A binder used in fly ash combustion and its preparation method

Abstract

This invention discloses a binder for use in fly ash combustion and its preparation method. The binder comprises the following raw materials in the following mass percentages: sodium silicate pentahydrate 20.37~30.30%, borax 0.91~2.44%, boric acid 0.60~1.63%, phosphate 0.30~2.12%, potassium silicate 2.03~3.55%, sodium silicate 4.02~7.06%, sodium dihydrogen phosphate 0.60~1.21%, surfactant 0.91~1.21%, and deionized water 50.61~61.10%. The preparation method of the binder includes raw material pretreatment, mixing reaction, and post-treatment steps. This invention utilizes the synergistic effect of sodium silicate and potassium silicate to form a dense silicon-oxygen network structure, reducing moisture penetration channels. The prepared adhesive, after being placed in an 80% humidity environment for 72 hours, exhibits a moisture absorption rate of ≤3%, far lower than traditional adhesive products. Leveraging the reaction characteristics of boric acid, borax, and phosphate, no additional curing agent is required; it can self-crosslink and cure at room temperature, achieving a compressive strength of 11.8 MPa after 24 hours. The components of this adhesive exhibit excellent compatibility, with a shelf life exceeding 5 months. The raw materials used in this method are simple and readily available, and the reaction conditions are mild, making it suitable for large-scale production.

Description

Technical Field

[0001] This invention relates to the field of pellet production technology in the steel industry, and more specifically, to a binder used in fly ash combustion and its preparation method. Background Technology

[0002] Fly ash is a major solid waste generated by coal-fired power plants. Its large-scale storage not only occupies land but also poses a potential environmental pollution risk. How to utilize fly ash for resource recovery and high-value-added purposes has become an important research direction. One effective way to achieve large-scale utilization and energy use is to process fly ash into shaped coal, shaped coke, or other products through molding and combustion processes. In my country, fly ash is mainly used in building materials, road engineering, backfilling, agriculture, and mineral extraction. In the building materials industry, fly ash is mainly used in the production of cement, commercial concrete, and new wall materials such as fly ash bricks and aerated concrete products. In road construction, fly ash is mainly used as a roadbed and as an admixture for road surface concrete. In agriculture, fly ash is mainly used for soil improvement. In mineral extraction, fly ash can be used to extract alumina and silica, and for iron and carbon extraction.

[0003] In the process of forming and applying fly ash, the performance of the binder is crucial, as it directly determines the performance of the fly ash molded products. However, existing binders mainly have the following shortcomings: (1) Poor moisture resistance: They are prone to absorbing moisture in high humidity environments, which leads to a decrease in strength; (2) Curing depends on external conditions: Curing agents need to be added or curing can be promoted by heating, introducing gas, etc., which increases the complexity of the process and production costs; (3) Insufficient component stability: The compatibility of each component is poor, and it is easy to separate into layers during long-term storage, which affects the use effect.

[0004] Currently, binders used in fly ash molding mainly include inorganic binders, organic binders, and composite binders. Inorganic binders are gradually gaining attention due to their advantages such as environmental friendliness and low cost, but balancing their moisture resistance and self-curing properties remains a technical challenge. Among existing technologies, sodium silicate-based binders have poor moisture resistance, while borate-based binders have slow curing speeds. There is an urgent need to develop a new type of inorganic binder that combines high moisture resistance, self-curing function, and simple processing. Summary of the Invention

[0005] In view of the above, the present invention provides a binder for use in fly ash combustion and a method for preparing the same. By optimizing the component design and preparation process, the binder achieves improved moisture resistance, self-curing function, and simplified process.

[0006] This invention provides a binder for use in fly ash combustion, comprising the following raw materials by mass percentage: sodium silicate pentahydrate 20.37~30.30%, borax 0.91~2.44%, boric acid 0.60~1.63%, phosphate 0.30~2.12%, potassium silicate 2.03~3.55%, sodium silicate 4.02~7.06%, sodium dihydrogen phosphate 0.60~1.21%, surfactant 0.91~1.21%, and deionized water 50.61~61.10%.

[0007] Among them, the synergistic effect of sodium silicate and potassium silicate forms a dense silicon-oxygen network structure, reducing moisture penetration channels and significantly improving the adhesive's moisture resistance; by utilizing the reaction characteristics of boric acid, borax and phosphate, no additional curing agent is needed, and it can self-crosslink and cure at room temperature, giving the adhesive self-curing properties and significantly improving the adhesive's compressive strength.

[0008] Optionally, the phosphate is one or more of aluminum dihydrogen phosphate, sodium phosphate, and ammonium dihydrogen phosphate.

[0009] Optionally, the surfactant is at least one of sodium fatty alcohol acyl sulfate and alcohol ether phosphate; wherein the alcohol ether phosphate includes at least one of potassium alcohol ether phosphate and sodium alcohol ether phosphate.

[0010] Preferably, the surfactant is a mixture of sodium fatty alcohol sulfate and alcohol ether phosphate, and the mass ratio of sodium fatty alcohol sulfate to alcohol ether phosphate is 1:0.5~2.

[0011] This invention also provides a method for preparing a binder for use in fly ash combustion, comprising the following steps:

[0012] (1) Raw material pretreatment: Add material A to deionized water and stir at 40~60℃ until completely dissolved to obtain sodium silicate solution; put material B into a ball mill and grind to a particle size of 100~200 mesh to obtain pretreated material B; wherein, material A is sodium silicate pentahydrate and material B is a mixture of borax, boric acid and phosphate.

[0013] (2) Mixing reaction: Add S material and the pretreated B material to the sodium silicate solution in sequence, and react for 1 to 3 hours at a temperature of 50 to 80°C and a stirring speed of 300 to 600 r / min; wherein, S material is a mixture of potassium silicate and sodium silicate.

[0014] (3) Post-processing: Add Z material and K material to the reaction system obtained in step (2), continue stirring for 30~60min, cool to room temperature and let stand for 2~4h to obtain the binder; wherein, Z material is sodium dihydrogen phosphate and K material is surfactant solution.

[0015] In step (1), the mass concentration of sodium silicate solution is 20-40%.

[0016] Preferably, the mass concentration of the sodium silicate solution in step (1) is 25-35%, and the particle size of the pretreated material B is preferably 150 mesh.

[0017] In step (1), the mass ratio of borax, boric acid and phosphate in material B is 3:2:1.

[0018] In step (2), the mass ratio of potassium silicate to sodium silicate in the S material is 1:2.

[0019] In steps (1) and (2), the mass ratio of material A, material S, and material B is 100:20~50:6~30.

[0020] Preferably, the reaction temperature of the mixing reaction in step (2) is 60~70℃, the stirring speed is 400~500r / min, and the reaction time is 1.5~2.5h.

[0021] In steps (2) and (3), the mass ratio of Z material to B material is 1:3~5.

[0022] Optionally, in step (3), K is an aqueous solution of at least one of sodium fatty alcohol sulfate and alcohol ether phosphate.

[0023] Preferably, the K material is a mixed aqueous solution of sodium fatty alcohol sulfate and alcohol ether phosphate, and the mass ratio of sodium fatty alcohol sulfate to alcohol ether phosphate is 1:0.5~2; the mass concentration of the K material is 10~40%.

[0024] Compared with the prior art, the technical solution of this application has at least the following beneficial effects:

[0025] This invention solves the problems of poor moisture resistance, the need for additional curing agents, and complex preparation processes in traditional foundry sand binders by optimizing the proportions of each component and the reaction conditions, utilizing the cross-linking properties of silicon-oxygen bonds and the self-curing properties of borate. Specifically, sodium silicate and potassium silicate work synergistically to form a dense silicon-oxygen network structure, reducing moisture penetration channels. The prepared binder, after being placed in an 80% humidity environment for 72 hours, has a moisture absorption rate of ≤3%, far lower than traditional binder products. Utilizing the reaction characteristics of boric acid, borax, and phosphate, no additional curing agent is needed; it can self-crosslink and cure at room temperature, achieving a compressive strength of 11.8 MPa after 24 hours. The binder prepared by this invention exhibits excellent compatibility among its components and a shelf life of over 5 months. Compared with traditional processes, the raw materials used are simple and readily available, the preparation process does not require high temperature and high pressure, the reaction conditions are mild, making it suitable for large-scale production, and it simplifies the foundry sand preparation process, improving the stability of casting quality. Detailed Implementation

[0026] The embodiments of this application will now be described in more detail. This application can be implemented in various forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to provide a more thorough and complete understanding of the application. It should be understood that the embodiments of this application are for illustrative purposes only and are not intended to limit the scope of protection of this application.

[0027] Example 1:

[0028] 1. A binder for use in fly ash combustion, comprising the following raw materials by mass percentage: 30.21% sodium silicate pentahydrate, 0.91% borax, 0.60% boric acid, 0.30% aluminum dihydrogen phosphate, 2.03% potassium silicate, 4.02% sodium silicate, 0.60% sodium dihydrogen phosphate, 0.91% sodium fatty alcohol sulfate, and 60.42% deionized water.

[0029] 2. A method for preparing a binder used in fly ash combustion, specifically comprising the following steps:

[0030] (1) Raw material pretreatment: 100g of material A (sodium silicate pentahydrate) was added to 200g of deionized water and stirred at 50℃ until completely dissolved to obtain a sodium silicate solution with a mass concentration of 33%; 6g of material B (borax 3g, boric acid 2g, aluminum dihydrogen phosphate 1g) was put into a ball mill and ground through a 150-mesh sieve to obtain pretreated material B;

[0031] (2) Mixed reaction: Add 20g of S material (6.7g of potassium silicate and 13.3g of sodium silicate) to the sodium silicate solution obtained in step (1), stir evenly, add the pretreated B material, and react for 2h at a temperature of 60℃ and a stirring speed of 400r / min.

[0032] (3) Post-processing: Add 2g of Z material (sodium dihydrogen phosphate) and 7.5g of K material with a mass concentration of 40% to the reaction system obtained in step (2). K material is a sodium fatty alcohol sulfate solution. Continue stirring for 45min, cool to room temperature and let stand for 3h to obtain the binder.

[0033] Example 2:

[0034] 1. A binder for use in fly ash combustion, comprising the following raw materials by mass percentage: 20.37% sodium silicate pentahydrate, 2.44% borax, 1.63% boric acid, 2.04% sodium phosphate, 3.40% potassium silicate, 6.78% sodium silicate, 1.22% sodium dihydrogen phosphate, 1.02% alcohol ether phosphate, and 61.10% deionized water; wherein the alcohol ether phosphate is potassium alcohol ether phosphate ester.

[0035] 2. A method for preparing a binder used in fly ash combustion, specifically comprising the following steps:

[0036] (1) Raw material pretreatment: 100g of material A (sodium silicate pentahydrate) was added to 300g of deionized water and stirred at 40℃ until completely dissolved to obtain a sodium silicate solution with a mass concentration of 25%; 30g of material B (borax 12g, boric acid 8g, sodium phosphate 10g) was ground in a ball mill and passed through a 100-mesh sieve to obtain pretreated material B;

[0037] (2) Mixed reaction: Add 50g of S material (16.7g of potassium silicate and 33.3g of sodium silicate) to the sodium silicate solution obtained in step (1), stir evenly, add the pretreated B material, and react for 1.5h at a temperature of 70℃ and a stirring speed of 500r / min.

[0038] (3) Post-processing: Add 6g of Z material (sodium dihydrogen phosphate) and 25g of K material with a mass concentration of 20% to the reaction system obtained in step (2). K material is an alcohol ether phosphate solution and alcohol ether phosphate is potassium alcohol ether phosphate. Continue stirring for 60min, cool to room temperature and let stand for 4h to obtain the binder.

[0039] Example 3:

[0040] 1. A binder for use in fly ash combustion, comprising the following raw materials by mass percentage: 30.30% sodium silicate pentahydrate, 2.42% borax, 1.52% boric acid, 2.12% ammonium dihydrogen phosphate, 3.55% potassium silicate, 7.06% sodium silicate, 1.21% sodium dihydrogen phosphate, 1.21% surfactant, and 50.61% deionized water; wherein the surfactant is a mixture of sodium fatty alcohol acyl sulfate and alcohol ether phosphate, and the mass ratio of sodium fatty alcohol acyl sulfate to alcohol ether phosphate is 1:1; wherein the alcohol ether phosphate is sodium alcohol ether phosphate ester.

[0041] 2. A method for preparing a binder used in fly ash combustion, specifically comprising the following steps:

[0042] (1) Raw material pretreatment: 100g of material A (sodium silicate pentahydrate) was added to 167g of deionized water and stirred at 60℃ until completely dissolved to obtain a sodium silicate solution with a mass concentration of 37.5%; 20g of material B (8g of borax, 5g of boric acid, and 7g of ammonium dihydrogen phosphate) was ground in a ball mill and passed through a 200-mesh sieve to obtain pretreated material B;

[0043] (2) Mixed reaction: Add 35g of S material (11.7g of potassium silicate and 23.3g of sodium silicate) to the sodium silicate solution obtained in step (1), stir evenly, add the pretreated B material, and react for 3h at a temperature of 50℃ and a stirring speed of 300r / min.

[0044] (3) Post-processing: Add 4g of Z material (sodium dihydrogen phosphate) and 40g of K material with a mass concentration of 10% to the reaction system obtained in step (2). K material is a mixed aqueous solution of sodium fatty alcohol sulfate and alcohol ether phosphate, and the mass ratio of sodium fatty alcohol sulfate to alcohol ether phosphate is 1:1. The alcohol ether phosphate is sodium alcohol ether phosphate ester. Continue stirring for 30min, cool to room temperature and let stand for 2h to obtain the binder.

[0045] The adhesives prepared in Examples 1-3 of this invention were subjected to performance tests. As shown in Table 1, the adhesives prepared in this invention, after being placed in an environment with 80% humidity for 72 hours, exhibited a moisture absorption rate of ≤3%, significantly lower than that of traditional adhesive products. The 24-hour compressive strengths of the adhesives prepared in Examples 1-3 were 10.2 MPa, 8.5 MPa, and 11.8 MPa, respectively, indicating that the adhesives provided by this invention do not require additional curing agents and can self-crosslink and cure at room temperature. The storage periods of the adhesives prepared in Examples 1-3 were 6 months, 6 months, and 7 months, respectively, all exceeding 5 months, indicating excellent compatibility among the adhesive components.

[0046] Table 1. Performance test results of the adhesive of the present invention

[0047]

[0048] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

Claims

1. A binder for use in the combustion of fly ash, characterized in that, The raw materials, calculated by mass percentage, include the following components: sodium silicate pentahydrate 20.37~30.30%, borax 0.91~2.44%, boric acid 0.60~1.63%, phosphate 0.30~2.12%, potassium silicate 2.03~3.55%, sodium silicate 4.02~7.06%, sodium dihydrogen phosphate 0.60~1.21%, surfactant 0.91~1.21%, and deionized water 50.61~61.10%.

2. The method for preparing a binder for use in fly ash combustion according to claim 1, characterized by, The phosphate is one or more of aluminum dihydrogen phosphate, sodium phosphate, and ammonium dihydrogen phosphate.

3. The method for preparing a binder for use in fly ash combustion according to claim 1, characterized by, The surfactant is at least one of sodium fatty alcohol acyl sulfate and alcohol ether phosphate; wherein the alcohol ether phosphate includes at least one of potassium alcohol ether phosphate and sodium alcohol ether phosphate.

4. The method for preparing a binder for use in fly ash combustion according to claim 3, characterized by, The surfactant is a mixture of sodium fatty alcohol sulfate and alcohol ether phosphate, and the mass ratio of sodium fatty alcohol sulfate to alcohol ether phosphate is 1:0.5~2.

5. A method for preparing the binder for use in the combustion of fly ash according to any one of claims 1 to 4, characterized by, Includes the following steps: (1) Raw material pretreatment: Add material A to deionized water and stir at 40~60℃ until completely dissolved to obtain sodium silicate solution; put material B into a ball mill and grind to a particle size of 100~200 mesh to obtain pretreated material B; wherein, material A is sodium silicate pentahydrate and material B is a mixture of borax, boric acid and phosphate. (2) Mixing reaction: Add S material and the pretreated B material to the sodium silicate solution in sequence, and react for 1 to 3 hours at a temperature of 50 to 80°C and a stirring speed of 300 to 600 r / min; wherein, S material is a mixture of potassium silicate and sodium silicate. (3) Post-processing: Add Z material and K material to the reaction system obtained in step (2), continue stirring for 30~60min, cool to room temperature and let stand for 2~4h to obtain the binder; wherein, Z material is sodium dihydrogen phosphate and K material is surfactant solution.

6. The method for preparing the binder for use in fly ash combustion according to claim 5, characterized in that, The mass concentration of the sodium silicate solution in step (1) is 20-40%.

7. The method for preparing a binder for use in fly ash combustion according to claim 5, wherein In step (1), the preferred mass concentration of sodium silicate solution is 25-35%, and the preferred particle size of pretreated material B is 150 mesh.

8. The method for preparing a binder for use in fly ash combustion according to claim 5, wherein The mass ratio of borax, boric acid, and phosphate in material B of step (1) is 3:2:

1.

9. The method for preparing a binder for use in fly ash combustion according to claim 5, wherein In step (2), the mass ratio of potassium silicate to sodium silicate in the S material is 1:

2.

10. The method for preparing a binder for use in fly ash combustion according to claim 5, characterized by, In steps (1) and (2), the mass ratio of material A, material S, and material B is 100:20~50:6~30.

11. The method for preparing a binder for use in fly ash combustion according to claim 5, wherein The preferred reaction temperature for the mixing reaction in step (2) is 60~70℃, the preferred stirring speed is 400~500r / min, and the preferred reaction time is 1.5~2.5h.

12. The method for preparing a binder for use in fly ash combustion according to claim 5, wherein In steps (2) and (3), the mass ratio of Z material to B material is 1:3~5.

13. The method for preparing the binder for use in fly ash combustion according to claim 5, characterized in that, In step (3), K material is an aqueous solution of at least one of sodium fatty alcohol sulfate and alcohol ether phosphate.

14. The method for preparing a binder for use in fly ash combustion according to claim 13, wherein The K material is a mixed aqueous solution of sodium fatty alcohol sulfate and alcohol ether phosphate, and the mass ratio of sodium fatty alcohol sulfate to alcohol ether phosphate is 1:0.5~2; the mass concentration of the K material is 10~40%.

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