Method for separating iron and copper with high selectivity and application thereof

Abstract

The application provides a method for high-selectivity separation of iron and copper and application thereof; the method for high-selectivity separation of iron and copper comprises the following steps: S1, providing a complexing agent-alkali mixed solution; the complexing agent-alkali mixed solution contains a metal ion complexing agent and an alkaline substance; S2, mixing and treating an iron-copper mixed solution and the complexing agent-alkali mixed solution to obtain a reaction solution; the iron-copper mixed solution contains ferric ion, ferrous ion and copper ion; the molar ratio of the metal ion complexing agent to the copper ion is 1.5-3:1; the molar ratio of the alkaline substance to iron in the iron-copper mixed solution is 4-8:1; the mixing and treating is carried out at a temperature of 10-45 DEG C; S3, performing solid-liquid separation on the reaction solution to obtain a copper-containing separation solution and a ferric solid substance. The application effectively realizes high-selectivity separation of iron and copper in the iron-copper mixed solution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of heavy metal separation, and particularly relates to a method for high-selectivity separation of iron and copper and application. BACKGROUND

[0002] Iron is an important metal in the fields of environment and energy. At present, the recycling of iron resources has become an important issue of concern. However, the zinc leaching solution generated in the process of zinc hydrometallurgy has high content of heavy metal elements such as copper and zinc; the combination of magnetite method and microfluidic technology can realize the separation of iron and zinc and the resource utilization of iron. Further, considering that the copper ions also produce a large amount of iron precipitation slag hazardous waste in the subsequent iron precipitation process, causing waste of metal resources and great environmental pollution risk. In view of this problem, it is of great significance to develop a method for high-selectivity separation of iron and copper in zinc hydrometallurgy leaching solution.

[0003] The traditional separation methods of heavy metals include solvent extraction, ion exchange and chemical precipitation, etc. Among them, the solvent extraction method is complex in operation, time-consuming and easy to cause environmental pollution. The ion exchange method has limited adsorption capacity for target metals and high regeneration cost. The chemical precipitation method has low separation efficiency of heavy metals.

[0004] Although certain progress has been made in the separation of iron and multi-metals by the iron precipitation method in the related art, there are still some limitations. Some separation methods (such as chemical precipitation method, solvent extraction method and electrolysis method, etc.) require a large amount of reagents or high energy consumption process conditions, which limits the feasibility of its large-scale production, and there are still problems such as high heavy metal doping in the obtained iron precipitation product, which is difficult to be resource utilization, etc., which need to be further improved and optimized.

[0005] Therefore, it is necessary to provide a method for high-selectivity separation of iron and copper and application, so as to solve or at least alleviate the technical problem of how to high-selectivity separate iron and copper. SUMMARY

[0006] The main purpose of the present application is to provide a method for high-selectivity separation of iron and copper and application, which aims to solve or at least alleviate the technical problem of how to high-selectivity separate iron and copper.

[0007] To achieve the above-mentioned purpose, the present application provides a method for high-selectivity separation of iron and copper, comprising the steps of:

[0008] S1, providing a complexing agent-alkali mixed solution;

[0009] The complexing agent-alkali mixed solution contains metal ion complexing agent and alkaline substance;

[0010] S2, mixing and treating the iron-copper mixed solution and the complexing agent-alkali mixed solution to obtain a reaction solution;

[0011] The iron-copper mixed solution contains ferric ions, ferrous ions and copper ions;

[0012] The molar ratio of the metal ion complexing agent to the copper ions is 1.5-3:1.

[0013] The molar ratio of the alkaline substance to the iron element in the iron-copper mixed solution is 4-8:1.

[0014] The mixing treatment is carried out at a temperature of 10-45℃.

[0015] S3, solid-liquid separation is carried out on the reaction solution to obtain a copper-containing separation solution and a ferric sediment solid.

[0016] Further, the metal ion complexing agent comprises a tetraamine organic substance.

[0017] Further, the tetraamine organic substance comprises triethylenetetramine.

[0018] Further, the preparation method of the complexing agent-alkali mixed solution comprises: mixing the metal ion complexing agent and the alkaline substance in water to obtain the complexing agent-alkali mixed solution.

[0019] Further, the alkaline substance comprises one or more of sodium hydroxide, potassium hydroxide and ammonia.

[0020] Further, the concentration of the metal ion complexing agent in the complexing agent-alkali mixed solution is 0.1-0.3 mol / L, and the concentration of the alkaline substance in the complexing agent-alkali mixed solution is 0.4-0.8 mol / L.

[0021] In the iron-copper mixed solution, the total concentration of the ferrous ions and the ferric ions is 0.05-0.2 mol / L, and the concentration of the copper ions is 0.05-0.2 mol / L; wherein the molar ratio of the ferrous ions to the ferric ions is 1:1-5.

[0022] Further, the mixing treatment lasts for no less than 3h, the rotation speed of the mixing treatment is 300-700 rpm, and the mixing treatment is carried out in a closed condition.

[0023] Further, the ferric ions exist in the form of ferric sulfate, the ferrous ions exist in the form of ferrous sulfate, and the copper ions exist in the form of copper sulfate.

[0024] Further, the step S3 further comprises: sequentially washing and drying the solid product obtained through the solid-liquid separation to obtain the ferric sediment solid.

[0025] The application further provides a use of the high-selectivity iron-copper separation material in the preparation of a weak-crystal high-iron substance.

[0026] Compared with the prior art, the present invention has at least the following advantages:

[0027] This invention enables highly selective separation of iron and copper. Specifically, the separation method provided by this invention involves adding a complexing agent-alkali mixture to an iron-copper mixture and stirring to react. By employing a metal ion complexing agent and controlling the ratio of the complexing agent to copper ions, the reaction temperature, and the amount of alkali, an excellent reaction environment for capturing copper ions—a low-temperature, low-alkali environment—is provided. After solid-liquid separation, the resulting product exhibits an iron content of up to 55.50% in the solid phase and a copper content as low as 0.88%. The copper content in the slag is significantly better than that of existing iron slag, achieving resource recycling and reducing heavy metal pollution to the environment. Unexpectedly, in this invention, under a low-alkali environment, the metal ion complexing agent selectively complexes with copper ions and effectively promotes the precipitation of iron ions. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0029] Figure 1 The X-ray diffraction patterns of the iron-sinking products in Example 1 and Comparative Example 2 of this invention are shown, where Intensity (au) represents intensity, 2θ (°) represents twice the diffraction angle, and Magnetite PDF#19-0629 represents the standard card of the magnetite mineral phase.

[0030] Figure 2 The image shows the elemental composition of the iron deposited products in Example 1 and Comparative Examples 1-2 of this invention; where the bars represent the iron and copper contents, and the stars represent the iron-copper ratio.

[0031] Figure 3 The image shows the elemental composition of the iron deposits in Comparative Examples 3-4 of this invention; where the bars represent the iron and copper contents, and the stars represent the iron-copper ratio.

[0032] Figure 4 The image shows the elemental composition of the iron deposits in Comparative Examples 5-7 of this invention; where the bars represent the iron and copper contents, and the stars represent the iron-copper ratio.

[0033] Figure 5 The Fourier transform infrared spectra of the iron-containing products in Example 1 and Comparative Example 2 of this invention are shown.

[0034] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0037] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention. The copper content, iron content, and iron deposition rate in this invention are all mass percentages.

[0038] To achieve highly selective iron-copper separation and solve the technical problems of high energy consumption, high cost, high copper ion doping in iron slag, and low iron resource utilization efficiency during the separation process, this invention places an iron-copper mixture in a reaction vessel, adds a complexing agent-alkali mixture, seals it, and stirs the reaction. During the experiment, only the appropriate ratio of complexing agent to copper ions, alkali amount, and reaction temperature need to be controlled to obtain iron slag products with low copper doping.

[0039] Specifically, the present invention provides a method for highly selectively separating iron and copper, comprising the following steps:

[0040] S1 provides a complexing agent-alkali mixture.

[0041] The complexing agent-alkali mixture contains a metal ion complexing agent and an alkaline substance, wherein the metal ion complexing agent includes a tetraamine organic compound; for example, the tetraamine organic compound may include triethylenetetramine.

[0042] In this invention, the preparation method of the complexing agent-alkali mixture may include: mixing the metal ion complexing agent and the alkaline substance in water (the specific reaction temperature can be room temperature) to obtain the complexing agent-alkali mixture.

[0043] In this invention, the concentration of the metal ion complexing agent in the complexing agent-alkali mixture can be 0.1-0.3 mol / L, preferably 0.15-0.3 mol / L; the concentration of the alkaline substance in the complexing agent-alkali mixture can be 0.4-0.8 mol / L, preferably 0.4-0.6 mol / L; the alkaline substance is used to provide an alkaline environment, and the alkaline substance may include one or more of sodium hydroxide, potassium hydroxide, and ammonia.

[0044] It should be noted that in this invention, high alkalinity conditions are not conducive to the separation of iron and copper. When there is excess alkali, triethylenetetramine and alkali will compete for copper ions simultaneously, resulting in the precipitation reaction of copper hydroxide, reducing the contact opportunity between triethylenetetramine and copper ions, thereby weakening the complexation effect between the two. Although the Fe / Cu ratio in Comparative Example 4 is improved compared to Comparative Example 3, it still cannot achieve the technical effect of this invention. When the amount of alkali is too low, iron precipitation cannot be completely achieved, and a large number of amino groups tend to be protonated, weakening the coordination ability of TETA. Therefore, it is necessary to control the amount of alkaline substance.

[0045] S2, the iron-copper mixture and the complexing agent-alkali mixture are mixed to obtain a reaction solution.

[0046] This invention does not limit the specific source of the iron-copper mixture. Exemplarily, the iron-copper mixture can originate from the leaching solution of hydrometallurgical zinc smelting. The iron-copper mixture contains ferric ions, ferrous ions, and copper ions; the ferric ions may exist in the form of ferric sulfate, the ferrous ions may exist in the form of ferrous sulfate, and the copper ions may exist in the form of copper sulfate.

[0047] In the iron-copper mixture, the total concentration of ferrous ions and ferric ions can be 0.05-0.2 mol / L, and the concentration of copper ions can be 0.05-0.2 mol / L; wherein the molar ratio of ferrous ions and ferric ions can be 1:1-5; in this invention, the molar ratio of iron (ferrous ions and ferric ions) and copper (copper ions) can be 0.8-4:1.

[0048] To achieve highly selective separation of iron and copper, the molar ratio of the metal ion complexing agent to the copper ions is 1.5-3:1, and the molar ratio of iron (ferrous ions and ferric ions) in the alkaline substance and the iron-copper mixture is 4-8:1, preferably 4-6:1. It is worth noting that the ratio of the metal ion complexing agent to the copper ions is an important parameter affecting the copper ion complexing effect.

[0049] Taking triethylenetetramine as an example, since triethylenetetramine undergoes rapid complexation with copper ions to form a stable four-coordinate water-soluble complex, and the stoichiometric ratio of nitrogen atoms to copper ions is 4:1, but only two amino groups in a triethylenetetramine molecule have strong complexation with copper ions; therefore, the optimal molar ratio of triethylenetetramine to copper ions is 2:1.

[0050] The structural formula of triethylenetetramine is as follows:

[0051]

[0052] In the specific implementation process, the duration of the mixing treatment is not less than 3 hours, preferably 3 hours to 5 days; in this invention, the rotation speed of the mixing treatment can be 300-700 rpm, the mixing treatment is carried out at a temperature of 10-45℃ (specifically room temperature), and can be carried out under closed conditions.

[0053] In this invention, reaction temperature is a key factor affecting the complexation reaction. High-temperature environments can cause the coordination bonds between the complexing agent and the target metal to break, leading to complex breakdown and significantly weakening the complexation effect. By adjusting the temperature to create the optimal environment for the triethylenetetramine complexation of copper ions, it is beneficial to reduce the entry of copper ions into the internal structure of the iron precipitate product and reduce the presence of copper impurities in the final product.

[0054] To ensure the effective progress of the reaction, both the iron-copper mixture and the complexing agent-alkali mixture can be purged of oxygen from the solution by passing nitrogen gas for 30 minutes before the reaction to prevent the ferrous iron from being oxidized.

[0055] S3, perform solid-liquid separation on the reaction solution to obtain a copper-containing separation liquid and precipitated iron solid (precipitated iron product with low copper doping).

[0056] Step S3 may further include: sequentially washing and drying the solid product obtained from the solid-liquid separation (e.g., solid-phase freeze drying) to obtain the precipitated iron solid. The washing process may include: rinsing the solid product obtained from the solid-liquid separation with deionized water 2-4 times by vacuum filtration, each rinse lasting 1-3 minutes; by repeatedly washing with deionized water, impurities and residues on the surface of the precipitated iron product are effectively removed, improving the purity of the product.

[0057] Since the complexing agent used in this invention is an organic reagent, it may remain on the surface of the iron precipitation product during the reaction process, which may have a negative impact on the performance and application of the product; therefore, after the reaction is completed, the solid product separated from the solid liquid can be washed and dried.

[0058] Since the iron precipitate product obtained by this invention has extremely small particle size, the solid-liquid separation method in this invention may include centrifugal separation.

[0059] It should be noted that, in response to the need for selective separation of iron and copper in hydrometallurgical zinc leaching solutions, improved traditional methods or complexing agents with high selectivity for capturing copper ions offer new approaches for the effective separation of iron and copper. Specific complexing agents can form stable complexes with target metal ions under mild conditions, thereby achieving efficient separation of iron and copper, improving iron resource utilization, and reducing environmental pollution.

[0060] The separation method provided by this invention does not require a high-temperature, high-alkali environment. Under room temperature and low-alkali conditions, it achieves iron-copper separation through the regulatory effect of a specific type of metal ion complexing agent. Specifically, iron ions rapidly precipitate, while copper ions remain in the solution as a complex. When the metal ion complexing agent comes into contact with copper ions, the lone pair electrons in the amino group can form coordinate bonds with the copper ions, resulting in a stable complex between the metal ion complexing agent and the copper ions. Simultaneously, the formation of these coordinate bonds lowers the free energy of the complex, further increasing its stability, thereby achieving highly selective separation of iron and copper.

[0061] The separation method provided by this invention aims to add a complexing agent-alkali mixture to an iron-copper mixture and stir to react, then separate the resulting product into solid and liquid phases. The solid phase contains 55.50% iron and 0.88% copper, with a small amount of slag. The copper content in the slag is significantly better than that of existing iron slag, thus realizing resource recycling and reducing heavy metal pollution to the environment.

[0062] The present invention also provides an application of highly selective separation of iron and copper as described above in the preparation of weakly crystalline high-iron materials.

[0063] The following are specific examples of the present application:

[0064] Example 1 (TETA:Cu = 2:1, NaOH = 0.5M, T = 25°C, t = 4h)

[0065] 1. At room temperature, ferric sulfate, copper sulfate, and ferrous sulfate solids are stirred evenly in water (ferric sulfate and copper sulfate are mixed first, and oxygen is removed to ensure the valence state of ferrous ions), resulting in an iron-copper mixture. In the iron-copper mixture, the total concentration of ferrous and ferric ions is 0.1 mol / L, and the concentration of copper ions is 0.1 mol / L; the molar ratio of ferrous ions to ferric ions is 1:2.

[0066] At room temperature, triethylenetetramine (metal ion complexing agent: TETA) and sodium hydroxide (NaOH) were stirred evenly in water to obtain a TETA-NaOH mixture (complexing agent-alkali mixture). In the TETA-NaOH mixture, the concentration of the complexing agent TETA was 0.2 mol / L, and the concentration of NaOH was 0.5 mol / L.

[0067] Both the iron-copper mixture and the TETA-NaOH mixture were subjected to oxygen removal treatment for 30 minutes before the reaction.

[0068] 2. Measure 50 mL of the iron-copper mixture into a reaction vessel (Eragonal flask), add 50 mL of TETA-NaOH mixture, seal, and stir. The stirring rate is 500 rpm, and the reaction time is 4 hours. The reaction vessel is placed in a 25°C water bath environment (reaction temperature). In the above reaction, the molar ratio of the complexing agent to copper ions is 2:1, i.e., TETA:Cu = 2:1.

[0069] After the reaction was completed, centrifugation was performed to obtain a copper-containing separation liquid (supernatant) and a solid product. The solid product was washed and freeze-dried to obtain a precipitated iron product with low copper doping. The washing process was as follows: rinse with deionized water, repeat 3 times, each rinse for 2 minutes.

[0070] 3. Test Results:

[0071] The determination and calculation process of copper and iron content is as follows: 0.01g of precipitated iron product is weighed and dissolved in 2mL of concentrated hydrochloric acid (AR, 36.0%~38.0%), diluted and then measured by inductively coupled plasma optical emission spectrometry (ICP-OES); the calculated mass concentration ratio of copper in the precipitated iron product is the copper content, and the mass concentration ratio of iron in the precipitated iron product is the iron content.

[0072] like Figure 1 As shown, the X-ray spectrum of the iron-laden product in this embodiment exhibits very weak characteristic peaks at 2θ of 35.64° and 62.55°, corresponding to the (311) and (440) crystal planes, respectively, indicating a weakly crystalline state. Compared to Comparative Example 2, the presence of TETA significantly inhibits the crystal structure of magnetite, suppressing the transformation of the iron precursor into magnetite. The weakening of the magnetite crystal structure is also one of the reasons for reducing the entry of copper ions into the iron-laden product.

[0073] like Figure 2 As shown, in this embodiment, the copper content in the precipitated iron product is 0.88%, the iron content is 55.50%, and the Fe / Cu ratio is 63.07.

[0074] like Figure 5 As shown, the Fourier transform infrared spectrum of the iron deposition product in this embodiment is at a wavenumber of 1632 cm⁻¹. -1A vibrational zone with adsorbed water was observed nearby, at 1478 cm. -1 and 1349cm -1 The nearby absorption peaks correspond to the OH stretching vibration of goethite, 1112–970 cm⁻¹ -1 The nearby absorption peak corresponds to the OH stretching vibration of fibrous ore, while the peak at wavenumber 590 cm⁻¹ corresponds to the absorption peak at wavenumber 590 cm⁻¹. -1 Compared to Comparative Example 2, the characteristic peaks of magnetite gradually disappeared. The reason is that other small organic molecules (such as -CH2) in the TETA structure that do not complex with copper ions are coated on the surface of the precursor that forms magnetite, inhibiting the conversion of the iron precursor to magnetite, thus weakening the characteristic absorption peaks of magnetite.

[0075] Comparative Example 1

[0076] Compared with Example 1, the molar ratio of complexing agent TETA to copper ions in this comparative example was adjusted to 1:1, while other conditions remained unchanged; specifically, in this comparative example, the concentration of TETA in the TETA-NaOH mixed solution was adjusted to 0.1 mol / L.

[0077] like Figure 2 As shown, in this comparative example, the copper content in the precipitated iron product was 5.18%, the iron content was 50.17%, and the Fe / Cu ratio was 9.69. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0078] Comparative Example 2

[0079] Compared with Example 1, no complexing agent TETA was added in this comparative example, and other conditions remained unchanged; that is, TETA in the TETA-NaOH mixture was omitted, and the TETA-NaOH mixture was replaced with a NaOH solution with a concentration of 0.5 mol / L.

[0080] like Figure 1 As shown, the X-ray spectrum of the iron-laden product in this comparative example has characteristic peaks at 2θ of 36.57° and 62.55°, corresponding to the (311) and (440) crystal planes, respectively, which are consistent with the PDF card (PDF#19-0629) of magnetite, indicating that magnetite is formed in the iron-laden product.

[0081] like Figure 2 As shown, in this comparative example, the copper content in the precipitated iron product was 16.94%, the iron content was 40.93%, and the Fe / Cu ratio was 2.42. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0082] like Figure 5 As shown, the Fourier transform infrared spectrum of the iron-deposited product in this comparative example is at a wavenumber of 590 cm⁻¹. -1The characteristic peaks of magnetite were identified at a wavenumber of 1632 cm⁻¹. -1 The vibratory zone exhibits adsorbed water, with wave numbers ranging from 1112 to 970 cm⁻¹. -1 The nearby absorption peaks correspond to the OH stretching vibration of fibrous ore.

[0083] Comparative Example 3

[0084] Compared with Example 1, the concentration of NaOH in the TETA-NaOH mixture in this comparative example was adjusted to 1 mol / L, while other conditions remained unchanged.

[0085] like Figure 3 As shown, in this comparative example, the copper content in the precipitated iron product was 6.17%, the iron content was 48.61%, and the Fe / Cu ratio was 7.88. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0086] Comparative Example 4

[0087] Compared with Example 1, the concentration of NaOH in the TETA-NaOH mixture in this comparative example was adjusted to 3 mol / L, while other conditions remained unchanged.

[0088] like Figure 3 As shown, in this comparative example, the copper content in the precipitated iron product was 3.79%, the iron content was 48.81%, and the Fe / Cu ratio was 12.88. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0089] Comparative Example 5

[0090] Compared with Example 1, this comparative example adjusts the reaction temperature to 60°C (the reaction vessel is in a 60°C water bath environment), while keeping other conditions unchanged.

[0091] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product was 4.12%, the iron content was 53.10%, and the Fe / Cu ratio was 12.89. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0092] Comparative Example 6

[0093] Compared with Example 1, this comparative example adjusts the reaction temperature to 90°C (the reaction vessel is in a 90°C water bath environment), while keeping other conditions unchanged.

[0094] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product was 4.20%, the iron content was 50.50%, and the Fe / Cu ratio was 12.01. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0095] Comparative Example 7

[0096] Compared with Comparative Example 6, this comparative example omits the complexing agent TETA (replacing the TETA-NaOH mixture with a 0.5 mol / L NaOH solution), while keeping other conditions unchanged.

[0097] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product was 12.92%, the iron content was 46.12%, and the Fe / Cu ratio was 3.57. The Fe / Cu ratio was much lower than that in Example 1, indicating poor iron-copper separation.

[0098] Comparative Example 8

[0099] Compared with Example 1, the metal ion complexing agent in this example was adjusted to mercaptoethylamine (C2H7NS), the TETA-NaOH mixture was adjusted to C2H7NS-NaOH mixture, the iron-copper molar ratio was 5:1, the molar ratio of complexing agent to copper ions was 1:1, the NaOH concentration was 1 mol / L, the reaction temperature was 60℃, the reaction time was 30 min, and other conditions remained unchanged.

[0100] Specifically, in this comparative example:

[0101] In the iron-copper mixture, the total concentration of ferrous and ferric ions is 0.05 mol / L, and the concentration of copper ions is 0.01 mol / L; the molar ratio of ferrous ions to ferric ions is 1:2.

[0102] In the C2H7NS-NaOH mixture, the concentration of the complexing agent C2H7NS is 0.01 mol / L, and the concentration of NaOH is 1 mol / L.

[0103] The amount of iron-copper mixture added is 50 mL, and the amount of C2H7NS-NaOH mixture added is 50 mL.

[0104] In this comparative example, the copper content in the precipitated iron product was 5.35%, the iron content was 49.46%, and the Fe / Cu ratio was 9.25.

[0105] Comparative Example 9

[0106] Compared with Comparative Example 8, this comparative example omits the complexing agent C2H7NS (replacing the C2H7NS-NaOH mixture with a 1 mol / L NaOH solution), while keeping other conditions unchanged.

[0107] In this comparative example, the copper content in the precipitated iron product was 7.47%, the iron content was 52.91%, and the Fe / Cu ratio was 7.09, indicating poor iron-copper separation.

[0108] Comparative Example 10

[0109] Compared with Example 1, this comparative example only changed the complexing agent triethylenetetramine (TETA) to the complexing agent mercaptoethylamine (C2H7NS), and the TETA-NaOH mixture to the C2H7NS-NaOH mixture, while keeping other conditions unchanged.

[0110] In this comparative example, the copper content in the precipitated iron product was 16.03%, the iron content was 31.64%, and the Fe / Cu ratio was 1.97, indicating poor iron-copper separation.

[0111] Comparative Example 11

[0112] Compared with Comparative Example 10, this comparative example only adjusted the molar ratio of complexing agent to copper ions to 8:1, while keeping other conditions unchanged; that is, the concentration of mercaptoethylamine (C2H7NS) in the C2H7NS-NaOH mixture was adjusted to 0.8 mol / L.

[0113] In this comparative example, the copper content in the precipitated iron product was 0.97%, the iron content was 50.11%, and the Fe / Cu ratio was 51.82. Compared with Comparative Example 10, the iron-copper separation effect was improved; however, it still did not reach the separation effect of Example 1.

[0114] Comparative Example 12

[0115] Compared with Example 1, this comparative example only changed the complexing agent triethylenetetramine (TETA) to the complexing agent disodium ethylenediaminetetraacetate (EDTA-2Na), and the TETA-NaOH mixture to the EDTA-2Na-NaOH mixture, while keeping other conditions unchanged.

[0116] In this comparative example, the copper content in the precipitated iron product was 2.04%, the iron content was 37.03%, and the Fe / Cu ratio was 18.15, indicating poor iron-copper separation.

[0117] Comparative Example 13

[0118] Compared with Comparative Example 12, this comparative example only adjusted the molar ratio of complexing agent to copper ions to 4:1, while keeping other conditions unchanged; that is, the concentration of disodium ethylenediaminetetraacetate (EDTA-2Na) in the EDTA-2Na-NaOH mixture was adjusted to 0.4 mol / L.

[0119] In this comparative example, the solution after the reaction is still a dark green solution, which cannot achieve the purpose of iron precipitation. Therefore, copper-iron separation cannot be carried out.

[0120] Analytical Example 1

[0121] The following are the results of iron and copper content, Fe / Cu ratio, and iron deposition rate of the iron-deposited products in various cases of this invention:

[0122] Table 1. Results of iron and copper content, Fe / Cu ratio, and iron deposition rate of the precipitated iron products.

[0123]

[0124]

[0125] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A method for highly selectively separating iron and copper, characterized in that, Including the following steps: S1 provides a complexing agent-alkali mixture; The complexing agent-alkali mixture contains a metal ion complexing agent and an alkaline substance; the metal ion complexing agent includes a tetraamine organic compound, and the tetraamine organic compound includes triethylenetetramine; S2, the iron-copper mixture and the complexing agent-alkali mixture are mixed to obtain a reaction solution; The iron-copper mixture contains ferric ions, ferrous ions, and copper ions. The molar ratio of the metal ion complexing agent to the copper ions is 1.5-3:1; The molar ratio of iron in the alkaline substance and the iron-copper mixture is 4-8:1; The mixing process is carried out at a temperature of 10-45°C; S3, the reaction solution is subjected to solid-liquid separation to obtain a copper-containing separation liquid and precipitated iron solid.

2. The method for highly selectively separating iron and copper according to claim 1, characterized in that, The preparation method of the complexing agent-alkali mixture includes: mixing the metal ion complexing agent and the alkaline substance in water to obtain the complexing agent-alkali mixture.

3. The method for highly selectively separating iron and copper according to claim 1, characterized in that, The alkaline substance includes one or more of sodium hydroxide, potassium hydroxide, and ammonia.

4. The method for highly selectively separating iron and copper according to claim 1, characterized in that, The concentration of the metal ion complexing agent in the complexing agent-alkali mixture is 0.1-0.3 mol / L, and the concentration of the alkaline substance in the complexing agent-alkali mixture is 0.4-0.8 mol / L. In the iron-copper mixture, the total concentration of ferrous ions and ferric ions is 0.05-0.2 mol / L, and the concentration of copper ions is 0.05-0.2 mol / L; wherein the molar ratio of ferrous ions to ferric ions is 1:1-5.

5. The method for highly selectively separating iron and copper according to claim 1, characterized in that, The mixing process lasts for no less than 3 hours, the mixing speed is 300-700 rpm, and the mixing process is carried out under sealed conditions.

6. The method for highly selectively separating iron and copper according to claim 1, characterized in that, The ferric ions exist in the form of ferric sulfate, the ferrous ions exist in the form of ferrous sulfate, and the copper ions exist in the form of copper sulfate.

7. The method for highly selective separation of iron and copper according to any one of claims 1-6, characterized in that, Step S3 further includes: washing and drying the solid product obtained from the solid-liquid separation in sequence to obtain the precipitated iron solid.

8. The application of the highly selective separation of iron and copper as described in any one of claims 1-7 in the preparation of weakly crystalline high-iron materials.

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