阅读说明：本技术 拜耳法赤泥生产胶凝材料的方法以及混凝土掺合料 (Method for producing cementing material from Bayer process red mud and concrete admixture ) 是由 蒋旭峰 于 2020-05-08 设计创作，主要内容包括：一种拜耳法赤泥生产胶凝材料的方法以及一种混凝土掺合料,上述方法包括如下步骤：S1还原处理：向拜耳法赤泥中添加铁还原细菌,将拜耳法赤泥中的Fe～(3+)还原至磁铁矿,制得赤泥基体；S2失水处理：赤泥基体失水至含水率为10～15％；S3混合处理：失水后的赤泥基体与钢渣颗粒混合,形成混合物；S4后序处理：混合物破碎、磁选、粉磨形成胶凝材料。混凝土掺合料包括上述方法制备的胶凝材料。本发明中拜耳法赤泥生产胶凝材料的方法实现了对于废渣拜耳法赤泥以及钢渣的再利用,减少了拜耳法赤泥以及钢渣造成的资源浪费和环境污染。制备形成的胶凝材料作为混凝土掺合料,应用在混凝土的制备中能显著提高了混凝土的强度。(A method for producing a cementing material by Bayer process red mud and a concrete admixture, the method comprises the following steps: s1 reduction treatment: adding iron reducing bacteria into the Bayer process red mud to reduce Fe in the Bayer process red mud 3+ Reducing to magnetite to prepare a red mud matrix; s2 dehydration treatment: dehydrating the red mud matrix until the water content is 10-15%; s3 mixing treatment: mixing the dehydrated red mud matrix with steel slag particles to form a mixture; s4 subsequent processing: the mixture is crushed, magnetically separated and ground to form the gel material. The concrete admixture comprises the gelled material prepared by the method. The method for producing the cementing material by using the Bayer process red mud realizes the reutilization of the waste residue Bayer process red mud and the steel slag, and reduces the resource waste and the environmental pollution caused by the Bayer process red mud and the steel slag. The prepared gelled material is used as a concrete admixture and applied to the preparation of concrete, and the strength of the concrete can be obviously improved。)

1. The method for producing the cementing material by using the Bayer process red mud is characterized by comprising the following steps of:

s1 reduction treatment: adding iron reducing bacteria into the Bayer process red mud to reduce Fe in the Bayer process red mud³⁺Reducing to magnetite to prepare a red mud matrix;

s2 dehydration treatment: dehydrating the red mud matrix until the water content in the red mud matrix is 10-15%;

s3 mixing treatment: mixing the dehydrated red mud matrix with steel slag particles to form a mixture;

s4 subsequent processing: the mixture is crushed, magnetically separated and ground to form the gel material.

2. The method for producing a cementitious material from Bayer process red mud according to claim 1, wherein the iron-reducing bacteria in the S1 reduction process are Shewanella pictopholars WP3 of Shewanella pictopholars, and the Shewanella pictopholars WP3 strain reduces Fe in Bayer process red mud in a high pressure vessel³⁺。

3. The method for producing a cementing material from Bayer process red mud according to claim 2, wherein the iron reducing bacteria added in the S1 reduction treatment is a culture solution of Shewanella pictotolerans WP3 strain, and the concentration of the Shewanella pictotolerans WP3 strain in the culture solution is 10⁷CFU/ml to 10⁶CFU/ml, the mass of the culture solution added in the S1 reduction treatment is 3% -8% of the mass of the Bayer process red mud.

4. The method for producing a cementing material from Bayer process red mud according to claim 3, wherein the Shewanellap in the culture solution added in the S1 reduction treatmentThe concentration of the strain of iezotolerans WP3 was 10⁶CFU/ml, wherein the mass of the culture solution is 5% of that of the Bayer process red mud.

5. The method for producing the cementing material from the Bayer process red mud according to claim 2, wherein in the S1 reduction treatment, the hydrostatic pressure in the high-pressure vessel is 1-5 MPa, the temperature in the high-pressure vessel is 10-15 ℃, and the reaction time of the Shewanella piozotolerans WP3 strain and the Bayer process red mud in the high-pressure vessel is 47-72 h.

6. The method for producing the cementing material from the Bayer process red mud according to claim 1, wherein the S2 dehydration treatment is to stack the red mud matrix naturally for 3-5 days until the water content in the red mud matrix is 10-15%.

7. The method for producing the cementing material from the Bayer process red mud as claimed in claim 1, wherein the mass ratio of the red mud matrix to the steel slag particles in the S3 mixing treatment is 2: 1.

8. The method for producing the cementing material from the Bayer process red mud according to claim 1 or 7, wherein the steel slag particles in the S3 mixing treatment are high-alkalinity steel slag particles, the alkalinity of the steel slag particles is not lower than 3mmol/L, the particle size is 3-5 mm, and the temperature of the steel slag particles in the S3 mixing treatment is 150-200 ℃; the grinding in the subsequent S4 treatment is vertical grinding, the temperature of hot air in the vertical grinding is 600-800 ℃, and the mixture is vertically ground until the specific surface area is 400-500 m²/kg。

9. A concrete admixture, characterized in that it comprises a cementitious material obtained by a process for producing a cementitious material from the Bayer process red mud of any of claims 1 to 8.

10. The concrete admixture of claim 9, comprising cement, wherein the cementitious material is substituted for 5% to 20% of the cement, i.e. the mass ratio of cement to cementitious material in the concrete admixture is 4:1 to 19: 1.

Technical Field

The invention relates to the technical field of red mud treatment, in particular to a method for producing a cementing material by Bayer process red mud and a concrete admixture.

Background

The red mud is polluting waste residue discharged when aluminum oxide is extracted in the aluminum industry, and generally 1.0-2.0 tons of red mud are additionally generated when 1 ton of aluminum oxide is produced on average. 6000 million tons of red mud are discharged every year around the world, and the comprehensive utilization rate is only about 15 percent. At present, the production method of alumina mainly comprises three methods, namely a sintering method, a Bayer method and a combination method, whereinOf the three red mud types, the red mud obtained by the sintering method and the red mud obtained by the combination method have higher content of calcium oxide and silicon dioxide, are suitable for manufacturing building materials, have relatively higher comprehensive utilization rate, and are rich in Fe (OH) in the red mud obtained by the Bayer method₃Gel and Al (OH)₃The gel ensures that the red mud has stronger water retention, is not easy to dry, has large dehydration energy consumption, and since 40 years, dozens of methods are provided for the comprehensive utilization of the Bayer process red mud in many countries, but the vast majority of the methods do not meet the requirements of industrial production, so the comprehensive utilization rate of the Bayer process red mud is the lowest among the three types of red mud, and the Bayer process red mud is hardly effectively utilized.

As a large country for alumina production in China, the red mud discharged each year is up to millions of tons. A large amount of red mud cannot be fully and effectively utilized and can only be stacked by a large-area yard, the stacking of the red mud not only occupies land resources, but also alkali, sodium, aluminum, fluoride, rare metals and the like in the red mud can enter underground water along with leachate to cause certain damage to human bodies. In addition, the high alkalinity of the red mud can pollute the water quality and cause certain harm to people, animals and plants. The production of the red mud has direct and indirect influences on the production and life of human beings in many aspects, so that the yield and the harm of the red mud are reduced to the maximum extent, and the realization of multi-channel and large-quantity recycling is urgent.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for producing a gelled material by effectively utilizing Bayer process red mud and a concrete admixture converted by utilizing the Bayer process red mud.

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

a method for producing a cementing material by Bayer process red mud comprises the following steps:

s1 reduction treatment: adding iron reducing bacteria into the Bayer process red mud to reduce Fe in the Bayer process red mud³⁺Reducing to magnetite to prepare a red mud matrix;

s2 dehydration treatment: dehydrating the red mud matrix until the water content in the red mud matrix is 10-15%;

s3 mixing treatment: mixing the dehydrated red mud matrix with steel slag particles to form a mixture;

s4 subsequent processing: the mixture is crushed, magnetically separated and ground to form the gel material.

Preferably, the iron-reducing bacteria in the S1 reduction treatment are Shewanella pictophotolerans WP3 of Shewanella, and the Shewanella pictophotolerans WP3 strain reduces Fe in Bayer process red mud in a high-pressure vessel³⁺。

Preferably, the iron-reducing bacteria added in the S1 reduction treatment is a culture solution of Shewanella pimelotolerans WP3 strain, and the concentration of the Shewanella pimelotolerans WP3 strain in the culture solution is 10⁷CFU/ml to 10⁶CFU/ml, the mass of the culture solution added in the S1 reduction treatment is 3% -8% of the mass of the Bayer process red mud.

Preferably, the concentration of the Shewanella pimozololerans WP3 strain in the culture solution added for the S1 reduction treatment is 10⁶CFU/ml, wherein the mass of the culture solution is 5% of that of the Bayer process red mud.

Preferably, in the S1 reduction treatment, the hydrostatic pressure in the high-pressure vessel is 1-5 MPa, and the temperature in the high-pressure vessel is 10-15 ℃.

Preferably, in the S1 reduction treatment, the reaction time of the Shewanella pimelotolerans WP3 strain and the Bayer process red mud in a high-pressure container is 47-72 h.

Preferably, the S2 dehydration treatment is to stack the red mud matrix naturally for 3-5 days until the water content in the red mud matrix is 10-15%.

Preferably, the mass ratio of the red mud matrix to the steel slag particles in the S3 mixing treatment is 2: 1.

Preferably, the steel slag particles in the S3 mixing treatment are high-alkalinity steel slag particles, the alkalinity of the steel slag particles is not lower than 3mmol/L, and the particle size is 3-5 mm.

Preferably, the temperature of the steel slag particles in the S3 mixing treatment is 150-200 ℃.

Preferably, the grinding in the subsequent treatment of S4 is vertical grinding, the temperature of hot air in the vertical grinding is 600-800 ℃, and the mixture is vertically ground until the specific surface area is 400～500m²/kg。

A concrete admixture comprising the cementitious material produced by any one of the above methods.

Preferably, the concrete admixture comprises cement and the cementitious material is used to replace 5% to 20% of the cement, i.e. the mass ratio of cement to cementitious material in the concrete admixture is 4:1 to 19: 1.

The method for producing the cementing material by the Bayer process red mud carries out biochemical treatment on the Bayer process red mud by iron reducing bacteria so as to lead Fe³⁺Conversion to magnetite particles, decomposition of Fe (OH) in red mud₃Gelling, further removing water in the red mud through water loss treatment and mixing treatment, and finally preparing the cementing material through subsequent crushing, magnetic separation and grinding. The reduction method of biochemical treatment in the method has no pollution, the subsequent dehydration treatment does not consume energy, and the industrial solid waste steel slag is effectively utilized.

The invention also provides a concrete admixture which comprises the gelled material prepared by the method, and the concrete admixture is applied to the preparation process of concrete, so that the strength of the concrete is obviously improved, and the concrete admixture has a very good application effect. The method has the advantages of low energy consumption and strong popularization, realizes the reutilization of the industrial polluting waste residue Bayer process red mud and the industrial solid waste steel slag, and reduces the resource waste, the environmental stress and the influence on human life caused by the Bayer process red mud and the steel slag.

Detailed Description

The following will further describe specific embodiments of the bayer process red mud for producing cementitious materials and a concrete admixture in combination with the given examples one to three. The method for producing a cementitious material from bayer process red mud and a concrete admixture of the present invention are not limited to the description of the following examples.

The first embodiment is as follows:

the embodiment provides a method for producing a cementing material from Bayer process red mud, which sequentially comprises S1 reduction treatment, S2 dehydration treatment, S3 mixing treatment and S4 subsequent treatment. The specific operation of the S1 reduction treatment is as follows: adding iron reducing bacteria into the Bayer process red mud to reduce Fe in the Bayer process red mud³⁺Reducing toMagnetite to prepare a red mud matrix; the specific operation of the water loss treatment of S2 is as follows: dehydrating the red mud matrix until the water content in the red mud matrix is 10-15%; the specific operation of the S3 mixing process is: mixing the dehydrated red mud matrix with steel slag particles to form a mixture; the specific operation of the subsequent processing of S4 is as follows: and sequentially crushing, magnetically separating and grinding the mixture to finally form the gelled material.

Bayer process red mud is rich in Fe (OH)₃Colloid, Fe (OH)₃The colloid contains a large amount of Fe³⁺Through detection, the bayer process red mud selected in the embodiment specifically contains Al₂O₃14.3% of Fe₂O₃(Fe³⁺In a total content of Fe₂O₃Formal characterization of) was 57.0%, SiO₂5.95% of Na₂O is 3.4%, of course, the method for producing the cementing material from the bayer process red mud in this embodiment is not limited to the red mud with this composition, and the method in this embodiment can be applied to bayer process red mud with different compositions. Fe in Bayer process red mud is reduced by S1 reduction treatment step under the action of iron reducing bacteria³⁺Reducing the iron-reducing bacteria into magnetite particles with stronger magnetism, wherein the iron-reducing bacteria in the embodiment are Shewanella pictophotolerans WP3 and Shewanella pictophotolerans WP3 strains with reducibility under high-pressure environment, and Fe can be obtained³⁺Reducing to magnetite particles. Of course, other iron-reducing bacteria may be used.

Concretely, 100 kg of Bayer process red mud is placed in a high-pressure container, a culture solution of Shewanella piezotolorans WP3 strain is added into the high-pressure container, and the concentration of the Shewanella piezotolorans WP3 strain in the culture solution is 10⁶CFU/ml, the mass of the added culture solution is 3% of the mass of the red mud, namely the mass of the added culture solution is 3 kg. Controlling the hydrostatic pressure of the high-pressure container to be 1-5 MPa, keeping the temperature in the high-pressure container to be 10-15 ℃, and reacting for 60 hours to obtain Fe in the Bayer process red mud³⁺The magnetite particles are completely reduced in a high-pressure environment, and become large in nucleation in the high-pressure environment and have a certain granularity. With Fe (OH) in red mud₃The gel content is continuously reduced, the water retention of the red mud is obviously reduced, and the viscosity is reducedAnd (3) naturally settling moisture in the red mud to obtain a red mud matrix in a high-pressure container.

The red mud matrix is separated from the high-pressure container to be in the normal-pressure environment, the Shewanella piezotolerans WP3 strain can lose the reduction activity in the normal-pressure environment, and the subsequent application of the red mud cannot be influenced. And naturally stacking the red mud matrix for 3 days until the water content of the red mud matrix is reduced to 10-15%, and finishing the water loss treatment of S2. Of course, in the present embodiment, the water loss treatment of S2 may also be performed by removing water from the red mud matrix with the aid of a centrifuge, but this method is energy-consuming.

The dehydrated red mud matrix and steel slag particles are mixed for S3 mixing treatment, the steel slag particles are high-alkalinity steel slag particles, the alkalinity is 3mmol/L, the particle size is 3-5 mm, the alkalinity of the steel slag particles in the embodiment is not lower than 3mmol/L, the higher the alkalinity of the steel slag is, the higher the activity of the steel slag is, the alkalinity of converter steel slag of large steel mills in the industry is generally more than 3mmol/L, and therefore the embodiment can be used for most steel slag in industrial production.

The red mud and the steel slag particles are mixed according to the mass ratio of 2:1, the steel slag particles are heated to the temperature of 150-200 ℃, the red mud and the steel slag particles are mixed, the water in the red mud is evaporated by the steel slag particles with higher temperature, the water in the red mud is greatly reduced by the porous steel slag particles by absorbing the water in the red mud, and the mixture of the steel slag particles and the red mud integrally presents the physical properties of powdery materials.

The method in the embodiment not only realizes the reutilization of the waste residue Bayer process red mud, but also solves the problem of the discharge of a part of industrial solid waste steel slag, and reduces the resource waste and the environmental pollution caused by the Bayer process red mud and the steel slag.

Crushing the mixture of the steel slag and the red mud, then carrying out magnetic separation to remove magnetite particles in the red mud and simple substance iron particles in the steel slag particles, and grinding the mixture of the red mud and the steel slag after the magnetic separation into powder in a vertical mill until the specific surface area is 400-500 m²and/Kg, namely the cementing material.

The cementing material mainly comprises silicon oxide and aluminum oxide, is similar to the fly ash, has higher soluble alkali content, and has a certain excitation effect on the pozzolan reaction of the steel slag. The cementing material can be used as a concrete admixture, and the activity of the cementing material is between that of fly ash and mineral powder. Because the cement admixture has similar components to the concrete admixture, the formed cementing material prepared by the embodiment can also be applied as a cement admixture.

Example two

S1 reduction treatment: 100 kg of Bayer process red mud is placed in a high-pressure container, a culture solution of Shewanella piezotolorans WP3 strain is added into the high-pressure container, and the concentration of the Shewanella piezotolorans WP3 strain in the culture solution is 10⁷CFU/ml, the mass of the added culture solution is 5 percent of the mass of the red mud, namely the mass of the added culture solution is 5 kilograms. Controlling the hydrostatic pressure of the high-pressure container to be 1-5 MPa, controlling the temperature in the high-pressure container to be 10-15 ℃, and reacting for 48 hours to obtain Fe in the Bayer process red mud³⁺And (4) completely reducing to form a red mud matrix.

S2 dehydration treatment: the red mud matrix is separated from the high-pressure container and is in the normal-pressure environment, and the Shewanella pimelotolerans WP3 strain loses the reduction activity in the normal-pressure environment. And (3) naturally stacking the red mud matrix for 4 days at normal temperature and normal pressure until the water content of the red mud matrix is reduced to 10-15%.

S3 mixing treatment: the dehydrated red mud matrix is mixed with steel slag particles, the steel slag particles are high-alkalinity steel slag particles, the alkalinity of the steel slag particles is 4mmol/L, the particle size is 3-5 mm, the red mud and the steel slag particles are mixed according to the mass ratio of 2:1, the temperature of the steel slag particles is 150-200 ℃, after mixing, the moisture in the red mud is greatly reduced, and the mixture of the steel slag particles and the red mud integrally presents the physical properties of powdery materials.

S4 subsequent processing: crushing the mixture of the steel slag and the red mud, then carrying out magnetic separation to remove magnetite particles in the red mud and simple substance iron particles in the steel slag particles, and grinding the mixture of the red mud and the steel slag after the magnetic separation into powder in a vertical mill until the specific surface area is 400-500 m²and/Kg, namely the cementing material.

The cementing material can be used as a cement mixing material or a concrete admixture, and the activity of the cementing material is between that of fly ash and mineral powder.

EXAMPLE III

S1 reduction treatment: 100 kg of Bayer process red mud is placed in a high-pressure container, a culture solution of Shewanella piezotolorans WP3 strain is added into the high-pressure container, and the concentration of the Shewanella piezotolorans WP3 strain in the culture solution is 10⁶CFU/ml, the mass of the added culture solution is 8% of the mass of the red mud, namely the mass of the added culture solution is 8 kg. Controlling the hydrostatic pressure of the high-pressure container to be 1-5 MPa, controlling the temperature in the high-pressure container to be 10-15 ℃, and reacting for 47 hours to obtain Fe in the Bayer process red mud³⁺And (4) completely reducing to form a red mud matrix.

S2 dehydration treatment: the red mud matrix is taken out from the high-pressure container and is in an environment of normal pressure, and the Shewanella piezotolerans WP3 strain loses the reduction activity in the environment of normal pressure. And naturally stacking the red mud matrix for 5 days until the water content of the red mud matrix is reduced to 10-15%.

S3 mixing treatment: the dehydrated red mud matrix is mixed with steel slag particles, the steel slag particles are high-alkalinity steel slag particles, the alkalinity of the steel slag particles is 3mmol/L, the particle size is 3-5 mm, the red mud and the steel slag particles are mixed according to the mass ratio of 2:1, the temperature of the steel slag particles is 150-200 ℃, after mixing, the moisture in the red mud is greatly reduced, and the mixture of the steel slag particles and the red mud integrally presents the physical properties of powdery materials.

S4 subsequent processing: crushing the mixture of the steel slag and the red mud, then carrying out magnetic separation to remove magnetite ion particles in the red mud and simple substance iron particles in the steel slag particles, and grinding the mixture of the red mud and the steel slag after the magnetic separation into powder by a vertical mill until the specific surface area is 400-500 m²and/Kg, namely the cementing material.

The cementing material can be used as a cement mixing material or a concrete admixture, and the activity of the cementing material is between that of fly ash and mineral powder.

A cement was prepared according to examples one to three, wherein the masses of the culture liquids of Shewanella piozoledrans WP3 strain added in the step of reduction treatment of S1 in examples one to three were 3%, 5% and 3% of the mass of Bayer process red mud, respectively8 percent, the time required for the complete reaction in the reduction treatment is respectively 60h, 48h and 47h, the more the culture solution of the Shewanella piezotolorans WP3 strain is added by mass, the shorter the time required for the reaction in the reduction treatment is, but the reaction time of the culture solution of the Shewanella piezotolorans WP3 strain added with 8 percent of Bayer process red mud by mass is only shortened by 1 hour compared with the culture solution of the Shewanella piezotolorans WP3 strain added with 5 percent of Bayer process red mud by mass, so the culture solution of the Shewanella piezotolorans WP3 strain in the method of the embodiment (the strain concentration is 10)⁶CFU/ml) is preferably 5% of the mass of the bayer process red mud.

The cement substitution amount of the cementing materials prepared in the first to third examples is 10%, the cementing materials are used as concrete admixture to prepare concrete, and the prepared concrete is subjected to strength test, and the test results are shown in the following table 1:

sample (I)	Compressive strength of 7 days	28 day compressive strength
			Blank space	33.5	45.2
Example one	38.7	52.8
			Example two	38.5	52.4
EXAMPLE III	39.5	53.8

TABLE 1

The test results show that the 7-day strength of the concrete prepared by using the cementing material prepared in the embodiment as a concrete admixture is improved by 15-18% and the 28-day strength is improved by 15-20% compared with the concrete in a blank experiment, so that the cementing material prepared by using the method in the embodiment has a very good application effect in the building industry.

The method realizes the reutilization of the Bayer process red mud, namely the Fe in the Bayer process red mud³⁺The biochemical treatment method is adopted to realize reduction, no pollution is caused, the processes of dehydration treatment, mixing treatment and subsequent treatment are simple, and a large amount of energy is not consumed, so that the method for producing the cementing material by using the Bayer process red mud can be widely applied.

The invention also provides a concrete admixture which comprises the gelled material prepared by the method, and the concrete admixture is applied to the preparation process of concrete, so that the strength of the concrete is obviously improved, and the concrete admixture has a very good application effect. The method has the advantages of low energy consumption and strong popularization, realizes the reutilization of the industrial polluting waste residue Bayer process red mud and the industrial solid waste steel slag, and reduces the resource waste, the environmental stress and the influence on human life caused by the Bayer process red mud and the steel slag. Preferably, when the cementing material is used as a concrete admixture, the cement substitution amount is 5 to 20 percent, namely, the cost is reduced, and the strength of concrete can be improved, and more preferably 10 percent. Namely, in the concrete admixture, the mass ratio of cement to the Bayer process red mud production cementitious material is preferably 4:1 to 19:1, and more preferably 9: 1. Of course, other proportions of the concrete admixture for producing the cementing material by using the Bayer process red mud also belong to the protection scope of the invention.

The foregoing is a more detailed description of the invention in connection with specific preferred embodiments and it is not intended that the invention be limited to these specific details. For those skilled in the art to which the invention pertains, several simple deductions or substitutions can be made without departing from the spirit of the invention, and all shall be considered as belonging to the protection scope of the invention.