Method for efficiently recovering metal gallium from red mud
By combining mechanical activation and segmented leaching with composite extraction-ion exchange technology, the problems of low leaching rate, high cost, and poor environmental performance in gallium extraction from red mud have been solved, achieving efficient and low-cost gallium recovery and red mud resource utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-25
- Publication Date
- 2026-03-27
AI Technical Summary
Existing red mud gallium extraction technologies suffer from low leaching rates, high costs, poor environmental performance, and weak adaptability, making it difficult to achieve large-scale industrial applications.
Mechanical activation pretreatment is used to enhance the gallium occurrence state in red mud. Combined with segmented leaching and composite extraction-ion exchange synergistic separation technology, gallium is efficiently recovered through segmented leaching with grinding aids, dilute sulfuric acid, and mixed alkaline solutions, along with composite extractants and ion exchange resins.
It improves gallium leaching rate and purity, reduces production costs, reduces waste emissions, is highly adaptable, applicable to red mud of different sources and compositions, and has the potential for large-scale industrial application.
Abstract
Description
Technical Field
[0001] This invention belongs to the field of industrial waste resource utilization and non-ferrous metal extraction technology, specifically relating to a method for efficiently recovering metallic gallium from red mud, a waste product of alumina production. Background Technology
[0002] Gallium, as an important rare and dispersed metal, is widely used in high-tech fields such as semiconductors, optoelectronic materials, and new energy batteries. With the rapid development of the global electronics and information industry, the market demand for gallium resources continues to rise. Red mud is a solid waste generated during the alkaline process of smelting alumina from bauxite. Approximately 0.8-1.5 tons of red mud are produced for every ton of alumina produced. my country discharges over ten million tons of red mud annually. Long-term stockpiling not only occupies a large amount of land but also causes environmental problems such as soil and water pollution due to the alkali metals and heavy metals it contains.
[0003] Red mud contains a certain amount of gallium resources, typically ranging from 10-100 g / t, which are valuable for recycling. Recovering gallium resources from red mud can alleviate the tight supply of gallium resources, realize the resource utilization of red mud, and reduce environmental pressure. Currently, domestic and international technologies for gallium extraction from red mud mainly focus on three core stages: leaching, separation, and enrichment. Commonly used processes include acid leaching, alkaline leaching, solvent extraction, and ion exchange.
[0004] Existing technologies have several shortcomings: First, acid leaching requires large amounts of strong acid, resulting in high leaching costs and difficult-to-treat acidic wastewater, which is environmentally unfriendly. Alkaline leaching easily leads to the dissolution of large amounts of impurities such as aluminum, increasing the difficulty of subsequent separation. Second, a single leaching process is insufficient for efficient gallium leaching, especially for red mud with complex gallium occurrence states, where the leaching rate is generally below 85%. Third, the extractants used in the separation and enrichment process are expensive, or the ion exchange resins have limited adsorption capacity and are difficult to regenerate, resulting in poor process economics. Fourth, existing processes have poor adaptability to red mud with different compositions, making large-scale industrial application difficult.
[0005] Therefore, developing a method for gallium extraction from red mud that has a high leaching rate, low cost, good environmental performance, and strong adaptability has become an urgent technical problem to be solved in this field. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of existing red mud gallium extraction processes, such as low leaching rate, high cost, poor environmental performance, and weak adaptability, and to provide a highly efficient and environmentally friendly method for gallium extraction from red mud. This method enhances the gallium occurrence state in red mud through mechanical activation pretreatment, controls impurity dissolution through segmented leaching, and employs a composite extraction-ion exchange synergistic separation technology to improve gallium recovery rate and purity, achieving the dual goals of red mud resource utilization and efficient gallium recovery.
[0007] To achieve the above objectives, the present invention adopts the following technical solution:
[0008] A highly efficient and environmentally friendly method for gallium extraction from red mud includes the following steps:
[0009] (1) Red mud pretreatment: Dry the red mud to a moisture content of ≤5%, crush it and pass it through a 200-mesh sieve to obtain red mud fine powder; send the red mud fine powder into a mechanical activation device, add grinding aid accounting for 5-8% of the red mud fine powder mass, and activate it for 30-60 minutes at a speed of 300-500 r / min to obtain activated red mud; the grinding aid is a mixture of citric acid and sodium sulfate, with a mass ratio of 3:2.
[0010] (2) Segmented leaching:
[0011] First leaching: Activated red mud is mixed with dilute sulfuric acid solution at a liquid-to-solid ratio of 4-6:1. Calcium fluoride, accounting for 2-3% of the activated red mud mass, is added as a leaching aid. Leaching is carried out at 60-80℃ and a stirring speed of 200-300 r / min for 40-60 min. The mixture is then filtered to obtain primary leaching residue and primary leachate. The concentration of the dilute sulfuric acid solution is 1.5-2.5 mol / L. Second leaching: A sodium hydroxide-sodium carbonate mixed alkaline solution is added to the primary leaching residue at a liquid-to-solid ratio of 5-7:1. Leaching is carried out at 90-110℃ and a stirring speed of 250-350 r / min for 60-90 min. The mixture is then filtered to obtain secondary leaching residue and secondary leachate. The concentration of sodium hydroxide in the mixed alkaline solution is 1.0-1.5 mol / L, and the concentration of sodium carbonate is 0.5-0.8 mol / L. The primary and secondary leachates are combined to obtain a mixed leachate.
[0012] (3) Leachate pretreatment:
[0013] Add lime milk to the mixed leachate to adjust the pH to 4.5-5.5, let it stand for 20-30 minutes, and filter to remove precipitates such as ferric hydroxide and aluminum hydroxide; add 0.3-0.5 g / L of activated carbon to the filtered solution, stir and adsorb for 15-20 minutes, and filter to obtain the purified leachate.
[0014] (4) Synergistic separation and enrichment: Composite extraction: The purified leachate is sent to the extraction tower, and a composite extractant is added for countercurrent extraction. The extraction ratio O / A = 1:3-1:5, the extraction temperature is 30-40℃, and the extraction time is 20-30 min, to obtain the loaded organic phase and raffinate; the composite extractant is composed of di(2-ethylhexyl)phosphoric acid (P2O4), trioctylphosphine oxide (TOPO), and kerosene, with a volume ratio of 5:2:93; Back-extraction: Hydrochloric acid solution is added to the loaded organic phase as a back-extraction agent, and the back-extraction ratio O / A = 1:3-1:5, the extraction temperature is 30-40℃, and the extraction time is 20-30 min, to obtain the loaded organic phase and the raffinate. The ratio of A to G is 2:1-3:1, the back-extraction temperature is 40-50℃, the back-extraction time is 15-25 min, and the back-extraction solution is obtained by filtration; the concentration of the hydrochloric acid solution is 1.0-1.5 mol / L; deep purification by ion exchange: the back-extraction solution is sent into an ion exchange column and adsorbed using D418 chelating resin at an adsorption flow rate of 1-2 BV / h. Adsorption is stopped when the gallium concentration in the effluent is ≥0.01 g / L; elution is performed with sulfuric acid solution at an elution flow rate of 0.5-1 BV / h, and the eluent is collected to obtain a high-purity gallium enrichment solution.
[0015] (5) Gallium preparation: Adjust the pH of the high-purity gallium enrichment solution to 7.0-7.5, add excess oxalic acid solution, stir and react for 30-40 min to generate gallium oxalate precipitate; filter and collect gallium oxalate precipitate, calcine at 500-600℃ for 2-3 h to obtain gallium oxide; mix gallium oxide with excess carbon powder, reduce at 1200-1300℃ for 3-4 h, and cool to obtain crude gallium; purify crude gallium by electrolytic refining to obtain refined gallium with a purity ≥99.99%.
[0016] Further, the mechanical activation device mentioned in step (1) is a planetary ball mill with a ball-to-material ratio of 10:1-15:1.
[0017] Further, in step (2), the concentration of the dilute sulfuric acid solution in the first leaching stage is preferably 2.0 mol / L, the liquid-to-solid ratio is preferably 5:1, the leaching temperature is preferably 70℃, and the leaching time is preferably 50 min; in the mixed alkaline solution in the second leaching stage, the concentration of sodium hydroxide is preferably 1.2 mol / L, the concentration of sodium carbonate is preferably 0.6 mol / L, the liquid-to-solid ratio is preferably 6:1, the leaching temperature is preferably 100℃, and the leaching time is preferably 75 min.
[0018] Further, in step (4), the O / A ratio of the composite extraction is preferably 1:4, and the extraction temperature is preferably 35℃; the O / A ratio of the back-extraction is preferably 2.5:1, and the back-extraction temperature is preferably 45℃; the ion exchange adsorption flow rate is preferably 1.5 BV / h, and the elution flow rate is preferably 0.8 BV / h.
[0019] Further, in step (5), the concentration of the oxalic acid solution is 0.8-1.2 mol / L, the volume ratio of the oxalic acid solution to the high-purity gallium enrichment solution is 1:3-1:5; the calcination temperature is preferably 550℃, the calcination time is preferably 2.5h; the reduction temperature is preferably 1250℃, and the reduction time is preferably 3.5h.
[0020] The beneficial effects of this invention are as follows:
[0021] 1) The present invention adopts mechanical activation pretreatment, which destroys the mineral lattice structure in red mud through the synergistic effect of grinding aid and mechanical force, increases the specific surface area and reactivity of red mud, and makes gallium easier to release from the mineral phase, laying the foundation for subsequent leaching. Compared with the unactivated treatment, the gallium leaching rate can be increased by 10-15%.
[0022] 2) An acid-alkali staged leaching process is adopted. The first stage of dilute sulfuric acid leaching can efficiently dissolve most of the gallium in the red mud, and calcium fluoride leaching aid can further promote the dissolution of gallium. The second stage of mixed alkali leaching can recover the gallium remaining in the primary leaching residue. At the same time, the addition of sodium carbonate can inhibit the dissolution of impurities such as aluminum and improve the purity of the leaching solution. After the two stages of leaching, the total gallium leaching rate can reach more than 95%.
[0023] 3) The composite extraction-ion exchange synergistic separation technology is adopted. In the composite extractant, P2O4 and TOPO work together to improve the selective extraction capability of gallium and reduce the co-extraction rate of impurities. Subsequent ion exchange deep purification can further remove trace impurities, ensuring that the purity of the final product is ≥99.99%. Compared with the single separation process, the gallium recovery rate can be improved by 5-8%.
[0024] 4) The amount of dilute sulfuric acid and mixed alkaline solution used in the process of this invention is reduced by 30-40% compared with the traditional process. The amount of grinding aid and extractant used is small and can be partially recycled and reused, which reduces the production cost. The leachate can be recycled after pretreatment, and the waste residue generated can be used to prepare building materials, achieving zero waste discharge and good environmental protection.
[0025] 5) By adjusting parameters such as leachate concentration, liquid-solid ratio, and extraction conditions, this invention can adapt to red mud of different sources and compositions, exhibiting wide adaptability and facilitating large-scale industrial application. Detailed Implementation
[0026] The present invention will be further described in detail below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.
[0027] Example 1
[0028] A method for efficiently recovering metallic gallium from red mud includes the following steps:
[0029] 1) Red mud pretreatment: Red mud from an alumina plant was dried to a moisture content of 3%, crushed, and passed through a 200-mesh sieve to obtain fine red mud powder; the fine red mud powder was fed into a planetary ball mill, and a grinding aid (citric acid to sodium sulfate mass ratio of 3:2) accounting for 6% of the mass of the fine red mud powder was added, with a ball-to-material ratio of 12:1, and activated for 45 minutes at a speed of 400 r / min to obtain activated red mud.
[0030] 2) Segmented leaching: ① First stage leaching: Activated red mud is mixed with 2.0 mol / L dilute sulfuric acid solution at a liquid-to-solid ratio of 5:1. Calcium fluoride at a mass of 2.5% of the activated red mud is added. Leaching is carried out at 70℃ and a stirring speed of 250 r / min for 50 min. The residue and leachate are obtained by filtration. ② Second stage leaching: A mixed alkaline solution (sodium hydroxide concentration 1.2 mol / L, sodium carbonate concentration 0.6 mol / L) is added to the residue of the first stage leaching. The mixture is carried out at a liquid-to-solid ratio of 6:1. Leaching is carried out at 100℃ and a stirring speed of 300 r / min for 75 min. The residue and leachate are obtained by filtration. The first and second leachates are combined to obtain a mixed leachate.
[0031] 3) Leachate pretreatment: Add lime milk to the mixed leachate to adjust the pH to 5.0, let stand for 25 min, filter to remove precipitate; add 0.4 g / L activated carbon to the filtered solution, stir to adsorb for 18 min, and filter to obtain purified leachate.
[0032] 4) Synergistic Separation and Enrichment: ① Composite Extraction: The purified leachate is fed into an extraction tower, and a composite extractant (P204:TOPO:kerosene = 5:2:93, volume ratio) is added for countercurrent extraction. The extraction ratio O / A = 1:4, the extraction temperature is 35℃, and the extraction time is 25 min, yielding a loaded organic phase and raffinate; ② Back Extraction: 1.2 mol / L hydrochloric acid solution is added to the loaded organic phase as a back extractant. The back extraction ratio O / A = 2.5:1, the back extraction temperature is 45℃, and the back extraction time is 20 min. The back extract is then filtered to obtain the back extract; ③ Deep Purification by Ion Exchange: The back extract is fed into an ion exchange column and adsorbed using D418 chelating resin at a flow rate of 1.5 BV / h. Adsorption is stopped when the gallium concentration in the effluent is ≥0.01 g / L. Elution is performed with 1.0 mol / L sulfuric acid solution at a flow rate of 0.8 BV / h. The eluent is collected to obtain a high-purity gallium enriched solution.
[0033] 5) Gallium Preparation: The pH of the high-purity gallium enrichment solution was adjusted to 7.2, and a 1.0 mol / L oxalic acid solution (volume ratio of oxalic acid solution to high-purity gallium enrichment solution 1:4) was added. The mixture was stirred for 35 min to generate gallium oxalate precipitate. The gallium oxalate precipitate was collected by filtration and calcined at 550℃ for 2.5 h to obtain gallium oxide. The gallium oxide was mixed with excess carbon powder and reduced at 1250℃ for 3.5 h. After cooling, crude gallium was obtained. The crude gallium was purified by electrolytic refining to obtain refined gallium with a purity of 99.992%. The total gallium leaching rate in this embodiment was 95.8%, and the total recovery rate was 92.3%.
[0034] Example 2
[0035] A method for efficiently recovering metallic gallium from red mud includes the following steps:
[0036] 1) Red mud pretreatment: Red mud from an alumina plant was dried to a moisture content of 4%, crushed, and passed through a 200-mesh sieve to obtain fine red mud powder; the fine red mud powder was fed into a planetary ball mill, and a grinding aid (citric acid to sodium sulfate mass ratio of 3:2) accounting for 5% of the mass of the fine red mud powder was added, with a ball-to-material ratio of 10:1, and activated for 60 minutes at a speed of 300 r / min to obtain activated red mud.
[0037] 2) Segmented leaching: ① First stage leaching: Activated red mud is mixed with 1.5 mol / L dilute sulfuric acid solution at a liquid-to-solid ratio of 4:1. Calcium fluoride at 2% of the mass of the activated red mud is added. The mixture is leached for 60 min at 60℃ and a stirring speed of 200 r / min. The residue and leachate are obtained by filtration. ② Second stage leaching: A mixed alkaline solution (sodium hydroxide concentration 1.0 mol / L, sodium carbonate concentration 0.5 mol / L) is added to the residue from the first stage leaching. The mixture is leached at a liquid-to-solid ratio of 5:1 at 90℃ and a stirring speed of 250 r / min for 90 min. The residue and leachate are obtained by filtration. The first and second leachates are combined to obtain a mixed leachate.
[0038] 3) Leachate pretreatment: Add lime milk to the mixed leachate to adjust the pH to 4.5, let stand for 20 min, filter to remove precipitate; add 0.3 g / L activated carbon to the filtered solution, stir to adsorb for 15 min, and filter to obtain purified leachate.
[0039] 4) Synergistic Separation and Enrichment: ① Composite Extraction: The purified leachate is fed into an extraction tower, and a composite extractant (P204:TOPO:kerosene = 5:2:93, volume ratio) is added for countercurrent extraction. The extraction ratio O / A = 1:3, the extraction temperature is 30℃, and the extraction time is 30 min, yielding a loaded organic phase and raffinate; ② Back Extraction: 1.0 mol / L hydrochloric acid solution is added to the loaded organic phase as a back extractant. The back extraction ratio O / A = 2:1, the back extraction temperature is 40℃, and the back extraction time is 25 min. The back extract is then filtered to obtain the back extract; ③ Deep Purification by Ion Exchange: The back extract is fed into an ion exchange column and adsorbed using D418 chelating resin at a flow rate of 1 BV / h. Adsorption is stopped when the gallium concentration in the effluent is ≥0.01 g / L. Elution is performed with 0.8 mol / L sulfuric acid solution at a flow rate of 0.5 BV / h. The eluent is collected to obtain a high-purity gallium enriched solution.
[0040] 5) Gallium Preparation: The pH of the high-purity gallium enrichment solution was adjusted to 7.0, and a 0.8 mol / L oxalic acid solution (volume ratio of oxalic acid solution to high-purity gallium enrichment solution 1:3) was added. The mixture was stirred for 30 min to generate gallium oxalate precipitate. The gallium oxalate precipitate was collected by filtration and calcined at 500℃ for 3 h to obtain gallium oxide. The gallium oxide was mixed with excess carbon powder and reduced at 1200℃ for 4 h. After cooling, crude gallium was obtained. The crude gallium was purified by electrolytic refining to obtain refined gallium with a purity of 99.990%. The total gallium leaching rate in this embodiment was 95.1%, and the total recovery rate was 91.5%.
[0041] Example 3
[0042] A method for efficiently recovering metallic gallium from red mud includes the following steps:
[0043] 1) Red mud pretreatment: Red mud from an alumina plant was dried to a moisture content of 2%, crushed, and passed through a 200-mesh sieve to obtain fine red mud powder; the fine red mud powder was fed into a planetary ball mill, and grinding aid (citric acid to sodium sulfate mass ratio 3:2) accounting for 8% of the mass of the fine red mud powder was added, with a ball-to-material ratio of 15:1, and activated for 30 minutes at a speed of 500 r / min to obtain activated red mud.
[0044] 2) Segmented leaching: ① First stage leaching: Activated red mud is mixed with 2.5 mol / L dilute sulfuric acid solution at a liquid-to-solid ratio of 6:1. Calcium fluoride at 3% of the activated red mud mass is added. Leaching is carried out at 80℃ and a stirring speed of 300 r / min for 40 min. The residue and leachate are obtained by filtration. ② Second stage leaching: A mixed alkaline solution (sodium hydroxide concentration 1.5 mol / L, sodium carbonate concentration 0.8 mol / L) is added to the residue of the first stage leaching. The mixture is carried out at a liquid-to-solid ratio of 7:1. Leaching is carried out at 110℃ and a stirring speed of 350 r / min for 60 min. The residue and leachate are obtained by filtration. The first and second leachates are combined to obtain a mixed leachate.
[0045] 3) Leachate pretreatment: Add lime milk to the mixed leachate to adjust the pH to 5.5, let stand for 30 min, filter to remove precipitate; add 0.5 g / L activated carbon to the filtered solution, stir to adsorb for 20 min, and filter to obtain purified leachate.
[0046] 4) Co-extraction and enrichment: ① Composite extraction: The purified leachate is fed into an extraction tower, and a composite extractant (P204:TOPO:kerosene = 5:2:93, volume ratio) is added for countercurrent extraction. The extraction ratio O / A = 1:5, the extraction temperature is 40℃, and the extraction time is 20 min, yielding a loaded organic phase and raffinate; ② Back-extraction: 1.5 mol / L hydrochloric acid solution is added to the loaded organic phase as a back-extraction agent. The back-extraction ratio O / A = 3:1, the back-extraction temperature is 50℃, and the back-extraction time is 15 min. The back-extraction solution is filtered to obtain the back-extraction solution; ③ Deep purification by ion exchange: The back-extraction solution is fed into an ion exchange column and adsorbed using D418 chelating resin at a flow rate of 2 BV / h. Adsorption is stopped when the gallium concentration in the effluent is ≥0.01 g / L; elution is performed with 1.2 mol / L sulfuric acid solution at a flow rate of 1 BV / h. The eluent is collected to obtain a high-purity gallium enriched solution.
[0047] 5) Gallium Preparation: The pH of the high-purity gallium enrichment solution was adjusted to 7.5, and a 1.2 mol / L oxalic acid solution (oxalic acid solution to high-purity gallium enrichment solution volume ratio 1:5) was added. The mixture was stirred for 40 min to generate gallium oxalate precipitate. The gallium oxalate precipitate was collected by filtration and calcined at 600℃ for 2 h to obtain gallium oxide. The gallium oxide was mixed with excess carbon powder and reduced at 1300℃ for 3 h. After cooling, crude gallium was obtained. The crude gallium was purified by electrolytic refining to obtain refined gallium with a purity of 99.993%. The total gallium leaching rate in this example was 96.2%, and the total recovery rate was 92.8%.
[0048] Comparative experiment: The red mud in Example 1 above was treated using the traditional sulfuric acid direct leaching-single P204 extraction process. The gallium leaching rate was 82.3%, the total recovery rate was 85.1%, and the product purity was 99.95%. Compared with Example 1 of the present invention, the leaching rate decreased by 13.5%, the recovery rate decreased by 7.2%, the purity decreased by 0.042%, and the acid consumption increased by 35%, and the amount of acidic wastewater generated increased by 40%.
[0049] As can be seen from the above embodiments and comparative experiments, the method of the present invention can significantly improve the leaching rate and recovery rate of gallium in red mud, improve product purity, and at the same time reduce reagent consumption and pollutant emissions, thus having good economic and environmental benefits.
Claims
1. A method for efficiently recovering metallic gallium from red mud, characterized in that, Includes the following steps: (1) Red mud pretreatment: Dry the red mud to a moisture content of ≤5%, crush it and pass it through a 200-mesh sieve to obtain red mud fine powder; send the red mud fine powder into a mechanical activation device, add a grinding aid accounting for 5-8wt% of the red mud fine powder, and activate it for 30-60min at a speed of 300-500r / min to obtain activated red mud; the grinding aid is a mixture of citric acid and sodium sulfate, with a mass ratio of 3:2; (2) Segmented leaching: ① First stage leaching: Activated red mud and dilute sulfuric acid solution are mixed at a liquid-solid ratio of 4-6:
1. Calcium fluoride, accounting for 2-3% of the mass of activated red mud, is added as a leaching aid. Leaching is carried out at a temperature of 60-80℃ and a stirring speed of 200-300 r / min for 40-60 min. The mixture is then filtered to obtain primary leaching residue and primary leaching solution. The concentration of the dilute sulfuric acid solution is 1.5-2.5 mol / L. ② Second stage leaching: A sodium hydroxide-sodium carbonate mixed alkaline solution is added to the primary leaching residue and mixed at a liquid-solid ratio of 5-7:
1. Leaching is carried out at a temperature of 90-110℃ and a stirring speed of 250-350 r / min for 60-90 min. The mixture is then filtered to obtain secondary leaching residue and secondary leaching solution. The concentration of sodium hydroxide in the mixed alkaline solution is 1.0-1.5 mol / L, and the concentration of sodium carbonate is 0.5-0.8 mol / L. The primary and secondary leaching solutions are combined to obtain a mixed leaching solution. (3) Leachate pretreatment: Add lime milk to the mixed leachate to adjust the pH value to 4.5-5.5, let it stand for 20-30 minutes, filter to remove the precipitate; add 0.3-0.5 g / L of activated carbon to the filtered solution, stir to adsorb for 15-20 minutes, and filter to obtain purified leachate; (4) Synergistic separation and enrichment: ① Composite extraction: The purified leachate is sent to the extraction tower, and a composite extractant is added for countercurrent extraction. The extraction ratio O / A = 1:3-1:5, the extraction temperature is 30-40℃, and the extraction time is 20-30min to obtain the loaded organic phase and the raffinate; ② Back-extraction: Hydrochloric acid solution is added to the loaded organic phase as the back-extraction agent. The back-extraction ratio O / A = 2:1-3:1, the back-extraction temperature is 40-50℃, and the back-extraction time is 15-25min. The back-extraction solution is filtered to obtain the back-extraction solution. The concentration of the hydrochloric acid solution is 1.0-1.5mol / L; ③ Ion exchange deep purification: The back-extraction solution is sent to the ion exchange column and adsorbed using D418 chelating resin. The adsorption flow rate is 1-2 BV / h. When the gallium concentration in the effluent is ≥0.01g / L, the adsorption is stopped. The solution is eluted with sulfuric acid solution at a flow rate of 0.5-1 BV / h. The eluent is collected to obtain a high-purity gallium enrichment solution. (5) Gallium preparation: Adjust the pH of the high-purity gallium enrichment solution to 7.0-7.5, add oxalic acid solution, stir and react for 30-40 min to generate gallium oxalate precipitate; Gallium oxalate precipitate was collected by filtration and calcined at 500-600℃ for 2-3 hours to obtain gallium oxide. Gallium oxide was mixed with excess carbon powder and reduced at 1200-1300℃ for 3-4 hours. After cooling, crude gallium was obtained. The crude gallium was purified by electrolytic refining to obtain refined gallium with a purity ≥99.99%.
2. The method for efficiently recovering metallic gallium from red mud according to claim 1, characterized in that, The mechanical activation device mentioned in step (1) is a planetary ball mill with a ball-to-material ratio of 10:1-15:
1.
3. The method for efficiently recovering metallic gallium from red mud according to claim 1, characterized in that, In step (2), the concentration of the dilute sulfuric acid solution in the first leaching stage is 2.0 mol / L, the liquid-to-solid ratio is 5:1, the leaching temperature is 70℃, and the leaching time is 50 min; in the second leaching stage, the concentration of sodium hydroxide in the mixed alkaline solution is 1.2 mol / L, the concentration of sodium carbonate is 0.6 mol / L, the liquid-to-solid ratio is 6:1, the leaching temperature is 100℃, and the leaching time is 75 min.
4. The method for efficiently recovering metallic gallium from red mud according to claim 1, characterized in that, The composite extractant in step (4) consists of di(2-ethylhexyl)phosphoric acid, abbreviated as P204, trioctylphosphine oxide, abbreviated as TOPO, and kerosene, with a volume ratio of 5:2:
93.
5. The method for efficiently recovering metallic gallium from red mud according to claim 1, characterized in that, In step (4), the extraction ratio of the composite extraction is 1:4 (O / A) and the extraction temperature is 35℃; the extraction ratio of the back-extraction is 2.5:1 (O / A) and the back-extraction temperature is 45℃; the ion exchange adsorption flow rate is 1.5 BV / h and the elution flow rate is 0.8 BV / h.
6. The method for efficiently recovering metallic gallium from red mud according to claim 1, characterized in that, In step (5), the concentration of oxalic acid solution is 0.8-1.2 mol / L, and the volume ratio of oxalic acid solution to high-purity gallium enrichment solution is 1:3-1:
5.
7. The method for efficiently recovering metallic gallium from red mud according to claim 1, characterized in that, In step (5), the calcination temperature is 550℃ and the calcination time is 2.5h; the reduction temperature is 1250℃ and the reduction time is 3.5h.