Separation method and application of iron, arsenic and indium

Abstract

The invention belongs to the technical field of hydrometallurgy, and particularly relates to a separation method and application of iron, arsenic and indium. The method for separating iron, arsenic and indium comprises the following steps: mixing a high-iron, high-arsenic and low-indium solution with an extracted organic phase, and extracting under the action of ultrasonic waves to obtain an indium-loaded organic phase and raffinate; carrying out reverse extraction on the indium-loaded organic phase to obtain an indium-containing reverse extraction solution; carrying out acid separation on the indium-containing strip liquor, mixing the indium-containing strip liquor with a reducing agent, reacting, and filtering to obtain an indium-enriched solution; the content of indium in the high-iron high-arsenic low-indium solution is less than 5g / L, and the content of iron and the content of arsenic are both greater than 5g / L; the extraction organic phase comprises an acidic phosphate extraction agent, a neutral phosphate extraction agent and a diluent. According to the method, the indium element is preferentially extracted through ultrasonic-assisted indium extraction in combination with neutral phosphate and acidic phosphate extractants, and meanwhile extraction of iron and arsenic elements is effectively inhibited. By means of the selective step-by-step separation method, effective enrichment of indium, iron and arsenic elements is achieved.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology, and specifically relates to a method and application for separating iron, arsenic and indium. Background Technology

[0002] Metallic indium typically does not exist as an independent deposit, but rather as a by-product in lead and zinc concentrates. Currently, most primary indium is recovered from zinc oxide, a byproduct of lead and zinc smelting. Indium volatilized and enriched in various leaching residues from hydrometallurgical zinc production has become the main raw material for comprehensive indium extraction. Due to the similar chemical properties of indium and iron, iron is always present alongside indium during the recovery process, posing a significant challenge to the enrichment and purification of indium.

[0003] Currently, several studies have been conducted on the separation technology of indium and iron in solution, with separation methods mainly including hydrolysis precipitation, weak acid salt precipitation, displacement deposition, solvent extraction, and ion exchange. However, the removal technology of arsenic from solution has not been sufficiently studied in depth. Furthermore, most research focuses on situations where the indium content in the solution is high, while the contents of iron and arsenic are low, and the solution acidity is not high. However, in actual production processes, the separation of indium, arsenic, and iron often faces the challenges of high acidity, high iron content, high arsenic content, and low indium. Traditional precipitation and solvent extraction methods are not ideal for separating iron and indium when applied to solutions with high acidity, high iron content, and high arsenic content, resulting in indium's inability to effectively aggregate and precipitate, leading to significant indium loss during the precipitation process. Moreover, for solvent extraction, to achieve effective separation of indium and iron, ferric iron must be reduced to ferrous iron, which undoubtedly increases the complexity of the production process and thus raises production costs.

[0004] To further improve the recovery rate and purity of indium, researchers have also developed electrochemical methods and biometallurgical techniques. In the electrochemical process, by applying an electric current, indium ions can be deposited from the solution onto the cathode, while iron ions remain in the solution. This method effectively reduces the co-deposition of impurities, resulting in higher purity indium. Furthermore, electrochemical methods can be carried out at lower temperatures, helping to reduce energy consumption and operating costs. However, electrochemical methods still have the following problems: difficulty in separating impurity metals, high process complexity; high energy and material consumption, limiting its large-scale application; and limited adaptability to low-concentration indium solutions, with efficiency degradation at extreme concentrations for dilute solutions containing <300 mg / L of indium. In biometallurgical techniques, certain microorganisms can selectively adsorb or enrich indium, thereby achieving the separation of indium from iron. This method has the advantages of being environmentally friendly and low-cost, but it is currently still in the laboratory research stage and has not yet been widely applied to industrial production.

[0005] Therefore, it is of great significance to provide a method that can effectively separate indium, iron, and arsenic elements in solutions with high iron, high arsenic, and low indium. Summary of the Invention

[0006] The present invention aims to solve one or more technical problems existing in the prior art, and at least provide a beneficial alternative. Specifically, the present invention provides a method for separating indium, iron, and arsenic, which overcomes the problem of separating high-concentration iron and arsenic from low-concentration indium in traditional methods. It preferentially extracts indium while effectively inhibiting the extraction of iron and arsenic. Through this selective stepwise separation method, the effective enrichment of indium, iron, and arsenic is achieved, promoting the resource utilization of these elements.

[0007] The inventive concept of this invention is as follows: The method for separating iron, arsenic, and indium in this invention involves first mixing a high-iron, high-arsenic, and low-indium solution with an extractable organic phase, and then extracting the solution under ultrasonic action to obtain an indium-loaded organic phase and a raffinate; then, the indium-loaded organic phase is back-extracted to obtain an indium-containing back-extract; the indium-containing back-extract is separated by acid, mixed with a reducing agent, reacted, and filtered to obtain an indium-enriched solution; the indium content in the high-iron, high-arsenic, and low-indium solution is less than 5 g / L, the iron content is greater than 5 g / L, and the arsenic content is greater than 5 g / L; the extractable organic phase includes an acidic phosphate extractant, a neutral phosphate extractant, and a diluent.

[0008] This invention addresses the selective stepwise separation of indium, iron, and arsenic in highly acidic solutions containing high concentrations of arsenic and iron. Utilizing an ultrasonic field-assisted process, it combines neutral and acidic phosphate extractants to preferentially extract indium while effectively inhibiting the extraction of iron and arsenic. This process successfully overcomes the challenge of separating high-concentration iron and arsenic from indium using traditional methods, achieving effective enrichment of these three elements through selective stepwise separation.

[0009] Therefore, a first aspect of the present invention provides a method for separating iron, arsenic and indium.

[0010] Specifically, the method for separating iron, arsenic, and indium includes the following steps:

[0011] (1) Mix the high-iron, high-arsenic, and low-indium solution with the extractable organic phase, and extract under ultrasonic action to obtain an indium-loaded organic phase and raffinate.

[0012] (2) The indium-loaded organic phase obtained in step (1) is back-extracted to obtain an indium-containing back-extracting solution; the indium-containing back-extracting solution is separated by acid, mixed with a reducing agent, reacted, filtered, and an indium-enriched solution is obtained.

[0013] The high-iron, high-arsenic, low-indium solution contains less than 5 g / L of indium, more than 5 g / L of iron, and more than 5 g / L of arsenic.

[0014] The extracted organic phase includes acidic phosphate extractants, neutral phosphate extractants, and diluents.

[0015] Preferably, the volume ratio of the acidic phosphate extractant, the neutral phosphate extractant, and the diluent is (10-50):(10-50):(10-50).

[0016] Preferably, the neutral phosphate extractant includes tributyl phosphate (TBP).

[0017] Preferably, the acidic phosphate extractant includes at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester (P507) and di(2-ethylhexyl) phosphate (P204).

[0018] Preferably, the diluent includes at least one of white oil and sulfonated kerosene.

[0019] Preferably, the white oil is a light white oil.

[0020] Preferably, the preparation process of the high-iron, high-arsenic, low-indium solution involves neutralizing an indium sulfate solution to obtain the solution.

[0021] Preferably, the temperature of the neutralization treatment is 18-100℃; more preferably, the temperature of the neutralization treatment is 20-90℃.

[0022] Preferably, the neutralizing agent used in the neutralization treatment includes sodium carbonate.

[0023] Preferably, after neutralization, the concentration of sulfuric acid in the indium sulfate solution is 10-50 g / L.

[0024] Preferably, after neutralization, the solution is filtered through a filter press to obtain the high-iron, high-arsenic, and low-indium solution.

[0025] Preferably, the preparation process of the indium sulfate solution is as follows: a dilute sulfuric acid solution is prepared by using concentrated sulfuric acid; the indium-containing displacement residue and the dilute sulfuric acid solution are mixed; an indium-containing displacement residue additive is added; a leaching reaction is carried out; the mixture is then filtered under pressure; and the filtrate is taken as the indium sulfate solution.

[0026] Preferably, the concentration of the dilute sulfuric acid solution is 120-300 g / L.

[0027] Preferably, the ratio of the amount of indium-containing displacement slag additive to the amount of indium-containing displacement slag is (0.3-2) kg: 1 t.

[0028] Preferably, the indium-containing displacement slag additive is a filter aid.

[0029] Preferably, the indium-containing displacement slag additive includes a polyethylene glycol filter aid.

[0030] Preferably, after the leaching reaction, the final acidity of the system is controlled to be 18-110 g / L; more preferably, after the leaching reaction, the final acidity of the system is controlled to be 20-100 g / L.

[0031] Preferably, the leaching reaction temperature is 70-130℃ and the leaching reaction time is 1-5.5h; more preferably, the leaching reaction temperature is 75-120℃ and the leaching reaction time is 1-5h.

[0032] Preferably, in step (1), the raffinate is subjected to sulfidation treatment with sodium sulfide (sulfidation arsenic removal) to achieve the separation of iron and arsenic.

[0033] Preferably, in step (1), the frequency of the ultrasonic wave is 18-55 kHz; more preferably, the frequency of the ultrasonic wave is 20-50 kHz.

[0034] Preferably, in step (1), the extraction ratio is (1-10):1; more preferably, the extraction ratio is (1-2):1.

[0035] Specifically, "comparison" refers to the volume ratio of the organic phase to the aqueous phase (O / A). In this invention, the comparison during extraction refers to the volume ratio of the extracting organic phase to the high-iron, high-arsenic, and low-indium solution, while the comparison during back-extraction refers to the volume ratio of the indium-loaded organic phase to the back-extraction agent.

[0036] Preferably, in step (1), the number of extraction stages is 2-10; more preferably, in step (1), the number of extraction stages is 3.

[0037] Preferably, in step (1), the extraction time is 2-30 min; more preferably, in step (1), the extraction time is 2-5 min.

[0038] Preferably, in step (1), the extraction temperature is 20-60℃; more preferably, in step (1), the extraction temperature is 35℃.

[0039] Preferably, in step (2), the ratio of back-extraction is (1-10):1; more preferably, the ratio of extraction is 2:1.

[0040] Preferably, in step (2), the number of back-extraction stages is 2-10; more preferably, in step (2), the number of back-extraction stages is 3.

[0041] Preferably, in step (2), the back-extraction time is 2-30 min; more preferably, in step (2), the back-extraction time is 2-10 min.

[0042] Preferably, in step (2), the temperature of the back-extraction is 20-60°C; more preferably, in step (2), the temperature of the back-extraction is 35°C.

[0043] Preferably, step (2) further includes a process of washing the organic phase loaded with indium before back-extraction.

[0044] Preferably, water is used for washing.

[0045] Preferably, after the indium-loaded organic phase is washed, the washing liquid is returned to the extraction feed liquid.

[0046] Preferably, the washing ratio is (5-20):1, the washing level is 1-5, the washing time is 2-30 minutes, and the washing temperature is 20-60℃.

[0047] Specifically, in this invention, the ratio of washing before back-extraction refers to the volume ratio of the indium-loaded organic phase to water.

[0048] Preferably, in step (2), the back-extraction agent used includes a sulfuric acid solution.

[0049] Preferably, the concentration of the sulfuric acid solution is 100-400 g / L.

[0050] Preferably, in step (2), the organic phase obtained after back-extraction is used for cyclic extraction.

[0051] Preferably, in step (2), the organic phase obtained after back-extraction is washed with water, and the washed organic phase is used for recycling extraction. The washing liquid is returned to the extraction feed liquid, that is, returned to the high iron, high arsenic, and low indium solution.

[0052] Preferably, in step (2), the washing ratio after back-extraction is (5-20):1, the number of washing stages is 2-10, the mixing washing time is 2-30 min, and the temperature is 20-60℃.

[0053] Specifically, in this invention, the washing ratio after back-extraction refers to the volume ratio of the organic phase obtained after back-extraction to water.

[0054] Preferably, in step (2), the back-extraction is recycled until the concentration of indium in the indium-containing back-extraction solution is ≥10 g / L.

[0055] Preferably, in step (2), the acid separation method is diffusion dialysis.

[0056] Specifically, the indium-containing back-extraction solution obtained after multiple cycles of back-extraction is tested for sulfuric acid concentration and indium ion concentration. It is then passed through a diffusion dialysis device to obtain recovered acid (acid solution) and diffusion dialysis residue (indium-containing low-acid solution). The recovered acid is added to concentrated sulfuric acid to prepare a back-extraction agent and returned to back-extraction for cyclic back-extraction, thus achieving recycling. The diffusion dialysis residue is used as a pre-arsenic removal solution for later use.

[0057] Preferably, in step (2), the reducing agent includes at least one of sodium sulfide and sodium hydrosulfide.

[0058] Preferably, in step (2), the reaction temperature is 20-100℃ and the reaction time is 5-120 min.

[0059] Specifically, the reaction involves a diffusion dialysis residue (containing indium and low acid solution) reacting with a reducing agent. After the reaction, the solution is filtered through a filter press to remove arsenic, thus achieving arsenic removal.

[0060] Preferably, the method for separating iron, arsenic, and indium includes the following steps:

[0061] Indium-containing displacement residue and dilute sulfuric acid solution are mixed, and indium-containing displacement residue additive is added. The mixture is then leached, filtered, and the filtrate is an indium-containing sulfate solution. The indium-containing sulfate solution is neutralized to obtain a high-iron, high-arsenic, low-indium solution. This high-iron, high-arsenic, low-indium solution is mixed with an extractant organic phase and extracted under ultrasonic conditions to obtain an indium-loaded organic phase and raffinate. The raffinate is sulfided with sodium sulfide to separate arsenic and iron, resulting in arsenic sulfide precipitate while iron remains in the solution. The indium-loaded organic phase is washed and then mixed with sulfuric acid solution for back-extraction to obtain an indium-containing back-extraction solution. This indium-containing back-extraction solution is acid-separated to obtain an indium-containing low-acid solution. The indium-containing low-acid solution is mixed with a reducing agent, reacted, and the arsenic impurity in the solution is removed. The solution is then filtered to obtain an indium-enriched solution.

[0062] A second aspect of the present invention provides an application of the method for separating iron, arsenic and indium described in the first aspect of the present invention in the field of hydrometallurgy.

[0063] Compared with the prior art, the beneficial effects of the technical solution provided by the present invention are as follows:

[0064] (1) Under highly acidic conditions, this invention targets indium solutions containing high concentrations of arsenic and iron. With the assistance of an ultrasonic field, it combines neutral and acidic phosphate extractants to preferentially extract indium while effectively inhibiting the extraction of iron and arsenic, achieving selective stepwise separation of indium, iron, and arsenic. This process successfully overcomes the challenge of separating high-concentration iron and arsenic from indium using traditional methods, achieving effective enrichment of indium, iron, and arsenic through this selective stepwise separation method.

[0065] (2) The organic phase obtained after back-extraction in this invention can be returned to the extraction section for cyclic extraction, which facilitates the rational utilization of resources. Attached Figure Description

[0066] Figure 1 This is a process flow diagram of the separation method in Embodiment 1 of the present invention. Detailed Implementation

[0067] To enable those skilled in the art to more clearly understand the technical solutions described in this invention, the following embodiments are provided for illustration. It should be noted that the following embodiments do not constitute a limitation on the scope of protection claimed by this invention.

[0068] Unless otherwise specified, the raw materials, reagents or devices used in the following examples are available from conventional commercial sources or can be obtained by existing known methods.

[0069] The calculation methods for extraction rate, back-extraction rate, retention rate, and removal rate involved in this invention are as follows:

[0070] Extraction rate = (1 - content of raffinate (indium, iron, arsenic) / content of leachate (indium, iron, arsenic) after neutralization) × 100%;

[0071] Back-extraction rate = (Indium, iron, arsenic) content in back-extraction solution / {{Indium, iron, arsenic) content in neutralized leachate - (Indium, iron, arsenic) content in raffinate} × 2} × 100%;

[0072] Retention rate = Iron, arsenic and indium in diffusion dialysis residue / Iron, arsenic and indium in indium back-extraction solution × 100%;

[0073] Removal rate = (1 - iron, arsenic and indium in the indium enrichment solution after arsenic removal / iron, arsenic and indium in the diffusion dialysis residue) × 100%.

[0074] Example 1

[0075] A method for separating iron, arsenic, and indium, comprising the following steps:

[0076] Pretreatment: A dilute sulfuric acid solution (120 g / L) prepared with 98% (mass fraction) industrial sulfuric acid was used to leach the indium-containing replacement slag. The liquid-to-solid ratio was 9:1, the leaching temperature was 105℃, the reaction time was 2 hours, and the dosage of the replacement slag additive was 1 kg / t (1 kg of polyethylene glycol was added to 1 ton of indium-containing replacement slag). The leachate obtained after leaching was an indium sulfate solution (corresponding to...). Figure 1 The indium-containing solution was neutralized by adding sodium carbonate at a temperature of 45°C until the sulfuric acid concentration was 25 g / L and the pH was 0.5. After filtration by a filter press, the pretreated leachate was obtained, which is a high-iron, high-arsenic, and low-indium solution, and was used as the extraction solution. The composition of the neutralized leachate is shown in Table 1.

[0077] Extraction and back-extraction: The volume ratio of P507, TBP, and white oil in the organic phase was 30:50:20. After thorough mixing, the mixture was pumped into an extraction tank and mixed with the pretreated leachate (i.e., a high-iron, high-arsenic, low-indium solution). The extraction reaction was carried out under ultrasonic assistance at a frequency of 20 kHz. The extraction ratio was controlled at 1:1, with 3 extraction stages, a mixing extraction time of 5 min, and an extraction temperature of 35 ℃. This yielded an indium-loaded organic phase and a raffinate (corresponding to...). Figure 1 The indium-loaded organic phase was subjected to sulfidation treatment with sodium sulfide to separate arsenic and iron, resulting in arsenic sulfide precipitate and iron in solution. The indium-loaded organic phase was washed with pure water at a ratio of 10:1, with two washing stages, a mixing time of 10 min, and a washing temperature of 35℃. The washing liquid was returned to the extraction feed. The indium-loaded organic phase was back-extracted using 250 g / L sulfuric acid solution as the back-extraction agent at a ratio of 2:1, with three back-extraction stages, a mixing time of 10 min, and a back-extraction temperature of 35℃. The unloaded organic phase obtained from the back-extraction was washed with pure water at a ratio of 10:1, with two washing stages, a mixing time of 10 min, and a temperature of 35℃. The washing liquid was returned to the extraction feed, and the regenerated organic phase was returned to the extraction. The parameters of the raffinate and back-extraction liquid are shown in Table 1.

[0078] Acid separation: The indium back-extraction solution obtained from multiple cycles of back-extraction was tested for sulfuric acid concentration and indium ion concentration. It was then passed through a diffusion dialysis device with a certain amount of softened water added to the inlet end of the diffusion dialysis to obtain recovered acid (acid solution) and diffusion dialysis residue (low-acid solution containing indium). The recovered acid was added to concentrated sulfuric acid to prepare back-extraction agent and returned to back-extraction. The diffusion dialysis residue was used as pre-treatment solution for arsenic removal. The test data of the recovered acid and diffusion dialysis residue are shown in Table 2.

[0079] Arsenic removal: The diffusion dialysis residue (containing indium low acid solution) obtained by diffusion dialysis was tested for the concentrations of indium, iron, and arsenic ions. Sodium sulfide was added according to the theoretical coefficient of 1.1, the mixing temperature was 45℃, the reaction time was 30 min, and the solution was filtered by a filter press to obtain the indium-enriched solution after arsenic removal. The test data of the diffusion dialysis residue and the indium-enriched solution after arsenic removal are shown in Table 3.

[0080] The process flow of the separation method in Embodiment 1 of the present invention is as follows: Figure 1 As shown.

[0081] Table 1: Comparative data of leachate, extract, and back-extraction solution after neutralization in Example 1

[0082]

[0083] Table 2: Comparison data of recovered acid and diffusion dialysis residue in Example 1

[0084] project Fe As In <![CDATA[H2SO4]]> Indium back-extraction solution (g / L) 2.2 1.3 19.5 220 Recovered acid (g / L) 0.12 0.21 0.52 192 Diffusion dialysis residue (g / L) 2.08 1.09 18.98 28 Retention rate (%) 94.55 83.85 97.33 12.72

[0085] Table 3: Comparative data of diffusion dialysis residue and indium-enriched solution after arsenic removal in Example 1

[0086] project Fe As In Diffusion dialysis residue (g / L) 2.08 1.09 18.98 Indium enrichment solution after arsenic removal (g / L) 2.01 0.02 18.77 Removal rate (%) 3.36 98.17 1.11

[0087] Example 2

[0088] Example 2 provides a method for separating iron, arsenic and indium. The only difference between Example 2 and Example 1 is that the frequency of the ultrasonic wave in Example 2 is 50 kHz. Otherwise, they are the same as in Example 1.

[0089] The comparative data of the leachate, extract, and back-extraction solution in Example 2 are shown in Table 4.

[0090] Table 4: Comparative data of leachate, extract, and back-extraction solution in Example 2

[0091]

[0092] Example 3

[0093] Example 3 provides a method for separating iron, arsenic, and indium. The only difference between this method and Example 1 is that the extraction uses an organic phase with different volume ratios. The volume ratios of P507, TBP, and white oil are 30:50:20 (denoted as A), 30:40:30 (denoted as B), and 30:30:40 (denoted as C), respectively. The effect of the leachate after extraction pretreatment is compared. The extraction ratio is controlled at 1:1, the number of extraction stages is 3, the mixing extraction time is 5 min, and the extraction temperature is 35°C. The back-extraction agent is a 250 g / L sulfuric acid solution, the back-extraction ratio is 2:1, the number of back-extraction stages is 3, the mixing back-extraction time is 10 min, and the back-extraction temperature is 35°C.

[0094] The parameters of the leachate, extract, and back-extraction solution in Example 3 are shown in Table 5.

[0095] Table 5: Comparison data of neutralized leachate, extract, and back-extraction solution in Example 3

[0096]

[0097]

[0098] Comparative Example 1

[0099] Comparative Example 1 provides a method for separating iron, arsenic, and indium. The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 does not perform ultrasonic-assisted extraction; otherwise, it is the same as Example 1.

[0100] The parameters of the leachate, extract, and back-extraction solution after neutralization in Comparative Example 1 are shown in Table 6.

[0101] The detection data of recovered acid and diffusion dialysis residue in Comparative Example 1 are shown in Table 7.

[0102] The detection data of the diffusion dialysis residue and the indium-enriched solution after arsenic removal in Comparative Example 1 are shown in Table 8.

[0103] Table 6: Comparative data of leachate, extract and back-extraction solution after neutralization in Comparative Example 1

[0104]

[0105] Table 7: Comparison data of recovered acid and diffusion dialysis residue in Comparative Example 1

[0106] project Fe As In <![CDATA[H2SO4]]> Indium back-extraction solution (g / L) 3.12 3.07 19.98 220 Recovered acid (g / L) 0.12 0.21 0.52 192 Diffusion dialysis residue (g / L) 2.94 2.56 19.46 28 Retention rate (%) 94.23 83.39 97.4 12.72

[0107] Table 8: Comparative data of diffusion dialysis residue and indium-enriched solution after arsenic removal from Comparative Example 1

[0108] project Fe As In Diffusion dialysis residue (g / L) 2.94 2.56 19.46 Indium enrichment solution after arsenic removal (g / L) 2.87 0.02 18.97 Removal rate (%) 2.38 99.22 2.52

[0109] Comparative Example 2

[0110] Comparative Example 2 provides a method for separating iron, arsenic, and indium. An extraction organic phase consisting of 30% P507 + 70% white oil (denoted as ①) and an extraction organic phase consisting of 30% P507 + 50% TBP + 20% white oil (denoted as ②) are compared. The pretreated extract is compared with the extract. The extraction ratio is controlled at 1:1, the extraction stages are 3, the mixing extraction time is 5 min, and the extraction temperature is 35℃. The back-extraction agent is a 250 g / L sulfuric acid solution, the back-extraction ratio is 2:1, the back-extraction stages are 3, the mixing back-extraction time is 10 min, and the back-extraction temperature is 35℃. Other parameters are the same as in Example 1.

[0111] The parameters of the leachate, extract, and back-extraction solution after neutralization in Comparative Example 2 are shown in Table 9.

[0112] Table 9: Comparative data of leachate, extract and back-extraction solution after neutralization in Comparative Example 2

[0113]

[0114]

[0115] Comparative Example 3

[0116] Comparative Example 3 provides a method for separating iron, arsenic, and indium. An extraction organic phase (denoted as ③) consisting of 50% TBP and 50% white oil (volume fraction) is compared with an extraction organic phase (denoted as ④) consisting of 30% P507, 50% TBP, and 20% white oil (volume fraction). The pretreated extract is compared. The extraction ratio is controlled at 1:1, with 3 extraction stages, a mixing extraction time of 5 min, and an extraction temperature of 35°C. A 250 g / L sulfuric acid solution is used as the back-extraction agent, with a back-extraction ratio of 2:1, 3 back-extraction stages, a mixing back-extraction time of 10 min, and a back-extraction temperature of 35°C. Other parameters are the same as in Example 1.

[0117] The parameters of the leachate, extract, and back-extraction solution after neutralization in Comparative Example 3 are shown in Table 10.

[0118] Table 10: Comparative data of leachate, extract and back-extraction solution after neutralization in Comparative Example 3

[0119]

[0120] As can be seen from the comparison of the examples and comparative examples, the present invention employs ultrasonic-assisted indium extraction, combined with an extraction organic phase of a specific composition, which can preferentially extract indium while effectively inhibiting the extraction of iron and arsenic, thus achieving a process for the selective stepwise separation of indium, iron, and arsenic. Furthermore, the extraction and separation effect can be adjusted by further regulating the volume ratio of each component in the extraction organic phase.

[0121] Comparative Example 1 did not undergo ultrasonic-assisted indium extraction. The extraction rate of indium in Comparative Example 1 was lower than that in Example 1, while the extraction rates of arsenic and iron were higher than those in Example 1.

[0122] Comparative Example 2 did not contain the neutral phosphate extractant TBP, and Comparative Example 3 did not contain the acidic phosphate extractant P507. As a result, in Comparative Example 2, the extraction rate of iron increased significantly, while the extraction rates of arsenic and indium and the back-extraction rate of iron decreased significantly. In Comparative Example 3, the extraction rates of iron and arsenic increased significantly, while the extraction rates of indium and the back-extraction rate decreased significantly.

[0123] In summary, this invention provides a process for the selective stepwise separation of indium, iron, and arsenic in indium solutions containing high concentrations of arsenic and iron, aided by an ultrasonic field. This process successfully overcomes the challenge of separating high-concentration iron and arsenic from indium using traditional methods. By employing ultrasonic-assisted indium extraction, combined with the use of neutral and acidic phosphate extractants, indium is preferentially extracted while effectively inhibiting the extraction of iron and arsenic. This selective stepwise separation method achieves the effective enrichment of indium, iron, and arsenic.

[0124] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for separating iron, arsenic, and indium, characterized in that, Includes the following steps: (1) Mix the high-iron, high-arsenic, and low-indium solution with the extractable organic phase, and extract under ultrasonic action to obtain an indium-loaded organic phase and raffinate. (2) The indium-loaded organic phase obtained in step (1) is back-extracted to obtain an indium-containing back-extracting solution; the indium-containing back-extracting solution is separated by acid, mixed with a reducing agent, reacted, filtered, and an indium-enriched solution is obtained. The high-iron, high-arsenic, low-indium solution contains less than 5 g / L of indium, more than 5 g / L of iron, and more than 5 g / L of arsenic. The extracted organic phase includes acidic phosphate extractants, neutral phosphate extractants, and diluents.

2. The separation method according to claim 1, characterized in that, The volume ratio of the acidic phosphate extractant, the neutral phosphate extractant, and the diluent is (10-50):(10-50):(10-50).

3. The separation method according to claim 2, characterized in that, The neutral phosphate extractant includes tributyl phosphate; and / or, the acidic phosphate extractant includes at least one of 2-ethylhexyl phosphate mono-2-ethylhexyl ester and di(2-ethylhexyl) phosphate; and / or, the diluent includes at least one of white oil and sulfonated kerosene.

4. The separation method according to claim 1, characterized in that, The preparation process of the high-iron, high-arsenic, low-indium solution involves neutralizing an indium sulfate solution to obtain the solution.

5. The separation method according to claim 1, characterized in that, In step (1), the raffinate is subjected to sulfidation treatment with sodium sulfide to achieve the separation of iron and arsenic; and / or, the frequency of the ultrasound is 18-55 kHz; and / or, the extraction ratio is (1-10):1; and / or, the number of extraction stages is 2-10; and / or, the extraction time is 2-30 min; and / or, the extraction temperature is 20-60℃.

6. The separation method according to claim 1, characterized in that, In step (2), the ratio of the back-extraction is (1-10):1; and / or, the number of back-extraction stages is 2-10; and / or, the back-extraction time is 2-30 min; and / or, the back-extraction temperature is 20-60℃.

7. The separation method according to claim 1, characterized in that, In step (2), the back-extraction process includes washing the indium-loaded organic phase before the back-extraction; and / or, the back-extraction agent used includes sulfuric acid solution; and / or, the organic phase obtained after back-extraction is used for cyclic extraction.

8. The separation method according to claim 7, characterized in that, The washing ratio is (5-20):1, the washing level is 1-5, the washing time is 2-30 minutes, and the washing temperature is 20-60℃. And / or, the concentration of the sulfuric acid solution is 100-400 g / L.

9. The separation method according to claim 1, characterized in that, In step (2), the reducing agent includes at least one of sodium sulfide and sodium hydrosulfide; and / or, the reaction temperature is 20-100℃ and the reaction time is 5-120 min.

10. The application of the separation method according to any one of claims 1-9 in the field of hydrometallurgy.

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