Method for preparing porous ceramics by mixing solid wastes

Abstract

This invention discloses a method for preparing porous ceramics from solid waste, comprising the following steps: (1) Raw material pretreatment: dewatering waste sludge; crushing waste insulation cotton; (2) Porous ceramic preparation: uniformly mixing the pretreated waste sludge, waste insulation cotton, and coal gasification slag to obtain a mixture; pressing the mixture into a porous ceramic blank; sintering the porous ceramic blank at high temperature; and cooling to obtain porous ceramics. This invention achieves the resource utilization of waste sludge, coal gasification slag, and waste insulation cotton through this method.

Description

Technical Field

[0001] This invention relates to the technical field of solid waste resource utilization, and specifically to a method for preparing porous ceramics by mixing solid waste. Background Technology

[0002] Porous ceramics, also known as porous functional ceramics, are novel ceramic materials in which numerous interconnected or closed pores are formed within the material during the forming and sintering process. Due to their large specific surface area and unique physical surface properties, porous ceramics exhibit selective permeability to liquid and gas media, energy absorption, and pressure resistance. Combined with the inherent high-temperature resistance and corrosion resistance of ceramic materials, porous ceramics are widely used in gas-liquid filtration, purification and separation, chemical catalyst carriers, advanced thermal insulation materials, and bio-implantation materials. The source of porous ceramics is natural minerals. However, with the depletion of resources, the content of natural minerals is decreasing, and the cost of preparing porous ceramics from natural minerals is increasing. Therefore, researchers have begun to study the preparation of ceramic materials using industrial waste.

[0003] Coal gasification slag is a byproduct of the coal gasification industry and a typical bulk solid waste. It is estimated that the annual output of coal gasification slag from fluidized bed gasifiers in the domestic coal gasification industry alone exceeds 60 million tons. The traditional method of treating coal gasification slag is landfill, which has the following problems: ① it requires a large land area, reducing the usable land area; ② some coal gasification slag contains heavy metals, which pollutes soil and water bodies and increases landfill costs. Therefore, it is necessary to find a better method for treating coal gasification slag. Coal gasification slag is mainly composed of silicon dioxide, alumina, residual carbon, and some other metal oxides. Due to the fine coal gasification slag's porous structure, abundant amorphous carbon, highly active siliceous components, and rich pore structure, the resource utilization of coal gasification slag is essential.

[0004] Waste sludge, also known as sewage sludge, is a type of waste that easily generates secondary pollution during traditional treatment and disposal processes. It generally refers to the sludge produced by urban wastewater treatment plants. Existing methods for treating and disposing of urban sewage sludge can no longer meet the needs of social development and people's demands. Therefore, recycling and reusing waste sludge has become a crucial method for waste sludge treatment because it increases utilization rates and reduces secondary pollution.

[0005] Waste thermal insulation cotton is a common industrial solid waste, and its disposal and treatment is an important environmental issue. On the one hand, if this waste is discarded directly without proper treatment, it not only occupies a large amount of land resources but may also pollute the environment, such as releasing harmful gases and affecting soil and groundwater quality. On the other hand, waste thermal insulation cotton contains reusable fiber or polymer components. Through reasonable recycling technologies, it can be transformed into renewable resources, achieving resource recycling, reducing the demand for new raw materials, and contributing to the construction of a sustainable circular economy system. Common methods for treating waste thermal insulation cotton include physical methods (such as crushing, screening, and washing), chemical methods (such as dissolution and modification), and thermal methods (such as pyrolysis and incineration). Summary of the Invention

[0006] The first objective of this invention is to provide a method for preparing porous ceramics by mixing solid wastes, thereby realizing the resource utilization of waste sludge, coal gasification slag and waste insulation cotton.

[0007] A second objective of this invention is to provide porous ceramics prepared by the above method.

[0008] The objective of this invention is achieved through the following scheme.

[0009] A method for preparing porous ceramics by mixing solid waste includes the following steps:

[0010] (1) Raw material pretreatment: Dewater the waste sludge; crush the waste insulation cotton;

[0011] (2) Preparation of porous ceramics: The pretreated waste sludge, waste insulation cotton and coal gasification slag are mixed evenly to obtain a mixture; the mixture is pressed into a porous ceramic blank, the porous ceramic blank is sintered at high temperature and cooled to obtain porous ceramics.

[0012] Preferably, the dehydration process in step (1) involves exposing and drying the waste sludge to the sun, reducing its moisture content to less than 5%.

[0013] Preferably, the particle size of the pretreated waste sludge, waste insulation cotton, and coal gasification slag should be less than 0.1 mm.

[0014] As a specific implementation method, the pretreated waste sludge, waste insulation cotton, and coal gasification slag are passed through a 200-mesh sieve to ensure that their particle size meets the requirements; of course, other methods can also be used for particle size screening. The waste sludge and coal gasification slag can be screened separately, or they can be mixed before screening.

[0015] Preferably, the coal gasification slag is fine coal gasification slag, which contains a certain amount of residual carbon and amorphous aluminosilicates, making it a good raw material for preparing porous ceramics.

[0016] As a specific implementation method, in step (2), waste sludge, coal gasification slag and waste insulation cotton are mixed in a mass ratio of 1-2:4-5:2-3.

[0017] As a specific implementation method, a magnetic stirrer is used to mix the pretreated waste sludge, waste insulation cotton, and coal gasification slag for 0.5 to 2 hours. Of course, other mixing methods can also be used, as long as the raw materials are mixed evenly.

[0018] As another specific implementation, when large-scale production is carried out, in order to accommodate a large amount of raw materials, in step (2), the pretreated waste sludge, waste insulation cotton and coal gasification slag are mixed evenly by ball milling for 30 minutes.

[0019] Preferably, in step (2), the pressing pressure is 15-20 MPa, and the pressure is held for 20-30 seconds.

[0020] Preferably, in step (2), the sintering temperature is 1000-1200℃ and the sintering time is 4h.

[0021] Preferably, in step (2), the sintering temperature is increased to 1000-1200°C at a heating rate of 3-10°C / min, held at the temperature for 4 hours, and then cooled to room temperature at a cooling rate of 2-6°C / min.

[0022] The present invention also provides a porous ceramic prepared by the above method.

[0023] The porous ceramic has a water absorption rate of 50-70%, an apparent porosity of 60-65%, a compressive strength of 10-20 MPa, and an average pore size of 1.7-2 μm. Furthermore, due to high-temperature sintering, the porous ceramic has almost no heavy metal residue.

[0024] Compared with the prior art, the present invention has the following beneficial effects.

[0025] This invention utilizes waste sludge, coal gasification slag, and waste insulation cotton as raw materials to produce porous ceramics, thereby realizing the resource utilization and high-value transformation of waste sludge, coal gasification slag, and waste insulation cotton. This promotes the development of a circular economy and solves the problems of large-scale accumulation of solid waste, occupation of land resources, and environmental pollution.

[0026] This invention completely replaces natural mineral raw materials in traditional ceramic preparation by efficiently utilizing solid waste. This not only reduces dependence on traditional ceramic production raw materials, but also greatly improves the recycling rate of resources and reduces production costs.

[0027] This invention utilizes coal gasification slag as a basic raw material, and waste sludge and waste insulation cotton as pore-forming agents and modifiers. By optimizing the ratio and process flow, porous ceramics are produced, which not only ensures that the porous ceramics have a high apparent porosity, but also improves their mechanical strength and toughness, thereby giving the product excellent water absorption, air permeability and filtration performance.

[0028] The porous ceramics prepared by this invention have high compressive strength, high water absorption rate, and high apparent porosity, and can be applied to water pollution control, air purification, sound insulation and heat insulation materials, etc. Detailed Implementation

[0029] The present invention will be further described below through specific embodiments.

[0030] The method for testing the performance of porous ceramic materials according to the present invention is as follows: the apparent porosity of porous ceramics is determined by the "Test Method for Apparent Porosity and Bulk Density of Porous Ceramics" (GB / T 1966-1996), the flexural strength is tested by the "Test Method for Bending Strength of Ceramic Materials" (GB / T4741-1999), and the average pore size of porous ceramics is determined by a pore size distribution measuring instrument.

[0031] In the following embodiments, the specific operations for pretreatment of waste sludge, coal gasification slag, and waste insulation cotton are as follows:

[0032] The waste sludge is exposed to the sun and then placed in a constant temperature drying oven to dry it until the moisture content is less than 5%, expressed as a percentage by mass.

[0033] The dewatered waste sludge and coal gasification slag are passed through a 200-mesh sieve;

[0034] The waste thermal insulation cotton is crushed and then passed through a 200-mesh sieve.

[0035] Example 1

[0036] Weigh out 20g of pretreated waste sludge, 50g of coal gasification fine slag, and 30g of waste insulation cotton according to the weight ratio. Stir with a magnetic stirrer for 1 hour to obtain a uniform mixture. Press the uniformly mixed material into a porous ceramic blank of 50mm*50mm*10mm using a hydraulic press. The molding pressure is 15MPa, and the pressure is held for 20s. Then, place the porous ceramic blank in a muffle furnace and heat it to 1000℃ at a heating rate of 5℃ / min. Hold it at that temperature for 4 hours, and then cool it to room temperature at a cooling rate of 3℃ / min to obtain the porous ceramic.

[0037] Measurements showed that the prepared porous ceramic had a water absorption rate of 52.3%, an apparent porosity of 61%, a flexural strength of 10 MPa, and an average pore size of 1.7 μm.

[0038] Example 2

[0039] Weigh out 20g of pretreated waste sludge, 40g of coal gasification fine slag, and 30g of waste insulation cotton according to the weight ratio. Stir with a magnetic stirrer for 1 hour to obtain a uniform mixture. Press the uniformly mixed material into a porous ceramic blank of 50mm*50mm*10mm using a hydraulic press. The molding pressure is 15MPa, and the pressure is held for 30s. Then, place the porous ceramic blank in a muffle furnace and heat it to 1200℃ at a heating rate of 9℃ / min. Hold it at that temperature for 4 hours, and then cool it to room temperature at a cooling rate of 6℃ / min to obtain the porous ceramic.

[0040] Measurements showed that the prepared porous ceramic had a water absorption rate of 65%, an apparent porosity of 60.7%, a compressive strength of 12 MPa, and an average pore size of 1.7 μm.

[0041] Example 3

[0042] Weigh out 1.5 kg of pretreated waste sludge, 5 kg of coal gasification fine slag, and 3 kg of waste insulation cotton according to the weight ratio. Ball mill them for 30 min to obtain a uniform mixture. Press the uniformly mixed material into multiple 50 mm * 50 mm * 10 mm porous ceramic blanks using a hydraulic press. The forming pressure is 20 MPa, and the pressure is held for 20 s. Then, place the porous ceramic blanks in a muffle furnace and heat them to 1200 °C at a heating rate of 3 °C / min. Hold the temperature for 4 h and then cool them to room temperature at a cooling rate of 4 °C / min to obtain porous ceramics.

[0043] Measurements showed that the prepared porous ceramic had a water absorption rate of 70%, an apparent porosity of 62.5%, a compressive strength of 15 MPa, and an average pore size of 1.8 μm.

[0044] Example 4

[0045] Weigh out 20 kg of pretreated waste sludge, 40 kg of coal gasification fine slag, and 20 kg of waste insulation cotton according to the weight ratio. Ball mill the mixture for 30 min and mix them evenly to obtain a mixture. Press the evenly mixed material into multiple 50 mm * 50 mm * 10 mm porous ceramic blanks using a hydraulic press. The forming pressure is 20 MPa and the pressure is held for 20 s. Then, place the porous ceramic blanks in a muffle furnace and heat them to 1000 °C at a heating rate of 5 °C / min. Hold the temperature for 4 h and then cool them to room temperature at a cooling rate of 4 °C / min to obtain porous ceramics.

[0046] Measurements showed that the prepared porous ceramic had a water absorption rate of 69%, an apparent porosity of 64.2%, a compressive strength of 15 MPa, and an average pore size of 1.7 μm.

[0047] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be noted that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for the production of porous ceramics from solid waste, characterized in that, Includes the following steps: (1) Raw material pretreatment: Dewatering the waste sludge; The waste insulation cotton is crushed. (2) Preparation of porous ceramics: The pretreated waste sludge, waste insulation cotton and coal gasification slag are mixed evenly to obtain a mixture; the mixture is pressed into a porous ceramic blank, the porous ceramic blank is sintered at high temperature and cooled to obtain porous ceramics; the mass ratio of the waste sludge, coal gasification slag and waste insulation cotton is 1~2:4~5:2~3, and the coal gasification slag is fine coal gasification slag.

2. The method for preparing porous ceramics by mixing solid waste according to claim 1, characterized in that, The dehydration process involves exposing and drying the waste sludge to the sun, reducing its moisture content to below 5%.

3. The method for preparing porous ceramics by mixing solid waste according to claim 2, characterized in that, The pretreated waste sludge, waste insulation cotton, and coal gasification slag are passed through a 200-mesh sieve.

4. The method for preparing porous ceramics by mixing solid waste according to claim 3, characterized in that, In step (2), the pressing pressure is 15~20MPa and the pressure is held for 20~30s.

5. The method for preparing porous ceramics by mixing solid waste according to claim 4, characterized in that, In step (2), the sintering temperature is 1000~1200℃, and the sintering time is 4h; The sintering temperature is specifically increased to 1000-1200℃ at a heating rate of 3-10℃ / min, held at that temperature for 4 hours, and then cooled to room temperature at a cooling rate of 2-6℃ / min.

6. The method for preparing porous ceramics by mixing solid waste according to claim 5, characterized in that, The pretreated waste sludge, waste insulation cotton and coal gasification slag were mixed using a magnetic stirrer for 0.5 to 2 hours.

7. The method for preparing porous ceramics by mixing solid waste according to claim 6, characterized in that, The pretreated waste sludge, waste insulation cotton and coal gasification slag are mixed evenly by ball milling for 30 minutes.