Modified phosphorus removal material based on phosphate tailings as well as preparation and application methods of modified phosphorus removal material

Abstract

The invention relates to the technical field of wastewater phosphorus removal, in particular to a modified phosphorus tailing phosphorus removal adsorbent, a preparation method thereof and application of the modified phosphorus tailing phosphorus removal adsorbent in phosphorus-containing wastewater phosphorus removal. The preparation method comprises the following steps: grinding phosphate tailings, sieving with a 200-mesh sieve, drying to obtain pretreated phosphate tailings, and calcining the pretreated phosphate tailings in a muffle furnace at 500-1050 DEG C for 0.6-3 hours to obtain the modified phosphate tailing dephosphorization adsorbent. The dephosphorization conditions are as follows: the pH value of a phosphorus solution before reaction is 4-9, the reaction temperature is 37 DEG C, the rotating speed is 200r / min, the reaction time is 0.7-48h, and the maximum adsorption capacity can reach 112.41 mg / g. And combining the calcined phosphate tailings and the uncalcined phosphate tailings according to a certain mass ratio to prepare the unfired ceramsite. The method provided by the invention is simple and economic, and can effectively utilize phosphate tailing resources to prepare the high-performance adsorbent.

Description

Technical Field

[0001] The invention relates to phosphorus pollution control technology for wastewater and surface water, and in particular to a material for removing phosphorus from water. Background Art

[0002] Eutrophication refers to the excessive nutrients (mainly nitrogen and phosphorus) in water bodies, which leads to the rapid reproduction of algae and other aquatic plants, thus causing a series of problems of ecological imbalance in water bodies. The main causes of eutrophication include agricultural runoff, domestic sewage, industrial wastewater and atmospheric deposition. After the nitrogen and phosphorus compounds from these sources enter the water body, they promote the excessive growth of algae and aquatic plants, eventually leading to the deterioration of water quality and the destruction of the ecological environment.

[0003] Phosphate tailings are solid waste generated during the mining and selection of phosphate ore. Due to the relatively low recovery rate of phosphate ore, a large amount of phosphate tailings is produced every year, and these tailings are usually stored in tailings ponds. By modifying phosphate tailings into phosphorus removal adsorbents, it is not only possible to effectively control eutrophication of water bodies, but also to achieve resource utilization of phosphate tailings, which has important environmental and economic significance. Future research should further optimize the modification process, improve the performance and stability of the adsorbent, and promote its application in actual water treatment. Summary of the invention

[0004] In order to solve or partially solve the problems existing in the related art, the present invention provides a modified phosphorus removal material based on phosphate tailings and a preparation and application method thereof.

[0005] The present invention has found through experimental research that when the calcination reaches a certain temperature, if the aqueous solution maintains a specific pH condition, the phosphorus concentration in the water can be reduced to the Class III surface water standard (GB3838-2002).

[0006] The present invention solves the technical problem by adopting the following technical solution: In the first aspect, the present invention provides a condition optimization of modified phosphorus removal materials based on phosphate tailings, which is characterized in that the phosphate tailings are modified at high temperature to obtain an adsorbent with better adsorption effect, and then the pH value of the phosphorus removal solution and the phosphorus removal time are optimized.

[0007] Furthermore, the high-temperature calcination temperature is 500-1050°C, and when the calcination temperature is 950°C, the phosphorus removal adsorption capacity of the modified phosphate tailings can reach the maximum.

[0008] Furthermore, the high-temperature calcination time is 0.6-3h, and when the calcination time is 1h, the phosphorus removal adsorption capacity of the modified phosphate tailings can reach the maximum.

[0009] Furthermore, the pH of the dephosphorization solution is 4-9, and when the reaction pH is 6 for 1 hour, the dephosphorization adsorption capacity of the modified phosphate tailings can reach a maximum.

[0010] Furthermore, the dephosphorization reaction time is 0.7-48h, and when the reaction time is 24h, the dephosphorization adsorption amount of the modified phosphate tailings can reach the maximum.

[0011] Furthermore, the phosphate tailings were dephosphorized under optimal conditions, and the maximum adsorption amount was 112.41 mg / g.

[0012] In the second aspect, the present invention provides a modified phosphorus removal material based on phosphate tailings, which is characterized in that uncalcined phosphate tailings and calcined phosphate tailings are uniformly mixed in a mass ratio of 1:9, 1:3, 1:1, 3:1, and 9:1, and then formed and consolidated to obtain a granular material.

[0013] Furthermore, the temperature of the high-temperature calcination is 500-1050° C. Setting the calcination temperature at 950° C. can make the composition of the obtained material meet the requirements of phosphorus removal.

[0014] Furthermore, the specific time of the high-temperature calcination depends on the type of calcination furnace equipment selected. In this method, a muffle furnace is selected and the calcination time is 1 hour. Furthermore, the size of the modified phosphorus removal material based on phosphate tailings can be set according to engineering needs. The diameter of the modified phosphorus removal material in this method is 3-5 mm.

[0015] In a third aspect, the present invention also discloses a method for preparing the modified phosphorus removal material based on phosphorus tailings, comprising the following steps: (1) putting the phosphate tailings into a calcining furnace and calcining at 950° C. for 1 hour to obtain calcined powder; (2) Uncalcined phosphate tailings and calcined phosphate tailings are mixed evenly in a mass ratio of 1:9, 1:3, 1:1, 3:1, 9:1, and then put into a round pot granulator and add water accounting for 20-40% of the mass of the powder, and then the granular material is formed and consolidated by the round pot granulator. Then, the granular material is aged for 12 hours under saturated humidity and room temperature conditions, and then steam cured for 24 hours. The final clay content of the ceramsite cannot exceed 1%, and the target product, a modified phosphorus removal material based on phosphate tailings, is obtained.

[0016] The beneficial effects of the present invention are embodied in: 1. Through high-temperature calcination modification, the internal structure of the phosphate tailings is optimized and the adsorption capacity is significantly improved; 2. The calcination process is simple and easy, suitable for industrial production; 3. Use modified phosphorus tailings to treat phosphorus-containing wastewater, with good phosphorus removal effect, and the water quality meets the standards after treatment; 4. Realize the resource utilization of phosphate tailings and reduce environmental pollution.

[0017] 5. The raw materials used in this method are easily available, the cost is low, and the operation is simple.

[0018] 6. The raw materials used to make the materials of the present invention do not contain toxic and harmful substances. The waste after phosphorus removal treatment is further enriched with phosphorus and can be used as a phosphorus-rich raw material to be composted with biomass as a fertilizer, or directly used as a cultivation nutrient soil without causing secondary pollution. Therefore, it is a safe and risk-free modified phosphorus removal material and technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The SEM images of the original phosphate tailings in Example 1 (a) and the SEM images of the sample after calcination at 950°C for 1h (b) Figure 2 The XRD patterns of the original and calcined phosphate tailings in Example 1 are shown in Figure 1. Figure 3 This is a diagram showing the phosphorus removal effect after the phosphorus tailings in Example 1 were calcined at 500-1050°C for 2 hours.

[0020] Figure 4 This is a diagram showing the phosphorus removal effect after the phosphorus tailings in Example 2 were calcined at 950°C for 0.1-3h.

[0021] Figure 5 This is a diagram showing the phosphorus removal effect of the phosphorus tailings in Example 3 in a phosphorus solution with a pH of 4-9 after calcination at 950°C for 1 hour.

[0022] Figure 6 This is a diagram showing the phosphorus removal effect of the phosphorus tailings in Example 4 after calcining at 950°C for 1 hour and then reacting in a phosphorus solution with a pH of 6 for 0.6-48 hours.

[0023] Figure 7 This is a diagram showing the phosphorus removal effect of the phosphorus tailings in Example 5 after calcining at 950°C for 1 hour and then reacting in a phosphorus solution with a pH of 6 for 24 hours. DETAILED DESCRIPTION

[0024] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment. Example 1

[0025] 300 kg of representative phosphate tailings were collected from the phosphate tailings pond. The morphology of the phosphate tailings is shown in Figure 1 Its XRD pattern is shown in Figure 2, the main mineral composition of the phosphate tailings was analyzed as follows: dolomite accounted for about 80%, collophanite accounted for about 15%, clay minerals accounted for about 5%, tailings fineness 200 mesh accounted for about 95%, pH 8.3-8.6, the phosphate tailings were crushed through a 200 mesh sieve and placed in a muffle furnace for calcination at 500-1050℃ for 2h, 0.2g of the calcined phosphate tailings was weighed and added to simulated phosphorus-containing water with a pH of 6 prepared with KH2PO4, and placed in a shaking table at a temperature of 37℃ and a speed of 200r / min for 40min. The results showed that the adsorption capacity of the phosphate tailings was the largest when the calcination temperature was 950℃, and the adsorption amount was 81.29 mg / g ( Figure 3 ). Example 2

[0026] This embodiment adopts the same phosphate tailings as in embodiment 1.

[0027] The phosphate tailings were crushed and passed through a 200-mesh sieve and placed in a muffle furnace for calcination at 950°C for 0.6-3h. 0.2g of the calcined phosphate tailings was weighed and added to simulated phosphorus-containing water with a pH of 6 prepared with KH2PO4. The phosphate tailings were placed in a shaking table at a temperature of 37°C and a speed of 200r / min for 40min. The results showed that the adsorption capacity of the phosphate tailings was the largest when the calcination time was 1h, and the adsorption amount was 87.48 mg / g ( Figure 4 ). Example 3

[0028] This embodiment adopts the same phosphate tailings as in embodiment 1.

[0029] The phosphate tailings were crushed and passed through a 200-mesh sieve and placed in a muffle furnace for calcination at 950°C for 1 hour. 0.2 g of the calcined phosphate tailings was weighed and added to simulated phosphorus-containing water with a pH of 4-9 prepared with KH2PO4. The phosphate tailings were placed in a shaking table at a temperature of 37°C and a speed of 200 r / min for 40 minutes. The results showed that the adsorption capacity of the phosphate tailings was the largest when the pH of the solution was 6, and the adsorption amount was 81.29 mg / g ( Figure 5 ). Example 4

[0030] This embodiment adopts the same phosphate tailings as in embodiment 1.

[0031] The phosphate tailings were crushed and passed through a 200-mesh sieve and placed in a muffle furnace for calcination at 950°C for 1 hour. 0.2 g of the calcined phosphate tailings was weighed and added to simulated phosphorus-containing water with a pH of 4-9 prepared with KH2PO4. The phosphate tailings were placed in a shaking table at a temperature of 37°C and a speed of 200 r / min for reaction for 0.7-48 hours. The results showed that the adsorption capacity of the phosphate tailings was the largest when the reaction time was 24 hours, and the adsorption amount was 112.41 mg / g ( Figure 6 ). Example 5

[0032] This embodiment adopts the same phosphate tailings as in embodiment 1.

[0033] The phosphate tailings are placed in a muffle furnace and calcined at 950°C for 1h, and the dolomite therein is completely decomposed into calcite (CaO) and periclase (MgO). The uncalcined phosphate tailings and the calcined phosphate tailings are mixed evenly in a mass ratio of 1:1 and then put into a round pot granulator and sprayed with water accounting for 30% of the mass of the powder, and then formed and consolidated into particles with a diameter of 3-5mm by the round pot granulator. Then age for 12h under saturated humidity and room temperature conditions, and then steam cure for 24h. The final ceramsite mud content cannot exceed 1%, that is, the target product is obtained. The modified phosphorus removal material based on phosphate tailings. The prepared modified phosphorus removal material is loaded into a plastic tube with a diameter of 3.6cm and a height of 30cm to form a water treatment filter column. The simulated phosphorus-containing water with a phosphorus concentration of 3mg / L prepared with potassium dihydrogen phosphate is operated according to a hydraulic retention time of 15min, and the phosphorus concentration is less than 0.2mg / L.

Claims

1. A method for preparing a modified phosphorus removal material based on phosphorus tailings, characterized in that: Step a), drying the phosphate tailings naturally, grinding them into 200 mesh (74 μm) and sieving them to obtain pretreated phosphate tailings; Step b), placing the pretreated phosphate tailings in a muffle furnace for calcination to obtain a modified phosphate tailings dephosphorization adsorbent; Step c), removing phosphorus from the obtained adsorbent under certain conditions; the phosphorus solution involved is prepared with KH2PO4 according to certain requirements; Step d), the uncalcined phosphate tailings and the calcined phosphate tailings are mixed evenly according to different mass ratios, and then formed and consolidated to obtain a granular material.

2. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: The main mineral components of the phosphate tailings are as follows: dolomite accounts for about 80%, collophanite accounts for about 15%, and clay minerals account for about 5%. The tailings fineness of 200 mesh accounts for about 95%, and the pH is 8.3-8.

6.

3. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: In the step a), the particle size of the phosphate tailings after crushing is less than 74 μm.

4. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: In the step b), the calcination temperature is 500-1050°C.

5. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: In the step c), the pH of the phosphorus solution before the reaction is 4-9.

6. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: In the step b), the calcination time at 950° C. is 0.6-3 h.

7. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: In the step c), the solution reaction time is 0.7-48h, the reaction temperature is 37°C, and the rotation speed is 200r / min.

8. The method for preparing a modified phosphorus removal material based on phosphorus tailings according to claim 1, characterized in that: In the step d), the uncalcined phosphate tailings and the calcined phosphate tailings are mixed evenly in a mass ratio of 1:9, 1:3, 1:1, 3:1, 9:1, and then put into a round pot granulator, and water accounting for 20-40% of the mass of the powder is added, and then the granular material is formed and consolidated by the round pot granulator; the obtained granular material is then aged for 12 hours under saturated humidity and room temperature conditions, and then cured with steam for 24 hours, and the final clay content of the ceramsite cannot exceed 1%, so that the target product, a modified phosphorus removal material based on phosphate tailings, is obtained.

9. An application method of the modified phosphorus removal material based on phosphate tailings according to any one of claims 1 to 8, characterized in that: The modified phosphorus removal material is placed in a laboratory constant temperature shaker for phosphorus removal.

10. An application method of the modified phosphorus removal material based on phosphorus tailings according to any one of claims 1 to 8, characterized in that: The modified phosphorus removal material is loaded into a water treatment column, a treatment pool, an artificial wetland, a farmland drainage ditch, or a permeable dam is constructed on the riverbed, and the water to be treated flows through the modified phosphorus removal material in a seepage manner. The modified phosphorus removal material acts as a reactive porous medium material to eliminate low-concentration phosphorus in the water, and the total phosphorus concentration of the effluent reaches the Class III surface water standard.

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