阅读说明：本技术 一种镁基胶凝材料及其制备方法和应用 (Magnesium-based cementing material and preparation method and application thereof ) 是由 王发洲 刘志超 吕璨宇 胡曙光 于 2021-11-19 设计创作，主要内容包括：本发明属于水泥化工技术领域,具体涉及一种镁基胶凝材料及其制备方法和应用。本发明所述的镁基胶凝材料包括：菱镁矿、砂岩和水；所述菱镁矿中：CaO质量百分含量<5％,SiO-(2)质量百分含量<5％,Al-(2)O-(3)质量百分含量<5％,Fe-(2)O-(3)质量百分含量<7％,MgO质量百分含量为37～50％；所述砂岩中：SiO-(2)质量百分含量>70％,CaO质量百分含量<10％,Al-(2)O-(3)的质量百分含量<10％,Fe-(2)O-(3)质量百分含量<5％。本发明所述的镁基胶凝材料中不包含MgCl-(2),避免了因MgCl-(2)遇水溶解,而导致的凝胶材料强度的降低,耐水性较强。同时,避免了镁基胶凝材料因氯化镁的存在而导致的对Fe、Al金属的腐蚀性。(The invention belongs to the technical field of cement chemical industry, and particularly relates to a magnesium-based cementing material, and a preparation method and application thereof. The magnesium-based cementing material comprises: magnesite, sandstone and water; in the magnesite: CaO content by mass percentage<5％，SiO 2 Mass percentage of<5％，Al 2 O 3 Mass percentage of<5％，Fe 2 O 3 Mass percentage of<7 percent of MgO, and the mass percentage of MgO is 37-50 percent; in the sandstone: SiO 2 2 Mass percentage of>70 percent of CaO in percentage by mass<10％，Al 2 O 3 In percentage by mass of<10％，Fe 2 O 3 Mass percentage of<5 percent. The invention is as describedDoes not contain MgCl 2 Avoid due to MgCl 2 The gel material is dissolved in water, so that the strength of the gel material is reduced and the water resistance is strong. Meanwhile, the corrosion of the magnesium-based cementing material to Fe and Al metal caused by the existence of magnesium chloride is avoided.)

1. The magnesium-based cementing material is characterized by comprising the following preparation raw materials: magnesite, sandstone and water;

in the magnesite: CaO in percentage by mass<5％，SiO₂In percentage by mass of<5％，Al₂O₃In percentage by mass of<5％，Fe₂O₃In percentage by mass of<7 percent of MgO, and the mass percentage of MgO is 37-50 percent;

in the sandstone: SiO 2₂In percentage by mass of>70 percent of CaO in percentage by mass<10％，Al₂O₃In percentage by mass of<10％，Fe₂O₃In percentage by mass of<5％。

2. The magnesium-based cement as claimed in claim 1, wherein the magnesite contains CaO 0.89% by mass and SiO₂1.23% by mass of Al₂O₃2.880% by mass of Fe₂O₃The content of (A) is 5.75% by mass, and the content of MgO is 43.025% by mass.

3. The magnesium-based cement according to claim 1, wherein in the magnesite, SiO is₂74.887 percent by mass, 5.366 percent by mass of CaO and Al₂O₃8.142% by mass of Fe₂O₃3.406% by mass and 1.223% by mass of MgO.

4. The magnesium-based cementing material according to any one of the claims 1 to 3, characterized in that the mass ratio of magnesite to sandstone is 65 to 75: 25 to 35.

5. The preparation method of the magnesium-based cementing material according to any one of the claims 1 to 4, characterized by comprising the following steps:

mixing magnesite and sandstone, and molding the obtained mixture to obtain a molding raw material;

calcining the molding raw material to obtain clinker;

mixing the clinker with water, and molding to obtain a primary cementing material;

and carbonizing and curing the primary cementing material to obtain the magnesium-based cementing material.

6. The production method according to claim 5, characterized in that the calcination comprises sequentially performing a first calcination and a second calcination; the temperature of the first calcination is 830-950 ℃, and the time is 0.5-1 h; the temperature of the second calcination is 1120-1350 ℃, and the time is 0.5-3 h.

7. The preparation method according to claim 5, wherein the mass ratio of the clinker to the water is 1: (0.1-0.4).

8. The method of claim 5, wherein the forming comprises pressing or casting.

9. The method of claim 5, wherein the carbonized cured CO is₂The concentration is 20-99%, the gas pressure is 0.1-0.4 MPa, the relative humidity is 10-99%, the carbonization curing temperature is-20-120 ℃, and the carbonization curing time is 10 min-28 d.

10. Use of a magnesium-based cementitious material as defined in any one of claims 1 to 4 or obtained by a method as defined in any one of claims 5 to 9 in a construction material.

Technical Field

The invention belongs to the technical field of cement chemical industry, and particularly relates to a magnesium-based cementing material, and a preparation method and application thereof.

Background

The magnesium cement gel material is a magnesium-based gel material, has excellent heat preservation and insulation, fire prevention and moisture prevention, light weight and earthquake resistance, high strength and durability, no toxicity and no emission, and can be widely used as a building material based on the excellent performance.

At present, the magnesium cement cementing material in the prior art is mainly magnesium oxychloride cement, which is prepared by calcining magnesite to obtain magnesium oxide (MgO) and then mixing the magnesium oxide (MgO) with magnesium chloride (MgCl)₂) Water (H)₂O), stirring, forming, curing and the like, but the prepared magnesium oxychloride cement has poor water resistance due to the existence of internal magnesium chloride, gradually loses strength in water, and the strength loss rate can reach 60-80%. And because of MgCl in the magnesium oxychloride cement₂The components contain chloride ions, and the chloride ions have strong corrosivity on metals such as Fe, Al and the like, thereby seriously limiting the application of the magnesium-based cementing material.

Disclosure of Invention

In view of the above, the invention provides a magnesium-based cementing material, a preparation method and an application thereof, and the magnesium-based cementing material provided by the invention has good water resistance, does not contain chloride ions in the composition, and has no corrosivity on metals such as Fe, Al and the like.

The invention provides a magnesium-based cementing material which comprises the following preparation raw materials: magnesite, sandstone and water;

in the magnesite, the mass percentage of CaO is<5％，SiO₂In percentage by mass of<5％，Al₂O₃In percentage by mass of<5％，Fe₂O₃In percentage by mass of<7 percent of MgO, and the mass percentage of MgO is 37-50 percent;

in the sandstone: SiO 2₂In percentage by mass of>70 percent of CaO in percentage by mass<10％，Al₂O₃In percentage by mass of<10％，Fe₂O₃In percentage by mass of<5％。

PreferablyIn the magnesite, the mass percentage of CaO is 0.89%, and SiO is₂1.23% by mass of Al₂O₃2.880% by mass of Fe₂O₃The content of (A) is 5.75% by mass, and the content of MgO is 43.025% by mass.

Preferably, in the magnesite, the mass percentage of CaO is 5.366%, and SiO is₂74.887% by mass of Al₂O₃8.142% by mass of Fe₂O₃3.406% by mass and 1.223% by mass of MgO.

Preferably, the mass ratio of the magnesite to the sandstone is 65-75: 25 to 35.

The invention also provides a preparation method of the magnesium-based cementing material, which comprises the following steps:

mixing magnesite and sandstone, and molding the obtained mixture to obtain a molding raw material;

calcining the molding raw material to obtain clinker;

mixing the clinker with water, and molding to obtain a primary cementing material;

and carbonizing and curing the primary cementing material to obtain the magnesium-based cementing material.

Preferably, the calcining comprises sequentially performing a first calcining and a second calcining; the temperature of the first calcination is 830-950 ℃, and the time is 0.5-1 h; the temperature of the second calcination is 1120-1350 ℃, and the time is 0.5-3 h.

Preferably, the mass ratio of the clinker to the water is 1: (0.1-0.4).

Preferably, the shaping comprises pressing or casting.

Preferably, the CO of the carbonization curing₂The concentration is 20-99%, the gas pressure is 0.1-0.4 MPa, the relative humidity is 10-99%, the carbonization curing temperature is-20-120 ℃, and the carbonization curing time is 10 min-28 d.

The invention also provides the application of the magnesium-based cementing material or the magnesium-based cementing material prepared by the preparation method in building materials.

In order to achieve the above object, the present invention provides a magnesium-based cement, comprising the following preparation raw materials: magnesite, sandstone and water; in the magnesite, the mass percentage of CaO is<5％，SiO₂In percentage by mass of<5％，Al₂O₃In percentage by mass of<5％，Fe₂O₃In percentage by mass of<7 percent of MgO, and the mass percentage of MgO is 37-50 percent; in the sandstone: SiO 2₂In percentage by mass of>70 percent of CaO in percentage by mass<10％，Al₂O₃In percentage by mass of<10％，Fe₂O₃In percentage by mass of<5 percent. The magnesium-based cementing material takes magnesite and sandstone as main preparation raw materials to obtain the cementing material taking magnesium carbonate, magnesium silicate and magnesium hydroxide composite crystal as main raw materials, and the cementing material does not contain MgCl₂Avoid due to MgCl₂The strength of the gel material is reduced due to dissolution in water; the magnesium-based cementing material is immiscible with water and has strong water resistance. Meanwhile, the corrosion of the magnesium-based cementing material to Fe and Al metal caused by the existence of magnesium chloride is avoided.

The data of the examples show that the compressive strength of the gel material provided by the invention is only reduced by about 15% after the gel material is soaked in water for 7 days. And the corrosion of the magnesium-based cementing material prepared by the invention to aluminum is far less than that of the cementing material in the comparative example 1.

The invention also provides a preparation method of the magnesium-based cementing material, which comprises the following steps: mixing magnesite and sandstone, and molding the obtained mixture to obtain a molding raw material; calcining the raw material to obtain clinker; mixing the clinker with water, and molding to obtain a primary cementing material; and carbonizing and curing the primary cementing material to obtain the magnesium-based cementing material. The invention is obtained by not including MgCl₂The magnesite and the sandstone are used as preparation raw materials, and are calcined, blended with water and formed to obtain a primary gel material; then carbonizing and curing the primary gel material to obtain the gel mainly comprising magnesium carbonate, magnesium silicate and magnesium hydroxide composite crystalCompared with the mode of curing the magnesium oxychloride cement into a gel state by water in the prior art, the gel phase improves the water resistance of the magnesium-based cementing material. Meanwhile, chloride ions are not introduced into the preparation method, so that the corrosion resistance is ensured.

Drawings

FIG. 1 is a diagram of a process for preparing a magnesium-based cementitious material according to the present invention;

FIG. 2 is a corrosion performance test chart of the iron plate of example 1;

fig. 3 is a corrosion performance test chart of the iron plate of comparative example 1.

Detailed Description

The invention provides a magnesium-based cementing material, which mainly comprises the following preparation raw materials: magnesite, sandstone and water.

In the invention, in the magnesite: CaO in percentage by mass<5％，SiO₂In percentage by mass of<5％，Al₂O₃In percentage by mass of<5％，Fe₂O₃In percentage by mass of<7 percent of MgO, and the mass percentage of MgO is 37-50 percent; preferably, the magnesite comprises the following components in percentage by mass: CaO 0.89 wt%, SiO₂1.23% by mass of Al₂O₃2.880% by mass of Fe₂O₃Is 5.75 percent by mass and the MgO is 43.025 percent by mass.

In the invention, the magnesite preferably also comprises other components with a loss on ignition at 900 ℃ of 40-60% by mass, specifically water, carbon dioxide and other gaseous components which can be lost at 900 ℃.

In the present invention, the sandstone comprises: SiO 2₂In percentage by mass of>70 percent of CaO in percentage by mass<10％，Al₂O₃In percentage by mass of<10％，Fe₂O₃In percentage by mass of<5 percent; preferably, in the sandstone, SiO₂74.887 percent by mass, 5.366 percent by mass of CaO and Al₂O₃8.142% by mass of Fe₂O₃Quality of (1)3.406 percent of weight percentage and 1.223 percent of MgO by weight percentage.

In the invention, the sandstone preferably also comprises other components with a loss on ignition at 900 ℃ of 5-10% by mass, specifically water, carbon dioxide and other gaseous components which can be lost at 900 ℃.

In the invention, the mass ratio of the magnesite to the sandstone is preferably 65-75: 25-35, and more preferably 70.6: 29.4.

in the present invention, the starting materials used in the present invention are preferably commercially available products unless otherwise specified.

The invention also provides a preparation method of the magnesium-based cementing material, which comprises the following steps:

mixing magnesite and sandstone, and molding the obtained mixture to obtain a molding raw material;

calcining the raw material to obtain clinker;

mixing the clinker with water, and molding to obtain a primary cementing material;

and carbonizing and curing the primary cementing material to obtain the magnesium-based cementing material.

The magnesite and sandstone are mixed, and the mixture is molded to obtain the molding raw material.

Before the mixing, the present invention preferably further comprises crushing and grinding the magnesite and the sandstone, respectively, and the specific embodiment of the crushing and grinding is not particularly limited, and the operation known to those skilled in the art can be adopted. In the present invention, the median particle size of the magnesite is preferably <150 μm, more preferably <100 μm. In the present invention, the median particle size of the sandstone is preferably <150 μm, more preferably <100 μm.

In the invention, the mass ratio of the magnesite to the sandstone is preferably 65-75: 25-35, and more preferably 70.6: 29.4.

in the present invention, the mixing is preferably mechanical stirring, and the mechanical stirring is not particularly limited in the present invention, and the raw materials may be uniformly mixed by an operation well known to those skilled in the art.

In the present invention, the forming treatment preferably includes granulation or pressing, and more preferably granulation; in the present invention, the granulation is preferably performed in a twin-roll mill.

After the molding raw material is obtained, the molding raw material is calcined to obtain the clinker.

In the present invention, the calcination preferably includes sequentially performing a first calcination and a second calcination; the first calcining temperature is preferably 830-950 ℃, and further preferably 850-900 ℃; the first calcination time is 0.5-1 h, and preferably 0.8-1 h. In the invention, the temperature of the second calcination is preferably 1120-1350 ℃, and is further preferably 1120-1250 ℃; the second calcination time is preferably 0.5 to 3 hours, and more preferably 1 to 2 hours.

After clinker is obtained, the clinker is mixed with water and molded to obtain the primary cementing material.

In the invention, the forming comprises pressing or pouring, and when the forming is pressing, the mass ratio of the clinker to the water is preferably 1 (0.10-0.25), and more preferably 1 (0.13-0.18). In the invention, when the forming is casting, the mass ratio of the clinker to the water is preferably 1 (0.30-0.40).

After the primary cementing material is obtained, the primary cementing material is carbonized and maintained to obtain the magnesium-based cementing material.

Before the carbonization curing, the invention preferably further comprises the step of pre-curing the primary cementing material.

In the invention, the pre-curing preferably comprises room temperature standard curing or carbonization pre-curing; in the invention, the room temperature standard curing temperature is preferably 18-22 ℃, and the room temperature standard curing time is preferably 1 d. In the present invention, the carbonized precured CO is₂The concentration is preferably 20-99%, and more preferably 60-99%; the carbonization pre-curing time is preferably 1 h; the pressure of the carbonization pre-curing is preferably normal pressure.

In the present invention, the CO of the carbonization and curing₂The concentration is preferably 20 to 99%, and more preferably 60 to 99%, the gas pressure for carbonization curing is preferably 0.1-0.4 MPa, and more preferably 0.1-0.3 MPa; the relative humidity of the carbonization and oxidation is 10-99%, and the preferable range is 40-60%; in the invention, the carbonization curing temperature is-20-120 ℃, and the preferable temperature is 10-60 ℃; in the present invention, the carbonization and curing time is preferably 10min to 28d, more preferably 2h to 7d, and most preferably 1d to 5 d.

FIG. 1 is a flow chart of a preparation process of the magnesium-based gel material, which can be obtained from FIG. 1, the magnesium-based gel material is prepared by mixing magnesite and sandstone, and molding the mixture to obtain a molding raw material; calcining the raw material to obtain clinker; mixing the clinker with water, and molding to obtain a primary cementing material; and carbonizing and curing the primary cementing material to obtain the magnesium-based cementing material.

The invention also provides application of the magnesium-based cementing material in building materials.

The following examples are provided to illustrate the magnesium-based gelling material of the present invention and its preparation method and application in detail, but they should not be construed as limiting the scope of the present invention.

Example 1

The compositions of magnesite and sandstone in this example are shown in table 1.

Table 1 composition of magnesite and sandstone as described in example 1

	Ignition loss (%)	CaO(％)	SiO2(％)	Al2O3(％)	Fe2O3(％)	MgO(％)
							Magnesite	46.975	0.89	1.23	2.880	5.75	43.025
Sandstone	6.381	5.366	74.887	8.142	3.406	1.223

The above ignition losses are water, carbon dioxide and other gaseous components that can be lost at 900 c.

Crushing and grinding magnesite and sandstone to obtain magnesite with a median particle size of 100 mu m and sandstone with a median particle size of 150 mu m;

and uniformly mixing 70.6g of the ground magnesite and 29.4g of the sandstone, and granulating the obtained mixture by using a double-roller machine to obtain a forming raw material with the diameter of 20-30 mm.

And (3) performing first calcination on the obtained molding raw material at the temperature of 850 ℃ for 1h, then heating to 1350 ℃ for further calcination for 1h, then sequentially cooling (cooling to room temperature), and grinding to obtain clinker with the particle size D90 being less than 150 μm.

And mixing the obtained 10g of clinker powder and 1.5g of water, pouring the obtained mixture into a mold, and performing compression molding to obtain the primary cementing material.

And curing the obtained primary cementing material for 1h in an environment with the carbon dioxide concentration of 80%, the atmospheric pressure of normal pressure and the relative humidity of 80% and the temperature of 25 ℃, and then demolding.

Carbonizing and curing the obtained demoulding product under the following curing conditions: the concentration of carbon dioxide is 99%, the gas pressure is 0.3MPa, the relative humidity is 50%, the temperature is 25 ℃, and the curing time is 1d, so that the magnesium-based cementing material is obtained.

Example 2

Crushing and grinding magnesite and sandstone to obtain magnesite with a median particle size of 100 mu m and sandstone with a median particle size of 110 mu m;

and uniformly mixing 70.6g of the ground magnesite and 29.4g of the sandstone, and granulating the obtained mixture by using a double-roller machine to obtain a forming raw material with the diameter of 20-30 mm.

And (3) performing first calcination on the obtained molding raw material at the temperature of 850 ℃ for 1h, then heating to 1200 ℃, continuing calcination for 1h, then sequentially cooling (cooling to room temperature), and grinding to obtain clinker with the particle size D90 being less than 150 μm.

And mixing the obtained 10g of clinker powder with 2.5g of water, pouring the obtained mixture into a mold, and performing compression molding to obtain the primary cementing material.

And curing the obtained primary cementing material for 1h in an environment with the carbon dioxide concentration of 80%, the atmospheric pressure of normal pressure and the relative humidity of 80% and the temperature of 25 ℃, and then demolding.

Carbonizing and curing the obtained demoulding product under the following curing conditions: the concentration of carbon dioxide is 99%, the gas pressure is 0.2MPa, the relative humidity is 80%, the temperature is 25 ℃, and the curing time is 1d, so that the magnesium-based cementing material is obtained.

Comparative example 1

The magnesite is put into 1000 ℃ to be calcined to obtain MgO, the magnesium oxide and the magnesium chloride are mixed according to the mass ratio of 7:3, and the mixture and water are mixed according to the water-powder ratio of 1:4 to obtain a mixture.

Pouring the obtained mixture into a mold, curing for 1d in a room-temperature oxygen-labeled environment, demolding, and then putting the product obtained by demolding into the room-temperature oxygen-labeled environment for curing for 28d to obtain the magnesium oxychloride cement product.

The magnesite and sandstone used in the examples and comparative examples of the invention have the following main chemical components: (LOI represents loss on ignition, specifically the sum of water and carbon dioxide):

	LOI(％)	CaO(％)	SiO2(％)	Al2O3(％)	Fe2O3(％)	MgO(％)
							magnesite	46.975	0.89	1.23	2.880	5.75	43.025
Sandstone	6.381	5.366	74.887	8.142	3.406	1.223

The mechanical properties of the examples 1-2 and the comparative examples 1-3 are tested, and the mechanical property testing method comprises the following steps: and pouring the mixture obtained by mixing the clinker and water into a cylindrical mold with the inner diameter of 20mm, and carrying out extrusion molding under the pressure of 30MPa to obtain a cylindrical molded product with the bottom surface diameter of 20mm and the height of 20 +/-0.1 mm. Then, a displacement loading mode (the loading rate is 0.5mm/min) is adopted, an MTS universal mechanical testing machine is used for testing the compressive strength, the test result is shown in table 2, and the magnesium-based cementing material prepared by the method has good compressive strength as can be seen from the table 2.

Table 2 test results of compressive strengths of cement materials prepared in examples 1 to 2 and comparative examples 1 to 3

	Example 1	Example 2	Comparative example 1
				Compressive strength (MPa)	110.23	90.75	51.60

The invention also carries out a water resistance test on the gelled materials prepared in the example 1 and the comparative example 1, and the test method comprises the following steps of soaking the carbonized and cured samples in the example 1 and the comparative example 1 in water for 7d, and then testing the compressive strength of the soaked samples, wherein the compressive strength is tested as follows: the test is carried out by adopting a displacement loading mode (the loading rate is 0.5mm/min) and utilizing an MTS universal mechanical testing machine.

The test result is as follows; the compressive strength of the magnesium-based cement prepared in example 1 was 93.59MPa, and the compressive strength of the cement prepared in comparative example 1 was 22.19 MPa. From the test results, it can be seen that the magnesium-based cement prepared by the present invention has good water resistance.

The corrosion performance of the magnesium-based cementing material prepared in the embodiment 1-2 and the corrosion performance of the cementing material prepared in the comparative example 1-3 on metal are tested, and the test method comprises the following steps: after coating an anti-rust coating on the surface of an iron plate of 100mm x 5mm, scraping the anti-rust coating on the upper surface, uniformly coating the mixture obtained by mixing the clinker and the water obtained in example 1 and the mixture obtained by mixing the clinker and the water obtained in comparative example 1 on one surface on which the anti-rust coating is scraped, and then respectively carrying out maintenance in the manners of example 1 and comparative example 1, wherein the iron plate after maintenance according to example 1 is taken as the iron plate of example 1, and the iron plate after maintenance according to comparative example 1 is taken as the iron plate of comparative example 1.

Fig. 2 and 3 are results of corrosion performance tests of the iron plates of example 1 and comparative example 1, respectively, and it can be seen from fig. 2 and 3 that: the iron plate of example 1 had no rust mark on the surface, and the iron plate of comparative example 1 had significant rust on the surface.

It should be noted that, for those skilled in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be construed as the protection scope of the present invention.