Preparation method of unfired haydite taking sludge gasification slag as raw material

Abstract

The method for preparing non-fired ceramsite using sludge gasification residue as raw material includes the following steps: (1) crushing the sludge gasification residue and screening out the large-sized particles as the core; (2) grinding particles and powders with a particle size of less than 5 mm to obtain finely ground sludge gasification residue powder, which is used as a component material of the coating powder; (3) preparing the coating powder; (4) uniformly mixing the core and the coating powder to form a particle-powder mixture; (5) adding water to the particle-powder mixture and mixing until uniform coating is obtained to obtain non-fired ceramsite using sludge gasification residue; (6) testing its cylinder compressive strength, apparent density, bulk density and water absorption rate after curing. This invention utilizes sludge gasification residue as a resource. When used as the core of non-fired ceramsite, it is easy to coat, and the preparation process is simple. When the finely ground sludge gasification residue replaces part of the cementitious material as the coating powder, the cost can be reduced. The strength of the prepared non-fired ceramsite meets the requirements of ordinary lightweight aggregates, and the sludge gasification residue can be used as a building material.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization technology, specifically relating to a method for preparing non-fired ceramsite using sludge gasification slag as raw material. Background Technology

[0002] With the increasing discharge of urban wastewater and sewage, the amount of urban sludge has also increased significantly. It is estimated that by 2025, my country's annual sludge production will exceed 90 million tons. If not properly treated, sludge will have adverse effects on the environment and human health, necessitating its resource utilization. Sludge pyrolysis gasification technology is a green, independent sludge incineration technology. After dewatering and granulating, the sludge is placed in a gasifier. The organic matter in the sludge undergoes physicochemical reactions to generate combustible gas. The high-temperature flue gas produced by the combustion of this combustible gas can dry the sludge in its early stages, preparing it into uniformly sized lumps. Slag is formed during the pyrolysis gasification process, reducing sludge volume by more than 90%. Sludge gasification slag is lightweight, but due to limitations in the incineration process, the slag particle shape and strength are uneven, making it difficult to use directly as aggregate in ordinary concrete. However, the sludge gasification slag undergoes high-temperature treatment in the incinerator, giving it a certain degree of reactivity, allowing it to be ground and used as an admixture.

[0003] Non-fired ceramsite is a type of artificial lightweight aggregate made from raw materials through granulation and natural curing. Compared with traditional calcined ceramsite, it has the advantages of lower production costs and less construction investment. However, existing non-fired ceramsite production processes often involve preparing the core from solid waste in a granulator and then coating it with a shell. The core forming process is complex, and the core has a high apparent density, making it difficult to meet the requirements for lightweight aggregate. The invention patent "A Method for Preparing High-Quality Lightweight Aggregate from Sludge" uses a mixture of sludge, plant fiber, quicklime, and water glass to form pellets as the core for lightweight aggregate preparation, but this requires additional processes such as microwave heating and sludge deodorization. The invention patent "Core-Shell Structure High-Strength Earthquake-Resistant Non-fired Ceramsite, Its Preparation Method and Application" uses foam balls as the core for non-fired ceramsite preparation, but the foam balls themselves lack strength and require processing. Meanwhile, existing non-fired ceramsite coating technologies often use cement composite admixtures or alkali-activated materials, resulting in relatively high costs.

[0004] Sludge gasification residue, the slag produced after pyrolysis and gasification in wastewater treatment plants, possesses a certain strength and is lightweight. Using it as the core material to prepare coated non-fired ceramsite can significantly simplify the preparation process. Sludge gasification residue powder can be processed and used as a coating material, further reducing the production cost of non-fired ceramsite. The application of sludge gasification residue as both the core and coating material for non-fired ceramsite simplifies the preparation process, enabling the production of non-fired ceramsite suitable for lightweight aggregate concrete at a lower cost. Furthermore, it allows for the resource utilization of sludge gasification residue, solving the problem of sludge treatment. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for preparing non-fired ceramsite using sludge gasification slag as raw material. The method uses sludge gasification slag from a wastewater treatment plant as the core material, and prepares a coated powder by grinding the sludge gasification slag and mixing it with a cementitious material. This coated powder is then used to prepare non-fired ceramsite. This method not only produces high-strength, lightweight ceramsite suitable for use in lightweight concrete, but also solves the problem of resource utilization of sludge gasification slag.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing non-fired ceramsite using sludge gasification slag as raw material, comprising the following steps:

[0007] (1) The sludge gasification residue is crushed using a crusher, and particles with a diameter of 5-25mm are screened out as the core of the non-fired ceramsite.

[0008] (2) The particles and powders with a particle size of less than 5 mm remaining after sieving are ground in a ball mill until the specific surface area is 100 m². 2 / kg or more, to obtain finely ground sludge gasification slag powder, which is used as a component material of the coating powder;

[0009] (3) Preparation of shell-coated powder;

[0010] (4) Mix the kernel prepared in step (1) with the shell powder prepared in step (3) to form a granular powder mixture;

[0011] (5) Add water to the granule-powder mixture and mix until the coating is uniform to obtain sludge gasification slag non-fired ceramsite.

[0012] (6) After the sludge gasification residue non-fired ceramsite is naturally cured or carbonized, its cylinder compressive strength, apparent density, bulk density and water absorption rate are tested.

[0013] Furthermore, the composition of the coating powder in step (3) is: 0-100 wt% ordinary silicate cement, 0-20 wt% ground sludge gasification slag, 0-100 wt% ground carbide slag, 0-50 wt% fly ash, 0-5 wt% silica fume, and 0-2 wt% polycarboxylate superplasticizer.

[0014] Furthermore, in step (4), the weight ratio of the core to the shell powder is 10:1 to 15:1.

[0015] Furthermore, in step (5), the mixing water is added in a spray form, and the granulation time is 10-25 minutes.

[0016] Furthermore, the natural curing conditions in step (6) are as follows: the unfired ceramsite after coating is placed in a natural environment for curing for more than 28 days, and the natural environment conditions are a temperature of 10-30℃ and a relative humidity of 40%-80%.

[0017] Furthermore, the carbonization curing conditions in step (6) are as follows: after coating, the non-fired ceramsite is placed in a carbonization environment for curing for more than 1 hour. The carbonization environment conditions are: carbon dioxide concentration of 10-100vt%, temperature of 10-30℃, and relative humidity of 40%-80%.

[0018] Compared with existing technologies, the beneficial effects of the present invention using the above technical solution are as follows: Sludge gasification slag urgently needs resource utilization; it is easy to coat as the core of non-fired ceramsite, the preparation process is simple, and the cost can be reduced when grinding sludge gasification slag to replace part of the cementitious material as the coating powder. The strength of non-fired ceramsite prepared using sludge gasification slag meets the requirements of ordinary lightweight aggregates, enabling the building material utilization of sludge gasification slag. Attached Figure Description

[0019] Figure 1 This is the cross-section of the non-fired ceramsite sample W11 after 90 days of curing;

[0020] Figure 2 This is the cross-section of the non-fired ceramsite sample numbered W14 after 90 days of curing. Detailed Implementation

[0021] The present invention will be further described in detail below with reference to specific embodiments.

[0022] The sludge gasification residue used in the following examples was taken from a wastewater treatment plant in Zhengzhou City. Its initial form was cylindrical particles approximately 2 cm long and 1 cm in diameter. A small jaw crusher was used to crush the sludge gasification residue, and particles with a diameter of 5 mm or larger were selected. The particle size range of the sludge gasification residue core was selected according to the required particle size of the ceramsite. After sieving, particles with a diameter of less than 5 mm were placed in a laboratory ball mill for grinding to obtain finely ground sludge gasification residue with a specific surface area of ​​310 m². 2 / kg; the cement used is P.O42.5 ordinary Portland cement; the finely ground calcium carbide slag powder is obtained by grinding calcium carbide slag powder, with a specific surface area of ​​288m². 2 / kg; the fly ash is Grade II fly ash with an activity index of 76%; the silica fume activity index is 110%; the polycarboxylate superplasticizer has a water reduction rate of 23% and is in powder form.

[0023] Example 1:

[0024] A method for preparing non-fired ceramsite using sludge gasification slag as raw material includes the following steps: The sludge gasification slag is crushed by a small jaw crusher, and particles with a diameter of 5-15 mm are screened out and placed in a granulator. Ordinary silicate cement, finely ground sludge gasification slag, fly ash, silica fume, and polycarboxylate superplasticizer are mixed evenly in a certain proportion and then uniformly added to the granulator. Mixing water is added via spraying. The granulation time is 25 minutes. After coating, the non-fired ceramsite is cured in a natural environment at 20℃ and 60% relative humidity. The compressive strength, apparent density, bulk density, and water absorption rate are tested after 28 days and 90 days of curing.

[0025] Design of non-fired ceramsite formulation using sludge gasification residue as raw material (single granulator usage, unit: kg)

[0026] W10 3 0 0 0 0 0 W11 3 0.9 0 0 0 0 W12 3 0.45 0.45 0 0 0 W13 3 0.405 0.225 0.225 0.045 0.018 W14 3 0.6 0 0 0 0 W15 3 0.3 0.3 0 0 0 W16 3 0.27 0.15 0.15 0.03 0.012

[0027] Performance testing of non-fired ceramsite using sludge gasification residue as raw material

[0028]

[0029] Example 2:

[0030] A method for preparing non-fired ceramsite using sludge gasification slag as raw material includes the following steps: The sludge gasification slag is crushed by a small jaw crusher, and particles with a diameter of 5-15 mm are screened out and placed in a granulator. Ordinary silicate cement, finely ground sludge gasification slag, fly ash, silica fume, and polycarboxylate superplasticizer are mixed evenly in a certain proportion and then uniformly added to the granulator. Mixing water is added in a spray manner, and the granulation time is 10 minutes. The coated non-fired ceramsite is cured in a natural environment at 20℃ and 60% relative humidity. The compressive strength, apparent density, bulk density, and water absorption rate are tested after 28 days and 90 days of curing.

[0031] Design of non-fired ceramsite formulation using sludge gasification residue as raw material (single granulator usage, unit: kg)

[0032] W20 3 0 0 0 0 0 W21 3 0.9 0 0 0 0 W22 3 0.45 0.45 0 0 0 W23 3 0.405 0.225 0.225 0.045 0.018 W24 3 0.6 0 0 0 0 W25 3 0.3 0.3 0 0 0 W26 3 0.27 0.15 0.15 0.03 0.012

[0033] Performance testing of non-fired ceramsite using sludge gasification residue as raw material

[0034]

[0035] like Figure 1 and 2 The figure shows a schematic diagram of the cross-section of the non-fired ceramsite after samples W11 and W14 have been cured for 90 days.

[0036] Example 3:

[0037] A method for preparing non-fired ceramsite using sludge gasification slag as raw material includes the following steps: The sludge gasification slag is crushed by a small jaw crusher, and particles with a diameter range of 10-25 mm are screened out and placed in a granulator. Ordinary silicate cement, finely ground sludge gasification slag, fly ash, silica fume, and polycarboxylate superplasticizer are mixed evenly in a certain proportion and then uniformly added to the granulator. Mixing water is added in a spray manner, and the granulation time is 25 minutes. After coating, the non-fired ceramsite is cured in a natural environment at 20℃ and 60% relative humidity. The compressive strength, apparent density, bulk density, and water absorption rate are tested after 28 days and 90 days of curing.

[0038] Design of non-fired ceramsite formulation using sludge gasification residue as raw material (single granulator usage, unit: kg)

[0039] W30 3 0 0 0 0 0 W31 3 0.9 0 0 0 0 W32 3 0.45 0.45 0 0 0 W33 3 0.405 0.225 0.225 0.045 0.018 W34 3 0.6 0 0 0 0 W35 3 0.3 0.3 0 0 0 W36 3 0.27 0.15 0.15 0.03 0.012

[0040] Performance testing of non-fired ceramsite using sludge gasification residue as raw material

[0041]

[0042] In this embodiment, the sludge gasification slag is the core of the non-fired ceramsite, and the outer coating powder generates a certain strength after hydration. When used as aggregate, it exhibits higher strength, which improves the homogeneity of the sludge gasification slag aggregate while maintaining its lightweight characteristics.

[0043] Example 4:

[0044] A method for preparing non-fired ceramsite using sludge gasification slag as raw material includes the following steps: The sludge gasification slag is crushed by a small jaw crusher, and particles with a diameter of 5-15 mm are screened out and placed in a granulator. Ordinary silicate cement, finely ground sludge gasification slag, and finely ground calcium carbide slag are mixed evenly in a certain proportion and then uniformly added to the granulator. Mixing water is added in a spray manner, and the granulation time is 25 minutes. After coating, the non-fired ceramsite is cured in a natural environment until the surface hardens, and then transferred to a carbonization environment with a carbon dioxide concentration of 50 VT% for further curing. The compressive strength, apparent density, bulk density, and water absorption rate are tested after 1 hour of carbonization curing and 3 days of curing.

[0045] Design of non-fired ceramsite formulation using sludge gasification residue as raw material (single granulator usage, unit: kg)

[0046] W40 3 0 0 0 W41 3 0.9 0 0 W42 3 0.45 0 0.45 W43 3 0.225 0.225 0.45 W44 3 0 0 0.9 W45 3 0.6 0 0 W46 3 0.3 0 0.3 W47 3 0.15 0.15 0.3 W48 3 0 0 0.6

[0047] Performance testing of non-fired ceramsite using sludge gasification residue as raw material

[0048]

[0049] In this embodiment, the sludge gasification slag is the core of the non-fired ceramsite. The outer coating powder generates a certain strength after undergoing hydration or carbonization reactions in a natural or carbonization environment. When used as aggregate, it exhibits higher strength, improves the homogeneity of the sludge gasification slag aggregate, and maintains its lightweight characteristics.

[0050] The above four embodiments are not intended to limit the shape, material, structure, etc. of the present invention in any way. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing non-fired ceramsite using sludge gasification slag as raw material, characterized in that: Includes the following steps: (1) The sludge gasification residue is crushed using a crusher, and particles with a diameter of 5-25mm are screened out as the core of the non-fired ceramsite. (2) The particles and powders with a particle size of less than 5 mm remaining after sieving are ground in a ball mill until the specific surface area is more than 100 m² / kg to obtain finely ground sludge gasification slag powder, which is used as a component material of the coating powder. (3) Preparation of coating powder; by mass parts, the coating powder includes the following raw materials: 0.405 parts of ordinary silicate cement, 0.225 parts of finely ground sludge gasification slag, 0.225 parts of fly ash, 0.045 parts of silica fume, and 0.018 parts of polycarboxylate superplasticizer; (4) Mix the kernel prepared in step (1) with the shell powder prepared in step (3) to form a granular powder mixture. The mixing weight ratio of the kernel to the shell powder is 10:1 to 15:

1. (5) Add water to the granule-powder mixture and mix until the coating is uniform. Add the mixing water in the form of a spray. The granulation time is 10-25 minutes to obtain non-fired ceramsite of sludge gasification slag. (6) After the sludge gasification residue non-fired ceramsite is naturally cured or carbonized, its cylinder compressive strength, apparent density, bulk density and water absorption rate are tested.

2. The method for preparing non-fired ceramsite using sludge gasification slag as raw material according to claim 1, characterized in that: The natural curing conditions in step (6) are: after coating, the non-fired ceramsite is placed in a natural environment for curing for more than 28 days. The natural environment conditions are temperature 10~30℃ and relative humidity 40%~80%.

3. The method for preparing non-fired ceramsite using sludge gasification residue as raw material according to claim 1, characterized in that: The conditions for carbonization curing in step (6) are as follows: after coating, the non-fired ceramsite is placed in a carbonization environment for curing for more than 1 hour. The carbonization environment conditions are: carbon dioxide concentration of 10-100vt%, temperature of 10-30℃, and relative humidity of 40%-80%.

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