Ceramic filter material based on yellow river sediment and its preparation method

Abstract

This invention discloses a ceramic filter media based on Yellow River sediment. By mass percentage, the ceramic filter media comprises the following components: 66-82 wt% Yellow River sediment, 9-15 wt% high-alumina bauxite, 3-7 wt% iron oxide, and 6-12 wt% sodium-based bentonite; the mass ratio of SiO2, Al2O3, and Fe2O3 in the above system is 40-58:8-20:5-12. This application provides a high-value-added utilization method for Yellow River sediment, realizing the resource utilization of Yellow River sediment and solving the problem of Yellow River sediment disposal. The ceramic filter media prepared in this application has wide applications, including in wastewater treatment processes such as aerated biological filters and constructed wetlands. By utilizing solid waste to treat water pollution, it achieves "treating pollution with waste."

Description

Technical Field

[0001] This invention relates to the field of ceramsite and solid waste resource utilization, specifically a ceramsite filter material based on Yellow River sediment and its preparation method. Background Technology

[0002] Sediment possesses both hazardous and resource-related attributes. Its hazardous nature is a global problem, with an annual global sediment load reaching 20 billion tons. The increasing severity of floods and ecological degradation caused by sediment deposition is a growing concern worldwide. The Yellow River is China's second-longest river, approximately 5,464 kilometers long with a drainage area of ​​about 752,443 square kilometers. Because its middle reaches flow through the Loess Plateau, it carries a large amount of sediment, making it one of the world's most sediment-laden rivers. The Loess Plateau contributes up to 1.6 billion tons of sediment to the Yellow River annually. This massive sediment accumulation causes river channel blockage, riverbed elevation, and numerous environmental problems. Therefore, the rational utilization of Yellow River sediment resources is crucial and has become one of the important ways to solve the ecological and environmental problems of the Yellow River basin and achieve sustainable development.

[0003] The Yellow River sediment has a complex composition, containing a large amount of mud and impurities, making its direct utilization technically challenging. Currently, the resource utilization of Yellow River sediment mainly focuses on soil improvement, building material manufacturing, and ecological environment restoration, particularly in the construction industry. For example, patent CN200810014994.7 discloses a technology for producing non-fired bricks using Yellow River sediment, and patent CN201310563180.X discloses a technology for preparing autoclaved aerated concrete blocks using Yellow River sand and its preparation method. Although these resource utilization pathways for Yellow River sediment have brought considerable environmental, economic, and ecological benefits, the efficiency and scope of these technologies remain limited, failing to meet the demand for large-scale, efficient utilization of Yellow River sediment. Therefore, there is an urgent need to develop new pathways for the resource utilization of Yellow River sediment to enhance its conversion and utilization value.

[0004] Ceramic granule filter media for wastewater treatment is a porous spherical ceramic particle material. It has a rough surface, is lightweight, has high porosity, large specific surface area, and stable chemical properties. Compared with organic fillers, it has advantages such as strong biological adhesion, good biofilm formation, easy backwashing, and strong interception capacity. It is mainly used in wastewater and sewage treatment technologies such as aerated biological filters and constructed wetlands. Ceramic granule filter media is usually made from high-quality clay, clay, and solvents through grinding, screening, and calcination. With the continuous advancement of ecological construction, the raw materials for ceramsite filter media have shifted from shale and clay to solid wastes rich in silicon and aluminum, such as fly ash and coal gangue. Chinese authorized patent CN119488757A uses coal gangue as the main raw material and prepares ceramsite filter media products that meet the requirements of the standard "Artificial Ceramic Granule Filter Media for Water Treatment" (CJ / T299-2008) through grinding, mixing, granulation, and sintering processes. However, there are currently no methods or technologies for applying Yellow River sediment to ceramsite filter media.

[0005] In summary, there is an urgent need for a method to prepare ceramsite filter media based on Yellow River sediment in order to improve the utilization rate of Yellow River sediment and provide a new approach to water pollution control using solid waste. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a ceramic filter material based on Yellow River sediment and its preparation method, so as to expand the utilization of Yellow River sediment, achieve the purpose of "treating pollution with waste", and prepare ceramic filter material that meets the regulations.

[0007] The objective of this invention is achieved through the following technical solution: On the one hand, a type of ceramsite filter media based on Yellow River sediment, wherein the ceramsite filter media comprises the following components by mass percentage: Yellow River sediment content: 66-82 wt% High-alumina bauxite 9~15 wt%; Iron oxide 3~7 wt% Sodium-based bentonite 6-12 wt% In the above system, the mass ratio of SiO2, Al2O3 and Fe2O3 is 40~58:8~20:5~12; Specifically, the Yellow River sediment comprises the following main components: SiO2 51.26~65.71 wt%, Al2O3 7.57~10.27 wt%, Fe2O3 4.98~7.58 wt%, Na2O 0.14~1.16 wt%, K2O 1.47~1.73 wt%, MgO 1.18~2.19 wt%, and CaO 7.43~9.27 wt%. Specifically, the loss on ignition of the Yellow River sediment is 3.56% to 7.47%; Preferably, the high-alumina bauxite has a particle size ≤150 μm; Preferably, the chemical composition of the high-alumina bauxite, by mass percentage, includes: SiO2 5~15 wt%, Al2O3 70~90 wt%, Fe2O3 <3 wt%; Preferably, the high-alumina bauxite includes at least one of the following: extra-grade high-alumina bauxite, first-grade high-alumina bauxite, and second-grade high-alumina bauxite. Preferably, the iron oxide particle size is ≤150 μm; Preferably, the chemical composition of the iron oxide includes Fe2O3 ≥99.5% wt by mass percentage.

[0008] Preferably, the sodium-based bentonite has a thickness of ≤150 μm; Preferably, the chemical composition of the sodium-based bentonite includes, by mass percentage, 60-75 wt% SiO2 and 12-20 wt% Al2O3. On the other hand, a method for preparing filter media based on Yellow River sediment ceramsite includes the following steps: S1. The Yellow River silt is dried, crushed and sieved for the first time to obtain Yellow River silt powder; S2. Mix the Yellow River silt powder with the high-alumina bauxite, the iron oxide, and the sodium-based bentonite in a certain proportion to obtain a mixture; S3. Add the mixture to a granulator, spray water mist to granulate, and obtain pellets; The pellets are sieved and dried a second time to obtain spherical ceramsite raw material; S4. The spherical ceramsite raw material is placed in a high-temperature box furnace for programmed heating and firing, and then cooled to obtain ceramsite filter media; Specifically, in S1, the instrument used for the first drying is a blower-type drying oven, the first drying temperature is 100~105℃, and the first drying time is 4 h; the sieving uses a standard square hole sieve with a pore size of 150 μm, and the undersize portion is taken.

[0009] Specifically, in S3, the granulator includes a disc granulator with an inclination angle of 40~50°; The initial rotation speed of the granulator is 50~60 r / min. After the granulator produces 2 mm pellets, the rotation speed of the granulator is adjusted to 90~110 r / min to continue granulation. The amount of mist water used is 15-25 wt% of the mass of the mixture; The second drying temperature is 100~105℃, and the second drying time is 4 h; the particle size of the spherical ceramsite raw material is 5~10 mm.

[0010] Specifically, in S4, the temperature rise rate of the programmed heating system is 5 ℃ / min, raising the temperature from room temperature to a preheating temperature of 500 ℃; after holding at this temperature for 10 min, the temperature continues to rise at a rate of 5 ℃ / min to a calcination temperature of 1090~1190 ℃, and is held at this temperature for 30~60 min; the cooling is carried out in the furnace and cooled to room temperature.

[0011] The beneficial effects of this invention are: (1) This invention utilizes Yellow River sediment as raw material for ceramsite filter media to realize the resource utilization of Yellow River sediment and solve the problem of Yellow River sediment disposal. (2) The ceramic filter media prepared by the present invention can be applied to sewage and wastewater treatment technologies such as aerated biological filters and constructed wetlands, achieving the effect of treating water pollution with solid waste and realizing the purpose of "treating pollution with waste"; (3) The preparation process of this invention is scientific and reasonable, the processing steps are simple and easy to implement, the cost is relatively low, and it can achieve large-scale production and generate economic benefits. Attached Figure Description

[0012] Figure 1 This is a process flow diagram of the preparation method of ceramsite filter media based on Yellow River sediment in this application. Detailed Implementation

[0013] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the following description.

[0014] According to the standard for artificial ceramsite filter media for water treatment (CJ / T 299-2008), the performance requirements for water treatment ceramsite are: porosity ≥ 40% and specific surface area ≥ 0.5 × 10⁻⁶. 4 cm 2 / g, mud content ≤1%, hydrochloric acid solubility ≤2%, and the sum of breakage rate and wear rate ≤6%.

[0015] The Yellow River sediment used in the following examples and comparative examples was selected from the Puyang section. The main components of the Yellow River sediment are shown in Table 1.

[0016] Table 1. Main chemical composition of Yellow River sediment Example 1 A type of ceramsite filter media based on Yellow River silt, the ceramsite filter media is prepared from the following raw materials in weight percentage: 73 wt% Yellow River silt, 12 wt% high-alumina bauxite, 5 wt% iron oxide, and 10 wt% sodium-based bentonite.

[0017] Premium high-alumina bauxite, produced by Gongyi Borun Refractory Materials Co., Ltd. Premium high-alumina bauxite particle size ≤150 μm. The chemical composition of premium high-alumina bauxite by mass percentage is as follows: 5.23 wt% SiO2, 82.07 wt% Al2O3, 2.05 wt% Fe2O3, and other unavoidable impurities.

[0018] Iron oxide, Henan Huamei Chengde Pigment Co., Ltd., iron oxide particle size ≤150 μm, the chemical composition of iron oxide by mass percentage is as follows: 99.53% wt% Fe2O3, other unavoidable impurities.

[0019] Sodium-based bentonite, Yueqing Xibian Automation Co., Ltd., sodium-based bentonite particle size ≤150 μm; the chemical composition of sodium-based bentonite by mass percentage is as follows: 19.45 wt% SiO2, 62.10 wt% Al2O3, and other unavoidable impurities.

[0020] A method for preparing ceramsite filter media based on Yellow River sediment includes the following steps: S1. Dry the Yellow River sediment in a forced-air drying oven at 100~105℃ for 4 h, then pulverize it through a 150 μm standard square hole sieve to obtain Yellow River sediment powder. S2. Mix the Yellow River silt powder with high-alumina bauxite, iron oxide and sodium bentonite according to the mass ratio to obtain a mixture. S3. Add the mixture to the disc granulator and spray 20 wt% of the mixture with atomized water for granulation. The disc granulator is tilted at 40-50° and the initial speed is 50-60 r / min. After obtaining 2 mm balls in the granulator, adjust the speed to 90-110 r / min and continue granulation. After granulation, sieve to obtain 5-10 mm balls and place them in a forced-air drying oven at 100-105℃ for 4 h to obtain spherical ceramsite raw material. S4. Place the spherical ceramsite raw material into a high-temperature box furnace for programmed heating and firing at a rate of 5℃ / min, from room temperature to a preheating temperature of 500℃, hold for 10 min, and then continue heating at a rate of 5℃ / min to a calcination temperature of 1140℃, hold for 40 min. After firing, cool to room temperature with the furnace to obtain ceramsite filter material.

[0021] Example 2 The difference from Example 1 is that the mass percentages of Yellow River silt, high-alumina bauxite, iron oxide, and sodium-based bentonite in the ceramsite filter material are 68 wt%, 14 wt%, 7 wt%, and 11 wt%, respectively, while the other steps and conditions are the same as in Example 1.

[0022] Example 3 The difference from Example 1 is that the mass percentages of Yellow River silt, high-alumina bauxite, iron oxide, and sodium-based bentonite in the ceramsite filter material are 80 wt%, 10 wt%, 4 wt%, and 6 wt%, respectively, while the other steps and conditions are the same as in Example 1.

[0023] Example 4 The difference from Example 1 is that when the ceramsite filter material is subjected to programmed heating and firing, the firing temperature is 1100℃, and the other steps and conditions are the same as in Example 1.

[0024] Example 5 The difference from Example 1 is that when the ceramsite filter material is subjected to programmed heating and firing, the firing temperature is 1180℃, and the other steps and conditions are the same as in Example 1.

[0025] Example 6 The difference from Example 1 is that when the ceramsite filter material is subjected to programmed heating and firing, the firing and holding time is 30 ℃, and the other steps and conditions are the same as in Example 1.

[0026] Example 7 The difference from Example 1 is that when the ceramsite filter material is subjected to programmed heating and firing, the firing and holding time is 60°C, and the other steps and conditions are the same as in Example 1.

[0027] Comparative Example 1 The difference from Example 1 is that the mass percentages of Yellow River silt, high-alumina bauxite, iron oxide, and sodium-based bentonite in the ceramsite filter material are 81 wt%, 4 wt%, 5 wt%, and 10 wt%, respectively, while the other steps and conditions are the same as in Example 1.

[0028] Comparative Example 2 The difference from Example 1 is that the mass percentages of Yellow River silt, high-alumina bauxite, iron oxide, and sodium-based bentonite in the raw material of the ceramsite filter media are 78 wt%, 12 wt%, 0 wt%, and 10 wt%, respectively, while the other steps and conditions are the same as in Example 1.

[0029] Comparative Example 3 The difference from Example 1 is that the mass percentages of Yellow River silt, high-alumina bauxite, iron oxide, and sodium-based bentonite in the raw material of the ceramsite filter media are 73 wt%, 12 wt%, 5 wt%, and 0 wt%, respectively, while the other steps and conditions are the same as in Example 1.

[0030] Comparative Example 4 The difference from Example 1 is that when the ceramsite filter material is subjected to programmed heating and firing, the firing temperature is 1050 ℃, and the other steps and conditions are the same as in Example 1.

[0031] Comparative Example 5 The difference from Example 1 is that when the ceramsite filter material is subjected to programmed heating and firing, the firing and holding time is 90 ℃, and the other steps and conditions are the same as in Example 1.

[0032] According to the standard for artificial ceramsite filter media for water treatment (CJ / T 299-2008), six indicators of the ceramsite filter media obtained in Examples 1-7 and Comparative Examples 1-5 were tested, namely porosity, specific surface area, mud content, hydrochloric acid solubility, and the sum of breakage rate and wear rate. The results are shown in Table 2.

[0033] Table 2 Performance test parameters of ceramsite filter media in Examples 1-7 and Comparative Examples 1-5 As shown in Table 2, when the raw materials are proportioned as follows (66~82):(9~15):(3~7):(6~12) of Yellow River silt, high-alumina bauxite, iron oxide, and sodium-based bentonite, and then fired at 1090~1190 ℃ for 30~60 min, ceramic filter media products that meet and exceed the requirements of the standard "Artificial Ceramic Filter Media for Water Treatment" (CJ / T299-2008) can be prepared. As shown in Examples 1~3 and Comparative Examples 1 and 2 in Table 2, the abundant Al2O3 in the high-alumina bauxite is the skeletal component for forming ceramic filter media. During the high-temperature firing process, it reacts with SiO2 to form crystalline minerals such as mullite. This ensures sufficient strength of the ceramic filter media, thereby reducing the sum of breakage and wear rates. Furthermore, its hard outer surface can encapsulate the gas released from the interior of the ceramic particles, thus promoting the formation of a porous structure. The full reaction of iron oxide with carbon inside the raw material to release gas is also the basis for the high specific surface area of ​​ceramsite. Increasing the amount of high-alumina bauxite and iron oxide within a reasonable range can improve the performance of ceramsite filter media. As can be seen from Examples 1-3 and Comparative Example 3, ceramsite filter media prepared without the addition of sodium-based bentonite has a smaller porosity, higher mud content, and a greater sum of breakage rate and wear rate than the standard requirements. This indicates that sodium-based bentonite plays a key role in the preparation of ceramsite in forming uniform pores, reducing impurity content, and improving mechanical strength. This application can effectively improve the pore structure, reduce mud content, and significantly reduce the sum of breakage rate and wear rate by adding an appropriate amount of sodium-based bentonite, thus meeting industry standards. As can be seen from Examples 1, 4-7, Comparative Examples 4 and 5 in Table 2, the calcination temperature and holding time during the firing process of ceramsite filter media are key parameters affecting the performance of ceramsite filter media. At lower calcination temperatures, ceramsite may be incompletely calcined or even under-calcined, resulting in decreased strength. The main issue with ceramsite filter media is that the sum of breakage and wear rates falls short of standards. Extended holding time leads to the liquid phase produced at high temperatures filling the internal pores of the ceramsite, causing shrinkage and even adhesion and melting of the ceramsite. This results in a decrease in the specific surface area of ​​the ceramsite filter media.

[0034] Example 8 The ceramsite filter media based on Yellow River sediment prepared in Example 1, with a particle size of 5-10 mm, was used. The experimental setup consisted of an upflow aerated biological filter column made of plexiglass, with an inner diameter of 100 mm and a height of 2.0 m. A uniform water and air distribution system was installed at the bottom. The filter column was filled from bottom to top with a support layer containing pebbles with a particle size of 10-20 mm. The main filter media layer used the ceramsite filter media prepared in Example 1, with a filling height of approximately 1.2 m. The experimental water was artificially prepared simulated domestic sewage. Before treatment, the relevant indicators of the sewage were: Chemical Oxygen Demand (COD) 348.18 mg / L, Ammonia Nitrogen 28.48 mg / L, Total Phosphorus 7.69 mg / L, and Suspended Solids 78.76 mg / L. After purification treatment with the ceramsite filter media prepared in Example 1, the changes in the relevant water indicators were: COD 46.15 mg / L, and Ammonia Nitrogen 5.28 mg / L. The total phosphorus content in the water was 3.21 mg / L, and the suspended solids content was 38.52 mg / L. Experimental data show that using the ceramsite filter media prepared in Example 1 as the main filter medium, the chemical oxygen demand (COD) removal rate of the treated wastewater reached 86.7%, and the ammonia nitrogen removal rate reached 81.5%, indicating that the ceramsite filter media has good biofilm formation performance and the ability to degrade organic matter and ammonia nitrogen. The total phosphorus and suspended solids removal rates were 58.3% and 51.1%, respectively, reflecting that the filter media has a certain physical interception and adsorption effect. The above description is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the forms disclosed herein and should not be considered as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be modified within the scope of the concept described herein through the above teachings or related field techniques or knowledge. Modifications and changes made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A type of ceramsite filter media based on Yellow River silt, characterized in that: The ceramsite filter media comprises the following components by weight percentage: Yellow River sediment content: 66-82 wt% High-alumina bauxite 9~15 wt%; Iron oxide 3~7 wt% Sodium-based bentonite 6-12 wt% The mass ratio of SiO2, Al2O3 and Fe2O3 in the above system is 40~58:8~20:5~12.

2. The ceramsite filter media according to claim 1, characterized in that: The Yellow River sediment comprises the following main components: SiO2 51.26~65.71 wt%, Al2O3 7.57~10.27 wt%, Fe2O3 4.98~7.58 wt%, Na2O 0.14~1.16 wt%, K2O 1.47~1.73 wt%, MgO 1.18~2.19 wt%, and CaO 7.43~9.27 wt%. The loss on ignition of the Yellow River sediment was 3.56% to 7.47%.

3. The ceramsite filter media according to claim 1, characterized in that: The high-alumina bauxite has a particle size ≤150 μm; The chemical composition of the high-alumina bauxite, by mass percentage, includes: SiO2 5~15 wt%, Al2O3 70~90 wt%, Fe2O3 <3 wt%.

4. The ceramsite filter media according to claim 1, characterized in that: The high-alumina bauxite includes extra-grade high-alumina bauxite, grade 1 high-alumina bauxite, and grade 2 high-alumina bauxite.

5. The ceramsite filter media according to claim 1, characterized in that: The iron oxide particle size is ≤150 μm; The chemical composition of the iron oxide includes Fe2O3 ≥99.5% wt by mass percentage.

6. The ceramsite filter media according to claim 1, characterized in that: The sodium-based bentonite is ≤150 μm; The chemical composition of the sodium-based bentonite includes, by mass percentage, 60-75 wt% SiO2 and 12-20 wt% Al2O3.

7. The method for preparing ceramsite filter media according to any one of claims 1 to 6, characterized in that, Includes the following steps: S1. The Yellow River silt is dried, crushed and sieved for the first time to obtain Yellow River silt powder; S2. Mix the Yellow River silt powder with the high-alumina bauxite, the iron oxide, and the sodium-based bentonite in a certain proportion to obtain a mixture; S3. Add the mixture to a granulator, spray water mist to granulate, and obtain pellets; sieve the pellets and dry them a second time to obtain spherical ceramsite raw material; S4. The spherical ceramsite raw material is placed in a high-temperature box furnace for programmed heating and firing, and then cooled to obtain ceramsite filter media.

8. The preparation method according to claim 7, characterized in that: In S1, the instrument used for the first drying is a blower-type drying oven, the temperature of the first drying is 100~105℃, and the time of the first drying is 4 hours. The sieving process uses a standard square-hole sieve with a pore size of 150 μm, and the undersize portion is collected.

9. The preparation method according to claim 7, characterized in that: In S3, the granulator includes a disc granulator with an inclination angle of 40~50°; The initial rotation speed of the granulator is 50~60 r / min. After the granulator produces 2 mm pellets, the rotation speed of the granulator is adjusted to 90~110 r / min to continue granulation. The amount of mist water used is 15-25 wt% of the mass of the mixture; The second drying temperature is 100~105℃, and the second drying time is 4 h; the particle size of the spherical ceramsite raw material is 5~10 mm.

10. The preparation method according to claim 7, characterized in that: In S4, the temperature rise rate of the programmed heating system is 5 ℃ / min, raising the temperature from room temperature to a preheating temperature of 500 ℃; after holding at this temperature for 10 min, the temperature continues to rise at a rate of 5 ℃ / min to a calcination temperature of 1090~1190 ℃, and is held at this temperature for 30~60 min; the cooling is carried out in the furnace and cooled to room temperature.

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