Preparation method of high-doped phosphogypsum-based carbon sequestration cementing material

Abstract

The application discloses a preparation method of high-content phosphogypsum-based carbon fixation cementing material, and steps include: preparing an organic salt immersion solution, mixing a metal ion chelating agent, and then fully dissolving the mixture in water to obtain the organic salt immersion solution; fully reacting the organic salt immersion solution with phosphogypsum; adding the phosphogypsum slurry into ammonia water, and introducing CO2 gas for carbonization for a certain time; filtering to obtain a residue sample and supernatant, and then mixing the residue sample and supernatant with mineral powder and quicklime to prepare carbonized phosphogypsum-based cementing material. The application not only realizes fixation and storage of CO2 in the preparation process of the cementing material, but also improves the content of phosphogypsum in the phosphogypsum-based cementing material, which can be as high as 60% to 80%, reduces the residual amount of phosphogypsum which does not participate in the hydration reaction in the phosphogypsum-based cementing material, and improves the mechanical properties and durability of the high-content phosphogypsum-based carbon fixation cementing material by calcium carbonate obtained by carbonization of the phosphogypsum.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of building materials, and particularly relates to a preparation method of high-content phosphogypsum-based carbon fixation cementitious material. BACKGROUND

[0002] Utilizing phosphogypsum to prepare building materials is a reliable way to resource utilization of phosphogypsum at present, but in the preparation of green cementitious material using phosphogypsum, the phosphogypsum is often excessive, and the excessive phosphogypsum cannot completely participate in the reaction, and the residual phosphogypsum can only be wrapped in the cementitious material by the hydration product, which will lead to the reduction of cement strength and the loss of durability after long-term contact with water.

[0003] In order to ensure the durability of the cementitious material, the content of phosphogypsum is usually controlled, which is not conducive to the high resource utilization and large-scale application of phosphogypsum. In addition, other materials (such as cement, mineral admixtures and additives) are also added to improve the performance, which will consume more energy and resources compared to directly using excellent cementitious materials, and make the process more complex.

[0004] Currently, green cementitious material is prepared by using phosphogypsum, in which the excessive phosphogypsum cannot completely participate in the reaction, and the phosphogypsum that does not participate in the hydration reaction can only be wrapped by the hydration product, which will lead to the reduction of cement strength and the loss of durability after long-term contact with water. In order to ensure the durability, the content of phosphogypsum must be controlled.

[0005] Therefore, it is necessary to improve the large-content application of phosphogypsum in green cementitious material, realize the fixation and sequestration of CO2, improve the resource utilization efficiency of phosphogypsum and reduce the damage of CO2 in the ecological environment to the ecological environment. In the existing utilization and carbon fixation technology of phosphogypsum, most of the researches convert calcium sulfate in phosphogypsum into calcium carbonate, thereby realizing the consumption of phosphogypsum and the fixation of CO2, but it is difficult to prepare carbon fixation cementitious material by using phosphogypsum combined with carbon fixation technology.

[0006] The patent document with publication number CN118184184A discloses a low-carbon cementitious material with large-content steel slag and phosphogypsum and a preparation method thereof. The cementitious material is prepared by mixing a plurality of different industrial solid waste phosphogypsum, steel slag, slag and a small amount of additives. However, the technical problem of fixation and sequestration of CO2 cannot be solved. SUMMARY

[0007] To solve the above technical problems, the present application provides a preparation method of high-content phosphogypsum-based carbon fixation cementitious material.

[0008] The present application is realized by the following technical solutions.

[0009] The application provides a preparation method of high-content phosphogypsum-based carbon sequestration cementing material.

[0010] S1: preparing an organic salt leaching solution;

[0011] S2: uniformly mixing the organic salt leaching solution in the step S1 with phosphogypsum to obtain a phosphogypsum slurry;

[0012] S3: adding ammonia water to the phosphogypsum slurry obtained in the step S2, and introducing carbon oxide gas into the mixture of the phosphogypsum slurry and the ammonia water and stirring to obtain a carbonized phosphogypsum-based slurry;

[0013] S4: filtering the carbonized phosphogypsum-based slurry obtained in the step S3 to obtain a residue sample and supernatant, and mixing the residue sample and the supernatant with material A, and obtaining the high-content phosphogypsum-based carbon sequestration cementing material after mixing.

[0014] Preferably, one or more metal ion chelating agents are mixed to obtain the organic salt leaching solution in the step S1, and the metal ion chelating agent includes one or more of amino acid derivatives, hydroxy acids and organic polybasic phosphonic acids; CO2 gas is introduced into the supernatant and stirred for 4-6 min, and then the supernatant is left to stand at room temperature for a period of time to obtain the phosphogypsum slurry in the step S2.

[0015] Preferably, the components of the organic salt leaching solution prepared by the metal ion chelating agent include GA 80-83 parts, EDTA-4Na 8-10 parts, EDTMP 1-2 parts and 90-110 parts of water in terms of mass parts.

[0016] Preferably, the liquid-solid ratio of the phosphogypsum and the organic salt leaching solution is 3:1-25:1 in the step S2, and the phosphogypsum slurry is obtained after standing for >90 min after mixing.

[0017] Preferably, the concentration of the ammonia water is 25%, and the mass of the ammonia water is 10-40% of the dry mass of the phosphogypsum in the step S3.

[0018] Preferably, the carbon oxide gas is delivered at a pressure of 0.1-8 MPa, the stirring speed is >700 r / min, and the carbon oxide gas is introduced for not less than 150 min in the step S3.

[0019] Preferably, the pH value of the supernatant obtained after filtering the phosphogypsum slurry in the step S4 is not less than 7.

[0020] Preferably, the material A includes mineral powder and quicklime, and the high-content phosphogypsum-based carbon sequestration cementing material is prepared by mixing 450-800 parts of the residue sample, 300-500 parts of the supernatant, 180-450 parts of the mineral powder and 2-5 parts of the quicklime in terms of mass parts.

[0021] Preferably, the mineral powder includes granulated blast furnace slag powder of S95, S105 grade, and the specific surface area is not less than 400m 2 / kg.

[0022] Preferably, the quicklime calcium oxide content is not less than 95%.

[0023] The beneficial effects of the present application are:

[0024] 1. Compared with ordinary Portland cement, the present application reduces the process of “two grinding and one burning”, greatly reduces the consumption of energy and the emission of greenhouse gases. The present application can directly use the raw phosphogypsum without pretreatment, saves cost, improves the resource utilization efficiency of phosphogypsum, provides direction and guidance for the treatment and utilization of bulk solid waste phosphogypsum, and has good economic and social benefits.

[0025] 2. Compared with traditional green cementitious materials, the high-dosage phosphogypsum-based carbon sequestration cementitious material of the present application realizes the fixation and sequestration of CO2 while preparing the cementitious material, converts CO2 into inert carbonate substances in the high-dosage phosphogypsum-based carbon sequestration cementitious material, effectively fixes CO2, and is conducive to sustainable green development.

[0026] 3. Compared with existing phosphogypsum-based cementitious materials, the high-dosage phosphogypsum-based carbon sequestration cementitious material of the present application improves the dosage proportion of phosphogypsum in the cementitious material, reduces the residual amount of unreacted phosphogypsum in the phosphogypsum-based cementitious material, and uses calcium carbonate obtained by carbon sequestration technology as one of the hydration products, so that the cementitious material has better compressive strength and durability. The high-dosage phosphogypsum-based carbon sequestration cementitious material of the present application has short molding time, simple preparation method, green and environmentally friendly, and high resource utilization value. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is the process flow chart of the present application. DETAILED DESCRIPTION

[0028] The technical solutions of the present application are further described below, but the scope of protection is not limited to the description.

[0029] A preparation method of a high-dosage phosphogypsum-based carbon sequestration cementitious material, comprising the following steps:

[0030] S1: preparing an organic salt immersion solution;

[0031] S2: uniformly mixing the organic salt immersion solution in step S1 with phosphogypsum to obtain a phosphogypsum slurry;

[0032] S3: Ammonia water is added to the phosphogypsum slurry obtained in step S2, and carbon oxide gas is introduced into the mixture of the phosphogypsum slurry and the ammonia water and stirred to ensure that the reaction is fully carried out, so as to obtain a carbonated phosphogypsum-based slurry;

[0033] S4: The carbonated phosphogypsum-based slurry obtained in step S3 is filtered to obtain a residue and a supernatant, and the residue and the supernatant are mixed with the material A to obtain a high-content phosphogypsum-based carbon sequestration cementitious material after mixing.

[0034] In step S1, one or more metal ion chelating agents are mixed and dissolved in water to obtain an organic salt leaching solution, and the metal ion chelating agents include one or more of amino acid derivatives, hydroxy acids, and organic polybasic phosphonic acids; in step S2, CO2 gas is introduced into the supernatant and stirred for 4-6 min, and then left to stand at room temperature for a period of time to obtain a phosphogypsum slurry.

[0035] The components of the organic salt leaching solution prepared by the metal ion chelating agent are in mass parts, including GA 80-83 parts, EDTA-4Na 8-10 parts, EDTMP 1-2 parts, and 90-110 parts of water.

[0036] In step S2, the liquid-solid ratio of phosphogypsum to organic salt leaching solution is 3:1-25:1, and after mixing, the phosphogypsum slurry is obtained after standing for >90 min. If the liquid-solid ratio is too low, the leaching efficiency of calcium ions will be reduced, and if the liquid-solid ratio is too high, energy and resources will be wasted.

[0037] In step S3, the concentration of ammonia water is 25%, and the mass of ammonia water is 10-40% of the dry mass of phosphogypsum. If the mass of ammonia solution is too low, it cannot effectively capture CO2, which can easily lead to the escape of CO2, and the low reaction rate results in low carbonation efficiency. If the mass of ammonia solution is too high, the carbonation efficiency of calcium ions will not increase, which will cause waste of resources. If the CO2 pressure is too low, the reaction rate will be slow and the carbonation efficiency will be too low; if the pressure is too high, the carbonation of calcium ions cannot be carried out in time, which will cause the escape and waste of CO2. If the CO2 introduction time is too short, the carbonation efficiency of phosphogypsum will be too low; if the introduction time is too long, the carbonation efficiency of phosphogypsum will be too high, and the supernatant will be acidic, which is not conducive to the condensation and hardening of the cementitious material and the development of its performance.

[0038] In step S3, the carbon oxide gas delivery pressure is 0.1-8 MPa, the stirring speed is >700 r / min, and the carbon oxide gas introduction time is not less than 150 min.

[0039] In step S4, the pH value of the supernatant obtained after the phosphogypsum slurry is filtered is not less than 7, which ensures that CO2 is fully dissolved and fixed, and ensures the alkaline environment required for the subsequent hydration reaction of the cementitious material.

[0040] The material A in the step S4 includes a mineral powder and quicklime, and the slag sample 450-800 parts, the supernatant 300-500 parts, the mineral powder 180-450 parts, and the quicklime 2-5 parts are mixed to obtain the high-doped phosphogypsum-based carbon sequestration cementing material.

[0041] The mineral powder includes a granulated blast furnace slag powder of S95 and S105 grades, and the specific surface area is not less than 400 m 2 / kg.

[0042] The quicklime is an alkaline activator of the phosphogypsum-based slag cement, and the calcium oxide content is not less than 95%.

[0043] The carbon sequestration in the step S4 is that the unstable phosphogypsum and part of the impurities are carbonated and converted into stable carbonate inert substances.

[0044] Example 1:

[0045] As Figure 1 shown in the figure, a high-doped phosphogypsum-based carbon sequestration cementing material and a preparation method thereof are provided, and the specific steps are as follows:

[0046] S1: An organic salt leaching solution is prepared, and GA 80 parts, EDTA-4Na 8 parts, and EDTMP 1 part are mixed and then fully dissolved in 90 parts of water to obtain an organic salt leaching solution;

[0047] S2: The organic salt leaching solution in the step S1 and the raw phosphogypsum are fully mixed and uniformly stirred for 6 min at a liquid-solid ratio of 3:1, and then are left to stand at room temperature for 95 min;

[0048] S3: Ammonia standard solution of 10% of the dry basis mass of the phosphogypsum is added to the phosphogypsum slurry obtained in the step S2, and CO2 gas is introduced into the mixture of the phosphogypsum slurry and the ammonia water at a conveying pressure of 0.5 MPa, and the stirring speed is 750 r / min, and the reaction is continuously carried out for 160 min to ensure that the reaction is fully carried out;

[0049] S4: The carbonated phosphogypsum-based slurry obtained in the step S3 is filtered to obtain a slag sample and a supernatant, and 800 parts of the slag sample and 350 parts of the supernatant are taken and mixed with 185 parts of a mineral powder and 2 parts of quicklime, and then the mixture is mixed to obtain a high-doped phosphogypsum-based carbon sequestration cementing material. The mixture is poured into a 40 mm*40 mm*40 mm neat paste mold, and after demolding, the mixture is placed in a standard curing environment for curing to a specified age, and the standard compressive strength is tested. The mineral powder is a granulated blast furnace slag powder of S95, and the specific surface area is not less than 400 m 2 / kg.

[0050] The quicklime is an alkaline activator of the phosphogypsum-based slag cement, and the calcium oxide content is not less than 95%.

[0051] Example 2:

[0052] As Figure 1 shown, a high-dosage phosphogypsum-based carbon sequestration cementitious material and a preparation method thereof, the specific steps are as follows:

[0053] S1: prepare an organic salt leaching solution, in mass parts, GA 81 parts, EDTA-4Na 10 parts, EDTMP 2 parts are mixed and fully dissolved in 100 parts of water to obtain an organic salt leaching solution;

[0054] S2: the organic salt leaching solution in step S1 and the raw phosphogypsum are fully mixed and uniformly stirred for 6 min at a liquid-solid ratio of 10:1, and then are left to stand at room temperature for 95 min;

[0055] S3: ammonia standard solution of 30% of the dry basis mass of the phosphogypsum obtained in step S2 is added, and CO2 gas is introduced into the mixture of the phosphogypsum slurry and the ammonia water at a conveying pressure of 2 MPa, continuously for 160 min and at a uniform speed of 750 r / min, to ensure that the reaction is fully carried out;

[0056] S4: the carbonated phosphogypsum-based slurry obtained in step S3 is filtered to obtain a residue sample and a supernatant, and 550 parts of the residue sample and 450 parts of the supernatant are taken and mixed with 340 parts of mineral powder and 3 parts of quicklime, and then the mixture is prepared into a high-dosage phosphogypsum-based carbon sequestration cementitious material. Pour into a 40mm*40mm*40mm neat paste mold, demold and put into standard curing for curing to the specified age, and test the standard compressive strength. The mineral powder is S105 grade granulated blast furnace slag powder, and the specific surface area is not less than 400 m 2 / kg.

[0057] The quicklime is an alkaline activator for phosphogypsum-based slag cement, and the content of calcium oxide is not less than 95%.

[0058] Example 3:

[0059] As Figure 1 shown, a high-dosage phosphogypsum-based carbon sequestration cementitious material and a preparation method thereof, the specific steps are as follows:

[0060] S1: prepare an organic salt leaching solution, in mass parts, GA 81 parts, EDTA-4Na 10 parts, EDTMP 2 parts are mixed and fully dissolved in 100 parts of water to obtain an organic salt leaching solution;

[0061] S2: the organic salt leaching solution in step S1 and the raw phosphogypsum are fully mixed and uniformly stirred for 6 min at a liquid-solid ratio of 10:1, and then are left to stand at room temperature for 95 min;

[0062] S3, adding ammonia standard solution of 40% dry basis mass of phosphogypsum to the phosphogypsum slurry obtained in step S2, and introducing CO2 gas into the mixture of the phosphogypsum slurry and the ammonia water at a conveying pressure of 5 MPa, continuously for 160 min and at a uniform speed of 750 r / min to ensure that the reaction is fully carried out;

[0063] S4: filtering the carbonated phosphogypsum-based slurry obtained in step S3 to obtain a residue sample and a supernatant, and mixing 450 parts of the residue sample and 500 parts of the supernatant with 450 parts of mineral powder and 5 parts of quicklime to obtain a high-dosage phosphogypsum-based carbon sequestration cementitious material. Pouring into a 40 mm*40 mm*40 mm neat paste mold, demolding and placing in standard curing for curing to the specified age, and testing the standard compressive strength. The mineral powder is a granulated blast furnace slag powder of S95 level, and the specific surface area is not less than 400 m 2 / kg.

[0064] The quicklime is an alkaline activator of the phosphogypsum-based slag cement, and the calcium oxide content is not less than 95%.

[0065] The performance results of the carbonated phosphogypsum-based cementitious materials prepared in Examples 1-3 are shown in Table 1:

[0066] Table 1 Performance index results of Examples 1-3

[0067]

Claims

1. A method for preparing a high-doped phosphogypsum-based carbon sequestration cementitious material, characterized in that, The method comprises the following steps: S1: preparing an organic salt leaching solution; S2: uniformly mixing the organic salt leaching solution in step S1 with phosphogypsum to obtain a phosphogypsum slurry; S3: adding ammonia water to the phosphogypsum slurry obtained in step S2, and introducing carbon oxide gas into the mixture of the phosphogypsum slurry and the ammonia water and stirring to obtain a carbonized phosphogypsum-based slurry; S4: filtering the carbonized phosphogypsum-based slurry obtained in step S3 to obtain a residue sample and a supernatant, and mixing the residue sample and the supernatant with material A to obtain a high-content phosphogypsum-based carbon sequestration cementitious material after mixing and stirring; In step S1, one or more metal ion chelating agents are mixed and dissolved in water to obtain an organic salt leaching solution, and the metal ion chelating agents include one or more of amino acid derivatives, hydroxy acids, and organic polybasic phosphonic acids; in step S3, CO2 gas is introduced into the supernatant and stirred for 4-6 min, and then left to stand at room temperature for a period of time to obtain a phosphogypsum slurry; The components of the organic salt leaching solution prepared by the metal ion chelating agent are in mass parts, including GA 80-83 parts, EDTA-4Na 8-10 parts, EDTMP 1-2 parts, and 90-110 parts of water; In step S4, material A includes mineral powder and quicklime, and the high-content phosphogypsum-based carbon sequestration cementitious material is prepared by mixing 450-800 parts of the residue sample, 300-500 parts of the supernatant, 180-450 parts of the mineral powder, and 2-5 parts of the quicklime; The mineral powder includes granulated blast furnace slag powder, and the specific surface area of the granulated blast furnace slag powder is not less than 400 m 2 / kg.

2. The preparation method of the high-amount phosphogypsum-based carbon sequestration cementing material according to claim 1, characterized in that: In step S2, the liquid-solid ratio of phosphogypsum to the organic salt leaching solution is 3:1-25:1, and the phosphogypsum slurry is obtained after standing for >90 min after mixing.

3. The preparation method of the high-amount phosphogypsum-based carbon sequestration cementing material according to claim 1, characterized in that: In step S3, the concentration of ammonia water is 25%, and the mass of ammonia water is 10-40% of the dry mass of phosphogypsum.

4. The preparation method of the high-amount phosphogypsum-based carbon sequestration cementing material according to claim 1, characterized in that: In step S3, the carbon oxide gas delivery pressure is 0.1-8 MPa, the stirring speed is >700 r / min, and the carbon oxide gas is introduced for not less than 150 min.

5. The preparation method of a high-content phosphogypsum-based carbon-fixing cementitious material as described in claim 1, characterized in that: In step S4, the pH value of the supernatant obtained after filtering the phosphogypsum-based slurry is not less than 7.

6. The preparation method of a high-content phosphogypsum-based carbon-fixing cementitious material as described in claim 1, characterized in that: The calcium oxide content of the quicklime is not less than 95%.

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