A treatment method for resource utilization of waste mud soil

Abstract

The present invention discloses a treatment method for the resource utilization of waste slurry soil, comprising the following steps: (1) preparing a slurry containing alkaline porous hardened aggregates: first, a retarder, a curing agent, and a flocculant are sequentially added to the waste slurry to form a floc structure in the slurry, and the supernatant is discharged after sedimentation. Then, an activator is added to the slurry, and the floc structure in the slurry becomes alkaline porous hardened aggregates after the addition of the activator; the slurry is subjected to vacuum filtration dehydration to obtain a slurry containing alkaline porous hardened aggregates; (2) preparing an acidic mud cake: an acidic additive and a flocculant are added to the waste slurry, and the treated slurry is subjected to high-pressure plate and frame filter press dehydration to obtain an acidic mud cake after dehydration; (3) mixing and stirring the slurry containing alkaline porous hardened aggregates with the acidic mud cake to form a soil material with a pH of 6.5 to 8.0.

Description

Technical Field

[0001] The present invention relates to a method for treating waste slurry soil resourcefully. Background Art

[0002] A large amount of waste slurry is generated in slurry balance pipe jacking projects, shield projects, river and lake cutter suction dredging projects, etc. These waste slurries have a high clay content, slow self-settling, and may contain pollutants. If they are treated by the conventional method of stacking in mud fields, not only a large area of land needs to be occupied for a long time, but also problems such as resource waste and secondary pollution will occur. Due to the characteristics of these waste slurries, such as high water content, rich in organic matter, low permeability, and large compressibility, they cannot be directly applied in engineering.

[0003] The existing method for treating waste slurry is to use lime and cement as additives and cooperate with high-pressure plate and frame filtration for dehydration. After the waste slurry is dehydrated, the water content drops below 60%, but the pH is higher than 12. Due to the high pH of the product and the loss of the aggregate structure of the product after high-pressure plate and frame dehydration, it is difficult to be directly used as a soil material. If the product is used as soil, generally, secondary treatment is required to neutralize the alkalinity of the product by adding additives and at the same time add aggregates in the soil to form a soil resource product.

[0004] At present, there are mainly two problems for waste slurry to be directly turned into soil through dehydration: (1) In the rapid dehydration stage, after the slurry is pretreated to form a dehydration product with a lower water content, the aggregates are formed by the flocculant and slurry particles during pretreatment. Their texture is soft, easy to deform, and over time, the structure generated by the flocculant gradually ages, and finally the aggregate structure may disappear, resulting in poor soil permeability and difficult tillage. When it rains or is irrigated, water often has difficulty infiltrating into the soil, leading to drainage difficulties, affecting the growth of plant roots, and hindering the absorption of soil nutrients by the roots. Therefore, it is necessary to consider that there must be permanent large particles in the planting soil. (2) Also, since the external additives are mainly lime and cement during the formation of the permanent aggregate structure, the aggregate slurry formed at this time is highly alkaline, which will have an adverse effect on the subsequent soil formation. Therefore, acidic substances are needed to neutralize it to ensure that its pH is moderate.

[0005] Regarding the problem of soil resource utilization of waste mud, the method currently used more is to improve the waste mud with a composite formula, and then mix the improved mud slurry with soil, so as to realize the soil resource utilization of waste mud. As disclosed in the invention with the application number CN201010148295.9, according to the density of the waste mud and the water content of 10% - 15%, it is mixed with natural soil with a particle size < 0.5 cm, and microorganisms are added, and sufficient stirring is carried out in the manner described therein, so as to harmlessly treat the waste mud in oil and gas drilling operations. This method is complex and requires a large amount of natural soil, which will cause certain damage to the environment.

[0006] Regarding the problem of directly turning mud into soil, as disclosed in the invention with the application number CN201810082332.7, a composite material for environmentally friendly treatment of shield waste mud is proposed, which can quickly solidify shield mud with a water content of 50% - 90% in 1 - 5 minutes, meet the requirements of dump truck transportation, and at the same time be improved during the solidification process, and be reused as planting soil for greening projects or highway subgrade fillers. However, the specific way of the composite material playing its role is not proposed, and no strengthening effect on flocs is proposed to form permanent aggregates with water-retaining and hydrophobic properties and good pores. And for the composite material proposed in its claims, the Portland cement will cause the final product formed to have extremely strong alkalinity, and cannot meet the standard of soil pH = 5.0 - 8.3. Another example is the invention disclosed in the application number 202010328997.9, which proposes a composite soil-forming material to prepare river and lake dredging mud into greening planting soil, and proposes to add the composite soil-forming material of this invention into the dredging mud together, and after curing for 8 - 14 days and screening, greening planting soil can be formed. However, it does not consider that the hydration reaction has occurred while adding cement, and the hydration at this stage cannot help improve the strength of the aggregates. And according to the curing of the mud cake for 7 - 14 days mentioned in this step, a whole mud cake with a certain strength will be formed, which cannot be used as planting soil. Another example is the invention disclosed in the patent number 202110827579.9, which adds uncommon materials such as river sand, coconut coir, branch particles, volcanic stone filter media and deodorants as sludge improvers. The materials are complex, and the process requires the mud to be dehydrated first, and it is impossible to use the dehydrated product directly as planting soil. Summary of the Invention

[0007] Object of the Invention: The object of the present invention is to provide a treatment method for soil resource utilization of waste mud, which can directly use the dehydrated product as planting soil without affecting the rapid reduction of waste mud.

[0008] Technical Solution: The treatment method for soil resource utilization of waste mud described in the present invention includes the following steps:

[0009] (1) Preparation of slurry containing alkaline porous hardened aggregates: First, a retarder, a curing agent, and a flocculant are sequentially added to the waste mud to form a floc structure in the mud. After sedimentation, the supernatant is discharged. Then, an activator is added to the mud, and the floc structure in the mud turns into porous hardened aggregates; the mud is subjected to vacuum filtration dehydration to obtain a slurry containing alkaline porous hardened aggregates; discharging the supernatant can effectively improve the activation efficiency, so that most of the hydration products during activation are retained in the flocs and do not lose during subsequent dehydration; and it reduces the vacuum filtration dehydration time. Vacuum filtration only discharges the excess water between the flocs. If the supernatant is not discharged in the previous step, the subsequent supernatant will be discharged by vacuum filtration, with lower efficiency.

[0010] (2) Preparation of acidic mud cake: An acidic admixture and a flocculant are added to the waste mud, and the treated mud is subjected to high-pressure plate and frame filter press dehydration to obtain an acidic mud cake after dehydration.

[0011] (3) Mix and stir the slurry containing alkaline porous hardened aggregates with the acidic mud cake to form a soil material with a pH of 6.5 - 8.0.

[0012] Among them, in step (1), the mass ratio of the dry matter of the waste mud to the retarder, the curing agent, the flocculant, and the activator is 1000:2 - 4:30 - 70:1 - 3:30 - 70.

[0013] Among them, in step (1), the retarder used in the present invention is: one or more of lignosulfonates, hydroxycarboxylates (such as citric acid, tartaric acid, malic acid, etc.), cellulose derivatives (such as carboxymethyl cellulose, etc.), inorganic compounds (such as phosphates, etc.), or organic phosphonates, etc.; the curing agent is: one or more of inorganic types (such as quicklime, cement, etc.), organic types (such as sulfonated oil, modified sodium silicate, epoxy resin, polymer materials, etc.), biological enzyme curing agents, etc.; the flocculant is: one or more of inorganic flocculants, such as iron salts (such as ferric chloride), organic flocculants, such as natural organic polymer flocculants (such as chitosan, lignin, gum, alginate, animal glue, gelatin, modified starch, and modified cellulose), synthetic organic polymer flocculants (non-ionic, cationic, anionic, etc.), microbial flocculants, composite flocculants, etc.; the activator is: one or more of alkali activators (such as sodium hydroxide, potassium hydroxide, and sodium silicate, etc.), acid activators (such as phosphoric acid, aluminum dihydrogen phosphate, acetic acid, etc.), and salt activators (such as calcium sulfate, silicate, etc.).

[0014] Among them, in step (1), a retarder is first added to the slurry. After the retarder is added, the stirring speed is 100 - 800 rpm, and stirring is carried out for 10 - 15 min; then a curing agent is added. After the curing agent is added, the stirring speed is 100 - 800 rpm, and stirring is carried out for 10 - 15 min; then a flocculant is added. After the flocculant is added, the stirring speed is 100 - 800 rpm, and stirring is carried out for 1 - 5 min. Then it is left standing for 5 - 6 min, and the supernatant is discharged to form a concentrated flocculent slurry; an activator is added to the concentrated flocculent slurry, the stirring speed is 400 - 420 rpm, and stirring is carried out for 5 - 10 min. Then it is left standing for 0.5 - 2 h to enable the hydration reaction to occur rapidly, and the flocs harden and reach stability.

[0015] Among them, in step (1), the suction filtration pressure for vacuum filtration dehydration is 60 - 105 kPa. After the free water is extracted, a slurry containing alkaline porous hardened aggregates is obtained, that is, vacuum filtration dehydration is carried out until the water content of the slurry reaches 70% - 80%; the pH of the alkaline porous hardened aggregates is 10.0 - 12.0.

[0016] Among them, in step (2), the acidic admixture is acidic chemical fertilizers such as polyaluminum sulfate, ferrous sulfate, ammonium sulfate, potassium sulfate, or superphosphate, etc.; the flocculant is: inorganic flocculants such as iron salts (ferric chloride, etc.), organic flocculants such as natural organic polymer flocculants (chitosan, lignin, gum, alginate, animal glue, gelatin, modified starch, and modified cellulose), synthetic organic polymer flocculants (non-ionic, cationic, anionic, etc.), microbial flocculants, composite flocculants, etc., one or more of them.

[0017] Among them, in step (2), the mass ratio of the waste slurry dry matter to the acidic admixture and the flocculant is 1000:30 - 70:1 - 3.

[0018] Among them, in step (2), during the high-pressure plate and frame filtration dehydration process, the pressure is 0.8 - 2 MPa, and the slurry is rapidly dehydrated to obtain an acidic mud cake, and its water content needs to be controlled at 30% - 50%; the pH of the acidic mud cake is 4.0 - 5.0. The water content of the mud cake in the acidic process is generally low, 30% - 50%; the water content of the slurry in the alkaline process is slightly higher, 70% - 80%; after the two are neutralized, the water content reaches about 60%. The purpose of controlling the water content is mainly to make the finally formed soil have a more appropriate water content.

[0019] Among them, in step (3), the slurry containing alkaline porous hardened aggregates and the acidic mud cake are mixed at a mass ratio of 1 - 1.5:1.

[0020] By controlling the dosages and specific addition sequences of retarders, curing agents, flocculants, and activators, alkaline porous hardened aggregates are formed in the dewatered product of waste mud, i.e., large - particle permanent soil skeletons are formed in the dewatered product, thus fulfilling the important condition for directly converting waste mud into soil in one step during dewatering. The water content of waste mud is extremely high, which easily causes the curing agent to directly hydrate in the mud. The retarder is added first to slow down the curing reaction of the subsequently added curing agent. The addition of the flocculant can quickly flocculate the fine particles and curing agent particles in the waste mud to form a floc structure containing the curing agent and soil particles. After the supernatant is settled and drained, the activator is added. The activator reacts with the retarder, rendering the effect of the retarder ineffective, thereby enabling the curing agent inside the floc to rapidly undergo a hydration reaction and harden the floc structure, causing the soil particles in the waste mud to form alkaline porous hardened aggregates one by one. (The key to the formation of hardened porous flocs in the mud dewatered product lies in delaying the hydration reaction of the curing agent using the retarder. After forming flocs that encapsulate the curing agent particles, the activator reacts with the retarder, enabling the curing agent in the flocs to immediately undergo a hydration reaction.) After the formation of alkaline porous hardened aggregates in the mud, the filtration effect of the mud can be further improved, thus accelerating the dewatering of the mud. At the same time, due to the moisture in the alkaline porous hardened aggregate slurry stimulating the acidic substances in the acidic mud cake, the acidic substances can enter the alkaline porous hardened aggregates and undergo an acid - base neutralization reaction with them, ultimately obtaining a soil material with a pH between 6.5 and 8.0, which has good water permeability, water retention, and fertilizer retention properties and can be directly used as planting soil for growing plants in situ.

[0021] Advantages: Compared with the prior art, the present invention has the following remarkable advantages: (1) The present invention can rapidly dewater high - moisture - content waste mud while forming hardened aggregates one by one through the dosages and addition sequences of specific agents, which exist in the final planting soil in the form of large particles, endowing the planting soil with permanently good permeability and excellent water - permeable effect. The specific agent addition sequence avoids premature hydration and inactivation of the curing agent and also avoids the formation of a large hardened mud cake. (2) Since most of the waste mud is composed of clay, has a relatively high organic matter content, and the added acidic admixture has certain fertility, most nutrients will not be lost due to plate - and - frame filtration. Therefore, the final acidic mud cake has good fertilizer - retaining ability, and by neutralizing the alkaline porous hardened aggregate slurry with the acidic mud cake, the pH of the final soil is between 6.5 and 8.0. (3) The soil formed by the present invention does not require the addition of extra large - particle substances such as straw and biochar. The present invention can, with the addition of only a small amount of admixtures, perform one - step treatment on waste mud to form high - quality soil with a moderate pH, good water permeability, water retention, and fertilizer retention properties, meeting the standards of "Greening Planting Soil", and the texture characteristics of this soil are permanent texture. Brief Description of the Drawings

[0022] Figure 1 Process flow chart of the treatment method of the present invention

[0023] Figure 2 Initial untreated slurry in step (1) of Example 1

[0024] Figure 3 Alkaline porous hardened aggregate slurry formed after being treated in step (1) of Example 1

[0025] Figure 4 Acidic mud cake obtained after being treated in step (2) of Example 1

[0026] Figure 5 Germination diagram of seeds after directly planting plants in the planting soil obtained in Example 1

[0027] Figure 6 Picture of the mud cake obtained after being treated in step (1) of Comparative Example 1 Detailed implementation manners

[0028] Example 1

[0029] The treatment method for resource utilization of waste slurry soil of the present invention is applied to Taihu Lake dredging slurry with a water content of 400%. The slurry is as Figure 2 shown and includes the following steps:

[0030] (1) Prepare a slurry containing alkaline porous hardened aggregates:

[0031] (1.1) Waste slurry concentration: The retarder, curing agent, and flocculant are hydroxyethyl cellulose, OPC, and PAM (polyacrylamide) respectively. Add the retarder hydroxyethyl cellulose to the slurry with a water content of 400% according to the mass ratio of 2:1000 to the dry matter of the slurry. Set the stirring speed to 600 rpm. After stirring for 15 minutes, add the curing agent OPC to the slurry with a water content higher than the liquid limit of the slurry according to the mass ratio of 50:1000 to the dry matter of the slurry. Set the stirring speed to 600 rpm. After stirring for 15 minutes, add the flocculant PAM to the slurry with a water content higher than the liquid limit of the slurry according to the mass ratio of 3:1000 to the dry matter of the slurry. Set the stirring speed to 500 rpm. Stir for 4 minutes, and then let it stand for 5 minutes to drain the supernatant;

[0032] (1.2) Alkaline porous hardened aggregate excitation: Add fly ash as an activator to the concentrated alkaline slurry according to the mass ratio of 40:1000 to the dry matter of the slurry. The stirring speed is 400 rpm. Stir for 5 minutes until evenly mixed, and then let it stand for 1 hour to excite the floc strength;

[0033] (1.3) Vacuum filtration dehydration: The alkaline porous hardened aggregate slurry after the excitation intensity is subjected to vacuum filtration dehydration process, and the dehydration negative pressure is 60 kPa. After the free water is extracted, a slurry of alkaline porous hardened aggregate with a pH of 10.0 to 12.0 and water retention properties is obtained. The water content of the slurry is 75%, and the aggregate structure generated by PAM flocculation does not change substantially after filtration. Figure 3 As shown;

[0034] (2) Preparation of low water content acidic mud cake:

[0035] (2.1) Add the acidic admixture polyaluminium sulfate to the mud dry matter mass ratio of 45:1000 into the mud with a water content higher than the mud liquid limit, set the stirring speed to 600 rpm, and stir for 20 minutes;

[0036] (2.2) Add flocculant PAM to mud dry matter at a mass ratio of 3:1000 to mud with a water content of 400%, set the stirring speed to 500 rpm, stir for 4 minutes, let it stand for 5 minutes, and discharge the supernatant;

[0037] (2.3) The sediment was subjected to high-pressure plate and frame filtration and dehydration. The pressure was set to 0.8 MPa. The mud was quickly dehydrated to obtain an acidic mud cake with a pH of 4.0-5.0. The water content of the mud cake was 35%. Since the acidic aggregates were flexible structures, the flexible flocculent structure formed by PAM no longer had pores due to the high pressure during filtration. Figure 4 As shown;

[0038] (3) Mixed soil formation process: The alkaline porous hardened aggregate slurry and the acid mud cake are discharged into the stirring tank in a mass ratio of 1:1. The stirring speed is set to 500 rpm. After stirring for 30 minutes, the acidic substances in the acid mud cake are stimulated by the water in the alkaline porous hardened aggregate slurry and enter the alkaline porous hardened aggregate, and undergo an acid-base neutralization reaction with it. The various indicators of the final soil product meet the standard requirements of planting soil. The specific test results of various indicators are shown in Table 1. The soil product was subsequently used for the planting test of white radish seeds, and the growth was good. Figure 5 .

[0039] Example 2

[0040] The treatment method of Example 2 is basically the same as that of Example 1, and the only difference is that: in Example 2, the treatment method for resource utilization of the waste mud soil of the present invention is applied to the Dalian Bay mud with a water content of 800%. At the same time, the retarder, curing agent, flocculant, and activator used in step (1) of Example 2 are desulfurized gypsum, OPC, PAM, and aluminum sulfate respectively. The mass ratios of the retarder, curing agent, flocculant, and activator to the dry matter of the mud are 3:40:3:50:1000; in step (2), the flocculant and acidic admixture are PAM and ferrous sulfate respectively, and the mass ratios of the flocculant and acidic admixture to the dry matter of the mud are 3:50:1000.

[0041] After the treatment of Example 2, all the indicators of the finally obtained soil product meet the standard requirements of the planting soil. The test results of specific indicators are shown in Table 1. It can be concluded from Example 2 that after changing the type of mud and replacing the chemicals according to the characteristics of the mud, the mud can still be subjected to the integrated treatment of dehydration - soilification according to the specific chemical addition sequence in the present invention.

[0042] Example 3

[0043] The treatment method of Example 3 is basically the same as that of Example 1, and the only difference is that: the activator used in step (1.2) of Example 3 is waste gypsum powder, and the mass ratio of the waste gypsum powder to the dry matter of the mud is 40:1000, and the standing time is 30 min.

[0044] After the treatment of Example 3, all the indicators of the finally obtained soil product meet the standard requirements of the planting soil. The test results of specific indicators are shown in Table 1. It can be concluded from Example 3 that after changing the type of activator, the mud can still be subjected to the integrated treatment of dehydration - soilification according to the specific chemical addition sequence in the present invention.

[0045] Example 4

[0046] The treatment method of Example 4 is basically the same as that of Example 1, and the only difference is that: the acidic admixture used in step (2.1) of Example 4 is potassium sulfate, and the mass ratio of potassium sulfate to the dry matter of the mud is 30:1000.

[0047] After the treatment of Example 4, all the indicators of the finally obtained soil product meet the standard requirements of the planting soil. The test results of specific indicators are shown in Table 1. It can be concluded from Example 4 that after changing the type of acidic admixture, the mud can still be subjected to the integrated treatment of dehydration - soilification according to the specific soilification mixing method in the present invention.

[0048] Comparative Example 1

[0049] The differences between Comparative Example 1 and the present invention are as follows: The types and addition sequence of the medicaments are not in accordance with the specific ones, and the production of acidic mud cakes is lacking. Compared with Example 1, the treatment method of Comparative Example 1 is basically the same as that of Example 1, with the differences being that in Comparative Example 1, the types and sequence of the medicaments added in step (1) are changed, and the process of producing acidic mud cakes is lacking. The types of medicaments added in Comparative Example 1 are: flocculant, curing agent, and activator; the sequence is: first add the flocculant, drain the supernatant, then add the curing agent, and then add the activator, and no retarder is added, and at the same time, the step of producing acidic mud cakes is lacking.

[0050] In the implementation process of Comparative Example 1, it was found that after the activator was added, the curing reaction occurred rapidly, thus hardening the floc structure. However, since the curing agent was added after the flocs were formed, the curing agent at this time caused a bulk structure to form between the flocs, and the pores between the aggregates disappeared. Eventually, an alkaline porous hardened aggregate slurry was not obtained, but a whole piece of mud cake that had undergone a hydration reaction and had a certain strength was obtained, and the infiltration effect was extremely poor, as shown in Figure 6 , and due to the lack of mixed acidic mud cakes, the product finally obtained was extremely alkaline, and the seed germination rate did not meet the standard. Its soil indicators are shown in Table 1, and some indicators cannot meet the standard values.

[0051] Comparative Example 2

[0052] The differences between Comparative Example 2 and the present invention are as follows: No retarder is added. Compared with Example 1, the treatment method of Comparative Example 2 is basically the same as that of Example 1, and the only difference is that in Comparative Example 2, the addition of the retarder is lacking in step (1).

[0053] In the implementation process of Comparative Example 2, it was found that since no retarder was added, after the curing agent was added to the high-water-content slurry, the reaction was relatively fast. On the one hand, the strength of the aggregates was relatively low, and the long-term retention of the aggregates was poor, and porous hardened aggregates could not be formed; on the other hand, the loss of the curing agent was large, and the product after adding the acidic mud cake and mixing could not be used as soil. Since it lacked a pore structure and its texture belonged to clay, it could not meet the requirements of loam, and at the same time, the infiltration effect was extremely poor, and the seed germination rate did not meet the standard. Its soil indicators are shown in Table 1, and some indicators cannot meet the standard values.

[0054] Comparative Example 3

[0055] The differences between Comparative Example 3 and the present invention are as follows: The specific addition ratio of the medicaments of the present invention is not followed. Compared with Example 1, the treatment method of Comparative Example 3 is basically the same as that of Example 1, and the only difference is that in Comparative Example 3, the retarder is added at a mass ratio of 0.5:1000 to the dry matter, and the flocculant is added at a mass ratio of 0.5:1000 to the dry matter.

[0056] In the implementation of Comparative Example 3, it was found that due to the small addition amount of the retarder, after adding the curing agent, because the dosage of the retarder was too small, most of the curing agent had already started the hydration reaction. And because the amount of the flocculant added was small, the formed tiny floc structure was connected to form a dense cake under the action of the activator, resulting in a very low infiltration rate. At the same time, the addition of the acidic mud cake failed to relieve the solidified alkaline substances, and the seed germination rate did not meet the standard. Its soil indicators are shown in Table 1, and some indicators cannot meet the standard values.

[0057] Comparative Example 4

[0058] Comparative Example 4 is a conventional method for treating waste mud in the prior art: the dredged mud adopts a cement and PAM formula, and a plate and frame pressure filtration process is used to obtain a mud cake with a low water content.

[0059] Through Comparative Example 4, the pH of the dehydrated product is > 12.5. At the same time, the infiltration rate of the dehydrated product is very low, and the seed germination rate does not meet the standard, making it difficult to be used as soil.

[0060] The test results of the main control indicators of the soil physical and chemical properties of the dehydrated products obtained in Examples 1 to 4 and Comparative Examples 1 to 4 are shown in Table 1.

[0061] Table 1

[0062]

[0063]

[0064] It can be seen from the data of Examples 1 to 4 in Table 1 that the method of the present invention is applicable to slurries with different sources and different water contents. It can be seen from Comparative Example 1 that the lack of types of reagent addition and the failure to follow the specific reagent addition sequence of the present invention, and the lack of the production of acidic mud cakes, resulting in the pH, EC, infiltration rate, and seed germination index not meeting the soil standards, and the slurry cannot be treated into soil; in Comparative Example 2, although the reagent addition has been carried out in accordance with the specific reagent addition sequence of the present invention, due to the lack of a retarder, the pH, infiltration rate, and seed germination index of the obtained mixed product do not meet the soil standards. This shows that adding reagents in accordance with the specific reagent addition sequence described in the present invention but lacking reagent types cannot treat the slurry into soil. In Comparative Example 3, since the reagent addition ratio is not within the addition range of the present invention, the EC, infiltration rate, and seed germination index of the obtained mixed product do not meet the soil standards, which shows that when the reagent addition is not within the scope of the present invention, the slurry soilification cannot be achieved. In Comparative Example 4 according to the conventional slurry disposal method, the pH, EC, infiltration rate, and seed germination index of its dehydrated product do not meet the soil standards, so the slurry cannot be directly treated into soil in one step according to the conventional disposal method. Only by adding specific reagents in accordance with the types, dosages, and sequences of the present invention, and at the same time producing and mixing acidic mud cakes, can different high-water-content dredged slurries be treated into soil while being dehydrated and directly recycled for resource utilization.

Claims

1. A treatment method for the resource utilization of waste mud soil, characterized in that, it includes the following steps: (1) Prepare a slurry containing alkaline porous hardened aggregates: First, add a retarder, a curing agent, and a flocculant to the waste mud in sequence to form a floc structure in the mud. After sedimentation, the supernatant is discharged. Then, add an activator to the mud. After adding the activator, the floc structure in the mud becomes porous hardened aggregates; perform vacuum filtration dehydration on the mud to obtain a slurry containing alkaline porous hardened aggregates; the mass ratio of the dry matter of the waste mud to the retarder, the curing agent, the flocculant, and the activator is 1000: 2 - 4: 30 - 70: 1 - 3: 30 - 70; (2) Prepare an acidic mud cake: Add an acidic admixture and a flocculant to the waste mud, and perform high-pressure plate-and-frame filter press dehydration on the treated mud to obtain an acidic mud cake after dehydration; (3) Mix and stir the slurry containing alkaline porous hardened aggregates with the acidic mud cake to form a soil material with a pH of 6.5 - 8.

0.

2. The treatment method for the resource utilization of waste mud soil according to claim 1, characterized in that: In step (1), first add a retarder to the mud. After adding the retarder, the stirring speed is 100 - 800 rpm, and stir for 10 - 15 min; then add a curing agent. After adding the curing agent, the stirring speed is 100 - 800 rpm, and stir for 10 - 15 min; then add a flocculant. After adding the flocculant, the stirring speed is 100 - 800 rpm, and stir for 1 - 5 min, then stand for 5 - 6 min, and discharge the supernatant to form a concentrated floc slurry; add an activator to the concentrated floc slurry, the stirring speed is 400 - 420 rpm, stir for 5 - 10 min, and then stand for 0.5 - 2 h.

3. The treatment method for the resource utilization of waste mud soil according to claim 1, characterized in that: In step (1), the suction filtration pressure for vacuum filtration dehydration is 60 - 105 kPa. After extracting the free water, a slurry containing alkaline porous hardened aggregates is obtained; the pH of the alkaline porous hardened aggregates is 10.0 - 12.

0.

4. The treatment method for the resource utilization of waste mud soil according to claim 1, characterized in that: In step (2), the acidic admixture is one of polyaluminum sulfate, ferrous sulfate, ammonium sulfate, potassium sulfate, or superphosphate.

5. The treatment method for the resource utilization of waste mud soil according to claim 1, characterized in that: In step (2), the mass ratio of the dry matter of the waste mud to the acidic admixture and the flocculant is 1000: 30 - 70: 1 - 3.

6. The treatment method for the resource utilization of waste mud soil according to claim 1, characterized in that: In step (2), the pH of the acidic mud cake is 4.0 - 5.

0.

7. The treatment method for the resource utilization of waste mud soil according to claim 1, characterized in that: In step (3), the slurry containing alkaline porous hardened aggregates is mixed with the acidic mud cake at a mass ratio of 1 - 1.5: 1.

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