Preparation method and application of composite curing agent based on industrial solid waste

Abstract

The invention provides a preparation method of a composite curing agent based on industrial solid waste. The method comprises the step of mixing slag powder, fly ash, carbide slag and cement. The invention further provides application of the composite curing agent based on the industrial solid waste for curing the phyllite filler, and the improved phyllite filler is prepared and serves as highway subgrade filler. According to the method, resource utilization of the waste rock-soil body is achieved, pollution damage of the waste rock-soil body and solid waste emission to the environment is avoided, solid waste materials are fully utilized, the environment is protected, and mineral resources are saved.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid waste resource utilization, and specifically relates to a preparation method and application of a composite curing agent based on industrial solid waste. Background Art

[0002] Cement production is a high-energy, high-consumption, and high-emissions industry. Cement production consumes significant quantities of natural resources such as coal and limestone, and also emits significant amounts of pollutants such as dust, sulfur oxides, and carbon dioxide. Therefore, finding alternatives to cement and reducing cement usage has become a crucial measure for energy conservation, efficiency improvement, and environmental comfort. Therefore, the search for a cement substitute based on industrial solid waste could not only reduce highway construction costs but also have significant practical implications for optimizing the allocation and rational utilization of resources, energy, and environmental carrying capacity within my country.

[0003] Solid waste refers to solid and semi-solid waste materials that pollute the environment during production and construction, daily life and other activities. Among them, industrial solid waste refers to non-hazardous solid waste generated from the production and life of industrial production, transportation, post and telecommunications and other industries, referred to as industrial solid waste. For example, mining solid wastes such as tailings, coal gangue, and waste rock generated by mining enterprises, and waste tires generated by the transportation manufacturing industry. Urban domestic waste includes construction waste. Industrial solid waste has typical resource properties and has potential hydraulic activity and activation and excitation capabilities. Typical slag and fly ash contain impurities such as silica and alumina, which react with lime, water, etc. to form a molten material with silicates and aluminosilicates as the main components, which is basically the same as the general silicate cement clinker.

[0004] Phyllite is a low-grade metamorphic rock with a phyllic structure. The rock is soft and carbon-containing phyllite easily becomes muddy and softens when it comes into contact with water. It has poor weathering resistance and is easily weathered to form rock debris. Its fine particles have poor cohesion and are usually difficult to use in engineering projects. They are often disposed of as engineering waste. The large amount of phyllite waste has caused great difficulties in land occupation, environmental protection and engineering costs. If phyllite can be used as a resource for roadbed filling, the problems of land occupation and environmental problems caused by waste materials can be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a preparation method and application of a composite curing agent based on industrial solid waste. The composite curing agent based on industrial solid waste can meet the curing requirements of phyllite fillers in related engineering cushion layers, road subgrade projects and other similar projects, thereby avoiding secondary pollution of the environment by industrial solid waste materials. At the same time, it has significant economic and social benefits for engineering construction, cost reduction and efficiency improvement.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a method for preparing a composite curing agent based on industrial solid waste, the method is: S1. Dry and grind the coarse slag particles, and pass them through a 200-mesh sieve to obtain slag powder; S2, drying and grinding the coarse particles of fly ash, and passing through a 200-mesh sieve to obtain fly ash; S3, drying and grinding the coarse particles of carbide slag, and passing them through a 200 mesh sieve to obtain carbide slag; S4. Evenly mix the slag powder obtained in S1, the fly ash obtained in S2, the carbide slag obtained in S3, and cement to obtain a composite curing agent based on industrial solid waste.

[0007] Preferably, the fly ash in S2 is secondary fly ash.

[0008] Preferably, the composite curing agent based on industrial solid waste in S4 is composed of the following raw materials in mass fractions: 30% to 40% slag powder, 15% to 45% fly ash, 20% to 35% carbide slag, and the balance is cement.

[0009] Preferably, the type of cement described in S4 is P.0.42.5.

[0010] The present invention also provides the application of the composite curing agent based on industrial solid waste prepared by the above preparation method, wherein the composite curing agent based on industrial solid waste is used to solidify the plain phyllite filler to prepare the improved phyllite filler as a highway subgrade filler.

[0011] Preferably, the mass ratio of the composite curing agent based on industrial solid waste to the phyllite filler is 5%:1.

[0012] Preferably, the unconfined strength of the solidified phyllite at 7 days of age is 0.932 MPa to 2.840 MPa, and the strength loss upon immersion in water is 15.0% to 38.5%.

[0013] Compared with the prior art, the present invention has the following advantages: The industrial solid waste-based composite curing agent of the present invention is mainly made of industrial solid waste, can be used to improve phyllite filler, and is used as highway roadbed filler, avoiding the pollution and damage to the environment caused by abandoned rock and soil and solid waste emissions, making full use of solid waste materials, protecting the environment, and saving mineral resources.

[0014] The present invention will be further described in detail below with reference to the embodiments. DETAILED DESCRIPTION

[0015] Example 1 This embodiment is a method for preparing a composite curing agent based on industrial solid waste, which is: S1. Dry the coarse slag particles to constant weight, grind them with a ball mill, and pass them through a 200-mesh sieve to obtain slag powder; S2. Drying the coarse particles of fly ash to constant weight, grinding them with a ball mill, and passing them through a 200-mesh sieve to obtain fly ash; the fly ash is secondary fly ash; S3, drying the coarse particles of carbide slag to constant weight, grinding them with a ball mill, and passing them through a 200-mesh sieve to obtain carbide slag; S4. Evenly mix the slag powder obtained in S1, the fly ash obtained in S2, the carbide slag obtained in S3, and cement to obtain a composite curing agent based on industrial solid waste; the composite curing agent based on industrial solid waste is composed of the following raw materials in the following mass fractions: 30% slag powder, 45% secondary fly ash, 20% carbide slag, and 5% cement.

[0016] Example 2 The preparation method of the solid waste-based composite curing agent in this embodiment is the same as the preparation method in Example 1, except that the composite curing agent based on industrial solid waste is composed of the following raw materials in mass fractions: 37% slag powder, 30% secondary fly ash, 30% carbide slag, and 3% cement.

[0017] Example 3 The preparation method of the solid waste-based composite curing agent in this embodiment is the same as the preparation method in Example 1, and the industrial solid waste-based composite curing agent is composed of the following raw materials in mass fractions: 40% slag powder, 15% secondary fly ash, 35% carbide slag, and 10% cement.

[0018] Example 4 The preparation method of the solid waste-based composite curing agent in this embodiment is the same as the preparation method in Example 1, and the industrial solid waste-based composite curing agent is composed of the following raw materials in mass fractions: 32% slag powder, 40% secondary fly ash, 22% carbide slag, and 6% cement.

[0019] Example 5 The preparation method of the solid waste-based composite curing agent in this embodiment is the same as the preparation method in Example 1, and the industrial solid waste-based composite curing agent is composed of the following raw materials in the following mass fractions: 38% slag powder, 20% secondary fly ash, 30% carbide slag, and 12% cement.

[0020] Comparative Example 1 This comparative example tests the performance of single-component doped phyllite fillers, wherein the single components are slag powder, fly ash, carbide slag and cement.

[0021] Fly ash, slag powder, carbide slag, and cement were added to plain phyllite filler at concentrations of 2%, 4%, 6%, and 8%, respectively, to prepare modified phyllite fillers. Strength comparisons were conducted using samples prepared from plain phyllite filler containing no fly ash, slag powder, carbide slag, or cement as a control (0% in Table 1). The results, shown in Table 1, show that when each component was added alone, at the same dosage, the strength of the cement-modified samples was significantly higher than that of samples modified with fly ash, slag powder, or carbide slag alone. Furthermore, large dosages of fly ash, slag powder, and carbide slag alone were required to effectively improve the strength of the phyllite filler samples.

[0022] Table 1 Unconfined compressive strength Comparative Example 2 The preparation method of the composite curing agent based on industrial solid waste in this comparative example is the same as that in Example 1, except that it does not contain carbide slag and cement. The composite curing agent based on industrial solid waste is composed of the following raw materials in mass fractions: 40% slag powder and 60% secondary fly ash.

[0023] Comparative Example 3 The preparation method of the composite curing agent based on industrial solid waste in this comparative example is the same as that in Example 1, except that it does not contain slag powder and cement. The composite curing agent based on industrial solid waste is composed of the following raw materials in mass fractions: 60% secondary fly ash and 40% carbide slag.

[0024] The solid waste-based composite curing agents prepared in Examples 1-5 and Comparative Examples 2-3 were subjected to 7-day unconfined compressive strength and water immersion strength loss tests.

[0025] The prepared industrial solid waste-based composite curing agent was used to cure samples filled with phyllite (the mass ratio of the industrial solid waste-based composite curing agent to the phyllite filler was 5%:1). The performance test results are shown in Table 2.

[0026] Table 2 Test results of composite curing agent based on industrial solid waste to improve phyllite filler Slag powder, fly ash and carbide slag have similar mineral components to cement, such as SiO2, CaO, Al2O3, etc., which determines that slag powder, fly ash and carbide slag are solid wastes with certain activity. In mature processes, slag powder, fly ash and carbide slag are added to cement as mineral admixtures. In roadbeds, they can replace cement, lime, etc. to improve phyllite fillers, etc. Their active characteristics can form stronger roadbed cement. Therefore, from the perspective of material properties, slag powder, fly ash, carbide slag and cement mixed together can be used as a good road construction material improver. By setting different amounts of slag powder, fly ash, carbide slag and cement, 5 embodiments and 2 comparative examples were formed, and their 7d unconfined compressive strength and immersion strength loss were tested. The results showed that the 7d unconfined compressive strength was: Example 1 (2.840MPa), Example 2 (1.444MPa), Example 3 (1.235MPa), Example 4 (0.932MPa), Example 5 (1.233MPa), Comparative Example 2 (0.521 MPa), Comparative Example 3 (0.901 MPa). The 7d unconfined compressive strength of the Examples was greater than that of the Comparative Example. The water immersion strength loss of the Examples was less than 50% for Example 1 (33.2%), Example 2 (19.5%), Example 3 (28.2%), Example 4 (15.0%), Example 5 (38.5%), Comparative Example 2 (100%), and Comparative Example 3 (50.1%). The strength loss of the Examples was less than 50%, while the strength loss of the Comparative Example was greater than 50%. Comparative Example 2 completely disintegrated after immersion in water, with a strength loss of 100%. Slag powder, fly ash, and carbide slag contain tricalcium silicate and dicalcium silicate, which have hydration reaction conditions, such as those shown in reaction equations (1-1) and (1-2). Table 3 shows the chemical composition analysis of various solid wastes. When composite curing agents developed based on slag powder, fly ash, carbide slag, and cement replace cement, the principle behind this is that slag powder and fly ash are rich in components such as CaO, SiO₂, and Al₂O₃. These components undergo secondary hydration reactions in an alkaline environment (Ca(OH)₂ generated by cement hydration), forming CSH gel, which improves later strength. Carbide slag, primarily composed of Ca(OH)₂, provides an alkaline environment to activate the activity of slag or fly ash. Cement primarily relies on the hydration of silicate clinker (C₃S, C₂S) to generate CSH gel for strength, but excessive cement content increases CO₂ emissions. Therefore, Comparative Example 2 does not contain carbide slag, which prevents the activation of its slag powder and fly ash. Consequently, the unconfined compressive strength of the phyllite filler modified with the composite curing agent based on industrial solid waste is lower than that of the example. Comparative Example 3 does not contain slag powder. Since slag powder is rich in components such as CaO, SiO2, and Al2O3, a secondary hydration reaction occurs under the stimulation of an alkaline environment (Ca(OH)2 generated by cement hydration), generating CSH gel and improving the later strength. Since there is no slag powder in Comparative Example 3, no secondary hydration reaction occurs, and therefore the 7d unconfined compressive strength is lower than that of the embodiment.

[0027] 2(3CaO·SiO2)+6H2O=3Ca(OH)2+3CaO·2SiO2·3H2O (1-1) 2(2CaO·SiO2)+4H2O=Ca(OH)2+3CaO·2SiO2·3H2O (1-2) Table 3 Chemical composition analysis of different solid wastes Note: “ / ” in the table means there is no such chemical component.

[0028] The grinding method used in the preparation method of the composite curing agent based on industrial solid waste of the present invention can be either separate solid waste grinding or mixed solid waste grinding. The use of the original solid waste can be determined based on the required amount of the project. Separate solid waste grinding is suitable for projects with small amounts of solid waste, while mixed solid waste grinding is suitable for projects with large amounts of solid waste.

[0029] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a composite curing agent based on industrial solid waste, characterized in that: The method is: S1. Dry and grind the coarse slag particles, and pass them through a 200-mesh sieve to obtain slag powder; S2, drying and grinding the coarse particles of fly ash, and passing through a 200-mesh sieve to obtain fly ash; S3, drying and grinding the coarse particles of carbide slag, and passing them through a 200 mesh sieve to obtain carbide slag; S4. Evenly mix the slag powder obtained in S1, the fly ash obtained in S2, the carbide slag obtained in S3, and cement to obtain a composite curing agent based on industrial solid waste.

2. The method for preparing a composite curing agent based on industrial solid waste according to claim 1, characterized in that: The fly ash described in S2 is secondary fly ash.

3. The method for preparing a composite curing agent based on industrial solid waste according to claim 1, characterized in that: The industrial solid waste-based composite curing agent described in S4 is composed of the following raw materials in mass fractions: 30% to 40% slag powder, 15% to 45% fly ash, 20% to 35% carbide slag, and the balance is cement.

4. The method for preparing a composite curing agent based on industrial solid waste according to claim 1, characterized in that: The type of cement described in S4 is P.0.42.

5.

5. An application of a composite curing agent based on industrial solid waste prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The composite curing agent based on industrial solid waste is used to solidify the plain phyllite filler to prepare the improved phyllite filler, which is used as a highway subgrade filler.

6. The use according to claim 5, characterized in that The mass ratio of the composite curing agent based on industrial solid waste to the phyllite filler is 5%:

1.

7. The use according to claim 6, characterized in that The unconfined strength of the solidified phyllite at 7 days of age is 0.932 MPa to 2.840 MPa, and the water immersion strength loss is 15.0% to 38.5%.

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