Method for extracting and separating indium

Abstract

The invention discloses a method for extracting and separating indium, and relates to the technical field of hydrometallurgy. The method comprises the following steps: mixing an extracted organic phase with an indium-containing sulfate solution, and extracting to obtain an indium-loaded organic phase; carrying out reverse extraction on the indium-loaded organic phase by adopting a sulfuric acid solution to obtain an indium-containing reverse extraction solution; carrying out acid separation and replacement to obtain indium; the extraction organic phase comprises an amine extraction agent, an acidic phosphate extraction agent and a diluent. According to the method, the extraction capacity of indium is guaranteed, meanwhile, the extraction capacity of iron ions is reduced, reverse extraction of indium and iron in the loaded organic phase is easier, chlorine-containing waste water and chlorine-containing waste residues are avoided, meanwhile, organic phase poisoning caused by difficulty in reverse extraction of iron through hydrochloric acid is avoided, and the method is suitable for industrial production. Water washing liquid, an organic phase and an acid solution generated in the extraction and separation process can be recycled, and waste water and waste residues are not generated.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy, and in particular to a method for extracting and separating indium. Background Art

[0002] Indium is an important strategic resource and one of the supporting materials for the development of high technology. Although the reserves of indium are high, since indium does not have independent deposits and mainly coexists with minerals such as lead, zinc, copper, and tin, the current level of recycling technology has a comprehensive recovery rate of only 40% to 60% for indium, and the recovered indium is only a very small part of the reserves. Therefore, how to efficiently separate and recover indium from the smelting process of metals such as lead, zinc, copper, and tin is an important research topic, among which solvent extraction is the key to determining the separation and recovery of indium.

[0003] At present, zinc smelting and other metal smelting mostly use sulfuric acid system production system, and the extracting agent for extracting indium from sulfuric acid solution is mainly acidic phosphate extracting agent, such as P204, P507, Cyanex272, etc. Among them, P204 is the most widely used extracting agent for indium recovery, and the extraction rate in 8mol / L sulfuric acid solution can exceed 80%. In the extraction process, In 3+ Separation of divalent metal ions, but due to the effect of P204 on indium and Fe 3+ The extraction ability of indium is too strong, and the separation coefficient between indium and impurity ions is small, which makes the stripping of indium difficult. High-concentration hydrochloric acid (≥4 mol / L) is required to achieve stripping. At the same time, after long-term operation, the Fe 3+ , Sb 3+ 、Bi 3+ Impurity ions such as ions circulate and accumulate in the organic phase, reducing the indium extraction efficiency and increasing the consumption of the extractant. The aged organic phase needs to be regenerated regularly, which increases the production cost and makes the waste residue difficult to handle. Although P507 has better extraction selectivity for indium than P204, its extraction capacity is weaker, and it will also extract Fe while extracting indium. 3+ In the stripping process, a relatively high concentration of hydrochloric acid (≥2 mol / L) is also required, and the separation effect of indium and iron is poor; Cyanex272 has the weakest extraction ability and the indium extraction rate is low.

[0004] In addition, since P204 and P507 are used as extractants, high-concentration hydrochloric acid needs to be used as a stripping agent for indium, resulting in a large amount of chlorine-containing wastewater being generated during the extraction process. Hydrochloric acid is highly corrosive. For production systems such as zinc smelting that use a sulfuric acid system, chloride ions have a serious negative impact on them. It is one of the important harmful elements for impurity removal. Therefore, the use of high-concentration hydrochloric acid as a stripping agent is bound to increase the difficulty of processing, and increase production costs and management costs. In order to solve the problem of chlorine, the prior art uses chloride ions in the extraction process by eluting and separating to avoid the production impact caused by chloride ions, and then replaces the chlorine-containing waste liquid produced by sponge indium. However, this not only increases the process flow, but also a part of the chlorine-containing waste residue produced after treatment will still enter the production system, which continuously causes the accumulation of chlorine in the production system, which will also have an adverse effect on the production system. Summary of the invention

[0005] The present invention aims to solve at least one of the above-mentioned technical problems existing in the prior art. To this end, the purpose of the present invention is to provide a method for extracting and separating indium, using an acidic phosphate extractant and an amine extractant as an organic phase for extraction, while ensuring the extraction rate of indium ions and reducing the extraction capacity of iron ions, and without using high-concentration hydrochloric acid as a stripping agent.

[0006] A second aspect of the present invention provides a method for recovering indium.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is:

[0008] A first aspect of the present invention provides a method for extracting and separating indium, comprising the following steps:

[0009] The extracted organic phase is mixed with an indium-containing sulfate solution to extract an organic phase loaded with indium; the indium-loaded organic phase is stripped with a sulfuric acid solution to obtain an indium-containing stripping solution; and indium is obtained by acid separation and replacement;

[0010] The extraction organic phase comprises an amine extractant, an acidic phosphate extractant and a diluent.

[0011] The present invention adds an amine extractant to the acidic phosphate extractant, retains the ability to extract indium ions, and can reduce the ability of the extractant system to extract iron ions. In the composite extraction organic phase system composed of the amine extractant and the acidic phosphate extractant, since the two extractants have opposite properties, a chemical reaction occurs after contacting each other, resulting in a change in the molecular structure of the acidic phosphate extractant after extracting iron ions, thereby causing a change in the ability to extract iron ions. The addition of the amine extractant, on the one hand, retains the ability of the original acidic phosphate extractant to extract indium ions in a low-concentration indium-containing sulfate solution, and on the other hand, a sulfuric acid solution can be used instead of hydrochloric acid or a chlorine-containing solution as a stripping agent, and the stripping efficiency of indium and iron is not much different from the stripping efficiency of a hydrochloric acid solution as a stripping agent.

[0012] In the method of the present invention, the equation involved in the extraction process is as follows:

[0013] Fe 3+ +3H2A2=FeA3·3HA+3H +

[0014] In 3+ +3H2A2=InA3·3HA+3H +

[0015] The equations involved in the stripping process are as follows:

[0016] FeA3·3HA+3H + =Fe 3+ +3H2A2

[0017] InA3·3HA+3H + =In 3+ +3H2A2

[0018] Preferably, the indium-containing sulfate solution is obtained by leaching indium-containing replacement slag from a zinc smelting process with a sulfuric acid solution.

[0019] Preferably, the indium-containing sulfate solution is an indium-containing zinc sulfate solution.

[0020] There are other impurity ions in the solution, such as iron ions.

[0021] Preferably, the extraction is a countercurrent extraction.

[0022] Preferably, the volume ratio of the amine extractant, the acidic phosphate extractant and the diluent in the extraction organic phase is (5-30): (10-40): (30-85).

[0023] Further preferably, the volume ratio of the amine extractant, the acidic phosphate extractant and the diluent in the extraction organic phase is (10-20): (20-30): (50-70).

[0024] More preferably, the volume ratio of the amine extractant, the acidic phosphate extractant and the diluent in the extraction organic phase is (10-15): (20-25): (60-70).

[0025] Preferably, the concentration of the sulfuric acid solution is 100-300 g / L.

[0026] More preferably, the concentration of the sulfuric acid solution is 150-250 g / L.

[0027] More preferably, the concentration of the sulfuric acid solution is 200-250 g / L.

[0028] Preferably, the amine extractant includes at least one of N235, TOA, and N1923.

[0029] Preferably, the acidic phosphate extractant is P507.

[0030] Preferably, the diluent includes at least one of white oil and sulfonated kerosene.

[0031] Preferably, the ratio of the extraction to the stripping is (1-10):1.

[0032] Further preferably, the extraction ratio is (1-2):1.

[0033] More preferably, the phase ratio of the stripping is (1-3):1.

[0034] The term "phase ratio" refers to the volume ratio of the organic phase to the aqueous phase (O / A), and in the present invention refers to the volume ratio of the extracted organic phase to the indium-containing sulfate solution or sulfuric acid solution.

[0035] Preferably, the extraction and stripping stages are both 1 to 5 stages.

[0036] More preferably, the extraction stage number is 2 to 4.

[0037] More preferably, the number of stripping stages is 2 to 4.

[0038] Preferably, the temperatures of the extraction and stripping are both 25-65°C.

[0039] More preferably, the extraction temperature is 30-40°C.

[0040] More preferably, the stripping temperature is 30-40°C.

[0041] Preferably, the extraction time is 2 to 15 minutes.

[0042] More preferably, the extraction time is 4 to 8 minutes.

[0043] More preferably, the extraction time is 5 to 6 minutes.

[0044] Preferably, the stripping time is 2 to 15 minutes.

[0045] More preferably, the stripping time is 10 to 15 minutes.

[0046] Preferably, the indium-containing sulfate solution is pre-treated by reduction and neutralization before extraction.

[0047] Further preferably, a reduction reaction occurs during the pretreatment process.

[0048] Further preferably, during the pretreatment process, a reducing agent is first added to carry out a reduction reaction, and then a neutralizing agent is added to carry out a neutralization reaction.

[0049] Before the extraction reaction, pre-treat As 5+ , Fe 3+ Reduction to As 3+ , Fe 2+ , reduce the extraction of arsenic and iron ions, the reduction reaction equation is as follows:

[0050]

[0051]

[0052] Further preferably, the neutralizing agent includes at least one of sodium carbonate, basic zinc carbonate and zinc oxide.

[0053] Further preferably, the reducing agent comprises sulfur dioxide and / or sodium sulfite.

[0054] More preferably, the pretreatment temperature is 30-60°C, more preferably 40-50°C.

[0055] More preferably, the pretreatment time is 1 to 5 hours, more preferably 1 to 2 hours.

[0056] In the present invention, the temperature and time of pretreatment refer to the temperature and time of the reduction reaction during the pretreatment process.

[0057] Preferably, the substance concentration in the indium-containing sulfate solution satisfies the following conditions at the same time:

[0058] 1)As 5+ The concentration is ≤0.5g / L;

[0059] 2)Fe 3+ The concentration is ≤0.3g / L;

[0060] 3) The concentration of sulfuric acid is 5-40 g / L.

[0061] Among them, As 5+ and Fe 3+ The lower the concentration, the better.

[0062] Further preferably, in the indium-containing sulfate solution, the concentration of sulfuric acid (H2SO4) is 10 to 30 g / L; more preferably 15 to 30 g / L.

[0063] The ion concentration and sulfuric acid concentration in the indium-containing sulfate solution are the concentrations during extraction. When the indium-containing sulfate solution is pretreated before extraction, the ion concentration and sulfuric acid concentration are the ion concentration and sulfuric acid concentration in the indium-containing sulfate solution after pretreatment.

[0064] Preferably, the organic phase loaded with indium is subjected to a washing treatment before stripping.

[0065] Further preferably, the washing is carried out with water, the volume ratio of the organic phase loaded with indium to water is (1-10):1; the washing stages are 1-3, the washing time is 2-15 min, and the washing temperature is 25-55°C.

[0066] After washing, the washing liquid obtained is returned to prepare the indium-containing sulfate solution.

[0067] Preferably, the organic phase obtained after the stripping is washed with water, and the washing liquid is returned to prepare the indium-containing sulfate solution.

[0068] Further preferably, in the washing of the organic phase after the stripping, the volume ratio of the organic phase to water is (1-10):1; the number of washing stages is 1-6, the washing time is 2-15 min, and the washing temperature is 25-55°C.

[0069] Preferably, the indium obtained after the replacement is sponge indium, and metallic indium is obtained through agglomeration, smelting and electrowinning.

[0070] Among them, electrodeposition refers to electrolytic deposition.

[0071] Further preferably, the sponge indium is pressed into agglomerates after being washed.

[0072] More preferably, the moisture content of the sponge indium after agglomeration is less than 5%.

[0073] Further preferably, during the smelting process, sodium hydroxide, sodium nitrate and sodium sulfide are added to the sponge indium for smelting.

[0074] Preferably, the replacement is accomplished by adding a replacement reagent to the indium-containing low-acid solution obtained by acid separation.

[0075] Further preferably, the replacement reagent comprises zinc, such as zinc powder and / or zinc plate.

[0076] Among them, zinc powder is blown by electrolytic zinc deposition, Zn T Greater than 99%; the zinc plate is electrolytic 0# zinc sheet.

[0077] Zn T Refers to the total zinc content in zinc powder; 0# zinc flake is the national standard for zinc ingot products.

[0078] More preferably, the molar ratio of zinc to indium in the replacement is (1-1.5):1; more preferably (1.025-1.2):1.

[0079] Preferably, the replacement temperature is 30-85°C; more preferably 50-70°C; more preferably 60-70°C.

[0080] Preferably, the replacement time is 2 to 24 hours; more preferably, it is 10 to 15 hours.

[0081] Preferably, the replacement further includes a filtration step; after the filtration, sponge indium and filtrate are obtained.

[0082] Further preferably, the filtering device comprises a filter press.

[0083] Further preferably, the filtrate after replacement and filtration is returned to the zinc smelting system for zinc recovery after oil removal.

[0084] More preferably, the TOC of the filtrate after oil removal is ≤50ppm.

[0085] Preferably, the smelting temperature is 300-400°C; more preferably 300-350°C.

[0086] Preferably, during the smelting process, the sponge indium is stirred for 30 to 60 minutes after melting to complete the reaction.

[0087] Preferably, the indium liquid obtained after smelting is cast to form a crude indium plate, and 99.99% metallic indium is obtained after electrowinning.

[0088] More preferably, the casting further includes alkali dissolution and impurity removal.

[0089] Preferably, the organic phase obtained after the stripping is used for cyclic extraction.

[0090] Preferably, the sulfuric acid solution obtained after the acid separation is used for cyclic stripping.

[0091] Preferably, the acid separation method is diffusion dialysis.

[0092] The invention adopts sulfuric acid as a stripping agent. The indium stripping solution obtained by extraction contains free sulfuric acid of a certain concentration. The free sulfuric acid is separated by acid separation, and is returned to the stripping agent preparation section to be added with concentrated sulfuric acid for recycling. The low-acid indium-containing solution obtained after the acid separation is added with zinc powder or zinc plate for replacement to obtain sponge indium. The zinc sulfate solution obtained after filtration can be returned to the zinc smelting system to recover zinc after oil removal treatment. No waste water and waste residue are generated in the whole process.

[0093] Further preferably, the diffusion dialysis is performed by a diffusion dialysis membrane device, and the specific process includes the following steps:

[0094] The indium-containing stripping solution obtained by stripping flows into the dialysis chamber, and pure water flows into the diffusion chamber as the receiving liquid. The sulfate ions in the dialysis chamber pass through the anion exchange membrane into the diffusion chamber. After the diffusion dialysis is completed, the liquid in the dialysis chamber is the dialysis residual liquid, and the liquid in the diffusion chamber is the acid solution.

[0095] Preferably, the method for extracting and separating indium comprises the following steps:

[0096] The indium-containing sulfate solution that has been pretreated by reduction and neutralization is mixed with the extracted organic phase for extraction to obtain an organic phase loaded with indium and a raffinate; the organic phase loaded with indium is washed, and then mixed with a sulfuric acid solution for stripping to obtain an indium-containing stripping solution; the indium-containing stripping solution is subjected to acid separation to obtain an indium-containing low-acid solution; the indium-containing low-acid solution is replaced to obtain sponge indium, and the sponge indium is pressed into a mass and cast to form a crude indium plate, and metallic indium is prepared by electrowinning.

[0097] A second aspect of the present invention provides a method for recovering indium, wherein the steps of the recovery method include the method for extracting and separating indium as described in the first aspect of the present invention.

[0098] The overall process of the method described in the present invention is all carried out in a sulfuric acid system without introducing chloride ions or other organic reagents. The process is green and environmentally friendly, the process is simple and efficient, the recovery rate of zinc and indium is high, and it can be used to recover indium.

[0099] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0100] (1) The method for extracting and separating indium of the present invention is simple and efficient. By using an amine extractant and an acidic phosphate extractant, the extraction capacity of indium is guaranteed while the extraction capacity of iron ions is reduced, and the stripping of indium and iron in the loaded organic phase is easier. The stripping effect of the metal can be achieved by using a dilute sulfuric acid solution as a stripping agent. The use of sulfuric acid solution instead of the traditional process must use hydrochloric acid solution or a chlorine-containing mixed stripping agent, compared with the traditional process, avoids the generation of chlorine-containing wastewater and chlorine-containing waste residue, and avoids the organic phase poisoning caused by the difficulty of stripping iron with hydrochloric acid, and many problems such as the need to use an organic reagent to regenerate the organic phase after poisoning.

[0101] (2) The method of the present invention can further select a specific extractant to solve the problems of existing extractants. For example, the combination of P507 and amine extractants can effectively solve the shortcomings of the currently widely used P204 extraction process for indium extraction, while overcoming the defect of P507's weak extraction ability, and having better ion selectivity, and easy to achieve industrial production.

[0102] (3) The method of the present invention separates the free acid in the indium-containing stripping solution through the acid separation step, and the obtained acid solution can be recycled, which greatly reduces the amount of stripping agent sulfuric acid solution and replacement reagent zinc powder or zinc plate, and the utilization rate of metal and acid is high.

[0103] (4) The overall production process in the method provided by the present invention is matched with the zinc smelting system. Since chloride ions are not introduced, there is no need to consider the impact of chloride ions on the zinc smelting system, which simplifies the traditional P204 indium extraction process. The sulfate solution or sulfuric acid solution produced in the process can be returned to the zinc smelting system to recover metallic zinc. The overall process does not produce wastewater or waste residue, and the process is simple, green, efficient and environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0104] Figure 1 The process flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0105] The present invention is further described in detail below by specific examples. Unless otherwise specified, the raw materials, reagents or devices used in the examples and comparative examples can be obtained from conventional commercial sources or can be obtained by prior art methods. Unless otherwise specified, the experiments or test methods are conventional methods in the art.

[0106] In the following examples and comparative examples of the present invention, the extraction rate (η 萃 ) and stripping rate (η 反 ) is calculated as follows:

[0107] η 萃 =(ρ0-ρ1) / ρ0×100%, η 反 =ρ2 / (ρ0-ρ1)×100%.

[0108] Where: ρ0—initial mass concentration of metal ions, unit: g / L; ρ1—mass concentration of metal ions in the raffinate, unit: g / L; ρ2—mass concentration of metal ions in the stripping solution, unit: g / L.

[0109] The calculation formula of retention rate (β) is:

[0110] β Me =ρ1 / ρ0×100%, β 酸 =ρ2 / ρ0×100%.

[0111] Where: ρ0—initial mass concentration of metal ions, unit: g / L; ρ1—mass concentration of metal ions in the residual liquid after diffusion dialysis, unit: g / L; ρ2—mass concentration of acid in the recovered acid, unit: g / L.

[0112] The qualified standards of the pretreated leachate in the embodiments and comparative examples are as follows: 5+ The concentration of Fe is ≤0.5g / L; 3+ The concentration of sulfuric acid is 5-40g / L.

[0113] The ion contents in the examples and comparative examples were all measured using conventional chemical analysis methods.

[0114] The process flow chart in the embodiment of the present invention is as shown in the attached Figure 1 As shown, the following is a detailed description in conjunction with specific embodiments.

[0115] Example 1

[0116] This embodiment provides a method for extracting and separating indium, comprising the following steps:

[0117] Pretreatment: Use 98% (mass fraction) industrial sulfuric acid to prepare dilute sulfuric acid (120g / L) to leach the indium-containing replacement slag. The leaching solution obtained after leaching is an indium-containing sulfate solution (corresponding to Figure 1 Indium-containing liquid in the process flow chart), draw 1m 3 The leaching solution was put into the reactor, stirring was started, and 35 kg of sodium sulfite was slowly added. The reduction temperature was controlled at 45 °C and the reduction reaction time was 1 h. After the reduction was completed, samples were taken to detect the As content in the solution. 5+ , Fe 3+ Ion concentration and sulfuric acid concentration, after passing the test, add sodium carbonate to neutralize to a sulfuric acid concentration of 25g / L, filter through a filter press to obtain a pre-treated leachate for standby use; the composition of the leachate after reduction and neutralization is shown in Table 1;

[0118] Extraction and back extraction: The volume ratio of the extracted organic phase is P507: N235: white oil = 20: 10: 70. After being fully mixed, it is pumped into the extraction box and subjected to extraction reaction with the pretreated leaching solution. The extraction control ratio is 1: 1, the extraction level is 3, the mixed extraction time is 6 minutes, and the extraction temperature is 35°C; the organic phase loaded with indium is washed with pure water, the washing ratio is 10: 1, the washing level is 2, the mixed washing time is 13 minutes, the washing temperature is 35°C, and the washing liquid is 1: 1. Return the indium-containing feed liquid; use 250g / L sulfuric acid solution as a stripping agent to strip the indium-loaded organic phase, the stripping ratio is 2:1, the stripping stage is 3, the mixed stripping time is 12min, and the stripping temperature is 35°C; the unloaded organic phase obtained by stripping is washed with pure water, the washing ratio is 10:1, the washing stage is 5, the mixed washing time is 13min, the temperature is 35°C, the washing liquid is returned to the indium-containing feed liquid, and the organic phase is returned to the extraction; the parameters of the extract and the stripping liquid are shown in Table 1;

[0119] Acid separation: After multiple rounds of cyclic stripping, indium stripping solution is obtained, and the sulfuric acid concentration and indium ion concentration are detected. Then, the recovered acid (acid solution) and diffusion dialysis residue (low-acid solution containing indium) are obtained through diffusion dialysis equipment. The recovered acid is added with concentrated sulfuric acid to prepare a stripping agent and returned to stripping; the test data of the recovered acid and the diffusion dialysis residue are shown in Table 2;

[0120] Replacement, briquetting, smelting, electrowinning: Take 10L of the residual liquid from the diffusion dialysis, press m zn :m In =1.1:1 Add electrolytic zinc sheet blowing (Zn T ≥99%) zinc powder 0.2kg, the replacement reaction temperature is 65°C, the reaction time is 12h, after the reaction, the replacement filtrate is filtered by a filter press, the filter residue is crude sponge indium, the filtered filtrate is passed through a first-level flotation oil removal device and an activated carbon adsorption device, the TOC after oil removal is 48ppm, and it is returned to the zinc smelting system to recover zinc; the sponge indium is washed with pure water and then pressed into a mass, the moisture content after pressing is 4.2%, and the mass content of In in the sponge indium is 82.52%, the sponge indium after pressing is slowly put into a smelting pot melted with sodium hydroxide, sodium nitrate and sodium sulfide for smelting, the smelting temperature is 320°C, after the sponge indium is melted, the reaction is stirred for 30min, the alkali slag is skimmed off, the crude indium is cast into crude indium with In≥98%, and 99.99% metallic indium is obtained after electrolysis.

[0121] Table 1 Comparative data of the leachate, extract and stripping solution of Example 1

[0122]

[0123] Table 2 Comparative data of recovered acid and diffusion dialysis raffinate of Example 1

[0124] project Fe As In <![CDATA[H2SO4]]> Indium stripping solution (g / L) 4.472 5.568 23.244 195 Recovered acid (g / L) 0.041 0.323 2.050 170 Diffusion dialysis residue (g / L) 3.901 3.111 21.194 25 Retention rate (%) 87.23 55.87 91.18 87.18

[0125] Example 2

[0126] This embodiment provides a method for extracting and separating indium, comprising the following steps:

[0127] Pretreatment: 98% industrial sulfuric acid was used to prepare dilute sulfuric acid (120 g / L) to leach different batches (batch 1 and batch 2) of indium-containing replacement slag. The leaching solution obtained after leaching was an indium-containing sulfate solution (indium-containing feed solution). 1m 3 The leaching solution was put into the reactor, and the stirring was started and the sulfur dioxide produced by the sulfur dioxide hydrolysis solution was slowly introduced into the zinc oxide to absorb the sulfur dioxide as a reducing agent. The reduction temperature was controlled at 40°C and the reduction reaction time was 4h. After the reduction was completed, the As content in the solution was sampled and tested. 5+ , Fe 3+ Ion concentration and sulfuric acid concentration, after passing the test, add basic zinc carbonate to neutralize until the sulfuric acid concentration is 20g / L, filter through a filter press to obtain a pre-treated leachate for standby use; the components of the leachate after neutralization and reduction are shown in Table 3;

[0128] Extraction and stripping: The volume ratio of the extracted organic phase is P507: N235: white oil = 20: 10: 70. After being fully mixed, it is pumped into the extraction box and subjected to extraction reaction with the pretreated leaching solution. The extraction control ratio is 1: 1, the extraction level is 3, the mixed extraction time is 5 min, and the extraction temperature is 35 ° C. The organic phase loaded with indium is washed with pure water, the washing ratio is 10: 1, the washing level is 2, the mixed washing time is 15 min, the washing temperature is 35 ° C, and the washing liquid is returned to the indium-containing liquid. The stripping agent is 250 g / L sulfuric acid solution, the stripping ratio is 2: 1, the stripping level is 3, the mixed stripping time is 10 min, and the stripping temperature is 35 ° C. The empty organic phase obtained after stripping is washed with pure water, the washing ratio is 10: 1, the washing level is 5, the mixing time is 15 min, the temperature is 35 ° C, the washing liquid is returned to the indium-containing liquid, and the organic phase is returned to the extraction; the parameters of the extract and stripping solution are shown in Table 3;

[0129] Acid separation: After multiple rounds of cyclic stripping, indium stripping solution was obtained, and the sulfuric acid concentration and indium ion concentration were detected. Then, the recovered acid and diffusion dialysis residue were obtained through diffusion dialysis equipment. The recovered acid was added with concentrated sulfuric acid to prepare a stripping agent and returned to stripping. The data of the recovered acid and the diffusion dialysis residue are shown in Table 4.

[0130] Replacement, briquetting, smelting, electrowinning: Take 10L of the residual liquid from the diffusion dialysis, press m zn :m In =1.2:1 Add electrolytic zinc sheet blowing (Zn T≥99%) zinc powder 0.14kg, the replacement reaction temperature is 60°C, the reaction time is 10h, after the reaction is completed, the replacement filtrate is filtered by a filter press, the filter residue is coarse sponge indium, the filtrate is passed through a first-level flotation oil removal device and an activated carbon adsorption device, the TOC after oil removal is 36ppm, and the zinc is returned to the zinc smelting system to recover zinc; the sponge indium is washed with pure water and then pressed into a mass, the moisture content after pressing is 4.2%, the mass content of In in the sponge indium is 81.22%, the pressed sponge indium is slowly put into a smelting pot melted with sodium hydroxide, sodium nitrate and sodium sulfide for smelting, and the smelting temperature is 320°C; after the sponge indium is melted, the reaction is stirred for 30min, the alkali slag is skimmed off, the coarse indium is cast into coarse indium with In≥98%, and 99.99% metallic indium is obtained after electrolysis.

[0131] Table 3 Comparative data of leachate, extract and stripping solution of Example 2

[0132] project <![CDATA[Fe 3+ ]]> <![CDATA[Fe 总 ]]> <![CDATA[As 5+ ]]> <![CDATA[As 总 ]]> In Cu Zn Co <![CDATA[H2SO4]]> Indium sulfate solution 1(g / L) 12.206 12.206 9.531 9.531 1.483 11.2 22.3 0.21 16 Indium sulfate solution 2 (g / L) 10.21 13.41 12.53 18.53 1.58 5.2 20.1 0.11 18 Leachate after reduction 1(g / L) 0.28 12.206 0.352 9.531 1.483 11.2 22.3 0.21 37 Leachate after reduction 2 (g / L) 0.225 13.41 0.35 18.53 1.58 5.2 20.1 0.11 40 Leachate after neutralization 1(g / L) 0.28 12.206 0.352 9.531 1.483 11.2 22.3 0.21 20 Leachate after neutralization 2(g / L) 0.225 13.41 0.35 18.53 1.58 5.2 20.1 0.11 20 Raffinate 1(g / L) 0.014 11.94 0.299 9.486 0.028 11.2 22.3 0.21 22 Raffinate 2(g / L) 0.010 13.117 0.305 18.444 0.031 5.2 20.1 0.11 22 Stripping solution 1(g / L) 0.498 0.504 0.095 0.083 2.751 0 0 0 235 Stripping solution 2 (g / L) 0.400 0.554 0.080 0.157 2.931 0 0 0 235 Extraction rate 1(%) 95.00 2.18 15.06 0.47 98.11 0 0 0 - Extraction rate 2(%) 95.36 2.19 12.86 0.46 98.04 0 0 0 - Stripping rate 1(%) 93.61 94.74 89.62 92.22 94.54 - - - - Stripping rate 2 (%) 93.26 94.38 88.89 92.05 94.60 - - - -

[0133] Note: Serial numbers 1 and 2 in Table 3 correspond to the data of batch 1 and batch 2 respectively.

[0134] Table 4 Comparative data of recovered acid and diffusion dialysis raffinate of Example 2

[0135]

[0136]

[0137] Example 3

[0138] This embodiment provides a method for extracting and separating indium, which is different from the embodiment 1 in that: the extraction organic phase with different volume ratios is used, and the volume ratios of P507:N235:white oil are 20:10:70 (denoted as A), 25:15:60 (denoted as B), 30:20:50 (denoted as C), and 20:15:65 (denoted as D), respectively. The effect of the leaching solution after extraction pretreatment is compared, and the extraction control ratio is 1:1, the extraction level is 3, the mixed extraction time is 5min, and the extraction temperature is 35°C; the stripping agent uses 250g / L sulfuric acid solution, the stripping ratio is 2:1, the stripping level is 3, the mixed stripping time is 10min, and the stripping temperature is 35°C. The parameters of the extract and the stripping solution are shown in Table 5.

[0139] Table 5 Comparative data of the leachate, extract and stripping solution of Example 3

[0140]

[0141]

[0142] Note: The serial numbers A, B, C, and D in Table 5 correspond to the groups with extraction organic phase ratios of A, B, C, and D, respectively.

[0143] Example 4

[0144] This embodiment provides a method for extracting and separating indium, and compares the effects of sulfuric acid solutions of different concentrations as stripping agents. The pretreatment process is the same as in Example 1, and the extraction and stripping processes are as follows:

[0145] The volume ratio of the extracted organic phase is P507: N235: white oil = 20: 10: 70. After being fully mixed, it is pumped into the extraction box and subjected to extraction reaction with the pretreated leaching solution. The extraction control ratio is 1: 1, the extraction level is 3, the mixed extraction time is 5 min, and the extraction temperature is 35 ° C. The organic phase loaded with indium after extraction is washed with pure water, the washing ratio is 10: 1, the washing level is 2, the mixed washing time is 15 min, the washing temperature is 35 ° C, and the washing liquid is returned to the indium-containing liquid. The organic phase loaded with indium is stripped with sulfuric acid solutions of different concentrations, and the stripping rate of indium is calculated. The stripping ratio is 5: 1, the stripping level is 3, the mixed stripping time is 10 min, and the temperature is 35 ° C. After stripping, the empty organic phase is washed with pure water, the washing ratio is 10: 1, the washing level is 5, the mixed washing time is 15 min, the temperature is 35 ° C, and the washing liquid is returned to the indium-containing liquid. The parameters of the extract and stripping solution are shown in Table 6.

[0146] Table 6 Comparative data of the leachate, extract and stripping solution of Example 4

[0147] project <![CDATA[Fe 3+ ]]> <![CDATA[Fe 总 ]]> <![CDATA[As 5+ ]]> <![CDATA[As 总 ]]> In Loaded organic phase (g / L) 0.215 0.293 0.045 0.086 1.549 50g / L sulfuric acid stripping solution (g / L) 0.114 0.165 0.182 0.352 1.180 100g / L sulfuric acid stripping solution (g / L) 0.542 0.753 0.185 0.357 4.124 150g / L sulfuric acid stripping solution (g / L) 0.854 1.196 0.189 0.358 6.639 200g / L sulfuric acid stripping solution (g / L) 0.962 1.321 0.192 0.369 7.058 250g / L sulfuric acid stripping solution (g / L) 1.000 1.384 0.198 0.394 7.327 50g / L sulfuric acid stripping rate (%) 10.59 11.22 80.73 82.34 15.24 100g / L sulfuric acid stripping rate (%) 50.49 51.31 82.18 83.37 53.25 150g / L sulfuric acid stripping rate (%) 79.61 81.52 84.00 83.60 85.72 200g / L sulfuric acid stripping rate (%) 89.71 90.05 85.45 86.34 91.12 250g / L sulfuric acid stripping rate (%) 93.26 94.38 87.78 92.05 94.60

[0148] Comparative Example 1

[0149] This comparative example provides a method for extracting indium, using high-concentration hydrochloric acid as a stripping agent to compare with using sulfuric acid solution as a stripping agent in the present invention, the specific extraction and stripping steps are as follows, and the other processes are the same as in Example 1:

[0150] The volume ratio of the extracted organic phase is P507: N235: white oil = 20: 10: 70. After being fully mixed, it is pumped into the extraction box and subjected to extraction reaction with the pretreated leaching solution; the extraction control phase ratio is 1: 1, the extraction level is 3, the mixed extraction time is 5 min, and the extraction temperature is 35 ° C; the loaded organic phase is washed with pure water, the washing phase ratio is 10: 1, the washing level is 2, the mixed washing time is 15 min, the washing temperature is 35 ° C, and the washing liquid is returned to the indium-containing feed liquid; the stripping agent is stripped with 6 mol / L hydrochloric acid solution and 250 g / L dilute sulfuric acid, respectively, the stripping phase ratio is 2: 1, the stripping level is 3, the mixed stripping time is 10 min, and the stripping temperature is 35 ° C. The parameters of the extract and stripping solution are shown in Table 7.

[0151] Table 7 Comparative data of leachate, extract and stripping solution in comparative example 1

[0152]

[0153] Comparative Example 2

[0154] This comparative example provides a method for extracting indium, using an extraction organic phase composed of 20% P507 + 80% white oil (denoted as ①) and an extraction organic phase composed of 20% P507 + 10% N235 + 70% white oil (denoted as ②) by volume fraction for comparison, and comparing the extraction pre-reduction treatment of the leaching solution, the extraction control phase ratio is 1:1, the extraction level is 3, the mixed extraction time is 5min, and the extraction temperature is 35°C; the stripping agent uses 250g / L sulfuric acid solution, the stripping phase ratio is 2:1, the stripping level is 3, the mixed stripping time is 10min, and the stripping temperature is 35°C; the others are the same as in Example 1. The parameters of the extract and the stripping solution are shown in Table 8.

[0155] Table 8 Comparative data of leachate, extract and stripping solution of Comparative Example 2

[0156]

[0157]

[0158] Comparative Example 3

[0159] This comparative example provides a method for extracting indium, using an extraction organic phase composed of 30% P204 + 70% white oil (denoted as ③) and an extraction organic phase composed of 20% P507 + 10% N235 + 70% white oil (denoted as ④), comparing the extraction pre-reduction and neutralization treatment of the leaching solution, the extraction control phase ratio is 1:1, the extraction level is 3, the mixing time is 5min, and the extraction temperature is 35°C; the stripping agent uses 250g / L sulfuric acid solution, the stripping phase ratio is 2:1, the stripping level is 3, the mixed stripping time is 10min, and the stripping temperature is 35°C; the other steps are the same as in Example 1. The parameters of the extract and the stripping solution are shown in Table 9.

[0160] Table 9 Comparative data of leachate, extract and stripping solution of comparative example 3

[0161]

[0162]

[0163] It can be seen from the above embodiments and comparative examples that the method of the present invention can enrich indium by using an amine extractant and an acidic phosphate extractant to extract after compounding, and can reduce the extraction capacity of iron ions while ensuring the extraction rate of indium, reduce the overall extraction rate of Fe and As, and reduce the difficulty of stripping, ensuring the recovery rate of indium. No hydrochloric acid solution or other chlorine-containing solution is needed to be added during the stripping process, thereby avoiding the generation of chlorine-containing wastewater or waste residue, and the influence of chloride ions on the production system. In addition, by further adjusting the volume ratio of each component of the extracted organic phase and adjusting the concentration of the stripping agent sulfuric acid solution, the extraction and separation effect can be adjusted.

[0164] Comparative Example 1 compares the effects of using sulfuric acid solution as the stripping agent and using concentrated hydrochloric acid as the stripping agent. It can be seen that the present invention can ensure a stripping effect equivalent to that of concentrated hydrochloric acid as the stripping agent without introducing chloride ions, and the stripping rate of indium is above 90%.

[0165] In Comparative Examples 2 and 3, no amine extractant was added. Regardless of whether P204 or P507 was used as the extractant, the difficulty of stripping was greatly increased, and the stripping rate of indium did not exceed 6%.

[0166] In summary, the method of the present invention reduces the extraction capacity of iron ions while ensuring the extraction capacity of indium, and the stripping of indium and iron in the loaded organic phase is easier, and the use of sulfuric acid solution instead of the traditional process must use hydrochloric acid solution or chlorine-containing mixed stripping reagent, avoiding the generation of chlorine-containing wastewater and chlorine-containing waste residue, while avoiding the organic phase poisoning caused by the difficulty of hydrochloric acid stripping iron, and the need to use organic reagents to regenerate the organic phase after poisoning. In addition, the water washing liquid, organic phase, and acid solution produced in the extraction and separation process of the present invention can be recycled, and no wastewater or waste residue is generated, which is in line with the concept of environmental protection.

[0167] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for extracting and separating indium, characterized in that: The following steps are involved: The extracted organic phase is mixed with an indium-containing sulfate solution to extract an organic phase loaded with indium; the indium-loaded organic phase is stripped with a sulfuric acid solution to obtain an indium-containing stripping solution; and indium is obtained by acid separation and replacement; The extraction organic phase comprises an amine extractant, an acidic phosphate extractant and a diluent.

2. The method according to claim 1, characterized in that The volume ratio of the amine extractant, the acidic phosphate extractant and the diluent in the extraction organic phase is (5-30): (10-40): (30-85).

3. The method according to claim 1, characterized in that: The concentration of the sulfuric acid solution is 100-300 g / L.

4. The method according to claim 1 or 2, characterized in that: The amine extractant includes at least one of N235, TOA, and N1923; and / or, the acidic phosphate extractant P507; And / or, the diluent includes at least one of white oil and sulfonated kerosene.

5. The method according to any one of claims 1 to 3, characterized in that: The ratio of the extraction to the stripping is (1-10):1; And / or, the extraction and stripping stages are both 1 to 5 stages; And / or, the temperatures of the extraction and stripping are both 25-65°C.

6. The method according to claim 1, characterized in that The indium-containing sulfate solution is pre-treated by reduction and neutralization before extraction; And / or, the organic phase loaded with indium is subjected to a washing treatment before stripping.

7. The method according to claim 1 or 6, characterized in that: The substance concentration in the indium-containing sulfate solution satisfies the following conditions simultaneously: 1)As 5+ The concentration is ≤0.5g / L; 2)Fe 3+ The concentration is ≤0.3g / L; 3) The concentration of sulfuric acid is 5-40 g / L.

8. The method according to claim 1, characterized in that The indium obtained after the replacement is sponge indium, and metallic indium is obtained through agglomeration, smelting and electrowinning.

9. The method according to claim 1, characterized in that: The organic phase obtained after the stripping is used for cyclic extraction; And / or, the sulfuric acid solution obtained after the acid separation is used for cyclic stripping.

10. A method for recovering indium, characterized in that: The steps of the recovery method include the method for extracting and separating indium as described in any one of claims 1 to 9.

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