A method for recovering metallic gallium and indium from gallium-based liquid metal waste

Abstract

The present invention relates to a method for recovering metallic gallium and indium from gallium-based liquid metal waste, and belongs to the technical field of high-value recovery of waste resources. The method of the present invention is to subject gallium-based liquid metal waste to oxidation and roasting in a muffle furnace to obtain metal oxides of various elements, and then to separate and enrich under different conditions by a two-stage vacuum carbon thermal reduction method to obtain a Ga-In alloy with higher purity. At the same time, Zn is also enriched and recovered. The mixture of Sn and carbonaceous reducing agent can continue to be recycled as a reducing agent. During the circulation process, not only the purity of the gallium-indium alloy and the zinc enrichment is significantly improved, but also the enrichment of Sn can be achieved, which provides further technical support for the subsequent recovery of Sn. The product obtained by the treatment of the present invention has a high recovery rate of each metal and high purity. The present invention is simple to operate, highly efficient, and has a high comprehensive recovery rate; it provides a new way for the efficient, clean treatment and recovery of gallium-based liquid metal waste.

Description

Technical Field

[0001] The invention relates to a method for recovering metallic gallium and indium from gallium-based liquid metal waste, belonging to the technical field of high-value recovery of waste resources. Background Art

[0002] Gallium-based liquid metal, primarily made from gallium-indium-tin alloys in varying proportions, is a broad class of multimetallic alloys that are liquid at room temperature and can flexibly transition between solid and liquid phases. They possess strong electrical and thermal conductivity, a controllable melting point, and require no high-temperature smelting, are environmentally friendly and non-toxic, and possess numerous remarkable physical, chemical, and even biological properties. They are widely used in aerospace, military, defense, biomedicine, education, and culture. As a novel material, gallium-based liquid metal has made significant progress in its applications, including actuators, flexible circuits, biodevices, and self-healing superconductors. Its waste, primarily composed of gallium and indium, possesses extremely high recycling value. Gallium and indium are in high demand within the technology industry due to their limited reserves. Given their potential benefits, research into recovering gallium and indium from secondary resources is urgently needed. While the applications of gallium-based liquid metal continue to expand, the recycling of its waste remains largely unreported. Therefore, research into recovering the valuable metals gallium and indium from gallium-based liquid metal is urgently needed.

[0003] This invention uses vacuum carbothermal reduction to extract the valuable metals gallium and indium from gallium-based liquid metal waste. This process recovers and enriches the gallium-indium alloy, while also enriching zinc. Tin is also enriched by mixing it with a carbonaceous reducing agent at the furnace bottom and undergoing decarburization. Summary of the Invention

[0004] To address the lack of existing valuable metal recovery processes for gallium-based liquid metal waste, the present invention provides a method for recovering gallium and indium from gallium-based liquid metal waste. This method offers a simple process flow, clean and pollution-free operation, and excellent separation efficiency, providing a new approach to the recycling of liquid metal waste. The present invention utilizes the following technical solutions.

[0005] The present invention provides a method for recovering metallic gallium and indium from gallium-based liquid metal waste, the specific steps of which are:

[0006] (1) Gallium-based liquid metal waste is oxidized and roasted at 600-900° C. to obtain a roasted product; the roasted product is crushed and ground to a particle size of 60-200 mesh; the gallium-based liquid metal waste contains indium and gallium; preferably contains indium, gallium, zinc, and tin;

[0007] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2-6 to obtain a standby mixed material;

[0008] (3) placing the standby mixed material obtained in step (2) into a vertical vacuum furnace, evacuating the air in the furnace to 1-10 Pa, raising the temperature to 500-850°C, preferably 600-800°C, and treating at a constant temperature for 30-240 min, collecting the Zn-enriched product in a condensation tray, and collecting the Zn-free residue at the bottom of the furnace;

[0009] (4) The Zn-removed residue in step (3) is subjected to a secondary vacuum carbon thermal reduction at 1050-1250°C, preferably 1100-1200°C, and the temperature is kept constant for 30-240 minutes. The gallium-indium alloy product is collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent is obtained at the bottom of the furnace. During the secondary vacuum carbon thermal reduction, the gas pressure in the furnace is controlled to be 1-10 Pa.

[0010] The present invention provides a method for recovering metallic gallium and indium from gallium-based liquid metal waste. The mixture of Sn and carbonaceous reducing agent obtained in step (4) is returned to step 2 for recycling.

[0011] In industrial applications, when the carbon content of the mixture of Sn and carbonaceous reducing agent obtained at the furnace bottom is less than or equal to Awt%, additional carbon is added. The value of A is 8-25.

[0012] The contents of gallium, indium, tin, zinc and oxygen in the gallium-based liquid metal waste are 57.84-66.99 wt.%, 11.90-13.95 wt.%, 9.56-11.42 wt.%, 1.86-6.23 wt.% and 1.41-18.84 wt.%, respectively.

[0013] As a further preference, the contents of gallium, indium, tin, zinc and oxygen in the gallium-based liquid metal waste are 60-61 wt.%, 11-12 wt.%, 10-10.5 wt.%, 3-3.5 wt.% and 14-15 wt.%, respectively.

[0014] The roasting in step (1) is atmospheric pressure oxidation roasting.

[0015] In step (2), the mass ratio of the calcined product to the carbonaceous reducing agent is 1:2-4.5.

[0016] In step (2), the carbonaceous reducing agent is selected from at least one of charcoal, petroleum coke, bituminous coal, and activated carbon. The first carbonaceous reducing agent is preferably composed of at least one of charcoal and activated carbon and at least one of petroleum coke and bituminous coal. As a further preferred embodiment, the content of petroleum coke and bituminous coal in the first carbonaceous reducing agent accounts for 20-60% of the carbonaceous reducing agent.

[0017] During the research process, the present invention found that the recycling of a mixture of Sn and a carbonaceous reducing agent can achieve unexpected results.

[0018] In the gallium-indium alloy obtained by the present invention, the recovery rates of gallium and indium relative to the corresponding gallium and indium in the raw material gallium-based liquid metal waste are both above 90%. In the obtained gallium-indium alloy, excluding gallium and indium, the content of other elements is less than or equal to 5wt%.

[0019] The Sn and carbonaceous reducing agent mixture is recycled, and the recovery rate of Sn can reach more than 95%. In the Sn enriched product obtained after decarburization treatment, the content of other elements except Sn is less than or equal to 5%.

[0020] The beneficial effects of the present invention are:

[0021] (1) The present invention uses a carbonaceous reducing agent to reduce the roasted product of gallium-based liquid metal waste under vacuum conditions, achieving a significant reduction effect and a metal volatilization temperature lower than that under normal pressure. The resulting gallium-indium alloy has a recovery rate of over 90% for both gallium and indium relative to the corresponding gallium and indium in the raw gallium-based liquid metal waste. The content of other elements in the resulting gallium-indium alloy, excluding gallium and indium, is less than or equal to 5% by weight. The recovery rate and purity of the gallium-indium alloy of the present invention are far superior to those of the existing technology for separating complex zinc-indium-gallium-tin alloys.

[0022] (2) In the present invention, tin and zinc are also enriched in different processes and regions, which facilitates subsequent purification and recovery.

[0023] (3) The present invention realizes for the first time the efficient separation of gallium, indium and tin by only carbon thermal vacuum reduction of oxide materials containing gallium, indium and tin.

[0024] (4) The present invention creatively recycles the mixture of Sn and carbonaceous reducing agent, which not only significantly improves the purity of gallium-indium alloy and zinc enrichment, but also achieves Sn enrichment, thus providing further technical support for the subsequent utilization of Sn.

[0025] (5) This method has a simple process flow, high efficiency, and no waste gas pollution, providing a new idea for the recycling of liquid metal waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a process flow chart of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with specific embodiments.

[0028] Example 1: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0029] In this embodiment, the contents of gallium, indium, tin, zinc, and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.%, and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is charcoal.

[0030] The specific steps are as follows:

[0031] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0032] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0033] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 600°C, and maintain the temperature for 60 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0034] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1050°C for 60 min, and the gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0035] The gallium recovery rate of the gallium-indium alloy obtained in this example relative to the raw material (gallium-based liquid metal waste) was 91.33%, and the indium recovery rate relative to the raw material in the gallium-indium alloy was 92.24%. The mass percentage of gallium + indium in the resulting gallium-indium alloy was approximately 91.82 wt%. The zinc recovery rate and purity were 95.33% and 86.38 wt%, respectively. Tin, which accumulated at the furnace bottom with the carbonaceous reducing agent, had a tin recovery rate and purity of 99.32% and 63.25 wt%, respectively.

[0036] Example 2: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0037] In this embodiment, the contents of gallium, indium, tin, zinc, and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.%, and 14.39 wt.%, respectively; and the carbonaceous reducing agents used are charcoal and bituminous coal (the mass ratio of charcoal to bituminous coal is 1:1).

[0038] The specific steps are as follows:

[0039] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0040] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:4 to obtain a standby mixed material;

[0041] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 750°C, and maintain the temperature for 60 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0042] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1100°C for 60 min, and the gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0043] The gallium recovery rate of the gallium-indium alloy obtained in this example relative to the raw material (gallium-based liquid metal waste) was 92.16%, and the indium recovery rate relative to the raw material in the gallium-indium alloy was 93.12%. The mass percentage of gallium + indium in the resulting gallium-indium alloy was approximately 92.37 wt%. The zinc recovery rate and purity were 98.26% and 87.66 wt%, respectively. Tin, which accumulated at the furnace bottom with the carbonaceous reducing agent, had a tin recovery rate and purity of 99.52% and 36.35 wt%, respectively.

[0044] Example 3: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0045] In this embodiment, the contents of gallium, indium, tin, zinc, and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.%, and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is the zero-valent carbon in the mixture of Sn and the carbonaceous reducing agent obtained in Example 2.

[0046] The specific steps are as follows:

[0047] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0048] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0049] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 750°C, and maintain the temperature for 60 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0050] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1100°C for 60 min, and the gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0051] The gallium recovery rate of the gallium-indium alloy obtained in this example relative to the raw material (gallium-based liquid metal waste) was 93.82%, and the indium recovery rate relative to the raw material in the gallium-indium alloy was 94.06% by weight. The mass percentage of gallium + indium in the resulting gallium-indium alloy was approximately 98.88% by weight. The zinc recovery rate and purity were 98.89% and 99.87% by weight, respectively. Tin was further enriched, with the recovery rate and purity increasing to 95.32% and 86.35% by weight.

[0052] Example 4: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0053] In this embodiment, the contents of gallium, indium, tin, zinc, and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.%, and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is the zero-valent carbon in the mixture of Sn and the carbonaceous reducing agent obtained in Example 3.

[0054] The specific steps are as follows:

[0055] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0056] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0057] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 850°C, and maintain the temperature for 120 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0058] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1150°C for 120 min, and the gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0059] In the gallium-indium alloy obtained in this example, the recovery rate of gallium relative to the raw material (gallium-based liquid metal waste) was 95.07%, and the recovery rate of indium in the gallium-indium alloy relative to the raw material was 96.03% by weight. The mass percentage of gallium + indium in the resulting gallium-indium alloy was approximately 99.39% by weight. The recovery rate and purity of zinc were 99.26% and 99.12% by weight, respectively. Tin was further enriched, with the recovery rate and purity increased to 96.32% and 93.35% by weight. The Sn and carbonaceous reducing agent obtained at the furnace bottom can be directly used for tin smelting. Alternatively, it can be used in the vacuum carbothermal reduction method designed for this invention, but this requires the addition of a carbonaceous reducing agent (such as charcoal, coke, or bituminous coal).

[0060] Example 5: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0061] In this embodiment, the contents of gallium, indium, tin, zinc, and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.%, and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is composed of the zero-valent carbon in the mixture of Sn and the carbonaceous reducing agent obtained in Example 4 and additional charcoal, wherein the mixture of Sn and the carbonaceous reducing agent obtained in Example 4 and the additional charcoal are composed of the mixture of Sn and the carbonaceous reducing agent: the additional charcoal in a mass ratio of 1:3.

[0062] The specific steps are as follows:

[0063] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0064] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0065] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 850°C, and maintain the temperature for 150 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0066] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1200°C for 150 min, and a gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0067] In the gallium-indium alloy obtained in this example, the recovery rate of gallium relative to the raw material (gallium-based liquid metal waste) was 96.86%, and the recovery rate of indium in the gallium-indium alloy relative to the raw material was 97.58wt%. The mass percentage of gallium + indium in the resulting gallium-indium alloy was approximately 99.01wt%. The recovery rate and purity of zinc were 99.34% and 99.86wt%, respectively. Tin was further enriched, with the recovery rate and purity increasing to 98.32% and 96.35wt%.

[0068] During the technical development, the present invention discovered for the first time that the residual Sn and carbonaceous reducing agent after the secondary vacuum carbothermal reduction can be used to separate zinc, gallium-indium, and tin after re-dosing. The effect is quite significant and even better than the first use.

[0069] During the technology development process, the following solutions were also tried:

[0070] Comparative Example 1: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0071] In this comparative example, the contents of gallium, indium, tin, zinc and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.% and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is charcoal.

[0072] The specific steps are as follows:

[0073] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0074] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0075] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 600°C, and maintain the temperature for 60 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0076] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 700°C and kept at this temperature for 60 minutes. A gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace. During the secondary vacuum carbothermal reduction, the pressure in the furnace was controlled to be 1-10 Pa.

[0077] The gallium-indium alloy recovered in this comparative example had a recovery rate of 0 and a purity of 0. The zinc recovery rate and purity were 95.37% and 86.28% by weight, respectively, while the gallium, indium, and tin were almost entirely concentrated at the furnace bottom with the carbonaceous reducing agent. This method failed to achieve truly efficient separation and recovery of zinc, gallium-indium, and tin.

[0078] Comparative Example 2: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0079] In this comparative example, the contents of gallium, indium, tin, zinc and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.% and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is charcoal.

[0080] The specific steps are as follows:

[0081] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0082] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0083] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 300°C, and maintain the temperature for 60 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0084] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1050°C for 60 min, and the gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0085] The recovery rate and purity of zinc obtained in this comparative example were 10.23% and 90.26 wt %, respectively. A large amount of zinc was present in the gallium-indium alloy product.

[0086] Comparative Example 3: A method for recovering metallic gallium and indium from gallium-based liquid metal waste.

[0087] In this comparative example, the contents of gallium, indium, tin, zinc and oxygen in the gallium-based liquid metal waste are 60.23 wt.%, 11.98 wt.%, 10.16 wt.%, 3.24 wt.% and 14.39 wt.%, respectively; and the carbonaceous reducing agent used is charcoal.

[0088] The specific steps are as follows:

[0089] (1) Gallium-based liquid metal waste is oxidized and roasted at 800°C to obtain a roasted product; the roasted product is crushed and ground to a particle size of 120 mesh;

[0090] (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2 to obtain a standby mixed material;

[0091] (3) Place the crucible prepared in step (2) into a vertical vacuum furnace, evacuate the air in the furnace to 1-10 Pa, raise the temperature to 900°C, and maintain the temperature for 150 minutes. Collect the Zn-enriched product in a condensation tray. Collect the Zn-free residue at the bottom of the furnace.

[0092] (4) The Zn-removed residue in step (3) was subjected to a secondary vacuum carbothermal reduction at 1200°C for 150 min, and a gallium-indium alloy product was collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent was obtained at the bottom of the furnace; during the secondary vacuum carbothermal reduction, the gas pressure in the furnace was controlled to be 1-10 Pa;

[0093] In the gallium-indium alloy obtained in this comparative example, the recovery rate of gallium relative to the raw material (gallium-based liquid metal waste) was 96.79%, and the recovery rate of indium in the gallium-indium alloy relative to the raw material was 96.83wt%. The mass percentage of gallium + indium in the resulting gallium-indium alloy was approximately 86.61wt%. (At this point, the recovery rates of gallium and indium would decrease, as would the purity of zinc.) The recovery rate and purity of zinc were 99.21% and 92.37%, respectively. Tin, which accumulated at the furnace bottom with the carbonaceous reducing agent, had a recovery rate and purity of 98.29% and 66.37%, respectively.

Claims

1. A method for recovering metallic gallium and indium from gallium-based liquid metal waste, characterized in that: The steps include: (1) Gallium-based liquid metal waste is oxidized and roasted at 600-900° C. to obtain a roasted product; the roasted product is crushed and ground to a particle size of 60-200 mesh; the gallium-based liquid metal waste contains indium and gallium; (2) The calcined product obtained in step (1) is mixed evenly with a carbonaceous reducing agent in a mass ratio of calcined product:carbonaceous reducing agent=1:2-6 to obtain a standby mixed material; (3) The standby mixture obtained in step (2) is placed in a vertical vacuum furnace, the air in the furnace is evacuated to 1-10 Pa, the temperature is raised to 500-850°C, and the temperature is kept constant for 30-240 min. The Zn-enriched product is collected in a condensation tray, and the Zn-free residue is collected at the bottom of the furnace; (4) The Zn-removed residue in step (3) is subjected to a secondary vacuum carbon thermal reduction at 1050-1250°C and constant temperature treatment for 30-240 minutes. The gallium-indium alloy product is collected in a condensation tray, and a mixture of Sn and a carbonaceous reducing agent is obtained at the bottom of the furnace. During the secondary vacuum carbon thermal reduction, the gas pressure in the furnace is controlled to be 1-10 Pa.

2. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: The mixture of Sn and carbonaceous reducing agent obtained in step (4) is returned to step 2 for recycling.

3. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: The roasting is atmospheric pressure oxidation roasting.

4. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: The mass ratio of the calcined product to the carbonaceous reducing agent is 1:2-4.

5.

5. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: The contents of gallium, indium, tin, zinc and oxygen in gallium-based liquid metal waste are 57.84~66.99wt.%, 11.90~13.95wt.%, 9.56~11.42wt.%, 1.86~6.23wt.% and 1.41~18.84wt.%, respectively.

6. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: The carbonaceous reducing agent is selected from at least one of charcoal, petroleum coke, bituminous coal and activated carbon.

7. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: In the gallium-indium alloy, the recovery rates of gallium and indium relative to the corresponding gallium and indium in the raw material gallium-based liquid metal waste are both above 90%. In the obtained gallium-indium alloy, excluding gallium and indium, the content of other elements is less than or equal to 5wt%.

8. The method for recovering metallic gallium and indium from gallium-based liquid metal waste according to claim 1, characterized in that: After the mixture of Sn and carbonaceous reducing agent is recycled, the recovery rate of Sn can reach more than 95%. In the Sn enriched product obtained after decarburization treatment, the content of other elements except Sn is less than or equal to 5%.

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