Treatment method of shield waste slurry

Abstract

The invention provides a treatment method of shield waste slurry, and relates to the field of slurry treatment. Screening the shield waste slurry to obtain screened slurry and screened solid particles; mixing the screened slurry with a flocculating agent to obtain a mixture, and carrying out filter pressing on the mixture to obtain filter-pressed mud blocks and muddy water; and mixing the muddy water with a pH regulator to obtain treated slurry. Solid particles with large particle sizes are separated out through screening, fine particles such as sludge and clay which cannot be screened are flocculated into clusters through a flocculating agent, then the clusters are filtered into mud blocks with low water content through filter pressing, the mud blocks are separated from muddy water, and then the pH value of residual water needing to be discharged is adjusted, so that muddy water discharge meets the environment-friendly requirement.

Description

Technical Field

[0001] The present application relates to the field of mud treatment, and in particular to a method for treating shield waste mud. Background Art

[0002] In shield construction, slurry usually contains various solid particles and liquids, such as clay, fine sand and other solid particles and water.

[0003] Traditional mud-water separation methods, such as physical, chemical, and biological treatment, each have their own applications in specific areas, but they suffer from drawbacks such as low efficiency, large footprints, and environmental pollution. These issues are particularly prominent in large-scale infrastructure construction, such as shield tunneling, when handling highly concentrated mud.

[0004] Based on this, there is an urgent need to provide a new method for treating shield waste mud to solve the above technical problems. Summary of the Invention

[0005] The purpose of this application is to provide a method for treating shield waste mud to solve the above problems.

[0006] To achieve the above objectives, the present application provides a first aspect of a method for treating shield waste slurry, comprising: Screening the shield waste slurry to obtain screened slurry and screened solid particles; Mixing the sieved mud and a flocculant to obtain a mixture, and filtering the mixture to obtain filtered mud blocks and mud water; The muddy water and the pH regulator are mixed to obtain treated mud.

[0007] Optionally, the diameter of the solid particles in the slurry after screening is less than or equal to 20 μm.

[0008] Optionally, the screening includes: Coarsely screening the waste shield mud to obtain coarse screen oversize and coarse screened mud; The coarsely screened slurry is subjected to cyclone classification.

[0009] Optionally, the diameter of the material on the coarse screen is greater than or equal to 4 mm, and the water content is less than 25 wt%.

[0010] Optionally, the method for treating shield waste slurry satisfies at least one of the following conditions: A. The pH value of the slurry after screening is 6.5-8.5; B. The organic matter content of the slurry after screening is less than or equal to 5%; C. The viscosity of the slurry after screening is less than or equal to 10 Pa·s; D. The density of the slurry after screening is 1.5 g / cm 3 -1.8 g / cm 3 .

[0011] Optionally, the treatment method of the shield waste slurry meets at least one of the following conditions: A. The flocculant includes an inorganic flocculant and / or an organic flocculant; B. The volume of the flocculant is 0.1%-0.6% of the volume of the slurry after screening.

[0012] Optionally, the method for treating waste slurry from shield tunneling meets at least one of the following conditions: A. The inorganic flocculant includes one or more of aluminum sulfate, ferrous sulfate, ferrous sulfate, ferrous chloride, ammonium aluminum sulfate, alum, polyaluminum chloride, sodium aluminate, active silicic acid, lime and magnesium oxide; B. The organic flocculant includes polyacrylamide and / or dodecylamine.

[0013] Optionally, the flocculant includes polyaluminum chloride and anionic polyacrylamide.

[0014] Optionally, the volume ratio of the polyaluminum chloride to the anionic polyacrylamide is 10-50:1-5.

[0015] Optionally, the pH value of the treated mud is 6.5-8.5.

[0016] Compared with the prior art, the advantages of this application include: The method for treating shield waste mud provided in the present application has a simple process. First, large-sized solid particles are separated by screening, and then fine particles of silt, clay, etc. that cannot be screened are flocculated into agglomerates using a coagulant. Then, they are filtered into mud blocks with low water content and separated from mud water. The pH value of the remaining water to be discharged is adjusted so that the mud water discharge meets environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope of the present application.

[0018] Figure 1 This is a physical picture of the material on the separator screen during coarse screening in Example 1; Figure 2 This is a physical picture of the material on the separator screen during the first-level cyclone classification in Example 1. DETAILED DESCRIPTION

[0019] As used herein: "Prepared from" is synonymous with "comprising." As used herein, the terms "comprising," "including," "having," "containing," or any other variations thereof, are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises the listed elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0020] The conjunction "consisting of" excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed, excluding materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0021] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, regardless of whether the range is disclosed alone. For example, when a range of "1 to 5" is disclosed, the described range should be interpreted as including the range "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0022] In these examples, parts and percentages are by mass unless otherwise indicated.

[0023] "Parts by mass" refers to the basic unit of measurement used to express the mass ratio of multiple components. One part can represent any unit of mass, such as 1g or 2.689g. For example, if we say that the parts by mass of component A are a parts and the parts by mass of component B are b parts, this means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, we could say that the mass of component A is aK and the mass of component B is bK (K is an arbitrary number representing a multiplication factor). It's important to note that, unlike parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0024] "And / or" is used to indicate that one or both of the stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0025] The first aspect of the present application provides a method for treating shield waste slurry, comprising: Screening the shield waste slurry to obtain screened slurry and screened solid particles; Mixing the sieved mud and a flocculant to obtain a mixture, and filtering the mixture to obtain filtered mud blocks and mud water; The muddy water and the pH regulator are mixed to obtain treated mud.

[0026] In some embodiments, the diameter of the solid particles in the slurry after screening is less than or equal to 20 μm.

[0027] Optionally, the diameter of the solid particles in the slurry after screening may be 20 μm, 10 μm, 5 μm, 1 μm, 0.01 μm, or any value less than or equal to 20 μm.

[0028] In some embodiments, the screening comprises: Coarsely screening the waste shield mud to obtain coarse screen oversize and coarse screened mud; The coarsely screened slurry is subjected to cyclone classification.

[0029] In some embodiments, a slurry separation device and a filter press are used in synergy to efficiently achieve both slurry separation and solid-liquid separation. The slurry separation device quickly separates solid particles, while the filter press further solidifies these solid particles to form a high-solids filter cake. This synergy improves processing speed and efficiency while reducing processing time.

[0030] In some embodiments, the diameter of the coarse screen oversize is greater than or equal to 4 mm, and the water content is less than 25 wt%.

[0031] Optionally, the diameter of the material on the coarse screen can be 4 mm, 10 mm, 100 mm, 1000 mm or any value greater than or equal to 4 mm, and the water content can be 24 wt%, 20 wt%, 10 wt%, 5 wt%, 1 wt% or any value less than 25 wt%.

[0032] In some embodiments, the method for treating shield waste slurry satisfies at least one of the following conditions: A. The pH value of the slurry after screening is 6.5-8.5; Optionally, the pH value of the slurry after screening can be 6.5, 7, 7.5, 8, 8.5, or any value between 6.5 and 8.5; B. The organic matter content of the slurry after screening is less than or equal to 5%; Optionally, the organic matter content of the slurry after screening may be 5%, 4%, 3%, 2%, 1%, or any value less than 5%; C. The viscosity of the slurry after screening is less than or equal to 10 Pa·s; Optionally, the viscosity of the slurry after screening may be 10 Pa·s, 9 Pa·s, 5 Pa·s, 1 Pa·s, or any value less than 10 Pa·s; D. The density of the slurry after screening is 1.5 g / cm 3 -1.8 g / cm 3 .

[0033] Optionally, the density of the slurry after screening can be 1.5 g / cm 3 , 1.6 g / cm 3 , 1.7 g / cm 3 , 1.8 g / cm 3 or 1.5 g / cm 3 -1.8 g / cm 3 Any value in between.

[0034] In some embodiments, the shield waste slurry treatment method satisfies at least one of the following conditions: A. The flocculant includes an inorganic flocculant and / or an organic flocculant; B. The volume of the flocculant is 0.1%-0.6% of the volume of the slurry after screening.

[0035] Optionally, the volume of the flocculant can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6% or any value between 0.1% and 0.6% of the volume of the slurry after screening.

[0036] In some embodiments, the method for processing shield waste slurry satisfies at least one of the following conditions: A. The inorganic flocculant includes one or more of aluminum sulfate, ferrous sulfate, ferrous sulfate, ferrous chloride, ammonium aluminum sulfate, alum, polyaluminum chloride, sodium aluminate, active silicic acid, lime and magnesium oxide; B. The organic flocculant includes polyacrylamide and / or dodecylamine.

[0037] In some embodiments, the flocculant comprises polyaluminum chloride and anionic polyacrylamide.

[0038] In some embodiments, the volume ratio of the polyaluminum chloride to the anionic polyacrylamide is 10-50:1-5.

[0039] It should be noted that the pH value is in the range of 6.5-8.5, the organic matter content is less than 5%, the viscosity is less than 10Pa·s, and the density is 1.5-1.8 g / cm 3For mud, polyaluminum chloride (PAC) is used as the main flocculant and anionic polyacrylamide (PAM) is used as the coagulant aid. The flocculant composition can effectively increase the floc formation rate and sedimentation rate, improve the mud-water separation effect, and lower the moisture content of the mud cake after filtration, thereby improving the mud-water treatment efficiency, reducing treatment costs, and reducing pollution to the environment.

[0040] Optionally, the volume ratio of polyaluminum chloride to anionic polyacrylamide can be 10:1, 10:5, 20:1, 50:1 or any value between 10-50:1-5.

[0041] In some embodiments, the pH value of the treated mud is 6.5-8.5.

[0042] Optionally, the pH value of the treated mud can be 6.5, 7, 7.5, 8, 8.5 or any value between 6.5 and 8.5.

[0043] It should be noted that the method for treating shield waste mud provided in this application occupies a smaller area than traditional mud treatment methods, which has significant advantages for projects with limited space, such as urban construction sites. Reducing the area occupied by treatment facilities helps to optimize the utilization of site space and reduce land costs. In addition, the use of mud-water separation equipment greatly reduces the generation of waste mud and reduces the cost of mud treatment. Secondly, filter pressing increases the solid content of solid particles and reduces the water content of filter cakes, making waste easier to handle and transport, thereby reducing the cost of waste treatment. Most importantly, by reducing the processing time, the construction progress can be improved and the total cost of the project can be reduced, which has significant economic benefits for projects that are sensitive to construction periods. This method helps to reduce pollution to the environment, reduce waste mud, recover clear filtrate, and make solid waste easier to handle and transport, with positive environmental benefits, which helps to meet environmental protection requirements and reduce resource waste.

[0044] It should also be noted that the method for treating shield waste slurry provided in this application is not only applicable to shield construction, but is also widely used in many fields such as port engineering, sewage treatment plants, large-scale dredging and desilting operations. This multi-field applicability shows that this technology has broad market prospects in different industries.

[0045] The embodiments of the present application will be described in detail below in conjunction with specific examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, the conditions are carried out according to conventional conditions or manufacturer recommendations. The reagents or instruments used are not specified by the manufacturer and are conventional products that can be purchased commercially.

[0046] Example 1 This embodiment provides a method for processing shield waste mud, and the specific steps are as follows: S1: The waste mud discharged from the shield machine is pumped to the ground mud-water separation equipment (KMAZ-1000 model) through the pipeline by the slurry pump. After the waste mud is decompressed in the first buffer tank, it flows to the clay block-mud separator at the bottom, such as Figure 1 As shown in the figure, materials larger than 20mm are directly separated by the separator and enter the slag soil, while particles smaller than 20mm and mud enter the coarse screen for the next step of separation. The large pieces of materials with a size of 4 to 250mm on the screen fall into the slag yard, and the mud under the screen enters the slurry storage tank below. The moisture content of the materials falling into the slag yard is less than 25%, which meets the requirements for automobile transportation. S2: The slurry in the slurry storage tank is pumped by the No. 1 slurry pump to the first-level cyclone for classification. Particles with a diameter greater than 0.074mm enter the bottom flow and fall into the first-level separation No. 2 vibrating screen for screening and dehydration. The operation process is as follows: Figure 2 As shown in the figure, the overflow of the cyclone enters the slurry storage tank of the secondary separation module through the first-stage cyclone return box. The oversize material of the vibrating dewatering screen is mainly sand material with a size of 0.074 to 4 mm, which falls to the slag yard with a moisture content of less than 25%, meeting the requirements for automobile transportation. S3: The overflow from the slurry storage tank of the secondary separation module is pumped by the No. 2 slurry pump to the secondary cyclone for classification. Particles with a diameter greater than 0.020 mm enter the underflow of the secondary cyclone and fall onto the secondary vibrating dewatering screen for dehydration. The particles on the vibrating screen are particles with a diameter less than 0.074 mm and fall to the slag yard. Their moisture content is less than 25%, meeting the requirements for automobile transportation. The overflow from the secondary cyclone has a pH value of 7.8, an organic matter content of 5%, a viscosity of 10 Pa·s, and a density of 1.7 g / cm 3 ; S4: The overflow of the secondary cyclone is mixed with a flocculant to obtain a mixture, wherein the volume of the flocculant is 0.4% of the overflow volume of the secondary cyclone, and the mixture is filtered (filter press model APN18SL80M) to obtain filtered mud and muddy water, wherein the flocculant is polyaluminum chloride and anionic polyacrylamide in a volume ratio of 30:1; S5: The muddy water is collected in the regulating tank. The pH value of the muddy water is tested to be 5.8. An appropriate amount of pH regulator, sodium hydroxide, is added for adjustment. The pH value of the muddy water after adjustment is 7.6, which meets the environmental emission standards.

[0047] The ground mud and water separation equipment (KMAZ-1000 type) used in this example consists of three sets of processing capacity of 1000m 3 / h mud-water separation equipment. A single set of separation equipment consists of a scraper, vibrating screen, and other modules. It communicates with the PLC control room via a standard communication module, utilizing modular design, manufacturing, and installation processes. The technical parameters of the KMAZ-1000 mud-water separation equipment are shown in Table 1.

[0048] Table 1 Technical performance parameters of KMAZ-1000 mud-water separation equipment

[0049] Example 2 The difference from Example 1 is that the flocculants are polyaluminum chloride and dodecylamine.

[0050] Example 3 The difference from Example 1 is that the flocculants are aluminum sulfate and anionic polyacrylamide.

[0051] Comparative Example 1 The difference from Example 1 is that the secondary cyclone classification in step S3 is not performed.

[0052] Comparative Example 2 The difference from Example 1 is that no flocculant is added and the filtration is performed directly.

[0053] The muddy water and solids obtained by the treatment methods of the shield waste mud of the above embodiment and comparative example were tested, and the specific data are shown in Table 2.

[0054] Among them, the suspended matter concentration is used to detect the suspended solids remaining in the muddy water and reflect the solid-liquid separation situation.

[0055] The solid phase recovery rate refers to the dry solid phase mass after separation divided by the dry solid phase mass of the original mud, which reflects the loss of material in the separation system.

[0056] Table 2 Test results

[0057] analyze: From the data in Table 2, it can be seen that: (1) The selection of flocculants has a significant impact on the treatment effect. Example 1 uses a combination of polyaluminum chloride and anionic polyacrylamide, which has the best flocculation effect, the lowest mud water suspended solids concentration (500 mg / L), and the highest solid phase recovery rate (95%). This shows that selecting a suitable flocculant combination is crucial to improving mud water separation efficiency and solid phase recovery rate. (2) Secondary cyclone classification can effectively improve the treatment effect. Comparative Example 1 did not perform secondary cyclone classification, and the mud water suspended solids concentration (800 mg / L) and solid phase recovery rate (85%) were both lower than those in Example 1, indicating that secondary cyclone classification can effectively remove fine particles in mud water and improve the treatment effect. (3) Filter pressing can further reduce the mud water suspended solids concentration. Comparative Example 2 did not add flocculants and directly performed filter pressing. The mud water suspended solids concentration (1000 mg / L) and solid phase recovery rate (80%) were both much lower than those in Example 1, indicating that the filter pressing effect depends on the use of flocculants. (4) The pH values ​​of the treated mud water all meet environmental protection requirements. The pH values ​​of the muddy water in Examples 1-3 and Comparative Examples 1-2 were both within the range of 6.5-8.5, indicating that the treatment method can effectively control the pH value of the muddy water and avoid harm to the environment.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present application.

[0059] Furthermore, those skilled in the art will appreciate that although some embodiments herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this application and to form distinct embodiments. For example, in the claims above, any of the claimed embodiments may be used in any combination. The information disclosed in this background section is intended solely to enhance understanding of the overall background of this application and should not be construed as an admission or any implication that such information constitutes prior art known to those skilled in the art.

Claims

1. A method for treating shield waste slurry, characterized in that: include: Screening the shield waste slurry to obtain screened slurry and screened solid particles; Mixing the sieved mud and a flocculant to obtain a mixture, and filtering the mixture to obtain filtered mud blocks and mud water; The muddy water and the pH regulator are mixed to obtain treated mud.

2. The method for treating shield waste slurry according to claim 1, characterized in that: The diameter of the solid particles in the slurry after screening is less than or equal to 20 μm.

3. The method for treating shield waste slurry according to claim 1, characterized in that: The screening comprises: Coarsely screening the waste shield mud to obtain coarse screen oversize and coarse screened mud; The coarsely screened slurry is subjected to cyclone classification.

4. The method for treating shield waste slurry according to claim 3, characterized in that: The material on the coarse screen has a diameter greater than or equal to 4 mm and a water content less than 25 wt %.

5. The method for treating shield waste slurry according to claim 1, characterized in that: At least one of the following conditions is met: A. The pH value of the slurry after screening is 6.5-8.5; B. The organic matter content of the slurry after screening is less than or equal to 5%; C. The viscosity of the slurry after screening is less than or equal to 10 Pa·s; D. The density of the slurry after screening is 1.5 g / cm 3 -1.8 g / cm 3 .

6. The method for treating shield waste slurry according to claim 1, characterized in that: At least one of the following conditions is met: A. The flocculant includes an inorganic flocculant and / or an organic flocculant; B. The volume of the flocculant is 0.1%-0.6% of the volume of the slurry after screening.

7. The method for treating shield waste slurry according to claim 6, characterized in that: At least one of the following conditions is met: A. The inorganic flocculant includes one or more of aluminum sulfate, ferrous sulfate, ferrous sulfate, ferrous chloride, ammonium aluminum sulfate, alum, polyaluminum chloride, sodium aluminate, active silicic acid, lime and magnesium oxide; B. The organic flocculant includes polyacrylamide and / or dodecylamine.

8. The method for treating shield waste slurry according to claim 7, characterized in that: The flocculants include polyaluminium chloride and anionic polyacrylamide.

9. The method for treating shield waste slurry according to claim 8, characterized in that: The volume ratio of the polyaluminium chloride to the anionic polyacrylamide is 10-50:1-5.

10. The method for treating shield waste slurry according to any one of claims 1 to 9, characterized in that: The pH value of the treated mud is 6.5-8.5.

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