A type of heavy ceramsite to replace offshore wind turbine rock dumping

Abstract

This invention relates to a heavy ceramsite, particularly a low-carbon, low-cost, sinter-free, moisture-free, high-density heavy ceramsite that can treat large quantities of various solid wastes and replace offshore wind power ballast. It comprises the following components: solid waste-based cementitious material, carbonized steel slag powder, and municipal sewage treatment sludge. The carbonized steel slag powder includes the following components: steel slag powder, water, EDTA-2Na, and tea saponin. By introducing EDTA-2Na and tea saponin, the carbon dioxide absorption capacity of the steel slag powder is extremely high, reaching 22%, resulting in a low-carbon and environmentally friendly product; the density of the heavy ceramsite can reach 2.95 g / cm³. 3 It is spherical and has a continuous gradation, which makes it more erosion resistant than natural stone. The raw materials are all solid waste materials that are difficult to process, and it can process a variety of solid wastes in large quantities. Because it does not require sintering, it is more low-carbon and environmentally friendly.

Description

Technical Field

[0001] This invention relates to a type of heavy ceramsite, particularly a low-carbon, low-cost, sinter-free and moisture-free heavy ceramsite that can process large quantities of various solid wastes and has a high density, making it a suitable alternative to offshore wind power riprap. Background Technology

[0002] Rockfill protection for offshore wind turbine foundations is a traditional method of erosion control. It involves mechanically or manually dumping natural stones such as boulders and pebbles into a designated area to form a protective structure. By appropriately combining stones of different particle sizes, a filtration effect can be achieved, preventing seabed sediment from escaping through the gaps between the stones and increasing the critical velocity for sediment transport, thus preventing erosion. Additionally, rockfill can increase the local roughness around the pile, reducing water flow velocity.

[0003] Its disadvantages are that, due to the unreasonable gradation of natural stones such as boulders and pebbles, continuous gradation cannot be achieved, the specific gravity is not high, they are easily lost, and secondary erosion is likely to occur, resulting in a large amount of maintenance. The mining and acquisition of natural stones such as boulders and pebbles will damage the environment and are not cheap, costing 100 to 130 yuan per ton. A slightly larger wind farm needs to dump tens of thousands of tons of stones, which is very costly.

[0004] As is well known, steel slag has a high density due to its iron content; the density of raw steel slag is 3.2–3.8, while the density of natural stones such as boulders and pebbles is 2.6, a significant difference. Furthermore, the steel industry generates substantial carbon emissions, making carbon reduction an urgent need. Steel slag has a high calcium content and high carbonization activity, allowing the use of carbon dioxide emitted by steel mills to carbonize steel slag powder. After absorbing carbon dioxide, the density of the steel slag powder further increases, and its stability is greatly enhanced.

[0005] The Encyclopedia of China records two effects: the double salt effect and the silicon tetracoordination isomorphism effect.

[0006] A double salt is a salt composed of one or more anions and / or one or more cations, meaning it contains at least three different ionic groups. Its key characteristic is that the combination of multiple ionic groups allows the electron orbitals within the system to reach the lowest possible energy level. The formation process is an exothermic process, involving a decrease in the system's energy state. Therefore, many active ions can be significantly reduced in solubility in water and thus fixed through the formation of double salts.

[0007] Common double salt minerals

[0008] ① Etium sulfide (AFt) – 3CaO·Al₂O₃·3CaSO₄·32H₂O, has a solubility product of 10 under alkaline conditions. -111.6 ,

[0009] ②Friedel's salt—a double-layered metal hydroxide, also known as Ca-Al hydrotalcite, 3CaO·Al₂O₃·CaCl·10H₂O, with a Ksp of 10 at room temperature. -27.1

[0010] ③C-SH (calcium silicate) gel xCaO·SiO2·yH2O

[0011] ④ Potassium ferric sulfate – KFe3(OH)6(SO4)2, solubility is 10. -93.21

[0012] ⑤ Boehmite – solubility 10 -94.75

[0013] Electret complex salts form needle-like crystals with nanometer diameters, thereby enhancing and toughening the hardened body.

[0014] During the depolymerization, migration, and repolymerization of silicon-oxygen tetrahedra, trivalent or pentavalent ions enter the silicon-oxygen tetrahedral network structure, forming tetrahedra with four oxygen coordination sites, which are connected to the silicon-oxygen tetrahedra at their vertices. Meanwhile, reactive monovalent or divalent cations or anions are captured and stabilized by balancing the charge in the interstitial spaces of the network.

[0015] Based on the above two effects, solid waste-based cementitious materials can be made by grinding slag, steel slag, and desulfurized gypsum.

[0016] Wastewater treatment plants are inherently energy-intensive industries. The past practice of simply dumping sludge has wasted a great deal of resources and land, and has also caused additional impacts on the ecological environment. Even from the perspective of carbon emissions, the necessity of sludge disposal exists, as sludge incineration technology is a high-energy-consuming, high-carbon-emission, and high-cost process.

[0017] In order to enable the large-scale disposal of solid wastes such as steel slag and sludge, and to reduce the cost of scour protection for offshore wind turbine pile foundations, it is necessary to prepare a low-carbon, low-cost, non-sintering and moisture-curing-free, high-density heavy ceramsite that can handle a variety of solid wastes in large quantities and replace offshore wind turbine scour protection. Summary of the Invention

[0018] The technical problem to be solved by this invention is: in order to overcome the shortcomings of the existing technology, to provide a heavy ceramsite that can replace offshore wind power rock dumping, and to use tea saponin and EDTA to further increase carbon dioxide absorption, thereby achieving the purpose of increasing the carbon dioxide absorption of steel slag powder, i.e., low carbon emissions.

[0019] The technical solution adopted in this invention is: a heavy ceramsite that replaces offshore wind turbine rock dumping, comprising the following components by weight percentage:

[0020] Solid waste-based cementitious materials 60%

[0021] 20% carbide steel slag powder

[0022] Sludge from municipal wastewater treatment accounts for 20%.

[0023] Furthermore, the solid waste-based cementitious material comprises the following components in weight percentage:

[0024] 60% slag particles

[0025] 28% steel slag particles

[0026] Desulfurized gypsum 12%.

[0027] When preparing solid waste-based cementitious materials, the following three types of solid waste slag particles, steel slag particles, and desulfurized gypsum are ground to a specific surface area of ​​420 μm using a vertical mill. 2 / g, then grind finely using a tube mill to a specific gravity of 580m. 2 / g, to prepare a solid waste-based cementitious material. The physical and mechanical properties of the obtained solid waste-based cementitious material are consistent with those of ordinary silicate 425 cement.

[0028] Furthermore, the carbide steel slag powder comprises the following components by weight percentage:

[0029]

[0030]

[0031] When preparing carbide steel slag powder, the steel slag powder is first ground to a specific surface area of ​​380 μm. 2 / g, then add calcium ion chelating agent EDTA-2Na and carbon dioxide absorbent tea saponin to increase carbon dioxide absorption, and then use flue gas discharged from the lime kiln of the steel plant to carbonize steel slag powder. The carbon dioxide concentration in the flue gas is 22% and the carbonization time is 8h.

[0032] Furthermore, both the slag particles and the steel slag particles are waste products generated from ironmaking in steel plants, and the steel slag particles are treated by a hot simmering process.

[0033] The desulfurized gypsum mentioned is power plant desulfurized gypsum with a moisture content of 18% and a chloride ion content of 3000 ppm. Power plant desulfurized gypsum normally used as building desulfurized gypsum powder requires a moisture content of less than 12% and a chloride ion content of less than 600 ppm. The desulfurized gypsum with extremely high chloride ion content in this application cannot be used for building desulfurized gypsum powder; it is pure waste and generally can only be landfilled, making it difficult to dispose of.

[0034] Furthermore, the water content of the municipal wastewater treatment sludge is 65%.

[0035] Furthermore, the specific surface area of ​​the slag particles, steel slag particles, and desulfurized gypsum is 580 m².2 / g.

[0036] Furthermore, the specific surface area of ​​the steel slag powder is 380 m². 2 / g, density is 3.43g / cm³ 3 .

[0037] Furthermore, the EDTA-2Na has the chemical formula C2. 10 H 14 N₂Na₂O₈ has a molecular weight of 336.206. EDTA-2Na has six coordinating atoms, forming a complex called a chelate. It has an extremely strong chelating ability for calcium, magnesium, and other metal ions.

[0038] EDTA-2Na has broad coordination properties and can form stable chelates with almost all metal ions. Therefore, it can be used to chelate a large number of calcium and magnesium ions, especially calcium ions, to increase the amount of calcium and magnesium ions in the carbonation reaction of steel slag and significantly increase the carbon dioxide absorption. Most of the EDTA-2Na chelates are charged, so they are soluble in water and react rapidly. Its aqueous solution is acidic, which is also very conducive to the carbonation reaction of steel slag and increases the carbon dioxide absorption.

[0039] Tea saponins are a type of glycoside compound extracted from tea plant seeds (tea seeds, tea leaves). They are a high-performance natural surfactant with a strong ability to absorb carbon dioxide.

[0040] Tea saponin itself has a strong ability to absorb carbon dioxide and can significantly reduce the surface tension of liquids. Within a concentration range of 0.001% to 1.0%, its surface tension decreases from 76 mN / m to 46 mN / m. At around 0.5%, its surface activity is almost unaffected within a water hardness range of 0 to 28.7. Simultaneously, it has a significant wetting effect on hydrophobic solid surfaces; at a concentration of 1%, its contact angle is <90 degrees, indicating good wetting performance. Therefore, it allows water to wet steel slag powder more quickly and deeply. Since the carbonation reaction of steel slag requires a certain amount of water, the surface tension reduction and wetting ability of tea saponin can significantly increase carbon dioxide absorption. Furthermore, the slightly acidic pH of the tea saponin solution is also highly conducive to the carbonation reaction of steel slag, further enhancing carbon dioxide absorption.

[0041] The present invention has the following advantages over the prior art:

[0042] 1. By introducing EDTA-2Na and tea saponin, the carbon dioxide absorption capacity of steel slag powder is extremely high, reaching 22%, and the resulting products are low-carbon and environmentally friendly.

[0043] 2. The density of heavy ceramsite can reach 2.95 g / cm³. 3Furthermore, it is spherical and has a continuous gradation, making it more resistant to erosion than natural stone;

[0044] 3. The raw materials are all difficult-to-treat solid waste materials, which can process a large amount of various solid wastes. Because it does not require sintering, it is more low-carbon and environmentally friendly. Detailed Implementation

[0045] The embodiments of the present invention are described in detail below. The embodiments are implemented based on the technical solution of the present invention, and detailed implementation methods and specific operation processes are given. However, the protection scope of the present invention is not limited to the following embodiments.

[0046] Example 1

[0047] Preparation of solid waste-based cementitious materials:

[0048] According to weight percentage, 60% slag particles, 28% steel slag particles, and 12% desulfurization gypsum were ground into a fine powder with a specific gravity of 420 μm using a vertical mill. 2 / g, then grind finely using a tube mill to a specific gravity of 580m. 2 / g, to obtain solid waste-based cementitious materials;

[0049] Preparation of carbide steel slag powder:

[0050] First, grind the steel slag powder to a specific surface area of ​​380 μm. 2 / g, 0.02% EDTA-2Na and 0.02% tea saponin were dissolved in 1.96% tap water according to weight percentage, and then mixed evenly with 98.00% steel slag powder. Then, flue gas with a carbon dioxide concentration of 22% discharged from the lime kiln of the steel plant was introduced into the carbonization kettle and carbonized for 8 hours to obtain carbonized steel slag powder.

[0051] Preparation of heavy ceramsite:

[0052] By weight percentage, 60% of carbide steel slag powder, 20% of solid waste-based cementitious material, and 20% of municipal sewage treatment sludge with a moisture content of 65% are mixed. Then, tap water, accounting for 10% of the total weight of the three components, is added and stirred evenly. The mixture is then continuously granulated using a disc granulator to produce spherical particles. Without sintering or moisture retention, after natural standing for 3 days, a high-quality heavy ceramsite is obtained, which can replace offshore wind turbine ballast.

[0053] The physical and mechanical properties of the obtained heavy ceramsite are as follows: continuous particle size distribution, barrel compressive strength of 3.6 MPa, and density of 2.88 g / cm³. 3 It is 10.77% higher than that of natural stone.

[0054] Example 2

[0055] The difference from Example 1 is as follows:

[0056] Preparation of carbide steel slag powder:

[0057] First, grind the steel slag powder to a specific surface area of ​​380m. 2 / g, 0.04% EDTA-2Na and 0.04% tea saponin were dissolved in 1.92% tap water according to weight percentage, and then mixed evenly with 98.00% steel slag powder. Then, flue gas with a carbon dioxide concentration of 22% discharged from the lime kiln of the steel plant was introduced into the carbonization kettle and carbonized for 8 hours to obtain carbonized steel slag powder.

[0058] The physical and mechanical properties of the obtained heavy ceramsite are as follows: continuous particle size distribution, barrel compressive strength of 3.8 MPa, and density of 2.93 g / cm³. 3 It is 12.69% higher than that of natural stone.

[0059] Example 3

[0060] The difference from Example 1 is as follows:

[0061] Preparation of carbide steel slag powder:

[0062] First, grind the steel slag powder to a specific surface area of ​​380m. 2 / g, 0.06% EDTA-2Na and 0.06% tea saponin were dissolved in 1.88% tap water according to weight percentage, and then mixed evenly with 98.00% steel slag powder. Then, flue gas with a carbon dioxide concentration of 22% discharged from the lime kiln of the steel plant was introduced into the carbonization kettle and carbonized for 8 hours to obtain carbonized steel slag powder.

[0063] The physical and mechanical properties of the obtained heavy ceramsite are as follows: continuous particle size distribution, barrel compressive strength of 4.0 MPa, and density of 2.94 g / cm³. 3 It is 13.08% higher than that of natural stone.

[0064] Example 4

[0065] The difference from Example 1 is as follows:

[0066] Preparation of carbide steel slag powder:

[0067] First, grind the steel slag powder to a specific surface area of ​​380m. 2 / g, 0.08% EDTA-2Na and 0.08% tea saponin were dissolved in 1.84% tap water according to weight percentage, and then mixed evenly with 98.00% steel slag powder. Then, flue gas with a carbon dioxide concentration of 22% discharged from the lime kiln of the steel plant was introduced into the carbonization kettle and carbonized for 8 hours to obtain carbonized steel slag powder.

[0068] The physical and mechanical properties of the obtained heavy ceramsite are as follows: continuous particle size distribution, barrel compressive strength of 4.1 MPa, and density of 2.95 g / cm³. 3 It is 13.46% higher than that of natural stone.

[0069] Comparative Example 1

[0070] The difference from Example 1 is as follows:

[0071] Preparation of carbide steel slag powder:

[0072] First, grind the steel slag powder to a specific surface area of ​​380 μm. 2 / g, mix 2.00% tap water and 98.00% steel slag powder evenly according to the weight percentage, and then introduce flue gas with a carbon dioxide concentration of 22% discharged from the lime kiln of the steel plant into the carbonization kettle, and carbonize for 8 hours to obtain carbonized steel slag powder.

[0073] The physical and mechanical properties of the obtained heavy ceramsite are as follows: continuous particle size distribution, barrel compressive strength of 3.1 MPa, and density greater than 2.72 g / cm³. 3 It is 4.62% higher than that of natural stone.

[0074] The properties of the steel carbide slag powder obtained in Examples 1-4 of this invention and the steel carbide slag powder obtained in Comparative Example 1 are shown in Table 1 below:

[0075] Table 1. Performance parameters of the steel carbide slag powder prepared in Examples 1-4 and Comparative Example 1

[0076]

[0077] As can be seen from the table above, it is obvious that the carbon dioxide absorption of the carbide steel slag powder prepared in Examples 1-4 is much higher than that of the comparative example. The highest absorption rate in Example 4 is 61.18% higher than that in Comparative Example 1, and the density is also much higher than that in Comparative Example 1, with the highest absorption rate in Example 4 being 7.71% higher than that in Comparative Example 1. The higher the carbon dioxide absorption rate, the lower the carbon content of the product.

[0078] The properties of the heavy ceramsite and natural stone obtained in Examples 1-4 of this invention are shown in Table 2 below:

[0079] Table 2 Performance parameters of the heavy ceramsite and natural stone obtained in Examples 1-4

[0080]

[0081] Although natural stone has higher strength, it does not need to be as strong in rock-laying protection projects. The most important thing is to have high density to prevent it from being washed away by ocean currents.

[0082] The raw material and production cost of solid waste-based cementitious materials is 100 yuan per ton, the raw material and production cost of carbonized steel slag powder is 90 yuan per ton, and the mixing and granulation cost of heavy ceramsite is 12 yuan per ton. In other words, the cost of producing one ton of high-quality heavy ceramsite to replace offshore wind power riprap is 82 yuan.

[0083] The profit from producing one ton of high-quality heavy ceramsite to replace offshore wind turbine rock dumping is as follows: sludge disposal revenue is 600 yuan per ton, the carbon price of carbon dioxide is 60 yuan per ton, and the ex-factory price of ceramsite is 10 yuan per ton. Therefore, the profit from producing one ton of high-quality heavy ceramsite to replace offshore wind turbine rock dumping is 55.2 yuan. With further increases in carbon prices, the economic benefits of the heavy ceramsite prepared by this invention will become increasingly higher.

[0084] As can be seen from the above data, the heavy ceramic particles prepared by this invention, which replace offshore wind turbine rock dumping, have a large carbon dioxide absorption capacity, can dispose of large quantities of difficult-to-treat solid waste, are low-carbon and environmentally friendly, have good physical and mechanical properties, are highly profitable, and have extremely significant economic and social benefits.

Claims

1. A type of heavy ceramsite that can replace offshore wind turbine rock dumping, characterized in that, Includes the following components by weight percentage: Solid waste-based cementitious materials 60% 20% carbide steel slag powder Municipal wastewater treatment sludge accounts for 20%; The solid waste-based cementitious material comprises the following components by weight percentage: 60% slag particles 28% steel slag particles Desulfurized gypsum 12%; The carbide steel slag powder comprises the following components by weight percentage: 98.00% steel slag powder Water content: 1.84%-1.96% EDTA-2Na 0.02%-0.08% Tea saponins: 0.02%-0.08%; Both the slag particles and steel slag particles mentioned above are waste products generated from ironmaking in steel plants. The steel slag particles are treated by a hot quenching process. The desulfurized gypsum mentioned is power plant desulfurized gypsum with a water content of 18% and a chloride ion content of 3000 ppm; The specific surface area of ​​the slag particles, steel slag particles and desulfurized gypsum is 580 m2 / g; The steel slag powder has a specific surface area of ​​380 m² / g and a density of 3.43 g / cm³. The EDTA-2Na has the chemical formula C10H14N2Na2O8 and a molecular weight of 336.

206. The water content of the municipal sewage treatment sludge is 65%.

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