Method for the co-precipitation enrichment of dispersed metals based on a microfluidic metallurgical system
Patent Information
- Application Number
- CN202610614998.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-05-07
- Publication Date
- 2026-09-25
AI Technical Summary
[0006]因此，为解决传统釜式反应传质传热受限、沉淀效率低及铝硅损失大的缺陷，开发一种基于微流体冶金体系的连续流制备工艺，对于稀散金属的高效富集及降低铝硅损失具有重要的工程应用价值
[0034]（1）工艺效率与稳定性高：
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Figure CN122811552A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of hydrometallurgy and microchemical technology, and in particular to a method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system. Background Technology
[0002] Rare dispersed metals (Rb, Ga, Ge, V, etc.) are key resources for industries such as semiconductors, energy storage, and deep space exploration, and are often concentrated in the sodium aluminate mother liquor of the alumina industry. However, this mother liquor has extreme characteristics of being strongly alkaline, highly saline, and containing multiple components, making the efficient and selective enrichment of trace rare dispersed metals a significant challenge for the industry. Therefore, achieving efficient enrichment of these rare dispersed metals in such a complex industrial system has become a challenge.
[0003] Current industrial preparation mainly relies on the traditional batch co-precipitation method. This method is limited by low macroscopic mixing efficiency and slow heat transfer rate (heating hysteresis), resulting in significant pH and temperature gradients within the reaction system.
[0004] Furthermore, traditional room temperature or conventional heating co-precipitation methods inevitably result in significant precipitation losses of valuable elements (such as silicon and aluminum) in the mother liquor, disrupting the original industrial production cycle. This method also suffers from poor batch stability and is difficult to implement for continuous production.
[0005] Microreactor technology enables extremely rapid mixing of fluids thanks to its micron-scale channels.
[0006] Therefore, in order to solve the defects of traditional batch reaction with limited mass and heat transfer, low precipitation efficiency and large aluminum and silicon loss, a continuous flow preparation process based on microfluidic metallurgy system is developed, which has important engineering application value for the efficient enrichment of rare and dispersed metals and the reduction of aluminum and silicon loss. Summary of the Invention
[0007] In view of this, the present invention provides a method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system. This method utilizes the enhanced mixing effect of a microreactor to trigger transient co-precipitation, followed by the introduction of microwave crystallization technology to accelerate nucleation and improve solid-liquid separation performance, thereby efficiently enriching rare and dispersed metals such as Rb, Ga, Ge, and V. Ultimately, the present invention successfully develops a short-process technology with low energy consumption, low aluminum and silicon loss, and ease of continuous production.
[0008] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:
[0009] A method for enriching rare and dispersed metals based on iron-based co-precipitation using a microfluidic metallurgical system includes the following steps:
[0010] (1) Use the strongly alkaline sodium aluminate mother liquor containing rare dispersed metals as the A phase fluid;
[0011] (2) Prepare an iron salt solution containing iron ions as phase B fluid;
[0012] (3) The sodium aluminate mother liquor and the iron salt solution are respectively transported to the microchannel reactor system and mixed in contact without the addition of a pH adjuster. The alkalinity of the liquid to be treated itself is used to initiate a co-precipitation reaction to form a slurry.
[0013] (4) The slurry is microwave crystallized under closed heating conditions to induce the formation of a coprecipitation system in situ;
[0014] (5) The crystallized slurry is subjected to solid-liquid separation, and the resulting solid is a coprecipitated product enriched with rare dispersed metals.
[0015] Preferably, in step (1), the liquid contains silicate and aluminate.
[0016] Preferably, in step (1), the sodium aluminate mother liquor is a seed mother liquor from the industrial alumina production process; the rare dispersed metal includes at least one or more of gallium (Ga), rubidium (Rb), germanium (Ge), and vanadium (V).
[0017] Preferably, in step (2), the iron salt includes, but is not limited to, one or more of ferric sulfate, ferric chloride, ferric nitrate, or organic iron salts.
[0018] Preferably, in step (2), Fe 3+ with Fe 2+ The molar ratio is (0-2):1.
[0019] Preferably, in step (3), the sodium aluminate mother liquor and the iron salt solution are mixed in contact at a volume ratio of 1:1 to 50:1.
[0020] Preferably, in step (3), the channel characteristic size of the microchannel reactor system is 0.5-1.5 mm, and the total fluid residence time does not exceed 1 s.
[0021] Preferably, in step (3), during the micro-mixing stage, core-induced generation and rare metal capture reactions occur, and the main chemical reaction equations include, but are not limited to:
[0022] (a) Rapid nucleation reaction of Fe-based seed crystals in microfluidic metallurgy:
[0023] ;
[0024] (b) Isomorphic substitution coprecipitation reaction of gallium (Ga) and germanium (Ge):
[0025] ;
[0026] or ;
[0027] (c) Strong adsorption and co-precipitation reaction of associated impurity vanadium V:
[0028] .
[0029] Preferably, in step (4), the microwave crystallization temperature is controlled between 70°C and 80°C, and the crystallization time does not exceed 30 minutes to maintain the stability of sodium aluminate in the solution to be treated;
[0030] Meanwhile, microwave crystallization is not a necessary process, and the slurry in step (3) can be directly separated into solid and liquid.
[0031] Preferably, step (5) is followed by a washing step:
[0032] The coprecipitated product is washed with deionized water or hot alkaline solution at 30℃-60℃ to remove the sodium aluminate impurities physically attached to the surface; then it is rinsed 2-3 times with low-temperature water to retain the rare dispersed metals in the precipitated product.
[0033] The present invention achieves the following technical effects compared to the prior art:
[0034] (1) High process efficiency and stability:
[0035] This invention compresses the traditional reaction cycle of several hours to less than 1 minute, which facilitates efficient mixing in microfluidic metallurgical processes and promotes rapid reaction.
[0036] The channel effectively eliminates the amplification effect, and the wall shear force generated by the high flow rate significantly reduces the risk of blockage;
[0037] (2) Unconventional and innovative designs in chemometrics:
[0038] This invention overturns the traditional understanding of "excessive carrier" and innovatively uses iron salt (iron salt / metal molar ratio of only about 0.056 times) in a state of significant stoichiometry deficiency as "inducing seed crystal";
[0039] Using this extremely small amount of seed crystals, a large-scale in-situ co-precipitation of a multiphase system was successfully triggered under a microwave field, achieving targeted enrichment with extremely small iron source consumption;
[0040] (3) Significant economic benefits:
[0041] The improved mass and heat transfer efficiency of this invention reduces energy consumption per unit product by approximately 40%; the modular design of the microreactor reduces the equipment footprint by 80% and facilitates capacity expansion through "numerical scaling-up," eliminating the traditional scale-up challenges.
[0042] (4) Compatible with industrial balances and impurity control:
[0043] This invention avoids excessive dilution of the mother liquor and excessive accumulation of single impurity ions by matching a high-concentration, multi-source iron salt system with a large flow rate ratio feed.
[0044] Since the target rare metal exists in trace amounts in the mother liquor, the absolute physical quantity of the high-concentration acidic iron salt solution required is extremely small.
[0045] Compared to the large alkali buffer capacity of sodium aluminate mother liquor, the co-precipitation process consumes a very small percentage (usually less than 0.5%) of the total caustic alkali concentration in the mother liquor. This not only effectively maintains the system's water balance but also prevents the unstable precipitation of sodium aluminate in the main process, perfectly meeting the anti-interference requirements of industrial systems. Attached Figure Description
[0046] Figure 1 The image shows the XRD pattern of the iron-based coprecipitate obtained in Example 1.
[0047] Figure 2 The FESEM and EDS spectra of the iron-based precipitate obtained in Example 1 are shown.
[0048] Wherein, a is the FESEM image of the iron-based precipitate obtained in Example 1; b is the EDS spectrum of the iron-based precipitate obtained in Example 1.
[0049] Figure 3 This is a loss rate distribution diagram of Al and Si in Embodiments 1, 2 and 3 of the present invention. Detailed Implementation
[0050] 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 some embodiments of the present invention, and not all embodiments. 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.
[0051] It should also be noted that, considering the strict limitations on the accumulation of impurities (such as sulfate) in the main process of alumina Bayer process production, in the alternative embodiments of the present invention, the iron salt source can be one or more of the following, in addition to ferric sulfate: ferric chloride (FeCl3), ferric nitrate (Fe(NO3)3), or organic iron salts (such as ferric acetate, ferric oxalate, etc.). Using these sulfate-free iron salts can completely solve the problem of sulfate being introduced into the sodium aluminate mother liquor recycling system from the source, greatly simplifying the subsequent impurity balancing and treatment process of the mother liquor.
[0052] This invention discloses a method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system, comprising the following steps:
[0053] (1) Use the strongly alkaline sodium aluminate mother liquor containing rare dispersed metals as the A phase fluid;
[0054] (2) Prepare an iron salt solution containing iron ions as phase B fluid;
[0055] (3) The sodium aluminate mother liquor and the iron salt solution are respectively transported to the microchannel reactor system and mixed in contact without the addition of a pH adjuster. The alkalinity of the liquid to be treated itself is used to initiate a co-precipitation reaction to form a slurry.
[0056] (4) The slurry is microwave crystallized under closed heating conditions to induce the formation of a coprecipitation system in situ;
[0057] (5) The crystallized slurry is subjected to solid-liquid separation, and the resulting solid is a coprecipitated product enriched with rare dispersed metals.
[0058] In step (1), the liquid contains silicate and aluminate.
[0059] In step (1), the sodium aluminate mother liquor is the seed mother liquor in the industrial alumina production process; the rare dispersed metals include at least one or more of gallium (Ga), rubidium (Rb), germanium (Ge), and vanadium (V).
[0060] In step (2), the iron salt includes, but is not limited to, one or more of ferric sulfate, ferric chloride, ferric nitrate, or organic iron salts.
[0061] In step (2), Fe 3+ with Fe 2+ The molar ratio is (0-2):1.
[0062] In step (3), the sodium aluminate mother liquor and the iron salt solution are mixed in contact at a volume ratio of 1:1 to 50:1.
[0063] In step (3), the channel characteristic size of the microchannel reactor system is 0.5-1.5 mm, and the total fluid residence time does not exceed 1 s.
[0064] In step (3), during the micro-mixing stage, core-induced generation and rare metal capture reactions occur. The main chemical reaction equations include, but are not limited to:
[0065] (a) Rapid nucleation reaction of Fe-based seed crystals in microfluidic metallurgy:
[0066] ;
[0067] (b) Isomorphic substitution coprecipitation reaction of gallium (Ga) and germanium (Ge):
[0068] ;
[0069] or ;
[0070] (c) Strong adsorption and co-precipitation reaction of associated impurity vanadium V:
[0071] .
[0072] In step (4), the microwave crystallization temperature is controlled between 70℃ and 80℃, and the crystallization time does not exceed 30 min in order to maintain the stability of sodium aluminate in the solution to be treated.
[0073] Meanwhile, microwave crystallization is not a necessary process, and the slurry in step (3) can be directly separated into solid and liquid.
[0074] Step (5) is followed by a washing step:
[0075] The coprecipitated product is washed with deionized water or hot alkaline solution at 30℃-60℃ to remove the sodium aluminate impurities physically attached to the surface; then it is rinsed 2-3 times with low-temperature water to retain the rare dispersed metals in the precipitated product.
[0076] Example 1:
[0077] 200 ml of industrial sodium aluminate mother liquor (containing elements such as Si, Al, K, Cl, Ga, Ge, Rb, and V) was used as phase A, and 100 ml of a mixed acidic solution of FeSO4 and Fe2(NO3)3 (Fe 3+ :Fe 2+ = 1:1, total iron concentration 0.25 mmol / L) as phase B.
[0078] Phases A and B are simultaneously pumped into a Y-type micro-mixer at a flow rate ratio of 2:1 (to adapt to industrial water balance, high-concentration iron salt can be used in actual production to increase the volumetric flow rate ratio of A:B to more than 10:1).
[0079] After mixing, the slurry is immediately placed into the microwave cavity. The microwave power is set to 300W to rapidly heat the slurry to 75°C and maintain flash mineralization for 20 minutes. After the process is completed, centrifugation is performed immediately at a speed of 8000 r / min for 5 minutes.
[0080] Subsequently, the solid product was washed 2-3 times with anhydrous ethanol and deionized water and then dried at 60°C to finally obtain a composite coprecipitate with an actual weight of about 2.16 g, denoted as Fe-1.
[0081] Theoretical calculation and metrological control: According to precise instrument detection, the total molar amount of target rare and dispersed metals (Ga, Rb, etc.) in 100 ml of A phase mother liquor is approximately 0.442 mmol.
[0082] In this embodiment, a mixed iron salt solution with a total iron concentration of only 0.25 mmol / L was used, so that the total iron content in 100 ml of phase B was only 0.025 mmol.
[0083] Calculations show that the molar ratio of the precipitant iron salt to the target rare metal in the mother liquor is 0.056 times (i.e., it is in a state of significant stoichiometry deficiency).
[0084] This means that this process abandons the excessive consumption of reagents and instead uses this trace amount of iron (0.056 times) as a highly active in-situ seed crystal to trigger precipitation.
[0085] Example 2:
[0086] The preparation method is the same as in Example 1, except that the flow rate ratio of phases A and B is changed to 1:1, and the stoichiometric ratio of iron salt to rare dispersed metal is 0.112 times (less than 0.112 times). A composite coprecipitate with an actual weight of 2.24 g is obtained and is denoted as Fe-2.
[0087] Example 3:
[0088] Using 1 M NaOH solution as phase A (simulating the strongly alkaline environment of sodium aluminate mother liquor), a mixed acidic solution of FeSO4 and Fe2(NO3)3 (Fe 3+ :Fe 2+ = 1:1, total iron concentration 0.25 mmol / L) as phase B.
[0089] Phases A and B are simultaneously pumped into a Y-type micro-mixer at a flow rate ratio of 1:1, and then the reactants are immediately centrifuged at a speed of 8000 r / min for 5 min.
[0090] Then, 2g of iron powder (Fe(OH)) was added. x / Fe x-1 O x The stoichiometric ratio of iron salt to rare and dispersed metals was 50.27 times (excessive), and the mixture was added to the sodium aluminate mother liquor and stirred for 20 h to precipitate.
[0091] After the mixing process is completed, the slurry is immediately centrifuged at a speed of 8000 r / min for 5 min.
[0092] Subsequently, the solid product was washed 2-3 times with anhydrous ethanol and deionized water, and then dried at 60°C to obtain a coprecipitate with a total mass of 2.223 g, which was designated as Fe-3.
[0093] Comparative Example 1: The actual sodium aluminate mother liquor (containing elements such as Si, Al, K, Cl, Ga, Ge, Rb, and V) mentioned above is denoted as Mother Liquor-1.
[0094] Results and Conclusions
[0095] Tables 1 and 2 illustrate the effect of the microfluidic metallurgical system described in this patent on the precipitation of rare dispersed metals, demonstrating that the system effectively precipitates and enriches the rare dispersed metals Ga, Rb, and Ge from industrial sodium aluminate solutions. Furthermore, compared to microfluidic preparation of Fe(OH)₂ alone... x / Fe x-1 O x For the precipitation of rare and dispersed metals, the introduction of a microwave field also promotes the precipitation of aluminosilicates in sodium aluminate solution and the adsorption and locking of Rb.
[0096] Table 1: Precipitated content of rare and dispersed precious metals and Al and Si contents
[0097]
[0098] Table 2: Precipitated content of rare and dispersed precious metals and Al and Si contents
[0099]
[0100] Figure 1 The image shows the XRD pattern of the Fe-1 rare metal enrichment precipitate prepared in Example 1.
[0101] The figure shows obvious Fe3O4 diffraction peaks at positions 30.1°, 35.4°, 56.9°, and 62.5°, while the peak at 21.9° is attributed to the formation of amorphous aluminosilicates. The remaining peaks correspond to the characteristic peaks of KCl and sodalite, respectively.
[0102] Figure 2 The images show the FESEM and EDS spectra of Fe-1 obtained in Example 1.
[0103] Due to Fe 3-x Ga x O4 is encapsulated by amorphous silicates, which showed a low elemental distribution in EDS, while amorphous regular salts and Rb were more abundant, indirectly indicating the enrichment effect of amorphous silicates and satellite sodalite on Rb.
[0104] Figure 3 This is a loss rate distribution diagram of Al and Si in Embodiments 1, 2 and 3 of the present invention.
[0105] Material balance calculations based on solid-phase mass balance and loss rate data show that the traditional long-term powder physical adsorption method (Fe-3) leads to a high loss rate of Al in the mother liquor (5.21%). However, the microfluidic-microwave optimization process (Fe-2) of this invention successfully triggers multiphase in-situ co-precipitation using only 0.112 times the amount of iron seed crystals, while breaking through and further suppressing the co-precipitation loss rate of the most economically valuable Al to an extremely low level of 4.74%.
[0106] This process perfectly demonstrates the superior metallurgical engineering strategy of "using extremely low iron consumption to induce the precipitation of impurity silicon as an active carrier, in exchange for high-value rare and dispersed metals, and to preserve the main aluminum resources to the greatest extent."
[0107] Therefore, this invention utilizes microfluidic metallurgy combined with microwave rapid nucleation technology to achieve continuous and efficient synthesis of iron-based coprecipitates. While controlling the loss of aluminum and silicon resources, it achieves the effective enrichment and separation recovery of rare dispersed metals (Ga, Rb, Ge, V) in strongly alkaline solutions, demonstrating promising prospects for industrial application.
[0108] This invention uses trace amounts of iron salt with insufficient stoichiometry as seed crystals, overturning the traditional co-precipitation technique that requires a large excess of carrier. Under the efficient mass transfer of microfluidic channels, the co-precipitation process can be completed in a very short reaction time. It has the advantages of low energy consumption, small footprint, stable process, and compliance with existing industrial balance and impurity control requirements. It can efficiently enrich and recover target rare and dispersed metals while preserving aluminum resources in the main process to the greatest extent, providing a brand-new technical route for the low-cost extraction of rare and dispersed metals by-products in the alumina industry.
[0109] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the technical scope of the present invention. Therefore, any minor modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.
Claims
1. A method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system, characterized in that, Includes the following steps: (1) Use the strongly alkaline sodium aluminate mother liquor containing rare dispersed metals as the A phase fluid; (2) Prepare an iron salt solution containing iron ions as phase B fluid; (3) The sodium aluminate mother liquor and the iron salt solution are respectively transported to the microchannel reactor system and mixed in contact without the addition of a pH adjuster. The alkalinity of the liquid to be treated itself is used to initiate a co-precipitation reaction to form a slurry. (4) The slurry is microwave crystallized under closed heating conditions to induce the formation of a coprecipitation system in situ; (5) The crystallized slurry is subjected to solid-liquid separation, and the resulting solid is a coprecipitated product enriched with rare dispersed metals.
2. The method for enriching rare and dispersed metals based on iron-based co-precipitation using a microfluidic metallurgical system according to claim 1, characterized in that, In step (1), the liquid contains silicate and aluminate.
3. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, In step (1), the sodium aluminate mother liquor is a seed mother liquor in the industrial alumina production process; the rare dispersed metal includes at least one or more of gallium (Ga), rubidium (Rb), germanium (Ge), and vanadium (V).
4. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, In step (2), the iron salt includes, but is not limited to, one or more of ferric sulfate, ferric chloride, ferric nitrate, or organic iron salts.
5. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, In step (2), Fe 3+ with Fe 2+ The molar ratio is (0-2):
1.
6. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, In step (3), the sodium aluminate mother liquor and the iron salt solution are mixed in contact at a volume ratio of 1:1 to 50:
1.
7. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, In step (3), the channel characteristic size of the microchannel reactor system is 0.5-1.5 mm, and the total fluid residence time does not exceed 1 s.
8. The method for enriching rare and dispersed metals based on iron-based co-precipitation using a microfluidic metallurgical system according to claim 1, characterized in that, In step (3), during the micro-mixing stage, core-induced generation and rare metal capture reactions occur. The main chemical reaction equations include, but are not limited to: (a) Rapid nucleation reaction of Fe-based seed crystals in microfluidic metallurgy: ； (b) Isomorphic substitution coprecipitation reaction of gallium (Ga) and germanium (Ge): ； or ; (c) Strong adsorption and co-precipitation reaction of associated impurity vanadium V: 。 9. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, In step (4), the microwave crystallization temperature is controlled between 70℃ and 80℃, and the crystallization time does not exceed 30 min in order to maintain the stability of sodium aluminate in the solution to be treated. Meanwhile, microwave crystallization is not a necessary process, and the slurry in step (3) can be directly separated into solid and liquid.
10. The method for enriching rare and dispersed metals by iron-based co-precipitation based on a microfluidic metallurgical system according to claim 1, characterized in that, The step (5) is followed by a washing step: The coprecipitated product is washed with deionized water or hot alkaline solution at 30℃-60℃ to remove the sodium aluminate impurities physically attached to the surface; then it is rinsed 2-3 times with low-temperature water to retain the rare dispersed metals in the precipitated product.