Industrial waste residue curing agent, preparation thereof and application of industrial waste residue curing agent in high-water-content sludge

Abstract

The invention discloses an industrial waste residue curing agent, preparation thereof and application of the industrial waste residue curing agent in high-water-content sludge, and belongs to the technical field of curing agents and preparation thereof. The curing agent comprises 18-22 parts of light calcined magnesia, 14-18 parts of magnesium chloride hexahydrate, 42-48 parts of industrial waste residue powder (the mass ratio of steel slag to fly ash is 1: 1.5), 10-12 parts of metakaolin, 3-4 parts of desulfurized gypsum, 1-2 parts of polypropylene fiber and 0.5-1 part of nano silicon dioxide. The preparation method comprises the following steps: premixing and activating, mixing powder and forming a curing agent in sequence, the curing agent is applied to curing of sludge with the water content of 30-70%, magnesium oxychloride cement is taken as a matrix, industrial waste residues and metakaolin construct a multi-component gel system, nano silicon dioxide fills pores and activates reaction, polypropylene fiber inhibits cracks, and desulfurized gypsum regulates and controls the hydration process. The method realizes resource utilization of industrial waste residues, solves the problem of solidification of high-water-content sludge, and has the advantages of environmental protection, economy and engineering performance.

Description

Technical Field

[0001] The invention relates to the technical field of curing agents and preparation thereof, and in particular to an industrial waste residue curing agent, preparation thereof and application thereof in high-water-content sludge. Background Art

[0002] Large quantities of high-water content silt are generated in numerous engineering projects, including urban river dredging, coastal reclamation, and municipal pipeline construction. This silt, characterized by its naturally high water content, large porosity, extremely low strength, and strong fluidity, is directly dumped or simply landfilled. This silt not only consumes significant land resources but can also cause damage to the surrounding ecological environment due to silt slippage and leakage, polluting soil and groundwater, and leading to secondary siltation in rivers.

[0003] Traditional silt solidification treatment mostly uses cement, lime and other curing agents. However, traditional curing agents have many insurmountable defects: on the one hand, traditional curing agents such as cement and lime are relatively expensive, and their large-scale use will significantly increase the cost of engineering treatment. In addition, the cement production process has high energy consumption and large carbon emissions, which is not in line with the current green and low-carbon development concept; on the other hand, traditional curing agents have poor adaptability to high-water-content silt. Existing traditional curing agents are generally suitable for curing slightly dry silt. The silt needs to be turned over and dried in the sun to reduce its moisture content to below 10% before adding curing agents for curing. In a high-water-content environment, the hydration reaction of cement and other materials is difficult to proceed fully, and a large amount of curing agent needs to be added to barely meet the basic strength requirements. In addition, the mechanical properties of the solidified silt are limited, and it is prone to cracking, strength attenuation and other problems, making it difficult to meet the project's requirements for the strength and stability of the solidified soil.

[0004] At the same time, the accumulation of waste residues, such as steel slag and fly ash, generated during industrial production is becoming increasingly serious. Steel slag is a byproduct of the steelmaking process, while fly ash is a waste product from industries like thermal power generation. The long-term accumulation of these industrial waste residues not only occupies significant land but also pollutes the surrounding soil, water, and air through the leaching of harmful substances and the creation of dust. Therefore, achieving efficient resource utilization of industrial waste residues has become an urgent need in the fields of environmental protection and comprehensive resource utilization.

[0005] Therefore, developing a curing agent that can efficiently treat high-water content sludge, is low-cost and can realize resource utilization of industrial waste residue has become a key issue that needs to be urgently addressed in this field. Summary of the Invention

[0006] The purpose of the present invention is to provide an industrial waste slag solidifying agent, its preparation method and application in high-water-content sludge. Through reasonable formula design and preparation process, a high-water-content sludge solidifying agent based on industrial waste slag magnesium cementing material is prepared from industrial waste slag. The solidifying agent uses magnesium oxychloride cement as a matrix. The solidifying agent can not only effectively treat sludge with a high water content of 30-70%, significantly improve the mechanical properties of the sludge, and meet the requirements of engineering use, but also realize the resource utilization of industrial waste slag, reduce environmental pollution, and lower production costs, thereby solving the problems of high cost of existing traditional solidifying agents, unsuitability for high-water-content sludge, and large-scale accumulation of industrial waste slag that pollutes the environment.

[0007] To achieve the above-mentioned purpose, the present invention provides an industrial waste residue solidifying agent, which comprises, by weight, 18-22 parts of light-burned magnesium oxide, 14-18 parts of magnesium chloride hexahydrate, 42-48 parts of industrial waste residue powder, 10-12 parts of metakaolin, 3-4 parts of desulfurized gypsum, 1-2 parts of polypropylene fiber and 0.5-1 part of nano-silicon dioxide.

[0008] Preferably, the active magnesium oxide content in the light-burned magnesium oxide is ≥90%.

[0009] Preferably, the specific surface area of ​​industrial waste slag powder is ≥550m 2 / kg, including steel slag and fly ash, and the mass ratio of steel slag to fly ash is 1:1.5.

[0010] Preferably, the particle size of the nano-silicon dioxide is 25-35 nm.

[0011] The present invention also provides a method for preparing the above-mentioned industrial waste residue solidifying agent, which specifically comprises the following steps:

[0012] Step 1: Premix activation

[0013] Putting industrial waste residue powder and nano-silicon dioxide into a high-speed dry mixer for dry mixing to obtain a premixed material;

[0014] Step 2: Powder mixing

[0015] Add light-burned magnesium oxide, metakaolin and desulfurized gypsum to the premixed material and continue mixing for 5-8 minutes to evenly disperse the powder components to obtain a mixed powder;

[0016] Step 3: Forming a curing agent

[0017] Add polypropylene fiber and pre-crushed magnesium chloride hexahydrate to the mixed powder, stir until the polypropylene fiber is evenly dispersed and the magnesium chloride hexahydrate is fully in contact with other components to obtain a finished curing agent.

[0018] Preferably, in step 1, the rotation speed of the high-speed dry mixer is 300-500 r / min, and the dry mixing time is 10 min.

[0019] Preferably, in step 3, the particle size of the pre-crushed magnesium chloride hexahydrate is less than 5 mm, the stirring speed is 100-200 r / min, and the stirring time is 3-5 min.

[0020] The present invention also provides an application of the above-mentioned industrial waste residue solidifying agent, wherein the industrial waste residue solidifying agent is applied to the solidification of high-water content sludge.

[0021] Preferably, the water content of the high-water content sludge is 30-70%.

[0022] Preferably, the specific operation for solidification of high-water-content sludge is: adding the industrial waste residue solidifying agent into the high-water-content sludge, subjecting it to biaxial stirring, turbine stirring and planetary stirring in sequence, and then curing and molding to complete the sludge solidification.

[0023] Lightly burned magnesium oxide (MgO) and magnesium chloride hexahydrate undergo hydration reaction to form magnesium oxychloride hydrate with gelling properties:

[0024] MgO+MgCl2+nH2O→Mg(OH)2·MgCl2·(n-2)H2O;

[0025] Among them, the 5·1·8 phase (5Mg(OH)2·MgCl2·8H2O) is the main phase, forming a network structure of needle-shaped or plate-shaped crystals, providing early strength (rapid hardening within 1 to 3 days). This reaction is exothermic and can accelerate water evaporation and silt consolidation; the MgCl2·6H2O crushed to a particle size of less than 5mm dissolves quickly, providing Cl - ions, promoting the hydration reaction rate of MgO; at the same time, maintaining the weak alkaline environment of the system (pH≈8~9), which not only avoids the inhibition of strong alkalinity on the activity of industrial waste slag, but also provides alkaline conditions for the pozzolanic reaction of industrial waste slag.

[0026] Steel slag is rich in CaO (20-30%), SiO2 (15-20%), Al2O3 (8-12%) and calcium aluminoferrite, and has potential hydraulic properties. Under the alkaline excitation of Mg(OH)2, the active SiO2, Al2O3 and Mg in its glassy body react with each other. 2+ OH - The reaction generates magnesium aluminum silicate gel, which enhances the later strength. The surface of the spherical glass microspheres of fly ash is rich in active SiO2 and Al2O3. They dissolve in an alkaline environment and react with Mg(OH)2 to form hydrated magnesium silicate and hydrated magnesium aluminate. At the same time, the "ball effect" of the spherical particles reduces the viscosity of the silt, improves construction and workability, fills pores, and increases density. The specific surface area of ​​industrial waste slag powder is ≥550m 2 / kg, much higher than ordinary cement (300-400m 2 / kg), significantly increasing the number of active sites on the particle surface, accelerating the reaction with MgO hydration products, and shortening the curing cycle. Specifically, the combination of steel slag (high in calcium) and fly ash (high in silicon and aluminum) combines the "calcium-silicon-aluminum" multi-component gelling activity and the micro-aggregate filling effect, compensating for the lack of activity of a single waste slag. Simultaneously, the large specific surface area promotes sufficient reaction, improving strength while reducing cement usage.

[0027] Metakaolin is rich in amorphous SiO2 and Al2O3, and its activity is 3 to 5 times that of ordinary fly ash. It will preferentially react with Mg(OH)2 to form magnesium aluminum hydroxy carbonate gel, thereby improving early strength and durability, and forming a "dual-activity system" with industrial waste slag powder to make up for the defect of slow strength growth of magnesium oxychloride cement in the later stage. At the same time, it can provide nucleation sites, promote the orderly growth of magnesium oxychloride hydrate and gel phase, and refine the pore structure.

[0028] Nano-SiO2 particles fill the pores of the cementitious material, reducing overall porosity and increasing density. Furthermore, their surface is rich in silanol groups, which promote the nucleation of hydration products, accelerate MgO hydration and pozzolanic reactions, and enhance early strength. Furthermore, they form a "multi-level micro-aggregate filling" system with industrial waste slag powder and metakaolin, synergistically improving strength and impermeability.

[0029] Polypropylene fibers are distributed three-dimensionally in the cementitious system, forming a composite network skeleton of "fiber-cementitious-silt", which inhibits microcracks caused by water migration and hydration shrinkage during the silt solidification process, improves toughness and crack resistance. Moreover, before the initial setting of magnesium oxychloride cement (about 1 to 2 hours), the fibers can also provide micro-support to prevent the silt from forming settlement cracks due to its own weight.

[0030] Desulfurization gypsum (CaSO4·2H2O) dissolves to provide SO4 2- , reacts with C3A (tricalcium aluminate) in steel slag to form ettringite (AFt):

[0031] C3A+3CaSO4·2H2O+26H2O→3CaO·Al2O3·3CaSO4·32H2O;

[0032] The needle-like crystals of ettringite are interspersed in the magnesium oxychloride gel, which enhances the early structural rigidity and slows down the hydration rate of MgO, thus avoiding the difficulty of construction caused by too fast coagulation. 2- With Cl - Competitive adsorption on the Mg(OH)2 surface reduces the migration of harmful ions and improves the long-term stability of the solidified body.

[0033] This solution, centered around the rapid gelling of magnesium oxychloride cement, constructs a multi-component cementing system through a composite pozzolanic reaction of industrial waste slag (steel slag + fly ash) and metakaolin. Utilizing the microscopic filling and chemical activation of nano-SiO2, the micro-reinforcement of polypropylene fibers for crack resistance, and the hydration control of desulfurized gypsum, this system achieves a synergistic chain of "rapid setting, reinforcement, crack resistance, and durability." Essentially, through the precise matching of the physical and chemical interactions of multiple components, it achieves the rapid solidification and locking of moisture in high-moisture sludge, the orderly construction of the cementitious structure, and the efficient release of the activity of the industrial waste slag, ultimately achieving the multiple goals of improved mechanical properties, reduced costs, and environmental friendliness.

[0034] Therefore, the present invention provides an industrial waste residue solidifying agent and its preparation and application in high-water content sludge, which has the following beneficial effects:

[0035] (1) Applicable to sludge with high water content

[0036] Through its unique formulation and preparation process, the present invention effectively solidifies sludge with a high moisture content of 30-70%, significantly improving the sludge's physical and mechanical properties. Compared to traditional solidifying agents, it significantly broadens the applicable sludge moisture content range and solves the problem of high-moisture sludge being difficult to solidify.

[0037] (2) Reasonable proportions, utilization of industrial solid waste, and cost reduction

[0038] This invention uses industrial waste slag powder (steel slag and fly ash) as one of the main raw materials, accounting for ≥45%, achieving large-scale resource utilization of industrial waste slag. This not only reduces industrial waste pollution and land occupation, but also reduces the raw material cost of the curing agent.

[0039] By rationally adjusting the proportions of light-burned magnesia, magnesium chloride hexahydrate, metakaolin, and desulfurized gypsum, while ensuring the curing effect, the total weight of light-burned MgO and MgCl2·6H2O is controlled to ≤ 40 parts, avoiding unnecessary cost increases. Furthermore, the small addition of polypropylene fiber and nano-SiO2 effectively enhances the performance of the curing agent, achieving an overall low-cost, high-performance technical result.

[0040] (3) Improve the mechanical properties of sludge

[0041] During the sludge solidification process, the formation of the magnesium oxychloride cement matrix and the synergistic interaction between its components give the solidified sludge high strength and good stability. The addition of surface-modified polypropylene fibers enhances the toughness of the solidified sludge, while nano-SiO2 further optimizes the microstructure, significantly improving the mechanical properties of the solidified sludge to meet the requirements of engineering applications.

[0042] The technical solution of the present invention is further described in detail below through examples. DETAILED DESCRIPTION

[0043] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. Any other changes, modifications, substitutions, combinations, simplifications made without violating the spirit and principles of the present invention should all be equivalent replacement modes and are included within the scope of protection of the present invention. In addition, it should be understood that after reading the contents of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims appended to this application and all belong to the scope of protection of the present invention.

[0044] References to "embodiments" herein mean that the specific features, structures, or characteristics described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the word "embodiment" in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or relevance to other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the various technical features mentioned in the embodiments can be combined in any manner to form a corresponding implementable technical solution.

[0045] Unless otherwise defined, the technical terms used herein have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms herein is only for describing specific embodiments and is not intended to limit this application.

[0046] Unless otherwise specified in the present invention, the reagents, instruments, and equipment used are those commonly used by those skilled in the art.

[0047] Example 1

[0048] This embodiment provides a high-water content sludge solidifying agent based on industrial waste slag magnesium cementitious material, comprising the following components: light-burned MgO (active MgO 92%): 20 parts; MgCl2·6H2O: 16 parts; industrial waste slag powder (steel slag: fly ash = 1:1.5, specific surface area 580m 2 / kg): 45 parts; metakaolin: 11 parts; desulfurized gypsum: 3.5 parts; polypropylene fiber (12mm): 1.5 parts; nano-SiO2 (30nm): 0.8 parts.

[0049] The preparation method of the above-mentioned sludge solidifying agent specifically comprises the following steps:

[0050] Step 1: Premix activation: industrial waste residue powder and nano-SiO2 are put into a 400r / min high-speed dry mixer and dry-mixed for 10 minutes to obtain a premixed material.

[0051] Step 2: Powder mixing: light-burned MgO, metakaolin and desulfurized gypsum were added to the premixed material and mixed for 7 minutes to obtain a mixed powder.

[0052] Step 3: Forming a curing agent: Add polypropylene fiber and MgCl2·6H2O pre-crushed to 3 mm into the mixed powder, and stir at 150 r / min for 4 minutes to obtain a finished curing agent.

[0053] The curing agent prepared in this example was used to solidify high-water sludge. Specifically, sludge with a water content of 60% was treated with the curing agent, at an amount of 11% of the sludge mass. The curing agent and sludge were initially mixed using a biaxial agitator at 45 rpm for 6 minutes. The mixture was further refined using a vortex agitator at 110 rpm for 4 minutes. Finally, the mixture was cured using a planetary agitator at 180 rpm for 3 minutes. The solidified sludge was then cured at 20°C and 95% humidity. Standard test specimens were then prepared from the solidified sludge.

[0054] Example 2

[0055] This embodiment provides a high-water content sludge solidifying agent based on industrial waste slag magnesium cementitious material, comprising the following components: light-burned MgO (active MgO 90%): 18 parts; MgCl2·6H2O: 14 parts; industrial waste slag powder (steel slag: fly ash = 1:1.5, specific surface area 600m 2 / kg): 48 parts; metakaolin: 10 parts; desulfurized gypsum: 3 parts; polypropylene fiber (10mm): 1 part; nano-SiO2 (25nm): 0.6 parts.

[0056] The preparation method of the above-mentioned sludge solidifying agent specifically comprises the following steps:

[0057] Step 1: Premix activation: industrial waste residue powder and nano-SiO2 are put into a 300r / min high-speed dry mixer and dry-mixed for 10 minutes to obtain a premixed material.

[0058] Step 2: Powder mixing: light-burned MgO, metakaolin and desulfurized gypsum are added to the premixed material and mixed for 5 minutes to obtain a mixed powder.

[0059] Step 3: Forming a curing agent: Add polypropylene fiber and MgCl2·6H2O pre-crushed to 3 mm into the mixed powder, and stir at 100 r / min for 3 minutes to obtain a finished curing agent.

[0060] The curing agent prepared in this example was used to solidify high-water sludge. Specifically, sludge with a water content of 70% was treated with the curing agent, at a concentration of 12% by mass. The sludge was then stirred using a biaxial agitator at 35 rpm for 8 minutes to initially mix the curing agent and sludge. The mixture was then further refined using a vortex agitator at 90 rpm for 5 minutes. Finally, the mixture was cured using a planetary agitator at 160 rpm for 4 minutes. The solidified sludge was then cured at 20°C and 95% humidity. Standard test specimens were then prepared from the solidified sludge.

[0061] Example 3

[0062] This embodiment provides a high-water content sludge solidifying agent based on industrial waste slag magnesium cementitious material, comprising the following components: light-burned MgO (active MgO 95%): 22 parts; MgCl2·6H2O: 18 parts; industrial waste slag powder (steel slag: fly ash = 1:1.5, specific surface area 550m 2 / kg): 42 parts; metakaolin: 12 parts; desulfurized gypsum: 4 parts; polypropylene fiber (8mm): 2 parts; nano-SiO2 (35nm): 1 part.

[0063] The preparation method of the above-mentioned sludge solidifying agent specifically comprises the following steps:

[0064] Step 1: Premix activation: industrial waste residue powder and nano-SiO2 are put into a 500r / min high-speed dry mixer and dry-mixed for 10 minutes to obtain a premixed material.

[0065] Step 2: Powder mixing: light-burned MgO, metakaolin and desulfurized gypsum are added to the premixed material and mixed for 8 minutes to obtain a mixed powder.

[0066] Step 3: Forming a curing agent: Add polypropylene fiber and MgCl2·6H2O pre-crushed to 3 mm into the mixed powder, and stir at 200 r / min for 5 minutes to obtain a finished curing agent.

[0067] The curing agent prepared in this example was used to solidify high-water sludge. Specifically, 10% of the sludge's mass was added to 30% water-content sludge. The sludge was then stirred using a biaxial agitator at 50 rpm for 5 minutes to initially mix the curing agent and sludge. The mixture was then further refined using a vortex agitator at 90 rpm for 3 minutes. Finally, the mixture was cured using a planetary agitator at 200 rpm for 2 minutes. The solidified sludge was then cured at 20°C and 95% humidity. Standard test specimens were then prepared from the solidified sludge.

[0068] Comparative Example 1

[0069] Grade 42.5 ordinary Portland cement was used as a comparative curing agent. It was applied to 60% moisture sludge at a concentration of 20% by mass. The sludge was then solidified using a single-shaft mixer at 80 rpm for 15 minutes. The solidified sludge was then cured at 20°C and 95% humidity. Standard test specimens were then prepared.

[0070] Comparative Example 2

[0071] This comparative example provides a sludge solidifying agent based on industrial waste magnesia gelling material. Compared with Example 1, the only difference is that no polypropylene fiber and nano-silica are added. The rest of the preparation method and application in sludge solidification are the same as Example 1 and will not be repeated here.

[0072] Standard specimens made from the solidified sludge of Examples 1-3 and Comparative Examples 1-2 were subjected to confined compressive strength tests (7d strength / 28d strength) and permeability tests, and their performance was analyzed. The cost of the curing agent required for curing per cubic meter of sludge was calculated based on the raw material costs of each component of the curing agent. The results are shown in Table 1.

[0073] Table 1 Performance comparison data analysis

[0074]

[0075] As can be known from the data in Table 1, the 7-day unconfined compressive strength of embodiment 1-3 is between 1.32-2.15MPa, and 28-day strength is between 2.51-3.82MPa.The 7-day and 28-day strengths of comparative example 1 (ordinary Portland cement) are respectively 0.85MPa and 1.72MPa, which is significantly lower than curing agent of the present invention, illustrating that curing agent of the present invention has a better gelling effect in high-water content sludge, can form strength faster and later-stage strength growth is obvious.The intensity of comparative example 2 (without polypropylene fiber and nano silicon) is lower than embodiment 1, shows that these two components have synergistic effect to strength promotion, and the micro-filling of nano silicon and chemical activation and the reinforcing effect of polypropylene fiber are indispensable.

[0076] The permeability coefficient of Examples 1-3 is 3.1×10 -7 -6.8×10 -7 cm / s, which are much lower than 1.2×10 -6 cm / s and 8.9×10 -7cm / s, indicating that the curing agent of the present invention significantly reduces the porosity of the sludge solidification body through multi-stage micro-aggregate filling (nanosilica, industrial waste residue powder, etc.), improves the density, and has better anti-permeability performance. Comparative Example 2, due to the lack of microscopic filling of nanosilica, has a higher permeability coefficient than Example 1, further verifying the key role of nanosilica in improving anti-permeability.

[0077] The cost of Examples 1-3 is 30-35 yuan / m 3 , much lower than the 55 yuan / m in comparative example 1 3 , and the cost of comparative example 2 is only 1 yuan / m higher than that of example 1 3 This shows that the present invention greatly reduces the raw material cost by using a large amount of industrial waste powder (accounting for ≥45%), and at the same time achieves a balance between low cost and high performance by adding a small amount of high-performance components (polypropylene fiber, nano-silica), with significant economic advantages.

[0078] Based on the performance characteristics of the samples prepared in Examples 1-3 and Comparative Examples 1-2, and in combination with the material durability test standard, water immersion, freeze-thaw, and dry-wet cycle tests were designed. The test data are shown in Table 2.

[0079] Table 2 Durability comparison data

[0080]

[0081]

[0082] It can be seen from the data in Table 2 that the compressive strength of Examples 1-3 after 7 days of immersion in water is 3.33-4.60MPa, and the strength retention rate is 81.5%-82.5%, showing good water stability. This is because the network structure formed by the hydration product of magnesium oxychloride cement and the stable gel phase generated by the multi-component gelling system can effectively resist water erosion. In contrast, the immersion strength retention rate of Comparative Example 1 (ordinary cement) is only 59.3%, and its hydration product is easily eroded by water, resulting in structural damage; the retention rate of Comparative Example 2 (without fiber and nano-silica) is 75.3%, which is lower than the embodiment, indicating that polypropylene fiber and nano-silica play an important role in maintaining structural integrity after immersion in water. The fiber inhibits crack expansion, and the nano-silica increases density and reduces water penetration paths.

[0083] After 25 freeze-thaw cycles, the strength loss rates of Examples 1-3 were between 9.0% and 12.0%, while those of Comparative Example 1 and Comparative Example 2 were 25.6% and 17.2%, respectively. The curing agent of the present invention enables the solidified body to better resist ice crystal expansion stress during freeze-thaw cycles through the rapid setting properties of magnesium oxychloride cement, the strength support of the multi-component gelling system, and the anti-cracking effect of the fiber. The micro-filling effect of nano-silica reduces macropores and reduces the risk of freeze-thaw damage. Comparative Example 1 suffers more severe freeze-thaw damage due to its porous cement stone structure and poor crack resistance; Comparative Example 2 lacks the synergistic effect of fiber and nano-silica, and its strength loss rate is higher than that of the examples, indicating that the two have a synergistic effect in improving freeze-thaw resistance.

[0084] After 10 dry-wet cycles, the strength loss rate of Examples 1-3 was between 14.6% and 16.3%, which was significantly lower than 33.1% of Comparative Example 1 and 21.4% of Comparative Example 2. The multi-component gelling system of the curing agent of the present invention can maintain a stable chemical structure during the dry-wet cycle. The calcium aluminate crystals generated by the desulfurized gypsum enhance the structural rigidity, while the polypropylene fibers inhibit the cracks caused by the dry-wet shrinkage-expansion cycle. Ordinary cement-cured sludge is prone to structural deterioration because its hydration products are not resistant to dry-wet alternation. Comparative Example 2 lacks fibers and nano-silica, so the cracks develop more obviously, resulting in increased strength loss. Overall, the curing agent of the present invention, through the synergistic effect of multiple components, has shown excellent stability and damage resistance in durability tests such as immersion in water, freeze-thaw, and dry-wet cycles, which is significantly better than traditional cement curing agents, and the addition of polypropylene fibers and nano-silica is crucial to improving durability.

[0085] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit the same. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solutions of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. An industrial waste residue solidifying agent, characterized in that: Calculated by weight, the invention comprises 18-22 parts of light-burned magnesium oxide, 14-18 parts of magnesium chloride hexahydrate, 42-48 parts of industrial waste residue powder, 10-12 parts of metakaolin, 3-4 parts of desulfurized gypsum, 1-2 parts of polypropylene fiber and 0.5-1 part of nano silicon dioxide.

2. An industrial waste residue solidifying agent according to claim 1, characterized in that: The active magnesium oxide content in light-burned magnesium oxide is ≥90%.

3. The industrial waste residue solidifying agent according to claim 1, characterized in that: The specific surface area of ​​industrial waste slag powder is ≥550m 2 / kg, including steel slag and fly ash, and the mass ratio of steel slag to fly ash is 1:1.

5.

4. The industrial waste residue solidifying agent according to claim 1, characterized in that: The particle size of nano-silica is 25-35nm.

5. The method for preparing an industrial waste residue solidifying agent according to any one of claims 1 to 4, characterized in that: The specific steps include: Step 1: Premix activation Putting industrial waste residue powder and nano-silicon dioxide into a high-speed dry mixer for dry mixing to obtain a premixed material; Step 2: Powder mixing Add light-burned magnesium oxide, metakaolin and desulfurized gypsum to the premixed material and continue mixing for 5-8 minutes to evenly disperse the components to obtain a mixed powder; Step 3: Forming a curing agent Add polypropylene fiber and pre-crushed magnesium chloride hexahydrate to the mixed powder, stir until the polypropylene fiber is evenly dispersed and the magnesium chloride hexahydrate is fully in contact with other components to obtain a finished curing agent.

6. The method for preparing an industrial waste residue solidifying agent according to claim 5, wherein: In step 1, the rotation speed of the high-speed dry mixer is 300-500 r / min, and the dry mixing time is 10 min.

7. The method for preparing an industrial waste residue solidifying agent according to claim 5, wherein: In step 3, the particle size of the pre-crushed magnesium chloride hexahydrate is less than 5 mm, the stirring speed is 100-200 r / min, and the stirring time is 3-5 min.

8. The use of an industrial waste solidifying agent according to any one of claims 1 to 4, characterized in that: The industrial waste residue solidifying agent is used for solidifying sludge with high water content.

9. The use of an industrial waste residue solidifying agent according to claim 8, characterized in that: The high-moisture sludge has a moisture content of 30-70%.

10. The use of an industrial waste residue solidifying agent according to claim 8, characterized in that: The specific operation of solidification applied to high-water-content sludge is as follows: adding the industrial waste residue solidifying agent into the high-water-content sludge, sequentially subjecting it to biaxial stirring, turbine stirring and planetary stirring, and then curing and forming to complete the sludge solidification.

Images