A method for separately recovering gallium-lutetium from gallium-lutetium garnet waste

Abstract

This application belongs to the field of renewable resource recycling technology, and particularly relates to a method for separately recovering gallium and lutetium from gallium-lutetium garnet waste. The method provided by this application separates gallium and lutetium into a water leaching solution and a water leaching residue after alkaline melting. Subsequently, the water leaching solution is subjected to silicon and aluminum removal to precipitate gallium hydroxide. The water leaching residue is then acid-leached, and the acid leaching solution is extracted to remove iron, purified by extraction, and back-extracted. An excess of oxalic acid is added to ensure that lutetium is fully precipitated in the lutetium-rich back-extraction solution after back-extraction. The lutetium oxalate precipitate is then calcined to obtain lutetium oxide, thereby realizing the separate recovery of gallium and lutetium from gallium-lutetium garnet waste and solving the technical problem of the lack of a method for separately recovering gallium and lutetium from gallium-lutetium garnet in the prior art.

Description

Technical Field

[0001] This application belongs to the field of renewable resource recycling technology, and in particular relates to a method for separately recovering gallium lutetium from gallium lutetium garnet waste. Background Technology

[0002] Among rare earth elements, lutetium compounds have excellent properties and wide applications. For example, lutetium oxide is a white powder with a high melting point, stability, and excellent optical and electrical properties. It is widely used in the fields of yttrium aluminum gallium garnet additives, phosphors, high-performance alloys, catalysts, and magnetic materials. Gallium compounds are also important semiconductor materials and are widely used in the manufacture of infrared optics and infrared detectors, integrated circuits, light-emitting diodes, and other optoelectronic devices. However, the abundance of lutetium and gallium in the earth's crust is not high, and there is a need to develop methods for the recovery of lutetium and gallium resources.

[0003] Gallium-lutetium garnet waste contains 6-15% lutetium, 5-20% gallium, and 10-20% aluminum. Its high gallium-lutetium content gives it significant recycling value. However, gallium-lutetium garnet has a stable silicate structure, requiring disruption of this structure for lutetium recycling. Currently, the main recycling methods for lutetium-containing garnet waste are: alkali fusion-hydrochloric acid leaching-evaporation crystallization-alkali precipitation of aluminum and silicon-extraction separation-lutetium oxalate precipitation-calcination to obtain high-purity lutetium oxide; or alkali fusion-water leaching-lutetium leaching with a combination of 5-10N nitric acid and an oxidant-extraction impurity removal-lutetium oxalate precipitation-calcination to obtain high-purity lutetium oxide. These two methods offer high lutetium recovery rates and good impurity separation, and are widely used in the recycling of lutetium-containing garnet waste. However, methods for separately recovering gallium and lutetium from gallium-lutetium garnet are currently lacking. Summary of the Invention

[0004] In view of this, this application provides a method for separately recovering gallium and lutetium from gallium-lutetium garnet waste, which solves the technical problem of the lack of a method for separately recovering gallium and lutetium from gallium-lutetium garnet in the prior art.

[0005] The first aspect of this application provides a method for separately recovering gallium lutetium from gallium lutetium garnet waste, the method comprising the steps of:

[0006] Step S1: The gallium lutetium garnet waste is crushed, alkali fused, water leached, and washed with pure water in sequence, and filtered to obtain water leaching solution and water leaching residue;

[0007] Step S2: Add calcium hydroxide to the aqueous leaching solution to carry out the silicon-aluminum removal reaction, and filter to obtain a gallium-rich solution;

[0008] Step S3: Add pH adjuster to gallium-rich solution to lower pH and carry out precipitation reaction, then filter to obtain gallium hydroxide precipitate;

[0009] Step S4: The water-leached residue is subjected to acid leaching and pure water washing in sequence to obtain acid-leached residue and acid leaching solution;

[0010] Step S5: The acid leaching solution is subjected to extraction to remove iron, extraction to purify, and back-extracted in sequence to obtain lutetium-rich back-extracted solution;

[0011] Step S6: Add oxalic acid to the lutetium-rich back-extraction solution to carry out a precipitation reaction, and filter to obtain lutetium oxalate;

[0012] Step S7: Calcining lutetium oxalate yields lutetium oxide.

[0013] Preferably, in step S1, the crushing process is: grinding until the particle size of the gallium lutetium garnet waste is no greater than 200 mesh;

[0014] The alkali fusion process is as follows: gallium lutetium garnet waste and caustic soda flakes with a mass ratio of 1:1~3 are placed in a muffle furnace at 600~800℃ and calcined for 2~4 hours.

[0015] Preferably, in step S1, the water leaching process is as follows: the alkaline-fused gallium lutetium garnet material and water are leached at a temperature of 70-100°C for 0.5-2 hours in a mass ratio of 1:3-5, and the leaching residue and the first water leaching solution are obtained by filtration.

[0016] The pure water washing process is as follows: the water-leached residue is washed with pure water at least once, and then filtered to obtain the washed water-leached residue and the second water-leached liquid.

[0017] Preferably, in step S2, during the silicon-aluminum removal reaction, the molar amount of calcium in the added calcium hydroxide is at least twice the sum of the molar amounts of aluminum and silicon in the gallium lutetium garnet waste.

[0018] Preferably, in step S2, the temperature of the silicon-aluminum removal reaction is 60~90℃ and the time is 0.5~2h.

[0019] Preferably, in step S3, the pH value of the precipitation reaction is 6-8, the temperature is room temperature, and the time is 0.5-2h.

[0020] Preferably, in step S4, the acid reagent used for acid leaching is 3.0~4.0 mol / L hydrochloric acid, the temperature is 70~100℃, and the time is 0.5~2h.

[0021] Preferably, in step S4, the pure water washing is performed at least once.

[0022] Preferably, in step S5, the extractant used for iron removal is selected from amine extractants, alcohols, and kerosene-based extractants.

[0023] The extraction and purification agent used is selected from P507 extractant, C272 extractant and kerosene compounded extractant.

[0024] The back-extraction agent used in the back-extraction is selected from hydrochloric acid.

[0025] Preferably, in step S5, the extractant comprises: 5-15% amine extractant, 10-30% alcohol, and 55-85% kerosene;

[0026] The purification extractant includes: 15-25% P507 extractant, 15-25% C272 extractant and 50-70% kerosene;

[0027] The concentration of the hydrochloric acid is 3~6 mol / L.

[0028] Preferably, in step S5, the extraction is performed at least once, the back-extraction is performed at least once, and the back-extraction is performed at least once.

[0029] Preferably, in step S6, the molar amount of oxalic acid used is at least 1.5 times the molar amount of lutetium in the gallium-lutetium garnet waste.

[0030] Preferably, in step S6, the precipitation reaction is carried out at a temperature of 30-50°C for 2-4 hours.

[0031] Preferably, in step S7, the calcination temperature of the oxalic acid is 800~900℃ and the time is 2~4h. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 This is a schematic flowchart illustrating a method for separately recovering gallium lutetium from gallium lutetium garnet waste, as provided in this application. Detailed Implementation

[0034] This application provides a method for separately recovering gallium and lutetium from gallium-lutetium garnet waste, which solves the technical problem that there is no method in the prior art for separately recovering gallium and lutetium from gallium-lutetium garnet.

[0035] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this application. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] Given that current research mainly focuses on the recovery of lutetium from lutetium-containing garnet waste, and lacks research on the recovery of gallium and lutetium from gallium-lutetium garnet waste, this application provides a method for separately recovering gallium and lutetium from gallium-lutetium garnet waste. The method includes: firstly, sequentially crushing, alkali melting, water leaching, and pure water washing of the gallium-lutetium garnet waste, and filtering to obtain a water leaching solution and a water leaching residue; then, adding calcium hydroxide to the water leaching solution to carry out a silicon-aluminum removal reaction and filtering to obtain a gallium-rich solution; subsequently, adding a pH adjuster to the gallium-rich solution to lower the pH to carry out a precipitation reaction and filtering to obtain gallium hydroxide precipitate; then, sequentially acid leaching, pure water washing, and filtering to obtain acid leaching residue and an acid leaching solution; next, sequentially extracting to remove iron, extracting to purify, and back-extracting to obtain a lutetium-rich back-extracting solution; finally, adding oxalic acid to the lutetium-rich back-extracting solution to react and calcining the obtained lutetium oxalate to obtain lutetium oxide.

[0037] The method for separately recovering gallium and lutetium from gallium-lutetium garnet waste provided in this application involves water leaching after alkali fusion to obtain leaching residue and leaching solution. During water leaching, gallium is easily leached out, while lutetium is difficult to leach, thus achieving gallium-lutetium separation. This avoids the defect of traditional hydrochloric acid leaching, which easily leads to the simultaneous leaching of gallium and lutetium, making separation difficult. After water leaching, the leaching residue is washed with pure water to flush residual gallium into the leaching solution. Subsequently, the leaching solution is treated with calcium hydroxide. The leaching solution after alkali fusion is a strong pH solution with a pH of 12-14. Aluminum mainly exists in the form of sodium aluminate, silicon mainly exists in the form of sodium silicate, and gallium mainly exists in the form of Ga(OH). 4- In the form of gallium, calcium hydroxide is added to the water leaching solution, and the calcium hydroxide reacts with sodium aluminate to form aluminum hydroxide precipitate and calcium aluminate. Sodium silicate reacts with calcium hydroxide to form calcium silicate precipitate. Gallium is difficult to participate in the reaction under strongly alkaline conditions, thus achieving the purpose of removing silicon and aluminum impurities and obtaining a gallium-rich solution. Subsequently, a pH adjuster is added to the gallium-rich solution to lower the pH and obtain gallium hydroxide precipitate. Next, the water leaching residue is acid-leached to leach lutetium from the water leaching residue to obtain acid leaching residue and acid leaching solution. After the acid leaching solution is subjected to impurity removal, purification and back-extraction, oxalic acid is added to react and lutetium oxalate precipitate is obtained. Subsequently, calcination yields lutetium oxide. Thus, the method provided in this application successfully recovers gallium and lutetium from gallium-lutetium garnet waste, realizing the resource utilization of gallium and lutetium and overcoming the deficiency of lack of research on gallium and lutetium recovery.

[0038] As a preferred technical solution, in order to effectively destroy the silicate structure of gallium lutetium garnet and improve the alkali melting effect, this application pre-treats the gallium lutetium garnet waste by crushing it to 200 mesh (approximately 74 μm), so that the gallium lutetium garnet waste can fully react with caustic soda (sodium hydroxide) during the alkali melting process; and controls the amount of raw materials, temperature and time during the alkali melting process, controlling the mass ratio of gallium lutetium garnet waste to caustic soda to be 1:3~5, the alkali melting temperature to be 600~800℃, and the time to be 2~4h.

[0039] As a preferred technical solution, in order to effectively promote the separation of gallium and lutetium during the water immersion process and improve the recovery effect of gallium and lutetium, this application controls the amount of water immersion solution, the water immersion temperature and time, the mass ratio of gallium and lutetium garnet material after alkali melting to water is 1:3~5, the water immersion temperature is 70~100℃, and the time is 0.5~2h; at the same time, pure water is used to wash the water immersion residue at least once to reduce the gallium residue in the water immersion residue.

[0040] As a preferred technical solution, in order to remove aluminum and silicon from gallium lutetium garnet waste as thoroughly as possible and improve the gallium recovery efficiency, this application controls the amount of calcium hydroxide added and the reaction temperature and time during the aluminum-silicon removal reaction. The molar amount of calcium is controlled to be at least twice the sum of the molar amounts of aluminum and silicon in the gallium lutetium garnet waste, the reaction temperature is 60~90℃, and the time is 0.5~2h.

[0041] As a preferred technical solution, in order to increase the amount of gallium recovered from gallium-lutetium garnet waste, this application controls the pH value of the precipitation reaction by adding an acid regulator. The pH value should be near neutral, with a pH of 6 to 8.

[0042] As a preferred technical solution, in order to thoroughly remove impurities such as iron from gallium-lutetium garnet waste and improve the efficiency of lutetium recovery, this application controls the solvents used in the extraction, purification, and back-extraction processes. The extractant used for iron removal is selected from amine extractants, extractants obtained by combining alcohols and kerosene; the purification extractant is selected from P507 extractant, C272 extractant, and kerosene; and the back-extraction agent used is selected from hydrochloric acid.

[0043] As a preferred technical solution, in order to increase the recovery of lutetium in gallium-lutetium garnet waste, this application controls the amount of oxalic acid added, and controls the molar amount of oxalic acid to be at least 1.5 times the molar amount of lutetium in gallium-lutetium garnet waste.

[0044] The following will provide a detailed description of a method for separately recovering gallium lutetium from gallium lutetium garnet waste, based on embodiments and gallium lutetium recovery data.

[0045] Example 1

[0046] Example 1 of this application provides a method for recovering gallium lutetium from gallium lutetium garnet waste. The method includes the following steps: alkali fusion and water leaching, water leaching solution for removing silicon and aluminum reaction, generating gallium hydroxide precipitate, acid leaching, acid leaching solution for purification and back-extraction, generating lutetium oxalate, and calcination.

[0047] The steps of alkali fusion and water leaching include: first, weighing 120g of gallium-lutetium garnet waste and grinding it through a 200-mesh sieve in a mortar; then, mixing 100g of gallium-lutetium garnet fine powder with 200g of caustic soda flakes, placing it in a nickel crucible, and calcining it in a muffle furnace at 600℃ for 3 hours; next, leaching 300g of the naturally cooled material with 1200mL of pure water at a liquid-to-solid ratio of 4:1 at 85℃ for 1 hour, filtering to obtain water-leached residue and a first water-leached solution; washing the water-leached residue with 500mL of pure water, filtering to obtain a second water-leached residue and a second water-leached solution. The water leaching solution and the second water leaching solution were mixed to form the water leaching solution. ICP spectroscopy analysis showed that the gallium-lutetium garnet waste used in this embodiment contained: 14.63% gallium, 6.70% lutetium, 0.53% iron, 15.61% aluminum, and 0.5% silicon. The water leaching solution contained: 13.65g gallium (93.34%), 0.001g lutetium (<0.02%), 0.0001g iron (<0.02%), 13.31g aluminum (85.31%), and 0.04g silicon (8.26%).

[0048] The steps of the water leaching reaction to remove silicon and aluminum include: adding 103.5g of calcium hydroxide solid to the water leaching solution mixed with the first and second water leaching solutions, reacting at 75°C for 1 hour to fully remove aluminum and silicon, and filtering to obtain calcium-aluminum-silicon slag and gallium-rich solution.

[0049] The steps for generating gallium hydroxide precipitate include: adding concentrated sulfuric acid to a gallium-rich solution to adjust the pH to 7.5, reacting for 1 hour, filtering and washing to obtain gallium hydroxide.

[0050] The acid leaching process includes: leaching hydrochloric acid (concentration 3.5 mol / L) and water leaching residue at a liquid-solid ratio of 4:1 at 85℃ for 1 hour, filtering and washing to obtain acid leaching residue and acid leaching solution. ICP spectroscopy analysis showed that the acid leaching solution contained: 0.033 g gallium (0.23%), 6.43 g lutetium (95.97%), 0.40 g iron (75.31%), 0.026 g aluminum (0.17%), and 0.0001 g silicon (0.03%).

[0051] The steps for removing impurities, purifying, and back-extracting the acid leaching solution include: first, mixing the extractant and acid leaching solution at an O / A ratio of 1:5 for 10 min and extracting to obtain iron extraction residue and a loaded organic phase, with the iron content in the iron extraction residue being less than 1 mg / L; then, mixing the purification extractant and iron extraction residue at an O / A ratio of 15:1 for 10 min and extracting to obtain lutetium extraction residue and a lutetium-rich organic phase, with the lutetium content in the lutetium extraction residue being less than 10 mg / L; finally, mixing the back-extractant and the lutetium-rich organic phase at an O / A ratio of 11:1 for 10 min. Extraction was performed at min to obtain lutetium back-extraction solution and organic phase, in which the lutetium content was less than 0.2 mg / L. The extractant used was a compound of 10% amine extractant N235, 20% 2-octanol and 70% kerosene, while the purified extractant was a compound of 20% P507 extractant, 20% C272 extractant and 60% kerosene. The back-extraction agent was hydrochloric acid (4.5 mol / L).

[0052] The steps for generating lutetium oxalate include: adding excess oxalic acid (concentration of 77 g / L) to the lutetium back-extraction solution, reacting at 40°C for 3 h to generate lutetium oxalate precipitate, filtering and washing to obtain lutetium oxalate. The amount of oxalic acid used is calculated based on the molar amount of lutetium in the oxalic acid / gallium-lutetium garnet waste being 1.7 / 1.

[0053] The calcination process includes: placing lutetium oxalate into a ceramic crucible and calcining it at 850°C for 3 hours to obtain lutetium oxide.

[0054] Example 2

[0055] Example 2 of this application provides a method for recovering gallium lutetium from gallium lutetium garnet waste. The method includes the following steps: alkali fusion and water leaching, water leaching solution for removing silicon and aluminum reaction, generation of gallium hydroxide precipitate, acid leaching, acid leaching solution for purification and back-extraction, generation of lutetium oxalate, and calcination. The difference from Example 1 is that gallium lutetium garnet waste is replaced.

[0056] The steps of alkali fusion and water leaching include: first, weighing 120g of gallium-lutetium garnet waste and grinding it through a 200-mesh sieve in a mortar; then, mixing 100g of gallium-lutetium garnet fine powder with 200g of caustic soda flakes, placing it in a nickel crucible, and calcining it in a muffle furnace at 600℃ for 3 hours; next, leaching 300g of the naturally cooled material with 1200mL of pure water at a liquid-to-solid ratio of 4:1 at 85℃ for 1 hour, filtering to obtain water-leached residue and a first water-leached solution; washing the water-leached residue with 500mL of pure water, filtering to obtain a second water-leached residue and a second water-leached solution. The water leaching solution and the second water leaching solution were mixed to form the water leaching solution. ICP spectroscopy analysis showed that the gallium-lutetium garnet waste used in this embodiment contained: 10.65% gallium, 7.68% lutetium, 1.37% iron, 21.11% aluminum and 0.2% silicon. The water leaching solution contained: 10.05g gallium (94.38%), 0.001g lutetium (<0.02%), 0.0002g iron (<0.02%), 18.73g aluminum (88.73%) and 0.01g silicon (5.17%).

[0057] The steps of the water leaching reaction to remove silicon and aluminum include: adding 136.9g of calcium hydroxide solid to the water leaching solution mixed with the first and second water leaching solutions, reacting at 75°C for 1 hour to fully remove aluminum and silicon, and filtering to obtain calcium-aluminum-silicon slag and gallium-rich solution.

[0058] The steps for generating gallium hydroxide precipitate include: adding concentrated sulfuric acid to a gallium-rich solution to adjust the pH to 7.5, reacting for 1 hour, filtering and washing to obtain gallium hydroxide.

[0059] The acid leaching process includes: leaching hydrochloric acid (concentration 3.5 mol / L) and water leaching residue at a liquid-to-solid ratio of 4:1 at 85℃ for 1 hour, filtering and washing to obtain acid leaching residue and acid leaching solution. ICP spectroscopy analysis showed that the acid leaching solution contained: 0.015 g gallium (0.14%), 7.32 g lutetium (95.28%), 1.06 g iron (77.29%), 0.025 g aluminum (0.12%), and 0.00004 g silicon (0.02%).

[0060] The steps for removing impurities, purifying, and back-extracting the acid leaching solution include: first, mixing the extractant and acid leaching solution at an O / A ratio of 1:5 for 10 min and extracting to obtain iron extraction residue and a loaded organic phase, with the iron content in the iron extraction residue being less than 1 mg / L; then, mixing the purification extractant and iron extraction residue at an O / A ratio of 15:1 for 10 min and extracting to obtain lutetium extraction residue and a lutetium-rich organic phase, with the lutetium content in the lutetium extraction residue being less than 10 mg / L; finally, mixing the back-extractant and the lutetium-rich organic phase at an O / A ratio of 11:1 for 10 min. Extraction was performed at min to obtain lutetium back-extraction solution and organic phase, in which the lutetium content was less than 0.2 mg / L; the extractant used was a compound of 10% amine extractant N235, 20% 2-octanol and 70% kerosene, while the purified extractant used was a compound of 20% P507 extractant, 20% C272 extractant and 60% kerosene, and the back-extraction agent was hydrochloric acid (4.5 mol / L).

[0061] The steps for generating lutetium oxalate include: adding excess oxalic acid (concentration of 77 g / L) to the lutetium back-extraction solution, reacting at 40°C for 3 h to generate lutetium oxalate precipitate, filtering and washing to obtain lutetium oxalate. The amount of oxalic acid used is calculated based on the molar amount of lutetium in the oxalic acid / gallium-lutetium garnet waste being 1.7 / 1.

[0062] The calcination process includes: placing lutetium oxalate into a ceramic crucible and calcining it at 850°C for 3 hours to obtain lutetium oxide.

[0063] Example 3

[0064] Example 3 of this application provides a method for recovering gallium lutetium from gallium lutetium garnet waste. The method includes: alkali melting and water leaching steps, water leaching solution for removing silicon and aluminum reaction, generating gallium hydroxide precipitate, acid leaching step, acid leaching solution for purification and back-extraction, generating lutetium oxalate step, and calcination step. The difference from Example 1 is that the amount of calcium hydroxide added is increased.

[0065] The steps of alkali fusion and water leaching include: first, weighing 120g of gallium-lutetium garnet waste and grinding it through a 200-mesh sieve in a mortar; then, mixing 100g of gallium-lutetium garnet fine powder with 200g of caustic soda flakes, placing it in a nickel crucible, and calcining it in a muffle furnace at 800℃ for 3 hours; next, leaching 300g of the naturally cooled material with 1200mL of pure water at a liquid-to-solid ratio of 4:1 at 85℃ for 1 hour, filtering to obtain water-leached residue and a first water-leached solution; washing the water-leached residue with 500mL of pure water, filtering to obtain a second water-leached residue and a second water-leached solution. The water leaching solution and the second water leaching solution were mixed to form the water leaching solution. ICP spectroscopy analysis showed that the gallium-lutetium garnet waste used in this embodiment contained: 14.63% gallium, 6.70% lutetium, 0.53% iron, 15.61% aluminum, and 0.5% silicon. The water leaching solution contained: 14.37g gallium (98.24%), 0.001g lutetium (<0.02%), 0.0001g iron (<0.02%), 14.13g aluminum (90.55%), and 0.031g silicon (6.24%).

[0066] The steps of the water leaching reaction for removing silicon and aluminum include: adding 118g of calcium hydroxide solid to the water leaching solution mixed with the first and second water leaching solutions, reacting at 75°C for 1 hour to fully remove aluminum and silicon, and filtering to obtain calcium-aluminum-silicon slag and gallium-rich solution.

[0067] The steps for generating gallium hydroxide precipitate include: adding concentrated sulfuric acid to a gallium-rich solution to adjust the pH to 7.5, reacting for 1 hour, filtering and washing to obtain gallium hydroxide.

[0068] The acid leaching process includes: leaching hydrochloric acid (concentration 3.5 mol / L) and water leaching residue at a liquid-to-solid ratio of 4:1 at 85℃ for 1 hour, filtering and washing to obtain acid leaching residue and acid leaching solution. ICP spectroscopy analysis showed that the acid leaching solution contained: 0.0073 g gallium (0.05%), 6.65 g lutetium (99.31%), 0.44 g iron (82.65%), 0.0047 g aluminum (0.03%), and 0.0001 g silicon (0.02%).

[0069] The steps for removing impurities, purifying, and back-extracting the acid leaching solution include: first, mixing the extractant and acid leaching solution at an O / A ratio of 1:5 for 10 min and extracting to obtain iron extraction residue and a loaded organic phase, with the iron content in the iron extraction residue being less than 1 mg / L; then, mixing the purification extractant and iron extraction residue at an O / A ratio of 15:1 for 10 min and extracting to obtain lutetium extraction residue and a lutetium-rich organic phase, with the lutetium content in the lutetium extraction residue being less than 10 mg / L; finally, mixing the back-extractant and the lutetium-rich organic phase at an O / A ratio of 11:1 for 10 min. Extraction was performed at min to obtain lutetium back-extraction solution and organic phase, in which the lutetium content was less than 0.2 mg / L. The extractant used was a compound of 10% amine extractant N235, 20% 2-octanol and 70% kerosene, while the purified extractant was a compound of 20% P507 extractant, 20% C272 extractant and 60% kerosene. The back-extraction agent was hydrochloric acid (4.5 mol / L).

[0070] The steps for generating lutetium oxalate include: adding excess oxalic acid (concentration of 77 g / L) to the lutetium back-extraction solution, reacting at 40°C for 3 h to generate lutetium oxalate precipitate, filtering and washing to obtain lutetium oxalate. The amount of oxalic acid used is calculated based on the molar amount of lutetium in the oxalic acid / gallium-lutetium garnet waste being 1.7 / 1.

[0071] The calcination process includes: placing lutetium oxalate into a ceramic crucible and calcining it at 850°C for 3 hours to obtain lutetium oxide.

[0072] Example 4

[0073] Example 4 presents data on gallium lutetium recovered from gallium lutetium garnet waste provided in Examples 1-3, as shown in Tables 1-2.

[0074] Table 1: Recovery data of lutetium oxide

[0075]

[0076] Table 2: Gallium hydroxide recovery data

[0077]

[0078] As can be seen from Table 1-2, the method provided in this application successfully recovered gallium and lutetium from gallium-lutetium garnet waste. This is because after alkaline melting, this application successfully separated most of the gallium into the water leaching solution by water leaching, which contains 93.34-98.24% gallium, while most of the lutetium was in the acid leaching solution, which contains 95.28-99.31% lutetium, thus separating gallium and lutetium from the gallium-lutetium garnet waste.

[0079] As can be further seen from Table 1, the method provided in this application not only successfully recovered lutetium from gallium-lutetium garnet waste, but also achieved good purity and yield of the recovered lutetium. This is because, during the lutetium recovery process, this application used an extractant obtained by combining amine extractants, alcohols, and kerosene to extract the lutetium-containing acid leaching solution, resulting in an iron content of less than 1 mg / L in the iron extraction residue. Furthermore, a purified extractant obtained by combining P507 extractant, C272 extractant, and kerosene was used to extract and purify the iron extraction residue, resulting in an lutetium content of less than 10 mg / L in the lutetium extraction residue, with lutetium enriched in the lutetium-rich organic phase. Hydrochloric acid was also used for back-extraction of the lutetium-rich organic phase, resulting in an lutetium content of less than 0.2 mg / L in the organic phase, with lutetium enriched in the lutetium back-extraction solution. Then, excess oxalic acid was added to the lutetium back-extraction solution, thus achieving good lutetium purity and yield.

[0080] Furthermore, as can be seen from Table 2, the method provided in this application not only successfully recovered gallium from gallium-lutetium garnet waste, but also achieved good gallium purity and yield. This is because, in the process of gallium recovery, calcium hydroxide was added to the water leaching solution after alkali fusion, causing aluminum and silicon to precipitate through aluminum hydroxide precipitation, calcium aluminate, and calcium silicate, thereby resulting in a better gallium recovery rate and recovery effect in the water leaching solution.

[0081] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A method for separately recovering gallium lutetium from gallium lutetium garnet waste, characterized in that, Including the following steps: Step S1: The gallium lutetium garnet waste is crushed, alkali fused, water leached, and washed with pure water in sequence, and filtered to obtain water leaching solution and water leaching residue; Step S2: Add calcium hydroxide to the aqueous leaching solution to carry out the silicon-aluminum removal reaction, and filter to obtain a gallium-rich solution; Step S3: Add pH adjuster to gallium-rich solution to lower pH and carry out precipitation reaction, then filter to obtain gallium hydroxide precipitate; Step S4: The water-leached residue is subjected to acid leaching and pure water washing in sequence, and filtered to obtain acid leaching residue and acid leaching solution; Step S5: The acid leaching solution is subjected to extraction to remove iron, extraction to purify, and back-extracted in sequence to obtain lutetium-rich back-extracted solution; Step S6: Add oxalic acid to the lutetium-rich back-extraction solution to carry out a precipitation reaction, and filter to obtain lutetium oxalate; Step S7: Calcining lutetium oxalate yields lutetium oxide.

2. The method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S1, the crushing process is as follows: grinding until the particle size of the gallium lutetium garnet waste is no greater than 200 mesh; The alkali fusion process is as follows: gallium lutetium garnet waste and caustic soda flakes with a mass ratio of 1:1~3 are placed in a muffle furnace at 600~800℃ and calcined for 2~4 hours.

3. The method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S1, the water leaching process is as follows: the gallium lutetium garnet material after alkali fusion and water are leached at a temperature of 70-100°C for 0.5-2 hours in a mass ratio of 1:3-5, and the leaching residue and the first water leaching solution are obtained by filtration. The pure water washing process is as follows: the water-leached residue is washed with pure water at least once, and then filtered to obtain the washed water-leached residue and the second water-leached liquid.

4. The method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S2, during the silicon-aluminum removal reaction, the molar amount of calcium in the added calcium hydroxide is at least twice the sum of the molar amounts of aluminum and silicon in the gallium lutetium garnet waste.

5. A method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S2, the temperature of the silicon-aluminum removal reaction is 60~90℃ and the time is 0.5~2h.

6. A method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S3, the pH value of the precipitation reaction is 6-8, the temperature is room temperature, and the time is 0.5-2h.

7. The method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S4, the acid reagent used for acid leaching is 3.0~4.0 mol / L hydrochloric acid, the temperature is 70~100℃, and the time is 0.5~2h.

8. A method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S5, the extractant used for iron removal is selected from amine extractants, alcohols, and kerosene-based extractants. The extraction and purification agent used is selected from P507 extractant, C272 extractant and kerosene compounded extractant. The back-extraction agent used in the back-extraction is selected from hydrochloric acid.

9. A method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S6, the molar amount of oxalic acid used is at least 1.5 times the molar amount of lutetium in the gallium-lutetium garnet waste.

10. A method for separately recovering gallium lutetium from gallium lutetium garnet waste according to claim 1, characterized in that, In step S6, the precipitation reaction is carried out at a temperature of 30-50°C for 2-4 hours.

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