Method for separating indium from secondary zinc oxide soot leachate by using hydrophobic deep eutectic solvent

Abstract

The invention discloses a method for separating indium from secondary zinc oxide soot leachate by using a hydrophobic deep-eutectic solvent, which comprises the following steps: S1, preparing the hydrophobic deep-eutectic solvent: heating and melting a hydrogen bond acceptor and a hydrogen bond donor to obtain a deep-eutectic solvent mixture combined in a hydrogen bond form, and taking the deep-eutectic solvent mixture as an extracting agent; s2, adjusting the pH value of a water phase; s3, extracting with a hydrophobic deep-eutectic solvent; s4, reverse extraction of indium: selecting a proper reverse extraction system to perform reverse extraction of indium so as to separate indium from zinc; the prepared hydrophobic deep-eutectic solvent is adopted as an efficient extraction agent, the raw materials for synthesizing the hydrophobic deep-eutectic solvent are wide in source, the preparation process is simple, and the raw materials are low in toxicity and low in harm; by means of the extracting agent, indium can be extracted into an organic phase, iron, aluminum, zinc and other elements are not extracted and are left in extraction raffinate, selective separation of indium is achieved, reverse extraction is conducted on the loaded organic phase through low-concentration sulfuric acid, indium can be reversely extracted into a water phase, an indium-rich solution is obtained, and an indium product can be obtained through electrolysis or precipitation transformation.

Description

Technical Field

[0001] The present invention belongs to the technical field of non-ferrous metal metallurgy, and particularly relates to a method for separating indium from the leaching solution of secondary zinc oxide soot by using a hydrophobic deep eutectic solvent. Background Technique

[0002] As a key strategic metal resource, indium has irreplaceable applications in high-value-added fields such as ITO films, semiconductor devices, photovoltaic cells, and special alloys due to its unique optoelectronic properties. In the zinc smelting process, secondary zinc oxide soot, as an important secondary resource, has an indium content of up to 0.1%-0.3% (mass fraction), and has become one of the main raw material sources for indium resource recovery. The current industrial extraction process mainly uses hydrometallurgy technology, and its main process flow usually includes three links: leaching, separation and purification, and transformation. However, during the leaching process in sulfuric acid medium, metal ions such as zinc (Zn2+), iron (Fe3+), aluminum (Al3+), antimony (Sb 3 +), arsenic (As 3 +) are leached simultaneously with indium (In3+), resulting in a complex leaching solution system and difficult separation.

[0003] At present, the main method for separating indium from the leaching solution of secondary zinc oxide soot is acidic phosphorus extraction, including extraction with di(2-ethylhexyl) phosphate (P204) and 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester (P507), etc. Acidic phosphorus extractants have strong extraction ability for trivalent metal ions such as In 3+ etc. Therefore, in the actual extraction process, Al 3+ , Fe 3+ are also extracted into the organic phase. To improve the purity of indium, a complex washing process is required to reduce the content of these two elements in the organic phase. At the same time, due to the strong extraction ability of acidic phosphorus extractants such as P204 and P507 for In 3+ , it is difficult to strip with sulfuric acid. For example, after 30% of P204 extracts In 3+ , even using 3 mol / L sulfuric acid, the single-stage stripping rate is less than 50%. Therefore, 6 mol / L hydrochloric acid complex stripping is often used. However, the use of hydrochloric acid causes relatively serious equipment corrosion and requires dechlorination in the subsequent process. Moreover, when using acidic phosphorus extraction, kerosene needs to be added as a diluent in the organic phase, which poses a risk of flammability. Therefore, the present invention uses a hydrophobic deep eutectic solvent (DES) to separate indium from the leaching solution of secondary zinc oxide soot. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for separating indium from the leaching solution of secondary zinc oxide soot by using a hydrophobic deep eutectic solvent, so as to solve the problems raised in the above background technique.

[0005] To achieve the above object, the present invention provides the following technical solutions: A method for separating indium from the leaching solution of secondary zinc oxide soot using a hydrophobic deep eutectic solvent, the specific steps including: S1: Preparation of a hydrophobic deep eutectic solvent:

[0006] The DES is composed of a hydrogen bond donor and a hydrogen bond acceptor, and the molar ratio between the two is between 1:1 and 4:1; the hydrogen bond acceptor and the hydrogen bond donor are heated and melted to obtain a deep eutectic solvent mixture bound by hydrogen bonds as the extractant;

[0007] S2: Adjust the pH of the aqueous phase:

[0008] Add sulfuric acid / sodium hydroxide solution to the water in the leaching solution of secondary zinc oxide soot to adjust the pH;

[0009] S3: Extraction with a hydrophobic deep eutectic solvent:

[0010] Use the prepared hydrophobic deep eutectic solvent as the extraction organic phase, and the metal ion solution after adjusting the pH as the aqueous phase, and extract according to a certain phase ratio;

[0011] S4: Stripping of indium:

[0012] Select a suitable stripping system to strip indium to separate indium from zinc.

[0013] Preferably, the hydrophobic deep eutectic solvent in S1 is composed of a hydrogen bond donor and a hydrogen bond acceptor, and the hydrogen bond donor is any one of caproic acid, octanoic acid, decanoic acid, and lauric acid; the hydrogen bond acceptor is any one of menthol and phenol.

[0014] Preferably, the specific production steps of the hydrophobic deep eutectic solvent in S1 are: Mix the hydrogen bond donor and the hydrogen bond acceptor in proportion, then place the mixture on a constant temperature heating magnetic stirrer, heat and stir at 60°C - 80°C until a uniform and transparent liquid is formed; the heating and stirring time is 10 - 20 min; the stirring uses a polytetrafluoroethylene rotor with a rotation speed of 1000 revolutions per minute.

[0015] Preferably, the pH of the extraction feed liquid in S2 is adjusted to 1 - 3 using a sulfuric acid solution.

[0016] Preferably, in S3, the extraction phase ratio, i.e., organic phase:aqueous phase, is 1:1 - 1:4; the extraction time using a vortex mixer is 3 min.

[0017] Preferably, the stripping system in S4 is a 0.5 - 1 mol / L sulfuric acid solution; the stripping phase ratio, i.e., organic phase:aqueous phase, is 1:1 - 3:1.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The present invention uses the prepared hydrophobic deep eutectic solvent as an efficient extractant. The raw materials for synthesizing the hydrophobic deep eutectic solvent are widely sourced, the preparation process is simple, and the raw materials are of low toxicity and less harm. Using this extractant, indium can be extracted into the organic phase, while other elements such as iron, aluminum, and zinc are not extracted and remain in the raffinate, realizing the selective separation of indium. The loaded organic phase is stripped with low-concentration sulfuric acid, enabling indium to be stripped into the aqueous phase to obtain an indium-rich solution. Through electrolysis or precipitation transformation, indium products can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic flow chart of the method of the present invention; DETAILED DESCRIPTION OF THE EMBODIMENTS

[0021] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0022] Example 1:

[0023] A method for separating indium from the leaching solution of secondary zinc oxide ash using a hydrophobic deep eutectic solvent,

[0024] Using menthol as the hydrogen bond acceptor and lauric acid as the hydrogen bond donor to prepare a hydrophobic deep eutectic solvent for extraction and separation of indium-containing zinc leaching solution. The specific steps are as follows:

[0025] Take menthol and lauric acid, mix them in a molar ratio of 1:1, heat and stir at 80 °C for 20 min to obtain hydrophobic DES1, which is used as the extractant. Adjust the pH of the secondary zinc oxide leaching solution to 2 as the aqueous phase. At 30 °C and a phase ratio of 1:1, under the condition of vortex mixing for 3 min and centrifugal separation, the metal ion concentrations in the aqueous phase and the organic phase of the aqueous solution are measured by ICP-OES, and the extraction rate is calculated therefrom. The results are shown in Table 1. It can be seen that the prepared hydrophobic DES has good selectivity for indium and can achieve effective separation of indium. The indium in the loaded organic phase is stripped with 1.0 mol / L sulfuric acid. Under the condition of a phase ratio of 1:2, vortex mixing is carried out for 3 min, and the two phases are centrifugally separated. The ion concentration of In 3+ is measured by ICP-OES, and the stripping rate is calculated. The single-stage stripping rate of In 3+ is 90.8%.

[0026] Table 1 Single-stage extraction rate of menthol-lauric acid DES for each element

[0027]

[0028] Example 2:

[0029] Using phenol as the hydrogen bond acceptor and octanoic acid as the hydrogen bond donor, a hydrophobic deep eutectic solvent was prepared for the extraction and separation of indium-containing zinc leaching solution. The specific steps are as follows:

[0030] Take phenol and octanoic acid and mix them in a molar ratio of 1:4, heat and stir at 60 °C for 10 min to obtain hydrophobic DES2, which is used as the extractant. Adjust the pH of the secondary zinc oxide leaching solution to 1 as the aqueous phase. At 30 °C and a phase ratio of 1:4, under the condition of shaking and mixing with a vortex mixer for 3 min, centrifugally separate, and use ICP-OES to measure the metal ion concentrations in the aqueous phase and organic phase of the aqueous solution, and calculate the extraction rate of each element. The results are shown in Table 2. It can be seen that the prepared hydrophobic DES has good selectivity for indium and can effectively separate indium. The indium in the loaded organic phase was back-extracted with 0.5 mol / L sulfuric acid. Under the condition of a phase ratio of 1:1, shake and mix with a vortex mixer for 3 min, centrifugally separate the two phases, and use ICP-OES to measure the In 3+ ion concentration and calculate the back-extraction rate to obtain an In 3+ single-stage back-extraction rate of 85.2%.

[0031] Table 1 Single-stage extraction rate of phenol-octanoic acid DES for each element

[0032]

[0033] Although the embodiments of the present invention have been shown and described, see the above detailed description. For those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for separating indium from the leaching solution of secondary zinc oxide soot using a hydrophobic deep eutectic solvent, characterized in that: The specific steps include: S1: Prepare a hydrophobic deep eutectic solvent: The DES is composed of a hydrogen bond donor and a hydrogen bond acceptor, and the molar ratio between the two is between 1:1 and 4:1; the hydrogen bond acceptor and the hydrogen bond donor are heated and melted to obtain a deep eutectic solvent mixture bound by hydrogen bonds as the extractant; S2: Adjust the pH of the aqueous phase: Add sulfuric acid / sodium hydroxide solution to the water of the leaching solution of secondary zinc oxide ash to adjust the pH; S3: Extract with the hydrophobic deep eutectic solvent: Use the prepared hydrophobic deep eutectic solvent as the extraction organic phase, and use the metal ion solution after adjusting the pH as the aqueous phase for extraction according to a certain phase ratio; S4: Back-extraction of indium: Select a suitable back-extraction system to back-extract indium to separate indium from zinc.

2. The method for separating indium from the leaching solution of zinc suboxide soot using a hydrophobic deep eutectic solvent according to claim 1, characterized in that: The hydrophobic deep eutectic solvent in S1 is composed of a hydrogen bond donor and a hydrogen bond acceptor. The hydrogen bond donor is any one of caproic acid, caprylic acid, capric acid, and lauric acid; the hydrogen bond acceptor is any one of menthol and phenol.

3. The method for separating indium from the leaching solution of secondary zinc oxide soot using a hydrophobic deep eutectic solvent according to claim 2, characterized in that: The specific production steps of the hydrophobic deep eutectic solvent in S1 are as follows: Mix the hydrogen bond donor and the hydrogen bond acceptor in proportion, then place the mixture on a constant temperature heating magnetic stirrer, heat and stir at 60°C - 80°C until a uniform and transparent liquid is formed; the heating and stirring time is 10 - 20 min; use a polytetrafluoroethylene rotor for stirring, and the rotation speed is 1000 revolutions per minute.

4. The method for separating indium from the leaching solution of zinc suboxide soot using a hydrophobic deep eutectic solvent according to claim 1, wherein: The pH of the extraction feed liquid in S2 is adjusted to 1 - 3 using a sulfuric acid solution.

5. The method for separating indium from the leaching solution of zinc suboxide soot using a hydrophobic deep eutectic solvent according to claim 1, characterized in that: In S3, the extraction phase ratio, i.e., organic phase:aqueous phase, is 1:1 - 1:4; the extraction time using a vortex mixer is 3 min.

6. The method for separating indium from the leaching solution of zinc suboxide soot using a hydrophobic deep eutectic solvent according to claim 1, characterized in that: The back-extraction system in S4 is a 0.5 - 1 mol / L sulfuric acid solution; the back-extraction phase ratio, i.e., organic phase:aqueous phase, is 1:1 - 3:1.

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