Method for preparing lightweight porous adsorption ceramsite by utilizing boiler ash and waste biomass

Abstract

The invention discloses a method for preparing lightweight porous adsorption ceramsite by using boiler ash and waste biomass, which comprises the following steps: S1, pretreating the raw materials boiler ash, potassium feldspar, coconut shell and soybean residue, and uniformly mixing to obtain a mixed material; s2, deionized water with the volume ratio of 10%-20% is added into the mixed material obtained in the step S1, then pelletizing and drying are conducted in sequence, and ceramsite to be sintered is obtained; and S3, putting the ceramsite to be sintered obtained in the step S2 into an atmosphere furnace, firstly raising the temperature from 50 DEG C to a preheating temperature of 400-600 DEG C, preserving heat for 20-40 minutes, then continuously raising the temperature to a sintering temperature of 1110-1170 DEG C, preserving heat for 20-40 minutes, and then cooling along with the furnace to obtain the lightweight porous adsorption ceramsite. According to the method, the performance of the ceramsite is improved, the shortage of traditional raw materials is relieved, high-valued resource utilization of the industrial solid waste can be achieved, the environmental risk of boiler ash stockpiling is reduced, double contributions are made to environmental protection and economic benefits, and the synergistic win-win situation of the economic benefits and the environmental benefits is achieved.

Description

Technical Field

[0001] This invention relates to the field of solid waste resource utilization technology, and in particular to a method for preparing lightweight porous adsorption ceramic particles using boiler ash and waste biomass. Background Technology

[0002] The process of replacing and optimizing the structure of coal energy consumption in my country continues to accelerate. However, in the short term, coal-fired power, as the baseload energy source of the power system, will still occupy a dominant position, resulting in the continued growth in the production of boiler ash, a major industrial solid waste generated during coal combustion. If boiler ash is not effectively treated, it will not only occupy a large amount of valuable land resources but also cause serious pollution to soil, water, and the atmosphere. Waste biomass faces the same problem; therefore, how to efficiently treat and utilize boiler ash and waste biomass has become an urgent environmental and resource issue.

[0003] Chemical analysis reveals that boiler ash is primarily composed of inorganic oxides such as SiO2, Al2O3, Fe2O3, CaO, and MgO. Currently, its resource utilization is concentrated in traditional areas like brick making, concrete admixtures, and soil conditioners. However, with the deepening of the "dual-carbon" strategy, my country has formulated more stringent environmental standards and technical specifications for the resource utilization of industrial solid waste. Traditional boiler ash products are facing declining market competitiveness due to their performance and environmental indicators failing to meet these new requirements. Therefore, overcoming the technological bottlenecks in ash resource utilization and achieving efficient resource recovery and harmless disposal has become a critical technical issue urgently needing to be addressed in the field of industrial solid waste treatment.

[0004] Meanwhile, ceramsite, a lightweight artificial aggregate made from aluminosilicates as its core raw material through processes such as batching, molding, and sintering, is widely used in building materials, deep wastewater purification, and ecological conservation due to its high strength, low density, excellent chemical stability, environmental friendliness, and efficient thermal insulation properties. However, the depletion of resources and ecological damage caused by the over-exploitation of traditional ceramsite raw materials have made finding low-cost, highly adaptable alternative raw materials an urgent priority for the sustainable development of the ceramsite industry. Summary of the Invention

[0005] To address the aforementioned problems, the purpose of this invention is to provide a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass. This method not only improves the performance of ceramsite but also alleviates the shortage of traditional raw materials. It also enables the high-value resource utilization of industrial solid waste, reduces the environmental risks of boiler ash accumulation, and makes a dual contribution to environmental protection and economic benefits, achieving a synergistic win-win situation for both economic and environmental benefits.

[0006] To address the problems in the existing technology, the technical solution adopted by this invention is as follows:

[0007] A method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass includes the following steps: S1: Pre-treating raw materials boiler ash, potassium feldspar, coconut shell, and soybean residue, then mixing them evenly to obtain a mixture; S2: Adding 10-20% by volume of deionized water to the mixture obtained in step S1, then sequentially pelletizing and drying to obtain ceramsite to be sintered; S3: Placing the ceramsite to be sintered in an atmosphere furnace, first raising the temperature from 50°C to a preheating temperature of 400-600°C, holding for 20-40 min, then continuing to raise the temperature to a sintering temperature of 1110-1170°C, holding for 20-40 min, and then cooling with the furnace to obtain lightweight porous adsorption ceramsite.

[0008] Furthermore, the pretreatment in step S1 includes the following steps: soaking coconut shells and soybean residue in a water tank, removing them and cleaning the surface mud, sand, fiber fibrous material and other impurities, cutting the cleaned whole coconut shells into small pieces with a cutting machine, then placing the coconut shells, soybean residue, boiler ash, and potassium feldspar in an oven to dry, and using a ball mill to grind the dried boiler ash, potassium feldspar, coconut shells and soybean residue until they are sieved.

[0009] Further, in step S1, the mass ratio of boiler ash, potassium feldspar, coconut shell and soybean residue is: boiler ash 50-80%, potassium feldspar 14-44%, coconut shell 3-6%, and soybean residue 3-6%.

[0010] Furthermore, during the pretreatment process, the drying temperature is 100℃ and the drying time is 4 hours.

[0011] Furthermore, during the pretreatment process, the specific cutting operation involves using a cutting machine to cut the whole coconut shell into small pieces of 5-10cm.

[0012] Furthermore, during the pretreatment process, the particle size of the boiler ash, potassium feldspar, coconut shell, and soybean residue obtained after sieving is ≥200 mesh.

[0013] Furthermore, during the pretreatment process, the boiler ash, potassium feldspar, coconut shell and soybean residue are dried at 100℃ for 3 hours.

[0014] Furthermore, in step S2, the conditions are a drying temperature of 100–130°C and a drying time of 2–4 hours.

[0015] Furthermore, in step S3, the particle size of the ceramic granules to be fired is 8~10mm.

[0016] Furthermore, in step S3, the heating rate is 5°C / min.

[0017] Another object of the present invention is to provide lightweight porous adsorbent ceramic particles prepared by the above method.

[0018] The mechanism of this invention is as follows: precisely controlling the silicon-to-aluminum ratio in the raw materials regulates the content of the formed glass phase, thus affecting the melt flowability and viscosity. SiO2 uses [SiO4] tetrahedra as its basic units, forming a continuous and stable three-dimensional network through shared oxygen atoms. When the silicon-to-aluminum ratio is high, a small amount of Al2O3 participates in the reaction, acting as a network modifier to partially replace Si. 4+ Upon entering the network, the overall structure remains a dense network dominated by SiO2. At this point, the tendency for glass phase formation is low; more SiO2 preferentially forms crystalline phases such as quartz and mullite. Furthermore, the glass phase itself is difficult to flow due to the network's stability, resulting in poor melt flowability, high viscosity of the high-temperature liquid phase, and difficulty for bubbles generated by raw material combustion to escape through the viscous liquid phase, forming small and closed micropores. The water absorption rate of the ceramic particles is low. When the silicon-to-aluminum ratio is low, and the Al2O3 content exceeds the network's capacity, Al³⁺ that has not entered the SiO2 network... + Al2O3 exists as isolated [AlO4] tetrahedra, which disrupt the continuous network structure of SiO2. Meanwhile, Al2O3 has a much higher melting point than SiO2. Excess Al2O3 forms eutectic compounds with alkali / alkaline earth metal oxides in the raw materials, significantly lowering the system's melting point. This allows more components to melt at the sintering temperature to form a glassy phase. The large amount of network-broken glassy phase becomes the main component of the melt, increasing the fluidity of the high-temperature liquid phase. At this point, the liquid phase viscosity is low, and bubbles escape more easily, leading to a significant increase in the porosity of the ceramsite and its water absorption rate.

[0019] The lightweight porous adsorption ceramsite prepared by this invention has an apparent density ranging from 1.45 to 1.72 g / cm³, a bulk density ranging from 0.68 to 0.75 g / cm³, a compressive strength ranging from 4.62 to 7.97 MPa, and a 1-hour water absorption rate ranging from 11.27% to 16.39%. The silicon-to-aluminum ratio of the raw material is 2.12 to 2.84. As the silicon-to-aluminum ratio decreases, the content of waste biomass increases, and the apparent density, bulk density, and compressive strength of the ceramsite show a decreasing trend, while the water absorption rate shows an increasing trend.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] 1. Given that boiler ash is rich in aluminosilicates, it can serve as an ideal skeletal substrate for ceramsite preparation. This invention uses boiler ash and potassium feldspar as the main raw materials. Boiler ash and potassium feldspar not only provide the necessary aluminosilicates for ceramsite but also important alkali oxides. Aluminosilicates constitute the skeletal components of ceramsite, supporting the entire structure and enabling the ceramsite to maintain its shape and stability during formation. Alkali oxides act as fluxes during the melting process of the ceramsite blank, effectively lowering the melting temperature and promoting sintering and molding. Through this innovative combination of raw materials and process design, this method not only improves the performance of ceramsite but also alleviates the shortage of traditional raw materials. It also enables the high-value resource utilization of industrial solid waste, reduces the environmental risks of boiler ash accumulation, and makes a dual contribution to environmental protection and economic benefits, achieving a synergistic win-win situation for both.

[0022] 2. In this invention, coconut shell is used as a foaming agent. Because it is rich in cellulose, hemicellulose, and lignin, it undergoes pyrolysis and combustion during the calcination of the expanded clay aggregate, producing gases such as CO2 and H2O, forming a large number of interconnected pore structures, which greatly increases the specific surface area and porosity of the expanded clay aggregate. By increasing the content of closed pores inside the expanded clay aggregate, the resulting lightweight porous adsorption expanded clay aggregate has a complete internal pore structure and uniform foaming degree, possessing not only excellent mechanical properties but also significantly reducing the bulk density of the expanded clay aggregate.

[0023] 3. In this invention, soybean residue is used as a binder, mainly playing a binding role. The protein, pectin and other components contained in soybean residue have good viscosity. By improving the bonding strength between raw material particles, the pelletizing efficiency of ceramsite is improved, and the microstructure of ceramsite is affected, so that the ceramsite produced is round and complete. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the following Examples 1-7, the boiler ash used is a large amount of solid waste generated after coal combustion.

[0026] In the following Examples 1-7, the coconut shells and soybean residue used are waste biomass.

[0027] In the following Examples 1-7, the deionized water is used in the form of adding it in small amounts multiple times.

[0028] The chemical composition of the raw materials in Examples 1-7 below is shown in the table.

[0029] raw materials <![CDATA[SiO2]]> <![CDATA[Al2O3]]> <![CDATA[Fe2O3]]> CaO MgO <![CDATA[K2O]]> <![CDATA[Na2O]]> other Boiler ash 60.08 26.31 5.56 4.07 1.52 1.64 0.22 0.60 Potassium feldspar 72.86 15.01 0.37 0.20 0.16 9.13 2.01 0.26

[0030] In Examples 1-7 below, the raw materials need to be pre-treated. Coconut shells and soybean residue are soaked in a water tank for 3 hours. After removal, the surface mud, sand, and fiber fibrous impurities are cleaned. The cleaned whole coconut shells are then cut into small pieces using a cutting machine. Next, the coconut shells, soybean residue, boiler ash, and potassium feldspar are placed in an oven to dry at 100°C for 3 hours. The dried boiler ash, potassium feldspar, coconut shells, and soybean residue are then ground into powder using a ball mill and sieved. The particle size of the sieved boiler ash, potassium feldspar, coconut shells, and soybean residue is ≥200 mesh.

[0031] Example 1

[0032] This embodiment discloses a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass.

[0033] (1) Weigh the treated boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 50:44:3:3. Then mix the raw materials evenly, add 10% deionized water by volume to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0034] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0035] The obtained lightweight porous adsorbent ceramsite has an apparent density of 1.72 g / cm³, a bulk density of 0.75 g / cm³, a porosity of 31.7%, a compressive strength of 7.97 MPa, and a water absorption rate of 11.27% after 1 hour.

[0036] Example 2:

[0037] This embodiment discloses a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass.

[0038] (1) Weigh boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 60:34:3:3. Then mix the raw materials evenly, add an equal volume of 10% deionized water to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0039] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0040] The obtained lightweight porous adsorbent ceramsite has an apparent density of 1.66 g / cm³, a bulk density of 0.73 g / cm³, a porosity of 36.5%, a compressive strength of 5.67 MPa, and a water absorption rate of 13.72% after 1 hour.

[0041] Example 3:

[0042] This embodiment provides a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass, including the following steps:

[0043] (1) Weigh boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 70:24:3:3. Then mix the raw materials evenly, add an equal volume of 10% deionized water to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0044] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0045] The obtained lightweight porous adsorbent ceramsite has an apparent density of 1.51 g / cm³, a bulk density of 0.68 g / cm³, a porosity of 39.4%, a compressive strength of 5.01 MPa, and a water absorption rate of 14.64% after 1 hour.

[0046] Example 4

[0047] This embodiment provides a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass, including the following steps:

[0048] (1) Weigh boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 80:14:3:3. Then mix the raw materials evenly, add an equal volume of 10% deionized water to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0049] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0050] The obtained lightweight porous adsorbent ceramsite has an apparent density of 1.45 g / cm³, a bulk density of 0.68 g / cm³, a porosity of 44.2%, a compressive strength of 4.62 MPa, and a water absorption rate of 16.39% after 1 hour.

[0051] Example 5

[0052] This embodiment provides a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass, including the following steps:

[0053] (1) Weigh boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 60:34:6:3. Then mix the raw materials evenly, add an equal volume of 10% deionized water to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0054] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0055] The obtained lightweight porous adsorbent ceramsite has an apparent density of 1.56 g / cm³, a bulk density of 0.74 g / cm³, a porosity of 41.3%, a compressive strength of 5.24 MPa, and a water absorption rate of 15.21% in 1 hour.

[0056] Example 6

[0057] This embodiment provides a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass, including the following steps:

[0058] (1) Weigh boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 60:34:3:6. Then mix the raw materials evenly, add an equal volume of 10% deionized water to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0059] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0060] The obtained lightweight ceramsite has an apparent density of 1.67 g / cm³, a bulk density of 0.71 g / cm³, a porosity of 36.8%, a compressive strength of 5.63 MPa, and a water absorption rate of 13.42% in 1 hour.

[0061] Example 7

[0062] This embodiment provides a method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass, including the following steps:

[0063] (1) Weigh boiler ash, potassium feldspar, coconut shell and soybean residue in a mass ratio of 60:34:6:6. Then mix the raw materials evenly, add an equal volume of 10% deionized water to the mixture, and then pelletize and dry them in sequence. The drying temperature is 100℃ and the drying time is 4h to obtain the ceramic granules to be fired.

[0064] (2) The obtained ceramic particles to be fired are placed in an atmosphere furnace. The temperature is first increased from 50°C to 500°C at 5°C / min and held for 30 min. Then the temperature is increased to 1150°C at 5°C / min and held for 30 min. After cooling with the furnace, lightweight porous adsorption ceramic particles are obtained.

[0065] The obtained lightweight ceramsite has an apparent density of 1.54 g / cm³, a bulk density of 0.72 g / cm³, a porosity of 40.2%, a compressive strength of 5.21 MPa, and a water absorption rate of 14.21% after 1 hour.

[0066] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing lightweight porous adsorbent ceramsite using boiler ash and waste biomass, characterized in that, Includes the following steps: S1: The raw materials, boiler ash, potassium feldspar, coconut shell and soybean residue, are pretreated and then mixed evenly to obtain a mixture. S2: Add 10-20% by volume of deionized water to the mixture obtained in step S1, and then proceed with pelletizing and drying to obtain ceramsite to be fired. S3: Place the ceramic particles to be fired obtained in step S2 into an atmosphere furnace, first raise the temperature from 50°C to a preheating temperature of 400-600°C, hold for 20-40 min, then continue to raise the temperature to a sintering temperature of 1110-1170°C, hold for 20-40 min, and then cool with the furnace to obtain lightweight porous adsorption ceramic particles.

2. The method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass as described in claim 1, characterized in that, In step S1, the mass ratio of boiler ash, potassium feldspar, coconut shell and soybean residue is: boiler ash 50-80%, potassium feldspar 14-44%, coconut shell 3-6%, and soybean residue 3-6%.

3. The method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass as described in claim 1, characterized in that, The pretreatment in step S1 includes the following steps: soaking coconut shells and soybean residue in a water tank, removing them and cleaning the surface mud, sand and fiber fibrous materials, etc., using a cutting machine to cut the cleaned whole coconut shells into small pieces, then placing the coconut shells, soybean residue, boiler ash and potassium feldspar in an oven to dry, and using a ball mill to grind the dried boiler ash, potassium feldspar, coconut shells and soybean residue until they are sieved.

4. The method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass as described in claim 3, characterized in that, During the pretreatment process, the drying temperature is 100-130℃ and the drying time is 2-4 hours.

5. The method for preparing lightweight porous adsorbent ceramsite using boiler ash and waste biomass as described in claim 3, characterized in that, During the pretreatment process, the specific cutting operation involves using a cutting machine to cut the whole coconut shell into small pieces of 5-10cm.

6. The method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass as described in claim 3, characterized in that, During the pretreatment process, the particle size of boiler ash, potassium feldspar, coconut shell and soybean residue obtained after sieving is ≥200 mesh.

7. The method for preparing lightweight porous adsorption ceramsite using boiler ash and waste biomass as described in claim 1, characterized in that, In step S2, the conditions are a drying temperature of 100–130°C and a drying time of 2–4 hours.

8. The method for preparing lightweight porous adsorbent ceramsite using boiler ash and waste biomass as described in claim 1, characterized in that, In step S2, the particle size of the ceramic granules to be fired is 8~10mm.

9. The method for preparing lightweight porous adsorbent ceramsite using boiler ash and waste biomass as described in claim 1, characterized in that, In step S3, the preheating rate is 5-10℃ / min, and the sintering rate is 5-8℃ / min.

10. Lightweight porous adsorbent ceramic particles prepared by the method according to any one of claims 1 to 9.