A method for red mud dealkalization activation based on solid waste-based acidic conditioning agent

Abstract

The application discloses a method for activating red mud by removing alkali based on a solid waste-based acidic conditioner, and belongs to the technical field of solid waste resource utilization of red mud. The method comprises the following steps: mixing red mud powder with a solid waste-based acidic conditioner to prepare slurry, and separating the slurry after stirring and reaction to obtain red mud after alkali removal and activation; the preparation method of the solid waste-based acidic conditioner is as follows: compounding coal gangue and phosphogypsum, and then calcining to obtain a porous solid waste-based material; mixing the porous solid waste-based material with a modifier to prepare slurry, and drying to obtain a modified solid waste-based material; the modifier comprises citric acid and ferrous sulfate; and mixing the modified solid waste-based material with an activation aid to form a shape, wherein the activation aid comprises sodium fluorosilicate and metakaolin, and the method is obtained. The method has the advantages of simple process and mild reaction conditions, can realize efficient alkali removal of red mud, improve the activity of silicon and aluminum, and provides an effective way for high-value resource utilization of red mud.

Description

Technical Field

[0001] This invention relates to the field of red mud solid waste resource utilization technology, and in particular to a red mud dealkalization and activation method based on solid waste-based acidic conditioner. Background Technology

[0002] Red mud is a major solid waste generated during the alumina industry. Due to its high content of free and bound alkalis, its pH value is typically above 11. Furthermore, the silica and aluminum components in red mud mostly exist as inert mineral phases such as nepheline and cereusite, exhibiting low reactivity. This high alkalinity and the inertness of the silica and aluminum components are the main factors restricting the large-scale resource utilization of red mud.

[0003] Existing methods for dealkalizing red mud mainly include strong acid neutralization, water washing, and biological dealkalization. While strong acid neutralization can rapidly reduce the alkalinity of red mud, it easily corrodes equipment, damages the particle structure of the red mud, and generates large amounts of high-salt wastewater. Water washing consumes a large amount of water, has low dealkalization efficiency, and high washing liquid treatment costs. Biological dealkalization suffers from long reaction cycles and unstable treatment effects. For the activation of silica-alumina components in red mud, existing technologies mostly employ physicochemical methods such as high-temperature calcination or strong alkali activation. However, high-temperature treatment consumes a lot of energy and easily leads to particle agglomeration, while strong alkali activation further exacerbates the alkalinity problem of red mud, contradicting the dealkalization requirements. Given the poor compatibility between existing dealkalization and activation methods, current processes typically adopt a step-by-step treatment mode of dealkalization followed by activation, resulting in complex process flows, long treatment cycles, and difficulty in achieving efficient synergistic treatment. Summary of the Invention

[0004] In view of this, the present invention provides a red mud dealkalization and activation method based on solid waste-based acidic conditioner, which solves the problems of red mud dealkalization and silicon-aluminum activation being difficult to carry out simultaneously in the prior art, high processing costs, and easy generation of secondary pollution.

[0005] In a first aspect, the present invention provides a method for preparing a solid waste-based acidic conditioner, comprising the following steps: Coal gangue and phosphogypsum were compounded and then calcined to obtain porous solid waste base material; The porous solid waste base material and the modifier are mixed and pulped, and then dried to obtain the modified solid waste base material; the modifier includes citric acid and ferrous sulfate; The modified solid waste base material is mixed with an activating agent, which includes sodium fluorosilicate and metakaolin, to obtain the solid waste-based acidic conditioner.

[0006] Preferably, the mass ratio of coal gangue to phosphogypsum is 1:(0.7~1.3); the calcination temperature is 650~750℃ and the time is 1.5~2.5h.

[0007] Preferably, the mass ratio of citric acid to ferrous sulfate in the modifier is (2.5~3.5):1; and the mass ratio of the porous solid waste base material to the modifier is 100:(6~12).

[0008] Preferably, the mass ratio of sodium fluorosilicate to metakaolin in the activator is (1.5~2.5):1; and the mass ratio of modified solid waste base material to activator is 100:(3~7).

[0009] Preferably, the process of mixing and molding the modified solid waste base material with the activator further includes the step of adding a molding agent; the amount of the molding agent added is 4 to 6% of the total mass of the modified solid waste base material, the activator, and the molding agent; the molding agent includes polyvinyl alcohol and starch.

[0010] Secondly, the present invention provides a solid waste-based acidic conditioner, characterized in that it is prepared by the above-described preparation method.

[0011] Thirdly, the present invention provides a method for red mud dealkalization and activation based on a solid waste-based acidic conditioner, comprising the following steps: Red mud powder was mixed with the above-mentioned solid waste-based acidic conditioner to make slurry, and after stirring and reaction, the red mud after dealkalization and activation was obtained. The mass ratio of the red mud powder to the solid waste-based acidic conditioner is 100:(15~25).

[0012] Preferably, the temperature of the stirring reaction is 40~60℃, and the stirring reaction time is 60~90min.

[0013] Preferably, the red mud powder has a particle size of 70-100 mesh and a moisture content of less than 25%; the solid waste-based acidic conditioner has a particle size of 2-4 mm.

[0014] Preferably, the separation is carried out by centrifugal filtration, and the de-alkali activated red mud and the adsorbed saturated solid waste acidic conditioner are obtained by centrifugal filtration; the adsorbed saturated solid waste acidic conditioner is regenerated by calcining at 500~600℃ for 1~2h.

[0015] Furthermore, the centrifugal filtration speed is 1800~2800 r / min; the centrifugal filtration time is 15~30 min.

[0016] Compared with the prior art, the present invention has achieved the following beneficial effects: This invention utilizes two types of industrial solid waste, coal gangue and phosphogypsum, as raw materials. A solid waste-based acidic conditioner is prepared through compound calcination, modification, and activation-aiding molding. This conditioner is then mixed with red mud powder to achieve simultaneous red mud dealkalization and silicon-aluminum activation. This method leverages the physicochemical properties of coal gangue and phosphogypsum to provide a composite conditioner for red mud treatment that combines mild acidity with silicon-aluminum activation functions, while simultaneously achieving resource utilization of industrial solid waste. The modifier, a mixture of citric acid and ferrous sulfate, and the activator, a mixture of sodium fluorosilicate and metakaolin, work synergistically to effectively disrupt the crystal structure of the inert silicon-aluminum mineral phases in the red mud under mild conditions. This avoids the high energy consumption, secondary pollution, and particle structure damage caused by strong acid corrosion and high-temperature calcination, allowing the activation of silicon-aluminum components to be completed simultaneously during the red mud dealkalization process. The method of this invention is simple in process and mild in reaction conditions, achieving efficient red mud dealkalization while enhancing silicon-aluminum activity, providing an effective pathway for the high-value resource utilization of red mud. Detailed Implementation

[0017] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0018] As the background art points out, existing methods for dealkalization and silicon-aluminum activation of red mud typically employ a step-by-step treatment mode of first dealkalizing and then activating, which results in complex processes, long processing cycles, and difficulty in achieving efficient synergistic treatment.

[0019] Based on this, the present invention provides a red mud dealkalization and activation method based on solid waste-based acidic conditioner, which can realize the simultaneous red mud dealkalization and silicon-aluminum activation, and the process is mild, energy-efficient, and free of secondary pollution, while realizing the resource utilization of industrial solid wastes such as coal gangue and phosphogypsum.

[0020] In a first aspect, the present invention provides a method for preparing a solid waste-based acidic conditioner, comprising the following steps: Coal gangue and phosphogypsum were compounded and then calcined to obtain porous solid waste base material; The porous solid waste base material and the modifier are mixed and pulped, and then dried to obtain the modified solid waste base material; the modifier includes citric acid and ferrous sulfate; The modified solid waste base material is mixed with an activating agent, which includes sodium fluorosilicate and metakaolin, to obtain the solid waste-based acidic conditioner.

[0021] In this invention, coal gangue is a solid waste generated during coal mining and washing. Its main components include SiO2 and Al2O3, typically containing 45-55% SiO2 and 20-30% Al2O3, while also containing a small amount of organic acid groups, providing acidic sites and supplementing silicon and aluminum. Phosphogypsum is a solid waste generated from the phosphate fertilizer industry, with its main component being CaSO4·2H2O, typically ≥85%. It is weakly acidic, providing a mild acidic environment, while also supplementing calcium ions to promote silicon and aluminum activation. Combining the two can achieve a synergistic effect.

[0022] When compounding, the mass ratio of coal gangue to phosphogypsum can be 1:(0.7~1.3), for example, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, or any range of the above ratios. In some preferred embodiments, the mass ratio of coal gangue to phosphogypsum is 1:1, at which the synergistic effect of the two is better.

[0023] This invention involves crushing the compounded solid waste base material to a particle size ≤20mm to facilitate subsequent calcination. The crushed material is then fed into a calcination furnace for calcination at a temperature of 650~750℃, for example, 650℃, 680℃, 700℃, 720℃, 750℃, or any range thereof; the calcination time is 1.5~2.5h, for example, 1.5h, 1.8h, 2h, 2.2h, 2.5h, or any range thereof. Under these calcination conditions, the coal gangue undergoes a dehydroxylation reaction, and the phosphogypsum completes the removal of its water of crystallization, both synergistically forming a well-developed porous structure; simultaneously, the anhydrous calcium sulfate crystal form of the phosphogypsum is reconstructed, providing stable weakly acidic sites. After calcination and cooling to room temperature, the material is then fed into a pulverizing and sieving device for pulverization until the particle size is ≤120 mesh. For example, it can be 100 mesh, 110 mesh, 120 mesh, or any range of the above values, to obtain a porous solid waste substrate. The porosity of this porous solid waste substrate can reach more than 50%. The porous structure is beneficial to increasing the contact area between the conditioner and the red mud, thereby enhancing the dealkalization and activation effects.

[0024] This invention modifies the aforementioned porous solid waste substrate with a modifier. The modifier comprises a compound system of citric acid and ferrous sulfate. Citric acid is a weak organic acid that enhances the mild acidity of the conditioner, preventing strong acids from corroding the red mud particles; ferrous sulfate provides Fe... 2+ ions, Fe 2+ It can catalyze the decomposition of inert silica-alumina mineral phases in red mud, improve activation efficiency, and at the same time, Fe 2+It can react with the free alkali in red mud to assist in dealkali removal. The mass ratio of citric acid to ferrous sulfate can be (2.5~3.5):1, for example, it can be 2.5:1, 2.8:1, 3:1, 3.2:1, 3.5:1 or any range of the above ratios.

[0025] During the modification process, the porous solid waste substrate and the modifier are mixed at a mass ratio of 100:(6~12), for example, 100:6, 100:7, 100:8, 100:9, 100:10, 100:11, 100:12, or any range of the above ratios. In some preferred embodiments, the mass ratio of the porous solid waste substrate to the modifier is 100:9. Water is added to adjust the slurry concentration to 35~45wt%, for example, 35wt%, 38wt%, 40wt%, 42wt%, 45wt%, or any range of the above values. The modification is carried out by stirring at 50~70℃ for 25~35min, for example, the modification temperature can be 50℃, 55℃, 60℃, 65℃, or 70℃, and the modification time can be 25min, 28min, 30min, 32min, or 35min, or any range of the above values. In some preferred embodiments, the modification temperature is 60°C and the modification time is 30 minutes. After modification, the material is sent to a vacuum drying oven and dried to constant weight at 80~90°C. For example, the drying temperature can be 80°C, 85°C, 90°C or any range of the above values ​​to obtain modified solid waste base material.

[0026] This invention involves compounding modified solid waste base material with an activator. The activator comprises a compound system of sodium fluorosilicate and metakaolin. Sodium fluorosilicate is a fluoride that can disrupt the crystal lattice structure of the silica-alumina mineral phase in red mud, promoting the dissociation of inert silica-alumina components. Metakaolin is an active silica-alumina material obtained by calcining kaolin, which can supplement the active silica-alumina components and synergistically improve the silica-alumina activation efficiency with sodium fluorosilicate. The mass ratio of sodium fluorosilicate to metakaolin can be (1.5~2.5):1, for example, 1.5:1, 1.8:1, 2:1, 2.2:1, 2.5:1, or any range of the above ratios.

[0027] During composite molding, the modified solid waste base material and the activator are mixed at a mass ratio of 100:(3~7), for example, 100:3, 100:4, 100:5, 100:6, 100:7, or any range thereof. A molding agent can also be added during mixing. The molding agent can be a mixture of polyvinyl alcohol and starch, with a mass ratio of polyvinyl alcohol to starch of 1:(1~2). The amount of molding agent added can be 4~6% of the total mass of the modified solid waste base material, activator, and molding agent, for example, 4%, 4.5%, 5%, 5.5%, 6%, or any range thereof. Deionized water is added during mixing to adjust the material's moisture content until the material is loosely granular and can be molded by hand. Adding a molding agent helps improve the material's plasticity and post-molding strength. The uniformly mixed materials are fed into a molding machine and pressed into spherical conditioner particles. The particle size can be controlled between 2 and 4 mm, for example, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, or any range thereof. The molded conditioner is then placed in a drying oven for drying. The drying temperature can be between 90 and 110°C, for example, 90°C, 95°C, 100°C, 105°C, 110°C, or any range thereof; the drying time can be between 1.5 and 2.5 hours, for example, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, or any range thereof. The dried product is a solid waste-based acidic conditioner.

[0028] The solid waste-based acidic conditioner prepared by this invention has a pH value that can be controlled between 3.5 and 4.5, is weakly acidic, has no strong corrosiveness, and has the dual functions of mild dealkali removal and silicon-aluminum activation. It can also be recycled and reused.

[0029] Secondly, this invention also provides a solid waste-based acidic conditioner, prepared by the above-described method. This solid waste-based acidic conditioner uses coal gangue and phosphogypsum, two industrial solid wastes, as main raw materials, which are compounded, calcined, modified, and composite molded. Its pH value can be controlled between 3.5 and 4.5, exhibiting weak acidity and no strong corrosiveness. It possesses both mild dealkalization and silicon-aluminum activation functions. This conditioner has a porous structure with a porosity exceeding 50%, which is beneficial for increasing the contact area and reaction efficiency with red mud.

[0030] Thirdly, the present invention also provides a method for red mud dealkalization and activation based on a solid waste-based acidic conditioner, comprising the following steps: Red mud powder was mixed with the above-mentioned solid waste-based acidic conditioning agent to make pulp, and after stirring and reaction, the dealkalized and activated red mud was obtained.

[0031] In this invention, the red mud is preferably high-alkali red mud produced during the Bayer process for alumina production, with an initial pH value typically ≥11.5, a SiO2 content generally of 15-25%, and an Al2O3 content generally of 10-20%. Before use, the red mud can be pretreated, including stirring, drying, and pulverizing. Specifically, the Bayer process red mud is stirred evenly and then sent to a dryer for low-temperature drying, with the drying temperature controlled at 80-100℃, until the moisture content is 15-25%. If the moisture content is too high, it will affect the contact efficiency between the conditioner and the red mud; if the moisture content is too low, energy consumption will increase. The dried red mud is then sent to a pulverizing device for pulverization. The particle size of the pulverized red mud can be controlled within 70-100 mesh, for example, 70 mesh, 80 mesh, 90 mesh, 100 mesh, or any range thereof. The smaller the particle size of the pulverized red mud, the larger the specific surface area, which is beneficial for improving the subsequent dealkalization and activation reaction rates.

[0032] This invention involves mixing and reacting the prepared red mud powder with a solid waste-based acidic conditioner. The mass ratio of red mud powder to the solid waste-based acidic conditioner can be 100:(15~25), for example, 100:15, 100:18, 100:20, 100:22, 100:25, or any range thereof. Both are fed into a reaction vessel, and water is added to adjust the slurry concentration to 40~60wt%, for example, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, or any range thereof. The stirring assembly is started, and the stirring speed can be 70~110 r / min, for example, 70 r / min, 80 r / min, 90 r / min, 100 r / min, 110 r / min, or any range thereof.

[0033] This invention involves a synergistic reaction of mild dealkali removal and silicon-aluminum activation during the stirring reaction process. Regarding mild dealkali removal, the weakly acidic components in the solid waste-based acidic conditioner, such as phosphogypsum and citric acid, undergo a mild neutralization reaction with free alkalis in red mud, such as NaOH and KOH, as well as the basic groups in bound alkalis, such as calcium nepheline and nepheline. This avoids strong acid corrosion and gradually lowers the pH of the red mud to 7.5-8.5, while simultaneously generating harmless salts such as sodium sulfate and potassium chloride, without secondary pollution. During the reaction, the porous structure of the porous solid waste substrate can adsorb free alkali ions in the red mud, further enhancing the dealkali removal effect, achieving a dealkali removal rate of over 90%. In terms of silicon-aluminum activation, under a mild acidic environment, the activators sodium fluorosilicate and metakaolin, along with the modifier ferrous sulfate, work synergistically to disrupt the crystal structure of inert silicon-aluminum mineral phases such as nepheline and calcium nepheline in red mud. This transforms inert SiO2 and Al2O3 into active silicon-aluminum components such as active SiO2 and aluminum hydroxide. Simultaneously, the silicon-aluminum components in the solid waste substrate can synergistically interact with the active components in the red mud, enhancing the silicon-aluminum activation efficiency. After activation, the active SiO2 content in the red mud can reach over 12%, the active Al2O3 content can reach over 8%, and the activation rate can reach over 75%.

[0034] In this invention, the temperature of the stirring reaction is controlled at 40~60℃, for example, it can be 40℃, 45℃, 50℃, 55℃, 60℃ or any range of the above values. The reaction time of the stirring reaction is 60~90min, for example, it can be 60min, 65min, 70min, 75min, 80min, 85min, 90min or any range of the above values. During the stirring reaction, the pH value and active component content of the reaction system can be monitored in real time using an online pH meter and an active component detector. When the pH drops to 7.5~8.5 and the active SiO2 content is ≥12%, the stirring reaction can be stopped.

[0035] After the stirring reaction is completed, the reaction slurry is subjected to solid-liquid separation to obtain de-alkali activated red mud and adsorbed saturated solid waste acidic conditioner. The separation method can be centrifugal filtration. The centrifugal filtration speed can be 1800~2800 r / min, for example, 1800 r / min, 2000 r / min, 2200 r / min, 2300 r / min, 2500 r / min, 2800 r / min or any range thereof; the centrifugal filtration time can be 15~30 min, for example, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, 30 min or any range thereof.

[0036] In this invention, due to the significant particle size difference between red mud powder and solid waste-based acidic conditioner—red mud powder having a particle size of 70-100 mesh (approximately 0.15-0.2 mm), while the solid waste-based acidic conditioner consists of spherical particles of 2-4 mm—effective separation can be achieved during centrifugal filtration by utilizing this particle size difference. The filtrate (water) is discharged through a filter screen or filter cloth; large particles of the solid waste-based acidic conditioner are retained above the filter screen; and small particles of the dealkali-activated red mud are separated and collected. The separated dealkali-activated red mud has a moisture content controlled below 20% and a pH value of 7.5-8.5, and can be directly used for subsequent preparation of high-value-added products such as cementitious materials, adsorbents, and building aggregates.

[0037] In this invention, the separated, adsorbed, saturated solid waste-based acidic conditioner can be regenerated for recycling, significantly reducing the cost of conditioner use. The regeneration method can employ a low-temperature roasting regeneration method. The adsorbed, saturated solid waste-based acidic conditioner is fed into a regeneration furnace and roasted at 500-600℃ for 1-2 hours. For example, the regeneration temperature can be 500℃, 520℃, 550℃, 580℃, 600℃, or any range thereof, and the roasting time can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, or any range thereof. Under these conditions, the alkaline substances and impurities adsorbed by the conditioner are fully desorbed, restoring the conditioner's weak acidity and activity. Roasting is carried out in an air atmosphere, and after roasting, the furnace is cooled to room temperature to obtain the regenerated conditioner. After the first regeneration, the pH of the solid waste-based acidic conditioner can be restored to 3.5~4.5, and the adsorption capacity and activation efficiency can be restored to more than 85% of the fresh conditioner. It can be recycled more than 20 times.

[0038] In this invention, the separated filtrate can be sent to a filtrate treatment unit for resource recovery. The filtrate contains salts generated during the reaction, which can be treated through neutralization, filtration, and concentration. Specifically, a small amount of lime can be added to adjust the pH to 7.0-7.5, causing some metal ions to precipitate and be removed. Then, filtration is performed, and the filtrate is concentrated to obtain a mixed salt solution, which can be recycled as an industrial raw material. The filter residue produced during filtration can be mixed with impurities removed during red mud pretreatment and sent to a solid waste disposal unit for harmless treatment. The small amount of tail gas generated during regeneration, mainly water vapor and a small amount of volatile impurities, can be treated by a condensation purification device. After treatment, it meets emission standards, and the condensate can be reused in red mud drying and other processes, achieving water resource recycling. The entire process has no wastewater or waste gas emissions, meeting green environmental protection requirements.

[0039] In summary, the red mud dealkalization and activation method based on solid waste-based acidic conditioners provided by this invention uses coal gangue and phosphogypsum as raw materials to prepare a composite acidic conditioner, realizing the resource utilization of industrial solid waste. Through calcination, modification, and composite molding, the conditioner possesses mild acidity, a porous structure, and silicon-aluminum activation functions. The conditioner is mixed and reacted with red mud under mild conditions, simultaneously completing the dealkalization and silicon-aluminum activation of the red mud, avoiding problems caused by strong acid corrosion and high-temperature calcination. Solid-liquid separation is achieved through particle size differences, and the saturated conditioner is regenerated by calcination, realizing the recycling of the conditioner. The filtrate is recycled, realizing the recycling of process water. This method has a simplified process, mild reaction, low energy consumption, no secondary pollution, high dealkalization rate, and good silicon-aluminum activation effect, providing an effective way for the high-value-added resource utilization of red mud.

[0040] The technical solution of the present invention will be further described below with reference to specific embodiments. The present invention does not impose any special restrictions on the source of reagents used in the following embodiments; commercially available products well known to those skilled in the art can be used. The red mud used in the following embodiments is Bayer process red mud.

[0041] In the following embodiments, the relevant indicator testing methods are as follows: The SiO2 and Al2O3 contents of red mud were determined using X-ray fluorescence spectrometry (XRF). After drying, grinding, pressing, or melting the red mud samples, the contents of SiO2 and Al2O3 were determined using an XRF spectrometer.

[0042] The active SiO2 and active Al2O3 contents of red mud were determined by alkaline leaching. A certain amount of sample was weighed and placed in a 20% sodium hydroxide solution. The sample was shaken and leached in an 80℃ constant temperature water bath for 1 hour. After filtration, the SiO2 and Al2O3 contents in the filtrate were determined, which are the contents of active SiO2 and active Al2O3.

[0043] pH of red mud or solid waste-based acidic conditioner: The pH was determined according to "HJ 962-2018 Determination of Soil pH by Potential Method". The sample was weighed and mixed with water at a mass ratio of 1:2.5, shaken thoroughly, and allowed to stand. The pH of the supernatant was then measured using a pH meter.

[0044] Red mud dealkali removal rate: The mud was digested at high temperature with hydrofluoric acid, hydrochloric acid, and nitric acid, and the solution was diluted to a 250 mL volumetric flask. Na+ was determined using a flame photometer. + Leaching rate. Using Na... + Leaching rate is used to represent the dealkali removal rate, Na + The leaching rate is calculated using the following formula: ; in, Sodium content in red mud (%) The sodium content (%) in the filter residue after acid leaching.

[0045] The growth rate of silicon-aluminum activity is characterized by the increase in active SiO2 and active Al2O3 in the red mud before and after the reaction. The growth rate of silicon-aluminum activity is calculated using the following formula: Silicon-aluminum activity growth rate = ×100%; in, , The active SiO2 content and active Al2O3 content (%) in the red mud before reaction are respectively. , The active SiO2 content and active Al2O3 content (%) in the red mud after the reaction are respectively.

[0046] Activity recovery rate: Used to evaluate the degree of performance recovery of acidic conditioners based on solid waste after regeneration. Calculated using the following formula: Activity recovery rate = ×100%; in, The percentage increase in silica-alumina activity of fresh solid waste-based acidic conditioner under standard red mud treatment conditions. The percentage increase in silicon-aluminum activity of the recycled solid waste-based acidic conditioner under the same conditions.

[0047] Example 1 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner, including the following steps: (1) Red mud pretreatment: The initial pH value of fresh red mud is 12.8, the SiO2 content is 20%, the Al2O3 content is 15%, and the initial moisture content is about 70%. Fresh red mud is sent to a dryer and dried at 90℃ until the moisture content is 20%; the dried red mud is sent to a pulverizing device and pulverized to a particle size of 80~100 mesh to obtain homogenized red mud powder.

[0048] (2) Preparation of acidic conditioner for solid waste: Coal gangue and phosphogypsum were compounded at a mass ratio of 1:1, crushed to a particle size ≤20mm, and calcined in a calcining furnace at 700℃ for 2 hours. After cooling, the mixture was pulverized to 100~120 mesh to obtain porous solid waste base material. The porous solid waste base material was mixed with a modifier at a mass ratio of 100:9, and deionized water was added to adjust the slurry concentration to 40wt%. The mixture was stirred and modified at 60℃ for 30 minutes, and then vacuum dried at 85℃ to constant weight to obtain modified solid waste base material. The modifier was a compound of citric acid and ferrous sulfate at a mass ratio of 3:1. The modified solid waste base material and the activator were mixed evenly at a mass ratio of 100:5. The activator was a compound of sodium fluorosilicate and metakaolin at a mass ratio of 2:1. A molding agent (a compound of polyvinyl alcohol and starch at a mass ratio of 1:1, with an addition amount of 5% of the total mass of the mixture) was added. After mixing evenly, the mixture was fed into a molding machine. An appropriate amount of deionized water was added to adjust the material humidity. The mixture was pressed into spherical particles with a particle size of 3 mm and dried at 100°C for 2 hours to obtain a solid waste-based acidic conditioner with a pH value of 4.0.

[0049] (3) Mild dealkali removal and synergistic reaction of silicon and aluminum activation: The red mud powder obtained in step (1) and the solid waste-based acidic conditioner prepared in step (2) are fed into the reactor at a mass ratio of 100:20. Deionized water is added to adjust the slurry concentration to 50wt%. Stirring is started at a speed of 90r / min, and the reaction temperature is controlled at 50℃. The pH value and active component content of the system are monitored in real time during the reaction. When the pH value drops to 8.0, the active SiO2 content reaches 13.2%, and the active Al2O3 content reaches 9.1%, the reaction is stopped. The reaction time is about 75min, and the dealkali-activated red mud slurry is obtained.

[0050] (4) Solid-liquid separation and conditioner regeneration: The slurry obtained in step (3) is sent to a centrifugal filter and centrifuged at 2300 r / min for 20 min to separate the de-alkali activated red mud (pH value of 8.0) and the adsorbed saturated solid waste acidic conditioner; the adsorbed saturated solid waste acidic conditioner is sent to a regeneration furnace and calcined at 550℃ for 1.2 h for regeneration. After the first regeneration, the pH value of the conditioner is restored to 4.1 and the silicon-aluminum activity growth rate is restored to 90.5% of that of the fresh conditioner.

[0051] (5) Filtrate treatment and resource recycling: Add quicklime to the filtrate obtained by centrifugation and filtration in step (4) to adjust the pH value to 7.2, filter to remove insoluble matter, and concentrate the filtrate to obtain a mixed salt solution; the tail gas generated during the regeneration process is condensed and purified, and then reused in the red mud drying process in step (1).

[0052] In this embodiment, the red mud dealkalization rate was 92.3%, and the silicon-aluminum activity growth rate was 80.5%. The regenerated conditioner was recycled for the synergistic reaction in step (3). After 25 cycles, its activity recovery rate remained above 78%.

[0053] Example 2 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 13.5, the SiO2 content is 25%, the Al2O3 content is 20%, and the initial moisture content is 75%; the drying temperature is 100℃, and the moisture content after drying is 25%; it is crushed to 90~100 mesh.

[0054] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum is 1:1.3; the calcination temperature is 750℃ and the calcination time is 2.5h; the particle size after crushing is 110~120 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier is 3.5:1, the mass ratio of porous solid waste base material to modifier is 100:12, the modification temperature is 70℃ and the modification time is 35min; the mass ratio of sodium fluorosilicate to metakaolin in the activator is 2.5:1, the mass ratio of modified solid waste base material to activator is 100:7; the amount of molding agent added is 6%, the molding particle size is 4mm, the drying temperature is 110℃ and the drying time is 2.5h; the pH value of the obtained solid waste-based acidic conditioner is 3.5.

[0055] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:25, the slurry concentration is 60wt%, the stirring speed is 110r / min, the reaction temperature is 60℃, and the reaction time is 90min; at the end of the reaction, the pH value of red mud is 7.5, the active SiO2 content is 14.5%, and the active Al2O3 content is 9.8%.

[0056] (4) Solid-liquid separation and regeneration: The centrifugation speed was 2800 r / min and the centrifugation time was 25 min; the regeneration temperature was 600℃ and the calcination time was 1.5 h; the activity recovery rate of the conditioner after regeneration was 92.1%.

[0057] In this embodiment, the red mud dealkalization rate was 93.8%, and the silicon-aluminum activity growth rate was 83.2%.

[0058] Example 3 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 11.5, the SiO2 content is 15%, the Al2O3 content is 10%, and the initial moisture content is 65%; the drying temperature is 80℃, and the moisture content after drying is 15%; it is crushed to 80~90 mesh.

[0059] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum is 1:0.7; the calcination temperature is 650℃ and the calcination time is 1.5h; the particle size after crushing is 100~110 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier is 2.5:1, the mass ratio of porous solid waste base material to modifier is 100:6, the modification temperature is 50℃ and the modification time is 25min; the mass ratio of sodium fluorosilicate to metakaolin in the activator is 1.5:1, the mass ratio of modified solid waste base material to activator is 100:3; the amount of molding agent added is 4%, the molding particle size is 2mm, the drying temperature is 90℃ and the drying time is 1.5h; the pH value of the obtained solid waste-based acidic conditioner is 4.5.

[0060] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:15, the slurry concentration is 40wt%, the stirring speed is 70r / min, the reaction temperature is 40℃, and the reaction time is 60min; at the end of the reaction, the pH value of red mud is 8.5, the active SiO2 content is 12.1%, and the active Al2O3 content is 8.2%.

[0061] (4) Solid-liquid separation and regeneration: The centrifugation speed was 1800 r / min and the centrifugation time was 15 min; the regeneration temperature was 500℃ and the calcination time was 1.0 h; the activity recovery rate of the conditioner after regeneration was 85.7%.

[0062] In this embodiment, the red mud dealkalization rate was 90.1%, and the silicon-aluminum activity growth rate was 75.3%.

[0063] Example 4 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 12.2, the SiO2 content is 18%, the Al2O3 content is 13%, and the initial moisture content is 68%; the drying temperature is 85℃, and the moisture content after drying is 18%; it is crushed to 85~100 mesh.

[0064] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum is 1:0.9; the calcination temperature is 680℃ and the calcination time is 1.8h; the particle size after crushing is 105~120 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier is 2.8:1, the mass ratio of porous solid waste base material to modifier is 100:7.5, the modification temperature is 55℃ and the modification time is 28min; the mass ratio of sodium fluorosilicate to metakaolin in the activator is 1.8:1, the mass ratio of modified solid waste base material to activator is 100:4; the amount of molding agent added is 4.5%, the molding particle size is 2.5mm, the drying temperature is 95℃ and the drying time is 1.8h; the pH value of the obtained solid waste-based acidic conditioner is 4.2.

[0065] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:17, the slurry concentration is 45wt%, the stirring speed is 80r / min, the reaction temperature is 45℃, and the reaction time is 65min; at the end of the reaction, the pH value of red mud is 8.2, the active SiO2 content is 12.8%, and the active Al2O3 content is 8.6%.

[0066] (4) Solid-liquid separation and regeneration: The centrifugation speed was 2000 r / min and the centrifugation time was 18 min; the regeneration temperature was 520℃ and the calcination time was 1.1 h; the activity recovery rate of the conditioner after regeneration was 87.9%.

[0067] In this embodiment, the red mud dealkalization rate was 91.2%, and the silicon-aluminum activity growth rate was 77.8%.

[0068] Example 5 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 13.0, the SiO2 content is 22%, the Al2O3 content is 17%, and the initial moisture content is 72%; the drying temperature is 95℃, and the moisture content after drying is 22%; it is crushed to 95~100 mesh.

[0069] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum is 1:1.1; the calcination temperature is 720℃ and the calcination time is 2.2h; the particle size after crushing is 115~120 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier is 3.2:1, the mass ratio of porous solid waste base material to modifier is 100:10.5, the modification temperature is 65℃ and the modification time is 32min; the mass ratio of sodium fluorosilicate to metakaolin in the activator is 2.2:1, the mass ratio of modified solid waste base material to activator is 100:6; the amount of molding agent added is 5.5%, the molding particle size is 3.5mm, the drying temperature is 105℃ and the drying time is 2.2h; the pH value of the obtained solid waste-based acidic conditioner is 3.8.

[0070] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:22, the slurry concentration is 55wt%, the stirring speed is 100r / min, the reaction temperature is 55℃, and the reaction time is 80min; at the end of the reaction, the pH value of red mud is 7.8, the active SiO2 content is 13.8%, and the active Al2O3 content is 9.4%.

[0071] (4) Solid-liquid separation and regeneration: The centrifugation speed was 2500 r / min and the centrifugation time was 22 min; the regeneration temperature was 580℃ and the calcination time was 1.3 h; the activity recovery rate of the conditioner after regeneration was 91.3%.

[0072] In this embodiment, the red mud dealkalization rate was 93.1%, and the silicon-aluminum activity growth rate was 81.7%.

[0073] Example 6 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 11.8, the SiO2 content is 16%, the Al2O3 content is 11%, and the initial moisture content is 66%; the drying temperature is 82℃, and the moisture content after drying is 16%; it is crushed to 80~95 mesh.

[0074] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum is 1:0.8; the calcination temperature is 660℃ and the calcination time is 1.6h; the particle size after crushing is 100~115 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier is 2.6:1, the mass ratio of porous solid waste base material to modifier is 100:6.5, the modification temperature is 52℃ and the modification time is 26min; the mass ratio of sodium fluorosilicate to metakaolin in the activator is 1.6:1, the mass ratio of modified solid waste base material to activator is 100:3.5; the amount of molding agent added is 4.2%, the molding particle size is 2.2mm, the drying temperature is 92℃ and the drying time is 1.6h; the pH value of the obtained solid waste-based acidic conditioner is 4.3.

[0075] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:16, the slurry concentration is 42wt%, the stirring speed is 75r / min, the reaction temperature is 42℃, and the reaction time is 62min; at the end of the reaction, the pH value of red mud is 8.3, the active SiO2 content is 12.3%, and the active Al2O3 content is 8.4%.

[0076] (4) Solid-liquid separation and regeneration: The centrifugation speed was 1900 r / min and the centrifugation time was 16 min; the regeneration temperature was 510℃ and the calcination time was 1.05 h; the activity recovery rate of the conditioner after regeneration was 86.3%.

[0077] In this embodiment, the red mud dealkalization rate was 90.5%, and the silicon-aluminum activity growth rate was 76.5%.

[0078] Example 7 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 13.2, the SiO2 content is 24%, the Al2O3 content is 19%, and the initial moisture content is 74%; the drying temperature is 98℃, and the moisture content after drying is 24%; it is crushed to 98~100 mesh.

[0079] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum was 1:1.2; the calcination temperature was 740℃ and the calcination time was 2.4h; the particle size after crushing was 118~120 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier was 3.4:1, the mass ratio of porous solid waste base material to modifier was 100:11.5, the modification temperature was 68℃ and the modification time was 34min; the mass ratio of sodium fluorosilicate to metakaolin in the activator was 2.4:1, the mass ratio of modified solid waste base material to activator was 100:6.5; the amount of molding agent added was 5.8%, the molding particle size was 3.8mm, the drying temperature was 108℃ and the drying time was 2.4h; the pH value of the obtained solid waste-based acidic conditioner was 3.6.

[0080] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:24, the slurry concentration is 58wt%, the stirring speed is 105r / min, the reaction temperature is 58℃, and the reaction time is 85min; at the end of the reaction, the pH value of red mud is 7.6, the active SiO2 content is 14.2%, and the active Al2O3 content is 9.6%.

[0081] (4) Solid-liquid separation and regeneration: The centrifugation speed was 2700 r / min and the centrifugation time was 24 min; the regeneration temperature was 590℃ and the calcination time was 1.4 h; the activity recovery rate of the conditioner after regeneration was 91.8%.

[0082] In this embodiment, the red mud dealkalization rate was 93.5%, and the silicon-aluminum activity growth rate was 82.8%.

[0083] Example 8 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 12.5, the SiO2 content is 19%, the Al2O3 content is 14%, and the initial moisture content is 70%; the drying temperature is 92℃, and the moisture content after drying is 21%; it is crushed to 88~100 mesh.

[0084] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum was 1:1.05; the calcination temperature was 710℃ and the calcination time was 2.1h; the particle size after crushing was 108~120 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier was 3.1:1, the mass ratio of porous solid waste base material to modifier was 100:9.5, the modification temperature was 62℃ and the modification time was 31min; the mass ratio of sodium fluorosilicate to metakaolin in the activator was 2.1:1, the mass ratio of modified solid waste base material to activator was 100:5.5; the amount of molding agent added was 5.2%, the molding particle size was 3.2mm, the drying temperature was 102℃ and the drying time was 2.1h; the pH value of the obtained solid waste-based acidic conditioner was 3.9.

[0085] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:21, the slurry concentration is 52wt%, the stirring speed is 95r / min, the reaction temperature is 52℃, and the reaction time is 70min; at the end of the reaction, the pH value of red mud is 7.9, the active SiO2 content is 13.5%, and the active Al2O3 content is 9.2%.

[0086] (4) Solid-liquid separation and regeneration: The centrifugation speed was 2400 r / min and the centrifugation time was 21 min; the regeneration temperature was 560℃ and the calcination time was 1.25 h; the activity recovery rate of the conditioner after regeneration was 90.8%.

[0087] In this embodiment, the red mud dealkalization rate was 92.7%, and the silicon-aluminum activity growth rate was 80.9%.

[0088] Example 9 This embodiment provides a red mud dealkali removal and activation method based on a solid waste-based acidic conditioner. The steps are basically the same as in Embodiment 1, except that the process parameters are as follows: (1) Red mud pretreatment: The initial pH value of fresh red mud is 12.0, the SiO2 content is 17%, the Al2O3 content is 12%, and the initial moisture content is 67%; the drying temperature is 88℃, and the moisture content after drying is 17%; it is crushed to 82~100 mesh.

[0089] (2) Preparation of solid waste-based acidic conditioner: The mass ratio of coal gangue to phosphogypsum was 1:0.85; the calcination temperature was 670℃ and the calcination time was 1.7h; the particle size after crushing was 102~118 mesh; the mass ratio of citric acid to ferrous sulfate in the modifier was 2.7:1, the mass ratio of porous solid waste base material to modifier was 100:7, the modification temperature was 58℃ and the modification time was 27min; the mass ratio of sodium fluorosilicate to metakaolin in the activator was 1.7:1, the mass ratio of modified solid waste base material to activator was 100:3.8; the amount of molding agent added was 4.8%, the molding particle size was 2.8mm, the drying temperature was 98℃ and the drying time was 1.7h; the pH value of the obtained solid waste-based acidic conditioner was 4.4.

[0090] (3) Synergistic reaction: The mass ratio of red mud powder to conditioner is 100:18, the slurry concentration is 48wt%, the stirring speed is 85r / min, the reaction temperature is 48℃, and the reaction time is 68min; at the end of the reaction, the pH value of red mud is 8.4, the active SiO2 content is 12.6%, and the active Al2O3 content is 8.5%.

[0091] (4) Solid-liquid separation and regeneration: The centrifugation speed was 2100 r / min and the centrifugation time was 17 min; the regeneration temperature was 530℃ and the calcination time was 1.15 h; the activity recovery rate of the conditioner after regeneration was 88.5%.

[0092] In this embodiment, the red mud dealkalization rate was 91.0%, and the silicon-aluminum activity growth rate was 77.2%.

[0093] Comparative Example 1 This comparative example is basically the same as Example 1, except that in step (2) when preparing the solid waste-based acidic conditioner, no activator (sodium fluorosilicate and metakaolin) was added, and the modified solid waste base material was directly molded.

[0094] The pH value of the treated red mud in this comparative example was 8.2, the active SiO2 content was 10.3%, the dealkali removal rate was 91.0%, and the silicon-aluminum activity growth rate was 60.5%. The results show that the silicon-aluminum activation effect decreased significantly without the addition of an activator.

[0095] Comparative Example 2 This comparative example is basically the same as Example 1, except that in step (2) when preparing the solid waste-based acidic conditioner, no modifier was added, and the porous solid waste base material was directly mixed with the activator to form the material.

[0096] After treatment, the pH value of the red mud in this comparative example was 8.4, the active SiO2 content was 9.8%, the dealkali removal rate was 89.2%, and the silicon-aluminum activity growth rate was 57.5%. The results show that without the addition of modifier, both the dealkali removal effect and the silicon-aluminum activation effect decreased, with the decrease in the silicon-aluminum activity growth rate being more significant.

[0097] Comparative Example 3 This comparative example uses a stepwise process of strong acid neutralization and dealkali removal followed by high-temperature calcination activation to treat red mud. The specific steps are as follows: (1) Red mud pretreatment: Same as step (1) in Example 1.

[0098] (2) Strong acid neutralization and dealkali removal: Mix red mud powder with water to prepare a slurry, add hydrochloric acid to adjust the pH value to about neutral, stir and react, then filter to obtain red mud filter cake after dealkali removal.

[0099] (3) High-temperature calcination activation: After drying the red mud filter cake after dealkalization, it is calcined and activated at 800℃, cooled and crushed to obtain activated red mud.

[0100] Using the same red mud raw material as in Example 1 (initial pH 12.8, SiO2 content 20%, Al2O3 content 15%), the treated red mud had a pH of 8.1, an active SiO2 content of 9.8%, a dealkali removal rate of 90.5%, and a silicon-aluminum activity growth rate of 58.2%.

[0101] Comparative Example 4 This comparative example uses a stepwise process of water washing and dealkalization followed by strong alkali activation to treat red mud. The specific steps are as follows: (1) Red mud pretreatment: Same as step (1) in Example 1.

[0102] (2) Water washing and dealkalization: Mix red mud powder with water, stir and wash, then filter. Repeat washing multiple times until the pH value of the filtrate drops to a certain range to obtain red mud filter cake after dealkalization.

[0103] (3) Strong alkali activation: The red mud filter cake after dealkali removal is mixed with sodium hydroxide solution, stirred and reacted, then filtered, washed and dried to obtain activated red mud.

[0104] Using the same red mud raw material as in Example 1, the treated red mud had a pH value of 10.2, an active SiO2 content of 10.5%, a dealkali removal rate of 65.3%, and a silicon-aluminum activity growth rate of 62.1%.

[0105] Comparative Example 5 This comparative example uses existing single solid waste phosphogypsum as a conditioner for dealkalization treatment. The specific steps are as follows: (1) Red mud pretreatment: Same as step (1) in Example 1.

[0106] (2) Conditioning agent preparation: Phosphogypsum is crushed and pulverized separately without compounding, modification and activation treatment.

[0107] (3) Dealkali reaction: Red mud powder and phosphogypsum conditioner are mixed at a mass ratio of 100:20 to form a slurry. The mixture is stirred at 50°C for 75 minutes. After the reaction, the red mud is filtered to obtain dealkali-free red mud.

[0108] Using the same red mud raw material as in Example 1, the treated red mud had a pH of 8.3, an active SiO2 content of 10.1%, a dealkali removal rate of 88.7%, and a silicon-aluminum activity growth rate of 55.8%. This process only has a dealkali removal function and cannot effectively activate the silicon-aluminum components. The conditioner cannot be regenerated, resulting in high costs.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing a solid waste-based acidic conditioner, characterized in that, Includes the following steps: Coal gangue and phosphogypsum were compounded and then calcined to obtain porous solid waste base material; The porous solid waste base material and the modifier are mixed and pulped, and then dried to obtain the modified solid waste base material; the modifier includes citric acid and ferrous sulfate; The modified solid waste base material is mixed with an activating agent, which includes sodium fluorosilicate and metakaolin, to obtain the solid waste-based acidic conditioner.

2. The preparation method according to claim 1, characterized in that, The mass ratio of coal gangue to phosphogypsum is 1:(0.7~1.3); the calcination temperature is 650~750℃ and the time is 1.5~2.5h.

3. The preparation method according to claim 1, characterized in that, The mass ratio of citric acid to ferrous sulfate in the modifier is (2.5~3.5):1; the mass ratio of porous solid waste base material to modifier is 100:(6~12).

4. The preparation method according to claim 1, characterized in that, The mass ratio of sodium fluorosilicate to metakaolin in the activator is (1.5~2.5):1; the mass ratio of modified solid waste base material to activator is 100:(3~7).

5. The preparation method according to claim 1, characterized in that, The process of mixing the modified solid waste base material with the activator also includes the step of adding a molding agent; the amount of the molding agent added is 4 to 6% of the total mass of the modified solid waste base material, the activator, and the molding agent; the molding agent includes polyvinyl alcohol and starch.

6. A solid waste-based acidic conditioner, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 5.

7. A method for red mud dealkalization and activation based on a solid waste-based acidic conditioner, characterized in that, Includes the following steps: Red mud powder is mixed with the solid waste-based acidic conditioner described in claim 6 to form a slurry, and after stirring and reaction, the red mud after dealkalization and activation is obtained. The mass ratio of the red mud powder to the solid waste-based acidic conditioner is 100:(15~25).

8. The red mud dealkali removal and activation method based on solid waste-based acidic conditioner as described in claim 7, characterized in that, The red mud powder has a particle size of 70-100 mesh and a moisture content of less than 25%; the solid waste-based acidic conditioner has a particle size of 2-4 mm.

9. The red mud dealkali removal and activation method based on solid waste-based acidic conditioner as described in claim 7, characterized in that, The temperature of the stirring reaction is 40~60℃, and the stirring reaction time is 60~90min.

10. The red mud dealkalization and activation method based on solid waste-based acidic conditioner as described in claim 7, characterized in that, The separation is carried out by centrifugal filtration, and the de-alkali activated red mud and the adsorbed saturated solid waste acidic conditioner are obtained by centrifugal filtration; the adsorbed saturated solid waste acidic conditioner is regenerated by calcining at 500~600℃ for 1~2h. The centrifugal filtration speed is 1800~2800 r / min; the centrifugal filtration time is 15~30 min.