Method for preparing phosphate concentrate through cooperation of phosphorus-rich wastewater and phosphorus-based solid waste

Abstract

The invention discloses a method for preparing phosphate concentrate from phosphorus-rich wastewater and phosphorus-based solid waste, and relates to the technical field of comprehensive utilization of phosphorus-based solid waste resources, the preparation method comprises the following steps: (1) fully mixing phosphate tailings and phosphogypsum, and calcining to obtain a porous phosphorus-based solid waste mixture; (2) grinding and mixing the phosphorus-based solid waste mixture and quick lime to obtain a solid-phase phosphorus carrier; (3) preparing an emulsion from the solid-phase phosphorus carrier and water; and (4) adding the emulsion into phosphorus-rich wastewater, fully stirring and reacting, filtering and separating out precipitate after the reaction is finished, and drying to obtain phosphate concentrate with the P2O5 content of 28-31%. The method has the advantages that cooperative treatment of phosphorus-based solid waste and phosphorus-rich wastewater is achieved, the purpose of efficient recycling of phosphorus resources is achieved, the problems of solid waste stockpiling pollution and standard exceeding of total phosphorus in wastewater are solved, and the method has both environmental benefits and economic benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of comprehensive utilization of phosphorus-based solid waste, and specifically refers to a method for preparing phosphorus concentrate by reconstructing the phosphorus phase state of phosphorus-rich wastewater and coordinating phosphorus-based solid waste. Background Art

[0002] As a typical solid waste generated in the process of phosphorus ore beneficiation, the contradiction between the resource endowment characteristics of phosphorus tailings and the bottleneck of comprehensive utilization has become increasingly prominent. From the analysis of mineral composition, dolomite CaMg(CO3)2 in phosphorus tailings accounts for up to 60%-80%, and at the same time contains residual phosphorus (P2O5 content 2%-5%) and trace metal elements. This mineral structure mainly composed of calcium and magnesium carbonates can be directionally transformed into highly active calcium oxide CaO and magnesium oxide MgO after high-temperature calcination, and its specific surface area is significantly increased (up to 15m 2 ·g -1 -35m 2 ·g -1 ), and a porous structure is formed, providing an ideal reaction interface for the adsorption and chemical precipitation of phosphate radical (PO4) 3- . However, the current mainstream underground filling and stacking disposal modes not only cause the idle solidification of millions of tons of calcium and magnesium resources every year, but also lead to the continuous loss of residual phosphorus in the tailings (annual loss exceeds 100,000 tons), forming a contradictory situation of coexistence of "solid waste accumulation" and "phosphorus resource shortage".

[0003] Existing phosphorus tailings utilization technologies have significant limitations: First, the traditional filling process only realizes the physical form transformation, without releasing the chemical activity of calcium and magnesium components, and the resource utilization rate is less than 30%; Second, wet stacking causes leachate pollution (total phosphorus leaching concentration reaches 8mg·L -1 -20mg·L -1 ), and additional curing agents and anti-seepage projects need to be invested, and the treatment cost is as high as 90-150 yuan / ton; Third, the residual phosphorus in the tailings is not effectively recovered, resulting in a vicious cycle of "separation-loss" in the phosphorus chemical industry chain. At the same time, traditional treatment methods for industrial phosphorus-rich wastewater (total phosphorus concentration 400mg / L-2000mg·L -1 ) generally have technical pain points such as high reagent cost (such as 15-18 yuan / ton of water treatment cost for calcium salt / aluminum salt / iron salt method) and large sludge production (sludge yield of chemical precipitation method is 15%-30%).

[0004] Based on the above background, it is urgent to develop a method for preparing phosphorus concentrate by coordinating phosphorus-based solid waste with phosphorus-rich wastewater, and through technological innovation, realize the transformation from "end treatment" to "resource reconstruction", providing key technical support for the green transformation of the phosphorus chemical industry. Summary of the Invention

[0005] The purpose of the present invention is to solve the shortcomings of the above-mentioned background technology. It uses phosphate tailings as the main raw material, supplemented by phosphogypsum as a crystallizing agent, and phosphorus-rich wastewater as a phosphorus source, to provide a method for preparing phosphate concentrate based on phosphorus phase reconstruction of phosphorus-rich wastewater and coordinated phosphorus-based solid waste.

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

[0007] (1) Phosphate tailings and phosphogypsum are fully mixed in a mass ratio of 100:(3-8) and then calcined to obtain a porous phosphorus-based solid waste mixture;

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

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

[0010] (4) Add the emulsion obtained in step (3) to a solution with a total phosphorus concentration of 600 mg·L -1 ~2000mg·L -1 The phosphorus-rich wastewater is stirred thoroughly for reaction, and after the reaction is completed, the precipitate is separated by filtration and then dried to obtain phosphate concentrate.

[0011] Preferably, in step (1), the calcination comprises: -1 Heat to 400-450℃ and preheat for 30-60min, then heat at 5-10℃·min -1 The temperature was raised to 880-1050°C at a constant rate for 60-120 min, then cooled to below 200°C in the furnace, taken out and cooled to room temperature.

[0012] Preferably, in step (1), the CaO+MgO content of the phosphate tailings is 48% to 68%, and the P2O5 content is ≤5%; the CaSO4·2H2O content of 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 size of less than 400 mesh.

[0014] Preferably, in step (3), the solid phase phosphorus carrier and water are mixed in a mass ratio of 1:1 to form 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 sufficiently stirred for 2 to 4 h

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

[0018] Preferably, the P2O5 content in the obtained phosphate concentrate is 28% - 31%.

[0019] The present invention also provides a phosphate concentrate prepared by the method for preparing a phosphate concentrate by using any one of the above phosphorus-rich wastewaters in cooperation with phosphorus-based solid wastes.

[0020] In the above preparation method:

[0021] (1) In the present invention, the phosphate tailings are the key raw materials for the phase reconstruction of phosphorus. Through thermodynamic analysis, it can be known that the main mineral composition of the phosphate tailings is dolomite. Dolomite undergoes staged decomposition when calcined at 400°C - 950°C: in the first stage, MgCO3 decomposes to form active MgO (400°C - 600°C), and in the second stage, CaCO3 decomposes into porous CaO (700°C - 900°C). The nano-scale metal oxides formed during the thermal decomposition of dolomite have strong Lewis basicity and can undergo chemical coordination reactions with phosphate ions, and its theoretical adsorption capacity reaches 120 mg / g - 180 mg / g. During technical implementation, the calcined tailings powder (particle size D 90 <45 μm) is added to the phosphorus-rich wastewater system, and CaO / MgO reacts with (PO4) 3- to generate stable compounds such as hydroxyapatite Ca5(PO4)3(OH) and struvite (MgNH4PO4), realizing the efficient conversion of liquid-phase phosphorus to solid-phase phosphorus (conversion rate ≥ 95%), and finally achieving the purpose of converting phosphate tailings into a regenerated phosphate concentrate with a P2O content ≥ 28%.

[0022] (2) In the present invention, the phosphogypsum is an important crystallization agent during the calcination process of phosphate tailings. The theory of SO4 2- inhibiting the crystal growth of CaO and MgO mainly comes from the mineralizing agent effect of sulfates at high temperatures and the crystal growth kinetics mechanism. ① Mineralizing agent effect: At high temperatures, SO4 2- ions will adsorb on the surface or grain boundaries of CaO and MgO grains, hindering the diffusion and migration between grains, thereby inhibiting the excessive growth of grains, maintaining small grains and high specific surface area, and enhancing the reaction activity. ② Lattice defects and specific surface area: SO4 2- entering the oxide lattice may cause lattice distortion, forming oxygen vacancies or cation vacancies, increasing the defect density, and increasing the surface energy. At the same time, the decrease in grain size will significantly increase the specific surface area and enhance the reaction activity.

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

[0024] (1) Fully activate the functionality of calcium and magnesium elements in phosphorus tailings. The calcium carbonate and magnesium carbonate rich in phosphorus tailings often exist in a chemically inert form, and the extraction efficiency of traditional physical separation methods is less than 15%. Through the gradient calcination process at 880°C - 1050°C, the carbonate is decomposed into highly active calcium oxide and magnesium oxide (specific surface area > 25m 2 / g), the density of surface hydroxyl sites is increased by 3 - 5 times, and the chemical adsorption capacity for phosphate radicals reaches 2 - 3 times that of the traditional lime method. The utilization rate of phosphorus tailings is increased from less than 20% to more than 95%, and the energy consumption per ton of treatment is reduced by 35% compared with the conventional calcination process.

[0025] (2) Build a new model for the coordinated treatment of double wastes to achieve pollution transformation and value addition. Aiming at the treatment problems of more than 30 million tons of phosphorus tailings and 1 billion cubic meters of phosphorus-rich wastewater (total phosphorus 400mg·L -1 -2000mg·L -1 ) in the phosphorus chemical industry every year, the coupling mechanism of "treating wastewater with waste ore" is proposed for the first time. The adsorption rate of the calcined phosphorus-based solid waste for the total phosphorus in the wastewater reaches 98%, the effluent TP is stably ≤ 80mg / L, and at the same time, P2O5 in the saturated adsorbed solid phase is enriched to 28% - 31%, meeting the phosphorus concentrate quality standard. Compared with the traditional chemical precipitation method, the sludge production is reduced by 90%, and the operating cost is reduced by 55% compared with the ion exchange method.

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

[0027] Figure 1 It is a process flow example diagram for preparing phosphorus concentrate from phosphorus-based solid waste and phosphorus-rich wastewater;

[0028] Figure 2 It is the N2 adsorption - desorption curve and pore size distribution diagram (BET) of the phosphorus-based solid waste obtained in Example 1 and Comparative Example 1;

[0029] Figure 3 It is the X-ray diffraction spectrum diagram (XRD) of the phosphorus concentrate prepared in Example 1;

[0030] Figure 4 It is the physical diagram of the phosphorus-based solid waste and phosphorus concentrate in Example 1;

[0031] Figure 5 Data graphs of treating simulated phosphorus-rich wastewater with phosphorus-based solid waste were obtained for Example 1, Example 2, and Example 4. Specific implementation manners

[0032] The following specific examples further illustrate the present invention in detail. Unless otherwise specified, the drugs used in the examples are all commercially available products, and the methods used are all conventional methods in the art. The contents mentioned in this patent are all mass percentages. The raw material dosages and product indexes in Examples 1-4 and Comparative Examples 1-2 are shown in Table 1 below.

[0033] Table 1 Raw material dosages and product indexes

[0034]

[0035] Example 1

[0036] As Figure 1 shown, this example provides a method for preparing phosphorus concentrate by synergistically treating phosphorus-rich wastewater with phosphorus-based solid waste based on phosphorus phase reconstruction, and the steps are as follows:

[0037] (1) After fully mixing 10 g of phosphorus tailings (CaO + MgO content 57.28%, P2O5 content 4.75%) and 0.8 g of phosphogypsum (CaSO4·2H2O content 86.82%, SiO2 content 7.63%), place them in a muffle furnace for roasting. The specific roasting process: control the heating rate to 450 °C at a rate of 10 °C·min -1 for preheating for 45 min, and then heat to 950 °C at a rate of 10 °C·min -1 for constant temperature for 90 min, cool with the furnace to below 200 °C and take out, and cool to room temperature in an environment with humidity <15% and seal in an oxygen-free environment to obtain 6.8 g of porous phosphorus-based solid waste mixture;

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

[0039] (3) Prepare 13.6 g of the solid-phase phosphorus carrier and 13.6 g of water into a 14.5 ml emulsion (27.2 g);

[0040] (4) Introduce 14.5 ml of the emulsion into a volume of 4.08 L and a total phosphorus concentration of 1000 mg·L -1In the phosphorus-rich wastewater (volume ratio of 1:281.4), mix and stir well for 4 h. After the reaction is completed, filter and separate to obtain a precipitate, which is dried at 120 °C to obtain 22.6 g of phosphate concentrate with a P2O5 content of 30.39% (P2O5 content of 30.39%). The remaining total phosphorus concentration in the filtered phosphorus-rich wastewater is 48.8 mg·L -1 。

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

[0042] Example 2

[0043] As Figure 1 shown, this example provides a method for preparing phosphate concentrate by synergistically using phosphate-based solid waste based on phosphorus phase reconstruction of phosphorus-rich wastewater, and the steps are as follows:

[0044] (1) After fully mixing 10 g of phosphate tailings (CaO + MgO content of 57.28%, P2O5 content of 4.75%) and 0.8 g of phosphogypsum (CaSO4·2H2O content of 86.82%, 7.63%), place them in a muffle furnace for roasting. The specific roasting process: control the heating rate to 450 °C at 10 °C·min -1 rate and preheat for 45 min, then heat to 950 °C at 10 °C·min -1 rate and keep it at a constant temperature for 90 min. Cool it in the furnace to below 200 °C and take it out, and cool it to room temperature in an environment with a humidity <15% and seal it to avoid oxygen to obtain 6.8 g of porous phosphate-based solid waste mixture;

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

[0046] (3) Prepare 13.6 g of the solid-phase phosphorus carrier and 13.6 g of water into a 14.5 ml emulsion (27.2 g);

[0047] (4) Pour 14.5 ml of the emulsion into 2.04 L of phosphorus-rich wastewater with a total phosphorus concentration of 2000 mg·L -1 (volume ratio of 1:141), mix and stir well for 4 h. After the reaction is completed, filter and separate to obtain a precipitate, which is dried at 120 °C to obtain 22.8 g of phosphate concentrate (P2O5 content of 30.84%), and the remaining total phosphorus concentration in the filtered phosphorus-rich wastewater is 79.3 mg·L -1 。

[0048] Example 3

[0049] As Figure 1As shown in the figure, this embodiment provides a method for preparing phosphorus concentrate by reconstructing phosphorus phase in phosphorus-rich wastewater in cooperation with phosphorus-based solid waste, and the steps are as follows:

[0050] (1) After fully mixing 10 g of phosphorus tailings (CaO + MgO content is 52.65%, P2O5 content is 4.89%) and 0.4 g of phosphogypsum (CaSO4·2H2O content is 86.82%, SiO2 content is 7.63%), place them in a muffle furnace for roasting. The specific roasting process: control the heating rate to 450 °C at a rate of 5 °C·min -1 for preheating for 30 min, and then heat to 980 °C at a rate of 10 °C·min -1 for constant temperature for 60 min, cool with the furnace to below 200 °C and take out, and cool to room temperature in an environment with humidity <15% for oxygen-free storage to obtain 6.4 g of porous phosphorus-based solid waste mixture;

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

[0052] (3) Prepare 12.8 g of the solid-phase phosphorus carrier and 12.8 g of water into a 13.6 ml emulsion (25.6 g);

[0053] (4) Pour 13.6 ml of the emulsion into 4.08 L of phosphorus-rich wastewater with a total phosphorus concentration of 1000 mg·L -1 (volume ratio is 1:300), mix and stir well for 2 h, filter and separate after the reaction is completed to obtain a precipitate, dry at 120 °C to obtain 21.3 g of phosphorus concentrate (P2O5 content is 29.67%), and the remaining total phosphorus concentration of the filtered phosphorus-rich wastewater is 45.7 mg·L -1 .

[0054] Example 4

[0055] As Figure 1 shown in the figure, this embodiment provides a method for preparing phosphorus concentrate by reconstructing phosphorus phase in phosphorus-rich wastewater in cooperation with phosphorus-based solid waste, and the steps are as follows:

[0056] (1) After fully mixing 10 g of phosphorus tailings (CaO + MgO content is 52.65%, P2O5 content is 4.89%) and 0.4 g of phosphogypsum (CaSO4·2H2O content is 86.82%, SiO2 content is 7.63%), place them in a muffle furnace for roasting. The specific roasting process: control the heating rate to 450 °C at a rate of 10 °C·min -1 for preheating for 60 min, and then heat to 980 °C at a rate of 5 °C·min -1The temperature is raised at a rate to 1000 °C and kept constant for 60 min, then cooled in the furnace to below 200 °C and taken out, and cooled to room temperature in an environment with humidity <15% to avoid oxygen and sealed to obtain 6.4 g of porous phosphorus-based solid waste mixture;

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

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

[0059] (4) Pour 12.4 ml of the emulsion into 6.80 L of phosphorus-rich wastewater with a total phosphorus concentration of 600 mg·L -1 (with a volume ratio of 1:548.4), mix and stir well for 4 h, filter and separate after the reaction is completed to obtain a precipitate, dry it at 120 °C to obtain 20.2 g of phosphorus concentrate (P2O5 content 28.16%), and the remaining total phosphorus concentration of the filtered phosphorus-rich wastewater is 18.8 mg·L -1 .

[0060] Comparative Example 1

[0061] This comparative example provides a method for preparing phosphorus concentrate by synergistically treating phosphorus-rich wastewater with phosphorus-based solid waste (without adding phosphogypsum), and the steps are as follows:

[0062] (1) Place 10 g of phosphorus tailings (CaO + MgO content 57.28%, P₂O₅ content 4.75%) in a muffle furnace for roasting. The specific roasting process: control the heating rate to 450 °C at a rate of 10 °C·min -1 and preheat for 45 min, then raise the temperature to 950 °C at a rate of 10 °C·min -1 and keep it constant for 90 min, then cool in the furnace to below 200 °C and take out, and cool to room temperature in an environment with humidity <15% to avoid oxygen and sealed to obtain 6.0 g of porous phosphorus-based solid waste mixture;

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

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

[0065] (4) Pour 12.5 ml of the emulsion into 4.08 L of phosphorus-rich wastewater with a total phosphorus concentration of 1000 mg·L -1The solution was added to the phosphorus-rich wastewater and stirred for 4 hours. After the reaction was completed, the precipitate was separated by filtration and dried at 120°C to obtain 21.2 g of phosphate concentrate (P2O5 content 24.64%). The total phosphorus concentration of the phosphorus-rich wastewater after filtration was 167.9 mg·L -1 .

[0066] Comparative Example 2

[0067] This comparative example provides a method for preparing phosphate concentrate by using phosphorus-rich wastewater in combination with phosphorus-based solid waste (without adding quicklime), and the steps are as follows:

[0068] (1) After 10 g of phosphorus tailings (CaO+MgO content 57.28%, P2O5 content 4.75%) and 0.4 g of phosphogypsum (CaSO4·2H2O content 86.82%, SiO2 content 7.63%) were fully mixed, the mixture was placed in a muffle furnace for roasting. The specific roasting process was controlled at 10 ° C·min -1 The temperature was raised to 450℃ and preheated for 45min, then the temperature was raised to 10℃·min -1 The temperature was raised to 950°C at a constant temperature for 90 minutes, and then the mixture was cooled to below 200°C in the furnace, taken out, cooled to room temperature in an environment with a humidity of <15%, and sealed to avoid oxygen, thereby obtaining 6.4 g of a porous phosphorus-based solid waste mixture.

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

[0070] (3) 6.4 g of solid phase phosphorus carrier and 6.4 g of water were prepared into 13.3 ml of emulsion (12.8 g);

[0071] (4) 13.3 ml of the emulsion was introduced into a 2.04 L tank with a total phosphorus concentration of 1000 mg / L. -1 The solution was added to the phosphorus-rich wastewater and stirred for 4 h. After the reaction was completed, the precipitate was separated by filtration and dried at 120 °C to obtain 10.7 g of phosphate concentrate (P2O5 content 23.78%). The total phosphorus concentration of the phosphorus-rich wastewater after filtration was 238.1 mg·L -1 .

[0072] Performance Characterization

[0073] (1) The chemical composition analysis (%) of the phosphate concentrates prepared in Examples 1 to 4 and Comparative Examples 1 to 2 was performed using an X-ray fluorescence spectrometer (XRF). The results are shown in Table 2.

[0074] Table 2 XRF of phosphate concentrate prepared in Examples and Comparative Examples

[0075]

[0076] As can be seen from the data in Table 2, the content of P2O5 in the main components of the phosphate rock concentrates prepared in Examples 1 to 4 is > 28%; while the content of P2O5 in the phosphate rock concentrates prepared in Comparative Examples 1 to 2 is only 22.78% - 24.64%. The physical diagrams of the phosphorus-based solid waste and phosphate rock concentrate of Example 1 are as Figure 3 shown.

[0077] (2) A BET tester was used to analyze the pore structure parameters of the phosphorus-based solid waste obtained in Example 1 and Comparative Example 1, and the results are shown in Table 3.

[0078] Table 3 Pore structure parameter table of the 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 those of Example 1 and Comparative Example 1 belong to mesoporous materials, and the average pore diameter is between that of microporous and macroporous materials; phosphogypsum was incorporated in Example 1, while no phosphogypsum was incorporated in Comparative Example 1. The incorporation of phosphogypsum will hinder the growth of CaO / MgO grains during the high-temperature calcination of the phosphorus-based solid waste, thereby achieving the refinement of the CaO / MgO grains. Therefore, the specific surface area of the phosphorus-based solid waste in Example 1 (22.7144 m 2 ·g -1 ) is larger than that of Comparative Example 1 (20.2392 m 2 ·g -1 ).

[0081] The N2 adsorption-desorption curves and pore size distributions of the phosphorus-based solid waste obtained in Example 1 and Comparative Example 1 are as Figure 2 shown in (a) and (b) therein. 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 pressures, belonging to mesoporous or macroporous materials; the middle section of the curve shows an H3-type hysteresis loop, and it is speculated that the material is polycrystalline powder with small grain size, and the mesopores are formed by the voids between grains.

[0082] (3) An X-ray diffractometer (XRD) was used to identify the phosphate rock concentrate prepared in Example 1 and compared with the diffraction file (PDF) card in the standard database, and the results are as Figure 3 shown. As Figure 3 can be seen, the main mineral components of the phosphate rock concentrate prepared in Example 1 are hydroxyapatite, slaked lime and periclase.

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

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

[0085] The preparation of phosphate rock concentrate was carried out according to the steps of Example 4, and the stirring reaction time in step (4) was adjusted to be 30 min, 60 min, 90 min, 120 min, 180 min, and 240 min in sequence. The phosphate rock concentrate grade and the remaining 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 cooperate with phosphorus-rich wastewater to achieve the closed-loop cycle of phosphorus resources, thus indicating that the new dual-waste collaborative treatment mode constructed by the present invention realizes the value-added transformation of pollution.

Claims

1. A method for preparing phosphorus concentrate by synergistically treating phosphorus-rich wastewater and phosphorus-based solid waste, characterized in that, The following steps are involved: (1) Phosphate tailings and phosphogypsum are fully mixed in a mass ratio of 100:(3-8) and then calcined to obtain a porous phosphorus-based solid waste mixture; (2) grinding and mixing the phosphorus-based solid waste mixture obtained in step (1) with quicklime in a mass ratio of 2:(1-2) to obtain a solid-phase phosphorus carrier; (3) preparing an emulsion by mixing the solid phase phosphorus carrier obtained in step (2) with water; (4) Add the emulsion obtained in step (3) to a solution with a total phosphorus concentration of 600 mg·L -1 ~2000mg·L -1 The phosphorus-rich wastewater is stirred thoroughly for reaction, and after the reaction is completed, the precipitate is separated by filtration and then dried to obtain phosphate concentrate.

2. The method for co-preparing phosphate concentrate from phosphorus-rich wastewater and phosphorus-based solid waste according to claim 1, characterized in that, In step (1), the calcination includes: heating at a rate of 5 - 10 °C·min -1 to a preheating temperature of 400 - 450 °C at a rate of 5 - 10 °C·min -1 for 30 - 60 min, then heating to a constant temperature of 880 - 1050 °C at a rate of 5 - 10 °C·min for 60 - 120 min, cooling in the furnace to below 200 °C, taking out and then cooling to room temperature.

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

4. The method for preparing phosphorus concentrate by using phosphorus-rich wastewater and phosphorus-based solid waste in a coordinated manner according to claim 1, characterized in that, In step (2), the phosphorus-based solid waste mixture is ground and mixed with quicklime to a size of less than 400 mesh.

5. The method for co-preparing phosphorus concentrate from phosphorus-rich wastewater and phosphorus-based solid waste according to claim 1, wherein, In step (3), the solid phase phosphorus carrier and water are mixed in a mass ratio of 1:1 to prepare an emulsion.

6. The method for preparing phosphorus concentrate by using phosphorus-rich wastewater and phosphorus-based solid waste in cooperation as claimed in claim 1, wherein, In step (4), the volume ratio of the emulsion to the phosphorus-rich wastewater is 1:(140-600).

7. The method for preparing phosphorus concentrate from phosphorus-rich wastewater and phosphorus-based solid waste as claimed in claim 1, wherein, In step (4), the reaction is stirred thoroughly for 2 to 4 hours.

8. The method for preparing phosphorus concentrate by using phosphorus-rich wastewater in cooperation with phosphorus-based solid waste according to claim 1, wherein In step (4), the total phosphorus concentration of the filtrate obtained by filtration ≤ 80 mg·L -1 , and the P2O5 content in the obtained phosphate concentrate ≥ 28%.

9. The method for preparing phosphorus concentrate by using phosphorus-rich wastewater and phosphorus-based solid waste in cooperation as claimed in claim 8, wherein, The P2O5 content in the obtained phosphate concentrate is 28% to 31%.

10. A phosphate concentrate, characterized in that, The phosphate concentrate is prepared by the method for preparing phosphate concentrate by using any one of phosphorus-rich wastewater and phosphorus-based solid waste according to claims 1 to 9.

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