A method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste

Abstract

This invention discloses a method for preparing phosphate concentrate from phosphorus-rich wastewater in synergistic treatment with phosphorus-based solid waste, relating to the field of comprehensive utilization of phosphorus-based solid waste resources. The preparation method includes the following steps: (1) thoroughly mixing phosphorus tailings and phosphogypsum and then calcining to obtain a porous phosphorus-based solid waste mixture; (2) grinding and mixing the phosphorus-based solid waste mixture with quicklime to obtain a solid-phase phosphorus carrier; (3) preparing an emulsion with water using the solid-phase phosphorus carrier; (4) adding the emulsion to phosphorus-rich wastewater, stirring and reacting thoroughly, filtering to separate the precipitate after the reaction is complete, and then drying to obtain phosphate concentrate with a P2O5 content of 28%–31%. The advantage of this invention is that it achieves the synergistic treatment of phosphorus-based solid waste and phosphorus-rich wastewater, achieving the goal of efficient recycling of phosphorus resources. It solves the problems of solid waste stockpiling pollution and excessive total phosphorus in wastewater, and has both environmental and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of comprehensive utilization technology of phosphorus-based solid waste resources, specifically to a method for preparing phosphate concentrate based on phosphorus-rich wastewater and phosphorus-based solid waste through phosphorus phase reconstruction. Background Technology

[0002] Phosphate tailings, a typical solid waste generated during phosphate ore beneficiation, are increasingly facing a contradiction between their resource endowment characteristics and bottlenecks in comprehensive utilization. Mineral composition analysis shows that dolomite (CaMg(CO3)2) accounts for 60%-80% of phosphate tailings, while also containing residual phosphorus (P2O5 content 2%-5%) and trace metal elements. This mineral structure, primarily composed of calcium and magnesium carbonates, can be directionally transformed into highly reactive calcium oxide (CaO) and magnesium oxide (MgO) after high-temperature calcination, significantly increasing its specific surface area (up to 15m²). 2 ·g -1 -35m 2 ·g -1 It forms a porous structure, which is a source of phosphate (PO4). 3- The adsorption and chemical precipitation provide an ideal reaction interface. However, the current mainstream underground filling and stockpiling disposal mode not only causes millions of tons of calcium and magnesium resources to be idle and solidified every year, but also leads to the continuous loss of residual phosphorus in tailings (annual loss of more than 100,000 tons), forming a contradictory situation of "solid waste accumulation" and "phosphorus resource shortage".

[0003] Existing technologies for utilizing phosphate tailings have significant limitations: First, traditional backfilling processes only achieve physical transformation without releasing the chemical activity of calcium and magnesium components, resulting in a resource utilization rate of less than 30%; second, wet storage leads to leachate pollution (total phosphorus leaching concentration reaches 8 mg / L). -1 -20mg·L -1 This requires additional investment in solidifying agents and seepage prevention projects, resulting in treatment costs as high as 90-150 yuan / ton; thirdly, residual phosphorus in tailings is not effectively recovered, leading to a vicious cycle of "sorting-loss" in the phosphorus chemical industry chain. Meanwhile, industrial phosphorus-rich wastewater (total phosphorus concentration 400mg / L-2000mg·L) -1 Traditional treatment methods for sludge generally suffer from technical drawbacks such as high chemical costs (e.g., the cost of treating one ton of water is 15-18 yuan for calcium / aluminum / iron salt methods) and large sludge production (sludge production rate of 15%-30% for chemical precipitation methods).

[0004] Against this backdrop, there is an urgent need to develop a method for preparing phosphate concentrate from phosphorus-rich wastewater in synergy with phosphorus-based solid waste. This method aims to achieve a shift from "end-of-pipe treatment" to "resource recycling" through technological innovation, providing key technological support for the green transformation of the phosphorus chemical industry. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the aforementioned background technology by providing a method for preparing phosphate concentrate based on phosphorus phase reconstruction of phosphorus-rich wastewater and synergistic phosphorus-based solid waste, using phosphorus tailings as the main raw material, phosphogypsum as the crystallizing agent, and phosphorus-rich wastewater as the phosphorus source.

[0006] The technical solution of this invention is: a method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste, comprising the following steps:

[0007] (1) After thoroughly mixing phosphorus tailings and phosphogypsum at a mass ratio of 100:(3-8), calcination is carried out to obtain porous phosphorus-based solid waste mixture;

[0008] (2) Grind and mix the phosphorus-based solid waste mixture obtained in step (1) with quicklime at a mass ratio of 2:(1~2) to obtain a solid phosphorus carrier;

[0009] (3) Prepare an emulsion by mixing the solid phosphorus carrier obtained in step (2) with water;

[0010] (4) Add the emulsion obtained in step (3) to a total phosphorus concentration of 600 mg·L⁻¹ -1 ~2000mg·L -1 In phosphorus-rich wastewater, the mixture is stirred and reacted thoroughly. After the reaction is complete, the precipitate is filtered out and dried to obtain phosphate concentrate.

[0011] Preferably, in step (1), the calcination includes: at 5-10°C / min -1 Preheat at a rate of 400–450°C for 30–60 min, then increase the temperature by 5–10°C / min. -1 The temperature is rapidly increased to 880–1050°C and held constant for 60–120 minutes. After cooling in the furnace to below 200°C, the product is removed and cooled to room temperature.

[0012] Preferably, in step (1), the CaO+MgO content in the phosphorus tailings is 48% to 68%, and the P2O5 content is ≤5%; the CaSO4·2H2O content in the phosphogypsum is 80% to 94%, and the SiO2 content is ≤10%.

[0013] Preferably, in step (2), the phosphorus-based solid waste mixture is ground and mixed with quicklime to a mesh size of less than 400.

[0014] Preferably, in step (3), the solid phosphorus carrier is mixed with water at a mass ratio of 1:1 to prepare an emulsion.

[0015] Preferably, in step (4), the volume ratio of the emulsion to the phosphorus-rich wastewater is 1:(140-600). Further, the volume ratio of the emulsion to the phosphorus-rich wastewater is 1:(140-300).

[0016] Preferably, in step (4), the reaction is thoroughly stirred for 2–4 hours.

[0017] Preferably, in step (4), the total phosphorus concentration of the filtrate obtained by filtration is ≤80 mg·L⁻¹. -1 The obtained phosphate concentrate has a P2O5 content of ≥28%.

[0018] Preferably, the obtained phosphate concentrate has a P2O5 content of 28% to 31%.

[0019] The present invention also provides a phosphate concentrate, which is prepared by any of the above methods for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste.

[0020] In the above preparation methods:

[0021] (1) In this invention, phosphorus tailings are the key raw material for phosphorus phase reconstruction. Thermodynamic analysis shows that the main mineral component of phosphorus tailings is dolomite. Dolomite undergoes staged decomposition during calcination at 400℃-950℃: in the first stage, MgCO3 decomposes to generate active MgO (400℃-600℃), and in the second stage, CaCO3 decomposes to generate porous CaO (700℃-900℃). The nanoscale metal oxides formed during the thermal decomposition of dolomite have strong Lewis basicity and can undergo chemical coordination reactions with phosphate ions, with a theoretical adsorption capacity of 120mg / g-180mg / g. During the implementation of the technology, the calcined tailings powder (particle size D) is... 90 <45μm) added to the phosphorus-rich wastewater system, CaO / MgO and (PO4) 3- The reaction produces stable compounds such as hydroxyapatite Ca5(PO4)3(OH) and struvite (MgNH4PO4), achieving efficient conversion of liquid-phase phosphorus to solid-phase phosphorus (conversion rate ≥95%), ultimately converting phosphorus tailings into regenerated phosphorus concentrate with a P2O5 content ≥28%.

[0022] (2) In this invention, phosphogypsum is an important crystallizing agent in the calcination process of phosphate tailings, and SO4 in CaSO4 2- The theory of inhibiting CaO and MgO grain growth is mainly based on the mineralizing effect of sulfates at high temperatures and the grain growth kinetic mechanism. ① Mineralizing effect: Calcium sulfate at high temperatures reacts with SO42-... 2- Ions adsorb onto the surface or grain boundaries of CaO and MgO grains, hindering diffusion and migration between grains, thereby suppressing excessive grain growth, maintaining small grains and high specific surface area, and enhancing reactivity. ② Lattice defects and specific surface area: SO4 2- Ingress into the oxide lattice can cause lattice distortion, forming oxygen or cation vacancies, increasing defect density, and raising surface energy. Simultaneously, reduced grain size significantly increases specific surface area, enhancing reactivity.

[0023] The present invention has the following beneficial effects:

[0024] (1) Fully activate the functionality of calcium and magnesium elements in phosphate tailings. Calcium carbonate and magnesium carbonate, abundant in phosphate tailings, often exist in a chemically inert form, and the extraction efficiency of traditional physical separation methods is less than 15%. Through a gradient calcination process at 880℃-1050℃, the carbonates are decomposed into highly active calcium oxide and magnesium oxide (specific surface area > 25m²). 2 The surface hydroxyl site density is increased by 3-5 times, and the chemical adsorption capacity for phosphate is 2-3 times that of the traditional lime method. This increases the utilization rate of phosphate tailings from less than 20% to over 95%, and reduces energy consumption per ton of phosphate tailings by 35% compared to conventional calcination processes.

[0025] (2) Construct a new model for the coordinated treatment of waste and pollution to achieve pollution transformation and value-added processing. This model targets the annual production of over 30 million tons of phosphate tailings and 1 billion cubic meters of phosphorus-rich wastewater (total phosphorus 400 mg·L⁻¹) from the phosphate chemical industry. -1 -2000mg·L -1 This study addresses the challenge of treating wastewater from calcined phosphorus-based solid waste, proposing a novel coupled mechanism of "wastewater treatment from waste minerals." The calcined phosphorus-based solid waste achieves a 98% adsorption rate for total phosphorus in the wastewater, resulting in a stable effluent TP concentration of ≤80 mg / L. Simultaneously, the solid phase after saturation adsorption is enriched with 28%-31% P2O5, meeting the quality standards for phosphate concentrate. Compared to traditional chemical precipitation methods, this reduces sludge production by 90%, and compared to ion exchange methods, it lowers operating costs by 55%.

[0026] (3) Establish a closed-loop phosphorus recycling system to promote the green transformation of the industry. Through the process design of "tailings activation - wastewater purification - concentrate regeneration", the phosphorus recovery rate within the system exceeds 85%. The phosphorus concentrate generated by phosphorus-rich wastewater and phosphorus-based solid waste can be directly used for phosphoric acid production, replacing 15%-20% of phosphate rock raw materials. This fundamentally solves the industry pain points such as tailings storage leachate pollution and dependence on wastewater treatment agents, enabling the phosphorus resource utilization model to shift from "end-of-pipe treatment" to "process recycling", providing key technical support for carbon emission reduction in the phosphorus chemical industry. Attached Figure Description

[0027] Figure 1 Example flow chart of process for preparing phosphate concentrate from phosphorus-based solid waste in conjunction with phosphorus-rich wastewater;

[0028] Figure 2 The N2 adsorption-desorption curves and pore size distribution (BET) of phosphorus-based solid waste were obtained for Example 1 and Comparative Example 1.

[0029] Figure 3 X-ray diffraction (XRD) pattern of phosphate concentrate prepared in Example 1;

[0030] Figure 4 The images show actual photos of phosphorus-based solid waste and phosphorus concentrate from Example 1.

[0031] Figure 5 The data graphs are for simulated phosphorus-rich wastewater treatment of phosphorus-based solid waste obtained in Examples 1, 2 and 4. Detailed Implementation

[0032] The following specific embodiments provide a further detailed description of the present invention. Unless otherwise specified, all pharmaceutical products used in the embodiments are commercially available, and all methods used are conventional methods in the art. All contents mentioned in this patent are mass percentages. The amounts of raw materials and product indicators in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 below.

[0033] Table 1 Raw Material Usage and Product Specifications

[0034]

[0035] Example 1

[0036] like Figure 1 As shown in the figure, this embodiment provides a method for preparing phosphate concentrate based on phosphorus-rich wastewater and phosphorus-based solid waste through phosphorus phase reconstruction. The steps are as follows:

[0037] (1) After thoroughly mixing 10g of phosphate tailings (CaO+MgO content 57.28%, P2O5 content 4.75%) and 0.8g of phosphogypsum (CaSO4·2H2O content 86.82%, SiO2 content 7.63%), the mixture was placed in a muffle furnace for roasting. The specific roasting process was controlled at 10℃·min. -1 Preheat at a rate of 450℃ for 45 minutes, then increase the temperature by 10℃·min. -1 The temperature was rapidly increased to 950℃ and held constant for 90 minutes. The mixture was then cooled to below 200℃ in the furnace and removed. It was then cooled to room temperature in an environment with humidity <15% and stored in an oxygen-free environment to obtain 6.8g of porous phosphorus-based solid waste mixture.

[0038] (2) Grind and mix 6.8g of phosphorus-based solid waste mixture with 6.8g of quicklime and pass it through a 400-mesh sieve (-0.038mm) to obtain 13.6g of solid phosphorus carrier;

[0039] (3) Prepare a 14.5 ml emulsion (27.2 g) by mixing 13.6 g of solid phosphorus carrier with 13.6 g of water;

[0040] (4) Transfer 14.5 ml of the emulsion to a 4.08 L volume container with a total phosphorus concentration of 1000 mg·L⁻¹. -1In phosphorus-rich wastewater (volume ratio 1:281.4), the mixture was thoroughly stirred for 4 hours. After the reaction was complete, it was filtered and separated to obtain a precipitate, which was dried at 120℃ to obtain 22.6 g of phosphate concentrate with a P2O5 content of 30.39%. The residual total phosphorus concentration in the filtered phosphorus-rich wastewater was 48.8 mg·L⁻¹. -1 .

[0041] The phosphorus-based solid waste (solid-phase phosphorus carrier) obtained in step (2) and the refined phosphate ore obtained in step (4) are shown in the following physical images. Figure 4 As shown.

[0042] Example 2

[0043] like Figure 1 As shown in the figure, this embodiment provides a method for preparing phosphate concentrate based on phosphorus-rich wastewater and phosphorus-based solid waste through phosphorus phase reconstruction. The steps are as follows:

[0044] (1) After thoroughly mixing 10g of phosphate tailings (CaO+MgO content 57.28%, P2O5 content 4.75%) and 0.8g of phosphogypsum (CaSO4·2H2O content 86.82%, 7.63%), the mixture was placed in a muffle furnace for roasting. The specific roasting process was controlled at 10℃·min. -1 Preheat at a rate of 450℃ for 45 minutes, then increase the temperature by 10℃·min. -1 The temperature was rapidly increased to 950℃ and held constant for 90 minutes. The mixture was then cooled to below 200℃ in the furnace and removed. It was then cooled to room temperature in an environment with humidity <15% and stored in an oxygen-free environment to obtain 6.8g of porous phosphorus-based solid waste mixture.

[0045] (2) Grind and mix 6.8g of phosphorus-based solid waste mixture with 6.8g of quicklime and pass it through a 400-mesh sieve (-0.038mm) to obtain 13.6g of solid phosphorus carrier;

[0046] (3) Prepare a 14.5 ml emulsion (27.2 g) by mixing 13.6 g of solid phosphorus carrier with 13.6 g of water;

[0047] (4) Transfer 14.5 ml of the emulsion to a 2.04 L volume container with a total phosphorus concentration of 2000 mg·L⁻¹. -1 In phosphorus-rich wastewater (volume ratio 1:141), the mixture was thoroughly stirred for 4 hours. After the reaction was complete, it was filtered and separated to obtain a precipitate, which was dried at 120℃ to obtain 22.8g of phosphate concentrate (P2O5 content 30.84%). The residual total phosphorus concentration in the filtered phosphorus-rich wastewater was 79.3 mg·L⁻¹. -1 .

[0048] Example 3

[0049] like Figure 1As shown in the figure, this embodiment provides a method for preparing phosphate concentrate based on phosphorus-rich wastewater and phosphorus-based solid waste through phosphorus phase reconstruction. The steps are as follows:

[0050] (1) After thoroughly mixing 10g of phosphate tailings (CaO+MgO content 52.65%, P2O5 content 4.89%) and 0.4g of phosphogypsum (CaSO4·2H2O content 86.82%, SiO2 content 7.63%), the mixture was placed in a muffle furnace for roasting. The specific roasting process was controlled at 5℃·min. -1 Preheat at a rate of 450℃ for 30 minutes, then increase the temperature by 10℃·min. -1 The temperature was rapidly increased to 980℃ and held constant for 60 minutes. The mixture was then cooled to below 200℃ in the furnace and removed. It was then cooled to room temperature in an environment with humidity <15% and stored in an oxygen-free environment to obtain 6.4g of porous phosphorus-based solid waste mixture.

[0051] (2) Grind and mix 6.4g of phosphorus-based solid waste mixture with 6.4g of quicklime and pass it through a 400-mesh sieve (-0.038mm) to obtain 12.8g of solid phosphorus carrier;

[0052] (3) Prepare a 13.6 ml emulsion (25.6 g) by mixing 12.8 g of solid phosphorus carrier with 12.8 g of water;

[0053] (4) Transfer 13.6 ml of the emulsion to a 4.08 L volume container with a total phosphorus concentration of 1000 mg·L⁻¹. -1 In phosphorus-rich wastewater (volume ratio 1:300), the mixture was thoroughly stirred for 2 hours. After the reaction was complete, it was filtered and separated to obtain a precipitate, which was dried at 120℃ to obtain 21.3g of phosphate concentrate (P2O5 content 29.67%). The residual total phosphorus concentration in the filtered phosphorus-rich wastewater was 45.7 mg·L⁻¹. -1 .

[0054] Example 4

[0055] like Figure 1 As shown in the figure, this embodiment provides a method for preparing phosphate concentrate based on phosphorus-rich wastewater and phosphorus-based solid waste through phosphorus phase reconstruction. The steps are as follows:

[0056] (1) After thoroughly mixing 10g of phosphate tailings (CaO+MgO content 52.65%, P2O5 content 4.89%) and 0.4g of phosphogypsum (CaSO4·2H2O content 86.82%, SiO2 content 7.63%), the mixture was placed in a muffle furnace for roasting. The specific roasting process was controlled at 10℃·min. -1 Preheat at a rate of 450℃ for 60 min, then increase the temperature by 5℃·min. -1The temperature was rapidly increased to 1000℃ and held constant for 60 minutes. The mixture was then cooled to below 200℃ in the furnace and removed. It was then cooled to room temperature in an environment with humidity <15% and stored in an oxygen-free environment to obtain 6.4g of porous phosphorus-based solid waste mixture.

[0057] (2) Grind and mix 6.4g of phosphorus-based solid waste mixture with 5.2g of quicklime, and pass it through a 400-mesh sieve (-0.038mm) to obtain 11.6g of solid phosphorus carrier;

[0058] (3) Prepare a 12.4 ml emulsion (23.2 g) by mixing 11.6 g of solid phosphorus carrier with 11.6 g of water;

[0059] (4) Transfer 12.4 ml of the emulsion into a 6.80 L container with a total phosphorus concentration of 600 mg·L⁻¹. -1 In phosphorus-rich wastewater (volume ratio 1:548.4), the mixture was thoroughly stirred for 4 hours. After the reaction was complete, it was filtered and separated to obtain a precipitate, which was dried at 120℃ to obtain 20.2g of phosphate concentrate (P2O5 content 28.16%). The residual total phosphorus concentration in the filtered phosphorus-rich wastewater was 18.8 mg·L⁻¹. -1 .

[0060] Comparative Example 1

[0061] This comparative example provides a method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste (without the addition of phosphogypsum), the steps of which are as follows:

[0062] (1) Place 10g of phosphorus tailings (CaO+MgO content 57.28%, P2O5 content 4.75%) into a muffle furnace for roasting. The specific roasting process is controlled at 10℃·min. -1 Preheat at a rate of 450℃ for 45 minutes, then increase the temperature by 10℃·min. -1 The temperature was rapidly increased to 950℃ and held constant for 90 minutes. The mixture was then cooled to below 200℃ in the furnace and removed. It was then cooled to room temperature in an environment with humidity <15% and stored in an oxygen-free environment to obtain 6.0g of porous phosphorus-based solid waste mixture.

[0063] (2) Grind and mix 6.0g of phosphorus-based solid waste mixture with 6.0g of quicklime, and pass it through a 400-mesh sieve (-0.038mm) to obtain 12.0g of solid phosphorus carrier;

[0064] (3) Prepare a 12.5 ml emulsion (24.0 g) by mixing 12.0 g of solid phosphorus carrier with 12.0 g of water;

[0065] (4) Transfer 12.5 ml of the emulsion to a 4.08 L volume container with a total phosphorus concentration of 1000 mg·L⁻¹. -1In the phosphorus-rich wastewater, the mixture was thoroughly stirred for 4 hours. After the reaction was complete, it was filtered and separated to obtain a precipitate, which was dried at 120℃ to obtain 21.2g of phosphate concentrate (P2O5 content 24.64%). The residual total phosphorus concentration in the filtered phosphorus-rich wastewater was 167.9 mg·L⁻¹. -1 .

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste (without the addition of quicklime), the steps of which are as follows:

[0068] (1) After thoroughly mixing 10g of phosphate tailings (CaO+MgO content 57.28%, P2O5 content 4.75%) and 0.4g of phosphogypsum (CaSO4·2H2O content 86.82%, SiO2 content 7.63%), the mixture was placed in a muffle furnace for roasting. The specific roasting process was controlled at 10℃·min. -1 Preheat at a rate of 450℃ for 45 minutes, then increase the temperature by 10℃·min. -1 The temperature was rapidly increased to 950℃ and held constant for 90 minutes. The mixture was then cooled to below 200℃ in the furnace and removed. It was then cooled to room temperature in an environment with humidity <15% and stored in an oxygen-free environment to obtain 6.4g of porous phosphorus-based solid waste mixture.

[0069] (2) Grind 6.4g of phosphorus-based solid waste mixture and pass it through a 400-mesh sieve (-0.038mm) to obtain 6.4g of solid phosphorus carrier;

[0070] (3) Prepare a 13.3 ml emulsion (12.8 g) by mixing 6.4 g of solid phosphorus carrier with 6.4 g of water;

[0071] (4) Transfer 13.3 ml of emulsion into 2.04 L of a solution with a total phosphorus concentration of 1000 mg·L⁻¹. -1 In the phosphorus-rich wastewater, the mixture was thoroughly stirred for 4 hours. After the reaction was complete, it was filtered and separated to obtain a precipitate, which was dried at 120℃ to obtain 10.7g of phosphate concentrate (P2O5 content 23.78%). The residual total phosphorus concentration in the filtered phosphorus-rich wastewater was 238.1 mg·L⁻¹. -1 .

[0072] Performance Characterization

[0073] (1) The chemical composition (%) of the phosphate concentrates prepared in Examples 1-4 and Comparative Examples 1-2 was analyzed by X-ray fluorescence spectrometry (XRF), and the results are shown in Table 2.

[0074] Table 2. XRF for preparing phosphate concentrate in examples and comparative examples.

[0075]

[0076] As shown in Table 2, the P2O5 content in the phosphate concentrates prepared in Examples 1-4 is >28%, while the P2O5 content in the phosphate concentrates prepared in Comparative Examples 1-2 is only 22.78%-24.64%. The physical images of the phosphorus-based solid waste and phosphate concentrate from Example 1 are shown below. Figure 3 As shown.

[0077] (2) The pore structure parameters of the phosphorus-based solid waste obtained in Example 1 and Comparative Example 1 were analyzed using a BET analyzer. The results are shown in Table 3.

[0078] Table 3. Pore structure parameters of phosphorus-based solid waste obtained in Example 1 and Comparative Example 1.

[0079] Sample Name <![CDATA[S BET / (m 2 ·g -1 )]]> <![CDATA[Single pore volume / (cm 3 ·g -1 )]]> <![CDATA[Total pore volume / (cm 3 ·g -1 )]]> Average pore size / nm Example 1 22.7144 0.132579 0.114949 23.3471 Comparative Example 1 20.2392 0.109585 0.114030 21.6579

[0080] As can be seen from the data in Table 3, both Example 1 and Comparative Example 1 are mesoporous materials, with an average pore size between that of microporous and macroporous materials. Example 1 incorporated phosphogypsum, while Comparative Example 1 did not. The incorporation of phosphogypsum hinders the growth of CaO / MgO grains during the high-temperature calcination of the phosphorus-based solid waste, thereby refining the CaO / MgO grains. Therefore, the specific surface area of ​​the phosphorus-based solid waste in Example 1 (22.7144 m²) is relatively small. 2 ·g -1 The specific surface area is greater than that of Comparative Example 1 (20.2392 m²). 2 ·g -1 ).

[0081] The N2 adsorption-desorption curves and pore size distributions of phosphorus-based solid waste obtained in Example 1 and Comparative Example 1 are shown below. Figure 2 As shown in (a) and (b), the adsorption-desorption curves of Example 1 and Comparative Example 1 both conform to the type III adsorption isotherm. The adsorption amount increases slowly at low relative pressure (P / P0<0.3) and then rises rapidly at higher pressure, indicating that it belongs to mesoporous or macroporous materials. The middle section of the curve shows an H3 type hysteresis loop, suggesting that the material is a polycrystalline powder with small grain size and mesopores formed by intergranular voids.

[0082] (3) The phosphate concentrate prepared in Example 1 was identified using X-ray diffraction (XRD) and compared with diffraction files (PDF) in the standard database. The results are as follows: Figure 3 As shown. By Figure 3 It can be seen that the main mineral composition of the phosphate concentrate prepared in Example 1 is hydroxyapatite, quicklime and periclase.

[0083] (4) Figure 5As shown, the preparation of phosphate concentrate was carried out according to the steps of Example 1. The stirring reaction time in step (4) was adjusted to 30 min, 60 min, 90 min, 120 min, 180 min and 240 min respectively. The phosphate concentrate grade and the residual concentration of phosphorus-rich wastewater corresponding to each reaction time are shown in Figure a.

[0084] Phosphate concentrate was prepared according to the steps of Example 2. The stirring reaction time in step (4) was adjusted to 30 min, 60 min, 90 min, 120 min, 180 min and 240 min respectively. The phosphate concentrate grade and the residual concentration of phosphorus-rich wastewater corresponding to each reaction time are shown in Figure b.

[0085] Phosphate concentrate was prepared according to the steps of Example 4. The stirring reaction time in step (4) was adjusted to 30 min, 60 min, 90 min, 120 min, 180 min and 240 min respectively. The phosphate concentrate grade and the residual concentration of phosphorus-rich wastewater corresponding to each reaction time are shown in Figure c.

[0086] from Figure 5 It can be seen that the highly active calcium and magnesium oxides generated by high-temperature activation of phosphorus-based solid waste, together with phosphorus-rich wastewater, achieve a closed-loop cycle of phosphorus resources, thus demonstrating that the new dual-waste synergistic treatment model constructed in this invention realizes pollution transformation and value-added.

Claims

1. A method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste, characterized in that, Includes the following steps: (1) After thoroughly mixing phosphate tailings and phosphogypsum at a mass ratio of 100:(3~8), calcination is carried out, wherein the calcination includes: at 5~10℃·min -1 Preheat at a rate of 400-450 °C for 30-60 min, then increase the temperature by 5-10 °C / min. -1 The temperature was rapidly increased to 880~1050 ℃ and held constant for 60~120 min. After cooling in the furnace to below 200 ℃, the mixture was removed and cooled to room temperature to obtain a porous phosphorus-based solid waste mixture. (2) Grind and mix the phosphorus-based solid waste mixture obtained in step (1) with quicklime at a mass ratio of 2: (1~2) to obtain a solid phosphorus carrier; (3) Prepare an emulsion by mixing the solid phosphorus carrier obtained in step (2) with water; (4) Add the emulsion obtained in step (3) to a total phosphorus concentration of 600 mg·L⁻¹ -1 ~2000 mg·L -1 In phosphorus-rich wastewater, the mixture is stirred thoroughly to react. After the reaction is complete, the precipitate is filtered out and dried to obtain phosphate concentrate. The total phosphorus concentration of the filtrate obtained from the filtration is ≤80 mg·L⁻¹. -1 The obtained phosphate concentrate has a P2O5 content of ≥28%.

2. The method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste as described in claim 1, characterized in that, In step (1), the content of CaO+MgO in the phosphorus tailings is 45%~68%, and the content of P2O5 is ≤5%; the content of CaSO4·2H2O in the phosphogypsum is 80%~94%, and the content of SiO2 is ≤10%.

3. The method for preparing phosphate concentrate from phosphorus-rich wastewater in synergistic with phosphorus-based solid waste as described in claim 1, characterized in that, In step (2), the phosphorus-based solid waste mixture is ground and mixed with quicklime to a mesh size of less than 400.

4. The method for preparing phosphate concentrate from phosphorus-rich wastewater in synergistic with phosphorus-based solid waste as described in claim 1, characterized in that, In step (3), the solid phosphorus carrier and water are mixed at a mass ratio of 1:1 to prepare an emulsion.

5. The method for preparing phosphate concentrate from phosphorus-rich wastewater in synergistic with phosphorus-based solid waste as described in claim 1, characterized in that, In step (4), the volume ratio of the emulsion to the phosphorus-rich wastewater is 1: (140~600).

6. The method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste as described in claim 1, characterized in that, In step (4), the reaction is stirred thoroughly for 2-4 hours.

7. The method for preparing phosphate concentrate from phosphorus-rich wastewater in conjunction with phosphorus-based solid waste as described in claim 1, characterized in that, The obtained phosphate concentrate has a P2O5 content of 28% to 31%.

8. A phosphate concentrate, characterized in that, It is prepared by the method of preparing phosphate concentrate from any of the phosphorus-rich wastewater and phosphorus-based solid waste as described in claims 1 to 7.

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