CN115536321A - CO capture by calcium silicate 2 And synchronously coagulating into high breaking strength material - Google Patents

Abstract

The invention discloses a method for capturing CO by calcium silicate ₂ The method for synchronously coagulating the calcium silicate mineral and the mixing water solution added with the crystal form regulator comprises the steps of mixing the calcium silicate mineral and the mixing water solution added with the crystal form regulator, stirring and forming, and then placing in a carbon dioxide atmosphere for carbonization and maintenance. The crystal form regulator comprises any one or a mixture of more than two of magnesium chloride, magnesium oxide, magnesium hydroxide, triethanolamine and amino acid. The crystal form regulating agent is creatively utilized to change the crystal form of the carbonic acid product calcium carbonate in the carbonized test block, so that the calcium carbonate test block has higher mechanical property, and calcium silicate consumes a large amount of CO in the carbonization and hardening process ₂ ，CO ₂ The highest absorption rate can reach 52 percent, and the carbonization efficiency is high.

Description

A method for calcium silicate to capture CO2 and simultaneously condense it into a material with high flexural strength

technical field

The invention belongs to the field of silicate materials, in particular to a method for calcium silicate to capture _CO2 and simultaneously condense it into a material with high flexural strength.

Background technique

The greenhouse effect of CO ₂ is generally considered to be an important cause of global warming. Therefore, research on the utilization of CO ₂ is an important issue that the world is currently facing. In recent years, many studies have shown that the use of calcium silicate materials to react with CO ₂ to form calcite-type calcium carbonate, and obtain better mechanical strength, and then condense into block building materials is a new technology path for CO ₂ utilization .

On the other hand, low flexural strength is an inherent disadvantage of Portland cement since its invention. Adding fiber materials to Portland cement is a means to improve the flexural strength of cement, such as patent CN201611269519.5 Disclosed is a kind of anti-fracture and anti-crack concrete based on basalt fiber and its preparation method. Using cement as raw material, cement, sand, coarse aggregate, basalt fiber and carbon fiber are mixed, and the flexural strength of the prepared concrete can reach 45-50MPa. Patent CN202210220420.5 discloses a preparation method of waste glass powder modified glass fiber reinforced cement mortar. Ordinary Portland cement is used as raw material, sand is Huaihe river sand, and modified glass fiber is added to make the cement mortar resistant to bending Strength is increased by up to 23%. However, with the increase of the fiber content, the uniformity of the cement is difficult to solve, especially when it is made into concrete containing aggregates such as stones, it is difficult to distribute the fibers evenly in the concrete, and the flow of the concrete will be significantly reduced This makes it difficult for cement or concrete to be prepared into building block materials with high flexural strength, which greatly limits the improvement of cement or concrete flexural strength.

Calcium silicate minerals react with CO ₂ , referred to as carbonization reaction, and the carbonization product is usually cubic calcite-type calcium carbonate. If the carbonization product is regulated and formed into fibrous aragonitic calcium carbonate through the method of crystal form regulation, the flexural strength of the block shape will be improved, and because the fibrous calcium carbonate is formed in situ through the reaction, the formed The fiber content will not affect the fluidity of cement and concrete.

Contents of the invention

Purpose of the invention: The technical problem to be solved by the present invention is to aim at the deficiencies of the prior art, and to provide a method for controlling the carbonization of calcium silicate minerals into fibrous aragonite-type calcium carbonate by using a crystal form control method to realize silicic acid Calcium captures _CO2 and simultaneously condenses into a high flexural strength material.

In order to achieve the above object, the technical scheme that the present invention takes is as follows:

A method for calcium silicate to capture _CO2 and simultaneously condense into a material with high flexural strength. Calcium silicate minerals are mixed with a mixing aqueous solution added with a crystal form regulator, stirred and formed, and then placed in a carbon dioxide atmosphere for carbonization curing .

Specifically, the crystal form regulator is selected from any one or a mixture of two or more of magnesium chloride, magnesium oxide, magnesium hydroxide, triethanolamine, and amino acids.

Specifically, the calcium silicate mineral is 3CaO·2SiO ₂ (C ₃ S ₂ ), 3CaO·SiO ₂ (C ₃ S), 2CaO·SiO ₂ (C ₂ S), CaO·SiO ₂ (CS) any one or a combination of two or more. Wherein, 2CaO·SiO ₂ includes but not limited to γ-type dicalcium silicate 2CaO·SiO ₂ (γ-C ₂ S), β-type dicalcium silicate 2CaO·SiO ₂ (β-C ₂ S).

Preferably, when the crystal form regulator is magnesium chloride, magnesium oxide or magnesium hydroxide, the molar ratio of the crystal form regulator to calcium ions in the calcium silicate mineral is 0.01-0.5:1;

When the crystal form regulator is triethanolamine, the mass concentration of triethanolamine in the mixing aqueous solution is 0.01-5%;

When the crystal form regulator is an amino acid, the concentration of the amino acid in the mixing aqueous solution is 0.01-0.5 mol/L;

Preferably, the crystal form regulator is selected from any one of magnesium chloride, magnesium oxide or magnesium hydroxide, and the molar ratio of magnesium to calcium is 0.1.

Preferably, the calcium silicate mineral is ground to a particle size of <80 μm.

Specifically, the calcium silicate mineral and the aqueous mixing solution are mixed according to a water-cement ratio of 0.3-0.6, preferably 0.5.

Preferably, in the carbon dioxide atmosphere, the volume concentration of carbon dioxide is not lower than 5%, preferably not lower than 98%.

Preferably, the carbonization conditions are as follows: the gas pressure is 0.1-0.5 MPa, the temperature is 60-90° C., and the carbonization time is more than 5 hours.

Further, after the carbonization is completed, the test block is continuously cured in a carbon dioxide atmosphere after demoulding.

Specifically, the CO ₂ gas used for carbonization curing is industrial flue gas or industrially prepared CO ₂ gas.

Beneficial effect:

(1) The present invention creatively utilizes the crystal form regulating agent to change the carbonic acid product calcium carbonate crystal form in the test block after carbonization, so that it has higher mechanical properties, and wherein the maximum flexural strength at 28 days can be increased to 148%.

(2) The calcium silicate in the present invention consumes a large amount of CO ₂ during the carbonization and hardening process, the CO ₂ absorption rate can reach up to 52%, and the carbonization efficiency is high.

(3) the method of the present invention does not need to add fiber, can not cause other adverse effects to cement, the fiber content of formation can not influence cement fluidity more or less, has greatly improved the flexural strength of calcium silicate carbonization hardening test block simultaneously, has Good application prospects.

Description of drawings

The advantages of the above and/or other aspects of the present invention will become clearer as the present invention will be further described in detail in conjunction with the accompanying drawings and specific embodiments.

Figure 1 shows the QXRD analysis results of the carbonized test block after adding different dosage regulators to C ₃ S ₂ in Example 1.

Figure 2 is a scanning electron micrograph of the carbonized test block without adding a regulator in Example 1.

Fig. 3 is a scanning electron micrograph of the carbonized test block after adding a regulator according to the magnesium-calcium molar ratio of 0.1 in Example 1.

detailed description

The present invention can be better understood from the following examples.

Embodiment 1～4:

Step 1, weigh a certain mass of C ₃ S ₂ and grind it in a ball mill jar for 1 hour, so that the particle size of the ground C ₃ S ₂ mineral is <40 μm, and reserve it for later use;

Step 2, configuring magnesium chloride solutions with different concentrations, respectively 0, 0.05, 0.1, 0.5 in magnesium-calcium molar ratio;

Step 3: Weigh 450g of spare C ₃ S ₂ , add 225g of magnesium chloride solution according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g of standard sand midway, and stir again to make it evenly mixed.

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160mm mold and place it on a vibrating table for vibration molding;

Step 5: Put the mold shaken in step 4 into the reactor. After the mold is put in, open the air inlet and the air outlet, and slowly introduce gas with a volume concentration of 99±1% CO ₂ to discharge the air inside the reactor. 2 After a few minutes, close the vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing;

After testing, Table 1 shows the 28-day compressive and flexural strength under different examples.

Table 1

Example Magnesium Calcium Molar Ratio 28-day compressive strength/MPa 28-day flexural strength/MPa 28-day carbon dioxide absorption % 1 0 65.6 6.3 42 2 0.05 67 10.6 41 3 0.1 71 15.6 40.2 4 0.5 58 8.4 38

It can be seen from Table 1 that adding a certain amount of magnesium chloride can effectively improve the mechanical properties of the calcium silicate mortar test block. When the molar ratio of magnesium to calcium is 0.05, the flexural strength of the test block is improved compared with that when the molar ratio of magnesium to calcium is 0. The compressive strength increased by 68%, and the compressive strength increased by 2%; when the magnesium-calcium molar ratio was 0.1, the flexural strength increased by 148%, and the compressive strength increased by 8%, but the magnesium-calcium molar ratio increased to 0.5 When , the strength of the test block showed a downward trend compared with when the molar ratio of magnesium to calcium was 0.1, which indicated that there was an optimal dosage of the molar ratio of magnesium to calcium.

The QXRD results of the test pieces after 28 days of carbonization of C ₃ S ₂ with different magnesium-calcium molar ratios are shown in Figure 1. The aragonite content changed significantly under the influence of magnesium chloride. When the magnesium-calcium molar ratio increased from 0 to 0.1, the aragonite content increased from 8% to 36%, while the calcite content decreased from 45% to 12%, which indicated that the addition of magnesium chloride, the carbonization product aragonite began to become the main calcium carbonate Crystal form, and with the increase of aragonite content, the flexural strength of the test block also increases, indicating that the increase of aragonite content is beneficial to increase the flexural strength of the test block. However, further increasing the MgCl molar ratio from 0.1 to 0.5 resulted in a decrease in aragonite (from 36% to 31%) and calcite (from 12% to 7%) contents. The compressive and flexural strengths also decreased compared with the Mg-Ca molar ratio of 0.1. In addition, after adding MgCl, the total amount of CaCO3 produced by carbonation decreased with the increase of _MgCa molar ratio, and the amount of uncarbonated _C3S2 also increased from the initial 10% to 29%. It shows that the addition of magnesium chloride is beneficial to the formation of aragonite, and the formed aragonite is conducive to improving the flexural strength of the C ₃ S ₂ test block, but excessive magnesium chloride will inhibit carbonization, reduce the total amount of calcium carbonate produced by carbonization, and will instead lead to a decrease in strength.

The scanning electron microscope of the C ₃ S ₂ carbonized test block with different magnesium-calcium molar ratios is shown in Figure 2 and Figure 3. It can be seen that when the magnesium-calcium molar ratio is 0, the carbonization product of the C ₃ S ₂ carbonized test block is mainly calcite Mainly, this can be found from the quantitative results of QXRD. When the molar ratio of magnesium to calcium is 0.1, a large number of fibrous aragonites can be found in the scanning electron microscope. These aragonites cross each other and fill the space between carbonized products. porosity, so as to improve the effect of flexural strength.

Embodiment 5～8:

Step 1: Weigh a certain amount of γ-C ₂ S and grind it in a ball mill jar for 1 hour, so that the particle size of the γ-C ₂ S mineral after grinding is <40 μm, and keep it for later use;

Step 2, configuring magnesium chloride solutions with different concentrations, respectively 0, 0.05, 0.1, 0.5 in magnesium-calcium molar ratio;

Step 3: Weigh 450g of spare γ-C ₂ S, add 225g of magnesium chloride solution according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g of standard sand in the middle, stir again to make it evenly mixed,

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160 mold and place it on a vibrating table for vibration molding;

Step 5, put the mold shaken in step 4 into the reaction kettle, after the mold is put in, open the air inlet and the air outlet, slowly introduce _CO2 gas with a volume concentration of 99±1%, and discharge the air inside the reaction kettle, After 2 minutes, close the air vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing;

After testing, Table 2 shows the compressive and flexural strength at different ages under different examples.

Table 2

Example Magnesium Calcium Molar Ratio 28d compressive strength/MPa 28d flexural strength/MPa 28-day carbon dioxide absorption % 5 0 68.2 7.1 46.5 6 0.05 73.1 12.6 45.2 7 0.1 75.5 16.3 44.3 8 0.5 71.5 9.2 42.1

Embodiment 9～12:

Step 1: Weigh a certain amount of β-C ₂ S and grind it in a ball mill jar for 1 hour, so that the particle size of the β-C ₂ S mineral after grinding is <40 μm, and keep it for later use;

Step 2, configuring magnesium chloride solutions with different concentrations, respectively 0, 0.05, 0.1, 0.5 in magnesium-calcium molar ratio;

Step 3: Weigh 450g of spare β-C ₂ S, add 225g of magnesium chloride solution according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g of standard sand in the middle, stir again to make it evenly mixed,

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160 mold and place it on a vibrating table for vibration molding;

Step 5, put the mold shaken in step 4 into the reaction kettle, after the mold is put in, open the air inlet and the air outlet, slowly introduce _CO2 gas with a volume concentration of 99±1%, and discharge the air inside the reaction kettle, After 2 minutes, close the air vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing;

After testing, Table 3 shows the compressive and flexural strength at different ages under different examples.

table 3

Example Magnesium Calcium Molar Ratio 28-day compressive strength/MPa 28-day flexural strength/MPa 28-day carbon dioxide absorption % 9 0 70.5 7.8 46.1 10 0.05 74.2 13.2 44.6 11 0.1 76.7 17.5 44.1 12 0.5 72.4 8.8 42.8

Embodiment 13～16:

Step 1, weigh a certain mass of C ₃ S and grind it in a ball mill jar for 1 hour, so that the particle size of the ground C ₃ S mineral is <40 μm, and reserve it for later use;

Step 2, configuring magnesium chloride solutions with different concentrations, respectively 0, 0.05, 0.1, 0.5 in magnesium-calcium molar ratio;

Step 3: Weigh 450g of spare C ₃ S, add 225g of magnesium chloride solution according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g of standard sand in the middle, stir again to make it evenly mixed,

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160 mold and place it on a vibrating table for vibration molding;

Step 5, put the mold shaken in step 4 into the reaction kettle, after the mold is put in, open the air inlet and the air outlet, slowly introduce _CO2 gas with a volume concentration of 99±1%, and discharge the air inside the reaction kettle, After 2 minutes, close the air vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing;

After testing, Table 4 shows the compressive and flexural strength at different ages under different examples.

Table 4

Example Magnesium Calcium Molar Ratio 28-day compressive strength/MPa 28-day flexural strength/MPa 28-day carbon dioxide absorption % 13 0 73.6 8.2 54.6 14 0.05 75.2 13.5 52.7 15 0.1 78.6 17.3 51.5 16 0.5 74.2 10.8 50.1

Embodiment 17～20:

Step 1, weigh a certain mass of CS and grind it in a ball mill jar for 1 hour, so that the particle size of the CS mineral after grinding is <40 μm, and keep it for later use;

Step 2, configuring magnesium chloride solutions with different concentrations, respectively 0, 0.05, 0.1, 0.5 in magnesium-calcium molar ratio;

Step 3, weigh 450g spare CS, add 225g magnesium chloride solution according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g standard sand in the middle, stir again to make it mix evenly,

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160 mold and place it on a vibrating table for vibration molding;

Step 5, put the mold shaken in step 4 into the reaction kettle, after the mold is put in, open the air inlet and the air outlet, slowly introduce _CO2 gas with a volume concentration of 99±1%, and discharge the air inside the reaction kettle, After 2 minutes, close the air vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing;

After testing, Table 5 shows the compressive and flexural strength at different ages under different examples.

table 5

Example Magnesium Calcium Molar Ratio 28-day compressive strength/MPa 28-day flexural strength/MPa 28-day carbon dioxide absorption % 17 0 58.2 5.9 35.2 18 0.05 62.3 9.5 33.4 19 0.1 66.8 14.1 32.6 20 0.5 59.8 10.8 30.2

Embodiment 21～24:

Step 1, weigh a certain mass of C ₃ S ₂ and grind it in a ball mill jar for 1 hour, so that the particle size of the ground C ₃ S ₂ mineral is <40 μm, and reserve it for later use;

Step 2, weighing triethanolamine according to 1%, 2%, and 5% of the mass of C ₃ S ₂ to be taken, and configuring it into a triethanolamine solution;

Step 3: Weigh 450g of spare C ₃ S ₂ , add 225g of triethanolamine solution according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g of standard sand in the middle, stir again to make it evenly mixed,

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160 mold and place it on a vibrating table for vibration molding;

Step 5, put the mold shaken in step 4 into the reaction kettle, after the mold is put in, open the air inlet and the air outlet, slowly introduce _CO2 gas with a volume concentration of 99±1%, and discharge the air inside the reaction kettle, After 2 minutes, close the air vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing.

After testing, Table 6 shows the compressive and flexural strength at different ages under different examples.

Table 6

Example Triethanolamine 28-day compressive strength/MPa 28-day flexural strength/MPa 28-day carbon dioxide absorption % twenty one 0 65.6 6.3 42 twenty two 1% 66.4 7.8 41.3 twenty three 2% 69.5 12.1 41.7 twenty four 5% 69.3 10.8 41.4

Embodiment 25～28:

Step 1, weigh a certain mass of C ₃ S ₂ and grind it in a ball mill jar for 1 hour, so that the particle size of the ground C ₃ S ₂ mineral is <40 μm, and reserve it for later use;

Step 2, select different amino acids to configure the solution, the selected amino acids and concentrations are 0.25mol/L arginine, 0.25mol/L serine, 0.25mol/L aspartic acid;

Step 3: Weigh 450g of spare C ₃ S ₂ , add the three different amino acids in step 2 according to the water-cement ratio of 0.5, then stir in the mixer, add 1350g of standard sand in the middle, and stir again to make it evenly mixed.

Step 4: Pour the mortar stirred in Step 3 into a 40×40×160 mold and place it on a vibrating table for vibration molding;

Step 5, put the mold shaken in step 4 into the reaction kettle, after the mold is put in, open the air inlet and the air outlet, slowly introduce _CO2 gas with a volume concentration of 99±1%, and discharge the air inside the reaction kettle, After 2 minutes, close the air vent. Adjust the pressure gauge to keep the _CO2 pressure in the reactor at 0.2MPa, set the temperature at 70°C, and take it out after accelerated carbonization in the reactor for 6 hours to remove the mold and take out the test block;

Step 6, continue to put the formed test block into the reaction kettle under the same carbonization conditions in step 5 to continue carbonization, and take it out after 28 days for strength testing.

After testing, Table 7 shows the compressive and flexural strength at different ages under different examples.

Table 7

Example amino acid 28-day compressive strength/MPa 28-day flexural strength/MPa 28-day carbon dioxide absorption % 25 0 65.6 6.3 42 26 arginine 67.6 11.1 40.3 27 serine 72.4 14.4 41.2 28 aspartic acid 71.2 14.8 41.6

The present invention provides an idea and method for calcium silicate to capture _CO and synchronously condense it into a material with high flexural strength. There are many methods and approaches to realize this technical solution, and the above is only a preferred embodiment of the present invention. It should be pointed out that those skilled in the art can make some improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. All components that are not specified in this embodiment can be realized by existing technologies.

Claims (10)

1. CO capture by calcium silicate ₂ The method is characterized in that calcium silicate minerals and a mixing water solution added with a crystal form regulator are mixed, stirred and formed, and then placed in a carbon dioxide atmosphere for carbonization and maintenance.

2. CO capture by calcium silicate according to claim 1 ₂ The method is characterized in that the crystal form regulator is selected from any one or a mixture of more than two of magnesium chloride, magnesium oxide, magnesium hydroxide, triethanolamine and amino acid.

3. The calcium silicate CO capture of claim 1 ₂ And synchronously condensing into a material with high breaking strength, which is characterized in that the calcium silicate mineral is 3CaO 2SiO ₂ 、3CaO·SiO ₂ 、2CaO·SiO ₂ 、CaO·SiO ₂ Any one ofOne or a combination of two or more.

4. CO capture by calcium silicate according to claim 2 ₂ And the method is characterized in that when the crystal form regulating agent is magnesium chloride, magnesium oxide or magnesium hydroxide, the molar ratio of the crystal form regulating agent to calcium ions in calcium silicate minerals is 0.01-0.5;

when the crystal form regulator is triethanolamine, the mass concentration of the triethanolamine in the mixed aqueous solution is 0.01-5%;

when the crystal form regulator is amino acid, the concentration of the amino acid in the mixed water solution is 0.01-0.5 mol/L.

5. CO capture by calcium silicate according to claim 1 ₂ And synchronously coagulating into a material with high breaking strength, characterized in that the calcium silicate mineral is ground into mineral grain size<80μm。

6. The calcium silicate CO capture of claim 1 ₂ And synchronously coagulating into a material with high flexural strength, which is characterized in that the calcium silicate mineral and the mixing water solution are mixed according to the water-cement ratio of 0.3-0.6.

7. CO capture by calcium silicate according to claim 1 ₂ And synchronously condensing the carbon dioxide into a material with high breaking strength, and is characterized in that the volume concentration of the carbon dioxide in the carbon dioxide atmosphere is not lower than 5 percent.

8. The calcium silicate CO capture of claim 1 ₂ And synchronously condensing the mixture into a material with high breaking strength, which is characterized in that the carbonization conditions are as follows: the gas pressure is 0.1-0.5 MPa, the temperature is 60-90 ℃, and the carbonization time is more than 5 h.

9. The calcium silicate CO capture of claim 1 ₂ And synchronously concreting into a material with high breaking strength,the method is characterized in that after the test block is carbonized, the test block is demolded and then continuously maintained in carbon dioxide atmosphere.

10. The calcium silicate CO capture of claim 1 ₂ And synchronously condensing the mixture into a material with high breaking strength, which is characterized in that CO used for carbonization and maintenance ₂ The gas is industrial flue gas or industrially prepared CO ₂ A gas.

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