Preparation method and application of magnetic phosphate tailing composite material

Abstract

The invention discloses a preparation method and application of a magnetic phosphate tailing composite material, and belongs to the technical field of water treatment.The preparation method comprises the following steps that phosphate tailing powder and a mixed salt solution of ferric iron salt and ferrous iron salt are mixed, stirred and heated to 70-90 DEG C; adding an alkaline substance into the obtained mixed slurry, adjusting the pH value to 10-12, and continuing stirring for reaction; and carrying out solid-liquid separation, washing the obtained precipitate to be neutral, and drying to obtain the product. The composite material prepared by the invention has a very good removal effect on phosphorus and fluorine in wastewater, can be rapidly separated under the action of an external magnetic field, and can be repeatedly used. According to the scheme, the phosphate tailings are used as main materials, the purpose of treating waste with waste is achieved, and the method has economic feasibility and environmental friendliness in practical application.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of water treatment, in particular to a preparation method of a magnetic phosphorus tailing composite material and application thereof in removal of water pollutants (especially phosphorus and fluorine). BACKGROUND

[0002] The pollution problem caused by excessive phosphorus and fluorine in water bodies is increasingly serious. Excessive phosphate ions (PO4 3- ) and fluorine ions (F - ) not only lead to algae outbreak and water hypoxia, but also cause deformation of aquatic organism skeletons and affect human tooth and bone health, seriously damaging the water ecological balance and threatening drinking water safety. In the traditional treatment method, a large amount of chemicals are consumed in the chemical precipitation method for treating phosphorus and fluorine, and secondary pollution is easily caused. The biological method is difficult to simultaneously meet the requirements of phosphorus and fluorine removal, and is limited by environmental conditions and has unstable efficiency. Therefore, it is urgent to develop a low-cost, efficient and sustainable phosphorus and fluorine removal material. Phosphorus tailings, as the main solid waste of the phosphorus chemical industry, have an annual production of hundreds of millions of tons. The main components of the phosphorus tailings are calcium phosphate, quartz and iron and aluminum oxides, and the phosphorus tailings are rich in active sites such as calcium, iron and aluminum, which have natural advantages in adsorbing phosphorus and fluorine. Calcium can combine with phosphate ions and fluorine ions to form insoluble salts through chemical precipitation, and iron and aluminum oxides can capture ions through surface complexation. However, the adsorption capacity of natural phosphorus tailings is limited and difficult to separate and recover. Through modification of the phosphorus tailings, good adsorption of anions, cations and organic matters in water can be achieved. For example, patent application CN 120054410 A discloses a magnetic iron mineral-phosphorus tailing material, which has good removal capacity for arsenic and cadmium pollutants in water bodies or soil. However, the technical solution needs to perform high-temperature thermal activation treatment on the phosphorus tailings, and the obtained composite material is not suitable for removal of phosphate ions and fluorine ions. SUMMARY

[0003] Therefore, the present application prepares a magnetic phosphorus tailing composite material through magnetic modification to selectively greatly improve the adsorption rate and adsorption capacity of phosphate ions and fluorine ions in water, and the obtained composite material is convenient for rapid separation by using a magnetic field, thereby significantly improving the use effect.

[0004] The technical solution of the present application is as follows: In a first aspect, the present application provides a preparation method of a magnetic phosphorus tailing composite material, which comprises the following steps: S1, mixing phosphorus tailing powder with an iron salt solution, stirring and heating to 70-90℃; wherein the iron salt solution is a mixed salt solution of trivalent iron salt and divalent iron salt; S2, adding an alkaline substance to the mixed slurry obtained in step S1, adjusting the pH value to 10-12 and continuing to stir and react; S3, solid-liquid separation to obtain the precipitate, washing the precipitate to neutral, drying to obtain the magnetic phosphorus tailing composite material.

[0005] In the present application, the phosphorus tailing powder refers to the fine phosphorus tailing powder obtained by crushing, screening and grinding treatment of the phosphorus tailing, wherein the phosphorus tailing is the solid waste generated by phosphorus flotation.

[0006] Preferably, the mass ratio of the phosphorus tailing powder to the divalent iron salt and the trivalent iron salt is 1:(1.5~2.3):(1.2~2.0), wherein the divalent iron salt is at least one of FeSO4, FeCl2 and Fe(NO3)2, and the trivalent iron salt is at least one of FeCl3, Fe(NO)3 and Fe2(SO4)3.

[0007] Preferably, the alkaline substance is a 2~5 mol / L NaOH solution.

[0008] Preferably, the stirring speed is 300~600 rpm.

[0009] Preferably, the reaction time in step S2 is 10~30 min.

[0010] Preferably, the drying in step S3 is drying at 70~90℃ in a vacuum drying device.

[0011] Preferably, the precipitate is obtained by external magnetic field separation in step S3.

[0012] In the second aspect, the present application provides a magnetic phosphorus tailing composite material obtained by the preparation method provided by the present application.

[0013] In the third aspect, the present application provides the application of the above-mentioned magnetic phosphorus tailing composite material in removing water pollutants, wherein the pollutants include phosphorus and fluorine. Experimental data show that the modification scheme of the present application for the phosphorus tailing has significantly improved the removal capacity of the obtained composite material for phosphate ions and fluoride ions in water.

[0014] Compared with the prior art, the present application has the following beneficial effects: In the present application, the phosphorus tailing is used as a carrier, and is reacted with a mixed salt solution of trivalent iron salt and divalent iron salt, which on the one hand endows the material with the unique performance of realizing rapid separation under the action of an external magnetic field and repeated use, solves the problem of difficult recovery after use of traditional adsorbent materials, and makes it more economically feasible and environmentally friendly in practical application; on the other hand, it solves the problem of limited phosphorus and fluorine removal capacity due to the low number of active functional groups on the surface of the phosphorus tailing, and constructs a large number of active sites on the surface of the phosphorus tailing and a multi-level pore structure inside, thereby significantly improving the adsorption rate and adsorption capacity for phosphate and fluoride ions in water.

[0015] The application uses industrial waste phosphorite tailings as raw materials, effectively realizes the resource utilization of waste, reduces the raw material cost, meets the requirements of environmental sustainable development, and reduces the pollution of industrial waste to the environment. BRIEF DESCRIPTION OF DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the present application, the drawings used in the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0017] Figure 1 The preparation process flow chart of the magnetic phosphorite tailings composite material in the present application is shown in the figure. Figure 2 The XRD graph of the magnetic phosphorite tailings composite material prepared in the embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0018] The technical solutions of the present application will be further described below in combination with the drawings and specific embodiments.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The terms "include" and "have" and any variations thereof in the present document are intended to cover non-exclusive inclusion.

[0020] In view of the technical problems that the phosphorite tailings powder is difficult to recover and has limited adsorption capacity for phosphorus and fluorine when used as an adsorbent, the present application provides a magnetic phosphorite tailings composite material and a preparation method thereof. The obtained composite material can be recovered by a magnetic field and greatly improves the adsorption capacity for phosphate and fluoride ions in water by using a mixed salt solution of ferric iron salt and divalent iron salt to modify the phosphorite tailings powder.

[0021] Reference Figure 1 The embodiment of the present application provides a preparation method of a magnetic phosphorite tailings composite material, which comprises the following steps: The divalent iron salt, the trivalent iron salt and distilled water are mixed and fully dissolved to obtain an iron salt solution; The phosphorite tailings (i.e. solid waste produced by phosphorite flotation) are crushed, sieved and ground to process the phosphorite tailings into phosphorite tailings powder with a particle size of ≤0.15 mm; The phosphorus tailing powder is added into the iron salt solution, stirring and synchronous heating, and then NaOH solution is added into the obtained mixed slurry, and the pH is adjusted to 10-12 to carry out the coprecipitation reaction; The reaction liquid is subjected to solid-liquid separation by using an applied magnetic field, and the precipitate obtained by the separation is washed several times by using distilled water until the pH of the washing liquid is slightly neutral (i.e., the pH is about 7), and then the precipitate after washing is dried to obtain the magnetic phosphorus tailing composite material.

[0022] Further, the divalent iron salt is at least one of FeSO4, FeCl2 and Fe(NO3)2, the trivalent iron salt is at least one of FeCl3, Fe(NO)3 and Fe2(SO4)3, and the mass ratio of the phosphorus tailing powder to the divalent iron salt and the trivalent iron salt is 1:(1.5-2.3):(1.2-2.0).

[0023] Further, in the coprecipitation reaction, the reaction temperature is 70-90℃, the stirring speed is 300-600 rpm, and the reaction time is 10-30 min.

[0024] Reference Figure 2 In the magnetic phosphorus tailing composite material prepared by the method of the application, the following peaks of the following substances are present: Fe3O4 (magnetite): The strong peaks at 2θ ≈ 30.1°, 35.5°, 43.1°, 57.0° and 62.6° in the spectrum are highly consistent with the standard card (JCPDS No. 19-0629) of cubic Fe3O4, indicating that the magnetite is the main iron-containing phase in the sample, and the sharp diffraction peaks indicate good crystallinity; Dolomite (CaMg(CO3)2): The diffraction peaks at 2θ ≈ 31.0°, 37.4°, 41.2° and 50.7° correspond to the standard card (JCPDS No. 36-0426) of dolomite, confirming the presence of calcium magnesium carbonate mineral, and the narrow peak shape indicates complete crystallization; Fluorapatite (Ca5(PO4)3F): The characteristic peaks at 2θ ≈ 31.8°, 32.9° and 34.1° match the standard card (JCPDS No. 15-0876) of hexagonal fluorapatite, and the dolomite and fluorapatite are the main components of the phosphorus tailing, and the XRD analysis shows that the magnetite is successfully loaded on the phosphorus tailing.

[0025] The magnetic phosphorus tailing composite material prepared by the application has a removal rate of phosphorus and fluorine of more than 95% and more than 76% respectively in a short time when used as an adsorbent for wastewater treatment, which has important significance for treating wastewater with excessive phosphorus and fluorine.

[0026] Some specific examples are listed below. It should be noted that the examples described below are exemplary and are used to explain the present application, and cannot be understood as a limitation of the present application. If a specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product manual. If the manufacturer of the reagent or instrument is not specified, it is a conventional product that can be obtained on the market.

[0027] Example 1 This example provides a magnetic phosphorus tailings composite material, and the preparation method thereof comprises the following steps: The phosphorus tailings produced by phosphorus ore flotation are prepared into phosphorus tailings powder with a particle size of less than or equal to 0.15 mm through crushing, screening, grading and grinding treatment in sequence.

[0028] Iron sulfate and ferrous sulfate heptahydrate are added to distilled water, and stirred at a speed of 300 revolutions per minute for 20 minutes to fully dissolve the iron salt, thereby obtaining an iron salt solution.

[0029] The iron salt solution is added to the phosphorus tailings powder, and stirred (300 revolutions per minute) to make the phosphorus tailings fully dispersed in the solution, while heating starts and heats to 80°C; wherein the mass ratio of phosphorus tailings: iron sulfate: ferrous sulfate heptahydrate is 1:1.6:2.2.

[0030] The obtained mixed slurry is placed in a water bath for heat preservation and continuous stirring, and 3 mol / L NaOH solution is added to the mixed slurry to adjust the pH of the solution to 11; continue heating and stirring for 30 minutes to enable the magnetic particle precursor to penetrate into the pores inside the phosphorus tailings matrix and adhere to the surface thereof.

[0031] After the reaction is completed, the magnetic phosphorus tailings composite material is separated from the solution by using an external magnetic field, and then washed repeatedly with deionized water until neutral. The precipitate is dried in a vacuum drying oven at a temperature of 80°C for 20 hours, thereby obtaining the magnetic phosphorus tailings composite material.

[0032] Example 2 This example provides a magnetic phosphorus tailings composite material, and the preparation method thereof comprises the following steps: The phosphorus tailings produced by phosphorus ore flotation are prepared into phosphorus tailings powder with a particle size of less than or equal to 0.15 mm through crushing, screening, grading and grinding treatment in sequence.

[0033] Iron sulfate and ferrous sulfate heptahydrate are added to distilled water, and stirred at a speed of 300 revolutions per minute for 20 minutes to fully dissolve the iron salt, thereby obtaining an iron salt solution.

[0034] The iron salt solution is added to the phosphorus tailings powder, and the phosphorus tailings are fully dispersed in the solution by stirring (300 rpm), while heating is started and heated to 90°C; wherein the mass ratio of phosphorus tailings: ferric sulfate: ferrous sulfate heptahydrate is 1:1.8:2.

[0035] The obtained mixed slurry is placed in a water bath for heat preservation and continuous stirring, and 3 mol / L NaOH solution is added to the mixed slurry to adjust the pH of the solution to 11; continue to heat and stir for 30 minutes, so that the magnetic particle precursor can penetrate into the pores inside the phosphorus tailings matrix and adhere to its surface.

[0036] After the reaction is completed, the magnetic phosphorus tailings composite is separated from the solution by using an external magnetic field, and then washed repeatedly with deionized water until neutral. The precipitate is dried in a vacuum drying oven at a temperature of 80°C for 20 hours to obtain the magnetic phosphorus tailings composite.

[0037] Example 3 The example provides a magnetic phosphorus tailings composite, and a preparation method thereof includes the following steps: The phosphorus tailings produced by phosphorus ore flotation are prepared into phosphorus tailings powder with a particle size of less than or equal to 0.15 mm by crushing, screening, grading and grinding treatment in sequence.

[0038] Ferric sulfate and ferrous sulfate heptahydrate are added to distilled water, and the iron salt is fully dissolved by stirring at a speed of 300 rpm for 20 minutes to obtain an iron salt solution.

[0039] The iron salt solution is added to the phosphorus tailings powder, and the phosphorus tailings are fully dispersed in the solution by stirring (300 rpm), while heating is started and heated to 90°C; wherein the mass ratio of phosphorus tailings: ferric sulfate: ferrous sulfate heptahydrate is 1:2:2.

[0040] The obtained mixed slurry is placed in a water bath for heat preservation and continuous stirring, and 3 mol / L NaOH solution is added to the mixed slurry to adjust the pH of the solution to 11; continue to heat and stir for 30 minutes, so that the magnetic particle precursor can penetrate into the pores inside the phosphorus tailings matrix and adhere to its surface.

[0041] After the reaction is completed, the magnetic phosphorus tailings composite is separated from the solution by using an external magnetic field, and then washed repeatedly with deionized water until neutral. The precipitate is dried in a vacuum drying oven at a temperature of 80°C for 20 hours to obtain the magnetic phosphorus tailings composite.

[0042] Comparative Example 1 The example provides a phosphorus tailing composite material, different from example 1, in the preparation method thereof, a ferric salt (FeCl3) is used to replace the mixed ferric salt solution, and the mass ratio of the phosphorus tailing powder to the FeCl3 is controlled to be 1:2.0 (the total iron addition amount is consistent with example 1).

[0043] It is found in the experiment process that the reaction product cannot be effectively separated by an external magnetic field, and finally the solid-liquid separation is completed by filtering operation. It is shown that the reaction does not synthesize ferroferric oxide because of the lack of a divalent iron salt.

[0044] Comparative example 2 The example provides a magnetic phosphorus tailing composite material, different from example 1, in the preparation method thereof, the mass ratio of the phosphorus tailing: ferric sulfate: ferrous sulfate heptahydrate is 1:3:3.5, and the others are consistent with example 1.

[0045] The phosphorus and fluorine removal capacities of the composite materials obtained in each example and comparative example are detected by taking the phosphorus tailing powder as a control. The detection method is as follows: a water solution containing 50 mg / L and 20 mg / L of phosphate ions and fluorine ions respectively is prepared, the adsorbent addition amount is 4 g / L, then the pH value of the solution is adjusted to 7, and the solution is stirred and adsorbed for 2 hours at room temperature; after the adsorption is completed, the adsorbent is separated by an external magnetic field (the materials in the phosphorus tailing powder and comparative example 1 are filtered), and then the concentrations of the phosphate ions and the fluorine ions in the solution are detected. The detection results are as follows:

[0046] The above results show that the adsorption rate and the adsorption capacity of the composite material prepared by the example scheme to the phosphate and fluorine ions in water are greatly improved, and the scheme endows the composite material with the unique performance of realizing rapid separation under the action of an external magnetic field and repeated use, and solves the problem of difficult recovery after the use of traditional adsorption materials. The removal rates of the composite material prepared in comparative example 1 to the phosphorus-containing and fluorine-containing wastewater are only 68.3% and 54.1% respectively, which proves that the lack of a divalent iron salt not only leads to the loss of the magnetism of the material, but also almost does not improve the adsorption performance. The adsorption effect of the composite material prepared in comparative example 2 is reduced, and the phosphorus and fluorine removal rates are reduced to 72.5% and 58.6% respectively, which is significantly lower than the data of examples 1-3 (>95.2%, >76.3%), which shows that the imbalance of the iron salt ratio will cause the material structure to deteriorate and the function to attenuate; the reason is that too much iron salt is added to make the solution strongly acidic, and the calcium and magnesium carbonates are seriously lost due to the violent reaction of the phosphorus tailing with hydrogen ions.

[0047] Note that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration as the technical idea and achieving the same effects within the scope of the technical idea of the present application are included in the technical scope of the present application. Furthermore, other modes constructed by applying various modifications that can be thought of by those skilled in the art to the embodiments or by combining part of the constituent elements of the embodiments are also included in the scope of the present application without departing from the spirit of the present application.

Claims

1. A method for preparing a magnetic phosphorus tailings composite material, characterized in that, Includes the following steps: S1. Mix the phosphorus tailings powder with the iron salt solution, stir and heat to 70~90℃; wherein, the iron salt solution is a mixed salt solution of ferric salt and ferrous salt; S2. Add an alkaline substance to the mixed slurry obtained in step S1, adjust the pH value to 10-12, and continue stirring to react. S3. Solid-liquid separation yields a precipitate, which is then washed until neutral and dried to obtain a magnetic phosphorus tailings composite material.

2. The preparation method according to claim 1, characterized in that, The particle size of the phosphorus tailings powder is ≤0.15 mm.

3. The preparation method according to claim 1, characterized in that, The mass ratio of the phosphorus tailings powder to divalent iron salts and trivalent iron salts is 1:(1.5~2.3):(1.2~2.0), wherein the divalent iron salt is at least one of FeSO4, FeCl2, and Fe(NO3)2, and the trivalent iron salt is at least one of FeCl3, Fe(NO)3, and Fe2(SO4)3.

4. The preparation method according to claim 1, characterized in that, The alkaline substance is a 2-5 mol / L NaOH solution.

5. The preparation method according to claim 1, characterized in that, The stirring speed is 300~600 rpm.

6. The preparation method according to claim 1, characterized in that, The reaction time in step S2 is 10-30 min.

7. The preparation method according to claim 1, characterized in that, The drying process involves drying at 70-90°C in a vacuum drying apparatus.

8. The preparation method according to claim 1, characterized in that, In step S3, the precipitate is separated and obtained by applying an external magnetic field.

9. The magnetic phosphorus tailings composite material obtained by the preparation method according to any one of claims 1-8.

10. The application of the magnetic phosphorus tailings composite material as described in claim 9 in the removal of pollutants from water bodies, wherein the pollutants include phosphorus and fluorine.

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