Environment-friendly sludge curing stabilizer and preparation method thereof

Abstract

The invention provides an environment-friendly sludge curing stabilizer and a preparation method thereof, and the environment-friendly sludge curing stabilizer comprises the following components in parts by weight: 10-25 parts of modified aggregate; 60-70 parts of a cementing agent; 5-30 parts of a water absorbent; the modified aggregate is formed by mixing silica fume and steel slag particles, the cementing agent is composed of slag, fly ash and bentonite, and the water absorbing material is composed of semi-hydrated phosphogypsum, quick lime and red mud; the curing stabilizer is composed of modified aggregate, a cementing agent and a water absorbing material. The environment-friendly sludge curing stabilizer prepared by the invention is used for treating sludge, the water content in 3d is reduced by 80% or more, and the compressive strength exceeds 3MPa; the water content within 14 days is reduced by 90% or above, the compressive strength can reach 6 MPa or above, the compressive strength exceeds the strength grade requirement of a roadbed material, meanwhile, the leaching concentration of heavy metal in the sludge is reduced by 95% or above, the sludge can be used as a building material for resource utilization, and the method has important significance on resource utilization, land occupation reduction and environmental pollution reduction. Wide popularization and application prospects are realized.

Description

Technical Field

[0001] This invention belongs to the field of industrial solid waste resource utilization technology, and specifically relates to an environmentally friendly sludge solidification stabilizer and its preparation method. Background Technology

[0002] Silt contains high levels of water and organic matter, posing a significant risk of heavy metal leaching. During river dredging, large quantities of silt are generated. Using traditional cement and quicklime as solidifying agents results in slow water content reduction and low strength after solidification. Furthermore, the production of cement and quicklime requires calcination, consuming substantial energy and releasing large amounts of carbon dioxide, hindering the achievement of carbon emission targets. The fine particles and high water and organic matter content of silt necessitate high dosages of cement and quicklime for solidification, leading to high stabilization costs. Additionally, the low strength of cement- and quicklime-solidified silt, coupled with the adverse effects of silt storage on surrounding water bodies and soil, poses significant environmental risks and land pressure. Therefore, there is an urgent need to develop a low-cost, environmentally friendly silt solidification and stabilizing agent. Summary of the Invention

[0003] The purpose of this invention is to provide an environmentally friendly sludge solidification stabilizer and its preparation method, which solves the above-mentioned technical problems, has low solidification cost, saves resources and has good effect.

[0004] The above-mentioned technical objective of the present invention is achieved through the following technical solution: an environmentally friendly sludge solidification stabilizer and its preparation method, comprising the following components by weight: Modified aggregate 10-25 parts; binder 60-70 parts; water-absorbing material 5-30 parts; The modified aggregate is composed of silica fume and steel slag particles mixed in a mass ratio of (0.1~0.5):(10~15); the binder is composed of slag powder, fly ash and bentonite; the water-absorbing material is composed of hemihydrate phosphogypsum, quicklime and red mud.

[0005] A further feature of the present invention is that the steel slag particles in the modified aggregate have a diameter of 2-8 mm, and the mixing and homogenization time of silica fume and steel slag particles is 5 min.

[0006] A further feature of the present invention is that the binder is composed of slag powder, fly ash and bentonite mixed in a mass ratio of 5:3:2, and the mixing and homogenization time is 5 minutes.

[0007] A further feature of the present invention is that the absorbent material is made by mixing and grinding hemihydrate phosphogypsum, quicklime, and red mud in a mass ratio of 6:3:1 for 10 minutes, resulting in a specific surface area exceeding 400 m². 2 / kg.

[0008] A further provision of the present invention is that the modified aggregate, binder, and water-absorbing material are mixed and stirred for 10 minutes. A further provision of the present invention is that the amount of the curing stabilizer is 15-20% of the mass of the sludge.

[0009] The beneficial effects of this invention are:

[0010] This invention provides an environmentally friendly sludge solidification stabilizer and its preparation method. The solidification stabilizer is prepared from industrial solid waste hemihydrate phosphogypsum, red mud, slag powder, and fly ash to replace traditional solidification agents such as cement and quicklime. By using a waste-to-waste approach to treat sludge, the solidification cost can be effectively reduced, the consumption of natural resources such as cement and lime can be reduced, and carbon dioxide emissions can be reduced.

[0011] This invention provides an environmentally friendly sludge solidification stabilizer and its preparation method. The modified aggregate, with steel slag particles of 2-8 mm in diameter, serves as a high-strength aggregate. Adding it to sludge significantly improves the particle size distribution and increases its fluidity. Increased sludge fluidity allows the solidification stabilizer to be evenly distributed on the surface of the sludge particles during mixing. After the binder hydrates, the resulting hydration products can fully contact the sludge particles, increasing the coating and filling effects of the hydrated products (ettringite and calcium silicate) on the sludge particles, thereby improving the strength of the solidified sludge.

[0012] This invention provides an environmentally friendly sludge solidification stabilizer and its preparation method. The water-absorbing materials hemihydrate phosphogypsum, quicklime, and red mud can rapidly absorb free water in the sludge and react with it, thereby converting the free water in the sludge into crystal water and chemically bound water. The reduction of free water is a key guarantee for the solidified sludge to maintain its shape and strength. With the rapid reduction of free water in the sludge, the slag, fly ash, bentonite, and calcium hydroxide, sodium silicate, and calcium sulfate dihydrate in the binder undergo a hydration reaction to generate ettringite and hydrated calcium silicate. Needle-shaped ettringite penetrates and fills the pores between aggregates and particles, acting as a filler. The network of hydrated calcium silicate covers the surface of the ettringite, acting as a coating, increasing the density and strength of the solidified sludge.

[0013] This invention provides an environmentally friendly sludge solidification and stabilizer. When solidifying and stabilizing sludge, the 3-day moisture content of the solidified body decreases by 80%, and the compressive strength is not less than 3 MPa. After 14 days, the moisture content decreases by 90%, and the compressive strength can reach over 6 MPa. This meets the compressive strength requirements of municipal roadbed materials, realizing the resource utilization of solidified sludge in the field of roadbed materials, thus effectively solving the problem of difficult sludge resource utilization.

[0014] The present invention provides an environmentally friendly sludge solidification and stabilizer, which, under the combined action of water-absorbing materials and binders, forms a good adsorption and binding effect on heavy metals in sludge, improves the solidification and stabilization effect on heavy metals, and reduces the leaching concentration of common heavy metals such as lead, zinc and cadmium in sludge by more than 90%, meeting the requirements of the Integrated Wastewater Discharge Standard (GB8978). Detailed Implementation

[0015] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Example 1

[0016] This embodiment provides an environmentally friendly sludge solidification stabilizer and its preparation method, which includes the following steps: Step 1: By weight, add 0.5 parts silica fume and 15 parts 2-8mm steel slag particles to the mixing system and mix evenly to form modified aggregate. Mixing time is 5 minutes. Step 2: The binder is made by mixing slag powder, fly ash and bentonite in a mass ratio of 5:3:2, and the mixing and homogenization time is 5 minutes. Step 3: The absorbent material is made by mixing and grinding hemihydrate phosphogypsum, quicklime, and red mud in a mass ratio of 6:3:1 for 10 minutes, resulting in a specific surface area exceeding 400 m². 2 / kg.

[0017] Step 4: Mix 25 parts of modified aggregate, 70 parts of binder and 5 parts of water-absorbing material together and stir evenly for 10 minutes.

[0018] Step 5: Add a certain amount of solidifying stabilizer to the sludge, the amount of solidifying stabilizer being 15% of the sludge mass. Example 2

[0019] This embodiment provides an environmentally friendly sludge solidification stabilizer and its preparation method, which includes the following steps: Step 1: By weight, add 0.1 parts silica fume and 10 parts 2-8mm steel slag particles to the mixing system and mix evenly to form modified aggregate. Mixing time is 5 minutes. Step 2: The binder is made by mixing slag powder, fly ash and bentonite in a mass ratio of 5:3:2, and the mixing and homogenization time is 5 minutes. Step 3: The absorbent material is made by mixing and grinding hemihydrate phosphogypsum, quicklime, and red mud in a mass ratio of 6:3:1 for 10 minutes, resulting in a specific surface area exceeding 400 m². 2 / kg.

[0020] Step 4: Mix 15 parts of modified aggregate, 65 parts of binder and 20 parts of water-absorbing material together and stir evenly for 10 minutes.

[0021] Step 5: Add a certain amount of solidifying stabilizer to the sludge, the amount of solidifying stabilizer being 20% ​​of the sludge mass. Example 3

[0022] This embodiment provides an environmentally friendly sludge solidification stabilizer and its preparation method, which includes the following steps: Step 1: By weight, add 0.3 parts silica fume and 13 parts 2-8mm steel slag particles to the mixing system and mix evenly to form modified aggregate. Mixing time is 5 minutes. Step 2: The binder is made by mixing slag powder, fly ash and bentonite in a mass ratio of 5:3:2, and the mixing and homogenization time is 5 minutes. Step 3: The absorbent material is made by mixing and grinding hemihydrate phosphogypsum, quicklime, and red mud in a mass ratio of 6:3:1 for 10 minutes, resulting in a specific surface area exceeding 400 m². 2 / kg.

[0023] Step 4: Mix 10 parts of modified aggregate, 60 parts of binder and 30 parts of water-absorbing material together and stir evenly for 10 minutes.

[0024] Step 5: Add a certain amount of solidifying stabilizer to the sludge, the amount of solidifying stabilizer being 20% ​​of the sludge mass. Example 4

[0025] This embodiment provides an environmentally friendly sludge solidification stabilizer and its preparation method. Step 4 of the preparation method involves mixing 15 parts by weight of modified aggregate and 65 parts by weight of binder for 10 minutes. No water-absorbing material is added. Other steps are the same as in Embodiment 2. Example 5

[0026] This embodiment provides an environmentally friendly sludge solidification stabilizer and its preparation method. In step 4 of the preparation method, 65 parts by weight of binder and 20 parts by weight of water-absorbing material are mixed together and stirred uniformly for 10 minutes. No modified aggregate is added. The other steps are the same as in Example 2. Example 6

[0027] This embodiment provides an environmentally friendly sludge solidification stabilizer and its preparation method. In step 4 of the preparation method, 15 parts by weight of modified aggregate and 20 parts by weight of water-absorbing material are mixed together and stirred uniformly for 10 minutes. No binder is added. Other steps are the same as in Example 2.

[0028] Performance testing The curing stabilizers from Examples 1-6 were added to the sludge and naturally cured for a certain period of time. Moisture content, compressive strength, and leaching concentration were then tested. The relevant results are shown in Table 1 below. Table 1

[0029] As can be seen from the above table, The environmentally friendly sludge solidification and stabilizer prepared in Examples 1-6 exhibits good performance in solidifying and stabilizing sludge. Its 3-day compressive strength reaches 3.6 MPa, and its 14-day compressive strength reaches 6.8 MPa, far exceeding the compressive strength requirements for municipal roadbed materials. The sludge treated with the solidification and stabilizer shows a 3-day moisture content reduction of over 80% and a 14-day moisture content reduction of over 90%. The leaching concentrations of heavy metals cadmium, lead, and zinc are reduced by over 95%, below the limits set by the GB 8978 Integrated Wastewater Discharge Standard.

[0030] Furthermore, compared with conventional solidification stabilizers, the material provided by this invention uses industrial solid waste slag powder, fly ash, red mud, and hemihydrate phosphogypsum as the main raw materials, and does not require complex calcination steps. The preparation process is simple and energy consumption is low. It is of great significance for realizing the resource utilization of industrial solid waste, reducing the occupation of silt land, and reducing environmental pollution, and has broad prospects for promotion and application.

Claims

1. An environmentally friendly sludge solidification stabilizer and a method for preparing the same, characterized by comprising: By weight parts, including the following components: ​ Modified aggregate 10~25 parts; binder 60~70 parts; water absorption material 5~30 parts; The modified aggregate is mixed by silica fume and steel slag particles according to the mass ratio of (0.1~0.5):(10~15); the binder is composed of slag powder, fly ash and bentonite; the water absorption material is composed of semi-water phosphogypsum, quicklime and red mud.

2. An environmentally friendly sludge solidification stabilizer and a preparation method thereof according to claim 1, characterized in that: The steel slag particle size in the modified aggregate is 2~8mm, and the silica fume and steel slag particle mixing homogenization stirring time is 5min.

3. An environmentally friendly sludge solidification stabilizer and a preparation method thereof according to claim 1, characterized in that: The binder is mixed by slag powder, fly ash and bentonite according to the mass ratio of 5:3:2, and the mixing homogenization stirring time is 5min.

4. An environmentally friendly sludge solidification stabilizer and a preparation method thereof according to claim 1, characterized in that: The water absorption material is prepared by mixing semi-hydrated phosphogypsum, quicklime and red mud in a mass ratio of 6:3:1, and grinding for 10 min, with a specific surface area of more than 400 m 2 / kg.

5. An environmentally friendly sludge solidification stabilizer and a preparation method thereof according to claim 1, characterized in that: The modified aggregate, binder and water absorption material are mixed uniformly for 10min.

6. An environmentally friendly sludge solidification stabilizer and a preparation method thereof according to claim 1, characterized in that: The amount of solidification stabilizer is 15-20% of the mass of sludge.

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