Magnesium phosphate cement-based grouting material suitable for deep sea carbon sequestration as well as preparation method and application of magnesium phosphate cement-based grouting material
By combining magnesium phosphate cement-based grouting materials with coral sand, the problem of insufficient performance of silicate cement-based materials in deep-sea environments was solved, rapid coagulation, self-repairing sealing and environmentally friendly deep-sea carbon fixation effects were achieved, and the maintenance cost of sealing materials was reduced.
Patent Information
- Application Number
- CN202511054321.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-30
- Publication Date
- 2025-10-17
AI Technical Summary
Existing silicate cement-based materials suffer from low-temperature inhibition of hydration reactions in deep-sea environments, resulting in low compressive strength. They are also prone to decomposition when exposed to high concentrations of CO2 over long periods, and their production process generates high carbon emissions. Furthermore, traditional aggregate systems are incompatible with the marine environment, leading to poor performance and environmental unfriendliness of the storage materials.
Magnesium phosphate cement-based grouting materials are used. Magnesium oxide powder reacts with potassium dihydrogen phosphate to generate magnesium phosphate mortar. Coral sand is added as aggregate to form a self-sealing structure. The porosity and environmental adaptability of coral sand are utilized to achieve rapid coagulation and long-term stable sealing.
It has achieved excellent rapid sealing performance, unique self-repairing sealing mechanism, environmental friendliness and significant economic benefits, reduced the maintenance cost of sealing materials and reduced the demand for land resource exploitation.
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Abstract
Description
TECHNICAL FIELD
[0001] The application relates to the field of building materials hormones or, in particular to a magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration and a preparation method and application thereof. BACKGROUND
[0002] With the intensification of global climate change, carbon dioxide emission reduction has become the common mission of the international community. The sixth assessment report of IPCC points out that in order to achieve the temperature control target of the Paris Agreement, about 5-10 billion tons of carbon dioxide need to be treated by carbon capture and storage (CCS) technology every year by 2050. Among various CCS technologies, ocean storage has become the focus of attention due to its huge carbon storage potential (theoretical capacity of about 40,000 Gt) and relatively low cost. However, traditional ocean storage technology is limited by material performance, and there is an urgent need to develop new efficient and environmentally friendly storage materials.
[0003] The current mainstream carbon dioxide storage material is mainly silicate cement-based material, but there are significant defects in the marine environment: firstly, the low-temperature environment of deep sea seriously inhibits the hydration reaction, and the 28-day compressive strength in 4℃ seawater is only 60%-70% of that under normal temperature conditions, which is difficult to meet the rapid storage demand; secondly, long-term exposure to high-concentration CO2 environment will cause carbonation decomposition of C-S-H gel in cement stone, and the material structure will deteriorate, such as the permeability of ordinary Portland cement can increase by 2-3 orders of magnitude within 90 days under 7MPa CO2 partial pressure; thirdly, the carbon emission of cement production is high (about 0.85 tons of CO2 are emitted per ton of production), which is contrary to the initial purpose of emission reduction of CCS technology.
[0004] As a new type of cementitious material, magnesium phosphate cement (MPC) generates K- struvite and other hydration products through MgO and soluble phosphate under acidic conditions, has the advantages of early strength, fast hardening, volume stability, environmental friendliness, etc., and shows application potential in special engineering fields. Aggregate is the core component of cement-based materials, and its performance directly affects the overall performance of the material. However, the traditional aggregate system faces challenges in the marine environment: natural river sand destroys the ecology due to overexploitation, and has poor compatibility with the MPC matrix; machine-made sand has high cost, poor particle shape and high water demand; industrial waste slag has large composition fluctuations and may introduce harmful substances. Coral sand, as a typical marine sediment, is mainly composed of aragonite-type calcium carbonate (CaCO3), and has unique advantages: porous surface (specific surface area of 2000-3000 cm 2 / g), which is beneficial to the interface combination with cementitious materials; can participate in cementation reaction in acidic environment; and is naturally compatible with seawater and has strong environmental adaptability.
[0005] The current ocean sealing material field has obvious technical blank, based on this, the present application proposes the corresponding technical solutions, the research and development not only help to promote the development of ocean CCS technology, but also provide new ideas for coral reef ecological protection, have important scientific value and application prospect. SUMMARY
[0006] In view of the above technical problems, the present application discloses a kind of magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration and its preparation method and application, compared with traditional plugging material, the technical scheme of the present application has significant advantages in plugging efficiency, long-term stability and environmental friendliness.
[0007] For this, the technical scheme adopted by the present application is:
[0008] The preparation method of the magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration comprises the following steps:
[0009] Step S1, prepare magnesium oxide powder;
[0010] Step S2, mix the magnesium oxide powder and potassium dihydrogen phosphate uniformly to obtain a first mixed powder, the molar ratio of the magnesium oxide powder to the potassium dihydrogen phosphate is 2-5:1; then add borax to the first mixed powder and mix uniformly to obtain a second mixed powder; wherein the addition amount of the borax is 5% to 10% of the mass of the magnesium oxide;
[0011] Step S3, mix and stir the coral sand after grinding with the first mixing water to obtain a mixture; mix the mixture with the mixed powder, add the second mixing water, and stir uniformly to obtain a magnesium phosphate cement mortar; wherein the amount of the coral sand is 3% to 50% of the mass of the first mixed powder; the particle size of the coral sand after grinding is less than 1mm.
[0012] This technical scheme proposes a plugging solution based on magnesium phosphate mortar cement. Magnesium oxide powder reacts with potassium dihydrogen phosphate to obtain magnesium phosphate, and magnesium phosphate mortar cement has significant fast-setting characteristics and can initial set within 20 to 50 minutes. It is used for carbon sequestration, and it reacts with CO2, the reaction formula is: MgKPO4·6H2O+CO2→MgCO3+KH2PO4+H2O, the generated magnesium carbonate precipitate can automatically fill the micropores and form a self-sealing structure, which can greatly reduce the leakage problem of CO2 during the material curing period. The coral sand as aggregate can realize the sustainable utilization of marine resources, and the raw material cost of the whole material is low, and the plugging time is short.
[0013] As a further improvement of the present application, in step S1, the finished magnesium oxide with a purity of ≥90% is directly selected by high-temperature calcination and purification.
[0014] As a further improvement of the present application, the temperature of the high-temperature calcination is not less than 1200℃.
[0015] As a further improvement of the present application, in step S3, the amount of the coral sand is 10% to 50% of the mass of the first mixed powder. Further preferably, the amount of the coral sand is 50% of the mass of the first mixed powder.
[0016] As a further improvement of the present application, in step S2, the molar ratio of the magnesium oxide powder to the potassium dihydrogen phosphate is 3-5:1. Further, the molar ratio of the magnesium oxide powder to the potassium dihydrogen phosphate is 4-5:1.
[0017] As a further improvement of the present application, in step S2, the amount of the borax added is 8% to 10% of the mass of the magnesium oxide powder. Further preferably, the amount of the borax added is 9% of the mass of the magnesium oxide powder.
[0018] As a further improvement of the present application, in step S3, the particle size of the ground coral sand is less than ≤150μm.
[0019] As a further improvement of the present application, in step S3, the total mass of the first mixing water and the second mixing water is 12% to 44% of the total mass of the magnesium oxide powder, the potassium dihydrogen phosphate and the coral sand. Further preferably, the total mass of the first mixing water and the second mixing water is 16-20% of the total mass of the magnesium oxide powder, the potassium dihydrogen phosphate and the coral sand. Further preferably, the total mass of the first mixing water and the second mixing water is 18% of the total mass of the magnesium oxide powder, the potassium dihydrogen phosphate and the coral sand.
[0020] As a further improvement of the present application, the amount of the first mixing water is 0% to 30% of the total mass of the first mixing water and the second mixing water. Further, the amount of the first mixing water is 0% to 20% of the total mass of the first mixing water and the second mixing water. Further, the amount of the first mixing water is 20% of the total mass of the first mixing water and the second mixing water.
[0021] As a further improvement of the present application, the total mass of the first mixing water and the second mixing water is 18% of the total mass of the magnesium oxide powder, the potassium dihydrogen phosphate and the coral sand.
[0022] The present application also discloses a magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration, which is prepared by the preparation method of the magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration.
[0023] The present application also discloses the application of the magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration as described above, which is used for ocean sequestration materials.
[0024] As a further improvement of the present invention, the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation is poured before initial setting, and the curing environment is a temperature of 20±2°C, a humidity of 70±5%, and a carbon dioxide concentration of 20±1%.
[0025] Compared with the prior art, the present invention has the following beneficial effects:
[0026] First, it offers excellent rapid plugging performance. Compared to traditional plugging materials such as lime milk, magnesium phosphate mortar cement has significantly faster setting properties, significantly shortening the plugging operation window. Its rapid setting properties effectively reduce the risk of CO2 leakage during the material curing phase, significantly improving the safety of well plugging operations.
[0027] Second, it possesses a unique self-repairing and sealing mechanism. The material chemically reacts with leaked CO2, generating magnesium carbonate precipitates that automatically fill micropores and form a self-sealing structure. Compared to traditional cement slurries that are prone to carbonization and degradation in CO2 environments, this material exhibits excellent long-term stability.
[0028] Third, it is environmentally friendly. The potash fertilizer in the material composition and the phosphate in the reaction product can be used as a slow-release fertilizer, significantly improving the surrounding geological environment. The use of coral sand as aggregate not only achieves the sustainable utilization of marine resources, but also reduces the demand for sand and gravel mining on land, reducing the risk of ecological damage.
[0029] Fourth, the economic benefits are significant. Magnesium phosphate cement has the property of long-term maintenance-free, which can significantly save subsequent maintenance costs and has obvious comprehensive economic advantages. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 This is a flow chart of a magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation and a preparation method thereof according to an embodiment of the present invention. DETAILED DESCRIPTION
[0031] The preferred embodiments of the present invention are described in further detail below.
[0032] A method for preparing a magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation, such as Figure 1 Said, including:
[0033] Step 1: calcining the magnesium oxide powder at a high temperature; the calcination temperature is greater than 1200° C. The magnesium oxide powder calcined at high temperature has fewer impurities and is less likely to react in air, thus having relatively stable properties.
[0034] Step 2: The calcined magnesium oxide powder and analytically pure potassium dihydrogen phosphate (KH2PO4, purity ≥99%) are mixed in a high-efficiency mixer at a molar ratio of 2-5:1 to form a uniform first mixed powder.
[0035] Step 3: Add 9% of the first mixed powder mass of borax (Na2B4O7·10H2O) as a retarder, and add it in three times by using a ladder feeding method to obtain the second mixed powder.
[0036] Step 4: Select natural coral sand with a particle size of 0.5-2mm, crush it by using a jaw crusher and a ball mill in two stages, and then pass it through a 100-mesh screen (particle size ≤1mm). Pre-mix the treated coral sand with the first mixing water (total mixing water amount 0%-30%) in a planetary mixer for 1-2 minutes to obtain a pre-mixed coral sand slurry.
[0037] Step 5: Add the pre-mixed coral sand slurry and the second mixed powder into the mixer together, and slowly add the second mixing water (remaining 70%-100%) to obtain a uniform magnesium phosphate cement sand.
[0038] Step 6: Immediately transfer the prepared slurry into a high-pressure grouting device, and inject it into the target mold before initial setting (usually within 15-30 minutes after mixing) to ensure continuous and uninterrupted grouting to ensure dense filling.
[0039] The borax is a retarder, and its amount can be configured according to the required well injection time. In this embodiment, the amount of the calcined magnesium oxide powder is 0.09.
[0040] The coral sand is ground to a size of 3%-50% of the first mixed powder mass, and in this embodiment, the ground size is less than 1mm.
[0041] The total required water amount is 18% of the total mass of the second mixed powder and the coral sand.
[0042] The rapid injection of the slurry is to pour all the slurry into the mold before the initial setting of the magnesium phosphate cement slurry.
[0043] In the above technical solution, the magnesium phosphate cement first generates amorphous MgCO3 under acidic conditions (carbon dioxide), and then generates hydrated magnesium carbonate under high temperature and high pressure (such as CCS environment):
[0044] 5MgCO3+2CO2+5H2O→Mg5(CO3)4(OH)2·4H2O+2HCO3 -
[0045] In summary, the magnesium phosphate cement has a unique self-repairing plugging mechanism. The C-S-H of the traditional Portland cement decomposes under acidic conditions for a long time, and the strength decreases. Therefore, the magnesium phosphate cement reduces the maintenance cost in the later period and has significant economic benefits.
[0046] The following will be described in conjunction with specific embodiments.
[0047] Example 1
[0048] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0049] Step 1: Take 720.0 g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1;
[0050] Step 2: Take 612.0 g of potassium dihydrogen phosphate powder, and the molar ratio of magnesium oxide to potassium dihydrogen phosphate, i.e., M / P ratio, is 4;
[0051] Step 3: Stir the magnesium oxide powder and the potassium dihydrogen phosphate powder uniformly in a container;
[0052] Step 4: Take 64.8 g of borax, and the borax accounts for 0.09 times the mass of the magnesium oxide powder;
[0053] Step 5: Grind the coral sand, and then sieve after grinding, and the composition of the coral sand is shown in Table 1;
[0054] Step 6: Take 40.0 g of coral sand below 1 mm, and the coral sand accounts for 0.03 times the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder);
[0055] Step 7: The total water requirement is 258.6 g, the first mixing water accounts for 20% of the total water requirement, which is 51.7 g, and the second mixing water accounts for 80% of the total water requirement, which is 206.9 g;
[0056] Step 8: After mixing and stirring the coral sand in Step 6 and the first mixing water, mix and stir the mixed powder in Step 3, and then put them into a stirring pot for automatic stirring, and add the second mixing water in Step 7 while stirring;
[0057] Step 9: Place the stirred mortar cement into a mold and then perform curing carbonization, and the environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1% (volume concentration).
[0058] Table 1 Chemical composition of magnesium oxide and coral sand raw materials
[0059] MgO (%) CaO (%) SiO2(%) LOI (%) Heavy Magnesia 95.5 1.4 0.9 0.4 Coral Sand 0.5 51.8 1.6 43.4
[0060] Example 2
[0061] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0062] Step 1: Take 720.0 g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1;
[0063] Step 2: Take 612.0 g of potassium dihydrogen phosphate powder, and the M / P ratio is 4;
[0064] Step 3: magnesium oxide powder and potassium dihydrogen phosphate powder are stirred uniformly in a container;
[0065] Step 4: 64.8g of borax is weighed, and the borax accounts for 0.09 times the mass of the magnesium oxide powder;
[0066] Step 5: the coral sand is ground, and after grinding, it is sieved, and the composition of the coral sand is shown in Table 1;
[0067] Step 6: 133.2g of coral sand below 1mm is weighed, and the coral sand accounts for 0.10 times the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder);
[0068] Step 7: the total water requirement is 275.4g, the first mixing water accounts for 20% of the total water requirement, which is 55.1g, and the second mixing water accounts for 80% of the total water requirement, which is 220.3g;
[0069] Step 8: after mixing and stirring the coral sand in Step 6 and the first mixing water, the mixture is stirred with the mixed powder in Step 3, and is put into a stirring pot for automatic stirring, and the second mixing water in Step 7 is added while stirring;
[0070] Step 9: the stirred mortar cement is placed in a mold for standing, and then is cured and carbonized, and the environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0071] Example 3
[0072] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0073] Step 1: 720.0g of magnesium oxide powder is weighed, and the specific composition of the magnesium oxide powder is shown in Table 1;
[0074] Step 2: 612.0g of potassium dihydrogen phosphate powder is weighed, and the M / P ratio is 4;
[0075] Step 3: magnesium oxide powder and potassium dihydrogen phosphate powder are stirred uniformly in a container;
[0076] Step 4: 64.8g of borax is weighed, and the borax accounts for 0.09 times the mass of the magnesium oxide powder;
[0077] Step 5: the coral sand is ground, and after grinding, it is sieved, and the composition of the coral sand is shown in Table 1;
[0078] Step 6: 333.0g of coral sand below 1mm is weighed, and the coral sand accounts for 0.25 times the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder);
[0079] Step 7: The total water requirement is 311.4g, the first mixing water accounts for 20% of the total water requirement, which is 62.3g, and the second mixing water accounts for 80% of the total water requirement, which is 249.1g;
[0080] Step 8: After mixing and stirring the stirred coral sand and the first mixing water in step 6, the mixed powder in step 3 is stirred and placed in a stirring pot for automatic stirring, and the second mixing water in step 7 is added while stirring;
[0081] Step 9: The stirred mortar cement is placed in a mold and then cured and carbonized, and the environment is: temperature 20±2℃, humidity 70±5%, carbon dioxide concentration 20±1%.
[0082] Example 4
[0083] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0084] Step 1: Take 720.0g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1;
[0085] Step 2: Take 612.0g of potassium dihydrogen phosphate powder, and the M / P ratio is 4;
[0086] Step 3: Stir the magnesium oxide powder and potassium dihydrogen phosphate powder uniformly in a container;
[0087] Step 4: Take 64.8g of borax, and the borax accounts for 0.09 of the mass of the magnesium oxide powder;
[0088] Step 5: Grind the coral sand and sieve after grinding, and the composition of the coral sand is shown in Table 1;
[0089] Step 6: Take 666.0g of coral sand below 1mm, and the coral sand accounts for 0.50 of the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder);
[0090] Step 7: The total water requirement is 371.8g, the first mixing water accounts for 20% of the total water requirement, which is 74.3g, and the second mixing water accounts for 80% of the total water requirement, which is 297.5g;
[0091] Step 8: After mixing and stirring the stirred coral sand and the first mixing water in step 6, the mixed powder in step 3 is stirred and placed in a stirring pot for automatic stirring, and the second mixing water in step 7 is added while stirring;
[0092] Step 9: The stirred mortar cement is placed in a mold and then cured and carbonized, and the environment is: temperature 20±2℃, humidity 70±5%, carbon dioxide concentration 20±1%.
[0093] The samples after curing of Examples 1-4 were tested, and the test results of the flexural strength and compressive strength are shown in Table 2. It can be seen that, after three days of curing, the flexural strength reaches more than 6.9 MPa, and the compressive strength reaches more than 29 MPa, achieving rapid plugging. With the increase of the CS mixing ratio to 0.5, the compressive strength increases to 39 MPa. It can be seen by comparison that the optimal mixing amount of coral sand is 50% (mass percent).
[0094] Table 2: Test results of flexural strength and compressive strength
[0095] Carbonation Curing Time M / P Ratio CS Incorporation Ratio Flexural Strength (MPa) Compressive Strength (MPa) Example 1 3 days 4 0.03 7.8 28.1 Example 2 3 days 4 0.1 7.4 32.7 Example 3 3 days 4 0.25 6.9 28.4 Example 4 3 days 4 0.5 7.2 39.1
[0096] Example 5
[0097] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0098] Step 1: Take 600.0 g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1.
[0099] Step 2: Take 680.0 g of potassium dihydrogen phosphate powder, and the M / P ratio is 3.
[0100] Step 3: Stir the magnesium oxide powder and potassium dihydrogen phosphate powder uniformly in a container.
[0101] Step 4: Take 54.0 g of borax, and the borax accounts for 0.09 of the mass of the magnesium oxide powder.
[0102] Step 5: Grind the coral sand, and sieve after grinding. The composition of the coral sand is shown in Table 1.
[0103] Step 6: Take 320.0 g of coral sand below 1 mm, and the coral sand accounts for 0.25 of the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder).
[0104] Step 7: The total water requirement is 297.7 g, the first mixing water accounts for 0% of the total water requirement, which is 0 g, and the second mixing water accounts for 100% of the total water requirement, which is 297.7 g.
[0105] Step 8: Stir the coral sand in Step 6 and the mixed powder in Step 3, and put them into a stirring pot for automatic stirring. Stir while adding water in Step 7.
[0106] Step 9: Place the stirred mortar cement into a mold and let it stand, and then perform curing and carbonization. The environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0107] Example 6
[0108] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0109] Step 1: Take 600.0 g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1;
[0110] Step 2: Take 680.0 g of potassium dihydrogen phosphate powder, and the M / P ratio is 3;
[0111] Step 3: Stir the magnesium oxide powder and the potassium dihydrogen phosphate powder uniformly in a container;
[0112] Step 4: Take 54.0 g of borax, and the borax accounts for 0.09 of the mass of the magnesium oxide powder;
[0113] Step 5: Grind the coral sand, and sieve after grinding, and the composition of the coral sand is shown in Table 1;
[0114] Step 6: Take 320.0 g of coral sand below 1 mm, and the coral sand accounts for 0.25 of the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder);
[0115] Step 7: The total water requirement is 297.7 g, the first mixing water accounts for 10% of the total water requirement, which is 29.8 g, and the second mixing water accounts for 90% of the total water requirement, which is 267.9 g;
[0116] Step 8: Stir the coral sand in Step 6 and the mixed powder in Step 3, and put them into a stirring pot for automatic stirring, while adding the water in Step 7;
[0117] Step 9: Put the stirred mortar cement into a mold for standing, and then perform curing carbonization, and the environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0118] Example 7
[0119] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0120] Step 1: Take 600.0 g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1;
[0121] Step 2: Take 680.0 g of potassium dihydrogen phosphate powder, and the M / P ratio is 3;
[0122] Step 3: Stir the magnesium oxide powder and the potassium dihydrogen phosphate powder uniformly in a container;
[0123] Step 4: Take 54.0 g of borax, and the borax accounts for 0.09 of the mass of the magnesium oxide powder;
[0124] Step 5: Grind the coral sand and sieve it after grinding. The composition of the coral sand is shown in Table 1;
[0125] Step 6: Weigh 320.0 g of coral sand less than 1 mm, where the coral sand accounts for 0.25 of the first mixed powder (the sum of the mass of magnesium oxide powder and potassium dihydrogen phosphate powder);
[0126] Step 7: The total water requirement is 297.7 g, of which the first mixing water accounts for 20% of the total water requirement, which is 59.5 g, and the second mixing water accounts for 80% of the total water requirement, which is 238.2 g;
[0127] Step 8: Mix the coral sand prepared in step 6 and the mixed powder prepared in step 3, and place them in a mixing pot. Stir automatically while adding the water prepared in step 7.
[0128] Step 9: Place the mixed mortar cement in a mold and let it stand for curing and carbonization. The environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0129] Example 8
[0130] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation is prepared by the following steps:
[0131] Step 1: Weigh 600.0 g of magnesium oxide powder. The specific composition of the magnesium oxide powder is shown in Table 1;
[0132] Step 2: Weigh 680.0 g of potassium dihydrogen phosphate powder with an M / P ratio of 3;
[0133] Step 3: Stir the magnesium oxide powder and potassium dihydrogen phosphate powder in a container until evenly mixed;
[0134] Step 4: Weigh 54.0 g of borax, which accounts for 0.09 of the mass of the magnesium oxide powder;
[0135] Step 5: Grind the coral sand and sieve it after grinding. The composition of the coral sand is shown in Table 1;
[0136] Step 6: Weigh 320.0 g of coral sand less than 1 mm, where the coral sand accounts for 0.25 of the first mixed powder (the sum of the mass of magnesium oxide powder and potassium dihydrogen phosphate powder);
[0137] Step 7: The total water requirement is 297.7 g, of which the first mixing water accounts for 30 wt% of the total water requirement, which is 89.3 g, and the second mixing water accounts for 70 wt% of the total water requirement, which is 208.4 g;
[0138] Step 8: Mix the coral sand prepared in step 6 and the mixed powder prepared in step 3, and place them in a mixing pot. Stir automatically while adding the water prepared in step 7.
[0139] Step 9: Put the stirred mortar cement into the mold and place it, and then perform curing and carbonization, with the environment being: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0140] The samples after curing in the above examples 5-8 were detected, and the test results of the flexural strength and compressive strength are shown in Table 3. It can be seen that when the ratio of the first mixing water to the total mixing water is 0-30wt% of CS, the flexural strength is above 5.7MPa and the compressive strength is above 17.6MPa after three days of curing, and the flexural strength and compressive strength are the highest when the ratio of the first mixing water to the total mixing water is 20wt%. It can be seen by comparison that the optimal ratio of water to coral sand before stirring is 20%, that is, the first mixing water 1 (20wt% of the total water requirement) is added to the coral sand first, and then the second mixing water (80wt% of the total water requirement) is added during the stirring process of the entire powder (mixed powder), and the flexural strength and compressive strength of the test block reach the maximum value.
[0141] Table 3 Test results of flexural strength and compressive strength
[0142] Carbonation Curing Time M / P Ratio Water Incorporation CS Ratio Flexural Strength (MPa) Compressive Strength (MPa) Example 5 3 days 3 0 6.1 19.9 Example 6 3 days 3 0.1 6.2 19.5 Example 7 3 days 3 0.2 6.6 24.7 Example 8 3 days 3 0.3 5.7 17.6
[0143] Example 9
[0144] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon sequestration is prepared by the following steps:
[0145] Step 1: Take 400.0g of magnesium oxide powder, and the specific composition of the magnesium oxide powder is shown in Table 1.
[0146] Step 2: Take 680.0g of potassium dihydrogen phosphate powder, and the M / P ratio is 2.
[0147] Step 3: Stir the magnesium oxide powder and the potassium dihydrogen phosphate powder uniformly in a container.
[0148] Step 4: Take 36.0g of borax, and the borax accounts for 0.09 of the mass of the magnesium oxide powder.
[0149] Step 5: Grind the coral sand, and then sieve it after grinding. The composition of the coral sand is shown in Table 1.
[0150] Step 6: Take 270.0g of coral sand below 1mm, and the coral sand accounts for 0.25 of the first mixed powder (the sum of the mass of the magnesium oxide powder and the mass of the potassium dihydrogen phosphate powder).
[0151] Step 7: The total water requirement is 249.5g, the first mixing water accounts for 20% of the total water requirement, which is 49.9g, and the second mixing water accounts for 80% of the total water requirement, which is 199.6g.
[0152] Step 8: Mix the coral sand prepared in step 6 and the mixed powder prepared in step 3, and place them in a mixing pot. Stir automatically while adding the water prepared in step 7.
[0153] Step 9: Place the mixed mortar cement in a mold and let it stand for curing and carbonization. The environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0154] Example 10
[0155] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation is prepared by the following steps:
[0156] Step 1: Weigh 600.0 g of magnesium oxide powder. The specific composition of the magnesium oxide powder is shown in Table 1;
[0157] Step 2: Weigh 680.0 g of potassium dihydrogen phosphate powder with an M / P ratio of 3;
[0158] Step 3: Stir the magnesium oxide powder and potassium dihydrogen phosphate powder in a container until evenly mixed;
[0159] Step 4: Weigh 54.0 g of borax, which accounts for 0.09 of the mass of the magnesium oxide powder;
[0160] Step 5: Grind the coral sand and sieve it after grinding. The composition of the coral sand is shown in Table 1;
[0161] Step 6: Weigh 320.0 g of coral sand less than 1 mm, where the coral sand accounts for 0.25 of the first mixed powder (the sum of the mass of magnesium oxide powder and potassium dihydrogen phosphate powder);
[0162] Step 7: The total water requirement is 297.7 g, of which the first mixing water accounts for 20% of the total water requirement, which is 59.5 g, and the second mixing water accounts for 80% of the total water requirement, which is 238.2 g;
[0163] Step 8: Mix the coral sand prepared in step 6 and the mixed powder prepared in step 3, and place them in a mixing pot. Stir automatically while adding the water prepared in step 7.
[0164] Step 9: Place the mixed mortar cement in a mold and let it stand for curing and carbonization. The environment is: temperature 20±2℃, humidity 70±5%, and carbon dioxide concentration 20±1%.
[0165] Example 11
[0166] A magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation is prepared by the following steps:
[0167] Step 1: Weigh 600.0g of magnesium oxide powder, the specific composition of which is shown in Table 1.
[0168] Step 2: Weigh 408.0g of potassium dihydrogen phosphate powder, with an M / P ratio of 5.
[0169] Step 3: Stir the magnesium oxide powder and potassium dihydrogen phosphate powder evenly in a container.
[0170] Step 4: Weigh 54.0g of borax, which accounts for 0.09 of the mass of the magnesium oxide powder.
[0171] Step 5: Grind the coral sand and sieve after grinding, the composition of which is shown in Table 1.
[0172] Step 6: Weigh 252.0g of coral sand below 1mm, which accounts for 0.25 of the first mixed powder (the sum of the mass of the magnesium oxide powder and the potassium dihydrogen phosphate powder).
[0173] Step 7: The total water requirement is 236.5g, the first mixing water accounts for 20% of the total water requirement, which is 47.3g, and the second mixing water accounts for 80% of the total water requirement, which is 189.2g.
[0174] Step 8: Mix and stir the coral sand from Step 6 and the first mixing water, then stir with the mixed powder from Step 3, and place it in a stirring pot for automatic stirring, while adding the second mixing water from Step 7.
[0175] Step 9: Place the stirred mortar cement in a mold and let it stand, then perform curing carbonization, with an environment of: temperature 20±2℃, humidity 70±5%, carbon dioxide concentration 20±1%.
[0176] The flexural strength of Examples 9-11 with different curing times is shown in Table 4, and the compressive strength is shown in Table 5.
[0177] Table 4 Flexural strength test results
[0178]
[0179] Table 5 Compressive strength test results
[0180]
[0181] Note: The units in Table 4 and Table 5 are MPa.
[0182] From Table 4, it can be seen that the flexural strength of the test block with M / P ratio of 4 is the largest when carbonization curing is performed for 3 days. The flexural strength of the test block with M / P ratio of 5 is the largest when carbonization curing is performed for 7 days and 28 days. From Table 5, it can be seen that the compressive strength of the test block with M / P ratio of 4 is the largest when carbonization curing is performed for 3 days and 7 days. The compressive strength of the test block with M / P ratio of 5 is the largest when carbonization curing is performed for 28 days.
[0183] In summary, the early strength of the test block with M / P ratio of 4 is high, and the strength of the test block with M / P ratio of 5 is high when carbonization curing is performed for 28 days. Therefore, the optimal M / P ratio is 4-5.
[0184] The above description is further detailed description of the present application in combination with specific preferred embodiments, and cannot be deemed as limitation of the specific implementation of the present application to these descriptions. For ordinary skilled in the art to which the present application belongs, several simple deductions or substitutions can be made without departing from the concept of the present application, and all of them shall be deemed as falling within the protection scope of the present application.
Claims
1. A method for preparing a magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation, characterized by: The steps include: Step S1, preparing magnesium oxide powder; Step S2, mixing the magnesium oxide powder and potassium dihydrogen phosphate uniformly to obtain a first mixed powder, wherein the molar ratio of the magnesium oxide powder to potassium dihydrogen phosphate is 2-5:1; then adding borax to the first mixed powder and mixing uniformly to obtain a second mixed powder; wherein the amount of borax added is 5% to 10% of the mass of the magnesium oxide; Step S3: Grind the coral sand and mix it with the first mixing water to obtain a mixture; mix the mixture with the mixed powder, add the second mixing water, and stir evenly to obtain magnesium phosphate cement mortar; wherein the amount of coral sand is 3%-50% of the mass of the first mixed powder; and the particle size of the coral sand after grinding is less than 1 mm.
2. The method for preparing a magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 1, characterized in that: In step S1, finished magnesium oxide with a purity of ≥90% is purified by high-temperature calcination or directly selected.
3. The method for preparing the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 2, characterized in that: The temperature of the high-temperature calcination is not less than 1200°C.
4. The method for preparing a magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 1, characterized in that: In step S2, the molar ratio of the magnesium oxide powder to potassium dihydrogen phosphate is 4-5:1; in step S2, the amount of borax added is 8% to 10% of the mass of the magnesium oxide powder.
5. The method for preparing a magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 1, characterized in that: In step S3, the particle size of the coral sand after grinding is ≤150 μm.
6. The method for preparing the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 1, characterized in that: In step S3, the total mass of the first mixing water and the second mixing water is 12%-44% of the total mass of magnesium oxide powder, potassium dihydrogen phosphate and coral sand; the amount of the first mixing water is 0%-30% of the total mass of the first mixing water and the second mixing water.
7. The method for preparing the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 6, characterized in that: The amount of the first mixing water is 0% to 20% of the total mass of the first mixing water and the second mixing water.
8. Magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation, characterized by: The material is prepared by the method for preparing the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to any one of claims 1 to 7.
9. The use of the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 8, characterized in that: Materials for ocean storage.
10. The use of the magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation according to claim 9, characterized in that: The magnesium phosphate cement-based grouting material suitable for deep-sea carbon fixation is poured before initial setting, and the curing environment is a temperature of 20±2° C., a humidity of 70±5%, and a carbon dioxide concentration of 20±1%.