A deep treatment process for collaborative resource recovery of phosphorus-fluorine wastewater to prepare fluorapatite

Abstract

The present invention provides a deep treatment process for synergistic resource recovery of phosphorus-fluorine wastewater to prepare fluorapatite, which comprises the following steps: adding a nano-titanium dioxide and hydroxyapatite composite material to the phosphorus-fluorine wastewater, and the dosage thereof is 0.3%-1.5% of the mass of the phosphorus-fluorine wastewater; simultaneously, according to the molar ratio of Ca / P / F in the phosphorus-fluorine wastewater being 8:4:1, adding a calcium source to the phosphorus-fluorine wastewater, and the added mass of the calcium source is 10%-15% in excess according to the calculation; then adding diatomite, and the dosage thereof is 1%-3% of the mass of the phosphorus-fluorine wastewater; after a synergistic crystallization reaction for a period of time, a fluorapatite product is obtained through precipitation, separation and purification. Using the surface-modified nano-titanium dioxide and hydroxyapatite composite material as crystal seeds and using diatomite as an auxiliary carrier to promote the crystallization reaction of fluoride ions, phosphate ions and calcium ions, improve the removal rates of phosphorus and fluorine in the phosphorus-fluorine wastewater, and simultaneously recover the fluorapatite product.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment and resource recovery and utilization, and particularly relates to a deep treatment process for co-recovering resources from phosphorus-fluorine wastewater to prepare fluorapatite. Background Art

[0002] In the current era of rapid industrial development, the generation and discharge of phosphorus-fluorine wastewater have become an environmental problem that urgently needs attention. More and more industries produce a large amount of phosphorus-fluorine wastewater: in the phosphorus chemical industry, a series of processes from the mining and beneficiation of phosphate rock to subsequent phosphoric acid production and phosphate manufacturing will generate a large amount of wastewater rich in phosphorus and fluorine. The aluminum electrolysis industry is also one of the important sources of phosphorus-fluorine wastewater. Bauxite often contains a certain amount of fluoride. During the production of electrolytic aluminum, fluoride will volatilize into the flue gas and, after being treated by the purification system, generate fluoride-containing wastewater. At the same time, some aluminum processing enterprises will also cause phosphorus elements to enter the wastewater system due to the use of phosphorus-containing additives or treatment agents in process links such as anodic oxidation and surface treatment, thus forming phosphorus-fluorine composite wastewater. In addition, in some electronic industries, during fine processing such as semiconductor manufacturing and circuit board etching, chemical reagents containing phosphorus and fluorine are used, and these reagents are discharged with wastewater after processes such as cleaning and etching. The phosphorus mainly comes from phosphate buffers, phosphating agents, etc., and the fluorine comes from etching agents such as hydrofluoric acid.

[0003] With the increasingly strict environmental protection requirements, the disorderly discharge of phosphorus-fluorine wastewater poses a serious threat to the ecological environment. High-concentration fluoride ions will harm the growth and reproduction of aquatic organisms, leading to the imbalance of the water ecosystem, and may also affect human health through food chain enrichment, such as causing diseases such as dental fluorosis and skeletal fluorosis. And the excessive discharge of phosphorus into the water body will cause eutrophication of the water body, resulting in a series of problems such as massive algal blooms, water quality deterioration, and reduction of dissolved oxygen, destroying the structure and function of the water ecosystem. At the same time, fluorine and phosphorus are important resources, so there is an urgent need for an innovative process that can not only deeply purify phosphorus-fluorine wastewater but also effectively recover phosphorus and fluorine resources. Summary of the Invention

[0004] The present invention provides a deep treatment process for co-recovering resources from phosphorus-fluorine wastewater to prepare fluorapatite, using a surface-modified nano-titanium dioxide and hydroxyapatite composite material as a seed crystal and diatomite as an auxiliary carrier to promote the crystallization reaction of fluoride ions, phosphate ions, and calcium ions, improve the removal rates of phosphorus and fluorine in phosphorus-fluorine wastewater, and at the same time recover the fluorapatite product.

[0005] To solve the above technical problems, the technical solution of the present invention is as follows:

[0006] A deep treatment process for co - resource recovery of phosphorus - fluorine wastewater to prepare fluorapatite, comprising the following steps: adding a nano - titanium dioxide and hydroxyapatite composite material to the phosphorus - fluorine wastewater, and the dosage is 0.3% - 1.5% of the mass of the phosphorus - fluorine wastewater; at the same time, according to the molar ratio of Ca / P / F in the phosphorus - fluorine wastewater of 8:4:1, adding a calcium source to the phosphorus - fluorine wastewater, and the added mass of the calcium source is 10% - 15% in excess according to the calculation; then adding diatomite, and the dosage is 1% - 3% of the mass of the phosphorus - fluorine wastewater; after a period of co - crystallization reaction, fluorapatite products are obtained through precipitation, separation, and purification.

[0007] Before the co - crystallization reaction, pretreatment is carried out on the phosphorus - fluorine wastewater, and the pretreatment includes the following steps:

[0008] (1.1) Water quality analysis: measuring the initial pH value, phosphorus concentration, fluorine concentration, and metal ion concentration of the phosphorus - fluorine wastewater;

[0009] (1.2) pH adjustment: adjusting the pH of the phosphorus - fluorine wastewater to 8.0 - 9.0;

[0010] (1.3) Wastewater activation: adding a chelating agent to the wastewater with the adjusted pH value, and the dosage of the chelating agent is added according to 1.2 - 1.5 times the total molar number of metal ions in the phosphorus - fluorine wastewater, and stirring and activation reaction is carried out.

[0011] The preparation method of the nano - titanium dioxide and hydroxyapatite composite material is as follows:

[0012] (2.1) Under mechanical stirring, a 0.5mol / L CaCl2 solution with pH adjusted to 2 - 4 by nitric acid is dropped into a 0.15mol / L KH2PO4 solution with pH adjusted to 2 - 4 by nitric acid as well. The mass ratio of Ca to P elements is Ca / P = 1.67. Then adding a surfactant Silwet408 and urea, heating to 70 - 80°C, continuously stirring for 24 - 48h, cooling, filtering, washing, and drying to obtain nano - hydroxyapatite powder;

[0013] (2.2) Slowly add 2 - 4mL of TiCl4 to 50mL of deionized water, hydrolyzing to form yellow metatitanic acid precipitate. Add 5 - 10mL of 65% hydrogen peroxide to the precipitate, ultrasonic treatment to form a pale yellow sol, add 1 - 2mL of isopropanol, and reflux at 60 - 80°C for 0.5 - 1h to obtain a stable TiO2 sol;

[0014] (2.3) Immerse the dried nano - hydroxyapatite powder in the TiO2 sol for 4 - 6h, filter and wash the solid sample, and calcine at 600°C for 0.5 - 1h to obtain the nano - titanium dioxide and hydroxyapatite composite material.

[0015] The surface of the nano-titanium dioxide and hydroxyapatite composite material is grafted with an organic molecule containing an amino active group; the specific steps for grafting the organic molecule containing an amino active group on the surface of the nano-titanium dioxide and hydroxyapatite composite material are as follows:

[0016] (3.1) Dissolve 20 - 30 g of amino silane in 70 mL of 95% ethanol, adjust the pH to 4 - 5, and carry out a hydrolysis reaction;

[0017] (3.2) Add the nano-titanium dioxide and hydroxyapatite composite material to the above solution according to a mass ratio of 1:(50 - 100) and react for 6 - 12 h;

[0018] (3.3) After the reaction, collect by centrifugation, wash with ethanol multiple times and then dry to obtain the nano-titanium dioxide and hydroxyapatite composite material with an organic molecule containing an amino active group grafted on its surface.

[0019] Before the nano-titanium dioxide and hydroxyapatite composite material is added, it needs to be pretreated. The pretreatment steps are as follows: Add the nano-titanium dioxide and hydroxyapatite composite material to deionized water according to a mass ratio of 1:(50 - 100), and perform ultrasonic dispersion treatment to make it uniformly dispersed in deionized water to form a stable suspension.

[0020] Before the diatomite is added, it needs to be pretreated. The pretreatment steps are as follows: Pickle the diatomite with a hydrochloric acid solution with a concentration of 0.5 - 1.5 mol / L for 2 - 4 hours. After pickling, rinse it repeatedly with deionized water until it is neutral, then dry it at 120 °C, and then crush it to 200 - 300 mesh for standby.

[0021] The porosity of the diatomite is not less than 60%, and the average pore diameter is between 10 - 50 nm.

[0022] The temperature of the co-crystallization reaction is 30 - 35 °C, the time is 1.5 - 2.5 h, and the stirring speed is 150 - 200 r / min.

[0023] The precipitation and separation treatment steps after the co-crystallization reaction are specifically as follows: Add a flocculant to the wastewater after the co-crystallization reaction for precipitation, and the dosing concentration of the flocculant is 5 - 15 mg / L; then use a plate and frame filter press for solid-liquid separation.

[0024] The purification treatment steps after the co-crystallization reaction are specifically as follows: First, pickle the separated filter cake, then wash it with water until it is neutral, and then perform preliminary screening through a vibrating screen to remove large particle impurities. The mesh number of the vibrating screen is 200 - 300 mesh; calcine the preliminarily screened filter cake at a high temperature of 800 - 1000 °C for 2 - 3 hours, and after cooling, fluorapatite is obtained.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the present invention, a surface-modified nano-titanium dioxide and hydroxyapatite composite material is used as a seed crystal. The active groups grafted on the surface of the nano-titanium dioxide and hydroxyapatite composite material will greatly increase its adsorption capacity for fluorine and phosphorus. At the same time, it can also increase the specific surface area of the material and increase the reactive sites. In addition, TiO2 has photocatalytic properties and can degrade organic pollutants in wastewater under the stimulation of ultraviolet light, reducing the interference of organic pollutants on fluorine and phosphorus. Hydroxyapatite can induce the directional deposition of phosphate and calcium ions on its surface. Utilizing the high specific surface area and unique surface activity of the nano-material, the crystallization reaction of fluoride ions, phosphate ions and calcium ions is promoted, making the crystallization reaction rate faster and the crystallization effect better. At the same time, diatomite is selected as an auxiliary carrier, and its rich pore structure can adsorb fine particles and impurities, making the crystallization process more orderly and further improving the crystallization effect.

[0026] (2) In the present invention, by adding a chelating agent to the wastewater, the chelating agent reacts fully with metal ions in the wastewater to form stable complexes, releasing more free phosphate and fluoride ions, improving the activity of phosphorus and fluorine, and promoting the subsequent crystallization reaction.

[0027] (3) In the present invention, the crystallization product is calcined at high temperature to further remove residual organic matters and impurities in the crystallization product, perfect the crystal structure of the fluorapatite crystal, and improve its purity and quality. Specific embodiments

[0028] The present invention will be further described below in conjunction with embodiments.

[0029] This embodiment provides a deep treatment process for the co-recovery of phosphorus and fluorine wastewater to prepare fluorapatite, including the following steps:

[0030] Step 1: Select a nano-titanium dioxide and hydroxyapatite composite material as a seed crystal. The preparation steps of this composite material are as follows:

[0031] (1.1) Under mechanical stirring, a 0.5 mol / L CaCl2 solution adjusted to pH 2-4 with nitric acid is dropped into a 0.15 mol / L KH2PO4 solution adjusted to pH 2-4 with nitric acid (Ca / P = 1.67). Then, a surfactant Silwet408 and urea are added, and the temperature is raised to 80 °C. Stir continuously for 48 hours. After the reaction solution is cooled and filtered, it is washed alternately with deionized water and ethanol 3 times, and vacuum dried at 90 °C for 12 hours to obtain nano-HA powder;

[0032] (1.2) Slowly add 2 mL of TiCl4 to 50 mL of deionized water, and hydrolyze to form yellow metatitanic acid precipitate. Add 5 mL of 65% hydrogen peroxide to the precipitate, and ultrasonically treat for 30 min (power 50 W) to form a pale yellow sol. Add 1 mL of isopropanol and reflux at 70 °C for 50 min to obtain a stable anatase TiO2 sol;

[0033] (1.3) Immerse the dried HA powder in the TiO2 sol for 4 - 6 h to ensure that the sol fully penetrates into the pores of HA. After filtration, wash with ethanol to remove unbound TiO2 particles. The sample is calcined in a muffle furnace at 600 °C for 40 min (heating rate 5 °C / min) to crystallize TiO2 into the anatase phase and form a stable bond with HA, obtaining a composite material of nano-titanium dioxide and hydroxyapatite. The particle size of this composite material is 50 - 100 nm, and its morphology is observed by scanning electron microscopy (SEM) to be uniformly dispersed granular.

[0034] In this example, the surface of the composite material of nano-titanium dioxide and hydroxyapatite is grafted with an organic molecule containing an amino active group to enhance its surface activity. The preparation steps for grafting an organic molecule containing an amino active group on the surface of the composite material of nano-titanium dioxide and hydroxyapatite in this example are as follows:

[0035] (2.1) Dissolve 20 g of amino silane in 70 mL of 95% ethanol, adjust the pH to 4 - 5, and carry out a hydrolysis reaction for 60 min;

[0036] (2.2) Add the composite material of nano-titanium dioxide and hydroxyapatite after ultrasonic cleaning with ethanol to the above solution according to a mass ratio of 1:(50 - 100) and react for 6 - 12 hours;

[0037] (2.3) After the reaction, collect by centrifugation, wash 3 times with ethanol, and dry at 60 °C to obtain the composite material of nano-titanium dioxide and hydroxyapatite with an organic molecule containing an amino active group grafted on its surface. The active groups grafted on the surface of the composite material of nano-titanium dioxide and hydroxyapatite will greatly increase its adsorption capacity for fluorine and phosphorus. At the same time, it can also increase the specific surface area of the material and increase the reactive active sites. The specific surface area of the surface-modified composite material in this example is 113 m 2 / g, and the number of surface active groups is 1.5 mmol / g; in addition, TiO2 has photocatalytic performance and can degrade organic pollutants in wastewater under the stimulation of ultraviolet light, reducing the interference of organic pollutants on fluorine and phosphorus. Hydroxyapatite can induce the directional deposition of phosphate and calcium ions on its surface.

[0038] The surface-modified nano-titanium dioxide and hydroxyapatite composite material is then pre-treated. The pre-treatment steps are as follows: The nano-titanium dioxide and hydroxyapatite composite material is added to deionized water at a mass ratio of 1:(50 - 100), and dispersed under ultrasonic conditions with a power of 200 - 300 W for 30 - 60 minutes to form a stable suspension uniformly dispersed in deionized water.

[0039] Step 2: Select diatomite with a rich pore structure as an auxiliary carrier. The porosity of the diatomite is not less than 60%, and the average pore diameter is between 10 - 50 nm. The diatomite is pre-treated. The pre-treatment steps are as follows: The diatomite is pickled with a hydrochloric acid solution with a concentration of 0.5 - 1.5 mol / L for 2 - 4 hours to remove the metal impurities therein. After pickling, it is repeatedly rinsed with deionized water until neutral, then dried at 120 °C, and then pulverized to 200 - 300 meshes by equipment such as a ball mill for standby. The rich pore structure of the diatomite can adsorb fine particles and impurities, making the crystallization process more orderly and further improving the crystallization effect.

[0040] The characterization data of the diatomite selected in this example are shown in the following table:

[0041]

[0042] Step 3: Pretreat the phosphorus-fluorine wastewater. The pretreatment includes the following steps:

[0043] (3.1) Water quality analysis: Use ion chromatography, spectrophotometry, etc. to accurately measure the initial pH value, phosphorus concentration, fluorine concentration, and the concentrations of other possible metal ions such as iron ions and aluminum ions in the phosphorus-fluorine wastewater;

[0044] In this example, the experimental phosphorus-fluorine wastewater comes from a phosphate fertilizer plant. The initial pH value of the phosphorus-fluorine wastewater from this plant is accurately measured by ion chromatography to be 6.5, the phosphorus concentration is 500 mg / L, the fluorine concentration is 150 mg / L, and the concentrations of other possible metal ions are measured by atomic absorption spectrometry. The iron ion concentration in the wastewater is measured to be 30 mg / L.

[0045] (3.2) pH adjustment: Use an alkaline calcium salt (such as calcium hydroxide), and drip it into the phosphorus-fluorine wastewater at a speed of 0.5 - 2 mL / min through a peristaltic pump to adjust the pH of the phosphorus-fluorine wastewater to 8.0 - 9.0; while adjusting the pH with the alkaline calcium salt, it can also provide calcium ions for the subsequent formation of fluorapatite products;

[0046] (3.3)Activation of wastewater: Add 0.1 mol / L ethylenediaminetetraacetic acid to the wastewater with adjusted pH value. The dosage of ethylenediaminetetraacetic acid is added according to 1.2 - 1.5 times the total molar number of metal ions in the phosphorus-fluorine wastewater, and carry out stirring activation reaction. The stirring speed is 100 - 150 r / min, and the reaction time is 30 - 60 minutes; Make the chelating agent fully react with the metal ions in the wastewater to form stable complexes, release more free phosphate and fluoride ions, improve the activity of phosphorus and fluorine, and promote the subsequent crystallization reaction.

[0047] Step 4: Add nano-titanium dioxide and hydroxyapatite composite material (after surface modification and pretreatment drying) to the phosphorus-fluorine wastewater, and its dosage is 0.3% - 1.5% of the mass of the phosphorus-fluorine wastewater; At the same time, according to the molar ratio of Ca / P / F in the phosphorus-fluorine wastewater of 8:4:1, add calcium source calcium chloride to the phosphorus-fluorine wastewater. The added mass of the calcium source is 10% - 15% in excess according to the calculation, that is, if the mass of the calcium source required to be added according to the molar ratio of Ca / P / F of 8:4:1 is m, then the actual added mass of the calcium source is 110%*m - 115%*m; Then add diatomite (after pretreatment), and its dosage is 1% - 3% of the mass of the phosphorus-fluorine wastewater; Carry out co-crystallization reaction for 1.5 - 2.5 h under the conditions of reaction temperature of 30 - 35 °C and stirring speed of 150 - 200 r / min.

[0048] Then add a flocculant (cationic polyacrylamide) to the wastewater after the co-crystallization reaction. The dosage concentration of the flocculant is 5 - 15 mg / L, stir quickly (200 - 300 r / min) for 1 - 3 minutes, and then stir slowly (50 - 100 r / min) for 10 - 20 minutes to make the fine crystal particles and suspended substances gather to form larger floc precipitates; Then carry out solid-liquid separation with a plate-and-frame filter press. The material of the filter cloth of the filter press is polypropylene, and the filtration accuracy is 1 - 5 μm. Control the pressure at 0.4 - 0.6 MPa, and monitor the pressure in real time through a pressure sensor for 20 - 30 minutes.

[0049] The filter cake obtained by solid-liquid separation is soaked in a dilute sulfuric acid solution (concentration: 0.2 - 0.4 mol / L) for 1.5 - 2.5 hours. During the soaking process, it is stirred every 30 minutes, and the stirring speed is 50 - 80 r / min. After soaking, filtration is carried out. Some impurities (such as incompletely reacted calcium salts, etc.) are dissolved through pickling, and the filter cake is rinsed with deionized water until neutral. The conductivity of the rinsing water is lower than 5 μS / cm. Then, it is preliminarily screened through a vibrating screen to remove large particle impurities. The mesh number of the vibrating screen is 200 - 300 meshes, the amplitude of the vibrating screen is 3 - 5 mm, and the frequency is 10 - 15 Hz. The preliminarily screened filter cake is put into a muffle furnace and heated to 800 - 1000 °C at a heating rate of 5 - 10 °C / min, and calcined at high temperature for 2 - 3 hours. High-temperature calcination can further remove organic impurities and make the crystal structure of crystalline substances such as fluorapatite more perfect. After calcination, it is cooled to room temperature with the furnace, and high-purity fluorapatite is obtained. The purity of the fluorapatite product is ≥95%, which can be recycled as high-quality chemical raw materials and used to produce chemical products such as phosphate fertilizers and fluorides.

[0050] In this example, the composition comparison of the phosphorus-fluorine wastewater before and after treatment is shown in the following table:

[0051]

[0052] As can be seen from the above table, after treating the phosphorus-fluorine wastewater through the advanced treatment process provided in this example, the removal rates of phosphorus and fluorine in the phosphorus-fluorine wastewater are relatively high.

[0053] In this example, the quality comparison of the crystalline product fluorapatite under different treatment conditions is shown in the following table:

[0054] 。

Claims

1. A deep treatment process for collaborative resource recovery of phosphorus-fluorine wastewater to prepare fluorapatite, characterized in that It includes the following steps: Add a nano-titanium dioxide and hydroxyapatite composite material to the phosphorus-fluorine wastewater, and the dosage is 0.3%-1.5% of the mass of the phosphorus-fluorine wastewater; at the same time, add a calcium source to the phosphorus-fluorine wastewater according to the molar ratio of Ca / P / F in the phosphorus-fluorine wastewater of 8:4:1, and the added mass of the calcium source is 10%-15% in excess according to the calculation; then add diatomite, and its dosage is 1%-3% of the mass of the phosphorus-fluorine wastewater; after the co-crystallization reaction for a period of time, fluorapatite products are obtained after precipitation, separation and purification; The preparation method of the nano-titanium dioxide and hydroxyapatite composite material is as follows: (2.1) Under mechanical stirring, slowly drip a 0.5 mol / L CaCl2 solution adjusted to pH 2-4 with nitric acid into a 0.15 mol / L KH2PO4 solution adjusted to pH 2-4 with nitric acid. The mass ratio of Ca and P elements is Ca / P = 1.

67. Then add a surfactant Silwet408 and urea, heat up to 70-80 °C, continuously stir for 24-48 h, cool, filter, wash and dry to obtain nano-hydroxyapatite powder; (2.2) Slowly add 2-4 mL of TiCl4 to 50 mL of deionized water to hydrolyze to form yellow metatitanic acid precipitate. Add 5-10 mL of 65% hydrogen peroxide to the precipitate, ultrasonically treat to form a light yellow sol, add 1-2 mL of isopropanol, and reflux at 60-80 °C for 0.5-1 h to obtain a stable TiO2 sol; (2.3) Immerse the dried nano-hydroxyapatite powder in the TiO2 sol for 4-6 h. The solid sample after filtration and washing is calcined at 600 °C for 0.5-1 h to obtain a nano-titanium dioxide and hydroxyapatite composite material; The surface of the nano-titanium dioxide and hydroxyapatite composite material is grafted with an organic molecule containing an amino active group; the specific steps for grafting an organic molecule containing an amino active group on the surface of the nano-titanium dioxide and hydroxyapatite composite material are as follows: (3.1) Dissolve 20-30 g of amino silane in 70 mL of 95% ethanol, adjust the pH to 4-5, and carry out a hydrolysis reaction; (3.2) Add the nano-titanium dioxide and hydroxyapatite composite material to the above solution according to a mass ratio of 1:(50-100) and react for 6-12 h; (3.3) After the reaction, centrifuge and collect, wash with ethanol multiple times and then dry to obtain a nano-titanium dioxide and hydroxyapatite composite material with an organic molecule containing an amino active group grafted on the surface.

2. The deep treatment process for collaborative resource recovery of phosphorus and fluorine wastewater to prepare fluorapatite, according to claim 1, is characterized in that: Before the co-crystallization reaction, pre-treat the phosphorus-fluorine wastewater. The pre-treatment includes the following steps: (1.1) Water quality analysis: Measure the initial pH value, phosphorus concentration, fluorine concentration and metal ion concentration of the phosphorus-fluorine wastewater; (1.2) pH adjustment: Adjust the pH of the phosphorus-fluorine wastewater to 8.0-9.0; (1.3) Wastewater activation: Add a chelating agent to the wastewater with the adjusted pH value. The dosage of the chelating agent is added according to 1.2-1.5 times the total molar number of metal ions in the phosphorus-fluorine wastewater, and carry out a stirring activation reaction.

3. The deep treatment process for co-recovering resources from phosphorus-fluorine wastewater to prepare fluorapatite according to claim 1, characterized in that: Before adding the nano-titanium dioxide and hydroxyapatite composite material, pretreatment is required. The pretreatment steps are as follows: Add the nano-titanium dioxide and hydroxyapatite composite material to deionized water at a mass ratio of 1:(50 - 100), and perform ultrasonic dispersion treatment to make it uniformly dispersed in deionized water to form a stable suspension.

4. The deep treatment process for co-recovering resources from phosphorus-fluorine wastewater to prepare fluorapatite according to claim 1, characterized in that: Before adding the diatomite, pretreatment is required. The pretreatment steps are as follows: Pickle the diatomite with a hydrochloric acid solution with a concentration of 0.5 - 1.5 mol / L for 2 - 4 hours. After pickling, repeatedly rinse it with deionized water until it is neutral, then dry it at 120 °C, and then crush it to 200 - 300 mesh for standby.

5. The deep treatment process for co-recovering resources from phosphorus-fluorine wastewater to prepare fluorapatite according to claim 1, characterized in that: The porosity of the diatomite is not less than 60%, and the average pore diameter is between 10 - 50 nm.

6. The deep treatment process for collaborative resource recovery of phosphorus-fluorine wastewater to prepare fluorapatite according to claim 1, characterized in that: The temperature of the co-crystallization reaction is 30 - 35 °C, the time is 1.5 - 2.5 h, and the stirring speed is 150 - 200 r / min.

7. The deep treatment process for collaborative resource recovery of phosphorus and fluorine wastewater to prepare fluorapatite according to claim 1, characterized in that: The specific steps for precipitation and separation after the co-crystallization reaction are as follows: Add a flocculant to the wastewater after the co-crystallization reaction for precipitation, and the dosing concentration of the flocculant is 5 - 15 mg / L; then use a plate and frame filter press for solid-liquid separation.

8. The deep treatment process for co-recovering resources from phosphorus-fluorine wastewater to prepare fluorapatite according to claim 1, characterized in that: The specific steps for purification treatment after the co-crystallization reaction are as follows: First, pickle the separated filter cake, then wash it with water until it is neutral, and then perform preliminary screening through a vibrating screen to remove large particle impurities. The mesh number of the vibrating screen is 200 - 300 mesh; Calcinate the preliminarily screened filter cake at a high temperature of 800 - 1000 °C for 2 - 3 hours, and fluorapatite is obtained after cooling.

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