A kind of casting waste sand based compression-resistant regenerated sand and preparation method thereof

Abstract

The present invention relates to the technical field of regenerated sand, and discloses a foundry waste sand-based compressive regenerated sand and a preparation method thereof. The foundry waste sand is crushed, calcined for 1-2 hours at a temperature of 600-650° C., and ground to obtain regenerated sand. The regenerated sand, sodium silicate, silicate cement, basalt fiber, silane coupling agent KH-550, an additive, and epoxy nano-silica are mixed, stirred for 15-25 minutes at a temperature of 50-65° C., pressed and formed under a pressure of 10-15 MPa, cured, and sintered at 230° C. for 50 minutes to obtain the foundry waste sand-based compressive regenerated sand. The foundry waste sand-based compressive regenerated sand of the present invention has good compressive strength.

Description

Technical Field

[0001] The invention relates to the technical field of regenerated sand, in particular to waste foundry sand-based compression-resistant regenerated sand and a preparation method thereof. Background Art

[0002] Foundry waste sand, a major component of industrial solid waste, faces challenges with traditional treatment methods (such as landfill or simple recycling) due to low resource utilization and severe environmental pollution. Existing sand regeneration technologies primarily rely on thermal or chemical methods, but these methods suffer from insufficient compressive strength. Conventional regenerated sand relies on physical crushing or a single binder (such as resin), resulting in low compressive strength and difficulty meeting the high-strength requirements of foundry and construction applications. Furthermore, the process is complex and costly: thermal regeneration requires high-temperature calcination exceeding 800°C, resulting in high energy consumption; chemical regeneration requires large amounts of organic binders, increasing costs and poor temperature resistance. Summary of the Invention

[0003] (1) Technical problems solved

[0004] In view of the shortcomings of the existing technology, the present invention provides a foundry waste sand-based compression-resistant regenerated sand and a preparation method thereof, which has good compression resistance.

[0005] (2) Technical solution

[0006] To achieve the above objectives, the present invention provides the following technical solution: a compression-resistant regenerated sand based on foundry waste sand, comprising the following components by weight: 80-100 parts by weight of foundry waste sand, 1-1.5 parts by weight of sodium silicate, 0.8-1.6 parts by weight of Portland cement, 1-2 parts by weight of basalt fiber, 0.5-1 parts by weight of silane coupling agent KH-550, 1-2 parts by weight of additives, and 0.5-0.6 parts by weight of epoxy nano-silica.

[0007] Furthermore, the preparation method of the auxiliary agent is:

[0008] S1. Add 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and N,N-dimethylethylenediamine to N,N-dimethylformamide solvent, stir and mix, heat to 65-75°C for reaction, and then distill under reduced pressure, wash, and dry to obtain intermediate 1;

[0009] S2. Add 4-vinylbenzoyl chloride and intermediate 1 to 50-60 mL of N,N-dimethylformamide solvent, stir to dissolve, continue to add pyridine catalyst, react at 85-95 ° C for 4-6 hours, and then distill under reduced pressure and wash to obtain intermediate 2;

[0010] S3. Add intermediate 2 to 45-60 mL of N,N-dimethylformamide solvent, stir and disperse, then add thioglycolic acid and benzoin dimethyl ether photoinitiator, irradiate with 365 nm ultraviolet light at 25-40 ° C, centrifuge, wash and dry to obtain an auxiliary agent.

[0011] Furthermore, the usage ratio of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde, N,N-dimethylethylenediamine, and N,N-dimethylformamide solvent in S1 is 2.27-2.34 g: 0.92-1.1 g: 50-55 mL.

[0012] Furthermore, the reaction time in S1 is 4-6 hours.

[0013] Furthermore, the mass ratio of 4-vinylbenzoyl chloride, intermediate 1, and pyridine catalyst in S2 is 2.65-3.44 g: 3.14-3.26 g: 0.01-0.013 g.

[0014] Furthermore, the mass ratio of the intermediate 2, thioglycolic acid, and benzoin dimethyl ether photoinitiator in S3 is 1.2-1.4 g: 2.01-2.13 g: 0.02-0.03 g.

[0015] Furthermore, the irradiation time in S3 is 2-4 hours.

[0016] Furthermore, the preparation method of the foundry waste sand-based compressive regenerated sand is as follows: after crushing the foundry waste sand, roasting it at a temperature of 600-650°C for 1-2 hours, grinding it to obtain regenerated sand, mixing the regenerated sand, sodium silicate, silicate cement, basalt fiber, silane coupling agent KH-550, additives, and epoxy nano-silica, stirring it at a temperature of 50-65°C for 15-25 minutes, pressing it into shape at a pressure of 10-15MPa, curing it, and sintering it at 230°C for 50 minutes to obtain the foundry waste sand-based compressive regenerated sand.

[0017] (3) Beneficial technical effects

[0018] The invention crushes foundry waste sand, roasts it, and grinds it to obtain regenerated sand; then, the regenerated sand, sodium silicate, silicate cement, basalt fiber, silane coupling agent KH-550, additives, and epoxy nano-silica are mixed, stirred for 15-25 minutes, pressed into shape, cured, and sintered to obtain foundry waste sand-based compression-resistant regenerated sand.

[0019] Sodium silicate and silicate cement form calcium silicate gel through hydration reaction, which synergizes with the mechanical reinforcement of basalt fiber and the nano-filling effect of epoxy nano-silica to increase its compressive strength; during the stirring process, the epoxy groups of epoxy nano-silica will undergo ring-opening reaction with the carboxyl and tertiary amine groups in the additive, resulting in cross-linking. This cross-linked network restricts the free movement of molecular chains and reduces the porosity inside the regenerated sand, thereby increasing its mechanical properties while also reducing its water absorption rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is the NMR spectrum of the auxiliary agent in Example 1. DETAILED DESCRIPTION

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0022] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Preparation of epoxy nano-silica: Referring to the literature "Silane coupling agent KH-560 modified nano-silica", a certain amount of nano-silica was weighed and added to 20 mL of toluene. Ultrasonic dispersion was performed at room temperature using a KQ-300E ultrasonic cleaner (300W) for 30 minutes to obtain a uniform suspension. Silane coupling agent KH-560 was then added and ultrasonicated for 3-4 minutes. The suspension was then transferred to a 100 mL four-necked flask equipped with a reflux condenser and a power-enhanced electric stirrer and stirred in an oil bath at a set temperature for reaction. The slurry after the reaction was centrifuged at room temperature at 12,000 r / min using a CT15RT desktop high-speed refrigerated centrifuge to obtain epoxy nano-silica. Example 1

[0024] S1. Add 2.27 g of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and 0.92 g of N,N-dimethylethylenediamine to 50 mL of N,N-dimethylformamide, stir and mix, heat to 65°C and react for 4 h. After reaction, evaporate under reduced pressure, wash, and dry to obtain intermediate 1.

[0025]

[0026] S2. Add 2.65 g of 4-vinylbenzoyl chloride and 3.14 g of intermediate 1 to 50 mL of N,N-dimethylformamide solvent, stir and dissolve, then add 0.01 g of pyridine catalyst, react at 85°C for 4 h, and then distill under reduced pressure and wash to obtain intermediate 2;

[0027] S3. To 45 mL of N, N-dimethylformamide solvent was added 1.2 g of intermediate 2, stirred and dispersed, and then 2.01 g of thioglycolic acid and 0.02 g of benzoin dimethyl ether photoinitiator were added thereto. The mixture was irradiated with ultraviolet light at 365 nm for 2 h at 25 ° C. After the reaction, the mixture was centrifuged, washed and dried to obtain an additive.

[0028] S4. After crushing 80 parts by weight of foundry waste sand, calcining it at a temperature of 600°C for 1 hour, and grinding it to obtain regenerated sand, the regenerated sand, 1 part by weight of sodium silicate, 0.8 part by weight of silicate cement, 1 part by weight of basalt fiber, 0.5 part by weight of silane coupling agent KH-550, 1 part by weight of additives, and 0.5 part by weight of epoxy nano-silica were mixed, stirred at a temperature of 50°C for 15 minutes, pressed into shape at a pressure of 10 MPa, cured, and sintered at 230°C for 50 minutes to obtain foundry waste sand-based compressive regenerated sand. Example 2

[0029] S1. Add 2.34 g of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and 1.1 g of N,N-dimethylethylenediamine to 55 mL of N,N-dimethylformamide, stir and mix, heat to 75°C and react for 6 h. After reaction, evaporate under reduced pressure, wash, and dry to obtain Intermediate 1.

[0030] S2. 3.44 g of 4-vinylbenzoyl chloride and 3.26 g of intermediate 1 were added to 60 mL of N,N-dimethylformamide solvent and stirred to dissolve. 0.013 g of pyridine catalyst was then added and the mixture was reacted at 95°C for 6 h. After reaction, the mixture was distilled under reduced pressure and washed to obtain intermediate 2.

[0031] S3. To 60 mL of N, N-dimethylformamide solvent was added 1.4 g of intermediate 2, stirred and dispersed, and then 2.13 g of thioglycolic acid and 0.03 g of benzoin dimethyl ether photoinitiator were added thereto. The mixture was irradiated with ultraviolet light at 365 nm for 4 h at 40 ° C. After the reaction, the mixture was centrifuged, washed and dried to obtain an additive.

[0032] S4. After crushing 100 parts by weight of foundry waste sand, calcining it at a temperature of 50°C for 2h, and grinding it to obtain regenerated sand, the regenerated sand, 1.5 parts by weight of sodium silicate, 1.6 parts by weight of silicate cement, 2 parts by weight of basalt fiber, 1 part by weight of silane coupling agent KH-550, 2 parts by weight of additives, and 0.6 parts by weight of epoxy nano-silica were mixed, stirred at a temperature of 65°C for 25min, pressed into shape at a pressure of 15MPa, cured, and sintered at 230°C for 50min to obtain foundry waste sand-based compressive regenerated sand. Example 3

[0033] S1. Add 2.31 g of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and 1.02 g of N,N-dimethylethylenediamine to 53 mL of N,N-dimethylformamide, stir and mix, heat to 70°C and react for 5 h. After reaction, evaporate under reduced pressure, wash, and dry to obtain intermediate 1.

[0034] S2. 3.04 g of 4-vinylbenzoyl chloride and 3.22 g of intermediate 1 were added to 55 mL of N,N-dimethylformamide solvent and stirred to dissolve. 0.011 g of pyridine catalyst was then added and the mixture was reacted at 90°C for 5 h. After reaction, the mixture was distilled under reduced pressure and washed to obtain intermediate 2.

[0035] S3. To 50 mL of N, N-dimethylformamide solvent was added 1.3 g of intermediate 2, stirred and dispersed, and then 2.08 g of thioglycolic acid and 0.025 g of benzoin dimethyl ether photoinitiator were added thereto. The mixture was irradiated with ultraviolet light at 365 nm for 3 h at 30 ° C. After the reaction, the mixture was centrifuged, washed and dried to obtain an additive.

[0036] S4. After crushing 90 parts by weight of foundry waste sand, calcining it at a temperature of 620°C for 1.5 hours, grinding it to obtain regenerated sand, and mixing the regenerated sand, 1.2 parts by weight of sodium silicate, 1.3 parts by weight of silicate cement, 2 parts by weight of basalt fiber, 0.8 parts by weight of silane coupling agent KH-550, 1 part by weight of an additive, and 0.55 parts by weight of epoxy nano-silica. The mixture was stirred at a temperature of 60°C for 20 minutes, pressed into shape at a pressure of 13 MPa, cured, and sintered at 230°C for 50 minutes to obtain foundry waste sand-based compressive regenerated sand. Example 4

[0037] S1. Add 2.27 g of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and 0.92 g of N,N-dimethylethylenediamine to 50 mL of N,N-dimethylformamide, stir and mix, heat to 65°C and react for 4 h. After reaction, evaporate under reduced pressure, wash, and dry to obtain intermediate 1.

[0038] S2. Add 2.65 g of 4-vinylbenzoyl chloride and 3.14 g of intermediate 1 to 50 mL of N,N-dimethylformamide solvent, stir and dissolve, then add 0.01 g of pyridine catalyst, react at 85°C for 4 h, and then distill under reduced pressure and wash to obtain intermediate 2;

[0039] S3. To 60 mL of N, N-dimethylformamide solvent was added 1.4 g of intermediate 2, stirred and dispersed, and then 2.13 g of thioglycolic acid and 0.03 g of benzoin dimethyl ether photoinitiator were added thereto. The mixture was irradiated with ultraviolet light at 365 nm for 4 h at 40 ° C. After the reaction, the mixture was centrifuged, washed and dried to obtain an additive.

[0040] S4. After crushing 90 parts by weight of foundry waste sand, calcining it at a temperature of 620°C for 1.5 hours, grinding it to obtain regenerated sand, and mixing the regenerated sand, 1.2 parts by weight of sodium silicate, 1.3 parts by weight of silicate cement, 2 parts by weight of basalt fiber, 0.8 parts by weight of silane coupling agent KH-550, 1 part by weight of an additive, and 0.55 parts by weight of epoxy nano-silica. The mixture was stirred at a temperature of 60°C for 20 minutes, pressed into shape at a pressure of 13 MPa, cured, and sintered at 230°C for 50 minutes to obtain foundry waste sand-based compressive regenerated sand. Example 5

[0041] S1. Add 2.34 g of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and 1.1 g of N,N-dimethylethylenediamine to 55 mL of N,N-dimethylformamide, stir and mix, heat to 75°C and react for 6 h. After reaction, evaporate under reduced pressure, wash, and dry to obtain Intermediate 1.

[0042] S2. 3.44 g of 4-vinylbenzoyl chloride and 3.26 g of intermediate 1 were added to 60 mL of N,N-dimethylformamide solvent and stirred to dissolve. 0.013 g of pyridine catalyst was then added and the mixture was reacted at 95°C for 6 h. After reaction, the mixture was distilled under reduced pressure and washed to obtain intermediate 2.

[0043] S3. To 50 mL of N, N-dimethylformamide solvent was added 1.3 g of intermediate 2, stirred and dispersed, and then 2.08 g of thioglycolic acid and 0.025 g of benzoin dimethyl ether photoinitiator were added thereto. The mixture was irradiated with ultraviolet light at 365 nm for 3 h at 30 ° C. After the reaction, the mixture was centrifuged, washed and dried to obtain an additive.

[0044] S4. After crushing 80 parts by weight of foundry waste sand, calcining it at a temperature of 600°C for 1 hour, and grinding it to obtain regenerated sand, the regenerated sand, 1 part by weight of sodium silicate, 0.8 part by weight of silicate cement, 1 part by weight of basalt fiber, 0.5 part by weight of silane coupling agent KH-550, 1 part by weight of additives, and 0.5 part by weight of epoxy nano-silica were mixed, stirred at a temperature of 50°C for 15 minutes, pressed into shape at a pressure of 10 MPa, cured, and sintered at 230°C for 50 minutes to obtain foundry waste sand-based compressive regenerated sand.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 5 is that intermediate 1 is used instead of the auxiliary agent.

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 5 is that intermediate 2 is used instead of the auxiliary agent.

[0049] The compressive strength test was carried out in accordance with GB / T 2684-2009.

[0050] Table 1: Compressive strength test.

[0051] project Compressive strength (MPa) Example 1 4.85 Example 2 5.13 Example 3 4.69 Example 4 4.82 Example 5 5.04 Comparative Example 1 2.3 Comparative Example 2 2.6

[0052] As can be seen from Table 1, Examples 1-5 of the foundry waste sand-based compressive regenerated sand of the present invention have better compressive strength than Comparative Examples 1-2.

[0053] The water absorption test was carried out in accordance with GB / T 17431.2-2010.

[0054] Table 2: Water absorption test.

[0055] project Water absorption rate (%) Example 1 2.8 Example 2 2.6 Example 3 2.7 Example 4 2.6 Example 5 2.9 Comparative Example 1 5.3 Comparative Example 2 4.5

[0056] As can be seen from Table 2, Examples 1-5 of the foundry waste sand-based compressive regenerated sand of the present invention have a lower water absorption rate than Comparative Examples 1-2.

[0057] It should be noted that, in this document, the terms "comprise," "include," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprises a ..." does not preclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0058] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

[0059] Those skilled in the art will appreciate that the foregoing descriptions are merely specific embodiments of the present invention, and not exhaustive. It should be noted that numerous variations and modifications are possible for those skilled in the art, and all such variations and modifications that do not exceed the scope of the claims should be considered within the scope of protection of the present invention.

Claims

1. A foundry waste sand-based compressive regenerated sand, characterized in that: The invention comprises the following components by weight: 80-100 parts by weight of foundry waste sand, 1-1.5 parts by weight of sodium silicate, 0.8-1.6 parts by weight of silicate cement, 1-2 parts by weight of basalt fiber, 0.5-1 parts by weight of silane coupling agent KH-550, 1-2 parts by weight of auxiliary agent, and 0.5-0.6 parts by weight of epoxy nano-silica; The preparation method of the auxiliary agent is: S1. Add 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde and N,N-dimethylethylenediamine to N,N-dimethylformamide solvent, stir and mix, heat to 65-75°C for reaction, and then distill under reduced pressure, wash, and dry to obtain intermediate 1; S2. Add 4-vinylbenzoyl chloride and intermediate 1 to 50-60 mL of N,N-dimethylformamide solvent, stir to dissolve, continue to add pyridine catalyst, react at 85-95 ° C for 4-6 hours, and then distill under reduced pressure and wash to obtain intermediate 2; S3. Add intermediate 2 to 45-60 mL of N,N-dimethylformamide solvent, stir and disperse, then add thioglycolic acid and benzoin dimethyl ether photoinitiator, irradiate with 365 nm ultraviolet light at 25-40 ° C, centrifuge, wash and dry to obtain an auxiliary agent.

2. The compression-resistant regenerated sand based on foundry waste sand according to claim 1, characterized in that: The usage ratio of 4-[N,N-bis(2-hydroxyethyl)amino]benzaldehyde, N,N-dimethylethylenediamine, and N,N-dimethylformamide solvent in S1 is 2.27-2.34 g: 0.92-1.1 g: 50-55 mL.

3. The compression-resistant regenerated sand based on foundry waste sand according to claim 1, characterized in that: The reaction time in S1 is 4-6 hours.

4. The compression-resistant regenerated sand based on foundry waste sand according to claim 1, characterized in that: The mass ratio of 4-vinylbenzoyl chloride, intermediate 1, and pyridine catalyst in S2 is 2.65-3.44 g: 3.14-3.26 g: 0.01-0.013 g.

5. The compression-resistant regenerated sand based on foundry waste sand according to claim 1, characterized in that: The mass ratio of the intermediate 2, thioglycolic acid, and benzoin dimethyl ether photoinitiator in S3 is 1.2-1.4 g: 2.01-2.13 g: 0.02-0.03 g.

6. The compression-resistant regenerated sand based on foundry waste sand according to claim 1, characterized in that: The irradiation time in S3 is 2-4 hours.

7. A method for preparing compression-resistant regenerated sand based on foundry waste sand according to any one of claims 1 to 6, characterized in that: The preparation method of the foundry waste sand-based compressive regenerated sand comprises the following steps: crushing the foundry waste sand, roasting it at a temperature of 600-650° C. for 1-2 hours, grinding it to obtain the regenerated sand, mixing the regenerated sand, sodium silicate, silicate cement, basalt fiber, silane coupling agent KH-550, additives, and epoxy nano-silica, stirring it at a temperature of 50-65° C. for 15-25 minutes, pressing it into shape at a pressure of 10-15 MPa, curing it, and sintering it at 230° C. for 50 minutes to obtain the foundry waste sand-based compressive regenerated sand.

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