A method for recovering indium from zinc hydrometallurgy waste residue

Abstract

This invention discloses a method for recovering metallic indium from wet zinc smelting waste. The waste from wet zinc smelting is crushed, then mixed with sulfuric acid solution, stirred, and reacted before filtration to obtain a leachate. The leachate is heated to 40°C–50°C, and the pH is adjusted to 2.0–2.5. Barium sulfide and sorbitol are then slowly added and stirred, followed by filtration to obtain a filtrate. Oxalic acid is added to the filtrate and stirred, followed by extraction with an extractant. The extract phase is then back-extracted with hydrochloric acid solution to obtain a back-extract. The extractant consists of a microencapsulated extractant and kerosene. The back-extract is then replaced with zinc flakes to obtain sponge indium, which is then compressed into briquettes and cast to obtain indium ingots. This invention can reduce the interference of various metal components in the leaching residue on the recovery of metallic indium, improve the recovery efficiency of metallic indium, and obtain indium ingots with high purity and good quality.

Description

Technical Field

[0001] This invention belongs to the field of zinc smelting waste residue recycling technology, specifically relating to a method for recovering metallic indium from wet zinc smelting waste residue. Background Technology

[0002] Hydrometallurgical zinc refining refers to the process of dissolving zinc in calcined ore or other zinc sulfide materials and zinc sulfide concentrate in an aqueous solution to extract metallic zinc or zinc compounds. It is the main method of modern zinc refining. Hydrometallurgical zinc refining mainly includes roasting, leaching, leaching solution purification, and electrowinning. In the leaching process, after the zinc concentrate is roasted, zinc oxide is dissolved by leaching. The resulting slurry is separated into supernatant and underflow slurry. The underflow slurry is then acid-leached again to produce leaching residue. In addition to some zinc, the acidic leaching residue also contains metals such as lead, copper, indium, and germanium. Directly discharging the leaching residue would cause significant environmental pollution, so further treatment of the leaching residue is necessary to recover various metals. However, existing methods, such as rotary kiln volatilization, cannot completely recover all the metals in the leaching residue. Furthermore, due to the complex composition of the leaching residue, the recovery of rare metals such as indium is more difficult, resulting in low recovery efficiency and poor quality of indium, which fails to meet the requirements for effective utilization of waste resources. Summary of the Invention

[0003] To address the aforementioned shortcomings, this invention discloses a method for recovering metallic indium from wet zinc smelting waste residue, reducing the interference of various metal components in the leaching residue on the recovery of metallic indium, improving the recovery efficiency of metallic indium, and obtaining indium ingots with high purity and good quality.

[0004] This invention is achieved using the following technical solution: A method for recovering metallic indium from waste residue in hydrometallurgical zinc smelting includes the following steps: (1) Take the waste residue from wet zinc smelting, crush it, and then mix it with sulfuric acid solution. Stir and react at 40℃~50℃ for 2h~3h. The mass ratio of the waste residue to the sulfuric acid solution is 1:(3~5). Then filter to obtain leachate. (2) Heat the leachate obtained in step (1) to 40℃~50℃, adjust the pH to 2.0~2.5, then slowly add barium sulfide and sorbitol and stir for 1h~2h, then filter to obtain filtrate. The weight ratio of barium sulfide to the volume ratio of filtrate is (60~80) g:1L, and the volume ratio of sorbitol to filtrate is (1~2):100. (3) Add oxalic acid to the filtrate obtained in step (2) and stir for 10 min to 20 min. The molar ratio of oxalic acid to iron in the filtrate is (1 to 1.2):1. Then add the extractant for extraction. The extract phase is back-extracted with hydrochloric acid solution to obtain the back-extract. The extractant is composed of the following components in parts by weight: 20 to 25 parts of microcapsule extractant and 75 to 80 parts of kerosene. The microcapsule extractant is prepared by adding sodium alginate to calcium chloride solution, stirring and mixing at 40°C to 50°C for 40 min to 60 min, and then adding diisooctyl phosphate and stirring and mixing for 30 min to 45 min to obtain the microcapsule extractant. The mass fraction of the calcium chloride solution is 3% to 5%. The weight ratio of sodium alginate to calcium chloride solution is (2 to 3):100. The weight ratio of diisooctyl phosphate to calcium chloride solution is (2 to 5):10. (4) Replace the back-extraction solution obtained in step (3) with zinc sheets to obtain sponge indium, and then press the sponge indium into lumps and melt and cast to obtain indium ingots.

[0005] Furthermore, the mass fraction of the sulfuric acid solution in step (1) is 20% to 30%.

[0006] Furthermore, in step (1), the waste residue from wet zinc smelting is crushed and passed through an 80-120 mesh sieve and then mixed with sulfuric acid solution. The mixture is then stirred and reacted at 40-50°C and a speed of 200-300 r / min. Furthermore, in step (2), barium sulfide is first added and stirred for 30 minutes before sorbitol is added to continue the reaction. First, barium sulfide reacts with metals such as copper and zinc in the leachate to form precipitates. Adding barium sulfide can easily increase the viscosity of the solution, affecting the flocculation and precipitation of sulfides. Therefore, adding an appropriate amount of sorbitol improves the viscosity of the solution and promotes the reaction of barium sulfide with metals such as copper and zinc to form precipitates, thereby achieving the purpose of impurity removal.

[0007] Furthermore, in step (3), oxalic acid is added to the filtrate obtained in step (2) and stirred at 30℃~40℃ for 10min~20min. By controlling a suitable temperature, the reaction between oxalic acid and iron in the solution is promoted, reducing ferric iron to ferrous iron, thus preventing ferric iron from being extracted together with metallic indium by the extractant and affecting the extraction effect of metallic indium.

[0008] Furthermore, in step (3), the concentration of the hydrochloric acid solution is 6 mol / L to 12 mol / L.

[0009] Furthermore, in step (3), the pH of the filtrate is adjusted to 1.5–2.0 before the extractant is added for extraction. Controlling the appropriate pH value is beneficial for promoting the extraction of indium from the solution by the extractant.

[0010] Furthermore, in step (3), the volume ratio of filtrate to extractant is (5-6):1.

[0011] Compared with existing technologies, this technical solution has the following advantages: 1. This invention uses sulfuric acid solution to leach metal elements from the waste residue of wet zinc smelting. Then, barium sulfide and sorbitol are added to the obtained leachate, so that barium sulfide reacts with metal impurities such as copper and zinc in the leachate to form precipitates, thereby achieving the purpose of impurity removal. Only one addition of barium sulfide and sorbitol is needed to remove multiple metal impurities in the leachate, simplifying the impurity removal steps and achieving good impurity removal effect. Then, a certain amount of oxalic acid is added to reduce the ferric iron in the solution, so that the ferric iron is converted into ferrous iron, thereby avoiding the ferric iron being extracted together with metallic indium by the extractant, which would affect the extraction effect of metallic indium.

[0012] 2. This invention employs a microencapsulated extractant. A calcium alginate coating is prepared using sodium alginate and calcium chloride to encapsulate the extractant diisooctyl phosphate, thus obtaining the microencapsulated extractant. This improves the stability of diisooctyl phosphate, enhancing its extraction efficiency for indium. Simultaneously, the microencapsulated extractant with calcium alginate as the coating exhibits a greater swelling ratio in the back-extraction agent (a hydrochloric acid solution with a concentration of 6 mol / L to 12 mol / L), which is beneficial for back-extraction of indium and improves the recovery rate of indium. 3. The process of this invention is simple and highly controllable, making it suitable for automated and large-scale processing and recovery of metallic indium from the waste residue of hydrometallurgical zinc smelting, and obtaining metallic indium products with high purity and good quality. Detailed Implementation

[0013] The present invention is further illustrated by the following examples, but these are not intended to limit the invention. Specific experimental conditions and methods not specified in the following examples are generally conventional methods well known to those skilled in the art.

[0014] Example 1: A method for recovering metallic indium from waste residue in hydrometallurgical zinc smelting, comprising the following steps: (1) The waste residue from wet zinc smelting is crushed and passed through a 100-mesh sieve and mixed with sulfuric acid solution. Then, the mixture is stirred at 42°C and 250 r / min for 2.5 h. The mass ratio of the waste residue to the sulfuric acid solution is 1:3.8. The leachate is then obtained by filtration. The mass fraction of the sulfuric acid solution is 22%. (2) Heat the leachate obtained in step (1) to 44°C, adjust the pH to 2.2, and then slowly add barium sulfide and sorbitol and stir for 1.5 h. First add barium sulfide and stir for 30 min, then add sorbitol and continue the reaction. Then filter to obtain filtrate. The weight ratio of barium sulfide to filtrate is 65 g: 1 L, and the volume ratio of sorbitol to filtrate is 1.5: 100. (3) Add oxalic acid to the filtrate obtained in step (2) and stir at 35°C for 15 min. The molar ratio of oxalic acid to iron in the filtrate is 1.1:1. Then adjust the pH of the filtrate to 1.8 and add the extractant for extraction. The volume ratio of filtrate to extractant is 5.4:1. Back-extract the extract phase with hydrochloric acid solution to obtain the back-extract. The extractant consists of the following components in parts by weight: 23 parts microcapsule extractant and 77 parts kerosene. The microcapsule extractant is prepared by adding sodium alginate to calcium chloride solution, stirring and mixing at 45°C for 50 min, and then adding diisooctyl phosphate and stirring and mixing for 35 min to obtain the microcapsule extractant. The mass fraction of the calcium chloride solution is 4%, the weight ratio of sodium alginate to calcium chloride solution is 2.6:100, and the weight ratio of diisooctyl phosphate to calcium chloride solution is 3:10. The concentration of the hydrochloric acid solution is 8 mol / L. (4) Replace the back-extraction solution obtained in step (3) with zinc sheets to obtain sponge indium, and then press the sponge indium into lumps and melt and cast to obtain indium ingots.

[0015] Example 2: A method for recovering metallic indium from wet zinc smelting waste, comprising the following steps: (1) The waste residue from wet zinc smelting is crushed and passed through an 80-mesh sieve and then mixed with sulfuric acid solution. The mixture is then stirred at 40°C and a speed of 200 r / min for 2 hours. The mass ratio of the waste residue to the sulfuric acid solution is 1:3. The solution is then filtered to obtain a leachate. The mass fraction of the sulfuric acid solution is 20%. (2) Heat the leachate obtained in step (1) to 40°C, adjust the pH to 2.0, and then slowly add barium sulfide and sorbitol and stir for 1 hour. First, add barium sulfide and stir for 30 minutes, then add sorbitol and continue the reaction. Then filter to obtain filtrate. The weight ratio of barium sulfide to filtrate is 60 g: 1 L, and the volume ratio of sorbitol to filtrate is 1: 100. (3) Add oxalic acid to the filtrate obtained in step (2) and stir at 30°C for 10 min. The molar ratio of oxalic acid to iron in the filtrate is 1:1. Then adjust the pH of the filtrate to 1.5 and add the extractant for extraction. The volume ratio of filtrate to extractant is 5:1. Back-extract the extract phase with hydrochloric acid solution to obtain the back-extract. The extractant consists of the following components in parts by weight: 20 parts of microcapsule extractant and 80 parts of kerosene. The microcapsule extractant is prepared by adding sodium alginate to calcium chloride solution, stirring and mixing at 40°C for 40 min, and then adding diisooctyl phosphate and stirring and mixing for 30 min to obtain the microcapsule extractant. The mass fraction of the calcium chloride solution is 3%, the weight ratio of sodium alginate to calcium chloride solution is 2:100, and the weight ratio of diisooctyl phosphate to calcium chloride solution is 2:10. The concentration of the hydrochloric acid solution is 6 mol / L. (4) Replace the back-extraction solution obtained in step (3) with zinc sheets to obtain sponge indium, and then press the sponge indium into lumps and melt and cast to obtain indium ingots.

[0016] Example 3: A method for recovering metallic indium from wet zinc smelting waste, comprising the following steps: (1) The waste residue from wet zinc smelting is crushed and passed through a 100-mesh sieve and mixed with sulfuric acid solution. Then, the mixture is stirred at 48°C and 250 r / min for 2.5 h. The mass ratio of the waste residue to the sulfuric acid solution is 1:4. The solution is then filtered to obtain a leachate. The mass fraction of the sulfuric acid solution is 25%. (2) Heat the leachate obtained in step (1) to 48°C, adjust the pH to 2.3, and then slowly add barium sulfide and sorbitol and stir for 1.5 h. First add barium sulfide and stir for 30 min, then add sorbitol and continue the reaction. Then filter to obtain filtrate. The weight ratio of barium sulfide to filtrate is 75 g: 1 L, and the volume ratio of sorbitol to filtrate is 1.8: 100. (3) Add oxalic acid to the filtrate obtained in step (2) and stir at 38°C for 15 min. The molar ratio of oxalic acid to iron in the filtrate is 1.17:1. Then adjust the pH of the filtrate to 1.7 and add the extractant for extraction. The volume ratio of filtrate to extractant is 5.5:1. Back-extract the extract phase with hydrochloric acid solution to obtain the back-extract. The extractant consists of the following components in parts by weight: 21 parts of microcapsule extractant and 79 parts of kerosene. The microcapsule extractant is prepared by adding sodium alginate to calcium chloride solution, stirring and mixing at 45°C for 45 min, and then adding diisooctyl phosphate and stirring and mixing for 40 min to obtain the microcapsule extractant. The mass fraction of the calcium chloride solution is 4.5%. The weight ratio of sodium alginate to calcium chloride solution is 2.8:100. The weight ratio of diisooctyl phosphate to calcium chloride solution is 4:10. The concentration of the hydrochloric acid solution is 10 mol / L. (4) Replace the back-extraction solution obtained in step (3) with zinc sheets to obtain sponge indium, and then press the sponge indium into lumps and melt and cast to obtain indium ingots.

[0017] Example 4: A method for recovering metallic indium from wet zinc smelting waste, comprising the following steps: (1) The waste residue from wet zinc smelting is crushed and passed through a 120-mesh sieve and mixed with sulfuric acid solution. Then, the mixture is stirred at 50°C and 300 r / min for 3 h. The mass ratio of the waste residue to the sulfuric acid solution is 1:5. The solution is then filtered to obtain a leachate. The mass fraction of the sulfuric acid solution is 30%. (2) Heat the leachate obtained in step (1) to 50°C, adjust the pH to 2.5, and then slowly add barium sulfide and sorbitol and stir for 2 hours. First, add barium sulfide and stir for 30 minutes, then add sorbitol and continue the reaction. Then filter to obtain filtrate. The weight ratio of barium sulfide to the volume ratio of filtrate is 80 g: 1 L, and the volume ratio of sorbitol to filtrate is 2: 100. (3) Add oxalic acid to the filtrate obtained in step (2) and stir at 40°C for 20 min. The molar ratio of oxalic acid to iron in the filtrate is 1.2:1. Then adjust the pH of the filtrate to 2.0 and add the extractant for extraction. The volume ratio of filtrate to extractant is 6:1. Back-extract the extract phase with hydrochloric acid solution to obtain the back-extract. The extractant consists of the following components in parts by weight: 25 parts microcapsule extractant and 75 parts kerosene. The microcapsule extractant is prepared by adding sodium alginate to calcium chloride solution, stirring and mixing at 50°C for 60 min, and then adding diisooctyl phosphate and stirring and mixing for 45 min to obtain the microcapsule extractant. The mass fraction of the calcium chloride solution is 5%. The weight ratio of sodium alginate to calcium chloride solution is 3:100. The weight ratio of diisooctyl phosphate to calcium chloride solution is 5:10. The concentration of the hydrochloric acid solution is 12 mol / L. (4) Replace the back-extraction solution obtained in step (3) with zinc sheets to obtain sponge indium, and then press the sponge indium into lumps and melt and cast to obtain indium ingots.

[0018] Comparative Example 1: The method for recovering metallic indium from wet zinc smelting waste described in this comparative example differs from the method described in Example 1 only in that, in step (2), only barium sulfide is added for treatment, and sorbitol is not added.

[0019] Comparative Example 2: The method for recovering metallic indium from wet zinc smelting waste described in this comparative example differs from the method described in Example 1 only in that, in step (3), the extractant is composed of the following components in parts by weight: 23 parts of diisooctyl phosphate and 77 parts of kerosene.

[0020] Experimental example: The waste residue obtained from the wet zinc smelting process was analyzed for composition (results are shown in Table 1). Then, indium metal was recovered according to the methods described in Examples 1-4 and Comparative Examples 1-2. The recovery rates of indium metal recovered by different methods are shown in Table 2.

[0021] Table 1. Component determination results of some components in the waste residue from hydrometallurgical zinc smelting. Element content 2.21 1237 6.89 6.37 0.22 0.02 Table 2 Recovery rates of indium metal by different methods Indium metal recovery rate (%) 95.4 94.2 94.7 94.1 86.4 91.2 Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for recovering metallic indium from waste residue in hydrometallurgical zinc smelting, characterized in that: Includes the following steps: (1) Take the waste residue from wet zinc smelting, crush it, and then mix it with sulfuric acid solution. Stir and react at 40℃~50℃ for 2h~3h. The mass ratio of the waste residue to the sulfuric acid solution is 1:(3~5). Then filter to obtain leachate. (2) Heat the leachate obtained in step (1) to 40℃~50℃, adjust the pH to 2.0~2.5, then slowly add barium sulfide and sorbitol and stir for 1h~2h, then filter to obtain filtrate. The weight ratio of barium sulfide to the volume ratio of filtrate is (60~80) g:1L, and the volume ratio of sorbitol to filtrate is (1~2):

100. (3) Add oxalic acid to the filtrate obtained in step (2) and stir for 10 min to 20 min. The molar ratio of oxalic acid to iron in the filtrate is (1 to 1.2):

1. Then add the extractant for extraction. The extract phase is back-extracted with hydrochloric acid solution to obtain the back-extract. The extractant is composed of the following components in parts by weight: 20 to 25 parts of microcapsule extractant and 75 to 80 parts of kerosene. The microcapsule extractant is prepared by adding sodium alginate to calcium chloride solution, stirring and mixing at 40°C to 50°C for 40 min to 60 min, and then adding diisooctyl phosphate and stirring and mixing for 30 min to 45 min to obtain the microcapsule extractant. The mass fraction of the calcium chloride solution is 3% to 5%. The weight ratio of sodium alginate to calcium chloride solution is (2 to 3):

100. The weight ratio of diisooctyl phosphate to calcium chloride solution is (2 to 5):

10. (4) Replace the back-extraction solution obtained in step (3) with zinc sheets to obtain sponge indium, and then press the sponge indium into lumps and melt and cast to obtain indium ingots.

2. The method for recovering metallic indium from wet zinc smelting waste according to claim 1, characterized in that: The mass fraction of the sulfuric acid solution in step (1) is 20% to 30%.

3. The method for recovering metallic indium from wet zinc smelting waste according to claim 1, characterized in that: In step (1), the waste residue from wet zinc smelting is crushed and passed through an 80-120 mesh sieve and then mixed with sulfuric acid solution. The mixture is then stirred and reacted at 40-50°C and a speed of 200-300 r / min.

4. The method for recovering metallic indium from wet zinc smelting waste according to claim 1, characterized in that: In step (2), barium sulfide is added and stirred for 30 minutes before sorbitol is added to continue the reaction.

5. The method for recovering metallic indium from wet zinc smelting waste according to claim 1, characterized in that: In step (3), oxalic acid is added to the filtrate obtained in step (2) and stirred at 30℃~40℃ for 10min~20min.

6. The method for recovering metallic indium from wet zinc smelting waste according to claim 1, characterized in that: In step (3), the concentration of the hydrochloric acid solution is 6 mol / L to 12 mol / L.

7. The method for recovering metallic indium from wet zinc smelting waste according to claim 1, characterized in that: In step (3), the pH of the filtrate is adjusted to 1.5-2.0 and then the extractant is added for extraction.

8. The method for recovering metallic indium from hydrometallurgical zinc smelting waste according to claim 1, characterized in that: In step (3), the volume ratio of filtrate to extractant is (5-6):1.