Phosphorus removal filter material, and preparation method and application thereof

Abstract

The application belongs to the technical field of filter materials, and particularly relates to a phosphorus removal filter material and a preparation method and application thereof. The phosphorus removal filter material comprises an inner core sphere and a shell layer coated on the surface of the inner core sphere. Raw materials for preparing the inner core sphere include the following materials with mass percentages: 70-80% stone tailings, 10-15% inorganic calcareous material, and 5-15% fly ash. Raw materials for preparing the shell layer include the following materials with mass percentages: 60-65% stone tailings, 15-25% inorganic calcareous material, and 10-20% steel slag ash. The phosphorus removal filter material can slowly release calcium ions and hydroxyl ions, and can form microsuspensions in a weak alkaline environment, combine with phosphorus to generate harmless phosphate, and be adsorbed on the surface of the filter material, so as to effectively remove phosphorus in wastewater. Aluminum ions contained in the steel slag ash in the shell layer of the phosphorus removal filter material have flocculation effect, and can accelerate the fixation of phosphorus in phosphorus-containing wastewater.

Description

Technical Field

[0001] This invention belongs to the field of pollutant treatment technology, specifically relating to a phosphorus removal filter material, its preparation method, and its application. Background Technology

[0002] Stone is widely used as a building decoration material in interior and exterior decoration design, curtain wall decoration, and public facility construction. With the continuous development of the stone processing industry, the problem of dust and waste generated during processing has become increasingly prominent. As a resource-processing industry, about half of the raw materials used in stone processing become waste, of which a large amount of waste stone powder slurry is stone tailings. The dumping of stone tailings not only occupies land but also causes significant soil compaction and water quality deterioration, seriously affecting the ecological environment and residents' health. How to dispose of and rationally utilize stone tailings, improve the utilization rate of stone resources, and achieve the recycling of waste resources has become an urgent technical problem to be solved.

[0003] Currently, the main way to utilize stone tailings is to process them into building materials such as sintered bricks, artificial stone, concrete, and special mortars. However, the sintering process in this resource utilization is complex, energy-intensive, and has low added value, making it difficult to achieve large-scale production and promotion. Summary of the Invention

[0004] In view of this, the present invention provides a phosphorus removal filter material, its preparation method and application. The phosphorus removal filter material prepared by the present invention using stone tailings as raw material can significantly remove phosphorus from wastewater, achieving the purpose of treating waste with waste.

[0005] To solve the above-mentioned technical problems, the present invention provides a phosphorus removal filter material, comprising a core sphere and a shell layer covering the surface of the core sphere;

[0006] The raw materials for preparing the core spheres include the following materials in weight percentage:

[0007] Stone tailings account for 70-80%;

[0008] Inorganic calcium materials: 10-15%;

[0009] 5-15% fly ash;

[0010] The raw materials for preparing the shell layer include the following materials in weight percentage:

[0011] Stone tailings 60-65%;

[0012] Inorganic calcium materials: 15-25%;

[0013] Steel slag ash: 10-20%.

[0014] Preferably, the average particle size of the core spheres is 3 to 6 mm.

[0015] Preferably, the thickness of the shell layer is 0.2 to 0.5 mm.

[0016] Preferably, the bulk density of the phosphorus removal filter media is 0.9–1.3 g / cm³. 3 ;

[0017] The specific surface area of ​​the phosphorus removal filter media is 0.9–12 m². 2 / g;

[0018] The compressive strength of the phosphorus removal filter media is 12-15 MPa.

[0019] Preferably, the inorganic calcareous material used to prepare the core sphere and the inorganic calcareous material used to prepare the shell sphere independently include silicate cement, clinker, or white clay slag;

[0020] The stone tailings used to prepare the core sphere and the stone tailings used to prepare the shell layer each have the following characteristic parameters: water content of 20-30 wt%, fineness of less than 10% residue on a 200-mesh sieve, silica mass percentage greater than or equal to 30%, calcium oxide mass percentage greater than or equal to 20%, and alumina mass percentage greater than or equal to 10%.

[0021] The present invention also provides a method for preparing the phosphorus removal filter material described in the above technical solution, comprising the following steps:

[0022] Stone tailings, inorganic calcareous materials and fly ash are mixed to obtain core ball mixture;

[0023] The core sphere mixture is granulated to obtain core spheres;

[0024] Stone tailings, inorganic calcareous materials and steel slag ash are mixed to obtain a shell mixture.

[0025] The core spheres are coated with the shell mixture to obtain the phosphorus removal filter material.

[0026] Preferably, the coating process further includes: allowing the coated product to rest and then subjecting it to autoclaving to obtain the phosphorus removal filter material.

[0027] Preferably, the resting process involves placing the coated product in the air for 10 to 15 hours.

[0028] Preferably, the autoclaving treatment is performed at a temperature of 180–200°C, a pressure of 1.0–1.2 MPa, and a time of 7–10 h.

[0029] The present invention also provides the application of the phosphorus removal filter material described in the above technical solution or the phosphorus removal filter material prepared by the preparation method described in the above technical solution in the treatment of phosphorus-containing wastewater.

[0030] This invention provides a phosphorus removal filter media, comprising a core sphere and a shell layer covering the surface of the core sphere; the raw materials for preparing the core sphere include the following materials in weight percentage: 70-80% stone tailings, 10-15% inorganic calcareous materials, and 5-15% fly ash; the raw materials for preparing the shell layer include the following materials in weight percentage: 60-65% stone tailings, 15-25% inorganic calcareous materials, and 10-20% steel slag ash. The phosphorus removal filter material prepared by this invention using stone tailings as raw material contains numerous micro- and nano-pores, and also possesses a large specific surface area and high strength, making it suitable for adsorbing phosphorus from phosphorus-containing wastewater. After hydration and steam pressing, the phosphorus removal filter material provided by this invention can form tobermorite crystals, which readily form chelates with phosphate substances. This filter material can also slowly release calcium and hydroxide ions, forming tiny suspended solids in a weakly alkaline environment. These solids fully combine with phosphorus in the wastewater to generate harmless phosphates, which are then adsorbed onto the filter material surface, effectively removing phosphorus from the wastewater. Furthermore, the aluminum ions contained in the steel slag ash in the shell layer of the phosphorus removal filter material have a flocculation effect, accelerating the fixation of phosphorus in phosphorus-containing wastewater. Attached Figure Description

[0031] Figure 1 This is a SEM image of the phosphorus removal filter media prepared in Example 1. Detailed Implementation

[0032] The present invention provides a phosphorus removal filter material, comprising a core sphere and a shell layer covering the surface of the core sphere;

[0033] The raw materials for preparing the core spheres include the following materials in weight percentage:

[0034] Stone tailings account for 70-80%;

[0035] Inorganic calcium materials: 10-15%;

[0036] 5-15% fly ash;

[0037] The raw materials for preparing the shell layer include the following materials in weight percentage:

[0038] Stone tailings 60-65%;

[0039] Inorganic calcium materials: 15-25%;

[0040] Steel slag ash: 10-20%.

[0041] In this invention, the average particle size of the core spheres is preferably 3 to 6 mm, more preferably 4 to 5 mm.

[0042] In this invention, the raw material for preparing the core sphere comprises 70-80% stone tailings, preferably 75-80%, by mass percentage. In this invention, the water content of the stone tailings is preferably 20-30 wt%, more preferably 23-25 ​​wt%; the fineness of the stone tailings is preferably less than 10% residue on a 200-mesh sieve, more preferably 5-8% residue on a 200-mesh sieve; the mass percentage of silicon dioxide in the stone tailings is preferably greater than or equal to 30%, more preferably 36-40%; the mass percentage of calcium oxide in the stone tailings is preferably greater than or equal to 20%, more preferably 23-25%; and the mass percentage of alumina in the stone tailings is preferably greater than or equal to 10%, more preferably 13-15%.

[0043] In this invention, the raw materials for preparing the core spheres comprise 10-15% inorganic calcareous material, preferably 12-14%, by mass percentage. In this invention, the inorganic calcareous material preferably includes silicate cement, clinker, or white clay residue, more preferably silicate cement.

[0044] In this invention, the raw material for preparing the core spheres comprises 5-15% fly ash, preferably 10-15%, by mass percentage. In this invention, the fly ash preferably has a residue of less than 10% on a 200-mesh sieve, more preferably 5-8%.

[0045] In this invention, the thickness of the shell layer is preferably 0.2 to 0.5 mm, more preferably 0.3 to 0.4 mm.

[0046] In this invention, the raw material for preparing the shell layer comprises 60-65% stone tailings, preferably 62-64%, by weight percentage. Preferably, the stone tailings used for preparing the shell layer are the same as those used for preparing the core sphere.

[0047] In this invention, the raw material for preparing the shell comprises 15-25% inorganic calcium material, preferably 15-20%, by mass percentage. In this invention, the inorganic calcium material used to prepare the shell is preferably the same as the inorganic calcium material used to prepare the core sphere.

[0048] In this invention, the raw material for preparing the shell layer comprises 10-20% steel slag ash, preferably 15-20%, by mass percentage. In this invention, the fineness of the steel slag ash is preferably less than 10% residue on a 200-mesh sieve, more preferably 5-8% residue on a 200-mesh sieve.

[0049] In this invention, the bulk density of the phosphorus removal filter material is preferably 0.9–1.3 g / cm³. 3 More preferably, it is 0.9–1.1 g / cm³.3 In this invention, the specific surface area of ​​the phosphorus removal filter material is preferably 0.9–12 m². 2 / g, more preferably 10-11m 2 / g. In this invention, the compressive strength of the phosphorus removal filter material is preferably 12-15 MPa, more preferably 13-14 MPa.

[0050] The phosphorus removal filter material provided by this invention has a nanoscale network structure inside, which has extremely strong adsorption properties.

[0051] The present invention also provides a method for preparing the phosphorus removal filter material described in the above technical solution, comprising the following steps:

[0052] Stone tailings, inorganic calcareous materials and fly ash are mixed to obtain core ball mixture;

[0053] The core sphere mixture is granulated to obtain core spheres;

[0054] Stone tailings, inorganic calcareous materials and steel slag ash are mixed to obtain a shell mixture.

[0055] The core spheres are coated with the shell mixture to obtain the phosphorus removal filter material.

[0056] This invention mixes stone tailings, inorganic calcareous materials, and fly ash to obtain a core sphere mixture. This invention does not have special requirements for the mixing process, as long as it achieves uniform mixing.

[0057] After obtaining the core sphere mixture, the present invention granulates the core sphere mixture to obtain core spheres. In the present invention, the granulation is preferably carried out in a disc granulator, the angle of the granulating disc of the disc granulator is preferably 30-60°, more preferably 40-50°; the rotational speed of the disc granulator is preferably 10-12 r / min, more preferably 10-11 r / min.

[0058] This invention mixes stone tailings, inorganic calcareous materials, and steel slag ash to obtain a shell mixture. This invention has no special requirements for the mixing process, as long as it achieves uniform mixing.

[0059] After obtaining the shell-layer mixture, the present invention uses the shell-layer mixture to coat the core spheres to obtain the phosphorus removal filter media. In the present invention, the coating is preferably performed in a coating machine. The present invention has no special requirements for the coating; conventional methods in the art can be used.

[0060] The present invention can significantly improve the mechanical strength of the phosphorus removal filter material by coating the surface of the core sphere with a shell layer (40-50% higher than before coating), thereby preventing the core sphere from pulverizing and extending its service life.

[0061] In this invention, the coating process preferably further includes: allowing the coated product to stand still before subjecting it to autoclaving to obtain the phosphorus removal filter material. In this invention, the standing still process involves placing the coated product in air to stand; the standing time is preferably 10–14 hours, more preferably 12 hours.

[0062] In this invention, the temperature of the autoclaving treatment is preferably 180-200°C, more preferably 180-190°C; the pressure of the autoclaving treatment is preferably 1.0-1.2 MPa, more preferably 1.0-1.1 MPa; and the time of the autoclaving treatment is preferably 7-10 h, more preferably 8-9 h.

[0063] In this invention, the autoclaving treatment is preferably carried out in an autoclave. The autoclaving treatment allows the material to form a tobermorite phase, and phosphorus forms a chelate with the tobermorite, thereby reducing the phosphorus content of the wastewater.

[0064] This invention also provides the application of the phosphorus removal filter material described in the above-described technical solutions or the phosphorus removal filter material prepared by the preparation method described in the above-described technical solutions in the treatment of phosphorus-containing wastewater. In this invention, the phosphorus-containing wastewater preferably includes agricultural wastewater, lake water, river water, sewage treatment plant wastewater, farmland wastewater, or aquaculture wastewater; the phosphorus content in the phosphorus-containing wastewater is preferably 0.2–12 mg / L, more preferably 0.2–5 mg / L.

[0065] The phosphorus removal filter material provided by this invention has a core-shell structure and good stability and adsorption performance. It has excellent phosphorus removal ability in wastewater, especially low-phosphorus wastewater.

[0066] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0067] Example 1

[0068] By mass percentage, 70% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 15% silicate cement, and 15% fly ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the core sphere mixture.

[0069] The core sphere mixture is fed into a disc granulator and granulated under the conditions of a 45° disc angle and a rotation speed of 11 r / min to obtain core spheres with a particle size of 3-6 mm.

[0070] By mass percentage, 60% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 20% silicate cement, and 20% steel slag ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the shell mixture.

[0071] The core spheres and shell mixture are transported to a coating machine for coating. The coated product is then placed in a curing chamber for natural curing for 12 hours, and then placed in an autoclave at a steam temperature of 180℃ and a pressure of 1.1MPa for 8 hours to obtain a phosphorus removal filter material with a shell thickness of 0.2-0.5mm.

[0072] Example 2

[0073] By mass percentage, 75% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 15% silicate cement, and 10% fly ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the core sphere mixture.

[0074] The core sphere mixture is fed into a disc granulator and granulated under the conditions of a 45° disc angle and a rotation speed of 11 r / min to obtain core spheres with a particle size of 3-6 mm.

[0075] By mass percentage, 65% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 15% silicate cement, and 20% steel slag ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the shell mixture.

[0076] The core spheres and shell mixture are transported to a coating machine for coating. The coated product is then placed in a curing chamber for natural curing for 12 hours, and then placed in an autoclave at a steam temperature of 180℃ and a pressure of 1.1MPa for 8 hours to obtain a phosphorus removal filter material with a shell thickness of 0.2-0.5mm.

[0077] Example 3

[0078] By mass percentage, 80% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 10% silicate cement, and 10% fly ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the core sphere mixture.

[0079] The core sphere mixture is fed into a disc granulator and granulated under the conditions of a 45° disc angle and a rotation speed of 11 r / min to obtain core spheres with a particle size of 3-6 mm.

[0080] By mass percentage, 65% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 20% silicate cement, and 15% steel slag ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the shell mixture.

[0081] The core spheres and shell mixture are transported to a coating machine for coating. The coated product is then placed in a curing chamber for natural curing for 12 hours, and then placed in an autoclave at a steam temperature of 180℃ and a pressure of 1.1MPa for 8 hours to obtain a phosphorus removal filter material with a shell thickness of 0.2-0.5mm.

[0082] Example 4

[0083] By mass percentage, 80% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 10% silicate cement, and 10% fly ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the core sphere mixture.

[0084] The core sphere mixture is fed into a disc granulator and granulated under the conditions of a 45° disc angle and a rotation speed of 11 r / min to obtain core spheres with a particle size of 3-6 mm.

[0085] By mass percentage, 60% stone tailings (25% water content, 5% residue on a 200-mesh sieve, 36% silica, 23% calcium oxide, and 13% alumina), 20% silicate cement, and 20% steel slag ash (5% residue on a 200-mesh sieve) are uniformly mixed to obtain the shell mixture.

[0086] The core spheres and shell mixture are transported to a coating machine for coating. The coated product is then placed in a curing chamber for natural curing for 12 hours, and then placed in an autoclave at a steam temperature of 180℃ and a pressure of 1.1MPa for 8 hours to obtain a phosphorus removal filter material with a shell thickness of 0.2-0.5mm.

[0087] The phosphorus removal filter material prepared in Example 1 was examined by scanning electron microscopy, and the SEM image is shown below. Figure 1 As shown. By Figure 1 It can be seen that the phosphorus removal filter material provided by the present invention has a nanoscale network structure inside.

[0088] The bulk density, specific surface area, and cylinder compressive strength of the phosphorus removal filter media prepared in Examples 1 to 4 were determined according to GB / T 17431-2010 "Lightweight aggregates and their test methods Part 2: Lightweight aggregates test methods"; the phosphorus adsorption rate and adsorption capacity of the phosphorus removal filter media were determined by adsorption kinetics test, and the results are shown in Table 1.

[0089] Table 1 Performance parameters of the phosphorus removal filter media prepared in Examples 1-4

[0090]

[0091] As can be seen from Table 1, the phosphorus removal filter material provided by the present invention has a large specific surface area, high strength, and good phosphorus adsorption performance.

[0092] The phosphorus removal efficiency of the phosphorus removal filter media prepared in Example 1 and the commercially available traditional phosphorus removal filter media (fired ceramsite) in wastewater was tested using the following method. Specifically, the phosphorus removal filter media prepared in Example 1 and the commercially available traditional phosphorus removal filter media were respectively placed into two 40L laboratory tanks, A and B, with the filter media filling 60% of the tank volume. A wastewater sample collected from a wastewater treatment plant was injected into the test tanks; the total phosphorus content in the wastewater was 12 mg / L. The test tanks treated approximately 25L of wastewater per day for 14 consecutive days, and the phosphorus concentration in the water was measured daily. The results are shown in Table 2.

[0093] Table 2. Phosphorus removal efficiency of phosphorus removal filter media after different treatment times.

[0094]

[0095]

[0096] As shown in Table 2, the total phosphorus concentration in the test tank (tank A) for wastewater treatment using the phosphorus removal filter media provided by this invention was 0.13–0.35 mg / L. The phosphorus removal rate reached 97.08% on the first day of the experiment, and remained above 97% throughout the experiment. In contrast, the total phosphorus concentration in the test tank (tank B) for wastewater treatment using commercially available traditional phosphorus removal filter media was 2.8–4.3 mg / L, with a removal rate of 64.17–76.64% during the experiment. This demonstrates that the phosphorus removal filter media provided by this invention has a good removal effect on total phosphorus in wastewater, and its effect is significantly better than that of commercially available traditional phosphorus removal filter media.

[0097] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A phosphorus removal filter material, characterized in that, It includes a core sphere and a shell covering the surface of the core sphere; The raw materials for preparing the core spheres include the following materials in weight percentage: Stone tailings account for 70-80%; Inorganic calcium materials: 10-15%; fly ash 5-15%; The raw materials for preparing the shell layer include the following materials in weight percentage: Stone tailings 60-65%; Inorganic calcium materials: 15-20%; Steel slag ash 10~20%; The fly ash has a fineness of 5-8% residue on a 200-mesh sieve. The stone tailings used to prepare the core sphere and the stone tailings used to prepare the shell layer each have the following characteristic parameters: moisture content of 20-30 wt%, fineness of 5-8% residue on a 200-mesh sieve, and the stone tailings contain 36-40% silica, 23-25% calcium oxide, and 13-15% alumina by mass. The inorganic calcareous materials used to prepare the core sphere and the inorganic calcareous materials used to prepare the shell are independently silicate cement, clinker, or white clay slag. The fineness of the steel slag ash is 5-8% on a 200-mesh sieve.

2. The phosphorus removal filter material according to claim 1, characterized in that, The average particle size of the core spheres is 3-6 mm.

3. The phosphorus removal filter material according to claim 1, characterized in that, The thickness of the shell is 0.2~0.5 mm.

4. The phosphorus removal filter material according to any one of claims 1 to 3, characterized in that, The bulk density of the phosphorus removal filter media is 0.9~1.3 g / cm³. 3 ; The specific surface area of ​​the phosphorus removal filter media is 0.9~12 m². 2 / g; The compressive strength of the phosphorus removal filter media is 12~15 MPa.

5. The method for preparing the phosphorus removal filter material according to any one of claims 1 to 4, characterized in that, Includes the following steps: Stone tailings, inorganic calcareous materials and fly ash are mixed to obtain core ball mixture; The core sphere mixture is granulated to obtain core spheres; Stone tailings, inorganic calcareous materials and steel slag ash are mixed to obtain a shell mixture. The core spheres are coated with the shell mixture, and the coated product is then cured and subjected to autoclaving to obtain the phosphorus removal filter material.

6. The preparation method according to claim 5, characterized in that, The resting process involves placing the coated product in the air for 10-15 hours.

7. The preparation method according to claim 5, characterized in that, The autoclaving process is carried out at a temperature of 180~200℃, a pressure of 1.0~1.2 MPa, and a time of 7~10 h.

8. The application of the phosphorus removal filter material according to any one of claims 1 to 4 or the phosphorus removal filter material prepared by the preparation method according to any one of claims 5 to 7 in the treatment of phosphorus-containing wastewater.

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