Carbonized calcined coal gangue solid waste-based cementing material and preparation method thereof

Abstract

The invention provides a carbonized calcined coal gangue solid waste-based cementing material and a preparation method thereof, and belongs to the technical field of coal gangue solid waste utilization. The carbonized coal gangue-based cementing material is prepared from the following raw materials: 30 to 70 parts of calcined coal gangue micro powder, 20 to 50 parts of premixed concrete waste residue, 10 to 20 parts of cement, 0 to 5 parts of gypsum, 0.5 to 1.0 part of surfactant and 0.1 to 0.5 part of organic amine. The preparation method comprises the following steps: firstly, crushing, grinding and calcining coal gangue solid waste; mixing the mixture with premixed concrete waste residues, ordinary Portland cement, gypsum, a surfactant and organic amine, introducing industrial carbon dioxide, and drying to obtain the cement. The performance index of the carbonized and calcined coal gangue solid waste based cementing material is equivalent to that of PO 42.5-grade cement, large-dosage utilization of the coal gangue solid waste and preparation of the low-carbon cementing material are achieved, the process is simple, and the practical application and popularization value is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of coal gangue solid waste utilization, and in particular relates to a carbonized calcined coal gangue solid waste-based cementitious material and a preparation method thereof. Background Art

[0002] Gangue is a solid waste generated during the production and processing of coal. It is a symbiotic resource of coal. It is a carbonaceous rock that is associated with coal during the coal formation process, with an ash content usually greater than 50% and a calorific value generally in the range of 3.5 to 8.3 mJ / kg. The main minerals of gangue are clay minerals such as kaolinite and chlorite and α-quartz. The main chemical components are SiO2, Al2O3, Fe2O3, etc. After activation treatment, the clay minerals are decomposed into amorphous SiO2 and Al2O3 substances, making them active. There are three main methods for activating gangue: thermal activation, chemical activation, and mechanical activation. Among them, the role of calcining gangue is: first, to remove carbon from the gangue; second, after calcination, the gangue is dehydrated and decomposed to generate metakaolinite and amorphous silica and alumina, showing volcanic ash activity.

[0003] Although adding activated coal gangue powder to cement can reduce carbon emissions and lower the degree of environmental pollution to a certain extent, the coal gangue itself has more pores and impurities, which will affect the working performance and mechanical properties of concrete. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a carbonized calcined coal gangue solid waste-based cementitious material and a preparation method thereof. The present invention carbonizes coal gangue, ready-mixed concrete waste, gypsum, surfactant, and organic amine, and then mixes them with ordinary Portland cement to prepare a carbonized calcined coal gangue solid waste-based cementitious material, which can improve the activity of coal gangue and optimize the pore structure, so that the performance indicators of coal gangue solid waste as a cementitious material are equivalent to those of PO 42.5 grade cement.

[0005] To achieve the above-mentioned purpose, the present invention provides a carbonized calcined coal gangue solid waste-based cementitious material, comprising the following raw materials in parts by weight: 30-70 parts of calcined coal gangue powder, 20-50 parts of ready-mixed concrete waste, 10-20 parts of cement, 0-5 parts of gypsum (the amount is not 0), 0.5-1.0 parts of surfactant and 0.1-0.5 parts of organic amine.

[0006] Furthermore, the particle size of the calcined coal gangue powder is less than 75 μm, and the apparent density is 2200-2500 kg / m 3 , the water absorption rate is 2.10-4.40%.

[0007] Furthermore, the moisture content of the ready-mixed concrete waste residue is less than 35%, which comes from the filter residue when the concrete is mixed and cleaned at the mixing station. The main components are calcium phase substances after cement hydration, such as Ca(OH)2 and CSH, which can be carbonized to form calcium carbonate and highly polymerized amorphous silica-alumina gel.

[0008] Furthermore, the gypsum is dihydrate gypsum or industrial by-product gypsum, preferably phosphogypsum, whose CaSO4 content is greater than 80%.

[0009] Furthermore, the cement is P·O42.5 grade ordinary Portland cement or PII42.5 grade Portland cement.

[0010] Furthermore, the surfactant is sodium lauryl sulfate or alkyl sulfonate.

[0011] Furthermore, the organic amine is tributylamine or diethylbutylamine.

[0012] The present invention also provides a method for preparing the carbonized calcined coal gangue solid waste-based cementitious material, which specifically comprises the following steps:

[0013] (1) Weighing various raw materials according to weight, ball-milling the ready-mixed concrete waste residue for 20 minutes and then mixing it with calcined coal gangue powder to obtain a solid mixture A;

[0014] (2) adding water, a surfactant, and an organic amine to the solid mixture A and soaking it for 30 minutes to obtain a solid-liquid mixture B;

[0015] (3) introducing gas into the solid-liquid mixture B for stirring, and then drying to obtain a solid mixture C;

[0016] (4) The solid mixture C is mixed with the gypsum and cement to obtain the carbonized calcined coal gangue solid waste-based cementitious material.

[0017] Furthermore, the calcined coal gangue powder is obtained by calcining the coal gangue, ball milling for 60 minutes, and sieving. The calcination temperature is 700° C., the calcination time is 2 hours, and the heat preservation time after the calcination is 30 minutes.

[0018] The effects of calcining coal gangue are: first, to remove carbon from the coal gangue; second, after calcination, the coal gangue is dehydrated and decomposed to produce kaolinite and amorphous silica and alumina, in this way, the coal gangue has a certain volcanic ash activity.

[0019] Furthermore, in step (3), the stirring time of introducing gas is 4 hours.

[0020] Furthermore, in step (3), the gas is CO2 gas, and the CO2 gas is industrial grade CO2 gas with a purity of 99%.

[0021] The introduction of CO2 gas and stirring can carbonize the waste slag calcium phase material in the ready-mixed concrete with the dissolved CO2 to generate calcium carbonate and highly polymerized amorphous silica-alumina gel, which improves the activity of the waste slag powder while filling the pores of the coal gangue powder and reducing the water absorption rate.

[0022] Compared with the prior art, the present invention has the following advantages and technical effects:

[0023] (1) The present invention first carbonizes the coal gangue, mixes the premixed concrete waste slag and the calcined coal gangue powder, and reacts the partially hydrated Ca(OH)2 and CSH and other substances with CO2 through wet carbonization to obtain calcium carbonate and highly polymerized amorphous silica-alumina gel, which improves the activity of the waste slag powder on the one hand, and fills the pores of the coal gangue powder on the other hand, reducing the water absorption rate. In addition, the volcanic ash activity in the calcined coal gangue powder is stimulated, and the cementitious material prepared by mixing with cement has excellent performance (the activated coal gangue contains Al2O3 and SiO2, which have high volcanic ash activity, and the calcium carbonate generated by the carbonized waste slag has a certain activity, which can not only provide crystal nuclei for the hydration growth of cement, but also react with C3A, CH and other substances in cement clinker to generate hydration products such as AFt and CO3-AFm, and the amorphous silica-alumina gel also has a certain volcanic ash activity). In addition, the preparation method and construction process of the present invention are simple, easy to operate, and have practical promotion and application value.

[0024] (2) The present invention crushes, cleans and screens the solid waste after coal mining in the mine to obtain clean and suitable coal gangue, and then processes it to make a cementitious material, thereby reducing the amount of cement used and thus reducing the emission of carbon dioxide. It is a green and economical preparation method and is suitable for promotion.

[0025] (3) The present invention uses coal gangue powder to replace part of the cement, which alleviates the shortage of materials in the construction industry to a certain extent, thereby exploring a method for preparing a sustainable cementitious material; it has certain environmental protection significance.

[0026] (4) The present invention uses solid waste from the coal mining process in the mine, solves some solid waste treatment problems, reduces environmental pollution, and turns waste into treasure. It has important economic value and environmental significance. DETAILED DESCRIPTION

[0027] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0028] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0029] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0030] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0031] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0032] An embodiment of the present invention provides a carbonized calcined coal gangue solid waste-based cementitious material, comprising the following raw materials in parts by weight: 30-70 parts of calcined coal gangue powder, 20-50 parts of ready-mixed concrete waste, 10-20 parts of cement, 0-5 parts of gypsum (the amount is not 0), 0.5-1.0 parts of surfactant and 0.1-0.5 parts of organic amine.

[0033] In a preferred embodiment of the present invention, the particle size of the calcined coal gangue powder is less than 75 μm, and the apparent density is 2200-2500 kg / m 3 , the water absorption rate is 2.10-4.40%.

[0034] In a preferred embodiment of the present invention, the moisture content of the ready-mixed concrete waste residue is less than 35%. The waste residue comes from the filter residue when the concrete is mixed and cleaned at the mixing station. The main components are calcium phase substances after cement hydration, such as Ca(OH)2 and CSH, which can be carbonized to form calcium carbonate and highly polymerized amorphous silica-alumina gel.

[0035] In a preferred embodiment of the present invention, the gypsum is dihydrate gypsum or industrial by-product gypsum, preferably phosphogypsum, whose CaSO4 content is greater than 80%.

[0036] In a preferred embodiment of the present invention, the gypsum and cement are P·O42.5 grade ordinary Portland cement or PII42.5 grade Portland cement.

[0037] In a preferred embodiment of the present invention, the surfactant is sodium lauryl sulfate or alkyl sulfonate.

[0038] In a preferred embodiment of the present invention, the organic amine is tributylamine or diethylbutylamine.

[0039] The embodiment of the present invention also provides a method for preparing the carbonized calcined coal gangue solid waste-based cementitious material, comprising the following steps:

[0040] (1) Weighing various raw materials according to weight, ball-milling the ready-mixed concrete waste residue for 20 minutes and then mixing it with calcined coal gangue powder to obtain a solid mixture A;

[0041] (2) adding water, a surfactant, and an organic amine to the solid mixture A and soaking it for 30 minutes to obtain a solid-liquid mixture B;

[0042] (3) introducing industrial carbon dioxide gas into the solid-liquid mixture B and stirring, and then drying to obtain a solid mixture C;

[0043] (4) The solid mixture C is mixed with the gypsum and cement to obtain the carbonized calcined coal gangue solid waste-based cementitious material.

[0044] In a preferred embodiment of the present invention, the calcined gangue powder is obtained by calcining the gangue, ball milling for 60 minutes, and sieving. The calcination temperature is 700°C, the calcination time is 2 hours, and the insulation time after the calcination is 30 minutes.

[0045] In step (3) of a preferred embodiment of the present invention, CO2 gas is introduced and stirred for 4 hours.

[0046] In step (3) of a preferred embodiment of the present invention, the CO2 gas is industrial grade CO2 gas with a purity of 99%.

[0047] In the embodiments of the present invention, "parts" represent "parts by weight" unless otherwise specified.

[0048] The coal gangue used in the embodiment of the present invention comes from solid waste coal gangue mined in Guizhou Province, with a carbon content of ≤8%. The ready-mixed concrete slag comes from solid waste recycled from a local commercial concrete mixing station in Wuhan, and the moisture content of the ready-mixed concrete slag is less than 35%.

[0049] The technical solution of the present invention is further illustrated by the following embodiments.

[0050] Example 1

[0051] A carbonized calcined coal gangue solid waste-based cementitious material comprises the following raw materials in parts by weight: 50 parts of calcined coal gangue powder, 30 parts of ready-mixed concrete waste residue, 15 parts of PO42.5 grade silicate cement, 5 parts of phosphogypsum, 0.5 parts of alkyl sulfonate and 0.5 parts of diethylbutylamine, and specifically comprises the following steps:

[0052] (1) putting coal gangue into a quartz crucible and placing it in a muffle furnace for calcination, setting the temperature to 700° C. for 2 h and keeping the temperature for 30 min, cooling naturally after completion to obtain solid particles, then pouring it into a ball mill and milling it for 60 min, and then passing it through a 0.075 mm sieve to obtain calcined coal gangue powder, pouring ready-mixed concrete waste into the ball mill and milling it for 20 min, and then adding it to the calcined coal gangue powder, mixing and stirring to obtain a solid mixture A;

[0053] (2) taking the solid mixture A obtained in step (1) and transferring it to a basin, adding 200 parts of water, alkyl sulfonate and diethylbutylamine and soaking it for 30 minutes to obtain a solid-liquid mixture B;

[0054] (3) passing industrial grade CO2 gas with a purity of 99% into the solid-liquid mixture B obtained in step (2) and stirring for 4 hours, then pouring out excess water and drying in a forced air drying oven for 24 hours to obtain a solid mixture C;

[0055] (4) The solid mixture C obtained in step (3) is mixed with phosphogypsum and P·O42.5 grade ordinary Portland cement to obtain a carbonized calcined coal gangue solid waste-based cementitious material.

[0056] Example 2

[0057] A carbonized calcined coal gangue solid waste-based cementitious material comprises the following raw materials in parts by weight: 30 parts of calcined coal gangue powder, 50 parts of ready-mixed concrete waste, 17 parts of PO42.5 grade silicate cement, 3 parts of phosphogypsum, 1 part of sodium lauryl sulfate and 0.5 parts of tributylamine, and specifically comprises the following steps:

[0058] (1) The coal gangue was placed in a quartz crucible and placed in a muffle furnace for calcination. The temperature was set to 700°C for 2 hours and kept warm for 30 minutes. After completion, it was naturally cooled to obtain solid particles. Then, it was poured into a ball mill and milled for 60 minutes. After that, it was passed through a 0.075 mm sieve to obtain calcined coal gangue powder (apparent density of 2200-2500 kg / m 3 , water absorption rate is 2.10-4.40%), pouring the premixed concrete waste into a ball mill and grinding for 20 minutes, then adding it into the calcined coal gangue powder, mixing and stirring to obtain a solid mixture A;

[0059] (2) taking the solid mixture A obtained in step (1) and moving it into a basin, adding 200 parts of water, sodium lauryl sulfate and tributylamine and soaking it for 30 minutes to obtain a solid-liquid mixture B;

[0060] (3) passing industrial grade CO2 gas with a purity of 99% into the solid-liquid mixture B obtained in step (2) and stirring for 4 hours, then pouring out excess water and drying in a forced air drying oven for 24 hours to obtain a solid mixture C;

[0061] (4) The solid mixture C obtained in step (3) is mixed with phosphogypsum and P·II42.5 grade ordinary Portland cement to obtain a carbonized calcined coal gangue solid waste-based cementitious material.

[0062] Example 3

[0063] A carbonized calcined coal gangue solid waste-based cementitious material comprises the following raw materials in parts by weight: 45 parts of calcined coal gangue powder, 35 parts of ready-mixed concrete waste residue, 15 parts of PO42.5 grade silicate cement, 5 parts of phosphogypsum, 1 part of sodium lauryl sulfate and 0.5 parts of tributylamine, and specifically comprises the following steps:

[0064] (1) The coal gangue was placed in a quartz crucible and placed in a muffle furnace for calcination. The temperature was set to 700°C for 2 hours and kept warm for 30 minutes. After completion, it was naturally cooled to obtain solid particles. Then, it was poured into a ball mill and milled for 60 minutes. After that, it was passed through a 0.075 mm sieve to obtain calcined coal gangue powder (apparent density of 2200-2500 kg / m 3 , water absorption rate is 2.10-4.40%), pouring the premixed concrete waste into a ball mill and grinding for 20 minutes, then adding it into the calcined coal gangue powder, mixing and stirring to obtain a solid mixture A;

[0065] (2) taking the solid mixture A obtained in step (1) and moving it into a basin, adding 200 parts of water, sodium lauryl sulfate and tributylamine and soaking it for 30 minutes to obtain a solid-liquid mixture B;

[0066] (3) passing industrial grade CO2 gas with a purity of 99% into the solid-liquid mixture B obtained in step (2) and stirring for 4 hours, then pouring out excess water and drying in a forced air drying oven for 24 hours to obtain a solid mixture C;

[0067] (4) The solid mixture C obtained in step (3) is mixed with phosphogypsum and P·II42.5 grade ordinary Portland cement to obtain a carbonized calcined coal gangue solid waste-based cementitious material.

[0068] Comparative Example 1

[0069] The same as Example 3, except that the raw material coal gangue in step (1) is not calcined. Specifically, step (1) comprises: pouring the coal gangue into a ball mill and milling for 60 minutes, and then passing through a 0.075 mm sieve to obtain coal gangue powder; pouring the ready-mixed concrete waste into the ball mill and milling for 20 minutes, and then adding it to the calcined coal gangue powder, and mixing and stirring to obtain a solid mixture A.

[0070] Comparative Example 2

[0071] The same as Example 3, except that the premixed concrete waste residue in step (1) is not subjected to ball milling treatment. Step (1) is specifically as follows: the coal gangue is placed in a quartz crucible and placed in a muffle furnace for calcination, the temperature is set to 700°C for 2 hours and the heat preservation is carried out for 30 minutes. After completion, it is naturally cooled to obtain solid particles, and then poured into a ball mill for ball milling for 60 minutes and then sieved through a 0.075 mm sieve to obtain calcined coal gangue fine powder (apparent density is 2200-2500 kg / m 3 , water absorption rate is 2.10-4.40%), adding the premixed concrete waste slag into the calcined coal gangue powder, mixing and stirring to obtain a solid mixture A.

[0072] Comparative Example 3

[0073] Same as Example 3, except that air is introduced in step (3).

[0074] Performance Testing

[0075] Concrete was prepared using the cementitious materials prepared in Examples 1-3 and Comparative Examples 1-3 as raw materials:

[0076] The concrete uses 5-20mm continuous graded natural crushed stone, II zone medium sand river sand, polycarboxylic acid high-efficiency water-reducing agent with a water-reducing rate of 20%-30%, and Wuhan tap water. The sand ratio and water-cement ratio are 54% and 0.40 respectively, and the water-reducing agent dosage is 1.5%. The concrete is forcedly mixed by machine, and the feeding sequence is: after the coarse and fine aggregates are mixed evenly, the cementitious material is added, and after continuing to mix evenly, the mixing water mixed with admixtures is added, and then stirred for 3-5 minutes, and then the consistency test of the mixture is carried out and the specimens are formed. After demolding for 24 hours, standard curing is carried out to the specified age (28d). According to GB / T50081 2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete", the mechanical properties tests of cubic specimens with a size of 100mm×100mm×100mm (compressive strength test) and prism specimens with a size of 100mm×100mm×300mm (splitting tensile strength) are carried out. The performance test results are shown in Table 1.

[0077] Table 1 Statistical results of concrete index tests

[0078]

[0079] It can be seen from Table 1 that the compressive strength of the concrete in the three embodiments exceeds 35MPa, and can reach up to 44MPa, and the splitting tensile strength exceeds 3.0MPa, and can reach up to 3.5MPa. It can be seen from Example 3 and Comparative Example 1 that the addition of calcined coal gangue can improve the compressive strength and splitting crack resistance of the composite cementitious material, and the compressive strength and splitting crack resistance of the composite cementitious material can be improved by grinding the stirred waste slag, and the introduction of carbon dioxide can improve the calcined coal gangue solid waste-based cementitious material. This shows that calcining coal gangue, mixing it with ground stirred waste slag, and then carbonizing it can improve the mechanical properties of calcined coal gangue-based solid waste-based cementitious materials.

[0080] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A carbonized calcined coal gangue solid waste-based cementitious material, characterized in that: The invention comprises the following raw materials in parts by weight: 30-70 parts of calcined coal gangue powder, 20-50 parts of ready-mixed concrete waste residue, 10-20 parts of cement, 0-5 parts of gypsum, 0.5-1.0 parts of surfactant and 0.1-0.5 parts of organic amine.

2. The carbonized calcined coal gangue solid waste-based cementitious material according to claim 1, characterized in that: The particle size of the calcined coal gangue powder is less than 75 μm, and the apparent density is 2200-2500 kg / m 3 , the water absorption rate is 2.10-4.40%.

3. The carbonized calcined coal gangue solid waste-based cementitious material according to claim 1, characterized in that: The moisture content of the premixed concrete waste residue is less than 35%.

4. The carbonized calcined coal gangue solid waste-based cementitious material according to claim 1, characterized in that: The ordinary Portland cement is P·O42.5 grade ordinary Portland cement or PII42.5 grade Portland cement.

5. The carbonized calcined coal gangue solid waste-based cementitious material according to claim 1, characterized in that: The gypsum is dihydrate gypsum or industrial by-product gypsum.

6. The carbonized calcined coal gangue solid waste-based cementitious material according to claim 1, characterized in that: The surfactant is sodium lauryl sulfate or alkyl sulfonate.

7. The carbonized calcined coal gangue solid waste-based cementitious material according to claim 1, characterized in that: The organic amine is tributylamine or diethylbutylamine.

8. A method for preparing the carbonized calcined coal gangue solid waste-based cementitious material according to any one of claims 1 to 7, comprising the following steps: (1) Weighing various raw materials according to weight, ball-milling the ready-mixed concrete waste slag and mixing it with calcined coal gangue powder to obtain a solid mixture A; (2) soaking the solid mixture A with water, a surfactant, and an organic amine to obtain a solid-liquid mixture B; (3) introducing gas into the solid-liquid mixture B for stirring, and then drying to obtain a solid mixture C; (4) The solid mixture C is mixed with the gypsum and cement to obtain the carbonized calcined coal gangue solid waste-based cementitious material.

9. The method for preparing the carbonized gangue-based cementitious material according to claim 8, characterized in that: The solid mixture A is added with water, a surfactant and an organic amine and soaked for 30 minutes.

10. The method for preparing carbonized gangue-based cementitious material according to claim 8, characterized in that: In step (3), the stirring time of introducing industrial carbon dioxide gas is 4 hours.

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