Activity-enhanced solid waste-based sludge curing agent as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of solid waste resource utilization, and discloses an activity-enhanced solid waste-based sludge curing agent as well as a preparation method and application thereof. The sludge curing agent comprises the following raw materials in percentage by mass: 30-40% of cement, 15-25% of S95 mineral powder, 15-23% of steel slag powder, 16-26% of an activity enhancing component and 0.5-3% of a composite exciting agent, wherein the activity enhancing component is prepared from the following raw materials in percentage by mass: 35 to 40 percent of desulfurized gypsum, 35 to 40 percent of carbide slag and 20 to 30 percent of biomass ash; the composite exciting agent comprises the following raw materials in percentage by mass: 30-35% of metakaolin, 30-35% of sodium sulfate, 15-20% of sodium silicate and 15-20% of sulfonated oil. According to the sludge curing agent, the industrial solid waste accounts for 57% or above, the desulfurized gypsum, the carbide slag and the biomass ash form an activity enhancing component, the activity enhancing component is matched with the composite exciting agent to jointly enhance and excite the activity of the metallurgical slag solid waste, and therefore the excellent curing effect is achieved, and when the sludge curing agent is used for sludge curing, the 3d unconfined compressive strength of a sludge curing body is larger than or equal to 0.5 MPa; and the 28d unconfined compressive strength is greater than or equal to 1.4 MPa.

Description

Technical Field

[0001] The invention belongs to the technical field of solid waste resource utilization, and specifically relates to an active enhanced solid waste-based sludge solidifying agent and a preparation method and application thereof. Background Art

[0002] Silt is a soft soil with a large porosity, high water content, high compressibility, low permeability, low strength, high rheology, high sensitivity, and easy thixotropy. The most common silt treatment method at present is chemical solidification, that is, by adding cement, lime and other cementitious materials to the silt, a series of chemical and physical reactions are caused to cause the silt to quickly reduce the water content and solidify the soil. However, the curing cost of cement, lime and other curing agents is relatively high, and they are prone to low long-term strength after curing. They are also high-carbon emission materials and are not environmentally friendly.

[0003] Steel enterprises, thermal power plants, acetylene plants, etc. produce a large amount of industrial solid wastes such as slag, steel slag, flue gas desulfurization gypsum, carbide slag, biomass ash, etc., and their resource utilization is an important issue that plagues the sustainable development of enterprises. If these solid wastes can be used to prepare sludge solidifiers, solid wastes can be reasonably disposed of, and the carbon dioxide emissions of solidifiers can be reduced, turning waste into treasure, and improving the economic value and environmental benefits of various solid wastes. However, the use of these solid wastes to prepare sludge solidifiers faces technical problems such as low gelling activity and insufficient early strength, which limits the development of solid waste-based sludge solidifiers. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide an active enhanced solid waste-based sludge solidifier and its preparation method and application in view of the deficiencies in the prior art. The industrial solid waste accounts for more than 57% of the sludge solidifier, wherein desulfurized gypsum, carbide slag and biomass ash constitute the active enhancing components, which are combined with a composite stimulant to jointly enhance and stimulate the activity of metallurgical slag solid waste, thereby achieving an excellent solidification effect. When used for sludge solidification, the 3d unconfined compressive strength of the sludge solidified body is ≥0.5MPa, and the 28d unconfined compressive strength is ≥1.4MPa.

[0005] In order to solve the technical problem raised by the present invention, the present invention provides an active enhanced solid waste-based sludge solidifying agent, comprising the following raw materials in percentage by weight: 30-40% cement, 15-25% S95 mineral powder, 15-23% steel slag powder, 16-26% active enhancing component, and 0.5-3% composite activator.

[0006] In the above scheme, the cement is ordinary Portland cement with a strength grade of 42.5 and above.

[0007] In the above scheme, the specific surface area of ​​the S95 mineral powder is greater than 400m 2 / kg, 7-day activity index ≥70%, 28-day activity index ≥95%.

[0008] In the above scheme, the steel slag powder is obtained by grinding the liquid converter steel slag after being treated by a hot stewing process, crushing, screening, grading, and magnetic separation to remove iron.

[0009] In the above scheme, the specific surface area of ​​the steel slag powder is ≥330m 2 / kg, moisture content <0.5%, 7d activity index ≥65%, 28d activity index ≥80%.

[0010] In the above scheme, the activity enhancement component includes the following raw materials in percentage by mass: 35-40% of desulfurized gypsum, 35-40% of carbide slag, and 20-30% of biomass ash.

[0011] Furthermore, the desulfurization gypsum is flue gas desulfurization gypsum from a coal-fired power plant, and the CaSO4·H2O content is greater than 50%.

[0012] Furthermore, the carbide slag is waste residue generated when carbide is used to produce chemical raw materials such as acetylene, and the Ca(OH)2 content is greater than 90%.

[0013] Furthermore, the biomass ash is the ash produced by burning biomass fuel in a circulating fluidized bed boiler in a biomass power plant, and is obtained after magnetic separation to remove iron.

[0014] Furthermore, the biomass ash has a SiO2 content of ≥40%, a CaO content of ≥16%, and an Al2O3 content of ≥10%.

[0015] In the above scheme, the composite activator comprises the following raw materials in percentage by weight: 30-35% of metakaolin, 30-35% of sodium sulfate, 15-20% of sodium silicate, and 15-20% of sulfonated oil.

[0016] Furthermore, the specific surface area of ​​the metakaolin is greater than 500m 2 / kg, moisture content <0.5%, Al2O3 content ≥40%, SiO2 content ≥47%.

[0017] Furthermore, the SiO2 content of the sodium silicate is ≥30%.

[0018] Furthermore, the solid content of the sulfonated oil is greater than 50%.

[0019] The present invention also provides a method for preparing an active enhanced solid waste-based sludge solidifying agent, comprising the following steps:

[0020] 1) Cement, S95 mineral powder and steel slag powder are mixed evenly in a mixer to obtain component A;

[0021] 2) After drying the active enhancement component, grind it to a specific surface area of ​​≥400m 3 / kg, to obtain component B;

[0022] 3) Component A, component B and the composite activator are mixed evenly with a mixer to obtain an activity-enhanced solid waste-based sludge solidifying agent.

[0023] In the above scheme, the mixer speed in step 1) is ≥400r / min, and the mixing time is 10 to 15min.

[0024] In the above scheme, the drying temperature in step 2) is 105-110° C. and the drying time is 4-5 hours.

[0025] In the above scheme, the mixer speed in step 3) is ≥400r / min, and the mixing time is 25 to 30min.

[0026] The present invention also provides an application of an active enhanced solid waste-based sludge solidifying agent, and the application method is:

[0027] S1, mixing an active enhanced solid waste-based sludge solidifying agent with water to obtain a solidifying agent working solution;

[0028] S2, adding the curing agent working liquid into the sludge, stirring evenly, and curing to obtain a sludge solidified body.

[0029] In the above scheme, in step S1, the mass ratio of the active enhanced solid waste-based sludge solidifying agent to water is 1:(0.5-1.5).

[0030] In the above scheme, in step S1, the mixing rate is 135-145 r / min, and the mixing time is 50-70 s.

[0031] In the above scheme, the moisture content of the sludge is 20-65%.

[0032] In the above scheme, the dosage of the active enhanced solid waste-based sludge solidifying agent is 5 to 30% of the wet weight of the sludge.

[0033] In the above scheme, in step S2, the stirring rate is 135-145 r / min, and the curing agent working solution is stirred for 5-6 minutes after being added, and then the bottom sludge is turned to the upper layer and stirred for 5-6 minutes to ensure full and uniform stirring.

[0034] In the above scheme, the curing conditions are: temperature 20±2°C, relative humidity 55±5%.

[0035] In the above scheme, the 3d unconfined compressive strength of the sludge solidified body is ≥0.5MPa, and the 28d unconfined compressive strength is ≥1.4MPa.

[0036] The technical principle of the sludge solidifying agent of the present invention is:

[0037] The present invention introduces an active enhancement component into the sludge solidifying agent. The active enhancement component can provide an alkaline environment, promote the hydration reaction, and destroy the glass structure in the mineral powder, making Si-O bonds and Al-O bonds more likely to break, increasing the hydration reaction rate, stimulating potential activity, continuously generating CSH gel, and enhancing the structural connection between soil particles. The active enhancement component in the active enhancement component can provide a suitable calcium-sulfur concentration, and react with water together with the C3S active component in cement and steel slag powder to generate calcium aluminate (AFt), converting the free water in the sludge soil into crystal water, thereby reducing the free water content in the sludge soil. In addition, the carbide slag and desulfurized gypsum can provide more Ca 2+ , same as the silt surface K + 、Na + The ion exchange reaction occurs in the plasma, which strengthens the bonding force between clay particles. The biomass ash in the active enhancement component contains SiO2 and Al2O3 with certain volcanic ash activity, which reacts with excess Ca 2+ A pozzolanic reaction occurs to generate cementitious products CSH and CAH.

[0038] The present invention also introduces a composite activator into the sludge solidifying agent, which can alkali-activate the reaction activity of cement, mineral powder, steel slag powder and other cementitious materials, promote the generation of gels such as CSH, CAH, NASH, etc., and improve the early strength of sludge solidified soil. At the same time, the composite activator has strong water absorption and water retention, and can convert the free water in the sludge into bound water and adsorbed water, thereby enhancing the connection between soil particles and improving the sludge strength. In addition, the adsorbed water can be used for the continued hydrolysis reaction of the cementitious material in the later stage, thereby improving the later strength of the sludge solidified soil. Combining the above effects, the early strength and late strength of the sludge solidified body are improved.

[0039] Compared with the prior art, the present invention has the following beneficial effects:

[0040] 1. The raw materials used in the present invention include industrial solid wastes such as steel slag powder, mineral powder, desulfurized gypsum, carbide slag, biomass ash, etc., which account for more than 57% of the curing agent components. Compared with cement, the cost is low and the curing effect is better. It can reasonably absorb various solid wastes, reduce the carbon dioxide emissions of the curing agent, and turn waste into treasure, thereby improving the economic value and environmental benefits of various solid wastes.

[0041] 2. The present invention comprises active enhancement components composed of carbide slag, desulfurized gypsum and biomass ash, and a composite activator to jointly enhance and stimulate the activity of metallurgical slag solid waste (slag, steel slag), promote the hydration reaction of each active component, reduce the free water content in silt soil, promote ion exchange reaction and volcanic ash reaction, thereby improving the strength of the silt solidified body and achieving an excellent solidification effect. DETAILED DESCRIPTION

[0042] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0043] In the following examples, the cement used is PC 42.5 ordinary Portland cement; the specific surface area of ​​S95 mineral powder is 445m 2 / kg, 7d activity index 73.2%, 28d activity index 98.3%; steel slag powder is the steel slag after liquid converter steel slag is treated by roller pressing and hot stewing process, and then after crushing, screening, grading, magnetic separation and iron removal, the 0-10mm steel slag tailing is ground by roller pressing system, with a specific surface area of ​​340m 2 / kg, moisture content 0.1%, 7d activity index 67.4%, 28d activity index 83.1%.

[0044] In the following embodiments, the desulfurized gypsum selected is flue gas desulfurized gypsum from a coal-fired power plant, with a CaSO4·H2O content of 60.3%; carbide slag is waste residue generated when carbide is used to produce chemical raw materials such as acetylene, with a Ca(OH)2 content of 92.7%; biomass ash is ash generated by a biomass power plant using a circulating fluidized bed boiler to burn biomass fuel, and is obtained after magnetic separation and iron removal, with a SiO2 content of 43.2%, a CaO content of 17.5%, and an Al2O3 content of 12.4%.

[0045] In the following examples, the metakaolin selected has a specific surface area of ​​720 m 2 / kg, water content 0.1%, Al2O3 content 45.5%, SiO2 content 48.5%; SiO2 content of sodium silicate is 35.7%; solid content of sulfonated oil is 53.4%; the sludge was taken from a pond sludge in a certain place, and the water content was 45.3%.

[0046] Embodiments 1 to 5

[0047] The mass percentage of each component of the active enhanced solid waste-based sludge solidifying agent in Examples 1 to 5 is shown in Table 1.

[0048] Table 1 Raw material composition of sludge solidifying agent in each embodiment

[0049]

[0050]

[0051] Among them, the raw material composition of the activity enhancing component is shown in Table 2, and the raw material composition of the composite activator is shown in Table 3.

[0052] Table 2 Raw material composition of active enhancing components in the sludge solidifying agent of each embodiment

[0053] Serial number Desulfurization gypsum Carbide slag Biomass ash Example 1 35 35 30 Example 2 38 35 27 Example 3 36 40 24 Example 4 40 38 22 Example 5 37 39 24

[0054] Table 3 Raw material composition of composite activator in each embodiment of sludge solidifying agent

[0055] Serial number Metakaolin Sodium sulfate Sodium silicate Sulfonated oil Example 1 30 30 20 20 Example 2 32 34 16 18 Example 3 35 30 19 16 Example 4 35 30 20 15 Example 5 30 32 18 20

[0056] The preparation method of the active enhanced solid waste-based sludge solidifying agent in Examples 1 to 5 comprises the following steps:

[0057] 1) Cement, S95 mineral powder and steel slag powder were mixed in a mixer at 450±10r / min for 15min to obtain component A;

[0058] 2) The active enhancement component was dried in a drying oven at 105°C for 4 h, and then mechanically crushed and ground to a specific surface area of ​​450 m 3 / kg, to obtain component B;

[0059] 3) Component A, component B and the composite activator are mixed in a mixer at 450±10 r / min for 30 min to obtain an active enhanced solid waste-based sludge solidifying agent.

[0060] The active enhanced solid waste-based sludge solidifying agent in Examples 1 to 5 is applied, and the application method is as follows:

[0061] S1, mixing the active enhanced solid waste-based sludge solidifying agent and water in a mass ratio of 1:1, with a mixing rate of 140 r / min and a mixing time of 60 s to obtain a solidifying agent working solution;

[0062] S2. Add the curing agent working solution into the sludge so that the dosage of the active enhanced solid waste-based sludge curing agent is 10% of the wet weight of the sludge. First stir at a rate of 140r / min for 5 minutes, then turn the bottom layer of sludge to the upper layer and continue stirring for 5 minutes. After stirring evenly, shape the mixed mud sample into a cube with a length of 10 cm, a width of 10 cm and a height of 10 cm. Curing is carried out at a temperature of 20±2°C and a relative humidity of 55±5% to obtain a sludge solidified body.

[0063] Comparative Example 1

[0064] The difference between Comparative Example 1 and Example 5 is that the sludge solidifying agent is 100% cement.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 2 and Example 5 is that no composite activator is added to the sludge solidifying agent.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 3 and Example 5 is that no active enhancing component is added to the sludge solidifying agent.

[0069] The sludge solidified bodies obtained in Examples 1 to 5 and Comparative Examples 1 to 3 were taken out according to their ages to carry out age strength tests. The test results are shown in Table 4.

[0070] Table 4 Age strength of sludge solidified bodies obtained in various examples and comparative examples

[0071] Serial number 3d unconfined compressive strength (MPa) 28d unconfined compressive strength (MPa) Example 1 0.54 1.57 Example 2 0.62 1.88 Example 3 0.57 1.73 Example 4 0.72 2.11 Example 5 0.66 1.93 Comparative Example 1 0.32 0.86 Comparative Example 2 0.34 0.91 Comparative Example 3 0.13 0.62

[0072] It can be seen from the data of Examples 1 to 5 that after the sludge is solidified by the sludge solidifying agent, the early and late strengths of the solidified body are greatly improved.

[0073] It can be seen from the test data of Comparative Example 1 and Example 5 that the curing effect of the sludge curing agent is stronger than that of the single-component cement curing agent.

[0074] It can be seen from the test data of Comparative Example 2 and Example 5 that if no composite activator is added to the sludge solidifying agent, the strength of the sludge solidified body is reduced.

[0075] It can be seen from the test data of Comparative Example 3 and Example 5 that without adding active reinforcing components to the sludge solidifying agent, the strength of the sludge solidified body is significantly reduced.

[0076] The curing agent of the present invention enhances and stimulates the activity of metallurgical slag solid waste through the active enhancement component and the composite stimulator, promotes the hydration reaction of each active component, reduces the free water content in the silt soil, promotes the ion exchange reaction and the volcanic ash reaction, thereby improving the strength of the silt solidified soil. The curing agent can reasonably absorb solid wastes such as slag, steel slag, desulfurized gypsum, carbide slag, etc., and its physical properties are better than PC 42.5 cement at the same dosage, while achieving the effect of reducing costs and carbon emissions, and improving the economic value and environmental benefits of various solid wastes.

[0077] The above embodiments are merely examples for clear explanation, and are not intended to limit the implementation methods. For those skilled in the art, other different forms of changes or modifications can be made based on the above descriptions. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the protection scope of the invention.

Claims

1. An active enhanced solid waste-based sludge solidifying agent, characterized in that: The invention comprises the following raw materials in percentage by weight: 30-40% cement, 15-25% S95 mineral powder, 15-23% steel slag powder, 16-26% activity enhancing component and 0.5-3% composite activator; the activity enhancing component comprises the following raw materials in percentage by weight: 35-40% desulfurized gypsum, 35-40% carbide slag and 20-30% biomass ash; the composite activator comprises the following raw materials in percentage by weight: 30-35% metakaolin, 30-35% sodium sulfate, 15-20% sodium silicate and 15-20% sulfonated oil.

2. The active enhanced solid waste-based sludge solidifying agent according to claim 1, characterized in that: The cement is ordinary Portland cement with a strength grade of 42.5 or above; the specific surface area of ​​the S95 mineral powder is greater than 400m 2 / kg, 7d activity index ≥70%, 28d activity index ≥95%; the specific surface area of ​​the steel slag powder ≥330m 2 / kg, moisture content <0.5%, 7d activity index ≥65%, 28d activity index ≥80%.

3. The active enhanced solid waste-based sludge solidifying agent according to claim 1, characterized in that: The CaSO4·H2O content of the desulfurized gypsum is greater than 50%; the Ca(OH)2 content of the carbide slag is greater than 90%; the SiO2 content of the biomass ash is ≥40%, the CaO content is ≥16%, and the Al2O3 content is ≥10%.

4. The active enhanced solid waste-based sludge solidifying agent according to claim 1, characterized in that: The specific surface area of ​​the metakaolin is > 500m 2 / kg, water content <0.5%, Al2O3 content ≥40%, SiO2 content ≥47%; the SiO2 content of the sodium silicate is ≥30%; the solid content of the sulfonated oil is >50%.

5. A method for preparing the active enhanced solid waste-based sludge solidifying agent according to any one of claims 1 to 4, characterized in that: The following steps are involved: 1) Cement, S95 mineral powder and steel slag powder are mixed evenly in a mixer to obtain component A; 2) After drying the active enhancement component, grind it to a specific surface area of ​​≥400m 3 / kg, to obtain component B; 3) Component A, component B and the composite activator are mixed evenly with a mixer to obtain an activity-enhanced solid waste-based sludge solidifying agent.

6. The method for preparing the active enhanced solid waste-based sludge solidifying agent according to claim 5, characterized in that: The mixer speed in step 1) is ≥400r / min, and the mixing time is 10 to 15min; the drying temperature in step 2) is 105 to 110°C, and the drying time is 4 to 5h; the mixer speed in step 3) is ≥400r / min, and the mixing time is 25 to 30min.

7. A method for using the active enhanced solid waste-based sludge solidifying agent according to any one of claims 1 to 4, characterized in that: The following steps are involved: S1, mixing an active enhanced solid waste-based sludge solidifying agent with water to obtain a solidifying agent working solution; S2, adding the curing agent working liquid into the sludge, stirring evenly, and curing to obtain a sludge solidified body.

8. The application method of the active enhanced solid waste-based sludge solidifying agent according to claim 7, characterized in that: In step S1, the mass ratio of the active enhanced solid waste-based sludge solidifying agent to water is 1:(0.5-1.5), the mixing rate is 135-145 r / min, and the mixing time is 50-70 s.

9. The application method of the active enhanced solid waste-based sludge solidifying agent according to claim 7, characterized in that: The water content of the sludge is 20-65%; the dosage of the active enhanced solid waste-based sludge solidifying agent is 5-30% of the wet weight of the sludge.

10. The application method of the active enhanced solid waste-based sludge solidifying agent according to claim 7, characterized in that: The curing conditions are: temperature 20±2°C, relative humidity 55±5%; the 3d unconfined compressive strength of the sludge solidified body is ≥0.5MPa, and the 28d unconfined compressive strength is ≥1.4MPa.

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