CN112645622A - Preparation method of high-activity gangue admixture - Google Patents
Preparation method of high-activity gangue admixture Download PDFInfo
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- CN112645622A CN112645622A CN202110016839.4A CN202110016839A CN112645622A CN 112645622 A CN112645622 A CN 112645622A CN 202110016839 A CN202110016839 A CN 202110016839A CN 112645622 A CN112645622 A CN 112645622A
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- coal gangue
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- admixture
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- gypsum
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/04—Heat treatment
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Curing Cements, Concrete, And Artificial Stone (AREA)
Abstract
The invention discloses a preparation method of a high-activity gangue admixture, which comprises the following steps: s1: taking coal gangue as a raw material, and pre-grinding the coal gangue into powder; s2: carrying out dry mixing and wet mixing on 80-90% of coal gangue powder, 5-15% of calcium oxide and 5-15% of gypsum; s3: steaming the wet mixed product at 70-90 ℃ for 4-8 hours, and calcining the steamed product at 600-900 ℃ for 1-4 hours; s4: and naturally cooling the calcined product, and grinding the calcined product into powder to obtain the high-activity coal gangue admixture. The gangue admixture prepared by the invention has higher activity, can meet the requirements of cement-based materials in different ages on activity, is suitable for large-scale popularization and application, and has remarkable economic benefit and social benefit.
Description
Technical Field
The invention relates to the technical field of building materials, in particular to a preparation method of a high-activity coal gangue admixture.
Background
Coal gangue is a byproduct of coal mining and washing, the coal consumption is rapidly increased along with the increase of economic development and energy consumption, and the yield of the coal gangue is also increased year by year. The coal gangue is stacked and unreasonable in utilization, which causes the problems of large land occupation, resource waste, environmental pollution and the like. China, as one of three major coal consuming countries in the world, consumes a large amount of coal resources every year and also produces more coal gangue. According to statistics, the cumulative coal gangue yield in China exceeds 70 hundred million tons, and the coal gangue still increases at a rate of 3-3.5 million tons per year. The coal gangue contains a large amount of silicon-aluminum minerals, namely SiO2And Al2O3The content respectively reaches 30-60 percent and 15-40 percent, and is an applicable resource in the field of building materials.
From the chemical composition, the coal gangue has high SiO2And Al2O3The low calcium composition of (A) and the high calcium composition of the portland cement clinker can form complementation, thereby effectively improving the performance of the portland cement. However, the use of the unactivated coal gangue which is not treated by any method as a concrete admixture directly brings adverse effects on the performance of concrete. In order to activate or activate the coal gangue with low activity, the strength of the concrete is low, the performance development is slow, the mechanical property and durability of the concrete are reduced, and the coal gangue can cause great hidden trouble when being used as a member.
In the existing research on coal gangue-based admixtures, the coal gangue-based admixtures are mostly compounded with CaO, gypsum and the like, and the coal gangue-containing composite materials are calcined to improve the activity, for example, CN 102167532A (a method for preparing a concrete admixture by a concrete admixture and calcining coal gangue) proposes a process for mixing and calcining coal gangue, limestone, gypsum and fluorite to prepare a high-activity coal gangue composite admixture, but the preparation method has larger water demand. CN 106316178A (mineral admixture I-grade composite fly ash for concrete and manufacturing method thereof) is mixed and ground by using burnt-through coal gangue, blast furnace slag, converter slag and crushed silica, the prepared I-grade composite fly ash has low water demand but unknown activity, and the coal gangue accounts for a small proportion, thus having small contribution to the resource utilization of the coal gangue.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a preparation method of a high-activity coal gangue admixture, the coal gangue admixture prepared by the preparation method has high coal gangue proportion and high activity, can meet the use requirements of concrete with different construction requirements, and is suitable for large-scale popularization and application.
The technical scheme of the invention is as follows:
a preparation method of a high-activity coal gangue admixture comprises the following steps: s1: taking coal gangue as a raw material, and pre-grinding the coal gangue into powder; s2: carrying out dry mixing and wet mixing on 80-90% of coal gangue powder, 5-15% of calcium oxide and 5-15% of gypsum; s3: steaming the wet mixed product at 70-90 ℃ for 4-8 hours, and calcining the steamed product at 600-900 ℃ for 1-4 hours; s4: and naturally cooling the calcined product, and grinding the calcined product into powder to obtain the high-activity coal gangue admixture.
Preferably, the specific surface area of the coal gangue after pre-grinding is more than or equal to 200m2/kg。
Preferably, the gypsum is one or more of anhydrous gypsum, hemihydrate gypsum, dihydrate gypsum, phosphogypsum and desulfurization gypsum.
Preferably, when the gangue powder, the calcium oxide and the gypsum are wet-mixed, the wet-mixing is carried out for 5 to 20 minutes at a water-powder ratio of 0.1 to 0.25.
Preferably, the gangue powder is wet-mixed with the calcium oxide and the gypsum in the form of spray.
Preferably, the steamed product is pelletized in a pelletizer before being calcined, and then the pelletized mixture is calcined.
Preferably, the particle size of the spherical mixture is 5 to 20 mm.
Preferably, the specific surface area of the high-activity coal gangue admixture is more than or equal to 350m2/kg。
The invention has the beneficial effects that:
the activity of the coal gangue powder is simultaneously improved from three aspects of hydrothermal alteration, calcination and calcium oxide content improvement, and the method comprises the following specific steps: pre-grinding coal gangue into powder, mixing the powder with calcium oxide and gypsum, performing autoclave curing in advance, and preliminarily exciting the activity of the coal gangue through hydrothermal alteration; then calcining the pre-excited coal gangue again to convert kaolin in the coal gangue into metakaolin, so as to improve the activity of the coal gangue powder; in addition, the calcium oxide doped in advance improves the calcium oxide content of the gangue admixture, and further improves the activity of the gangue powder. The coal gangue admixture prepared by the invention has higher activity, can be directly used in concrete construction, can be formed by mixing the admixture with concrete and adding water and then stirring, and has the same curing system as common concrete; in addition, the method can also be used for producing cement-based materials, reduces stacking of coal gangue and environmental pollution caused by the coal gangue, and reduces energy consumption.
Detailed Description
The present invention will be further described with reference to the following examples.
It should be noted that, in the present application, the embodiments and the technical features of the embodiments may be combined with each other without conflict.
It is noted that, unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
Example 1
A preparation method of a high-activity coal gangue admixture comprises the following steps:
s1: coal gangue is used as raw material, and is pre-ground into powder by using a ball mill, so that the specific surface area of the coal gangue reaches 200m2/kg。
S2: the gangue powder is dry-mixed with 5% calcium oxide and 5% semi-hydrated gypsum for 15 minutes in a dry mixing mode according to 90% of gangue powder, and then the powder is wet-mixed for 15 minutes in a water-to-powder ratio of 0.15 by using tap water in a spraying mode.
S3: steaming the wet mixed product at 80 ℃ for 6 hours, taking out the product, balling the product by using a balling machine to ensure that the grain diameter of the spherical mixture is between 5 and 20mm, calcining the spherical mixture at 700 ℃ for 4 hours, taking out the mixture, and naturally cooling the mixture at room temperature.
S4: grinding the cooled material in a ball mill for 15 minutes to ensure that the specific surface area reaches 400m2And/kg, obtaining the high-activity coal gangue admixture.
Example 2
A preparation method of a high-activity coal gangue admixture comprises the following steps:
s1: coal gangue is used as raw material, and is pre-ground into powder by using a ball mill, so that the specific surface area of the coal gangue reaches 300m2/kg。
S2: the coal gangue powder 80%, the calcium oxide 15% and the phosphogypsum 5% are dry-mixed for 15 minutes, and then the powder is wet-mixed for 20 minutes by using tap water and adopting a spraying mode according to a water-powder ratio of 0.15.
S3: steaming the wet mixed product at 80 ℃ for 4 hours, taking out the product, balling the product by using a balling machine to ensure that the grain diameter of the spherical mixture is between 5 and 20mm, calcining the spherical mixture at 800 ℃ for 2 hours, taking out the mixture, and naturally cooling the mixture at room temperature.
S4: grinding the cooled material in a ball mill for 10 minutes to ensure that the specific surface area reaches 350m2And/kg, obtaining the high-activity coal gangue admixture.
Example 3
A preparation method of a high-activity coal gangue admixture comprises the following steps:
s1: coal gangue is used as raw material, and is pre-ground into powder by a ball mill, so that the specific surface area of the coal gangue reaches 400m2/kg。
S2: the coal gangue powder 80%, the calcium oxide 15%, the dihydrate gypsum 3% and the phosphogypsum 2% are dry-mixed for 15 minutes, and then the powder is wet-mixed for 20 minutes by using tap water and adopting a spraying mode and a water-powder ratio of 0.2.
S3: steaming the wet mixed product at 80 ℃ for 4 hours, taking out the product, balling the product by using a balling machine to ensure that the grain diameter of the spherical mixture is between 5 and 20mm, calcining the spherical mixture at 800 ℃ for 2 hours, taking out the mixture, and naturally cooling the mixture at room temperature.
S4: grinding the cooled material in a ball mill for 5 minutes to ensure that the specific surface area reaches 400m2And/kg, obtaining the high-activity coal gangue admixture.
Test example
The high-activity coal gangue admixtures prepared in examples 1-3 were mixed into cement mortar according to the mass percent of the cementing material of 30%, and compared with the directly calcined and ground coal gangue, the activities of the coal gangue admixtures were tested for 14 days and 28 days, and the test results of each group are shown in table 1:
TABLE 1 test results of coal gangue admixtures activity in each example
| Examples | 14d | 28d |
| Control group | 68.3 | 75.6 |
| Example 1 | 78.1 | 87.1 |
| Example 2 | 84.2 | 88.2 |
| Example 3 | 86.4 | 89.4 |
As can be seen from table 1, the activity of the gangue powder can be significantly improved using the embodiments of the present invention. Mixing coal gangue powder with calcium oxide and gypsum, performing autoclave curing in advance, eroding quartz and feldspar by hydrothermal alteration process, and causing Al-O band fracture and Silicon (SiO) enrichment by the alkalinity of calcium oxide2·nH2O), and preliminarily exciting the activity of the coal gangue. Meanwhile, under the action of heat and mechanics, the kaolinite is dehydroxylated and converted into metakaolinite, so that the silicon-oxygen and aluminum-oxygen bond structures in the gangue minerals are further destroyed to generate activity. In addition, the addition of the calcium oxide also plays a certain role in improving the activity of the coal gangue powder. Therefore, the coal gangue powder prepared by the method has higher activity.
In addition to the above examples, the inventors also performed other examples of changing the amounts (e.g., end points, intermediate values), steam curing temperature, steam curing time, calcination temperature, calcination time, etc. of the components by experimental design methods such as orthogonal experiments, etc., and the activities of the obtained coal gangue admixtures were improved compared to the control.
It should be noted that, the steam cured product is pelletized in a pelletizer, and then the pelletized mixture is calcined, which can make the phases react better and more fully at high temperature, but it is not an essential condition, and the high activity coal gangue admixture can also be prepared by directly calcining after steam curing.
Although the present invention has been described with reference to a preferred embodiment, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (8)
1. The preparation method of the high-activity coal gangue admixture is characterized by comprising the following steps:
s1: taking coal gangue as a raw material, and pre-grinding the coal gangue into powder;
s2: carrying out dry mixing and wet mixing on 80-90% of coal gangue powder, 5-15% of calcium oxide and 5-15% of gypsum;
s3: steaming the wet mixed product at 70-90 ℃ for 4-8 hours, and calcining the steamed product at 600-900 ℃ for 1-4 hours;
s4: and naturally cooling the calcined product, and grinding the calcined product into powder to obtain the high-activity coal gangue admixture.
2. The method for preparing the high-activity coal gangue admixture as defined in claim 1, wherein the coal gangue is pre-pulverized to have a specific surface area of 200m or more2/kg。
3. The method for preparing the high-activity coal gangue admixture as defined in claim 1, wherein the gypsum is one or more of anhydrite, hemihydrate gypsum, dihydrate gypsum, phosphogypsum and desulfurized gypsum.
4. The method for preparing the high-activity coal gangue admixture as defined in claim 1, wherein the wet mixing of the coal gangue powder, the calcium oxide and the gypsum is carried out for 5-20 minutes at a water-to-powder ratio of 0.1-0.25.
5. The method for preparing the high-activity coal gangue admixture as defined in claim 4, wherein the coal gangue powder is wet-mixed with the calcium oxide and the gypsum in the form of spraying.
6. The method for preparing the high-activity coal gangue admixture as defined in claim 1, wherein the steamed product is pelletized in a pelletizer before being calcined, and then the pelletized mixture is calcined.
7. The method for preparing the high-activity coal gangue admixture as defined in claim 6, wherein the particle size of the spherical mixture is 5-20 mm.
8. The method for preparing the high-activity coal gangue admixture as defined in any one of claims 1 to 7, wherein the high-activity coal gangue admixture has a specific surface area of 350m or more2/kg。
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| CN202110016839.4A CN112645622A (en) | 2021-01-07 | 2021-01-07 | Preparation method of high-activity gangue admixture |
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| CN202110016839.4A CN112645622A (en) | 2021-01-07 | 2021-01-07 | Preparation method of high-activity gangue admixture |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN115321864A (en) * | 2022-08-31 | 2022-11-11 | 中南大学 | Cooling method on coal gangue belt type sintering decarburization machine |
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2021
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| CN101391868A (en) * | 2008-10-17 | 2009-03-25 | 清华大学 | Hydrothermal alternation pre-treatment process of inert salic material |
| CN102167532A (en) * | 2010-12-15 | 2011-08-31 | 中国矿业大学(北京) | concrete admixture and a method for preparing the concrete admixture by calcining coal gangue |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115321864A (en) * | 2022-08-31 | 2022-11-11 | 中南大学 | Cooling method on coal gangue belt type sintering decarburization machine |
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Application publication date: 20210413 |