Method for preparing gradient low-carbon cementing material through cooperation of sludge incineration ash and industrial solid waste

Abstract

The invention discloses a method for preparing a gradient low-carbon cementing material from sludge incineration ash and industrial solid waste. The method comprises the following steps: mixing nitric acid with the sludge incineration ash to obtain a mixture; the mixture is filtered and separated into a leaching solution and ash residues; drying the ash at 60 DEG C until the water content is less than or equal to 1% to obtain dried ash Uniformly mixing 20-30% by weight of the dried ash, 25-35% by weight of mineral powder, 10-20% by weight of desulfurized gypsum, 20-30% by weight of cement and 1-5% by weight of a conditioning agent to obtain a common low-carbon cementing material; mixing the leachate with phosphoric acid to obtain a composite acid solution; and mixing the composite acid liquor with the low-grade low-carbon cementing material to prepare the high-performance low-carbon cementing material. The problem that the sludge ash is not suitable for preparing building material products due to high phosphorus content is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a method for preparing a hierarchical low-carbon cementitious material by synergistically using sludge incineration ash and industrial solid waste. BACKGROUND

[0002] With the acceleration of urbanization, the production of municipal sludge has increased dramatically. Traditional disposal methods such as landfill and composting can cause secondary pollution. Although incineration can significantly reduce the volume, it produces a large amount of incineration ash rich in heavy metals and phosphorus, which poses a challenge to its resource utilization. At present, sludge incineration ash has been generally classified as general industrial solid waste, and its use as building materials has reduced environmental risks. However, the long-term stability of heavy metals needs further solidification treatment. In addition, a large number of studies have shown that the high phosphorus content in sludge ash has a negative impact on the setting time and strength of building materials, which also limits the resource utilization of sludge ash. At the same time, the storage of industrial solid waste such as metallurgical slag and desulfurization gypsum generated by the steel and chemical industries is huge, and mainly relies on landfill or low-value utilization, which not only occupies land but also poses environmental risks.

[0003] Existing cementitious materials (such as ordinary Portland cement) production relies on limestone calcination, which has high carbon emissions. Research on low-carbon cementitious materials prepared from solid waste has mainly focused on single solid waste (such as slag or fly ash), and there is a lack of research on the synergistic activation of multiple solid wastes and the efficient utilization of sludge incineration ash. In addition, the further stabilization of heavy metals in sludge incineration ash, the negative impact of phosphorus on the setting time and strength of cementitious materials, the efficient extraction and reuse of phosphorus, and the synergistic activation of sludge incineration ash and other solid waste have not been systematically solved. Therefore, developing a method for preparing low-carbon cementitious materials from municipal sludge incineration ash and industrial solid waste can not only realize the high-value utilization of solid waste but also reduce the carbon footprint of cementitious materials, which has significant environmental and economic value. SUMMARY

[0004] To overcome the defects of the prior art, a method for preparing a hierarchical low-carbon cementitious material by synergistically using sludge incineration ash and industrial solid waste is provided to solve the problem of high phosphorus content in sludge ash, which is not suitable for preparing building materials.

[0005] To achieve the above-mentioned purpose, a method for preparing a hierarchical low-carbon cementitious material by synergistically using sludge incineration ash and industrial solid waste is provided, which comprises:

[0006] The method comprises the following steps:

[0007] Mixing nitric acid and sludge incineration ash to obtain a mixture;

[0008] Filtering and separating the mixture into a leaching solution and an ash residue;

[0009] Drying the ash residue at 60℃ to obtain a dried ash residue with a water content of ≤1%.

[0010] Mixing 20-30% of the dried ash, 25-35% of the mineral powder, 10-20% of the desulfurization gypsum, 20-30% of the cement and 1-5% of the adjusting agent to obtain the ordinary low-carbon cementitious material;

[0011] Mixing the leaching solution with phosphoric acid to obtain a composite acid solution;

[0012] Mixing the composite acid solution with the low-grade low-carbon cementitious material to obtain a high-performance low-carbon cementitious material.

[0013] Further, the desulfurization gypsum is a solid waste desulfurization gypsum of a power plant.

[0014] Further, the molar concentration of the nitric acid is 1 mol / L, and the liquid-solid volume-mass ratio of the nitric acid to the sludge incineration ash is 30 ml:1 g.

[0015] Further, the phosphoric acid is a 75% mass concentration phosphoric acid.

[0016] Further, the mass ratio of the leaching solution to the phosphoric acid is 3:1

[0017] Further, the mass ratio of the composite acid solution to the ordinary low-carbon cementitious material is 4:100.

[0018] Further, the adjusting agent is lignin fiber.

[0019] The sludge incineration ash cooperates with industrial solid waste to prepare a low-carbon cementitious material in the method, the sludge incineration ash is pretreated, the phosphorus component is fully extracted and reused, the industrial solid waste such as composite mineral powder and gypsum is formed into a low-carbon cementitious material, all components can be fully utilized, and high-value application of the sludge incineration ash is realized. DETAILED DESCRIPTION

[0020] The application will be further described in detail below with reference to the embodiments. It can be understood that the specific embodiments described herein are only used to explain the related application, and not to limit the application.

[0021] It should be noted that the embodiments in the application and the features in the embodiments can be combined with each other without conflict. The application will be described in detail below with reference to the embodiments.

[0022] The application provides a method for preparing a low-carbon cementitious material by sludge incineration ash cooperated with industrial solid waste, which comprises the following steps:

[0023] S1, mixing nitric acid and sludge incineration ash to obtain a mixture.

[0024] The molar concentration of nitric acid is 1 mol / L. The liquid-solid volume-mass ratio of nitric acid to sludge incineration ash is 30 ml:1 g.

[0025] S2, filter the mixture to separate into leaching liquid and ash residue.

[0026] First, the sludge incineration ash is pretreated. Specifically, the mixture is pretreated using an ultrasonic device.

[0027] The ultrasonic conditions are: ultrasonic water bath temperature 60°C, ultrasonic power 840w, and ultrasonic time 2h.

[0028] The mixture is filtered to separate into leaching liquid and ash residue.

[0029] S3, the ash residue is dried in a 60°C oven to obtain dried ash residue.

[0030] In this embodiment, the ash residue is dried at 60°C to obtain dried ash residue with a water content of ≤1%.

[0031] S3, 20-30% of the dried ash residue, 25-35% of the mineral powder, 10-20% of the desulfurization gypsum, 20-30% of the cement, and 1-5% of the adjusting agent are mixed uniformly to obtain a general type of low-carbon cementitious material.

[0032] The mineral powder is a conventional 95-grade mineral powder. The cement is a conventional 425 cement. The desulfurization gypsum is a solid waste from a power plant, in powder form, and the main component is calcium sulfate dihydrate.

[0033] The general type of low-carbon cementitious material is particularly suitable for use as a soil solidifying agent, and can solidify engineering spoil for roadbed and pavement subbase.

[0034] S4, the leaching liquid is mixed with phosphoric acid to obtain a composite acid solution.

[0035] The phosphoric acid has a mass concentration of 75%. The mass ratio of the leaching liquid to the phosphoric acid is 3:1.

[0036] S5, the composite acid solution is mixed with the low-grade low-carbon cementitious material to obtain a high-performance low-carbon cementitious material.

[0037] The mass ratio of the composite acid solution to the general type of low-carbon cementitious material is 4:100.

[0038] The composite acid solution and the general type of low-carbon cementitious material are mixed uniformly at a mass ratio of 4:100 to obtain an acid-activated high-performance low-carbon cementitious material.

[0039] The high-performance low-carbon cementitious material is particularly suitable for replacing cement to prepare corrosion-resistant mortar.

[0040] The sludge incineration ash cooperates with industrial solid waste to prepare a low-carbon cementing material of a ladder type according to the method of the present application, and ordinary low-carbon cementing materials and high-performance low-carbon cementing materials are prepared.

[0041] The method of the present application uses ultrasonic water bath to make the mixture more uniformly mixed and accelerate the reaction rate. The ultrasonic wave can accelerate the dissolution of the sludge incineration ash, promote the mixing efficiency with nitric acid, and the increase of the reaction temperature can also increase the reaction activity, activate the unactivated molecules, and the temperature, power and ultrasonic time can be slightly floated.

[0042] Although the phosphorus in the sludge incineration ash mainly exists in the form of inorganic phosphorus, there is still a small amount of organic phosphorus. The strong oxidizing property of nitric acid can convert the organic phosphorus into inorganic phosphate, further improving the phosphorus leaching rate. In addition, if the nitric acid is excessive, other impurity metal elements will be leached into the solution at the same time, which will adversely affect the purity of the leaching solution, so the concentration of nitric acid is preferably 1 mol / L.

[0043] The Ca-P, Al-P, Fe-P and other components contained in the sludge ash will react with H+ produced by the ionization of nitric acid to generate phosphoric acid, so the main components of the leaching solution are phosphoric acid, a small amount of residual nitric acid and Ca 2+ , Al 3+ , Fe 3+ .

[0044] The main components of the sludge incineration ash are SiO2 and Al2O3, P2O5, and a small amount of Fe2O3 and CaO. Phosphorus is a harmful substance that can affect the setting time and strength of the cementing material, and other components are beneficial to the cementing material. After treatment, the phosphorus content of the ash is significantly reduced, and the iron and aluminum contents are slightly reduced. The ordinary low-carbon cementing material is optimized by proportioning. The cement preferentially hydrates to generate hydrated calcium silicate and calcium hydroxide to stimulate the pozzolanic activity of the ash and the mineral powder. The hydrated calcium aluminate and the calcium sulfate in the desulfurization gypsum react to generate hydrated calcium aluminate, which further supplements the strength of the cementing body, continuously promotes the pozzolanic reaction in the later stage, densifies the pores, and further enhances the strength. At the same time, the reduction of phosphorus content makes the setting time of the ordinary low-carbon cementing material close to that of cement, and the early strength is improved.

[0045] The regulator in the ordinary low-carbon cementing material is lignin fiber. When the ordinary low-carbon cementing material is used as a soil solidifying agent, the lignin fiber can make the soil particles more closely combined, enhance the flexibility of the cementing material, further improve the strength of the solidified soil, and prevent the cracking of the reinforced soil. When used in mortar, the ordinary low-carbon cementing material is mainly used to adjust the flexibility of the mortar and improve the bending and tensile strengths.

[0046] The acid component in the leaching solution can be used as an activator, but due to insufficient concentration, 75% concentrated phosphoric acid needs to be added, and the activated ash, mineral powder and gypsum are mixed in a suitable ratio to depolymerize oligomeric silicon and aluminum, and phosphoric acid radicals and sulfuric acid radicals, and further condense to form phosphorus oxygen tetrahedron and sulfur oxygen tetrahedron, which are bonded with each other and with silicon oxygen tetrahedron and aluminum oxygen tetrahedron to form a three-dimensional network structure, thereby forming a geopolymer gel. The three-dimensional network structure has better heavy metal solidification capacity and corrosion resistance, and can also play a role in cement hydration products.

[0047] Meanwhile, the amount of the composite acid component needs to be controlled, because excessive phosphoric acid groups will destroy the charge balance of the polymer, resulting in instability of the three-dimensional network structure and macroscopic strength loss. Therefore, the reasonable amount of the composite acid component mixed with the ordinary low-carbon cementitious material is 4:100, and a high-performance low-carbon cementitious material with higher strength and better corrosion resistance can be formed.

[0048] The sludge incineration ash and industrial solid waste are mixed in a suitable ratio to form a low-carbon cementitious material, so that all components can be fully utilized, and high-value-added application of the sludge incineration ash is realized.

[0049] In order to further illustrate the method for preparing a low-carbon cementitious material from sludge incineration ash and industrial solid waste according to the present application, the following examples are provided for further illustration.

[0050] Example 1

[0051] The present example provides a method for preparing a low-carbon cementitious material from sludge incineration ash and industrial solid waste, which comprises the following steps:

[0052] First, the sludge incineration ash is pretreated, and the specific method is to mix 1 mol / L nitric acid with the sludge incineration ash, and the liquid-solid volume-to-mass ratio is 30 ml / 1 g.

[0053] The mixture is pretreated by using an ultrasonic device.

[0054] The ultrasonic conditions are: ultrasonic water bath temperature 60 DEG C, ultrasonic power 840 w, and ultrasonic time 2 h.

[0055] The mixture is filtered and separated into a leaching solution and ash.

[0056] The ash is dried in a 60 DEG C oven to obtain dried ash.

[0057] The dried ash, mineral powder, desulfurization gypsum, cement and lignin fiber are mixed in the following mass ratio to obtain an ordinary low-carbon cementitious material.

[0058] The mineral powder is a conventional 95-grade mineral powder. The cement is a conventional 425 cement. The desulfurization gypsum is a solid waste from a power plant, in powder form, and mainly composed of calcium sulfate dihydrate.

[0059] The phosphoric acid with a weight concentration of 75% is mixed with the leaching solution at a mass ratio of 1:3 to obtain a composite acid solution.

[0060] The composite acid solution is mixed with component B at a mass ratio of 4:100 to obtain an acid-activated high-performance low-carbon cementitious material.

[0061] Example 2

[0062] The present embodiment provides a method for preparing a hierarchical low-carbon cementitious material by co-processing sludge incineration ash and industrial solid waste, which comprises the following steps:

[0063] First, the sludge incineration ash is pretreated by mixing it with 1 mol / L nitric acid at a liquid-solid volume-to-mass ratio of 30 ml / 1 g.

[0064] The mixture is pretreated using an ultrasonic device.

[0065] The ultrasonic conditions are: ultrasonic water bath temperature 60°C, ultrasonic power 840 W, and ultrasonic time 2 h.

[0066] The mixture is filtered to separate the leaching solution and the ash residue.

[0067] The ash residue is dried in a 60°C oven to obtain dried ash residue.

[0068] The dried ash residue, mineral powder, desulfurization gypsum, cement, and lignin fiber are mixed at the following mass ratios to obtain a general low-carbon cementitious material: 25 parts of dried ash residue, 30 parts of mineral powder, 18 parts of desulfurization gypsum, 25 parts of cement, and 2 parts of lignin fiber.

[0069] The mineral powder is a conventional 95-grade mineral powder. The cement is a conventional 425 cement. The desulfurization gypsum is a solid waste from a power plant, in powder form, and mainly composed of calcium sulfate dihydrate.

[0070] The phosphoric acid with a weight concentration of 75% is mixed with the leaching solution at a mass ratio of 1:3 to obtain a composite acid solution.

[0071] The composite acid solution is mixed with component B at a mass ratio of 4:100 to obtain an acid-activated high-performance low-carbon cementitious material.

[0072] Example 3

[0073] The present embodiment provides a method for preparing a hierarchical low-carbon cementitious material by co-processing sludge incineration ash and industrial solid waste, which comprises the following steps:

[0074] First, the sludge incineration ash is pretreated by mixing it with 1 mol / L nitric acid at a liquid-solid volume-to-mass ratio of 30 ml / 1 g.

[0075] The mixture is pretreated by using an ultrasonic device.

[0076] Ultrasonic conditions: ultrasonic water bath temperature 60℃, ultrasonic power 840w, ultrasonic time 2h.

[0077] The mixture is separated by filtration into leaching liquid and ash residue.

[0078] The ash residue is dried in a 60℃ oven to obtain dried ash residue.

[0079] The dried ash residue, mineral powder, desulfurized gypsum and cement are mixed in the following mass ratio to obtain ordinary low-carbon cementitious material: 30 parts of dried ash residue, 30 parts of mineral powder, 17 parts of desulfurized gypsum, 20 parts of cement and 3 parts of lignin fiber.

[0080] The mineral powder is conventional 95-grade mineral powder. The cement is conventional 425 cement. The desulfurized gypsum is a solid waste from a power plant, in powder form, and the main component is calcium sulfate dihydrate.

[0081] Phosphoric acid with a weight concentration of 75% is selected and mixed with the leaching liquid in a mass ratio of 1:3 to obtain a composite acid solution.

[0082] The composite acid solution is mixed with component B in a mass ratio of 4:100 to obtain acid-activated high-performance low-carbon cementitious material.

[0083] The mass mixing ratio of engineering sludge 1 part to ordinary low-carbon cementitious material (Example 2) is 8% of the engineering sludge. According to the “Highway Engineering Inorganic Binder Stabilized Material Test Procedures” JTG 3441-2024, the best dry density is 1.84 g / cm 3 , the best water content is 14.2%, the static pressure forming diameter is 50mm and the height is 50mm. The average value of the 7-day non-measurement limit compressive strength of the test piece is 2MPa.

[0084] The high-performance low-carbon cementitious material obtained in Example 2 is taken, and the mass ratio of ordinary low-carbon cementitious material in the high-performance low-carbon cementitious material to standard sand is 1:3 according to the “Cement Mortar Strength Test Method (ISO)” GB / T 17671-2021. The composite acid component dosage is 4%, water is added 220g (excluding water content in the composite acid component), and the total water-cement ratio is controlled at 0.5. According to the “Cement Mortar Strength Test Method (ISO)” GB / T 17671-2021, the mortar fluidity is 180cm, the 3d average value of the flexural strength is 5.1MPa, the 3d average value of the compressive strength is 27.7MPa; the 28d average value of the flexural strength is 7.7MPa; and the 28d average value of the compressive strength is 54.2MPa.

[0085] The above description is only the preferred embodiment of the present application and the explanation of the technical principles. It should be understood by those skilled in the art that the scope of the protection of the present application is not limited to the technical solutions formed by the specific combinations of the above technical features. It should also cover other technical solutions formed by the combinations of the above technical features or their equivalent features without departing from the concept of the present application. For example, the technical solutions formed by the mutual replacement of the above features and the technical features with similar functions disclosed (but not limited to) in the present application.

Claims

1. A method for preparing a low-carbon cementing material with a cascade structure from sludge incineration ash and industrial solid waste, characterized in that, The method comprises the following steps: mixing nitric acid and sludge incineration ash to obtain a mixture; filtering and separating the mixture into leaching liquid and ash residue; drying the ash residue at 60 DEG C to obtain dried ash residue with water content less than or equal to 1%; mixing 20-30% of the dried ash residue, 25-35% of mineral powder, 10-20% of desulfurization gypsum, 20-30% of cement and 1-5% of adjusting agent in percentage by weight to obtain common low-carbon cementitious material; mixing the leaching liquid with phosphoric acid to obtain composite acid liquid; mixing the composite acid liquid with the low-grade low-carbon cementitious material to obtain high-performance low-carbon cementitious material.

2. The method according to claim 1, characterized in that, The desulfurization gypsum is solid waste desulfurization gypsum from power plants.

3. The method according to claim 1, characterized in that, The molar concentration of the nitric acid is 1 mol / L, and the liquid-solid volume-mass ratio of the nitric acid to the sludge incineration ash is 30 ml:1 g.

4. The method according to claim 1, characterized in that, The phosphoric acid is phosphoric acid with mass concentration of 75%.

5. The method according to claim 4, characterized in that, The mass ratio of the leaching liquid to the phosphoric acid is 3:

1.

6. The method according to claim 1, characterized in that, The mass ratio of the composite acid liquid to the common low-carbon cementitious material is 4:

100.

7. The method according to claim 1, characterized in that, The adjusting agent is lignin fiber.