A magnetic yellow potassium vanadium iron composite material for copper and zinc recovery of acid mine drainage and a preparation method and application thereof

Abstract

The application belongs to the technical field of inorganic composite materials and wastewater treatment, and relates to a magnetic jarosite-vanadium ferrite composite material for recovering copper and zinc in acid mine wastewater as well as a preparation method and application of the magnetic jarosite-vanadium ferrite composite material. The composite material has a core-shell structure, the inner core is superparamagnetic ferroferric oxide nanoparticles, and the shell layer is high-crystallinity jarosite crystals. The preparation method comprises the following steps: preparing ferroferric oxide nano cores; preparing a jarosite precursor solution; performing hierarchical grinding, multi-stage gradient heating treatment, and then gradient drying and alkali treatment and activation to obtain the magnetic jarosite-vanadium ferrite composite material. The composite material has uniform particle size, good monodispersity, rapid magnetic response, large specific surface area, high adsorption capacity, and strong cyclic stability. When applied to the adsorption and recovery of copper and zinc ions in acid mine wastewater, the composite material can realize rapid magnetic separation, has excellent desorption and regeneration performance, has a high adsorption capacity retention rate after cyclic use, and does not cause secondary pollution.

Description

Technical Field

[0001] This invention belongs to the field of inorganic composite materials and wastewater treatment technology, and relates to a magnetic vanadium-iron composite material for copper-zinc recovery from acidic mining wastewater, its preparation method and application. Background Technology

[0002] Acidic mine wastewater (AMD) is a typical type of highly polluting wastewater generated during mining operations. Its pH value is typically between 1.5 and 3.5, and it contains high concentrations of sulfates and Cu. 2+ Zn 2+ Pb 2+ The presence of various heavy metal ions, if directly discharged, can severely damage the surrounding soil and aquatic ecosystems, while also wasting valuable metal resources. Current treatment methods mainly rely on lime neutralization and modified clay adsorption. Although these methods can reduce the acidity and heavy metal concentration of wastewater to some extent, they easily generate large amounts of hazardous waste sludge and cannot achieve resource recovery of valuable metals, resulting in high treatment costs and a significant risk of secondary pollution.

[0003] Potassium ferric sulfate (KFe3(SO4)2(OH)6) has become a superior material in the treatment of acidic mine wastewater due to its unique tunnel-type crystal structure, large specific surface area, and strong heavy metal co-precipitation and adsorption capabilities. However, pure potassium ferric sulfate has significant limitations in practical applications. Its solid-liquid separation is difficult, its recycling rate is low, and its uneven particle size distribution leads to poor adsorption kinetics, making it difficult to meet the dual requirements of efficient separation and resource recovery in the treatment of industrial-grade acidic mine wastewater. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a magnetic potassium-iron-vanadium composite material with high crystallinity, narrow particle size distribution, strong magnetic response, and high adsorption capacity. The material's structure and properties are optimized through a multi-stage, precisely temperature-controlled, and gradient-heating hydrothermal crystallization process. This material is then applied to Cu in acidic mining wastewater. 2+ Zn 2+ The recycling and treatment process achieves the integration of wastewater purification and valuable metal resource utilization, providing a new technological approach for the efficient treatment of acidic mine wastewater.

[0005] The magnetic potassium ferrovanadium composite material provided by this invention adopts a core-shell structure design, effectively combining the superior properties of the magnetic core and the potassium ferrovanadium shell. Specifically, the core of the composite material consists of superparamagnetic Fe3O4 nanoparticles with a precisely controlled particle size between 8-12 nm, ensuring excellent magnetic response performance. The shell consists of highly crystalline potassium ferrovanadium crystals with a particle size controlled between 200-300 nm and a specific surface area of ​​120-150 m². 2 / g provides ample active sites for the adsorption of heavy metal ions.

[0006] The overall particle size of the composite material is strictly controlled within 300-500 nm, with a particle size distribution coefficient ≤0.15 and good monodispersity, effectively avoiding the low adsorption efficiency problem caused by the uneven particle size of traditional materials. In terms of component ratio, the Fe3O4 magnetic core accounts for 12-18% by mass, and the jaundice iron alum shell accounts for 82-88% by mass. This ratio has been precisely optimized, achieving a synergistic improvement in the material's adsorption performance and magnetic response performance. Its saturation magnetization can reach 45-55 emu / g, and the magnetic response time is ≤10s, enabling rapid and efficient separation of the material from wastewater.

[0007] The specific preparation method is as follows:

[0008] Step 1: Dissolve FeCl3·6H2O and FeSO4·7H2O in oxygen-free deionized water at a molar ratio of (2.05-2.15):1 to achieve a total iron concentration of 0.8-1.0 mol / L. An oxygen-free environment effectively prevents Fe... 2+ Oxidation was performed to ensure the purity of the Fe3O4 nanonuclei. Under inert gas protection, the temperature was raised to 84-86℃, and the pH was adjusted to 10.4-10.6 with NaOH solution. After stirring for 60 min, the Fe3O4 precursor was obtained. The precursor was transferred to a high-pressure reactor lined with polytetrafluoroethylene with a filling rate of 75-80%, and hydrothermally reacted at 178-182℃ for 4 h to further control the particle size and crystallinity of the nanonuclei. After the reaction, the mixture was naturally cooled to room temperature, and the product was separated using a 0.5T permanent magnet. The product was washed sequentially with oxygen-free deionized water and anhydrous ethanol until the pH reached 7.0±0.05, and then dried at 60℃ and -0.095MPa for 12 h to obtain Fe3O4 nanonuclei with a particle size of 8-12 nm and good monodispersity.

[0009] Preferably, the oxygen content in the oxygen-free deionized water is <0.5 mg / L.

[0010] Preferably, the concentration of the NaOH solution is 5 mol / L, and the dropping rate is 0.5 mL / min.

[0011] Step 2: Mix K2SO4, Fe2(SO4)3·9H2O with a 0.5 mol / L H2SO4 solution at a molar ratio of K... + :Fe 3+ :SO4 2- The solutions were mixed in a 1:3:2 ratio and stirred at 44-46℃ for 30 min to obtain a potassium ferric sulfate precursor solution with a total iron concentration of 0.6-0.7 mol / L. The pH was then adjusted to 1.8±0.05 to lay the foundation for the directional growth of potassium ferric sulfate crystals.

[0012] Step 3: Mix Fe3O4 nanonuclei and potassium ferrous sulfate precursor solution at a mass ratio of (15-17):100, and sonicate at 40kHz and 300W for 20 minutes to obtain a homogeneous mixed suspension. This ensures that the Fe3O4 nanonuclei are uniformly dispersed in the precursor solution, preventing magnetic phase agglomeration. Evaporate and concentrate the suspension at 54-56℃ to a solid content of 45-50%, obtaining a wet mixed precursor. Precise temperature control can prevent uneven particle size caused by excessively rapid drying of the precursor. Next, a graded grinding process was used to control the particle size: coarse grinding was carried out using a planetary ball mill with zirconia grinding balls at a ball-to-material ratio of 8:1, at 300 rpm for 40 min, to obtain coarse particles with a particle size of 5-8 μm; fine grinding was carried out using a high-energy nano-grinding mill with anhydrous ethanol added as a dispersant (liquid-to-solid mass ratio of 3:1), at 1500 rpm for 90 min, with a temperature of 24-26℃ and a humidity of 34-36% throughout the process, to finally obtain an ultrafine mixed precursor with a particle size ≤200 nm and a particle size distribution uniformity ≥95%.

[0013] Step four: The ultrafine mixed precursor is mixed with oxygen-free deionized water at a mass ratio of 1:(6-8), and the temperature is increased to 119-121℃ at a rate of 0.4-0.6℃ / min and held for 2 hours to activate the hydroxyl groups on the Fe3O4 core surface, providing active sites for the formation of potassium vanadium crystal nuclei. The temperature is then increased to 159-161℃ at the same rate and held for 6 hours to promote the directional growth of potassium vanadium crystals along the Fe3O4 core surface, forming a regular core-shell structure. The temperature is then increased to 198-202℃ at the same rate and held for 4 hours to further improve the crystallinity of potassium vanadium, eliminate internal crystal defects, and enhance the stability of the material. After the reaction, the mixture is naturally cooled to room temperature, and the product is separated using a 0.5T permanent magnet. The product is washed with oxygen-free deionized water until the conductivity of the washing solution is <10μS / cm to obtain the magnetic potassium vanadium-iron vanadium composite material precursor.

[0014] Step 5: Temperature and humidity control during the drying process directly affects the particle size and stability of the composite material. This step adopts a three-stage humidity gradient drying process to effectively remove free water, interstitial water and bound water from the material, and avoid material agglomeration or crystal structure damage during the drying process.

[0015] The precursor of the magnetic potassium iron vanadium composite material was dried at 45℃ for 4 hours to remove free water from the material surface; dried at 60℃ for 6 hours to remove interstitial water; and dried at 75℃ for 8 hours to remove bound water. The potassium iron vanadium powder with a particle size of 300-500 nm was collected by air classifier under inert gas protection to further ensure the uniformity of the material particle size.

[0016] To further improve the composite material's resistance to Cu 2+ Zn 2+To improve the adsorption performance, potassium vanadium iron oxide powder was mixed with 0.1 mol / L NaOH solution at a mass ratio of 1:10 and stirred at 50℃ for 30 min. This alkali treatment introduced a large number of -OH functional groups onto the material surface, enhancing its complexation ability with heavy metal ions. After treatment, the mixture was separated using a 0.5T permanent magnet, washed with deionized water until neutral, and dried to obtain a magnetic potassium vanadium iron oxide composite material.

[0017] The present invention has the following advantages:

[0018] Compared with existing materials, the magnetic potassium ferrovanadium composite material prepared by this invention has significant performance advantages and application value. Firstly, by precisely controlling the particle size of the Fe3O4 nanonucleus and the potassium ferrovanadium shell, a regular core-shell structure is constructed, achieving a balance between high adsorption capacity and rapid magnetic separation. Secondly, through multi-stage temperature, humidity, and proportion control, along with complex processes such as graded grinding and gradient crystallization, the problems of uneven particle size, poor magnetic phase loading, and low crystallinity in traditional preparation methods are solved. The material exhibits high performance stability and strong cycling stability; after five cycles, the adsorption capacity retention rate remains ≥90%, and the magnetic response performance shows no significant decrease, greatly reducing processing costs and meeting the needs of large-scale industrial production. Furthermore, no toxic reagents are added during the preparation process, and no secondary sludge is generated during wastewater treatment. This achieves full-process resource utilization from "wastewater purification - metal recovery - material regeneration," solving the pollution problem of acidic mine wastewater and realizing the recovery and utilization of valuable metals, resulting in significant environmental, economic, and social benefits. Detailed Implementation

[0019] The technical solutions in the embodiments of the invention are described clearly and completely below. 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.

[0020] Example 1

[0021] Step 1: FeCl3·6H2O and FeSO4·7H2O were dissolved in deionized water (oxygen content <0.5mg / L) at a molar ratio of 2.1:1 to make the total iron concentration 0.9mol / L. Under nitrogen protection, the temperature was raised to 85℃, and 5mol / L NaOH solution was added dropwise at a rate of 0.5mL / min to adjust the pH to 10.5±0.1. The mixture was stirred for 60min to obtain the Fe3O4 precursor. The precursor was transferred to a high-pressure reactor lined with polytetrafluoroethylene with a filling rate of 75%, and hydrothermally reacted at 180℃ for 4h. After natural cooling to room temperature, the product was separated using a 0.5T permanent magnet. The product was washed successively with deionized water and anhydrous ethanol until the pH reached 7.0±0.05, and dried at 60℃ and -0.095MPa for 12h to obtain Fe3O4 nanonuclei with a particle size of 8-12nm.

[0022] Step 2: Mix K2SO4, Fe2(SO4)3·9H2O, and a 0.5 mol / L H2SO4 solution at a molar ratio of K... + :Fe 3+ :SO4 2- Mix the solutions in a 1:3:2 ratio, stir at 45℃ for 30 min to obtain a potassium ferric sulfate precursor solution, and adjust the pH to 1.8±0.05.

[0023] Step 3: Fe3O4 nanonuclei and potassium ferrous sulfate precursor solution were mixed at a mass ratio of 16:100 and sonicated at 40kHz and 300W for 20 minutes to obtain a uniform mixed suspension. The suspension was then evaporated and concentrated at 55℃ to a solid content of 48% to obtain a wet mixed precursor. A planetary ball mill with zirconia grinding balls at a ball-to-material ratio of 8:1 was used to grind the precursor at 300rpm for 40 minutes. Then, a high-energy nano-milling mill was used with anhydrous ethanol as a dispersant (liquid-to-solid ratio of 3:1) and the precursor was ground at 1500rpm for 90 minutes. The temperature and humidity were maintained at 25℃ and 35% throughout the process. Finally, an ultrafine mixed precursor with a particle size ≤200nm and a particle size distribution uniformity ≥95% was obtained.

[0024] Step 4: Mix the ultrafine mixed precursor with oxygen-free deionized water at a mass ratio of 1:7, heat to 120℃ at a rate of 0.5℃ / min, hold for 2 hours, heat to 160℃ at the same rate, hold for 6 hours, then heat to 200℃ at the same rate, hold for 4 hours, and allow to cool naturally to room temperature. Separate the product using a 0.5T permanent magnet, and wash with oxygen-free deionized water until the conductivity of the washing solution is <10μS / cm to obtain the magnetic potassium iron vanadium composite material precursor.

[0025] Step 5: The precursor of the magnetic potassium iron vanadium composite material was dried at 45℃ for 4 hours, 60℃ for 6 hours, and 75℃ for 8 hours. Under nitrogen protection, it was sieved using an air classifier to collect potassium iron vanadium powder with a particle size of 300-500 nm. It was mixed with 0.1 mol / L NaOH solution at a mass ratio of 1:10, stirred at 50℃ for 30 minutes, separated with a 0.5T permanent magnet, washed with deionized water until neutral, and dried to obtain the magnetic potassium iron vanadium composite material.

[0026] Experimental Example 1

[0027] Prepare an acidic mine wastewater solution, adjusting the pH to 4.5 ± 0.1, and add Cu. 2+ Concentration 200 mg / L, Zn 2+ A magnetic potassium vanadium iron composite material with a concentration of 250 mg / L was added and the mixture was shaken and adsorbed at 25℃ and 150 rpm for 24 h.

[0028] After adsorption, the strong magnetic response characteristics of the composite material are utilized to perform rapid magnetic separation using a 0.8T permanent magnet, with a separation time ≤10s. This effectively solves the problem of difficult solid-liquid separation in traditional potassium ferrous sulfate compounds. The Cu in the supernatant after separation is significantly reduced. 2+ Zn 2+ The concentration removal rate reached 98%, and the material effectively removed Cu. 2+ Zn 2+ The adsorption capacities reached 185-210 mg / g and 220-245 mg / g, respectively. Subsequently, metal desorption and recovery were performed to transfer the loaded Cu... 2+ Zn 2+ The composite material was added to a 0.5 mol / L H₂SO₄ solution, with a solid-liquid ratio of 1:8. The mixture was then subjected to shaking desorption at 40 °C for 40 min. After magnetic separation, a Cu-rich solution was obtained. 2+ Zn 2+ The desorption solution has a desorption rate of ≥95%. After concentration and crystallization, copper-zinc sulfate can be recovered from the desorption solution, realizing the resource utilization of valuable metals.

[0029] The desorbed composite material can be recycled after regeneration. The specific regeneration process is as follows: the desorbed composite material is added to a 0.1 mol / L NaOH solution for 20 min to activate it, and after washing and drying, it is reused for adsorption. After 5 cycles, the adsorption capacity retention rate of the composite material is ≥90%, and the magnetic responsiveness does not decrease significantly. This greatly reduces the cost of wastewater treatment and improves the economy and feasibility of the process.

[0030] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a magnetic potassium ferrovanadium composite material for copper-zinc recovery from acidic mining wastewater, characterized in that, Includes the following steps: Step 1: Dissolve FeCl3·6H2O and FeSO4·7H2O in oxygen-free deionized water at a molar ratio of (2.05-2.15):1 to make the total iron concentration 0.8-1.0 mol / L. Adjust the pH to 10.4-10.

6. Under inert gas protection, stir at 84-86℃ for 60 min and hydrothermally react at 178-182℃ for 4 h. Separate the product, wash and dry it to obtain Fe3O4 nanonuclei. Step 2: Mix K2SO4, Fe2(SO4)3·9H2O and H2SO4 solution at a molar ratio of K + :Fe 3+ :SO4 2- Mix the solutions in a ratio of 1:3:2 and adjust the pH to 1.8±0.05 to obtain the potassium ferric sulfate precursor solution. Step 3: Mix Fe3O4 nanonuclei and potassium ferrous sulfate precursor solution at a mass ratio of (15-17):100, sonicate, evaporate and concentrate to a solid content of 45-50%, and grind to obtain an ultrafine mixed precursor. Step 4: Mix the ultrafine mixed precursor with oxygen-free deionized water at a mass ratio of 1:(6-8), heat to 119-121℃ and hold for 2 hours, heat to 159-161℃ and hold for 6 hours, heat to 198-202℃ and hold for 4 hours, cool naturally to room temperature, separate the product, wash with oxygen-free deionized water until the conductivity of the washing solution is <10μS / cm, and obtain the magnetic potassium iron vanadium composite material precursor; Step 5: The precursor of the magnetic potassium vanadium iron composite material is dried at 45℃ for 4 hours, 60℃ for 6 hours, and 75℃ for 8 hours. After sieving, potassium vanadium iron powder is obtained. It is mixed with NaOH solution at a mass ratio of 1:10, stirred, and the product is separated. It is washed with deionized water until neutral and dried to obtain the magnetic potassium vanadium iron composite material.

2. The preparation method of a magnetic potassium vanadium iron composite material for copper-zinc recovery from acidic mine wastewater according to claim 1, characterized in that, The oxygen content in the deionized water described in step one is <0.5 mg / L.

3. The preparation method of a magnetic potassium ferrovanadium composite material for copper-zinc recovery from acidic mine wastewater according to claim 1, characterized in that, In step one, the pH is adjusted using a 5 mol / L NaOH solution at a dropping rate of 0.5 mL / min.

4. The preparation method of a magnetic potassium ferrovanadium composite material for copper-zinc recovery from acidic mine wastewater according to claim 1, characterized in that, The concentration of the H2SO4 solution mentioned in step two is 0.5 mol / L.

5. The preparation method of a magnetic potassium ferrovanadium composite material for copper-zinc recovery from acidic mine wastewater according to claim 1, characterized in that, In step three, ball milling is performed at 300 rpm for 40 minutes with a ball-to-material ratio of 8:1, followed by high-energy nano-grinding at 1500 rpm for 90 minutes. Anhydrous ethanol is added as a dispersant with a liquid-to-solid ratio of 3:

1.

6. The preparation method of a magnetic potassium ferrovanadium composite material for copper-zinc recovery from acidic mine wastewater according to claim 1, characterized in that, In step five, the concentration of the NaOH solution is 0.1 mol / L.

7. The magnetic potassium vanadium iron composite material prepared by the method according to any one of claims 1-6.

8. The application of the magnetic potassium vanadium iron composite material according to any one of claims 1-7 in the field of adsorbing copper and zinc ions.