A method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leaching solution

Abstract

The invention discloses a method for neutralizing and precipitating gallium and arsenic in gallium arsenide leachate, comprising the following steps: (1) adding acid to gallium arsenide alkaline leachate to adjust pH, so that arsenic and gallium in the leachate are neutralized and precipitated, and filtering and separating after complete precipitation to obtain neutralized slag and neutralized liquid; (2) adding alkali to the neutralized slag and heating to dissolve, so as to obtain gallium arsenic enriched liquid; (3) cooling the gallium arsenic enriched liquid, standing at low temperature for cooling and crystallization, and then filtering and separating to obtain arsenic-containing crystals and gallium-rich mother liquor; (4) recovering gallium ions in the gallium-rich mother liquor by cyclone electrowinning to obtain metallic gallium. The invention adopts the neutralization precipitation process to enrich gallium and arsenic, has low cost and is easy to operate, ensures a high concentration of gallium in the electrolyte, and subsequently adopts cooling crystallization to remove arsenic, and then cyclone electrowinning, so that the concentration of gallium in the solution after arsenic removal is high, and the concentration of impurity ions such as arsenic is low, which is conducive to the subsequent electrowinning to recover metallic gallium.

Description

Technical Field

[0001] The invention belongs to the field of waste material recycling, and in particular relates to a method for recovering gallium arsenic in a gallium arsenide leaching solution. Background Art

[0002] Gallium and its compounds have excellent photoelectric and chemical properties and are widely used in high-tech fields such as semiconductor materials and solar cells. They are key raw materials for the development of emerging technology industries. Gallium is an important rare metal. The abundance of gallium in the earth's crust is extremely low, and there are no independent deposits worth mining. Therefore, gallium is mainly recovered as a by-product of the smelting process, such as Bayer process mother liquor, zinc leaching slag, etc. At present, the recovery of gallium is mainly based on primary resources, but with the increasing global demand for gallium, the recovery of gallium from secondary resources has gradually attracted people's attention. The efficient and clean recovery of gallium secondary resources can be used to alleviate the contradiction between the supply and demand of gallium metal in the future.

[0003] Gallium arsenide is one of the most widely used products of gallium. Its gallium grade is much higher than that of general gallium minerals, and it is an important raw material for secondary gallium. The production process of gallium arsenide devices has many steps and a low yield rate, including grinding and polishing. The gallium arsenide waste generated in these processes accounts for 85% of the raw materials. The gallium grade in the above-mentioned gallium arsenide waste is about 2-3%, which is a high-quality secondary resource, but its composition is relatively complex, including corundum, silicon dioxide, zirconium dioxide, cerium oxide, iron oxide, etc. contained in the abrasive. Since the waste is difficult to recycle and contains arsenic, the current conventional disposal method of enterprises is to treat it as hazardous waste and then landfill it, which leads to the waste of gallium resources and the increase of processing costs. Therefore, recycled gallium has the dual significance of resource utilization and environmental protection. It is not only conducive to alleviating the contradiction between the supply and demand of metallic gallium, but also can turn waste into treasure and solve the environmental problems caused by arsenic-containing waste.

[0004] Patent CN110938742A discloses a method for recovering sodium arsenate and metallic gallium from gallium arsenide waste residue. The method first uses an alkaline solution and an oxidant to repeatedly leach gallium arsenide to obtain a gallium arsenic enriched solution, and then cools the gallium arsenic enriched solution to crystallize and precipitate arsenic and swirl electrolysis to obtain metallic gallium. In the above method, the process steps of repeatedly leaching gallium arsenide are cumbersome; and the concentration of gallium in the enriched solution is low. Since the theoretical precipitation potential of gallium is relatively negative, there are serious concentration polarization and hydrogen evolution side reactions during the electrolysis process, resulting in low current efficiency; in addition, when cooling and crystallizing arsenic, the solution still contains arsenic, and arsenic and arsine may be produced during the electrolysis process.

[0005] Therefore, it is of great significance to develop a new process for obtaining gallium-arsenic enriched solution to increase the concentration of gallium in the enriched solution and to improve the gallium-arsenic separation efficiency in the gallium-arsenic enriched solution to facilitate the gallium electrolysis process. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology, and provide a method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leaching solution, which is beneficial to increasing the concentration of gallium in the gallium arsenic enriched solution and improving the gallium arsenic separation efficiency in the gallium arsenic enriched solution, so as to facilitate the gallium electrolysis process. In order to solve the above technical problems, the technical solution proposed by the present invention is:

[0007] A method for neutralizing, precipitating, enriching and recovering gallium and arsenic in a gallium arsenide leaching solution comprises the following steps:

[0008] (1) adding acid to the gallium arsenide alkaline leachate to adjust the pH, so that the arsenic and gallium in the leachate are neutralized and precipitated, and filtering and separating after the precipitation is complete to obtain a neutralized slag and a neutralized liquid; in this step, the gallium in the leachate is neutralized to form a colloidal precipitate, and the arsenic ions are adsorbed by the gallium hydroxide colloid and co-precipitated therewith, and filtering and separating after the precipitation is complete to obtain a neutralized slag and a neutralized liquid, and sodium sulfate in the neutralized liquid can be further recovered;

[0009] (2) adding alkali to the neutralized slag obtained in step (1) and heating to dissolve it to obtain a gallium-arsenic enriched solution (with a higher gallium-arsenic concentration);

[0010] (3) cooling the gallium-arsenic enriched solution obtained in step (2), standing at low temperature for cooling and crystallization, and then filtering and separating to obtain arsenic-containing crystals (sodium arsenate crystals) and gallium-rich mother liquor;

[0011] (4) Recovering gallium ions from the gallium-rich mother liquor obtained in step (3) by cyclonic electrolysis to obtain metallic gallium.

[0012] The main reactions in the above process are:

[0013] GaO2 - +2H2O=Ga(OH)3↓+OH - ;

[0014] Ga(OH)3+OH - =GaO2 - +2H2O;

[0015] AsO4 3- +3Na + =Na3AsO4↓;

[0016] GaO2 - +2H2O+3e - →Ga+4OH - .

[0017] In the above-mentioned method for enriching and recovering gallium and arsenic in gallium arsenide leachate by neutralization precipitation, preferably, the concentrations of gallium and arsenic in the gallium arsenide alkaline leachate (a first-stage leachate) are both 5-10 g / L. Although cyclic leaching can enrich gallium and arsenic in the solution, the leaching rate of gallium arsenide will continue to decrease, and the concentration of gallium is easy to reach saturation. The present invention uses a first-stage leachate to enrich gallium and arsenic by neutralization precipitation, which is conducive to the enrichment of gallium and arsenic. And the gallium arsenic concentration in the first-stage leachate should not be too low, because in a gallium arsenic solution with a lower concentration, due to the small amount of precipitation produced, arsenic will not form a co-precipitation due to colloidal adsorption, and the harmful arsenic-containing solution needs to be treated later, which increases the post-treatment steps, and the acid consumption of the low-concentration enrichment process is large and the efficiency is low. In a high-concentration gallium-arsenic solution, due to the large amount of precipitation produced, arsenic will form a co-precipitation with gallium due to colloidal adsorption, which can achieve high enrichment of gallium and arsenic at the same time. Arsenic and gallium can be recovered separately to obtain different products with higher purity. For example, arsenic will be enriched in the form of sodium arsenate, which can be used as a product and also achieves high enrichment of arsenic, reducing the cost of hazardous waste treatment. In addition, gallium and arsenic are highly enriched at the same time, and a relatively pure sodium sulfate product can be directly recovered from the neutralized liquid.

[0018] In the above-mentioned method for neutralizing and precipitating gallium arsenide in the gallium arsenide leachate, preferably, sulfuric acid is added during the neutralization precipitation to adjust the pH value to 3-5, the reaction temperature is controlled to 20-30°C, the stirring reaction time is 0.5-1h and then aged for 0.5-1h. Gallium is an amphoteric metal and will react as Ga and N respectively under acidic and alkaline conditions. 3+ and GaO2 - Arsenic ions exist in the form of ions, so the pH value must be strictly controlled during neutralization precipitation to achieve complete precipitation of gallium. At the same time, arsenic ions will precipitate together with gallium due to colloidal adsorption.

[0019] In the above-mentioned method for neutralizing, precipitating, enriching and recovering gallium arsenic in gallium arsenide leachate, preferably, high-concentration sodium hydroxide is added to the neutralized slag and heated to dissolve, the concentration of sodium hydroxide is controlled to be 40-120 g / L, the heating temperature is 60-90° C., and the dissolution time is 0.5-2 h. In order to avoid the generation of hydrogen arsenide gas, the selected system is an alkaline system, and in order to achieve complete dissolution of gallium hydroxide, the concentration and temperature of the alkali must be high.

[0020] In the above-mentioned method of neutralizing, precipitating, enriching and recovering gallium and arsenic in the gallium arsenide leachate, preferably, the concentrations of gallium and arsenic in the gallium arsenide enriched solution are both 30-60 g / L. If the concentration is too low, the production efficiency will be affected, while if the concentration is too high, gallium will be saturated and precipitated, thereby affecting the recovery rate of gallium.

[0021] In the above-mentioned method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leachate, preferably, the cooling crystallization temperature is controlled to be 10-20°C and the cooling crystallization time is 0.5-2h during low-temperature standing cooling crystallization. In order to achieve deep removal of arsenic, the cooling crystallization temperature should be kept low.

[0022] In the above-mentioned method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leachate, preferably, the concentration of gallium in the gallium-rich mother liquor is 30-60 g / L, the concentration of arsenic is lower than 5 g / L, and the arsenic removal rate is higher than 90%. The higher the concentration of gallium, the more conducive it is to reduce concentration polarization and improve current efficiency in the subsequent electrowinning recovery process, while too high an arsenic concentration will have an adverse effect on the purity of cathode gallium. The present invention needs to control the concentration of arsenic in the gallium-rich mother liquor.

[0023] In the above-mentioned method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leachate, preferably, the gallium-rich mother liquor is subjected to secondary arsenic removal by an arsenic precipitator before the cyclone electrowinning of step (4), the arsenic precipitator comprises barium oxide, calcium oxide, magnesium oxide and cerium oxide, the mass ratio of barium oxide, calcium oxide, magnesium oxide and cerium oxide is (3-8): (0.1-1): (0.1-1): (0.1-1), and the arsenic precipitator is first dispersed using a hot alkaline solution (sodium hydroxide solution at 30-90°C) with a pH value >14 to obtain a dispersed suspension with a mass concentration of 30-50%.

[0024] In the above-mentioned method of neutralizing, precipitating, enriching and recovering gallium and arsenic in the gallium arsenide leachate, preferably, after the secondary arsenic removal, the filtrate is filtered and collected, and then sulfate ions and / or carbonate ions (sodium sulfate and / or sodium carbonate) are added to the filtrate for impurity removal to remove excess arsenic precipitating agent.

[0025] Since the effective components of the above-mentioned arsenic precipitating agent are slightly soluble or difficult to dissolve in alkali, directly adding the arsenic precipitating agent to the gallium-rich solution may cause flocculation and agglomeration, resulting in a smaller specific surface area, thereby reducing the arsenic removal efficiency. The present invention first uses a hot alkaline solution to prepare a dispersed suspension, so that the effective components of the arsenic precipitating agent can be dispersed more evenly in the gallium-rich solution in the form of a colloidal precipitate, have a larger specific surface area, and have a better arsenic removal effect. The dispersed solution for preparing the suspension can use the post-electrolysis liquid produced by cyclone electrolysis, which can be recycled.

[0026] The present invention adds barium oxide, calcium oxide, magnesium oxide and cerium oxide to a hot alkaline solution with a pH value of more than 14 to generate a colloidal precipitate, which has a large specific surface area and has a good adsorption and removal effect on arsenic. In addition, the present invention uses a mixed alkaline arsenic precipitator to remove arsenic, and by virtue of the property that arsenic can react with calcium, magnesium, barium and cerium ions to generate arsenate precipitates with a large solubility product, it has a good selective removal effect on arsenic. Barium oxide and calcium oxide, magnesium oxide and cerium oxide are mixed and used. The microstructure of the arsenate complex salt formed by the mixed use of these four substances is more stable. Therefore, the use of a mixed arsenic precipitator to remove arsenic has a better effect than that of a single component, and can make the precipitation of arsenic more complete.

[0027] The reaction conditions for secondary arsenic removal can be: temperature of 30-90°C, mass ratio of arsenic precipitator: arsenic of (3-5): 1, stirring reaction time of 30-60min, stirring speed of 200-300r / min, aging treatment after arsenic precipitation, aging temperature of 60-80°C, aging time of 60-90min, aging stirring speed of 50-100r / min. Increasing the temperature can accelerate the precipitation reaction, but too high a temperature will increase the ion solubility product, resulting in incomplete precipitation and a decrease in precipitation rate. In order to ensure the arsenic removal rate, the amount of arsenic precipitator used needs to be higher than the theoretical amount, but the excess coefficient of the arsenic precipitator should be reduced as much as possible while ensuring the precipitation rate.

[0028] The reaction conditions when adding sulfate ions and / or carbonate ions for impurity removal can be: the mass ratio of the total amount of sodium sulfate and sodium carbonate to the excess arsenic precipitant is (1.5-2.5):1, the stirring reaction time is 10-30min, the stirring speed is 200-300r / min, the aging temperature is 20-40°C, and then the aging treatment is performed, the aging time is 10-30min, and the aging stirring speed is 50-100r / min. In order to prevent the introduction of new impurity ions into the system and ensure the purity of gallium in the subsequent recovery process, sodium sulfate and sodium carbonate need to be added as precipitants to remove excess arsenic precipitant ions.

[0029] The arsenic precipitation agent of the present invention has the advantages of good gallium-arsenic separation effect, high arsenic removal rate, less gallium loss in the process, and lower impurity ion content in the purified solution.

[0030] In the above-mentioned method for neutralizing, precipitating, enriching and recovering gallium arsenide in gallium arsenide leaching solution, preferably, the current density is controlled to be 250-750A / m during cyclonic electrowinning. 2 , the electrolytic temperature is 20-30℃, the electrolytic time is 4-12h, and the gallium recovery rate is higher than 85%. Too low current efficiency will affect production efficiency, while too high current efficiency will lead to severe concentration polarization and low current efficiency.

[0031] In the above-mentioned method for neutralizing, precipitating, enriching and recovering gallium arsenide in the gallium arsenide leachate, preferably, the post-electrolysis liquid produced by cyclone electrolysis is returned to step (2) as a leaching agent for neutralizing the slag. The sodium hydroxide used for hot alkali dissolution can use the post-electrolysis liquid produced by step (4) as a leaching agent in the continuous production process. Hydroxide will be continuously produced during the electrolysis process to maintain the alkali concentration, so it can be returned to the hot alkali dissolution process to achieve recycling.

[0032] Since the theoretical precipitation potential of gallium is relatively negative, there are serious concentration polarization and hydrogen evolution side reactions during the electrolysis process, resulting in low current efficiency. Increasing the gallium concentration in the electrolyte is conducive to improving the theoretical precipitation potential of gallium and alleviating concentration polarization, thereby improving the current efficiency. The presence of arsenic will also affect the electrolysis process of gallium. Therefore, minimizing the concentration of arsenic in the electrolyte is also conducive to the electrolysis process of gallium. However, it is difficult to achieve high enrichment of gallium and efficient separation of arsenic. The present invention uses a neutralization precipitation method to enrich gallium arsenic. The concentration of gallium arsenic in a first leaching solution is relatively high. Gallium is neutralized to form a colloidal precipitate. Arsenic ions will be adsorbed by gallium hydroxide colloid and co-precipitated with it. After the precipitation is complete, it is filtered and separated to obtain a neutralized slag, which can achieve high enrichment of gallium arsenic. After the gallium arsenic enriched solution is cooled and crystallized to remove arsenic, the gallium concentration in the gallium-rich mother liquor is high and the arsenic concentration is low, but a certain amount of arsenic will still exist. After the gallium-rich mother liquor of the present invention is subjected to secondary arsenic removal by an arsenic precipitator, the arsenic concentration in the gallium-rich mother liquor is lower, which is more conducive to the cyclone electrolysis process of gallium.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] 1. The method for enriching and recovering gallium and arsenic in gallium arsenide leachate by neutralization precipitation of the present invention adopts a neutralization precipitation process to enrich gallium and arsenic, has low cost and is easy to operate, ensures a high concentration of gallium in the electrolyte, and can realize the recycling of alkali, avoiding the large-scale use of alkali and the treatment of high-alkali wastewater.

[0035] 2. The neutralization precipitation enrichment and recovery method of gallium and arsenic in the gallium arsenide leachate of the present invention adopts cooling crystallization to remove arsenic, and then cyclone electrowinning. After the arsenic removal, the concentration of gallium in the solution is high, and the concentration of impurity ions such as arsenic is low, which is conducive to the subsequent electrowinning recovery of metallic gallium. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0037] Figure 1The present invention is a process flow chart of the method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leaching solution.

[0038] Figure 2 These are photos of the solutions after the neutralization precipitate was allowed to settle under different pH conditions in Example 1.

[0039] Figure 3 This is the SME-EDS image after neutralization, precipitation and washing in Example 1. DETAILED DESCRIPTION

[0040] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0041] Unless otherwise defined, all the professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0042] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0043] The gallium arsenide alkaline leaching solution used in the following examples has a gallium concentration of 7.95 g / L, an arsenic concentration of 8.13 g / L, a pH of 14, and concentrations of other impurity ions are all lower than 50 ppm.

[0044] Embodiment 1:

[0045] like Figure 1 As shown, a method for neutralizing, precipitating, enriching and recovering gallium and arsenic in a gallium arsenide leaching solution comprises the following steps:

[0046] (1) Neutralization precipitation: sulfuric acid was added to the gallium arsenide alkaline leaching solution to adjust the pH to 4, and the precipitation reaction was carried out at 25°C and a stirring speed of 250 rpm for 1 hour. After the reaction was completed, it was allowed to stand for 0.5 hour without stirring, and then filtered to separate the neutralized slag and the neutralized liquid. The precipitation rates of gallium and arsenic could reach 99.91% and 99.05%, respectively.

[0047] (2) Hot alkali dissolution: Take 130 g of the neutralized slag obtained in step (1), add 1 L of 80 g / L sodium hydroxide solution (which can be the post-electrolysis solution in step (4)), and react at 70°C for 1 h until the precipitate is completely dissolved to obtain a high-concentration gallium-arsenic enriched solution, in which the gallium concentration is 39.45 g / L and the arsenic concentration is 41.46 g / L.

[0048] (3) Cooling crystallization: The high-concentration gallium-arsenic-enriched solution obtained in step (2) was cooled at 20° C. for 1 h, and then filtered to separate the crystallized sodium arsenate crystals and the gallium-rich mother liquor, wherein the gallium concentration was 38.94 g / L and the arsenic concentration was 3.58 g / L.

[0049] (4) Electrolytic recovery of gallium: The gallium-rich mother liquor obtained in step (3) is electrolytically recovered to recover gallium ions therein at a temperature of 25° C. and a current density of 500 A / m 2 Under the conditions of , the electrolysis was carried out for 8 hours, the current efficiency was 26.5%, the gallium recovery rate was 91.2%, the gallium concentration in the solution after electrolysis was 3.43 g / L, and the purity of the prepared metallic gallium was 99.95%.

[0050] In this example, by changing the pH value in step (1), the results are as follows Figure 2 As shown in Figure 1, gallium is an amphoteric metal and is soluble in both acid and alkali. Figure 2 It can be seen that when the neutralization pH is high (pH>6), the solution is basically clear and the precipitation rate is low. At this time, gallium is in the form of GaO2 - It exists in ionic form; when the pH is 3-5, a large amount of precipitation appears; when the pH is 2, the solution becomes clear again, and gallium is in the form of Ga 3+ Exists in ionic form.

[0051] The SME-EDS diagram of the neutralized slag in this embodiment is as follows: Figure 3 As shown, Figure 3 (a) is the spectrum before neutralization slag washing, (b) is the spectrum after neutralization slag washing with water. It can be seen from the figure that the sodium content of the two is quite different, indicating that some adsorbed sodium sulfate was washed away during the washing process, but the content of gallium and arsenic remained basically unchanged, indicating that the adsorbed co-precipitated arsenic cannot be removed by washing, and the content of gallium and arsenic in the precipitate is basically the same, indicating that the two have co-precipitated, and the neutralization method cannot be used to achieve direct separation, but the high enrichment of the two can be achieved.

[0052] Embodiment 2:

[0053] like Figure 1 As shown, a method for neutralizing, precipitating, enriching and recovering gallium and arsenic in a gallium arsenide leaching solution comprises the following steps:

[0054] (1) Neutralization precipitation: sulfuric acid was added to the gallium arsenide alkaline leaching solution to adjust the pH to 5. The precipitation reaction was carried out at 25°C and a stirring speed of 250 rpm for 1 hour. After the reaction was completed, it was allowed to stand for 0.5 hour without stirring. The neutralized slag and the neutralized liquid were then separated by filtration. The precipitation rates of gallium and arsenic were 96.41% and 95.68%, respectively.

[0055] (2) Hot alkali dissolution: Take 200 g of the neutralized slag obtained in step (1), add 1 L of 80 g / L sodium hydroxide solution thereto, and react at 80°C for 1 h until the precipitate is completely dissolved to obtain a high-concentration gallium-arsenic enriched solution, in which the gallium concentration is 59.79 g / L and the arsenic concentration is 57.43 g / L.

[0056] (3) Cooling crystallization: The high-concentration gallium-arsenic-enriched solution obtained in step (2) was cooled at 10° C. for 1 h, and then filtered to separate the crystallized sodium arsenate crystals and the gallium-rich mother liquor, wherein the gallium concentration was 58.46 g / L and the arsenic concentration was 5.57 g / L.

[0057] (4) Electrolytic recovery of gallium: The gallium-rich mother liquor obtained in step (3) is electrolytically recovered to recover gallium ions therein at a temperature of 25° C. and a current density of 500 A / m 2 Under the conditions of , the electrolysis was carried out for 8 hours, the current efficiency was 29.2%, the gallium recovery rate was 87.2%, the gallium concentration in the solution after electrolysis was 7.48 g / L, and the purity of the prepared metallic gallium was 99.97%.

[0058] Embodiment 3:

[0059] A method for neutralizing, precipitating, enriching and recovering gallium and arsenic in a gallium arsenide leaching solution comprises the following steps:

[0060] (1) Neutralization precipitation: sulfuric acid was added to the gallium arsenide alkaline leaching solution to adjust the pH to 5. The precipitation reaction was carried out at 25°C and a stirring speed of 250 rpm for 1 hour. After the reaction was completed, it was allowed to stand for 0.5 hour without stirring. The neutralized slag and the neutralized liquid were then separated by filtration. The precipitation rates of gallium and arsenic were 96.19% and 95.24%, respectively.

[0061] (2) Hot alkali dissolution: Take 200 g of the neutralized slag obtained in step (1), add 1 L of 80 g / L sodium hydroxide solution thereto, and react at 80°C for 1 h until the precipitate is completely dissolved to obtain a high-concentration gallium-arsenic enriched solution, in which the gallium concentration is 59.28 g / L and the arsenic concentration is 56.59 g / L.

[0062] (3) Cooling crystallization: The high-concentration gallium-arsenic-enriched solution obtained in step (2) was cooled at 10° C. for 1 h, and then filtered to separate the crystallized sodium arsenate crystals and the gallium-rich mother liquor, wherein the gallium concentration was 58.94 g / L and the arsenic concentration was 5.22 g / L.

[0063] (4) Secondary arsenic removal: add an arsenic precipitator to the gallium-rich mother liquor obtained in step (3) for deep arsenic removal, wherein the arsenic precipitator comprises barium oxide, calcium oxide, magnesium oxide and cerium oxide, wherein the mass ratio of barium oxide, calcium oxide, magnesium oxide and cerium oxide is 6:1:1:1, and the arsenic precipitator is first dispersed by a hot sodium hydroxide solution with a pH value of >14 to obtain a dispersed suspension with a mass concentration of 50%, and then added to the gallium-rich mother liquor at a temperature of 50°C and a mass ratio of the arsenic precipitator to arsenic of 5:1, stirred for 40 minutes, and the stirring speed is controlled to be 250 r / min, and then aged, wherein the aging temperature is controlled to be 70°C, the aging time is controlled to be 60 minutes, and the aging stirring speed is controlled to be 50 r / min. After aging, the arsenic residue and the primary gallium liquid are separated by filtration. In this step, the arsenic removal rate is 99.18%, the gallium loss rate is 10.26%, the gallium concentration in the primary gallium liquid is 52.46 g / L, and the arsenic concentration is 0.05 g / L.

[0064] (5) Precipitation and impurity removal: Sodium sulfate and sodium carbonate are added to the primary gallium liquid for stirring reaction, and the mass ratio of the total amount of sodium sulfate and sodium carbonate to the excess arsenic precipitant is controlled to be 2:1, and the stirring reaction time is controlled to be 30 minutes, and the stirring speed is 200r / min. After the stirring reaction, aging treatment is carried out, and the aging temperature is controlled to be 20°C, the aging time is 30 minutes, and the aging stirring speed is 50r / min. After aging, filtration and separation are performed to obtain sulfate precipitate and secondary gallium liquid. In this step, the removal rate of impurity ions can reach 98.59%, and the concentration of gallium ions does not change significantly.

[0065] (6) Electrolytic recovery of gallium: The gallium ions in the secondary gallium solution after impurity removal in step (5) are recovered by electrolytic recovery at a temperature of 25° C. and a current density of 500 A / m 2 Under the conditions of , the electrolysis was carried out for 8 hours, the current efficiency was 35.9%, the gallium recovery rate was 91.03%, the gallium concentration in the solution after electrolysis was 4.71 g / L, and the purity of the prepared metallic gallium was 99.993%.

Claims

1. A method for neutralizing, precipitating, enriching and recovering gallium and arsenic in gallium arsenide leachate, characterized in that: The following steps are involved: (1) adding acid to the gallium arsenide alkaline leaching solution to adjust the pH, so that the arsenic and gallium in the leaching solution are neutralized and precipitated, and after the precipitation is complete, filtering and separating to obtain the neutralized slag and the neutralized liquid; (2) adding alkali to the neutralized slag obtained in step (1) and heating to dissolve it to obtain a gallium-arsenic enriched solution; (3) cooling the gallium-arsenic enriched solution obtained in step (2), standing at low temperature for cooling and crystallization, and then filtering and separating to obtain arsenic-containing crystals and gallium-rich mother liquor; (4) recovering gallium ions from the gallium-rich mother liquor obtained in step (3) by cyclonic electrowinning to obtain metallic gallium; The gallium-rich mother liquor is subjected to secondary arsenic removal by an arsenic precipitator and then subjected to the cyclone electrowinning of step (4). The arsenic precipitator comprises barium oxide, calcium oxide, magnesium oxide and cerium oxide, and the mass ratio of barium oxide, calcium oxide, magnesium oxide and cerium oxide is (3-8): (0.1-1): (0.1-1): (0.1-1), and the arsenic precipitator is first dispersed using a hot alkaline solution with a pH value greater than 14 to obtain a dispersed suspension with a mass concentration of 30-50%.

2. The method for neutralization precipitation enrichment and recovery of gallium arsenic in gallium arsenide leachate according to claim 1, characterized in that: The concentrations of gallium and arsenic in the gallium arsenide alkaline leaching solution are both 5-10 g / L.

3. The method for neutralization precipitation enrichment and recovery of gallium arsenic in gallium arsenide leachate according to claim 1, characterized in that: When neutralizing the precipitate, sulfuric acid is added to adjust the pH value to 3-5, the reaction temperature is controlled to 20-30°C, the stirring reaction time is 0.5-1h and then aged for 0.5-1h.

4. The method for neutralization precipitation enrichment and recovery of gallium and arsenic in gallium arsenide leachate according to claim 1, characterized in that: Add high concentration sodium hydroxide to the neutralized slag and heat to dissolve, control the concentration of sodium hydroxide to 40-120g / L, the heating temperature to 60-90°C, and the dissolution time to 0.5-2h.

5. The method for neutralization precipitation enrichment and recovery of gallium and arsenic in gallium arsenide leachate according to claim 1, characterized in that: The concentrations of gallium and arsenic in the gallium-arsenic enriched solution are both 30-60 g / L.

6. The method for neutralization precipitation enrichment and recovery of gallium and arsenic in gallium arsenide leachate according to any one of claims 1 to 5, characterized in that: During low temperature standing cooling crystallization, the cooling crystallization temperature is controlled to be 10-20°C, and the cooling crystallization time is 0.5-2h.

7. The method for neutralization precipitation enrichment and recovery of gallium and arsenic in gallium arsenide leachate according to any one of claims 1 to 5, characterized in that: The gallium concentration in the gallium-rich mother liquor is 30-60 g / L, the arsenic concentration is lower than 5 g / L, and the arsenic removal rate is higher than 90%.

8. The method for neutralization precipitation enrichment and recovery of gallium and arsenic in gallium arsenide leachate according to claim 1, characterized in that: After the secondary arsenic removal, the filtrate is collected by filtration, and then sulfate ions and / or carbonate ions are added to the filtrate for impurity removal to remove excess arsenic precipitating agent.

9. The method for neutralization precipitation enrichment and recovery of gallium and arsenic in gallium arsenide leachate according to any one of claims 1 to 5, characterized in that: The current density is controlled to be 250-750A / m during cyclonic electrowinning. 2 , the electrolysis temperature is 20-30℃, the electrolysis time is 4-12h, and the gallium recovery rate is higher than 85%.

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