Pipe network sludge conditioner as well as preparation method and application thereof

Abstract

The invention discloses a pipe network sludge conditioner as well as a preparation method and application thereof. The preparation method of the pipe network sludge conditioner comprises the following steps: mixing calcium carbonate and phosphogypsum according to a mass ratio of (0.45-0.65): 1, and carrying out ball milling to obtain co-ground powder; and uniformly mixing the co-ground powder with steel slag according to a mass ratio of (24-30): 1 to prepare the pipe network sludge conditioner. The conditioner disclosed by the invention is beneficial to formation of pores in the sludge and promotes release of moisture in the sludge, so that the dehydration effect is effectively improved; after ball milling treatment, the activity of calcium carbonate and phosphogypsum is remarkably enhanced, so that the pH value of the treated sludge is stabilized in an alkalescence range, and the problem that the alkalinity of the sludge is too high when industrial solid wastes such as steel slag are used for conditioning is solved.

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 the existing industrial treatment and disposal system for polluted sludge, there are a large number of dehydrated products in the pipeline network, and its resource disposal has become a key bottleneck to ensure the normal operation and maintenance of the pipeline network. If these sludges are not properly handled, it will have a great negative impact on the environment.

[0003] It is difficult to remove water from pipe network sludge, mainly because its particle structure is flocculating and highly hydrophilic, resulting in extremely high sludge moisture content (94%~99%), which makes the sludge bulky and increases the complexity of subsequent treatment and disposal. The degree of sludge dehydration directly affects the cost of treatment and disposal; the lower the moisture content of the dehydrated sludge, the smaller the mud cake volume, and the corresponding transportation and disposal costs are also lower.

[0004] Although the sludge moisture content can be reduced to 75%~85% after dehydration treatment by mechanical equipment such as filter press or centrifuge, such mechanical methods have high energy consumption and it is difficult to further reduce the sludge moisture content. Usually, sludge conditioners are added to change the sludge floc structure to improve the dehydration performance, and then combined with mechanical means for dehydration. Commonly used conditioners include polyacrylamide, iron salts, aluminum salts and quicklime, etc. However, these materials often require a large dosage, may be toxic to the environment, and affect the subsequent treatment and utilization of sludge. In addition, there is a problem of excessive alkalinity of sludge when using industrial solid waste such as steel slag for conditioning. Therefore, it is urgent 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] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a pipe network sludge conditioner and its preparation method and application. After being treated with the conditioner of the present invention, the pH value of the sludge is stabilized in the slightly alkaline range, which effectively solves the problem of excessive alkalinity of the sludge when using industrial solid waste such as steel slag for conditioning.

[0006] The purpose of the present invention is achieved through the following technical solutions: A method for preparing a pipe network sludge conditioner comprises the following steps: mixing calcium carbonate and phosphogypsum at a mass ratio of 0.45-0.65:1 and ball milling to obtain a co-ground powder with a particle size of 60-90 μm; and uniformly mixing the co-ground powder with steel slag at a mass ratio of 24-30:1 to prepare the pipe network sludge conditioner.

[0007] Preferably, the mass ratio of calcium carbonate to phosphogypsum is 0.6:1.

[0008] Preferably, the rotation speed of the ball mill is 180-220 r / min.

[0009] Preferably, the rotation speed of the ball mill is 200 r / min.

[0010] Preferably, the ball milling time is 25 to 35 min.

[0011] Preferably, the ball milling time is 30 min.

[0012] Preferably, the water content of calcium carbonate, phosphogypsum and steel slag does not exceed 5%.

[0013] The pipeline sludge conditioner prepared by the preparation method of the pipeline sludge conditioner.

[0014] 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 evenly, the amount of the pipeline sludge conditioner added accounts for 10~20wt% of the dry weight of the pipeline sludge, and then separating the evenly stirred sludge into solid and liquid to obtain a dehydrated filter cake, thereby completing dehydration conditioning.

[0015] Preferably, the solid-liquid separation method is filter pressing.

[0016] The mechanism involved in the present invention is: 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 these 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- Combine to form Ca3(PO4)2, the first two parts release the remaining H + Can neutralize excess OH in steel slag - ;CO3 2- Hydrolysis generates a small amount of H2CO3 and OH - , OH -The carbonic acid generated by absorbing CO2 in the air can also act on the alkalinity of the buffered steel slag. This reaction mechanism greatly alleviates the strong alkalinity problem caused by the 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 coagulation effect between particles, thereby improving the sedimentation performance and dehydration efficiency of the sludge. In summary, the present invention not only improves the effect of sludge dehydration, but also solves the problem of increased pH value caused by steel slag, and realizes a more environmentally friendly and efficient sludge treatment solution.

[0017] Compared with the prior art, the beneficial effects of the present invention include: (1) The present invention uses phosphogypsum, which is widely available, as the main raw material, which not only helps to reduce the processing cost, but also due to its high proportion of application, it can consume industrial solid waste more fully than 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.

[0018] (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.

[0019] (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.

[0020] (4) The pH value of the conditioned sludge is stabilized in the slightly alkaline range. The activity of calcium carbonate and phosphogypsum is greatly enhanced through ball milling, effectively solving the problem of strong alkalinity of sludge caused by the use of industrial solid waste such as steel slag. Compared with the method that requires further adjustment of the pH value to deal with the excessive alkalinity of the conditioned sludge, the present invention significantly reduces the overall treatment cost while reducing the moisture content of the sludge.

[0021] (5) The sludge treated by the present invention has multiple resource utilization pathways. 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 necessary for plant growth. In addition, calcium carbonate helps to optimize the soil pore structure and enhance soil aggregation stability, providing high-quality materials for agriculture and ecological restoration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a bar chart comparing 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.

[0023] Figure 2 It is a comparison chart of pH values ​​of the sludge after treatment in Comparative Examples 1-3 and Examples 1-3. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution 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 used to limit the present invention.

[0025] The calcium carbonate, phosphogypsum and steel slag used in each embodiment are from the same source, and the moisture content is no more than 5%; the steel slag used in the embodiments and the comparative examples is from the same source. In addition, the filter pressing and dehydration operations in the embodiments and the comparative examples are carried out under the same conditions.

[0026] Example 1 A method for preparing a pipe network sludge conditioner, comprising the following steps: Calcium carbonate and phosphogypsum are mixed in a mass ratio of 0.6:1, added into 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.

[0027] The pipe network sludge conditioner prepared in Example 1 was added to the pipe network sludge with a moisture content of 80.83%, and the amount of the pipe network sludge conditioner added accounted for 10wt% of the dry weight of the pipe network sludge. The conditioner was stirred for 2 hours for conditioning. After the conditioning, the pH value of the sludge was tested to be 9.78. Further, the conditioned sludge was sent to a plate and frame filter press for filtration and dehydration, and the moisture content of the obtained filter cake was 42.39%.

[0028] Example 2 A method for preparing a pipe network sludge conditioner, comprising the following steps: Calcium carbonate and phosphogypsum are mixed in a mass ratio of 0.6:1, added into 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.

[0029] The pipe network sludge conditioner prepared in Example 2 was added to the pipe network sludge with a moisture content of 80.83%, and the amount of the pipe network sludge conditioner added accounted for 15wt% of the dry weight of the pipe network sludge. The conditioner was stirred for 2 hours for conditioning. After the conditioning, the pH value of the sludge was tested to be 9.17. Further, the conditioned sludge was sent to a plate and frame filter press for filtration and dehydration, and the moisture content of the obtained filter cake was 39.75%.

[0030] Example 3 A method for preparing a pipe network sludge conditioner, comprising the following steps: Calcium carbonate and phosphogypsum are mixed in a mass ratio of 0.6:1, added into 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.

[0031] The pipe network sludge conditioner prepared in Example 3 was added to the pipe network sludge with a moisture content of 80.83%, and the amount of the pipe network sludge conditioner added accounted for 20wt% of the dry weight of the pipe network sludge. The conditioner was stirred for 2 hours for conditioning. After the conditioning, the pH value of the sludge was tested to be 8.66. Further, the conditioned sludge was sent to a plate and frame filter press for filtration and dehydration, and the moisture content of the obtained filter cake was 37.86%.

[0032] Comparative Example 1 Steel slag was added to the pipe network sludge with a moisture content of 80.83%, and the amount of steel slag added accounted for 10wt% of the dry weight of the pipe network sludge. After stirring for 2 hours, the pH value of the sludge was tested to be 11.08. Further, the conditioned sludge was sent to a plate and frame filter press for filtration and dehydration, and the moisture content of the obtained filter cake was 47.15%.

[0033] Comparative Example 2 Steel slag was added to the pipe network sludge with a moisture content of 80.83%, and the amount of steel slag added accounted for 15wt% of the dry weight of the pipe network sludge. After stirring for 2 hours, the pH value of the sludge was tested to be 11.24. Further, the conditioned sludge was sent to a plate and frame filter press for filtration and dehydration, and the moisture content of the obtained filter cake was 43.84%.

[0034] Comparative Example 3 Steel slag was added to the pipe network sludge with a moisture content of 80.83%, and the amount of steel slag added accounted for 20wt% of the dry weight of the pipe network sludge. After stirring for 2 hours, the pH value of the sludge was tested to be 11.41. Further, the conditioned sludge was sent to a plate and frame filter press for filtration and dehydration, and the moisture content of the obtained filter cake was 40.28%.

[0035] Figure 1 The following is a bar chart comparing the moisture content of the filter cakes of the sludges in Comparative Examples 1 to 3 and Examples 1 to 3 after conditioning and filter pressing. 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.

[0036] Figure 2 The pH value of the sludge after being treated with the conditioner of the present invention and steel slag at different addition amounts is compared. Figure 2From the data, we can see that the pH value of the sludge treated with steel slag increases with the increase in the amount of steel slag added (the weight percentage of the dry weight of the sludge); when the amount of steel slag added reaches 20wt%, the pH value of the treated sludge reaches 11.41. On the contrary, when the sludge is treated with the conditioner of the present invention, when the amount of the conditioner added is 10-20wt%, the pH value of the sludge is maintained between 8.66 and 9.78, showing a slightly alkaline characteristic. This slightly alkaline sludge is conducive to simplifying the subsequent treatment process and reducing treatment costs.

[0037] The specific implementation of the present invention described above does not constitute a limitation on the protection scope 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 protection scope 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 to obtain a co-milled powder with a particle size of 60-90 μm; and uniformly mixing the co-milled 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 calcium carbonate to 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 into 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 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 pressing.

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