阅读说明：本技术 一种赤泥地聚物骨料及其制备方法 (Red mud geopolymer aggregate and preparation method thereof ) 是由 王琰帅 董必钦 戴建国 邢锋 洪舒贤 田凯歌 侯东帅 于 2020-04-22 设计创作，主要内容包括：本发明提供了一种赤泥地聚物骨料及其制备方法,所述赤泥地聚物骨料的原材料包括如下重量份的组分：赤泥50～100份；激发剂1～10份；粉煤灰0～40份；水20～60份。本发明提供的赤泥地聚物骨料具有较高的力学性能和抗压强度,具有更加广泛的工程应用。(The invention provides red mud geopolymer aggregate and a preparation method thereof, wherein the raw materials of the red mud geopolymer aggregate comprise the following components in parts by weight: 50-100 parts of red mud; 1-10 parts of an excitant; 0-40 parts of fly ash; 20-60 parts of water. The red mud geopolymer aggregate provided by the invention has higher mechanical property and compressive strength, and has wider engineering application.)

1. The red mud geopolymer aggregate is characterized in that raw materials of the red mud geopolymer aggregate comprise the following components in parts by weight:

2. the red mud geopolymer aggregate of claim 1, wherein the activator is at least one selected from sulfuric acid, carbonic acid, phosphoric acid, sodium hydroxide, calcium hydroxide, sodium chloride, sodium carbonate, sodium silicate, and sodium sulfate.

3. The red mud geopolymer aggregate of claim 1, wherein the activator is selected from any one of a combination of sodium hydroxide and sodium silicate, a combination of calcium hydroxide and sodium sulfate, and a combination of phosphoric acid and aluminum dihydrogen phosphate.

4. The red mud geopolymer aggregate according to any one of claims 1 to 3, wherein the raw material of the red mud geopolymer aggregate further comprises 0.01 to 1 part of an additive.

5. The red mud geopolymer aggregate according to any one of claims 1 to 3, wherein the median diameter of the red mud is 1.3 to 1.6 μm.

6. The red mud geopolymer aggregate according to any one of claims 1 to 3, wherein the red mud geopolymer aggregate is spherical particles, and the particle size of the spherical particles is 500 μm to 10 mm.

7. The preparation method of the red mud geopolymer aggregate is characterized by comprising the following steps:

weighing the components according to the formula of the raw material of the red mud geopolymer aggregate of any one of the claims 1 to 6;

pretreating the red mud, and mixing the pretreated red mud with fly ash and water to obtain a first mixture;

and mixing and granulating the first mixture and an exciting agent to obtain the red mud geopolymer aggregate.

8. The method for preparing red mud geopolymer aggregate according to claim 7, further comprising curing the red mud geopolymer aggregate.

9. The method for preparing red mud geopolymer aggregate according to claim 7, wherein in the step of pretreating the red mud, the pretreatment method comprises the following steps: and drying the red mud at 60-80 ℃, and then carrying out ball milling treatment.

10. The preparation method of the red mud geopolymer aggregate according to claim 7, wherein in the step of mixing the pretreated red mud with the fly ash and water, the red mud is mixed in a stirring manner at a rotation speed of 30-35 rpm for 1-10 minutes; and/or the presence of a gas in the gas,

and in the step of mixing and granulating the first mixture and the exciting agent to obtain the red mud aggregate, mixing and granulating in a stirring mode at a rotating speed of 60-65 rpm for 10-15 minutes.

Technical Field

The invention relates to the field of concrete materials, in particular to red mud geopolymer aggregate and a preparation method thereof.

Background

At present, the national requirements promote the comprehensive utilization of metallurgical slag, chemical slag, red mud, phosphogypsum and other industrial wastes, promote a batch of advanced applicable technologies and equipment, and enhance the recycling of strategic rare and precious metals in industrial solid wastes.

Red mud is industrial solid waste discharged in the production process of alumina, and contains a large amount of ferric oxide and is red powder. The output and components of red mud vary with the grade of ore, production method and technical level, and according to statistics, 0.5-2.0 tons of red mud are generated for each 1 ton of alumina. Currently, the alkaline process for producing alumina, which is common in industry, comprises three types, namely, a sintering process, a bayer process and a combined process. China, as the 4 th alumina producing country in the world, has the alumina yield increased year by year, and the red mud discharged each year is up to millions of tons. If a large amount of red mud cannot be fully and effectively utilized, the red mud can be stacked only by a large-area yard, so that a large amount of land is occupied, and the environment is seriously polluted. Therefore, the comprehensive recycling of the red mud is very important.

The cement concrete pavement is a pavement structure which is most commonly used in China, the scale of new construction is huge every year, and a large amount of sand and stone raw materials are consumed. However, the cement stabilized macadam structure or the lime-fly ash macadam structure adopted by the base course and the subbase of the traditional cement concrete pavement structure has large strength variation and serious thermal shrinkage and drying shrinkage cracking, and is easy to cause damages such as plate breakage, void and the like on the cement concrete pavement. At present, a lot of researches are carried out on applying red mud as an admixture to a cement concrete material, but the red mud mixing amount is low, and the mechanical property of the material is obviously reduced along with the doping of the red mud. Therefore, the comprehensive utilization effect of the red mud is not ideal, and the red mud cannot be well applied to engineering application such as construction.

Disclosure of Invention

The invention aims to provide red mud geopolymer aggregate and a preparation method thereof, and aims to solve the problems that the mechanical strength and compressive strength of red mud are too low in the prior art, so that the comprehensive utilization effect is not good, and the application to engineering application is not facilitated.

In order to achieve the purpose, the invention adopts the following technical scheme:

the red mud geopolymer aggregate comprises the following raw materials in parts by weight:

and the preparation method of the red mud geopolymer aggregate comprises the following steps:

weighing the components according to the formula of the raw material of the red mud geopolymer aggregate;

pretreating the red mud, and mixing the pretreated red mud with fly ash and water to obtain a first mixture;

and mixing and granulating the first mixture and an exciting agent to obtain the red mud geopolymer aggregate.

The red mud geopolymer aggregate provided by the invention takes the red mud as a main raw material, and the red mud mainly contains SiO₂、Al₂O₃、CaO、Fe₂O₃And the like, under the action of an excitant, the red mud and water are subjected to hydration reaction to form A product with A C- (A) -S-H gel structure or an S-A-P-H, S-A-H gel structure through interaction, A network structure is formed inside the red mud, the crosslinking performance of the red mud material is enhanced, and the compressive strength of the mechanical strength of the red mud material is improved. The red mud geopolymer aggregate provided by the invention can be selectively added with fly ash, the fly ash is mixed with the red mud, and the red mud geopolymer aggregate with different density grades is prepared according to requirements, so that the red mud geopolymer aggregate can achieve higher mechanical property and compressive strength, and on one hand, the red mud raw material can be recycled on a large scale to form the red mud geopolymer aggregate; on the other hand, the red mud geopolymer aggregate can achieve higher mechanical property and compressive strength, and can replace common building sand to be widely applied to engineering applications such as buildings and the like.

According to the preparation method of the red mud geopolymer aggregate, the red mud is pretreated, and other components are mixed, so that the components can be uniformly dispersed, and the red mud geopolymer aggregate has high compressive strength and excellent stability. In addition, the preparation method has simple process, controllable conditions and low equipment requirement, and can be used for industrial production.

Drawings

FIG. 1 is an electron micrograph of red mud geopolymer aggregate provided in example 1 of the present invention.

FIG. 2 is an electron micrograph of red mud geopolymer aggregate provided in example 3 of the present invention.

FIG. 3 is an electron micrograph of red mud geopolymer aggregate provided in example 4 of the present invention.

Detailed Description

In order to make the objects, technical solutions and technical effects of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive step in connection with the embodiments of the present invention shall fall within the scope of protection of the present invention.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined otherwise.

The embodiment of the invention provides red mud geopolymer aggregate, which comprises the following raw materials in parts by weight:

the red mud geopolymer aggregate provided by the invention takes the red mud as a main raw material, and the red mud mainly contains SiO₂、Al₂O₃、CaO、Fe₂O₃Etc. in the presence of an activatorThe water is used for carrying out hydration reaction, so that the red mud and water interact to form A product with A C- (A) -S-H gel structure or an S-A-P-H, S-A-H gel structure, A 'network structure' is formed inside the red mud, the crosslinking performance of the red mud material is enhanced, and the compressive strength of the mechanical strength of the red mud material is improved; the red mud geopolymer aggregate provided by the invention can be selectively added with fly ash, the fly ash is mixed with the red mud, and the red mud geopolymer aggregate with different density grades is prepared according to requirements, so that the red mud geopolymer aggregate can achieve higher mechanical property and compressive strength, and is more widely applied.

Specifically, the red mud geopolymer aggregate takes red mud as a main raw material, and the red mud mainly contains SiO₂、Al₂O₃、CaO、Fe₂O₃And the like. The red mud raw material is modified, so that the component properties of the red mud are changed, and the mechanical strength and the pressure resistance of the red mud raw material are improved. In the specific embodiment of the invention, 1-10 parts of exciting agent, 0-40 parts of fly ash and 20-60 parts of water are added on the basis of 50-100 parts of red mud, so that the red mud geopolymer aggregate is prepared by using red mud as a main raw material, and the comprehensive utilization of the red mud is realized.

Preferably, the median diameter of the red mud is 1.3-1.6 μm; the median diameter of the red mud is controlled to be 1.3-1.6 mu m, so that the particle size of the red mud is moderate, and when the red mud is subjected to modification treatment, a structure with a gel network can be formed after interaction with water. If the particle size of the red mud is too large, the hydration reaction is unbalanced, so that the formed gel network is too sparse, and the mechanical strength and the pressure resistance of the red mud raw material cannot be improved; if the particle size of the red mud is too small, agglomeration is easy to occur in the reaction process, and the use of the red mud geopolymer aggregate is not facilitated. The median diameter of the red mud is further controlled, so that the uniform particle size of the red mud can be ensured, the subsequent test is facilitated, and the hydration reaction effect after the excitant is added is balanced.

Preferably, the water content of the red mud is 0.01-3%, the water content of the red mud is low, the mechanical strength of the red mud cannot be influenced by excessive water in the reaction process, and the prepared red mud geopolymer aggregate can achieve high mechanical property and compressive strength.

Specifically, the red mud geopolymer aggregate comprises an excitant, and the excitant is mainly used for exciting the hydration reaction of the red mud and water to form a structure with a gel network, so that the crosslinking performance in the red mud material is enhanced, and the compressive strength of the mechanical strength of the red mud material is improved.

Preferably, the activator is at least one selected from sulfuric acid, carbonic acid, phosphoric acid, sodium hydroxide, calcium hydroxide, sodium chloride, sodium carbonate, sodium silicate and sodium sulfate. In some embodiments, when the activator is selected from at least one of sulfuric acid, carbonic acid, and phosphoric acid, wherein sulfuric acid contains sulfate ions, carbonic acid contains carbonate ions, and phosphoric acid contains phosphate ions; under the action of an acid radical ion-containing excitant, the red mud material is combined with water to carry out hydration reaction to form A gel product with an S-A-P-H or S-A-H gel structure, A 'network structure' is formed in the red mud, the crosslinking performance of the red mud material is enhanced, and the compressive strength of the mechanical strength of the red mud material is improved. In some embodiments, when the activator is selected from at least one of sodium hydroxide and calcium hydroxide, wherein both the sodium hydroxide and the calcium hydroxide contain hydroxide ions; under the action of an excitant containing hydroxide ions, the red mud material is combined with water to generate hydration reaction to form a gel product with a C- (A) -S-H gel structure, a 'network structure' is formed in the red mud, the crosslinking performance of the red mud material is enhanced, and the compressive strength of the mechanical strength of the red mud material is improved.

Further preferably, the activator is selected from any one of a combination of sodium hydroxide and sodium silicate, a combination of calcium hydroxide and sodium sulfate, and a combination of phosphoric acid and aluminum dihydrogen phosphate. In some embodiments, a composition of sodium hydroxide and sodium silicate is used as an activator, wherein the sodium hydroxide is a strong alkaline substance, the sodium silicate is a soluble inorganic silicate and has high viscosity, a mixed system of the inorganic silicate and the strong alkaline substance is used as the activator, and a plurality of anions act together to improve the rate of hydration reaction, generate a product with a C- (A) -S-H gel structure, improve the crosslinking performance among red mud materials, and enable the modified red mud material to have stronger mechanical strength. In some embodiments, a composition of calcium hydroxide and sodium sulfate is used as an activator, strong base and salt with sulfate radical are used as activators, so that the hydration products are promoted to be generated more quickly, the cross-linking of the red mud grid structure is accelerated, and the mechanical strength of the red mud geopolymer aggregate is improved. In some embodiments, a combination of phosphoric acid and aluminum dihydrogen phosphate is used as an activator, wherein the phosphoric acid is a ternary medium-strong acid, is not easy to volatilize and decompose, and has certain oxidizability and acid universality; the aluminum dihydrogen phosphate is an inorganic metal salt with viscosity, can reduce the viscosity of the aluminum dihydrogen phosphate when being mixed with phosphoric acid, improves the speed of hydration reaction, and simultaneously can generate a product with a C- (A) -S-H gel structure, thereby improving the mechanical strength of the red mud geopolymer aggregate.

Specifically, on the basis of 50-100 parts of the addition amount of the red mud, 1-10 parts of an exciting agent is added, and the rapid and complete hydration reaction of the red mud can be ensured by adding the exciting agent, so that A product with A C- (A) -S-H gel structure or an S-A-P-H/S-A-H gel structure is formed, A 'network structure' is formed in the red mud, the crosslinking performance of the red mud material is enhanced, and the compressive strength of the mechanical strength of the red mud material is improved. If the addition amount of the exciting agent is small, the hydration reaction is incomplete, and the strength of the red mud geopolymer aggregate is low; if the addition amount is too much, excessive precipitation can occur, and the cost is too high, so that the large-scale production is not facilitated.

Preferably, the raw material of the red mud geopolymer aggregate further comprises 0.01-1 part of additive on the basis of 50-100 parts of addition amount of the red mud. The addition of the additive can improve the excitation capability of the exciting agent, further improve the hydration degree of the raw material red mud, improve the rate of hydration reaction and enable the hydration reaction to be more complete. Preferably, the additive is selected from organometallic compounds. Further preferably, the organometallic compound is at least one selected from sodium methoxide, sodium ethoxide, and sodium propoxide. The addition of the organic metal compound can improve the excitation effect of the exciting agent, promote the hydration reaction of the red mud and improve the strength of the red mud geopolymer aggregate.

Specifically, on the basis that the addition amount of the red mud is 50-100 parts, the red mud geopolymer aggregate comprises 0-40 parts of fly ash; the red mud geopolymer aggregate provided by the invention can be selectively added with fly ash, the fly ash is mixed with the red mud, and the red mud geopolymer aggregate with different density grades is prepared according to requirements, so that the red mud geopolymer aggregate can achieve higher mechanical property and compressive strength, and is more widely applied.

Preferably, the red mud geopolymer aggregate is spherical particles, and the particle size of the spherical particles is 500-10 mm. The particle size of the red mud geopolymer aggregate is 500 mu m-10 mm, and the particle size is small and uniform, thereby being beneficial to subsequent use.

The red mud geopolymer aggregate is prepared by the following preparation method.

Correspondingly, the embodiment of the invention also provides a preparation method of the red mud geopolymer aggregate. The method comprises the following steps:

s01, weighing the components according to the formula of the raw material of the red mud geopolymer aggregate;

s02, pretreating the red mud, and mixing the pretreated red mud with fly ash and water to obtain a first mixture;

and S03, mixing and granulating the first mixture and an exciting agent to obtain the red mud geopolymer aggregate.

According to the preparation method of the red mud geopolymer aggregate, the red mud is pretreated, and other components are mixed, so that the components can be uniformly dispersed, and the red mud geopolymer aggregate has high compressive strength and excellent stability. In addition, the preparation method has simple process, controllable conditions and low equipment requirement, and can be used for industrial production.

Specifically, in the step S01, the components are weighed according to the formula of the raw material of the red mud geopolymer aggregate, the properties and the content of the raw material of the red mud geopolymer aggregate are as described above, and details are not repeated herein for the sake of brevity.

Specifically, in step S02, the red mud is pretreated and then mixed with fly ash and water to obtain a first mixture. Preferably, in the step of pretreating the red mud, the pretreatment method comprises drying the red mud at 60-80 ℃, and then performing ball milling treatment. The drying temperature is controlled to be 60-80 ℃, the obtained red mud is ensured to be beneficial to carrying out subsequent tests, if the temperature is too high, the red mud is crystallized, the reaction with an exciting agent in the later period is not facilitated, and meanwhile, too much energy consumption and more cost are caused. Further preferably, the water content of the dried red mud is 0.01-3%, and the control of the water content of the red mud is favorable for better forming red mud geopolymer aggregate with higher mechanical property and compressive strength.

Further, performing ball milling treatment, wherein in a preferred embodiment of the invention, the ball milling treatment is performed by using a ball mill, so that the median diameter of the red mud is 1.3-1.6 μm; the median diameter of the red mud is controlled to be 1.3-1.6 mu m, so that the particle size of the red mud is moderate, and when the red mud is subjected to modification treatment, the red mud can be ensured to interact with water to be beneficial to forming a structure with a gel network; if the particle size of the red mud is too large, the hydration reaction is unbalanced, so that the formed gel network is too sparse, and the mechanical strength and the pressure resistance of the red mud raw material cannot be improved; if the particle size of the red mud is too small, agglomeration is easy to occur in the reaction process, and the use of the red mud geopolymer aggregate is not facilitated. The median diameter of the red mud is further controlled, the uniform particle size of the red mud can be ensured, the subsequent test is facilitated, and the effect of hydration treatment after the excitant is added is balanced.

Preferably, in the step of mixing the pretreated red mud with the fly ash and water, mixing the pretreated red mud with the fly ash and the water in a stirring manner at a rotating speed of 30-35 rpm for 1-10 minutes; in the step, the first mixture is prepared through mixing treatment at low speed and in short time to form a part of sphere, so that the subsequent addition of the exciting agent can be uniformly reacted.

In the step S03, in the step of mixing and granulating the first mixture and the exciting agent to obtain the red mud aggregate, mixing and granulating are performed in a stirring manner at a rotation speed of 60-65 rpm for 10-15 minutes, after the exciting agent is added, the mixture reacts with the first mixture, and the hydration reaction between the red mud raw materials is accelerated by adopting a higher rotation speed and a longer treatment time to form a gel network structure, so as to form the red mud geopolymer aggregate.

In some embodiments, the activator is added as a solid activator, and after the first mixture and the activator are mixed, water is sprayed for granulation to obtain the red mud aggregate, wherein the adding mass of the sprayed water is 5-10% of the mass of the first mixture; the solid activator is adopted for testing, and the testing process is simple and convenient. In some embodiments, the activator is added as a liquid activator, the mixture is mixed with 90% -95% of the liquid activator, then the mixture is placed in a granulator, and 5% -10% of the liquid activator is sprayed for granulation to obtain the red mud aggregate; the liquid excitant is adopted for testing, the liquid excitant is more uniformly distributed, and the prepared red mud geopolymer aggregate has better strength.

Preferably, the preparation method further comprises the step of curing the red mud geopolymer aggregate. Further preferably, in the step of curing the red mud geopolymer aggregate, the red mud geopolymer aggregate is cured at a temperature of 20-25 ℃ and a humidity of 85-95%, so that the prepared red mud geopolymer aggregate can achieve high mechanical properties and compressive strength, and is more widely applied.

The following further describes specific examples.