CN115520887A - Novel method for fixing carbon dioxide by construction waste - Google Patents
Novel method for fixing carbon dioxide by construction waste Download PDFInfo
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- CN115520887A CN115520887A CN202211092080.9A CN202211092080A CN115520887A CN 115520887 A CN115520887 A CN 115520887A CN 202211092080 A CN202211092080 A CN 202211092080A CN 115520887 A CN115520887 A CN 115520887A
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- waste
- carbon dioxide
- carbonation
- fixing carbon
- calcium carbonate
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F11/00—Compounds of calcium, strontium, or barium
- C01F11/18—Carbonates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
- C01F5/00—Compounds of magnesium
- C01F5/24—Magnesium carbonates
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Inorganic Chemistry (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
Abstract
The invention discloses a novel method for fixing carbon dioxide by construction wastes, which is technically characterized in that waste concrete is crushed, cleaned and graded, coarse aggregate in the waste concrete is recovered, waste cement particles with the mass as high as 1/3 (by mass) can be generated in the process of recovering recycled aggregate, and the waste cement particles are used as raw materials and CO compressed by a compressor 2 Performing carbonation treatment chemical reaction in a container filled with appropriate amount of magnetized water to generate calcium-rich hydrate, and curing in a curing tank to obtain stable CaCO 3 The calcium carbonate is nontoxic and harmless, can be used as a raw material for producing cement, can also be used for other industrial purposes, and utilizes solid waste to carbonate CO 2 And toxic heavy metals can be fixed, and noble metals can be recovered, so that the method has good economic benefit.
Description
Technical Field
The invention belongs to the technical field of double carbon, and particularly relates to a novel method for fixing carbon dioxide by construction waste.
Background
So far, most of the energy sources of all countries in the world are still fossil fuels, and as the energy source demand of all countries continuously increases, especially in the process of industrialization of developing countries, the fossil fuels will continue to dominate in the next decades. If no effective emission reduction measures are taken, CO in air in 2030 2 The content of the carbon dioxide is 40-110% higher than that in 2000, and the carbon dioxide in the air is CO in 2100 years 2 The content of the active ingredients in the soil can reach 540-970ppm, and the global average temperature rises by 1.8-4 ℃, so that the sea level rises, glacier shrinks, frozen soil meltsAnd the like. This will cause serious harm to the climate and environment, human health, human living environment, ecological balance and even biodiversity. CO2 2 The trapping and sequestration (CCS) technology is used for coping with global climate change and reducing CO generated by using fossil energy 2 And appeared to be considered one of the most potential emission reduction technologies.
CO for developing safe, efficient, economic and environment-friendly concept 2 Capture and Containment (CCS) technology is becoming the focus of current research. Patent CN1721043A reports a method for preparing a bulk material for cultivating marine algae and aquatic organisms by steel slag sinking in water, the bulk material consisting of: a) Preparing a mixture of granular slag produced during steel production; and b) carbonating the mixture to form carbonate, and using the carbonate as a binder to form the mixture into a block. However, generally, the safe, efficient, green and environment-friendly method for fixing carbon dioxide is less, and the novel method for fixing carbon dioxide by using construction waste is developed aiming at the situations.
Disclosure of Invention
The invention develops a novel method for fixing carbon dioxide by using construction waste aiming at the situation.
The invention is realized by adopting the following technical scheme.
The invention discloses a novel method for fixing carbon dioxide by construction waste, which is summarized as follows as shown in figure 1: CO2 2 Dissolution → ionization of calcium, magnesium and other ions in the construction waste → precipitation of calcium carbonate or magnesium carbonate. It is essentially CO 2 Dissolving in water to form carbonic acid, and gradually dissolving the construction waste under the action of the carbonic acid to form carbonate. The chemical reaction formula can be expressed as:
Co 2 +H 2 O→H 2 CO 3 →H + +HCO 3 - →2H + +CO 3 2- (1)
Mg 2 SiO 4 +4H + →2Mg 2+ +SiO 2 +H 2 O (2)
Mg 2+ +CO 3 2- →MgCO 3 (3)
the method has the characteristics of convenience and simplicity, but a silicon-rich passivation layer is formed on the surface of the mineral in the carbonation process, the further progress of the carbonation reaction is prevented, and the reaction rate is slow. Increasing the carbonation rate by increasing the temperature or increasing the pressure, temperature increasing the CO 2 The dissolution of (2) is accelerated and the solubility of calcium carbonate and magnesium carbonate is reduced, thereby facilitating the carbonation reaction.
The invention has the beneficial effects that: the carbonation of the construction waste can treat the greenhouse gas with potential, and the generated calcium carbonate is nontoxic and harmless, can be used as a raw material for producing cement, and can also be used for other industrial purposes. Carbonation of CO from solid waste 2 And toxic heavy metals can be fixed, and precious metals can be recovered, so that the method has good economic benefit and is an innovative method for fixing carbon dioxide by using construction wastes.
Drawings
Fig. 1 is a flow chart of a method for fixing carbon dioxide by using novel construction waste, fig. 2 is a flow chart of a method for fixing carbon dioxide by using novel construction waste, fig. 3 is a micro-morphology of different types of calcium carbonate, (a) amorphous calcium carbonate ACC; (b) low magnesium calcite (Mg = 6%); (c) high magnesium calcite (Mg = 20%); (d) aragonite; (e) monohydrocalcite; (f) vaterite. FIG. 4 (a) shows the FE-SEM photograph and the particle size of calcium carbonate in 72h steel slag after carbonation, and (b) shows the particle size of calcium carbonate. FIG. 5 is dicalcium silicate beta-C 2 FE-SEM pictures (morphology and size change pictures) of calcite generated by the S carbonation process.
Detailed Description
The technical solution of the present invention is clearly and completely described below with reference to the specific embodiments.
EXAMPLE 1 carbonation treatment of construction waste
The waste concrete is crushed, cleaned and graded, the coarse aggregate in the waste concrete is recovered, waste cement particles up to 1/3 (by mass) are generated in the process of recovering the recycled aggregate, and most of the waste cement is used as a roadbed materialWhen the waste cement particles are not effectively utilized, the invention takes the waste cement particles as raw materials and CO compressed by a compressor 2 Performing carbonation treatment chemical reaction in a container filled with appropriate amount of magnetized water to generate calcium-rich hydrate, and curing in a curing tank to obtain stable CaCO 3 The calcium carbonate is nontoxic and harmless and can be used as a raw material for producing cement, and the whole process is shown in figure 2.
The waste cement is solid waste (cement hydration products such as calcium hydroxide, hydrated calcium silicate and hydrated calcium aluminate) with high calcium content, and is easy to carbonate to form more stable calcium carbonate.
Carbonation of waste Cement for CO 2 The chemical reaction formula is as follows:
Ca(OH) 2 +CO 2 (g)→CaCO 3 (4)
xCaO·SiO 2 ·nH 2 O+CO 2 (g)→xCaCO 3 +Si O 2+nH 2 O (5)
Ca 6 Al 2 O 6 (SO 4 ) 3 ·32H 2 O+3CO 2 →3CaCO 3 +3CaSO 4 ·2H 2 O+Al 2 O 3 ·3H 2 O+23H 2 O (6)
EXAMPLE 2 carbonation of Steel slag, a waste of construction
In the embodiment, carbon dioxide is sealed and stored by carbonating steel slag and fixing CO by direct wet method 2 Realizing 130-330g of CO fixed by per kilogram of steel slag 2 The chemical reaction formula can be expressed by the expressions (1), (2) and (3), and the method for fixing carbon dioxide is shown in FIG. 1. With dicalcium silicate beta-C 2 S and tricalcium silicate C 3 The carbonation of the S-based silicate phase is a major source of strength in carbonated steel slag products, which benefits from the microstructure modification by calcium carbonate growth. beta-C 2 S and C 3 Calcium carbonate has similar growth rule in S carbonation process, and can generate calcite with good crystallization and single crystal structure. The rhombohedral blocky calcite is converted from amorphous calcium carbonate at the initial stage of reaction, and the spherical nano particles covered on the surface of the rhombohedral blocky calcite increase the specific surface area of the particles so as to promote the further precipitation of calcium carbonate,and simultaneously, the crystal nucleus function is realized, and the subsequent hydration of the minerals is promoted. In the stable stage of the reaction, heat release is not obvious, but the size of calcite particles is rapidly increased, the calcite particles are tightly stacked, an obvious mechanical occlusion phenomenon is presented, a powerful crystalline phase cementation effect is generated, a compact calcium carbonate framework is formed, and the strength of the matrix is obviously improved. Dicalcium silicate beta-C 2 S carbonation is accompanied by an increase in the grain size of calcite (from 50nm to 107 nm), an increase in the particle size (from 64nm to 1800 nm) and an increase in the thermodynamic stability (from 698 ℃ to 810 ℃), with a final solidification strength of 127MPa. The micro-topography of the different types of calcium carbonate is shown in fig. 3. The FE-SEM morphology of calcite produced by the dicalcium silicate beta-C2S carbonation process is shown in figure 5.
The optimal liquid-solid ratio of the steel slag carbonation reaction is 0.12. The carbonation rate of the calcium-containing alkaline mineral in the steel slag is sequentially calcium hydroxide CH, dicalcium silicate beta-C2S and tetracalcium aluminoferrite C4AF from high to low. Compared with other minerals in the steel slag, the calcium hydroxide CH has highest carbonation reaction activity, and due to high solubility of the calcium hydroxide CH, the maximum carbonation degree of the steel slag powder reaches 56 percent, and the corresponding CO is 2 The holding power is 209.8g CO2/kg dry steel slag.
Along with the increase of the carbonation reaction degree, the pH value of the steel slag percolate is gradually reduced. The pH of the solution of the uncarbonated steel slag is controlled by calcium hydroxide CH. CaCO formed by carbonation 3 The consumption of the coating and alkaline minerals results in a decrease in pH after carbonation. During subsequent hydration due to CaCO 3 Partial dissolution of the coating and hydration of the remaining alkaline minerals results in a pH regain. The time for the pH of the solution to stabilize during the subsequent hydration is gradually increased as the degree of carbonation increases.
The Ca leaching amount of the steel slag is obviously reduced along with the increase of the carbonation reaction degree, but the Si leaching amount is increased. The change in leaching properties of the slag after carbonation is determined by its mineral composition. Ca leaching of uncarbonated steel slag is controlled by calcium hydroxide, CH. The Ca leaching amount of the steel slag after carbonation gradually approaches to saturated CaCO 3 And (3) solution. The Si leaching is mainly controlled by the silica gel Si-gel produced by carbonation.
Carbonic acidCaCO with poor crystallization is generated in the combined hydration and maintenance process 3 Micron-sized crystalline phase CaCO 3 And monocarbon type calcium hydrocarbonate aluminate
So that the microstructure of the test block is more compact. Carbonation contributes to the main strength of the test block. When the steel slag test block is carbonated for 24 hours, dicalcium silicate beta-C 2 S and tetracalcium aluminoferrite C4AF are respectively consumed by 51 percent and 14 percent, and the residual active minerals can be further subjected to hydration reaction. Subsequent hydration is hindered by carbonation, the higher the carbonation reaction degree is, the more remarkable the inhibition effect on the subsequent hydration rate is, however, subsequent hydration curing can still further promote the strength increase of the test block, and the microstructure of the steel slag after being carbonated for 72 hours is shown in fig. 4 (a).
The average grain size of calcite produced by the carbonation of steel slag is less than 80nm. The calcium carbonate coating layer can be dissolved and reprecipitated in the solution to be separated from the surface of the particles, and the decomposition temperature of the calcium carbonate is reduced due to the reduction of the particle size and the grain size of the calcium carbonate along with the transformation of the shape from a rhombohedral block to a sheet, the reduction of the decomposition temperature and the reduction of the grain size to 50 nm.
Carbonation solves the problems of low reaction activity and poor stability of the steel slag, and fixes the greenhouse gas CO 2 The pH value of the steel slag solution is reduced, the leaching of Si is increased, the leaching of partial harmful elements is reduced, and the compatibility of the steel slag and the environment is improved.
The embodiments described above are only a part of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Claims (5)
1. A novel method for fixing carbon dioxide by using construction wastes is technically characterized by comprising CO 2 Dissolution → ionization of calcium and magnesium ions in construction waste → precipitation of calcium carbonate or magnesium carbonate.
2. The method for fixing carbon dioxide by using novel construction wastes as claimed in claim 1, which is technically characterized in that waste concrete is crushed, cleaned and classified, then coarse aggregate is recovered, waste cement particles with the mass as high as 1/3 generated in the process of recovering recycled aggregate are used as raw materials, and CO compressed by a compressor is used as the raw materials 2 Carbonating in a container filled with magnetized water to generate calcium-rich hydrate, and solidifying in solidifying pool to obtain stable CaCO 3 The calcium carbonate is nontoxic and harmless and can be used as a raw material for producing cement.
3. The method for fixing carbon dioxide by using the novel construction waste as claimed in claim 1, wherein the carbonation rate is increased by increasing the temperature or increasing the pressure appropriately.
4. The method as claimed in claim 1, wherein the generated calcium carbonate can be used for other industrial purposes, and the construction waste is used for carbonation of CO 2 And some poisonous heavy metals can be fixed, and some precious metals can be recovered.
5. The method for fixing carbon dioxide by using novel construction waste as claimed in claim 1, wherein the technical characteristic is that direct wet carbonation is adopted to fix CO 2 Can realize that 130-330g of CO is fixed per kilogram of steel slag 2 。
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211092080.9A CN115520887A (en) | 2022-09-05 | 2022-09-05 | Novel method for fixing carbon dioxide by construction waste |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202211092080.9A CN115520887A (en) | 2022-09-05 | 2022-09-05 | Novel method for fixing carbon dioxide by construction waste |
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| Publication Number | Publication Date |
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| CN115520887A true CN115520887A (en) | 2022-12-27 |
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| CN202211092080.9A Withdrawn CN115520887A (en) | 2022-09-05 | 2022-09-05 | Novel method for fixing carbon dioxide by construction waste |
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- 2022-09-05 CN CN202211092080.9A patent/CN115520887A/en not_active Withdrawn
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Application publication date: 20221227 |