Soft soil curing agent based on industrial waste residues as well as preparation method and application of soft soil curing agent

Abstract

The invention discloses a soft soil curing agent based on industrial waste residues and a preparation method and application of the soft soil curing agent, and belongs to the technical field of soft soil curing agents. Waste residues generated by lithium batteries are subjected to material selection, water washing desalination and low-temperature roasting, pretreated lithium battery residues are obtained, and cobalt, nickel and manganese oxides contained in the pretreated lithium battery residues are added into the lithium battery residues; the red mud and the calcium carbide slag cooperate with the lithium slag and the cement clinker to rapidly generate gelatinization products such as hydrated calcium silicate and ettringite, the early strength of the curing agent is improved, the 7d compressive strength is larger than or equal to 3.5 MPa, the rapid reinforcing requirement of a soft soil foundation is met, aluminate components in the red mud can optimize the microstructure of a curing body and reduce compressibility, the calcium carbide slag provides an alkaline environment, dissolution of active components of all the raw materials is promoted, and the curing agent has a good curing effect. The compatibility of the curing agent and soft soil is enhanced, the adaptability of the curing agent is high, and powder or slurry products can be prepared by adjusting the water-material ratio.

Description

Technical Field

[0001] This invention belongs to the field of soft soil solidification agent technology, specifically relating to a soft soil solidification agent based on industrial waste residue, its preparation method, and its application. Background Technology

[0002] Soft soil stabilizers are functional materials that improve the physical and mechanical properties of soft soil. They mainly work through physical adsorption, chemical reactions (such as ion exchange and cementation), or physicochemical processes to reduce the water content of soft soil, enhance interparticle cohesion, and thus improve the strength, stability, and impermeability of soft soil, while reducing compressibility and settlement. These stabilizers come in various types and are widely used in engineering projects such as highways, railways, ports, and building foundation treatment. The appropriate stabilizer type and dosage can be selected based on the origin and composition of the soft soil (such as organic matter content and clay ratio) and engineering requirements to achieve rapid improvement and stabilization of soft soil foundations, meeting the engineering construction needs for foundation bearing capacity and durability.

[0003] Industrial waste residues, such as fly ash, slag, and steel slag, are byproducts of industrial production and exist in large quantities. Long-term stockpiling not only occupies land resources but also poses environmental risks. In recent years, the resource utilization of industrial waste residues in the building materials field has become a research hotspot. The active components contained in industrial waste residues, such as silicon, aluminum, and calcium, can undergo physicochemical reactions with moisture and clay minerals in soft soil under specific conditions, possessing the potential to be transformed into functional solidification materials. Chinese patent application CN105016661A provides a method for solidifying soft soil based on industrial waste residues, belonging to the field of soft soil reinforcement in civil engineering. It uses fly ash or limestone slag as a solidifying agent, mixing it with the soft soil and compacting it to achieve the effect of solidifying the soft soil. Although it can achieve "waste treatment with waste" by using industrial waste such as fly ash and lime slag, reducing the cost of solidifying agent raw materials, and the process operation (mixing and compaction) is simple and suitable for conventional soft soil reinforcement scenarios, it does not have specific adaptability for soft soil with high water content. The early strength improvement of soft soil after solidification is limited (usually 7-day unconfined compressive strength <0.8MPa). Furthermore, it does not involve the resource utilization of high-risk industrial waste such as lithium batteries, and cannot solve the problem of heavy metal and electrolyte pollution caused by the accumulation of lithium battery waste. At the same time, the solidifying agent has a single form (only suitable for dry mixing), which is difficult to meet the diverse construction needs such as wet spray grouting.

[0004] It is evident that a new type of environmentally friendly soft soil solidifying agent based on industrial waste is needed to solve the problems of difficult treatment of lithium battery industrial waste pollution, poor compatibility of solidifying agents with high water content soft soil, insufficient early strength, and single form that cannot be adapted to multiple construction processes. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a soft soil solidifying agent based on industrial waste residue, its preparation method and application, so as to solve the technical problems of high pollution risk of existing lithium battery industrial waste residue, poor compatibility of traditional solidifying agents with high water content soft soil, limited early strength improvement, and single product form that is difficult to meet the requirements of diversified construction processes.

[0006] To achieve the above objectives, the present invention employs the following technical solution: This invention discloses a method for preparing a soft soil stabilizing agent based on industrial waste residue, comprising: The waste residue generated from lithium batteries is pretreated by selecting materials, washing and desalting, and low-temperature roasting. 35%-45% of the pretreated lithium battery residue is then mixed with 15%-25% lithium slag, 20%-30% cement clinker, 5%-10% red mud, and 5%-10% calcium carbide slag by mass percentage to obtain a mixture. This mixture is then ball-milled to a specific surface area of ​​400-500 m². 2 / kg, to obtain a soft soil stabilizer based on industrial waste residue; The initial setting time of the soft soil solidifying agent based on industrial waste residue is ≥45min, the final setting time is ≤10h, and the 7d compressive strength is ≥3.5MPa.

[0007] Preferably, the selection conditions include: screening waste residue generated during the production and dismantling of lithium batteries, and removing metal scraps, plastic impurities and blocky particles with a particle size greater than 5 mm from the waste residue; The conditions for water washing and desalination include: soaking the selected lithium battery residue in deionized water with a liquid-to-solid ratio of 3:1-5:1, a soaking temperature of 25-35℃, a stirring rate of 100-150r / min, and a soaking time of 2-4h, during which the water is changed 2-3 times. The conditions for low-temperature roasting include: roasting the desalted lithium battery residue at 300-400℃ for 1-2 hours and then naturally cooling it to room temperature.

[0008] Preferably, the lithium slag is a byproduct of lithium extraction from lithium ore, with a moisture content of ≤5%; The cement clinker is P·O42.5 grade cement clinker with a free calcium oxide content of ≤1.5%; The red mud is Bayer process red mud from the aluminum industry, dried at 105℃ to constant weight; Calcium carbide slag is a byproduct of acetylene production, with a calcium hydroxide content of ≥85%.

[0009] Preferably, the particle size of lithium slag is 1-3 mm; the particle size of cement clinker is 1-3 mm; the particle size of red mud is 1-3 mm; and the particle size of calcium carbide slag is 1-3 mm.

[0010] Preferably, the mixing rate is 200-300 r / min and the mixing time is 15-20 min.

[0011] Preferably, the grinding media of the ball mill is alumina balls, the ball-to-material ratio is 8:1-10:1, and the grinding time is 2-3 hours.

[0012] Preferably, the grinding chamber temperature of the ball mill is ≤60℃.

[0013] Preferably, deionized water is added during the ball milling process, with a water-to-material ratio of 0.4:1 to 0.5:1. After stirring evenly, a slurry-like soft soil solidifying agent based on industrial waste residue is obtained.

[0014] The present invention discloses a soft soil solidifying agent based on industrial waste residue, which is prepared by the above-mentioned preparation method of soft soil solidifying agent based on industrial waste residue.

[0015] The soft soil solidifying agent based on industrial waste disclosed in this invention can be used in highway subgrade, foundation pit backfilling, dam seepage prevention, road base course and parking lot foundation.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention discloses a method for preparing a soft soil solidifying agent based on industrial waste residue. It involves compounding pretreated lithium battery slag, lithium slag, cement clinker, red mud, and carbide slag to achieve resource utilization of lithium battery waste residue and treat waste with waste. This not only reduces the solidifying agent's dependence on cement clinker but also co-processes multiple industrial solid wastes such as lithium slag, red mud, and carbide slag, resulting in significant environmental and economic benefits. The lithium battery slag undergoes pretreatment including material selection, water washing and desalination, and low-temperature roasting to avoid the use of strong acids and alkalis and reduce chemical reagent pollution. Pretreatment removes impurities and activates the material, laying the foundation for subsequent high performance. The mixture is ball-milled to a specific surface area of ​​400-500 m². 2 The specified strength ( / kg) ensures sufficient reactivity of the material for rapid hydration (supporting 7-day strength) while avoiding excessively fine particles that would lead to high processing energy consumption or a surge in water demand. Initial setting time ≥45 min and final setting time ≤10 h ensure sufficient time for mixing, transportation, and pouring, preventing excessively slow solidification—a prerequisite for the product's engineering applications. A 7-day compressive strength ≥3.5 MPa meets the requirements for rapid reinforcement of soft soil foundations. High early strength translates to shorter construction periods and faster load-bearing capacity, crucial for soft soil consolidation projects.

[0017] Furthermore, by selecting high-quality materials to remove large particles and impurities, the homogeneity of the raw materials and the stability of subsequent reactions are ensured. Water washing and desalination effectively remove soluble salts (such as Li and F), which could adversely affect subsequent hydration products or the soil environment; water exchange further enhances the desalination effect. Temperatures of 300-400℃ effectively decompose some residual organic matter, further remove water of crystallization, and enhance the activity of some amorphous substances, while avoiding the sintering deactivation of active components and the dramatic increase in energy consumption that can occur with high temperatures.

[0018] Furthermore, the low moisture content of lithium slag prevents agglomeration during grinding and storage, ensuring material flowability. The low free calcium oxide content of cement clinker prevents poor cement volume stability caused by excessive free calcium oxide. The high calcium hydroxide content of carbide slag ensures its role as a highly efficient alkaline activator, providing a stable and sufficient alkaline environment for the system. Furthermore, controlling the initial particle size of all raw materials to 1-3 mm is beneficial for achieving uniform distribution of each component during subsequent mixing and ball milling, avoiding uneven mixing or low ball milling efficiency caused by excessive differences in the initial particle size, thereby improving the homogeneity of the final product.

[0019] Furthermore, the mixing rate is 200-300 r / min, and the mixing time is 15-20 min, to ensure that the various solid waste raw materials can achieve preliminary macroscopic uniform mixing before entering the ball mill, creating favorable conditions for subsequent high-efficiency and high-quality fine ball milling and ensuring batch consistency of products.

[0020] Furthermore, the grinding media of the ball mill is alumina balls, the ball-to-material ratio is 8:1-10:1, and the grinding time is 2-3 hours; effectively balancing grinding efficiency, energy consumption and product fineness.

[0021] Furthermore, the grinding chamber temperature is ≤60℃ to prevent the material from sticking or undergoing unnecessary pre-hydration due to excessive temperature during the grinding process, which would affect the flowability and subsequent hydration activity of the powder and ensure the storage stability and performance of the product.

[0022] Furthermore, the curing agent has strong adaptability and can be prepared into powder or slurry products by adjusting the water-to-material ratio. These products are suitable for different construction processes such as dry mixing piles and wet jet grouting, thus meeting diverse engineering needs.

[0023] This invention discloses a soft soil solidification agent based on industrial waste residue. The components undergo a synergistic hydration reaction in an alkaline environment, rapidly forming a high-strength network structure. Calcium carbide slag quickly provides a strongly alkaline environment, stimulating the large-scale dissolution of active SiO2 and Al2O3 from lithium slag, red mud, and lithium battery slag. The dissolved silicon and aluminum ions react with Ca2+ produced during the hydration of cement clinker. 2+ And SO4 in red mud 2-Rapid reaction. Cement clinker dominates the formation of CSH gel; simultaneously, the abundant aluminum and calcium sources in the system promote the rapid and abundant formation of ettringite. The intertwined symbiosis of these two high-strength hydration products constitutes the framework of early strength. Cobalt, nickel, and manganese oxides in lithium battery slag act as micro-aggregate fillers and catalytic agents, further refining the pores and accelerating the hydration process, thereby enhancing early strength.

[0024] This invention discloses a soft soil solidifying agent based on industrial waste residue for use in highway subgrades and road base courses, requiring high load-bearing capacity. The solidifying agent, through a rapid synergistic hydration reaction induced by carbide slag, generates a large amount of high-strength hydrated calcium silicate (CSH) gel and needle-like ettringite in the early stages (7 days). These two products interweave and intersect, forming a dense three-dimensional network skeleton that effectively transfers and disperses stress from the pavement, providing sufficient compressive and shear strength (28-day strength reaches 5.9-6.5 MPa) for the subgrade and base courses, preventing rutting and structural subsidence. The cementing system forms a highly stable structure, and the transition metal oxides in the lithium battery slag may act as micro-fillers and reinforcements, making the structure denser and reducing porosity, thereby improving resistance to wet-dry cycles and freeze-thaw cycles, meeting the long-term service requirements of road engineering. When using industrial waste-based soft soil solidifiers for foundation pit backfilling, rapid achievement of design strength, settlement control, and convenient construction are required. The solidifier's rapid early strength development (7d ≥ 3.5MPa) significantly shortens the curing time after backfilling and accelerates subsequent construction, which is crucial for projects with tight schedules. After reacting with soft soil, the solidifier consumes free water through hydration and generates cementing products that encapsulate and bind soil particles, greatly improving the soil's integrity and modulus. This effectively reduces later compression settlement of the backfill soil, preventing adverse effects on the foundation pit support structure or surrounding buildings. The solidifier is formulated as a slurry, suitable for grouting or spraying backfilling in narrow foundation pits, ensuring density and uniformity. For dam seepage control, good impermeability and stability are required. The introduction of red mud, rich in aluminum and iron, contributes to the formation of more complex cementing products after reaction, further filling and refining pores and optimizing pore size distribution. The generated gel and ettringite network effectively block seepage channels in the soil, significantly reducing the permeability coefficient of the solidified soil. The strong alkaline environment and dense structure of the solidifying agent not only stabilize the heavy metal ions contained in lithium battery slag, preventing them from leaching and polluting water bodies, but also, to a certain extent, seal off potentially harmful substances in soft soil, acting as a dual environmental barrier. The overall improvement in soil strength after solidification enhances the anti-sliding stability of embankment slopes and the integrity of the dam body. When using industrial waste-based soft soil solidifying agents for parking lot foundations, uniform load-bearing capacity, resistance to localized settlement, and high surface smoothness are required. Through dry mixing or wet grouting, the solidifying agent can uniformly mix or penetrate with the soft soil foundation, forming a composite foundation with good integrity. Its high-strength cementitious network ensures uniform load distribution, avoiding localized plastic deformation caused by long-term vehicle parking. The uniformity and stability of the soil improvement by the solidifying agent ensure that the parking lot surface is flat and free from cracks or misalignments. Attached Figure Description

[0025] Figure 1 This is a flowchart illustrating the preparation process of the soft soil solidification agent based on industrial waste residue disclosed in this invention. Detailed Implementation

[0026] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Unless otherwise specified, all embodiments and preferred embodiments mentioned herein can be combined to form new technical solutions.

[0028] Unless otherwise specified, all the technical features and preferred features mentioned herein can be combined to form new technical solutions.

[0029] In this invention, unless otherwise specified, percentage (%) or parts refer to weight percentage or parts relative to the composition.

[0030] Unless otherwise specified, the components or preferred components involved in this invention can be combined with each other to form new technical solutions.

[0031] In this invention, unless otherwise specified, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "6~22" indicates that all real numbers between "6~22" have been listed in this document, and "6~22" is simply a shortened representation of these numerical combinations.

[0032] The "scope" disclosed in this invention can be in the form of a lower limit and an upper limit, and can be one or more lower limits and one or more upper limits, respectively.

[0033] In this invention, the term "and / or" as used herein refers to any combination of one or more of the associated listed items, as well as all possible combinations, and includes such combinations.

[0034] In this invention, unless otherwise stated, the various reactions or operation steps may be performed sequentially or in a particular order. Preferably, the reaction methods described herein are performed sequentially.

[0035] Unless otherwise stated, the technical and scientific terms used herein have the same meanings as those familiar to those skilled in the art. Furthermore, any methods or materials similar to or equivalent to those described herein may also be used in this invention.

[0036] This invention provides a soft soil solidification agent based on industrial waste residue, comprising: 35%-45% pretreated lithium battery slag, 15%-25% lithium slag, 20%-30% cement clinker, 5%-10% red mud, and 5%-10% calcium carbide slag. The pretreated lithium battery slag is prepared through the following steps: S1: Material selection, screening waste residue generated during lithium battery production and dismantling, removing metal scraps, plastic impurities and lumpy particles with a diameter greater than 5mm from the waste residue; S2: Water washing and desalination. The selected lithium battery residue is soaked in deionized water with a liquid-to-solid ratio of 3:1-5:1, a soaking temperature of 25-35℃, a stirring rate of 100-150r / min, and a soaking time of 2-4h. The water is changed 2-3 times during the process to remove residual electrolyte salts such as lithium hexafluorophosphate from the waste residue. S3: Low-temperature roasting. The washed lithium battery residue is placed in a roasting furnace and roasted at 300-400℃ for 1-2 hours to remove organic binders and carbon powder from the residue, while activating the activity of metal oxides in the residue. After roasting, it is naturally cooled to room temperature to obtain pretreated lithium battery residue.

[0037] Preferably, the lithium slag is a byproduct of lithium extraction from lithium ore, with a moisture content ≤5%; the cement clinker is P O42.5 grade cement clinker with free calcium oxide content ≤1.5%; red mud is Bayer process red mud from the aluminum industry, dried to constant weight at 105℃; calcium carbide slag is a by-product of acetylene production with calcium hydroxide content ≥85%.

[0038] A method for preparing an environmentally friendly soft soil stabilizer Includes the following steps: Step 1: Raw material crushing. Lithium slag, cement clinker, red mud, and carbide slag are respectively fed into a jaw crusher for crushing. The particle size after crushing is controlled to be 1-3mm. Step 2: Mixing and batching. According to the formula ratio of claim 1, the pretreated lithium battery slag, crushed lithium slag, cement clinker, red mud, and carbide slag are put into a twin-screw mixer. The mixing rate is 200-300 r / min and the mixing time is 15-20 min to obtain the mixture. Step 3: Grinding and refining. The mixture is fed into a ball mill with alumina balls as the grinding media. The ball-to-material ratio is 8:1-10:1, and the grinding time is 2-3 hours. The specific surface area of ​​the material after grinding is controlled at 400-500 m². 2 / kg, to obtain the finished soft soil stabilizer; Step 4: Finished product testing. Test the initial setting time, final setting time, and 7-day compressive strength of the finished product. The initial setting time should be ≥45 min, the final setting time ≤10 h, and the 7-day compressive strength ≥3.5 MPa. After passing the test, the finished product is packaged.

[0039] Preferably, during the ball mill grinding process in step three, the grinding chamber temperature is controlled to be ≤60℃ to avoid the material activity being reduced due to high temperature.

[0040] Preferably, if a slurry-like curing agent is to be prepared, deionized water can be added to the material after grinding in step three, with a water-to-material ratio of 0.4:1-0.5:1, and the slurry-like curing agent can be obtained after stirring evenly.

[0041] Figure 1 This is a flowchart illustrating the preparation process of a soft soil solidification agent based on industrial waste slag disclosed in this invention. As shown in the flowchart, this invention uses lithium battery slag as the core raw material and follows a linear process route of pretreatment, crushing, mixing, grinding, and testing, reflecting the concept of resource utilization of industrial waste slag. Before mixing, particle size control is performed on various raw materials, including lithium slag, cement clinker, red mud, and carbide slag, to ensure the uniformity of the initial materials, laying the foundation for efficient mixing and reaction. The mixture is refined to a specific surface area of ​​400-500 m² using ball milling. 2 / kg, initial setting time ≥45min, final setting time ≤10h, 7d compressive strength ≥3.5MPa.

[0042] The beneficial effects achieved by this invention compared with the prior art include: First, this invention uses lithium battery industrial waste residue as the core raw material to replace part of the cement clinker, realizing the resource utilization of lithium battery waste residue, reducing the solid waste storage area and pollution risk. The pretreatment process adopts water washing and desalination + low-temperature roasting, avoiding the use of strong acids and alkalis, reducing chemical reagent pollution, and the water washing wastewater can be reused after sedimentation and filtration. The roasting temperature is only 300-400℃, which reduces energy consumption compared with traditional high-temperature roasting (above 600℃). The red mud and calcium carbide slag in the formula are both industrial by-products, further realizing "waste treatment with waste", reducing the consumption of natural resources and meeting environmental protection requirements.

[0043] Secondly, the cobalt, nickel, and manganese oxides contained in the pretreated lithium battery slag of this invention, in synergy with lithium slag and cement clinker, can rapidly generate cementitious products such as hydrated calcium silicate and ettringite, improving the early strength of the curing agent. The 7-day compressive strength is ≥3.5MPa, meeting the needs of rapid reinforcement of soft soil foundations. The aluminate components in the red mud can optimize the microstructure of the solidified body and reduce compressibility. The carbide slag provides an alkaline environment, promoting the dissolution of active components of various raw materials and enhancing the compatibility between the curing agent and soft soil. The curing agent has strong adaptability and can be prepared into powder or slurry products by adjusting the water-material ratio, which are suitable for different construction processes such as dry mixing piles and wet jet grouting, meeting diverse engineering needs.

[0044] Third, the lithium battery slag, lithium slag, red mud and calcium carbide slag in the formula of this invention are all industrial waste residues, with low procurement costs and lower raw material costs compared to traditional cement-based curing agents. The preparation process does not require complex equipment, and crushing, mixing and grinding are all conventional processes, making it easy to industrialize.

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0046] Example 1 Powder solidifier suitable for soft soil with medium moisture content (35%) Lithium battery slag pretreatment Raw material source: Waste residue generated during the production of cathode material (ternary NCM523) in a lithium battery factory. The main components are: 8.5% cobalt oxide, 12.3% nickel oxide, 6.2% manganese oxide, 5.1% lithium carbonate, 3.2% organic binder (PVDF), and the remainder are inert impurities.

[0047] Material selection process: A double-layer vibrating screen (5mm mesh size on the upper layer and 1mm mesh size on the lower layer) is used to remove lumpy impurities (such as unreacted lithium salt agglomerates) and metal fragments with a particle size >5mm, and to collect waste residue with a particle size range of 1-5mm. The screening recovery rate reaches 82%.

[0048] Water washing and desalination parameters: The screened waste residue was put into a mixing tank, and deionized water (conductivity ≤5μS / cm) was added at a liquid-to-solid ratio of 4:1. The temperature was controlled at 30℃, and the mixture was continuously stirred at a stirring rate of 120r / min. After standing for 10min every 1 hour, the deionized water was replaced, and the water was changed twice in total. After water washing, the fluoride ion content in the waste residue was tested and decreased from the initial 1.8% to 0.12%, which met the environmental protection requirements (GB15562.2-1995 "Environmental Protection Graphic Symbols - Solid Waste Storage (Disposal) Sites").

[0049] Curing agent preparation process The formula is precisely proportioned as follows: 40% pretreated lithium battery slag, 20% lithium slag (taken from a lithium salt plant, with Li2O content of 2.1% and moisture content of 4.2%), 25% P·O42.5 cement clinker (free CaO content of 1.2%), 8% Bayer process red mud (Al2O3 content of 18.5%, moisture content of 3.8% after drying at 105℃), and 7% calcium carbide slag (Ca(OH)2 content of 88%). The composition of each raw material is detected by X-ray fluorescence spectroscopy (XRF) to ensure the accuracy of the proportions.

[0050] Crushing process: Lithium slag, cement clinker, red mud, and carbide slag are fed into a jaw crusher for crushing. After crushing, a laser particle size analyzer is used to detect the particle size distribution to ensure that more than 90% of the particles are ≤2mm in size, so as to avoid large particles from affecting the uniformity of subsequent mixing.

[0051] Mixing process: The pretreated lithium battery residue and other crushed raw materials are put into a twin-screw mixer. The mixing rate is set to 250 r / min and the mixing time is 18 min. During the mixing process, samples are taken every 5 min for testing. The color difference of the mixture is detected by a colorimeter to ensure that the color difference ΔE ≤ 1.5, which is considered to be uniform mixing.

[0052] Grinding optimization: The mixed materials were fed into a planetary ball mill with Φ10mm alumina balls as the grinding media, a ball-to-material ratio of 9:1, a grinding speed of 300 r / min, and a grinding time of 2.5 h. During the grinding process, cooling water was circulated through the jacket to control the grinding chamber temperature to ≤55℃, preventing high temperature from causing cement clinker hydration. After grinding, the specific surface area was measured using a specific surface area meter, and the specific surface area reached 450 m². 2 / kg, particle size distribution D50=15μm, which meets the requirements of finished product.

[0053] Performance testing and engineering application verification The curing agent's own performance: According to the "Test Method for Standard Consistency Water Requirement, Setting Time and Soundness of Cement" (GB / T1346-2011), the initial setting time is 55 min, the final setting time is 8.5 h, and the soundness is qualified (the difference in the Le Chatelier test is ≤1.5 mm); according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T17671-1999), the 7-day compressive strength is 3.8 MPa, and the 28-day compressive strength is 6.2 MPa.

[0054] Soft soil solidification effect: A soft soil sample with a moisture content of 35% was taken, and the solidifying agent of this embodiment was added at a dosage of 10% of the soft soil mass. The mixture was stirred for 3 minutes with a small mixer (500 r / min) until homogeneous, and Φ50mm×100mm unconfined compressive strength specimens were prepared. After standard curing (temperature 20±2℃, relative humidity ≥95%) for 7 days, the unconfined compressive strength reached 1.2MPa, which is 7 times higher than that of untreated soft soil (0.15MPa). After curing for 28 days, the compression modulus E was tested.s1-2 It reaches 8.5MPa, which meets the strength requirements of subgrade fill material for Class II highways (≥0.8MPa) in the "Specifications for Design of Highway Subgrade" (JTGD30-2015).

[0055] Environmental performance testing: The leachate of the solidified soft soil was tested according to the "Leaching Toxicity Method for Solid Waste - Horizontal Oscillation Method" (HJ557-2010). The concentrations of cobalt, nickel, and manganese ions were 0.02 mg / L, 0.03 mg / L, and 0.01 mg / L, respectively, all of which are lower than the Class III groundwater limits in the "Groundwater Quality Standard" (GB / T14848-2017) (cobalt ≤ 1.0 mg / L, nickel ≤ 0.02 mg / L; the nickel concentration was slightly higher here, but it was reduced to 0.018 mg / L after adjusting the roasting temperature to 380℃). There is no risk of heavy metal pollution.

[0056] Example 2 Grout solidification agent suitable for soft soil with high water content (40%) Lithium battery slag pretreatment Raw material source: Electrode waste residue from a waste lithium battery dismantling plant was selected. The main components are: 15.2% graphite carbon powder, 5.8% cobalt oxide, 9.3% nickel oxide, 4.5% lithium hexafluorophosphate residue, and 3.1% aluminum foil fragments.

[0057] Material selection process: First, a magnetic separator (magnetic field strength 12000Gs) is used to remove aluminum foil debris, and then a vibrating screen with a 3mm aperture is used to screen and collect waste residue with a particle size ≤3mm. The screening recovery rate is 78%.

[0058] Water washing and desalination enhancement: Add deionized water at a liquid-to-solid ratio of 5:1, stir at 150 r / min at 35℃, change the water every 40 min, and change the water 3 times in total; after water washing, the fluoride ion content was reduced to 0.08%, and the carbon powder residue was 8.5% (which can be removed by subsequent calcination).

[0059] Low-temperature calcination optimization: heating rate 6℃ / min, holding at 400℃ for 1h, and introducing air (flow rate 1L / min) to promote carbon powder combustion; after calcination, the residual carbon powder content is <0.5%, and the specific surface area of ​​the waste residue reaches 320m². 2 / kg.

[0060] Preparation of curing agent and slurry modulation Formula: 45% pretreated lithium battery slag, 15% lithium slag (Li2O content 1.8%, moisture content 4.8%), 20% cement clinker (free CaO content 1.4%), 10% red mud (Al2O3 content 17.2%), and 10% carbide slag (Ca(OH)2 content 86%).

[0061] Crushing and mixing: After crushing, the particle size is ≤1mm. The mixture is stirred at 300r / min for 15min in a double spiral mixer, and the mixing uniformity ΔE is ≤1.2.

[0062] Grinding: Ball-to-material ratio 10:1, grinding for 2 hours, specific surface area 480m² 2 / kg, particle size D50=12μm.

[0063] Slurry preparation: Add deionized water to the ground powder at a water-to-material ratio of 0.45:1, and stir for 5 minutes using a high-speed disperser (2000 r / min) to prepare a slurry curing agent; the viscosity of the slurry (rotational viscometer, 25℃) is 800 mPa·s, with good fluidity and no stratification, meeting the requirements for wet jet grouting construction (viscosity 500-1500 mPa·s).

[0064] Performance testing and application results Performance of slurry curing agent: initial setting time 48 min, final setting time 9.2 h; 7-day compressive strength 3.6 MPa, 28-day compressive strength 5.9 MPa.

[0065] Soft soil solidification effect: Soft soil with a moisture content of 40% was mixed with a slurry solidifying agent at a dosage of 12% of the soft soil mass. After thorough mixing, specimens were prepared. The unconfined compressive strength was 1.0 MPa at 7 days and reached 1.8 MPa at 28 days. The permeability coefficient of the solidified soft soil (variable head method) was measured from an initial 1×10⁻⁶. -6 cm / s decreased to 5×10 -8 With a speed of cm / s, its impermeability is significantly improved, making it suitable for engineering scenarios such as foundation pit backfilling and dam seepage prevention.

[0066] Construction compatibility: A small jet grouting machine (working pressure 0.8MPa) is used to spray the grout curing agent. There is no clogging within a 3m spraying distance, and the grout and soft soil are mixed with a uniformity of over 90%.

[0067] Example 3 Low-cost powder solidifier suitable for soft soil with low moisture content (32%) Lithium battery slag pretreatment Raw material source: Mixed waste residue (production + dismantling) from a lithium battery factory, the main components of which are: manganese oxide 7.5%, nickel oxide 8.2%, lithium salt residue 3.1%, and impurities 12.3%.

[0068] Material selection process: Direct screening is performed using a 5mm aperture sieve, eliminating the need for magnetic separation (metal impurity content <1%), achieving a screening recovery rate of 85% and reducing pretreatment costs.

[0069] Water washing and desalination: liquid-to-solid ratio 3:1, stirring at 100 r / min for 4 hours at 25℃, water changed twice; fluoride ion content reduced to 0.15%, meeting basic environmental protection requirements.

[0070] Low-temperature calcination: 300℃ for 2 hours, followed by natural heating (no temperature control required), resulting in 30% lower energy consumption compared to Example 1; the specific surface area after calcination is 290 m². 2 / kg.

[0071] Curing agent preparation Formula: 35% pretreated lithium battery slag, 25% lithium slag (Li2O content 1.5%, moisture content 5%), 30% cement clinker (free CaO content 1.3%), 5% red mud (Al2O3 content 16.8%), and 5% carbide slag (Ca(OH)2 content 84%). The increased proportion of cement clinker compensates for the insufficient activity of waste residue caused by simplified pretreatment.

[0072] Crushing and mixing: After crushing, the particle size is ≤3mm. The mixture is stirred at 200r / min for 20min in a double spiral mixer. The mixing uniformity ΔE is ≤1.8.

[0073] Grinding: Ball-to-material ratio 8:1, grinding for 3 hours, specific surface area 420m² 2 / kg, particle size D50=18μm.

[0074] Performance testing and cost analysis Curing agent performance: initial setting time 62 min, final setting time 9.8 h; 7-day compressive strength 3.5 MPa, 28-day compressive strength 6.5 MPa, meeting engineering requirements.

[0075] Soft soil solidification effect: With a soft soil moisture content of 32% and a solidifying agent dosage of 8%, the unconfined compressive strength is 1.3MPa at 7 days and reaches 2.1MPa at 28 days. It is suitable for road base courses, parking lot foundations and other scenarios with high strength requirements.

[0076] Cost advantages: The pretreatment ring saves the steps of demagnetization and temperature control, and the proportion of low-cost waste residue (lithium slag, red mud) in the raw materials reaches 35%, reducing the overall raw material cost by 18% compared with Example 1 and by 32% compared with traditional cement-based curing agents (pure cement), which has the potential for large-scale promotion.

[0077] Example 4 Endpoint parameter verification type grout solidifier suitable for soft soil with medium to high moisture content (38% moisture content) Lithium battery slag pretreatment Raw material source: Waste residue (ternary NCM811) from a lithium battery factory was selected. The main components are: cobalt oxide 6.3%, nickel oxide 8.5%, manganese oxide 2.1%, lithium salt residue 4.8%, and aluminum foil fragments 2.5%.

[0078] Material selection process: A magnetic separator (magnetic field strength 11000Gs) removes aluminum foil debris, and a 5mm aperture vibrating screen is used to screen and collect waste residue with a particle size ≤5mm, with a recovery rate of 80%.

[0079] Water washing and desalination: liquid-solid ratio 4:1, 32℃, stirring rate 130r / min, soaking time 3h, water changed 2 times; after water washing, the fluoride ion content was reduced to 0.10%.

[0080] Low-temperature calcination: calcined at 350℃ for 1.5 hours, then naturally cooled; the specific surface area after calcination is 350 m². 2 / kg.

[0081] Preparation of curing agent and slurry modulation Formula: 42% pretreated lithium battery slag, 18% lithium slag (Li2O content 2.0%, moisture content 4.5%), 26% cement clinker (P·O 42.5 grade, free CaO content 1.5%), 7% red mud (Bayer process, dried at 105℃, Al2O3 content 17.8%), and 7% carbide slag (Ca(OH)2 content 85%).

[0082] Crushing and mixing: All raw materials are crushed to a particle size of 2mm, and stirred in a twin-screw mixer at 260r / min for 17min. The mixing uniformity ΔE ≤ 1.4.

[0083] Grinding: The grinding media was alumina balls, with a ball-to-material ratio of 9:1. The grinding time was 2.2 hours, and the grinding chamber temperature was controlled between 58℃ and 60℃. The specific surface area after grinding was 500 m². 2 / kg, particle size D50=10μm.

[0084] Slurry preparation: Add deionized water at a water-to-material ratio of 0.4:1, and stir at 1800 r / min for 4 min using a high-speed disperser to prepare the slurry; the slurry viscosity is tested to be 650 mPa·s, which meets the requirements for spraying construction.

[0085] Performance testing and application results Curing agent performance: initial setting time 45 min, final setting time 10 h; 7-day compressive strength 3.7 MPa ≥ 3.5 MPa, 28-day compressive strength 6.0 MPa.

[0086] Soft soil stabilization effect: Soft soil with a moisture content of 38% was mixed with 11% stabilizing agent and molded. After standard curing for 7 days, the unconfined compressive strength was 1.1 MPa, and after 28 days it reached 1.6 MPa; the permeability coefficient decreased to 8 × 10⁻⁶. -8 cm / s, suitable for auxiliary engineering of dam seepage prevention.

[0087] Construction compatibility: The jet grouting machine operates at a pressure of 0.7 MPa, with a jetting distance of 2.5 m without clogging, and a mixing uniformity of 92%.

[0088] Example 5 Endpoint parameter verification type powder solidifier suitable for soft soil with medium to low moisture content (33% moisture content) Lithium battery slag pretreatment Raw material source: waste residue (lithium iron phosphate cathode) from a lithium battery factory. The main components are: 6.2% residual lithium iron phosphate, 2.8% organic binder, and 10.5% inert impurities.

[0089] Material selection process: Double-layer vibrating screen (5mm upper layer, 2mm lower layer) is used to remove large impurities and collect 2-5mm waste residue, with a recovery rate of 83%.

[0090] Water washing and desalination: liquid-to-solid ratio 4:1, 30℃, stirring speed 125r / min, soaking time 3.5h, water changed 3 times; after water washing, the fluoride ion content was reduced to 0.09%.

[0091] Low-temperature calcination: calcined at 360℃ for 1.6 hours, then naturally cooled; the specific surface area after calcination is 340 m². 2 / kg.

[0092] Curing agent preparation Formula: 38% pretreated lithium battery slag, 22% lithium slag (Li2O content 1.7%, moisture content 4.3%), 24% cement clinker (P·O 42.5 grade, free CaO content 1.3%), 8% red mud (Bayer process, dried at 105℃, Al2O3 content 18.2%), and 8% carbide slag (Ca(OH)2 content 87%).

[0093] Crushing and mixing: All raw materials are crushed to a particle size of 2.5 mm, and stirred in a twin-screw mixer at 240 r / min for 19 min. The mixing uniformity ΔE ≤ 1.6.

[0094] Grinding: The grinding media was alumina balls, with a ball-to-material ratio of 9:1. The grinding time was 2.8 hours, and the grinding chamber temperature was controlled at 55℃. The specific surface area after grinding was 400 m². 2 / kg, particle size D50=20μm.

[0095] Performance testing and application results Curing agent performance: initial setting time 50 min, final setting time 9.5 h; 7-day compressive strength 3.6 MPa, 28-day compressive strength 6.3 MPa.

[0096] Soft soil stabilization effect: Soft soil with a moisture content of 33% was mixed with a 9% stabilizing agent, and molded into specimens. After standard curing for 7 days, the unconfined compressive strength was 1.2 MPa, and after 28 days it reached 1.9 MPa; the compression modulus E... s1-2 It reaches 9.0MPa, which meets the requirements for road base construction.

[0097] A separate slurry sample was prepared with a water-to-material ratio of 0.5:1 and a slurry viscosity of 1400 mPa·s. The slurry exhibited good fluidity and no stratification, meeting the requirements for wet construction.

[0098] Table 1. Performance comparison of soft soil stabilizing agents based on industrial waste prepared in Examples 1, 2, and 3.

[0099] Table 1 compares the performance of the soft soil solidification agents based on industrial waste obtained in Examples 1, 2, and 3. As can be seen from the table, the 7-day compressive strength of the solidification agents in all three examples is ≥3.5 MPa, which improves early strength and meets the requirements for rapid reinforcement. The 28-day compressive strength reaches approximately 6.0 MPa, indicating not only rapid early strength development but also continuous strength growth in later stages, providing long-term stable bearing capacity for various engineering projects. The 7-day unconfined compressive strength of the soft soil reaches 1.2 MPa, 1.0 MPa, and 1.3 MPa respectively, significantly improving the strength of the soft soil after practical application. Even when the soft soil moisture content is as high as 40% (Example 2), the improved strength still reaches 1.0 MPa, demonstrating good compatibility and reinforcement effect for soft soil with high moisture content. Powder form (Examples 1 and 3): Suitable for secondary highway subgrades, road base courses, and parking lot foundations. These scenarios typically involve large areas, making dry mixing construction more efficient and economical. Slurry form (Example 2): Specifically used for foundation pit backfilling and dam seepage prevention. In such scenarios, where space may be limited or there are special requirements for uniformity and seepage prevention, wet spraying or pressure grouting can better ensure construction quality. The relative cost of pretreatment is based on Example 1 (1.0). Example 2 has a slightly higher cost due to enhanced water washing and calcination temperature control; Example 3 has a significantly lower cost due to simplified pretreatment steps.

[0100] In summary, this invention discloses a soft soil solidifying agent based on industrial waste residue, its preparation method, and its application, comprising: 35%-45% pretreated lithium battery slag, 15%-25% lithium slag, 20%-30% cement clinker, 5%-10% red mud, and 5%-10% carbide slag. This novel environmentally friendly soft soil solidifying agent based on industrial waste residue contains cobalt, nickel, and manganese oxides in the pretreated lithium battery slag, which synergistically react with lithium slag and cement clinker to rapidly generate cementitious products such as hydrated calcium silicate and ettringite, improving the early strength of the solidifying agent. The 7-day compressive strength is ≥3.5 MPa, meeting the requirements for rapid reinforcement of soft soil foundations. The aluminate components in the red mud optimize the microstructure of the solidified body and reduce compressibility. The carbide slag provides an alkaline environment, promoting the dissolution of active components from each raw material and enhancing the compatibility between the solidifying agent and soft soil. The solidifying agent has strong adaptability and can be prepared into powder or slurry products by adjusting the water-to-material ratio.

[0101] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a soft soil stabilizing agent based on industrial waste residue, characterized in that, include: The waste residue generated from lithium batteries is pretreated by selecting materials, washing and desalting, and low-temperature roasting. 35%-45% of the pretreated lithium battery residue is then mixed with 15%-25% lithium slag, 20%-30% cement clinker, 5%-10% red mud, and 5%-10% calcium carbide slag by mass percentage to obtain a mixture. This mixture is then ball-milled to a specific surface area of ​​400-500 m². 2 / kg, to obtain a soft soil stabilizer based on industrial waste residue; The initial setting time of the soft soil solidifying agent based on industrial waste residue is ≥45min, the final setting time is ≤10h, and the 7d compressive strength is ≥3.5MPa.

2. The preparation method of the soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, The selection criteria include: screening waste residue generated during lithium battery production and dismantling, and removing metal debris, plastic impurities and blocky particles with a particle size greater than 5 mm from the waste residue. The conditions for water washing and desalination include: soaking the selected lithium battery residue in deionized water with a liquid-to-solid ratio of 3:1-5:1, a soaking temperature of 25-35℃, a stirring rate of 100-150r / min, and a soaking time of 2-4h, during which the water is changed 2-3 times. The conditions for low-temperature roasting include: roasting the desalted lithium battery residue at 300-400℃ for 1-2 hours and then naturally cooling it to room temperature.

3. The preparation method of the soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, The lithium slag is a byproduct of lithium extraction from lithium ore, with a moisture content of ≤5%. The cement clinker is P·O42.5 grade cement clinker with a free calcium oxide content of ≤1.5%; The red mud is Bayer process red mud from the aluminum industry, dried to constant weight at 105°C; The calcium carbide slag is a byproduct of acetylene production, with a calcium hydroxide content of ≥85%.

4. The preparation method of the soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, The lithium slag has a particle size of 1-3 mm; the cement clinker has a particle size of 1-3 mm; the red mud has a particle size of 1-3 mm; and the carbide slag has a particle size of 1-3 mm.

5. The preparation method of the soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, The mixing rate is 200-300 r / min, and the mixing time is 15-20 min.

6. The method for preparing a soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, The grinding media of the ball mill is alumina balls, the ball-to-material ratio is 8:1-10:1, and the grinding time is 2-3 hours.

7. The method for preparing a soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, The grinding chamber temperature of the ball mill is ≤60℃.

8. The method for preparing a soft soil stabilizing agent based on industrial waste residue according to claim 1, characterized in that, Deionized water is added during the ball milling process, with a water-to-material ratio of 0.4:1-0.5:

1. After stirring evenly, a slurry-like soft soil solidifying agent based on industrial waste residue is obtained.

9. A soft soil stabilizing agent based on industrial waste residue, characterized in that, It is prepared by the method of any one of claims 1-8 for preparing soft soil solidifying agent based on industrial waste residue.

10. The application of the soft soil solidifying agent based on industrial waste obtained by the preparation method of the soft soil solidifying agent based on industrial waste as described in any one of claims 1-8 in highway subgrade, foundation pit backfill, dam seepage prevention, road base course and parking lot foundation.

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