CN114573318A - Special mixture for aerated concrete and preparation method thereof - Google Patents

Abstract

The invention discloses a special mixture for aerated concrete and a preparation method, belongs to the technical field of cementitious materials, and solves the problems of large fluctuation of raw materials for aerated concrete, unstable quality, high energy consumption, high _CO2 emission and environmental impact in the prior art. big problem. The preparation method of the present invention includes: preparing mixed raw meal, the raw meal comprising 30%-40% of calcium carbide slag, 56%-68% of siliceous coal gangue and 2%-4% of industrial by-product gypsum; The raw meal is calcined to obtain a mixed clinker; a dispersant is added to the clinker, and the mixture is mixed and ground to obtain a special mixture for aerated concrete. The invention also discloses the special mixture for air-entrained concrete prepared by the above method. The method of the invention solves the simultaneous supply of calcareous, siliceous and sulphuric materials required for the preparation of aerated concrete in one step, simplifies the preparation process of the raw material of the aerated concrete, and reduces the difficulty of controlling the preparation of the raw material. The raw materials used in the present invention are all bulk solid wastes, which are energy-saving and environment-friendly.

Description

A kind of special mixture for air-entrained concrete and preparation method thereof

technical field

The invention belongs to the technical field of cementitious materials, and in particular relates to a special mixture for aerated concrete and a preparation method.

Background technique

Air-entrained concrete is based on calcareous materials (lime, cement) and siliceous materials (quartz sand, river sand, fly ash and siliceous tailings, etc.) Powder paste) air-entraining agent, after mixing with water, gas is obtained by chemical reaction, and it is a lightweight porous silicate product made by batching, stirring, pouring, pre-curing, cutting, curing and other processes. It is a new building material with many advantages such as quality, heat preservation, fire prevention, sound absorption and environmental protection. In the production of conventional aerated concrete, raw materials such as lime, cement, gypsum, and siliceous materials need to be purchased separately. The siliceous materials in the purchased raw materials need to be separately ground and stored, and then mixed with lime, cement, gypsum and other calcareous materials and mixed. Water and other ingredients are mixed and stirred to prepare slurry, which is difficult to control and complex in process. In particular, the quality of the purchased lime, gypsum, and siliceous materials fluctuates greatly, resulting in large fluctuations in the performance and quality of aerated concrete products. In addition, among the raw materials of aerated concrete, both cement and lime production require high-temperature calcination and a large amount of limestone, resulting in high energy consumption, high _CO2 emissions, and a large environmental impact.

In view of this, it is necessary to design a special mixture for aerated concrete and its preparation method. The special mixture should contain lime (CaO), gypsum, and siliceous materials with suitable composition at the same time, so as to reduce the fluctuation of raw material quality and reduce the difficulty of batching process. At the same time, calcium, silicon and sulfur solid wastes with low carbonate content should be used as raw materials for the preparation of special mixtures, so as to reduce the consumption of natural mineral resources, energy consumption, and CO ₂ emissions in the preparation of special mixtures, and improve the green and low-carbon products of products. content.

SUMMARY OF THE INVENTION

One of the objectives of the present invention is to provide a method for preparing a special mixture for air-entrained concrete, which solves the problems in the prior art that the raw material of air-entrained concrete fluctuates greatly, the quality is unstable, the energy consumption is high, the CO ₂ emission is high, and the environmental impact is large. question.

The second purpose of the present invention is to provide a special mixture for air-entrained concrete prepared by the preparation method.

For achieving the above object, the technical scheme adopted in the present invention is as follows:

The preparation method of a kind of special admixture for air-entrained concrete provided by the present invention comprises the following steps:

S1. Prepare mixed raw meal, the raw meal includes 30%-40% calcium carbide slag, 56%-68% siliceous coal gangue and 2%-4% industrial by-product gypsum by mass percentage;

S2. clinker calcination, calcining the mixed material raw meal to obtain the mixed material clinker;

S3. The mixture is prepared, the dispersant is mixed into the clinker obtained in S2, and the mixture is mixed and ground to a powder with a sieve ratio of less than 20% by a 80-micron square-hole sieve to obtain a special mixture for aerated concrete.

In some embodiments of the present invention, before preparing the mixed raw meal, each raw material of the raw meal is pre-crushed to a particle size of less than 15 mm.

In some embodiments of the present invention, the content of Ca(OH) ₂ in the carbide slag is greater than 85 wt%, and the content of adhering water is less than 3 wt%.

In some embodiments of the present invention, the content of SiO ₂ in the siliceous coal gangue is greater than 60 wt %, the content of Al ₂ O ₃ is less than 20 wt %, and the content of combined water is less than 10 wt %.

In some embodiments of the present invention, the industrial by-product gypsum includes at least one of desulfurized gypsum, phosphogypsum, titanium gypsum and mirabilite gypsum, and the content of CaSO ₄ .2H ₂ O in the industrial by-product gypsum is greater than 85 wt %, and water adheres to Content<5wt%.

In some embodiments of the present invention, the dispersing agent includes at least one of triethanolamine, triisopropanolamine, and ethylene glycol monoisopropanolamine.

In some embodiments of the present invention, the S2 is calcined at 550-650° C. for 20-60 min; preferably, calcined for 30 min.

In some embodiments of the present invention, the dosage of the dispersant is 0.01-0.1% by mass of the clinker, preferably 0.05%.

The special mixture for air-entrained concrete prepared by the preparation method of the above-mentioned special mixture for air-entrained concrete provided by the present invention.

In some embodiments of the present invention, the special admixture for air-entrained concrete comprises 25-35wt% of CaO, 45-55wt% of SiO ₂ and 1.5-2.5wt% of SO ₃ .

The calcareous material (lime, CaO) in the special mixture for air-entrained concrete of the present invention is derived from the calcination of calcium carbide slag. The chemical composition of calcium carbide slag is mainly Ca(OH) ₂ , and CaO is produced by dehydration during calcination. This is different from the traditional lime prepared by calcining limestone, and the calcium carbide slag in the present invention has a low calcination and dehydration temperature, does not emit CO ₂ , and produces higher CaO activity, which can fully meet the needs and requirements of calcareous materials for air-entrained concrete.

The siliceous material (SiO ₂ ) in the special mixture for air-entrained concrete of the present invention is derived from the calcination of siliceous coal gangue. SiO ₂ in siliceous coal gangue exists in quartz and clay minerals. During the calcination of siliceous coal gangue, clay minerals are dehydrated and decomposed to release part of amorphous SiO ₂ with higher activity, which improves the reaction between siliceous materials and calcareous materials. Activity, which helps to improve the quality of air-entrained concrete.

In the prior art, gypsum also needs to be added in the preparation process of air-entrained concrete to adjust the lime digestion speed, slurry consistency and setting time, and at the same time, gypsum can also promote siliceous and calcareous materials to generate more tobomo under hydrothermal conditions. Beneficial minerals such as stone. However, the industrial by-product gypsum mainly composed of CaSO ₄ .2H ₂ O contains more soluble phosphorus and fluorine compounds, which will reduce the properties of air-entrained concrete paste and products. In the preparation method of the present invention, the industrial by-product gypsum is used as a raw material, and through calcination, CaSO ₄ .2H ₂ O is converted into stable and active anhydrous CaSO ₄ , and at the same time, phosphorus and fluorine compounds are volatilized and removed during the calcination process to avoid The influence of impurities on the quality of aerated concrete.

When preparing aerated concrete, the special mixture for air-entrained concrete of the invention is directly mixed with water and aluminum powder paste for the production of air-entrained concrete of various grades.

Compared with the prior art, the present invention has the following beneficial effects:

The invention has scientific design and ingenious conception. The special mixture for aerated concrete prepared by the method of the invention does not need to be separately mixed with lime, cement, fly ash, quartz sand, gypsum and other materials, and can be directly mixed with water and aluminum powder paste. Mixing is used in the production of various grades of aerated concrete, which overcomes the problems of raw material quality control, complex batching process and unstable product quality in the production process of aerated concrete.

The preparation method of the invention simultaneously realizes the dehydration of calcium carbide slag to generate active CaO, the dehydration of siliceous coal gangue to generate activated SiO ₂ , the dehydration of industrial by-product gypsum to generate active anhydrite and the removal of harmful impurities simultaneously during the calcination process, and a single step solves the problem of aeration. Simultaneous supply of calcium, siliceous and sulfur materials required for concrete preparation simplifies the preparation process of aerated concrete raw materials and reduces the difficulty of raw material preparation and control.

The raw material calcium carbide slag, siliceous coal gangue and industrial by-product gypsum used in the present invention are all bulk solid wastes, and the air-entrained concrete of the present invention does not need to be mixed with other natural ore resources, fully embodying the concept of energy saving and environmental protection.

Detailed ways

Hereinafter, a special admixture for air-entrained concrete and a preparation method thereof according to the present invention will be described in detail using examples.

A preparation method of a special mixture for air-entrained concrete, comprising the following steps:

S1. Prepare mixed raw meal, the raw meal includes 30%-40% calcium carbide slag, 56%-68% siliceous coal gangue and 2%-4% industrial by-product gypsum by mass percentage;

S2. clinker calcination, calcining the mixed material raw meal to obtain the mixed material clinker;

S3. The mixture is prepared, the dispersant is mixed into the clinker obtained in S2, and the mixture is mixed and ground to a powder with a sieve ratio of less than 20% by a 80-micron square-hole sieve to obtain a special mixture for aerated concrete.

Before preparing the mixed raw meal, each raw material of the raw meal is pre-crushed to a particle size of less than 15 mm.

The content of Ca(OH) ₂ in the carbide slag is more than 85wt%, and the content of attached water is less than 3wt%.

In the siliceous coal gangue, the content of SiO ₂ is more than 60 wt %, the content of Al ₂ O ₃ is less than 20 wt %, and the content of combined water is less than 10 wt %.

The industrial by-product gypsum includes at least one of desulfurization gypsum, phosphogypsum, titanium gypsum and mirabilite gypsum, and the industrial by-product gypsum has a CaSO ₄ .2H ₂ O content of >85wt% and an attached water content of <5wt%.

The dispersing agent includes at least one of triethanolamine, triisopropanolamine, and ethylene glycol monoisopropanolamine.

In the S2, calcination is performed at 550-650° C. for 20-60 min; preferably, calcination is performed for 30 min.

The dosage of the dispersant is 0.01-0.1% of the clinker mass, preferably 0.05%.

The special mixture for aerated concrete is prepared by the preparation method of the special mixture for air-entrained concrete.

The special mixture for air-entrained concrete comprises 25-35wt% of CaO, 45-55wt% of SiO ₂ and 1.5-2.5wt% of SO ₃ .

When preparing aerated concrete, the special mixture for air-entrained concrete of the invention is directly mixed with water and aluminum powder paste for the production of air-entrained concrete of various grades.

The content of Ca(OH) ₂ used in the examples of the present invention is more than 85 wt %, and the content of attached water is less than 3 wt %.

In the siliceous coal gangue used in the embodiments of the present invention, the SiO ₂ content is greater than 60 wt %, the Al ₂ O ₃ content is less than 20 wt %, and the combined water content is less than 10 wt %.

The content of CaSO ₄ .2H ₂ O in the industrial by-product gypsum used in the embodiment of the present invention is more than 85wt%, and the content of attached water is less than 5wt%.

Example 1

The present embodiment discloses the preparation method of the special mixture for air-entrained concrete of the present invention, specifically:

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum phosphogypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 30wt% of carbide slag, 67wt% of siliceous coal gangue and 3wt% of industrial by-product gypsum;

3) calcining the clinker, calcining the raw material of the mixed material in an electric heating furnace at 650° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with the dispersant triethanolamine accounting for 0.05% of the clinker mass, mixed and ground to a powder with an 80-micron square-hole sieve remaining less than 20%, to obtain a special mixture for aerated concrete .

Example 2

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum desulfurization gypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 35wt% of carbide slag, 62wt% of siliceous coal gangue and 3wt% of industrial by-product gypsum;

3) calcining the clinker, and calcining the raw material of the mixed material in an electric heating furnace at 600° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with the dispersant triisopropanolamine which accounts for 0.05% of the clinker mass, mixed and ground to a powder with a sieve of 80 microns square sieve less than 20%, and the air-entrained concrete is obtained Special mix.

Example 3

1) pre-crushing calcium carbide slag, siliceous coal gangue, industrial by-product gypsum Glauber's gypsum respectively to particle size＜15mm;

2) prepare mixed raw meal, the raw meal includes 40wt% of carbide slag, 57wt% of siliceous coal gangue and 3wt% of industrial by-product gypsum;

3) calcining the clinker, and calcining the raw material of the mixed material in an electric heating furnace at 550° C. for 30 minutes to obtain the mixed material clinker;

4) The mixed material is prepared. The dispersant ethylene glycol monoisopropanolamine, which accounts for 0.05% of the clinker mass, is mixed into the clinker, and the powder is mixed and ground to a powder with a sieve ratio of less than 20% of the 80-micron square-hole sieve to obtain Special mix for aerated concrete.

Example 4

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum titanium gypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 30wt% of carbide slag, 68wt% of siliceous coal gangue and 2wt% of industrial by-product gypsum;

3) calcining the clinker, calcining the raw material of the mixed material in an electric heating furnace at 650° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with the dispersant triethanolamine accounting for 0.05% of the clinker mass, mixed and ground to a powder with an 80-micron square-hole sieve remaining less than 20%, to obtain a special mixture for aerated concrete .

Example 5

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum phosphogypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 35wt% of carbide slag, 63wt% of siliceous coal gangue and 2wt% of industrial by-product gypsum;

3) calcining the clinker, and calcining the raw material of the mixed material in an electric heating furnace at 600° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with the dispersant triethanolamine accounting for 0.05% of the clinker mass, mixed and ground to a powder with an 80-micron square-hole sieve remaining less than 20%, to obtain a special mixture for aerated concrete .

Example 6

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum phosphogypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 40wt% of carbide slag, 58wt% of siliceous coal gangue and 2wt% of industrial by-product gypsum;

3) calcining the clinker, and calcining the raw material of the mixed material in an electric heating furnace at 550° C. for 30 minutes to obtain the mixed material clinker;

4) The mixed material is prepared. The dispersant ethylene glycol monoisopropanolamine, which accounts for 0.05% of the clinker mass, is mixed into the clinker, and the powder is mixed and ground to a powder with a sieve ratio of less than 20% of the 80-micron square-hole sieve to obtain Special mix for aerated concrete.

Example 7

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum phosphogypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 30wt% of carbide slag, 66wt% of siliceous coal gangue and 4wt% of industrial by-product gypsum;

3) calcining the clinker, calcining the raw material of the mixed material in an electric heating furnace at 650° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with the dispersant triisopropanolamine which accounts for 0.05% of the clinker mass, mixed and ground to a powder with a sieve of 80 microns square sieve less than 20%, and the air-entrained concrete is obtained Special mix.

Example 8

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum desulfurization gypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 35wt% of carbide slag, 61wt% of siliceous coal gangue and 4wt% of industrial by-product gypsum;

3) calcining the clinker, and calcining the raw material of the mixed material in an electric heating furnace at 600° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with a dispersant accounting for 0.05% of the mass of the clinker, mixed and ground to a powder with a sieve of 80 micron square holes less than 20% to obtain a special mixture for aerated concrete.

Example 9

1) pre-crushing calcium carbide slag, siliceous coal gangue and industrial by-product gypsum titanium gypsum to particle size <15mm;

2) preparing mixed raw meal, the raw meal includes 40wt% of carbide slag, 56wt% of siliceous coal gangue and 4wt% of industrial by-product gypsum;

3) calcining the clinker, and calcining the raw material of the mixed material in an electric heating furnace at 550° C. for 30 minutes to obtain the mixed material clinker;

4) The mixture is prepared, the clinker is mixed with the dispersant triethanolamine accounting for 0.05% of the clinker mass, mixed and ground to a powder with an 80-micron square-hole sieve remaining less than 20%, to obtain a special mixture for aerated concrete .

Comparative Example 1

Compared with Example 1, the calcination temperature of this comparative example is 540°C, and other conditions are the same.

Comparative Example 2

Compared with Example 1, the calcination temperature of this comparative example is 680°C, and other conditions are the same.

Each component of the special admixture for air-entrained concrete prepared by Example 1-9 and Comparative Example 1-2 is measured, and the results are shown in the following table:

Table 1 shows the raw meal composition and calcination temperature of the mixed materials of Examples 1-9 and Comparative Examples 1-2.

Table 1

It can be seen from the above data that the special mixture for air-entrained concrete prepared by the embodiment of the present invention contains calcium, siliceous and gypsum components required for the preparation of air-entrained concrete, and the calculated CaO/SiO ₂ molar ratio is 0.5 Between -0.83, it meets the requirements of the molar ratio of CaO/SiO ₂ in the ingredients of air-entrained concrete. The prepared special mixture for aerated concrete can no longer be mixed with lime, cement, fly ash, quartz sand, gypsum and other materials, and can be directly mixed with water and aluminum powder paste for the production of various grades of aerated concrete.

Comparative example 1, the calcination temperature is too low, the crystal water content in carbide slag, gypsum and coal gangue is high, the content of limited components such as silicon aluminum sulfur is reduced, and the system activity is low; comparative example 2, the calcination temperature is too high, anhydrous CaSO ₄ Overburning (decreased solubility), can not play the role of adjusting the consistency and setting time.

Although the present invention has been described above in connection with the exemplary embodiments, it will be apparent to those skilled in the art that various modifications and variations can be made in the exemplary embodiments of the present invention without departing from the spirit and scope defined by the appended claims. Change.

Claims (10)

1. a preparation method of aerated concrete special mixture, is characterized in that, comprises the following steps: S1. Prepare mixed raw meal, the raw meal includes 30%-40% calcium carbide slag, 56%-68% siliceous coal gangue and 2%-4% industrial by-product gypsum by mass percentage; S2. clinker calcination, calcining the mixed material raw meal to obtain the mixed material clinker; S3. The mixture is prepared, the dispersant is mixed into the clinker obtained in S2, and the mixture is mixed and ground to a powder with a sieve ratio of less than 20% by a 80-micron square-hole sieve to obtain a special mixture for aerated concrete. 2 . The preparation method of a special mixture for aerated concrete according to claim 1 , characterized in that, before preparing the mixed raw meal, each raw material of the raw meal is pre-crushed to a particle size of less than 15 mm. 3 . 3 . The preparation method of a special mixture for air-entrained concrete according to claim 1 , wherein the calcium carbide slag has a Ca(OH) ₂ content of >85 wt % and an attached water content of < 3 wt %. 4 . 4. The preparation method of a special mixture for air-entrained concrete according to claim ₁ , characterized in that, in the siliceous coal gangue, the content of _SiO2 >60wt%, the content of _Al2O3 <20wt%, the combined water Content<10wt%. 5. the preparation method of a kind of special admixture for aerated concrete according to claim 1, is characterized in that, described industrial by-product gypsum comprises at least one in desulfurization gypsum, phosphogypsum, titanium gypsum, mirabilite gypsum, industrial The content of CaSO ₄ .2H ₂ O in the by-product gypsum is more than 85wt%, and the content of attached water is less than 5wt%. 6. the preparation method of a kind of special admixture for air-entrained concrete according to claim 1, is characterized in that, described dispersant comprises at least in triethanolamine, triisopropanolamine, ethylene glycol monoisopropanolamine A sort of. 7. The preparation method of a kind of special mixture for air-entrained concrete according to any one of claims 1-6, characterized in that, in the S2, calcining at 550-650°C for 20-60min; preferably, Calcined for 30min. 8 . The preparation method of a special mixture for air-entrained concrete according to claim 7 , wherein the dosage of the dispersant is 0.01-0.1% of the clinker mass, preferably 0.05%. 9 . 9. The special mixture for aerated concrete prepared by the method for preparing a special mixture for aerated concrete according to any one of claims 1-8. 10 . The special mixture for aerated concrete according to claim 9 , wherein the special mixture for aerated concrete comprises 25-35wt% CaO, 45-55wt% SiO and _1.5-2.5wt % SO ₃ .