A non-calcium-based sludge solidifying agent and its application

Abstract

The present application discloses a non-calcium-based silt solidifying agent and its application. The non-calcium-based silt solidifying agent comprises the following raw materials by weight: 15-30 parts water glass, 1-2 parts auxiliary solidifying agent, 1-2 parts anionic surfactant, and 70-75 parts water, wherein the modulus of the water glass is 2.0-2.8. The non-calcium-based silt solidifying agent of the present application is not easy to cause soil compaction during the silt solidification process, has a low dry density, a large porosity, and high permeability, can significantly improve the unconfined compressive strength and water stability of silt soil, and expand the application range of the solidified silt soil.

Description

Technical Field

[0001] The present application relates to the field of sludge solidifying agents, and in particular to a non-calcium-based sludge solidifying agent and its application. Background Art

[0002] Silt is a special type of soil with properties that differ from those of ordinary soil. Silt soft soil has a high moisture content, generally greater than 40%, and exhibits rheological and thixotropic properties. Its natural porosity ratio is greater than 1.0, and it exhibits low strength, high compressibility, poor permeability, and low shear strength.

[0003] Silt solidification treatment involves adding a certain amount of a solidifying agent to the silt to improve its physical and mechanical properties to meet the needs of various projects. Commonly used silt solidifiers are calcium-based solidifiers, primarily composed of calcium-containing inorganic compounds such as lime, cement, and fly ash. They can significantly improve soil strength and water stability. However, the production and use of traditional calcium-based solidifiers generate large amounts of greenhouse gases, causing serious air pollution. They can also lead to severe soil compaction and salinization. Plants are largely unable to survive in solidified soil, resulting in poor ecological performance. Therefore, they are primarily used in non-ecological solidification applications such as roads, water conservancy projects, and construction. With the advent of the concept of ecological civilization construction, the application scenarios of silt solidifiers have become more complex. Demand is increasing in areas such as desertification control, mine remediation, and slope soil and water conservation. The performance of solidifiers should also take into account improvements in both soil engineering and ecological properties. Summary of the Invention

[0004] In order to make the solidified sludge have better ecological properties, the present application provides a non-calcium-based sludge solidifying agent.

[0005] In a first aspect, a non-calcium-based sludge solidifying agent comprises the following raw materials in parts by weight: 15-30 parts of water glass, 1-2 parts of an auxiliary solidifying agent, 1-2 parts of anionic surfactant, and 70-75 parts of water, wherein the modulus of the water glass is 2.0-2.8.

[0006] The anionic surfactant may be sulfonated oil or α-sulfonated fatty acid ester.

[0007] By adopting the above technical solution, water glass is an admixture for sand solidification, which is often added together with limestone, cement and other curing agents to improve the curing effect of limestone and cement; the sodium ions and silicon oxide in water glass can react with the calcium ions and magnesium ions in silt to form silica gel, which fills the gaps between soil particles and bonds soil particles, thereby improving the integrity of soil particles. However, the present application is to prepare a silt solidifier. The difference between silt and sand is that silt contains a large number of fine particles, with a particle size usually less than 0.002mm, while the particle size of sand is between 0.002 and 2mm. Therefore, the particles of silt are finer and generally more difficult to solidify. In addition, the high mineral content in silt leads to a strong water absorption capacity of silt, resulting in a higher water content in silt. When using a calcium-based curing agent, the soil is more likely to form clumps, causing soil compaction. The water glass used in this application is a calcium-free inorganic compound. The soil structure formed during solidification is uniform, and an auxiliary curing agent is used to increase the water glass's hardening speed, improving the early strength of the silt soil while uniformly solidifying it. This application also incorporates an anionic surfactant. On the one hand, the anionic surfactant can improve the interaction between soil particles and reduce the hydrophilicity of the soil surface, thereby reducing the moisture content of the silt and forming a permanent bond between the particles. This improves the stability and compressive strength of the silt particles after the bonding bridge is formed. On the other hand, the anionic surfactant also promotes the uniform dispersion of the water glass and, together with the water glass, coats the silt particles, increasing the adhesion and compactness of the silt soil, thereby improving the compressive strength and durability of the silt. The modulus of water glass is further limited to between 2.0 and 2.8. If the modulus of water glass is too high, the fluidity and hydrophilicity of water glass are poor, the local hardness of the solidified silt is too large and soil compaction is prone to occur, and the synergistic effect between water glass and other components is poor, resulting in poor stability of the solidified silt; if the modulus of water glass is too low, the solidified silt is soft and has poor compressive strength. By optimizing the water glass modulus, the solidified silt soil has better compressive strength and better stability.

[0008] Preferably, the raw materials include the following parts by weight: 15-30 parts of water glass, 1-2 parts of auxiliary curing agent, 1-2 parts of anionic surfactant, 0.5-1 part of sodium lignin sulfonate, and 70-75 parts of water.

[0009] By adopting the above technical solution, sodium lignin sulfonate is further added. Sodium lignin sulfonate hydrolyzes in the soil interstitial fluid to produce high-valent cations, which replace low-valent cations in the silt. This reduces the thickness of the double layer on the surface of the silt particles and the distance between soil layers. The sodium lignin sulfonate works together with the anionic surfactant to reduce the electrostatic attraction between the silt particles and improve their cohesion and adhesion. In addition, because the silt particles carry a negative charge on their surface, positively charged organic macromolecules can be adsorbed onto the surface of the silt particles to form a cementing substance, filling the pores and connecting the silt particles together through frictional and physical bonding. The hydrolyzed lignin produces a volume-expanding substance that further fills the pores, improving the compactness of the silt and enhancing the curing and bonding effect of the curing agent.

[0010] Preferably, the modulus of the water glass is 2.3-2.5.

[0011] By adopting the above technical solution, the modulus of water glass is further optimized. When the modulus is 2.3-2.5 and it is used as a binder for silt particles, no colloid particles will be generated inside the silt, and therefore a system in which true solution and colloidal solution coexist will not be formed. The effect of the silt solidifier is greatly improved, thereby greatly improving the compressive strength and stability of the solidified silt.

[0012] Preferably, the auxiliary curing agent is selected from one of silicon phosphate, zinc phosphate, magnesium phosphate, sodium fluorosilicate, zinc chloride, ammonium chloride, polyacrylic acid, polyacrylamide, and polyvinyl alcohol.

[0013] By adopting the above scheme, the above auxiliary curing agents can increase the hardening speed of water glass, improve the curing strength and bonding effect of water glass, thereby improving the coating effect of water glass and anionic surfactants, and improving the curing effect of non-calcium-based sludge curing agent on sludge.

[0014] Preferably, the auxiliary curing agent is selected from one of silicon phosphate, zinc phosphate, magnesium phosphate, sodium fluorosilicate, zinc chloride, and ammonium chloride.

[0015] By adopting the above technical solution, organic materials are selected as auxiliary curing agents, and water glass forms a silicate gel solution after the ion reaction with the silt, which further reacts with the organic polymer, causing the bond bridge structure of the silt particles to be destroyed, and the gel strength is destroyed, affecting the compressive strength and durability of the silt. In addition, the surface polarity of the organic polymer is low, and the contact with the water glass is poor, and the organic polymer is easily reacted with other substances in the silt or is catalytically decomposed, affecting the hardening of the water glass and the stability after hardening, and then affecting the curing effect of the non-calcium-based silt curing agent. Preferably, inorganic materials are used as curing agents, which can reduce the strength decay of the silt soil after the water glass solidifies, thereby improving the stability after the silt solidifies.

[0016] Preferably, the auxiliary curing agent is selected from silicon phosphate.

[0017] By adopting the above technical solution, silicon phosphate, when used as a hardener for water glass, hydrolyzes at a moderate rate, resulting in a moderate hardening rate for the water glass. This results in a uniform and stable structure of silt particles, and reduces soil compaction that can occur when the water glass hardens too quickly, as well as the loss of compressive strength that can occur when the water glass hardens too slowly. Furthermore, silicon phosphate is a non-toxic inorganic material with minimal environmental pollution. The cured silt has better ecological properties, thus expanding its application range.

[0018] Preferably, the raw materials further include modified wool fibers, the weight ratio of the modified wool fibers to water glass is (2-7):(15-30), and the modified wool fibers are obtained by grafting carboxymethyl chitosan onto wool fibers.

[0019] By adopting the above technical solution, wool fiber is a natural fiber with a wide range of sources, with good softness and flexibility. It can form a certain spatial structure inside the silt and increase the internal friction of the silt soil. In addition, there are active groups such as carboxyl and hydroxyl groups on the surface of wool fibers, which can form multiple chemical bonds with water glass, making the internal cross-linking of the silt form a more complex spatial structure, thereby improving the compressive strength and stability of the silt. Wool fiber can improve the microscopic pore structure of the silt, and synergize with wood cellulose to improve the drainage and drying properties of the silt, thereby improving the water stability of the silt. The surface of wool fibers carries a large number of active groups such as amino and hydroxyl groups, which can increase the electrical flux of the silt, reduce the corrosion resistance of the solidified silt, and improve the durability of the silt. Under the action of anionic surfactants, wool fibers can be more evenly dispersed in the soil, further exerting the synergistic effect of wool fibers and other substances.

[0020] Wool fibers are modified with carboxymethyl chitosan, a natural substance that gradually decomposes into nutrients in the soil, improving the soil's ecological health. Carboxymethyl chitosan modification introduces cationic groups, such as carboxyl groups, into the wool fibers, allowing them to better bind to negatively charged silt particles and form complexes with calcium and magnesium ions in the silt, increasing the silt's compressive strength. Carboxymethyl chitosan-modified wool fibers are more hydrophilic and synergize with lignocellulose to improve the silt's water stability.

[0021] Preferably, the raw materials of the modified wool fiber include the following components in parts by weight: 8-12 parts of wool fiber, 1-6 parts of carboxymethyl chitosan, and 0.5-1.5 parts of a cross-linking agent.

[0022] Typically, but not limited to, the crosslinking agent is an aziridine crosslinking agent.

[0023] By adopting the above technical solution, the modified wool fiber prepared by using the above components has a better effect and a better synergistic effect with other components, which can improve the compressive strength and stability of the sludge after solidification.

[0024] Preferably, the modified wool fiber is prepared by the following steps:

[0025] Preparation of modified wool fiber: carboxymethyl chitosan is dissolved in acetic acid solution to form a carboxymethyl chitosan solution, and then wool fiber and a crosslinking agent are added, and the reaction is carried out at 40-60° C. for 24-36 hours to obtain the modified wool fiber.

[0026] By adopting the above technical solution, the wool fibers are modified under milder conditions, which causes less damage to the wool fibers, thereby saving costs and improving the yield of the modified wool fibers.

[0027] The second aspect includes the following steps:

[0028] S1: Mechanically dewatering or air-drying and crushing the silt material; dissolving silicon phosphate in water to obtain an auxiliary solution;

[0029] S2: mixing the auxiliary solution obtained in step S1 with water glass and sulfonated oil to obtain a non-calcium-based sludge solidifying agent, and then stirring the non-calcium-based sludge solidifying agent and the sludge material obtained in step S1 and allowing them to stand;

[0030] S3: backfilling and mechanically compacting the solidified soil obtained in step S2;

[0031] S4: The solidified soil obtained by filling in step S3 is sprinkled with water, covered, and heat-insulated to obtain solidified silt.

[0032] By adopting the above technical solution, the solidified sludge obtained has better ecological properties, good compressive strength and water stability, and has a wider range of applications.

[0033] In summary, this application has the following beneficial effects:

[0034] 1. Using unconventional auxiliary admixture water glass as the solidifying agent of sludge, by optimizing the modulus of water glass and the synergistic effect of water glass with anionic surfactants, auxiliary solidifying agents, etc., the non-calcium-based sludge solidifying agent has better solidification effect and good ecological properties, thereby improving the application range of the solidified sludge.

[0035] 2. Silicon phosphate is selected as the auxiliary curing agent. The silt solidifies at a uniform speed, the compressive strength and stability of the solidified silt are good, and the ecological properties of the silt are better.

[0036] 3. Sodium lignin sulfonate and modified wool fiber are added to further improve the curing effect of the non-calcium-based sludge curing agent. The cured sludge has better ecological properties and a wider range of applications. DETAILED DESCRIPTION

[0037] The present application is further described in detail below with reference to the embodiments.

[0038] Modified wool fiber

[0039] Preparation Example 1-1: A modified wool fiber is prepared by the following steps:

[0040] Preparation of modified wool fiber: 3.5 g of carboxymethyl chitosan was dissolved in 500 mL of 5% acetic acid solution to obtain a carboxymethyl chitosan solution. 10 g of wool fiber and 1 g of aziridine crosslinking agent were added to the carboxymethyl chitosan solution, and the mixture was reacted at 50°C for 30 h to obtain the modified wool fiber.

[0041] Preparation Example 1-2: A modified wool fiber is prepared by the following steps:

[0042] Preparation of modified wool fiber: 6 g of carboxymethyl chitosan was dissolved in 500 mL of 5% acetic acid solution to obtain a carboxymethyl chitosan solution. 12 g of wool fiber and 1.5 g of aziridine crosslinking agent were added to the carboxymethyl chitosan solution, and the reaction was carried out at 40°C for 36 hours to obtain the modified wool fiber.

[0043] Preparation Example 1-3, a modified wool fiber, is prepared by the following steps:

[0044] Preparation of modified wool fiber: 1 g of carboxymethyl chitosan was dissolved in 500 mL of 5% acetic acid solution to obtain a carboxymethyl chitosan solution. 8 g of wool fiber and 0.5 g of aziridine crosslinking agent were added to the carboxymethyl chitosan solution, and the mixture was reacted at 60°C for 24 h to obtain the modified wool fiber.

[0045] Preparation Example 1-4 is a modified wool fiber, which is different from Preparation Example 1-1 in that carboxymethyl chitosan is replaced by an equal amount of chitosan.

[0046] Preparation Example 1-5, a modified wool fiber, is prepared by the following steps:

[0047] Preparation of modified wool fiber: 3.5 g of carboxymethyl chitosan was dissolved in 500 mL of 5% acetic acid solution to obtain a carboxymethyl chitosan solution. 10 g of wool fiber and 1 g of aziridine crosslinker were added to the carboxymethyl chitosan solution, and the reaction was carried out at 80°C for 12 h to obtain the modified wool fiber (relatively intense reaction conditions).

[0048] Preparation Example 1-6, a modified wool fiber, is prepared by the following steps:

[0049] Preparation of modified wool fiber: 3.5 g of carboxymethyl chitosan was dissolved in 500 mL of 5% acetic acid solution to obtain a carboxymethyl chitosan solution. 10 g of wool fiber and 1 g of aziridine crosslinker were added to the carboxymethyl chitosan solution, and the reaction was carried out at 25°C for 72 h to obtain the modified wool fiber (milder reaction conditions).

[0050] Example

[0051] Example 1, application of a non-calcium-based sludge solidifying agent, adopts the following steps:

[0052] S1: Mechanically dehydrate or air-dry and crush 325 g of silt to a maximum particle size of less than 2 cm and a moisture content of less than 10%; dissolve 1.5 g of silicon phosphate in 72.5 g of water to obtain an auxiliary solution;

[0053] S2: The auxiliary solution prepared in step S1 was mixed with 22.5 g of water glass and 1.5 g of sulfonated oil to obtain a non-calcium-based sludge solidifying agent, and then the non-calcium-based sludge solidifying agent and the sludge material prepared in step S1 were stirred for 15 minutes and allowed to stand for 4 hours;

[0054] S3: backfilling and mechanically compacting the solidified soil obtained in step S2, and controlling the compaction degree to be greater than 95%;

[0055] S4: The solidified soil obtained by filling in step S3 is sprinkled with water, covered, and heat-insulated for 14 days to obtain solidified silt.

[0056] Among them, the modulus of water glass is 2.4.

[0057] Example 2, application of a non-calcium-based sludge solidifying agent, adopts the following steps:

[0058] S1: Mechanically dehydrate or air-dry and crush 350 g of silt soil to a maximum particle size of less than 2 cm and a moisture content of less than 10%; dissolve 2 g of silicon phosphate in 75 g of water to obtain an auxiliary solution;

[0059] S2: The auxiliary solution prepared in step S1 was mixed with 30 g of water glass and 2 g of sulfonated oil to obtain a non-calcium-based sludge solidifying agent, and then the non-calcium-based sludge solidifying agent and the sludge material prepared in step S1 were stirred for 15 minutes and allowed to stand for 4 hours;

[0060] S3: backfilling and mechanically compacting the solidified soil obtained in step S2, and controlling the compaction degree to be greater than 95%;

[0061] S4: The solidified soil obtained by filling in step S3 is sprinkled with water, covered, and heat-insulated for 14 days to obtain solidified silt.

[0062] Among them, the modulus of water glass is 2.8.

[0063] Example 3, application of a non-calcium-based sludge solidifying agent, using the following steps:

[0064] S1: Mechanically dehydrate or air-dry and crush 300 g of silt soil to a maximum particle size of less than 2 cm and a moisture content of less than 10%; dissolve 1 g of silicon phosphate in 70 g of water to obtain an auxiliary solution;

[0065] S2: The auxiliary solution prepared in step S1 was mixed with 15 g of water glass and 1 g of sulfonated oil to obtain a non-calcium-based sludge solidifying agent, and then the non-calcium-based sludge solidifying agent and the sludge material prepared in step S1 were stirred for 15 minutes and allowed to stand for 4 hours;

[0066] S3: backfilling and mechanically compacting the solidified soil obtained in step S2, and controlling the compaction degree to be greater than 95%;

[0067] S4: The solidified soil obtained by filling in step S3 is sprinkled with water, covered, and heat-insulated for 14 days to obtain solidified silt.

[0068] Among them, the modulus of water glass is 2.0.

[0069] Example 4, application of a non-calcium-based sludge solidifying agent, differs from Example 1 in that, in step S2, the auxiliary solution is obtained by dissolving 1.5 parts of silicon phosphate and 0.75 g of sodium lignin sulfonate in 72.5 g of water.

[0070] In some embodiments, the amount of sodium lignin sulfonate in the non-calcium-based sludge solidifying agent can be 0.5 parts, 0.75 parts, 1 part, or a range consisting of any two of the above values.

[0071] Example 5, application of a non-calcium-based sludge solidifying agent, is different from Example 4 in that the modulus of water glass is 2.3.

[0072] Example 6, application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that the modulus of water glass is 2.5.

[0073] Example 7, application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that silicon phosphate is replaced by an equal amount of sodium fluorosilicate.

[0074] Example 8, application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that silicon phosphate is replaced by an equal amount of polyacrylamide.

[0075] Example 9, an application of a non-calcium-based sludge solidifying agent, is different from Example 4 in that, in step S2, the auxiliary solution obtained in step S1 is mixed with 22.5 g of water glass, 1.5 g of sulfonated oil, and 4.5 g of modified wool fiber to obtain a non-calcium-based sludge solidifying agent, and then the non-calcium-based sludge solidifying agent and the silt material obtained in step S1 are stirred for 15 minutes and allowed to stand for 4 hours.

[0076] The modified wool fiber is derived from Preparation Example 1-1.

[0077] In some embodiments, the amount of modified wool fiber in the non-calcium-based sludge solidifying agent can be 2 parts, 4.5 parts, 7 parts, or a range consisting of any two of the above values. In these embodiments, the modified wool fiber can be any one of Preparation Example 1-1, Preparation Example 1-2, or Preparation Example 1-3.

[0078] Example 10, application of a non-calcium-based sludge solidifying agent, is different from Example 9 in that the modified wool fiber is derived from Preparation Example 1-4.

[0079] Example 11, application of a non-calcium-based sludge solidifying agent, is different from Example 9 in that the modified wool fiber is derived from Preparation Example 1-5.

[0080] Example 12, application of a non-calcium-based sludge solidifying agent, is different from Example 9 in that the modified wool fiber is derived from Preparation Example 1-6.

[0081] Example 13, application of a non-calcium-based sludge solidifying agent, is different from Example 9 in that the modified wool fiber is replaced by an equal amount of unmodified wool fiber.

[0082] Comparative Example

[0083] Comparative Example 1, an application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that the modulus of water glass is 3.3.

[0084] Comparative Example 2, an application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that the modulus of water glass is 1.8.

[0085] Comparative Example 3, an application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that the auxiliary solidifying agent is replaced by other raw materials of the non-calcium-based sludge solidifying agent in parts by weight.

[0086] Comparative Example 4, an application of a non-calcium-based sludge solidifying agent, differs from Example 4 in that the anionic surfactant is replaced by other raw materials of the non-calcium-based sludge solidifying agent in parts by weight.

[0087] Comparative Example 5 is an application of a sludge solidifying agent. The difference from Example 4 is that the added admixtures are only water and 3% (mass ratio of cement to dry soil) of cement.

[0088] Comparative Example 6 is an application of a sludge solidifying agent. The difference from Example 4 is that the added admixtures are only water and 5% (mass ratio of cement to dry soil) of cement.

[0089] Comparative Example 7, an application of a sludge solidifying agent, differs from Example 4 in that the added admixtures are only water and 7% (mass ratio of cement to dry soil) of cement.

[0090] Performance testing

[0091] The performance tests were conducted on the solidified sludge obtained in Examples 1-13 and Comparative Examples 1-8. Each test was conducted in parallel 6 times and the average value was taken. The results are shown in Table 1-3.

[0092] Test 1: According to the "Standard for Geotechnical Test Methods" (GB / T50123-2019), the optimum moisture content was determined, and the dry density and porosity were calculated. The results are shown in Table 1.

[0093] Test 2: Permeability was measured according to the "Standard for Geotechnical Test Methods" (GB / T50123-2019). The results are shown in Table 2. A ring-cut soil sample was prepared using solidified silt and maintained at a constant temperature and humidity of 20°C for 14 days at a humidity greater than 90%. The test was then conducted. The results are shown in Table 2.

[0094] Test 3: The 14-day unconfined compressive strength and water stability coefficient of the solidified silt were measured according to the "Testing Procedures for Inorganic Binder Stabilized Materials for Highway Engineering" (JTJ057-94). The results are shown in Table 3. Cylindrical specimens were prepared from solidified silt and subjected to constant temperature and humidity curing at a humidity greater than 90% and a temperature of 20°C for 14 days before testing. The results are shown in Table 3.

[0095] Table 1 Test results of optimal moisture content, dry density and porosity ratio of solidified sludge

[0096] Group Optimum moisture content / % <![CDATA[Dry density / (g / cm 3 )]]> Porosity Example 1 20.6 1.57 0.64 Example 2 20.1 1.58 0.63 Example 3 20.7 1.6 0.63 Example 4 21.7 1.54 0.67 Example 5 19.9 1.52 0.66 Example 6 18.7 1.53 0.61 Example 7 21.7 1.55 0.66 Example 8 21.4 1.56 0.62 Example 9 20.9 1.44 0.76 Example 10 21.3 1.5 0.7 Example 11 20.8 1.46 0.75 Example 12 20.7 1.44 0.76 Example 13 22.1 1.52 0.69 Comparative Example 1 / / / Comparative Example 2 / / / Comparative Example 3 21.3 1.13 0.8 Comparative Example 4 19.4 1.66 0.71 Comparative Example 5 25.2 1.62 0.68 Comparative Example 6 20.9 1.7 0.62 Comparative Example 7 21.3 1.71 0.6 Comparative Example 8 21.4 1.72 0.58

[0097] Table 2 Test results of permeability coefficient of sludge after solidification

[0098]

[0099]

[0100] Table 3 Test results of unconfined compressive strength and water stability coefficient of solidified sludge

[0101]

[0102]

[0103] From Examples 1-4 and Tables 1-3, it can be seen that the addition of sodium lignin sulfonate can improve the curing efficiency of the non-calcium-based sludge curing agent. The reason is that lignin sulfonate ammonia can increase the cohesion and adhesion between sludge particles, fill the pores after hydrolysis, and improve the density of the sludge, thereby improving the unconfined compressive strength and water stability of the sludge.

[0104] Combining Examples 1-6, Comparative Examples 1-2, and Tables 1-3, it can be seen that when the modulus of water glass is too high or too low, the sludge solidification effect is poor. This is because when the modulus of water glass is too high, the viscosity of water glass is too high, and its fluidity and dispersibility are very poor, making it difficult to consolidate smaller sludge particles, resulting in poor solidification effect. When the modulus of water glass is too low, the strength of the water glass-solidified sludge is too low, and the hydrophilicity is too strong, resulting in poor water stability of the solidified sludge.

[0105] Combining Examples 4, 7-8, and Tables 1-3, it can be seen that using silicon phosphate as an auxiliary curing agent rather than other components can produce better auxiliary curing effects. This is because, although sodium fluorosilicate has similar auxiliary curing effects to silicon phosphate, sodium fluorosilicate has certain biofouling properties, which can have a certain impact on the subsequent application and reprocessing of the solidified sludge. Compared with the organic auxiliary curing agent polyacrylamide, silicon phosphate has a moderate hydrolysis rate and can steadily increase the hardening speed of water glass. As a result, the solidified sludge has better unconfined compressive strength.

[0106] In combination with Example 4, Examples 9-13 and Tables 1-3, it can be seen that the non-calcium-based sludge solidifying agent added with wool fiber or modified wool fiber has a better solidification effect on sludge, and the wool fiber modified with carboxymethyl chitosan has a better solidification effect on sludge. The reason is that the wool fiber is modified with carboxymethyl chitosan, which is also a natural substance and can gradually decompose into nutrients in the soil, improving the ecological properties of the soil. After the wool fiber is modified with carboxymethyl chitosan, cationic groups such as carboxyl are introduced, which better combine with negatively charged sludge particles and can form complexes with calcium ions and magnesium ions in the sludge to increase the compressive strength of the sludge. The wool fiber modified with carboxymethyl chitosan has a stronger hydrophilicity and can better cooperate with lignocellulose to improve the water stability of the sludge.

[0107] In combination with Example 4, Comparative Examples 3-4 and Tables 1-3, it can be seen that after removing the auxiliary curing agent or anionic surfactant, the curing effect of the non-calcium-based sludge curing agent on the sludge is greatly reduced. The reason is that the hardening speed of water glass itself is slow and its binding ability with the surface of the sludge particles is poor. After adding the auxiliary curing agent and the anionic surfactant, the hardening speed of water glass is increased and the binding ability with the sludge particles is enhanced. The sludge cured by the non-calcium-based sludge curing agent has both good unconfined compressive strength and good water stability.

[0108] In combination with Examples 1-4, Comparative Examples 5-8 and Tables 1-3, it can be seen that compared with the traditional calcium-based curing agent "cement", the silt after curing in this application has the characteristics of low dry density, large porosity, and large permeability coefficient, which greatly improves the compaction of the soil and improves the ecology of the soil; and the unconfined compressive strength and water stability of the cured silt of this application are greatly improved compared with before curing, and can be further applied to foundation soil backfill or ecological soil reconstruction projects with appropriate foundation strength requirements, which greatly improves the application range of the cured silt.

[0109] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make non-creative modifications to the present embodiment as needed, but as long as they are within the scope of the claims of the present application, they are protected by the patent law.

Claims

1. A non-calcium-based sludge solidifying agent, characterized in that: The invention comprises the following raw materials in parts by weight: 15-30 parts of water glass, 1-2 parts of an auxiliary curing agent, 1-2 parts of sulfonated oil, 0.5-1 part of sodium lignin sulfonate, and 70-75 parts of water, wherein the modulus of the water glass is 2.3-2.5; the raw materials also include modified wool fiber, wherein the weight ratio of the modified wool fiber to the water glass is (2-7):(15-30), and the modified wool fiber is prepared by grafting carboxymethyl chitosan onto wool fiber. The raw materials comprise, by weight, 8-12 parts of wool fiber, 1-6 parts of carboxymethyl chitosan, and 0.5-1.5 parts of an aziridine crosslinking agent. The preparation method comprises: dissolving the carboxymethyl chitosan in an acetic acid solution to form a solution, adding the wool fiber and the crosslinking agent, and reacting at 40-60°C for 24-36 hours.

2. A non-calcium-based sludge solidifying agent according to claim 1, characterized in that: The auxiliary curing agent is selected from one of silicon phosphate, zinc phosphate, magnesium phosphate, sodium fluorosilicate, zinc chloride, ammonium chloride, polyacrylic acid, polyacrylamide, and polyvinyl alcohol.

3. A non-calcium-based sludge solidifying agent according to claim 1, characterized in that: The auxiliary curing agent is selected from one of silicon phosphate, zinc phosphate, magnesium phosphate, sodium fluorosilicate, zinc chloride and ammonium chloride.

4. A non-calcium-based sludge solidifying agent according to claim 3, characterized in that: The auxiliary curing agent is selected from silicon phosphate.

5. The use of a non-calcium-based sludge solidifying agent in sludge according to claim 1, characterized in that: The steps include: S1: Mechanically dehydrate or air-dry and crush 325 g of silt soil to a maximum particle size of less than 2 cm and a moisture content of less than 10%; dissolve 1.5 g of silicon phosphate and 0.75 g of sodium lignin sulfonate in 72.5 g of water to obtain an auxiliary solution; S2: The auxiliary solution prepared in step S1 is mixed with 22.5 g of water glass, 1.5 g of sulfonated oil, and 4.5 g of modified wool fiber to obtain a non-calcium-based sludge solidifying agent, and then the non-calcium-based sludge solidifying agent and the sludge material prepared in step S1 are stirred for 15 minutes and allowed to stand for 4 hours; S3: backfilling and mechanically compacting the solidified soil obtained in step S2 to control the compaction degree to be greater than 95%; S4: Step S3 is completed to fill the solidified soil, sprinkle water, cover and maintain for 14 days to obtain solidified silt; Among them, the modulus of water glass is 2.4; The modified wool fiber was prepared by dissolving 3.5 g of carboxymethyl chitosan in 500 mL of 5% acetic acid solution to obtain a carboxymethyl chitosan solution, adding 10 g of wool fiber and 1 g of aziridine crosslinker to the carboxymethyl chitosan solution, and reacting at 50° C. for 30 h to obtain the modified wool fiber.

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