Micro-channel reactor, iron precipitation method based on iron-zinc mixed solution and application

Abstract

The application provides a micro-channel reactor, a method for iron precipitation based on a mixed solution of iron and zinc and application, and the micro-channel reactor comprises a liquid conveying mechanism and a reaction mechanism; the liquid conveying mechanism comprises a first liquid conveying assembly and a second liquid conveying assembly; the reaction mechanism comprises a first preheating micro-channel, a second preheating micro-channel, a mixing connector and a reaction micro-channel; the mixing connector is provided with a first liquid inlet channel, a second liquid inlet channel and a liquid outlet channel, the first liquid inlet channel is communicated with a liquid outlet of the first preheating micro-channel, the second liquid inlet channel is communicated with a liquid outlet of the second preheating micro-channel, and the liquid outlet channel is communicated with a liquid inlet of the reaction micro-channel. The application can avoid the formation of impurity phases and the co-precipitation of multiple metals while ensuring the efficient formation of iron precipitation products.

Description

Technical Field

[0001] This invention relates to the field of microfluidic enhanced separation technology, and in particular to a microchannel reactor, an iron precipitation method based on an iron-zinc mixture, and its applications. Background Technology

[0002] Iron slag is a solid waste generated during the hydrometallurgical zinc smelting process, typically containing 5%-10% zinc. The large amount of iron slag generated annually, if not properly disposed of, not only wastes metal resources but also poses a significant environmental pollution risk. Currently, traditional source-based iron slag removal methods suffer from high carbon emissions, significant secondary pollution risks, and low utilization rates of valuable metal resources, only providing short-term relief from the pollution situation. Therefore, it is necessary to develop new iron slag removal methods that achieve high iron content and low levels of harmful impurities to solve the current problems.

[0003] Compared to existing traditional iron precipitation methods, the magnetite method has advantages such as high theoretical iron content, strong magnetism facilitating separation, and rapid formation without the need for high temperature and pressure. However, the iron precipitation process in hydrometallurgical zinc leaching solutions is complex, involving nucleation, growth, and intermediate product stages. Furthermore, heavy metals such as zinc in the leaching solution continuously co-precipitate with iron minerals, becoming part of the iron minerals. Therefore, controlling the formation process of magnetite to reduce the doping of impurity elements (such as zinc) is particularly important.

[0004] Therefore, it is necessary to provide a microchannel reactor, an iron-zinc mixed solution-based iron precipitation method and its application, in order to solve or at least alleviate the technical defects of high zinc doping in the iron precipitation slag. Summary of the Invention

[0005] The main objective of this invention is to provide a microchannel reactor, an iron-zinc mixed solution-based iron precipitation method and its application, aiming to solve the technical problem of high zinc doping in iron precipitation slag.

[0006] To achieve the above objectives, the present invention provides a microchannel reactor, comprising a liquid delivery mechanism and a reaction mechanism; the liquid delivery mechanism includes a first liquid delivery component and a second liquid delivery component; the reaction mechanism includes a first preheating microchannel, a second preheating microchannel, a mixing connector, and a reaction microchannel;

[0007] The liquid outlet of the first liquid delivery component is connected to the liquid inlet of the first preheating microchannel, and the liquid outlet of the second liquid delivery component is connected to the liquid inlet of the second preheating microchannel; the mixing connector has a first liquid inlet passage, a second liquid inlet passage, and a liquid outlet passage, the first liquid inlet passage is connected to the liquid outlet of the first preheating microchannel, the second liquid inlet passage is connected to the liquid outlet of the second preheating microchannel; the liquid outlet passage is connected to the liquid inlet of the reaction microchannel.

[0008] Furthermore, both the first liquid delivery assembly and the second liquid delivery assembly include an injection pump;

[0009] The first preheating microchannel, the second preheating microchannel, and the reaction microchannel are all spiral tubes with an inner diameter of 2-6 cm; the inner diameters of the first preheating microchannel, the second preheating microchannel, and the reaction microchannel are all 0.8-1.2 mm; the lengths of the first preheating microchannel and the second preheating microchannel are both 2-5 m, and the length of the reaction microchannel is 2-10 m.

[0010] The mixing connector is a T-shaped three-way connector. The first liquid inlet passage and the liquid outlet passage are on the same straight line, and the second liquid inlet passage is perpendicular to the first liquid inlet passage. The liquid outlets of the first liquid inlet passage and the second liquid inlet passage are connected to the liquid inlet of the liquid outlet passage. The inner diameters of the first liquid inlet passage, the second liquid inlet passage, and the liquid outlet passage are all 0.5-1.0 mm.

[0011] Furthermore, the microchannel reactor also includes a temperature control component and / or a collection container;

[0012] The temperature control component is used to heat the first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel, and the collection container is used to receive the product flowing out of the reaction microchannel.

[0013] The present invention also provides an application of the microchannel reactor as described above in the precipitation of iron and reduction of zinc co-precipitation.

[0014] The present invention also provides a method for iron precipitation based on an iron-zinc mixture, comprising: injecting an iron-zinc mixture into a first liquid inlet passage of a mixing connector through a first preheated microchannel, and injecting an alkaline solution into a second liquid inlet passage of the mixing connector through a second preheated microchannel, so that the iron-zinc mixture and the alkaline solution merge in the mixing connector to obtain a reaction solution;

[0015] The reaction liquid is introduced into the reaction microchannel through the outlet passage of the mixing connector, and the product flowing out of the reaction microchannel is collected to obtain a suspension; the suspension is then separated into solid and liquid components to obtain precipitated iron solids.

[0016] Furthermore, the iron-zinc mixture is injected into the first inlet passage of the mixing connector from the first preheating microchannel under the push of the first liquid delivery component, and the alkali solution is injected into the second inlet passage of the mixing connector from the second preheating microchannel under the push of the second liquid delivery component.

[0017] Furthermore, in the iron-zinc mixture, the total concentration of ferrous ions and ferric ions is 0.01-0.2 mol / L, and the concentration of zinc ions is 0.01-0.2 mol / L; wherein the molar ratio of ferrous ions to ferric ions is 1:1-5.

[0018] Furthermore, the concentration of alkaline substances in the alkaline solution is 3-10 mol / L.

[0019] Furthermore, the flow rate of the iron-zinc mixture in the first preheating channel and the flow rate of the alkali solution in the second preheating channel are both 2-6 ml / min; the residence time of the reaction solution in the reaction microchannel is 29-88 s.

[0020] Furthermore, the first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel are all in an environment of 50-90°C.

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

[0022] 1. The microchannel reactor provided by this invention can precisely control the formation process of precipitated iron products in a multi-metal coexistence solution system. While ensuring the efficient formation of precipitated iron products, it can avoid the formation of impurity phases and the co-precipitation of multiple metals.

[0023] 2. The iron precipitation method provided by this invention injects an iron-zinc mixture and an alkaline solution into a preheated microchannel of a microchannel reactor. After preheating, they are mixed at the mixing joint and react rapidly in the reaction microchannel to form magnetite. The magnetite is collected at the outlet of the reaction microchannel. After solid-liquid separation, the iron content in the solid phase can be as high as 61.89%, and the zinc content can be as low as 2.83%. The slag volume is small, and the zinc content in the slag is significantly better than that of existing iron precipitation slag. 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 This is a schematic diagram of the microchannel reactor module in this invention;

[0026] Figure 2 This is a reaction scenario diagram of the iron deposition method in this invention;

[0027] Figure 3 The X-ray diffraction patterns of the iron-sinking products in Examples 1-3 of this invention are shown below.

[0028] Figure 4 The elemental composition diagrams are shown for the iron precipitate products in Example 1 and Comparative Examples 1-2 of this invention.

[0029] Figure 5 The elemental composition diagrams are shown for the iron precipitate products in Examples 2-3 and Comparative Examples 3-4 of this invention.

[0030] Figure 6 This is a graph showing the elemental composition of the iron-sinking product in Example 4 of the present invention;

[0031] Figure 7 This is a diagram showing the elemental composition of the iron-containing product in Comparative Example 5 of this invention.

[0032] Reference numerals: 1. First liquid delivery assembly; 2. Second liquid delivery assembly; 3. First preheating microchannel; 4. Second preheating microchannel; 5. Mixing connector; 6. Reaction microchannel; 7. Collection container.

[0033] 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

[0034] 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.

[0035] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but this must be 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 a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. It should be noted that the data in the embodiments and comparative examples of the present invention are all average values ​​after multiple tests, and have stability and repeatability; and the iron content and zinc content in the present invention are both mass ratios.

[0036] Currently, the magnetite formation process is mainly applied to traditional macroscopic mixed systems. The main methods for magnetite formation include coprecipitation, ferrous oxidation, and reduction-conversion. Among these, coprecipitation, due to its very rapid magnetite formation rate, makes precise control of the reaction time difficult in macroscopic mixed systems. Furthermore, due to the limitations of the macroscopic scale, regions of excessively high local concentrations can easily form in the solution, leading to uncontrollable mass transfer, or regions of excessively high temperatures can form, resulting in uneven heating and the formation of more impurity phases and intermediate states, directly affecting the effective control of impurity elements in the magnetite formation process. Therefore, developing a microchannel reactor and a method for iron precipitation and metal doping reduction using a microchannel reactor is of great significance.

[0037] Based on this, see Figure 1-2 As shown, the present invention provides a microchannel reactor, including a liquid delivery mechanism and a reaction mechanism; the liquid delivery mechanism includes a first liquid delivery component and a second liquid delivery component; the reaction mechanism includes a first preheating microchannel, a second preheating microchannel, a mixing connector and a reaction microchannel.

[0038] The liquid outlet of the first liquid delivery component is connected to the liquid inlet of the first preheating microchannel, and the liquid outlet of the second liquid delivery component is connected to the liquid inlet of the second preheating microchannel; the mixing connector has a first liquid inlet passage, a second liquid inlet passage, and a liquid outlet passage, the first liquid inlet passage is connected to the liquid outlet of the first preheating microchannel, the second liquid inlet passage is connected to the liquid outlet of the second preheating microchannel; the liquid outlet passage is connected to the liquid inlet of the reaction microchannel.

[0039] It should be noted that the first liquid delivery component is used to inject an iron-zinc mixture into the first preheating microchannel, which preheats the iron-zinc mixture and delivers it into the first liquid inlet passage. Simultaneously, the second liquid delivery component is used to inject an alkaline solution into the second preheating microchannel, which preheats the alkaline solution and delivers it into the second liquid inlet passage. When the iron-zinc mixture and the alkaline solution converge in the mixing connector, they enter the reaction microchannel from the liquid outlet passage, thereby causing an iron precipitation reaction.

[0040] Furthermore, in order to realize the liquid supply operation from the infusion mechanism to the reaction mechanism, both the first liquid delivery component and the second liquid delivery component may include or be an injection pump.

[0041] Furthermore, in order to reduce the footprint and increase the mixing and mass transfer effect, the first preheating microchannel, the second preheating microchannel and the reaction microchannel can all be spiral tubes, and the spiral tubes can be in a regular spiral shape; the inner diameter of the spiral tube can be 2-6 cm, and the inner diameter refers to the diameter between the inner walls of the spiral tube.

[0042] Furthermore, in order to avoid particles clogging the pipes and to ensure stable flow of fluid within the microchannels, the inner diameter of the first preheating microchannel, the second preheating microchannel, and the reaction microchannel can all be 0.8-1.2 mm, and the outer diameter can all be 1.5-2.0 mm; the inner and outer diameters of the first preheating microchannel, the second preheating microchannel, and the reaction microchannel can be the same.

[0043] Furthermore, to ensure that the iron-zinc mixture and the alkaline solution reach the reaction temperature before merging at the mixing joint, and to ensure that the reaction occurs smoothly within the microchannel, the lengths of both the first and second preheating microchannels can be 2-5 m; the length of the reaction microchannel can be 2-10 m, and more specifically, 5-10 m. It should be noted that the lengths here refer to the total length of the tube after it has been unfolded.

[0044] Furthermore, to enhance mixing and heat exchange efficiency, thereby increasing reaction and mixing rates and improving iron-zinc separation, the mixing connector is a T-shaped three-way connector. The first liquid inlet passage and the liquid outlet passage are on the same straight line, and the second liquid inlet passage is perpendicular to the first liquid inlet passage. The liquid outlets of both the first and second liquid inlet passages are connected to the liquid inlet of the liquid outlet passage.

[0045] Furthermore, in order to enhance the mixing effect of the iron-zinc mixture and the alkaline solution, the inner diameters of the first inlet passage, the second inlet passage, and the outlet passage can be consistent and can be smaller than the inner diameters of the first preheating microchannel, the second preheating microchannel, and the reaction microchannel; specifically, the inner diameters of the first inlet passage, the second inlet passage, and the outlet passage can all be 0.5-1.0 mm, where the inner diameter is the aperture of the mixing connector.

[0046] Furthermore, in order to achieve temperature control of the first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel, the microchannel reactor may further include a temperature control component. The temperature control component may include a water bath heater, which may include or be a water bath. The first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel may all be placed in the water bath heater. The temperature control component is used to heat the first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel.

[0047] Furthermore, in order to collect the product, the microchannel reactor may also include a collection container, which may be equipped with a cooling component to keep the collection container at around 0°C; the collection container may be connected to the outlet of the reaction microchannel, and the collection container is used to receive the product flowing out of the reaction microchannel.

[0048] The present invention also provides an application of the microchannel reactor as described above in the precipitation of iron and reduction of zinc coprecipitation; wherein the object of the precipitation of iron and reduction of zinc coprecipitation is an iron-zinc mixture.

[0049] As one way of applying the above, see [link to relevant documentation]. Figure 2 As shown, the present invention also provides a method for iron deposition based on an iron-zinc mixture, which can be implemented in a microchannel reactor as described above.

[0050] The iron deposition method includes: injecting an iron-zinc mixture into the first liquid inlet passage of the mixing joint through the first preheating microchannel, and injecting an alkaline solution into the second liquid inlet passage of the mixing joint through the second preheating microchannel, so that the iron-zinc mixture and the alkaline solution merge in the mixing joint to obtain a reaction solution.

[0051] In the iron-zinc mixture, the total concentration of ferrous and ferric ions can be 0.01-0.2 mol / L, the molar ratio of ferrous to ferric ions can be 1:1-5, the zinc ion concentration can be 0.01-0.2 mol / L, and the pH of the iron-zinc mixture can be 0.5-5. Specifically, the iron-zinc mixture can be obtained by mixing ferrous sulfate, ferric sulfate, zinc sulfate, and a sulfuric acid solution with pH=1. The iron-zinc mixture can be derived from zinc leaching solutions, such as hydrometallurgical zinc leaching solutions. The concentration of alkaline substances in the alkaline solution can be 3-10 mol / L, preferably 8-10 mol / L. The alkaline solution can include or be a sodium hydroxide solution. Before the reaction, nitrogen gas can be bubbled into the iron-zinc mixture and the alkaline solution for 30 minutes to remove oxygen.

[0052] The iron-zinc mixture can be injected into the first inlet passage of the mixing connector from the first preheating microchannel under the push of the first liquid delivery component, and the alkali solution can be injected into the second inlet passage of the mixing connector from the second preheating microchannel under the push of the second liquid delivery component.

[0053] The first liquid inlet passage can be arranged horizontally (the liquid outlet passage is also arranged horizontally, thus being integrally formed with the first liquid inlet passage) so that the iron-zinc mixture can enter the mixing joint horizontally (e.g., from left to right); the second liquid inlet passage can be arranged vertically, and the inlet of the second liquid inlet passage faces downward, that is, the second liquid inlet passage is located below the first liquid inlet passage so that the alkali solution can enter the mixing joint from bottom to top.

[0054] When the iron-zinc mixture and the alkaline solution meet in the mixing joint, the reaction solution enters the reaction microchannel from the liquid outlet of the mixing joint, initiating the nucleation and crystallization process of the precipitated iron product, and the product flowing out of the reaction microchannel is collected to obtain a suspension; the suspension is then separated into a solid and liquid state to obtain a separated liquid and precipitated iron solid, which contains iron.

[0055] To ensure stable operation of the fluid under the flow-driven device, the flow rate of the iron-zinc mixture in the first preheating microchannel can be 2-6 ml / min, preferably 4-5 ml / min; the flow rate of the alkali solution in the second preheating microchannel can be 2-6 ml / min, preferably 4-5 ml / min; both flow rates can be the same. The flow rate of the reaction solution in the reaction microchannel can be 4-12 ml / min, preferably 8-10 ml / min; the residence time of the reaction solution in the reaction microchannel can be 29-88 s, preferably 35-44 s; the residence time is the time from when the reaction solution enters the reaction microchannel to when it flows out of the reaction microchannel.

[0056] To ensure the reaction proceeds, the first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel can all be kept in an environment of 50-90°C.

[0057] To prevent the suspension from continuing to react in the collection container, the collection container can be placed in a temperature environment of about 0°C; for example, the collection container can be placed in a cooling tank containing ice water.

[0058] Specifically, this invention can be understood as follows: two reaction solutions (iron-zinc mixture and alkaline solution) are injected into the reaction mechanism through an injection pump for a continuous process of preheating, mixing and reaction; the two reaction solutions are injected into the preheating microchannel for preheating and then flow into the T-shaped micro-interface (mixing connector) for rapid mixing, and continue to flow into the reaction microchannel to continue the reaction. Finally, the suspension of the iron precipitation product flows into the precooled collection container to complete the microfluidic iron precipitation process.

[0059] This invention significantly increases the iron content of the iron precipitation product (iron precipitate solids), reduces the zinc content, and improves the iron-zinc separation efficiency, effectively compensating for the shortcomings of iron precipitation technology caused by zinc co-precipitation. This invention utilizes the enhanced characteristics of the "three transfers and one reaction" process at the microscale to rapidly precipitate iron from simulated wet zinc smelting leaching solutions and obtain high-purity magnetite iron precipitate products, contributing to iron slag reduction and recycling from the source. "Three transfers and one reaction" refers to momentum transfer, heat transfer, mass transfer, and chemical reaction processes. This invention enables the rapid formation of stable magnetite in a micro-space, with more controllable fluid flow and mass transfer patterns and rapid heat transfer, almost eliminating local temperature differences, which is beneficial for the separation of iron from other metals. This invention precipitates iron from wet zinc smelting leaching solutions in the form of magnetite, while zinc remains in the solution. Compared to macroscopic mixed systems, this method increases the iron content of the iron precipitate product, significantly reduces the amount of iron slag, and significantly reduces zinc doping during the iron precipitation process.

[0060] The following are specific examples of the present invention:

[0061] Example 1: Microchannel 7M-35s

[0062] This embodiment is implemented in a microchannel reactor, and the iron deposition method in this embodiment includes:

[0063] Ferrous sulfate, ferric sulfate, zinc sulfate, and a sulfuric acid solution with pH=1 were mixed to obtain an iron-zinc mixed solution. Sodium hydroxide was mixed with water to obtain an alkaline solution. Both reaction solutions were subjected to oxygen removal treatment.

[0064] Use one syringe to draw 50 mL of a mixed iron-zinc solution, and another syringe to draw 50 mL of an alkaline solution. The concentrations of ferrous ions in the mixed iron-zinc solution are 0.0167 mol / L, ferric ions are 0.0334 mol / L, and zinc ions are 0.05 mol / L; the concentration of the alkaline solution (sodium hydroxide solution) is 7 mol / L.

[0065] The inner diameter of the first preheating microchannel, the second preheating microchannel, and the reaction microchannel is 1.0 mm, and the outer diameter is 1.6 mm. The length of the first preheating microchannel and the second preheating microchannel is 2.5 m, and the length of the reaction microchannel is 7.5 m. The first preheating microchannel, the second preheating microchannel, and the reaction microchannel are all spiral tubes with an inner diameter of 4 cm. The mixing connector is a T-type tee connector with an orifice diameter of 0.51 mm. The iron-zinc mixed solution enters from the left side of the T-type tee connector, and the alkaline solution enters from the lower side of the T-type connector.

[0066] A 2.5m long preheated microchannel was injected with an iron-zinc mixed solution at a flow rate of 5ml / min using a dual-channel syringe pump, and a 2.5m long preheated microchannel was injected with an alkaline solution at a flow rate of 5ml / min. The reaction solution obtained after the iron-zinc mixed solution and the alkaline solution were mixed at the T-shaped tee joint (exiting from the right side of the joint) continued to react in the 7.5m reaction microchannel, with a residence time of 35s in the reaction microchannel. The first preheated microchannel, the second preheated microchannel, the T-shaped tee joint, and the reaction microchannel were all placed in a 60℃ water bath.

[0067] A collection container located in a cooling tank (around 0°C) is set at the outlet of the reaction microchannel to collect the suspension of precipitated iron product. After the reaction is completed, the solid and liquid are separated, and the solid phase is vacuum dried to obtain the precipitated iron product, which is then subjected to X-ray diffraction and elemental content testing.

[0068] The test procedure for elemental content is as follows: Weigh 0.02g of the precipitated iron product, dissolve it in concentrated hydrochloric acid, dilute to 50mL in a colorimetric tube, and then determine the iron and zinc content using ICP-OES.

[0069] See Figure 3 As shown, the iron-laden product (microchannel 7M-35s) in this embodiment is magnetite with a good crystal structure.

[0070] See Figure 4 As shown, in this embodiment, the iron content of the iron-laden product (microchannel 7M-35s) is 57.07%, and the zinc content is 4.67%. Compared with Comparative Example 1, less zinc is doped during the magnetite formation process, which increases the iron content of the iron-laden product and enhances the iron-zinc separation effect.

[0071] Example 2: Microchannel 9M-35s

[0072] Compared to Example 1, this embodiment only adjusts the concentration of the alkaline solution to 9 mol / L, while keeping other conditions unchanged.

[0073] See Figure 3 As shown, the iron-laden product (microchannel 9M-35s) in this embodiment is magnetite with a good crystal structure.

[0074] See Figure 5 As shown, in this embodiment, the iron content of the iron-laden product (microchannel 9M-35s) is 61.89%, and the zinc content is 2.83%. Compared with Comparative Examples 1-4, the zinc doping during the magnetite formation process is significantly reduced, which increases the iron content of the iron-laden product and enhances the iron-zinc separation effect.

[0075] Example 3: Microchannel 9M-44s

[0076] Compared to Example 2, this embodiment only adjusts the flow rate of the iron-zinc mixed solution in the first preheating microchannel to 4 ml / min, the flow rate of the alkaline solution in the second preheating microchannel to 4 ml / min, and the residence time of the reaction solution obtained after mixing the iron-zinc mixed solution and the alkaline solution in the reaction microchannel to 44 s, while keeping other conditions unchanged.

[0077] See Figure 3 As shown, the iron-laden product (microchannel 9M-44s) in this embodiment is magnetite with a good crystal structure.

[0078] See Figure 5 As shown, in this embodiment, the iron content of the iron-laden product (microchannel 9M-44s) is 57.63%, and the zinc content is 2.89%. Compared with Example 2, the magnetite crystal form is better in this embodiment; compared with Comparative Examples 1-4, the zinc doping during the magnetite formation process is significantly reduced, which increases the iron content of the iron-laden product and enhances the iron-zinc separation effect.

[0079] Example 4: Microchannel 9M-88s

[0080] Compared to Example 3, this embodiment only adjusts the flow rate of the iron-zinc mixed solution in the first preheating microchannel to 2 ml / min, the flow rate of the alkaline solution in the second preheating microchannel to 2 ml / min, and the residence time of the reaction solution obtained after mixing the iron-zinc mixed solution and the alkaline solution in the reaction microchannel to 88 s, while keeping other conditions unchanged.

[0081] See Figure 6 As shown, in this embodiment, the iron content of the iron-laden product (microchannel 9M-88s) is 64.22%, and the zinc content is 5.03%. Compared with Embodiments 2 and 3, the iron and zinc contents of this embodiment are increased, which shows that precise control of the reaction time can enhance the separation of iron and zinc during the formation of magnetite.

[0082] Comparative Example 1: Macroscopic Mixture 7M-35s

[0083] Ferrous sulfate, ferric sulfate, zinc sulfate, and a sulfuric acid solution with pH=1 were mixed to obtain an iron-zinc mixed solution. Sodium hydroxide was mixed with water to obtain an alkaline solution. Both reaction solutions were subjected to oxygen removal treatment.

[0084] In the iron-zinc mixed solution, the concentration of ferrous ions is 0.0167 mol / L, the concentration of ferric ions is 0.0334 mol / L, and the concentration of zinc ions is 0.05 mol / L; the concentration of the alkaline solution (sodium hydroxide solution) is 7 mol / L.

[0085] 50 mL of alkaline solution was poured into a container containing 50 mL of iron-zinc mixed solution within 10 seconds. After sealing, the container was stirred in a 60°C water bath at a speed of 200 r / min for 35 seconds. After the reaction was completed, the container was cooled in an ice-water bath. After cooling, the mixture was filtered, and the solid phase was dried under vacuum to obtain the precipitated iron product. The elemental content of the product was then analyzed.

[0086] The test procedure for elemental content is as follows: Weigh 0.02g of the precipitated iron product, dissolve it in concentrated hydrochloric acid, dilute to 50mL in a colorimetric tube, and then determine the iron and zinc content using ICP-OES.

[0087] See Figure 4 As shown, in this comparative example, the iron content of the precipitated iron product (macro-mixed 7M-35s) was 50.78%, and the zinc content was 10.01%.

[0088] Comparative Example 2: Macroscopic Mixture 7M-600s

[0089] Compared to Comparative Example 1, this comparative example only changed the stirring time to 600s, while keeping all other conditions unchanged.

[0090] See Figure 4 As shown, in this comparative example, the iron content of the precipitated iron product (macroscopic mixture 7M-600s) was 52.28%, and the zinc content was 7.43%.

[0091] Comparative Example 3: Macroscopic Mixture 9M-35s

[0092] Compared to Comparative Example 1, this comparative example only changed the concentration of the alkaline solution to 9 mol / L, while keeping all other conditions unchanged.

[0093] See Figure 5 As shown, in this comparative example, the iron content of the precipitated iron product (macro-mixed 9M-35s) was 54.03%, and the zinc content was 7.01%.

[0094] Comparative Example 4: Macroscopic Mixture 9M-600s

[0095] Compared to Comparative Example 3, this comparative example only changed the stirring time to 600s, while keeping all other conditions unchanged.

[0096] See Figure 5 As shown, in this comparative example, the iron content of the precipitated iron product (macroscopic mixture 9M-600s) was 54.98%, and the zinc content was 6.19%.

[0097] Comparative Example 5: Macroscopic Mixing 7M - 600s - 500r / min

[0098] Compared to Comparative Example 2, this comparative example only changed the stirring speed to 500 r / min, while keeping other conditions unchanged.

[0099] See Figure 7 As shown, in this comparative example, the iron content of the precipitated iron product (macroscopic mixing 7M-600s-500r / min) was 52.21%, and the zinc content was 6.97%.

[0100] 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 using the contents of the present invention under the technical concept of the present invention, 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 iron precipitation based on an iron-zinc mixture, characterized in that, include: The iron-zinc mixture is injected into the first liquid inlet passage of the mixing connector through the first preheating microchannel, and the alkaline solution is injected into the second liquid inlet passage of the mixing connector through the second preheating microchannel, so that the iron-zinc mixture and the alkaline solution come into contact in the mixing connector to obtain a reaction solution. The reaction liquid is introduced into the reaction microchannel through the outlet passage of the mixing connector, and the product flowing out of the reaction microchannel is collected to obtain a suspension; the suspension is then separated into solid and liquid components to obtain precipitated iron solids, which are magnetite. In the iron-zinc mixture, the total concentration of ferrous ions and ferric ions is 0.01-0.2 mol / L, and the concentration of zinc ions is 0.01-0.2 mol / L; the molar ratio of ferrous ions to ferric ions is 1:1-5; the concentration of alkaline substances in the alkaline solution is 3-10 mol / L; and the residence time of the reaction solution in the reaction microchannel is 29-88 s.

2. The iron precipitation method based on an iron-zinc mixture according to claim 1, characterized in that, The iron deposition method is carried out in a microchannel reactor; the microchannel reactor includes a liquid delivery mechanism and a reaction mechanism; the liquid delivery mechanism includes a first liquid delivery component and a second liquid delivery component; the reaction mechanism includes a first preheating microchannel, a second preheating microchannel, the mixing connector, and the reaction microchannel; The outlet of the first liquid delivery component is connected to the inlet of the first preheating microchannel, and the outlet of the second liquid delivery component is connected to the inlet of the second preheating microchannel; the mixing connector has a first liquid inlet passage, a second liquid inlet passage, and a liquid outlet passage, the first liquid inlet passage is connected to the outlet of the first preheating microchannel, the second liquid inlet passage is connected to the outlet of the second preheating microchannel, and the liquid outlet passage is connected to the inlet of the reaction microchannel.

3. The iron precipitation method based on an iron-zinc mixture according to claim 2, characterized in that, Both the first liquid delivery assembly and the second liquid delivery assembly include an injection pump; The first preheating microchannel, the second preheating microchannel, and the reaction microchannel are all spiral tubes with an inner diameter of 2-6 cm; the inner diameters of the first preheating microchannel, the second preheating microchannel, and the reaction microchannel are all 0.8-1.2 mm; the lengths of the first preheating microchannel and the second preheating microchannel are both 2-5 m, and the length of the reaction microchannel is 2-10 m. The mixing connector is a T-shaped three-way connector. The first liquid inlet passage and the liquid outlet passage are on the same straight line, and the second liquid inlet passage is perpendicular to the first liquid inlet passage. The liquid outlets of the first liquid inlet passage and the second liquid inlet passage are connected to the liquid inlet of the liquid outlet passage. The inner diameters of the first liquid inlet passage, the second liquid inlet passage, and the liquid outlet passage are all 0.5-1.0 mm.

4. The iron precipitation method based on an iron-zinc mixture according to claim 2, characterized in that, The microchannel reactor also includes a temperature control component and / or a collection container; The temperature control component is used to heat the first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel, and the collection container is used to receive the product flowing out of the reaction microchannel.

5. The iron precipitation method based on an iron-zinc mixture according to claim 2, characterized in that, The iron-zinc mixture is injected into the first inlet passage of the mixing connector from the first preheating microchannel under the push of the first liquid delivery component, and the alkali solution is injected into the second inlet passage of the mixing connector from the second preheating microchannel under the push of the second liquid delivery component.

6. The iron precipitation method based on an iron-zinc mixture according to claim 1, characterized in that, The flow rate of the iron-zinc mixture in the first preheating microchannel and the flow rate of the alkali solution in the second preheating microchannel are both 2-6 ml / min.

7. The iron precipitation method based on an iron-zinc mixture according to claim 1, characterized in that, The first preheating microchannel, the second preheating microchannel, the mixing connector, and the reaction microchannel are all in an environment of 50-90°C.

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