has become one of the most important compound semiconductor materials at present due to its high frequency, high electron mobility, low noise, high output power, low power consumption, high efficiency, good linearity, and poor distortion. The consumption fields of metal gallium in China include semiconductor and photoelectric materials, solar cells, alloys, medical devices, magnetic materials, etc., and the consumption of gallium in the semiconductor industry accounts for 80% to 85% of the total consumption of gallium, which is the main application field of metal gallium. With the rapid development of downstream application industries of gallium, especially the semiconductor industry and the solar cell industry, the demand for metal gallium will also steadily increase in the future. With the development of economy in recent years, a large amount of gallium-containing waste such as semiconductor will be generated. At present, GaAs waste is the largest category of gallium-containing electronic waste recycling, mainly including GaAs thin film solar cell waste and wastewater waste generated during the preparation of GaAs chips in the semiconductor industry.

[0003] Due to the presence of As in GaAs, which can pose a threat to the environment, and is difficult to separate, it is difficult to directly recycle. At present, the main recovery processes are mainly divided into three kinds of wet leaching, pyrometallurgy and bioleaching. Pyrometallurgy is limited by the high equipment and energy consumption costs, and the bioleaching method is not mainstream due to its low leaching efficiency. Chinese patent CN111440955B discloses a method for extracting gallium from gallium-containing smelting slag, which uses alkali and calcium source to remove impurities, and then electrolyzes to obtain high-purity gallium. However, the gallium smelting slag also contains a large amount of fluoride ions, which will combine with gallium ions and hinder the formation of gallium hydroxide precipitate to some extent, affecting the extraction rate of gallium ions; and when removing metal ion impurities such as As, it will also cause the loss of gallium ions, thereby affecting the recovery rate of gallium ions. SUMMARY

[0004] In view of the technical problems in the background art, the present application provides a method for extracting gallium from a gallium arsenide leaching solution in a hydrogen fluoride and nitric acid mixed system, which aims to solve the technical problem of low gallium recovery rate in the process of recovering gallium by wet leaching.

[0005] In a first aspect, the embodiments of the present application provide a method for extracting gallium from a gallium arsenide leaching solution in a hydrogen fluoride and nitric acid mixed system, which comprises the following steps: S1, adding a sodium salt to the gallium arsenide leaching solution, and filtering after reaction to obtain a fluorine-containing residue and a fluorine-removed filtrate; S2, adjust the pH of the fluoride-removed filtrate to 5.0-5.5 using liquid alkali, stir and react, and then filter to obtain a gallium-containing residue; The fluoride-containing residue is subjected to acid washing to obtain a first acid washing liquid, and the first acid washing liquid is mixed with the gallium arsenide leaching liquid in step S1; S3, dissolve the gallium-containing residue using a strong acid solution to obtain a gallium-containing solution, add sodium sulfide to the gallium-containing solution to remove arsenic, and then filter to obtain an arsenic-containing residue and an arsenic-removed filtrate; S4, adjust the pH of the arsenic-removed filtrate to be greater than 12 using liquid alkali, and then filter to obtain a gallium-rich filtrate; S5, perform electrodeposition on the gallium-rich filtrate to obtain gallium metal.

[0006] In some embodiments, the molar ratio of the sodium salt to the fluoride ions in the gallium arsenide leaching liquid in step S1 is (2-3):1; The sodium salt includes at least one of sodium chloride, sodium carbonate, sodium sulfate, and sodium bicarbonate.

[0007] In some embodiments, the concentration of the sulfuric acid solution used for acid washing in step S2 is 0.1-2 mol / L; The volume ratio of the sulfuric acid solution to the fluoride-containing residue is (2-3):1.

[0008] In some embodiments, the strong acid solution in step S3 includes a sulfuric acid solution; The volume ratio of the strong acid solution to the gallium-containing residue is (1-4):1.

[0009] In some embodiments, the molar ratio of the sodium sulfide to the arsenic ions in the gallium-containing solution in step S3 is (2-5):1.

[0010] In some embodiments, the concentration of the liquid alkali in step S4 is 100-150 g / L.

[0011] In some embodiments, the electrodeposition voltage in step S5 is 2-5 V.

[0012] In some embodiments, the arsenic-containing residue in step S3 is subjected to acid washing to obtain a second acid washing liquid, and the second acid washing liquid is mixed with the gallium-containing solution.

[0013] In some embodiments, the electrolysis liquid obtained after electrodeposition is mixed with the arsenic-removed filtrate.

[0014] In some embodiments, the gallium arsenide leaching liquid includes SiO3 2- 7-25 g / L, F - 30-100 g / L, Ca 2+ 10-60 g / L, AsO4 3- 10-60 g / L, NO3 - 120-350 g / L, Fe 3+< 1 g / L.

[0015] Compared with the prior art, the application has the following beneficial effects: The application firstly removes fluorine ions by using sodium salt to remove the interference of fluorosilicate on subsequent gallium extraction, then precipitates gallium ions by using lye to remove nitrate, and then dissolves gallium-containing filter residue by using a sulfuric acid solution, and then adds sulfide to remove arsenic, so that a relatively pure arsenic-removed filtrate is obtained, and then the pH is adjusted to above 12 to remove iron ions and other impurities, so that a gallium-rich filtrate is obtained, and finally the gallium-rich filtrate is subjected to electrodeposition to obtain gallium metal. The application takes advantage of the characteristics of gallium hydroxide as an amphoteric hydroxide to transfer gallium in a complex leaching solution system to a single system for gallium extraction, greatly reduces the loss of gallium in the process of removing arsenic and other impurities, simplifies the process flow, improves the recovery rate of gallium metal, and greatly reduces the operating cost in industrial production.

[0016] The above description is only a summary of the technical solutions of the application, in order to enable the technical means of the application to be more clearly understood and implemented according to the content of the specification, and in order to enable the above and other purposes, characteristics and advantages of the application to be more obvious and easy to understand, the following specific embodiments of the application will be described. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings used in the application. Obviously, the drawings described below are only some embodiments of the application, and other drawings can also be obtained by those skilled in the art without creating any creative labor on the basis of these drawings.

[0018] Figure 1 Process flow chart for the embodiments of the application. DETAILED DESCRIPTION

[0019] The embodiments of the technical solutions of the application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the application, and therefore only serve as examples, and cannot limit the protection scope of the application.

[0020] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the application; the terms "include" and "have" and any variations thereof in the specification and claims of the application and the above drawing description are intended to cover non-exclusive inclusion.

[0021] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited.

[0022] The gallium smelting slag also contains a large amount of fluoride ions, which will combine with gallium ions and hinder the formation of gallium hydroxide precipitate to some extent, affecting the extraction rate of gallium ions; and when removing metal ion impurities such as As, it will also cause loss of gallium ions, thereby affecting the recovery rate of gallium ions.

[0023] In order to solve the technical problem of low gallium recovery rate in the process of recovering gallium by wet leaching, the present application provides a method for extracting gallium from gallium arsenide leaching solution in a mixed system of hydrofluoric acid and nitric acid, as shown in Figure 1 The method comprises the following steps: S1, sodium salt is added to the gallium arsenide leaching solution, and after reaction, filtration is performed to obtain fluorine-containing filter residue and fluorine-removed filtrate. The sodium salt can react with fluorosilicate to form sodium fluorosilicate precipitate, and the reaction equation is as follows (1). If fluorosilicate is not removed preferentially, it will hinder the formation of gallium hydroxide precipitate from gallium ions and hydroxide, so sodium salt is added in the first step to remove the interference of fluorosilicate on the subsequent process.

[0024] H2SiF6+2Na→Na2SiF6↓+2HCl↑(1).

[0025] S2, adjust the pH of the fluorine-removed filtrate to 5.0-5.5 by using liquid alkali, stir and react, and then filter to obtain gallium-containing filter residue and gallium-precipitated liquid. Gallium ions form gallium hydroxide precipitate under the condition of pH 5.0-5.5, which can remove nitrate in the gallium arsenide leaching solution.

[0026] The fluorine-containing filter residue is subjected to acid pickling, and the first acid pickling liquid and the acid pickling fluorine-removal residue are obtained by filtration. The first acid pickling liquid is mixed with the gallium arsenide leaching solution in step S1; sodium hexafluorosilicate will entrain part of the gallium ions during the precipitation process. The fluorine-containing filter residue is subjected to acid pickling, and sodium hexafluorosilicate is insoluble in acid, so that the gallium ions in it can be dissolved out. The first acid pickling liquid containing gallium is mixed with the gallium arsenide leaching solution, so that the gallium ions in it can be recovered, thereby ensuring that the loss of gallium is <0.5%.

[0027] S3, dissolve the gallium-containing filter residue by using a strong acid solution to obtain a gallium-containing solution, add sodium sulfide to the gallium-containing solution to remove arsenic, and filter to obtain arsenic-containing filter residue and arsenic-removed filtrate. After the gallium-containing filter residue is dissolved by using a strong acid solution, sodium sulfide is added to it, which can generate arsenic sulfide precipitate, thereby removing arsenic in the gallium arsenide leaching solution, so that arsenic and gallium are separated.

[0028] S4, the arsenic removal filtrate is adjusted to pH greater than 12 by using liquid alkali, and a gallium-rich filtrate is obtained after filtration. Gallium hydroxide is soluble in strong acid and strong alkali. When the pH of the arsenic removal filtrate is adjusted to greater than 12, gallium hydroxide is still in a dissolved state, while metal ions such as iron ions form hydroxide precipitates, thereby separating out impurities such as iron, and a gallium-rich filtrate with higher purity is obtained after filtration and separation.

[0029] S5, the gallium-rich filtrate is subjected to electrodeposition to obtain gallium metal. A stainless steel plate is used as an electrode, and metal gallium is electrodeposited to the cathode under a voltage of 2-5V.

[0030] In some embodiments, the molar ratio of sodium salt to fluoride ions in the gallium arsenide leaching solution in step S1 is (2-3):1. The sodium salt includes at least one of sodium chloride, sodium carbonate, sodium sulfate, and sodium bicarbonate.

[0031] In some embodiments, the concentration of the sulfuric acid solution used in the pickling in step S2 is 0.1-2 mol / L. The volume ratio of the sulfuric acid solution to the fluorine-containing residue is (2-3):1.

[0032] In some embodiments, the strong acid solution in step S3 includes a sulfuric acid solution. The volume ratio of the strong acid solution to the gallium-containing residue is (1-4):1.

[0033] In the technical solution of the embodiments of the present application, the strong acid solution does not include a strong acid solution containing chloride ions, which avoids corrosion of the electrode plate during the subsequent electrodeposition process.

[0034] In some embodiments, the molar ratio of sodium sulfide to arsenic ions in the gallium-containing solution in step S3 is (2-5):1.

[0035] In some embodiments, the concentration of the liquid alkali in step S4 is 100-150 g / L.

[0036] In some embodiments, the electrodeposition voltage in step S5 is 2-5V.

[0037] In some embodiments, the arsenic-containing residue is subjected to pickling in step S3 to obtain a second pickling solution, and the second pickling solution is mixed with the gallium-containing solution.

[0038] In the technical solution of the embodiments of the present application, after the arsenic-containing residue is subjected to pickling, arsenic sulfide is insoluble in the sulfuric acid solution, which can dissolve out the gallium ions therein, thereby improving the recovery rate of gallium.

[0039] In some embodiments, the electrolysis solution obtained after electrodeposition is mixed with the arsenic removal filtrate.

[0040] In the technical scheme of the embodiment of the present application, the electrolysis solution also contains a certain amount of unreacted gallium ions, and the recovery rate of gallium can be improved by mixing the electrolysis solution with the arsenic removal filtrate and then performing electrodeposition.

[0041] In some embodiments, the gallium arsenide leaching solution includes SiO3 2- 7~25g / L, F - 30~100g / L, Ca 2+ 10~60g / L, AsO4 3- 10~60g / L, NO3 - 120~350g / L, Fe 3+ <1g / L.

[0042] Some specific examples are listed below, it should be noted that the examples described below are exemplary, only for explaining the present application, and can not be understood as limiting the present application. The specific technology or condition not noted in the examples is carried out according to the technology or condition described in the literature in the art or according to the product instruction. The reagent or instrument not noted by the manufacturer is a conventional product that can be obtained by market purchase.

[0043] I. Preparation method Example 1 The method for extracting gallium from gallium arsenide leaching solution in a mixed system of hydrofluoric acid and nitric acid includes the following steps: S1, 115g of sodium chloride is added to 500mL of gallium arsenide leaching solution, and fluoride is removed under room temperature conditions for 1h, and after filtration, fluoride-containing filter residue and fluoride removal filtrate are obtained.

[0044] S2, liquid alkali is added to the fluoride removal filtrate, the pH is adjusted to 5.36, gallium is precipitated by stirring and reacting, and after filtration, gallium-containing filter residue is obtained.

[0045] The fluoride-containing filter residue is washed with dilute sulfuric acid under the condition of water bath at 70℃ for 1h, and after filtration, the fluoride-containing filter residue after acid washing and the first acid washing liquid are obtained, and the first acid washing liquid is returned to be mixed with the gallium arsenide leaching solution in step S1.

[0046] S3, the gallium-containing filter residue is added to a sulfuric acid solution, and is completely dissolved by stirring at 70℃ to obtain a gallium-containing solution, 105g of sodium sulfide is added to the gallium-containing solution, and is reacted at room temperature for 2h, and after filtration, arsenic-containing filter residue and arsenic removal filtrate are obtained; S4, the arsenic removal filtrate is adjusted to pH 13 by liquid alkali, and after filtration, a gallium-rich filtrate is obtained; S5, the arsenic-containing filter residue is washed with a sulfuric acid solution to obtain a second acid washing liquid and an acid-washed arsenic-containing filter residue, and the second acid washing liquid is mixed with the gallium-containing solution to recover gallium, The gallium-rich filtrate is electrolyzed at 40℃, the cathode and anode both use stainless steel electrodes, the electrolysis voltage is 5V, and the electrolysis time is 32h. Pure gallium is obtained on the cathode plate.

[0047] Comparative Example 1 15g of sodium sulfide is added to 300mL of gallium arsenide leaching solution, and the precipitation reaction is carried out for 2h. After filtration, arsenic-containing residue and arsenic-removed solution are obtained.

[0048] Comparative Example 2 12g of sodium chloride is added to 150mL of gallium arsenide leaching solution, and the reaction is carried out for 1h at room temperature to remove fluorine. After filtration, fluorine-containing residue and fluorine-removed filtrate are obtained.

[0049] 30g of sodium sulfide is added to the fluorine-removed filtrate, and the reaction is carried out for 1h at room temperature to remove arsenic. After filtration, arsenic-containing residue and arsenic-removed solution are obtained.

[0050] II. Test Methods 1. Detection method of fluorine (F - ) Fluorine mainly exists in the form of free fluoride ion (F - ) or fluoride in solution. Spectrophotometry (alizarin sulfonate colorimetry) is used.

[0051] Principle: Under acidic conditions, F - reacts with alizarin sulfonate complex to change the color of the solution from red-violet to yellow. The concentration of F - is quantified by the change in absorbance.

[0052] 2. Detection method of silicon (Si) Silicon in solution mainly exists in the form of silicate (SiO3 2- ), silicic acid (H2SiO3) or colloidal silicon. Molybdenum blue spectrophotometry is usually used.

[0053] Principle: Under acidic conditions, silicate (SiO3 2- ) reacts with ammonium molybdate to form yellow silicon molybdenum heteropoly acid (silicon molybdenum yellow). A reducing agent (such as ascorbic acid, ferrous ammonium sulfate) is added to reduce it to blue silicon molybdenum blue. The concentration of silicon is quantified by the absorbance at 660nm.

[0054] 3. Detection method of arsenic (As) Arsenic in solution may exist in the form of As 3+ , As 5+ , organic arsenic (such as methyl arsenic), etc. It needs to be converted into inorganic arsenic through pretreatment (such as acidification, reduction) before detection. Inductively coupled plasma mass spectrometry (ICP-MS) is usually used.

[0055] Principle: arsenic ions are ionized in plasma, separated and detected by mass spectrometer for mass-to-charge ratio (As) 75 As), and quantified by ion counting.

[0056] 4. Method for detecting gallium (Ga) Gallium is a rare metal, and in solution, it is mostly in the form of Ga 3+ , and its concentration is usually low. Therefore, inductively coupled plasma mass spectrometry (ICP-MS) is usually used.

[0057] Principle: Ga 3+ is ionized in plasma to Ga + , and its mass-to-charge ratio (Ga 69 , Ga 71 ) is detected by a mass spectrometer to quantify the concentration.

[0058] III. Analysis of test results of each embodiment and comparative example The concentrations and contents (content = concentration x volume) of F, Si, As and Ca elements in the filtrate and filter residue obtained in each step in Example 1 were detected, and the removal rate and recovery rate of each element were calculated. The specific detection data are shown in Tables 1-7 below.

[0059] The contents of each element in the gallium arsenide leaching solution and the fluoride removal filtrate in detection step S1 were detected, and the detection data are shown in Table 1.

[0060] Table 1. Detection data table of sodium chloride for fluoride removal

[0061] As can be seen from Table 1, sodium chloride (2.46 times the molar amount of F - in the gallium arsenide leaching solution) is added to the gallium arsenide leaching solution for fluoride removal, and the fluoride removal rate reaches more than 95%, but there is a loss of about 15% Ga, because the sodium fluorosilicate precipitate generated by the reaction of sodium chloride with fluorosilicate will entrain part of the gallium ions.

[0062] The mass fraction and content of each element in the acid washing fluoride removal residue obtained after acid washing of the fluoride-containing filter residue in step S2 were detected, and the detection results are shown in Table 2.

[0063] Table 2. Detection data table of acid washing fluoride removal residue

[0064] In the acid washing fluoride removal residue obtained after acid washing of the fluoride-containing filter residue, the Ga content is less than 0.5%, and the loss of Ga is controlled to be below 100 mg, indicating that the recovery rate of Ga can be greatly improved after acid washing.

[0065] The pH of the defluorinated filtrate is adjusted to 5.36 in step S2 by using a lye to precipitate gallium, and a gallium-containing residue and a post-gallium-precipitation solution are obtained by filtration, which is used to remove nitrate. The elements in the post-gallium-precipitation solution are detected, and the detection results are shown in Table 3 below.

[0066] Table 3 Detection data table of post-gallium-precipitation solution

[0067] As can be seen from Table 3, when the pH is adjusted to 5-6, the gallium precipitation rate reaches 99.9%, and the gallium in the post-gallium-precipitation solution is below 30 mg / L.

[0068] In step S3, the gallium-containing residue is dissolved by using a sulfuric acid solution to obtain a gallium-containing solution, and the concentrations and contents of various elements in the gallium-containing solution are detected, and the detection results are shown in Table 4 below.

[0069] Table 4 Monitoring data of gallium-containing solution

[0070] As can be seen from Table 4, the gallium dissolution rate is 89.03%, and the arsenic dissolution rate is 95.03%.

[0071] In step S3, sodium sulfide (1.56 times the molar amount of arsenic) is added to the gallium-containing solution to obtain an arsenic-containing residue and an arsenic-removal filtrate, and the contents and concentrations of various elements therein are detected, and the detection data are shown in Table 5 below.

[0072] Table 5 Detection data of arsenic-containing residue and arsenic-removal filtrate

[0073] As can be seen from Table 5, after adding 1.56 times of sodium sulfide to remove arsenic, the arsenic removal rate is 100%, and gallium is also lost.

[0074] In step S5, gallium is recovered after acid washing of the arsenic-containing residue, and the recovery rate is above 96%, and the gallium in the acid-washed arsenic-containing residue is controlled to be below 1%, and the detection data are shown in Table 6 below.

[0075] Table 6 Detection data of acid-washed arsenic-containing residue

[0076] In steps S4-S5, the pH of the arsenic-removal filtrate is adjusted to 12-13 to obtain a gallium-rich filtrate, and then electrolysis is performed to obtain a post-electrolysis solution, and the contents of various elements therein are detected, and the detection results are shown in Table 7 below.

[0077] Table 7 Detection data of gallium-rich filtrate and post-electrolysis solution

[0078] From Table 7, it can be seen that the pH is adjusted to 12-13 to obtain a gallium hydroxide solution, and there is no loss of gallium. After electrolysis of the gallium-rich filtrate, 14.6 g of pure gallium is obtained, and the electrolysis rate is 93.00%.

[0079] In Comparative Example 1, sodium sulfide (1.25 times the molar amount of arsenic) is directly added to the gallium arsenide leaching solution to obtain an arsenic-removed solution, and the content of each element in the solution is detected, as shown in Table 8 below.

[0080] Table 8: Detection data of the arsenic-removed solution in Comparative Example 1

[0081] As can be seen from Table 8, after the gallium arsenide leaching solution is directly subjected to arsenic removal by sulfidation, the arsenic removal rate is only 12.23%, which is much lower than the 100% arsenic removal rate in Example 1, and causes a 6.4% loss of gallium.

[0082] In Comparative Example 2, sodium chloride is first used to remove fluorine, and then 3 times the molar amount of arsenic of sodium sulfide is added to remove arsenic, to obtain an arsenic-removed solution, and the content of each element in the solution is detected, as shown in Table 9 below.

[0083] Table 9: Detection data of the arsenic-removed solution in Comparative Example 2

[0084] As can be seen from Table 9, after the addition of sodium chloride, the fluorine removal rate is 97.03%, the arsenic removal rate is 13.81%, and there is no loss of gallium. After the addition of sodium sulfide for arsenic removal, the arsenic removal rate is 71.48%, the loss of gallium is 46.4%, and the removal rate of nitrate is 99.79%, and the loss rate of gallium is large.

[0085] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are only examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications of the embodiments that can be thought of by those skilled in the art, and other ways constructed by combining part of the constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A method for extracting gallium from a gallium arsenide leach solution in a hydrofluoric acid, nitric acid mixture, characterised in that, The method comprises the following steps: S1, adding a sodium salt to a gallium arsenide leaching solution, and filtering after reaction to obtain a fluorine-containing residue and a fluoride-removed filtrate; S2, adjusting the pH of the fluoride-removed filtrate to 5.0-5.5 by using liquid alkali, and filtering after stirring to obtain a gallium-containing residue; The fluorine-containing residue is subjected to acid pickling to obtain a first acid pickling solution, and the first acid pickling solution is mixed with the gallium arsenide leaching solution in step S1; S3, dissolving the gallium-containing residue by using a strong acid solution to obtain a gallium-containing solution, adding sodium sulfide to the gallium-containing solution to remove arsenic, and filtering to obtain an arsenic-containing residue and an arsenic-removed filtrate; S4, adjusting the pH of the arsenic-removed filtrate to be greater than 12 by using liquid alkali, and filtering to obtain a gallium-rich filtrate; S5, electrodepositing the gallium-rich filtrate to obtain gallium metal.

2. The method of claim 1, wherein the gallium is extracted from the gallium arsenide in hydrofluoric acid and nitric acid mixture. The molar ratio of the sodium salt to fluorine ions in the gallium arsenide leaching solution in step S1 is (2-3):1; The sodium salt includes at least one of sodium chloride, sodium carbonate, sodium sulfate, and sodium bicarbonate.

3. The method of claim 1, wherein the method of extracting gallium from a gallium arsenide leach solution in a hydrofluoric acid, nitric acid mixture is characterized by, The concentration of the sulfuric acid solution used for acid pickling in step S2 is 0.1-2 mol / L; The volume ratio of the sulfuric acid solution to the fluorine-containing residue is (2-3):

1.

4. The method of claim 1 for extracting gallium from a gallium arsenide leach in a hydrofluoric acid, nitric acid mixture, wherein The strong acid solution in step S3 includes a sulfuric acid solution; The volume ratio of the strong acid solution to the gallium-containing residue is (1-4):

1.

5. The method of claim 1, wherein the method of extracting gallium from a gallium arsenide leach in a hydrofluoric acid, nitric acid mixture is characterized by, The molar ratio of the sodium sulfide to arsenic ions in the gallium-containing solution in step S3 is (2-5):

1.

6. The method of claim 1, wherein the method of extracting gallium from a gallium arsenide leach in a hydrofluoric acid, nitric acid mixture is characterized by, The concentration of the liquid alkali in step S4 is 100-150 g / L.

7. The method of claim 1, wherein the method is characterized by, The voltage for electrodeposition in step S5 is 2-5 V.

8. The method of claim 1, wherein the method is characterized by, The arsenic-containing residue in step S3 is subjected to acid pickling to obtain a second acid pickling solution, and the second acid pickling solution is mixed with the gallium-containing solution.

9. The method of claim 1, wherein the method is characterized by, The electrolysis solution obtained after electrodeposition is mixed with the arsenic-removed filtrate.

10. The method of claim 1, wherein the method of extracting gallium from a gallium arsenide leach in a hydrofluoric acid, nitric acid mixture is characterized by, SiO3 2- 7~25g / L, F - 30~100g / L, Ca 2+ 10~60g / L, AsO4 3- 10~60g / L, NO3 - 120~350g / L, Fe 3+ <1g / L.

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