Preparation method of an environment-friendly porous ceramic particle for treating acidic mine wastewater

Abstract

The invention discloses a method for preparing environmentally friendly porous ceramic particles for treating acid mine wastewater, and belongs to the technical field of wastewater treatment. The environmentally friendly porous ceramic particles are composed of an inner layer and an outer layer; the inner layer includes the following raw materials in mass percentage: 43-47% of biochar-loaded nano zero-valent iron material, 24-32% of clay, and 28-33% of water; the outer layer includes the following raw materials in mass percentage: 14-18% of excess sludge cracking ash, 22-25% of excess sludge, 13-15% of clay, 9-15% of lignin, and 28-33% of water. The porous ceramic particles with a double-layer structure prepared by the present invention not only improve the treatment effect of acid mine wastewater, but also make resource utilization of excess sludge solid waste, and have good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of wastewater treatment, and particularly to a preparation method of an environment-friendly porous ceramic particle for treating acidic mine wastewater. Background Art

[0002] With the increasing scale of sewage treatment, the output of municipal sludge has also increased correspondingly. The sludge problem has not been properly solved. Only a small part of the sludge in sewage treatment plants is subjected to stabilization treatment, land use, incineration, and building material utilization, etc., and most of the sludge has not been treated and disposed of standardized. Making high-value applications according to the characteristics of the substances rich in excess sludge to realize the resource utilization of sludge is the key goal of sludge disposal. Excess sludge is an organic solid waste with high water content and easy to corrupt. Improper treatment will cause secondary environmental pollution. Considering the specific properties of the sludge in sewage treatment plants, the dual attributes of "resource" and "pollution" of the sludge should be fully considered to maximize the environmental, economic, and social benefits.

[0003] Porous ceramic materials not only have the advantages of ordinary ceramic materials, but also compared with polymers or metals, ceramic materials have characteristics such as high hardness, high stability, thermal shock resistance, corrosion resistance, and wear resistance. Moreover, due to its uniform pore distribution, large porosity, small bulk density, and large specific surface area, etc., it is often used to remove heavy metal ions in the environmental protection field. And sludge contains about 20-30% of inorganic substances, including silicon, aluminum, iron, calcium, etc., which are similar to the raw materials of ceramic materials; the lignin molecular structure contains a variety of functional groups, and has a porous structure after combustion, which can provide more adsorption space for pollutants; biochar nano zero-valent iron has been widely used in the treatment of heavy metals in water due to its large specific surface area and dense reaction sites, and has good removal effects on many metal ions in water. Therefore, if excess sludge, lignin, and biochar nano zero-valent iron can be combined to make a porous ceramic material, the excess sludge can be effectively utilized to maximize the environmental, economic, and social benefits. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of an environment-friendly porous ceramic particle for treating acidic mine wastewater to solve the problems existing in the above-mentioned prior art. The porous ceramic particles prepared by the present invention have a double-layer structure. Lignin is added to the outer layer of the ceramsite, and during the sintering process, the ceramsite forms a porous structure with a relatively high porosity, providing more adsorption space for pollutants; and the difficult-to-treat pollutants can enter the inner layer through the pores in the outer layer of the ceramsite and react with the strongly reducing and highly reactive nano zero-valent iron, so that the pollutants can be removed more thoroughly. To achieve the above purpose, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention: An environmentally friendly porous ceramic particle for treating acidic mine wastewater, the porous ceramic particle is composed of an inner layer and an outer layer;

[0006] The inner layer comprises raw materials in the following mass percentages: 43-47% of biochar-supported nano zero-valent iron material, 24-32% of clay, and 28-33% of water;

[0007] The outer layer comprises raw materials in the following mass percentages: 14-18% of sludge cracking ash, 22-25% of sludge, 13-15% of clay, 9-15% of lignin, and 28-33% of water.

[0008] Furthermore, the sludge cracking ash is residual sludge cracking ash; the sludge is the surplus sludge of a municipal wastewater treatment plant.

[0009] Furthermore, the particle sizes of the solid raw materials of the outer layer are all 50-150 μm; the particle sizes of the solid raw materials of the inner layer are all 150-200 μm; the mass ratio of the inner layer to the outer layer is (0.8-1.2):1.

[0010] Two of the technical solutions of the present invention: A preparation method of the above-mentioned environmentally friendly porous ceramic particle, comprising the following steps:

[0011] (1) Weigh each raw material of the inner layer according to the mass percentage, mix them evenly, stir into a mud shape, then granulate, ripen, and dry to obtain inner layer particles;

[0012] (2) Weigh each raw material of the outer layer according to the mass percentage, mix them evenly, stir into a mud shape, then add the inner layer particles for coating to obtain green ceramsite, and finally ripen, dry, and calcine the green ceramsite to obtain the porous ceramic particle.

[0013] Furthermore, in step (1), the average particle size of the granulation is 3-8 mm;

[0014] Furthermore, in step (1), the ripening temperature is 20-27 °C, and the time is 12-24 h; the drying is natural air drying, and the time is 12 h.

[0015] Furthermore, in step (2), the average particle size of the green ceramsite is 4-12 mm.

[0016] Furthermore, in step (2), the ripening temperature is 20-27 °C, and the time is 12-24 h; the drying temperature is 90-130 °C, and the time is 2-4 h.

[0017] Further, in step (2), the calcination is specifically as follows: first, calcine at 200 - 280°C for 20 - 30 min, then raise the temperature to 400 - 550°C and calcine for 40 - 60 min, and finally raise the temperature to 750 - 1550°C and calcine for 60 - 180 min.

[0018] Further, in step (2), the calcination is carried out in a nitrogen atmosphere.

[0019] The third technical solution of the present invention: an application of the above-mentioned environment-friendly porous ceramic particles in water treatment.

[0020] The present invention discloses the following technical effects:

[0021] (1) The environment-friendly porous ceramic particles for treating acid mine wastewater of the present invention have a double-layer structure, good adsorption performance, large adsorption space, many adsorption sites, and low cost. While resourcefully utilizing the surplus sludge solid waste, the efficiency of wastewater treatment is improved, and it has good application prospects.

[0022] (2) By controlling the material parameters of the inner and outer layers, the present invention enables the porous ceramic to form a double-layer pore size distribution structure. The lignin in the outer layer of the ceramsite forms a porous structure with a higher porosity during the sintering process, providing more adsorption space for pollutants. And the pollutants that are difficult to treat can enter the inner layer through the pores in the outer layer of the ceramsite and react with the strongly reducing and highly reactive nano-zero-valent iron, so that the pollutants can be removed more thoroughly. It provides a method for the disposal and resource utilization of surplus sludge.

[0023] (3) The present invention uses the surplus sludge solid waste as the main material for preparing the ceramsite. The ceramsite has a double-layer structure. By adding lignin to the outer layer of the ceramsite, more adsorption space is provided for pollutants. The pollutants that are difficult to treat react with the strongly reducing nano-zero-valent iron in the inner layer through the pores in the outer layer of the ceramsite, so that the pollutants can be removed more thoroughly. While improving the treatment effect of acid mine wastewater, the double-layer structured ceramsite resourcefully utilizes the surplus sludge solid waste and has good application prospects. Specific embodiments

[0024] Now, various exemplary embodiments of the present invention will be described in detail. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, characteristics, and implementation schemes of the present invention.

[0025] It should be understood that the terms used in the present invention are only for describing specific embodiments and are not intended to limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range, as well as each smaller range between any other stated value or intermediate value within the stated range, is also included in the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0026] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0027] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and examples of this application are only exemplary.

[0028] Regarding the use of "comprising", "including", "having", "containing", etc. in this article, they are all open-ended terms, meaning including but not limited to.

[0029] All "parts" mentioned in the following examples are "parts by mass".

[0030] The biochar-supported nano-zero-valent iron material used in the following examples of the present invention was purchased online.

[0031] Example 1

[0032] A preparation method of an environmentally friendly porous ceramic particle for treating acid mine wastewater:

[0033] The environmentally friendly porous ceramic particle consists of two layers:

[0034] The inner layer is composed of the following raw materials by mass percentage: 43% of biochar-supported nano-zero-valent iron material, 27% of clay, and 30% of water; the average particle size of each raw material in the inner layer is 50 μm.

[0035] The outer layer is composed of the following raw materials by mass percentage: 14% of sludge pyrolysis ash, 25% of sludge, 13% of clay, 15% of lignin, and 33% of water; the average particle size of each raw material in the outer layer is 150 μm.

[0036] The mass ratio of the inner layer to the outer layer is 0.8:1.

[0037] The preparation method is as follows:

[0038] (1) Mix the inner layer raw materials evenly, stir until it becomes a mud-like state, then put it into a granulator for granulation to prepare particles with an average particle size of 5 mm. Finally, cure it in a space at 20 °C for 12 h, and then air-dry it naturally for 12 h to obtain inner layer particles.

[0039] (2) Mix the outer layer raw materials evenly, stir until it becomes a mud-like state, then add the inner layer particles and wrap the inner layer particles into particles with an average particle size of 10 mm for the whole particles to obtain the green ceramsite.

[0040] (3) Place the green ceramsite in a space at 20 °C for 12 h, then put it into a vacuum drying oven at 90 °C for 2 h to remove moisture and obtain the dried particles.

[0041] (4) First, calcine the dried particles at 200 °C for 20 min, then calcine them at 400 °C for 60 min, and finally calcine them at 750 °C for 180 min. After the calcination is completed, cool them to room temperature (the whole process from heating, calcination to cooling is carried out in a nitrogen atmosphere) to obtain porous ceramic particles.

[0042] Example 2

[0043] A preparation method of an environmentally friendly porous ceramic particle for treating acidic mine wastewater:

[0044] The environmentally friendly porous ceramic particle is composed of an inner layer and an outer layer:

[0045] The inner layer is composed of raw materials with the following mass percentages: 45% of biochar-supported nano-zero-valent iron material, 24% of clay, and 31% of water; the average particle size of each raw material in the inner layer is 100 μm.

[0046] The outer layer is composed of raw materials with the following mass percentages: 18% of sludge pyrolysis ash, 24% of sludge, 14% of clay, 12% of lignin, and 32% of water; the average particle size of each raw material in the outer layer is 180 μm.

[0047] The mass ratio of the inner layer to the outer layer is 1:1.

[0048] The preparation method is as follows:

[0049] (1) Mix the inner layer raw materials evenly, stir until it becomes a mud-like state, then put it into a granulator for granulation to prepare particles with an average particle size of 3 mm. Finally, cure it in a space at 25 °C for 18 h, and then air-dry it naturally for 12 h to obtain inner layer particles.

[0050] (2) Mix the outer layer raw materials evenly and stir until they become a mud-like state. Then add the inner layer particles and wrap the inner layer particles into integral particles with an average particle size of 5 mm to obtain the ceramsite raw material.

[0051] (3) Place the ceramsite raw material in a space at 25 °C for 18 h of curing, and then put it into a vacuum drying oven at 100 °C for 3 h of drying to remove moisture, obtaining the dried particles.

[0052] (4) First, calcine the dried particles at 240 °C for 30 min, then at 480 °C for 50 min, and finally at 1000 °C for 120 min. After the calcination is completed, cool them to room temperature (the whole process from heating, calcination to cooling is carried out in a nitrogen atmosphere) to obtain the porous ceramic particles.

[0053] Example 3

[0054] A preparation method of an environmentally friendly porous ceramic particle for treating acidic mine wastewater:

[0055] The environmentally friendly porous ceramic particle consists of an inner layer and an outer layer:

[0056] The inner layer is composed of raw materials with the following mass percentages: 46% of biochar-supported nano-zero-valent iron material, 26% of clay, and 28% of water; the average particle size of each raw material in the inner layer is 150 μm.

[0057] The outer layer is composed of raw materials with the following mass percentages: 16% of sludge pyrolysis ash, 23% of sludge, 15% of clay, 13% of lignin, and 33% of water; the average particle size of each raw material in the outer layer is 200 μm.

[0058] The mass ratio of the inner layer to the outer layer is 1.2:1.

[0059] The preparation method is as follows:

[0060] (1) Mix the inner layer raw materials evenly and stir until they become a mud-like state. Then put them into a granulator for granulation to prepare particles with an average particle size of 8 mm. Finally, cure them in a space at 27 °C for 24 h and then air-dry them naturally for 12 h to obtain the inner layer particles;

[0061] (2) Mix the outer layer raw materials evenly and stir until they become a mud-like state. Then add the inner layer particles and wrap the inner layer particles into integral particles with an average particle size of 12 mm to obtain the ceramsite raw material.

[0062] (3) Place the ceramsite raw material in a space at 27 °C for 24 h of curing, and then put it into a vacuum drying oven at 130 °C for 2 h of drying to remove moisture, obtaining the dried particles.

[0063] (4) The dried particles are first calcined at 280 °C for 25 min, then at 550 °C for 40 min, and finally at 1550 °C for 60 min. After the calcination is completed, they are cooled to room temperature (the whole process from heating, calcination to cooling is carried out in a nitrogen atmosphere), and porous ceramic particles are obtained.

[0064] 10 g of the environmentally friendly porous ceramic particles prepared in Example 1, Example 2, and Example 3 are respectively taken and put into acidic mine wastewater with a pH value of 3.2 for adsorption for 24 h. The water quality indexes before and after treatment are shown in Table 1.

[0065] Table 1

[0066]

[0067] The results show that the environmentally friendly porous ceramic particles prepared by the present invention have a good removal effect on heavy metals in acidic mine wastewater, and can adjust the pH to 8.0 - 9.0, improving the wastewater treatment efficiency.

[0068] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. An environmentally friendly porous ceramic particle for treating acidic mine wastewater, Characterized in that, The porous ceramic particle consists of an inner layer and an outer layer; The inner layer includes raw materials in the following mass percentages: 43 - 47% of biochar-supported nano zero-valent iron material, 24 - 32% of clay, and 28 - 33% of water; The outer layer includes raw materials in the following mass percentages: 14 - 18% of pyrolysis ash of excess sludge, 22 - 25% of excess sludge, 13 - 15% of clay, 9 - 15% of lignin, and 28 - 33% of water.

2. The environmentally friendly porous ceramic particle according to claim 1, Characterized in that, The particle size of the solid raw materials of the outer layer is screened to 150 - 200 μm; the particle size of the solid raw materials of the inner layer is screened to 50 - 150 μm; the mass ratio of the inner layer to the outer layer is (0.8 - 1.2):

1.

3. The preparation method of the environmentally friendly porous ceramic particle according to any one of claims 1 - 2, Characterized in that, Comprises the following steps: (1) Weigh each raw material of the inner layer according to the mass percentage, mix evenly, stir into a mud shape, then granulate, ripen, and dry to obtain inner layer particles; (2) Weigh each raw material of the outer layer according to the mass percentage, mix evenly, stir into a mud shape, then add the inner layer particles for coating to obtain green ceramsite, and finally ripen, dry, and calcine the green ceramsite to obtain the porous ceramic particle.

4. The preparation method according to claim 3, Characterized in that, In step (1), the average particle size of the inner layer particles is 3 - 8 mm.

5. The preparation method according to claim 3, Characterized in that, In step (1), the ripening temperature is 20 - 27 °C, the time is 12 - 24 h, and the drying is natural air drying for 12 h.

6. The preparation method according to claim 3, Characterized in that, In step (2), the average particle size of the green ceramsite is 4 - 12 mm.

7. The preparation method according to claim 3, Characterized in that, In step (2), the ripening temperature is 20 - 27 °C, the time is 12 - 24 h; the drying temperature is 90 - 130 °C, the time is 2 - 4 h.

8. The preparation method according to claim 3, Characterized in that, In step (2), the calcination is specifically: first calcine at 200 - 280 °C for 20 - 30 min, then raise the temperature to 400 - 550 °C and calcine for 40 - 60 min, and finally raise the temperature to 750 - 1550 °C and calcine for 60 - 180 min.

9. The preparation method according to claim 3, Characterized in that, In step (2), the calcination is carried out in a nitrogen atmosphere.

10. The application of the environmentally friendly porous ceramic particle according to any one of claims 1 - 2 in water treatment.

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