A pipe network sludge conditioner and its preparation method and application

Abstract

The present invention discloses a pipeline sludge conditioner, a preparation method thereof, and an application thereof. The preparation method of the pipeline sludge conditioner comprises the following steps: mixing calcium carbonate and phosphogypsum in a mass ratio of 0.45 to 0.65:1 and ball milling to obtain a co-ground powder; and uniformly mixing the co-ground powder with steel slag in a mass ratio of 24 to 30:1 to obtain the pipeline sludge conditioner. The conditioner of the present invention is conducive to the formation of pores inside the sludge, promotes the release of water inside the sludge, and thus effectively improves the dehydration effect; after ball milling, the activity of calcium carbonate and phosphogypsum is significantly enhanced, so that the pH value of the treated sludge is stabilized in the slightly alkaline range, solving the problem of excessively high sludge alkalinity when using industrial solid waste such as steel slag for conditioning.

Description

Technical Field

[0001] The invention belongs to the field of sludge treatment, and in particular relates to a pipe network sludge conditioner and a preparation method and application thereof. Background Art

[0002] In existing industrial-scale treatment and disposal systems for contaminated sludge, large quantities of dewatered sludge products remain in the pipeline network. Their resource utilization has become a key bottleneck in ensuring the normal operation and maintenance of the pipeline network. Failure to properly handle this sludge will have a significant negative impact on the environment.

[0003] Removing moisture from pipe network sludge is challenging, primarily due to the flocculent and highly hydrophilic nature of its particle structure. This results in an extremely high moisture content (94% to 99%), which in turn increases the volume of the sludge and complicates subsequent treatment and disposal. The degree of sludge dehydration directly impacts treatment and disposal costs; the lower the moisture content of the dehydrated sludge, the smaller the sludge cake, and the lower the corresponding transportation and disposal costs.

[0004] Although the sludge moisture content can be reduced to 75%-85% after dewatering using mechanical equipment such as filter presses or centrifuges, such mechanical methods consume a lot of energy and are difficult to further reduce the sludge moisture content. Typically, sludge conditioners are added to change the sludge floc structure to improve dewatering performance, and then combined with mechanical means for dewatering. Commonly used conditioners include polyacrylamide, iron salts, aluminum salts, and quicklime. However, these materials often require large dosages, may be toxic to the environment, and affect the subsequent treatment and utilization of the sludge. In addition, when using industrial solid waste such as steel slag for conditioning, there is the problem of excessive sludge alkalinity. Therefore, there is an urgent need to develop a new type of pipeline sludge conditioner that is efficient, environmentally friendly, and economically feasible to overcome the limitations of existing technologies and promote the effective management and resource utilization of sludge. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention provides a pipeline sludge conditioner, its preparation method, and its application. After treatment with the conditioner, the pH value of the sludge stabilizes within a slightly alkaline range, effectively resolving the problem of excessive sludge alkalinity when treating industrial solid wastes such as steel slag.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for preparing a pipeline sludge conditioner comprises the following steps: mixing calcium carbonate and phosphogypsum in a mass ratio of 0.45-0.65:1 and ball-milling the mixture to obtain a co-ground powder with a particle size of 60-90 μm; and uniformly mixing the co-ground powder with steel slag in a mass ratio of 24-30:1 to obtain the pipeline sludge conditioner.

[0008] Preferably, the mass ratio of calcium carbonate to phosphogypsum is 0.6:1.

[0009] Preferably, the rotation speed of the ball mill is 180-220 r / min.

[0010] Preferably, the rotation speed of the ball mill is 200 r / min.

[0011] Preferably, the ball milling time is 25 to 35 minutes.

[0012] Preferably, the ball milling time is 30 min.

[0013] Preferably, the water content of calcium carbonate, phosphogypsum and steel slag does not exceed 5%.

[0014] The pipeline sludge conditioner prepared by the above-mentioned preparation method of the pipeline sludge conditioner.

[0015] The application of the above-mentioned pipeline sludge conditioner includes the following steps: adding the above-mentioned pipeline sludge conditioner to the pipeline sludge and stirring it evenly, the amount of the pipeline sludge conditioner added accounts for 10~20wt% of the dry weight of the pipeline sludge, and then performing solid-liquid separation on the evenly stirred sludge to obtain a dehydrated filter cake, thereby completing dehydration conditioning.

[0016] Preferably, the solid-liquid separation method is filter press.

[0017] The mechanism involved in the present invention is:

[0018] In the present invention, a skeleton support structure is constructed inside the sludge by introducing a small amount of steel slag, which helps to form drainage channels and ensure good permeability during the dehydration process, so that water can be removed more effectively. In addition, calcium carbonate and phosphogypsum are treated by mechanical ball milling, which significantly refines the particle size of the two materials. This process not only increases the porosity and specific surface area of ​​phosphogypsum, but also increases the number of active sites of calcium carbonate. As a result, the synergistic effect between phosphogypsum and calcium carbonate is enhanced, and the reaction rate is significantly improved. Specifically, by ball milling calcium carbonate and phosphogypsum, the acid (HF, H3PO4 and H2SO4) adsorbed on the surface of phosphogypsum is released (controlled by crystal structure and morphology), the calcium carbonate is activated, and the following reaction occurs: CaCO3→Ca 2+ +CO3 2- , where: Ca 2+ With F - Combined with PO4 to form CaF2 precipitate 3- Combined to form Ca3 (PO4) 2, the first two parts release the remaining H + Can neutralize excess OH in steel slag - ;CO3 2- Hydrolysis produces a small amount of H2CO3 and OH - , OH- The carbonic acid generated by absorbing CO2 from the air can also act to buffer the alkalinity of steel slag. This reaction mechanism significantly alleviates the strong alkalinity problem caused by steel slag. At the same time, the stable colloidal structure formed by the above two materials can be evenly dispersed in the sludge, optimizing the cohesion effect between particles, thereby improving the sludge settling performance and dewatering efficiency. In summary, the present invention not only improves the sludge dewatering effect, but also solves the problem of increased pH value caused by steel slag, realizing a more environmentally friendly and efficient sludge treatment solution.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) The present invention uses phosphogypsum, which is widely available, as the main raw material, which not only helps to reduce processing costs, but also, due to its high proportion of application, can more fully consume industrial solid waste compared with other technologies, significantly improve the utilization rate of solid waste, and thus effectively alleviate the environmental pressure caused by the storage of large amounts of industrial solid waste.

[0021] (2) The moisture content of the pipe network sludge after conditioning with the conditioning agent of the present invention is significantly reduced, which is beneficial to subsequent treatment, disposal and resource utilization, and improves the efficiency and economy of the entire sludge management process.

[0022] (3) The present invention adopts mechanical ball milling, which is easy to operate, low cost, and does not generate waste gas emissions during the entire process, thus meeting environmental protection requirements.

[0023] (4) The pH value of the conditioned sludge is stabilized within a slightly alkaline range. The ball milling process significantly enhances the activity of calcium carbonate and phosphogypsum, effectively resolving the problem of strong alkalinity in sludge caused by the use of industrial solid waste such as steel slag. Compared with methods that require further pH adjustment to address excessive alkalinity in conditioned sludge, this method significantly reduces overall treatment costs while reducing the sludge moisture content.

[0024] (5) The sludge treated by the present invention can be used as a resource in a variety of ways. Phosphogypsum and calcium carbonate release abundant calcium and sulfur nutrients after co-grinding, while steel slag can provide trace elements such as iron and manganese that are essential for plant growth. In addition, calcium carbonate helps optimize soil pore structure and enhance soil aggregation stability, providing a high-quality material for agriculture and ecological restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a bar chart comparing the moisture content of the filter cakes after conditioning and filter pressing of the sludge described in Comparative Examples 1 to 3 and Examples 1 to 3.

[0026] Figure 2 The figure is a comparison chart of the pH values ​​of the sludge after treatment in Comparative Examples 1-3 and Examples 1-3. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0028] The calcium carbonate, phosphogypsum and steel slag used in each embodiment are of the same source, and the moisture content is no more than 5%; the steel slag used in the embodiments and the comparative examples is of the same source. In addition, the filter press dehydration operations in the embodiments and the comparative examples are carried out under the same conditions.

[0029] Example 1

[0030] A method for preparing a pipe network sludge conditioner comprises the following steps:

[0031] Calcium carbonate and phosphogypsum are mixed in a mass ratio of 0.6:1, added to a ball mill, and ball milled for 30 minutes at a rotation speed of 200 rpm to obtain a co-ground powder; the co-ground powder is evenly mixed with steel slag in a mass ratio of 24:1 to prepare the pipeline sludge conditioner.

[0032] The pipe network sludge conditioner prepared in Example 1 was added to pipe network sludge with a moisture content of 80.83% (10 wt % of the dry weight of the pipe network sludge). The sludge was stirred for 2 hours for conditioning. After conditioning, the pH value of the sludge was tested to be 9.78. The conditioned sludge was then passed through a plate and frame filter press for dehydration, resulting in a filter cake with a moisture content of 42.39%.

[0033] Example 2

[0034] A method for preparing a pipe network sludge conditioner comprises the following steps:

[0035] Calcium carbonate and phosphogypsum are mixed in a mass ratio of 0.6:1, added to a ball mill, and ball milled for 30 minutes at a rotation speed of 200 rpm to obtain a co-ground powder; the co-ground powder is evenly mixed with steel slag in a mass ratio of 24:1 to prepare the pipeline sludge conditioner.

[0036] The pipe network sludge conditioner prepared in Example 2 was added to pipe network sludge with a moisture content of 80.83% (15 wt % of the dry weight of the pipe network sludge). The sludge was stirred for 2 hours for conditioning. After conditioning, the pH value of the sludge was tested to be 9.17. The conditioned sludge was then passed through a plate and frame filter press for dehydration, resulting in a filter cake with a moisture content of 39.75%.

[0037] Example 3

[0038] A method for preparing a pipe network sludge conditioner comprises the following steps:

[0039] Calcium carbonate and phosphogypsum are mixed in a mass ratio of 0.6:1, added to a ball mill, and ball milled for 30 minutes at a rotation speed of 200 rpm to obtain a co-ground powder; the co-ground powder is evenly mixed with steel slag in a mass ratio of 24:1 to prepare the pipeline sludge conditioner.

[0040] The pipe network sludge conditioner prepared in Example 3 was added to pipe network sludge with a moisture content of 80.83% (20 wt % of the dry weight of the pipe network sludge). The sludge was stirred for 2 hours for conditioning. After conditioning, the pH value of the sludge was tested to be 8.66. The conditioned sludge was then passed through a plate and frame filter press for dehydration, resulting in a filter cake with a moisture content of 37.86%.

[0041] Comparative Example 1

[0042] Steel slag was added to pipe network sludge with a moisture content of 80.83% (10% by weight of the dry weight of the sludge) and stirred for two hours to condition the sludge. After conditioning, the pH value of the sludge was tested to be 11.08. The conditioned sludge was then filtered and dehydrated in a plate and frame filter press, resulting in a filter cake with a moisture content of 47.15%.

[0043] Comparative Example 2

[0044] Steel slag was added to pipe network sludge with a moisture content of 80.83% (15% by weight of the dry weight of the sludge) and stirred for two hours to condition the sludge. After conditioning, the pH value of the sludge was tested to be 11.24. The conditioned sludge was then filtered and dehydrated in a plate and frame filter press, resulting in a filter cake with a moisture content of 43.84%.

[0045] Comparative Example 3

[0046] Steel slag was added to pipe network sludge with a moisture content of 80.83% (20% by weight of the dry weight of the sludge) and stirred for two hours to condition the sludge. After conditioning, the pH value of the sludge was tested to be 11.41. The conditioned sludge was then filtered and dehydrated in a plate and frame filter press, resulting in a filter cake with a moisture content of 40.28%.

[0047] Figure 1 The bar chart shows the moisture content of the filter cakes after conditioning and filter pressing of the sludge in Comparative Examples 1 to 3 and Examples 1 to 3. Figure 1 It can be seen that after being treated with the conditioning agent of the present invention, the moisture content of the pipeline sludge is reduced to a certain extent compared with ordinary steel slag.

[0048] Figure 2The comparison of pH value of sludge after treatment with steel slag and the conditioner of the present invention at different addition amounts. Figure 2 The data show that the pH of sludge treated with steel slag increases with the amount of steel slag added (as a percentage of the dry sludge weight); when the amount of steel slag added reaches 20 wt%, the pH of the treated sludge reaches 11.41. In contrast, when the conditioner of the present invention is used to treat sludge at an addition level of 10-20 wt%, the pH of the sludge remains between 8.66 and 9.78, exhibiting a slightly alkaline characteristic. This slightly alkaline sludge simplifies subsequent treatment processes and reduces processing costs.

[0049] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a pipe network sludge conditioner, characterized in that: The method comprises the following steps: mixing calcium carbonate and phosphogypsum in a mass ratio of 0.45-0.65:1 and ball milling the mixture to obtain a co-ground powder with a particle size of 60-90 μm; and uniformly mixing the co-ground powder with steel slag in a mass ratio of 24-30:1 to prepare the pipeline sludge conditioner.

2. The method for preparing the pipe network sludge conditioner according to claim 1, characterized in that: The mass ratio of the calcium carbonate to the phosphogypsum is 0.6:

1.

3. The method for preparing the pipe network sludge conditioner according to claim 1, characterized in that: The rotation speed of the ball mill is 180-220 r / min.

4. The method for preparing the pipe network sludge conditioner according to claim 3, characterized in that: The rotation speed of the ball mill is 200 r / min.

5. The method for preparing the pipe network sludge conditioner according to claim 1, characterized in that: The ball milling time is 25 to 35 minutes.

6. The method for preparing the pipe network sludge conditioner according to claim 5, characterized in that: The ball milling time is 30 min.

7. The method for preparing the pipe network sludge conditioner according to claim 1, characterized in that: The water content of the calcium carbonate, phosphogypsum and steel slag does not exceed 5%.

8. The pipeline sludge conditioner prepared by the preparation method of the pipeline sludge conditioner according to any one of claims 1 to 7.

9. The use of the pipe network sludge conditioner according to claim 8, characterized in that: The method comprises the following steps: adding the pipeline sludge conditioner to the pipeline sludge and stirring evenly, wherein the amount of the pipeline sludge conditioner added accounts for 10-20wt% of the dry weight of the pipeline sludge; and then performing solid-liquid separation on the evenly stirred sludge to obtain a dehydrated filter cake, thereby completing dehydration conditioning.

10. The use according to claim 9, characterized in that The solid-liquid separation method is filter press.

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