Method for co-stabilization of fly ash and sludge

Abstract

The present application relates to waste treatment and solidification technical field, disclose a kind of fly ash slag and sludge collaborative solidification treatment method, comprising the following steps: S1, raw material pretreatment: using centrifugal dehydrator fly ash is dewatered to moisture content is less than 10%, and by vibrating screen and jaw crusher fly ash and slag are treated to particle size is between 0.5-2 mm;Using belt filter press sludge is dewatered to moisture content is less than 30%, then in hot air drying furnace it is dried to moisture content is less than 10%;S2, raw material mixing: after pretreatment fly ash, slag and sludge are mixed according to set mass ratio;S3, add solidification agent: solidification agent is added to mixture, and is uniformly stirred.By optimizing proportioning and selecting suitable solidification agent, the problem of insufficient stability of solidified body and incomplete sealing of harmful substances is solved, and by raw material treatment, adding solidification agent and solidification agent optimization, the problem of poor heavy metal sealing effect and high processing cost is solved.

Description

Technical Field

[0001] This invention relates to the field of waste treatment and solidification technology, specifically a method for the synergistic stabilization treatment of fly ash, slag and sludge. Background Technology

[0002] Against the backdrop of environmental protection and resource utilization, the treatment of industrial wastes such as fly ash, slag, and sludge has become a key focus of current social concern. These wastes contain a large number of harmful components, such as heavy metals and organic pollutants, which can cause serious environmental pollution if not properly treated. Traditional treatment methods mainly include solidification and stabilization technologies, which aim to fix these harmful components in a solidified body through physical and chemical methods, thereby reducing their migration and release into the environment.

[0003] Existing solidification and stabilization technologies use cement, lime, and other solidifying agents to solidify fly ash, slag, and sludge into block materials. These methods, by adjusting the type and amount of solidifying agent and controlling the solidification and curing conditions, enable the solidified blocks to possess certain physical and mechanical properties and chemical stability, thereby reducing the leaching of heavy metals.

[0004] However, due to the complex and highly variable composition of waste, traditional solidification methods still face many challenges in terms of the long-term stability and effectiveness of the solidified body when treating these wastes. Traditional solidification methods have limited effect on the sequestration of heavy metals, and the treated solidified body is prone to a decrease in strength and an increase in heavy metal leaching during long-term use. In addition, the large consumption of solidifying agents and the high treatment cost are also major drawbacks of traditional methods, especially when treating large-scale industrial wastes. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for the synergistic stabilization treatment of fly ash slag and sludge, which solves the problems of insufficient stability of the solidified body and incomplete sealing of harmful substances in existing technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a method for the synergistic stabilization treatment of fly ash slag and sludge, comprising the following steps:

[0007] S1. Raw material pretreatment:

[0008] The fly ash is dehydrated to a moisture content of less than 10% using a centrifugal dewatering machine, and the fly ash and slag are processed to a particle size of 0.5-2 mm using a vibrating screen and a jaw crusher.

[0009] The sludge is dewatered to a moisture content of less than 30% using a belt filter press, and then dried to a moisture content of less than 10% in a hot air drying oven.

[0010] S2, Raw material mixing:

[0011] The pretreated fly ash, slag and sludge are mixed according to the set mass ratio;

[0012] S3. Add curing agent:

[0013] Add the curing agent to the mixture and stir evenly;

[0014] S4. Curing and Maintenance:

[0015] The mixture was pressed into shape and cured for 28 days at 20°C±2°C and 60% humidity.

[0016] Preferably, the mass ratio of fly ash, slag, and sludge is:

[0017] F:R:S=40:30:30

[0018] Where F is the mass of fly ash, R is the mass of slag, and S is the mass of sludge.

[0019] Preferably, the curing agent is selected from one of the following: cement, lime, bentonite, and the ratio (C) of the mass of the curing agent to the mass of fly ash is:

[0020] C=

[0021] in, For the quality of the curing agent, For fly ash mass, 10% ≤ C ≤ 15%.

[0022] Preferably, the raw material processing procedure includes:

[0023] The activation is performed using a ball mill for 30-60 minutes at a speed of 400 RPM.

[0024] Alternatively, use a vibratory mixer to mix for 20 minutes at a speed of 500 RPM.

[0025] Preferably, the process of adding the curing agent includes:

[0026] Use a high-shear mixer at a speed of 2000 RPM for 15 minutes;

[0027] The treatment was performed using an ultrasonic processor with a power of 200W for 10 minutes.

[0028] Preferably, the mold pressure during the molding of the cured block is the ratio of the force applied during the molding process to the mold area.

[0029] Preferably, the compressive strength test of the solidified block is performed using a compression testing machine with a loading rate of 1 mm / min, and the compressive strength of the test sample should reach ≥10 MPa.

[0030] Preferably, the heavy metal content of the solidified block is tested using an atomic absorption spectrometer, and the test items include heavy metals such as Pb, Cd, and Cr.

[0031] Preferably, during the curing and maintenance process, the ambient temperature is maintained at 20°C ± 2°C and the humidity is maintained within the range of 60% ± 5%.

[0032] Preferably, the chemical stability of the cured block after the 28-day curing period is tested by the following indicators:

[0033] pH value: The pH value of the test sample should be in the range of 6.5 to 8.5;

[0034] Leachate testing: Heavy metal testing is performed on the leachate.

[0035] This invention provides a method for the co-stabilization treatment of fly ash, slag, and sludge. It has the following beneficial effects:

[0036] 1. This invention, through optimized formulation design and selection of suitable curing agents, effectively improves the curing effect of fly ash, slag, and sludge, solving the problem of insufficient stability of the cured body after treatment. This method ensures that the physical and mechanical properties of the cured body meet the expected standards, enhances its stability during long-term use, and thus effectively seals harmful components in waste, reducing the risk of heavy metal leaching.

[0037] 2. This invention, through raw material processing technology and the addition of curing agents, significantly improves the efficiency of the curing reaction and solves the problem of ineffective heavy metal sequestration in traditional methods. The cured block meets national environmental protection standards in terms of chemical stability and physical and mechanical properties, greatly reducing the risk of secondary pollution to soil and water bodies and protecting the ecological environment.

[0038] 3. By optimizing the amount of solidifying agent used and improving the utilization rate of waste resources, this invention reduces the consumption of solidifying agent and the overall treatment cost, solving the problem of high cost in traditional treatment methods. This method not only improves treatment efficiency but also reduces the volume of waste and the difficulty of treatment, achieving a more economical and efficient waste treatment process. Attached Figure Description

[0039] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.

[0041] Please see the appendix Figure 1 This invention relates to a method for the synergistic stabilization treatment of fly ash, slag, and sludge, aiming to effectively reduce the migration capacity of harmful substances in fly ash, slag, and sludge, and to prepare a solidified material with high strength and good stability. The method includes the following steps:

[0042] Step S1: Raw material pretreatment

[0043] Pretreatment of fly ash:

[0044] The collected fly ash is dehydrated using a centrifugal dewatering machine to reduce its moisture content to below 10%. This process helps improve the workability of the fly ash and the subsequent mixing effect.

[0045] After dehydration, the fly ash undergoes particle size control using a vibrating screen and a jaw crusher to ensure that the particle size is between 0.5-2 mm. This particle size range helps to enhance the overall uniformity of the solidified material.

[0046] Sludge pretreatment:

[0047] A belt filter press is used to perform preliminary dewatering of the sludge, reducing its moisture content to below 30%.

[0048] The dewatered sludge is then fed into a hot air drying oven for further drying until its moisture content is reduced to below 10%. The dried sludge has better fluidity and mixability, which is beneficial for subsequent stabilization treatment.

[0049] Step S2: Mixing raw materials

[0050] The pretreated fly ash, slag, and sludge are mixed in a specific mass ratio of F:R:S = 40:30:30.

[0051] Where F represents the mass of fly ash, R represents the mass of slag, and S represents the mass of sludge. During the mixing process, it is essential to ensure that all components are evenly distributed to guarantee the consistent performance of the solidified blocks.

[0052] Step S3: Add curing agent

[0053] Add the curing agent to the mixture and stir evenly. The curing agent can be one of cement, lime, or bentonite, and the amount added is based on the mass of fly ash, with a ratio of 10% ≤ C ≤ 15%, where C represents the ratio of the mass of the curing agent to the mass of the fly ash. The formula is as follows:

[0054] C=

[0055] in, For the quality of the curing agent, For fly ash mass, 10% ≤ C ≤ 15%.

[0056] Step S4: Curing and Maintenance

[0057] forming:

[0058] The uniformly mixed materials are pressed into a solidified block using a mold. The mold pressure during solidification should be controlled within an appropriate range to ensure the density and strength of the solidified block.

[0059] Maintenance:

[0060] The cured block was placed in an environment at 20°C±2°C and 60%±5% humidity for 28 days. During the curing process, the environment should be kept stable to ensure that the chemical reaction within the cured block proceeds fully, thereby achieving the expected physical and chemical properties.

[0061] Step S5: Performance testing of the cured block

[0062] Compressive strength test:

[0063] The compressive strength of the cured block was tested using a compression testing machine at a loading rate of 1 mm / min. The test results show that the compressive strength of the cured block should reach ≥10 MPa to ensure sufficient mechanical properties for use in engineering applications.

[0064] Heavy metal content test:

[0065] Atomic absorption spectrometry was used to detect potential heavy metals such as Pb, Cd, and Cr in the cured blocks. This test was primarily to ensure the environmental friendliness and safety of the cured blocks and to prevent secondary pollution to the environment during practical applications.

[0066] Optional enhancement processing steps

[0067] Before the raw materials are mixed or cured, the following enhancement treatments can be performed according to specific needs to improve the performance of the cured block:

[0068] Raw material processing:

[0069] The mixture was activated using a ball mill for 30-60 minutes at a speed of 400 RPM.

[0070] Alternatively, a vibratory mixer can be used for mechanical mixing for 20 minutes at a speed of 500 RPM.

[0071] Add curing agent:

[0072] The mixture was processed using a high-shear mixer, with the mixing speed set to 2000 RPM and the mixing time set to 15 minutes.

[0073] An ultrasonic processor with a power of 200W and a processing time of 10 minutes can also be used. These methods help enhance the homogeneity of the components within the mixture and the reaction rate, thereby further improving the performance of the cured block.

[0074] Chemical stability test of cured block

[0075] After the curing period, the chemical stability of the cured block is evaluated, mainly through testing the following indicators:

[0076] pH value test:

[0077] The pH value of the cured block should be tested and the result should be within the range of 6.5 to 8.5 to ensure its chemical stability and that it will not have a negative impact on the environment.

[0078] Leachate testing:

[0079] The solidified blocks are subjected to leaching liquid heavy metal testing to ensure that heavy metals in the solidified blocks will not be released during use, thereby meeting environmental protection standards.

[0080] Example 1: Treatment method steps based on cement hardener:

[0081] Raw material pretreatment:

[0082] Fly ash: Use a centrifugal dewatering machine (3500 RPM) for 20 minutes to reduce the moisture content of fly ash to below 10%.

[0083] Slag: Use a jaw crusher to process the slag to a particle size of 0.5-2 mm.

[0084] Sludge: Dewatered to a moisture content of less than 30% using a belt filter press (pressure 0.9 MPa), and then dried to less than 10% in a hot air drying oven (80°C, 12 hours).

[0085] Raw material mixing:

[0086] Ratio: fly ash: slag: sludge = 40:30:30.

[0087] Mix: Mix for 20 minutes using a high-efficiency mixer (500 RPM).

[0088] Add curing agent:

[0089] Hardener: Cement, the mass ratio of hardener to fly ash is 12%.

[0090] Add cement evenly to the mixture and stir for 10 minutes.

[0091] Curing and maintenance:

[0092] Curing: Fill the mold with the mixture, apply a pressure of 2 MPa, and press for 5 minutes.

[0093] Maintenance: Maintain at 20°C±2°C and 60% humidity for 28 days.

[0094] Process parameters:

[0095] Raw material processing: Use a ball mill at a speed of 400 RPM for 45 minutes.

[0096] Add curing agent: Use a high-shear mixer at a speed of 2000 RPM for 15 minutes.

[0097] Example 2: Treatment method based on lime solidifying agent

[0098] step:

[0099] Raw material pretreatment:

[0100] Fly ash: Use a centrifugal dewatering machine (4000 RPM) to treat for 15 minutes to reduce the moisture content of fly ash to below 10%.

[0101] Slag: The slag is screened using a vibrating screen (2 mm aperture).

[0102] Sludge: Dewatered to a moisture content of less than 25% using a belt filter press (pressure 1.0 MPa), and then dried to less than 10% in a hot air drying oven (85°C, 10 hours).

[0103] Raw material mixing:

[0104] Ratio: fly ash: slag: sludge = 35:35:30.

[0105] Mixing: Use a vibratory mixer at 500 RPM for 25 minutes.

[0106] Add curing agent:

[0107] Hardener: Lime, the mass ratio of hardener to fly ash is 10%.

[0108] Add lime evenly to the mixture and stir for 15 minutes.

[0109] Curing and maintenance:

[0110] Curing: Fill the mold with the mixture, apply a pressure of 1.5 MPa, and press for 6 minutes.

[0111] Maintenance: Maintain at 20°C±2°C and 60% humidity for 28 days.

[0112] Process parameters:

[0113] Raw material processing: Use a vibratory mixer at a speed of 500 RPM for 30 minutes.

[0114] Add curing agent: Use an ultrasonic processor with a power of 200W and a processing time of 12 minutes.

[0115] Example 3: Treatment method based on bentonite solidifier

[0116] step:

[0117] Raw material pretreatment:

[0118] Fly ash: Use a centrifugal dewatering machine (3500 RPM) for 25 minutes to reduce the moisture content of fly ash to below 10%.

[0119] Slag: Use a jaw crusher to process the slag to a particle size of 0.5-2 mm.

[0120] Sludge: Dewatered to a moisture content of less than 35% using a belt filter press (pressure 0.8 MPa), and then dried to less than 10% in a hot air drying oven (75°C, 15 hours).

[0121] Raw material mixing:

[0122] Ratio: fly ash: slag: sludge = 40:30:30.

[0123] Mixing: Use a high-efficiency mixer at 500 RPM for 20 minutes.

[0124] Add curing agent:

[0125] Hardener: Bentonite, the mass ratio of hardener to fly ash is 15%.

[0126] Add: Add bentonite evenly to the mixture and stir for 10 minutes.

[0127] Curing and maintenance:

[0128] Curing: Fill the mold with the mixture, apply a pressure of 3 MPa, and press for 4 minutes.

[0129] Maintenance: Maintain at 20°C±2°C and 60% humidity for 28 days.

[0130] Process parameters:

[0131] Raw material processing: Use a ball mill at a speed of 400 RPM for 50 minutes.

[0132] Add curing agent: Use a high-shear mixer at a speed of 2000 RPM for 15 minutes.

[0133] Comparative experimental design

[0134] Experimental objective: To compare the effects of different solidifying agents (cement, lime, bentonite) on the synergistic stabilization treatment of fly ash, slag and sludge, and to evaluate their performance in terms of compressive strength, heavy metal stability and environmental standards.

[0135] Experimental conditions:

[0136] Hardeners: cement, lime, bentonite

[0137] Hardener mass ratio: 10%-15% of fly ash

[0138] Curing and maintenance conditions: 20°C±2°C, 60% humidity, curing for 28 days.

[0139] Experimental data table:

[0140] Example curing agent curing agent to fly ash mass ratio Compressive strength (MPa) pH value Pb (mg / kg) Cd (mg / kg) Cr (mg / kg) Concentration of heavy metal leachate (mg / L) Example 1 cement 12% 12.5 7.2 20 0.5 25 0.01 Example 2 lime 10% 10.2 7.5 25 0.8 28 0.02 Example 3 Bentonite 15% 11.8 7.0 18 0.4 22 0.015 Comparative experiment No curing agent N / A 5.0 6.8 60 1.5 55 0.05

[0141] According to the table, Example 1 (cement curing agent) showed the best compressive strength (12.5 MPa), superior to Example 2 (lime curing agent, 10.2 MPa) and Example 3 (bentonite curing agent, 11.8 MPa), indicating that the cement curing agent was the most effective in improving the strength of the cured block. The pH values ​​of all examples were within the range of 6.5 to 8.5, meeting environmental standards. Example 2 (lime curing agent) had a slightly higher pH value (7.5), which helped stabilize the curing of harmful substances. The heavy metal content of Examples 1 (cement curing agent) and Example 3 (bentonite curing agent) was lower than that of Example 2 (lime curing agent), indicating that cement and bentonite had better stabilizing effects on heavy metals. The heavy metal leachate concentration of all examples was below 0.05 mg / L, with Example 1 (cement curing agent) showing the best performance (0.01 mg / L), demonstrating the advantage of the cement curing agent in reducing heavy metal leaching.

[0142] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the co-stabilization treatment of fly ash slag and sludge, characterized in that, Includes the following steps: S1. Raw material pretreatment: The fly ash is dehydrated to a moisture content of less than 10% using a centrifugal dewatering machine, and the fly ash and slag are processed to a particle size of 0.5-2 mm using a vibrating screen and a jaw crusher. The sludge is dewatered using a belt filter press to a moisture content of less than 30%, and then dried in a hot air dryer to a moisture content of less than 10%. S2, Raw material mixing: The pretreated fly ash, slag and sludge are mixed according to the set mass ratio; S3. Add curing agent: Add the curing agent to the mixture and stir evenly; S4. Curing and Maintenance: The mixture was pressed into shape and cured for 28 days at 20°C±2°C and 60% humidity. The mass ratio of fly ash, slag, and sludge is: F : R : S =40:30:30 in, F For fly ash quality, R For the quality of slag, S For sludge quality; The curing agent can be selected from one of the following: cement, lime, or bentonite, and the ratio of the mass of the curing agent to the mass of fly ash is ( C )for: C= in, For the quality of the curing agent, For fly ash quality, 10%≤C≤15%； The process of adding the curing agent includes: Use a high-shear mixer at a speed of 2000 RPM for 15 minutes; The treatment was performed using an ultrasonic processor with a power of 200W for 10 minutes.

2. The method for co-stabilizing fly ash slag and sludge according to claim 1, characterized in that, Before the raw materials are mixed or cured, the following reinforcement treatments can be performed according to specific requirements. The reinforcement treatment process includes: The activation is performed using a ball mill for 30-60 minutes at a speed of 400 RPM. Alternatively, use a vibratory mixer to mix for 20 minutes at a speed of 500 RPM.

3. The method for co-stabilizing fly ash slag and sludge according to claim 1, characterized in that, The mold pressure during the molding of the cured block is the ratio of the force applied during the molding process to the mold area.

4. The method for co-stabilizing fly ash slag and sludge according to claim 1, characterized in that, The compressive strength of the solidified block was tested using a compression testing machine with a loading rate of 1 mm / min. The compressive strength of the test sample should reach ≥10 MPa.

5. The method for co-stabilizing fly ash slag and sludge according to claim 1, characterized in that, The heavy metal content of the solidified block was tested using an atomic absorption spectrometer, and the test items included Pb, Cd, and Cr heavy metals.

6. The method for co-stabilizing fly ash slag and sludge according to claim 1, characterized in that, The chemical stability of the cured block after the 28-day curing period was tested for the following indicators: pH value: The pH value of the test sample should be in the range of 6.5 to 8.5; Leachate testing: Heavy metal testing is performed on the leachate.

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