Method for recovering gallium and gadolinium from gadolinium gallium garnet waste

Abstract

A method for recovering gallium and gadolinium from a gadolinium gallium garnet waste material comprises the following steps: crushing and screening the gadolinium gallium garnet waste material to obtain gadolinium gallium garnet waste material particles; uniformly mixing the gadolinium gallium garnet waste particles with alkali and an oxidizing agent, putting the mixture into a crucible, and calcining to form alkali-fused slag; cooling the slag to room temperature, soaking the slag together with the crucible in a container filled with water, completely stripping the slag on the crucible into the water for water soaking, moving away the crucible, and heating and stirring; leaching the slag subjected to alkali fusion with water, and washing with filtered water to obtain water leaching slag and water leaching liquid; putting the water leaching residues into a container, adding water and acid, heating and stirring; after pickling the water leaching residues, filtering and washing to obtain pickling residues and a pickling solution; pouring the pickling solution into a container, adding an alkaline solution to adjust the pH value, and filtering to obtain gallium deposition slag and a gallium deposition post-solution; placing the gallium deposition slag in a container, adding alkali and water, heating and stirring; after alkaline leaching of the gallium precipitation slag, washing with filtered water to obtain alkaline leaching slag and alkaline leaching liquid; electrolyzing the water leaching solution and the alkaline leaching solution; placing the gallium-deposited solution in a container, adding an alkali solution to adjust the pH value, and stirring to react; and filtering to obtain liquid after gadolinium precipitation and gadolinium hydroxide.

Description

Technical Field

[0001] The present disclosure relates to the field of rare earth element and rare metal recovery, and more particularly to a method for recovering gallium gadolinium from gadolinium gallium garnet waste. Background Art

[0002] Gallium is a dispersed / rare metal with low content in nature. It is crucial to industrial development and is widely used in photovoltaics, magnetic materials, medical treatment, wireless communications, LED and other fields.

[0003] Gadolinium is a rare earth element with great effects and small usage. It plays an important role in improving product structure, increasing scientific and technological content, and promoting technological progress in the industry. It is widely used in metallurgy, military, petrochemical, glass and ceramics, agriculture, new materials and other fields.

[0004] The traditional method of recovering gallium is to acid-leach or alkaline-leach the gallium-containing material, remove impurities, and then recover gallium by electrolysis. Patent document CN105567982A discloses a method for recovering gallium from gallium nitride material: the material is dissolved by adding a strong base to an oxidant, and then metallic gallium is obtained by electrolytic deposition.

[0005] The method for recovering rare earth elements is to use a reducing agent or an extractant and an ion exchange resin to remove most of the iron ions in the rare earth-containing material, and then recover the rare earth elements by precipitation. Patent document CN104603303A discloses a method for recovering rare earth elements and rare metals, which uses a reducing agent or an extractant and an ion exchange resin to remove most of the iron ions, and then reacts with a precipitant to co-precipitate and recover the rare earth elements and rare elements.

[0006] Gadolinium gallium garnet is a garnet spatial configuration. The garnet structure is difficult to separate and recover gallium and gadolinium using traditional recovery methods. The leaching and separation effects of gallium and gadolinium are poor, the recovery rate is low, and the cost is high.

[0007] Therefore, there is a need to develop a method for recovering gallium gadolinium from gadolinium gallium garnet. Summary of the invention

[0008] In view of the problems existing in the background technology, an object of the present disclosure is to provide a method for recovering gadolinium gallium from gadolinium gallium garnet waste, which can separate and recover gadolinium gallium from gadolinium gallium garnet waste.

[0009] Another object of the present disclosure is to provide a method for recovering gallium gadolinium from gadolinium gallium garnet waste, which can recover gallium gadolinium with a high recovery rate.

[0010] Thus, a method for recovering gallium gadolinium from gadolinium gallium garnet waste comprises the following steps: S1, crushing and screening the gadolinium gallium garnet waste to obtain gadolinium gallium garnet waste particles; S2, alkali fusion, mixing the gadolinium gallium garnet waste particles with alkali and an oxidant evenly and then loading them into a crucible, placing the crucible in a roasting device for calcination, so that alkali-fused slag is formed in the crucible; S3, water immersion, after the alkali-fused slag is cooled to room temperature, placing it together with the crucible in a container filled with water for immersion, peeling off all the slag on the crucible into the water in the container for water immersion, removing the crucible after the slag is peeled off, and heating the container with stirring for reaction; S4, filtering and washing with water, after the alkali-fused slag is water-immersed, filtering to obtain filter residue and washing the filter residue with water as a washing liquid to obtain water-leached residue, and mixing the filtered filtrate with the washing liquid to form a water-leached liquid; S5, acid washing, placing the water-leached residue in a container, adding water and acid to the container, and heating the container with stirring for reaction; S6 , filter and wash with water, after the water leaching residue is acid-washed, filter to obtain filter residue and use water as washing liquid to wash the filter residue to obtain acid-washing residue, and mix the filtered filtrate with the washing liquid to form an acid-washing liquid; S7, gallium precipitation, pour the acid-washing liquid into a container, add an alkaline solution to the container to adjust the pH of gallium precipitation, and filter to obtain gallium precipitation residue and gallium precipitation liquid after a certain period of time; S8, alkaline leaching, place the gallium precipitation residue in a container, add alkali and water to the container, heat the container and stir to react; S9, filter and wash with water, after the gallium precipitation residue is alkaline-leached, filter to obtain filter residue and use water as washing liquid to wash the filter residue to obtain alkaline leaching residue, and mix the filtered filtrate with the washing liquid to form an alkaline leaching liquid; S10, electrolysis, electrolyze the water leaching liquid of step S4 and the alkaline leaching liquid of step S9 to recover metal gallium; S11, gadolinium precipitation, place the gallium precipitation liquid in a container, add an alkaline solution to the container to adjust the pH, and stir to react; S12, filter to obtain gadolinium precipitation liquid and gadolinium hydroxide.

[0011] The beneficial effects of the present disclosure are as follows: through steps S1 to S12, the recovery rate of gallium can reach 95.5-97.6% (i.e., reaching more than 95%), and the recovery rate of gadolinium can reach 95.6-98.2% (i.e., reaching more than 95%), which can not only separate and recover gadolinium gallium from insoluble gadolinium gallium garnet waste, but also recover gallium gadolinium with a high recovery rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a flow chart of a method for recovering gallium gadolinium from gadolinium gallium garnet waste according to the present disclosure. DETAILED DESCRIPTION

[0013] It will be understood that the disclosed embodiments are merely examples of the present disclosure, which may be implemented in various forms, and therefore, the specific details disclosed herein should not be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one of ordinary skill in the art to implement the present disclosure in various ways.

[0014] [Method for recovering gallium gadolinium from gadolinium gallium garnet waste]

[0015] Reference Figure 1 According to the present disclosure, the method for recovering gallium gadolinium from gadolinium gallium garnet waste comprises the steps of:

[0016] S1, crushing and screening the gadolinium gallium garnet waste to obtain gadolinium gallium garnet waste particles;

[0017] S2, alkali melting, mixing the gadolinium gallium garnet waste particles with alkali and oxidant evenly and loading them into a crucible, placing the crucible in a roasting device and calcining it to form alkali-melted slag in the crucible;

[0018] S3, water immersion, after the alkali-melted slag is cooled to room temperature, the slag is placed together with the crucible in a container filled with water for immersion, and all the slag on the crucible is peeled off into the water in the container for water immersion, and after the slag is peeled off, the crucible is removed, and the container is heated and stirred for reaction;

[0019] S4, filtering and washing with water, after the alkali-melted residue is soaked in water, filtering to obtain a filter residue and washing the filter residue with water as a washing liquid to obtain a water-leached residue, and mixing the filtered filtrate with the washing liquid to form a water-leached liquid;

[0020] S5, pickling, placing the water-soaked residue in a container, adding water and acid into the container, and heating and stirring the container for reaction;

[0021] S6, filtering the water for washing, and after the water-soaked residue is pickled, filtering to obtain a filter residue and using water as a washing liquid to wash the filter residue to obtain an acid-washed residue, and mixing the filtered filtrate with the washing liquid to form an acid-washing liquid;

[0022] S7, gallium precipitation, pouring the pickling solution into a container, adding an alkaline solution into the container to adjust the pH to precipitate gallium, and filtering after a certain period of gallium precipitation to obtain gallium precipitation slag and gallium precipitation liquid;

[0023] S8, alkali leaching, placing the gallium precipitated slag in a container, adding alkali and water into the container, and heating the container to stir for reaction;

[0024] S9, filtering the gallium precipitate after washing with water, filtering the precipitate after alkali leaching to obtain a filter residue, and washing the filter residue with water as a washing liquid to obtain an alkali leached residue, and mixing the filtered filtrate with the washing liquid to form an alkali leaching liquid;

[0025] S10, electrolysis, electrolyzing the water leaching solution of step S4 and the alkaline leaching solution of step S9 to recover metallic gallium;

[0026] S11, precipitating gadolinium, placing the solution after gallium precipitation in a container, adding an alkaline solution to the container to adjust the pH, and stirring the reaction;

[0027] S12, filtering to obtain gadolinium precipitated liquid and gadolinium hydroxide.

[0028] In the method for recovering gallium-gadolinium from gadolinium-gallium-garnet waste according to the present disclosure, through steps S1 to S12, as verified in the subsequent test process, the recovery rate of gallium can reach 95.5-97.6% (i.e., reaching more than 95%), and the recovery rate of gadolinium can reach 95.6-98.2% (i.e., reaching more than 95%), which not only can separate and recover gadolinium-gallium from the insoluble gadolinium-gallium-garnet waste, but also can recover gallium-gadolinium with a high recovery rate.

[0029] In step S1, for example, the gadolinium gallium garnet waste is SGGG, the Ga content is 27.83%, and the Gd content is 44.99%. In one example, in step S1, the gadolinium gallium garnet waste is crushed to less than 100 mesh, such as 100 mesh and 200 mesh.

[0030] In one example, in step S2, the amount of alkali added is 2-4 times the mass of the gadolinium gallium garnet waste particles, and the amount of oxidant added is 0.2-0.6 times the mass of the gadolinium gallium garnet waste particles. In one example, in step S2, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide, and the oxidant is selected from one or more of sodium peroxide and sodium chlorate. In one example, in step S2, the calcination temperature is controlled at 500-700°C, and the calcination time is 2-8h. In one example, in step S2, the crucible is a nickel crucible or a graphite crucible, and the roasting equipment is a muffle furnace.

[0031] In one example, in step S3, the water immersion time is 2-8 hours, during the water immersion, the liquid-solid ratio of water to gadolinium gallium garnet waste is 10-30, the water immersion temperature is controlled at 70-90° C., and the water immersion time is 1-4 hours. In one example, in step S3, the heating and stirring is performed using a magnetic stirrer, and the container is a beaker.

[0032] In one example, in step S5, the mass liquid-to-solid ratio of water to water-leached slag is 10-20, the acid concentration is controlled at 100-300 g / L, the pickling temperature is controlled at 70-90°C, and the pickling time is 1-4 hours. In one example, in step S5, the acid is selected from one or more of nitric acid, hydrochloric acid, phosphoric acid, and sulfuric acid. Further, nitric acid, hydrochloric acid, phosphoric acid, and sulfuric acid are industrial grade, specifically 68% nitric acid, 36% hydrochloric acid, 85% phosphoric acid, and 98% sulfuric acid. In one example, in step S5, a magnetic stirrer is used for heating and stirring, and the container is a beaker.

[0033] In one example, in step S7, the alkali of the alkaline solution is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide. In one example, in step S7, the mass fraction of the alkali used for pH is 5-50%, the pH of gallium precipitation is controlled at 5-8, and the gallium precipitation time is controlled at 0.5-4h. In one example, in step S7, the container is a beaker, and the gallium is stirred during precipitation, and the stirring is carried out using a magnetic stirrer.

[0034] In one example, in step S8, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide. In step S8, during alkali leaching, the alkali concentration is 10-100 g / L, the mass liquid-solid ratio of water to gallium precipitate slag is 6-20, the alkali leaching temperature is controlled at 60-80°C, and the alkali leaching time is 0.5-4h. In one example, in step S8, a magnetic stirrer is used for heating and stirring, and the container is a beaker.

[0035] In one example, in step S10, the electrolysis uses a graphite or platinum plate as an anode, a stainless steel plate, a titanium plate or a platinum plate as a cathode, and controls the current density to be 10-100 A / m 2 The water leaching solution of step S4 or the alkaline leaching solution of step S8 is used as the electrolyte, the temperature of the electrolyte is 20-80°C, gallium is reduced and precipitated at the cathode, and the cathode product is washed with pure water until the pH of the attached liquid is 6-8 to obtain 4N gallium.

[0036] In one example, in step S11, the alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide. In step S11, in one example, the mass fraction of the alkali solution is 5-50%, the pH of the solution after gallium precipitation is adjusted to above 11 to precipitate gadolinium, and the stirring time is 0.5-4h. In step S11, the stirring is performed using a magnetic stirrer and the container is a beaker.

[0037] In addition, the pickling slag in step S6 and the alkaline leaching slag in step S9 are recovered, the pickling slag in step S6 is gadolinium oxide, and the alkaline leaching slag in step S9 is gadolinium hydroxide.

[0038] Furthermore, the water in step S3, step S4, step S5, step S6, step S8 and step S9 may be pure water. In an alternative example, the water in step S3, step S4, step S5, step S6, step S8 and step S9 is tap water.

[0039] [test]

[0040] Example 1

[0041] Example 1 adopts the following steps:

[0042] S1, crushing and screening the gadolinium gallium garnet waste to obtain gadolinium gallium garnet waste particles, wherein the gadolinium gallium garnet waste is SGGG, the Ga content is 27.83%, the Gd content is 44.99%, and the crushed gadolinium gallium garnet waste is screened through a 200-mesh sieve;

[0043] S2, alkali fusion, 20g of gadolinium gallium garnet waste particles, 40g of alkali selected from sodium hydroxide, and 4g of oxidant selected from sodium peroxide (i.e., the amount of alkali added is 2 times the mass of the gadolinium gallium garnet waste particles, and the amount of oxidant added is 0.2 times the mass of the gadolinium gallium garnet waste particles) are mixed evenly and then loaded into a crucible selected from a nickel crucible, and the crucible is placed in a roasting device using a muffle furnace for calcination to form alkali-fused slag in the crucible, the calcination temperature is controlled at 600°C, and the calcination time is 4h;

[0044] S3, water immersion, after the alkali-melted slag is cooled to room temperature, it is placed together with the crucible in a container containing 200 ml of pure water in a beaker for immersion, and the immersion time is 3 hours. All the slag on the crucible is peeled off into the water in the container (i.e., the liquid-to-solid ratio of water to gadolinium gallium garnet waste is 10) for water immersion. After the slag is peeled off, the crucible is removed, and the container is heated and stirred for reaction. The heating and stirring are carried out by a magnetic stirrer. The heating provided by the magnetic stirrer makes the water immersion temperature controlled at 80°C, and the water immersion time is 2 hours;

[0045] S4, filtering and washing with water, after the alkali-melted slag is soaked in water, filtering to obtain filter residue, and washing the filter residue with pure water as washing liquid to obtain water-leached residue, mixing the filtered filtrate with the washing liquid to form a water-leached liquid, wherein the water-leached residue is sampled, and the element content thereof is detected by ICP spectrometer, and the Ga content of the water-leached residue is 3.42%, the Gd content is 59.81%, and the gallium leaching rate is 90%;

[0046] S5, pickling, putting the water-leached residue into a container using a beaker, adding pure water with a mass of 10 times that of the water-leached residue (i.e., the mass liquid-to-solid ratio of water to the water-leached residue is 10) and acid selected from industrial-grade 98% sulfuric acid with a mass of 1.5 times that of the water-leached residue (i.e., the acid concentration is controlled at 150 g / L) into the container, heating and stirring the container for reaction, using a magnetic stirrer for heating and stirring, and the pickling temperature is controlled at 80° C. by the heating provided by the magnetic stirrer, and the pickling time is 2 h;

[0047] S6, filtering water washing, after pickling the water-leached residue, filtering to obtain filter residue, and washing the filter residue with pure water as washing liquid to obtain pickling residue, mixing the filtered filtrate with the washing liquid to form a pickling liquid, wherein the pickling residue is sampled, and the element content thereof is detected by ICP spectrometer, and the Ga content of the pickling residue is 2.08%, the Gd content is 40.41%, and the total gallium leaching rate is 97%;

[0048] S7, gallium precipitation, pouring the pickling liquid into a container using a beaker, adding an alkaline solution with a mass fraction of 32% sodium hydroxide to the container to adjust the pH to 5 and stirring to precipitate gallium, filtering to obtain gallium precipitate slag and gallium precipitation liquid after a certain period of time, wherein the stirring is carried out using a magnetic stirrer, and the gallium precipitation time is controlled at 0.5h, wherein the gallium precipitation liquid is sampled and the element content thereof is detected by an ICP spectrometer, and the Ga content of the gallium precipitation liquid is <1ppm, and the Gd content is 7200ppm;

[0049] S8, alkali leaching, placing the gallium precipitate slag in a container using a beaker, adding alkali using sodium hydroxide in an amount of 0.1 times the mass of the gallium precipitate slag and pure water in an amount of 10 times the mass of the gallium precipitate slag (i.e., the mass liquid-solid ratio of water to the gallium precipitate slag is 10, and the alkali concentration is 10 g / L) into the container, heating and stirring the container for reaction, using a magnetic stirrer for heating and stirring, and controlling the alkali leaching temperature at 60° C. through the heating provided by the magnetic stirrer, and the alkali leaching time is 1 hour;

[0050] S9, filtering water for washing, alkali leaching of the gallium precipitated slag, filtering to obtain filter residue, and washing the filter residue with pure water as a washing liquid to obtain alkali leaching residue, mixing the filtered filtrate with the washing liquid to form an alkali leaching solution, wherein the alkali leaching residue is sampled, and the element content thereof is detected by an ICP spectrometer, and the Ga content of the alkali leaching residue is 1200ppm, the Gd content is 22%, and the gallium leaching rate is 98.5%;

[0051] S10, electrolysis, electrolyzing the water leaching solution of step S4 and the alkaline leaching solution of step S9 to recover metallic gallium, wherein the electrolysis uses a platinum plate as an anode and a platinum plate as a cathode, and controls the current density to be 60A / m 2 , the water leaching solution of step S4 or the alkaline leaching solution of step S8 is used as the electrolyte, the temperature of the electrolyte is 50°C, gallium is reduced and precipitated at the cathode, the cathode product is washed with pure water until the pH of the attached liquid is 7, 4N gallium is obtained, and the gallium loss rate is 3%. Based on the gallium leaching rate of step S9, the total gallium recovery rate after electrolysis is 95.5%;

[0052] S11, precipitating gadolinium, placing the gallium precipitate in a beaker container, adding 32% sodium hydroxide alkaline solution to the container to adjust the pH to 11.32, stirring the reaction, stirring with a magnetic stirrer, and stirring for 0.5 h;

[0053] S12, filtering to obtain gadolinium precipitation liquid and gadolinium hydroxide, wherein the gadolinium precipitation liquid is sampled and the element content thereof is detected by ICP spectrometer, the Ga content of the gadolinium precipitation liquid is <1ppm, the Gd content is <1ppm, and the gadolinium precipitation rate is above 99%. Since most of the gallium in the gadolinium gallium garnet waste has been separated and recovered, most of the gadolinium remains in the waste. Based on the fact that the pickling slag in step S6 is gadolinium oxide, the alkaline leaching slag in step S9 is gadolinium hydroxide, and the gadolinium hydroxide in step S12, the recovery rate of gadolinium is above 95.6%.

[0054] Example 2

[0055] Example 2 adopts the following steps:

[0056] S1, crushing and screening the gadolinium gallium garnet waste to obtain gadolinium gallium garnet waste particles, wherein the gadolinium gallium garnet waste is SGGG, the Ga content is 27.83%, the Gd content is 44.99%, and the crushed gadolinium gallium garnet waste is screened through a 100-mesh sieve;

[0057] S2, alkali fusion, 20g of gadolinium gallium garnet waste particles, 60g of a base selected from potassium hydroxide, and 6g of an oxidant selected from sodium chlorate (i.e., the amount of the base added is 3 times the mass of the gadolinium gallium garnet waste particles, and the amount of the oxidant added is 0.3 times the mass of the gadolinium gallium garnet waste particles) are mixed evenly, and then loaded into a crucible selected from a nickel crucible, and the crucible is placed in a roasting device using a muffle furnace for calcination to form alkali-fused slag in the crucible, and the calcination temperature is controlled at 700°C, and the calcination time is 3h;

[0058] S3, water immersion, after the alkali-melted slag is cooled to room temperature, it is placed together with the crucible in a container containing 200 ml of pure water in a beaker for immersion, the immersion time is 2 hours, all the slag on the crucible is peeled off into the water in the container (that is, the liquid-to-solid ratio of water to gadolinium gallium garnet waste is 10) for water immersion, after the slag is peeled off, the crucible is removed, and the container is heated and stirred for reaction, the heating and stirring are carried out by a magnetic stirrer, the heating provided by the magnetic stirrer is provided so that the water immersion temperature is controlled at 90°C, and the water immersion time is 1 hour;

[0059] S4, filtering water washing, after alkali fusion, the slag is water-soaked, filtered to obtain filter residue, and the filter residue is washed with pure water as a washing liquid to obtain water-soaked residue, and the filtered filtrate is mixed with the washing washing liquid to form a water-soaked liquid, wherein the water-soaked residue is sampled, and the element content thereof is detected by an ICP spectrometer, and the Ga content of the water-soaked residue is 3.12%, the Gd content is 62.34%, and the gallium leaching rate is 92.6%;

[0060] S5, pickling, putting the water-leached residue into a container using a beaker, adding pure water with a mass of 20 times that of the water-leached residue (i.e., the mass liquid-to-solid ratio of water to the water-leached residue is 20) and acid selected from industrial-grade 68% nitric acid with a mass of 2 times that of the water-leached residue (i.e., the acid concentration is controlled at 100 g / L) into the container, heating and stirring the container for reaction, using a magnetic stirrer for heating and stirring, and the pickling temperature is controlled at 70° C. by the heating provided by the magnetic stirrer, and the pickling time is 2.5 h;

[0061] S6, filtering water for washing, and pickling the water-leached residue, filtering to obtain filter residue, and washing the filter residue with pure water as a washing liquid to obtain pickled residue, and mixing the filtered filtrate with the washing liquid to form a pickling liquid, wherein the pickled residue is sampled, and the element content thereof is detected by an ICP spectrometer, and the Ga content of the pickled residue is 2%, the Gd content is 43.32%, and the total gallium leaching rate is 96.5%;

[0062] S7, gallium precipitation, pouring the pickling liquid into a container using a beaker, adding an alkaline solution with a mass fraction of 16% potassium hydroxide to the container to adjust the pH to 6.5 and stirring to precipitate gallium, filtering to obtain gallium precipitation slag and gallium precipitation liquid after a certain period of time, wherein the stirring is carried out using a magnetic stirrer, and the gallium precipitation time is controlled to be 1h, wherein the gallium precipitation liquid is sampled and the element content thereof is detected by an ICP spectrometer, and the Ga content of the gallium precipitation liquid is <1ppm, and the Gd content is 6892ppm;

[0063] S8, alkali leaching, placing the gallium precipitate slag in a container using a beaker, adding alkali using potassium hydroxide in an amount of 0.2 times the mass of the gallium precipitate slag and pure water in an amount of 8 times the mass of the gallium precipitate slag (i.e., the mass liquid-solid ratio of water to the gallium precipitate slag is 8, and the alkali concentration is 25 g / L) into the container, heating and stirring the container for reaction, using a magnetic stirrer for heating and stirring, and the alkali leaching temperature is controlled at 70° C. by the heating provided by the magnetic stirrer, and the alkali leaching time is 1.5 h;

[0064] S9, filtering water for washing, alkali leaching of the gallium precipitated slag, filtering to obtain filter residue, and washing the filter residue with pure water as a washing liquid to obtain alkali leaching residue, mixing the filtered filtrate with the washing liquid to form an alkali leaching solution, wherein the alkali leaching residue is sampled, and the element content thereof is detected by an ICP spectrometer, and the Ga content of the alkali leaching residue is 1800ppm, the Gd content is 36%, and the gallium leaching rate is 98.65%;

[0065] S10, electrolysis, electrolyzing the water leaching solution of step S4 and the alkaline leaching solution of step S9 to recover metallic gallium, wherein the electrolysis uses a platinum plate as an anode and a platinum plate as a cathode, and controls the current density to be 60A / m 2 , the water leaching solution of step S4 or the alkaline leaching solution of step S8 is used as the electrolyte, the temperature of the electrolyte is 50°C, gallium is reduced and precipitated at the cathode, the cathode product is washed with pure water until the pH of the attached liquid is 7, 4N gallium is obtained, and the loss rate of gallium is 2%. Based on the gallium leaching rate of step S9, the total recovery rate of gallium after electrolysis is 96.7%;

[0066] S11, precipitating gadolinium. The solution after precipitating gallium is placed in a container using a beaker, and an alkaline solution of potassium hydroxide with a mass fraction of 16% is added to the container to adjust the pH to 12, and the reaction is stirred. A magnetic stirrer is used for stirring, and the stirring time is 1 hour;

[0067] S12, filtering to obtain gadolinium precipitation liquid and gadolinium hydroxide, wherein the gadolinium precipitation liquid is sampled and the element content thereof is detected by ICP spectrometer, the Ga content of the gadolinium precipitation liquid is <1ppm, the Gd content is <1ppm, and the gadolinium precipitation rate is above 99%. Since most of the gallium in the gadolinium gallium garnet waste has been separated and recovered, most of the gadolinium remains in the waste. Based on the fact that the pickling slag in step S6 is gadolinium oxide, the alkaline leaching slag in step S9 is gadolinium hydroxide, and the gadolinium hydroxide in step S12, the recovery rate of gadolinium reaches above 97.8%.

[0068] Example 3

[0069] Example 3 adopts the following steps:

[0070] S1, crushing and screening the gadolinium gallium garnet waste to obtain gadolinium gallium garnet waste particles, wherein the gadolinium gallium garnet waste is SGGG, the Ga content is 27.83%, the Gd content is 44.99%, and the crushed gadolinium gallium garnet waste is screened through a 100-mesh sieve;

[0071] S2, alkali melting, mixing 20g of gadolinium gallium garnet waste particles with 40g of a base selected from calcium hydroxide and 8g of an oxidant selected from sodium chlorate (i.e., the amount of the base added is 2 times the mass of the gadolinium gallium garnet waste particles, and the amount of the oxidant added is 0.4 times the mass of the gadolinium gallium garnet waste particles) and then loading them into a crucible selected from a nickel crucible, placing the crucible in a roasting device using a muffle furnace and calcining it to form alkali-melted slag in the crucible, the calcination temperature is controlled at 600°C, and the calcination time is 4h;

[0072] S3, water immersion, after the alkali-melted slag is cooled to room temperature, it is placed together with the crucible in a beaker containing 400 ml of pure water for immersion for 3 hours, and all the slag on the crucible is peeled off into the water in the container (i.e., the liquid-to-solid ratio of water to gadolinium gallium garnet waste is 20) for water immersion. After the slag is peeled off, the crucible is removed, and the container is heated and stirred for reaction. The heating and stirring are performed by a magnetic stirrer, and the heating provided by the magnetic stirrer is provided so that the water immersion temperature is controlled at 70° C. The water immersion time is 2 hours;

[0073] S4, filtering and washing with water, after the alkali-melted slag is soaked in water, filtering to obtain filter residue, and washing the filter residue with pure water as washing liquid to obtain water-leached residue, mixing the filtered filtrate with the washing liquid to form a water-leached liquid, wherein the water-leached residue is sampled, and the element content thereof is detected by ICP spectrometer, and the Ga content of the water-leached residue is 2.96%, the Gd content is 60.21%, and the gallium leaching rate is 95.6%;

[0074] S5, pickling, putting the water-leached residue into a container using a beaker, adding pure water with a mass of 10 times that of the water-leached residue (i.e., the mass liquid-to-solid ratio of water to the water-leached residue is 10) and acid selected from industrial-grade 36% hydrochloric acid with a mass of 2 times that of the water-leached residue (i.e., the acid concentration is controlled at 200 g / L) into the container, heating and stirring the container for reaction, using a magnetic stirrer for heating and stirring, and controlling the pickling temperature at 80° C. through the heating provided by the magnetic stirrer, and the pickling time is 2 hours;

[0075] S6, filtering water washing, after pickling the water-leached residue, filtering to obtain filter residue, and washing the filter residue with pure water as washing liquid to obtain pickling residue, mixing the filtered filtrate with the washing liquid to form a pickling liquid, wherein the pickling residue is sampled, and the element content thereof is detected by ICP spectrometer, and the Ga content of the pickling residue is 1.86%, the Gd content is 39.6%, and the total gallium leaching rate is 98.7%;

[0076] S7, gallium precipitation, pouring the pickling liquid into a container using a beaker, adding an alkaline solution of sodium bicarbonate with a mass fraction of 32% to the container to adjust the pH to 8 and stirring to precipitate gallium, filtering to obtain gallium precipitation slag and gallium precipitation liquid after a certain period of time, wherein the stirring is carried out using a magnetic stirrer, and the gallium precipitation time is controlled at 1.5h, wherein the gallium precipitation liquid is sampled and the element content thereof is detected by an ICP spectrometer, and the Ga content of the gallium precipitation liquid is <1ppm, and the Gd content is 6980ppm;

[0077] S8, alkali leaching, placing the gallium precipitate slag in a container using a beaker, adding alkali selected from potassium hydroxide in an amount of 0.2 times the mass of the gallium precipitate slag and pure water in an amount of 10 times the mass of the gallium precipitate slag (i.e., the mass liquid-solid ratio of water to the gallium precipitate slag is 10, and the alkali concentration is 20 g / L) into the container, heating and stirring the container for reaction, using a magnetic stirrer for heating and stirring, and the alkali leaching temperature is controlled at 70° C. by the heating provided by the magnetic stirrer, and the alkali leaching time is 1 hour;

[0078] S9, filtering water for washing, alkali leaching of the gallium precipitated slag, filtering to obtain filter residue, and washing the filter residue with pure water as a washing liquid to obtain alkali leaching residue, mixing the filtered filtrate with the washing liquid to form an alkali leaching solution, wherein the alkali leaching residue is sampled, and the element content thereof is detected by an ICP spectrometer, and the Ga content of the alkali leaching residue is 1102ppm, the Gd content is 21.36%, and the gallium leaching rate is 99.32%;

[0079] S10, electrolysis, electrolyzing the water leaching solution of step S4 and the alkaline leaching solution of step S9 to recover metallic gallium, wherein the electrolysis uses a platinum plate as an anode and a platinum plate as a cathode, and controls the current density to be 60A / m 2, using the water leaching solution of step S4 or the alkaline leaching solution of step S8 as the electrolyte, the temperature of the electrolyte is 50°C, gallium is reduced and precipitated at the cathode, the cathode product is washed with pure water until the pH of the attached liquid is 7, and 4N gallium is obtained, and the loss rate of gallium is 1.7%, wherein, based on the gallium leaching rate of step S9, the total recovery rate of gallium after electrolysis is 97.6%;

[0080] S11, precipitating gadolinium. The solution after gallium precipitation is placed in a beaker container, and a sodium bicarbonate solution with a mass fraction of 16% is added to the container to adjust the pH to 12, and the reaction is stirred. A magnetic stirrer is used for stirring, and the stirring time is 1.5 hours;

[0081] S12, filtering to obtain gadolinium precipitation liquid and gadolinium hydroxide, wherein the gadolinium precipitation liquid is sampled and the element content thereof is detected by ICP spectrometer, the Ga content of the gadolinium precipitation liquid is <1ppm, the Gd content is <1ppm, and the gadolinium precipitation rate is above 99%. Since most of the gallium in the gadolinium gallium garnet waste has been separated and recovered, most of the gadolinium remains in the waste. Based on the fact that the pickling slag in step S6 is gadolinium oxide, the alkaline leaching slag in step S9 is gadolinium hydroxide, and the gadolinium hydroxide in step S12, the recovery rate of gadolinium is above 998.2%.

[0082] The above detailed description is used to describe multiple exemplary embodiments, but this document is not intended to be limited to the explicitly disclosed combinations. Therefore, unless otherwise stated, the various features disclosed herein can be combined together to form multiple additional combinations that are not shown for the sake of simplicity.

Claims

1. A method for recovering gallium gadolinium from gadolinium gallium garnet waste, characterized in that: Includes steps: S1, crushing and screening the gadolinium gallium garnet waste to obtain gadolinium gallium garnet waste particles; S2, alkali melting, mixing the gadolinium gallium garnet waste particles with alkali and oxidant evenly and loading them into a crucible, placing the crucible in a roasting device and calcining it to form alkali-melted slag in the crucible; S3, water immersion, after the alkali-melted slag is cooled to room temperature, the slag is placed together with the crucible in a container filled with water for immersion, and all the slag on the crucible is peeled off into the water in the container for water immersion, and after the slag is peeled off, the crucible is removed, and the container is heated and stirred for reaction; S4, filtering and washing with water, after the alkali-melted residue is soaked in water, filtering to obtain a filter residue and washing the filter residue with water as a washing liquid to obtain a water-leached residue, and mixing the filtered filtrate with the washing liquid to form a water-leached liquid; S5, pickling, placing the water-soaked residue in a container, adding water and acid into the container, and heating and stirring the container for reaction; S6, filtering the water for washing, and after the water-soaked residue is pickled, filtering to obtain a filter residue and using water as a washing liquid to wash the filter residue to obtain an acid-washed residue, and mixing the filtered filtrate with the washing liquid to form an acid-washing liquid; S7, gallium precipitation, pouring the pickling solution into a container, adding an alkaline solution into the container to adjust the pH to precipitate gallium, and filtering after a certain period of gallium precipitation to obtain gallium precipitation slag and gallium precipitation liquid; S8, alkali leaching, placing the gallium precipitated slag in a container, adding alkali and water into the container, and heating the container to stir for reaction; S9, filtering the gallium precipitate after washing with water, filtering the precipitate after alkali leaching to obtain a filter residue, and washing the filter residue with water as a washing liquid to obtain an alkali leached residue, and mixing the filtered filtrate with the washing liquid to form an alkali leaching liquid; S10, electrolysis, electrolyzing the water leaching solution of step S4 and the alkaline leaching solution of step S9 to recover metallic gallium; S11, precipitating gadolinium, placing the solution after gallium precipitation in a container, adding an alkaline solution to the container to adjust the pH, and stirring the reaction; S12, filtering to obtain gadolinium precipitated liquid and gadolinium hydroxide.

2. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S1 , the gadolinium gallium garnet waste is SGGG, the Ga content is 27.83%, and the Gd content is 44.99%.

3. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S2, The amount of alkali added is 2-4 times the mass of the gadolinium gallium garnet waste particles. The amount of the oxidant added is 0.2-0.6 times the mass of the gadolinium gallium garnet waste particles; The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide, The oxidant is selected from one or more of sodium peroxide and sodium chlorate; The calcination temperature is controlled at 500-700°C and the calcination time is 2-8h.

4. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S3, the water immersion time is 2-8 hours, during the water immersion, the liquid-to-solid ratio of water to the gadolinium gallium garnet waste is 10-30, the water immersion temperature is controlled at 70-90° C., and the water immersion time is 1-4 hours.

5. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S5, The mass liquid-solid ratio of water to water-leached residue is 10-20, the acid concentration is controlled at 100-300g / L, the pickling temperature is controlled at 70-90℃, and the pickling time is 1-4h; The acid is selected from one or more of nitric acid, hydrochloric acid, phosphoric acid and sulfuric acid.

6. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 5, characterized in that: Nitric acid, hydrochloric acid, phosphoric acid and sulfuric acid are of industrial grade.

7. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S7, The alkali of the alkaline solution is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide; The mass fraction of the alkali used for pH is 5-50%, the pH of gallium precipitation is controlled at 5-8, and the gallium precipitation time is controlled at 0.5-4h.

8. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S8, The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide; During alkali leaching, the alkali concentration is 10-100 g / L, the mass liquid-solid ratio of water to gallium precipitate slag is 6-20, the alkali leaching temperature is controlled at 60-80° C., and the alkali leaching time is 0.5-4 h.

9. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S10, Electrolysis uses graphite or platinum plates as anodes, stainless steel plates, titanium plates or platinum plates as cathodes. Control current density to 10-100A / m 2 The water leaching solution of step S4 or the alkaline leaching solution of step S8 is used as the electrolyte at a temperature of 20-80°C to reduce and precipitate gallium at the cathode. The cathode product is washed with pure water until the pH of the attached liquid is 6-8 to obtain 4N gallium.

10. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: In step S11, The alkali is selected from one or more of sodium hydroxide, potassium hydroxide, sodium carbonate, sodium bicarbonate, and calcium hydroxide; The mass fraction of the alkaline solution is 5-50%. After gallium precipitation, the pH of the solution is adjusted to above 11 to precipitate gadolinium. The stirring time is 0.5-4h.

11. The method for recovering gallium gadolinium from gadolinium gallium garnet waste according to claim 1, characterized in that: The pickling residue in step S6 and the alkaline leaching residue in step S9 are recovered, the pickling residue in step S6 is gadolinium oxide, and the alkaline leaching residue in step S9 is gadolinium hydroxide.

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