Filtration-increasing composite curing agent and application thereof in solid-filtration combined technology

Abstract

The invention discloses a filtration-increasing composite curing agent and application thereof in a solid-filtration combined technology, and belongs to the technical field of soft soil foundation treatment in civil engineering and traffic transportation engineering. The filtration-increasing composite curing agent is composed of a gelling agent, a retarder and a hydrophobic material, and is added into the sludge for curing the sludge; the sludge comprises sludge dry soil and water, and the water content in the sludge is 70-80%; the doping amount of the gelling agent is 6%-12% of the mass of the sludge, the doping amount of the retarder is 0.05%-0.2% of the mass of the gelling agent, and the doping amount of the hydrophobic material is 0.05%-0.2% of the mass of the dry sludge soil. According to the invention, a solid-filtration combined technology is introduced into sludge treatment, and a composite curing agent with a filtration increasing characteristic is adopted, so that the purposes of further enhancing the vacuum dehydration performance of the solidified soil, improving the solid-filtration treatment effect and reducing the cost can be achieved, and the solid-filtration combined technology is optimized.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of foundation treatment in civil engineering and transportation engineering, and relates to a filter-increasing composite solidifying agent and application of the filter-increasing composite solidifying agent in a solidification-filtering combined technology. BACKGROUND

[0002] The bottom silt of rivers and lakes has the characteristics of high water content, high compressibility and low strength, and is difficult to handle. In the process of road construction, the traditional treatment method is to dredge and backfill the ponds on the route, which not only increases the engineering cost, but also occupies a large amount of land resources and causes certain pressure on the local environment. On the other hand, bored piles are often used in high-speed bridge sections, and a large amount of waste mud will be generated during construction, which will cause serious environmental problems if directly discharged, and is not suitable for use, and often needs to be stored and treated on the construction site. The consistency of these waste muds is very large, and it is difficult to sink naturally. The untreated mud pool yard not only occupies a large amount of land, but also may cause secondary pollution such as water pollution. The treatment method of natural settlement and drying after being transported to the landfill site by tank trucks is not only backward, inefficient and high in cost, but also causes leakage during transportation, affecting the urban environment.

[0003] In-situ solidification can treat river, lake and pond silt and waste mud on site, solving the problems of resource waste and environmental pollution during transportation and yard treatment of the discarded soil, but high water content silt needs to be solidified with a high cement content to meet the design requirements, which is high in resource and energy consumption, and the cement production process emits a large amount of CO2, dust and other toxic gases, which is not conducive to environmental protection. The in-situ solidification-extraction combined process can reduce the water content of solidified soil, reduce the void ratio and densify the soil body through vacuum dewatering, achieve strength improvement and reduce cement content, and further reduce energy consumption, which is an optimized method for in-situ solidification of river and pond silt and waste mud.

[0004] However, the vacuum dewatering efficiency decreases with time due to the cement hydration reaction to fill the pores. In addition, clay minerals are hydrophilic, and part of the water molecules are constrained on the particle surface to form a hydration film, which does not participate in the hydration reaction and is difficult to remove, and is present in the solidified soil, affecting the strength improvement.

[0005] Patent CN116354673A relates to a composite curing agent and a curing combined vacuum dewatering in-situ curing method. The composite curing agent for high water content sludge is prepared by sludge, cement and retarder according to the following mass percentage. The cement mixing amount is 416% of the mass of sludge, and the retarder mixing amount is 0.05% to 0.2% of the mass of cement. Patent CN113845341A relates to a composite curing agent for river pond sludge and a curing method. The composite curing agent for river pond sludge is prepared by sludge, cement and desulfurization ash according to the following mass percentage. The cement mixing amount is 6% to 8% of the mass of sludge, and the desulfurization ash mixing amount is 15% to 20% of the mass of cement. However, the above patents cannot solve the core problems of high water content sludge combined water difficult to remove, short dewatering window period and limited strength improvement. SUMMARY

[0006] Based on the shortcomings of the prior art, the purpose of the present application is to provide a filter-enhanced composite curing agent and its application in filter-curing combined technology to solve the problem of in-situ utilization of river sludge and waste slurry.

[0007] The stronger the hydrophilicity of clay, the thicker the hydration film, the more residual water in the cured soil, and the smaller the strength growth. Therefore, the cement retarding and clay hydrophilic performance modification can be considered to improve the dewatering efficiency and optimize the filter-curing process.

[0008] The surfactant has both "hydrophilicity" and "lipophilicity", which can change the hydrophilicity of clay minerals. The surfactant commonly used for hydrophobic modification is cationic surfactant (such as quaternary ammonium salt), anionic surfactant (such as sulfonate) and the like. After adding ionic surfactant to sludge and waste slurry, the hydrophilic head and the surface of clay particles exchange ions, adsorb and other physical and chemical effects, which can effectively reduce the negative charge on the surface of particles, promote the aggregation of particles to form flocs; the hydrophobic tail long chain covers the surface of particles to form a hydrophobic layer to hinder water molecules from approaching, and at the same time, the high molecular chain is entangled on the surface of soil particles and in the pores to form a network membrane structure, so that the dispersed soil particles form stable aggregates, thereby improving the strength of the soil. Compared with anionic surfactants, cationic surfactants have stronger charge neutralization ability and better hydrophobic modification effect. Therefore, quaternary ammonium salt cationic surfactant is selected as the hydrophobic material, which can modify the hydrophobic properties of sludge and waste slurry, reduce the thickness of the water film of mineral particles, increase the internal structural strength of particles, make the soil particles coagulate to form larger flocs, increase the pores between particles, improve the dewatering performance of soil, and positively promote the vacuum dewatering.

[0009] Retarders extend the initial and final setting times of cement, allowing the mixture to maintain its plasticity for a longer period, facilitating pouring or transportation, thereby improving construction efficiency and quality. They are widely used in concrete engineering. Common retarders include tartaric acid, lignin sulfonates, and sugars. Considering the potential for enhanced modification through compounding with quaternary ammonium salts, lignin sulfonates are chosen. In combined solid-filtration processes, adding retarders can extend the vacuum filtration window of the solidified soil, increase dewatering capacity, and improve the solid-filtration effect.

[0010] This invention utilizes calcium lignosulfonate as a retarder to delay setting time, increase the vacuum filtration window, and improve dewatering efficiency. It employs hexadecyl ammonium bromide to alter the hydrophobic properties of clay minerals, thinning the bound water film and simultaneously acting as a flocculator, changing the properties and structure of the solidified soil and making it easier to drain. Using this enhanced composite solidifying agent, combined with a solid-filtration integrated process, accelerates filtration efficiency, increases total dewatering volume, enhances the strength of the solidified soil, and enables on-site solidification of river and pond sediments and waste mud, demonstrating significant engineering value.

[0011] This invention provides the following technical solutions: Technical solution 1 provides a filter-enhancing composite solidifying agent, composed of a gelling agent, a retarder, and a hydrophobic material, which is added to sludge for solidification. The sludge comprises dry sludge and water, with a water content of 70-80%, preferably 76%. The gelling agent is added at 6%-12% of the sludge mass, the retarder at 0.05%-0.2% of the gelling agent mass, and the hydrophobic material at 0.05%-0.2% of the dry sludge mass.

[0012] Furthermore, the cementitious agent is cement, preferably P.O42.5 cement; Furthermore, the retarder is calcium lignosulfonate, and the molecular formula of calcium lignosulfonate is C2. 20 H 24 CaO 10 S2, abbreviated as lignocalcium; Furthermore, the hydrophobic material is a cationic surfactant, preferably hexadecyltrimethylammonium bromide, the molecular formula of which is C1. 19 H 42 BrN, abbreviated as CTAB.

[0013] Technical solution 2 provides the application of the above-mentioned filter-enhancing composite curing agent in sludge solidification, the application being based on a combined solidification and filtration technology. The sludge solidification is divided into in-situ solidification or ex-situ solidification, and the filter-enhancing composite curing agent provided by this invention is preferably used for in-situ sludge solidification.

[0014] In-situ solidification is a treatment method for river and pond bottom sludge and waste mud. It eliminates the need to excavate and transfer the sludge from its original site. The solidifying agent is directly added to the sludge in its original location (within the river, pond, or mud pit), mixed, and then solidified using processes such as vacuum filtration. It has the advantages of eliminating the need for transportation, minimizing site damage, and reducing costs, making it suitable for treating large areas and shallow surface sludge. Ex-situ solidification, on the other hand, requires excavating the sludge from its original site (such as a river or pond) using excavators and dredging equipment, transporting it to a specialized treatment site (such as a solidification workshop or temporary storage area), and then performing operations such as mixing the solidifying agent and dehydration solidification. It is suitable for scenarios with severe sludge pollution (requiring centralized pollution control) and limited in-situ treatment conditions (such as narrow sites or complex underground pipelines).

[0015] Furthermore, the silt provided is selected from river and pond bottom mud, waste mud, and silt from in-situ remediation areas awaiting treatment. The method is as follows: Construction preparation – surveying and setting out – preparation of curing agent slurry – mixing with mixer – site leveling with excavator – installation of drainage body – installation of vacuum filtration equipment – ​​removal of drainage device; The specific steps are as follows: 1) Drain the standing water in the in-situ remediation area to be treated, and clean up the debris (such as large plant roots in the pond) in the in-situ remediation area; investigate the area and depth of silt, mark the lines, and divide the in-situ remediation area into zones (blocks); take samples to determine the initial moisture content, wet density and liquid limit of the soil in the blocks, and calculate the required amount of each component of the filter-enhancing composite curing agent and the amount required for each block; 2) Weigh the gelling agent and retarder according to the calculation results of step 1) to prepare a mixed slurry, weigh the hydrophobic material separately to prepare a hydrophobic slurry, then mix the mixed slurry and the hydrophobic slurry, add water according to the design moisture content and stir evenly to make a curing agent slurry, and transport it to the mixing head through the mud pump. Use the mixing head to add the curing agent slurry into the block, and stir the sludge and curing agent in the block vertically up and down evenly. 3) After mixing, use an excavator vibrating plate to initially level the site. Bury drainage bodies (such as plastic drainage boards) at certain intervals in the solidified area, with a burial depth equal to the treatment depth of silt and waste mud. Connect the drainage bodies and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 12-24 hours. 4) After the entire area to be cured has been mixed and the water has been pumped out, remove the drainage device, level the surface, and cure for at least 28 days.

[0016] Preferably, in step 2), the designed moisture content is ≥ 1.4 times the silt liquid limit, and the combined filtration process ensures the controllability of the actual solidified soil moisture content.

[0017] Preferably, in step 2), the solidification area is constructed in blocks using a method of simultaneous solidification and advancement. Each construction area is 5m × 10m in size, with an overlap width of not less than 5cm between adjacent blocks. After the solidification construction of each block is completed, the entire area is stirred.

[0018] Preferably, in step 2), the lifting or lowering rate of the stirring head is 10~20 s / m, the curing agent spraying rate is controlled at 70~160 kg / min, and the number of up-and-down stirring times at each stirring position is 2 or 4.

[0019] Preferably, in step 3), the spacing of the buried drainage bodies is selected to be 0.8m to 1.5m according to the site conditions.

[0020] Preferably, in step 3), the total time for installing the mixing, leveling, and drainage equipment should be controlled within 2 hours, and vacuum pumping should be started immediately after installation.

[0021] Compared with the prior art, the present invention has at least the following improvements and beneficial effects: This invention is the first to introduce hydrophobic materials and retarder into a combined solid-filtration technology. By utilizing the ability of hydrophobic materials to reduce the thickness of the clay-bound water film, the dewatering effect of the solidification-filtration combined process is improved, thus enhancing the solidification effect. Specifically, this can be summarized in the following aspects: (1) This invention introduces hydrophobic materials and retarder into the in-situ solidification-filtration combined technology for the first time. Quaternary ammonium salt is used to hydrophobically modify clay particles to play a flocculation role. Combined with retarder to extend cement setting time, it can effectively improve the efficiency of vacuum dehydration and the strength of solidified soil, reduce construction difficulty, and appropriately reduce cement usage and project cost while meeting strength requirements.

[0022] (2) This invention develops integrated and optimized construction equipment that integrates curing agent preparation (cement slurry mixer, hydrophobic solution preparation machine), in-situ mixing (excavator mixer) and vacuum drainage system. This not only simplifies the construction process and improves construction efficiency, but also maximizes dewatering efficiency and accelerates the process of improving the strength of the solidified soil. The construction equipment can be reused, which is beneficial to saving costs.

[0023] (3) The vacuum pumping time of the material-process-equipment three-dimensional collaborative system constructed by the present invention is shorter than that of the traditional process, the strength is stable for 28 days and there is no cracking problem, and the overall cost is reduced; it avoids secondary pollution during sludge transportation and achieves the unity of efficient treatment, structural stability and economic and environmental protection. Attached Figure Description

[0024] Figure 1 This is a graph showing the variation of vacuum dehydration effect of curing agents with different material compositions according to the present invention; Figure 2This is a graph showing the variation of unconfined compressive strength in vacuum-filtered soil samples with curing agents of different material compositions according to the present invention; Figure 3 This is a graph showing the variation of unconfined compressive strength in solidified filter soil samples with different amounts of hydrophobic materials according to the present invention; Figure 4 This is a schematic diagram illustrating the application of the solid-filtration combined technology of the present invention; In the diagram: 1. Hardener tank, 2. Retarder tank, 3. Hydrophobic material tank, 4. Water tank, 5. Cement slurry mixer, 6. Hydrophobic solution preparation machine, 7. Slurry pool, 8. Slurry pump, 9. Excavator mixer, 10. In-situ repair area, 11. Vacuum drainage system, 12. Vacuum pumping device. Detailed Implementation

[0025] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be described in detail below with reference to specific embodiments. It should be noted that the following embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be pointed out that those skilled in the art can make several modifications and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0026] This invention provides a composite solidification agent for enhanced filtration and its application method in combined solid-filtration technology. Calcium lignosulfonate is used as a retarder to delay setting time, increase the vacuum filtration window, and improve dewatering efficiency. Hexadecyl ammonium bromide is used to modify the hydrophobic properties of clay minerals, resulting in a thinner bound water film and flocculation, thus altering the properties and structure of the solidified soil and making it easier to drain. Combined with vacuum filtration, this accelerates filtration efficiency, increases total dewatering volume, and enhances the strength of the solidified soil. This invention effectively integrates hydrophobic materials and retarders into combined solid-filtration technology, enhancing both dewatering and solidification effects, and providing technical support for the on-site solidification treatment of river and pond sediments and waste mud.

[0027] Unless otherwise specified, the source of all raw materials used in this invention is not particularly limited; they can be purchased from the market or prepared using conventional methods known to those skilled in the art. The soil sample used in the specific implementation method was silt from the bottom of ponds in the Lixiahe area of ​​the Ningyan Expressway. Its basic physicochemical properties are shown in Table 1 below. The cement used was Conch brand P.O42.5 cement, the retarder was calcium lignosulfonate, and the hydrophobic material was hexadecyltrimethylammonium bromide. The main components are shown in Table 2.

[0028] Table 1 Basic physical properties of soil samples Table 2. Main components and content of retarder and hydrophobic material The following embodiments are based on a solid-filtration combined technology device, and a schematic diagram of the device is shown below. Figure 4 As shown, the equipment includes: a curing agent tank 1, a retarding material tank 2, a hydrophobic material tank 3, a water tank 4, a cement slurry mixer 5, a hydrophobic solution preparation machine 6, a slurry pool 7, a slurry pump 8, an excavator mixer 9, an in-situ repair area 10, a vacuum drainage system 11, and a vacuum pumping device 12.

[0029] The connections and collaboration between the components are as follows: The curing agent provided by the curing agent tank 1, the retarding material provided by the retarding material tank 2, and the water provided by the water tank 4 enter the cement slurry mixer 5 together and are stirred to form a cement slurry containing retarding components; the slurry then flows into the slurry pool 7 for temporary storage.

[0030] The hydrophobic material provided by the hydrophobic material tank 3 and the water provided by the water tank 4 enter the hydrophobic solution preparation machine 6 to prepare a hydrophobic solution, which provides raw materials for the hydrophobic modification of sludge.

[0031] The mixed slurry temporarily stored in the slurry tank 7 is transported by the slurry pump 8 and, together with the excavator mixer 9, injected into the sludge in the in-situ repair area 10. The excavator mixer 9 forcibly mixes the sludge and slurry, so that the curing agent, retarder and hydrophobic material are evenly dispersed in the sludge, thus completing the composite modification of the sludge.

[0032] A vacuum drainage system 11 is laid in the in-situ remediation area 10, and a vacuum pumping device 12 provides vacuum power for the system. Through the negative pressure, the water in the modified sludge is quickly extracted, promoting the efficient solidification of the sludge and improving the treatment efficiency and final solidification effect.

[0033] Comparative Example 1 A cement-based curing agent is added to sludge for sludge curing. The cement is added at 8% of the sludge mass, with the remainder being 0%.

[0034] This example also provides a method for applying the composite curing agent in solid-filtration combined technology for sludge solidification, used to treat river and pond bottom sludge, including the following steps: 1) Divide the curing area into blocks, each block being 5 m × 10 m. The curing and advancing process should be carried out simultaneously. There should be an overlap width of no less than 5 cm between adjacent blocks to avoid missing any areas. After the curing of each block is completed, the entire area should be thoroughly stirred. 2) With a cement content of 8% of the silt mass, the cement slurry is mixed with water at the designed moisture content to make a curing agent slurry. The slurry is then pumped to the mixing head, and the mixing head is used to vertically mix the silt and curing agent in the block evenly. The lifting or lowering speed of the mixing head is controlled at 10~20 s / m, the curing agent spraying speed is controlled at 70~160 kg / min, and the number of up and down mixing times at each mixing position is not less than 2.

[0035] 3) After mixing, install plastic drainage boards at 0.5 m intervals in the solidification area, with the burial depth being the sludge treatment depth. Connect the plastic drainage boards and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane, and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 24 hours.

[0036] 4) After the entire area to be cured has been stirred and the water has been pumped out, level it and cure it for more than 28 days.

[0037] Comparative Example 2: Cement + Calcium Lignosulfonate (excluding CTAB) A composite curing agent is disclosed, comprising cement and calcium lignosulfonate, which is added to sludge for curing the sludge. The cement content is 8% of the sludge mass, and the calcium lignosulfonate content is 0.2% of the cement mass.

[0038] This example also provides a method for applying the composite curing agent in solid-filtration combined technology for sludge solidification, used to treat river and pond bottom sludge, including the following steps: 1) Divide the curing area into blocks, each block being 5 m × 10 m. The curing and advancing process should be carried out simultaneously. There should be an overlap width of no less than 5 cm between adjacent blocks to avoid missing any areas. After the curing of each block is completed, the entire area should be thoroughly stirred. 2) Mix cement slurry at a ratio of 8% cement content to sludge mass and 0.2% calcium lignosulfonate content to cement mass. Add water according to the designed moisture content and stir evenly to make curing agent slurry. Transport the slurry to the mixing head through a mud pump. Use the mixing head to vertically stir the sludge and curing agent in the block evenly. Control the lifting or lowering speed of the mixing head at 10~20s / m, control the curing agent spraying speed at 70~160 kg / min, and stir up and down at each mixing position no less than 2 times.

[0039] 3) After mixing, install plastic drainage boards at 0.5 m intervals in the solidification area, with the burial depth being the sludge treatment depth. Connect the plastic drainage boards and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane, and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 24 hours.

[0040] 4) After the entire area to be cured has been stirred and the water has been pumped out, level it and cure it for more than 28 days.

[0041] Comparative Example 3: Cement + CTAB (without calcium lignosulfonate) A composite curing agent, comprising cement and CTAB, is added to silt for silt curing. The cement content is 8% of the silt mass, and the CTAB content is 0.1% of the dry silt mass.

[0042] This example also provides a method for applying the composite curing agent in solid-filtration combined technology for sludge solidification, used to treat river and pond bottom sludge, including the following steps: 1) Divide the curing area into blocks, each block being 5 m × 10 m. The curing and advancing process should be carried out simultaneously. There should be an overlap width of no less than 5 cm between adjacent blocks to avoid missing any areas. After the curing of each block is completed, the entire area should be thoroughly stirred. 2) Prepare cement slurry with a cement content of 8% of the silt mass and prepare CTAB slurry separately with a CTAB content of 0.1% of the dry silt mass. Then mix the cement slurry and the hydrophobic material (CTAB) slurry, add water according to the designed moisture content and stir evenly to make a curing agent slurry. Transport the slurry to the mixing head through a mud pump. Use the mixing head to vertically stir the silt and curing agent in the block evenly. The lifting or lowering speed of the mixing head is controlled at 10~20 s / m, the curing agent spraying speed is controlled at 70~160 kg / min, and the number of up and down stirring times at each mixing position is not less than 2.

[0043] 3) After mixing, install plastic drainage boards at 0.5 m intervals in the solidification area, with the burial depth being the sludge treatment depth. Connect the plastic drainage boards and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane, and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 24 hours.

[0044] 4) After the entire area to be cured has been stirred and the water has been pumped out, level it and cure it for more than 28 days.

[0045] Example 1: Cement + Calcium Lignosulfonate + CTAB A filter-enhancing composite curing agent is disclosed, comprising cement, calcium lignosulfonate, and CTAB. The curing agent is added to sludge for sludge curing. The cement content is 8% of the sludge mass, the calcium lignosulfonate content is 0.2% of the cement mass, and the cetyltrimethylammonium bromide (CTAB) content is 0.1% of the dry sludge mass.

[0046] This example also provides a method for applying the aforementioned filter-enhancing composite solidifying agent in solid-filtration combined technology for sludge solidification, used to treat river and pond bottom sludge, including the following steps: 1) Divide the curing area into blocks, each block being 5 m × 10 m. The curing and advancing process should be carried out simultaneously. There should be an overlap width of no less than 5 cm between adjacent blocks to avoid missing any areas. After the curing of each block is completed, the entire area should be thoroughly stirred. 2) Mix cement slurry at a ratio of 8% cement content and 0.2% calcium lignosulfonate content. Prepare slurry separately at a ratio of 0.1% CTAB content and 0.1% dry slurry content. Then mix cement slurry and hydrophobic material slurry, add water according to the designed moisture content and stir evenly to make curing agent slurry. Transport the slurry to the mixing head through a mud pump. Use the mixing head to vertically stir the slurry and curing agent in the block evenly. Control the lifting or lowering speed of the mixing head at 10~20 s / m, control the curing agent spraying speed at 70~160 kg / min, and stir at each mixing position at least twice.

[0047] 3) After mixing, install plastic drainage boards at 0.5 m intervals in the solidification area, with the burial depth being the sludge treatment depth. Connect the plastic drainage boards and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane, and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 24 hours.

[0048] 4) After the entire area to be cured has been stirred and the water has been pumped out, level it and cure it for more than 28 days.

[0049] Example 2: Cement + Calcium Lignosulfonate + CTAB A filter-enhancing composite curing agent is disclosed, comprising cement, calcium lignosulfonate, and CTAB. The curing agent is added to sludge for sludge curing. The cement content is 8% of the sludge mass, the calcium lignosulfonate content is 0.2% of the cement mass, and the cetyltrimethylammonium bromide (CTAB) content is 0.2% of the dry sludge mass.

[0050] This example also provides a method for applying the aforementioned filter-enhancing composite solidifying agent in solid-filtration combined technology for sludge solidification, used to treat river and pond bottom sludge, including the following steps: 1) Divide the curing area into blocks, each block being 5 m × 10 m. The curing and advancing process should be carried out simultaneously. There should be an overlap width of no less than 5 cm between adjacent blocks to avoid missing any areas. After the curing of each block is completed, the entire area should be thoroughly stirred. 2) Mix cement slurry at a ratio of 8% cement content and 0.2% calcium lignosulfonate content. Prepare slurry separately at a ratio of 0.2% CTAB content and 0.2% dry silt content. Then mix cement slurry and hydrophobic material slurry, add water according to the designed moisture content and stir evenly to make curing agent slurry. Transport the slurry to the mixing head through a mud pump. Use the mixing head to vertically stir the silt and curing agent in the block evenly. Control the lifting or lowering speed of the mixing head at 10~20 s / m, control the curing agent spraying speed at 70~160 kg / min, and stir at each mixing position at least twice.

[0051] 3) After mixing, install plastic drainage boards at 0.5 m intervals in the solidification area, with the burial depth being the sludge treatment depth. Connect the plastic drainage boards and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane, and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 24 hours.

[0052] 4) After the entire area to be cured has been stirred and the water has been pumped out, level it and cure it for more than 28 days.

[0053] Example 3: Cement + Calcium Lignosulfonate + CTAB A filter-enhancing composite curing agent is disclosed, comprising cement, calcium lignosulfonate, and CTAB. The curing agent is added to sludge for sludge curing. The cement content is 8% of the sludge mass, the calcium lignosulfonate content is 0.2% of the cement mass, and the cetyltrimethylammonium bromide (CTAB) content is 0.05% of the dry sludge mass.

[0054] This example also provides a method for applying the aforementioned filter-enhancing composite solidifying agent in solid-filtration combined technology for sludge solidification, used to treat river and pond bottom sludge, including the following steps: 1) Divide the curing area into blocks, each block being 5 m × 10 m. The curing and advancing process should be carried out simultaneously. There should be an overlap width of no less than 5 cm between adjacent blocks to avoid missing any areas. After the curing of each block is completed, the entire area should be thoroughly stirred. 2) Mix cement slurry at a ratio of 8% cement content and 0.2% calcium lignosulfonate content. Prepare slurry separately at a ratio of 0.05% CTAB content and 0.05% dry silt content. Then mix cement slurry and hydrophobic material slurry, add water according to the designed moisture content and stir evenly to make curing agent slurry. Transport the slurry to the mixing head through a mud pump. Use the mixing head to vertically stir the silt and curing agent in the block evenly. Control the lifting or lowering speed of the mixing head at 10~20 s / m, control the curing agent spraying speed at 70~160 kg / min, and stir at each mixing position at least twice.

[0055] 3) After mixing, install plastic drainage boards at 0.5 m intervals in the solidification area, with the burial depth being the sludge treatment depth. Connect the plastic drainage boards and the water collection pipe with a hose, and connect the water collection pipe to the water circulation pump. Then lay a vacuum pre-compression membrane, and seal the edges to ensure that the vacuum degree of the entire pumping area is maintained above 80 kPa. Turn on the vacuum pump to pump water for 24 hours.

[0056] 4) After the entire area to be cured has been stirred and the water has been pumped out, level it and cure it for more than 28 days.

[0057] The components and contents of the above embodiments are summarized in Table 3.

[0058] Table 3 Summary of components in the examples and comparative examples The results of the above embodiments and comparative examples are characterized as follows: Different comparative proportions and examples of sludge + solidifying agent mixtures were taken and thoroughly stirred using a stirrer. The prepared solidified soil was then placed into a φ5cm×10cm solid-filtration unit model for vacuum filtration until virtually no water was removed, and the process time was recorded. The vacuum dewatering results are as follows: Figure 1 As shown in the figure. The prepared solidified soil samples were placed in a curing room and cured for 7 days, 14 days, and 28 days, and then unconfined compressive strength tests were conducted. The results are as follows. Figures 2-3 As shown.

[0059] Depend on Figure 1 As can be seen, the total dewatering amount of Comparative Example 1 (cement alone) was relatively low at 133g, which was used as a benchmark for comparison; the total dewatering amount of Comparative Example 2 (cement and calcium lignosulfonate compound) was 152g, an increase of 14%; the total dewatering amount of Comparative Example 3 (cement and CTAB compound) was 172g, an increase of 29%; and the total dewatering amount of Example 1 (cement, calcium lignosulfonate, and CTAB compound) was 194g, an increase of 46%. It is evident that the introduction of retarders and hydrophobic materials into the curing agent can enhance the vacuum dewatering performance of the solidified soil.

[0060] Depend on Figure 2As can be seen, compared with the 28-day unconfined compressive strength of the solidified soil in Comparative Example 1 (cement alone), the strength of Example 1 (a mixture of cement, calcium lignosulfonate, and CTAB) was increased by approximately 50%; Comparative Example 3 (a mixture of cement and CTAB) was increased by approximately 30%; and Comparative Example 2 (a mixture of cement and calcium lignosulfonate) was increased by approximately 15%. This demonstrates that introducing retarders and hydrophobic materials into the curing agent can effectively improve strength and enhance the solidification and filtration effect.

[0061] Depend on Figure 3 It can be seen that with the increase of CTAB content, the unconfined compressive strength first increases and then decreases. The strength improvement is most significant when the content is 0.1%, and the hydrophobic modification effect is optimal.

[0062] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A filter-aid composite coagulant, characterized by, The application relates to a filter-enhanced composite solidifying agent for silt solidification, which is composed of a gelling agent, a retarder and a hydrophobic material and is added into silt for silt solidification; the silt comprises silt dry soil and moisture, the water content in the silt is 70-80%, the gelling agent is mixed in an amount of 6%-12% of the mass of the silt, the retarder is mixed in an amount of 0.05%-0.2% of the mass of the gelling agent, and the hydrophobic material is mixed in an amount of 0.05%-0.2% of the mass of the silt dry soil.

2. The filter-enhancing composite curing agent according to claim 1, wherein The gelling agent is cement.

3. The filter-enhanced composite curing agent of claim 1, wherein, The retarder is calcium lignosulfonate.

4. The filter-enhanced composite curing agent of claim 1, wherein, The hydrophobic material is a cationic surfactant.

5. The filter-enhanced composite curative of claim 4, wherein, The hydrophobic material is hexadecyl trimethyl ammonium bromide.

6. The filter-enhanced composite solidifying agent according to claim 1 is used in silt solidification.

7. Use of a filter-enhanced composite solidifying agent according to claim 6 in the solidification of sludge, characterized in that, The silt solidification is classified as in-situ solidification or ex-situ solidification.

8. Use of a filter-enhanced composite solidifying agent according to claim 7 in the solidification of sludge, characterized in that, The method for in-situ solidification of the filter-enhanced composite solidifying agent in silt comprises the following steps: 1) clear water in a region to be treated in-situ is pumped out, sundries in the region to be treated in-situ are cleaned, the silt area and depth are surveyed, lofting and marking are performed, the region to be treated in-situ is divided into blocks, the initial water content, wet density and liquid limit of the soil in the blocks are determined by sampling, the required amounts of the components of the filter-enhanced composite solidifying agent and the amounts of the solidifying agent for the blocks are calculated; 2) the gelling agent and the retarder are weighed according to the calculation results of step 1) to prepare mixed slurry, the hydrophobic material is weighed to prepare hydrophobic slurry, then the mixed slurry and the hydrophobic slurry are mixed, water is added to the mixture to uniformly prepare solidifying agent slurry with a designed water content, the solidifying agent slurry is delivered to a stirring head by a mud pump, the solidifying agent slurry is added into the blocks by the stirring head, and the silt in the blocks is uniformly stirred vertically up and down with the solidifying agent; 3) after the stirring is completed, a flat plate is vibrated by an excavator to preliminarily level the site, drainage bodies are embedded in the solidification region at certain intervals, the embedding depth is the treatment depth of the silt and waste mud, the drainage bodies and a water collecting pipe are connected by a hose, the water collecting pipe is connected with a water circulating pump, then a vacuum preloading film is laid, the edges of the film are sealed to ensure that the vacuum degree of the whole water pumping region is maintained to be higher than 80 kPa, and the vacuum pump is turned on to perform vacuum water pumping for 12-24 hours; 4) after the solidification region is completely stirred and pumped, the drainage device is removed, the site is leveled and maintained for more than 28 days.

9. Use of a filter-enhanced composite solidifying agent according to claim 8 for the solidification of sludge, characterized in that, In step 2), the designed water content is 1.4 times of the liquid limit of the silt; in step 2), the solidification region is constructed in a form of advancing while solidifying, and the adjacent blocks are arranged with a lap width of not less than 5 cm; in step 2), the lifting or lowering speed of the stirring head is 10-20 s / m, and the solidifying agent spraying speed is controlled to be 70-160 kg / min.

10. Use of a filter-enhanced composite solidifying agent according to claim 8 in the solidification of silt, characterized in that, In step 3), the interval of the embedded drainage bodies is arranged to be 0.8-1.5 m.

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