Red mud dry powder binder capable of changing shape of red mud and preparation method of red mud dry powder binder

Abstract

The invention provides a red mud dry powder binder for changing the shape of red mud and a preparation method thereof, and the red mud dry powder binder comprises the following components by weight: 80-96% of red mud powder, 3-10% of polyvinyl alcohol, 0.5-5% of sodium polyacrylate, 0.5-5% of modified starch, and a silane coupling agent. The red mud dry powder binder prepared by the invention not only can replace bentonite, but also is a new utilization method of red mud, and meanwhile, in the preparation process, the equipment is simple, the operation is simple and convenient, the economic value is high, and large-scale production is easy to realize, so that the red mud dry powder binder is suitable for industrial production. The red mud dry powder binder has a great application prospect in the fields of comprehensive treatment of red mud and development of novel red mud dry powder binders.

Description

Technical Field

[0001] The invention belongs to the field of comprehensive utilization of red mud, and particularly relates to a red mud dry powder binder for changing the shape of red mud and a preparation method thereof. Background Art

[0002] With the rapid development of the steel industry, pellets, a key raw material for blast furnace ironmaking, have a crucial impact on the efficiency, cost, and product quality of the entire ironmaking process. Adding a binder to pellet production is crucial for improving the material's ball-forming properties and enhancing the molecular bonding between particles within the pellets. Currently, bentonite is the most commonly used binder, but its use can reduce the iron grade of the pellets and increase the silicon content, leading to increased slag production during blast furnace ironmaking, a decrease in blast furnace coefficient, and increased fuel consumption.

[0003] Red mud is an industrial solid waste generated during the extraction of alumina in the aluminum industry. Approximately 1.0 to 1.8 tons of red mud are emitted for every ton of alumina produced. Maximizing the resource utilization of red mud is imperative. However, traditional red mud treatment methods often rely on simple crushing and screening, making efficient use of red mud difficult.

[0004] CN118531209A discloses a pelletizing process using iron ore powder and rotary furnace raw materials, and a method for preparing the pellets. The pelletizing process comprises the following components by weight: 70-95% iron-containing composition, 0-5% magnesium powder, 2.2-9.5% binder, and the remainder bentonite. The iron-containing composition primarily comprises red mud. This prior art uses a small amount of bentonite, which still results in a lower iron grade in the pellets and an increased silicon content.

[0005] Therefore, there is an urgent need to develop a red mud dry powder binder that changes the shape of red mud, which can not only transform red mud waste into cohesive pellet particles, but also realize large-scale resource utilization of red mud. At the same time, it has the characteristics of reducing the SiO2 content and increasing the Fe2O3 content in the sintered material, thereby improving the sintering quality and solving the problems existing in the existing technology. Summary of the Invention

[0006] The existing technology suffers from high red mud waste discharge and low treatment efficiency, high cost of red mud dry powder binders, low iron grade, and high silicon content. To address these issues, the present invention provides a red mud dry powder binder that modifies the shape of red mud and a method for preparing the same.

[0007] In a first aspect of the present application, a red mud dry powder binder for changing the shape of red mud is provided, which comprises the following components, in weight percentage: 80-96% red mud powder, 3-10% polyvinyl alcohol, 0.5-5% sodium polyacrylate, and 0.5-5% modified starch.

[0008] Furthermore, the red mud dry powder binder includes the following components in weight percentage: 90-96% red mud powder, 3-5% polyvinyl alcohol, 0.5-1% sodium polyacrylate, and 0.5-1% modified starch.

[0009] In a specific embodiment of the present application, the modified starch is a water-soluble modified starch; further, the modified starch is at least one of water-soluble sweet potato starch, oxidized starch, dextrin, cross-linked starch, and esterified starch.

[0010] In a specific embodiment of the present application, the red mud dry powder binder also contains a silane coupling agent.

[0011] In a specific embodiment of the present application, the mass of the silane coupling agent is 0.5-2% of the mass of the red mud powder; further, the mass of the silane coupling agent is 0.5-1% of the mass of the red mud powder.

[0012] In a specific embodiment of the present application, the silane coupling agent is at least one of KH-550 (γ-aminopropyltriethoxysilane) and KH-560 (γ-glycidyloxypropyltrimethoxysilane).

[0013] In this application, polyvinyl alcohol mainly acts as a binder to make the powder cohesive; sodium polyacrylate is a polymer dispersant / thickener that can improve fluidity, prevent agglomeration, and assist in granulation; water-soluble modified starch can be used as a binder and film-forming agent to enhance cohesiveness and particle strength.

[0014] The raw materials of the red mud dry powder binder provided in this application are easily available and reasonably priced, and compared with bentonite binders, the cost can be effectively reduced. Therefore, the present invention has great application prospects in the fields of comprehensive treatment of red mud and development of new red mud dry powder binders.

[0015] In a second aspect of the present application, a method for preparing the above-mentioned red mud dry powder binder is provided, comprising the following steps: S1. The red mud is filtered, dried and crushed into powder to obtain red mud powder; S2. The red mud powder was added to a stirred mill, and the silane coupling agent was sprayed onto the surface of the red mud powder at a certain speed, and the grinding and stirring were continued to obtain a surface-modified red mud powder; S3. Add polyvinyl alcohol, sodium polyacrylate and modified starch to the surface-modified red mud powder, and continue grinding and stirring to obtain the red mud dry powder binder.

[0016] In a specific embodiment of the present application, step S1 specifically comprises: filtering the red mud into a filter cake, drying it to a moisture content of ≤6%, and then grinding it to 200-300 mesh to obtain red mud powder.

[0017] In a specific embodiment of the present application, step S2 further includes at least one of the following technical features: (1) diluting the silane coupling agent with anhydrous ethanol and uniformly spraying the silane coupling agent onto the surface of the red mud powder by high-pressure atomization; further, the volume ratio of the silane coupling agent to the anhydrous ethanol is 1:(5-10); (2) spraying the silane coupling agent when the rotation speed of the stirring grinder is 500-800 rpm; (3) The time for spraying the silane coupling agent is 5-15 minutes; (4) The amount of the silane coupling agent added is 0.5-2% of the mass of the red mud powder, preferably 0.5-1%; (5) The silane coupling agent is at least one of KH-550 (γ-aminopropyltriethoxysilane) and KH-560 (γ-glycidyloxypropyltrimethoxysilane).

[0018] In step S2 of the present application, by introducing a silane coupling agent on the surface of red mud, the high shear force during the grinding and stirring process is utilized to make silane instantly embedded in the surface of red mud, and the Fe-OH groups on the surface of red mud rapidly condense with siloxane to form Fe-O-Si covalent bonds. At the same time, the system is designed to avoid introducing moisture as much as possible. Water promotes the hydrolysis of silane into silanols and self-polymerization to form polysiloxanes, which are deposited on the surface of red mud particles to form an irregular coating, resulting in a rough surface and decreased strength of spherical particles. Therefore, ethanol needs to be selected from anhydrous ethanol, and the stirring grinder needs to be kept closed after spraying to prevent ethanol from volatilizing too quickly. After atomization, the silane coupling agent has good dispersibility, increases the contact area with the red mud powder, and improves the reaction efficiency.

[0019] In step S2 of the present application, the interfacial condensation reaction between silane and red mud requires activation energy. The mechanical friction heat during the grinding process can increase the system temperature, promote the formation of Fe-O-Si bonds, and avoid silane hydrolysis. Therefore, the silane coupling agent needs to be sprayed onto the surface of the red mud powder at a certain rotation speed.

[0020] In a specific embodiment of the present application, in step S3, the modified starch is a water-soluble modified starch, selected from at least one of water-soluble sweet potato starch, oxidized starch, dextrin, cross-linked starch, and esterified starch.

[0021] In a specific embodiment of the present application, in step S3, the proportions of each material, in weight percentage, are: red mud powder 80-96%, polyvinyl alcohol 3-10%, sodium polyacrylate 0.5-5%, and modified starch 0.5-5%; preferably, the proportions of each material are: red mud powder 90-96%, polyvinyl alcohol 3-5%, sodium polyacrylate 0.5-1%, and modified starch 0.5-1%.

[0022] In step S3 of the present application, in a stirred mill, red mud powder is mixed with various additives under strong stirring and grinding action, and is subjected to the rolling, extrusion and collision action of the stirring and grinding media. Under the action of polyvinyl alcohol, sodium polyacrylate and modified starch, the red mud powder will gradually agglomerate and round up, and finally form spherical particles.

[0023] Compared with the prior art, the present invention has the following advantages: (1) This application transforms red mud waste into spherical granular dry powder with adhesive properties through a specific treatment process. This new type of binder can be used for sintering iron ore powder to improve the sintering quality and realize the large-scale resource utilization of red mud.

[0024] (2) In this application, polyvinyl alcohol mainly acts as a binder to make the powder cohesive; sodium polyacrylate is a polymer dispersant / thickener that can improve fluidity, prevent agglomeration, and assist in granulation; water-soluble modified starch can be used as a binder and film-forming agent to enhance cohesiveness and granule strength.

[0025] (3) In the present application, by introducing a silane coupling agent on the surface of red mud and utilizing the high shear force during the grinding and stirring process, the silane is instantly embedded in the surface of the red mud. The Fe-OH groups on the surface of the red mud quickly condense with siloxane to form Fe-O-Si covalent bonds. The formation of this covalent bond can inhibit the hydrolysis of siloxane under alkaline conditions. On the other hand, after the silane coupling agent modifies the surface of the red mud, an "amphiphilic organic layer" of "weak hydrophilic + organic chain" is constructed on the surface of the red mud. It can not only combine with the hydrophilic groups of additives such as PVA (hydrogen bonds, van der Waals forces, etc.), but also rely on the steric hindrance of the organic chain to prevent excessive agglomeration, thereby providing an interface basis for the formation of spherical particles.

[0026] (4) The raw materials in this application are easily available and reasonably priced, which can effectively reduce costs compared to bentonite binders.

[0027] (5) The red mud dry powder binder prepared in the present application can not only replace bentonite, but also is a new method for utilizing red mud. At the same time, the present invention has simple equipment, simple operation, high economic value, and is easy to achieve large-scale production during the preparation process. Therefore, the present invention has great application prospects in the fields of comprehensive treatment of red mud and development of new red mud dry powder binders. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of the process flow of a red mud dry powder binder provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0031] In the description of the present invention, it should be noted that the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0032] In a specific embodiment of the present application, a method for preparing a red mud dry powder binder is provided, which specifically comprises the following steps: (1) Red mud pretreatment The red mud ore is filtered and dehydrated to obtain a filter cake, which is then dried and the agglomerated material is broken up and dried to a moisture content of ≤6%. The dried red mud is fed into a ball mill and ground to a particle size of 200-300 mesh to obtain red mud powder.

[0033] (2) Preparation of silane coupling agent solution The silane coupling agent is mixed with anhydrous ethanol and stirred at room temperature to form a uniform silane coupling agent solution.

[0034] (3) Red mud surface modification The red mud powder obtained above is added to a stirring grinder, the stirring device is started, and the prepared silane coupling agent solution is evenly sprayed on the surface of the red mud powder through a high-pressure atomizing nozzle; after the spraying is completed, the grinding and stirring are continued to ensure that the silane coupling agent and the red mud particles are fully in contact and reacted.

[0035] (4) Ball making Add polyvinyl alcohol, sodium polyacrylate, and modified starch to the stirring mill in sequence, maintain the speed of the stirring mill, and continue stirring and grinding to fully mix the components and form spherical particles.

[0036] (5) Finished product collection The mixed and ground materials are passed through a screening device to separate spherical particles with a particle size of 0.5-3mm. The coarse particles on the sieve are returned to the mixing grinder for further grinding, and the fine powder under the sieve is treated as defective product and processed separately.

[0037] The present invention is further described in detail below through specific examples.

[0038] In the following examples, red mud was collected from a Bayer process red mud dump at an aluminum plant. The chemical composition (mass percentage) was: Fe2O3 43%, Al2O3 18%, SiO2 12%, CaO 8%, Na2O 4%, and the remainder were trace elements and loss on ignition.

[0039] Example 1 (1) Red mud pretreatment The red mud ore is filtered and dehydrated through a plate and frame filter press to control the moisture content of the filter cake to 35-40%. The filter cake is then conveyed to a drum dryer and dried at 120°C. The agglomerated material is broken up by a drop-type crushing process and then dried to a moisture content of ≤6%. The dried red mud is fed into a ball mill and ground to a particle size of 200-300 mesh to obtain red mud powder.

[0040] (2) Preparation of silane coupling agent solution In a sealed container with a stirring device, add KH-550 silane coupling agent and anhydrous ethanol in a volume ratio of 1:10 and stir at room temperature for 10 minutes to form a uniform silane coupling agent solution.

[0041] (3) Red mud surface modification The red mud powder obtained in step (1) was placed in a horizontal agitator grinder, and the stirring device was started, with the speed set to 500 rpm. The silane coupling agent solution prepared in step (2) was evenly sprayed on the surface of the red mud powder through a high-pressure atomizing nozzle, wherein the mass of KH-550 was 1wt% of the red mud powder, and the spraying process lasted for 10 minutes. After the spraying was completed, the agitator grinder speed was increased to 800 rpm, and grinding was continued for 15 minutes to allow the silane coupling agent to fully contact and react with the red mud particles.

[0042] (4) Ball making In terms of weight percentage, polyvinyl alcohol, sodium polyacrylate and water-soluble sweet potato starch were added to the stirring mill in the proportion of 96% red mud powder, 3% polyvinyl alcohol, 0.5% sodium polyacrylate and 0.5% water-soluble sweet potato starch. The stirring mill speed was maintained at 800 rpm and the stirring and grinding was continued for 20 minutes to fully mix the components and form spherical particles.

[0043] (5) Finished product collection The material obtained in step (4) is passed through a screening device to separate spherical particles with a particle size between 0.5 and 3 mm, with a spherical yield of 95%. The coarse particles on the sieve are returned to the stirring grinder for further grinding, and the fine powder under the sieve is treated as defective product and processed separately.

[0044] Application effect experiment The red mud dry powder binder prepared in Example 1 was added to iron ore concentrate at a ratio of 3% to conduct a sintering experiment. Comparative experimental results showed that the SiO2 content of the sintered ore with the binder was 0.6% lower than that without the binder, while the Fe2O3 content was 1.2% higher.

[0045] Example 2 (1) Red mud pretreatment The red mud ore is filtered and dehydrated through a plate and frame filter press to control the moisture content of the filter cake to 35-40%. The filter cake is then conveyed to a drum dryer and dried at 120°C. The agglomerated material is broken up by a drop-type crushing process and then dried to a moisture content of ≤6%. The dried red mud is fed into a ball mill and ground to a particle size of 200-300 mesh to obtain red mud powder.

[0046] (2) Preparation of silane coupling agent solution In a sealed container with a stirring device, add KH-560 silane coupling agent and anhydrous ethanol in a volume ratio of 1:10 and stir at room temperature for 10 minutes to form a uniform silane coupling agent solution.

[0047] (3) Red mud surface modification The red mud powder obtained in step (1) was placed in a horizontal agitator grinder, and the stirring device was started with the speed set to 500 rpm. The silane coupling agent solution prepared in step (2) was evenly sprayed on the surface of the red mud powder through a high-pressure atomizing nozzle, wherein the mass of KH-560 was 0.5 wt% of the red mud powder, and the spraying process lasted for 5 minutes. After the spraying was completed, the speed of the agitator grinder was increased to 800 rpm, and the grinding was continued for 15 minutes to allow the silane coupling agent to fully contact and react with the red mud particles.

[0048] (4) Ball making In terms of weight percentage, polyvinyl alcohol, sodium polyacrylate and dextrin were added to the stirring mill in the ratio of 93% red mud powder, 5% polyvinyl alcohol, 1% sodium polyacrylate and 1% dextrin in sequence. The stirring mill speed was maintained at 800 rpm and stirring and grinding was continued for 20 minutes to fully mix the components and form spherical particles.

[0049] (5) Finished product collection The material obtained in step (4) was passed through a screening device to separate spherical particles with a particle size between 0.5 and 3 mm, with a spherical yield of 93%. The coarse particles on the sieve were returned to the stirring grinder for further grinding, and the fine powder under the sieve was treated as defective product and processed separately.

[0050] Example 3 (1) Red mud pretreatment The red mud ore is filtered and dehydrated through a plate and frame filter press to control the moisture content of the filter cake to 35-40%. The filter cake is then conveyed to a drum dryer and dried at 120°C. The agglomerated material is broken up by a drop-type crushing process and then dried to a moisture content of ≤6%. The dried red mud is fed into a ball mill and ground to a particle size of 200-300 mesh to obtain red mud powder.

[0051] (2) Preparation of silane coupling agent solution In a sealed container with a stirring device, add KH-550 silane coupling agent and anhydrous ethanol in a volume ratio of 1:10 and stir at room temperature for 10 minutes to form a uniform silane coupling agent solution.

[0052] (3) Red mud surface modification The red mud powder obtained in step (1) was placed in a horizontal agitator grinder, and the agitator was started, with the speed set to 800 rpm. The silane coupling agent solution prepared in step (2) was evenly sprayed onto the surface of the red mud powder using a high-pressure atomizing nozzle, wherein the mass of KH-550 was 1 wt% of the red mud powder, and the spraying process lasted for 15 minutes. After the spraying was completed, the grinding was continued at 800 rpm for 15 minutes to allow the silane coupling agent to fully contact and react with the red mud particles.

[0053] (4) Ball making In terms of weight percentage, polyvinyl alcohol, sodium polyacrylate and water-soluble sweet potato starch were added to the stirring mill in the proportion of 93.5% red mud powder, 5% polyvinyl alcohol, 1% sodium polyacrylate and 0.5% water-soluble sweet potato starch. The stirring mill speed was maintained at 800 rpm and the stirring and grinding was continued for 20 minutes to fully mix the components and form spherical particles.

[0054] (5) Finished product collection The material obtained in step (4) is passed through a screening device to separate spherical particles with a particle size between 0.5 and 3 mm, with a spherical yield of 96%. The coarse particles on the sieve are returned to the stirring grinder for further grinding, and the fine powder under the sieve is treated as defective product and processed separately.

[0055] Example 4 (1) Red mud pretreatment The red mud ore is filtered and dehydrated through a plate and frame filter press to control the moisture content of the filter cake to 35-40%. The filter cake is then conveyed to a drum dryer and dried at 120°C. The agglomerated material is broken up by a drop-type crushing process and then dried to a moisture content of ≤6%. The dried red mud is fed into a ball mill and ground to a particle size of 200-300 mesh to obtain red mud powder.

[0056] (2) Ball making In terms of weight percentage, polyvinyl alcohol, sodium polyacrylate and water-soluble sweet potato starch were added to the stirring mill in the proportion of 96% red mud powder, 3% polyvinyl alcohol, 0.5% sodium polyacrylate and 0.5% water-soluble sweet potato starch. The stirring mill speed was maintained at 800 rpm and the stirring and grinding was continued for 20 minutes to fully mix the components and form spherical particles.

[0057] (3) Finished product collection The material obtained in step (2) was passed through a screening device to separate spherical particles with a particle size between 0.5 and 3 mm, with a spherical yield of 84%. The coarse particles on the sieve were returned to the agitator grinder for further grinding, and the fine powder under the sieve was treated as defective product and processed separately.

[0058] Comparative Example 1 (1) Red mud pretreatment The red mud ore is filtered and dehydrated through a plate and frame filter press to control the moisture content of the filter cake to 35-40%. The filter cake is then conveyed to a drum dryer and dried at 120°C. The agglomerated material is broken up by a drop-type crushing process and then dried to a moisture content of ≤6%. The dried red mud is fed into a ball mill and ground to a particle size of 200-300 mesh to obtain red mud powder.

[0059] (2) Preparation of silane coupling agent solution In a sealed container with a stirring device, add KH-550 silane coupling agent and anhydrous ethanol in a volume ratio of 1:10 and stir at room temperature for 10 minutes to form a uniform silane coupling agent solution.

[0060] (3) Red mud surface modification The red mud powder obtained in step (1) was placed in a horizontal agitator grinder. Without starting the agitator, the silane coupling agent solution prepared in step (2) was evenly sprayed onto the surface of the red mud powder through a high-pressure atomizing nozzle. The mass of KH-550 was 1 wt% of the red mud powder, and the spraying process lasted for 10 minutes. After the spraying was completed, the agitator grinder was started and milled at 800 rpm for 15 minutes to allow the silane coupling agent to fully contact and react with the red mud particles.

[0061] (4) Ball making In terms of weight percentage, polyvinyl alcohol, sodium polyacrylate and water-soluble sweet potato starch were added to the stirring mill in the proportion of 96% red mud powder, 3% polyvinyl alcohol, 0.5% sodium polyacrylate and 0.5% water-soluble sweet potato starch. The stirring mill speed was maintained at 800 rpm and the stirring and grinding was continued for 20 minutes to fully mix the components and form spherical particles.

[0062] (5) Finished product collection The material obtained in step (4) was passed through a screening device to separate spherical particle products with a particle size between 0.5 and 3 mm, with a ball yield of 83%.

[0063] Comparative Example 2 With reference to Example 1, the only difference between this comparative example 3 and Example 1 is that polyvinyl alcohol is not added in step (4), and the other operations remain unchanged. The final ball yield is 36%.

[0064] Comparative Example 3 With reference to Example 1, the only difference between this comparative example 3 and Example 1 is that sodium polyacrylate is not added in step (4), and the other operations remain unchanged. The final ball yield is 57%.

[0065] Comparative Example 4 With reference to Example 1, the only difference between this comparative example 3 and Example 1 is that water-soluble sweet potato starch is not added in step (4), and the other operations remain unchanged. The final ball yield is 62%.

[0066] The above describes in detail the specific embodiments of the present invention. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0067] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0068] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A red mud dry powder binder for changing the shape of red mud, characterized in that: Calculated by weight percentage, the invention comprises the following components: 80-96% red mud powder, 3-10% polyvinyl alcohol, 0.5-5% sodium polyacrylate and 0.5-5% modified starch.

2. The red mud dry powder binder according to claim 1, characterized in that Calculated by weight percentage, the red mud dry powder binder includes the following components: 90-96% red mud powder, 3-5% polyvinyl alcohol, 0.5-1% sodium polyacrylate, and 0.5-1% modified starch.

3. The red mud dry powder binder according to claim 1, characterized in that The modified starch is at least one of water-soluble sweet potato starch, oxidized starch, dextrin, cross-linked starch, and esterified starch.

4. The red mud dry powder binder according to claim 1, characterized in that The red mud dry powder binder also contains a silane coupling agent.

5. The red mud dry powder binder according to claim 2, characterized in that: The mass of the silane coupling agent is 0.5-2% of the mass of the red mud powder.

6. The red mud dry powder binder according to claim 2, characterized in that: The silane coupling agent is at least one of KH-550 and KH-560.

7. The method for preparing the red mud dry powder binder according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. The red mud is filtered, dried and crushed into powder to obtain red mud powder; S2. The red mud powder was added to a stirred mill, and the silane coupling agent was sprayed onto the surface of the red mud powder at a certain speed, and the grinding and stirring were continued to obtain a surface-modified red mud powder; S3. Add polyvinyl alcohol, sodium polyacrylate and modified starch to the surface-modified red mud powder, and continue grinding and stirring to obtain the red mud dry powder binder.

8. The preparation method according to claim 7, characterized in that The step S1 specifically comprises: filtering the red mud into a filter cake, drying the filter cake to a moisture content of ≤6%, and then grinding the filter cake to 200-300 mesh to obtain red mud powder.

9. The preparation method according to claim 7, characterized in that In step S2, the silane coupling agent is diluted with anhydrous ethanol and then evenly sprayed onto the surface of the red mud powder by high-pressure atomization.

10. The preparation method according to claim 7, characterized in that In step S2, when the rotation speed of the stirring grinder is 500-800 rpm, the silane coupling agent is sprayed; Preferably, the time for spraying the silane coupling agent is 5 to 15 minutes.

Images