Preparation method of solidified agent based on full solid waste saline soil

Abstract

The application provides a preparation method of a solidifying agent based on a full-solid waste saline soil, which comprises the following steps: respectively measuring the content of SO4 2‑ and Cl ‑ in saline soil and mixture A, respectively calculating the mixing amount of mixture A and mixture B in the saline soil, obtaining the mass of required alkali residue and carbide slag according to the mixing ratio of mixture A and mixture B in the saline soil, respectively adding mixture A, mixture B and water into a stirring machine to obtain a solidifying agent of solidified saline soil by stirring, and respectively adding the solidifying agent and the saline soil into a stirring machine container to obtain solidified saline soil. The solidifying agent formed by the synergistic excitation system of salt-alkali is used to excite slag and steel slag, so that the saline soil is reinforced, and the saline soil has higher strength when the mixing amount of the solidifying agent accounts for 25% to 35% of the mass of the saline soil.

Description

Technical Field

[0001] This invention relates to the field of building materials, and in particular to a method for preparing a solidifying agent based on solid waste saline soil. Background Technology

[0002] Saline soils contain a large amount of readily soluble salts, such as chlorides, sodium sulfate, and magnesium sulfate; they also contain moderately soluble salts, mainly calcium sulfate; and sparingly soluble salts, mainly calcium carbonate. The SO42- produced by the dissolution of readily soluble and moderately soluble salts... 2- It possesses strong oxidizing properties, which allows it to react with certain inorganic ions in the environment, leading to the formation of toxic and harmful byproducts. The high concentration of Cl- produced by the dissolution of easily soluble salts is also a result. - It inhibits plant root growth and interferes with the absorption and transport of other elements within the plant, ultimately leading to plant death. Therefore, feasible treatment and utilization technologies for saline soil are urgently needed.

[0003] Solidifying agents are inorganic hydraulic cementitious materials used to solidify soft soils and other fine-grained soils. After thorough mixing with soil, through physical and chemical reactions between their components and with the soil, they can significantly improve the physical and mechanical properties of the soil and form a solidified body that meets environmental standards and maintains long-term stability. Traditional solidifying agents mainly utilize cement as a cementing material. However, the annual discharge of phosphogypsum, carbide slag, alkali slag, and alkaline solid waste exceeds 4 million tons. Due to their high salt and alkali content and numerous harmful components, their utilization is difficult, with a resource utilization rate of less than 20%. There is an urgent need to develop large-scale, high-value-added industrial solid waste utilization technologies.

[0004] In summary, considering the high SO4 content in saline soil... 2- Cl - Similar to the main ions contained in phosphogypsum and alkali slag, and solid wastes such as phosphogypsum, alkali slag, and carbide slag can be used in conjunction with other aluminosilicate solid wastes to prepare novel cementitious materials, achieving the effect of replacing cement. Therefore, if phosphogypsum, alkali slag, and carbide slag are used for the solidification of saline soil, the three solid wastes and the salt and alkali components contained in the saline soil can be combined to form a composite activator. Then, active aluminosilicate materials can be used as precursors to activate the strength, thus forming a solidified body with a certain strength. This can achieve the purpose of solidifying saline soil and consolidating harmful ions within it, while also consuming and utilizing solid waste, resulting in significant technical benefits. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a method for preparing a solidifying agent based on saline soil from solid waste. The method utilizes carbide slag to adjust alkalinity, and under the synergistic activation of salt and alkali, it stimulates steel slag and blast furnace slag to generate strong C-(A)-SH gel, ettringite, and hydrated calcium chloroaluminate crystal products. This not only strengthens the saline soil but also solidifies the harmful ions within it. Furthermore, it utilizes phosphogypsum and the SO4-rich environment of the saline soil...2- The ettringite formed by the reaction with aluminates not only ensures the early strength of the solidified saline soil, but also reduces the early drying shrinkage of the solidified saline soil. The reduction in drying shrinkage makes the volume change of the solidified saline soil more uniform, thereby improving the volume stability of the solidified saline soil. Furthermore, the micro-expansion effect of steel slag can resist the shrinkage in the later stage of the hydration reaction of the solidified saline soil. Shrinkage will cause local tensile stress on the surface and inside of the solidified saline soil, which will lead to cracks. External harmful substances can enter the interior of the solidified saline soil along the cracks. Reducing drying shrinkage will improve the durability of the solidified saline soil.

[0006] This invention provides a method for preparing a solidifying agent based on saline soil from solid waste, the specific implementation steps of which are as follows:

[0007] S1. Determination of SO4 in saline soil 2- Content:

[0008] S11. Using EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in saline soil. 2- The content was determined;

[0009] S12. The CaSO4·2H2O content of moderately soluble salts in saline soil was determined using the moderately soluble salt gypsum test method. This method was used to determine the concentration of readily soluble and moderately soluble salts (SO4·2H2O) in the saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content;

[0010] S2, Determination of Cl in saline soil - Content: The content of Cl in easily soluble salts in saline soil was determined by silver nitrate titration. - Perform the measurement;

[0011] S3. Determination of SO4 in mixture A 2- and Cl - Content:

[0012] S31. Quantitative X-ray diffraction (XRD) analysis was used to quantitatively analyze the CaSO4 content in phosphogypsum in mixture A, and the SO4 content in phosphogypsum in mixture A was obtained. 2- Quality score;

[0013] S32. X-ray fluorescence spectrometry (XRF) analysis of the Cl content in the alkali residue of mixture A. - Quantitative analysis was performed to determine the Cl content in the alkali residue of mixture A. - Quality score;

[0014] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively:

[0015] S41. Based on the SO4 content of saline soil and mixture A2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture is 1% to 2% of the total mass of the saline soil and mixture A. The amount of alkali residue incorporated into mixture A is obtained, thereby determining the amount of phosphogypsum and alkali residue incorporated into the curing agent containing ettringite (3CaO·Al2O3·3CaSO4·(30-32)H2O) and hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O), which enhances the strength and shrinkage resistance of the saline soil. The specific calculation expression for the amount of phosphogypsum and alkali residue incorporated is as follows:

[0016]

[0017]

[0018] In the formula: T is the mass of the saline soil, and a and b are the SO4 content in the saline soil, respectively. 2- and Cl - The content of , x and y are the masses of phosphogypsum and alkali residue in the mixture A, respectively, in wt. a and wt b SO4 in phosphogypsum 2- Cl in alkali residue - The mass fraction;

[0019] S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is calculated as follows:

[0020] (25%~35%)×T-(x+y)

[0021] In the formula: T is the mass of the saline soil, and x and y are the masses of phosphogypsum and alkali residue in the mixture A, respectively;

[0022] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mixing ratio of mixture A and mixture B in saline soil.

[0023] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali residue and carbide residue determined in step S5, add a certain amount of water to obtain the solidifying agent for solidifying saline soil.

[0024] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0025] Preferably, the mixture A comprises phosphogypsum and alkali residue.

[0026] Preferably, the mixture B comprises carbide slag, steel slag and blast furnace slag, and the dry basis mass fraction of each component in the mixture B is: the mass fraction of carbide slag is 5% to 10%, the mass fraction of steel slag is 1% to 5%, and the mass fraction of blast furnace slag is 85% to 90%, and the sum of the three is 100%.

[0027] Preferably, in the ettringite, SO4 2- The total amount of Ca incorporated into mixture A and mixture B 2+ The ratio is approximately 3:17, which corresponds to the total amount of Al incorporated into mixture A and mixture B. 3+ The ratio is approximately 1:2.

[0028] Preferably, in the hydrated calcium chloroaluminate, Cl - The total amount of Ca incorporated into mixture A and mixture B 2+ The ratio is approximately 2:17, which corresponds to the total amount of Al incorporated into mixture A and mixture B. 3+ The ratio is approximately 1:3.

[0029] Preferably, in step S5, the alkali slag and the carbide slag are both undried and unground slurries, the steel slag is 1000-mesh finely ground steel slag, and the ore slag is S95 grade finely ground ore slag.

[0030] Preferably, in step S5, the number of samples for determining the moisture content of the alkali residue and the carbide residue is greater than or equal to 9, and the number of samples from the top, middle and bottom is greater than or equal to 3.

[0031] Preferably, in step S6, the mass of water required for mixing the curing agent is 30% to 35% of the total mass of mixture A, mixture B, and saline soil.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. This invention removes SO4 from saline soil. 2- and Cl -After quantitative analysis, it is utilized as a beneficial component. Combined with the same ions contained in phosphogypsum and alkaline slag, and by adding carbide slag to adjust alkalinity, a salt-alkali synergistic effect is formed. Supplemented with active aluminosilicate materials such as steel slag and mineral slag, through hydration reactions, harmful SO4 ions in saline soil are consolidated. 2- and Cl - The formation of strong C-(A)-SH gel and ettringite and hydrated calcium chloroaluminate crystals provides a guarantee for the formation of strength in solidified saline soil.

[0034] 2. This invention utilizes the SO4-rich soil and phosphogypsum. 2- The reaction with aluminates produces ettringite, which improves the early-age strength of the solidified saline soil, enabling it to meet the early-age performance requirements of actual construction. At the same time, the formation of ettringite effectively reduces the drying shrinkage of the solidified saline soil and improves its early-age volume stability. Adding steel slag to the saline soil solidifier, which contains free CaO, will form Ca(OH)2 crystals in the later hydration reaction, producing a micro-expansion effect. At the optimal dosage, the expansion amount and the shrinkage amount of the solidified saline soil cancel each other out, improving the later-age volume stability of the solidified saline soil and thus increasing its durability.

[0035] 3. This invention utilizes all solid waste materials to prepare saline soil solidifying agent, achieving high utilization rates for industrial solid wastes such as phosphogypsum, alkali slag, and carbide slag. Furthermore, this invention does not use cement; through the comprehensive utilization of mixture A and mixture B, it significantly reduces solid waste disposal costs and lowers the cost per unit strength of solidified saline soil.

[0036] 4. This invention directly utilizes alkaline slag slurry and carbide slag slurry as components of saline soil solidification agent, without separation and purification, drying or grinding, thus significantly reducing energy consumption during solid waste disposal. Attached Figure Description

[0037] Figure 1 This is a flowchart of the preparation method of the solidifying agent based on saline soil from solid waste according to the present invention;

[0038] Figure 2 This is a bar chart showing the unconfined compressive strength at 7 days and 28 days in a specific embodiment of the preparation method of the solidifying agent based on solid waste saline soil of the present invention.

[0039] Figure 3 This is a graph showing the drying shrinkage rate at 7 days and 28 days in a specific embodiment of the preparation method of the solidifying agent based on all-solid waste saline soil of the present invention. Detailed Implementation

[0040] To provide a detailed description of the technical content, objectives, and effects of this invention, the following description will be provided in conjunction with the accompanying drawings.

[0041] The preparation method of the solidifying agent based on solid waste saline soil utilizes the SO4 content of easily soluble and moderately soluble salts in the saline soil. 2- and Cl - SO4 from industrial solid waste phosphogypsum and alkali residue 2- and Cl - By adjusting the alkalinity using carbide slag, and under the synergistic activation effect of salt and alkali, aluminosilicate materials (steel slag, mine slag) are stimulated to generate C-(A)-SH gel with strength, as well as crystalline products such as ettringite and hydrated calcium chloroaluminate. This not only reinforces the saline soil but also consolidates the SO4 in the saline soil. 2- and Cl - The reinforced saline soil has a strength of 1.0-1.5 MPa at 7 days and 2.0-3.0 MPa at 28 days; phosphogypsum and saline soil are rich in SO4. 2- The ettringite produced by the reaction with aluminates not only ensures the early strength of solidified saline soil but also reduces its early-age drying shrinkage, thus improving volume stability. Furthermore, the micro-expansion effect of steel slag resists the shrinkage during the later stages of hydration, enhancing durability. This saline soil solidifying agent does not use cement; instead, it utilizes the synergistic activating effect of phosphogypsum, alkali slag, and carbide slag, supplemented with active aluminosilicate materials such as steel slag and mineral slag, to prepare a green solidifying agent, achieving the resource utilization of industrial solid waste. Figure 1 As shown, the specific implementation steps are as follows:

[0042] S1. Determination of SO4 in saline soil 2- The content of.

[0043] S2, Determination of Cl in saline soil - Content: The content of Cl in easily soluble salts in saline soil was determined by silver nitrate titration. - The measurements were taken.

[0044] S3. Determination of SO4 in mixture A 2- and Cl - The content of.

[0045] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively.

[0046] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mix ratio of mixture A and mixture B in saline soil.

[0047] Specifically, both the alkali slag and the carbide slag are undried and unground slurries, the steel slag is 1000-mesh finely ground steel slag, and the ore slag is S95 grade finely ground ore slag. In a preferred embodiment of the present invention, the number of samples for determining the moisture content of the alkali slag and the carbide slag is greater than or equal to 9, and the number of samples from the top, middle, and bottom are greater than or equal to 3.

[0048] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the moisture content of the alkali slag and carbide slag determined in step S5, add a certain amount of water to obtain the solidifying agent for solidified saline soil.

[0049] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0050] Specifically, mixture A includes phosphogypsum and alkaline slag. Mixture B includes carbide slag, steel slag, and blast furnace slag. The dry basis mass fractions of each component in mixture B are: carbide slag 5%–10%, steel slag 1%–5%, and blast furnace slag 85%–90%, and the sum of the three is 100%. In step S6, the mass of water required for mixing the curing agent is 30%–35% of the total mass of mixture A, mixture B, and saline soil.

[0051] The alkali slag in mixture A is rich in calcium elements such as CaCl2, Ca(OH)2, and CaCO3, and contains small amounts of Al2O3 and SiO2, with a pH of approximately 11-12. The carbide slag in mixture B contains a large amount of calcium oxide and small amounts of silicon, aluminum, and magnesium, with a pH of approximately 13-14. Both the alkali slag and carbide slag are alkaline and contain calcium, silicon, and aluminum components, possessing the potential to act as alkali activators. Simultaneously, phosphogypsum is rich in CaSO4, and its sulfate content can effectively activate the ettringite reaction in aluminosilicate materials, significantly affecting shrinkage and strength regulation. A salt-alkali synergistic activation system is constructed, supplemented with active aluminosilicate materials (slag, steel slag) as precursors to generate a salt-alkali synergistic activation effect forming a curing agent. The curing agent generates a strong C-(A)-SH gel and ettringite and hydrated calcium chloroaluminate crystals through hydration. ettringite is formed in the early stages of the curing agent's hydration reaction, exhibiting a micro-expansion effect that resists the shrinkage of the solidified saline soil.

[0052] Preferably, step S1 involves determining SO4 in the saline soil. 2- The specific process for determining the content is as follows:

[0053] S11. Using EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in saline soil. 2- The content of [the substance] was determined.

[0054] S12. The CaSO4·2H2O content of moderately soluble salts in saline soil was determined using the moderately soluble salt gypsum test method. This method was used to determine the concentration of readily soluble and moderately soluble salts (SO4·2H2O) in the saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content of.

[0055] Preferably, step S3 involves determining the SO4 content in mixture A. 2- and Cl - The specific process for determining the content is as follows:

[0056] S31. Quantitative X-ray diffraction (XRD) analysis was used to quantitatively analyze the CaSO4 content in phosphogypsum in mixture A, and the SO4 content in phosphogypsum in mixture A was obtained. 2- Quality score.

[0057] S32. X-ray fluorescence spectrometry (XRF) analysis of the Cl content in the alkali residue of mixture A. - Quantitative analysis was performed to determine the Cl content in the alkali residue of mixture A. - Quality score.

[0058] Preferably, the specific process for calculating the amount of mixture A and mixture B to be incorporated into the saline soil in step S4 is as follows:

[0059] S41. Based on the SO4 content of saline soil and mixture A 2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture A is 1% to 2% of the total mass of the saline soil. The amount of alkali residue incorporated into mixture A is then determined, thereby obtaining the amount of phosphogypsum and alkali residue incorporated into the curing agent containing ettringite (3CaO·Al2O3·3CaSO4·(30~32)H2O) and hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O), which enhances the strength and shrinkage resistance of the saline soil. The specific calculation expression for the amount of phosphogypsum and alkali residue incorporated is as follows:

[0060]

[0061]

[0062] In the formula: T is the mass of saline soil, and a and b are the concentrations of SO42- in the saline soil, respectively. 2- and Cl -The content of , x and y are the masses of phosphogypsum and alkali residue in mixture A, respectively, in wt. a and wt b SO4 in phosphogypsum 2- Cl in alkali residue - The quality score.

[0063] Furthermore, to optimize the formation of ettringite and hydrated calcium aluminate—that is, to improve the strength of saline soil and counteract its shrinkage without causing excessive expansion and resulting in microcracks within the soil—SO4 in ettringite should be optimized. 2- The total amount of Ca incorporated into mixture A and mixture B 2+ The ratio is approximately 3:17, which corresponds to the total amount of Al incorporated into mixture A and mixture B. 3+ The ratio is approximately 1:2. In hydrated calcium chloroaluminate, Cl... - The total amount of Ca incorporated into mixture A and mixture B 2+ The ratio is approximately 2:17, which corresponds to the total amount of Al incorporated into mixture A and mixture B. 3+ The ratio is approximately 1:3. Simultaneously, hydrated calcium aluminosilicate (Ca2Al2SiO7(OH)4nH2O) and hydrated calcium silicate (Ca5Si6O) are produced during the hydration reaction. 16 Two compounds (OH)·4H2O) overlap with crystals such as ettringite and hydrated calcium chloroaluminate, forming a network structure that solidifies saline soil particles and creates a stable saline soil solidified body.

[0064] S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is calculated as follows:

[0065] (25%~35%)×T-(x+y)

[0066] In the formula: T is the mass of saline soil, and x and y are the masses of phosphogypsum and alkali residue in mixture A, respectively.

[0067] The following describes in further detail a method for preparing a solidifying agent based on saline soil from solid waste, according to the present invention, with reference to specific embodiments:

[0068] Example 1:

[0069] S1. Determination of SO4 in 1.8 kg of saline soil 2- The content of.

[0070] S11. Weigh at least 10 portions of air-dried saline soil samples passing through a 2mm sieve, each portion weighing 100g, accurate to 0.01g. Use EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in the saline soil. 2-The content of SO42- was determined in each sample of saline soil. 2- Content, using the average value to represent the easily soluble salt SO4 in saline soil 2- content.

[0071] S12. Weigh at least 10 portions of air-dried saline soil samples that have passed through a 0.25mm sieve, each portion weighing 5g, accurate to 0.0001g. Use the medium-soluble salt gypsum test method to determine the CaSO4·2H2O content of the medium-soluble salt in the saline soil, obtaining the soluble salt SO4 content in each saline soil sample. 2- Content, using the average value to represent the soluble salt SO4 content in saline soil 2- Content; The content of easily soluble and moderately soluble salts (SO4) in saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content is 5.128 g·kg. -1 .

[0072] S2, Determination of Cl in 1.8 kg of saline soil - Content: Weigh at least 10 samples of air-dried saline soil (passing through a 2mm sieve), each 100g, accurate to 0.01g. Use silver nitrate titration to determine the Cl content of easily soluble salts in the saline soil. - The soluble salt Cl in each saline soil sample was determined by measurement. - Content, using the average value to represent Cl in saline soil - Content: 6.078 g / kg -1 .

[0073] S3. Determination of SO4 in mixture A 2- and Cl - The quality score.

[0074] S31. Weigh at least 10 portions of dried phosphogypsum sample, each portion weighing 2g, accurate to 0.01g. Quantitatively analyze the CaSO4 content in the phosphogypsum of mixture A using quantitative X-ray diffraction (XRD) to obtain the SO4 content of each portion of phosphogypsum in mixture A. 2- Mass fraction, using the average value to represent the SO4 content of phosphogypsum 2- The quality score is 67.701%.

[0075] S32. Weigh at least 10 portions of dried alkali residue sample, each 2g, accurate to 0.01g, and analyze the Cl content in the alkali residue of mixture A using X-ray fluorescence spectrometry (XRF). - Quantitative analysis was performed to determine the Cl content of the alkali residue in each sample of mixture A. - Mass fraction, using the average value to represent the Cl content in the alkali residue. - The quality score is 22.490%.

[0076] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively.

[0077] S41. Based on the SO4 content of saline soil and mixture A 2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture is 1% to 2% of the total mass of the saline soil and mixture A. The amount of alkali residue added to mixture A is obtained, thereby obtaining the amount of phosphogypsum and alkali residue added to the curing agent containing ettringite (3CaO·Al2O3·3CaSO4·(30~32)H2O) and hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O), which have high strength and good resistance to shrinkage of the saline soil. The amounts of phosphogypsum and alkali residue added are 77.7g and 103.8g, respectively.

[0078] S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is 0.22g, wherein the content of calcium carbide slag is 31.5g, the content of steel slag is 12.6g, and the content of blast furnace slag is 346.5g. Specifically, using this preparation method, the amount of mixture B added is 20% to 30% of the mass of the saline soil.

[0079] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mix ratio of mixture A and mixture B in saline soil.

[0080] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali slag and carbide slag determined in step S5, add a certain mass of water so that the mass of water is 0.3 of the total mass of mixture A, mixture B and saline soil, to obtain the solidifying agent for solidifying saline soil.

[0081] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0082] The solidifying agent for saline soil obtained by the preparation method of this invention in this embodiment has advantages such as high early strength (7-day unconfined compressive strength reaches 1.44 MPa) and low drying shrinkage (56-day drying shrinkage is only 0.21%). While solidifying harmful ions in saline soil, it realizes the synergistic resource utilization of industrial solid wastes such as phosphogypsum, alkali slag, carbide slag and steel slag in the field of building materials.

[0083] Example 2:

[0084] S1. Determination of SO4 in 1.8 kg of saline soil 2- The content of.

[0085] S11. Weigh at least 10 portions of air-dried saline soil samples passing through a 2mm sieve, each portion weighing 100g, accurate to 0.01g. Use EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in the saline soil. 2- The content of SO42- was determined in each sample of saline soil. 2- Content, using the average value to represent the easily soluble salt SO4 in saline soil 2- content.

[0086] S12. Weigh at least 10 portions of air-dried saline soil samples that have passed through a 0.25mm sieve, each portion weighing 5g, accurate to 0.0001g. Use the medium-soluble salt gypsum test method to determine the CaSO4·2H2O content of the medium-soluble salt in the saline soil, obtaining the soluble salt SO4 content in each saline soil sample. 2- Content, using the average value to represent the soluble salt SO4 content in saline soil 2- Content; The content of easily soluble and moderately soluble salts (SO4) in saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content of SO4 in 1.8 kg of saline soil. 2- The content is 6.244 g·kg -1 .

[0087] S2, Determination of Cl in 1.8 kg of saline soil - Content: Weigh at least 10 samples of air-dried saline soil (passing through a 2mm sieve), each 100g, accurate to 0.01g. Use silver nitrate titration to determine the Cl content of easily soluble salts in the saline soil. - The soluble salt Cl in each saline soil sample was determined by measurement. - Content, using the average value to represent Cl in saline soil - Content; Cl in 1.8 kg of saline soil - The content is 6.678 g·kg. -1 .

[0088] S3. Determination of SO4 in mixture A 2- and Cl -The quality score.

[0089] S31. Weigh at least 10 portions of dried phosphogypsum sample, each portion weighing 2g, accurate to 0.01g. Quantitatively analyze the CaSO4 content in the phosphogypsum of mixture A using quantitative X-ray diffraction (XRD) to obtain the SO4 content of each portion of phosphogypsum in mixture A. 2- Mass fraction, using the average value to represent the SO4 content of phosphogypsum 2- The quality score is 67.701%.

[0090] S32. Weigh at least 10 portions of dried alkali residue sample, each 2g, accurate to 0.01g, and analyze the Cl content in the alkali residue of mixture A using X-ray fluorescence spectrometry (XRF). - Quantitative analysis was performed to determine the Cl content of the alkali residue in each sample of mixture A. - Mass fraction, using the average value to represent the Cl content in the alkali residue. - The quality score is 22.490%.

[0091] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively.

[0092] S41. Based on the SO4 content of saline soil and mixture A 2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture is 1% to 2% of the total mass of the saline soil and mixture A. The amount of alkali residue added to mixture A is obtained, thereby obtaining the amount of phosphogypsum and alkali residue added to the curing agent containing ettringite (3CaO·Al2O3·3CaSO4·(30~32)H2O) and hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O), which have high strength and good resistance to shrinkage of the saline soil. The amounts of phosphogypsum and alkali residue added are 43.9g and 97.6g, respectively.

[0093] S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is 0.24g, wherein the content of calcium carbide slag is 32.4g, the content of steel slag is 15.5g, and the content of blast furnace slag is 378.0g. Specifically, using this preparation method, the amount of mixture B added is 20% to 30% of the mass of the saline soil.

[0094] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mix ratio of mixture A and mixture B in saline soil.

[0095] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali slag and carbide slag determined in step S5, add a certain mass of water so that the mass of water is 0.3 of the total mass of mixture A, mixture B and saline soil, to obtain the solidifying agent for solidifying saline soil.

[0096] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0097] The solidifying agent for solid waste saline soil obtained by the preparation method of this invention in this embodiment shows comparable overall differences between the solidified saline soil and that of Example 1. The solidified saline soil obtained by this embodiment has a 7-day unconfined compressive strength of 1.34 MPa, indicating high early strength; a 28-day unconfined compressive strength of 2.65 MPa; and a 56-day drying shrinkage rate of 0.20%, indicating low shrinkage.

[0098] Example 3:

[0099] S1. Determination of SO4 in 1.8 kg of saline soil 2- The content of.

[0100] S11. Weigh at least 10 portions of air-dried saline soil samples passing through a 2mm sieve, each portion weighing 100g, accurate to 0.01g. Use EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in the saline soil. 2- The content of SO42- was determined in each sample of saline soil. 2- Content, using the average value to represent the easily soluble salt SO4 in saline soil 2- content.

[0101] S12. Weigh at least 10 portions of air-dried saline soil samples that have passed through a 0.25mm sieve, each portion weighing 5g, accurate to 0.0001g. Use the medium-soluble salt gypsum test method to determine the CaSO4·2H2O content of the medium-soluble salt in the saline soil, obtaining the soluble salt SO4 content in each saline soil sample. 2- Content, using the average value to represent the soluble salt SO4 content in saline soil 2- Content; The content of easily soluble and moderately soluble salts (SO4) in saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content of SO4 in 1.8 kg of saline soil. 2- The content is 6.244 g·kg -1 .

[0102] S2, Determination of Cl in 1.8 kg of saline soil- Content: Weigh at least 10 samples of air-dried saline soil (passing through a 2mm sieve), each 100g, accurate to 0.01g. Use silver nitrate titration to determine the Cl content of easily soluble salts in the saline soil. - The soluble salt Cl in each saline soil sample was determined by measurement. - Content, using the average value to represent Cl in saline soil - Content; Cl in 1.8 kg of saline soil - The content is 6.678 g·kg. -1 .

[0103] S3. Determination of SO4 in mixture A 2- and Cl - The quality score.

[0104] S31. Weigh at least 10 portions of dried phosphogypsum sample, each portion weighing 2g, accurate to 0.01g. Quantitatively analyze the CaSO4 content in the phosphogypsum of mixture A using quantitative X-ray diffraction (XRD) to obtain the SO4 content of each portion of phosphogypsum in mixture A. 2- Mass fraction, using the average value to represent the SO4 content of phosphogypsum 2- The quality score is 67.701%.

[0105] S32. Weigh at least 10 portions of dried alkali residue sample, each 2g, accurate to 0.01g, and analyze the Cl content in the alkali residue of mixture A using X-ray fluorescence spectrometry (XRF). - Quantitative analysis was performed to determine the Cl content of the alkali residue in each sample of mixture A. - Mass fraction, using the average value to represent the Cl content in the alkali residue. - The quality score is 22.490%.

[0106] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively.

[0107] S41. Based on the SO4 content of saline soil and mixture A 2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture is 1% to 2% of the total mass of the saline soil and mixture A. The amount of alkali residue added to mixture A is obtained, thereby obtaining the amount of phosphogypsum and alkali residue added to the curing agent containing ettringite (3CaO·Al2O3·3CaSO4·(30~32)H2O) and hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O), which have high strength and good resistance to shrinkage of the saline soil. The amounts of phosphogypsum and alkali residue added are 43.99g and 37.74g, respectively.

[0108] S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is 0.27, wherein the content of calcium carbide slag is 30.2g, the content of steel slag is 20.0g, and the content of blast furnace slag is 441.0g. Specifically, using this preparation method, the amount of mixture B added is 20% to 30% of the mass of the saline soil.

[0109] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mix ratio of mixture A and mixture B in saline soil.

[0110] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali slag and carbide slag determined in step S5, add a certain mass of water so that the mass of water is 0.3 of the total mass of mixture A, mixture B and saline soil, to obtain the solidifying agent for solidifying saline soil.

[0111] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0112] The solidifying agent for solid waste saline soil obtained by the preparation method of this invention in this embodiment shows comparable overall differences between the solidified saline soil and those in Examples 1 and 2. The solidified saline soil obtained by this embodiment has a 7-day unconfined compressive strength of 1.38 MPa, indicating high early strength; a 28-day unconfined compressive strength of 2.68 MPa; and a 56-day drying shrinkage rate of 0.20%, indicating low shrinkage.

[0113] The saline soil used in Examples 1, 2, and 3 was SO4. 2- and Cl - Different types of saline soil with varying content achieve similar solidification effects, demonstrating that the saline soil solidifier of this invention can be used to solidify different types of saline soil.

[0114] Comparative Example 1:

[0115] S1. Determination of SO4 in 1.8 kg of saline soil 2- The content of.

[0116] S11. Weigh at least 10 portions of air-dried saline soil samples passing through a 2mm sieve, each portion weighing 100g, accurate to 0.01g. Use EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in the saline soil.2- The content of SO42- was determined in each sample of saline soil. 2- Content, using the average value to represent the easily soluble salt SO4 in saline soil 2- content.

[0117] S12. Weigh at least 10 portions of air-dried saline soil samples that have passed through a 0.25mm sieve, each portion weighing 5g, accurate to 0.0001g. Use the medium-soluble salt gypsum test method to determine the CaSO4·2H2O content of the medium-soluble salt in the saline soil, obtaining the soluble salt SO4 content in each saline soil sample. 2- Content, using the average value to represent the soluble salt SO4 content in saline soil 2- Content; The content of easily soluble and moderately soluble salts (SO4) in saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content is 5.128 g·kg. -1 .

[0118] S2, Determination of Cl in 1.8 kg of saline soil - Content: Weigh at least 10 samples of air-dried saline soil (passing through a 2mm sieve), each 100g, accurate to 0.01g. Use silver nitrate titration to determine the Cl content of easily soluble salts in the saline soil. - The soluble salt Cl in each saline soil sample was determined by measurement. - Content, using the average value to represent Cl in saline soil - Content: 6.078 g / kg -1 .

[0119] S3. This comparative example does not include phosphogypsum; only the Cl content in mixture A is determined. - Mass fraction: Weigh at least 10 portions of dried alkali residue sample, each 2g, accurate to 0.01g, and analyze the Cl content in the alkali residue of mixture A using X-ray fluorescence spectrometry (XRF). - Quantitative analysis was performed to determine the Cl content of the alkali residue in each sample of mixture A. - Mass fraction, using the average value to represent the Cl content in the alkali residue. - The quality score is 22.490%.

[0120] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively.

[0121] S41, based on the Cl content of saline soil and mixture A - The total mass of the alkali residue is 1% to 2% of the total mass of the saline soil and mixture A, thus determining the amount of alkali residue incorporated into mixture A. The amounts of phosphogypsum and alkali residue incorporated are 0g and 103.8g, respectively.

[0122] S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is 0.22g, wherein the content of calcium carbide slag is 31.5g, the content of steel slag is 12.6g, and the content of blast furnace slag is 346.5g. Specifically, using this preparation method, the amount of mixture B added is 20% to 30% of the mass of the saline soil.

[0123] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mix ratio of mixture A and mixture B in saline soil.

[0124] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali slag and carbide slag determined in step S5, add a certain mass of water so that the mass of water is 0.3 of the total mass of mixture A, mixture B and saline soil, to obtain the solidifying agent for solidifying saline soil.

[0125] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0126] In this comparative example, mixture A, without the addition of phosphogypsum, had a 7-day unconfined compressive strength of 0.34 MPa, which was only 23.6% of the 7-day unconfined compressive strength in Example 1, 25.4% in Example 2, and 24.6% in Example 3, indicating very low early strength. Its 56-day drying shrinkage was 0.30%, which was 1.43 times that of Example 1, and 1.5 times that of both Example 2 and Example 3, indicating high drying shrinkage and poor volume stability. The addition of phosphogypsum significantly improved the early-age strength of the solidified saline soil and inhibited drying shrinkage.

[0127] Comparative Example 2:

[0128] S1. Determination of SO4 in 1.8 kg of saline soil 2- The content of.

[0129] S11. Weigh at least 10 portions of air-dried saline soil samples passing through a 2mm sieve, each portion weighing 100g, accurate to 0.01g. Use EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in the saline soil. 2- The content of SO42- was determined in each sample of saline soil. 2-Content, using the average value to represent the easily soluble salt SO4 in saline soil 2- content.

[0130] S12. Weigh at least 10 portions of air-dried saline soil samples that have passed through a 0.25mm sieve, each portion weighing 5g, accurate to 0.0001g. Use the medium-soluble salt gypsum test method to determine the CaSO4·2H2O content of the medium-soluble salt in the saline soil, obtaining the soluble salt SO4 content in each saline soil sample. 2- Content, using the average value to represent the soluble salt SO4 content in saline soil 2- Content; The content of easily soluble and moderately soluble salts (SO4) in saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content is 5.128 g·kg. -1 .

[0131] S2, Determination of Cl in 1.8 kg of saline soil - Content: Weigh at least 10 samples of air-dried saline soil (passing through a 2mm sieve), each 100g, accurate to 0.01g. Use silver nitrate titration to determine the Cl content of easily soluble salts in the saline soil. - The soluble salt Cl in each saline soil sample was determined by measurement. - Content, using the average value to represent Cl in saline soil - Content: 6.078 g / kg -1 .

[0132] S3. Determination of SO4 in mixture A 2- and Cl - The quality score.

[0133] S31. Weigh at least 10 portions of dried phosphogypsum sample, each portion weighing 2g, accurate to 0.01g. Quantitatively analyze the CaSO4 content in the phosphogypsum of mixture A using quantitative X-ray diffraction (XRD) to obtain the SO4 content of each portion of phosphogypsum in mixture A. 2- Mass fraction, using the average value to represent the SO4 content of phosphogypsum 2- The quality score is 67.701%.

[0134] S32. Weigh at least 10 portions of dried alkali residue sample, each 2g, accurate to 0.01g, and analyze the Cl content in the alkali residue of mixture A using X-ray fluorescence spectrometry (XRF). - Quantitative analysis was performed to determine the Cl content of the alkali residue in each sample of mixture A. - Mass fraction, using the average value to represent the Cl content in the alkali residue. - The quality score is 22.490%.

[0135] S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively.

[0136] S41. Based on the SO4 content of saline soil and mixture A 2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture is 1% to 2% of the total mass of the saline soil and mixture A. The amount of alkali residue added to mixture A is obtained, thereby obtaining the amount of phosphogypsum and alkali residue added to the curing agent containing ettringite (3CaO·Al2O3·3CaSO4·(30~32)H2O) and hydrated calcium chloroaluminate (3CaO·Al2O3·CaCl2·10H2O), which have high strength and good resistance to shrinkage of the saline soil. The amounts of phosphogypsum and alkali residue added are 77.7g and 103.8g, respectively.

[0137] S42. In this comparative example, no steel slag is added. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is 0.21g, containing 31.5g of calcium carbide slag, 0g of steel slag, and 346.5g of blast furnace slag. Specifically, using this preparation method, the amount of mixture B added is 20%–30% of the mass of the saline soil.

[0138] S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mix ratio of mixture A and mixture B in saline soil.

[0139] S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali slag and carbide slag determined in step S5, add a certain mass of water so that the mass of water is 0.3 of the total mass of mixture A, mixture B and saline soil, to obtain the solidifying agent for solidifying saline soil.

[0140] S7. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0141] The comparative mixture B, without the addition of steel slag, had a 56-day drying shrinkage rate of 0.26%, which was 1.24 times that of Example 1, 1.30 times that of Example 2, and 1.30 times that of Example 3. This high drying shrinkage resulted in poor volume stability. The addition of steel slag significantly inhibited the drying shrinkage of the solidified saline soil.

[0142] Comparative Example 3:

[0143] S1. Determination of SO4 in 1.8 kg of saline soil 2- The content of.

[0144] S11. Weigh at least 10 portions of air-dried saline soil samples passing through a 2mm sieve, each portion weighing 100g, accurate to 0.01g. Use EDTA (ethylenediaminetetraacetic acid) complexometric titration to determine the soluble salt SO4 in the saline soil. 2- The content of SO42- was determined in each sample of saline soil. 2- Content, using the average value to represent the easily soluble salt SO4 in saline soil 2- content.

[0145] S12. Weigh at least 10 portions of air-dried saline soil samples that have passed through a 0.25mm sieve, each portion weighing 5g, accurate to 0.0001g. Use the medium-soluble salt gypsum test method to determine the CaSO4·2H2O content of the medium-soluble salt in the saline soil, obtaining the soluble salt SO4 content in each saline soil sample. 2- Content, using the average value to represent the soluble salt SO4 content in saline soil 2- Content; The content of easily soluble and moderately soluble salts (SO4) in saline soil. 2- The sum of the contents of SO4 in saline soil 2- The content is 5.128 g·kg. -1 .

[0146] S2, Determination of Cl in 1.8 kg of saline soil - Content: Weigh at least 10 samples of air-dried saline soil (passing through a 2mm sieve), each 100g, accurate to 0.01g. Use silver nitrate titration to determine the Cl content of easily soluble salts in the saline soil. - The soluble salt Cl in each saline soil sample was determined by measurement. - Content, using the average value to represent Cl in saline soil - Content: 6.078 g / kg -1 .

[0147] S3. In this comparative example, mixture A is not added; only mixture B is added. The amount of mixture B added is 0.22g, containing 31.5g of calcium carbide slag, 12.6g of steel slag, and 346.5g of blast furnace slag. Specifically, using this preparation method, the amount of mixture B added is 20%–30% of the mass of the saline soil.

[0148] S4. Stir the carbide slag in mixture B evenly and determine the moisture content of the carbide slag; and obtain the required mass of carbide slag according to the mixing ratio of mixture B in saline soil.

[0149] S5. Add the prepared mixture B to the mixer, stir at low speed for 100s, then stir at high speed for 180s. Based on the water content of the carbide slag determined in step S5, add a certain mass of water so that the mass of water is 0.3 times the total mass of mixture A, mixture B and saline soil, to obtain the solidifying agent for solidifying saline soil.

[0150] S6. Add the curing agent and saline soil to the mixer container separately. First, mix at low speed for 3 minutes, then mix at high speed for 7 minutes. Scrape the mixture on the blades and the mixer container wall into the middle of the mixer container wall. Mix at high speed for 5 minutes. After molding and curing, the cured saline soil is obtained.

[0151] This comparative example did not include mixture A, SO4. 2- and Cl - The required proportions were not met. The 7-day unconfined compressive strength was 0.25 MPa, only 17.4% of the 7-day unconfined compressive strength in Example 1, 18.7% in Example 2, and 18.1% in Example 3, indicating very low early strength. The 56-day unconfined compressive strength at 28 days was also 0.28 MPa, only 10.0% of the 56-day unconfined compressive strength in Example 1, 10.6% in Example 2, and 10.4% in Example 3, essentially providing no reinforcement to the saline soil. This comparative example did not add mixture A; only SO4 in the saline soil was present. 2- and Cl - When interacting with mixture B, the reinforcement effect of Examples 1 to 3 cannot be achieved.

[0152] from Figure 2 and Figure 3 It can be seen that, compared with comparative examples 1 to 3, the examples 1 to 3 obtained by the preparation method of the present invention have higher early-age unconfined compressive strength and lower drying shrinkage. The higher early-age unconfined compressive strength can better meet the requirements of actual construction for its early-age performance, and the lower drying shrinkage can effectively reduce cracks on the surface and inside of the solidified saline soil, and reduce the intrusion of external harmful substances into the solidified saline soil along the cracks, thereby making the solidified saline soil more durable.

[0153] This invention utilizes industrial solid waste to prepare a solid waste-based saline soil stabilizer that meets application requirements while eliminating harmful SO4 in the saline soil. 2- Cl - By utilizing and solidifying these technologies, environmental protection can be achieved while reducing production costs, resulting in promising prospects for industrial application and economic benefits.

[0154] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing a solidifying agent based on saline soil from solid waste, characterized in that, The specific implementation steps are as follows: S1, Determination of the content of SO4 in saline soil 2- : S11, the content of easily soluble salt SO4 in saline soil is determined by EDTA complexometric titration method; 2- the content of easily soluble salt SO4 in saline soil is determined by EDTA complexometric titration method; S12, the content of CaS04-2H20 in the medium-soluble salt in the saline soil is determined by the medium-soluble salt gypsum test method, and the sum of the contents of the easily soluble salt and the medium-soluble salt SO4 2- in the saline soil is taken as the content of SO4 2- in the saline soil. S2, Determination of Cl in saline soil - Content: The content of Cl in easily soluble salts in saline soil was determined by silver nitrate titration. - Perform the measurement; S3. Determination of SO4 in mixture A 2- and Cl - Content: S31. Quantitative X-ray diffraction analysis was used to quantitatively analyze the CaSO4 content in phosphogypsum in mixture A, and the SO4 content in phosphogypsum in mixture A was obtained. 2- Quality score; S32. Analyze the Cl content in the alkaline residue of mixture A using X-ray fluorescence spectroscopy. - Quantitative analysis was performed to determine the Cl content in the alkali residue of mixture A. - Quality score; S4. Calculate the amount of mixture A and mixture B to be added to the saline soil respectively: S41. Based on the SO4 content of saline soil and mixture A 2- The total mass of the saline soil and mixture A accounts for 2% to 4% of the total mass of the mixture. The amount of phosphogypsum incorporated into mixture A is then determined based on the Cl content of the saline soil and mixture A. - The total mass of the mixture is 1% to 2% of the total mass of the saline soil and mixture A. The amount of alkali residue incorporated into mixture A is obtained, thereby determining the amount of phosphogypsum and alkali residue incorporated into the curing agent containing ettringite and hydrated calcium chloroaluminate, which enhance the strength and shrinkage resistance of the saline soil. The specific calculation expression for the amount of phosphogypsum and alkali residue incorporated is as follows: ； ； In the formula: T Let a be the mass of the saline soil, and b be the amount of SO4 in the saline soil, respectively. 2- and Cl - The content of , x and y are the masses of phosphogypsum and alkali residue in the mixture A, respectively, in wt. a and wt b SO4 in phosphogypsum 2- Cl in alkali residue - The mass fraction; S42. Based on the total amount of mixture A and mixture B added, and using the amount of mixture A obtained in step S41, the amount of mixture B added is calculated as follows: (25%~35%)× T -( x + y ) ； In the formula: T Let x be the mass of the saline soil, and let y be the mass of phosphogypsum and alkali residue in mixture A, respectively. S5. Mix the alkali residue in mixture A and the carbide slag in mixture B evenly, and determine the moisture content of the alkali residue and carbide slag respectively; and obtain the required mass of alkali residue and carbide slag according to the mixing ratio of mixture A and mixture B in saline soil. S6. Add the prepared mixture A and mixture B to the mixer respectively, stir at low speed for 100s, then stir at high speed for 180s. According to the water content of the alkali residue and carbide residue determined in step S5, add a certain amount of water to obtain the solidifying agent for solidifying saline soil. The mixture A comprises phosphogypsum and alkali residue; The mixture B includes carbide slag, steel slag and blast furnace slag. The dry basis mass fraction of each component in the mixture B is as follows: the mass fraction of carbide slag is 5% to 10%, the mass fraction of steel slag is 1% to 5%, and the mass fraction of blast furnace slag is 85% to 90%, and the sum of the three is 100%.

2. The method for preparing the solidifying agent based on saline soil from solid waste according to claim 1, characterized in that, In the ettringite, SO4 2- The total amount of Ca incorporated into mixture A and mixture B 2+ The ratio is 3:17, which corresponds to the total amount of Al incorporated into mixture A and mixture B. 3+ The ratio is 1:

2.

3. The method for preparing the solidifying agent based on saline soil from solid waste according to claim 1, characterized in that, In the hydrated calcium chloroaluminate, Cl - The total amount of Ca incorporated into mixture A and mixture B 2+ The ratio is 2:17, which corresponds to the total amount of Al incorporated into mixture A and mixture B. 3+ The ratio is 1:

3.

4. The method for preparing the solidifying agent based on saline soil from whole solid waste according to claim 1, characterized in that, In step S5, both the alkali slag and the carbide slag are undried and unground slurries, the steel slag is 1000-mesh finely ground steel slag, and the ore slag is S95 grade finely ground ore slag.

5. The method for preparing a solidifying agent based on saline soil from solid waste according to claim 1, characterized in that, In step S5, the number of samples for determining the moisture content of the alkali residue and the carbide residue is greater than or equal to 9, and the number of samples from the top, middle and bottom is greater than or equal to 3.

6. The method for preparing a solidifying agent based on saline soil from solid waste according to claim 1, characterized in that, In step S6, the mass of water required for mixing the curing agent is 30% to 35% of the total mass of mixture A, mixture B and saline soil.

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