Ferrophosphorus tailing targeted flocculant based on modified chitosan microsphere-polyacrylamide as well as preparation method and application of ferrophosphorus tailing targeted flocculant
By preparing a targeted flocculant by combining modified chitosan microspheres with polyacrylamide, the problems of poor flocculation selectivity and low sedimentation efficiency in phosphate-iron tailings slurry were solved, achieving efficient and stable solid-liquid separation and selective enrichment of valuable minerals.
Patent Information
- Application Number
- CN202512002290.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-29
- Publication Date
- 2026-02-13
AI Technical Summary
Existing solid-liquid separation methods for phosphate-iron tailings slurry suffer from poor flocculation selectivity, loose floc structure, slow settling velocity, and low processing efficiency. In particular, under conditions of high fineness, conventional flocculants are unable to achieve stable and efficient solid-liquid separation.
A targeted flocculant was prepared by combining modified chitosan microspheres with polyacrylamide. During the polymerization process, magnetic chitosan microspheres and polyacrylamide were combined in situ to form a composite flocculation system with targeted adsorption and efficient bridging. The magnetic component was used to achieve rapid response and sedimentation, and the floc structure strength and sedimentation efficiency were improved through multiple mechanisms.
It significantly improves the flocculation and sedimentation performance of phosphate iron tailings, forming dense and high-strength flocs, shortening sedimentation time, improving solid-liquid separation efficiency, and reducing the risk of secondary pollution. It is highly adaptable and environmentally friendly.
Smart Images
Figure CN121516985A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of mineral processing and tailings treatment, in particular to a modified chitosan microsphere-polyacrylamide-based phosphorus iron tailings targeted flocculant, a preparation method and application thereof. BACKGROUND
[0002] Phosphorus iron tailings are a typical industrial solid waste generated in the process of mining and beneficiation of phosphate rock, iron ore and other mineral resources. They have the characteristics of large output, complex composition, wide particle size distribution range and high content of fine particles. With the increasing intensity of mineral resource development, the problems of phosphorus iron tailings storage and treatment are becoming increasingly prominent. Not only do they occupy a large amount of land resources, but the fine particles contained in the tailings are also prone to migration with water, posing a potential threat to the surrounding ecological environment and water resources safety. Therefore, efficient solid-liquid separation of phosphorus iron tailings slurry and clarification of tailings water are key technical links in the process of tailings reduction, harmlessness and resource utilization. At present, the solid-liquid separation of phosphorus iron tailings slurry usually adopts methods such as sedimentation, filtration or flocculation, among which the chemical flocculation method is widely used due to its simple operation and high treatment efficiency. Existing flocculants mainly include inorganic flocculants, organic polymer flocculants and their compound systems. However, in actual application, phosphorus iron tailings slurry often has the characteristics of high salinity, complex particle surface electrical properties and high proportion of fine and ultra-fine particles, which leads to the problems of poor flocculation selectivity, loose flocculation structure and slow settling velocity of conventional flocculants, making it difficult to achieve stable and efficient solid-liquid separation.
[0003] In addition, although single inorganic flocculants can promote the initial aggregation of particles through electrical neutralization, the strength of the formed flocculation is low and it is prone to breakage during stirring or transportation. Traditional organic polymer flocculants mainly rely on the bridging action of molecular chains, and have limited effect on tailings particles with small particle size or large surface property difference. Especially under the conditions of high solid content and high fine particles, a large dosage is often required to achieve the desired effect, increasing the treatment cost and possibly causing secondary pollution risk.
[0004] In view of the characteristics of strong dispersion, complex surface charge and difficult settling of fine mineral particles in phosphorus iron tailings, although the existing technology attempts to improve the treatment effect by compounding multiple flocculants or changing the dosage method, it still has the problems of single action mechanism, insufficient targeting, poor adaptability to different types of particles, etc., making it difficult to balance the treatment efficiency, economy and stability. Therefore, how to improve the selective action ability of the flocculant on the fine particles in the phosphorus iron tailings and the overall flocculation and sedimentation performance without significantly increasing the process complexity is still a technical problem to be solved in the field. SUMMARY
[0005] One of the technical problems to be solved by the present application is to provide a preparation method of a modified chitosan microsphere-polyacrylamide-based phosphorus iron tailings targeted flocculant, so as to solve the problems of difficulty in efficient destabilization of fine particles of phosphorus iron tailings, loose flocculation structure, slow settling velocity, low solid-liquid separation efficiency and insufficient adaptability of the flocculant in the prior art.
[0006] To overcome the defects of the prior art, the present application provides a preparation method of a modified chitosan microsphere-polyacrylamide-based phosphorus iron tailings targeted flocculant, comprising the following steps: S1. Preparation of magnetic chitosan microspheres: dissolve chitosan in an acidic aqueous solution, add magnetic nanoparticles and disperse uniformly to obtain a chitosan solution containing magnetism; mix and emulsify the solution with an oil phase containing an emulsifier to form a water-in-oil emulsion; add a crosslinking agent to the emulsion for ionic crosslinking and solidification, separate, wash and dry after the reaction is completed to obtain magnetic chitosan microspheres; S2. Preparation of polymerization solution: dissolve acrylamide monomer in deionized water to prepare acrylamide solution or mixed monomer solution containing acrylic acid; S3. Compound and polymerization: disperse the magnetic chitosan microspheres obtained in step S1 in the polymerization solution of step S2, adjust the pH of the system to near neutral, and add an initiator under inert atmosphere and low temperature conditions to carry out free radical polymerization reaction; S4. Post-treatment: granulate, dry and crush the product after polymerization reaction to obtain the targeted flocculant.
[0007] Compared with the prior art, the preparation method of the phosphorus iron tailings targeted flocculant based on modified chitosan microspheres-polyacrylamide has the following advantages: the preparation method of the present application in situ composites the magnetic chitosan microspheres and polyacrylamide in the polymerization process, and constructs a composite flocculation system with targeted adsorption and high bridging capacity. The high molecular chain of polyacrylamide can effectively connect the micro-fine particles in the phosphorus iron tailings system through adsorption bridging and form larger flocs. The magnetic chitosan microspheres not only provide a stable spatial framework for the polymer chain segment, but also can selectively bind to heavy metal ions, phosphorus-containing mineral particles and their complexes in the tailings through electrostatic interaction, coordination and hydrogen bonding, etc. The targeted flocculation capacity of the target pollutants and valuable components is significantly improved. At the same time, the introduction of the magnetic component makes the obtained flocs have the characteristics of rapid response and accelerated sedimentation under the action of an external magnetic field, effectively shortens the sedimentation time and improves the solid-liquid separation efficiency. The above various mechanisms work together in the system, making the floc structure formed by the flocculant of the present application more compact, higher in strength and less likely to break, which significantly improves the problems of loose flocs, slow sedimentation and unstable separation effect in the traditional flocculation system. Moreover, the present application uses natural polymer chitosan as the main functional component, and combines the controllable polyacrylamide system with residual monomers after polymerization, which has good environmental friendliness, can improve the efficiency of phosphorus iron tailings treatment while reducing the risk of secondary pollution, and provides favorable conditions for the selective enrichment and resource utilization of valuable minerals in tailings.
[0008] In one possible implementation, in the step S1, the acid aqueous solution is an ice acetic acid aqueous solution with a volume fraction of 2%-4%; the use amount ratio of chitosan to the acid aqueous solution is 1g:(10-20)ml; the dissolving is carried out under mechanical stirring, and the stirring rate is 700-900 rpm, and the temperature is 35-45℃.
[0009] Compared with the prior art, the present embodiment controls the concentration of ice acetic acid in the range of 2%-4%, which fully protonates the amino groups on the chitosan molecular chain, significantly improves the solubility of chitosan in water and the stretching degree of the molecular chain; further, by limiting the use amount ratio of chitosan to the acid aqueous solution to 1g:(10-20)ml, and dissolving under the conditions of a mechanical stirring rate of 700-900 rpm and a temperature of 35-45℃, the problem of local agglomeration or incomplete dissolution of chitosan is effectively avoided, and a uniform and stable chitosan solution is formed; the above conditions are jointly limited, which is beneficial to the uniform introduction of the magnetic nanoparticles and the controllable formation of the microsphere structure, thereby laying a foundation for preparing magnetic chitosan microspheres with uniform particle size distribution and stable structure.
[0010] In a possible implementation, in the step S1, the magnetic nanoparticles are Fe3O4 nanoparticles, and the mass ratio of the Fe3O4 nanoparticles to chitosan is 1:(5-10); the magnetic nanoparticles are dispersed in advance in an acetic acid solution with a concentration of 1%-3%, and then mixed with the chitosan solution.
[0011] Compared with the prior art, by selecting Fe3O4 nanoparticles as the magnetic component and limiting the mass ratio of the Fe3O4 nanoparticles to chitosan to be within the range of 1:(5-10), the magnetic response capability is ensured, and the excess of the magnetic particles is avoided to cause the microsphere structure to be brittle or agglomerate; in addition, by dispersing the Fe3O4 nanoparticles in advance in an acetic acid solution with a concentration of 1%-3%, the surface energy of the nanoparticles can be reduced and agglomeration is inhibited in the acidic environment, so that the nanoparticles can be more uniformly embedded in the microsphere skeleton after being incorporated into the chitosan solution; thus, the magnetic chitosan microspheres prepared in this way have uniform magnetic distribution and sensitive response, which is beneficial to the rapid magnetic response settlement of the flocs in the subsequent flocculation process, thereby improving the solid-liquid separation efficiency.
[0012] In a possible implementation, in the step S1, the oil phase is soybean oil; the emulsifier is Span-80, and the mass fraction of the Span-80 in the oil phase is 1%-3%; when the water-in-oil emulsion is formed, the volume ratio of the magnetic chitosan-containing acidic aqueous solution to the oil phase is 1:(2-4), and the emulsification stirring rate is 400-500 rpm.
[0013] Compared with the prior art, by selecting soybean oil as the oil phase and cooperating with the Span-80 emulsifier with a mass fraction of 1%-3%, the water-in-oil emulsion can be stably formed under lower shear conditions; at the same time, by controlling the volume ratio of the water phase to the oil phase to be within the range of 1:(2-4) and emulsifying at a stirring rate of 400-500 rpm, it is beneficial to form droplet structures with relatively concentrated particle size distribution and regular morphology; the above emulsification conditions make the chitosan solution exist in the oil phase in the form of stable microdroplets, thereby providing a uniform reaction interface for the subsequent ionic cross-linking reaction, and helping to obtain magnetic chitosan microspheres with controllable particle size and good dispersity.
[0014] In a possible implementation, in the step S1, the cross-linking agent is a sodium tripolyphosphate aqueous solution, and the mass-volume concentration of the sodium tripolyphosphate aqueous solution is 1%-5%; the cross-linking and solidification reaction is performed at 50-70 ℃, and the reaction time is 2-6 hours; after the reaction is completed, the microspheres are washed with petroleum ether, acetone, anhydrous ethanol and deionized water in sequence, and then vacuum dried or freeze-dried at 50-70 ℃ to obtain the magnetic chitosan microspheres.
[0015] Compared with the prior art, by adopting the above technical scheme, through adopting 1%-5% sodium tripolyphosphate as a crosslinking agent, and performing ion crosslinking reaction under the condition of 50-70 DEG C for 2-6 hours, stable ion crosslinking network structure can be formed between the chitosan molecular chains, which can not only ensure that the microspheres have sufficient mechanical strength, but also avoid excessive crosslinking from causing the pore structure to be closed; in addition, vacuum drying or freeze drying treatment is continuously performed under the condition of 50-70 DEG C, which is beneficial to removing the solvent while maintaining the original porous structure and specific surface area of the microspheres; through the synergistic effect of the crosslinking and drying conditions, the magnetic chitosan microspheres obtained by the embodiment have stable structure, developed pores and rich surface active sites, which provide a structural basis for subsequent compounding with polyacrylamide and efficient adsorption and flocculation of target particles in phosphorus iron tailings.
[0016] In a possible implementation, in the step S3, the polymerization solution further contains one or more of urea, sodium sulfate and polyaluminum chloride; and the pH is adjusted to 6.5-7.5 before polymerization.
[0017] Compared with the prior art, by introducing urea, sodium sulfate and / or polyaluminum chloride into the polymerization solution, the embodiment can produce a synergistic regulation effect on the ionic strength, molecular chain conformation and interface action of the system during the polymerization process: the urea is beneficial to weakening the hydrogen bond interaction between molecules during the polymerization process and promoting the full stretching of the polyacrylamide molecular chain; the sodium sulfate can inhibit the uneven entanglement of chain segments caused by local rapid polymerization by adjusting the ionic environment of the solution; the polyaluminum chloride can provide certain electrical neutralization and bridging auxiliary action in the system; at the same time, controlling the pH before polymerization in the range of 6.5-7.5 can effectively balance the reactivity of acrylamide and acrylic acid monomers, and avoid side reactions or polymerization out of control under strong acid or strong base conditions; the above conditions jointly make the polymerization process more stable, which is beneficial to forming polyacrylamide chain segments with reasonable molecular weight distribution and uniform structure, thereby improving the bridging capacity and overall flocculation performance of the composite flocculant.
[0018] In a possible implementation, in the step S3, the initiator of the polymerization reaction is a free radical initiator; nitrogen is introduced for 20-40 minutes before the reaction to create an anaerobic environment; and the initial temperature of the polymerization reaction is-5 DEG C to 0 DEG C.
[0019] Compared with the prior art, by adopting the technical scheme, the dissolved oxygen in the system is effectively removed by adopting the free radical initiator and passing nitrogen for 20-40 minutes before the reaction, so that the quenching effect of oxygen on the free radical is avoided, the initiation efficiency is ensured, and the controllable progress of the polymerization reaction is ensured; at the same time, the starting temperature of the polymerization reaction is controlled in the range of -5 DEG C to 0 DEG C, which can significantly reduce the polymerization rate at the initial stage of the reaction, inhibit the occurrence of the phenomenon of local overheating, and make the polyacrylamide molecular chain grow slowly and extend fully, and the above low temperature and oxygen-free conditions are beneficial to obtain a polymer with high molecular weight and regular chain structure, promote the formation of a more stable composite structure between the polyacrylamide segment and the surface of the magnetic chitosan microspheres in the growth process, and thus enhance the adsorption bridging capacity and flocculation stability of the flocculant.
[0020] In a possible implementation, in the step S4, the drying temperature is 85-95 DEG C.
[0021] Compared with the prior art, by controlling the drying temperature in the range of 85-95 DEG C, the residual moisture in the composite flocculant can be effectively removed, the thermal degradation of the polyacrylamide segment or the damage to the structure of the magnetic chitosan microspheres caused by excessively high temperature is avoided, the stability of the particle morphology and internal structure of the composite flocculant is maintained, and the obtained product has good storage stability and use dispersity; the targeted flocculant prepared in this way can swell quickly and fully play the roles of adsorption bridging and targeted flocculation in actual application, and the treatment efficiency and solid-liquid separation effect of the phosphorus iron tailings are improved.
[0022] Another technical problem to be solved by the present application is to provide a phosphorus iron tailings targeted flocculant based on modified chitosan microspheres-polyacrylamide, so as to solve the technical problems of poor selectivity of the flocculant to fine minerals and complex pollution components in the phosphorus iron tailings, loose flocculation structure, low settling efficiency, and difficulty in balancing rapid separation and efficient removal in the prior art.
[0023] In order to overcome the defects of the above prior art, the present application provides a targeted flocculant prepared by the preparation method.
[0024] Compared with the prior art, the phosphorus iron tailings targeted flocculant based on modified chitosan microspheres-polyacrylamide has the following advantages: the modified chitosan microspheres with rich amino and hydroxyl active sites are compounded with polyacrylamide with long chain structure to construct a flocculation system with targeted adsorption, efficient bridging, rapid separation and synergistic effect, wherein the polyacrylamide molecular chain plays a role in adsorption and bridging in the system, and can effectively connect and aggregate the fine particles destabilized after electric neutralization into flocs with large volume and dense structure; the modified chitosan microspheres realize preferential recognition and combination of target components through coordination, electrostatic and hydrogen bond effects between the surface amino and hydroxyl groups and phosphorus-containing mineral particles, heavy metal ions and organic pollutants in the tailings; at the same time, the introduced magnetic nano components endow the flocs with good magnetic response performance, so that the formed flocs can realize rapid aggregation and separation under the action of an external magnetic field; the above structure and formula synergize with each other, so that the targeted flocculant of the present application can significantly improve the floc strength, settling velocity and separation efficiency while ensuring high flocculation efficiency, and solves the problems of insufficient flocculation selectivity, slow settling and low treatment efficiency in the background technology.
[0025] The application provides an application of the targeted flocculant, and the application comprises the following steps of using the targeted flocculant to treat phosphorus iron tailings slurry: (a) analyzing the particle size distribution and Zeta potential of the phosphorus iron tailings slurry; (b) preparing the targeted flocculant into a solution with a mass concentration of 0.05%-0.3%; (c) adding the solution prepared in step (b) into the phosphorus iron tailings slurry, and realizing solid-liquid separation after mixing and static settling; In step (c), the flocculant solution is added in a segmented manner, and gradient stirring process is adopted for mixing.
[0026] Compared with the prior art, the above application of the present application can accurately control the adding mode and action stage of the flocculant according to the dispersion state and surface electric property of the tailings particles by analyzing the particle size distribution and Zeta potential of the phosphorus iron tailings slurry before adding; the targeted flocculant is prepared into a solution with a mass concentration of 0.05%-0.3%, which is beneficial to the rapid and uniform dispersion of the flocculant in the tailings slurry and the full expansion of the molecular chain; the segmented adding combined with gradient stirring can promote the sufficient contact between the flocculant and particles in the early stage and reduce the shear damage in the later stage, so as to form flocs with large particle size and stable structure; in combination with the synergistic mechanisms of targeted adsorption, long chain bridging and magnetic response separation, the settling velocity of the flocs can be significantly accelerated, the solid-liquid separation efficiency can be improved, the energy consumption and reagent consumption in the tailings treatment process can be reduced, and finally the efficient and stable treatment of the phosphorus iron tailings slurry can be realized. BRIEF DESCRIPTION OF DRAWINGS
[0027] Figure 1 The curves show the settling performance of the composite flocculant described in Example 1 of this invention compared with other types of flocculants and the settling performance of a certain phosphate-iron tailings treated in a comparative manner. Figure 2 The curve shows a comparison of the settling performance of the composite flocculant described in Example 2 of this invention with other types of flocculants in the treatment of a certain phosphate-iron tailings. Figure 3 This is a comparison curve of the settling performance of the composite flocculant used in the treatment of a phosphate-iron tailings mine in Shenyang, as described in this embodiment of the invention. Figure 4 This is a comparison curve of the settling performance of a phosphate-iron tailings ore in Guizhou treated with the composite flocculant described in this embodiment of the invention. Figure 3 In Example 4, PAM corresponds to the polyacrylamide flocculant prepared in Example 1, Fe3O4NPs-CS corresponds to the magnetic chitosan microspheres prepared in Example 2, Fe3O4NPs-CS / PAM corresponds to the chitosan microsphere / polyacrylamide blend flocculant prepared in Example 3, and Fe3O4NPs-CS / PAM corresponds to the Fe3O4NPs-CS / PAM composite targeted flocculant prepared in Example 1. Figure 5 This is a schematic flowchart of the preparation method of the modified chitosan microsphere-polyacrylamide flocculant described in this invention. Detailed Implementation
[0028] First, those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.
[0029] This invention provides a method for preparing a targeted flocculant for phosphate-iron tailings based on modified chitosan microspheres and polyacrylamide, comprising the following steps: S1. Preparation of magnetic chitosan microspheres: Chitosan was dissolved in an acidic aqueous solution, magnetic nanoparticles were added and dispersed evenly to obtain a magnetic chitosan solution; the solution was mixed and emulsified with an oil phase containing an emulsifier to form a water-in-oil emulsion; a crosslinking agent was added to the emulsion for ionic crosslinking and curing; after the reaction was completed, the mixture was separated, washed and dried to obtain magnetic chitosan microspheres; S2. Preparation of polymerization solution: Dissolve acrylamide monomer in deionized water to prepare an acrylamide solution or a mixed monomer solution containing acrylic acid; S3. Composite and Polymerization: The magnetic chitosan microspheres obtained in step S1 are dispersed in the polymerization solution of step S2, the pH of the system is adjusted to near neutral, and an initiator is added under inert atmosphere and low temperature to carry out free radical polymerization reaction; S4. Post-processing: The product after polymerization is granulated, dried and crushed to obtain the targeted flocculant.
[0030] As a preferred scheme, in the step S1, the acidic aqueous solution is 2%-4% by volume fraction of glacial acetic acid aqueous solution; the use amount ratio of chitosan to the acidic aqueous solution is 1g:(10-20)ml; the dissolving is carried out under mechanical stirring, and the stirring rate is 700-900 rpm, and the temperature is 35-45℃.
[0031] As a preferred scheme, in the step S1, the magnetic nanoparticles are Fe3O4 nanoparticles, and the mass ratio of the magnetic nanoparticles to chitosan is 1:(5-10); the magnetic nanoparticles are pre-dispersed in an acetic acid solution with a concentration of 1%-3%, and then mixed with the chitosan solution.
[0032] As a preferred scheme, in the step S1, the oil phase is soybean oil; the emulsifier is Span-80, and the mass fraction of Span-80 in the oil phase is 1%-3%; when the water-in-oil emulsion is formed, the volume ratio of the magnetic chitosan-containing acidic aqueous solution to the oil phase is 1:(2-4), and the emulsification stirring rate is 400-500 rpm.
[0033] As a preferred scheme, in the step S1, the crosslinking agent is a sodium tripolyphosphate aqueous solution, and the mass volume concentration is 1%-5%; the crosslinking and curing reaction is carried out at 50-70℃, and the reaction time is 2-6 hours; after the reaction is completed, the microspheres are washed with petroleum ether, acetone, anhydrous ethanol and deionized water in sequence, and then vacuum dried or freeze-dried at 50-70℃ to obtain the magnetic chitosan microspheres.
[0034] As a preferred scheme, in the step S3, the polymerization liquid further contains one or more of urea, sodium sulfate and polyaluminum chloride; before polymerization, the pH is adjusted to 6.5-7.5.
[0035] As a preferred scheme, in the step S3, the initiator of the polymerization reaction is a free radical initiator; before the reaction, nitrogen is introduced for 20-40 minutes to create an anaerobic environment; the starting temperature of the polymerization reaction is-5℃ to 0℃.
[0036] As a preferred scheme, in the step S4, the drying temperature is 85-95℃.
[0037] The application provides a targeted flocculant prepared by the preparation method.
[0038] The application provides an application of the targeted flocculant, and the application includes the following steps of using the targeted flocculant to treat phosphorus iron tailing slurry. (a) analyzing the particle size distribution and Zeta potential of the phosphorus iron tailings slurry; (b) formulating the targeted flocculant into a solution with a mass concentration of 0.05%-0.3%; (c) adding the solution formulated in step (b) into the phosphorus iron tailings slurry, and after mixing and standing, achieving solid-liquid separation; In step (c), the flocculant solution is added in a segmented manner, and gradient stirring process is used for mixing.
[0039] The working principle of the present application is to organically combine the long-chain adsorption bridging effect of polyacrylamide with the targeted adsorption and rapid separation characteristics of magnetic chitosan microspheres: polyacrylamide produces effective adsorption bridging effect on the destabilized fine particles through its high molecular long chain, so that the dispersed particles gradually aggregate and form dense alunite flowers; the introduced magnetic chitosan microspheres can realize rapid response and separation of the flocculation under the action of an external magnetic field on the basis of their high saturation magnetization, thereby shortening the settling time, simplifying the operation process and not introducing secondary pollution; on the other hand, the abundant amino and hydroxyl functional groups on the chitosan molecular chain can specifically bind with heavy metal ions (including Fe 2+ , Pb 2+ , Cd 2+ ) and organic pollutants (dyes, antibiotics, etc.) in the phosphorus iron tailings system through coordination, electrostatic adsorption and hydrogen bonding, etc., thereby significantly improving the adsorption capacity and flocculation efficiency of the system; under the above synergistic effect, the flocculant obtained by the present application has the advantages of strong targeting, large and dense flocculation particle structure, fast settling speed, high mechanical strength and not easy to break, which is beneficial to the subsequent solid-liquid separation and dewatering process, can effectively improve the underflow concentration and reduce the moisture content of the filter cake; at the same time, the present application can adjust the microsphere parameters and modification methods according to the mineral composition, particle size distribution and pH conditions of different phosphorus iron tailings, and has strong adaptability; in addition, the chitosan used in the present application is a natural polymer material, which is combined with a low-toxicity or non-toxic modifier and a controllable acrylamide system after polymerization, and has good overall environmental friendliness, which helps to reduce the risk of secondary pollution, and realizes selective enrichment of valuable mineral particles through targeted flocculation, which provides favorable conditions for subsequent resource recovery and comprehensive utilization.
[0040] Example 1: The present embodiment provides a phosphorus iron tailings targeted flocculant based on modified chitosan microspheres-polyacrylamide and a preparation method thereof, which comprises the following steps: S1: Preparation of magnetic chitosan microspheres: 2 g of chitosan powder was slowly added to 30 mL of 3% (by volume) ice acetic acid aqueous solution, and mechanical stirring was continued at room temperature for several hours until complete dissolution, with a stirring rate of 800 rpm and a temperature of 40℃, to obtain a clear and transparent viscous solution; meanwhile, 0.3 g of Fe3O4 nanoparticles was added to 30 mL of 2% (by mass) acetic acid solution, which was dispersed under ultrasonic assistance and then added to the above chitosan solution to obtain a magnetic chitosan solution; then the magnetic chitosan solution was slowly added to a system containing 100 mL of soybean oil and 2% Span-80 emulsifier in the oil phase, and a water-in-oil (W / O) emulsion was formed under mechanical stirring; the emulsion was then placed in a 60℃ water bath for stirring and reaction for 4 h, and after the reaction was completed, the microspheres were separated by centrifugation, washed with petroleum ether and anhydrous ethanol several times, and dried at 60℃ under vacuum for 24 h to obtain magnetic chitosan microspheres (i.e. Fe3O4NPs-CS microspheres); S2: Preparation of polymerization solution: acrylamide, acrylic acid, sodium hydroxide, urea, polyaluminum chloride and other raw materials were uniformly stirred in deionized water at a certain proportion until dissolved to prepare a polymerization solution for standby use; S3: Complexation and polymerization: 1.0 g of magnetic chitosan microspheres prepared in step S1 and dried were dispersed in 50 mL of deionized water, ultrasonically dispersed for 30 min, and then added to the polymerization solution of step S2, and the pH of the polymerization solution was adjusted to 7.2; then the system was cooled and nitrogen was passed for 20 min, and then cooled to -2℃, and a certain concentration of initiator was added for free radical polymerization reaction, and after the system reached the peak temperature, it was aged for a period of time; S4: Post-treatment: After the polymerization was completed, the product was granulated, and further dried, ground and sieved to obtain Fe3O4NPs-CS / PAM composite targeted flocculant; the drying condition was 90℃.
[0041] Example 2 The present embodiment provides a modified chitosan microsphere-polyacrylamide-based phosphorus iron tailings targeted flocculant and a preparation method thereof, which is similar to that of Example 1, except that: In step S1, the acidic aqueous solution is an aqueous solution of 2% glacial acetic acid, the dosage ratio of chitosan to the acidic aqueous solution is 1 g: 10 mL, the dissolving process is carried out at 35℃, and the mechanical stirring rate is 700 rpm; the magnetic nanoparticles are Fe3O4 nanoparticles, the mass ratio of the magnetic nanoparticles to chitosan is 1:5, and the magnetic nanoparticles are dispersed in 1% acetic acid solution in advance; the oil phase is soybean oil, the mass fraction of the emulsifier Span-80 in the oil phase is 1%, when the water-in-oil emulsion is formed, the volume ratio of the water phase to the oil phase is 1:2, and the emulsification stirring rate is 400 rpm; the crosslinking agent is a 1% sodium tripolyphosphate aqueous solution, the crosslinking and curing reaction is carried out at 50℃, the reaction time is 2 h, and vacuum drying is carried out at 50℃ after the reaction is completed; In step S3, the pH of the system is adjusted to 6.5 before polymerization, the nitrogen blowing time is 20 min, and the initial temperature of the polymerization reaction is 0℃; In step S4, the drying temperature is 85℃.
[0042] Example 3 This example provides a modified chitosan microsphere-polyacrylamide-based phosphorus iron tailings targeted flocculant and a preparation method thereof, which is similar to that of Example 1, except that: In step S1, the acidic aqueous solution is an aqueous solution of 4% glacial acetic acid, the dosage ratio of chitosan to the acidic aqueous solution is 1 g: 20 mL, the dissolving process is carried out at 45℃, and the mechanical stirring rate is 900 rpm; the magnetic nanoparticles are Fe3O4 nanoparticles, the mass ratio of the magnetic nanoparticles to chitosan is 1:10, and the magnetic nanoparticles are dispersed in 3% acetic acid solution in advance; the oil phase is soybean oil, the mass fraction of the emulsifier Span-80 in the oil phase is 3%, when the water-in-oil emulsion is formed, the volume ratio of the water phase to the oil phase is 1:4, and the emulsification stirring rate is 500 rpm; the crosslinking agent is a 5% sodium tripolyphosphate aqueous solution, the crosslinking and curing reaction is carried out at 70℃, the reaction time is 6 h, and vacuum drying or freeze-drying is carried out at 70℃ after the reaction is completed; In step S3, the pH of the system is adjusted to 7.5 before polymerization, the nitrogen blowing time is 40 min, and the initial temperature of the polymerization reaction is −5℃; In step S4, the drying temperature is 95℃.
[0043] Comparative Example 1 The comparative example provides a polyacrylamide flocculant for phosphorus iron tailings treatment, which only uses a polyacrylamide flocculant and does not introduce chitosan microspheres. The preparation method is similar to that of Example 1, except that: Step S1 in Example 1 is not performed, i.e., no magnetic chitosan microspheres are prepared; According to the method of step S2 in Example 1, acrylamide and related auxiliaries are dissolved in deionized water to prepare a polymerization solution; In step S3, only the conventional free radical polymerization reaction is performed on the polymerization solution, without introducing any microsphere carriers; After the polymerization is completed, granulation, drying, and crushing are performed according to step S4 to obtain a polyacrylamide flocculant.
[0044] The obtained polyacrylamide flocculant is used for phosphorus iron tailings slurry treatment, and the dosage, stirring method, and settling conditions are consistent with those of Example 1.
[0045] Comparative Example 3 The comparative example provides a tailings treatment material based on magnetic chitosan microspheres, which only prepares magnetic chitosan microspheres and does not prepare a polymerization solution or perform polymerization. The preparation method is similar to that of Example 1, except that: Only step S1 in Example 1 is performed to prepare magnetic chitosan microspheres; Step S2 is not performed, and no acrylamide or acrylic acid polymerization solution is prepared; Step S3 is not performed, and no free radical polymerization reaction is performed; The magnetic chitosan microspheres prepared in step S1 are dried and crushed, and then directly used as a flocculating material.
[0046] The obtained magnetic chitosan microspheres are directly added to phosphorus iron tailings slurry, and the dosage, stirring method, and settling conditions are consistent with those of Example 1.
[0047] Comparative Example 3 The comparative example provides a chitosan microsphere / polyacrylamide blended flocculant, which prepares chitosan microspheres but does not perform in-situ composite polymerization, only physical blending. The preparation method is similar to that of Example 1, except that: Magnetic chitosan microspheres are prepared according to step S1 of Example 1; According to steps S2 and S3 of Example 1, a free radical polymerization reaction of polyacrylamide is separately completed to prepare a polyacrylamide flocculant; The magnetic chitosan microspheres are not introduced into the polymerization system for in-situ compounding during the polymerization process, but are physically mixed with the polyacrylamide flocculant after the polymerization reaction is completed, at the same mass ratio as in Example 1; The obtained mixture is dried and pulverized to obtain the chitosan microsphere / polyacrylamide blended flocculant.
[0048] The blended flocculant is used for treating phosphorus iron tailings slurry, and the use method is consistent with that of Example 1.
[0049] The flocculants prepared in Example 1 and Comparative Examples 1-3 and common flocculants purchased on the market are subjected to flocculant performance characterization tests, and the specific test methods and results are shown in Tables 1-4 and Table 1-4. Figures 1-4 and Table 1-4: Table 1: Comparison results of settling velocity and 300 s supernatant turbidity of phosphorus iron tailings treated by different types of flocculants (I) Table 2: Comparison results of settling velocity and 300 s supernatant turbidity of phosphorus iron tailings treated by different types of flocculants (II) Table 3: Comparison results of settling velocity and 300 s supernatant turbidity of phosphorus iron tailings treated by Example 1 and Comparative Examples 1-3 (I) Table 4: Comparison results of settling velocity and 300 s supernatant turbidity of phosphorus iron tailings treated by Example 1 and Comparative Examples 1-3 (II) Through the above Example 1 and Comparative Examples 1-3, and in combination with Figures 1-4As can be seen from the test results of Tables 1-4, the Fe3O4 NPs-CS / PAM composite targeted flocculant prepared in the application can achieve a better comprehensive balance between the settling speed and the supernatant clarification effect in the treatment of phosphorus iron tailings slurry; in the application, the polyacrylamide relies on the stretching and adsorption bridging effect of the long polymer chain to make the destabilized fine particles rapidly aggregate and form flocs with larger volume and more compact structure, thereby significantly improving the particle agglomeration efficiency and the settling driving force; meanwhile, the further introduction of the magnetic chitosan microspheres rich in active functional groups such as amino and hydroxyl groups can produce stronger adsorption and selective combination capacity for the target components such as fine mineral particles, phosphorus-containing particles and heavy metal ions in the tailings through various interaction modes such as electrostatic interaction, coordination and hydrogen bonding, and improve the overall structural strength and shear stability of the flocs under the support of the microsphere skeleton; in addition, the Fe3O4 magnetic component contained in the microspheres endows the flocs with good magnetic response characteristics, making the formed flocs more likely to aggregate and speeding up the solid-liquid separation process, thereby effectively shortening the settling time, improving the underflow concentration and reducing the subsequent dewatering load. In contrast, Comparative Example 1 is composed of only polyacrylamide and lacks the targeted adsorption and structural support of chitosan microspheres, and the flocs are prone to loose and break; Comparative Example 3 only uses magnetic chitosan microspheres and lacks the high polymer bridging effect, and the particle growth capacity is insufficient, limiting the separation efficiency; and in the blending type system without in-situ compounding, the combination between the polymer chain and the microspheres is not firm, and the synergistic effect is difficult to fully play. As can be seen, the application organically combines the efficient bridging capacity of polyacrylamide, the targeted adsorption characteristics of magnetic chitosan microspheres and the magnetic response separation advantage, realizes more efficient and stable flocculation and solid-liquid separation effect of the phosphorus iron tailings slurry, and fully embodies the effectiveness and superiority of the technical scheme of the application.
[0050] In the description of the application, the description of the terms "one embodiment", "some embodiments", "in this embodiment", "specific examples" or "some examples" means that the specific features, mechanisms, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the application. In this specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in any suitable manner in any one or more embodiments or examples. In addition, the skilled in the art can combine and combine the different embodiments or examples described in the specification and the features of the different embodiments or examples without contradiction.
[0051] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of the changes or replacements within the technical range disclosed by the present application, which should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A method for preparing a targeted flocculant for phosphate-iron tailings based on modified chitosan microspheres-polyacrylamide, characterized in that, Includes the following steps: S1. Preparation of magnetic chitosan microspheres: Chitosan was dissolved in an acidic aqueous solution, magnetic nanoparticles were added and dispersed evenly to obtain a magnetic chitosan solution; the solution was mixed and emulsified with an oil phase containing an emulsifier to form a water-in-oil emulsion; a crosslinking agent was added to the emulsion for ionic crosslinking and curing; after the reaction was completed, the mixture was separated, washed and dried to obtain magnetic chitosan microspheres; S2. Preparation of polymerization solution: Dissolve acrylamide monomer in deionized water to prepare an acrylamide solution or a mixed monomer solution containing acrylic acid; S3. Composite and Polymerization: The magnetic chitosan microspheres obtained in step S1 are dispersed in the polymerization solution of step S2, the pH of the system is adjusted to near neutral, and an initiator is added under inert atmosphere and low temperature to carry out free radical polymerization reaction; S4. Post-processing: The product after polymerization reaction is granulated, dried and pulverized to obtain the targeted flocculant.
2. The preparation method according to claim 1, characterized in that, In step S1, the acidic aqueous solution is a glacial acetic acid aqueous solution with a volume fraction of 2%-4%; the ratio of chitosan to acidic aqueous solution is 1g:(10-20)ml; the dissolution is carried out under mechanical stirring at a stirring rate of 700-900 rpm and a temperature of 35-45℃.
3. The preparation method according to claim 1, characterized in that, In step S1, the magnetic nanoparticles are Fe3O4 nanoparticles, and the mass ratio of the magnetic nanoparticles to chitosan is 1:(5-10). The magnetic nanoparticles are pre-dispersed in an acetic acid solution with a concentration of 1%-3%, and then mixed with the chitosan solution.
4. The preparation method according to claim 1, characterized in that, In step S1, the oil phase is soybean oil; the emulsifier is Span-80, and its mass fraction in the oil phase is 1%-3%; when forming a water-in-oil emulsion, the volume ratio of the acidic aqueous solution containing magnetic chitosan to the oil phase is 1:(2-4), and the emulsification stirring rate is 400-500 rpm.
5. The preparation method according to claim 1, characterized in that, In step S1, the crosslinking agent is an aqueous solution of sodium tripolyphosphate with a mass-volume concentration of 1%-5%; the crosslinking and curing reaction is carried out at 50-70°C for 2-6 hours; after the reaction is completed, the microspheres are washed sequentially with petroleum ether, acetone, anhydrous ethanol and deionized water, and then vacuum dried or freeze-dried at 50-70°C to obtain the magnetic chitosan microspheres.
6. The preparation method according to claim 1, characterized in that, In step S3, the polymerization solution further includes one or more of urea, sodium sulfate, and polyaluminum chloride; the pH is adjusted to 6.5-7.5 before polymerization.
7. The preparation method according to claim 1, characterized in that, In step S3, the initiator of the polymerization reaction is a free radical initiator; nitrogen gas needs to be introduced for 20-40 minutes before the reaction to create an oxygen-free environment; the starting temperature of the polymerization reaction is -5℃ to 0℃.
8. The preparation method according to claim 1, characterized in that, In step S4, the drying temperature is 85-95℃.
9. A targeted flocculant, characterized in that, The targeted flocculant is prepared by the preparation method described in any one of claims 1-8.
10. The application of the targeted flocculant according to claim 9, characterized in that, The application includes using the flocculant in the treatment of phosphate-iron tailings slurry, comprising the following steps: (a) Analyze the particle size distribution and Zeta potential of the phosphate-iron tailings slurry; (b) Prepare the targeted flocculant into a solution with a mass concentration of 0.05%-0.3%; (c) The solution prepared in step (b) is added to the phosphate iron tailings slurry, and after mixing and settling, solid-liquid separation is achieved; In step (c), the flocculant solution is added in stages and mixed using a gradient stirring process.