Method for preparing active mixed material by calcining sludge-based solid waste at high temperature

Abstract

The invention relates to the technical field of sludge resource utilization, in particular to a method for preparing an active mixed material through high-temperature calcination of sludge-based solid waste, which comprises the following steps: S1, raw material mixing: mixing 14-16% of carbide slag, 2-3% of phosphogypsum and the balance of sludge powder for 15-20 minutes in percentage by mass to obtain co-doped sludge; s2, high-temperature calcination: calcining the co-doped sludge obtained in S1 according to a calcining method as follows: heating to 780-785 DEG C at a rate of 6-8 DEG C / min, then heating to 880-885 DEG C at a rate of 2-4 DEG C / min, preserving heat for 25-35 min, naturally cooling in a furnace to room temperature after heat preservation is finished, and taking out to obtain calcined sludge; according to the method, the sludge is calcined, crystal structures of quartz and muscovite in the sludge are partially destroyed, amorphous silicon-aluminum components are generated, the microstructure is loose and porous, the porosity is increased, the volcanic ash activity is remarkably improved, CSG and PG are doped into the sludge, decomposition of the quartz and the muscovite is further promoted, and the gelling activity of the calcined sludge is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of sludge resource utilization, and particularly relates to a method for preparing active mixed material from high-temperature calcined sludge-based solid waste. BACKGROUND

[0002] Due to the presence of Si and Al components in sludge, the sludge has potential pozzolanic activity, and thus the sludge is used as an admixture of cement, concrete and other materials. However, due to the low activity of the sludge itself and the insufficient calcium content, direct mixing of the sludge will significantly weaken the mechanical properties and durability of concrete or paste, and limit the increase of the replacement ratio. Generally, the replacement ratio of the sludge directly replacing cement is usually not more than 10-15%, otherwise the performance will be reduced, which seriously affects the engineering application. Therefore, simply using the sludge as a replacement mineral admixture cannot fundamentally solve the technical bottleneck of resource utilization.

[0003] In view of the problem of insufficient activity of the sludge, the prior art proposes to heat activate the sludge by high-temperature calcination. However, only calcining the sludge, the product still has obvious deficiencies: firstly, the calcium content of the sludge is low, and after heat activation, the sludge has a certain activity, but lacks the conditions to form stable hydration products; secondly, the high calcination temperature is easy to lead to mineral phase stabilization (such as the formation of mullite), which reduces the activity; thirdly, even after calcination treatment, the hydration reaction rate and product generation amount are still limited, which is difficult to form an effective cementitious system with cement.

[0004] By introducing solid waste such as carbide slag, phosphogypsum, fly ash and steel slag, and calcining the solid waste together with the sludge, the chemical reactions between multiple components can be utilized to achieve synergistic activation. For example, the carbide slag is rich in CaO, and the phosphogypsum contains CaO and SO3, which can react with the Si and Al components in the sludge under high temperature conditions to generate C2S, CA and AFt, etc. mineral phases with hydration activity, thereby significantly improving the cementitious properties of the calcined product. And research shows that the synergistic calcination system can generate hydration products in a short age period, and form a dense pore structure in the long-term solidification process, thereby improving the performance.

[0005] However, the existing multi-solid waste co-calcination technology still has the following shortcomings: firstly, the sources of different solid wastes are complex, and the composition difference is large, which leads to insufficient raw material adaptability, resulting in unstable system performance; secondly, existing researches are mostly focused on single factor investigation, lacking of system optimization of multi-factor coupling, resulting in unreasonable ratio design; thirdly, the selection of calcination process parameters (such as temperature, heating rate, holding time, etc.) has not formed a unified standard, and the product performance fluctuates greatly; fourthly, although some systems can obtain high strength under laboratory conditions, there are problems such as high energy consumption, high cost and increased carbon emissions in large-scale application, which is difficult to meet the requirements of green and low-carbon development. Therefore, the existing sludge co-calcination technology still needs to be improved in stability, economy and environmental protection. SUMMARY

[0006] In order to solve the above problems, the present application provides a method for preparing active mixed material from high-temperature calcined sludge-based solid waste.

[0007] A method for preparing active mixed material from high-temperature calcined sludge-based solid waste, comprising the following steps:

[0008] S1, raw material mixing:

[0009] According to the mass percentage, 14-16% of carbide slag powder, 2-3% of phosphogypsum powder, and the rest of sludge powder are mixed for 15-20 min to obtain a mixed sludge.

[0010] S2, high-temperature calcination:

[0011] The mixed sludge obtained in S1 is calcined by the following method: first, increase the temperature to 780-785℃ at a rate of 6-8℃ / min, then increase the temperature to 880-885℃ at a rate of 2-4℃ / min, and keep the temperature for 25-35 min. After the holding time is over, the sample is taken out after natural cooling to room temperature in the furnace to obtain the active mixed material.

[0012] Further, the preparation method of the sludge powder is as follows: after dewatering and drying the sludge to a water content of 60-80%, it is dried in the sun for 3 days, then hot-dried at 100-110℃ to a constant weight, and finally ball-milled for 14-16 min to obtain a sludge powder with a particle size of 4-150μm.

[0013] Note: Dewatering and drying avoids the problem of increased porosity due to water flashing during subsequent high-temperature calcination, improving the density of cement clinker. Hot drying reduces the risk of harmful gas generation during calcination. Ball-milling significantly increases the specific surface area, making the inorganic components such as silicon, aluminum and iron in the sludge more fully exposed. In the subsequent calcination, these components can quickly participate in the solid-phase reaction of cement minerals, shortening the clinker formation time.

[0014] Further, the preparation method of the carbide slag powder is: ball milling the carbide slag for 14-16 min to obtain the carbide slag powder.

[0015] Description: The incorporation of CSG largely destroys the crystal structure of quartz and muscovite in the calcined sludge, largely converts the siliceous and aluminous components into free state, generates amorphous siliceous and aluminous components, and the calcium components generated by the decomposition of CSG under high temperature environment react with the free siliceous and aluminous components to generate anorthite and calcium gel mineral CA, etc., thereby improving the compressive strength.

[0016] Further, the preparation method of the phosphogypsum powder is: ball milling the phosphogypsum for 14-16 min to obtain the phosphogypsum powder.

[0017] Description: The incorporation of PG largely destroys the crystal structure of quartz and muscovite in the sludge, largely converts the siliceous and aluminous components into free state, generates amorphous siliceous and aluminous components, and the PG reacts with the free siliceous and aluminous components under high temperature environment to generate anorthite and gel mineral CA, etc.; the incorporation of PG generates ettringite in the calcined sludge system, thereby improving the early strength.

[0018] Further, the phosphogypsum powder is subjected to activation and modification treatment, and the method is:

[0019] The silica sol with a solid content of 50-55% is subjected to magnetic stirring with polyvinylpyrrolidone accounting for 0.4-0.45% of the silica sol for 1-1.5 h, then 0.1-0.2 mol / L acetic acid is added to adjust the pH to 6.0-6.5, and the mixture is subjected to stirring in a constant-temperature water bath at 35-36℃ for 1.5-2 h to obtain a modified sol; the modified sol is subjected to freeze-drying, then is subjected to ball milling for 25-30 min and is sieved through a 200-mesh screen to obtain a modified powder; the phosphogypsum powder and the modified powder are mixed at a mass ratio of 26-28:1 at 48-50℃ for 25-30 min to obtain a pre-modified phosphogypsum.

[0020] The silica sol with a solid content of 35-45% is subjected to magnetic stirring with polyethylene glycol accounting for 0.5-0.6% of the silica sol for 1-1.5 h, then 1-2% of silane coupling agent is added to the silica sol, and the pH is adjusted to 6.5-7 with 0.1-0.2 mol / L citric acid, and the mixture is subjected to stirring in a constant-temperature water bath at 38-40℃ for 4-4.5 h to obtain a modified gel; the modified gel is washed with deionized water, and the pre-modified phosphogypsum is mixed with the modified gel at a mass ratio of 1:18-20 at 45-50℃ for 30-40 min, and then is subjected to air drying and crushing through a 100-mesh screen to obtain the activated and modified phosphogypsum, and the activation and modification treatment is completed.

[0021] Note: The powder silica sol (porous structure) and the gel silica sol (continuous silica-based layer) on the surface of the modified phosphogypsum will be converted into amorphous SiO2 glass during subsequent calcination, which is rich in unsaturated Si-O bonds on the surface, can weaken the stability of the quartz lattice, promote the decomposition of quartz in the sludge, and activate the modified phosphogypsum to slow down the volatilization speed of SO2, so that SO42- remains in the system, stabilizes the high-activity calcium silicate crystal form, avoids its conversion to the inert γ phase, long-term retains the cementing activity of C2S, and avoids the strength decline caused by crystal form conversion when the calcined sludge is added into the cement system; and the activated modified phosphogypsum can accelerate the formation of ettringite and improve the early strength of the calcined sludge.

[0022] Further, the parameters of the freeze-drying include: a temperature of -50 to -40℃ and a time of 7 to 7.5h.

[0023] Note: Too small or too large parameters are easy to cause the phosphogypsum powder to collapse or lattice shrinkage, affecting the subsequent improvement of the cementing performance of the sludge.

[0024] Further, the parameters of the air-drying include: a temperature of 80 to 85℃ and a time of 3 to 3.5h.

[0025] Note: Too small or too large parameters are easy to cause the activated modified phosphogypsum to crack or agglomerate, affecting the subsequent improvement of the cementing performance of the sludge.

[0026] Further, in S1, the mixing method is:

[0027] First, the sludge powder is separated to obtain A-type sludge powder with a particle size of ≤80μm and B-type sludge powder with other particle sizes;

[0028] The A-type sludge powder is immersed in a NaOH solution with a mass fraction of 3 to 5% at a solid-liquid ratio of 1g:4 to 6mL, preliminary immersion is performed for 10 to 15min, after the immersion is completed, the immersion pressure is increased to 1 to 1.5MPa, and microwave heating is performed at 700 to 750W to 90 to 95℃, after the heating is completed, the temperature is kept unchanged, the pressure is released to normal pressure, stirring immersion is performed for 10 to 15min, and then drying is performed, the dried A-type sludge powder and the carbide slag powder are stirred and mixed at 50 to 55℃ for 30 to 35min to obtain an A-type mixture;

[0029] The B-type sludge powder is treated by plasma at a power of 100 to 200W for 15 to 20min, and then the B-type sludge powder treated by plasma and the phosphogypsum powder are stirred and mixed for 25 to 30min to obtain a B-type mixture;

[0030] The A-type mixture and the B-type mixture are further added into a microchannel reactor for high-shear mixing, the pressure is 1 to 2MPa, the temperature is 50 to 55℃, and the shear rate is 800 to 1000s-1.-1 Time is 15-20s, cycle 2-3 times, mixing is completed.

[0031] Description: NaOH solution penetrates into the organic matter of sludge under high pressure, releasing the wrapped silicon-aluminum minerals; microwave heating makes the molecules move violently, accelerating the reaction of lye with active SiO2 and Al2O3 to generate sodium silicate gel, and subsequent drying and solidification form a porous framework; low-temperature plasma bombards the surface of sludge, etching the organic film and generating microcracks, exposing the internal apatite; at the same time, part of the sulfide is oxidized to SO42-, reducing the release of SO2 during calcination, and after mixing with phosphogypsum, CaSO4·2H2O fills the microcracks, which can promote the generation of ettringite at high temperature, and high-speed shearing mixing improves the uniformity of mixing, thereby improving the cementing performance of calcined sludge.

[0032] Further, during the preliminary immersion, ozone microbubbles with a diameter of 50-200nm are injected into the NaOH solution under a nitrogen pressure of 0.5-0.6MPa, and the injection rate is 0.3-0.6L / min.

[0033] Description: Ozone microbubbles increase the degradation rate of extracellular polysaccharides, thereby increasing the dissolution rate of silicon and aluminum, and can provide sufficient reaction substrates for the subsequent generation of calcium silicate hydrate (C-S-H).

[0034] Compared with the existing sludge building material utilization method, the beneficial effects of the present application are:

[0035] (1) The present application calcines the sludge, significantly improving the activity of the sludge, and the crystal structure of quartz and muscovite in the calcined sludge is partially destroyed, generating amorphous silicon-aluminum components, loose and porous microstructure, increased porosity, and significantly improved pozzolanic activity.

[0036] (2) The present application adds CSG and PG to the sludge, the addition of CSG further promotes the decomposition of quartz and muscovite, generating calcium feldspar and calcium gel mineral CA, improving the cementing activity of calcined sludge and the compressive strength of sludge building material utilization, CSG re-doping reacts with Ca(OH)2 in the cement hydration environment to generate C-(A)-S-H gel, consuming CH, and the generated dense structure reduces the porosity, improving the hydration performance of calcined sludge; PG re-doping promotes the decomposition of quartz and muscovite, generating more amorphous silicon-aluminum components, the addition of sulfate stabilizes the high-activity dicalcium silicate (alpha-CS) crystal form, avoiding its transformation to the inert gamma phase, and rapidly generating additional ettringite through nucleation reaction with calcium aluminate in cement, which is beneficial to the generation of early strength, improving the cementing activity of calcined sludge and the compressive strength of cement paste, T2 nuclear magnetic resonance analysis shows that the porosity of PG re-doped calcined sludge cement paste is reduced, and the pore structure is optimized.

[0037] (3) When the classified mixed sludge powder, phosphogypsum and carbide slag are classified, the NaOH solution penetrates into the inside of the sludge organic matter under high pressure to release the wrapped silicon aluminum minerals; the microwave heating makes the molecules move violently to accelerate the reaction of the lye with the active SiO2 and Al2O3 to generate sodium silicate gel, and the subsequent drying and solidification form a porous framework; the low-temperature plasma bombards the surface of the sludge to etch the organic film and generate microcracks, so that the internal apatite is exposed; at the same time, part of the sulfide is oxidized to SO42-, reducing the release of SO2 during calcination, and after mixing with the phosphogypsum, the CaSO4·2H2O fills the microcracks, which can promote the generation of ettringite at high temperature, and high-speed shearing mixing improves the mixing uniformity, thereby improving the cementing property of the calcined sludge. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the compressive strength result comparison chart of the experimental example of the active mixed material of the present application;

[0039] Figure 2 is the compressive strength result comparison chart of the experimental example of the active mixed material of the present application;

[0040] Figure 3 is the compressive strength result comparison chart of the experimental example of the active mixed material of the present application. DETAILED DESCRIPTION

[0041] In order to further illustrate the manner of carrying out the application and to enable one to understand the effects attained by its use, the technical solutions of the present application will be described in detail below with reference to experiments.

[0042] Embodiment 1: A method for preparing an active mixed material from high-temperature calcined sludge-based solid waste, comprising the following steps:

[0043] S1, mixing of raw materials:

[0044] According to the mass percentage, 14.78% of carbide slag powder, 2.26% of phosphogypsum powder and the rest of sludge powder are mixed for 18 min to obtain a re-mixed sludge;

[0045] S2, high-temperature calcination:

[0046] The re-mixed sludge obtained in S1 is calcined, and the calcination method is as follows: first, increase the temperature to 782.45℃ at a rate of 7℃ / min, then increase the temperature to 882.45℃ at a rate of 3℃ / min, keep the temperature for 30 min, and then take out after natural cooling to room temperature in the furnace to obtain the active mixed material;

[0047] The preparation method of the sludge powder is as follows: the sludge taken from the sewage purification company of Zhengzhou City, Henan Province is dewatered and dried to a water content of 70%, then is dried under the action of natural sunlight for 3 days, and then is dried under the action of heat at 105 DEG C until the weight is constant, and then is ball milled for 15 minutes by using a SM500*500 type cement test mill to obtain the sludge powder with a particle size of 50-100 mu m.

[0048] The preparation method of the calcium carbide slag powder is as follows: the calcium carbide slag taken from Haohua Aerospace Chemical Co., Ltd. is ball milled for 15 minutes by using a SM500*500 type cement test mill to obtain the calcium carbide slag powder.

[0049] The preparation method of the phosphogypsum powder is as follows: the phosphogypsum taken from Enshi, Hubei is ball milled for 15 minutes by using a SM500*500 type cement test mill to obtain the phosphogypsum powder.

[0050] The chemical composition of the sludge powder includes, in percentage by mass: 38.97% of SiO2, 11.71% of Al2O3, 4.09% of Fe2O3, 3.44% of CaO, 2.11% of MgO, 0.47% of TiO2, 1.12% of Na2O, 2.15% of K2O, and the balance is loss on ignition.

[0051] The chemical composition of the phosphogypsum powder includes, in percentage by mass: 3.19% of SiO2, 0.57% of Al2O3, 48.98% of SO3, 0.18% of Fe2O3, 38.25% of CaO, 0.18% of MgO, 1.25% of P2O5, 0.08% of K2O, and the balance is loss on ignition.

[0052] The chemical composition of the calcium carbide slag powder includes, in percentage by mass: 3.32% of SiO2, 1.08% of Al2O3, 0.24% of Fe2O3, 67.9% of CaO, 0.12% of MgO, 0.32% of TiO2, 0.13% of Na2O, 1.1% of K2O, and the balance is loss on ignition.

[0053] Example 2: The difference between this example and example 1 is that the sludge is dewatered and dried to a water content of 80%, then is dried under the action of natural sunlight for 3 days, and then is dried under the action of heat at 100 DEG C until the weight is constant, and then is ball milled for 14 minutes to obtain the sludge powder with a particle size of 100-150 mu m.

[0054] Example 3: The difference between this example and example 1 is that the sludge is dewatered and dried to a water content of 60%, then is dried under the action of natural sunlight for 3 days, and then is dried under the action of heat at 110 DEG C until the weight is constant, and then is ball milled for 16 minutes to obtain the sludge powder with a particle size of 4-50 mu m.

[0055] Example 4: The difference between this example and Example 1 is that the preparation method of the carbide slag powder is: ball milling the carbide slag for 14 min to obtain the carbide slag powder.

[0056] Example 5: The difference between this example and Example 1 is that the preparation method of the carbide slag powder is: ball milling the carbide slag for 16 min to obtain the carbide slag powder.

[0057] Example 6: The difference between this example and Example 1 is that the preparation method of the phosphogypsum powder is: ball milling the phosphogypsum for 14 min to obtain the phosphogypsum powder.

[0058] Example 7: The difference between this example and Example 1 is that the preparation method of the phosphogypsum powder is: ball milling the phosphogypsum for 16 min to obtain the phosphogypsum powder.

[0059] Example 8: The difference between this example and Example 1 is that S1, the raw materials are mixed in proportion for 15 min to obtain the mixed sludge; S2, the mixed sludge obtained in S1 is calcined, and the calcination method is: first increased to 780℃ at a rate of 6℃ / min, then increased to 880℃ at a rate of 2℃ / min, and kept for 25 min, and after the end of the heat preservation, it is naturally cooled to room temperature in the furnace and taken out to obtain the active mixed material.

[0060] Example 9: The difference between this example and Example 1 is that S1, the raw materials are mixed in proportion for 20 min to obtain the mixed sludge; S2, the mixed sludge obtained in S1 is calcined, and the calcination method is: first increased to 785℃ at a rate of 8℃ / min, then increased to 885℃ at a rate of 4℃ / min, and kept for 35 min, and after the end of the heat preservation, it is naturally cooled to room temperature in the furnace and taken out to obtain the active mixed material.

[0061] Example 10: The difference between this example and Example 1 is that the phosphogypsum powder is activated and modified, and the method is:

[0062] The silica sol with a solid content of 52% is magnetically stirred with 0.42wt% of the silica sol polyvinylpyrrolidone for 1.2h, and then adjusted to pH 6.2 with 0.15mol / L acetic acid, and stirred in a 35℃ constant temperature water bath for 1.8h to obtain a modified sol; the modified sol is poured into a-45℃ freeze dryer for 7.2h, then ball milled for 28min and sieved through a 200 mesh sieve to obtain a modified powder; the phosphogypsum powder and the modified powder are mixed at a mass ratio of 27:1 at 49℃ for 28min to obtain a pre-modified phosphogypsum.

[0063] The silica sol with solid content of 40% was stirred with 0.55wt% of the polyethylene glycol based on the silica sol by magnetic force for 1.2h, then 1.5wt% of the silane coupling agent KH560 based on the silica sol was added, and the pH was adjusted to 6.8 with 0.15mol / L of citric acid, and then the mixture was stirred in a constant temperature water bath at 39°C for 4.2h to obtain a modified gel. The modified gel was washed with deionized water, and then mixed with the pre-modified phosphogypsum at a mass ratio of 1:19 at 48°C for 35min, and then dried by blowing air at 82°C for 3.2h, and then crushed through a 100 mesh sieve to obtain the activated modified phosphogypsum, and the activation and modification treatment was completed.

[0064] Example 11: The difference between this example and Example 10 is that the silica sol with solid content of 50% was stirred with 0.4wt% of the polyvinylpyrrolidone based on the silica sol by magnetic force for 1h, and then the pH was adjusted to 6.0 with 0.1mol / L of acetic acid, and then the mixture was stirred in a constant temperature water bath at 35°C for 1.5h to obtain a modified sol.

[0065] Example 12: The difference between this example and Example 10 is that the silica sol with solid content of 55% was stirred with 0.45wt% of the polyvinylpyrrolidone based on the silica sol by magnetic force for 1.5h, and then the pH was adjusted to 6.5 with 0.2mol / L of acetic acid, and then the mixture was stirred in a constant temperature water bath at 35-36°C for 2h to obtain a modified sol.

[0066] Example 13: The difference between this example and Example 10 is that the modified sol was poured into a freeze dryer at -40°C for 7h, and then crushed through a 200 mesh sieve after ball milling for 25min to obtain a modified powder.

[0067] Example 14: The difference between this example and Example 10 is that the modified sol was poured into a freeze dryer at -50°C for 7.5h, and then crushed through a 200 mesh sieve after ball milling for 30min to obtain a modified powder.

[0068] Example 15: The difference between this example and Example 10 is that the phosphogypsum was mixed with the modified powder at a mass ratio of 26:1 at 48°C for 25min to obtain a pre-modified phosphogypsum.

[0069] Example 16: The difference between this example and Example 10 is that the phosphogypsum was mixed with the modified powder at a mass ratio of 28:1 at 50°C for 30min to obtain a pre-modified phosphogypsum.

[0070] Example 17: The difference between this example and Example 10 is that the silica sol with solid content of 35% was stirred with 0.5wt% of the polyethylene glycol based on the silica sol by magnetic force for 1h, then 1wt% of the silane coupling agent based on the silica sol was added, and the pH was adjusted to 6.5 with 0.1mol / L of citric acid, and then the mixture was stirred in a constant temperature water bath at 38°C for 4h to obtain a modified gel.

[0071] Example 18: The difference between this example and example 10 is that the silica sol with a solid content of 45% is stirred with 0.6wt% of polyethylene glycol relative to the silica sol for 1.5h, then 2wt% of silane coupling agent relative to the silica sol is added, and after adjusting the pH to 7 with 0.2mol / L citric acid, it is stirred in a constant temperature water bath at 40°C for 4.5h to obtain a modified gel.

[0072] Example 19: The difference between this example and example 10 is that the modified gel is washed with deionized water and then mixed with pre-modified phosphogypsum at a mass ratio of 1:18 at 45°C for 30min, then dried at 80°C with a blast for 3h, and crushed to pass through a 100 mesh sieve to obtain activated modified phosphogypsum.

[0073] Example 20: The difference between this example and example 10 is that the modified gel is washed with deionized water and then mixed with pre-modified phosphogypsum at a mass ratio of 1:20 at 50°C for 40min, then dried at 85°C with a blast for 3.5h, and crushed to pass through a 100 mesh sieve to obtain activated modified phosphogypsum.

[0074] Example 21: The difference between this example and example 10 is that the mixing method is as follows:

[0075] First, the sludge powder is separated to obtain A-type sludge powder with a particle size of ≤80μm and B-type sludge powder with the rest of the particle size;

[0076] The A-type sludge powder is immersed in a NaOH solution with a mass fraction of 4% at a solid-liquid ratio of 1g:5mL, and is subjected to preliminary immersion for 13min, during which ozone microbubbles with a diameter of 100-150nm are injected into the NaOH solution at a nitrogen pressure of 0.55MPa at an injection rate of 0.4L / min, after the immersion is completed, the immersion pressure is increased to 1.2MPa, and the temperature is heated to 93°C by microwave at 725W, after heating is completed, the temperature is maintained and the pressure is released to normal pressure, and the immersion is continued for 8min, then the temperature is maintained and the immersion is continued for 10-15min, then the A-type sludge powder is dried, and the dried A-type sludge powder is mixed with carbide slag at 53°C for 33min to obtain an A-type mixture;

[0077] The B-type sludge powder is subjected to plasma treatment at a power of 150W for 18min, it can be understood that the plasma treatment is in an air environment, and then the B-type sludge powder after plasma treatment is mixed with phosphogypsum at 25°C for 28min to obtain a B-type mixture;

[0078] The A-type mixture and the B-type mixture are added to a microchannel reactor for high shear mixing, the pressure is 1.5MPa, the temperature is 53°C, the shear rate is 900s -1 , the time is 18s, the cycle is 2 times, and the mixing is completed.

[0079] Example 22: The difference between this example and Example 21 is that the Class A sludge powder is immersed in a 3% mass fraction NaOH solution at a solid-liquid ratio of 1 g:6 mL.

[0080] Example 23: The difference between this example and Example 21 is that the Class A sludge powder is immersed in a 5% mass fraction NaOH solution at a solid-liquid ratio of 1 g:4 mL.

[0081] Example 24: The difference between this example and Example 21 is that the preliminary immersion is 10 min, after the immersion is completed, the immersion pressure is increased to 1 MPa, and heated to 90°C with a 700 W microwave, after heating is completed, continue to immerse for 5 min, then keep the temperature unchanged, depressurize to normal pressure, stir for 10 min and then dry.

[0082] Example 25: The difference between this example and Example 21 is that the preliminary immersion is 15 min, after the immersion is completed, the immersion pressure is increased to 1.5 MPa, and heated to 95°C with a 750 W microwave, after heating is completed, continue to immerse for 10 min, then keep the temperature unchanged, depressurize to normal pressure, stir for 15 min and then dry.

[0083] Example 26: The difference between this example and Example 21 is that the dried Class A sludge powder and carbide slag are stirred and mixed at 50°C for 30 min to obtain a Class A mixture.

[0084] Example 27: The difference between this example and Example 21 is that the dried Class A sludge powder and carbide slag are stirred and mixed at 55°C for 35 min to obtain a Class A mixture.

[0085] Example 28: The difference between this example and Example 21 is that the Class B sludge powder is plasma treated at a power of 100 W for 15 min, then the plasma treated Class B sludge powder and phosphogypsum are stirred and mixed for 25 min to obtain a Class B mixture.

[0086] Example 29: The difference between this example and Example 21 is that the Class B sludge powder is plasma treated at a power of 200 W for 20 min, then the plasma treated Class B sludge powder and phosphogypsum are stirred and mixed for 30 min to obtain a Class B mixture.

[0087] Example 30: The difference between this example and Example 21 is that the Class A mixture and the Class B mixture are added to a microchannel reactor for high shear mixing, the pressure is 1 MPa, the temperature is 50°C, the shear rate is 800 s -1 , the time is 15 s, the cycle is 2 times, and the mixing is completed.

[0088] Example 31: The difference between this example and example 21 is that the A mixture and the B mixture are added into the micro-channel reactor for high shear mixing, the pressure is 2 MPa, the temperature is 55℃, the shear rate is 1000 s -1 , the time is 20 s, and the mixing is completed after 3 cycles.

[0089] Example 32: The difference between this example and example 21 is that during the preliminary impregnation, ozone microbubbles with a diameter of 150-200 nm are injected into the NaOH solution under a nitrogen pressure of 0.5 MPa at an injection rate of 0.3 L / min.

[0090] Example 33: The difference between this example and example 21 is that during the preliminary impregnation, ozone microbubbles with a diameter of 50-100 nm are injected into the NaOH solution under a nitrogen pressure of 0.6 MPa at an injection rate of 0.6 L / min.

[0091] Example 34: The difference between this example and example 1 is that the mixing method is as follows:

[0092] First, the sludge powder is separated to obtain A sludge powder with a particle size of ≤80 μm and B sludge powder with a particle size of >80 μm;

[0093] The A sludge powder is impregnated in a NaOH solution with a mass fraction of 4% at a solid-liquid ratio of 1 g:5 mL, the preliminary impregnation is performed for 13 min, during the preliminary impregnation, ozone microbubbles with a diameter of 100-150 nm are injected into the NaOH solution under a nitrogen pressure of 0.55 MPa at an injection rate of 0.4 L / min, after the impregnation is completed, the impregnation pressure is increased to 1.2 MPa, and the temperature is heated to 93℃ by microwave with a power of 725 W, after the heating is completed, the impregnation is continued for 8 min, the temperature is maintained, the pressure is released to normal pressure, the impregnation is stirred for 10-15 min, and then the A sludge powder is dried, the dried A sludge powder and the carbide slag are stirred and mixed at 53℃ for 33 min to obtain an A mixture;

[0094] The B sludge powder is treated by plasma at a power of 150 W for 18 min, it can be understood that the plasma treatment is in an air environment, and then the B sludge powder after the plasma treatment and the phosphogypsum are stirred and mixed at 25℃ for 28 min to obtain a B mixture;

[0095] The A mixture and the B mixture are added into the micro-channel reactor for high shear mixing, the pressure is 1.5 MPa, the temperature is 53℃, the shear rate is 900 s -1 , the time is 18 s, and the mixing is completed after 2 cycles.

[0096] Experimental example: The description of this experimental example is based on the description in example 2, and is intended to illustrate the actual application effect of the present application.

[0097] The active mixed materials obtained in the various embodiments of this application were replaced by 30% and the water-cement ratio was 0.4. 40mm×40mm×40mm active mixed material-cement paste samples were prepared using the National Standard for Cement Mortar Strength (GB / T 17671-2021). The prepared samples were placed in a SHBY-40B type cement constant temperature and humidity standard curing chamber (temperature 20±2℃, relative humidity 95%) produced by Suzhou Donghua Test Instrument Co., Ltd. for curing for 24±2 hours before demolding. The demolded cement paste samples continued to be cured in the cement constant temperature and humidity standard curing chamber for 3 days and 28 days. After curing, the active mixed material-cement paste was obtained.

[0098] The compressive strength of the reactive admixture-cement paste samples at 3d and 28d was tested using a DY-208JX integrated flexural and compressive strength tester manufactured by Jinan Xinguang Testing Machine Manufacturing Co., Ltd., and the compressive strength results of the reactive admixture-cement paste samples at 3d and 28d for each embodiment were obtained.

[0099] Table 1. Compressive strength, cost, and carbon emissions of the reactive admixture-cement paste samples from Examples 1 and 2.

[0100] Group 3d compressive strength 28d compressive strength Cost Carbon emission Example 1 33.07 MPa 52.79 MPa 62.32 yuan / t 48.92 kg CO2e / t

[0101] As shown in Table 1, the strength of the active blended material-cement paste obtained in this application is close to 85% of that of pure cement paste, achieving good utilization of solid waste in building materials. Furthermore, the cost and carbon emissions of the active blended material-cement paste prepared in this application are significantly lower than those of P.O42.5 grade ordinary Portland cement. If it replaces 30% of cement, the cement cost will decrease by 44.54%, and carbon emissions will decrease by 29.34%. This system not only reduces costs but also effectively absorbs solid wastes such as CSG, PG, and sludge, and significantly reduces the carbon emission load of the building materials industry.

[0102] 1. Investigate the effects of the composition ratio of raw materials and preparation methods on the compressive strength of active admixture-cement paste samples at 3d and 28d.

[0103] The difference between Comparative Example 1 and Example 1 is that the temperature was raised at a constant rate throughout the calcination process;

[0104] Depend on Figure 1 The results show that the lack of stepped calcination in Control Example 1 easily leads to the inertization of active components and the residue of impurities. Therefore, the compressive strength of the calcined sludge-cement paste samples in Control Example 1 decreased at 3 days and 28 days compared with those in Examples 1 to 9.

[0105] From comparative example 1 to example 9, it can be seen that too small or too large proportion of sludge powder, too small or too large preparation parameter of sludge powder, too small or too large ball milling time of phosphogypsum, too small or too large proportion of ball milling time of carbide slag, and too low or too high calcination rate can all reduce the 3d and 28d compressive strength of the active admixture-cement neat paste sample, and therefore, from the comprehensive perspective, the parameter effect of example 1 is relatively more optimal.

[0106] 2. Explore the influence of the activation and modification treatment of phosphogypsum on the 3d and 28d compressive strength of the active admixture-cement neat paste sample.

[0107] Comparative example 2 differs from example 10 in that only the modified powder is used to activate and modify the phosphogypsum.

[0108] Comparative example 3 differs from example 10 in that only the modified gel is used to activate and modify the phosphogypsum.

[0109] Comparative example 4 differs from example 10 in that the modified gel is first used to pre-modify the phosphogypsum, and then the modified powder is used to modify the phosphogypsum.

[0110] From comparative example 1 to example 9, Figure 2 It can be seen from the results that comparative example 2 has the problems of silicon source loss, internal modification sufficiency but external coating deficiency, SO42- easy volatilization during high-temperature calcination, and poor α-C2S stability effect; comparative example 3 has the problems of internal penetration deficiency, surface modification sufficiency but internal activity, incomplete decomposition of quartz and muscovite, and small amount of amorphous silica and alumina generated; and comparative example 4 has the problems of high solvent difficult to disperse in the early stage due to the gel first and then powder, and powder difficult to penetrate and easy to agglomerate in the later stage; therefore, the 3d and 28d compressive strength of the active admixture-cement neat paste sample of comparative example 2 to comparative example 4 all show a downward trend compared with example 10 to example 20.

[0111] From comparative example 1 to example 10 to example 20, it can be seen that the activated and modified phosphogypsum can promote the decomposition of quartz in the sludge and improve the early strength of the calcined sludge, and therefore, example 10 to example 20 significantly improve the 3d and 28d compressive strength of the calcined sludge-cement neat paste sample compared with example 1.

[0112] From comparative example 10 to example 20, it can be seen that too small or too large preparation parameter of the modified sol, too small or too large preparation parameter of the modified powder, too small or too large preparation parameter of the pre-modified phosphogypsum, too small or too large preparation parameter of the modified gel, and too small or too large parameter of the modified gel modified phosphogypsum can all reduce the 3d and 28d compressive strength of the active admixture-cement neat paste sample, and therefore, from the comprehensive perspective, the parameter effect of example 10 is relatively more optimal.

[0113] 3. Investigate the effect of raw material mixing method on the compressive strength of active admixture-cement paste samples at 3d and 28d.

[0114] The difference between Comparative Example 5 and Example 21 is that ozone microbubbles were not injected during the initial impregnation.

[0115] The difference between Comparative Example 6 and Example 21 is that the pressure and temperature remained constant throughout the impregnation process;

[0116] The difference between Comparative Example 7 and Example 21 is that the B-type sludge powder is not subjected to plasma treatment;

[0117] Depend on Figure 3 The results show that the lack of ozone microbubbles in Control Example 5 reduced the silica-alumina dissolution rate; the lack of pressure and temperature regulation in Control Example 6 resulted in the blockage of CSH gel formation if low pressure was maintained, and the formation of inert clumps when high pressure was maintained, making it easier to form when mixed with carbide slag; the lack of plasma treatment in Control Example 7 reduced the interfacial bonding strength with phosphogypsum, making it easier for phosphogypsum to accumulate during subsequent shearing; therefore, the compressive strength of the active mixed material-cement paste samples of Control Examples 5 to 7 at 3 days and 28 days all showed a downward trend compared with Examples 24 to 36.

[0118] Comparing Examples 10 and 21-33, it can be seen that by processing the sludge powder according to particle size, then mixing it separately with carbide slag and phosphogypsum, and finally performing high-speed shear mixing, the gelling performance of the calcined sludge is significantly improved compared to Example 2. Therefore, the compressive strength of the active mixed material-cement paste samples in Examples 24-36 is significantly improved at 3 days and 28 days compared to Example 2.

[0119] Comparing Examples 1 and 34, it can be seen that the combination of unmodified phosphogypsum powder and particle size separation mixing method significantly improves the compressive strength of the active mixture-cement paste sample at 3d and 28d compared to Example 1. However, the effect is relatively weaker compared to the parameters of Examples 21 to 33. Therefore, the combination of activated modified phosphogypsum and particle size separation mixing method is more effective.

[0120] Comparing Examples 21 to 33, it can be seen that parameters that are too small or too large for the impregnation solid-liquid ratio, the overall impregnation parameters, the preparation parameters of type A mixture, type B mixture, and overall mixing parameters will all reduce the compressive strength of the calcined sludge-cement paste samples at 3 days and 28 days. Therefore, from a comprehensive perspective, the parameters of Example 21 are relatively better.

Claims

1. A method for producing an active blended material from a high temperature incinerated sludge-based solid waste, characterized by, The method comprises the following steps: S1, raw material mixing: 14-16% carbide slag powder, 2-3% phosphogypsum powder, and the rest of the sludge powder are mixed in a mass percentage ratio for 15-20 min to obtain a mixed sludge; S2, high-temperature calcination: The mixed sludge obtained in S1 is calcined by the following method: first, the temperature is raised to 780-785°C at a rate of 6-8°C / min, then the temperature is raised to 880-885°C at a rate of 2-4°C / min, and the temperature is maintained for 25-35 min, and then the calcined product is taken out after natural cooling in the furnace to room temperature to obtain an active mixed material.

2. A method of producing an active blended material from a high temperature incinerated sewage sludge-based solid waste as claimed in claim 1, wherein, The preparation method of the sludge powder is as follows: the sludge is dewatered and dried to a water content of 60-80%, then air-dried for 3 days, then hot-dried at 100-110°C to a constant weight, and then ball-milled for 14-16 min to obtain a sludge powder with a particle size of 4-150μm.

3. A method of producing an active blended material from a high temperature incinerated sewage sludge-based solid waste as claimed in claim 1, wherein, The preparation method of the carbide slag powder is as follows: the carbide slag is ball-milled for 14-16 min to obtain a carbide slag powder.

4. A method of producing an active blended material from a high temperature incinerated sewage sludge-based solid waste as claimed in claim 1, wherein, The preparation method of the phosphogypsum powder is as follows: the phosphogypsum is ball-milled for 14-16 min to obtain a phosphogypsum powder.

5. A method of producing an active blended material from a high temperature incinerated sewage sludge-based solid waste as claimed in claim 4, wherein, The phosphogypsum powder is subjected to an activation and modification treatment by the following method: The silicon sol with a solid content of 50-55% is magnetically stirred with polyvinylpyrrolidone accounting for 0.4-0.45wt% of the silicon sol for 1-1.5h, then the pH is adjusted to 6.0-6.5 with 0.1-0.2mol / L acetic acid, and the mixture is stirred in a constant-temperature water bath at 35-36°C for 1.5-2h to obtain a modified sol; the modified sol is freeze-dried, then ball-milled for 25-30min and sieved through a 200-mesh sieve to obtain a modified powder; the phosphogypsum powder and the modified powder are mixed in a mass ratio of 26-28:1 at 48-50°C for 25-30min to obtain a pre-modified phosphogypsum; The silicon sol with a solid content of 35-45% is magnetically stirred with polyethylene glycol accounting for 0.5-0.6wt% of the silicon sol for 1-1.5h, then 1-2wt% of a silane coupling agent is added, the pH is adjusted to 6.5-7 with 0.1-0.2mol / L citric acid, and the mixture is stirred in a constant-temperature water bath at 38-40°C for 4-4.5h to obtain a modified gel; the modified gel is washed with deionized water, then mixed with the pre-modified phosphogypsum in a mass ratio of 1:18-20 at 45-50°C for 30-40min, and then dried by blowing air and crushed through a 100-mesh sieve to obtain an activated and modified phosphogypsum, and the activation and modification treatment is completed.

6. A method of producing an active blended material from a high temperature incinerated sewage sludge-based solid waste as claimed in claim 1, wherein, The parameters of the freeze-drying include a temperature of -50 to -40°C and a time of 7-7.5h.

7. A method of producing an active blended material from a high temperature incinerated sewage sludge based solid waste as claimed in claim 5, wherein, The parameters of the air-drying include a temperature of 80-85°C and a time of 3-3.5h.

8. A method of preparing a multi-solid waste composite for use in high temperature incineration of sludge as claimed in claim 1, wherein, In S1, the mixing method is as follows: First, the sludge powder is separated to obtain A-type sludge powder with a particle size of ≤80μm and B-type sludge powder with other particle sizes; The A-class sludge powder is dipped in a 3-5% NaOH solution at a solid-liquid ratio of 1g:4-6mL, and is preliminarily dipped for 10-15min; after the dipping is completed, the dipping pressure is increased to 1-1.5MPa, and the dipping is heated to 90-95°C by microwave at 700-750W; after the heating is completed, the dipping is continued for 5-10min, the temperature is kept unchanged, the pressure is released to normal pressure, the dipping is stirred for 10-15min, and then drying is performed; the dried A-class sludge powder and the carbide slag powder are stirred and mixed at 50-55°C for 30-35min to obtain an A-class mixture; The B-class sludge powder is treated by plasma at a power of 100-200W for 15-20min, and then the B-class sludge powder after the plasma treatment and the phosphogypsum powder are stirred and mixed for 25-30min to obtain a B-class mixture; The A-type mixture and the B-type mixture are added into the micro-channel reactor for high shear mixing, the pressure is 1-2 MPa, the temperature is 50-55℃, the shear rate is 800-1000 s -1 , the time is 15-20 s, the cycle is 2-3 times, and the mixing is completed.

9. A method of preparing a multi-solid waste composite according to claim 8, wherein During the preliminary dipping, ozone microbubbles with a diameter of 50-200nm are injected into the NaOH solution at a nitrogen pressure of 0.5-0.6MPa, and the injection rate is 0.3-0.6L / min.

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