Coal gasification slag-based multi-solid-waste low-carbon cementing material as well as preparation method and application thereof

Abstract

The invention discloses a coal gasification slag-based multi-solid-waste low-carbon cementing material as well as a preparation method and application thereof, and relates to the technical field of solid waste resource utilization and building materials. The raw materials of the invention comprise, by mass, 50-70% of coal gasification slag, 5-15% of a composite alkaline activator, 3-15% of desulfurized gypsum, and 20-40% of cement. The water-binder ratio is 0.30 to 0.40; the composite alkaline activator comprises carbide slag, ammonia distillation waste residue and ash slag. According to the invention, the coal gasification slag is used as a main raw material, and industrial solid wastes such as carbide slag, ammonia distillation waste residue, ash slag, desulfurized gypsum and the like are cooperatively utilized, so that a large-scale and high-value absorption way is provided for a large amount of industrial solid wastes. The use amount of cement is greatly reduced, carbon emission and energy consumption generated in the cement production link are effectively reduced, meanwhile, the performance of the cementing material is excellent, the material cost is remarkably reduced due to the fact that the main raw material is industrial solid waste, and the cementing material has the advantages of environmental protection and economy.

Description

Technical Field

[0001] This invention relates to the fields of solid waste resource utilization and building materials technology, and in particular to a coal gasification slag-based multi-solid waste low-carbon cementitious material, its preparation method, and its application. Background Technology

[0002] Coal gasification technology is a core technology for the clean and efficient utilization of coal, but its production process generates a large amount of coal gasification slag. Statistics show that processing 1 million tons of coal produces approximately 900,000 tons of coal gasification slag, with a huge annual output and continuously increasing stockpiles. The indiscriminate dumping of this gasification slag not only occupies land, but its heavy metals and unburned carbon residue also cause serious pollution to the atmosphere, soil, and water bodies.

[0003] Currently, the utilization of coal gasification slag mainly focuses on its use as concrete aggregate, in the preparation of wall materials, or in geopolymers. However, these utilization methods are limited in scale and make it difficult to achieve large-scale disposal of gasification slag. On the other hand, cement, as the most important cementitious material, has a high energy consumption and heavy pollution during its production process, which involves grinding and burning, and is one of the main sources of carbon emissions. Therefore, it is urgent to develop a new type of cementitious material that can dispose of industrial solid waste on a large scale, at low cost, and with low carbon emissions.

[0004] While some studies have attempted to use coal gasification slag as a cementitious material, existing technologies generally suffer from problems such as insufficient activation of activity, low dosage, slow strength development, or poor early strength. For example, directly incorporating high-carbon fine slag significantly reduces strength; while simple physical grinding or single chemical activation is insufficient to effectively disrupt the stable glassy structure in the gasification slag, resulting in its pozzolanic activity not being fully realized.

[0005] Therefore, developing a coal gasification slag-based cementitious material that is low-cost, high-performance, and environmentally safe based on the synergistic effect of multiple solid wastes has an urgent practical need and broad application prospects. Summary of the Invention

[0006] The purpose of this invention is to provide a low-carbon cementitious material based on coal gasification slag and its preparation method and application, in order to solve the problems existing in the prior art. This invention provides a multi-element solid waste cementitious material with coal gasification slag, a composite alkaline activator (carbide slag, ammonia stripping waste slag, and ash slag) as the main raw materials. This material can achieve high-volume, high-value resource utilization of coal gasification slag, and has the advantages of low cost, high strength, low carbon emissions, and environmental friendliness. It can absorb a large amount of solid waste, achieving the resource utilization goal of "adapting to local conditions and treating waste with waste," while also possessing the value of circular economy and energy conservation and environmental protection.

[0007] To achieve the above objectives, the present invention provides the following solution:

[0008] This invention provides a low-carbon cementitious material based on coal gasification slag and multiple solid wastes, the raw materials of which include the following components by mass percentage:

[0009] The composition consists of 50%–70% coal gasification slag, 5%–15% composite alkaline activator, 3%–15% desulfurized gypsum, and 20%–40% cement; the water-cement ratio is 0.30–0.40.

[0010] The composite alkaline activator includes carbide slag, ammonia stripping waste residue, and ash slag.

[0011] As a further preferred embodiment of the present invention, the water-to-binder ratio is 0.35.

[0012] As a further preferred embodiment of the present invention, the coal gasification slag is coarse or medium coal gasification slag that has undergone mechanical grinding, with a specific surface area of ​​not less than 450 m² / kg and a particle size distribution range of 0.275 μm to 79.432 μm. 50 The thickness is 9.937 μm; the loss on ignition of the gasification slag is not higher than 5%.

[0013] By combining physical grinding with chemical activation, the pozzolanic activity of coal gasification slag can be fully activated, promoting the formation of hydration products such as CSH gel and ettringite during the hydration process.

[0014] As a further preferred embodiment of the present invention, the particle size distribution of the carbide slag is between 0.523 μm and 111.468 μm, D 50 It is 18.341 μm.

[0015] As a further preferred embodiment of the present invention, the CaO content in the carbide slag is not less than 90 wt%, and the CaO content in the ammonia stripping waste residue and the ash slag is not less than 60 wt%.

[0016] As a further preferred embodiment of the present invention, the particle size distribution of the desulfurized gypsum is between 0.463 μm and 185.869 μm, D 50 It is 20.927 μm.

[0017] As a further preferred embodiment of the present invention, the content of CaSO4·2H2O in the desulfurized gypsum is not less than 85 wt%.

[0018] As a further preferred embodiment of the present invention, the cement is ordinary Portland cement with a strength grade of 42.5 or higher.

[0019] This invention also provides a method for preparing the above-mentioned coal gasification slag-based multi-solid waste low-carbon cementitious material, comprising the following steps:

[0020] According to the mass percentage ratio, coal gasification slag, composite alkaline activator, desulfurization gypsum and cement are mixed to obtain dry mix;

[0021] Add mixing water to the dry mixture, control the water-cement ratio, and stir to obtain a slurry;

[0022] The slurry is molded and cured to obtain the coal gasification slag-based multi-solid waste low-carbon cementitious material.

[0023] The present invention further provides the application of the above-mentioned coal gasification slag-based multi-solid waste low-carbon cementitious material in the field of construction engineering.

[0024] The present invention discloses the following technical effects:

[0025] This invention uses coal gasification slag as the main raw material and synergistically utilizes industrial solid wastes such as carbide slag, ammonia stripping waste slag, ash slag, and desulfurization gypsum to successfully achieve waste treatment with waste, providing a large-scale, high-value disposal method for bulk industrial solid waste.

[0026] This invention can fully activate the pozzolanic activity of coal gasification slag, promoting the formation of hydration products such as CSH gel and ettringite during the hydration process. This, in turn, endows the cementitious material with excellent mechanical properties. The prepared cementitious material can achieve a compressive strength of over 35 MPa after 28 days, which is superior to most similar materials. Simultaneously, this invention significantly reduces cement usage, effectively reducing carbon emissions and energy consumption in the cement production process. Furthermore, because the main raw material is industrial solid waste, it significantly reduces material costs, offering both environmental and economic advantages.

[0027] The preparation process of this invention is compatible with traditional cement-based materials, requires no special equipment, facilitates industrial production and widespread application, and has broad application prospects in the field of building materials. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 The XRD pattern of the coal gasification slag used in the embodiments of the present invention;

[0030] Figure 2 This is a SEM image of the coal gasification slag used in the embodiments of the present invention;

[0031] Figure 3 The diagram shows the compressive strength of the coal gasification slag-based multi-solid waste low-carbon cementitious materials prepared in Examples 1-5 at different curing ages. Detailed Implementation

[0032] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0033] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0034] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0035] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0036] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0037] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0038] The first aspect of this invention: provides a low-carbon cementitious material based on coal gasification slag and multi-solid waste, the raw materials comprising the following components by mass percentage:

[0039] The composition consists of 50%–70% coal gasification slag, 5%–15% composite alkaline activator, 3%–15% desulfurized gypsum, and 20%–40% cement; the water-cement ratio is 0.30–0.40.

[0040] The composite alkaline activator includes carbide slag, ammonia stripping waste residue, and ash slag.

[0041] In a specific embodiment of the present invention, the water-to-binder ratio is preferably 0.35.

[0042] As a specific embodiment of the present invention, the coal gasification slag is coarse or medium coal gasification slag that has undergone mechanical grinding, with a specific surface area of ​​not less than 450 m² / kg and a particle size distribution range of 0.275 μm to 79.432 μm. 50 The thickness is 9.937 μm; the loss on ignition of the gasification slag is not higher than 5%.

[0043] By combining physical grinding with chemical activation, the pozzolanic activity of coal gasification slag can be fully activated, promoting the formation of hydration products such as CSH gel and ettringite during the hydration process.

[0044] As a specific embodiment of the present invention, the particle size distribution of the carbide slag is between 0.523 μm and 111.468 μm, D 50 It is 18.341 μm.

[0045] As a specific embodiment of the present invention, the CaO content in the carbide slag is not less than 90%, and the CaO content in the ammonia stripping waste residue and the ash slag is not less than 60%.

[0046] As a specific embodiment of the present invention, the particle size distribution of the desulfurized gypsum ranges from 0.463 μm to 185.869 μm, D 50 It is 20.927 μm.

[0047] As a specific embodiment of the present invention, the content of CaSO4·2H2O in the desulfurized gypsum is not less than 85%.

[0048] As a specific embodiment of the present invention, the cement is ordinary Portland cement with a strength grade of 42.5 or higher.

[0049] A second aspect of the present invention provides a method for preparing the above-mentioned coal gasification slag-based multi-solid waste low-carbon cementitious material, comprising the following steps:

[0050] According to the mass percentage ratio, coal gasification slag, composite alkaline activator, desulfurization gypsum and cement are mixed to obtain dry mix;

[0051] Add mixing water to the dry mixture, control the water-cement ratio, and stir to obtain a slurry;

[0052] The slurry is molded and cured to obtain the coal gasification slag-based multi-solid waste low-carbon cementitious material.

[0053] A third aspect of this invention is to provide the application of the above-mentioned coal gasification slag-based multi-solid waste low-carbon cementitious material in the field of construction engineering.

[0054] As a specific embodiment of the present invention, the preparation method may specifically adopt the following steps:

[0055] 1. Raw material pretreatment: The coal gasification slag is ball-milled for 2-3 hours until the target fineness is achieved (specific surface area ≥450 m² / kg, particle size distribution range between 0.275μm and 79.432μm, D50 of 9.937μm).

[0056] 2. Dry mixing: Weigh the ground coal gasification slag, composite alkaline activator, desulfurization gypsum and cement according to the proportion, put them in a mixer and dry mix them evenly to obtain a uniform dry mix.

[0057] 3. Wet mixing: Add mixing water to the dry mixture, with the water-to-binder ratio controlled at 0.30~0.40, preferably 0.35, and stir for 5~10 minutes until a uniform slurry is formed;

[0058] 4. Molding and curing: Pour the slurry into the mold, vibrate and level it, and then cure it for 24 hours under standard conditions of temperature 20±2℃ and humidity ≥95% before demolding. Then continue to cure it under standard conditions until the specified age.

[0059] The present invention will be further described in detail below with reference to embodiments:

[0060] The specifications and chemical composition of the coal gasification slag, calcium carbide slag, ammonia stripping waste slag, ash slag, and desulfurization gypsum in the following embodiments of the present invention are shown in Tables 1-5. The coal gasification slag used in the embodiments was ball-milled for 2 hours.

[0061] Table 1 Chemical composition of coal gasification slag (wt.%)

[0062]

[0063] The particle size distribution of the coal gasification slag ranges from approximately 0.275 μm to 79.432 μm, with a D50 of 9.937 μm and a specific surface area of ​​520 m². 2 / kg. Characteristic particle sizes are expressed as follows: D 10 =1.433μm; D 50 =9.937μm; D 90 =32.126μm. Loss on ignition is 3.2%.

[0064] Table 2 Chemical composition of carbide slag (wt.%)

[0065]

[0066] The particle size distribution of carbide slag ranges from 0.523 μm to 111.468 μm. The characteristic particle sizes are expressed as follows: D 10 =1.60μm; D 50 =18.341μm; D90 =62.814μm.

[0067] Table 3 Chemical composition of ammonia stripping waste residue (wt.%)

[0068]

[0069] Table 4 Chemical composition of ash slag (wt.%)

[0070]

[0071] Table 5 Chemical composition of desulfurized gypsum (wt.%)

[0072]

[0073] The particle size distribution of desulfurized gypsum ranges approximately from 0.463 μm to 185.869 μm. The characteristic particle sizes are expressed as follows: D 10 =1.164μm; D 50 =20.927μm; D 90 =94.486μm.

[0074] The water used is municipal tap water. The cement is ordinary Portland cement with a strength grade of 42.5.

[0075] Example 1

[0076] A coal gasification slag-based low-carbon cementitious material composed of the following raw materials by weight:

[0077] 645g of coal gasification slag, 64.5g of compound alkaline activator, 64.5g of desulfurized gypsum, and 226g of cement.

[0078] In the composite alkaline activator, the mass ratio of carbide slag, ammonia stripping waste residue, and ash slag is 8:1:1.

[0079] The preparation steps are as follows:

[0080] Mix the above raw materials thoroughly with a dry mix, add an appropriate amount of water at a water-to-binder ratio of 0.35, and stir for 5 minutes to form a uniform slurry.

[0081] The slurry was poured into a 40mm×40mm×40mm test mold, vibrated, leveled, and covered with plastic wrap. After curing under standard curing conditions (temperature 20±2℃, humidity ≥95%) for 24 hours, the mold was removed to obtain building material A1, and curing continued for 3 days, 7 days, and 28 days.

[0082] Example 2

[0083] A coal gasification slag-based low-carbon cementitious material composed of the following raw materials by weight:

[0084] 625g of coal gasification slag, 62.5g of compound alkaline activator, 93.8g of desulfurized gypsum, and 219g of cement.

[0085] In the composite alkaline activator, the mass ratio of carbide slag, ammonia stripping waste residue, and ash slag is 8:1:1.

[0086] The preparation steps are as follows:

[0087] Mix the above raw materials thoroughly with a dry mix, add an appropriate amount of water at a water-to-binder ratio of 0.35, and stir for 5 minutes to form a uniform slurry.

[0088] The slurry was poured into a 40mm×40mm×40mm test mold, vibrated, leveled, and covered with plastic wrap. After curing under standard curing conditions (temperature 20±2℃, humidity ≥95%) for 24 hours, the mold was removed to obtain building material A2. Curing was continued for 3 days, 7 days, and 28 days.

[0089] Example 3

[0090] A coal gasification slag-based low-carbon cementitious material composed of the following raw materials by weight:

[0091] 645g of coal gasification slag, 64.5g of compound alkaline activator, 32.3g of desulfurized gypsum, and 258g of cement.

[0092] In the composite alkaline activator, the mass ratio of carbide slag, ammonia stripping waste residue, and ash slag is 8:1:1.

[0093] The preparation steps are as follows:

[0094] Mix the above raw materials thoroughly with a dry mix, add an appropriate amount of water at a water-to-binder ratio of 0.35, and stir for 5 minutes to form a uniform slurry.

[0095] The slurry was poured into a 40mm×40mm×40mm test mold, vibrated, leveled, and covered with plastic wrap. After curing under standard curing conditions (temperature 20±2℃, humidity ≥95%) for 24 hours, the mold was removed to obtain building material A3, and curing continued for 3 days, 7 days, and 28 days.

[0096] Example 4

[0097] A coal gasification slag-based low-carbon cementitious material composed of the following raw materials by weight:

[0098] 625g of coal gasification slag, 62.5g of compound alkaline activator, 62.5g of desulfurized gypsum, and 250g of cement.

[0099] In the composite alkaline activator, the mass ratio of carbide slag, ammonia stripping waste residue, and ash slag is 8:1:1.

[0100] The preparation steps are as follows:

[0101] Mix the above raw materials thoroughly with a dry mix, add an appropriate amount of water at a water-to-binder ratio of 0.35, and stir for 5 minutes to form a uniform slurry.

[0102] The slurry was poured into a 40mm×40mm×40mm test mold, vibrated, leveled, and covered with plastic wrap. After curing under standard curing conditions (temperature 20±2℃, humidity ≥95%) for 24 hours, the mold was removed to obtain building material A4. Curing continued for 3 days, 7 days, and 28 days.

[0103] Example 5

[0104] A coal gasification slag-based low-carbon cementitious material composed of the following raw materials by weight:

[0105] 606g of coal gasification slag, 60.6g of composite alkaline activator, 90.1g of desulfurized gypsum, and 242.4g of cement.

[0106] In the composite alkaline activator, the mass ratio of carbide slag, ammonia stripping waste residue, and ash slag is 8:1:1.

[0107] The preparation steps are as follows:

[0108] Mix the above raw materials thoroughly with a dry mix, add an appropriate amount of water at a water-to-binder ratio of 0.35, and stir for 5 minutes to form a uniform slurry.

[0109] The slurry was poured into a 40mm×40mm×40mm test mold, vibrated, leveled, and covered with plastic wrap. After curing under standard curing conditions (temperature 20±2℃, humidity ≥95%) for 24 hours, the material was demolded to obtain building material A5. Curing continued for 3 days, 7 days, and 28 days.

[0110] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A coal gasification slag-based multi-solid waste low-carbon cementitious material, characterized in that, The raw material comprises the following components by mass percentage: 50-70% of coal gasification slag, 5-15% of composite alkaline activator, 3-15% of desulfurization gypsum, and 20-40% of cement; and the water-binder ratio is 0.30-0.40; The composite alkaline activator comprises carbide slag, ammonia distillation waste slag, and lime ash slag.

2. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The water-binder ratio is 0.

35.

3. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The coal gasification slag is treated by mechanical grinding, has a specific surface area of not less than 450 m2 / kg, a particle size distribution range of 0.275-79.432 μm, a D 50 of 9.937 μm, and a loss on ignition of not higher than 5%.

4. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The particle size distribution of the carbide slag ranges between 0.523 μm and 111.468 μm, D 50 is 18.341 μm.

5. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The CaO content in the carbide slag is not less than 90wt%, and the CaO content in the ammonia distillation waste slag and the lime ash slag is not less than 60wt%.

6. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The particle size distribution of the desulfurized gypsum ranges between 0.463 μm and 185.869 μm, D 50 was 20.927 μm.

7. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The CaSO4·2H2O content in the desulfurization gypsum is not less than 85wt%.

8. The coal gasification slag-based multi-solid waste low carbon cementitious material according to claim 1, characterized in that, The cement is ordinary Portland cement with a strength grade of 42.5 or above.

9. The method of producing coal gasification slag-based multi-solid waste low carbon cementitious material according to any one of claims 1-8, characterized in that, The method comprises the following steps: The coal gasification slag, the composite alkaline activator, the desulfurization gypsum, and the cement are mixed according to the mass percentage to obtain dry mixture; Water is added to the dry mixture, the water-binder ratio is controlled, and stirring is performed to obtain slurry; The slurry is shaped and cured to obtain the coal gasification slag-based multi-solid waste low-carbon cementitious material.

10. Application of the coal gasification slag-based multi-solid waste low-carbon cementitious material in claim any one of claims 1-8 in the field of building engineering.

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