A method for rapid separation of iron and copper based on a microreactor

Abstract

The application provides a method for rapidly separating iron and copper based on a micro-reactor, comprising the following steps: S1, controlling a complexing agent-alkali mixed solution and an iron-copper mixed solution to be injected into a same mixing joint to obtain a mixed flow solution; the complexing agent-alkali mixed solution is injected into the mixing joint through a first micro-liquid inlet channel, and the iron-copper mixed solution is injected into the mixing joint through a second micro-liquid inlet channel; the complexing agent-alkali mixed solution contains a metal ion complexing agent and an alkaline substance; the iron-copper mixed solution contains ferric ions, ferrous ions and copper ions; S2, controlling the mixed flow solution to flow from a liquid outlet end of the mixing joint into a reaction micro-channel, and collecting a reaction solution at a liquid outlet end of the reaction micro-channel; and S3, performing solid-liquid separation on the reaction solution to obtain a copper-containing separation solution and a ferric solid. The application can realize rapid and high-degree separation of iron and copper.

Description

Technical Field

[0001] This invention belongs to the field of microfluidics, and particularly relates to a method for rapid separation of iron and copper based on a microreactor. Background Technology

[0002] Separation of heavy metals from hydrometallurgical zinc leaching solutions has always been a challenge in the metallurgical and environmental fields. Due to the high concentrations and similar chemical properties of iron and copper in zinc leaching solutions, traditional separation methods are often inefficient, energy-intensive, and costly. Therefore, developing an efficient, rapid, and economical method for separating copper and iron is crucial for improving the resource utilization rate of iron in hydrometallurgical zinc leaching solutions.

[0003] Traditional methods for heavy metal separation include solvent extraction, ion exchange, and chemical precipitation; however, these methods have many drawbacks. For example, solvent extraction requires large amounts of organic solvents, is complex to operate, and pollutes the environment; ion exchange consumes large quantities of reagents and the subsequent regeneration process is costly; chemical precipitation tends to precipitate other impurity elements along with the product, resulting in low product purity and low heavy metal separation efficiency. Furthermore, while microfluidics can promote solution mass transfer, conventional reaction methods alone cannot simultaneously achieve rapid and high-level separation of iron and copper.

[0004] Therefore, it is necessary to provide a method for rapid separation of iron and copper based on microreactors to solve or at least alleviate the aforementioned technical problem of how to simultaneously achieve rapid and high-level separation of iron and copper. Summary of the Invention

[0005] The main objective of this invention is to provide a method for rapid separation of iron and copper based on a microreactor, which aims to solve or at least alleviate the aforementioned technical problem of how to simultaneously achieve rapid and high-level separation of iron and copper.

[0006] To achieve the above objectives, the present invention provides a method for rapid separation of iron and copper based on a microreactor, comprising the following steps:

[0007] S1, control the injection of complexing agent-alkali mixture and iron-copper mixture into the same mixing joint to obtain mixed liquid;

[0008] The complexing agent-alkali mixture is injected into the mixing connector through the first micro-inlet channel, and the iron-copper mixture is injected into the mixing connector through the second micro-inlet channel.

[0009] The complexing agent-alkali mixture contains a metal ion complexing agent and an alkaline substance; 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 1.7-2.5:1, and the molar ratio of the alkaline substance to the iron in the iron-copper mixture is 4-8:1.

[0010] S2, control the mixed liquid to flow into the reaction microchannel from the outlet end of the mixing connector, and collect the reaction liquid at the outlet end of the reaction microchannel; the residence time of the mixed liquid in the reaction microchannel is 18-100s;

[0011] S3, the reaction solution is separated into solid and liquid components to obtain a copper-containing separation liquid and precipitated iron solids.

[0012] Furthermore, the flow rate of the complexing agent-alkali mixture in the first inlet microchannel is 0.5-6 mL / min, and the flow rate of the iron-copper mixture in the second inlet microchannel is 0.5-6 mL / min.

[0013] Furthermore, the inner diameters of the first liquid inlet microchannel, the second liquid inlet microchannel, and the reaction microchannel are all 0.8-1.2 mm.

[0014] Furthermore, the residence time of the mixed liquid in the reaction microchannel is 20-60 s.

[0015] Furthermore, 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.

[0016] Furthermore, in the complexing agent-alkali mixture, the concentration of the metal ion complexing agent is 0.05-0.3 mol / L, and the concentration of the alkaline substance is 0.4-0.8 mol / L.

[0017] Furthermore, the metal ion complexing agent includes tetraamine organic compounds.

[0018] Furthermore, the tetraamine organic compound includes triethylenetetramine.

[0019] Furthermore, the alkaline substances include one or more of sodium hydroxide and potassium hydroxide.

[0020] Furthermore, the first liquid inlet microchannel, the second liquid inlet microchannel, the mixing connector, and the reaction microchannel are all kept at a temperature of 10-65°C.

[0021] Compared with the prior art, the present invention has at least the following advantages:

[0022] 1. The separation method provided by this invention uses a small amount of reagent and has a short reaction time. The complexing agent-alkali mixture and the iron-copper mixture are injected into microchannels respectively, then mixed at the mixing joint, and reacted rapidly in the reaction microchannels to form a suspension in about 24 seconds. After solid-liquid separation, the iron content in the solid phase can reach 53.17%, and the copper content can be as low as 1.04%. The copper content in the slag is significantly lower than that in existing iron slag, realizing resource recycling and reducing heavy metal pollution to the environment.

[0023] 2. The separation method provided by this invention can enhance fluid mixing and mass transfer in a low-temperature, low-alkali environment, efficiently forming precipitated iron products. Under the regulation of the complexing agent, it efficiently achieves the selective separation of iron and copper, i.e., iron ions rapidly precipitate, while copper ions remain in the solution in the form of a complex. Specifically, when a specific complexing agent comes into contact with copper ions in a microreactor, the lone pair electrons in the amino group rapidly form coordinate bonds with the copper ions, resulting in a stable complex between the 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 the selective separation of iron and copper. Attached Figure Description

[0024] 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.

[0025] Figure 1 The X-ray diffraction patterns of the iron-sinking products in Example 1 and Comparative Example 1 of this invention are shown below. Intensity (au) represents intensity, 2θ (°) represents twice the diffraction angle, and Magnetite PDF#19-0629 represents the standard card of the magnetite mineral phase.

[0026] Figure 2 The image shows the elemental content of the iron-precipitated products in Examples 1-2 and Comparative Examples 1-4 of this invention; wherein, the bars represent the iron and copper content, and the stars represent the iron-copper ratio.

[0027] Figure 3 The image shows the elemental composition of the iron-containing products in Comparative Examples 5-6 of this invention; where the bars represent the iron and copper contents, and the stars represent the iron-copper ratio.

[0028] Figure 4 The image shows the elemental composition of the iron deposits in Comparative Examples 7-10 of this invention; where the bars represent the iron and copper contents, and the stars represent the iron-copper ratio.

[0029] Figure 5 The Fourier transform infrared spectra of the iron deposits in Example 1 and Comparative Example 1 of this invention are shown.

[0030] 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

[0031] 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.

[0032] 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.

[0033] 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.

[0034] This invention provides a method for rapid separation of iron and copper based on a microreactor, comprising the following steps:

[0035] S1, control the injection (continuous injection) of complexing agent-alkali mixture and iron-copper mixture into the same mixing joint to obtain mixed flow liquid.

[0036] The complexing agent-alkali mixture is injected (continuously) into the mixing connector through the first inlet microchannel, and the iron-copper mixture is injected (continuously) into the mixing connector through the second inlet microchannel. The mixing connector can be a T-shaped connector (the T-shaped connector has two inlet ends and one outlet end), and the inner diameter (orifice diameter) of the mixing connector can be 0.3-0.8 mm.

[0037] Both the iron-copper mixture and the complexing agent-alkali mixture need to be purged with nitrogen for 30 minutes before use to remove oxygen from the solution and prevent ferrous iron from being oxidized.

[0038] The flow rate of the complexing agent-alkali mixture in the first inlet microchannel can be 0.5-6 mL / min, and the flow rate of the iron-copper mixture in the second inlet microchannel can be 0.5-6 mL / min; the flow rates of both can be kept consistent. The inner diameters of the first inlet microchannel, the second inlet microchannel, and the reaction microchannel can all be 0.8-1.2 mm, and the inner diameters of all three can be kept consistent.

[0039] 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.

[0040] The iron-copper mixture contains ferric ions, ferrous ions, and copper ions; the total concentration of ferrous and ferric ions in the iron-copper mixture is 0.05-0.2 mol / L, and the concentration of copper ions is 0.05-0.2 mol / L; the molar ratio of ferrous ions to ferric ions is 1:1-5; in this invention, the molar ratio of iron (ferrous and ferric ions) to copper (copper ions) can be 0.8-4:1.

[0041] 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; the tetraamine organic compound includes triethylenetetramine; the alkaline substance includes one or more of sodium hydroxide and potassium hydroxide. In the complexing agent-alkali mixture, the concentration of the metal ion complexing agent can be 0.05-0.3 mol / L, preferably 0.17-0.25 mol / L; the concentration of the alkaline substance can be 0.4-0.8 mol / L, preferably 0.4-0.6 mol / L.

[0042] In the mixed liquid, the molar ratio of the metal ion complexing agent to the copper ions is 1.7-2.5:1, and the molar ratio of iron (ferrous ions and ferric ions) in the alkaline substance and the iron-copper mixture is 4-8:1.

[0043] S2, control the mixed liquid to flow directly (continuously) into the reaction microchannel from the outlet end of the mixing connector, and collect the reaction liquid at the outlet end of the reaction microchannel, wherein the reaction liquid is a suspension flowing out from the outlet end of the reaction microchannel.

[0044] The residence time of the mixed liquid in the reaction microchannel is 18-100s, preferably 20-60s; the temperature of the complexing agent-alkali mixture, the iron-copper mixture, and the mixed liquid can all be 10-65℃, preferably 10-45℃; that is, without affecting the inlet and outlet of the liquid, the first inlet microchannel, the second inlet microchannel, the mixing connector, and the reaction microchannel can all be in an ambient temperature of 10-65℃ or 10-45℃.

[0045] S3, the reaction solution is separated into solid and liquid components to obtain a copper-containing separation liquid and precipitated iron solids.

[0046] In this invention, the method for rapidly separating iron and copper is implemented in a microreactor, which includes a first inlet microchannel, a second inlet microchannel, a mixing connector (which can be a T-shaped connector), and a reaction microchannel. The mixing connector has a first inlet (first inlet end), a second inlet (second inlet end), and an outlet (outlet end). The first inlet microchannel and the first inlet of the mixing connector are connected, the second inlet microchannel and the second inlet of the mixing connector are connected, and the outlet of the mixing connector and the reaction microchannel are connected.

[0047] The microreactor may further include a dual-channel injection pump, wherein the dual-channel injection pump injects a complexing agent-alkali mixture into the first inlet microchannel through a first syringe, and injects an iron-copper mixture into the second inlet microchannel through a second syringe; the first inlet is used to inject the complexing agent-alkali mixture from the first inlet microchannel into the mixing connector, and the second inlet is used to inject the iron-copper mixture from the second inlet microchannel into the mixing connector.

[0048] The iron-copper mixture and the complexing agent-alkali mixture converge inside the mixing joint to form the mixed liquid. The mixed liquid flows into the reaction microchannel from the outlet of the mixing joint. After the reaction is completed, the obtained suspension is immediately centrifuged and washed, and the solid phase is freeze-dried to obtain a copper-doped precipitated iron solid.

[0049] The first liquid inlet microchannel, the second liquid inlet microchannel, and the reaction microchannel can all be spiral tubes, and the inner diameter of the spiral tubes can be 2-6 cm; the lengths of the first preheating microchannel and the second preheating microchannel can both be 2-5 m, and the lengths of the first preheating microchannel and the second preheating microchannel can be the same; the length of the reaction microchannel can be 2-8 m.

[0050] In this invention, after solid-liquid separation (e.g., centrifugation) of the reaction solution, the solid can be washed and dried sequentially to obtain the precipitated iron solid. Since the obtained precipitated iron solid particles are extremely small, the first step involves centrifugation to obtain the solid phase. The washing step includes rinsing the solid phase with deionized water 2-4 times by vacuum filtration, each rinse lasting 1-3 minutes. Repeated washing with deionized water effectively removes impurities and residues from the surface of the precipitated iron product.

[0051] It should be noted that the amount of alkali in this invention needs to be controlled. High alkali conditions are not conducive to the separation of iron and copper, while low alkali conditions will affect the precipitation of iron. For example, when there is excess alkali, triethylenetetramine and alkali will compete for copper ions, resulting in the precipitation reaction of copper hydroxide, which reduces the contact opportunity between triethylenetetramine and copper ions, thereby weakening the complexation effect between the two.

[0052] Furthermore, temperature is a key factor affecting the complexation reaction in this invention. High temperatures 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.

[0053] It is worth noting that the ratio of the complexing agent to copper ions is also an important parameter affecting the complexing effect of copper ions. 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 a strong complexing effect with copper ions, the optimal molar ratio of triethylenetetramine to copper ions is 2:1.

[0054] The structural formula of triethylenetetramine is as follows:

[0055]

[0056] The separation method provided by this invention can enhance fluid mixing and mass transfer in a low-temperature, low-alkali environment, efficiently forming iron precipitation products. Under the regulation of a complexing agent, it efficiently achieves selective separation of iron and copper, i.e., iron ions rapidly precipitate, while copper ions remain in the solution as complexes. When triethylenetetramine 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 triethylenetetramine and copper ions. Simultaneously, the formation of these coordinate bonds lowers the free energy of the complex, further increasing its stability, thereby achieving selective separation of iron and copper.

[0057] The separation method provided by this invention uses a small amount of reagents and has a short reaction time. The iron-copper mixture and the alkali-regulator mixed liquid are injected into the inlet microchannel of the microreactor, mixed at the mixing joint, and quickly remain in the reaction microchannel for about 24 seconds to form a suspension. After solid-liquid separation, the iron content in the solid phase can reach 53.17%, and the copper content can be as low as 1.04%. The slag volume is small, and the copper content in the slag is significantly better than that of existing iron slag. This achieves resource recycling and reduces heavy metal pollution to the environment.

[0058] The following are specific examples of the present invention:

[0059] Example 1 (TETA:Cu = 2:1, NaOH = 0.5M, T = 25℃, t = 24s)

[0060] 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 to ferric ions is 1:2.

[0061] 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.

[0062] Both the iron-copper mixture and the TETA-NaOH mixture were subjected to oxygen removal treatment for 30 minutes before the reaction.

[0063] 2. Use one syringe to draw 50 mL of iron-copper mixed solution, and use another syringe to draw 50 mL of TETA-NaOH mixed solution.

[0064] A TETA-NaOH mixture is injected into a first inlet microchannel with a length of 2.5m using a dual-channel syringe pump at a flow rate of 5mL / min, and an iron-copper mixture is injected into a second inlet microchannel with a length of 2.5m using a flow rate of 5mL / min. The first inlet microchannel is connected to the first inlet (lower port) of the T-connector, and the second inlet microchannel is connected to the second inlet (left port) of the T-connector.

[0065] The iron-copper mixture and the TETA-NaOH mixture are mixed at a T-joint to obtain a mixed flow. The mixed flow flows into a 5m long reaction microchannel for reaction, and the residence time of the mixed flow in the reaction microchannel is 24s. Specifically, the iron-copper mixture enters from the left opening of the T-joint, the TETA-NaOH mixture enters from the bottom opening of the T-joint, and the mixed flow exits from the right opening of the T-joint and directly enters the reaction microchannel. The reaction microchannel and the outlet (right opening) of the T-joint are connected.

[0066] The first inlet microchannel, the second inlet microchannel, and the reaction microchannel all have an inner diameter of 1.0 mm and an outer diameter of 1.6 mm. All three are spiral tubes with an inner diameter of 4 cm. The orifice diameter of the T-connector is 0.5 mm. All three are placed in a 25°C water bath (reaction temperature).

[0067] After the reaction was completed, the reaction solution (suspension) flowing out of the reaction microchannel was centrifuged to obtain a copper-containing separation solution (supernatant) and a solid product. The solid product was washed (rinsed with deionized water, repeated 3 times, rinsing for 2 minutes each time) and dried to obtain the precipitated iron product.

[0068] 3. Test Results:

[0069] X-ray diffraction, elemental analysis, and Fourier transform infrared spectroscopy were performed on the precipitated iron product. The determination and calculation of copper and iron content were as follows: 0.01 g of the precipitated iron product was weighed and dissolved in 2 mL of concentrated hydrochloric acid (AR, 36.0%–38.0%), diluted, and then measured using 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.

[0070] like Figure 1 As shown, the X-ray spectrum of the iron-laden product in this embodiment has broad characteristic peaks at 2θ of 34.52° and 62.41°, corresponding to the (311) and (440) crystal planes, respectively, which are consistent with the PDF card (PDF#19-0629) of magnetite. However, compared with Comparative Example 1, the crystal form of magnetite is significantly suppressed, which inhibits the transformation of iron precursor to magnetite. The weakening of the magnetite crystal form is also one of the reasons for reducing the entry of copper ions into the iron-laden product.

[0071] like Figure 2 As shown, in this embodiment, the copper content in the precipitated iron product is 1.04%, the iron content is 53.17%, the Fe / Cu ratio is 51.13, and the precipitated iron rate is 99.04%.

[0072] like Figure 5As shown, the Fourier transform infrared spectrum of the iron deposition product in this embodiment is at a wavenumber of 1104 cm⁻¹. -1 and 1052cm -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 with Comparative Example 1, the characteristic peaks of magnetite gradually disappeared. This is mainly because 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 transformation of magnetite and thus weakening its characteristic absorption peaks.

[0073] Example 2

[0074] Compared to Example 1, this example adjusts the reaction temperature to 60°C while keeping other conditions unchanged.

[0075] like Figure 2 As shown, in this embodiment, the copper content in the precipitated iron product is 1.25%, the iron content is 54.83%, the Fe / Cu ratio is 43.86, and the precipitation rate is 99.44%. Compared with Example 1, the Fe / Cu ratio shows a decreasing trend. This is because with the increase in temperature, the internal energy of the system increases, and the coordination bond between TETA and copper ions becomes unstable, weakening the iron-copper separation effect.

[0076] Comparative Example 1

[0077] Compared to Example 1, 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.

[0078] like Figure 1 As shown, the X-ray spectrum of the iron-sinking product in this embodiment has characteristic peaks at 2θ of 36.47° and 62.41°, 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-sinking product.

[0079] like Figure 2 As shown, in this comparative example, the copper content in the precipitated iron product was 18.2%, the iron content was 34.36%, the Fe / Cu ratio was 1.89, and the precipitated iron rate was 94.44%. Compared with Example 1, the Fe / Cu ratio decreased significantly, indicating that TETA is a highly efficient regulator for promoting iron-copper separation.

[0080] 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. -1 The characteristic peaks of magnetite were identified at a wavenumber of 1104 cm⁻¹. -1and 1052cm -1 The nearby absorption peaks correspond to the OH stretching vibration of fibrous ore.

[0081] Comparative Example 2

[0082] Compared to Comparative Example 1, this comparative example adjusted the flow rate of the TETA-NaOH mixture in the first inlet microchannel to 1 mL / min, the flow rate of the iron-copper mixture in the second inlet microchannel to 1 mL / min, and the residence time of the mixed liquid in the reaction microchannel to 120 s, while keeping other conditions unchanged.

[0083] like Figure 2 As shown, in this comparative example, the copper content in the precipitated iron product was 17.71%, the iron content was 35.68%, the Fe / Cu ratio was 2.01, and the iron precipitation rate was 95.08%. Compared to Comparative Example 1, without the regulating effect of the complexing agent TETA, extending the residence time of the mixed liquid in the reaction microchannel had almost no effect on the iron-copper separation effect.

[0084] Comparative Example 3

[0085] Compared to Example 1, this comparative example adjusted the flow rate of the TETA-NaOH mixture in the first inlet microchannel to 1 mL / min, the flow rate of the iron-copper mixture in the second inlet microchannel to 1 mL / min, and the residence time of the mixed liquid in the reaction microchannel to 120 s, while keeping other conditions unchanged.

[0086] like Figure 2 As shown, in this comparative example, the copper content in the precipitated iron product is 1.62%, the iron content is 51.94%, the Fe / Cu ratio is 32.06, and the precipitated iron rate is 99.88%.

[0087] Comparative Example 4

[0088] Compared to Comparative Example 1, this comparative example adjusted the reaction temperature to 60℃, while keeping other conditions unchanged.

[0089] like Figure 2 As shown, in this comparative example, the copper content in the precipitated iron product is 18.36%, the iron content is 38.43%, the Fe / Cu ratio is 2.09, and the precipitated iron rate is 95.66%.

[0090] Comparative Example 5

[0091] Compared to Example 1, this comparative example adjusts the molar ratio of complexing agent TETA to copper ions to 1.5:1, while keeping other conditions unchanged; that is, the concentration of complexing agent TETA in the TETA-NaOH mixture is adjusted to 0.15 mol / L.

[0092] like Figure 3 As shown, in this comparative example, the copper content in the precipitated iron product is 2.83%, the iron content is 54.27%, the Fe / Cu ratio is 19.15, and the precipitated iron rate is 99.53%.

[0093] Comparative Example 6

[0094] Compared to Example 1, this comparative example adjusts the molar ratio of complexing agent TETA to copper ions to 1:1, while keeping other conditions unchanged; that is, the concentration of complexing agent TETA in the TETA-NaOH mixture is adjusted to 0.1 mol / L.

[0095] like Figure 3 As shown, in this comparative example, the copper content in the precipitated iron product is 4.35%, the iron content is 50.92%, the Fe / Cu ratio is 11.70, and the precipitated iron rate is 99.96%.

[0096] Comparative Example 7

[0097] Compared to Comparative Example 1, the concentration of NaOH in this comparative example was adjusted to 1 mol / L, while other conditions remained unchanged.

[0098] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product is 25.44%, the iron content is 35.80%, the Fe / Cu ratio is 1.41, and the precipitated iron rate is 99.97%.

[0099] Comparative Example 8

[0100] Compared to Example 1, the concentration of NaOH in the TETA-NaOH mixture in this comparative example was adjusted to 1 mol / L.

[0101] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product is 8.10%, the iron content is 46.56%, the Fe / Cu ratio is 5.75, and the precipitated iron rate is 99.97%.

[0102] Comparative Example 9

[0103] Compared to Comparative Example 1, the concentration of NaOH in this comparative example was adjusted to 3 mol / L, while other conditions remained unchanged.

[0104] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product was 22.56%, the iron content was 34.19%, the Fe / Cu ratio was 1.52, and the precipitated iron rate was 99.97%.

[0105] Comparative Example 10

[0106] Compared to 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.

[0107] like Figure 4 As shown, in this comparative example, the copper content in the precipitated iron product is 9.11%, the iron content is 43.50%, the Fe / Cu ratio is 4.77, and the precipitated iron rate is 99.94%.

[0108] Comparative Example 11

[0109] Measure 50 mL of iron-copper mixture (same as in Example 1) into a reaction vessel (conical flask), add 50 mL of TETA-NaOH mixture (same as in Example 1), seal and stir the reaction. The stirring rate is 500 rpm, and the reaction times are 1 h and 4 h, respectively. The reaction vessel is placed in a 25°C water bath environment (reaction temperature).

[0110] 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.

[0111] In this comparative example, when the reaction time was 1 hour, the copper content in the precipitated iron product was 1.37%, the iron content was 53.65%, the Fe / Cu ratio was 39.16, and the precipitation rate was 99.09%. When the reaction time was 4 hours, the copper content in the precipitated iron product was 0.88%, the iron content was 55.50%, the Fe / Cu ratio was 63.07, and the precipitation rate was 99.95%. Therefore, this comparative example could not obtain a low-copper, high-iron precipitated iron product within 1 hour.

[0112] Comparative Example 12

[0113] Compared with Comparative Example 11, this comparative example only changed the complexing agent triethylenetetramine (TETA) to the complexing agent mercaptoethylamine (C2H7NS), and the TETA-NaOH mixture was changed to the C2H7NS-NaOH mixture. The reaction time was 4 hours, and other conditions remained unchanged.

[0114] In this comparative example, the copper content in the precipitated iron product was 16.03%, the iron content was 31.64%, the Fe / Cu ratio was 1.97, the precipitated iron rate was 99.95%, and the iron-copper separation effect was poor.

[0115] Comparative Example 13

[0116] Compared with Comparative Example 12, 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.

[0117] In this comparative example, the copper content in the precipitated iron product was 0.97%, the iron content was 50.11%, the Fe / Cu ratio was 51.82, and the precipitation rate was 92.31%. Compared with Comparative Example 12, the iron-copper separation effect was improved; however, the precipitation rate decreased significantly.

[0118] Comparative Example 14

[0119] Compared with Comparative Example 11, 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. The reaction time was 4 hours, and other conditions remained unchanged.

[0120] In this comparative example, the copper content in the precipitated iron product was 2.04%, the iron content was 37.03%, the Fe / Cu ratio was 18.15, and the precipitated iron rate was 44.79%, indicating poor iron-copper separation.

[0121] Comparative Example 15

[0122] Compared with Comparative Example 14, 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.

[0123] 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.

[0124] 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 rapid separation of iron and copper based on microreactor, characterized in that, The method comprises the steps of: S1, controlling the injection of a complexing agent-alkali mixture and an iron-copper mixture into the same mixing joint to obtain a mixed flow liquid; wherein the complexing agent-alkali mixture is injected into the mixing joint through a first micro-liquid feeding channel, and the iron-copper mixture is injected into the mixing joint through a second micro-liquid feeding channel; the complexing agent-alkali mixture contains a metal ion complexing agent and an alkaline substance; the metal ion complexing agent comprises a tetraamine organic compound, and the tetraamine organic compound comprises triethylenetetramine; the alkaline substance comprises one or both of sodium hydroxide and potassium hydroxide; the iron-copper mixture contains ferric ions, ferrous ions and copper ions; the molar ratio of the ferrous ions to the ferric ions is 1:1-5; the molar ratio of the metal ion complexing agent to the copper ions is 1.7-2.5:1, and the molar ratio of the alkaline substance to the iron element in the iron-copper mixture is 4-8:1; S2, controlling the mixed flow liquid to flow from the liquid outlet end of the mixing joint into a reaction micro-channel, and collecting a reaction liquid at the liquid outlet end of the reaction micro-channel; the residence time of the mixed flow liquid in the reaction micro-channel is 18-100 s; S3, solid-liquid separating the reaction liquid to obtain a copper-containing separation liquid and a ferric solid.

2. The method for rapid separation of iron and copper based on micro-reactor according to claim 1, characterized in that, The flow rate of the complexing agent-alkali mixture in the first micro-liquid feeding channel is 0.5-6 mL / min, and the flow rate of the iron-copper mixture in the second micro-liquid feeding channel is 0.5-6 mL / min.

3. The method for rapid separation of iron and copper based on micro-reactor according to claim 1, characterized in that, The inner diameters of the first micro-liquid feeding channel, the second micro-liquid feeding channel and the reaction micro-channel are all 0.8-1.2 mm.

4. The method for rapid separation of iron and copper based on micro-reactor according to claim 1, characterized in that, The residence time of the mixed flow liquid in the reaction micro-channel is 20-60 s.

5. The method for rapid separation of iron and copper based on micro-reactor according to claim 1, characterized in that, In the iron-copper mixture, 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.

6. The method for rapid separation of iron and copper based on micro-reactor according to claim 1, characterized in that, In the complexing agent-alkali mixture, the concentration of the metal ion complexing agent is 0.05-0.3 mol / L, and the concentration of the alkaline substance is 0.4-0.8 mol / L.

7. The method for fast separation of iron and copper based on micro-reactor according to any one of claims 1-6, characterized in that, The first micro-liquid feeding channel, the second micro-liquid feeding channel, the mixing joint and the reaction micro-channel are all in a temperature of 10-65°C.

Images